Class-E half-wave zero dv/dt rectifiers for inductive power transfer

Abstract

This paper analyses and compares candidate zero dv/dt half-wave Class-E rectifier topologies for integration into multi-MHz inductive power transfer (IPT) systems. Furthermore, a hybrid Class-E topology comprising advantageous properties from all existing Class-E half-wave zero dv/dt rectifiers is analysed for the first time. From the analysis, it is shown that the hybrid Class-E rectifier provides an extra degree of design freedom which enables optimal IPT operation over a wider range of operating conditions. Furthermore, it is shown that by designing both the hybrid and the current driven rectifiers to operate below resonance provides a low deviation input reactance and inherent output voltage regulation with duty cycle allowing efficient IPT operation over wider dc load range than would otherwise be achieved. A set of case studies demonstrated the following performances: 1) For a constant dc load resistance, a receiving end efficiency of 95% was achieved when utilising the hybrid rectifier, with a tolerance in required input resistance of 2.4% over the tested output power range (50W to 200W). 2) For a variable dc load in the range of 100% to 10%, the hybrid and current driven rectifiers presented an input reactance deviation less than 2% of the impedance of the magnetising inductance of the inductive link respectively and receiving end efficiencies greater than 90%. 3) For a constant current in the receiving coil, both the hybrid and the current driven rectifier achieve inherent output voltage regulation in the order of 3% and 8% of the nominal value respectively, for a variable dc load range from 100% to 10%.