Evaluation of the low-frequency neutral-point voltage oscillations in the three-level inverter
Pou, J.; Pindado, R.; Boroyevich, D.; Rodriguez, P.
Industrial Electronics, IEEE Transactions on
Volume 52, Issue 6, Dec. 2005 Page(s): 1582 - 1588
Digital Object Identifier 10.1109/TIE.2005.858723
Summary: The nearest vectors to the reference vector are commonly used in space-vector modulation (SVM) strategies. The main advantages of these modulation strategies are the low switching frequencies of the devices, the good output voltage spectra, and the low electromagnetic interference. However, when these techniques are applied to the three-level neutral-point (NP)-clamped inverter, low-frequency oscillations appear in the NP voltage for some operating conditions. As a result, the value of the dc-link capacitors must be increased in order to attenuate such oscillations. In this paper, these amplitudes are quantified for two modulation strategies that use nearest vectors to the reference vector. Owing to the nondimensional variables used in the analysis, the information provided will help for the calculation of the dc-link capacitors in a given specific application. Simulated and experimental examples are presented.
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