Repetitive Control for Harmonic Compensation in Three-phase Isolated Matrix Rectifier

Three-phase isolated matrix rectifier (IMR) is a kind of single-stage converters without dc-bus. IMR has the advantages of high transmission efficiency and flexible adjusta-bility of output voltage, which is very suitable for electrical vehicle (EV) chargers. But IMR generates harmonic pollution to the power grid because of its nonlinearity property, which in turn brings disturbances to the output side of IMR. This paper proposes an improved plug-in repetitive controller for the harmonic compensation to three-phase IMR. The proposed controller, which consists of a repetitive controller with a parallel forward path and a conventional PI controller can compensate the harmonic in power grid and attenuate the harmonic currents. For IMR operating at the power frequency, a fractional delay(FD) filter is utilized to approximate the characteristic of the delay and improve the steady-state tracking performance of the proposed controller. Simulation results verify that the proposed control scheme can compensate the harmonics of IMR effectively.