Effects of parallel load-side compensation in wireless power transfer

High reliability and ever increasing cost-effectiveness of power electronics components and digital processors have resulted in high interests in inductive power transfer techniques. The interest is directed mostly at electric and hybrid passenger car battery charging, although the first solutions have already been conceptualized and turned into homologated products for much higher power levels for bus and light rail vehicles. Transformers used for automotive applications have a large air gap and relatively low coupling coefficients. High levels of output power require tuning techniques in order to eliminate or decrease the associated reactive power. In this paper a parallel load side compensation technique and its consequences are described. The analysis is done by utilizing a novel method based on Boucherot Bridge model for the wireless power transformer. The analytical results are confirmed by circuit simulation using the transformer parameters derived from finite element electromagnetic analysis.