Mutual Inductance and Load Identification Method for Inductively Coupled Power Transfer System Based on Auxiliary Inverter

Abstract

The parameter identification of the inductively coupled power transfer (ICPT) system is of great significance for the high performance control, efficiency optimization and safe operation of the system. A method realizing mutual inductance and load identification without affecting load operation is proposed in this paper. Two inverters and two matching transformers are applied in transmitting side. One is called main inverter operating in resonant state and another is called auxiliary inverter in non resonant state. Two matching transformers are connected in series. The operating state of the system can be divided into mode 1 and mode 2 according to the non-operation or operation of the auxiliary inverter. Theoretical derivation shows that the transmitting coil current peak is enveloped when system operates in mode 2. Then the mutual inductance and load parameter can be determined according to the maximum and minimum values of the envelope. By designing the operating frequency of the auxiliary inverter and its current, the load voltage of mode 2 is basically the same as that of mode 1. The identification of mutual inductance and load are carried out under different condition. The results show that proposed method of the mutual inductance and load identification is feasible without affecting the load operation and the identification errors of mutual inductance and load are less than 6%.