Cost-Effective and Compact Multistring LED Driver Based on a Three-Coil Wireless Power Transfer System

In this letter, a multistring light-emitting diode (LED) driver based on a three-coil wireless power transfer system is proposed. The proposed system can solve the current imbalance problem among multiple LED strings because of its unique merit of multiple load-independent constant current (CC) outputs. Also, zero-phase-angle operation is achieved. Thus, not only the power rating of power switches can be reduced but also the efficiency is improved. For the sake of compactness, the source coil and the transmitter coil on the transmitting side are attached to the same plane. In addition, to further save the install space, magnetically integrated LCL resonators are utilized on the receiving side. The proposed system is cost-effective since only one receiver and passive components are needed to obtain the multiple CC outputs. Furthermore, by employing a master-slave control strategy, the output currents can be changed synchronously, which enables the 'plug and play' capability and features a simple control structure. Finally, the feasibility of the proposed method is verified on a laboratory prototype.