Dynamic pulse modulation: a technique to control resonant DC/DC converters

A new method to control the voltage output of the resonant DC/DC converter is presented. The technique is based on either gating (i.e. turning on) the switches following normal sequences or keeping the switches ideal by suppressing the pulses to the base/gate drive circuit. Thus, when the switches operate, they all operate in proper sequence at constant frequency or none of the switches operate at all. Therefore, the voltage output of the converter may easily be controlled by adjusting the time of the pulse suppression. The superiority of the control technique over pulse width modulation and frequency modulation has been highlighted. The technique may be implemented for a wide range of half-bridge/full-bridge load resonant and quasi-resonant converter topologies. In this paper a series resonant half-bridge network is considered as an example. A simple design method for the converter is also discussed. The results from the experiments show excellent voltage regulation through out the entire range of load variation for the series resonant converter. The method is also applied for the parallel resonant converter and excellent regulation is again confirmed.