| With the development of new energy industry and power electronic technology,three-level topology construction has gradually became research highlights in middle-high voltage and high power application. Owing to the merits of low withstand voltage of devices, perfect output waveform and low switching losses; it has widely been used in the high voltage variable frequency speed regulation, inverter and rectification, FACTS and photovoltaic power generation systems.Because of various topology and control strategy of three-level inverter, and T-type three-level NPC topology as the research object in this paper., the space vector pulse width modulation(SVPWM) algorithm were theoretical analysis, with T-type three-level topology characteristics, simulation and experimental verification.The problem of neutral point potential balance control in T-type three-level topology inverter is analyzed and studied. And the current mathematical model of it is established. From the view of SVPWM control algorithm, the reasons of neutral point potential unbalance get deeply analyzed. On the aspect of neutral point potential control,not only the control of neutral point potential by the addition of the converter is analyzed in hardware construction, but the vector adjustment factor is introduced to redistribute the action time of each vector in the software control algorithm.Simultaneously, according to the charge balance of voltage dividing capacitor, vector adjustment factor is determined which can effectively control the neutral point charge balance. At the same time, it can effectively avoid the influence of the parameter difference of the two voltage capacitance on the Neutral point potential.The T-type three-level inverter model is established in MATLAB/Simulink which purpose is to simulate and verify the control algorithm. On the basis of simulation study,the hardware and software of the system are designed; the experimental platform of T-type three-level inverter is built. |
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