A Study of the Relationship between Acoustic Noise and Torque Pulsation in Permanent Magnet Synchronous Motors

Acoustic noise and torque ripple are some of the undesirable performance indices in the design of electric motors. In fact, knowing the relationship between the two quantities can be very crucial, especially in the optimization process. For instance, where an increase in torque ripple is known to exacerbate the noise and vibrations, the two quantities could be considered as non-conflicting objectives. What this means is that minimizing one quantity could result in the optimization of the other without necessarily treating the two as mutually exclusive objectives. This paper, therefore, explores the correlation, if any exists, between torque ripple and the acoustic noise performance of the electric motor. The procedure involves exploring the design space of a 10 pole 12 slot surface-mounted permanent magnet synchronous motor to compute the torque ripple and the corresponding acoustic noise related to thousands of different motor configurations. Then, a statistical analysis is performed to establish the correlation strength between torque ripple and acoustic noise.