无线电能传输零电压开关角跟踪和动态电容补偿矩阵复合控制策略

Composite Control Strategy of Zero Voltage Switch Angle Tracking and Dynamic Capacitance Compensation Matrix for Wireless Power Transfer

为了保证动态无线电能传输(DWPT)系统工作于较高的电能传输效率和传输功率,减小由于系统参数变化导致的传输功率和传输效率的下降。该文提出一种零电压开关角(ZVSA)跟踪和动态电容补偿矩阵(DCCM)相结合的无线电能传输系统频率跟踪控制策略。采用电流传感器来获取谐振电流的相位,并利用处理器产生的参考信号来测量谐振电流的相位。微控制根据频率漂移的程度计算补偿电容的大小,粗略地将自然谐振频率调至85 kHz,然后系统自动跟踪谐振电流相位,对谐振频率精确跟踪。该方法通过直接对相位检测电路输出的直流信号进行采样,轻松地获取高频电流的相位,大大降低了对微控制器的占用。该文提出的控制策略和系统结构结合了模拟电路和数字控制的优点,不仅对系统参数变化有高动态响应,而且极大地节省了处理器资源。

Changing parameters of dynamic wireless power transfer systems can affect power transfer efficiency.This paper proposes a frequency-tracking control strategy for the DWPT system combined with zero voltage switch angle tracking and a dynamic capacitance compensation matrix.A current sensor is used to obtain the phase of the resonant current,and a reference signal generated by the processor is used to measure the phase of the resonant current.The micro-control calculates the size of the compensation capacitor according to the degree of frequency drift,roughly adjusts the natural resonant frequency to 85 kHz,and then automatically tracks the resonant current phase.Firstly,the structure of the wireless power transfer system and the working conditions of constant current and constant voltage charging are analyzed,and the relationship between the output voltage/duty cycle and working frequency is deduced.The output voltage can be adjusted by manipulating the duty cycle D andω.The working principle of the dynamic capacitance compensation matrix is also analyzed.By adjusting the dynamic capacitance compensation matrix,the resonant frequency of the circuit can be tuned.Next,the operating principle of the phase detection circuit is analyzed,and a new phase detection method is adopted to effectively improve the system’s anti-interference capability.The components of the system are introduced,and the working principle of each part of the circuit is explained.Then,a control strategy is proposed combining dynamic capacitance compensation matrix and zero-voltage switching angle tracking.The battery load charging and anti-disturbance are simulated.The results show that the composite control strategy can realize the battery load charging while tracking frequency.Finally,the efficiency of the control method is quantitatively compared with the existing control methods.The proposed method acquires the phase of the high-frequency current by sampling the DC signal derived from the phase detection circuit,greatly reducing the microcontroller’s computational workload.The control strategy and system structure proposed in this paper combines the advantages of analog circuits and digital control,which have a high dynamic response to system parameter changes and save processor resources.With precise zero-voltage switching angle control,the system can achieve zero-voltage switching over almost a large load range,and its efficiency reaches up to 91.19%when k=0.25.