Exploring High Frequency Operation of Motor Drives: Practical Insights on Efficiency and Loss

Abstract:
This work provides a comprehensive investigation of high switching frequency operation in motor drive systems. Two motor drive systems: with and without a stator core are developed and controlled via inverters utilizing Infineon’s 100V 4mOmega OptiMOS silicon technology. The study shows that higher power factor of the coreless system increases inverter efficiency by more than 2 times at maximum load. Motor efficiency increases for both systems due to the reduction of motor losses driven primarily by harmonic loss reduction as evident from the coreless system results. The performance of the coreless system improves significantly with switching frequency, confirming that wideband technologies would be the ideal choice for inverters. Surprisingly, the comparison of motor and system power losses indicate that once the switching frequency for a specific application is determined, motors with lower L/R, such as coreless motors, perform better at lower motor speeds. In contrast, motors with cores that have higher L/R provide better performance at higher motor speeds due to the reduction of harmonic losses.