Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power...

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Advanced Thermal Control Enabling Cost Reduction for Automotive Power Electronics Thomas Abraham, Kenneth Kelly, and Kevin Bennion National Renewable Energy Laboratory Andreas Vlahinos, Advanced Engineering Solutions, LLC NREL/PR-540-43819 Presented at the 2008 ANSYS Automotive Conference sponsored by ANSYS held September 4-5, 2008 in Dearborn, Michigan This presentation is subject to Government rights. NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by Midwest Research Institute • Battelle.

Transcript of Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power...

Page 1: Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power Electronics Thomas Abraham, Kenneth Kelly, and Kevin Bennion. National Renewable Energy

Advanced Thermal Control Enabling Cost Reduction for Automotive Power ElectronicsThomas Abraham, Kenneth Kelly, and Kevin BennionNational Renewable Energy Laboratory

Andreas Vlahinos, Advanced Engineering Solutions, LLC

NREL/PR-540-43819Presented at the 2008 ANSYS Automotive Conference sponsored by ANSYS held September 4-5, 2008 in Dearborn, Michigan

This presentation is subject to Government rights.

NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by Midwest Research Institute • Battelle.

Page 2: Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power Electronics Thomas Abraham, Kenneth Kelly, and Kevin Bennion. National Renewable Energy

Industry and Academia

DOE’s Advanced Power Electronics and Electric Machines (APEEM) Research

Oak Ridge National Laboratory (ORNL)Lead: Power Electronics & Electric Machines R&D

National Renewable Energy Laboratory (NREL)Lead: APEEM Thermal Control R&D

+ Other Industry Partnersand Universities

Page 3: Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power Electronics Thomas Abraham, Kenneth Kelly, and Kevin Bennion. National Renewable Energy

Motivation

• Most aggressive target of FreedomCAR program is the cost (2020 target is $8/kW for a 55 kW traction system).

• Meeting the cost target is critical for greater penetration of the vehicles market .

• NREL’s Advanced Power Electronics team is working on next-generation advanced cooling technologies (jets/sprays/micro-channels with single or two-phase) and novel packaging topologies.

• Advanced cooling technologies are used in conjunction with novel packaging topologies for identifying low-cost materials for cost (and weight) reductions while meeting the targets of performance and reliability.

Page 4: Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power Electronics Thomas Abraham, Kenneth Kelly, and Kevin Bennion. National Renewable Energy

Description of Technology

TIMDBCsolder

BH

RRRTTQ++

−=

)( Silicon Chip

Solder

Direct Bond CopperCu, AlN, Cu

Thermal Paste

Base Plate, Heat Sink

Pin FinsTB, Base Plate Temp.

TH, IGBT Temp.

TC, Coolant Temp.Q heat

)( CB TTAhQ −=

Page 5: Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power Electronics Thomas Abraham, Kenneth Kelly, and Kevin Bennion. National Renewable Energy

Topologies

Baseline TopologyTopology 1 (very similar to the baseline topology, which uses Thermal Interface Material)

Topology 2 (Base plate cooling; does not involve Thermal Interface Material) Topology 3 (Direct Cooling of Direct

Bonded Copper)

Page 6: Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power Electronics Thomas Abraham, Kenneth Kelly, and Kevin Bennion. National Renewable Energy

Thermal Materials Exploration Study – Steps

Thermal Materials Exploration Study

Part 1:

Exploring tradeoffs between thermal performance and cost for several topologies

Part 2:Evaluation of Thermal

Stress andReliability Aspects

Part 3:Emerging technologies: 1)LTCC substrates 2)Organic substrates

• Performance: Peak temperatures of the switching devices (IGBTs and diodes) need to be below 150oC.

• Reliability: Power electronics need to meet life-cycle target of 15 years.

Page 7: Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power Electronics Thomas Abraham, Kenneth Kelly, and Kevin Bennion. National Renewable Energy

Thermal Materials Exploration Study – Comments

• Two layers that have potential opportunities for cost reduction are the substrate and the cold plate.

• Today’s preferred substrate, Aluminum Nitride (AlN) is expensive.

• Low-cost LTCC technology has been well demonstrated in automotive electronics applications. Several issues, notably thermal disadvantages have slowed down the spread of this substrate technology [1].

• Silicon nitride (SiN) as a substrate would make economic sense if the cost is reduced to $5 per pound [2].

1. Fairchild, M.R., Snyder, R.B., Berlin, C.W., and Sarma, D.H.R., “Emerging Substrate Technologies for Harsh-Environment Automotive Electronics Applications,” SAE 2002-01-1052.

2. Das, S., and Curlee, T.R., “The Cost of Silicon Nitride Powder: What Must It Be To Compete?” 1992, ORNL-6694.

Page 8: Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power Electronics Thomas Abraham, Kenneth Kelly, and Kevin Bennion. National Renewable Energy

Materials Exploration – Topology 1

Alternate materials are explored for each layer

Page 9: Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power Electronics Thomas Abraham, Kenneth Kelly, and Kevin Bennion. National Renewable Energy

Verification of CFD Model with Test

CFD Test

Average Heat Transfer Coefficient

(W/m2.K) 18,350 18,481

CFD (using Fluent) Test

Page 10: Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power Electronics Thomas Abraham, Kenneth Kelly, and Kevin Bennion. National Renewable Energy

”What-If” option of Design Explorer in “ANSYS Workbench Thermal Simulation” is used to automate materials exploration studies

Heat Transfer Coefficient = 18,350 W/(m^2.K)

Coolant Temperature = 105 oC

Heat load per IGBT heat load = 85 WHeat Load per Diode = 35 W

Thermal Conductivity is varied for all the layers according to

the material

kcoldplate ksolder ksubstrate kbaseplate

Bulk material costs are assigned on a volumetric

basis

Page 11: Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power Electronics Thomas Abraham, Kenneth Kelly, and Kevin Bennion. National Renewable Energy

Materials combination for cost reduction – Topology 1

Low-cost combination that meets the performance target (Cu-Mo, Graphite, SiN-Ideal)

Cost -> 842 Peak Temp -> 142 OC

Low-cost combination that meets the performance target (Cu-Mo, Graphite, Alumina, an LTCC substrate)

Cost -> 889 Peak Temp -> 149 OC

Page 12: Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power Electronics Thomas Abraham, Kenneth Kelly, and Kevin Bennion. National Renewable Energy

Substrate Materials for Cost Reduction – Topology 1

500 1000 1500 2000 2500 3000 3500115

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Cost per IGBT Diode pair*1000 ($)

Max

imum

Tem

pera

ture

(C)

Maximum Temperature Vs Cost Aluminum Nitride AINALN, AL-501ALN, AL-502AL-503AL-504AN75WAlumina, Al203AL203, AL-600AL2O3, AL-601AL2O3, AL-602AL203, AL-603AL2O3, AL-604AL203, AL-605AL2O3, AL-610Boron Nitride, BO-502Silicon Nitride, S1-501Silicon Nitride, IdealBeryllium Oxide (BeO)

Silicon nitride, ideal

Alumina, an LTCC substrate

Page 13: Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power Electronics Thomas Abraham, Kenneth Kelly, and Kevin Bennion. National Renewable Energy

Base Plate Materials for Cost Reduction – Topology 1

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Maximum Temperature Vs Cost

Copper Cu-Mo Cu-Tungsten AlSiC

Cu-Mo is a candidate base plate material (used in Prius)

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Materials Exploration – Topology 2

• First level text – Arial 28 pt.– Second level text – Arial 28 pt.

• Third level text – Arial 24 pt.– Fourth level text – Arial 22 pt.

• Fifth level text – Arial 20 pt.

Base Plate Cooling

Page 15: Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power Electronics Thomas Abraham, Kenneth Kelly, and Kevin Bennion. National Renewable Energy

Materials Combination for Cost Reduction – Topology 2

Low-cost combination that meets the performance target (Cu-Mo, SiN-Ideal)

Cost -> 662 Peak Temp -> 132 OC

Low-cost combination that meets the performance target (Cu-Mo, Alumina, an LTCC substrate)

Cost -> 682 Peak Temp -> 148 OC

Cost with Topology 1 -> 889

Page 16: Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power Electronics Thomas Abraham, Kenneth Kelly, and Kevin Bennion. National Renewable Energy

Substrate Materials for Cost Reduction – Topology 2

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Max

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Maximum Temperature Vs Cost

Aluminum Nitride AINALN, AL-501ALN, AL-502AL-503AL-504AN75WAlumina, Al203AL203, AL-600AL2O3, AL-601AL2O3, AL-602AL203, AL-603AL2O3, AL-604AL203, AL-605AL2O3, AL-610Boron Nitride, BO-502Silicon Nitride, S1-501Silicon Nitride, IdealBeryllium Oxide (BeO)

Silicon nitride, ideal

Alumina, an LTCC substrate

Page 17: Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power Electronics Thomas Abraham, Kenneth Kelly, and Kevin Bennion. National Renewable Energy

Materials Exploration – Topology 3

Direct Cooling of Direct Bonded Copper

Page 18: Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power Electronics Thomas Abraham, Kenneth Kelly, and Kevin Bennion. National Renewable Energy

Materials Combination for Cost Reduction – Topology 3

Low-cost combination that meets the performance target (SnPb(63/37), SiN-Ideal)

Cost -> 339 Peak Temp -> 130 OC

Low-cost combination that meets the performance target (SnPb(63/37), Alumina, an LTCC substrate)

Cost -> 354 Peak Temp -> 149 OC

Topology 1 -> 889, Topology 2 -> 682

Page 19: Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power Electronics Thomas Abraham, Kenneth Kelly, and Kevin Bennion. National Renewable Energy

Substrate Materials for Cost Reduction – Topology 3

Silicon nitride, ideal

Alumina, an LTCC substrate

400 600 800 1000 1200 1400 1600 1800 2000115

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Cost per IGBT Diode pair*1000 ($)

Max

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Maximum Temperature Vs Cost

Aluminum Nitride AINALN, AL-501ALN, AL-502AL-503AL-504AN75WAlumina, Al203AL203, AL-600AL2O3, AL-601AL2O3, AL-602AL203, AL-603AL2O3, AL-604AL203, AL-605AL2O3, AL-610Boron Nitride, BO-502Silicon Nitride, S1-501Silicon Nitride, IdealBeryllium Oxide (BeO)

Page 20: Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power Electronics Thomas Abraham, Kenneth Kelly, and Kevin Bennion. National Renewable Energy

Topology Effect on Junction Temperature Effect of Topology on Peformance

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Distance, mm

Tem

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ture

, o C

Baseline Topology 1Topology 2Topology 3

Complex interaction between spreading and convection

Direct Backside Cooling

Baseline

h = 18,350 W/(m2.K)

Page 21: Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power Electronics Thomas Abraham, Kenneth Kelly, and Kevin Bennion. National Renewable Energy

Thermal Resistances – Contributions

100% 68% 61%

Opportunity for further reduction in thermal resistance through surface enhancement

Page 22: Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power Electronics Thomas Abraham, Kenneth Kelly, and Kevin Bennion. National Renewable Energy

Surface EnhancementU = h . A

U = h . 3 A

U = (2.2 h) . A

Effective area would be less than 3. Let’s assume it’s about 2.2:

U = h . (2.2 A) (in the test)

(for modeling purposes)

The assumption above might be all right for a first order approximation:

Baseline, h = 18, 350 W/(m2.K)

Enhanced, h = 2.2 * h = 2.2 * 18, 350 = 40,000 W/(m2.K)

Targeted surface area enhancement is about 3

Page 23: Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power Electronics Thomas Abraham, Kenneth Kelly, and Kevin Bennion. National Renewable Energy

Combined Effects of Topology and Cooling Technology on Junction Temperature

Combined Effects of Topology and Cooling Technology on Performance

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0 1 2 3 4 5 6 7

Distance, mm

Tem

pera

ture

, o C

Baseline Topology 1, htc = 18,350Topology 2, htc = 18,350Topology 3, htc = 18,350Topology 1, htc = 40,000Topology 2, htc = 40,000Topology 3, htc = 40,000

Backside Cooling with surface enhancement

Baseline

Page 24: Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power Electronics Thomas Abraham, Kenneth Kelly, and Kevin Bennion. National Renewable Energy

Conclusions and Future Studies

• Advanced thermal control (advanced cooling technologies and novel packaging topologies) helps to meet FreedomCAR program’s key target of cost.

• Direct Backside Cooling (Topology 3) has the greatest potential for cost reduction.

• Using Advanced Thermal Control, low-cost LTCC substrate (alumina) has the potential to replace the traditional, more expensive HTCC substrate, AlN.

• Surface enhancement provides further opportunity for performance enhancement .

• Future studies would involve reliability aspects and emerging substrate technologies (LTCC and Organic).

Page 25: Advanced Thermal Control Enabling Cost Reduction for ...Cost Reduction for Automotive Power Electronics Thomas Abraham, Kenneth Kelly, and Kevin Bennion. National Renewable Energy

Acknowledgements

• First author acknowledges the inputs from Andrew A. Wereszczak, Govindarajan Muralidharan (Oak Ridge National Laboratory), Rajen Chanchani (Sandia National Laboratory), Dr. Liangyu Chen (NASA Glenn Research Center) and Prof. Jean-Paul Issi.