A voltage ratio-based efficiency control method for 3 kW wireless power transmission

This paper presents a novel control method for wireless power transmission (WPT). The proposed method can maximize the power efficiency only by controlling the voltage ratio between the primary and the secondary side. Experimental measurement results of the prototype system with 3 kW power transmission show the efficiency difference between the proposed control method and the available maximum value is less than 0.3 % even with a large variation of coil-to-coil distance and load voltage. The automatic controller for the proposed method provides the load-following operation, maintaining both constant power and high efficiency, using a WLAN connection.