| With the development of power electronics technology, high-power switching devices are being widely used. In the field of high voltage power conversion applications, there is often a contradiction between the power conversion capability and switching frequency of high-power switching devices. As long as there is no essential breakthrough in power switching devices, multilevel converter is undoubtedly the best choice. Based on the analysis of traditional multilevel converters, this thesis carried out a detailed study for the topology and control strategies of modular multilevel converter (MMC).Firstly, the multilevel converter topologies have been reviewed. Then, several modulation techniques for multilevel converter topology such as carrier phase-shifted sinusoidal pulse width modulation, multi-carrier PWM modulation technology were analyzed in comparison.Moreover, the topology together with its operation principles of MMC was analyzed, and then, the equivalent mathematical model for MMC was introduced. Based on this model, the law and realization of CPS-SPWM applying for MMC was proposed and analyzed in detail. Thirdly, the DC capacitor voltage control strategy was also studied in this paper and the method for capacitor pre-charging was also proposed.Based on the theoretical analysis and software simulation, a low power three-level single phase half-bridge MMC prototype was designed and constructed. The experimental results verified the effectiveness of the proposed control strategies. The experimental results also show that the MMC have characteristics of modular, high equivalent switching frequency, small current capacity for high-power switching devices, etc. MMC based on carrier phase-shifting technology is of perfect prospect in the field of high voltage power conversion applications.
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