Modular multilevel converter is a new type of topological converter which can replace the traditional voltage source converter.However

with the improvement of application of voltage level

the number of cascades of MMC sub-modules increases greatly and especially the problem of second-harmonic circulation in phase unit is particularly obvious.By analyzing the relationship between inductance voltage of bridge arm and circulation current

the interval adaptive feedback is introduced on the basis of hysteresis control.Effectively balancing the contradiction between circulation current suppression efficiency and switching loss

a dynamic suppression method for adaptive control of MMC circulating current in hysteresis interval is proposed.This method can control flexibly inductance voltage drop of the bridge arm and change the flow direction before the limit is exceededso that it can be controlled within the allowable range without additional hardware devices.Finally

simulink simulation model of multi-level two-end back-to-back interconnected system is used to verify the effectiveness of this method in suppressing the circulation in the arm of MMC bridges.