Small Signal Modeling of LCC-S Compensated Multiphase Inductive Power Transfer System Using Extended Describing Function Method

This paper presents the small-signal modeling of an LCC-S compensated multiphase inductive power transfer (MIPT) system using the Extended Describing Function (EDF) method. The system incorporates three-phase electromagnetic coupler powered by a three-phase 2-level voltage source inverter. The implementation of an LCC compensation network at the primary side provides a constant coil current in the primary coil and ensures load-independent gain characteristics. Additionally, the necessary mathematical formulations for deriving the small-signal model using EDFs are thoroughly detailed. Based on this analysis, the open-loop transfer function between the duty cycle and the output voltage of the system is formulated. Furthermore, the LCC-S MIPT system's controller parameters are designed to ensure stable dynamic performance. The simulation results for the linearized model are presented for open-loop and closed-loop operations. Finally, the approach is experimentally validated on a scaled-down MIPT system prototype, and the results demonstrate the functionality of the designed parameters and controller.