Implementation of constant current and constant voltage charging control of a wireless charging converter

Abstract

In this work, implementation of constant current (CC) and constant voltage (CV) control of the LC/S compensated wireless charging converter (WCC) is presented. The LC/S compensation topology, operating as load independent in CC mode, is used in the proposed WCC. The CC charging control mode of the WCC is achieved at the constant operation frequency providing the maximum power transfer. On the other hand, frequency modulation (FM) control method is applied to achieve the CV charging control operation. Thus, implementation of entire charge period of WCC using LC/S compensation is provided with a minimum frequency variation. The basic principles and the analytical analysis of the proposed WCC are presented. The analytical output regulation, during CC and CV charging control modes, is discussed based on power transfer efficiency. Finally, a prototype with 60 W output power is built to validate the presented analytical analysis. The efficiency variations of CC and CV charging control modes are extracted as function of the load condition. The misalignment performance of the proposed system is also evaluated based on the load condition. The maximum efficiency of the proposed system is measured as 86.6% at 70 mm air gap and 40 W output power.