Research On Adjustable Three-level Inverter

With the power electronic devices applied in power systems, industrial, rail transport,reactive power and harmonics that devices generate are also growing. Reactive power andharmonics reduce the reliability of the power electrical equipment, even may damage thedevice and affect the operation of the grid safe in severe situations. China’s power grid waslarge-scale, long distance, large capacity, AC and DC transmission and mixing a variety ofcontrol devices, which device that China’s power grid will face security and stability risks.Therefore, the use of High-voltage large-capacity Integrated Flow Controller and Active filterwhich use multi-level inverter technology is an effective treatment method. In this case,multi-level inverter power electronics become an important research focus. Multi-levelinverter technology is an emerging energy conversion technology, still in development stageand the majority of research workers need do a lot of research work.First, this paper analysis the research purpose and significance of the three-level inverterdetailed, followed analysis the three-level inverter topology and control strategy, Aftercomprehensive analysis, the paper select the diode-clamped three-level inverter as the studyobject and select the space vector algorithm as the control strategy of this circuit topology.Article analysis the three-level inverter works detailed, gives the three-level space vectormodel, the method to determine the reference vector, the method of calculation of the vectorwork time, the optimization sequence of the vector and build the simulation model to verifythe correctness of the algorithm.The DC side of the circuit exist the phenomenon of midpoint potential imbalance, Thepaper raised the control algorithm to balance the midpoint potential and verified it inMATLAB, for the problems exited in control algorithm the paper gives continuousimprovement to make the midpoint potential in the reasonable range.The paper studied induction motor vector control system based on three-level inverterand analyzed simulation results, The results showed that the induction motor can achieve agood dynamic performance.Finally, the paper gives the three-level inverter system hardware design and softwaredesign, it uses TI’s DSP2812 as the core controller, builds the peripheral circuit and designsthe software flow chart.