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Abstract and Applied Analysis
Volume 2013 (2013), Article ID 870904, 12 pages
Research Article

Improved Switching Strategy for Selective Harmonic Elimination in DC-AC Signal Generation via Pulse-Width Modulation

1Departament of Applied Mathematics III, Universitat Politècnica de Catalunya (UPC), Avenue Bases de Manresa 61-73, 08242 Manresa, Barcelona, Spain
2Department of Electronic Systems Design and Programming, Universitat Politècnica de Catalunya (UPC), Avenue Bases de Manresa 61-73, 08242 Manresa, Barcelona, Spain
3Department of Engineering, Faculty of Engineering and Science, University of Agder (UiA), Grimstad 4898, Norway

Received 15 June 2013; Accepted 13 August 2013

Academic Editor: Sundarapandian Vaidyanathan

Copyright © 2013 Francisco Palacios-Quiñonero et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We present an advanced design methodology for pulse-width-modulated (PWM) DC-AC signal generation. Using design methods based on the Walsh transform, AC sinusoidal signals can be approximated by suitable PWM signals. For different AC amplitudes, the switching instants of the PWM signals can be efficiently computed by using appropriate systems of explicit linear equations. However, the equation systems provided by conventional implementations of this approach are typically only valid for a restricted interval of AC amplitudes and, in general, a supervised implementation of several equation systems is necessary to cover the full AC amplitude range. Additionally, obtaining suitable equation systems for designs with a large number of switching instants requires solving a complex optimization problem. In defining the constitutive pulses of a PWM signal, a suitable partition of the time interval is used as a reference system. In the new methodology, pulses are chosen to be symmetric with respect to the partition points, and the switching times are specified by means of switching ratios with respect to the endpoint subintervals. This approach leads to particularly simple Walsh series representations, introduces a remarkable computational simplification, and achieves excellent results in reducing the harmonic distortion.