Design And Engineering Realization On T-Type Three Level Inverter

High power, light weight, miniaturization are the future direction of power conversion system(PCS), and three-level T-type topology has a huge advantage in this aspect. The three-level converter has been one of the research focus topics in the field of high-voltage and capacity electrical energy. Through different combinations of switches, multi-level ladder wave output voltage can effectively improve capacity and voltage pressure levels of inverters, reduce the output voltage harmonic and switching losses. But more switches and control demand cause complicated control method. So the space-vector PWM(SVPWM) is analyzed in three level converters.The dissertation mainly presents the construction and control strategies of AC drive system based on three-level inverter. First, the thesis introduces the development and application about the technology of three-level T-type topology in detail and discusses the prospect about them. Second, the thesis presents the principle of three-level T-type inverter, and establishes the mathematical model. Third, an LCL-filter and bus capacitor design approach with suitable filtering-inductor voltage drop and good bypass effect for switching ripple provided by capacitor and grid-side inductor is proposed based on LCL-filter operation characteristic analysis, and takes advantage of MATLAB software to simulate those strategies. Fourth, the thesis analyzes the principle of many kinds of SVPWM control strategies based on three-level inverter, and uses MATLAB software to simulate all control strategies, compares the disadvantage and advantage of them, and compares the influence of all method on output harmonics and neural point voltage and so on, the thesis offers reference value for the application in engineering of those control strategies. At last, through theoretical study and simulation a control system which has a DSP as the control center of the system has been constructed, the improved method of carder modulation which based on three-level SVPWM algorithm and the neutral point balancing methods are applied in the experiments, The experiment results show the feasibility and effectiveness of the global algorithm and the control strategy.