ISSUE 6 – November 2015 POWER ICs · Email: [email protected] Circulation and subscription:...

Coming from high-power semiconductors, ABB is regarded as one of the world’sleading supplier setting world standards in quality and performance. ABB’s uniqueknowledge in high-power semiconductors now expands to industry standardmedium-power IGBT and bipolar (thyristor/diode) modules. ABB is launching the

• 62Pak: a 1,700 volt, 300 ampere, dual IGBT in a 62 mm package • 20Pak, 34Pak, 50Pak and 60Pak: 1,600 - 6,000 volt, 120 - 830

ampere dual thyristor and dual diode modules in 20 - 60 mm packagesDemanding medium-power applications such as low-voltage drives, softstarters, UPS and renewables benefit from ABB’s well-known experience andquality.For more information please contact us or visit our website:www.abb.com/semiconductors

ABB Switzerland Ltd. / ABB s.r.o.www.abb.com/[email protected].: +41 58 586 1419

Medium power modules. Industry icons go quality.

02_pee_0615.indd 1 04/11/2015 09:26

CONTENTS

www.power-mag.com Issue 6 2015 Power Electronics Europe

3

Editor Achim ScharfTel: +49 (0)892865 9794Fax: +49 (0)892800 132Email: [email protected]

Production Editor Chris DavisTel: +44 (0)1732 370340

Financial Manager Clare JacksonTel: +44 (0)1732 370340Fax: +44 (0)1732 360034

Reader/Circulation Enquiries Perception-MPS Ltd.Tel: +44 (0) 1825 749900Email: [email protected]

INTERNATIONAL SALES OFFICESMainland Europe: Victoria Hufmann, Norbert HufmannTel: +49 911 9397 643 Fax: +49 911 9397 6459Email: [email protected]

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Eastern US Karen C Smith-Kerncemail: [email protected] US and CanadaAlan A KerncTel: +1 717 397 7100Fax: +1 717 397 7800email: [email protected]

Italy Ferruccio SilveraTel: +39 022 846 716 Email: [email protected]

Japan:Yoshinori Ikeda, Pacific Business IncTel: 81-(0)3-3661-6138Fax: 81-(0)3-3661-6139Email: [email protected]

TaiwanPrisco Ind. Service Corp.Tel: 886 2 2322 5266 Fax: 886 2 2322 2205

Publisher & UK Sales Ian AtkinsonTel: +44 (0)1732 370340Fax: +44 (0)1732 360034Email: [email protected]

Circulation and subscription: Power ElectronicsEurope is available for the following subscriptioncharges. Power Electronics Europe: annual chargeUK/NI £60, overseas $130, EUR 120; single copiesUK/NI £10, overseas US$32, EUR 25. Contact: DFA Media, 192 The High Street, Tonbridge, Kent TN9 1BE Great Britain. Tel: +44 (0)1732 370340. Fax: +44 (0)1732 360034. Refunds on cancelledsubscriptions will only be provided at the Publisher’sdiscretion, unless specifically guaranteed within theterms of subscription offer.

Editorial information should be sent to The Editor,Power Electronics Europe, PO Box 340131, 80098Munich, Germany.

The contents of Power Electronics Europe aresubject to reproduction in information storage andretrieval systems. All rights reserved. No part of thispublication may be reproduced in any form or by anymeans, electronic or mechanical includingphotocopying, recording or any information storageor retrieval system without the express prior writtenconsent of the publisher.

Printed by: Garnett Dickinson.

ISSN 1748-3530

PAGE 18

Cross Switch XS - Silicon andSilicon Carbide HybridDue to the inherent advantages of wide bandgap (WBG) semiconductor materials

such as Silicon Carbide (SiC) and Gallium Nitride (GaN), WBG based power

devices are fabricated on much thinner and higher doped n-base regions when

compared to silicon. Therefore, in principle they can provide a wide range of

voltage ratings with improved electrical performance in terms of low conduction

losses, very low switching losses and low leakage currents making them suitable

for applications targeting lower losses and higher operational frequencies and

temperatures. Munaf Rahimo, Charalampos Papadopoulos, Francisco

Canales, Renato Amaral Minamisawa, Umamaheswara Vemulapati, ABB

Semiconductors Lenzburg, Switzerland

PAGE 25

New Energy Harvesting ICs Power SensorsSo far various types of sensors were routinely connected by wires to their power

sources. Today it is possible to install reliable, industrial-strength wireless sensors

that can operate for years on a small battery, or even harvest energy from sources

such as light, vibration or temperature gradients. Furthermore, it is also possible to

use a combination of a rechargeable battery and multiple ambient energy sources

too. Moreover, due to intrinsic safety concerns, some rechargeable batteries

cannot be charged by wires but require being charged via wireless power transfer

techniques. Linear Technology has introduced energy harvesting ICs designed to

work with different battery voltages. Tony Armstrong, Director Product

Marketing Power Products, Linear Technology Corp., Milpitas, USA

PAGE 27

Asymmetrical Inductance toSupport Long Cables in Low-Power Motor DrivesHigh capacitive turn-on current often overload IGBTs in low-power inverter

applications that use long shielded cables. A simple workaround can reduce

losses and electromagnetic interference and ensure more reliable performance.

Michael Frisch, Head of Product Marketing, Vincotech,

Unterhaching/Munich, Germany

PAGE 29

The Need for High-FrequencyHigh-Accuracy PowerMeasurementAs more and more innovation focuses on energy efficiency and the use of

renewable energy resources, engineers are increasingly demanding accuracy and

precision from their power measurements. At the same time, new standards such

as IEC62301 Ed2.0 and EN50564:2011, covering standby power consumption,

and the SPEC guidelines, covering power consumption in data centres, demand

more precise and accurate testing to ensure compliance. But these levels of

precision can only be achieved if the measuring instruments are properly

calibrated with reference to national and international standards. Clive Davis,

Marketing Manager T&M and Erik Kroon, Metrology Expert, Yokogawa

T&M Center Europe, Amersfoort, Netherlands

PAGE 32

ProductsProduct update.

PAGE 33

Website Product Locator

Efficiency Revolutionin Auxiliary andStandby PowerSuppliesThe new InnoSwitch TM-EP family of ICs simplify thedevelopment and manufacturing of low-voltage, high-current power supplies, particularly those in compactenclosures or with high efficiency requirements. Itsarchitecture is revolutionary in that the devicesincorporate both primary and secondary controllers,with sense elements and a safety-rated feedbackmechanism into a single IC. It combines a high-voltagepower MOSFET along with both primary-side andsecondary-side controllers in one device. A novelinductive coupling feedback scheme using the packageleadframe and bond wires o provide accurate directsensing of the output voltage and output current onthe secondary to communicate information to theprimary IC. The first application for InnoSwitch ICs wasincreasingly power-hungry smart mobile devices, butauxiliary and standby power in appliances, HVAC,consumer electronics, computing, telecom and datacommunication applications would also gainsubstantial benefits from increased efficiency acrossthe load range. InnoSwitch-EP ICs are an answer toengineers looking to address increasingly demandingTotal Energy Consumption (TEC) regulations frombodies such as ENERGY STAR® and ErP with an easy-to-implement solution that improves power supplyefficiency from standby to full load. For example,InnoSwitch-EP ICs enable a 20 W power supply toachieve 90 % efficiency in a multi-output design, whilereducing no load consumption to less than 30 mW.

Full story on page 22.

Cover image supplied by Power Integrations, USA

COVER STORY

PAGE 6

Market NewsPEE looks at the latest Market News and company

developments

PAGE 11

Industry News

PAGE 14

Research

p03 Contents.qxp_p03 Contents 04/11/2015 11:21

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04_pee_0615.indd 1 04/11/2015 09:37

OPINION 5


Around two years ago Google and the IEEE initiatedthe “Little Box Challenge”, a contest addressingpower electronic developers to design the smallestand most efficient inverter. The grand prize ($1million) winner will be announced sometime inJanuary, 2016. Inverters will become increasinglyimportant to our economy and environment as solarPV, batteries, and similar power sources continuetheir rapid growth. More broadly, similar forms ofpower electronics are everywhere: in laptops,phones, motors drives, electric vehicles, windturbines, to give just a few examples. The innovationsinspired by this prize will have wide applicabilityacross these areas, increasing efficiency, drivingdown costs, and opening up new uses cases that wecan’t imagine today. It also doesn’t hurt that many ofthese improvements could make data centers runmore safely and efficiently. By July, over 100 teamssubmitted Technical Approach and TestingApplications to have their inverters tested at theNational Renewable Energy Laboratory’s EnergySystems Integration Facility in Golden, Colorado thisfall. Out of this number 18 finalists have beenselected – with impressing European contribution.

One promising set of new technologies whichmay allow for the achievement of higher powerdensities are wide bandgap (WBG) semiconductors,such as Gallium Nitride (GaN) and Silicon Carbide(SiC). The list of WBG device manufacturers whohave made pages describing their technology, how itmight enable contestants to win the competition andopportunities for obtaining some of their devicescontains EPC, GaN Systems, GeneSiC, Infineon,Monolith Semiconductors, NXP, ROHM, ST,Transphorm, USCi, and Wolfspeed (formerly Cree).The GaN devices market is expected to explode,announced Yole in its technology and marketanalysis entitled “GaN & SiC for power electronicsapplications”. Under this report Yole proposes twoscenarios, from 2014 to 2020, based on thepenetration rate of GaN: The differentiating factor,compared with the Silicon Carbide solutions’adoption, is mainly focused on below 200 V and600 V applications, but after the adoption phase ofthe Wide Band Gap technologies, how will GaN andSiC technologies cohabite? Will they enter in directcompetition or become complementarytechnologies? In the nominal scenario, Yole estimates

the GaN device market size will be around $300million in 2020, but in the accelerated scenario,where low voltage GaN and 600 V GaN are rapidlyadopted, market figure for 2020 reaches $560million.

The overall power semiconductor market,including both power discretes and power modules,is predicted by IHS to grow 5 % in 2015 to reach$17 billion. In 2014, year-over-year power discreterevenue grew 5 % and power module revenue grew12 %. The global power module market is projectedto comprise nearly one third (30 %) of the powersemiconductor market by 2019, growing at twice therate of power discretes from 2014 to 2019. Infineoncontinued to be the largest supplier for the globalpower semiconductor market in 2014, with anestimated market share of 13 %. With theacquisition of International Rectifier by Infineon lastyear, the market landscape for powersemiconductors is changing. The merged companiesheld almost 27 % of the power transistor market in2014. The transistor product category includesbipolar transistors, MOSFETs, and IGBTs, accountingfor about two thirds of the total discrete powersemiconductor market.

From the technology side first, the power moduleis becoming a key part in the power electronics valuechain. And this evolution is directly impacting thesupply chain with many new entrants willing tocapture the power module added-value. At thegeographic level then, Chinese companies areentering the IGBT devices market with their owndisruptive technologies or with the acquisition of diemanufacturers. With this strategy, Chinese playerscompete established companies mostly based inEurope and Japan. Under this context, the Japanesecompanies are expected by Yole to still dominate themarket. But this industry will be progressivelyreshaping with the entrance of new players at thepower module level. Most IGBT manufacturers havebeen involved in the field for decades. Relationshipsare deep-rooted between tiers and users, andbusiness models are already drawn. However,evolutions are occurring: with the electrified vehiclemarket’s growth, the power module is becoming akey piece of the value chain and an important stepto master. Modules integrating embedded dies arebeginning to enter the market via areas likephotovoltaics and automotive. Big players are alsopursuing mergers and acquisitions in order to quicklyacquire this know-how. In parallel, Chinesecompanies are entering the market to compete withEuropean and Japanese leaders. In 2014, as in2013, Chinese market represented around 1/3 ofthe global IGBT devices market. According to Yole’sIGBT analysis, many Chinese companies are involvedin module manufacturing and buy the dies fromforeign companies for integration. However, anincreasing number of Chinese companies try to enterthe die manufacturing market. To answer Chinesecompetition, Japanese and European players rely notonly on their experience and product quality, but alsoon a strong in-house market. With an overall marketfueled by electrified vehicles, these establishedplayers can benefit from a strong local supply chainin automotive, and look forward to attractive futuregrowth.

With that outlook we wish all our readers asuccessful remaining year 2015 and a good jumpinto 2016!

Achim ScharfPEE Editor

Power Electronics in Contest

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05_PEE_0615_NEW.qxp_p05 Opinion 04/11/2015 09:40

6 MARKET NEWS

Issue 6 2015 Power Electronics Europe www.power-mag.com

We invented the Manganin® resistance alloy 125 years ago. To this day, we produce the Manganin® used in our resistors by ourselves.

More than 20 years ago, we patented the use of electron-beam welding for the production of resistors, laying the foundation for the ISA-WELD® manufacturing technology (composite material of Cu-MANGANIN®-Cu). We were the first to use this method to manufacture resistors. And for a long time, we were the only ones, too.

Today, we have a wealth of expertise based on countless pro-jects on behalf of our customers. The automotive industry’s high standards were the driving force behind the continuous advancement of our BVx resistors. For years, we have also been leveraging this experience to develop successful indus-trial applications.

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Innovation by Tradition

“The IGBT devices industry is aboutto change” announces YoleDéveloppement (Yole) in its latestpower electronics report, entitled“IGBT Market and TechnologyTrends”.From the technology side first, the

power module is becoming a keypart in the power electronics value

chain. And this evolution is directlyimpacting the supply chain withmany new entrants willing tocapture the power module added-value. At the geographic level then,Chinese companies are entering theIGBT devices market with their owndisruptive technologies or with theacquisition of die manufacturers.

With this strategy, Chinese playerscompete established companiesmostly based in Europe and Japan.Under this context, the Japanesecompanies are still dominating themarket, even with InternationalRectifier’s acquisition by InfineonTechnologies beginning of 2015.“The IGBT supply-chain is well-

established”, confirms Coralie LeBret, analyst at Yole. “But we stayconvinced this industry will beprogressively reshaping with theentrance of new players at thepower module level”, she adds.Indeed most IGBT manufacturershave been involved in the field fordecades. Relationships are deep-rooted between tiers and users, andbusiness models are already drawn.However, evolutions are occurring:with the electrified vehicle market’sgrowth, the power module isbecoming a key piece of the valuechain and an important step tomaster.More and more companies are

choosing to enter the power modulemarket in order to capture thisadded value. Under its report, Yoleidentified lot of companies such asNissan, Toyota and InternationalRectifier, still in the power modulearea even after its acquisition byInfineon Technologies.However, many challenges must

be faced by companies at thepackaging level, such as yieldincrease, failure issue reduction,manufacturing ease, and costcompetitiveness. To achieve thesetargets, new designs and newmaterials can be used, either toeliminate connection levels orimprove interfaces. New solutionsinspired by big-volume markets likesmartphones are being adapted tohigher power needs: for example,modules integrating embedded diesare beginning to enter the marketvia areas like photovoltaics andautomotive. Big players are alsopursuing mergers and acquisitions inorder to quickly acquire this know-how. In parallel, Chinese companies

are entering the market to competewith European and Japaneseleaders. In 2014, as in 2013,Chinese market represented around1/3 of the global IGBT devicesmarket. According to Yole’s IGBTanalysis, many Chinese companiesare involved in modulemanufacturing and buy the diesfrom foreign companies forintegration. However, Yole’s analystssee an increasing number ofChinese companies trying to enterthe die manufacturing market. Someare developing their owntechnology. Yole identified for

Chinese Challange in IGBTs

Market News.qxp_Layout 1 04/11/2015 10:21

MARKET NEWS 7


example, MacMic, BYD. Othercompanies are choosing to acquiredie manufacturers. Regardless oftheir preferred tactic, every companyunderstands that developing areputation for good quality is key inorder to first enter their local market,and then compete with establishedIGBT manufacturers.Yole’s analysis highlight the role of

the Chinese companies in the IGBTdevices market and propose acomprehensive presentation ofChinese players split between powermodule makers and IGBT diemakers, along with an associatedpower range. n terms of marketshare, Japanese companies still lead,even in light of the recent mergerbetween International Rectifier andInfineon. To answer Chinesecompetition, Japanese andEuropean players rely not only ontheir experience and product quality,but also on a strong in-housemarket. With an overall marketfueled by electrified vehicles, theseestablished players can benefit froma strong local supply chain inautomotive, and look forward toattractive future growth.

Additionally Gallium Nitride (GaN)devices market is expected toexplode, announced Yole in itstechnology and market analysisentitled “GaN & SiC for powerelectronics applications”. Under thisreport Yole proposes two scenarios,from 2014 to 2020, based on thepenetration rate of GaN: Thedifferentiating factor, compared withthe Silicon Carbide (SiC) solutions’adoption, is mainly focused onbelow 200V and 600V applications,but after the adoption phase of theWide Band Gap (WBG)technologies, how will GaN and SiCtechnologies cohabite? Will theyenter in direct competition orbecome complementarytechnologies? “In the nominalscenario, we estimate the GaNdevice market size will be around$300 million in 2020,” expectsHong Lin, Technology & MarketAnalyst at Yole. “In the acceleratedscenario, where low voltage GaNand 600 V GaN are rapidly adopted,market figure for 2020 reaches$560 million”.

www.yole.fr

Don’t let currentmeasurementcheckmate your

SPS/IPC/

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According to market researcher IHS the global power module market isprojected to comprise nearly one third (30 %) of the power semiconductormarket by 2019, growing at twice the rate of power discretes from 2014 to2019. The overall power semiconductor market, including both powerdiscretes and power modules, is predicted to grow 5 % in 2015 to reach $17billion. In 2014, year-over-year power discrete revenue grew 5 % and powermodule revenue grew 12 %.Power modules contain multiple discrete power semiconductor devices.

Compared to discrete power semiconductors, power module packagesprovide higher power density and more reliability. “OEMs will continue to want

Power ModulesOutperformDiscretes


8 MARKET NEWS


modular power solutions, which can be integrated easily into varioussubsystems and used in many different devices,” said Richard Eden,semiconductor senior analyst IHS Technology. “Power modules are widelyfound in inverters for wind converters, photovoltaic solar energy systems andother renewable energy applications. They are also found in industrial motordrives and hybrid and electric vehicles. Standardized discrete powersemiconductors have become commoditized with little differentiation. OEMsand ODMs typically multisource discrete products through distributors.Suppliers will continue to face challenges, when it comes to increasing profit incommodity segments of the power discrete market.”

Infineon continued to be the largest supplier for the global powersemiconductor market in 2014, with an estimated market share of 13 %.With the acquisition of International Rectifier (IR) by Infineon last year, themarket landscape for power semiconductors is changing. The merged

Yokogawa Europe has in October 2015 inAmersfoort/Netherlands introduced the world’sfirst non-governmental ISO17025 accreditatedlab for power measurements up to 100 kHz.Only four national institutes so far cover thisfrequency range. This is in addition to itsestablished capability for providing high-accuracy calibration at 50 Hz, especially at verylow power factors (down to 0.0001) and athigh currents and its efforts starting in 1991 forinternal ISO9001 accreditation. “Due to more inverterized power systems

such as drives or solar inverters, particularlywith the growing focus on renewable energymarkets and the need to optimize energyefficiency while complying with internationalstandards on power quality, especially at lowpower factors, there is a growing demand forcalibrated power mesurement and test system.In addition, the inverters used in renewableenergy systems are switching at higher speeds:a scenario that introduces harmonics at higherfrequencies”, commented Erik Kroon,Yokogawa’s Metrology Expert. Thus power measurements have to be

correct to meet the exacting requirements ofmodern design. Their power meters need tobe calibrated at the frequencies present intheir specific application and not just at 50Hz. However good the calibration result at 50Hz, it does not say anything about high-frequency performance. Frequency is just onefactor being addressed in the calibration ofpower meters. Whereas in the past it wassufficient to list voltage and currentmeasurements in a power meter’s data sheet,today’s power environment needs to addressvariables such as phase shift, power factorand the effects of distorted waveforms –which today are included in the instrumentspecifications. Calibration of instruments delivered to

customers is done mostly over night in an

automated process. The calibration lab itselfis located in a temperature/humiditystabilized room, where the masterinstruments run 24 h/7 d without switchingoff. Low-current measurements (up to 20 A)are provided via highly accurate (ppmtolerance rage) in-house made shunts,whereas higher currents are measured via in-house made current transducers (high-

permeability cores, special winding). Regarding instruments, in the efficiency

validation stage of inverters for instance, thekey factors that need to be tested are poweranalysis, conversion efficiency, harmonics, andin automotive applications perhaps the batterycharge and discharge process. For tests of thistype, the instrument of choice is the poweranalyser, offering high precision, high accuracy,

Yokogawa Offer Accredited PowerCalibration Up to 100 kHz

companies held almost 27 % of the power transistor market in 2014. Thetransistor product category includes bipolar transistors, MOSFETs, and IGBTs,accounting for about two thirds of the total discrete power semiconductormarket. Mitsubishi ranked second, at 7 %. STMicrosystems moved up to thethird market position, displacing Toshiba, with an estimated market share of 6 %.

Mitsubishi Electric was the largest supplier for power modules in 2014,although the company’s estimated share of the market remained at 24 % for2013 and 2014. Infineon maintained the second-ranked position at 20 %.The top four power module suppliers – Mitsubishi, Infineon, Semikron andFuji Electric – accounted for 65 % of the global power module market in2014.

www.ihs.com

Yokogawa’s Metrology Expert Erik Kroon showing high-accuracy shunt in front of master power calibration system Photo: AS


MARKET NEWS 9


Do you usethe best tools?

Design engineers in more than 50 countries worldwide trust in the Vector Network Analyzer Bode 100 when great usability, high accuracy and unbeatable price-performance ratio are needed.

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high stability, and the ability to carry outcalibrated measurements. Yokogawa’sWT3000E Power Analyzer offers 0.01% ofreading + 0.03% of range. It is theenhanced version of the industry standardWT3000. Along with high accuracy itprovides a broad bandwidth of DC, and0.1Hz to 1 MHz. The high measurementaccuracy will provide engineers with the testdata needed to evaluate powerconsumption and energy loss moreprecisely.

In addition to the dedicated instruments,engineers and R&D professionals are alsolooking for hybrid instruments that can beused at all stages of the development cycle.When the power consumed by the loadvaries at start-up of a motor, it may benecessary to measure power at muchshorter intervals. A specific requirement isthe time-based measurement functionalityof an oscilloscope combined with theaccuracy of a power analyzer. Such precisionpower scopes offer flexibility, accuracy andwide bandwidth, allowing for drawing therange of power readings needed to

optimize the efficiency of boost-circuits andinverters. Yokogawa’s PX8000 Power Scopebrings transient analysis and high time-based accuracy to electrical powermeasurements. Its combination of accuratepower measurements over precise timeintervals is vital for analyzing energy lossand efficiency in high speed switchingdevices.

In addition to wide-band and highaccurate power-meter calibration systems,the state-of-the-art calibration laboratoryalso includes systems for calibratingoscilloscopes, recorders and opticalproducts, and is therefore capable ofcalibrating a wide range of instruments inthe test & measurement industry. “Futurerequirements due to even higher switchingfrequencies of SiC and GaN power stages insolar inverters of power power supplies willbe covered step-by-step”, Kroon said. Moretechnical details in our feature ‘The Need forHigh-Frequency High-Accuracy PowerMeasurement’. AS

www.tmi.yokogawa.com/ea/

Knowles announced that the new Capacitorfacility in Suzhou, China is fully operational.This completes the relocation of MultilayerCeramic Capacitor (MLCC) manufacturing fromplants in the UK and Mexico.

Located in the Xiangcheng Economic

Development Area in Suzhou, the factory has10,000 m? of floor space. This reflects asignificant investment in expanded capacity andprovides space to grow the business. Thefacility makes a broad range of MLCC productsincluding standard, high voltage, high Q and

Moving CapacitorProduction to China


10 MARKET NEWS

application specific capacitors, as well as surfacemount and feedthrough EMI filters. The Capacitordivision of Knowles is the consolidation ofDielectric Laboratories (DLI), Novacap, SyferTechnology and Voltronics into a singleorganization with a combined history exceeding175 years. Whilst the production facility is fully ‘upand running’ the original R & D operations in

Norwich and North America continues to makestrides in the development of single and multilayercapacitors. Notable achievements over the lastdecade being ‘FlexiCap™’, used in safety-criticalenvironments, winning the UK Queens Award forEnterprise and more recently ProtectiCap™ andStackiCap™ product lines. “The completion of ournew factory is a great achievement for the

Knowles Capacitor business. It is the result of a lotof hard work, a big investment in time and money,and gives us a facility that we can use as afoundation to grow our business”, remarked DaveWightman, President of Knowles CapacitorDivision.

www.knowlescapacitors.com

The SEMIKRON Innovation Award and the Young Engineer Award whichhave been initiated and are donated by the SEMIKRON Foundation aregiven for outstanding innovations in projects, prototypes, services ornovel concepts in the field of power electronics in Europe, combinedwith notable societal benefits in form of supporting environmentalprotection and sustainability by improving energy efficiency andconservation of resources. SEMIKRON Foundation is awarding theprizes in cooperation with the European ECPE Network.

With the awards the SEMIKRON Foundation wants to motivatepeople of all ages and organizations of any legal status to deal withinnovations in power electronics, a key technology of the 21th century,in order to improve environmental protection and sustainability byenergy efficiency and conservation of resources. The SEMIKRONInnovation (EUR 10.000,00) and Young Engineer Prizes (EUR 3.000,00)

will be awarded in the frame of the ECPE Annual Event in March 2016in Nuremberg. A single person or a team of researchers can beawarded.

The selection procedure for the prize winners is organized incooperation with ECPE European Center for Power Electronics e.V.. Thesubmitted proposals will be passed to an independent and neutralevaluation committee of experts for discussion and assessment. Toapply for the SEMIKRON Awards own applications as well as proposalsfrom third parties are welcomed.

Deadline for submission is 10.01.2016. The receipt of proposals willbe confirmed by email.

Proposals resp. applications with the reference �SEMIKRONInnovation Award� should be sent by email to Thomas Harder, GeneralManager of ECPE e.V., [email protected].

SEMIKRON Awards Power Electronics Engineers


INDUSTRY NEWS 11


The design of power electronics modules andpower packages is heavily influenced by thermalconcerns. New substrate materials, thinner andthermally more conductive attachment materialsare used to decrease the thermal resistance of agiven module. When a new material or technologyis applied, its reliability has to be tested thoroughlybefore the module can be considered forproduction.

The two commonly used lifetime tests forpower modules are Temperature Cycling andActive Power Cycling. Both test methods introducea thermal load by periodically changing the devicetemperature, but are fundamentally different.

Accelerated testing strategiesIn Temperature Cycling the device is unpowered.Temperature change is achieved by placing thepart in a thermostatically-controlled environmentsuch as an oven, which both heats and cools thepart. Hence the heating is externally applied. The

Field Lifetime Estimation ofPower Modules using ActivePower Cycling

heating and cooling rates are relatively slow, of theorder of several minutes, so the temperaturewithin the part remains fairly uniform as it heatsand cools. Temperature Cycling is mainly used toevaluate solder joints between the Direct BondedCopper (DBC) substrate and the module’sbaseplate.

By contrast, in Active Power Cycling the part isheated internally, by passing current through thesemiconductor device, thereby using it as adissipating element. Heat is dissipated at the samelocation heat is dissipated during normal operation,resulting in a temperature distribution within thepart that is similar to the application. As the heatingis localized, significant temperature gradients result.These can be controlled by changing the rate ofheating by changing the supplied current.

By using a low current and long heating andcooling times, Active Power Cycling can also beused to heat the solder joints between the DBCand module baseplate. Normally, Active Power

Cycling uses shorter cycle times with heating timesof just a few seconds. High currents are used toelevate the chip junction temperature in order tostress the bond wires and die attach solder joint.Hence the long term reliability of a package can becomprehensively investigated using Active PowerCycling. As temperature variations within thethermal structure trigger the various types ofdegradation, the effect on electrical parameterssuch as collector-emitter (drain-source) voltagedrop or gate leakage current can be observed ateach cycle. Degradation in the thermal stack canalso be monitored by performing transient thermaltesting periodically. The combination of the twoallows to fully assess the evolution of the variousinterrelated damage mechanisms within a module.

Determining the thermal loadThe most frequent cause of failure of a powermodule is the cracking or delamination of differentlayers due to the thermally-induced stresses thatarise from periodic cycling. The magnitude of thethermal stress is proportional to the temperaturechange induced by the power dissipated by thesemiconductor devices. Consequently the nextstep is to turn the P(t) mission profile into atemperature vs. time function. As the dissipation isnot constant, but rather a complex time function,the temperature function cannot be analyticallycalculated either. Most modern 3D thermalsimulators can do transient simulations, and thereare some that can handle arbitrary dissipationprofiles as well. Even in case of quite complexpackage structures a detailed 3D model can bebuilt.

Before the simulation model can be used tosupport reliability studies it needs to be calibratedso the transient behavior exactly matches withexperimental results. The importance of accurate

Detailed ThermalModel of IGBT inMentor’sFloTHERM XT

StructureFunctions forIGBT beforeand aftermodelcalibration

Industry News.qxp_Layout 1 04/11/2015 10:43

12 INDUSTRY NEWS


control of parameters affecting the lifetime duringthe experiment should not be underestimated. Intests on identical IGBT samples the junctiontemperature change was increased from 110°C to120°C (a 9 % increase), the lifetime wasshortened from ~57500 cycles to ~39000 cycles(a ~37% decrease).As the lifetime is highly dependent on the

junction temperature swing, it follows that thesimulation model must be able to predict thejunction temperature swing resulting from the loadprofile P(t) with high accuracy if it is to be used forlifetime prediction. A significant challenge whenbuilding high-fidelity thermal models of chippackages is ensuring that the models incorporatethe correct thermal properties for the materials ofconstruction and thicknesses of bond lines andsoldered interfaces, such as the die attach layer. Asa result, the simulated thermal response to apower step will be different to that observed inpractice.Precise calibration of the model requires highly

accurate test data, having a high resolution in bothtemperature and time, makes it possible to convertthe temperature time response into a StructureFunction, showing the cumulative thermalcapacitance vs resistance along the heat flow path. A comparison shows the thermal response of

an IGBT modeled in FloTHERM with the physicalpart measured with Mentor Graphics’ T3Sterthermal characterization hardware (see also “1500A Power Tester”, PEE 4/2014, pages 22 – 24),T3Ster, as the model is initially set up (left) andafter calibration (right). It is important that all partsof the curves match with high accuracy to ensurethat all time constants along the heat flow pathwithin the package are correct, ensuring the correcttemperature rise is predicted irrespective of thelength of the applied heat pulse.

Developing failure modelsThere are number of models that take intoaccount many more parameters, but the base ofall these models is the well-known Arrheniusmodel that was primarily elaborated to describechemical reaction rates:

(1)

where Ea is the activation energy, kb is theBoltzmann constant, and T is the absolutetemperature. This equation only takes into accountthe mean temperature. In order to take intoaccount the empirical fact that the larger thetemperature swing is, the shorter the lifetime willbe, a �Tj term can be added yielding the thermo-mechanical stress model:

(2)

where �Tj is the junction temperature change, andA and � are coefficients that are calculated usingcurve fitting.Despite the fact that this model can give a fair

approximation to the failure rate, it is also knownthat the cycle time also affects the lifetime. The

same junction temperature change can beachieved either with a short high-power heatingpulse, or a longer lower power heating pulse, butthe choice influences the lifetime. If the heatingpower is high, some features in the package donot have enough time to heat up during this shorttime. Shorter heating pulses primarily stress thechip itself, the die-attach and the wire bonds. If theheating power is lower, requiring a longer heatingtime to achieve the same temperature change, theheat can spread further down into the DBCsubstrate and base plate, so the change in thetemperature distribution within the package isquite different, despite both producing the samejunction temperature swing. Longer pulsestherefore stress solderlayers further way from the junction. To account

for this, a further term, f� is added to the aboveformula resulting in the Norris-Landzberg model

(3)

where f is the cycle time and � is anothercoefficient calculated using curve fitting. A similarmodel is reported to be used by some companiesmanufacturing power modules, e.g. in one of theirapplication notes, Infineon (Application Note AN2010-02, 2010) published a calculation in whichthey are using a similar expression for lifetimemodeling, with the slight difference being that theytake into account only the heating time rather thanthe whole cycle period. There are also morecomplex models available in the literature, thattake into account even more parameters (e.g.electrical load conditions: current and voltage),however those cannot increase the accuracy of theprediction, because these parameters are notregulated in the same way during operation asthey can be during reliability testing.In the previous section it was shown how the

lifetime of a device can be modeled based on theexperimental power cycling results, but theresulting Nf lifetime only predicts the devicelifetime at a certain constant load (at which it wascalculated).To calculate the expected total lifetime of the

device, taking account of the variable load causedby the selected mission profile, the overall effect ofthe different load conditions has to be estimated.A commonly-used equation to sum the agingeffects from different loads that arise in parallel isthe following

(4)

where Nf_sum is the number of times the loadcorresponding to the mission profile can beapplied to the device until it is expected to fail, andthe wi are the weight factors calculated from thehistogram.Finally, if this aggregated cycle number Nf_sum by

the duration of the mission profile is multiplied,the operation lifetime can be calculated

toperation = Nf_sum x tcycle (5)

ConclusionMission profile based power module design isbecoming the state-of-the-art design method inthe power electronics industry. To get an accurateprediction of the lifetime of a thermal system, anumber of parameters have to be known, such asthe mission profile, the mechanical properties ofthe system and the reliability characteristics of thepower modules used. The accurate definition ofthese parameters, combined with calibration of thethermal model, allows the proper calculation of thetemperature changes in the power device’sjunction using numerical methods. Thisinformation can then be combined with the data inthe lifetime curves to give a fair lifetime prediction.Predicting the lifetime of a system based on agiven mission profile may give power moduledesigners greater confidence in their time-to-failureestimates, supporting new product introductions,and cost reduction efforts efforts, and opening upnew applications and cooling solutions (see also‘Reliability of IGBT Modules Tested’ in PEE2/2015).

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Industry News.qxp_Layout 1 04/11/2015 10:43

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14 RESEARCH


Contest for Highest Power Density and EfficiencyThe Little Box Challenge is a design contest presented by Google and the IEEEPower Electronics Society to spur innovation in power inverter design with thehighest power density (at least 50 Watts per cubic inch) with a $1,000,000prize. The inverter must demonstrate an efficiency of >95 percent.

In parallel with the Little Box Challenge, Google Research is solicitingproposals for groundbreaking research in the area of increasing the powerdensity for DC/AC power conversion. This funding opportunity is available onlyto academics who are full time faculty at degree granting Universities. It isenvisioned that award recipients could use their grant funding to assist inbuilding a device that could win the competition. Applying for or receiving anaward will not affect an entrant’s chances of winning the grand prize.

Why little box?Google believes that inverters will become increasingly important to economyand environment as solar PV, batteries, and similar power sources continuetheir rapid growth. More broadly, similar forms of power electronics areeverywhere: in laptops, phones, motors drives, electric vehicles, wind turbines,to give just a few examples. The innovations inspired by this prize will havewide applicability across these areas, increasing efficiency, driving down costs,and opening up new uses cases that we can’t imagine today. It also doesn’thurt that many of these improvements could make data centers run moresafely and efficiently.

Up to 18 finalists will be notified of their selection for final testing at thetesting facility. They are required to bring their inverters in person to a testingfacility in United States by October 21, 2015. The grand prize winner will beannounced sometime in January, 2016.

Google and the IEEE Power Electronics Society have announced that theNational Renewable Energy Laboratory (NREL) in Golden, Colorado, USA will

be the testing facility for the competition. Up to 18 finalist teams will be invitedto bring their inverters for extended testing (up to approximately 100 hours) atNREL’s Energy Systems Integration Facility (ESIF) using state of the artequipment and supervised by world-class technical staff. The results will helpensure that the best entry wins. Over 100 teams submitted a TechnicalApproach and Testing Applications to have their inverters tested. The 18finalists are !verter (Germany/Switzerland), Adiabatic Logic (UK), AHED(Germany), AMR (Argentina), Cambridge Active Magnetics (UK), Energylayer(Ukraine), Fraunhofer IISB (Germany), Future Energy Electronics Center (USA),Helios (USA), LBC1 (Slovakia), OKE-Services (Netherlands), Red ElectricalDevils (Belgium), Rompower (USA/Romania), Schneider Electric Team(France), The University of Tennessee (USA), Tommasi – Bailly (France), UIUCPilawa Group (USA), and Venderbosch (Netherlands). Thus European teamsare very well represented.

One promising set of new technologies which may allow for theachievement of higher power densities are wide bandgap (WBG)semiconductors, such as Gallium Nitride (GaN) and Silicon Carbide (SiC). Thelist of WBG device manufacturers who have made pages describing theirtechnology, how it might enable contestants to win the competition andopportunities for obtaining some of their devices contains EPC, GaN Systems,GeneSiC, Infineon, Monolith Semiconductors, NXP, ROHM, ST, Transphorm,USCi, and Wolfspeed (formerly Cree).

Inverter specificationsThe inverter must be contained within a rectangular metal enclosure with avolume of less than 40 in3. Each face of the enclosure should be flat, sinceany bulging on a face will result in an increased assessment of the relevantdimension of height width or depth. The maximum dimension may not

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Research.qxp_Layout 1 04/11/2015 10:31

RESEARCH 15

Testing application - LBS technical specification sheet

exceed 20 inches and the minimum dimension may not be less than 0.5inches. The inverter will be tested using a near ideal voltage supply set at 450 V. This

power supply will be floating. Its positive terminal will be connected to a 10 Ωwire wound resistor which in turn will be connected to the positive DC inputterminal of the inverter. The voltage source will be very close to ripple free. Thevoltage output must be 240 V RMS single phase AC, within a +/ 12 V band.After a transient change in the load the voltage should return to withinacceptable bands in 1 second or less and not leave the band again until thenext load change. The voltage will be measured at the output of the inverter toensure it remains within acceptable bands. Unintentional DC voltage must notbe more than 1.2 V present between the 2 AC terminals. The frequencyoutput must be 60 Hz single phase AC, within a band between 59.7 to 60.3 Hz. The amount of heat generated by the system will decrease as the efficiency

of the system increases, but even at the required efficiency of >95 % at fullload a 2 kVA inverter can generate up to 100 W of heat which must bedissipated in order to prevent an unacceptable temperature rise. The higherthe power density of the inverter, the less surface area is available for this heatto be dissipated across. The local thermal management requirements in thesystem may be relaxed by using devices (e.g. wide bandgap semiconductors)that can operate reliably at elevated temperatures. New passive or activethermal management approaches may be used to manage the heat that doesget generated and distribute it evenly across the surface area of the enclosureto avoid the presence of hot spots above 60°C. The technical approachdocument must describe what innovations in thermal management are beingused to achieve the required specifications at these high power densities. The inverter will be tested under dynamic load conditions. The load will be

provided by an electronic load bank which can switch in and out a series oflinear, resistive, inductive and capacitive loads in parallel in small (< 50 VA)increments. The maximum load will be 2 kVA. The power factors will vary

between 0.7 and 1, leading and lagging. The load change profile will be similarto that seen in a residential setting, although only using linear loads. The load can vary between 0 and 2 kVA with individual load jumps as high

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16 RESEARCH


Researchers at the Fraunhofer Institute for Solar Energy Systems ISE havedeveloped a highly compact and efficient inverter for use in uninterruptiblepower supplies (UPS) for electrical devices. The demonstrator, which containsinnovative silicon carbide components, was developed in cooperation with anindustry partner and achieved an efficiency of 98.7 %. The research anddevelopment findings can be applied to other areas of electronic powerconversion in which weight and efficiency play a key role, e. g. electric mobilityor portable power supply.UPS inverters ensure that electrical devices continue to be supplied with

power during disruptions to the power grid. In combination with a battery, theyallow electrical power outages of varying lengths to be bypassed. Forparticularly critical loads, such as computer centers, online UPSs offer thehighest protection as they are connected between the grid and the load andare thus able to compensate for any disruptions stemming from the grid. Thisdoes mean, however, that all energy is transferred via the UPS inverter evenduring periods of disruption-free operation. Efficiency therefore plays a veryimportant role for this application, as it is closely connected with the costsrequired to operate the UPS. This context provided the starting point for theFraunhofer ISE project, which has now been successfully completed.

Compact and highly efficientUsing silicon carbide (SiC) transistors, scientists were able to showcase a UPSinverter with an output of 10 kW and a volume of just five liters. Despite itshighly compact design, the inverter still achieved a very high efficiency. Thegood dynamic and static properties of the SiC transistors, such as on-stateresistance and switching loss, permit a switching frequency of 100 kHz. This isaround five times higher than that of conventional power electronic Siliconcomponents, yet does not significantly increase losses in the semiconductors.Thanks to the high switching frequency, the passive elements in the system,such as inductors and capacitors, could also be reduced in size, while the lowlosses in the semiconductors permitted the implementation of a compact

cooling system for the transistors. “On the whole, this design saves system-related costs and materials. In comparison to using a conventional switchingrate of 16 kHz, we were able to reduce the size and price of the maininductance in our UPS inverter by around two thirds,” says CorneliusArmbruster, development engineer at ISE. For applications in online UPS systems, efficiency is even more important

than reducing materials, as it not only compensates short-term voltage dipsin the grid, but also ensures that electrical devices are continuouslysupplied with power via the UPS. The annual energy demand of a smallserver room with a typical capacity utilization amounting to half of the ratedpower of the UPS system is around 44,000 kWh. Depending on theefficiency of the UPS inverter, the energy demand increases to cover thelosses that occur in the inverter, thus explaining the considerable impactthat UPS inverter efficiency has on operating costs in the form of electricitycosts. In comparison to a conventional system with an efficiency of around97.4 %, the newly developed demonstrator (98.7 %) can reduce annualcosts by around 40 %.

Material with prospectsThe Fraunhofer Institute for Solar Energy Systems ISE has been researchingand developing highly efficient power electronics for renewable energysystems and the application of the latest components made from GalliumNitride and Silicon Carbide. The technology demonstrator showcased, whichwas commissioned by ROHM Semiconductor, once again highlights thepotential of these semiconductor materials. The SiC transistors used in thedemonstrator were provided by ROHM Semiconductor. “Thanks to thissemiconductor material, transistors will be available for even higher currents inthe future, allowing systems to achieve considerably higher output powers”,Armbruster stated.

www.ise.fraunhofer.de/en

Silicon Carbide Components Enable Efficiency of 98.7 Percent

Fraunhofer ISE developed a three-phase 10 kW UPS inverter with avolume of just five liters and anefficiency of 98.7 percent


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18 POWER SEMICONDUCTORS www.abb.com/semiconductors


Cross Switch XS - Silicon andSilicon Carbide HybridDue to the inherent advantages of wide bandgap (WBG) semiconductor materials such as Silicon Carbide(SiC) and Gallium Nitride (GaN), WBG based power devices are fabricated on much thinner and higherdoped n-base regions when compared to silicon. Therefore, in principle they can provide a wide range ofvoltage ratings with improved electrical performance in terms of low conduction losses, very low switchinglosses and low leakage currents making them suitable for applications targeting lower losses and higheroperational frequencies and temperatures. Munaf Rahimo, Charalampos Papadopoulos, FranciscoCanales, Renato Amaral Minamisawa, Umamaheswara Vemulapati, ABB SemiconductorsLenzburg, Switzerland

For high power applications inparticular, SiC based power devices are thepreferred choice today for exhibitingrelatively high current ratings due to thevertical structure such devices are basedon. Whereas Silicon based unipolar powerdevices such as MOSFETs and SchottkyBarrier Diodes (SBD) do not exceed 1200V with respect to the voltage blockingcapability, unipolar SiC devices on theother hand can extend this range to wellbeyond 6.5 kV.

In this particular voltage range, the SiCMOSFET and SBD are destined tocompete with today`s popular Si IGBT anddiode solutions for a wide range of powerelectronics circuits. In addition to theabove-mentioned advantages, SiCMOSFET also provides very low losses atlow currents compared to the Silicon IGBThaving an inherent pn-junction barrierpotential of around 0.7 V. Therefore, formany applications where losses are takeninto account for the full current range (i. e.sub-load conditions), the SiC MOSFETbecomes an attractive prospect.Nevertheless, many challenges need to beovercome for permitting the widespreademployment of SiC based devices inmainstream power electronics systems.One major obstacle is the significantlyhigher cost associated with SiC devices, inparticular due to starting substrate materialmanufacturing cost and expensiveepitaxial growth processing especially forhigher voltage devices with thick n-baseregions.

High performance at lower costTo reduce cost, the utilization of less SiCdevice area is one approach but at theexpense of higher thermal resistances andhigher conduction losses. In relation, highvoltage SiC unipolar devices display a

strong positive temperature coefficient ofthe Rds(on) during current conduction whichresults in higher losses at highertemperatures. Furthermore, on the deviceperformance front, unipolar SiC devicessuffer from oscillatory behavior duringswitching transients due to the absence ofexcess carriers which normally providebipolar devices with a slow decliningcurrent tail during turn-off for achievingsofter characteristics. Finally, unipolar SiCdevices provide less fault current handlingcapability such as short circuit withstandcapability for MOSFETs and surge currenthandling capability for SBDs compared tobipolar devices. To resolve some of theabove hindering issues for SiCtechnologies, while at the same timebenefiting from the advantages of the wellproven Silicon based devices, wedemonstrate here a Cross Switch “XS”hybrid solution consisting of a parallelcombination of a Si IGBT and SiC MOSFET.

The cross sections of the two structuresare shown in Figure 1 along with thedescribed parallel combination.

In practice, hybrid arrangements ofdifferent power semiconductor devicestructures target optimized performanceby providing the combined advantages ofthe diverse device properties for a givenapplication. With reference to Si and SiCdevices, a popular hybrid combinationutilizing a SiC SBD as the anti-paralleldiode for a Si IGBT has been widelyinvestigated and is currently employed insome applications for achieving lowerreverse recovery and turn-on losseswhen compared to employing thestandard Silicon bipolar fast recoverydiode. Hybrid concept combining a SiIGBT and a Si MOSFET have also beeninvestigated in the lower voltage range<600 V in line with Si MOSFETperformance capabilities. This approachcombines the advantages of both devices

Figure 1: Si IGBT and SiC MOSFET structures for the hybrid Cross Switch

ABB_Feature.qxp_Layout 1 04/11/2015 09:34

www.abb.com/semiconductors POWER SEMICONDUCTORS 19


with low conduction losses for the IGBTand low switching losses for the MOSFET.Building on this trend and for a widervoltage and current range by employingSiC MOSFETs, the basic hybridcombination of an IGBT and MOSFET

provides a potential solution to obtainoverall improvements at lower cost for agiven application requirement.

Hybrid 1200 V demonstrationThe Cross Switch “XS” combines a Si IGBT

and a SiC MOSFET in parallel. The maintargets of such a combination are toprovide low static and dynamic losseswhile improving the overall electrical andthermal properties due to theadvantageous features both devices canoffer in many power electronicsapplications. To investigate and validate theabove concept, XS hybrid test sampleswere manufactured consisting of a single1200 V/25 A Si Soft Punch Through (SPT)IGBT (6.5 mm x 6.5 mm) in parallel to a1200 V/30 A SiC MOSFET (4.1 mm x 4.1mm) with an Rds(on) of 80 m� on a singletest substrate. The active area ratio of theIGBT to the MOSFET was close to 3:1. Theassumed nominal current rating of thecombined XS hybrid was set at 50A.

Both gates are connected and controlledby the same single gate unit. Forcomparison, reference samples were alsomade with one consisting of two paralleledSi SPT IGBTs and the other having twoparalleled SiC MOSFETs to provide thesame 50A rating per test sample. Thesame gate voltage signal was also appliedfor all chips in parallel. Furthermore, toanalyze the behavior of the XS hybrid, testsamples containing a single Si SPT IGBTand others containing a single SiC MOSFETwere also fabricated. For the staticparameters, Figure 2 shows the IV transfercurves at 25°C and output characteristicsat 150°C for the XS hybrid. Curves for thesingle Si IGBT and SiC MOSFET are alsodepicted to show that the XS hybrid is acombination of both device characteristics.

For the same 50A current rating, the IVoutput characteristics at 150°C comparingXS hybrid to the 2 x Si SPT IGBT and 2 xSiC MOSFET samples are provided inFigure 3 which also shows the same IVoutput characteristics but only up to 10 %of the nominal current. It is shown that theparallel combination offers the possibilityto provide IGBT characteristics at highcurrents while still maintaining low lossesat very low currents as for a MOSFET. Thisparticular feature has always been a majorhurdle for bipolar devices and thus such acombination offers an important advantagein power device performance. In addition,the XS hybrid offers improved thermalresistance due to the large Si IGBT area.More reductions in MOSFET Rds(on)values will further lower the XS hybridconduction losses when compared to thefull Si IGBT. The switching characteristicswere measured using a double pulseclamped inductive test circuit having astray inductance value of 60 nH. A SiCSBD diode rated at 1200 V and 50 A wasemployed as the freewheeling diode.Figure 4 shows the turn-off performance ofthe XS hybrid compared to the 2 x Si SPTIGBT and 2 x SiC MOSFET samples under

Figure 2: IV transfer characteristics at 25°C (left) and IV output characteristics at 150°C comparing theXS hybrid to a single Si SPT IGBT and a single SiC MOSFETs

Figure 3: IV output characteristics at 150°C (left) comparing the XS hybrid to 2 x Si SPT IGBTs and 2 xSiC MOSFETs up to twice and 10% of nominal current

Figure 4: Turn-offswitching waveformscomparing the XShybrid to 2 x Si SPTIGBTs and 2 x SiCMOSFETs at 50 A, 600 V, 150°C


20 POWER SEMICONDUCTORS www.abb.com/semiconductors


nominal conditions and with an Rg(off) of 10 � at 150°C. Under such switching conditions, the XS

hybrid provides again a combination of thetwo device distinctive turn-offcharacteristics. The switching event isinitiated with the SiC MOSFET turning off atan earlier time compared to the Si IGBT.The XS hybrid is therefore displaying aswitching behavior corresponding to bothdevice behavior patterns while clearlyexhibiting a soft current tail due to theremaining excess charge in the IGBT. Thesoftness of the XS hybrid is also confirmedwith a low overshoot voltage whencompared to the SiC MOSFET. In general,SiC MOSFETs are normally slowed downby increasing the gate resistor Rg(off) toreduce the EMI and overshoot voltagesespecially at high currents. Therefore, theturn-off softness will improve in the XShybrid by providing a current tail duringturn-off and the possibility to employ theconcept in high voltage and high currentmodules with a moderate stray inductance.To gain further understanding, the turn-offswitching losses and softness dependence

on the turn-off gate resistor Rg(off) wasfurther investigated. Figure 5 shows such dependency for

the turn-off losses Eoff at 150°C andmaximum overshoot voltage Vcem at 25°C.Over the full Rg(off) range, the XS hybridoffers 40 % lower Eoff compared to the SiIGBT reference sample and softerperformance than the SiC MOSFET. Bycomparing the Eoff when achieving similarovershoot voltages, the XS hybrid showsapproximately 3 mJ compared to 5 mJ forthe full Si IGBT at an Rg(off) of 2.2 �, and 1mJ for the full SiC MOSFET at an Rg(off) of47 �.The turn-on losses Eon of the XS hybrid

under nominal conditions and Rg(on) of 22 � at 150°C was measured at 2.8 mJ.The turn-on measurements for thedifferent samples including the full Si IGBTand full SiC MOSFET show that the lossesare not influenced by the switch type butmainly dependent on the SiC SBDcharacteristic and switching conditions.Finally, the short circuit performance ofthe XS hybrid was verified at a DC voltageof 600 V and a gate voltage of 15 V at

150°C. Figure 6 shows the short circuitwaveforms of the XS hybrid while alsoproviding the short circuit waveforms ofthe single Si SPT IGBT and single SiCMOSFET. As expected, the total shortcircuit current of the XS hybrid is the sumof the short circuit current of bothparalleled device. The test was repeatedsuccessfully with increased gate voltagesup to 19 V.Compared to previous work on Silicon

based IGBT/MOSFET hybrids, the XSHybrid concept enables a very high voltagerating up to 6.5 kV and potentially beyond.Future work will focus on a more advancedhigh voltage XS Hybrid combining inparallel a Silicon Reverse Conducting RC-IGBT or BIGT and a SiC MOSFET to providethe XS Hybrid with Bimode operation withintegrated diode functionalities whileeliminating the need for an externalfreewheeling diode.

ConclusionThe above demonstrations provide aninitial insight into the XS hybrid conceptand validate the potential of such acombination for future power electronicsapplications. Results confirm that inaddition to the potential lower cost, themain expected advantages of the XS hybridcombinations are (a) low conductionlosses over the full current range, (b) lowswitching losses, (c) low thermalresistance, (d) soft turn-off performance,(e) high switching robustness and (f)improved fault current protection in shortcircuit and surge current capability. The XShybrid also provides a conceivable path forfurther optimization for a given targetedpower electronics application at therequired operational frequency.

Figure 5: Eoff at 150°C(left) and Vcem at 25°Cas a function of Rgoff

comparing the XShybrid to 2 x Si SPTIGBTs and 2 x SiCMOSFETs at 50 A/600 V

Figure 6: Short Circuitswitching waveformsfor the XS hybrid, asingle Si SPT IGBTand a single SiCMOSFETs at 600 Vand 150°C

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22 POWER ICs www.power.com/innoswitch-ep


Efficiency Revolution in Auxiliary and Standby Power SuppliesThe new InnoSwitch TM-EP family of ICs simplify the development and manufacturing of low-voltage, high-current power supplies, particularly those in compact enclosures or with high efficiency requirements.Its architecture is revolutionary in that the devices incorporate both primary and secondary controllers, withsense elements and a safety-rated feedback mechanism into a single IC. It combines a high-voltage powerMOSFET along with both primary-side and secondary-side controllers in one device. A novel inductivecoupling feedback scheme using the package leadframe and bond wires o provide accurate direct sensingof the output voltage and output current on the secondary to communicate information to the primary IC.Silvestro Fimiani, Senior Product Marketing Manager, Power Integrations, San Jose, USA

Usually, different methods for solvingsimilar problems arise because a designeris trying to optimize one particularcharacteristic – size, efficiency, cost etc.However, an optimized performance inone aspect of a specification often leads toa compromise somewhere else. This isespecially true in power supply design.When we look at the available switchingpower topologies there are many typesthat have evolved to suit specificrequirements Nonetheless, true break-through developments occur from time-to-time when designers develop a new ideathat radically changes the traditionalbalance of engineering trade-offs.

This is perhaps why the word‘revolutionary’ has been used to describe anew series of switcher ICs launched lastyear. The new devices combine primaryand secondary switcher circuitry, reducingcomponent count and eliminatingoptocouplers. In addition to benefits overtraditional opto-based topologies, the newICs outperform primary-side controllers inefficiency at full-load and standby powerand in transient load response. The firstdevices – named InnoSwitch-CH™ -targeted smart mobile devices; now thecompany has introduced InnoSwitch-EP™ICs (Figure 1) designed to bring the samebenefits to higher power applications.

New power IC topologyThese new CV/CC flyback switching ICsfeature an integrated 725 V MOSFET,synchronous rectification and precisesecondary-side feedback sensing controller.InnoSwitch parts employ a proprietary highspeed magneto-inductive communication

– termed FluxLink™ – incorporated in thedevice package which creates a magneticcoupling between the primary andsecondary side. No integrated magneticcore is required and the bill-of-materials forthe manufacture of the IC packageremains the same. FluxLink technologyprovides very accurate control of theswitching function, enabling synchronousrectification techniques to be employed,delivering high efficiency without complexcontrol circuitry (Figure 2).

Replacing the traditional Schottky diodewith a MOSFET is the basis of synchronousrectification. MOSFETs have a very low on-resistance (RDS(ON)), so the voltage dropacross the transistor is much lower than fordiodes, resulting in a significant increase in

efficiency. However, moving tosynchronous rectification is notstraightforward. Control circuitry is requiredto correctly phase the drive for thetransistor on the primary side with that ofthe transistor on the secondary side. Thiscontrol circuit must ensure that currentonly flows through one of the transistors atany given time.

To prevent overlap in the switching ofthe primary (flyback) and synchronousrectification MOSFETs which would resultin highly destructive cross conduction,controllers typically introduce a delaybetween the turn off of one transistor andthe turn on of the other. This ‘dead-time’must be sufficient to account for thevariable propagation delays associated with

Figure 1: InnoSwitch-EP™ CV/CC flyback switching ICs

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www.power.com/innoswitch-ep POWER ICs 23


the circuitry necessary to drive transistorson opposite sides of an isolation barrier.Integration of key switching elements(controller, MOSFETs and drivers) reducesthis uncertainty and allows the dead-timeto be reduced with a correspondingincrease in efficiency.

MOSFETS contain an integral bodydiode and in the synchronous rectificationMOSFET will conduct during the dead-time. The body diode has a slow turn-offcharacteristic and significant forwardvoltage-drop leading to a 1 to 2 % drop inefficiency. A Schottky diode placed inparallel with the body diode of thesynchronous rectification MOSFET preventsthe body diode from conducting andreduces the loss in efficiency.

So although synchronous rectificationhas advantages, it can be difficult to

implement because the timing of theMOSFET’s switching is challenging. Theideal approach is to control the primary-side switch from the secondary-side of thepower supply. This avoids the need topredict of the state of either MOSFETallowing greatly reduced dead-time whilstensuring that the two MOSFETs are neversimultaneously in the on-state.

However, until recently, synchronousrectification required a complex andexpensive circuit often involving multiplepulse transformers, limiting the utility ofsynchronous rectification in compact and/orhigh-reliability applications. FluxLinktechnology (Figure 3) within InnoSwitch ICseliminates the need for this extra circuitry.Accurate feedback is provided and precisecontrol made possible, so that circuits areneither too conservative - which would

adversely affect efficiency - nor tooaggressive which would risk the damagingeffects of shoot-through. InnoSwitch ICs sitacross the isolation barrier utilizing whatwould otherwise be dead-space on the PCB.

Typical applicationsThe first application for InnoSwitch ICs wasincreasingly power-hungry smart mobiledevices, but auxiliary and standby power inappliances, HVAC, consumer electronics,computing, telecom and datacommunication applications would alsogain substantial benefits from increasedefficiency across the load range.InnoSwitch-EP ICs are an answer toengineers looking to address increasinglydemanding Total Energy Consumption(TEC) regulations from bodies such asENERGY STAR® and ErP with an easy-to-implement solution that improves powersupply efficiency from standby to full load.For example, InnoSwitch-EP ICs enable a20 W power supply to achieve 90 %efficiency in a multi-output design, whilereducing no load consumption to less than30 mW. Voltage regulation across line ishighly accurate at +/-5 % with tightlycontrolled over-current protection alsoprovided (Figure 4).

As well as efficiency, InnoSwitch-EPCV/CC flyback switching ICs also deliverexcellent multi-output cross-regulationwithout requiring linear regulators, andprovide full line protection andinstantaneous transient response. Withappliances becoming increasinglysophisticated and correspondingly highcost items, reliability is crucial, especiallyfor brands that promise long life anduninterrupted service by offering lifetimeguarantees. Multi-output regulation is alsoan important consideration for appliancedesigners who deal with multiple functionsthat need power – clocks, motors, displays,microprocessors etc. Some functionsrequire very tight voltage tolerances and tomeet this engineers have previously used

Figure 2: High-speed magneto-inductive communication FluxLink

ABOVE Figure 3:FluxLink technologyprovides accuratefeedback enablingprecise control

RIGHT Figure 4: Highefficiency at light

loads


24 POWER ICs www.power.com/innoswitch-ep


complex multi-stage architectures.Figure 5 compares a design using a

Schottky diode rectifier with an InnoSwitch-based circuit using synchronousrectification. In the circuit on the left, aSchottky diode is used for outputrectification. The forward voltage drop of aSchottky diode is current sensitive (andcan be modeled as a diode plus a seriesresistor) causing forward voltage drop toincrease with rising load current. Primaryside regulation cannot control multipleoutputs, so the other outputs increasewhen the controller acts to regulate theprimary output to compensate for thisincrease in voltage drop. The circuit shown in the right had side

of the diagram – based on InnoSwitch-EP -uses a synchronous rectification MOSFETwhich is relatively insensitive to changes inload current. This reduces cross regulationeffects on the other outputs.InnoSwitch-EP ICs feature advanced

protection and safety features including:primary sensed output OVP; secondarysensed output overshoot clamping;secondary sensed output over-currentprotection down to zero output voltage;hysteretic thermal shutdown; and an inputvoltage monitor with accurate brown-in/brown-out plus line over-voltageprotection. The circuit shown in the right had side

of the diagram – based on InnoSwitch-EP -uses a synchronous rectification MOSFETwhich is relatively insensitive to changes inload current. This reduces cross regulationeffects on the other outputs.InnoSwitch-EP ICs feature advanced

protection and safety features including:primary sensed output OVP; secondarysensed output overshoot clamping;secondary sensed output over-currentprotection down to zero output voltage;hysteretic thermal shutdown; and an inputvoltage monitor with accurate brown-

in/brown-out plus line overvoltageprotection. InnoSwitch-EP switcher ICs can safely be

connected across the isolation barrier. Allparts undergo HIPOT compliance testduring production equivalent to 6 kVDC/1-sec and have reinforced insulationwith an isolation voltage of greater than3500 V AC. They are UL1577 and TUV(EN60950) safety approved andEN61000-4-8 (100 A/m) and EN61000-4-9 (1000 A/m) compliant.A reference design (RDR 469) is freely

downloadable at: https://ac-dc.power.com/design-support/reference-designs/design-examples/rdr-469-dual-output-20-w-embedded-power/ (Figure 6). It describesa dual output 20 W embedded powersupply based on the InnoSwitch-EPINN2605K which has universal 85 – 264V AC input and 12 V, 1.5 A and 5 V, 0.5 Aoutputs. A reference design kit is alsoavailable for purchase.

Figure 6: A dual output 20 W embedded power supply based on the InnoSwitch-EP INN2605K

Figure 5: InnoSwitch-EP uses a synchronous rectification MOSFET which is relatively insensitive to changes in load current, reducing cross regulation effectson the other outputs


www.linear.com ENERGY HARVESTING 25


New Energy Harvesting ICsPower SensorsSo far various types of sensors were routinely connected by wires to their power sources. Today it ispossible to install reliable, industrial-strength wireless sensors that can operate for years on a small battery,or even harvest energy from sources such as light, vibration or temperature gradients. Furthermore, it is alsopossible to use a combination of a rechargeable battery and multiple ambient energy sources too.Moreover, due to intrinsic safety concerns, some rechargeable batteries cannot be charged by wires butrequire being charged via wireless power transfer techniques. Linear Technology has introduced energyharvesting ICs designed to work with different battery voltages. Tony Armstrong, Director ProductMarketing Power Products, Linear Technology Corp., Milpitas, USA

State-of-the-art and off-the-shelf energyharvesting technologies, for example invibration energy harvesting from piezotransducers and indoor photovoltaic cells,can yield power levels in the order ofmilliwatts under typical operating conditions.While such power levels might initiallyappear restrictive, the operation ofharvesting elements over a number of yearscan mean that the technologies are broadlycomparable to long-life primary batteries,both in terms of energy provision and thecost per energy unit provided. Furthermore,systems incorporating energy harvesting willtypically be capable of recharging afterdepletion, something that systems poweredby primary batteries cannot do. Thus, theadditional cost of adding energy harvestingto power a sensor can be offset by themaintenance cost of having to change

primary batteries every 7 to 10 years, or so.

Overcoming barriersWireless and wired sensor systems are oftenfound in environments rife with ambientenergy, ideal for powering the sensorsthemselves. Today it is generally acceptedthat energy harvesting can significantlyextend the lifetime of installed batteries,especially when power requirements arelow, reducing down time in addition to long-term maintenance costs. In spite of thesebenefits, a number of adoption roadblocksstill persist. The most significant is thatambient energy sources are oftenintermittent, or insufficient to power thesensor system continuously, where primarybattery power sources are extremely reliableover the course of their rated life. As aconsequence, some system designers may

be reluctant to upgrade their systems toharvest ambient energy, especially whenseamless integration is paramount.Nevertheless, most implementations will

use an ambient energy source as the primarypower source, but will supplement it with abattery that can be switched in if the ambientenergy source goes away or is disrupted. Thisbattery can be either be rechargeable or notand this choice is usually driven by the endapplication itself. So it follows that if the enddeployment allows for easy access to changea non-rechargeable battery, wheremaintenance personnel can readily swap itout in a cost effective manner, then thismakes economic sense. However, if changingthe battery is cumbersome and expensive,then the utilization of a rechargeable batterymakes more economic sense.Even if a rechargeable battery is selected,

the question of the optimum method tocharge it remains open. Some of the factorsthat will affect this decision are:� Is there a wired power source to chargethe battery

� Is there sufficient power available from theambient energy sources to have sufficientpower available to power the wirelesssensor network (WSN), and also chargethe battery

� Is wireless power transfer required tocharge the battery due to intrinsic safetyrequirements due to the hazardous natureof its deployment

Simple IC solutionsThe LTC3107 is a highly integrated DC/DCconverter designed to extend the life of aprimary battery in low power wirelesssystems by harvesting and managing surplusenergy from extremely low input voltagesources such as TEGs (ThermoelectricGenerators) and thermopiles.With the LTC3107, a point-of-load energyFigure 1: The LTC3331 converts multiple energy sources and can use a primary rechargeable battery

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26 ENERGY HARVESTING www.linear.com


harvester requires little space, just enoughroom for the IC’s 3 mm � 3 mm DFNpackage and a few external components. Bygenerating an output voltage that tracks thatof the existing primary battery, the devicecan be seamlessly adopted to bring the cost-savings of free thermal energy harvesting tonew and existing battery-powered designs.Along with a small source of thermal energy,the device can extend battery life, in somecases up to the shelf life of the battery,thereby reducing the recurring maintenancecosts associated with battery replacement.The LTC3107 was designed to augment thebattery or even supply the load entirely,depending on the load conditions andharvested energy available. Another example is the LTC3331 (see

Figure 1, 2), a complete regulating energyharvesting solution that delivers up to 50mA of continuous output current to extend

battery life when harvestable energy isavailable. It requires no supply currentfrom the battery when providing regulatedpower to the load from harvested energyand only 950 nA operating when poweredfrom the battery under no-load conditions.This device integrates a high-voltageenergy harvesting power supply, plus asynchronous buck-boost DC/DC converterpowered from a rechargeable primary cellbattery to create a single non-interruptibleoutput for energy harvesting applicationssuch as wireless sensor nodes (WSNs)and Internet of things (IoT) devices.The LTC3331’s energy harvesting power

supply, consisting of a full-wave bridgerectifier accommodating AC or DC inputs anda high efficiency synchronous buck converter,harvests energy from piezoelectric (AC), solar(DC) (see Figure 3) or magnetic (AC)sources. A 10 mA shunt enables simple

charging of the battery with harvested energywhile a low battery disconnect functionprotects the battery from deep discharge. The rechargeable battery powers a

synchronous buck-boost converter thatoperates from 1.8 V to 5.5 V at its input andis used when harvested energy is notavailable to regulate the output whether theinput is above, below or equal to the output.The battery charger has a very importantpower management feature that cannot beoverlooked when dealing with micropowersources. The IC incorporates logical controlof the battery charger such that it will onlycharge the battery when the energyharvested supply has excess energy.Without this logical function the energyharvested source would get stuck at startupat some non-optimal operating point andnot be able to power the intendedapplication through its startup. Automaticallytransitions to the battery are performedwhen the harvesting source is no longeravailable. This has the added benefit ofallowing the battery operated WSN to extendits operating life from 10 years to over 20years if a suitable EH power source isavailable at least half of the time, and evenlonger if the EH source is more prevalent. Asupercapacitor balancer is also integratedallowing for increased output storage. Figure4 shows the battery charging process.

ConclusionTo facilitate the adoption of ambient energyharvesting into a wide range of new andexisting primary battery-powered applications,Linear Technology has introduced energyharvesting ICs designed to work with differentbattery voltages. This includes most of thepopular long-life primary batteries used inlower power applications, such as 3 Vlithium coin cell batteries and 3.6 V lithium-thionyl chloride batteries. These productseasily offer the best of both worlds — thereliability of battery power and themaintenance cost savings of energyharvesting with minimal design effort.

Figure 2: LTC3331block diagram

Figure 4: Battery charging processFigure 3: LTC3331 solar energy harvesting application

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www.vincotech.com POWER INVERTERS 27


Asymmetrical Inductance toSupport Long Cables in Low-Power Motor DrivesHigh capacitive turn-on current often overload IGBTs in low-power inverter applications that use longshielded cables. A simple workaround can reduce losses and electromagnetic interference and ensuremore reliable performance. Michael Frisch, Head of Product Marketing, Vincotech,Unterhaching/Munich, Germany

Capacity and current for charging areindependent of the output current. In low-power inverter applications, the additionallosses for this capacitive load account for asignificant share of overall powerdissipation.

The additional dissipated energy is thuscalculated according to equation 1:

E = 1⁄2 C*U2 (1)

The IGBT has to charge the capacitybefore it is able to turn on completely. Thevoltage drop between the DC voltage andcapacitor voltage is dissipated in theswitch. The losses are also proportional tothe switching frequency and DC voltage.The problem with a long cable is perhapsmost pronounced in low-powerapplications with 700 V DC and a PWMfrequency of 16 kHz.

Countermeasure 1 - increase activecurrent ratingA simple countermeasure is to increasethe inverter IGBTs’ current rating. A bettercooling system would be necessarybecause of the increased losses, soselecting an inverter with a higher rating forapplications with long cables is a simple

solution, but certainly not the besteconomically speaking. The higherdissipation is a disadvantage and EMIincreases with the high turn-on current,which compounds the EMI filter circuit’scomplexity.

Countermeasure 2 - add an outputfilterA sine wave output filter is one way ofreducing turn-on losses in the inverter. Thiskind of filter would rule out any increase inturn-on current, which in turn wouldreduce losses and EMI in the inverter.However, placing sine wave filters in theoutput would easily double the cost, sothis is too expensive for most low-powerapplications.

Countermeasure 3 - add a smalloutput inductorAnother approach would be to use lowinductance in the output to achieve therequired voltage drop with reactive power,the idea being to smooth out the slope ofthe output turn-on voltage and thus thecable capacitor’s charging current. Aninductor with just 2 µH would not addmuch to the inverter’s cost. Unfortunately,this won’t work. Once the inductor has

charged the parasitic capacity of the cable,it will continue driving the current � = �(motor)

+ �(charge). This would increase voltage at theoutput, alternating with increased current,which would culminate in heavyundamped oscillation.

Countermeasure 4 - use asymmetricalinput inductanceAdding inductance to the DC input wouldwork. A small snubber capacitor with adiode would have to be connected toprevent resonance with the outputcapacitance and voltage overshooting atturn-off (see Figure 2).

Although the IGBT turns on, the currentis limited by the inductor. The inductorcurrent includes the cable capacitancecharging current. The current decreasesonce the output capacitance is charged.The stored energy in the inductor flowsthrough the diode into the transientcapacitor and is dissipated by a resistor.

Inverter with asymmetrical inputinductanceLet’s see what such an inverter could looklike. The dimensions of the additionalcomponents would depend on cablecapacitance.

Figure 1: An invertercircuit with acapacitive loadgenerated by a longmotor cable

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28 POWER INVERTERS www.vincotech.com


Energy according to equation 2

E = 1⁄2 C*�U2 = 1⁄2 L*��2) (2)

is transferred into the transient capacitor,and the majority of it is dissipated by aresistor according to the following exampleand equation 3:� Long cable (100 m) with 5 nF outputcapacitance

� Transient capacitor: 2 µF� DC inductance: 2 µH� DC voltage VDC=600 V� fPWM = 16 kHz� Output power: 2 kW to 4 kW� �Out(max) = 10 A

E = 1⁄2 C*U2 = 1⁄2 * 5 nF * (600 V)2

= 0.9 mWs (3)

The voltage increase in the transientcapacitor is less than 60V. The resistor thenhas to dissipate at turn-on

PON = 16 kHz * 0.9 mWs = 14 W (4)

and at turn-off

POFF = fPWM * 1⁄2 �2 * L, POFF = 16 kHz * 1⁄2 *(10 A)2 * 2 µH = 1.6 W (5)

and in total

P = PON + POFF = 15.6 W (6)

The IGBT losses of 15.6W are

dissipate transient energy at no extra cost. Stored energy can be regenerated for

applications demanding highest efficiency.

ConclusionThe combination of asymmetrical inputinductance and a brake resistor thatdissipates stored energy is the perfectsolution to the problem with long cables inlow-power inverter applications. The DCcapacitor’s reduced pulse load and theimproved EMC more than compensatesfor the additional outlay. This newapproach minimizes expenses, particularlyfor applications with a brake chopperwhere the brake resistor can be used tothis end.

Figure 2: An inverterwith a snubber circuitto reduce turn-onlosses in the IGBT

Figure 3: An inverterwith snubber circuitwhere the brakeresistor serves todissipate parasiticenergy

transferred into the resistor. The inductorwill also reduce the main DC capacitor’spulse load. And EMI is reduced because ofthe limited turn-on current. Required components are 1 transient

diode, 1 inductor (2 µH / 4 A), 1 DCcapacitor (2 µF / 1000 V), and 1 resistor(100 �-200 � / 20 W).

Use of a brake resistorIn applications with a brake chopper, thebrake resistor could be used to dissipateenergy stored in the transient capacitor(see Figure 3). Required components are1 transient diode, 1 inductor (2 µH / 4 A),and 1 DC capacitor (2 µF / 1000 V). Thebrake resistor serves to dissipate storedenergy.Benefits are reduced power dissipation

in the IGBTs and in particular -15.6 W(reduced rating), reduced pulse load in themain DC capacitor resulting in a lowervalue, reduced peak current at turn-onresulting in a lighter workload for the EMIfilter. The brake resistor also serves to

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www.tmi.yokogawa.com/ea/ POWER MEASUREMENT 29


The Need for High-FrequencyHigh-Accuracy PowerMeasurementAs more and more innovation focuses on energy efficiency and the use of renewable energy resources,engineers are increasingly demanding accuracy and precision from their power measurements. At the sametime, new standards such as IEC62301 Ed2.0 and EN50564:2011, covering standby power consumption,and the SPEC guidelines, covering power consumption in data centres, demand more precise and accuratetesting to ensure compliance. But these levels of precision can only be achieved if the measuringinstruments are properly calibrated with reference to national and international standards. Clive Davis,Marketing Manager T&M and Erik Kroon, Metrology Expert, Yokogawa T&M Center Europe,Amersfoort, Netherlands

The need for new levels of higherprecision in power measurement arises,but these levels of precision can only beachieved if the measuring instrumentsare properly calibrated with reference tonational and international standards.Regular calibration by a laboratory, whichcan provide very low measurementuncertainties at the specificmeasurement points applicable toindividual users, should enableinstrument makers and their customers to have confidence in theirtest results.

High-frequency power measurementOne key area which is often neglected intraditional specifications is that of powermeasurements at high frequencies.Traditionally, AC power meters arecalibrated at frequencies of 50-60 Hz.Nowadays, however, there is a demandfor power measurement at highfrequencies on devices such as switch-mode power supplies, electronic lightingballasts, soft starters in motor controlsand frequency inverters in tractionapplications.

Calibration of high-frequency powerhas lagged behind the development ofpower meters to address theseapplications, and few nationallaboratories can provide traceability up to100 kHz: the frequency at whichinstruments have to be calibrated toprovide accurate results in theseapplication sectors.

There are a number of otherparameters involved in powermeasurements that determine the

performance of an instrument in aparticular application. It is no longersufficient merely to list voltage andcurrent specifications: today’s powerenvironment needs to address variablessuch as phase shift, power factor and theeffects of distorted waveforms.

It is also important to calibrate theinstrument under the right conditions.Many test houses still use pure sinewaves at only 50 Hz to calibrate powermeters, which renders the results virtuallyuseless for users carrying out tests under“real world” conditions. It is thereforeimportant for users of power measuringinstruments to look at the actual‘calibrated’ performance of differentmanufacturers’ products rather than justcomparing specifications. This is the keybehind Yokogawa’s opening of its ownEuropean Standards Laboratory. It hasbecome recently the first non-governmental facility to receive fullISO17025 accreditation for powermeasurements at up to 100 kHz.

Why calibration?Calibration can be defined as thecomparison of an instrument’sperformance with a standard of knownaccuracy because no measurement isever correct. There is always anunknown, finite, non-zero differencebetween a measured value and thecorresponding “true” value.

It is important to understand thedifference between ‘calibration’ and‘adjustment’. Calibration is thecomparison of a measuring instrument(an unknown) against an equal or better

standard. A standard in a measurementis therefore the reference. Instrumentsare adjusted initially at the factory toindicate a value that is as close aspossible to the reference value. Theuncertainties of the reference standardused in the adjustment process will alsodictate the confidence that the indicatedvalue is ‘correct’.

As the instrument ages, the indicatedvalue may drift due to environmentalfactors (temperature, humidity, oxidation,loading etc.) which will also bedependent on the quality of its designand manufacture. To ensure that theinstrument continues to operate withinthe manufacturer’s tolerances, theinstrument should be compared to thereference value on a regular basis(usually annually). If necessary, theinstrument can then be re-adjusted. Ifthere is no appreciable change in thecalibrated results, this means that theinstrument’s design is inherently highlystable. In this case, there is no need toadjust it, and the user can also rely onthe fact that the unit will exhibit the samestability on a day-by-day basis.

Yokogawa’s calibration capabilitiesAt the heart of the laboratory is a specialcalibration system with the capability tocalibrate power up to 100 kHz (seeFigure 1). Housed in a climate-controlledenvironment (23.0 ± 1.0)°C, the systemis able to calibrate voltage, current, DCpower, AC power, frequency and motorfunctions, all under fully automaticcontrol.

The system consists of two parts, a

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signal generator section and a referencemeasuring unit. Those two parts areseparated by a metal shield in order toprevent the heat generated by the signalsources from affecting the referencemeters. Different sources are used togenerate the calibration signal because asingle source is not sufficient to generateall the signals required. Instead,multiplexers are used to select thesources needed for any particularmeasurement. Similarly, differentreference power meters are selected viaa multiplexer. This allows the selection ofthe best reference power meters forhigh-current, low-current or low-voltagecalibrations. The reference power metersare from Yokogawa and are specialmodels modified with aged components and firmware to enhancethe resolution. The power meter under calibration is

connected via a multiplexer on thecalibration system. Each element of thepower meter under calibration iscalibrated separately. A power meter withmixed inputs is easily calibrated. Extrainstruments are added to the calibrationsystem to calibrate any additional optionsof the power meter such as the motorfunction and analogue output.The system is designed to minimize

effects such as capacitive leakage andcrosstalk, with special attention given tothe wiring harness and multiplexers. Forvoltage, twisted and screened coaxialcables are used, while current usescoaxial cabling. The multiplexers usespecial relays to avoid leakage andcrosstalk. The influence of the wiringharness is now kept to a minimum. Witha worst-case measurements using 100 Vat 100 kHz, the crosstalk suppression tothe current channels is better than -93dB. For mixed-input units, every elementis calibrated separately to minimize theeffects of loading.

A calibration is normally based on theinternal Quality Inspection Standards(QIS). If the QIS is passed, it isdemonstrated that the measured valuesare within specifications. However, onrequest it is possible to calibrateadditional points. The system is able tocommunicate with the power meterunder calibration by GPIB, RS232, USBor Ethernet. A typical calibration of a power meter

takes a few hours, depending on thenumber of elements. For each element,tests are made at about 45 voltagecalibration points, 65 current calibrationpoints and 78 power calibration points.Using all those points the voltage gain,voltage linearity, voltage flatness, currentgain, current linearity, current flatness,power gain, power linearity, powerflatness, power factor and frequency arecalibrated at DC and from 10 Hz to 100kHz. This includes also the externalcurrent sensor (shunt) if applicable. Atotal of about 180 calibrations are donefor each element. The system is also able

Figure 1: Traceability overview

Figure 2: Power comparison with national Standards Laboratory of Sweden (SP)

to calibrate the motor function by usinganalogue or pulse shape signals. A 30-channel multiplexer measurementsystem is installed to measure theanalogue output of the power meter. When the calibration is finished, the

results are used to generate thecalibration certificate.

TraceabilityTraceability for power is based on valuesfor voltage, current and phase. Usingthese units, it is possible to calculatepower by the equation P = U x I x cosphi which is valid only for sine waves, sothat special attention has to be taken intoaccount for the harmonic distortions ofthe generated signals.The measurement of voltage is

straightforward using a digital multimeter.However, using a digital multimeter tomeasure the current is limited due to thefrequency capability and uncertainty, andtherefore two different options are used.If the current frequency is 50 to 60 Hz,an electronic compensated currenttransformer (ECCT) is used to measurethe current, but if the frequency is highercurrent shunts have to be used for theother frequencies. Yokogawa has built itsown current shunts to measure from 1mA up to 10 A at up to 100 kHz with amaximum AC/DC difference of 3 parts ina million (ppm) at 100 kHz. Measuringthe voltage over the shunt allows thecurrent to be calculated. To obtain the phase, a phase

measurement device based on a high-speed, high-resolution digitizer is used,equipped with differential inputs to avoidground loops. The biggest uncertaintyhere is the phase angle deviation of thecurrent shunts, which is corrected bycalibrating the shunt at differentfrequencies. The phase measurements


www.tmi.yokogawa.com/ea/ POWER MEASUREMENT 31


device is calibrated via a phase standard,which in turn is calibrated using self-calibrating phase bridges. This setupenables power to be made traceable atup to 100 kHz.

To confirm the calibration setup, aYokogawa WT3000 power analyzer wascalibrated by Yokogawa, and then sent tothe national Standards Laboratory ofSweden (SP). At SP they also calibratedthe Yokogawa WT3000 at the samepoints which verified the results (Figure 2).

The importance of accreditationThe familiar ISO 9001 standard aims atconfirming the traceability of ameasurement but does not define howthe measurement is carried out.Laboratories that are accredited to ISO17025 (General requirements for thecompetence of testing and calibrationlaboratories), however, havedemonstrated that they are technicallycompetent and able to produce preciseand accurate calibration measurements.Figure 3 shows an ISO 17025 certificate

complete with measurementuncertainties, which confirms that thepower meter is truly much more accuratethan its specification. There is noguarantee that the measurements on anISO9001 certificate are correct.

ISO17025 accreditation also reflectsthe attention paid to the design of theinput circuits of Yokogawa’s precisionpower analyzers, with an emphasis onwideband, high-linearity characteristicsthat make them the most accurateinstruments in their class (Figure 4).

Figure 4: Yokogawa WT3000 Power Analyser

Figure 3: Differencesbetween the ISO9001

and ISO17025certificates


32 PRODUCT UPDATE

Vincotech announced the flowRPI 1 family, a new 3-in-1 solution thatintegrates three topologies into one flow1 housing. This module isdesigned for welding, charger and SMPS applications rated from 1.5 to 7kW. The new flowRPI 1 family combines a rectifier with highly efficient low-voltage drop diodes, a two legs PFC featuring ultrafast 650 V IGBTs anddiodes, integrated filtering capacitors and diodes for current sensing viaexternal transformer, and an inverter with H-bridge open emitter topologyand optional capacitors into a single module. A special version comes witha PFC featuring IGBTs with higher current ratings for a wider input voltagerange. It is rated for applications with 110 – 220 V AC input voltage. Theenhanced layout of the flowRPI 1 is more EMC-friendly. With the latestIGBT H5 chip technologies on board, the module delivers ultra-fastswitching at ultra-low conduction and switching losses. Given the option ofthree power stages in a single module, engineers will find it very easy todesign highly compact PCBs. Various power ratings are available in thesame flow1 housing with the same pinout, so applications may be scaledup with PCB design remaining intact. This latest generation module coversapplication power ranges from 1.5 up to 7 kW in various steps. The newflowRPI 1 family comes in flow1 12 mm and 17 mm housings. Press-fitpins and phase-change material are available on request. These moduleswill be manufactured in series in early 2016.

www.vincotech.com

Texas Instruments introduced a new half-bridge gate driver(UCC27714) for discrete power MOSFETs and IGBTs thatoperate up to 600 V. The high-side, low-side driver with 4-A source and 4-A sink current capability delivers 90 nspropagation delay, tight control of the propagation delaywith a maximum of 125 ns across -40°C to 125°C andtight channel-to-channel delay matching of 20 ns acrossthis temperature range. The device eliminates the need forbulky gate drive transformers, saving significant boardspace in high-frequency switch-mode power electronics.With the UCC27714 and TI’s recently released UCC29950combination PFC + LLC controller, designers can developa complete, offline AC/DC power supply rated up to a fewhundred watts. The fully internalized PFC compensation ofUCC29950 reduces design steps enabling fast time-to-market while the three-level over current protection andhiccup mode operation ensures a robust operation undershort circuits and overload conditions. The high-speed 600V high-side low-side gate driver comes in a small outlineintegrated circuit (SOIC)-14 package and is priced at $1.75in 1,000 unit-quantities.

www.ti.com/UCC27714-pr-eu

The new A1245 from Allegro MicroSystems Europe is a two-wire Hall-effectlatch with high magnetic sensitivity for automotive and industrial speed andposition sensing applications.The latch is produced using BiCMOS wafer fabrication process, and

implements the company’s patented high-frequency 4-phase chopper-stabilisation technique to achieve magnetic stability over its full operatingtemperature range from -40º to +150ºC. Two-wire latches of this type areparticularly advantageous in cost-sensitive applications because they requireone less wire for operation compared with the more traditional open-collectoroutput switches. In addition, the system designer inherently gains diagnosticcapabilities because there is always output current flowing, which should be ineither of two narrow ranges. Any current level not within these rangesindicates a fault condition. The Hall-effect latch is in the high output currentstate in the presence of a magnetic south polarity field of sufficient magnitude,and remains in this state until a sufficient north polarity field is present. TheA1245 is designed for speed and position sensing of ring magnets or othermoving/rotating assemblies in applications that are safety-critical and/or havelong wiring harnesses. Typical automotive applications include internal modeswitch transmissions and transmission range switch/manual lever positionsensor shift selectors; electronic parking brake motors; electronic powersteering; and sunroof, tailgate and other motors. The device is also suited toindustrial and consumer applications including white goods, industrial controland factory automation, and automatic doors.

www.allegromicro.com


Two-Wire Hall-Effect Latch

One Module ContainsRectifier and PFC andInverter

600 V Gate Driver

Product Pages_0615.qxp_Layout 1 04/11/2015 10:09

WEBSITE LOCATOR 33


AC/DC Connverters

www.irf.comInternational Rectifier Co. (GB) LtdTel: +44 (0)1737 227200

Diodes

Discrete Semiconductors

Drivers ICS

EMC/EMIwww.microsemi.comMicrosemiTel: 001 541 382 8028

Ferrites & Accessories

GTO/Triacs

Hall Current Sensors

IGBTs

DC/DC Connverters


www.power.ti.comTexas InstrumentsTel: +44 (0)1604 663399


www.neutronltd.co.ukNeutron LtdTel: +44 (0)1460 242200

Harmonic Filters

www.murata-europe.comMurata Electronics (UK) LtdTel: +44 (0)1252 811666

Direct Bonded Copper (DPC Substrates)

www.curamik.co.ukcuramik� electronics GmbHTel: +49 9645 9222 0


www.mark5.comMark 5 LtdTel: +44 (0)2392 618616

www.dgseals.comdgseals.comTel: 001 972 931 8463

www.microsemi.comMicrosemiTel: 001 541 382 8028


www.digikey.com/europeDigi-KeyTel: +31 (0)53 484 9584


www.dextermag.comDexter Magnetic Technologies, Inc.Tel: 001 847 956 1140



www.protocol-power.comProtocol Power ProductsTel: +44 (0)1582 477737

Busbars

www.auxel.comAuxel FTGTel: + 33 3 20 62 95 20

Capacitors

Certification

www.psl-group.uk.comPSL Group UK Ltd.Tel +44 (0) 1582 676800

Connectors & Terminal Blocks

www.auxel.comAuxel FTGTel: +44 (0)7714 699967

www.productapprovals.co.ukProduct Approvals LtdTel: +44 (0)1588 620192

www.proton-electrotex.com/ Proton-Electrotex JSC/Tel: +7 4862 440642;

www.voltagemultipliers.com Voltage Multipliers, Inc.Tel: 001 559 651 1402


Arbitrary 4-Quadrant PowerSources

www.rohrer-muenchen.deRohrer GmbH Tel.: +49 (0)89 8970120



Website Locator.qxp_p41-42 Website Locator 04/11/2015 10:51

34 WEBSITE LOCATOR


Power Modules

Power Protection Products

Power Semiconductors

Power Substrates

Resistors & Potentiometers

RF & Microwave TestEquipment.

Simulation Software

Thyristors

Smartpower Devices

Voltage References

Power ICs

Power Amplifiers

Switches & Relays

Switched Mode PowerSupplies

Switched Mode PowerSupplies

Thermal Management &Heatsinks

Thermal Management &Heatsinks




www.neutronltd.co.ukNeutron LtdTel: +44 (0)1460 242200

www.rubadue.comRubadue Wire Co., Inc.Tel. 001 970-351-6100








www.fujielectric-europe.comFuji Electric Europe GmbHTel: +49 (0)69-66902920




www.ar-europe.ieAR EuropeTel: 353-61-504300



www.universal-science.comUniversal Science LtdTel: +44 (0)1908 222211

www.power.ti.comTexas InstrummentsTel: +44 (0)1604 663399


www.dau-at.comDau GmbH & Co KGTel: +43 3143 23510

www.power.ti.comTexas InstrummentsTel: +44 (0)1604 663399


www.isabellenhuette.deIsabellenhütte Heusler GmbH KGTel: +49/(27 71) 9 34 2 82

ADVERTISERS INDEX

Mosfets

Magnetic Materials/Products

Line Simulation

Optoelectronic Devices

Packaging & Packaging Materials


www.biaspower.comBias Power, LLCTel: 001 847 215 2427www.digikey.com/europe

Digi-Key Tel: +31 (0)53 484 9584


www.digikey.com/europeDigi-Key Tel: +31 (0)53 484 9584




www.abl-heatsinks.co.ukABL Components LtdTel: +44 (0) 121 789 8686

www.hero-power.com Rohrer GmbH Tel.: +49 (0)89 8970120

www.rohrer-muenchen.deRohrer GmbHTel.: +49 (0)89 8970120


ABB ............................................................................................................................................................IFCAPEC...........................................................................................................................................................21Dau................................................................................................................................................................5Cornell Dubilier ......................................................................................................................................13DFA Media ..............................................................................................................................................14Microchip ..................................................................................................................................................17Fuji Electric ...........................................................................................................................................OBCHKR.............................................................................................................................................................27

Isabellenhutte ............................................................................................................................................6

LEM ...............................................................................................................................................................7

Omicron.......................................................................................................................................................9

PCIM ........................................................................................................................................................IBC

Powerex.....................................................................................................................................................10

Semikron .....................................................................................................................................................4

Toshiba ......................................................................................................................................................15




Website Locator.qxp_p41-42 Website Locator 04/11/2015 10:51

Connecting Global Power

International Exhibition and Conferencefor Power Electronics, Intelligent Motion,Renewable Energy and Energy ManagementNuremberg, 10 – 12 May 2016

More information at +49 711 [email protected] or pcim-europe.com

PCIM_EU_2016_ANZ_E_210x297.indd 1 05.10.15 11:0535_pee_0615.indd 1 04/11/2015 09:25

36_pee_0615.indd 1 04/11/2015 09:23

ISSUE 6 – November 2015 POWER ICs · Email: [email protected] Circulation and subscription:...

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