基于SVPWM和模糊PI参数自整定的Z源逆变器并网研究

Research on Z Source Inverter Grid-Connected System Based on SVPWM and Fuzzy PI Control of Parameter Self-Adjustment

相比于传统的电压/电流型逆变器,Z源逆变器能实现升降压变换的功能,同时桥臂不需要死区时间,变换器可靠性更高。在传统SVPWM调制方法里,通过在零矢量中插入直通状态(同一桥臂同时导通),使其应用在逆变器中。Z源逆变器在实现更好交流输出的同时,实现了对直流侧电压任意倍数的升压。对于Z源逆变器传统的控制策略是采用电压外环和电流内环构成的双环PI控制,但双环PI控制无法达到较高的控制精度并且并网电流谐波畸变率较高。针对PI控制的局限性,提出了模糊PI控制器。该控制器利用模糊控制技术,根据误差大小对PI参数进行实时在线调整,从而满足最优的性能要求。通过仿真研究,试验结果证实了所提方法的有效性和正确性。

Compared with the traditional voltage source inverter （VSI） and current source inverter （ CSI）, Z- source inverter had the ability like buck-boost conversion and no dead time was needed in phase legs, so high reliability could be achieved. A space vector pulse width modulation （SVPWM） technique was modified to realize the shoot-through zero vectors in the Z-source inverter（ZSI）. The Z-source inverter could generate a more ideal sinusoidal AC output voltage and step up the DC-link voltage in any multiple. For the Z-source inverter, the traditional control strategy often used the double loop PI control of outer voltage loop and inner current loop. It was hard to achieve higher control accuracy while using the control of traditional double PI loop and the harmonic distortion rate of grid- connected current was high. According to the limitations of traditional PI control, a fuzzy PI controller was proposed. The controller took advantage of fuzzy control to adjust the PI parameter online according to the error, so as to meet the requirments of optimal performance. Through the simulation experiment the effectiveness and validity of the proposed method were verified.