Secondary-side-only Control for Smooth Voltage Stabilization in Wireless Power Transfer Systems with Constant Power Load

In recent years, wireless power transfer technology has received considerable attention because of its wide range of applications. Almost all literature focuses on resistance load or constant voltage load, but constant power load is never considered. The constant power load voltage is unstable, thus stabilization is required. In order to perform it without resorting to discontinuous operation and avoid big voltage transients, this paper proposes a control strategy for a secondary side with a single converter. It is based on the combination of synchronous rectification and symmetric phase shift, without communication with the primary side. While the primary side is not manipulated, the AC/DC converter regulates the amplitude of the secondary coil voltage and stabilizes the constant power load voltage on the DC side. In this paper, the control concept, the design and the stability analysis are provided. The proposed control is verified through experimental results both in a static scenario.