An analysis of delta PWM inverter

Choudhury, Mohammad Ali (1984) An analysis of delta PWM inverter. 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 (7MB) [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

At present, various modulation techniques are in use for PWM inverters in AC motor drives. This thesis is devoted to the analysis and implementation of a newly proposed modulation technique for inverter operation. The technique known as delta modulation has been used previously in voice transmission. In inverter applications, analog implementation of DM has several distinct advantages over other modulation techniques. These are easy implementation, inherent V/f ratio control, low order harmonic attenuation and easy harmonic and commutation controls. -- In this thesis, the delta modulation technique as the applied for inverter switching waveforms generation is analyzed. A Fourier analysis of the delta modulated inverter output has been carried out in order to study the harmonic behaviour of the inverter output. The analytical results confirms the advantageous features of the delta modulation technique. Practical implementation of the modulation process for inverter operations was realized and the results obtained in analytical studies were verified for a single phase bridge inverter. -- Loading characteristics of a single phase delta modulated inverter were studied under different types of passive and dynamic loads. The passive loads were resistive and R-L loads. The dynamic loads were single phase induction motors. Theoretical results are verified experimentally for loading characteristics. -- A modulation and a logic circuit were designed and implemented for a three phase inverter switching. The implementation involved the design and construction of a three phase sine reference wave generator, a three phase modulation circuit and the logic circuits for generation of proper switching waveforms of the three phase inverter switches. -- A comparison has been made in the study between the proposed delta modulation technique and conventionally used sine PWM technique. Several suggestions have been put forward for the further study.

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