High performance single-stage transformer-isolated AC/DC converter

This paper proposes a high performance single-stage transformer isolated AC/DC converter to give high input power factor and low current distortion on the input side and provide stable and low ripple dc voltage on the output side. The proposed AC/DC converter only employs four switches to perform the power factor correction in input side and provide regulation of the output dc voltage magnitude. Thus, its cost is lower than the others. It has a common arm between the rectifier and inverter, and adopts an appropriate switching strategy. A significant reduction in the conduction losses is achieved, since 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. A simple pulse-width modulation control strategy is employed to synthesize a suitable low harmonics sinusoidal waveform for the input current and achieve well dynamic regulation. A design example of 500W single-stage transformer-isolated AC/DC converter is examined to assess its performance.