Annual Meeting and Technology Showcase – Logan, Utah – September 27-28, 2016

Professor of ECE, Purdue University

Dr. Steve Pekarek

Power Electronics and Electric Drives

• Fundamental building blocks of electrified transportation

• Research focused on:– Converter topologies and control

• Wide bandgap devices (higher voltage and current levels)

• Integration of wide-bandwidth control (stability)• Better passives

– Electric machine design and control• Multi-objective optimization• New materials• New topologies

Power Electronics and Electric Drives

• Dragan Maksimovic, CU-Boulder• Bob Erickson, CU-Boulder• Khurram Afridi, CU-Boulder• Dionysios Aliprantis, Purdue• Scott Sudhoff, Purdue• Regan Zane, Utah State• Zeljko Pantic, Utah State

• 10 posters and demos

Power & Machines Faculty Introductions

ProjectsNASA - NRIPI: Sudhoff, Pekarek• Design of electric

machines for traction drives and humanoid robots

• Reduce mass and loss

Navy Electric Ship DesignPI: Pekarek, Sudhoff• Design of Medium

Voltage DC Systems– Components, controls,

stability– Grounding, EMI/EMC

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ProjectsJohn Deere: Control of IPM Drives with WBG DevicesPI: Aliprantis, Pekarek

DOE: A Disruptive Approach to Electric Vehicles Power Electronics PI: Bob Erickson, DraganMaksimovic, Khuram Afridi

5

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Active Rectifier Inverter Load Machine

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Annual Meeting and Technology Showcase – Logan, Utah – September 27-28, 2016

Project supported by US DOEVehicle Technologies OfficePI: Prof. Robert EricksonCo-PIs: Prof. Dragan Maksimovic

Prof. Khurram Afridi

A Disruptive Approach to Electric Vehicle Power Electronics Electrical, Computer and Energy Engineering

University of Colorado Boulder

Project Overview Composite

DC-DCConverter

InverterMotor

VbusVbatt

+

-

+

-

Integrated Charger

3φ-AC

Goals: non-incremental improvements in• Power density (2x)• Average loss (4x)• Film capacitor requirements (2x)• Magnetics size (4x)• Add-on volume of onboard level 2 charger

Approach• Fundamental improvements in converter circuit topology• Compare performance of Si vs. SiC devices• Optimization to minimize loss over standard drive cycles, based on

calibrated converter loss models• Integration of level 2 charger with DC-DC system

An appropriate performance metric for loss-limited converter systems:

Modeling and design of drivetrain power electronics to minimize CAFE loss

Drive cycle histograms• Design of power electronics system architecture and optimization of power component designs to minimize loss over standard drive cycles

• Low-power efficiency disproportionately impacts loss

Boost Composite Converter ArchitectureDissimilar partial-power converter modules:

• Same total silicon area as conventional boost approach

• Total film capacitor size reduced by 3x

• Significantly lower loss at high boost ratios

• Significantly reduced partial-power loss

Dominant loss mechanisms are addressed:• Use of pass-through modes to minimize AC losses• Use of ultra-high-efficiency DC Transformer (DCX) module to

convert most of the indirect power1. H. Chen, K. Sabi, H. Kim, T. Harada, R. Erickson, and D. Maksimovic, “A 98.7% Efficient Composite Converter Architecture with

Application-Tailored Efficiency Characteristic,” IEEE Transactions on Power Electronics, vol. 31, no. 1, pp. 101-110, Jan. 2016.2. H. Chen, H. Kim, R. Erickson and D. Maksimovic, “Electrified Automotive Powertrain Architecture Using Composite DC-DC

Converters,” IEEE Transactions on Power Electronics, 2016.

SiC Composite Boost Prototype• 400 kHz DCX switching frequency• 200 kHz buck and boost switching

frequency• Employs 900 V 10 mΩ SiC

MOSFETs• Planar magnetics use ELP43 and

ELP64 ferrite coresSize of high density prototype• Volumetric power density 23 kW/L• Gravimetric power density 18.7

kW/kg• Rated power 27 kW continuous,

39 kW peak for these SiC devices

60 kW motor-generator set for testing EV drivetrain power electronics

Measured Si composite boost efficiencyat 250 V : 650 V Ferrite planar transformer used in 60 kW

prototype

Loss model efficiencyMeasured efficiency•

Calibrated loss models of SiC converter modules

Efficiency comparison (250-to-650 V, 15 kW)

SiCboost

Si IGBT boost

Si MOSFET composite

SiC MOSFET composite

Summary of converter technologies: EV drivetrain boost

• Brute-force device replacement of Si with SiC in the conventional boost converter yields relatively small improvements in efficiency and converter Q

• Capacitor size is driven by rms current, and is unaffected by increase of switching frequency or use of SiC devices

• Composite architecture + SiC devices = transformative improvement• Composite architecture addresses fundamental loss mechanisms• SiC enables increased switching frequency and much reduced magnetics size• In the composite architecture, SiC yields very high peak and average efficiency,

much higher converter Q, and very high power density

Converter Si-IGBTConventional boost

Si-MOSFETComposite boost

SiC-MOSFETConventional boost

SiC-MOSFETComposite boost

Switching frequency 10 kHz 20 kHz 240 kHz 240 kHz

CAFE efficiency 94.3 % 98.2 % 96.9 % 98.3 %

CAFE Q factor 22.2 55.3 34.7 58.6

Magnetic volume [relative to Si IGBT] 100% 108% 40% 24%

Film capacitor size [relative to Si IGBT] 100% 30% 100% 30%

Integrated SiC Charger

Re-use of composite dc-dc boost modules

120 Hz energy storage capacitor

plus 240 VAC interface module

SiC prototype, 6 kW• 900 V 10 mΩ devices• 120 kHz switching frequency• Planar magnetics

• 10 kHz, 800 V DC bus• Same module used with Si composite boost and SiC composite boost systems• Each phase employs SiC 1200 V 25 mΩ MOSFETs• Rated power: 30 kW, power density: 16 kW/L

Comparison with Si IGBTs, based on calibrated loss models:

SiC Inverter

1200 V Si IGBT 1200 V SiC MOSFET

Semiconductor area 3464 mm2 1801 mm2

Rated current, per phase 360 A 360 A

UDDS avg effcy/Q 97.3%/35.8 99.0%/101

HWFET avg effcy/Q 99.0%/96.1 99.5%/195

US06 avg effcy/Q 98.3%/58.9 99.5%/199

Annual Meeting and Technology Showcase – Logan, Utah – September 27-28, 2016

Scott D. SudhoffMichael and Katherine Birck Professor of Elect. and Comp. EngineeringSchool of Electrical and Computer Engineering | Purdue UniversityEditor-in-Chief, IEEE Power and Energy Technology Systems Journal

sudhoff@purdue.edu | 765-494-3246 | Wang 2057 465 Northwestern Avenue | West Lafayette, IN 47907

Research Related to Electrified Vehicles

Steel Characterization and Hi-Si Fe

17

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Analyticalish (Non-FEA) Magnetic Analysis

18

Tooth Flux Density

Backiron Flux Density

19

Analyticalish (Non-FEA) Structural Analysis

FEA Model Relative errorInner bridge 18.99 MPa 19.51 MPa 2.75 %Outer bridge 15.85 MPa 15.47 MPa -2.39 %

Rotationally Asymmetrical Machines

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TABLE 6 AS-PMSM Design Model and FEA Torque

Rotor Speed (rpm)

Design Model

Torque (Nm)

3-D FEA Torque (Nm) % Error

1000 rpm 18.0 17.6 2.20 2236 rpm 8.10 7.70 5.00 5000 rpm 3.70 3.40 8.10

Multi-PM-Pole Machines

21

Passive Component Design

22

AC InductorsPM InductorsCommon Mode InductorsLF TransformersHF Transformers

http://www.nrel.gov/images/site_hpphoto_pv.jpg

Metamodel-Based Sub-System Design

23

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Metamodel-Based System Design

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Panelists• Dr. Robert Erickson, Carline and Wilfred Slade

Professor, University of Colorado-Boulder

• Dr. Scott Sudhoff, Michael and Katherine Birck Professor of Electrical and Computer Engineering, Purdue University

• Dr. Tao Wang, Engineering Manager, Control Electronics (Hybrid Vehicles), General Motors

Power Electronics and Electric Drive