基于无电解电容AC/AC变换的无线充电系统优化控制研究

Research on optimal control of wireless charging system based on AC/AC conversion without electrolytic capacitor

针对传统无线电能传输系统原边整流级和逆变级之间采用电解电容,使系统成本高、体积大、功率密度低,以及副边不控整流和DC/DC变换器的组合增加了系统的成本、体积、和复杂性等问题,提出了一种改进的无线电能传输系统,去掉了原边整流级和逆变级之间的电解电容,副边采用半有源整流器来代替不控整流和DC/DC变换器的组合,减少了无功元件和开关器件的使用,简化了系统结构,节约了成本,提高了功率密度。通过对系统进行数学建模,分析了电网电流谐波来源和影响传输效率的关键参数。在原边采用移相角随工频周期线性变化的调制方式来减小电网电流的谐波失真,副边通过检测谐振电流过零点,在电流过零处对开关管施加触发脉冲,使电流和电压同相从而等效阻抗中不含无功阻抗,提高了效率。原副边之间无需通信,实验结果验证了数学模型和调制方案的有效性。

Aiming at the problems of high cost,large volume and low power density of the system due to the use of electrolytic capacitor between the primary rectifier stage and the inverter stage in the traditional radio energy transmission system,and the combination of secondary uncontrolled rectifier and DC/DC converter increases the cost,volume and complexity of the system,this paper proposes an improved radio energy transmission system,which removes the electrolytic capacitor between the primary rectifier stage and the inverter stage.The secondary side adopts semi-active rectifier to replace the combination of uncontrolled rectifier and DC/DC converter,which reduces the use of reactive components and switching devices,simplifies the system structure,saves cost and improves power density.Through the mathematical modeling of the system,the source of power grid current harmonics and the key parameters affecting transmission efficiency are analyzed.The primary side adopts the modulation mode that the phase shift angle changes linearly with the power frequency cycle to reduce the harmonic distortion of the power grid current.The secondary side detects the zero crossing of the resonant current and applies a trigger pulse to the switch at the zero crossing of the current,so that the current and voltage are in phase,so that the equivalent impedance does not contain reactive impedance and improves the efficiency.There is no communication between the primary and secondary sides.The experimental results verify the effectiveness of the mathematical model and modulation scheme.