Research Of Control Algorithm On Three-level Convertor

Nowdays with the technical requirement of low-carbon life and enregy efficient reduction, research on energy saving technology, especially high power convertor is becoming more and more attention to us. There is a limit to the voltage for two-level convertor, and it can't make direct convert to high voltage. Howerver, multilevel converter, especially three-level converter has some advantages of low hormonics, high power factor and low power loss. It is widely used in electric network transformation and communication driver. The control algorithms of multilevel converter have become the focus of research.This paper analyses the structure and operational principle of three-level converter and introduces several different three-level topology structures and their merits and faults. On basis of this, the principle of Neutral Point Clamped (NPC) Converter is selective analysis, especially the achievement of three circuit switch modes. According to the working characteristics of multilevel converter, SVPWM control algorithm of common three-phase convertor is detailed introduction, including sector judgement, basic vector seclecion, working time calculation, vector working sequence and switch state sequence.In the study of this paper, we use MATLAB/Simulink simulate toolbar. Through building simulated system model, we simulate the control strategy of three-level converter, and achieve the waveforms of line voltage and phase voltage by changing the input direct voltage. In the environment of Matlab, we can use wavelet transform to detect the open fault of power switch. In the laboratory, we build the hardware experiment system and use TMS320LF2407ADSP to program. According to the comparison of simulation and experiment results, we can draw the conclusion that the experiment system is reasonable and the control algorithm is right, as well as realizing the online analysis.