不连续空间PWM的无电网电压传感器的三相并网逆变器

摘要

In order to improve the reliability and further reduce the cost of three-phase grid-connected inverter,a control strategy without grid voltage sensors is adopted based on the virtual grid flux. Based on its mathematical model in synchronous rotating frame, the virtual grid flux vector orientation and current close -loop controls are used to realize the decoupling control of d-and q-axis currents for the active and the reactive power controls respectively. The relation and difference between CSVPWM(Continuous Vector PWM)and DSVPWM(Discontinuous Vector PWM) are analyzed in details. The essential difference is the selection of zero vectors, different zero vector resulting in different PWM. According to the characteristics of three -phase grid-connected inverter,DSVPWM is adopted to reduce the switching losses. Simulative and experimental results show that,the grid- connected inverter based on virtual grid flux orientation and DSVPWM has good dynamic and static performances,verifying the feasibility and correctness of the control strategy.%为提高三相并网逆变器的可靠性和进一步降低三相并网逆变器的成本,采用了一种基于虚拟电网磁链的无电网电压传感器的控制策略.根据三相并网逆变器在同步旋转坐标系下的数学模型,采用虚拟电网磁链矢量定向的矢量控制和d、q轴电流闭环控制,实现了d、q轴电流的解耦控制,使q轴电流控制有功功率,d轴电流控制无功功率.详细分析了连续空间PWM和不连续空间PWM之间的联系和区别.连续空间PWM和不连续空间PWM之间的本质区别在于零矢量的选择,选择不同的零矢量从而导致不同空间PWM.为了减少开关损耗,针对三相并网逆变器的特点,采用一种不连续空间PWM方式.仿真和实验结果看出:基于不连续空间PWM和虚拟电网磁链矢量定向的三相并网逆变器具有良好的动、静态性能,从而验证了该方案的可行性和正确性.