On-line Estimation of Fundamental and Ripple Components of Line Currents in a Voltage-Source Inverter Operated at Low Switching Frequency

Tripathi, Avanish and G, Narayanan (2014) On-line Estimation of Fundamental and Ripple Components of Line Currents in a Voltage-Source Inverter Operated at Low Switching Frequency. In: Sixth National Power Electronics Conference-2013, December 20-22, 2013, Indian Institute of Technology, Kanpur.

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Abstract

High-power voltage-source inverters (VSI) are often switched at low frequencies due to switching loss constraints. Numerous low-switching-frequency PWM techniques have been reported, which are quite successful in reducing the total harmonic distortion under open-loop conditions at such low operating frequencies. However, the line current still contains low-frequency components (though of reduced amplitudes), which are fed back to the current loop controller during closed-loop operation. Since the harmonic frequencies are quite low and are not much higher than the bandwidth of the current loop, these are amplified by the current controller, causing oscillations and instability. Hence, only the fundamental current should be fed back. Filtering out these harmonics from the measured current (before feeding back) leads to phase shift and attenuation of the fundamental component, while not eliminating the harmonics totally. This paper proposes a method for on-line extraction of the fundamental current in induction motor drives, modulated with low-switching-frequency PWM. The proposed method is validated through simulations on MATLAB/Simulink. Further, the proposed algorithm is implemented on Cyclone FPGA based controller board. Experimental results are presented for an R-L load.

Item Type:	Conference Paper
Additional Information:	Copyright for this article belongs to the NPEC
Keywords:	Fundamental current extraction, harmonic current estimation, harmonic model of induction motor, low switching frequency PWM, pulse width modulation
Department/Centre:	Division of Electrical Sciences > Electrical Engineering
Date Deposited:	08 Nov 2014 05:39
Last Modified:	08 Nov 2014 05:39
URI:	http://eprints.iisc.ac.in/id/eprint/50245

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