Research Of High Frequency Switch Power Supply Based On Soft Switching Technique

Soft-switching PWM technique integrates the advantage of resonant converter and constant frequency modulator, which realizes zero-voltage-switching in constant frequency, and is one of the development trends of power electronics. Only adding a resonant inductor, stress of voltage and current in devices turns lower than traditional PWM hard-switching, without increasing cost and complication of circuit. Phase Shifted zero-voltage-switching PWM converter (PS-ZVS-PWM converter) is one of the topologies using soft-switching PWM technique, and is suited for middle to high power DC-DC conversion application.This dissertation analyzes the operation principle of PS-ZVS-PWM FB converter systemically. The classical PS ZVS PWM DC-DC FB converter has. some disadvantages such as its lagging leg is difficult to achieve ZVS and its loss duty of secondary is large. To alleviate these problems, this paper introduces a PS ZVS PWM DC-DC FB converter using saturable inductor to.reduce its loss duty of secondary. 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 to the problem is proposed.Based on the circuit topology, a switch power supply of 48V/10A for communication system is designed. The design of structure and calculation methods of parameter in the DC-DC converter main circuit and the design of the control and protect circuit have been presented. The phase-shift control is implemented with UC3879. The scheme verified by SPICE simulation shows the circuit topology is right.