Submodule Capacitance Monitoring Strategy for Phase-Shifted Carrier Pulsewidth-Modulation-Based Modular Multilevel Converters

Capacitance monitoring is one of the important issues for a modular multilevel converter (MMC) to obtain high reliability. Since pulsewidth modulation usually implemented in field-programmable gate array (FPGA), produced precise switching states FPGA cannot be directly accessed by top digital signal processor (DSP) controller, which poses challenges existing capacitance methods based on MMC. This article presents submodule (SM) strategy MMC with simple algorithm, where fundamental frequency components SM capacitor voltage and current are extracted estimate reference, but not states. The proposed scheme only simplifies implementation calculation, also avoids control limitations heavy communication burden between DSP FPGA. Besides, effectively eliminates noise impact from sensors increases accuracy. Simulation experimental studies implemented, results confirm effectiveness strategy.