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Analytical evaluation of DC capacitor RMS current and voltage ripple in neutral-point clamped inverters

Gopalakrishnan, K S and Janakiraman, Santosh and Das, Soumitra and Narayanan, G (2017) Analytical evaluation of DC capacitor RMS current and voltage ripple in neutral-point clamped inverters. In: SADHANA-ACADEMY PROCEEDINGS IN ENGINEERING SCIENCES, 42 (6). pp. 827-839.

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Official URL: http://dx.doi.org/10.1007/s12046-017-0668-y


The sizing of the DC-link capacitor in a three-level inverter is based on the RMS current flowing through it. This paper analyses the DC-link capacitor RMS current in a neutral-point clamped (NPC) inverter and expresses the same as a function of modulation index, line-side current amplitude and power factor. Analytical closed-form expressions are derived for the capacitor RMS current for single-phase half-bridge, single-phase full-bridge and three-phase three-leg topologies of a three-level inverter. The worst-case capacitor current stress is determined for each topology based on the analytical expressions. Further, analytical expressions are derived for the RMS values of low-frequency and high-frequency capacitor currents. These expressions are then used to estimate voltage ripple across the DC capacitor for sinusoidally modulated three-phase NPC inverter. The analytical expressions for the RMS current and voltage ripple are validated experimentally over a wide range of operating points.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the INDIAN ACAD SCIENCES, C V RAMAN AVENUE, SADASHIVANAGAR, P B #8005, BANGALORE 560 080, INDIA
Department/Centre: Division of Electrical Sciences > Electrical Engineering
Date Deposited: 22 Jul 2017 05:43
Last Modified: 22 Jul 2017 05:43
URI: http://eprints.iisc.ac.in/id/eprint/57463

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