Parallel structure 6k ± 1 repetitive control for three-phase PWM inverters

In this paper, a parallel structure repetitive control scheme is proposed for three-phase PWM inverters to compensate 6k ± 1th order harmonics. This new control scheme divides conventional repetitive control into two branches in parallel structure. By this design, it avoids using filters in series, thus achieving higher gains for targeted harmonic groups than other 6k±1 repetitive controllers. Besides, the proposed control scheme reduces the number of delay units required to one third of that in conventional repetitive control schemes, thereby offering faster convergence rate and better transient performance. Stability and convergence of this approach are proved mathematically. Experimental results are provided to show the effectiveness of the proposed control scheme.