| High-power switching devices are being more and more widely used in the field of high voltage power conversion. However, switching frequency of power switching devices is often limited in order to meet the needs of high power. This problem can be solved by utilizing voltage synthesizers of small voltage levels and small power. Multilevel converter is the best choice to realize the idea. The multilevel converter controls switching devices and synthesizes a desired voltage output from several levels of voltages as inputs, whose amplitude is much higher than the voltage borne by a single switching device.This paper summarized the trends of multilevel converter by analyzing topologies and the basic operating principles of several common used multilevel converters. These lead to the focus of this paper-Modular Multilevel Converter (MMC). The topology, operating principles and controlling strategies of MMC was analyzed in detail. The simulations of three-phase three-level MMC were implemented in MATLAB by using carrier phase-shifting SPWM control strategy.The requirements of hardware and software of MMC control systems were summed up by analyzing its operating principles. Reference to models of other types multilevel converters, the MMC control system based on DSP+FPGA was established, and a three-phase MMC prototype was designed and constructed. Experimental analysis of MMC working as inverter and rectifier verified operating principles and MMC control system.The MMC control system developed in this subject can start the topology and correctly export voltage and current by using CPS-SPWM control strategy. More in-depth research based on it could surely push more promotion and application of MMC.
|
PDF Full Text Request