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published_or_final_version / Electrical Engineering / Master / Master of Philosophy

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Thesis (M.S.)--Ohio University, November, 1993. / Title from PDF t.p.

M.Ing. (Electrical & Electronic Engineering) / Three single phase current fed converters operating in pwm mode, are combined as an active power filter of 15 kVA. The undesired limit cycle shown by the system is eliminated by feedback loop compensation. Analog, computer and analytical models which predict remarkably similar system responses are used to investigate the technique. The analytical model involves describing function methods. The losses in the converters are modelled, and used as a feedback reference to allow losses in the system to be accurately covered from the supply. The system behaves as an accurate, fast active filter for distortion in power networks. Results illustrating this include the time and frequency response of the system for different reference currents. This is shown for the computer simulation as well as the practical system. Some more results include the response of the system to both a balanced and an unbalanced set of references in the three phases. The last results shown, illustrate the ability of the system to compensate a non-linear load.

M.Ing. (Electrical & Electronic Engineering) / Please refer to full text to view abstract

M.Ing. (Electrical and Electronic) / Please refer to full text to view abstract

Pulse Width Modulation (PWM) has been used extensively for motor control, DC-AC converters, DC-DC converters and in audio applications. The conventional method of generating a pulse width modulated signal involves generating an accurate sawtooth or triangle wave using analog circuits. In CMOS, being analog circuit intensive puts extra constraints on the fabrication process used for manufacture, thus requiring a higher cost than digital CMOS. Delta-Sigma Modulation on the other hand is analog intensive, but requires only quality capacitor matching, which can be obtained with current digital CMOS processes. This thesis describes a method to generate a digital PWM with pulse dithering using a Delta-Sigma modulator. The Delta-Sigma modulator provides accuracy and allows the circuit to be implemented in a digital CMOS process, while the pulse dithering in the PWM spreads out harmonic noise generated from the PWM fundamental frequency. / Graduation date: 1998

E.R. Kretzmer. / "Reprinted from the Proceedings of the Institute of Radio Engineers ; v.35, no.11" / Includes bibliographical references. / Army Signal Corps Contract No. W-36-039 sc-32037.

Thesis (M.S.)--University of Florida, 2005. / Title from title page of source document. Document formatted into pages; contains 74 pages. Includes vita. Includes bibliographical references.