Direct digital control of D.C. machines

 

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dc.contributor.advisor McLaren, S G en_ZA
dc.contributor.author Von Zwiklitz, Aubrey Paul en_ZA
dc.date.accessioned 2016-03-14T07:02:22Z
dc.date.available 2016-03-14T07:02:22Z
dc.date.issued 1972 en_ZA
dc.identifier.citation Von Zwiklitz, A. 1972. Direct digital control of D.C. machines. University of Cape Town. en_ZA
dc.identifier.uri http://hdl.handle.net/11427/17669
dc.description.abstract This thesis set out to improve on previous methods of digital control of a three phase fully controlled thyristor bridge, using phase control of the thyristors, and to use this bridge for the purpose of controlling the speed of a separately excited D. C. machine, under the supervision of a small digital computer. Interfacing equipment for this purpose was designed and built. Various methods of speed detection were considered, and a simple digital tachometer designed and built. This tachometer was able to feed a digital number, related to the speed of the machine, to the computer, and was accurate to better than 1%. A direct digital control system was then implemented. The behaviour of the system was first studied under open loop conditions in order to determine the parameters of the system, and to discover any shortcomings in it. The behaviour of the closed loop system was then studied, using z-transform analysis, at sampling rates of from twice to eight times the natural frequency of the machine. Initially, the computer was used as an integral controller. The behaviour of the mathematical model was compared to that of the actual system, and the correlation found to be very good. The control system was then compensated, using compensation routines based on the z-transform analysis, and the behaviour of various compensated systems studied at sampling rates varying from 0,4 to 1 second. Again, the actual system response was found to correspond closely to the designed behaviour. Finally, a dual-machine control system, on a time sharing basis, was implemented, and a degree of interrelation between the speeds of the two machines introduced. The control algorithms developed were able to provide speed control to better than l% accuracy, with a 5% or less overshoot in the step response, a delay of one sampling period but no overshoot in the ramp response, and satisfactory behaviour under load transient conditions. The time, and memory, utilization was such that such algorithms could be extended to the control of several machines, using the single computer, if sufficient input and output facilities were available. en_ZA
dc.language.iso eng en_ZA
dc.subject.other Electrical Engineering en_ZA
dc.subject.other Electronic Engineering en_ZA
dc.title Direct digital control of D.C. machines en_ZA
dc.type Master Thesis
uct.type.publication Research en_ZA
uct.type.resource Thesis en_ZA
dc.publisher.institution University of Cape Town
dc.publisher.faculty Faculty of Engineering and the Built Environment
dc.publisher.department Department of Electrical Engineering en_ZA
dc.type.qualificationlevel Masters
dc.type.qualificationname MSc (Eng) en_ZA
uct.type.filetype Text
uct.type.filetype Image
dc.identifier.apacitation Von Zwiklitz, A. P. (1972). <i>Direct digital control of D.C. machines</i>. (Thesis). University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Electrical Engineering. Retrieved from http://hdl.handle.net/11427/17669 en_ZA
dc.identifier.chicagocitation Von Zwiklitz, Aubrey Paul. <i>"Direct digital control of D.C. machines."</i> Thesis., University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Electrical Engineering, 1972. http://hdl.handle.net/11427/17669 en_ZA
dc.identifier.vancouvercitation Von Zwiklitz AP. Direct digital control of D.C. machines. [Thesis]. University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Electrical Engineering, 1972 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/17669 en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Von Zwiklitz, Aubrey Paul AB - This thesis set out to improve on previous methods of digital control of a three phase fully controlled thyristor bridge, using phase control of the thyristors, and to use this bridge for the purpose of controlling the speed of a separately excited D. C. machine, under the supervision of a small digital computer. Interfacing equipment for this purpose was designed and built. Various methods of speed detection were considered, and a simple digital tachometer designed and built. This tachometer was able to feed a digital number, related to the speed of the machine, to the computer, and was accurate to better than 1%. A direct digital control system was then implemented. The behaviour of the system was first studied under open loop conditions in order to determine the parameters of the system, and to discover any shortcomings in it. The behaviour of the closed loop system was then studied, using z-transform analysis, at sampling rates of from twice to eight times the natural frequency of the machine. Initially, the computer was used as an integral controller. The behaviour of the mathematical model was compared to that of the actual system, and the correlation found to be very good. The control system was then compensated, using compensation routines based on the z-transform analysis, and the behaviour of various compensated systems studied at sampling rates varying from 0,4 to 1 second. Again, the actual system response was found to correspond closely to the designed behaviour. Finally, a dual-machine control system, on a time sharing basis, was implemented, and a degree of interrelation between the speeds of the two machines introduced. The control algorithms developed were able to provide speed control to better than l% accuracy, with a 5% or less overshoot in the step response, a delay of one sampling period but no overshoot in the ramp response, and satisfactory behaviour under load transient conditions. The time, and memory, utilization was such that such algorithms could be extended to the control of several machines, using the single computer, if sufficient input and output facilities were available. DA - 1972 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1972 T1 - Direct digital control of D.C. machines TI - Direct digital control of D.C. machines UR - http://hdl.handle.net/11427/17669 ER - en_ZA


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