Multiple soft-switching operating points-based power flow control of contactless power transfer systems

This study proposes a new power flow control method of a resonant converter used for contactless power transfer applications based on a multiple soft-switching operating points (MSSOP) approach. The essential idea is to switch the converter to hop among different zero-current-switching (ZCS) operating points. The proposed MSSOP controller consists of two closed loops. The inner loop achieves soft-switching by detecting the zero crossing instants of the current and controlling the semiconductor switches synchronously. The outer loop controls the power flow by selecting proper ZCS operating points according to the error between the measured and the reference voltages. Simulation and experiment results have verified that the proposed control method can regulate the output voltage of the system to be constant against wide load variations.