Control of Modular Multilevel Converter under Unequal Arm Capacitor Values

摘要

This paper presents analysis and control of the modular multilevel converter under unequal arm voltages shared by the capacitors. The effect of deviation between the instantaneous values of two DC-link capacitor voltages on the control algorithm is investigated in this paper. The control algorithm consists of the sorting method with the power decoupling, phase shifted pulse width modulation and measured arm voltages in process. This controller is modified in order for taking the voltage differences shared by the arm capacitors into consideration. The submodule and DC-link capacitors are estimated by using an analytical expression derived. The results of Matlab simulation obtained on the five-level modular multilevel converter are compared to the experimental ones.