Practical considerations of series-series and series-parallel compensation topologies in wireless power transfer system application

Wireless power transfer (WPT) system has the advantages of safety, reliability, convenience and so on. In order to improve the output power and reduce the input capacity of the system, the energy transfer coils should be compensated by electrical measures in practical applications. In this paper, series-series (SS) and series-parallel (SP) compensation topologies of primary and secondary coils were respectively analyzed based on the theory of mutual inductance in detail. The relationship was obtained between output power, transmission efficiency and the load, frequency and coupling coefficient by Matlab simulation. The simulation results show that the output power is more sensitive to the change of frequency, and SS compensation topology is more suitable for small load system while SP is appropriate for large load system. For a fixed transmission distance, there is an optimal load to maximize the output power and transmission efficiency. And the smaller the load, the frequency splitting is more easily for SS topology. In contrary, the larger the load, the frequency splitting is more easily for SP topology. In addition, the transmission efficiency increases with the decrease of transmission distance. So this paper can give a guideline for selecting the suitable compensation topology under the consideration of practical applications.