Analysis on safety issues of capacitive power transfer system

The capacitive power transfer (CPT) technology is a novel solution to transfer power wirelessly by using electric field. Although there is an insulating layer on the coupling plates, leakage electric field is still existing around the plates. So there might have an electric shock hazard when a human body touches the conductors placed around the coupling plates. To solve this problem, an equivalent capacitor model of the metallic conductor and the coupling plate is established. Besides, a human body impedance model is introduced to obtain equivalent circuits of the CPT system when a human touches the conductor. The formulas of the four coupling plate voltages are derived for a full bridge series resonant CPT system. Moreover, the distributed voltages of the conductor placed above different coupling plates are given. The correctness of the theoretical analysis has been verified by the experimental results.