A Dynamic Tuning Method Utilizing Inductor Paralleled With Load for Inductive Power Transfer

The detuning of an inductive power transfer (IPT) system caused by the component tolerance and aging of the inductors and capacitors can decrease the system efficiency, accordingly. To tune the receiver circuit of the IPT system dynamically, an inductor is parallelly connected with a diode full-bridge rectifier cascaded with a buck converter serving as a tuning circuit in this paper. By changing the duty cycle of the buck converter, the impedance of the tuning circuit can be adjusted to compensate the reactance caused by detuning. The tuning range of the proposed method is analyzed in detail. A corresponding control method, in which an auxiliary measurement coil is utilized, is proposed to tune the receiver circuit dynamically while regulating the output voltage. Because the buck converter is with the dc side of the receiver, no synchronization is required for the switches of the buck converter, and the switching frequency of the buck converter can be much lower than the inverter frequency. A 400 W prototype is established to validate the proposed method. The experimental results show that with 15% tolerance of the resonant capacitor in the receiver side, the system efficiency with the proposed tuning method can reach 91% with an improvement by 7.9% compared to the detuned system.