Abstract:Each half-bridge sub-module of a modular multilevel converter (MMC) consists of two switch groups (1 IGBT and 1 anti-parallel diode).In the case of the large scale of the submodules included in the MMC, the simulation solution of the submodules divided by the circuit model segmentation method will still occupy more resources and the efficiency is not high. A simulation verification method of MMC submodule based on numerical model is proposed.Firstly, by analyzing the working principle of MMC and the working mechanism of HBSM, two switching groups in the half-bridge sub-module are equivalent to the constant switching resistance in high and low resistance states, and the equivalent circuit is given. Then，in order to discretize the capacitor branch，numerical solution formula of the half-bridge sub-module of MMC is deduced based on the trapezoidal rule and the numerical calculation circuit model is given. Finally, the simulation in the MATLAB which includes two types of sub-module model，the simulation waveforms of the two models are compared and analyzed. The simulation results prove that the numerical calculation model sub-module is feasible.