The Control Technique Of Three-phase Inverter

The non-grid-connected inverter is widely applied in the fields of military, industry, civil use and services.Under such condition the research on the control technique of single inverter is still of great significance. Therefore, in this paper, we focus on the control technique of inverter's output voltage and the unbalanced load disturbance rejection.(1)Firstly, this article introduced and analyzed the advantages and disadvantages of commonly used type of three-phase voltage source inverter topology,and indroduced the the mathematical model of inverter in three kinds of system. Then it illustrated the phenomenon that when system is controlled under the two phase rotating coordinate system, the control volumes are mutual coupling. Finally, through the theoretical analysis and simulation prove that this coupling mainly affects the dynamic performance of inverter.(2)This article firstly analyzed advantages and disadvantages of several control methods, and chose the double loop control strategy with load current feed-forward,in which inductor current current feedback in the inner loop and inductance capacitance voltage feedback in the outer one. This control strategy can not only realize the function of current limiting, but also has good dynamic characteristics of the system at the same time. In order to improve the quality of the output voltage waveform, the harmonic controller is setted in the outer loop.The controller parameters is designed based on analysis. Simulation and experimental results show that the designed parameters not only make sure the system has good dynamic characteristics, but also improve the quality of the output waveform.(3)Finally, as for the problem of the inverter's output voltage imbalance caused by unbalanced load, the article firstly analysis the principle why improve controller's the gain of secondary component analysis can improve the system's resistance of unbalanced load. To improve the second time gain, the method in the article adds a second resonant controller in the traditional PI and repetitive compound controller and analyze its stability condition. At last, the result of simulation and experiment verify the reliability of the control method.