Analysis of Predictive Current Regulator for High-Speed IPMSM Operating at Low Sampling to Fundamental Frequency Ratios

At low sampling to fundamental frequency ratios (SFRs), the time delay and current sampling error deteriorate the performances of the current regulator. Therefore, this paper proposes a comprehensive analysis and a tuning method of the PI controller and Internal Model Controller (IMC) with one-step current prediction (OCP) operating under low SFRs. The tuning method analyzes the migration of the closed-loop poles with the electrical speed change and selects the optimal control parameters to improve the system's performance. To enhance the disturbance rejection of the IMC approach, a novel active resistance is also proposed. Simulation and experimental results performed on an interior permanent magnet synchronous motor (IPMSM) have successfully validated the proposed methods. The results show that, the conventional PI design with OCP results in acceptable decoupling and dynamic performances at a minimum SFR of 7.5. While the proposed IMC approach still retains its stability and dynamic performances both at SFR of 7.5 and 5. For disturbance rejection, only the proposed IMC design can achieve enhanced performance at low SFRs.