| Nowadays, high voltage variable frequency and speed control technology hasgradually become an important part in the field of power electronics. As animportant topological structure, cascaded multilevel inverter usually requiresreal-time control with multiple power switching devices. To control moreaccurately and simply, research of multilevel-inverter various modulation methodshas gradually become hot and difficult. As a vital link influence the control effectof invert, multilevel Pulse-Width Modulation(PWM) attracts widely attention. Themethods of PWM are divided into two kinds：triangular carrier modulation andspace vector modulation method. This paper focuses on the research of cascadedmultilevel inverter space vector modulation(SVPWM) technology which relates tothe multilevel inverter topology, modulation methods, and analysis of relationshipand rules of these methods. The superiority of the space vector modulation isillustrated by analyzing several basic modulation methods through softwaresimulation and specific experimental verification. This paper describes the designof cascaded high-voltage inverter experimental platform in detail.(1) High-voltage inverter especially cascaded high-voltage inverter currentsituation at home and abroad, and the exist development problems of hi gh voltagefrequency converter in our country and the gap between our country and developedcountries such as Europe、 the United States and Japan exists in this field issummarized in this paper, solutions and low carbon energy-saving applicationprospect in future is stated. Research of multilevel inverter topology structure,control technology and modulation method is presented.(2) The topological structure of high voltage frequency converter is describedin this paper. Principles and design ways of three kinds of high-voltage invertertopologies are described too. By analyzing these topological structures andcompared with the other two，cascaded multilevel inverter structures shown moreadvantages precisely.(3) A variety of modulation methods of multilevel inverter are described,including ladder wave modulation method, SPWM method etc. The principle andclassification of SPWM and three times harmonic injection modulation method ofSPWM with harmonic analysis are introduced in this article. (4) Study of space vector modulation showed that essentials differencebetween SVPWM and SPWM. A general space vector PWM generation scheme formulti-level inverter which is based on the principle of mapping is presented in thispaper. Finally, some advantages of space vector PWM are summarized.(5) A cascaded high-voltage inverter experimental platform is built； thealgorithm simulation is realized with Matlab/Simulink simulation continuousdomain model system. The software、hardware part of the control system aredesigned with DSP and FPGA as core. A structure of cascade high-voltage invertersystem which is based on the technology of space vector PWM；a main circuit forpower unit; multiplex pulse of FPGA; switch input and output data of DSP；digital-analog conversion; frequency measurement are designed. DSP mainprogram and communication module for experimental platform are changed thenexperimental results are obtained to verify the proposed modulation method in thispaper, which promote the cascade multilevel inverter application in high voltagefrequency domain and has a widespread industrial prospect. |
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