An Indirect Testing Method for the Torque Ripple of Multiunit Permanent Magnet Synchronous Machines

The torque ripple of the permanent magnet synchronous machine (PMSM) is always cared in the machine system, since the torque ripple mainly determines the vibration and stability of the machine. This paper presents an indirect testing strategy for the torque ripple of multiunit PMSMs without using a mechanical load. Through the proposed unit-motor configuration, the curve of the torque can be obtained in the situation that some unit motors are running as generators and some unit motors are running as motors. Then, the additional torque ripple in this situation will be calculated based on the measured parameters. Finally, the torque ripple can be obtained by subtracting the additional torque ripple from the tested torque ripple in the situation without mechanical load.