Study on Steady-State Errors for Asymmetrical Six-Phase Permanent Magnet Synchronous Machine Fault-Tolerant Predictive Current Control

The traditional pulsewidth modulation predictive control (PPC) has poor steady-state performance when used for fault-tolerant control of multi-phase machine drives, because this paper finds that PPC theoretically has a large steady-state error when tracking ac signals. Thus, an improved PPC regulator is proposed, which can rapidly and accurately track ac current references and realize decoupling control among phase currents. The proposed method is developed by redesigning the transfer function of the conventional PPC to a resonant form, reducing the amplitude and phase error in the conventional approach. By making the resonant frequency of the resonant term track the machine frequency, the amplitude and phase response of the system at the working frequency are close to zero. Thus, the proposed R-PPC features fast-response-performance and high-ac-tracking-accuracy. The effectiveness of the proposed method has been verified on a surface-mounted permanent magnet synchronous machine by experiments.