Fast Dynamic Current Control of High-Speed SPMSMs With Minimized THDs Based on Optimal Flux Trajectory and Switching Vector Patterns

Space vector modulation (SVM) provides good dynamic control for surface-mounted permanent magnet synchronous machine (SPMSM) drives by realizing reference voltage or flux in each time step. However, high-speed SPMSM drives can suffer from significant switching-induced harmonic distortions due to high electrical frequencies and low carrier ratios. Harmonic-optimized pulse width modulation (PWM) methods like synchronous optimal modulation (SOM) minimize current total harmonic distortion (THD) through offline-optimized pulse patterns (OPPs), but they have poor dynamic response. This paper proposes a fast dynamic current control method for high-speed SPMSM drives that addresses these limitations. The proposed method tracks the optimal flux trajectory (OFT) under low pulse number conditions via space vector synthesis, using optimal switching vector patterns (OSVPs) derived from SOM rather than conventional 7- or 5-section SVM patterns. Hence, this method synergistically combines the advantages of both SVM and SOM, achieving fast current tracking (within 1/6 of an electrical cycle) during transients, while minimizing current THD in steady-state conditions. Additionally, the method is simple, avoiding complex flux observers and high control frequencies, while compensating for control delay and machine parameter uncertainties. Experiments on a prototype high-speed SPMSM drive with pulse numbers ranging from 3 to 15 confirm the method's effectiveness.