Power and Signal Synchronization Control Method of Wireless Charging System Based on Variable Phase Shift Angle

Aiming at the problem that the transmission signal of bidirectional wireless power transfer (BWPT) system requires additional hardware circuit, and the transmission efficiency caused by seamless bidirectional flow of power and reactive power is rarely taken into account when the power and signal are transmitted synchronously, a power and signal synchronization control method of BWPT system based on variable phase shift angle is proposed. Firstly, by analyzing the power/signal transmission characteristics of the fundamental and kth harmonic equivalent models of the BWPT system based on the doubled-side LCC compensation network, the four control degrees of freedom of frequency, primary side internal phase shift angle, secondary side internal phase shift angle and external phase shift angle are obtained. The analysis shows that the active power size and direction are determined by the external phase shift angle, and the reactive power size is determined by the internal phase shift angle. Therefore, the fundamental component transmission power of the output square wave voltage of the full-bridge converter is selected. The third harmonic component transmits the signal, and the phase shift angle of the primary side is changed to transmit the signal. Furthermore, a double closed-loop control strategy of external phase shift angle controlling active power and secondary internal phase shift angle controlling reactive power is proposed to realize half-duplex communication, forward and reverse seamless power flow and efficiency improvement. Finally, the effectiveness of the control method is verified by Matlab/Simulink and experimental platform.