Cancellation Conditions of Magnetic Field Leakage From Inductive Power Transfer Systems

In inductive power transfer systems, a transmitter array can maintain high power transfer efficiency (PTE), despite lateral misalignment between the transmitter and receiver. However, a control method for reducing magnetic field leakage in this situation has not been found. Therefore, a novel theory of controlling the transmitter array is necessary for electromagnetic compatibility and user safety. In this study, we optimize the input currents at the transmitter array and the load impedance at the receiver to maximize PTE under the cancellation condition of the magnetic field leakage. Simulations show that the proposed method reduces magnetic field leakage by more than 10 and 38 dB, with and without ferrite plates, respectively, compared with existing PTE maximization methods, even when there is a lateral misalignment between the transmitter and receiver. Additionally, experiments using coils having ferrite plates show that the proposed method reduces magnetic field leakage by more than 6.75 dB. The decrease in PTE is within 4.17 %, which compares favorably with existing methods.