The modulation and simulation of voltage source converter based on Half Bridge Sub Module

Modular Multilevel Converter (MMC) can greatly reduce the switching frequency and consequently lower the converter losses. By increasing the number of Half Bridge Sub Modules (HBSMs) per arm, the filter can be eliminated, scalability to higher voltages can be easily achieved and reliability can be improved. But in the study of high-voltage MMC, the large number of HBSMs makes simulation speed very slow. It will be even worse when multi-terminal HVDC and DC Grid are studied. In order to solve these problems, studies have been done on the topology and the mathematical model of HBSM and HBSM Group in this paper, and the equivalent circuit and the mathematical model are acquired. On this basis, different simulation models are established, and the processes of charging, steady state and DC fault are studied. The comparison of the simulation results show that the equivalent circuit and its mathematical model is accuracy, and the simulation time is also reduced significantly.