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It is important to determine the position of the receiver (Rx) coils in wireless power transfer (WPT) system, and to control the power transmitted to the Rx coil based on this result. In particular, in a situation where there is no feedback between the primary side and the secondary side, it is difficult to control the received power because the information is limited. In this paper, a method for determining the position of the Rx coils and controlling the received power using limited parameters in a feedback-free WPT system is proposed. The proposed method is verified by constructing a 4 × 2 WPT system, and it is validated that the simulation result and the experimental result are consistent well. Furthermore, arbitrary power can be transmitted to the Rx coil based on the result of the position of the Rx coil. The experiment is conducted by transmitting about 1 W to Rx 1 and Rx 2, and the efficiency for Rx 1 is about 32.93 % , Rx 2 is 25.03 % , and the overall efficiency is confirmed to be 57.96 % . [ABSTRACT FROM AUTHOR]

This paper proposes the algorithm to control the current ratio of the transmitting (Tx) coils for proper power distribution to the two receiving (Rx) coils in wireless power transfer (WPT) system. The proposed algorithm assumes that each Rx coil appears at different times to consider the situation where multiple users request power transmission as practically as possible. That is, suppose the second Rx coil enters the charging space later than the first Rx coil. When each coil enters the charging space, only the Tx coil is used to obtain the value required for calculation. Using the obtained result, the optimized Tx coil current is calculated by the proposed algorithm and proper power distribution to both Rx coils is achieved. Three Tx coils and two Rx coils are constructed using the ANSYS MAXWELL simulation tool. As a result of applying the proposed algorithm, it was confirmed that a similar level of power was transmitted between 40∼60%, respectively. The sum of the power transmitted to the two Rx coils also appeared as more than 75%. [ABSTRACT FROM AUTHOR]