A novel high input power factor soft-switching single-stage single-phase AC/DC/AC converter

This paper proposes novel soft-switching single-stage single-phase ac/dc/ac converter to give high input power factor and low current distortion on the rectifier side and provide clean and stable ac voltage on the inverter side. In the proposed converter, besides operating at constant frequency, all semiconductor devices operate at soft-switching without additional voltage stress and current stress. A significant reduction in the conduction losses is achieved, since the circulating current for the soft switching flows only through the auxiliary circuit and a minimum number of switching devices are involved in the circulating current path, and the rectifier in the proposed converter uses a single converter instead of the conventional configuration composed of a four-diode front-end rectifier followed by a boost converter. An average-current-mode control is employed in the rectifier side of proposed converter to detect the transition time and synthesize a suitable low harmonics sinusoidal waveform for the input current. The sinusoidal pulse-width modulation (SPWM) control strategy is employed in the inverter of proposed converter to achieve well dynamic regulation. A design example of 1000W soft-switching single-stage single-phase ac/dc/ac converter is examined to assess the converter performance.