Magnetic field intensity suppression using communication-less impedance adjustment for inductive power transfer systems

This letter describes the effectiveness of magnetic field intensity suppression through communication-less impedance adjustment in an inductive power transfer (IPT) system. The impedance adjustment scheme comprises a circuit configuration design that enables adaptive reactance adjustment using a field-effect transistor (FET) bridge-based variable reactor, which includes a coupling-coefficient estimation method for adjusting load resistance. The experimental results show that the load impedance that minimizes the magnetic energy stored in the IPT system can suppress the magnetic field intensity by up to 16.5% with only a 4.8% decrease in power transfer efficiency compared to load impedance that maximizes the power transfer efficiency.