Zero-voltage and zero-current switching buck-boost converter with low voltage and current stresses

A family of soft-switching power converter is presented for fuel cell applications. The salient points are that all the switching devices are under zero-current switching during turn-on and zero-voltage switching during turn-off. The family of the circuit presented includes the buck, boost, buck-boost and Cuk converter. The active switches in the converter undergo zero-capacitive turn-on losses unlike switches in other soft-switched topologies discussed in the literature. The switches do not experience any over voltage/over current stress proportional to load as in resonant converters. This soft-switching technique can also be applied to other classical switched mode power converters. A detailed mathematical analysis of the converter under steady state is carried out, and experimental results obtained from a prototype are presented. The converter was also connected to a model toy car driven by fuel cells for the demonstration of the application.