Load estimation of a series-series tuned wireless power transfer system

For an inductive wireless power transfer system, developing a high-performance controller is very challenging. Because the transmitter cannot directly sense the receiver-side voltage and currents, many conventional systems use wireless communication to feedback receiver-side information to the transmitter-side controller. However, because of delay and frequent data loss of the wireless communication causes significant problem in control. Using a synchronous reference frame model of a series-series tuned inductive power transfer system which was proposed in a previous research, receiver-side voltage and current observers for d- and q-axis currents are proposed in this study. Based on the relationship between d- and q-axis currents of the transmitter and receiver, Luenberger-style observers are developed. Using a simulation software, MATLAB/SIMULINK, estimation performance of the proposed observers are evaluated. It was found that estimated d- and q-axis currents of the receiver follow well the actual d- and q-axis currents of the receiver within 1 ms. Also, estimated voltages of the receiver follow the actual voltages within 1 ms under the step load change.