Title: Ramp based constant frequency current control for DSTATCOM

Authors: S. Srikanthan, Mahesh K. Mishra

Addresses: Department of Electrical Engineering, Indian Institute of Technology Madras, Chennai-600036, India. ' Department of Electrical Engineering, Indian Institute of Technology Madras, Chennai-600036, India

Abstract: The conventional hysteresis current controller is simple to implement, has inherent peak current-limiting capability, fast dynamic response etc. However, it suffers from the demerit of variable switching frequency, which may be prohibitively high, increasing the stress levels on the switches. Although a ramp controller may be used to achieve a constant switching frequency, the selection of frequency of the triangular carrier waveform plays a crucial role in maintaining the frequency of operation same as that of the carrier. If an appropriate frequency of the carrier is not chosen, the actual current may encounter undesirable effects of over-crossing and under-crossing. This paper proposes an analytical method for proper selection of the carrier so that the above-said effects are eliminated. The method is also extended to a ramp controller with hysteresis to achieve a reduced value of the constant switching frequency. Detailed simulation has been carried out through MATLAB and an experimental prototype is also built to validate the proposed method.

Keywords: carrier frequency; distribution static compensator; DSTATCOM; hysteresis band current control; ramp controller; instantaneous symmetrical component theory; frequency selection; triangular carrier waveform; simulation.

DOI: 10.1504/IJPELEC.2009.023621

International Journal of Power Electronics, 2009 Vol.1 No.3, pp.249 - 266

Received: 30 May 2008
Accepted: 06 Sep 2008

Published online: 03 Mar 2009 *

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