Analysis and design of Delta PWM static AC to DC converters

Esmail, Ali-Reza (1988) Analysis and design of Delta PWM static AC to DC converters. Masters thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (21MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

In this thesis, the modelling, analysis and implementation of the delta modulation technique as used in controlled ac-to-dc converters are presented. The proposed modulation scheme, fundamentally differs from conventional PWM techniques, by virtue of its self-carrier generating ability. This intrinsic feature provides the added advantages of ease of implementation, continuous converter voltage control and more importantly, a direct control on the line harmonic contents. -- An analytical model is developed, which provides key information on the maximum converter switching frequency, location of dominant harmonics and the PWM switching instances. Optimization of the delta modulator parameters is also carried out by means of parametric variations on a single-phase converter. -- The delta PWM technique is implemented in both a single-phase and three-phase transistor bridge converter. In each case, theoretical harmonic analysis of the converter waveforms are presented based on the discrete Fourier transform approach. The pertinent converter waveforms are described in terms of generalized switching functions and the harmonic components are evaluated using an FFT algorithm. Attention has been given to the design of the power and logic circuity conforming to the delta modulator switching specifications. Theoretical results are substantiated by experimental results conducted on prototype single-phase and three-phase transistor converters. -- Performance of the three-phase delta modulated converter with typical R-L and dynamic motor loads are also considered. The results indicate the enhanced performance of the delta modulated converter yielding improved power-factor, near sinusoidal line currents and minimum filtering requirements.

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