Accurate Torque Ripple Measurement for PMSM

Torque ripple in permanent-magnet synchronous motors is generally undesirable. Significant work has been done to minimize this torque, either by modifying the mechanical motor design or by careful controller design. Surprisingly, however, little work has been published on the accuracy of torque ripple measurement. A successful measurement requires a mechanical design with readily modeled dynamics, sensors with suitable bandwidth and resolution, a method of applying a smooth load to the motor, and a method for calibrating the measurement. This paper presents a thorough approach to the accurate measurement of torque ripple. The proposed system has been validated by finite-element modeling, analytical calculations, and experimental analysis.