Efficiency Estimates of Integrated Two-Speed e-Powertrain System under WLTP Driving Cycle for Electric Vehicle

Efficiency is always one of key metrics for electric powertrain system to make the most of battery stored energy and boost electric vehicle’s range. This paper presents a systematic method to estimate efficiency capability for an integrated two-speed e-Powertrain system. Overall system is modelled in MATLAB/Simulink. Inverter power, voltage and current requirements are defined from system specifications. Inverter losses, efficiencies and thermal conditions are investigated at switching frequencies of SkHz and 12kHz. With both traction motor and gearbox efficiency maps, 93.2% system peak efficiency and 90.2% Worldwide Harmonized Light Vehicle Test Procedure (WLTP) Class 3b driving cycle efficiency are obtained to verify that design targets are met in simulations. A prototype is built to validate system efficiency performance in the thermal chamber during tests.