Analysis of buck mode realization possibilities in quasi-Z-source DC-DC converters with voltage doubler rectifier

A series resonant tank in the quasi-Z-source (qZS) DC-DC converter with a voltage doubler rectifier could significantly increase the input voltage regulation range by adding the buck mode realization possibility. This paper discusses two different control approaches of the qZS series resonant DC-DC converter in the buck mode: variable frequency control and phase shift modulation. Both methods are explained by means of steady-state analysis. To verify the theoretical background, a 200 W experimental prototype was built. Experimental results are compared with theoretical predictions.