A Generic Digital $nk \pm m$ -Order Harmonic Repetitive Control Scheme for PWM Converters

In this paper, a generic digital nk ± m-order harmonic repetitive control ( nk ± m RC) scheme is presented for constant-voltage constant-frequency pulsewidth-modulation (PWM) converters to track/remove any nk ± m-order harmonic frequencies efficiently, e.g., 4k ± 1-order harmonics for single-phase converters or 6k ± 1-order harmonics for three-phase converters. Compared with conventional RC, the proposed nk ± m RC occupies less data memory and can achieve zero-error tracking or perfect disturbance rejection of nk ± m-order harmonics at much faster error convergence rate. What is more, the proposed RC provides a unified formula for various RC schemes. Application examples of 6k ± 1-RC-controlled three-phase PWM inverter and 4k ± 1-RC-controlled single-phase PWM inverter demonstrate the effectiveness and advantages of the proposed RC scheme.