Dual-Side Closed-Loop Control, Stability Analysis, and Parameter Design of Two-Stage LCC-LCC WPT

In the LCC-LCC wireless power transfer (WPT) system with the secondary buck converter, the overvoltage (OV), and overcurrent (OC) faults occur when the secondary buck converter is shut down suddenly. To ensure safety, this issue is analyzed at the transient level and the dual-side indirect closed-loop control strategy is proposed to achieve the closed-loop control of the terminal voltage and the secondary dc bus voltage. The secondary dc bus voltage is under the indirect control by the closed-loop control of the primary inverter current and this conclusion is proven in the transient level. Under the dual-side closed-loop control strategy, the two-stage WPT system forms a cascade system and there is the instability problem. The integrated design criteria of the dual-side controller parameters based on the cascade system stability theory are given. The feasibility and practicability of the proposed control strategy and parameter design method are verified by the experiments.