Modeling and control of inductive power transfer system supplied by multiphase phase-controlled inverter

A multiphase inverter with phase-shifted control is proposed for the inductive power transfer (IPT) of electric vehicles where the charging voltage can be regulated by adjusting the angle among the inverter phases. An equivalent circuit model is developed and linearized to analyze the system dynamic characteristics at its operating point. In terms of the high-order model, a balanced model reduction method is used to remove the fast modes that are outside the desired system bandwidth and insignificant to controller design. In addition, the model is discretized and the communication delay of the feedback loop is considered in the discretized model. Based on this model, the parameters of a PI controller are designed to achieve the expected performance indexes. A 6.5 kW S-S compensation IPT system prototype with constant voltage control is built and tested to verify the control performance. The experimental results show that the charging voltage can be maintained constant within 6 ms and has no overshoot under disturbances, which verifies that the closed-loop system with PI controller operates properly and efficiently for IPT. Besides, the measured transmission efficiency of the system at a receiving power of 6.5 kW is 95.1%.