Research Of Cascaded Multilevel Inverters Based On DSP

With the development of electrical drive technology recently, High voltage and highpower inverter has already become one of research focus in AC drives. It not only could enhancethe turnout and quality of products, but also could economize large numbers of power energy andreduce production cost if high voltage motor could change their velocity smoothly using highvoltage inverter. It has huge market potential and widely application in the future.Multilevel power conversion has the ability to make lower voltage semiconductors bestably used to high-voltage and large-capacity applications while reducing the high orderharmonics produced by PWM control efficiently. But its topology and control is rathercomplicated. Due to expanding to medium-voltage fields easily, cascaded multilevel powerinverters have been utilized in medium-voltage motor drives and reactive power compensationsof power system. This dissertation is devoted to research the topological structure, PWM controlmethod and application in motor drives of cascaded multilevel inverters, so that someeffective methods for optimizing topology and improving control performance could beproposed.Cascaded multilevel power inverters are different from traditional 2-level powerinverters. Because of an increase of switch components, the distribution of driving impulse iscaused. Moreover, there exists some technique difficulty about interface of driving impulsebetween digital signals process available and switch components of multilevel power inverters.Hence, considering the control system consisted of cascaded multilevel power inverters, theoperating mechanism of 3-cell serial inverter is analyzed in depth based on the main circuit ofcascaded multilevel power inverters. Then contrast and analyze the Pulse Width Modulation forCascaded Multilevel Inverter. The result of experiment is discussed, and the conclusion issignificative. This dissertation provides experimental data and guideline of technique. At last,under analysis of theory and emulational validation, it designed the whole experimental system, including the main circuit, control unit, (based on DSP&CPLD), in order to improve theperformance of system.