Zero-current-switching PWM power-factor-correction converter

A novel single-phase zero-current-switching pulse-width modulation (ZCS-PWM) power-factor-correction (PFC) converter is presented, which features regulation by conventional PWM, soft commutation, low conduction loss and instantaneous average line current control. Two resonant cells are configured in the presented ZCS-PWM PFC converter to perform soft-switching in the semiconductor devices and the soft commutation of the main switches is achieved without additional 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 proposed rectifier uses a single converter instead of the conventional configuration composed of a four-diode front-end rectifier followed by a boost converter. Seven transition states for describing the behaviour of the ZCS-PWM PFC converter in one switching period are described. A prototype rated at 2.5 kW, operating at 60 kHz, with an input AC voltage of 220 V RMS and an output voltage 400 V DC has been implemented in the laboratory. An efficiency of 97.8% and a power factor over 0.99 has been measured. Analysis, design and the control circuitry are also presented.