ACHIEVING THE CONSTANT OUTPUT POWER AND TRANSFER EFFICIENCY OF A MAGNETIC COUPLING RESONANCEWIRELESS POWER TRANSFER SYSTEM BASED ON THE MAGNETIC FIELD SUPERPOSITION PRINCIPLE

The output power of a magnetic coupling resonance wireless power transfer (MCR-WPT) system attains the maximum value at two frequencies splitting in an over-coupled region. To achieve suitable transfer characteristics, impedance compensation methods have been used in MCR-WPT domain. In securing the constant output power and transfer efficiency in a constant frequency mode, a topology of the MCR-WPT system with two transmitting coils is employed. First, the circuit model is designed while evaluating the transmission characteristics. Second, when the two transmitting coils are placed into the transmitting loop, the main transmitter and sub-transmitter loops are created by sharing the same transmitter. The use of two transmitting coils to achieve a magnetic field superposition is investigated. Constant output power and transfer efficiency are then investigated in a constant frequency mode. Finally, the experimental equipment is designed. Experimental results confirm the effectiveness and robustness of the topology. Such a topology can be optimized for the transfer performance by itself and can achieve constant output power and transfer efficiency. If the distance between the two transmitting coils is appropriate and the receiving coil moves between the two transmitting coils, the fluctuation of the output power and transfer efficiency of the MCR-WPT system is less than 5%.