Development Of A Novel Zero-Voltage And Zero-Current-Switching Full-Bridge PWM DC/DC Converter

Fhase-shifted full-bridge zero-voltage and zero-current-switching (ZVZCS) PWM converter resets the primary current during the freewheeling period to realize the ZVS of leading-legs and the ZCS of lagging-legs, which overcomes some obvious disadvantages of phase-shifted full-bridge zero-voltage-switching(ZVS) converter. At present, the existing methods to reset primary current have some limitations such as loss increasing, difficult control and complicated manufacturing technnology, etc..A novel ZVZCS converter is proposed which uses a coupled output inductor. Compared with the previously proposed topologies, a simple auxiliary circuit that consists of neither lossy components nor active switchings is used. The voltage stress of the secondary rectifier diode is kept as small as that of hard-switching converter. The current to charge clamping capacitance is self-adjusted in accordance with the load at light condition, which guarantees high efficiency over wide load range. Diode D_c of auxiliary circuit is softly commutated and it's of reverse recovery is minimized.The principle of the novel converter is analyzed, and the foundations of parameter-design are presented. Futhermore, parameter calculation formulas at different modes are deduced. A simulation is performed successfully to analyze the converter's working characteristics using Pspice9.2, different parameters' effects on performance of converter are analyzed and the optimized parameters have been obtained. One 1KW ZVZCS soft-switching power supply based on this topology is developed, and the design process of main circuit, control circuit, protection circuit and high-frequency transformer are presented, lastly, working waveforms and efficiency of the converter are measured on prototype.Theory analysisses and experiments have showed that this novel converter can realize ZVS of leading-legs at the condition of more than one-three full load and ZCS of legging-legs in the whole range of load. High efficiency has bee reached over wide range of load. So this novel converter has a wide application and huge economy effect in power converting field, especially in the high voltage and high power feild where IGBT is used as the main switch.