Comparative Study on Pulse Pattern Optimization for High-Speed Permanent Magnet Synchronous Motors

Optimal pulse patterns (OPPs) have many advantages for permanent magnet synchronous motor (PMSM) drives, such as low switching frequency, and low current harmonic distortion at medium to high speeds. Selective harmonic mitigation is an effective approach to generate optimal switching pulse patterns by minimizing the entire harmonic content instead of eliminating individual harmonics. A proper offline optimization method is required for selective harmonic mitigation to maximize the power utilization of PMSMs. This paper discusses two optimization techniques: 1) genetic algorithm (GA) and 2) FMINCON solver for obtaining the OPPs for a two-level inverter. Both the methods are studied with different pulse number to calculate the optimal switching angles that can provide less total harmonic distortion (THD) of phase currents. Comparative simulations are performed to validate the effectiveness of the optimization approach and it is found that FMINCON solver can optimize the switching angles better than GA with an approximately 4% reduction in the phase current THD.