Z源并网逆变器的间接单周电流控制策略

摘要

针对直接电流控制方式需要较多的采样环节造成控制电路结构复杂,且控制精确度依赖于传感器精确度的缺点,提出一种无需电流采样环节的间接单周电流控制方式.以单相Z源并网逆变器为对象,建立其状态平均数学模型,以实现单位功率因数并网为控制目标推导占空比控制函数d(t),利用单周控制的思想,根据d(t)产生相应的开关驱动信号,从而控制并网电流.仿真结果表明,逆变器输出电流与电网电压同频同相,并能够根据输入功率的变化而改变并网功率.该控制方式的控制电路结构简单,控制成本低,同时该控制方式的基础是系统的状态平均模型,克服了传统的间接电流控制策略动态响应慢的缺点；单周控制的引入也保证了系统具有良好的鲁棒性.%Because of needing more sampling sectors, the direct current control method had disadvantages of complex control circuit, and the control accuracy depended on the accuracy of the sensor, so the indirect one cycle current control method with no current sampling sensor was proposed. Targeting on the single phase Z source grid-connected inverter, analyzing its steady-state mathematical model and deriving the duty cycle control function d(t) with the goal of realizing grid-connecting with unit power factor, then based on the ideas of one cycle control, the corresponding switch drive signal was generated according to d(t) , finally the grid current was controlled. Simulation results show that the output current of the inverter has the same frequency and phase with the grid voltage, and can change according to changes in input power. In this control method, the structure of the control circuit is very simple and the cost is low, while this method is based on the average model state of the system, the shortcomings of slow dynamic response of the traditional amplitude and phase control strategy is overcome; in addition, the use of one cycle control also ensures the system have good robustness.