Three-Coil-Based Single-Stage Inductive Power Transfer Converter with Voltage-Sigma Architecture for Battery Charging Applications

This paper introduces an innovative concept for implementing constant current (CC) and constant voltage (CV) battery charging using the proposed three-coil-based single stage inductive power transfer (IPT) converter with voltage-sigma architecture. In proposed converter, an adjustable dc voltage and a constant dc voltage are provided by two receiver coils, i.e., the intermediate receiver coil (IRC) and the back-end receiver coil (BRC). Such two dc voltages are stacked together on the battery port. The total output voltage is controlled by the adjustable dc voltage using semi-active rectifier (SAR) in IRC. Therefore, BRC can always operate the optimized operation point to ensure high efficiency. Since the adjustable dc voltage is much lower than the constant dc voltage, low power-rating switches can be used in SAR, which is benefit for reduction of switching loss. Primary inverter can achieve zero phase angle (ZPA) operation, fixed switching frequency and zero voltage switching (ZVS) without wireless communication links. Finally, a simulation of 3kW IPT system is built to verify the feasibility of proposed method.