Analysis of Phase-Shift Full Bridge ZVZCS Converter

In recent years, more and more researches show that hard switching mode has limited the switching frequency in converter and full-bridge zero-voltage PWM soft switching (ZVZCS) converter existing the phenomenon of duty cycle loss seriously. This paper introduces full-bridge zero-voltage and zero-current PWM soft switching converter´s main circuit topology and working principle. Because one of characteristics is symmetric operation, seven kinds of modals in the first half period of work process is analyzed in this paper. At last, the theory has been verified on a 2.4KW DC-DC transform type charging power supply, a detailed analysis and discussion is made about soft switching waveform when second side is under no-load, half load and full load. At the same time, the efficiency curve is given. Experimental results show that the converter can achieve zero-voltage-switching for leading leg switches and zero current-switching for lagging leg switches effectively, and when load current increases from 0A to 80A, the maximum efficiency of converter can reach 97.8%.