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

Power Electronics and Electric Drives

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

– Electric design and control • Multi-objective optimization • New materials • New topologies Power & Faculty Introductions • 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 Projects NASA - NRI Navy Electric Ship PI: Sudhoff, Pekarek Design • Design of electric PI: Pekarek, Sudhoff machines for traction • Design of Medium drives and humanoid Voltage DC Systems robots – Components, controls, • Reduce mass and loss stability – Grounding, EMI/EMC

4 Projects John Deere: Control of DOE: A Disruptive IPM Drives with WBG Approach to Electric Devices Vehicles Power PI: Aliprantis, Pekarek Electronics PI: Bob Erickson, Dragan Maksimovic, Khuram Afridi

Source Machine Active Rectifier DC Bus Inverter Load Machine eas eal Ls Rs Lfs Lf l Rl Ll

Ldc Rdc S1 S2 S3 S1 S2 S3 ebs ebl Ls Rs Lfs Lf l Rl Ll

Cdc1 Cdc2 ecs S4 S5 S6 S4 S5 S6 ecl Ls Rs Lfs Lf l Rl Ll

Cwgs Cwgs Cwgs Ldc Rdc Lb Cwgl Cwgl Cwgl Cgb Sb Rb Db Lb Cgb Buck Converter DC Load

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

A Disruptive Approach to Electric Vehicle Power Electronics Electrical, Computer and Energy Engineering University of Colorado Boulder Project supported by US DOE Vehicle Technologies Office PI: Prof. Robert Erickson Co-PIs: Prof. Dragan Maksimovic Prof. Khurram Afridi Project Integrated Charger + + Overview Composite Motor Vbatt DC-DC Vbus Inverter Converter - - 3φ-AC

Goals: non-incremental improvements in • Power density (2x) An appropriate performance metric • Average loss (4x) for loss-limited converter systems: • 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 Modeling and design of drivetrain power electronics to minimize CAFE loss

• Design of power electronics system Drive cycle histograms architecture and optimization of power component designs to minimize loss over standard drive cycles • Low-power efficiency disproportionately impacts loss Boost Composite Converter Architecture Dissimilar 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 (DCX) module to convert most of the indirect power

1. 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 cores Size 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 Measured Si composite boost efficiency at 250 V : 650 V Ferrite planar transformer used in 60 kW prototype

Calibrated loss models of SiC converter modules

Loss model efficiency • Measured efficiency 60 kW motor-generator set for testing EV drivetrain power electronics Efficiency comparison (250-to-650 V, 15 kW)

Si MOSFET SiC MOSFET composite composite

SiC boost

Si IGBT boost Summary of converter technologies: EV drivetrain boost

Si-IGBT Si-MOSFET SiC-MOSFET SiC-MOSFET Converter Conventional boost Composite boost Conventional boost Composite 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 100% 108% 40% 24% [relative to Si IGBT] Film capacitor size 100% 30% 100% 30% [relative to Si IGBT]

• 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 Integrated SiC Charger

120 Hz energy storage capacitor Re-use of composite dc-dc boost modules plus 240 VAC interface module SiC prototype, 6 kW • 900 V 10 mΩ devices • 120 kHz switching frequency • Planar magnetics SiC Inverter

• 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:

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

Research Related to Electrified Vehicles

Scott D. Sudhoff Michael and Katherine Birck Professor of Elect. and Comp. Engineering School of Electrical and Computer Engineering | Purdue University Editor-in-Chief, IEEE Power and Energy Technology Systems Journal [email protected] | 765-494-3246 | Wang 2057 465 Northwestern Avenue | West Lafayette, IN 47907 Steel Characterization and Hi-Si Fe

-3 10 -i Characteristic 3

2 2 2 T dB f = dt 1 eq 22∫ ∆Bπ 0  dt

0 , Vs αβ−

s 1 N nnT 2 feq Bmax  kfe dB -1 p= k f + dt ld∑ h, n    2 ∫  = f B B dt n 1 bb    b  0    -2 Measured Estimated Anhysteretic Hysteresis Loss Eddy Current Loss Fitted Anhysteretic

-3 -60 -40 -20 0 20 40 60 i , A p 17 Analyticalish (Non-FEA) Magnetic Analysis

Backiron Flux Density

Tooth Flux Density

18 Analyticalish (Non-FEA) Structural Analysis

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

19 Rotationally Asymmetrical Machines

TABLE 6 AS-PMSM Design Model and FEA Torque Design Speed 3-D FEA Model % Error (rpm) Torque (Nm) Torque (Nm) 1000 rpm 18.0 17.6 2.20 2236 rpm 8.10 7.70 5.00 5000 rpm 3.70 3.40 8.10

20 Multi-PM-Pole Machines

21 Passive Component Design

AC Inductors PM Inductors Common Mode Inductors LF HF Transformers

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

22 Metamodel-Based Sub-System Design

KM n * *1/3 Mk, M= cEM M∏ ( J pk E M+ b M, k ) , k=1 KP n 2 *1/3 *1/3 Pk, Pdc= cKE P J M∏ ( J pk E M+ b P, k ) . k=1

23 Metamodel-Based System Design

24 Power Electronics and Electric Drive 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