Single-phase AC/AC converter with capacitor-clamped scheme

A single-phase AC/AC converter with a capacitor-clamped scheme is proposed to act as the nearly unity power factor at the input side, to regulate the DC-link voltage and to provide a stable AC voltage at the output side for the critical load. The AC/DC part of the proposed converter is controlled to generate a unipolar PWM waveform on the AC terminal using four power switches with a voltage stress of half the DC bus voltage. A hysteresis current control, a proportional-integral voltage control and a neutral point voltage compensator are used to perform the input line current tracking, DC-link voltage regulation and neutral point voltage balance, respectively. The DC/AC part of the proposed converter is controlled to generate a stable and clean sinusoidal output voltage to the critical load. Experimental results based on a laboratory prototype were implemented to verify the validity and effectiveness of the proposed control strategy.