Abstract: The high frequency AC power supply for wireless power transmission systems is provided by the class D power amplifier, and the receiving end uses the DC-DC converter to optimize load. Base on this research, the problem of reducing the transmission efficiency caused by the dynamic change of load condition, coupling coefficient and frequency offset is solved using the maximum power tracking control strategy, which includes frequency tracking and load tracking. The efficiency of the wireless power supply system is analyzed by the equivalent model of the transmitter and receiver circuit, and the optimal value of the equivalent load impedance matching is obtained. An integrated control strategy based on frequency tracking by phase locked loop and load tracking by searching for the minimum input power operating point for a given output power is proposed to keep the system output power and efficiency constant. The experimental results show that the proposed control strategy can automatically track the frequency and load changes, so that the system can always keep the resonant state, track and maintain the maximum energy transfer efficiency according to the load condition.

Key words:

Electromagnetic resonance, wireless power transmission; coupling efficiency; efficiency tracking

摘要： 在无线电能传输系统中采用D类功率放大器作为髙频交流电源，在接收端使用DC-DC变换器优化负载，并在此基础上研究了包括频率跟踪和负载跟踪在内的最大能量跟踪控制策略以解决负载条件、耦合系数和频率偏移的动态变化引起的传输效率降低问题。通过发射端和接收端电路等价模型对无线供电系统效率进行了分析，得到等效负载阻抗匹配优化值。提出了基于锁相环的频率跟踪和给定输出功率条件下寻找最小输入功率的工作点的负载跟踪集成控制策略，使系统输出功率和效率保持不变。实验结果表明，提出的控制策略能够自动跟踪频率和负载变化，使系统始终保持谐振状态，根据负载条件跟踪并保持最大能量传输效率运行。

关键词: 电磁谐振, 无线电能传输, 耦合效率, 效率跟踪