Research on bidirectional contactless resonant converter for energy charging between EVs

Contactless power transmission (CPT) technique based on the contactless transformers is extraordinarily promising for the electrical vehicle (EV) battery charging application for its safety, convenience and flexibility. By introducing two parallel windings into two EV CPT charging systems so as to constitute two cascaded contactless transformers, a novel contactless bidirectional resonant converter (CBRC) is proposed in this paper. Based on which, an emergency battery charging system is also presented. The equivalent circuit of the cascaded contactless transformers and the topology of the CBRC are analyzed and discussed in this paper and the series-series compensated double full bridge CBRC is finally adopted as the main circuit. This paper takes a thoroughly study on the control strategies for the proposed CBRC. After proposing and analyzing three possible control methods, primary constant frequency plus secondary PWM control and primary PLL and PWM control are adopted. Finally, an 1800 W CBRC prototype with two control methods is fabricated to verify the theoretical analysis and the effectiveness of the proposed control strategies.