Analysis, design and operation strategy of high-efficient Class E2 wireless power transfer systems for automotive EV battery charging applications

A zero current switched Class E-2 wireless power transfer battery charging system is proposed for automotive applications and a suitable operating strategy has been developed that always achieves optimum class E operating conditions of the active switching device, independent from transferred power, battery voltage and magnetic coupling. A prototype with two different-size energy transfer coils with 25cm and 60cm outer diameter has been built and tested to verify theoretical predictions obtained from the analyses and the simulations. Efficiencies around 95% have been achieved at maximum output power and minimum magnetic coupling of k = 0.2. Experimental results are in close correlation with theoretical predictions and show the good performance of the proposed power transfer system.