Z源三电平并网逆变器的准PR控制系统

Quasi-PR Control System of Grid-connected Z-source Three-level Inverter

Z源三电平逆变器将具有独特性能的Z源拓扑和高性能的三电平逆变器相结合,能够充分发挥两者的优势。由于Z源三电平逆变器的拓扑结构相比两电平逆变器更加复杂,为了避免并网控制策略中复杂的坐标变换和解耦过程,进而提高系统效率,将准PR控制引入Z源三电平并网逆变器中。在理论分析的基础上,将准PR控制和SVPWM调制算法相结合,设计出了系统完整的控制策略,实现了Z源三电平逆变器在两相静止αβ坐标系下对电网交流信号的无静差跟踪,简化了传统的系统控制结构,提高了系统的性能。最后在Matlab/Simulink仿真软件中建立了Z源三电平并网逆变器的的仿真模型。仿真结果表明,相比于传统的两电平逆变器,该三电平逆变器输出的电压更接近正弦波,谐波畸变率更低,系统的鲁棒性更强。

The Z-source three-level inverter combines the unique structure of Z-source inverter and the high performance of three-level inverter together, which can make full use of the advantages of both Z-source and three-level inverter. Since the topology of Z-source three-level inverter is much more complex than that of two level inverter, in order to avoid the complex coordinate transformation process and the decoupling process in the grid-connected control strategy, and to improve the utilization of the system, the quasi-PR is introduced control into Z-source three-level inverter. Based on the theoretical analysis, the quasi-PR control and SVPWM are combined, the complete control system strategy is designed to achieve no-static-error tracking of the AC signal in the two-phase stationary αβ coordinate system, and the traditional system control structure is simplified, meanwhile,the performance of the system is improved. Finally, the simulation model of the grid-connected Z-source three-level inverter is established by using the Matlab/Simulink simulation software. The simulation results show that, compared with traditional two-level inverter, the output voltage of three-level inverter is closer to sine wave, the total harmonic distortion rate of three level inverter is lower, and the system robustness of three-level inverter is stronger.