Wireless Power Transfer to Multiple Loads Over a Long Distance With Load-Independent Constant-Current or Constant-Voltage Output

The regulated output characteristic is crucial for a wireless power transfer (WPT) system. Most studies focus on the single-load system or the system with multiple evenly distributed loads; however, the loads might distribute in space at different distances from the power supply in practice. In this article, a WPT hybrid repeater system is proposed to power multiple loads over a long distance. The output mode of each load in the system can be switched separately to realize the load-independent constant-current (CC) or constant-voltage (CV) output. Based on four compensation network combinations of a two-load WPT repeater system with CC/CV output, the structure of the N-load WPT hybrid repeater system with load-independent CC/CV output is derived. With the ZPA input characteristic, fixed operating frequency, and high system efficiency, the proposed system can be easily used in various medium- or low-power applications. The effects of system parameters on output characteristics, power transfer capability, and system efficiency are investigated. A three-load experimental prototype was built to verify the theoretical analysis. Measurement results were in good agreement with the analysis, and the maximum measured efficiency reached 83%.