Real-time Simulation Realization of Modular Multilevel Converter Based on FPGA

FPGA can be used to implement nanosecond step size simulation of Modular Multilevel Converter (MMC). However, the design of the solver limits its application in simulation realization. This paper presents an equivalent model simulation realization. Backward Euler method is used to discretize the bridge arm inductance and the sub-module capacitance. Thevenin's theorem is used to get the bridge arm equivalent circuit. The method take both the calculation accuracy and the simulation rate of the model into account and the design difficulty of the model solver is reduced. Model solution with the 100ns-step simulation is implemented in the FPGA. Comparing and analyzing the results between primary simulation and hybrid simulation of equivalent model from the effects and errors, two simulation waveforms are highly compatible and the paradigm error is within 0.5%. Moreover, FPGA-based Hardware-in-the-loop can simulate the complete operation process of the MMC switch, which confirms the effectiveness of the method.