A New Variable Coil Structure Based IPT System with Load-Independent Constant Output Current or Voltage for Charging Electric Bicycles

This letter presents an inductive power transfer system based on a new variable coil structure to achieve load-independent constant current (CC) and constant voltage (CV) outputs for charging electric bicycles (EBs), without involving complex control strategies. The new variable coil structure consists of three-layer coils, i.e., two bipolar coils and one unipolar coil, on the transmitter side and one unipolar coil on the receiver side. The compact and portable receiver with series compensation is installed in the EB, while two switches on the transmitter side at the power charging station are utilized to reconfigure the transmitter coil structure to select the charging mode, i.e., CC mode or CV mode. The proposed system can achieve zero phase angle operation, fixed operating frequency, and zero-voltage switching, which will lower the power rating of power switches and improve the efficiency. A laboratory prototype is built to verify the feasibility of the proposed method.