Abstract: The frequency division phenomenon of the wireless power transfer（WPT）circuit in the electric

vehicle wireless charging system under the premise of the optimal load resistance was discussed．In the optimized

WPT circuit，by changing the value of the coupling coefficient（k） between the master and slave coils in the

charging system，three zero reactance frequency（ZRF）points would be generated in the circuit，and then frequency division was generated. Through the adaptive frequency selection of the ZRF point，the output power of the entire circuit system can be maximized under the premise of high energy transmission efficiency ．

      Key words: wireless charging；optimal load；zero reactance frequency（ZRF）；frequency selection