Method of feedback detection for loosely coupled inductive power transfer system with frequency-tracking mechanism

This paper proposes a feedback signal detection method and frequency-tracking control approach for inductive power transfer (IPT) systems. The power delivery efficiency is increased by utilizing a resonance compensation circuit and frequency-tracking control. Yet, it was observed that the resonance characteristics of IPT systems are easily influenced by load impedance and coil gap, hence frequency-tracking control is integrated into the microprocessor control unit (MCU) controller such that the operation frequency can be closely locked with the primary current phase. In the circuit design, a voltage across R_DS(on) of the power MOSFET is utilized to compensate the resonance features of IPT system, by which the system delivery efficiency and zero-voltage switching can be both achieved. This proposed system has been tested under several scenarios. Test results help confirm the feasibility of IPT module for the application that is investigated.