An LCL composite resonant-type bi-directional contactless power transfer mode

Classical single-load bi-directional inductive power transfer systems have some drawbacks such as low resonant capacity and high voltage and current stress of switching devices. Based on LCL composite resonance, a bi-directional power energy transfer mode using symmetric topology was proposed. The impedance model for alternating current was presented and the gain between the input and output was deduced. By analyzing the frequency responses and the output power under different loads and coupling coefficients, an output voltage regulation method was proposed, which runs in the bi-operation mode between energy injection and free running. Furthermore, a duty cycle control method for the bi-operation mode was also proposed to guarantee the stability of output voltage. The simulation and experimental results indicate that the proposed mode can achieve bi-directional energy transmission and the output voltage ripple less than 0.3 V. Moreover, this mode is simple and easy for implementation.