Synthesis and Control of a Three-Port LCL Resonant Wireless Power Transfer System for DC Energy Conversion Applications

This article proposes a three-port
LCL
resonant wireless power transfer system with hybrid power flow control methods for dc--dc energy conversion applications. Two half-bridge microinverters provide the dual input ports for DC energy sources, while the load port is connected through an
LCL--LCL
wireless coupling tank loaded with a full-bridge rectifier. The three-port topology allows flexible power transfer between dual input sources while the two sources share one
LCL
resonant tank to transfer energy to the load without additional components. The control function of this proposed system can be divided into two phases. In phase one, PWM method is employed to implement bidirectional power transfer between dual input sources by controlling the average dc offset current in the
LCL
resonant tank. In phase two, phase-shift modulation (PSM) method is applied to regulate wireless power output for load. The proposed modulation methods enable the system to take sources with different voltage levels at the dual input ports. Theoretical time domain analysis of the proposed topology and
LCL
coupling tank is presented in detail. Open-loop simulation is carried out to obtain the power transfer characteristics between the multiple ports, and closed-loop simulation is done to verify the efficiency of the designed control method. A 200 W prototype was built to evaluate the performance of the proposed topology. Experimental results show that the proposed system can achieve a peak efficiency of 93.6% with the load-independent constant current performance achieved.