The Research On The New Topology Of Multi-level Reinjection Current Source Converter

Multi-Level Reinjection Converter is based on dc-ripple reinjection,the converter ac side obtain perfect sine ac voltage or ac current via approximating ideal injection current or voltage waveforms at converter dc side.The Multi-Level Reinjection Converter merges technology of multi-level、harmonic injection and soft switching,so it possesses high technology advantage,the converter switches work in low frequency condition,switch losses reduce greatly.The converter ac side reduce inconvenience of installing huge and expensive filtering devices.Multi-Level Reinjection Current Converter(MLCR—CSC)is based on traditional three-phase twelve pulse converter,the MLCR—CSC approximates ideal waveform at dc side by adding injection circuit,so it can obtain sine current of more step number in unit cycle.The main switches working frequence is 50Hz,injection switches working frequence is 300Hz,the main switches switch in zero area,so its switch losses reduce greatly.The original circuit of MLCR—CSC have higher requirements to injection circuit switches,and main switches can not switch in zero area thoroughly.This paper improved original circuit structure,made the new MLCR—CSC reach thorough zero current switching,also reached ac current phase and amplitude free adjustment.This paper made simulation analysis to seven-level injection circuit under the PSCAD/EMTDC software environment and verified correctness of working principle.The paper summarized waveforms and topological structure characteristics of new MLCR—CSC via making simulation to 3～9 level injection circuit.In order to conduct experiment on circuit running and realize current sharing of injection branch,the paper designed two different pulse cycling methods with state traversal for the principle.The paper gave specific sequence analysis and simulation diagram.This text used VHDL hardware language to program trigger impulse of main switches and injection switches based on Quartus Ⅱ 7.2 software,the paper gave the specific designing and writing process of program.In order to checkout the correctness of programs the paper made the simulation to program and give simulation figure.In the end the program was proved to be right by test on the EP1C6Q240C8N FPGA platform and the paper gave the two different pulse cycling experimental waveforms.The new MLCR—CSC experimental plattform was set up in the laboratory,its actual capacity is 15kVA.The experimental apparatus was conducted operation experiment via using one of designed pulse cycling methods,and the experimental results verified the correctness of new MLCR—CSC working principle.These experiments made a great contribution to follow-up tests and device application.The paper extracted and sowed related experimental waveforms.