This paper presents a control strategy for voltage balancing of the capacitors of different sub-modules in single phase five-level modular multilevel cascaded inverter based on carrier phase-shifted sinusoidal pulse width modulation. Since the modules consist of capacitors, whose voltages can vary significantly throughout the operation of the converter, the need for a balancing algorithm is derived. Through the specific algorithm it is being ensured that all the capacitors are kept on the same voltage level and all the power devices are equally stressed. Thus the combination of averaging and balancing control enables the modular multilevel converter to achieve the voltage balancing of the sub-module capacitors. The simulation has been carried out using MATLAB/Simulink and the effectiveness of the voltage-balancing control is confirmed based on simulation results.
Keywords: Modular Multilevel Cascaded Inverter (MMCI), Double star chopper cells (DSCC), Carrier phase-shifted sinusoidal pulse width modulation (CPS- SPWM), Total harmonic distortion (THD), Fast Fourier Transform (FFT)
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