A modified single-phase h-bridge PWM rectifier with power decoupling

It is well known that single-phase PWM rectifiers suffer from second-order ripple power and subsequent dc-link voltage pulsation. To reduce this low frequency fluctuation of dc-link voltage as well as to obtain the sinusoidal grid current with unity power factor, a modified single-phase H-bridge PWM rectifier consisting of a conventional H-bridge rectifier and a pure passive auxiliary circuit is presented. Through utilization of the extra degree of freedom of the H-bridge, the proposed circuit can achieve power decoupling as well as maintaining basic function of a conventional PWM rectifier without additional power devices, which decreases both the product volume and the cost. The corresponding dc-link ripple reduction control method, with the instantaneous power feedforward loop and the dc-link ripple voltage feedback loop, is also provided. The experimental results based on a 1.3kW prototype verified the feasibility of the proposed method.