Investigation of Losses in Regenerative Testing for a 240-kW Sectored Dual-Three-Phase PMSM

Regenerative testing (RT) as an indirect test method is increasingly attractive in high-power multiple three-phase motor applications since no additional mechanical load is needed. However, the RT may bring additional losses, which cause an abnormal temperature rise in the motor. This paper investigates the losses under RT conditions for a 240-kW sectored dual-three-phase surface permanent magnet synchronous motor (SPMSM). First, the distorted air-gap magnetic field generated by the phase difference between the currents of each set of windings under RT conditions is analyzed. Then the resulting additional losses are calculated, which shows that the losses of the permanent magnets (PMs) are the main additional losses under RT conditions. Finally, the validity of the analysis is demonstrated by the comparison of the calculated losses and the experimental results.

I. Introduction

Owing to the rigorous requirements of the dynamometer system and challenges related to installation, it is difficult and expensive to test high-power motors at full load on the test bench, especially when large-size or high-speed motors are involved [1]. Furthermore, when only one motor is available for testing due to cost considerations, classic back-to-back (BB) bench test methods become impractical.