Extended efficiency control method for WPT systems in smart grid under loose coupling extremes

This study presents an extended efficiency control method with resonant frequency tracking, load optimisation and output voltage regulation of extremely loosely coupled wireless power transfer (WPT) systems for smart grid applications. Adaptive resonant frequency tracking of this specified system is proposed and implemented to achieve a robust and efficient transmission efficiency with fast searching and less fluctuation. Automatic load optimisation of the system with the required output is realised to further improve the efficiency by adjusting the phase-shift angle of the converter on the transmitter side. Owing to a receiving feedback circuit, the proposed system does not require any communication which is suited for operating under high-voltage insulation conditions. Input current from source is the only parameter to be sensed for the proposed strategy of extended efficiency control, which makes the method cost-effective and work-robust even in the harsh environments. Experimental results prove the feasibility of the extended efficiency control method, which can be used in wireless powered devices in a smart grid or other extremely loosely coupled WPT systems.