Enhanced Anti-Disturbance Capability of Digital Controller for the SPMSM at Low Switching to Fundamental Frequency Ratios

The digital current controller designed directly in the discrete-time domain can generally meet the dynamic requirement of controlling the surface-mount permanent magnet synchronous machine (SPMSM). However, when the switching-to-fundamental frequency ratios are low, the anti-disturbance capability of current controllers will be weakened, leading to potentially unstable operations. After thoroughly studying the inadequacy of the existing controllers, this article proposes an enhanced digital controller by adjusting the plant’s forward channel and feedback channel. The addressed controller can effectively suppress the influence of the back electromotive force and additional disturbance terms regardless of the machine parameter mismatch. As a result, the current tracking response and anti-disturbance capability are significantly improved. Finally, the feasibility and effectiveness of the proposed method have been verified by experiment results on a 1.5-kW SPMSM.