Development of Benchmarking Methods for Electric Vehicle Drive Units 2024-01-2270

As part of the U.S. Environmental Protection Agency’s (EPA’s) continuing assessment of advanced light-duty automotive technologies in support of regulatory and compliance programs, a development project was started to study various test methods to benchmark Electric Drive Units (EDUs) consisting of an electric motor, inverter and a speed-reduction gearset.

Several test methods were identified for consideration, including both in-vehicle testing of the complete EDU and stand-alone testing of the EDU and its subcomponents after removal from the vehicle. In all test methods explored, sweeps of speed and torque test points were conducted while collecting key EDU data required to determine efficiency, including motor torque and speed, direct current (DC) battery voltage and current into the inverter, and three-phase alternating current (AC) phase voltages and currents out of the inverter and into the electric motor. In addition, EDU operational data were collected to ensure consistent repeatable benchmarking conditions, including electric motor/drive temperatures, oil supply pressure, and available Controller Area Network (CAN) bus data.

This paper documents the electric vehicle benchmarking test methods which were evaluated and developed by the EPA and compares the results from the selected test methods and configurations examined. The efficiency data measured by the EPA is also compared to published efficiency data from the technology manufacturer.