Harmonic analysis of DC capacitor current in sinusoidal and space-vector modulated neutral-point-clamped inverters

Gopalakrishnan, KS and Narayanan, G (2015) Harmonic analysis of DC capacitor current in sinusoidal and space-vector modulated neutral-point-clamped inverters. In: SADHANA-ACADEMY PROCEEDINGS IN ENGINEERING SCIENCES, 40 (5). pp. 1501-1529.

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Abstract

The voltage ripple and power loss in the DC-capacitor of a voltage source inverter depend on the harmonic currents flowing through the capacitor. This paper presents a double Fourier series based analysis of the harmonic contents of the DC capacitor current in a three-level neutral-point clamped (NPC) inverter, modulated with sine-triangle pulse-width modulation (SPWM) or conventional space vector pulse-width modulation (CSVPWM) schemes. The analytical results are validated experimentally on a 3-kVA three-level inverter prototype. The capacitor current in an NPC inverter has a periodicity of 120(a similar to) at the fundamental or modulation frequency. Hence, this current contains third-harmonic and triplen-frequency components, apart from switching frequency components. The harmonic components vary with modulation index and power factor for both PWM schemes. The third harmonic current decreases with increase in modulation index and also decreases with increase in power factor in case of both PWM methods. In general, the third harmonic content is higher with SPWM than with CSVPWM at a given operating condition. Also, power loss and voltage ripple in the DC capacitor are estimated for both the schemes using the current harmonic spectrum and equivalent series resistance (ESR) of the capacitor.

Item Type:	Journal Article
Publication:	SADHANA-ACADEMY PROCEEDINGS IN ENGINEERING SCIENCES
Publisher:	INDIAN ACAD SCIENCES
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
Keywords:	Capacitor current; capacitor loss; conventional space vector pulse width modulation; diode-clamped inverter; double Fourier series; harmonic analysis; neutral-point-clamped inverter; sine-triangle pulse width modulation; three-level inverter
Department/Centre:	Division of Electrical Sciences > Electrical Engineering
Date Deposited:	19 Nov 2015 04:56
Last Modified:	19 Nov 2015 04:56
URI:	http://eprints.iisc.ac.in/id/eprint/52781

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