Low Vibrations and Improved NVH in Permanent Magnet Synchronous Machines Due to Injection of Flux-Linkage Harmonics

Harmonic currents have a significant influence on the vibration behavior of electrical machines. Nevertheless, it remains a challenge to determine the optimum amplitude and phase position of the harmonic currents. This article concentrates on the injection of flux-linkage harmonics to enable acoustic optimization for permanent magnet synchronous machines (PMSMs). The test bench verification of this method using a commercial drive from a luxury class hybrid car proves that vibrations of the problematic mode zero are almost completely eliminated. The total sound pressure level of the machine is reduced by approximately 10 dB compared to the usual field-oriented control. Besides the advantage on the acoustic behavior, this article evaluates the impact of the harmonic flux-linkage injection on current amplitude, average torque, and efficiency.