Relationship between Drive Frequency and Load Characteristics in Bidirectional Contactless Power Transfer for Electric Vehicles

Vehicle to home (V2H) attracts attention as a way to use electric cars. In V2H, it is necessary to exchange electricity between the electric car and the household. Therefore, bidirectional contactless power feeding technology is effective. In bidirectional non-contact power feeding, it is required that the performance does not deteriorate even if the power transmitting side and the power receiving side are switched. Therefore, it is effective that the capacitor is symmetric as a capacitor connecting method for efficiency compensation and power factor improvement. We adopt the series-series (SS) system connecting the capacitors in series to the coil. However, in the case of the SS method, if the load fluctuates, the current on the primary side increases and the leakage magnetic field increases. Also, an increase in the primary current causes an increase in the output voltage. Therefore, in this paper, in order to suppress the primary current at light load and to stabilize the output voltage, a method of controlling the drive frequency was proposed. As a result, by selecting an appropriate drive frequency, it was possible to suppress increase in the primary side current at light load and realize voltage stabilization.