Comparison of Input Voltages of Series Resonant Converters for Isolated Auxiliary Power Supply

Isolated auxiliary voltages are often required in electrical devices. Three-level or multi-level inverters require more than twelve isolated voltages, e.g. gate supply and supply for isolated measurement. Currently, resonant converters are increasingly being used to generate an isolated voltage. This paper discusses the optimization of the input voltage of a resonant converter to minimize the effects of parasitic secondary capacitance. A converter with a discrete driver is constructed so that no dead time is required. An exemplary resonant converter is designed and the effect of recharging the secondary side of the transformer is described by equations and verified and minimized in simulation and measurements.