Phase-shift Control Of Zvs Pwm Dc-dc Full-bridge Converters Soft-switching Technology And Application

This paper briefly reviews the development of soft-switching technique applied to switch power supply. The operation principle of pulsewidth-modulated (PWM) DC-DC full-bridge (FB) converter is analyzed, and then the nine control methods and the two ways to achieve soft-switching are put forward systematically. In this paper, we only discuss phase-shifted (PS) control and zero-voltage switching (ZVS). The operation principle of the classical PS ZVS PWM DC-DC FB converter is analyzed, then the requirements of its operating under ZVS, its transformer secondary side duty cycle loss and the conditions of current commutation in output diodes are discussed.The classical PS ZVS PWM DC-DC FB converter has some disadvantages such as its lagging leg is difficult to achieve ZVS and its duty cycle loss is large. To alleviate these problems, this paper introduces a PS ZVS PWM DC-DC FB converter using saturable inductor to reduce its duty cycle loss. This paper also introduces a PS PWM DC-DC FB converter with an auxiliary network attached to its lagging leg. This auxiliary network has the advantages such as its circuit is simple, the current stresses and voltage stresses on its components are small. The question of unbalance on PS PWM DC-DC FB converter is discussed, and the solution is proposed.The PS PWM DC-DC FB converter s key parameters are calculated and the control 1C UCX875 is introduced. Finally, a 48V/10A switch power supply applied to communication system is designed to meet the requirements of the standard "YC/T731-94" . The scheme is verified by SPICE simulation.