Thesis (MScEng)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: This thesis presents the design and implementation of a voltage controller for an
Uninterruptible Power Supply (UPS) Inverter. The inverter is capable of producing a
nearly sinusoidal output voltage waveform, thereby keeping the Total Harmonic
Distortion (THD) to a minimum.
Digital controllers introduce a time delay in the control law that causes system
instability. Various control techniques, which includes Pade approximations and
system augmentation, are investigated to eliminate the effect of the time delay. These
controllers employ classical control as well as modem control techniques. The
selection of the various control parameters is verified by mathematical equations. A
load-disturbance compensation scheme, implementing feed-forward and gain
scheduling, is also developed to improve voltage distortion when varying loads, such
as non-linear loads, are connected to the system. It is shown that the constructed
pulse-width modulated (PWM) control scheme can achieve fast dynamic response as
well as a low THD. / AFRIKAANSE OPSOMMING: Hierdie verhandeling ondersoek die ontwerp en implementering van 'n spanningsbeheerder
vir 'n ononderbroke kragtoevoer omsetter. Die stelsel produseer 'n uittree
spannigsgolfvorm met 'n lae Totale Harmoniese Distorisie (THD).
Digital beheerders veroorsaak 'n tydvertraging in die beheerwet wat stelsel
onstabiliteit kan veroorsaak. Verskeie beheertegnieke wat gebaseer is op die Pade
benaderings van die tydvertraging en stelsel aanpassings, is ondersoek. Hierdie
beheerders maak gebruik van klassieke en moderne beheertegnieke. Die seleksie van
die verskeie beheerderveranderlikes word gestaaf deur wiskundige vergelykings.
Spannigsvervorming word tot 'n minimum beperk deur gebruik te maak van 'n
lasveranderings-kompensasietegniek wat onderskeidelik vorentoe-voer en aanwins
skedulering implementeer. Verder word daar bewys dat die pulswydte modulasie
(PWM) beheerskema vinnige dinamiese gedrag asook 'n lae THD bewerkstellig.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/52810 |
| Date | 12 1900 |
| Creators | Uys, Jacobus Johannes |
| Contributors | Beukes, H. J., Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 156 p. : ill. |
| Rights | Stellenbosch University |
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