A Modular Multilevel Converter with Integrated Self-balancing Series IGBTs

A capacitor voltage self‐balancing method of modular multilevel converters based on switching state matrix construction

“…These methods generally need high switching frequency, whereas the efforts of reducing switching frequency will significantly increase the complexity of the control algorithm, so it is difficult to achieve voltage balance when the number of submodules is large. Thus, these strategies are mainly used in the field of medium‐ and low‐voltage classes with a small number of submodules. The third category adds auxiliary hardware circuits such as clamping diodes to the system or uses novel MMC topologies [33–47], which will avoid the sampling of bridge arm currents or submodule capacitor voltages, whereas additional clamping components or energy transfer paths are required. There are also other topologies designed for lower energy storage and DC‐fault tolerance that require closed‐loop control [48–51].…”

“…3. The third category adds auxiliary hardware circuits such as clamping diodes to the system or uses novel MMC topologies [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47], which will avoid the sampling of bridge arm currents or submodule capacitor voltages, whereas additional clamping components or energy transfer paths are required. There are also other topologies designed for lower energy storage and DC-fault tolerance that require closedloop control [48][49][50][51].…”