感应电能传输技术是一种利用磁场耦合来实现电能以无接触的方式进行传输的技术。在系统中，由于开关管在谐振电容电压非零点切换会导致环流的出现。环流使谐振电容电压波形发生畸变，EMI增强，开关管损耗增大，严重影响系统的稳定性和传输效率 ［6］。通过分析指出谐振频率变化是环流产生的原因。通过分析开关管在谐振电压过零点之前和过零点之后切换时环流的特点以及开关频率与谐振频率之间的关系，提出一种通过实时检测环流方向，动态调节开关频率与谐振频率一致，以保证开关管在谐振电容电压过零点切换，从而抑制环流。给出了以FPGA芯片为载体的环流抑制系统的设计方案。通过搭建硬件电路验证了该控制方法的有效性。

Inductive power transfer (IPT)technology allows electrical energy to be transferred between two loosely coupled inductors over relatively large air gaps based on electromagnetic induction. In current-fed IPT systems,resonant capacitor voltage distortions and current spikes on the semiconductor switches are easily caused when switches isn’t switched at zero crossing point of resonant voltage. As a result,the EMI level of the system and the switching loss are increased and thus the system transmission stability and efficiency decrease. The article analyzes the production mechanism of circulating current in load resonant high frequency inverter and points out that the resonant frequency change is the real cause. By analyzing the characters of circulating current before and after the zero-crossing points of resonant voltage and relationship between switching frequency and resonant frequency,this paper proposes a method of real-time detection for the direction of circulating current,and regulating the switching frequency in accordance with resonant frequency dynamically to ensure the switching of switch tubes at the zero-crossing points of the resonant capacitor voltage,and thus to inhibit circulating current. An experiental system with the platform of FPGA is set up to verify the effectiveness of this control method.

重庆市国际科技合作计划项目 (CSTC,2011GGHZA40001)