Asymmetrical PWM control of galvanically isolated impedance-source series resonant DC-DC converters

In this paper the asymmetrical pulse width modulation (APWM) is proposed for the control of galvanically isolated impedance-source series resonant DC/DC converters in the buck mode. Contrary to the variable frequency control, which is most widespread control technique of the series resonant converters, the APWM features fixed frequency operation and reduced circulation energy of the converter. This paper focuses on implementation challenges of the APWM with discontinuous current through the isolation transformer (DC-APWM), which enables the two-fold input voltage regulation, no duty cycle loss and reduced circulation energy. Based on the proposed approach a 200 W converter prototype was developed and experimental results are presented and discussed.