Practical Phase Shift Angle Bounds in Current Fed Digitally Controlled ZVS Semi-Active Rectifiers

This article reveals issues with operation of practical current source fed phase shift controlled semi-active rectifier (PS-ZVS SAR), often utilized as the output stage of resonant converters functioning in the load-independent output current mode. Active rectifier (AR) adoption allows attaining load matching or dc output regulation capabilities. In this work, the operation of a practical PS-ZVS SAR is revisited taking into account output capacitances of switching devices in order to derive lower and upper bounds of attainable output dc current and phase shift angle. Furthermore, measurement and computational delay imposed by digital implementation are also considered for accurate prediction of practical system behavior. According to the findings, voltage transients caused by parasitic capacitances of semiconductor devices and digital delays narrow the feasible phase shift angle region. In order to validate the presented material, series-series compensated wireless power transfer (WPT) system employing PS-ZVS SAR as a receiving-side rectifier is studied as an example. The analytical framework is shown to be accurately supported by both simulations and experiments.