Constant Power Output for LCC-LCC Compensated WPT Systems Considering Large Variations of Loads and Coupling Coefficients

Misalignments and variations of loads often occur in wireless power transfer (WPT) systems, which would cause fluctuations of output power. To tackle this problem, this article attempts to present a novel control scheme to maintain a constant power (CP) output when there are variations of loads and coupling coefficient. The CP WPT system employs a double-LCC (DLCC) compensation topology, where the secondary side compensation inductor is connected in series with a semi-active rectifier (SAR) and a switch-controlled capacitor (SCC). Additionally, a parameter collaborative regulation strategy is specially proposed, which enables the CP-WPT system to operate at resonant states and deliver CP output by configuring the equivalent load impedance on the secondary side. Moreover, the proposed control can guarantee that all switching devices can achieve ZVS, which significantly reduces switching losses and improves the overall efficiency of the system. Finally, an experimental prototype is built to verify the effectiveness of the proposed method. The measured results demonstrate that the proposed system can achieve CP output under conditions of loads and coupling coefficient variation greater than 50%, while the fluctuations of output power are smaller than 5%.