Simplified control strategy to improve AC-input-current waveform of parallel-connected current-type PWM rectifiers

A new control method for parallel-connected current-type PWM rectifiers for high-power applications is proposed. To reduce waveform distortion and transient oscillation of the AC supply current, state-feedback control of the AC-side LC filter is introduced. A new method of generating a PWM pattern suitable for the parallel connected rectifiers is proposed to obtain sufficient controllability with a reduced switching frequency of the power devices. A method of balancing DC output currents of the component bridges is shown, and an analysis of the interbridge current is made. The effectiveness of the proposed control strategy is confirmed by experimental investigation employing a test system