Research On Modular Multilevel Rectifier

MMR modular multi-level rectifier with the characteristics of cascade rectifiers, easy to implement multi-level number and the modular design and can achieve the DC side of the back to back connection, is a very suitable for multi-level VSC HVDC topology.Compared to traditional two-level or three-level voltage derived rectifier, the modular multi-level just by changing the number of sub-module used by the MMC can be made to meet the different voltage and power requirements and wide range of applications field, MMC can use the same hardware and mechanical construction.Firstly, this paper firstly compared and analysed three topology structure for modularization multilevel rectifier,and then emphasis on working principle and mathematical model of a double-star-configured modular multi-level converter;for modular multi-level rectifiers, we proposed dual-loop control system design and control strategy design of carrier phase shift, we also made simulation for modular multi-level rectifier at the same time, we got simulation waveforms based on this model which are obtained by simulation software PSCAD/EMTDC, we known this control strategy is correct and effective through the simulation waveform; Secondly, it is focused on a modular multi-level sub-module rectifier capacitor voltage balance control method, and the sub-module implementation of pre-charge capacitance method; Finally we made designs on modular multilevel rectifier of digital control system.