Asymmetrical Voltage-Cancellation control for LCL resonant converters in Inductive Power Transfer systems

This paper presents the first conceptual description of a fixed frequency soft switched LCL load-resonant converter for Inductive Power Transfer (IPT) systems. By using Asymmetric Voltage Cancellation (AVC) control to avoid diode reverse recovery loss (DRRL), ZVS operation over a wide load range becomes possible. The circuit was solved using a time domain analysis method and the optimal control trajectory was determined using a greedy salesperson algorithm. Experiments on a 60W prototype were carried out to validate the regions for which DRRL is avoided and were used to compare the improved performance against previous fixed frequency control strategies. It has been shown that the efficiency can be improved up to 5% and the THD can be reduced up to a factor of 7 compared to phase shift and Asymmetric Duty Cycle control, respectively.