A fixed-frequency control method for wireless power transmission battery chargers using a dual-function compensator

High efficiency and unity power factor (PF) are the most important requirements of a wireless charger system simultaneous with the output voltage regulation. Achieving all above-mentioned criteria in a wide range of the load is challenging in the system. This paper presents a novel control approach applied to series-series wireless power transmission converter by using a dual-function compensator to achieve unity PF and maximum efficiency during the constant power-constant voltage (CP-CV) charging scenarios. A semi-active rectifier with impedance matching capability along with a switch-controlled capacitor constitutes the dual-function compensator on the secondary side. Meanwhile, the primary side inverter executes the CP-CV charging scenario for the battery with various charging characteristics at a fixed-switching frequency. Besides that, all secondary side switches experience soft switching condition throughout the battery charging. Finally, a prototype with a power of 200 W and roughly regulated efficiency of 90% is presented in order to verify the proposed control method.