Analysis of magnetic coupling resonant wireless power transfer system based on multiple reconfigurable relay coils designed by variable inductors

The performance of the traditional low-power three-coil magnetic coupling resonant wireless power transfer (MCRWPT) system with a single-relay coil still deteriorates significantly during long-distance transmission. To address this question, a reconfigurable relay coil designed with a variable inductor and a maximum power point tracking (MPPT) control strategy is introduced to improve the real-time dynamic performance of a five-coil MCRWPT system. The impact of the number and position of reconfigurable relay coils on the transmission performance of the closed-loop controlled system has been thoroughly analyzed. The study results indicate that, due to the inherent loss of the variable inductor, the performance of the five-coil system cannot be effectively improved when multiple reconfigurable relay coils are employed. When the transmission distance is 500 mm, the original five-coil system's transfer efficiency and output power are 59.01% and 16.48 W. When the relay coil Z2 is replaced by a reconfigurable relay coil, the performance of the system with MPPT control strategy is the best, the highest transfer efficiency of the controlled system is 55.41%, and the maximum output power is 22.56 W. Compared with uncontrolled systems, although the transfer efficiency decreases, the power increases by 36.89%. Furthermore, the system has better misalignment tolerance. The proposed method can significantly improve the dynamic performance of the five-coil MCRWPT system under various working conditions, expected to solve the power supply challenges faced by complex environments, such as the field of electrical insulation.