采用Z源变换器的小型风力并网逆变系统

基于Z源变换器的小型风力发电并网系统的工作特点及控制结构,不同于传统的电压型逆变器,Z源变换器引入特定的阻抗源网络将变换器主电路和电源耦合在一起,并且通过新增直通零矢量调制实现独特的直流升压功能,从而得到大范围变化的交流输出电压.经过对系统电路和要求的分析,文章对控制系统进行简单的设计.通过原有正弦波调制因子的控制,实现内环并网电流的单位功率因数运行和外环Z源电容电压的稳定;通过直通零矢量调制对发电机输出整流电流进行闭环控制,实现风力发电机的电能输出控制.最后,以2.5kW Z源变换器装置进行实验,实验结果验证了分析的正确性.

Small Wind Turbine Grid-Connected Systems Based on Z-Source Inverter

It presents a small wind turbine grid-connected generating system based on Z-source inverter, including the operating character and the control configuration. The Z-source inverter employs a unique impedance network to couple the inverter main circuit to the diode front end and can be shoot through to boost the DC link voltage, so the widely range AC voltage can be obtained. The whole control systems are designed based on analyzing the circuit and systems object. By controlling inhere sine modulation index, the grid-connected current inner loop to ensure system working in unit power factor and the Z-source capacitor voltage outer loop is adopted to ensure the voltage stabilization; by controlling the shoot-through duty cycle, the wind turbine output rectified current is controlled. Lastly, a 2.5kW Z-source inverter circuit is built and the experiment results validate the operating principle.