Zero-Phase Fractional-Order Repetitive Current Control for Permanent Magnet Synchronous Motors

This paper proposes a zero-phase fractional-order repetitive current control scheme for permanent magnet synchronous motors. The repetitive control (RC) is implemented in the disturbance estimation correction term of an extended state observer (ESO), and a zero-phase design approach is developed for the RC through constructing a compensator based on an inverse derived from the internal dynamics of the ESO rather than the plant model, such that the effective suppression of periodic harmonic disturbances and rejection of aperiodic external disturbances can be achieved. To maintain the harmonic suppression performance under different operating speeds, a fractional-order delay based on a finite impulse response filter is developed to ensure that the resonant frequencies of the RC accurately track the harmonic frequencies, such that the highprecision current control of the PMSM system under varying speed conditions can be guaranteed. Comparative experiments demonstrate the effectiveness of the proposed method.