Measurement-Based Optimal Current Angle Identification of an Electric Drive Unit

This work targets analyzing the system efficiency of a permanent magnet synchronous machine (PMSM) and its associated power electronics based on measurements. Therefore, a test bench is built and efficiencies of the motor and the power electronics are measured over the full torque-speed range of the motor under test, where the current angle of the motor and the PWM frequency of the voltage source inverter (VSI) is varied. From these measurements, temperature-harmonized efficiency maps are derived and optimal current angle values for VSI-, PMSM-, and system efficiency are evaluated. In addition, the differences between motor-optimal, inverter-optimal and system-optimal current angles are examined.