A Junction Temperature Balance Control Among Sub-Modules for Modular Multilevel Converter

There are many sub-modules(SMs) in the modular multilevel converter(MMC), and the voltage balance among the SMs is a prerequisite for the normal operation of the converter. Thus, in order to maintain the balance of the capacitor voltage of the SMs, a general sorting algorithm based on the capacitor voltage of the SMs is adopted. However, due to the mismatch of the parameters among the SMs, there is a deviation in the consistency of the junction temperature among them in fact. Once a general sequencing method is adopted, the reliable operation of the equipment is seriously threatened. For this reason, the mechanism of the thermal balance control method is revealed. Moreover, a new control strategy of the capacitance embedded in the voltage sorting (CEVS) is proposed considering the difficulty of collecting the junction temperature of the device. Finally, the feasibility of the proposed control strategy is verified through thermoelectric co-simulation.