Compact On-board Drivetrain-Integrated Level II Electric ... · Recently proposed drivetrain...
Transcript of Compact On-board Drivetrain-Integrated Level II Electric ... · Recently proposed drivetrain...
Usama Anwar, Hyeokjin Kim, Hua Chen, Robert Erickson, Dragan Maksimović and Khurram K. AfridiColorado Power Electronics Center, ECEE Department
University of Colorado Boulder
Compact On-board Drivetrain-Integrated Level II Electric Vehicle Charger
SELECT Annual Meeting and Technology Showcase – Logan, Utah – September 27-28, 2016
INTRODUCTION On-board electric vehicle (EV) charger size and weight reduction helps:
Incorporate higher power (Level II) on-board chargers
Minimize vehicle styling constraints
Reduce range anxiety
Accelerate EV adoption
Existing approaches to incorporate on-board Level II chargers: On-board charger separate from drivetrain power electronics – adds excessive size and weight
On-board charger integrated with drivetrain using traction motor windings – adds complexity, cost and reliability issues
Recently proposed composite boost converter provides opportunity for new approaches for charger integration Composite boost converter has superior performance than conventional boost converter
Comprises buck, boost and DCX modules
Utilizes lower voltage devices due to stacked nature
Modular nature allows multiple options for on-board charger integration
ALTERNATIVE DRIVETRAIN INTEGRATED CHARGER ARCHITECTURES
Architecture A
Bridgeless Boost + PSFB converter
Achieves low level of integration
Only utilizes composite converter filter
SELECTION OF DRIVETRAIN INTEGRATED CHARGER ARCHITECTURE
SUMMARY AND CONCLUSIONS
OPPORTUNITY Goal of research is to identify and develop optimal way to integrate on-board charger with EV drivetrains utilizing
composite boost converter: Achieve on-board Level II charging functionality with minimal additional size and weight, while maintaining high efficiency
Maximize reuse of existing drivetrain parts
Minimize additional switches and passive components
Architecture A
Architecture B
Architecture B
Rectifier + PFC Boost Isolated DC/DC converter + Buck converter
Achieves high level of integration
Reduced efficiency due to hard switching in Isolated PFC Boost converter
Architecture C
Architecture D
Architecture C
Bridgeless Boost + DAB + Buck converter
Achieves high level of integration
Energy buffering at two places
Architecture D
Bridgeless Boost + DAB + Buck converter
Three winding transformer reduces weight
Achieves high level of integration
Energy buffering at two places
Architecture D selected as it offers best tradeoff between weight and losses
Designed using Silicon super-junction FETs
Interfaced with existing drivetrain by adding third winding to DCX transformer
Energy buffering at two places reduces capacitor weight
Added Module:
PFC bridgeless boost converter + H-bridge + one transformer winding
Proposed architectures compared in terms of added weight and losses
Factors considered for comparison: Weight of added charger module components:
capacitors, inductors, heat sink
Losses introduced by added components
Architecture Added Weight [kg] Losses [W]
A 2.67 238
B 1.97 322
C 2.07 268
D 1.90 265
Recently proposed drivetrain composite boost converter well suited for on-board charger integration
Four alternative approaches for achieving charger integration explored and quantitatively compared Selected charger architecture only adds bridgeless boost converter, one
H-bridge and one extra winding to the existing converter
PFC stage of the selected charger architecture uses a bridgeless boost converter The converter is operated in DCM at 20 kHz
Hybrid feedforward control architecture is used to achieve PFC functionality
Effective zero crossing mitigation techniques employed to achieve natural commutation of input current between the half bridge legs
Second stage DAB is controlled by introducing phase shift between primary and secondary H-bridges
Third stage boost converter regulates battery power by controlling input current. Current reference is generated by sensing input voltage of the converter
POWER FACTOR CORRECTION STAGE
Measured zero crossing
Hybrid feedforward control eliminates high bandwidth current sensor
Control objective: 𝑖𝑖𝑛 𝑇𝑠 =𝑣𝑖𝑛
𝑅𝑒
Inductor current
𝑖𝑖𝑛 𝑇𝑠 =𝑇𝑠2𝐿
.𝑑2
1 −𝑣𝑖𝑛𝑣𝑜𝑢𝑡
𝑣𝑖𝑛
Duty cycle modulation equation:
𝑑 =2𝐿
𝑅𝑒𝑇𝑠1 −
𝑣𝑖𝑛𝑣𝑜𝑢𝑡
Zero crossing distortion mitigated by switching both switches with same duty cycle command around input voltage zero crossing
Efficiency
Switching Waveforms
Low Power
6.6kW Results
Input voltage and current and output voltage waveforms
REFERENCES U. Anwar, D. Maksimovic and K.K. Afridi,
“Generalized Hybrid Feedforward Control of Pulse Width Modulated Switching Converters,” IEEE Workshop on Control and Modeling for Power Converter (COMPEL), Trondheim, Norway, June 2016.
B. Whitaker, A. Barkley, Z. Cole, B. Passmore, D. Martin, T. McNutt, A. Lostetter, J. S. Lee, K. Shiozaki, “A High-Density, High-Efficiency, Isolated On-Board Vehicle Battery Charger Utilizing Silicon Carbide Power Devices,” IEEE Transactions on Power Electronics, vol. 29, no. 5, May 2014.
J. Sun, “On the Zero-Crossing Distortion in Single-Phase PFC Converters,” IEEE Transactions on Power Electronics, vol. 19, no. 3, May 2004.
R.W. Erickson and D. Maksimović, Fundamentals of Power Electronics, Second Ed., Kluwer Academic Publishers, 2001
ISOLATION AND REGULATION STAGESDual Active Bridge Isolation Stage
Each half bridge switches at ~50% duty cycle
Output voltage regulated by control of primary and secondary phase shifts
ZVS can be achieved on both primary and secondary H-bridges
DAB output capacitor performs energy buffering
Input and output voltage waveform
Boost Power Regulation Stage
Regulates power flowing into the battery
Controls input current and generates current reference by sensing input voltage
Simulation Results
Inductor current waveform
Boost converter topology, model and control architecture
Converter simulation waveforms