Research On Single Phase Multilevel Current Source Inverter Topology And Control Strategy

With the rapid development of domestic economy, the industry to have the large capacity of converter which has good output performance is increasing strongly, then it has to use such as fast response speed, low switching frequency and large power capacity of the multilevel converter. But with the continuous development of superconducting energy storage technology, and at the same time, there appeared the high reverse blocking voltage capability of semiconductor devices, such as IGBT, etc. The working efficiency of the current mode converter will be effiectively solved. Making multilevel current source converters get rapid response, short circuit protection, current direct control, the excellent characteristics of good electromagnetic compatibility, etc.In this thesis, on the basis of reading a large number of references,the current three-phase multilevel inverter topology has carried on the summary and induction, the working principle of single-phase circuit unit module for the theoretical derivation and analysis. On the basis of the existing three-phase and single-phase voltage type topology structure, it deduced the Ⅰ,Ⅱ,Ⅲ type of single-phase current multilevel converter topology. And worked out the appropriated of PWM modulation strategy and control strategy for the multilevel current source converter.First of all, in this thesis the duality principle in the application of circuit had been made a deep research in detail. It deduced the dual relationship of nonlinear devices, transformers and switches, etc. Precondition for equivalent conversion of circuit topology must be planarized simultaneously the complex circuit is simplified to single network, and using dual method respectively. It isolated the single-phase topology from the voltage type three-phase multilevel inverter and derivation and derivative the new work unit.Secondly, under the condition of inductive load and capacitive load, the derivation and the working principle of the topology of the derived frequency mathematical model is established. Carrying on the shunt inductance voltage of mathematical modeling, studied this kind of converter circuit current balance characteristics. Draw the appropriate conclusions and provides a theoretical basis for the current control.Thirdly, study the carrier phase-shifted SPWM, the ladder wave PWM,APOD-PWM, POD-PWM,PD-PWM modulation,Walsh-SHEPWM strategy and open loop type single-phase current closed-loop control strategy in the multilevel inverter topology circuit output characteristic of the application. Various modulation strategies for the double Fourier transform mathematical modeling analysis, from the perspective of mathematical model for the output of the circuit characteristics were described in detail.Finally, in the topology and its modulation strategy, the control strategy has carried on the simulation analysis, validate the new topology and its mathematical model, the correctness of the modulation strategy and control strategy of the switch used.The topology in the corresponding switch modulation strategy and control strategy, the output characteristic of current net side current, power factor, total harmonic distortion rate and response speed are obviously improved. Finally, at the end of this paper, the full text is summarized, the type of single phase current direction of the research and application of multilevel converter is discussed.