Abstract：The study of the circulating harmonic currents and the capacitor voltage fluctuation of the modular multilevel converter (MMC) is a hot topic, so the analytic expressions of the circulating harmonic currents and capacitor voltages in steady state based on an existing equivalent model of the MMC is deduced. During this course, it concluded that the circulating harmonic currents are essentially products of the exciting course of a harmonic voltage upon the dc loop, and the principle of the circulating harmonics produced each other. According the deduced expressions, effects of the system parameters upon the circulating harmonics are analyzed. Finally the simulation study proved the deduced expressions.
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2017, Vol. 18 
