Independent control of maximum transmission efficiency by the transmitter side and power by the receiver side for wireless power transfer

Wireless power transfer via magnetic resonant coupling is becoming ideal for applications in electric vehicles (EV) because it is considered a potential solution. The transmission efficiency and charging power, decided by the load impedance and mutual inductance, are very important for achieving a high efficiency in the charging system of EVs. However, in order to achieve a simple transmitter, communication between the transmitter and receiver sides is not desired. In this study, a simultaneous control method without communication is proposed to control the transmission efficiency on the transmitter side and the charging power on the receiver side. It is shown that the transmission efficiency can be changed by manipulating the transmitter-side voltage while the transmitted power is controlled by the receiver side. A method for estimating the desired power by the transmitter side is also proposed in order to achieve the optimal transmitter-side voltage without communication. The effectiveness of the proposed method using the calculated optimal transmitter-side voltage and the method for estimating the charging power is shown through experiments.