Suppression of Dead-Time Distortion Through Revised Repetitive Controller in PMSM Drives

This paper proposes a new dead-time compensation method for voltage-source inverters (VSIs) used in permanent-magnet synchronous motor (PMSM) drives. The proposed technique is developed based on the revised repetitive controller (RRC) to reduce current harmonics and distortion, which is essential to improve efficiency, rotor position observer performance at very low speed, and self-commissioning accuracy. This method significantly suppresses the sixth-order harmonics and its multiples in synchronous reference frame and reduces the current total harmonic distortion (THD) without depending on the precise current sampling especially in the zero-crossing region. Unlike in most average value theory or pulse based compensations, it does not require additional hardware. It is also shown that RRC-based compensation has better robustness against motor parameter variations than disturbance observer based methods and requires very low computational effort. Compared to other repetitive controllers (RC), the proposed RRC is dedicated for dead-time compensation and can easily be integrated because of its simpler structure. In addition, it can be conveniently activated or deactivated on the fly, which adds more flexibility to the control overall algorithm. The effectiveness of the proposed method is validated by theoretical analysis, spectrum analysis, as well as simulation and experimental results.