Parameters Optimization for Zero-Voltage-Switching Realization in LCCL-LC Compensated MCR WPT Systems

Recently, LCCL-LC compensated magnetically coupling resonant wireless power transfer (MCR WPT) systems are widely used to achieve the constant and load independent output voltage performance compared with other counterparts. To analyze the zero-voltage-switching (ZVS) conditions of the system, the fundamental harmonic approximation (FHA) model is usually utilized, but the analytical results are not accurate due to the neglect of high order harmonics. In this paper, a time domain model considering high order harmonics was proposed to solve this issue. Based on that, a method of modulating the compensated capacitor was put forward to realize ZVS within the full range of loads. However, this method will cause the system to deviate from its full resonance state and further deteriorate the system efficiency. To enable the system to realize ZVS in the full resonance state, the improved optimization method to modulate the compensated inductor was proposed. Finally, a 1kW prototype was built and a series of experiments were carried out, the experimental results demonstrate the effectiveness of the parameters optimization for ZVS realization. The overall efficiency enhancements by the two proposed methods are 0.47% and 1.31% respectively.