Experimental Investigation of Efficiency Map for an Inverter-Fed Surface-Mount Permanent Magnet Synchronous Motor

Losses in inverter-fed permanent magnet motors are underestimated by using analytical or numerical approach since additional losses due to extra harmonics of the frequency converter are normally skipped. Further, losses in switches and passive components of the converter and the effect of switching frequencies cannot be numerically taken into consideration. Loss-minimizing control and proper efficiency analysis of inverter-fed permanent magnet motors cannot be achieved if an efficiency map is built based on a numerical investigation of the motors alone. This works first reviews losses in a surface-mount permanent magnet synchronous motor (SPMSM) and frequency converters. The efficiency map of a surface-mount permanent magnet synchronous motor in both motoring and generating mode, voltage source inverter and entire drive considering the effect of the switching frequency and modulation, is experimentally investigated in different load conditions. Finally, an appropriate range of switching frequencies in order to maximize the drive efficiency is recommended through the investigation.