Mode Switching Based Parameter Identification for 2TX-1RX Wireless Power Transfer Systems

Parameters within wireless power transfer (WPT) systems could vary for different reasons. On one hand, mutual inductances and load conditions could vary due to different operating points of the WPT system. On the other hand, the values of capacitors within the WPT system could also vary due to aging issues. Identifying those parameters is of great importance to ensure highly efficient, controllable, and reliable operation for WPT systems. However, those parameters are strongly coupled within the system and are quite challenging to be estimated at the same time. This paper proposes a model based method to estimate all the parameters of interest, including mutual inductances, load condition, and all the capacitances, for multi-coil WPT systems with 2 transmitting coils (2TX) and 1 receiving coil (1RX). Specifically, to overcome the challenge of estimating many parameters at the same time, the idea of “mode switching” is applied to greatly improve the redundancy of the parameter identification problem. Auxiliary standard capacitors are introduced into the system to enable the switching of different operating modes. Afterward, a mathematical model is established to describe the physical laws among all the interested parameters in each mode, including the fundamental frequency and harmonic components. Finally, a standard solve procedure is introduced to solve the nonlinear model and calculate the parameters. The method only requires transmitter side measurements, without any information from the receiver side. Experiments conducted on a prototype of a 2TX-1RX LCC-S WPT system verified the effectiveness of the proposed parameter identification method.