The Key Technology Research Of A Multi-level Current Reinjection Current Source Converter

This paper studied a new topology of Five-level Current Reinjection-Current Source Converter(FLR-CSC).The new topology adds a set of reinjection circuit to the traditional 12-pulse rectifier circuit,the current of DC side is modulated as the theory requires by controlling the reinjection switches regularly,as a result of which,the current of AC side is similar with sine wave of 48 levels.The followings are advantages of the new topology compared with the traditional one:(1)The introduction of current harmonics inject method improves the current distortion of AC side,so the number of filtering equipments is cut down in high power application,saving space and cost accordingly.(2)In new topology,the reinjection circuit is introduced providing a zero current region periodically in which the main bridge switches can act,hence the new topology realizes ZCS,making it possible to reduce the switching loss and increase the power capacity.(3)When the DC side is the resistance-inductance load,the traditional 12-pulse rectifier circuit can only work at the condition of 0°???90°,while the new topology expanding the scope to-90°???90°,so it is able to supply reactive power,which can wide the application of the new topology.This paper focuses on the following works:(1)The topology structure of the new FLR-CSC is introduced,and the mathematical expression of the injection current is deduced,which provides the theoretical basis for designing the control pulse of each switch.The control mode of switch between main bridge and injection bridge is studied,and the modulation principle of injection switch is summarized.The effects of different injection levels on the harmonic elimination are compared.(2)The performance of the injection circuit directly affects the operation of the FLR-CSC.In this paper,the simulation of the system under three different triggering pulses of injection switches is carried out,the simulation results are analyzed and summarized,so it can be applied to the engineering practice.The principle of FLR-CSC is analyzed.Based on this,a scheme of power decoupling of FLR-CSC series topology is studied to lay the foundation for the further development of the new topology.The feasibility of the scheme is verified by simulation..(3)The system structure of the 4KVA prototype is introduced in detail,including the design of the control module,the driving module and the power module.The triggering pulse of the main bridge switch and injection switch of the prototyping are sent out by FPGA,and the principle of programming based on VHDL is analyzed and verified by simulation.,so this paper analyzed prototype platform results,in contrast to theory.Finally,the shortcomings of FLR-CSC topology and the research direction are summarized.