Smart technology for a sustainable world

Introduction to Power ElectronicsClass 1

Julio Pimentel, CEO Kylowave Inc.

www.kylowave.comwww.kylowaveeducation.com

Department of Electronics

Carleton University, Ottawa, ON, CA

September 9th, 2013

Class 1What you will learn Why we need power electronics

Fundamentals of power electronics circuits

Functioning of some widely used power electronics devices

Classes of power electronics circuits

Examples of some basic power electronics circuits

MotivationWhat you have learned so far Digital electronics

Transistors operate in saturation or cut-off regions => switch

Very effective to process logicalinformation

Not as efficient to process analog information

Transistor Ro (output resistance) is optimum: R0 = Vt / Ic Dissipated power: P = Vsw x Ic

Cut-off: Ic=0 => R0 = infinity

Sat: Ic=Ic(min) => Ro=minimum

Transistors are of minimum size => can not process high energy signals

Analog electronics Transistors operate in the linear

region

Very effective to process analoginformation

Not so efficient to process logical information

Transistor Ro (output resistance) is not optimum: R0 = Vt / Ic

Dissipated power: P = Vsw x Ic

Transistors are of small size => can not process high energy signals

MotivationWhy Is It Exciting Technology? Power electronics is a growing field due to the

improvement in switching technologies and the need for more and more efficient switching circuits

It is the enabling technology for emerging applications CleanTech

photovoltaic and wind energy generation and Fuel cell

Electric vehicles (hybrids and plug-in cars, bikes, scooters, etc.)

Smart power system grids

Mechatronics and robotics

Biomedical devices, and many more …

MotivationSome Example Applications Heating and lighting

control

Induction heating

Fluorescent lamp ballasts

Motor drives

Battery chargers

Electric vehicles

Switching power supplies

Spacecraft power systems

Uninterruptible power supplies

Energy storage High density batteries

Flywheels

Super capacitors

Alternative power sources Photovoltaic

Wind turbines

Fuell cells

AND MANY MANY MORE

MotivationWhy power “electronics”? Objectives:

To process “analog” signals

Carrying very large amount of energy

At very high efficiency (sometimes at 95% or 98%)

Requires low loss devices: NO RESISTORS IN THE ENERGY PATH

Recall that the theoretical maximum efficiency of a:

Class A amplifier: η(max) = 50 %

Class B amplifier: η(max) = 78.5 %

Class AB amplifier: 50 % < η(max) < 78.5 %

Class C amplifier: η(max) < 90 % but @ high output distortion

MotivationWhy power “electronics”? (Cntd) Requirements

Process analog signals Uses modulation techniques (ex.: PWM Pulse Width Modulation)

Use filtering to eliminate high frequency harmonics

Process high energy signals (high current and/or high voltage) requires very large transistors

Requires very low RON values

Very high efficiency Transistors must dissipate minimum power

Transistors operate as switches (saturation and cut-off regions)

Transistor Ro (output resistance) is optimum: R0 = Vt / Ic

Dissipated power: P = Vsw x Ic

Cut-off: Ic=0 => R0 is maximum

Saturation: Ic=Ic(max) => Ro is minimum

IntroductionTypical circuit example These are valid topologies: voltage source connected to current source

These ones are not valid topologies: two sources of same type

GateiL

SW

DIdc Vdc

GateiL

SW

D IdcVdc

GateiL

SW

D Idc

GateiL

SW

D VdcVdc

The use of low loss components make these topologies not valid

IntroductionBasic Building Blocks PWM – Pulse Width Modulation - The idea is to modulate

the width of a stream of pulses, keeping the carrier frequency constant, such that the low pass frequency spectrum produces the required waveform

LP Filtered signal

HF Stream of

Pulses

PWM in Wikipedia

IntroductionBasic building blocks Inductors – driven by cte voltage source Capacitors – driven by cte current source

Diodes –2nd and 4th quadrants Switches – 1st and 3rd quadrants

C

v

i

i = C dv/dt

E = ½ * C v2

V(s)=I(s) / sC

Current integration

t

v0

i = constant

v = v0 + t i

/ C

L

v

i

V = L di/dt

E = ½ * L i2

I(s)=V(s) / sL

Voltage integration

t

i0

v = constant

i = i0

+ t v / L

vd

id

vd

id

vd(on) = Rd(on) id

E = 0

vd(off) = Rd(off) id

id

vd

On

Off

TurnOff

TurnOn

vsw

isw

vsw

isw

vsw(on) = Ron isw(on)

E = 0

vsw(off) = Roff isw(off)

TurnOff

TurnOn

IntroductionPutting it all together Spontaneous switching Forced switching

D1

D1N4002V2

FREQ = 60VAMPL = 10VOFF = 0

R1

1K

V3

FREQ = 60VAMPL = 10VOFF = 0

D2

D1N4002

L1

10uHC1

5u

0V

IV V

Gate

iLSW

C D

L

RvD

vSW

Some power electronics devicesThe ideal unidirectional switch Unidirectional => operation in the 1st quadrant

Switching controlled by Gate port

There are only two stable states: ON or OFF

Ron = 0 and Roff = ∞

Power loss = vsw x isw = 0

Turn on

vsw

isw

vsw

isw

vsw(on) = Ron isw(on)

E = 0

vsw(off) = Roff isw(off)

Turn off

Gate

Instantaneous i-v characteristicGate

iLSW

C D

L

RvD

vSW

Some power electronics devicesThe ideal diode Operation in the 2nd or 4th quadrants

Ron = 0 and Roff = ∞

Spontaneous switching: no Gate port

Switching controlled by

Turn on: voltage Vd ≥ Vth

Turn off: current Id ≤ 0

vd

id

id

vd(on) = Rd(on) id

E = 0

vd(off) = Rd(off) id vd

On

Off

Instantaneous i-v characteristic

Gate

iLSW

C D

L

RvD

vSW

Some power electronics devicesThe thyristor or SCR SCR - Semiconductor-Controlled Rectifier

Conduction only from A to K: Unidirectional switch Turn ON - by a positive pulse at the gate Turn Off – if current through SCR drops below a certain threshold

NOTE: Figures from: http://mysite.du.edu/~etuttle/electron/elect5.htm

Turn on

vsw

isw

vsw

isw

vsw(on) = Ron isw(on)

E = 0

vsw(off) = Roff isw(off)

Turn off

Gate

Instantaneous i-v characteristic

Some power electronics devicesThe Triac It is “equivalent” to two complementary unilateral thyristors in a inverse

parallel connection Conducts in both directions: bidirectional switch Turn ON - by a positive or a negative pulse at the gate Turn Off – if current through the TRIAC drops below a certain threshold

NOTE: Figures from: http://mysite.du.edu/~etuttle/electron/elect5.htm

TurnOff

TurnOn

vsw

isw

vsw

isw

vsw(on) = Ron isw(on)

E = 0

vsw(off) = Roff isw(off)

TurnOff

TurnOn

Instantaneous i-v characteristic

Some power electronics devicesThe power BJT BJT - Bipolar Junction Transistor

Conduction only from C to E: unidirectional switch

Main advantages: Very high commutation speed

good efficiency at low voltages

Very low saturation voltage VCE

Disadvantages Not isolated gate making it to be difficult to drive

Can not handle very high energy levels

NOTE: Figures from www.wikipedia.com

Turn on

vsw

isw

vsw

isw

vsw(on) = Ron isw(on)

E = 0

vsw(off) = Roff isw(off)

Turn off

Gate

Instantaneous i-v characteristic

Some power electronics devicesThe power MOSFET ) MOSFET - Metal Oxide Semiconductor Field Effect Transistor

Bidirectional switch

It is a specific type of MOSFET designed to handle significant power levels

Advantages: high commutation speed

good efficiency at low and medium voltages

isolated gate what makes it easy to drive

Disadvantage Lower speed than the BJTs

Higher saturation voltage VDS

Turn on

vsw

isw

vsw

isw

vsw(on) = Ron isw(on)

E = 0

vsw(off) = Roff isw(off)

Turn off

Gate

Instantaneous i-v characteristic

Some power electronics devicesThe IGBT (Insulated Gate Bipolar Transistor)

IGBT - Insulated Gate Bipolar Transistor

Conduction only from C to E: unidirectional switch

Advantages: high commutation speed good efficiency at medium to high voltages isolated gate what makes it easy to drive Very low saturation voltage VCE (similar to BJT)

NOTE: Figures from www.wikipedia.com

Turn on

vsw

isw

vsw

isw

vsw(on) = Ron isw(on)

E = 0

vsw(off) = Roff isw(off)

Turn off

Gate

Instantaneous i-v characteristic

Some power electronics devicesOthers power electronic devices For your information, there are many others power

electronic devices such as Diac

SIDAC

GTO - Gate Turn-off Thyristor

IGCT - Integrated Gate-Commutated Thyristor

But these ones are less common They are usually used in niche applications

Choice is based on cost, speed, power level and maximum di/dt supported by the device

Some general classes of power electronics circuits Families of solid state power converters categorized

according to their conversion function

AC

Vac1, f1

AC

Vac2, f2

DC

Vdc1

DC

Vdc2

DC-DC

Converters

AC-D

C

Rectifiers

DC-A

C

Inve

rters

DC

Link

AC

-AC

Co

nve

rte

rs

Cic

loco

nve

rte

rs

Example #1Spontaneous switching - Rectifiers

Single phase Three phaseD1

D1N4002

V2FREQ = 60VAMPL = 10VOFF = 0 R1

1K

L110uH

C1

5u

V VI

D1

D1N4002

R1

1KV2

FREQ = 60

VAMPL = 10VOFF = 0

PHASE = 120

D2

D1N4002

L110uH

C1

5u

D3

D1N4002

D4

D1N4002

D5

D1N4002

D6

D1N4002

V3

FREQ = 60

VAMPL = 10VOFF = 0

PHASE = 240

V1

FREQ = 60

VAMPL = 10VOFF = 0

PHASE = 0

I V

V

Smoothinginductance

Example #2Forced switching phase controlled rectifier DC-DC Converter

R320

V2TD = 0

TF = 10nsPW = 30uPER = 100u

V1 = 0

TR = 10ns

V2 = 2

L1

5mh

V3

20V

D1

D1N4002

C1

10n

Q1Q2N2222

R410

I

VV1

FREQ = 60

VAMPL = 50VOFF = 0

PHASE = 0

R3100

X12N1595

V2TD = 3ms

TF = 10nsPW = 0.2ms

PER = 16.6667ms

V1 = 0

TR = 10ns

V2 = 5

L1

5mh

R4

1k

V

V

V

ConclusionResources available Orcad version 16.3 Student Edition – Free

http://www.cadence.com/products/orcad/pages/downloads.aspx

NOTE: The student edition has limitations in terms of # of components, # of pins, etc.

We will publish a copy of the example circuits

The internet has many useful links Search for “ pspice and power and electronics”

References This is one of the best references

Erickson, R. W. & Maksimovic, D., “Fundamentals of Power Electronics,” 2nd Edition, University of Colorado, Boulder, http://ecee.colorado.edu/copec/book/slides/slidedir.html

These are good references as well Ramshaw, E. & Shuumman, D. C., “PSpice Simulation of Power

Electronics Circuits: An Introductory Guide,” Springer Verlag, 1996 Ferrieux, J. P. & Forest, F., “Alimentation à découpage -

Convertisseurs à résonance: principes, modélisation, composants,” Collection technologies, Masson, Paris, 1987, ISBN 2-225-81205-5

Tolyat, H. A. & Campbell, S., “DSP-Based Electromechanical Motion Control,”CRC Press, 2003

Thompson, M. T., “Introduction to Power Electronics,”, 2007, http://www.thompsonrd.com/NOTES%2001%20INTRODUCTION%20TO%20POWER%20ELECTRONICS.pdf

Q & A Thank you

My contact:

Julio Pimentel

jpiment@kylowave.com