A novel soft‐switching PWM dc‐dc converter with high‐frequency transformer link and its open‐loop regulation characteristics

Abstract

In the practical requirement for high efficiency, high power density, and high performance in switched-mode power supplies and their related application systems, a variety of circuit topologies of dc-dc converters incorporating soft-switching PDM, PFM, and PWM control schemes have attracted special interest in low-power and high-power applications. Some types of quasi-resonant soft-switching PWM converters have remarkable advantages, such as lowered switching losses of power semiconductor devices, reduced dynamic electrical stresses, constant-frequency operation, simple control schemes, and reduced EMI noise. However, most soft-switched quasi-resonant PWM converters developed so far include some inherent problems which must be solved, such as reduced power conversion efficiency due to significant circulating current generation. In recent years, a newly modified prototype soft-switched PWM dc-dc converter with a high-frequency transformer link has been proposed, which is capable of excluding circulating current operation mode. This paper presents a novel high-frequency transformer link soft-switching PWM dc-dc converter using active switches in the rectifier circuit. Its operating principles and unique features are described and compared with previously developed dc-dc converters. The operating performance of this converter in the steady state is illustrated and discussed, including simulated analytical and experimental results. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 119(3): 81–93, 1997