Efficiency characteristics of a half-bridge series resonant converter for the contact-less power supply

Comparing with a conventional transformer without an air gap, a contact-less transformer with a large air-gap (4.8 cm) between the long primary winding and the secondary winding has large leakage inductance and small magnetizing inductance. Because of the large leakage inductance and small magnetizing inductance on the primary of the contact-less transformer, a large amount of the primary current circulates through magnetizing inductance, which results in large losses and high voltage gain characteristics to the load variations in contact-less power supply (CPS) system. In this paper, an equivalent model of the system for the theoretical efficiency analysis by dividing the system into series resonant inverter and rectifier portion is given, then the efficiency characteristics of the contact-less power supply system using a half-bridge series resonant converter is analyzed considering performance and gain characteristics of the contact-less system. Finally, the system efficiencies are compared and verified through simulation results and experimental measurement of 2.5kW experimental prototype system.