Single-Switch Inverter Wireless Charger with Adaptive Constant Current and Constant Voltage Control by Transmitting Side Sensing Load Changes of Receiving Side

Because of its excellent flexibility, security, reliability and convenience, wireless power transfer(WPT) has become a research hotspot at home and abroad. Currently available WPT technology has the broadest application prospects and can be used in consumer electronics, household appliances, medical equipment, electric vehicles and many other fields. In low-power wireless charging systems such as electric bicycles, volume and cost of the receiving side are required to be minimized. However, in traditional receiving side circuit, compensation network, sampling circuit and wireless communication circuit make it difficult to reduce the device size and limit further reduction of cost. Aiming at the above problems, a single-switch LC inverter S-S wireless charging circuit with adaptive constant current (CC) and constant voltage (CV) control by transmitting side sensing load changes of receiving side is proposed. In this paper, load-independent CC and CV characteristics and relationship between auxiliary coil voltage and load voltage are derived. The simplest equivalent model of the proposed circuit is developed, the expression for equivalent input voltage is derived, and the constraints of zero-voltage switching (ZVS) are analyzed. Based on the constraint, an iterative method of variable duty cycle is proposed, which can accurately find the duty cycle range in which the ZVS can be realized as well as the peak resonant current in this range, which provides a reference for parametric design of single-switching circuit. Finally, a 5A/54.6V experimental prototype is built to verify the correctness of the proposed theory.