Multiple-Transmitter Achieving Load-Independent Transmitter Current and Compensation of Cross-Interference among Transmitters for Wide Charging Area Wireless Power Transfer Systems

Recently, a resonant inductive coupling wireless power transfer (RIC-WPT) system with multiple transmitters is emerging as a promising power supply method for household appliances, mobile devices, and wearable devices dispersedly placed in a wide area. However, the multiple-transmitter often suffers from an unstable operation of an inverter, feeding AC current to the transmitter coil, due to the cross-interference (i.e., cross-coupling) among the transmitters. When the cross-interference occurs, the inverter may not achieve high power factor and soft switching, which damages the power density and reliability of the multiple-transmitter. Therefore, this paper proposes a multiple-transmitter, including its controller, that can compensate for the effect of the cross-interference. In the proposed multiple-transmitter, each transmitter has a simple switching circuit that can automatically cancel the induced voltage due to the cross-interference with only simple control. Furthermore, the proposed multiple-transmitter also achieves a load-independent transmitter current by the control of the input voltage of the inverter, which results in a stable magnetic field regardless of load variation. Experiments verify the effectiveness and appropriateness of the proposed multiple-transmitter.