Study Of One-cycle Control Cascade Multilevel Converter

In recent years, multilevel converter achieves wide application in high-powerconversion areas for its low switching frequency, low harmonic level and its high qualityoutput waveform. But, with the continuous development of solar energy, wind energy, fuelcells and other new energy power generation, it has put forward higher requirements onthe performance of the converter control. Traditional constant power source is substitutedfor the DC supply with fluctuation, and because of all sorts of complex factors make itmixed with noise interference. When using such DC supply as the input power of themultilevel converter, the conventional modulation strategies have been unable to meet theneeds of the application. According to the characteristics above, in this paper, we proposeda One-cycle control scheme for the application of the cascade multilevel converter.The scheme combines traditional carrier phase-shifted SPWM modulation strategywith One-cycle control and make it owes both of the advantages. In this paper, theOne-cycle control cascade multilevel converter is researched and simulated, and its workproperties in different applications were studied. The results show that, the proposedscheme has good control effect for the cascade multilevel converter. It has goodperformance to resist the DC side voltage fluctuation, and it can also effectively avoid theDC side counter current existing in the traditional modulation when applied to HybridCascade Multilevel Converter. The scheme has generality in modulation when differentcells work in different voltage ratio. Therefore, One-cycle control cascade multilevelconverter shows good working performance in different applications, and has been provedto be a method of great reference value for research and application.Finally, the prototype of a cascade multilevel converter of two H-bridge cells areaccomplished, and the experimental results verify the feasibility and effectiveness of thismethod.