Design of Inductively Coupled Power Transfer System Based on Dual-Loop Control

To solve the problem of constant voltage output due to frequent load fluctuations in rail transit power supply systems, a dual-loop control strategy based on sliding mode control and PI control is proposed. First, the authors established a model for the system with a discrete time dynamic model for the primary side, and a large signal model for the secondary side. Second, a dual-loop control strategy based on the model is proposed, in which the internal current loop is controlled by sliding mode control and the external voltage loop is controlled by the PI controller. The test results show that when switching the resistance to between 70 Ω and 50 Ω under a constant output voltage, the voltage changes by about 5% and returns to a stable value in approximately 15 ms. Therefore, the proposed control strategy can ensure a constant output voltage and fast response times under frequent load fluctuations.