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UBC Theses and Dissertations

Optimum response contactor servomechanism Butt, Chak Ying


This thesis deals with the design of simple circuits to realize the optimum second order contactor type servo. The analysis is based on the generation of a switching function so that torque reversal will occur at the point where the generated function g(t) intersects the error function e(t). The conventional treatment differs from the above method in that the required switching boundary relationship, f(ė), between e and e^° is obtained so that voltage proportional to e-f(e^°) is used as the switching signal. Using a d-c shunt motor or an induction motor, analysis and design of optimum systems based on the generated function treatment had been carried out taking into account the actual motor characteristics and relay time delay. An optimum relay servo for a 1/50 h.p. Ford induction motor was constructed on this principle and tested. The simplicity of the circuits involved makes this design highly practical. The optimization of a second order contactor servo can also be accomplished by approximating the optimum switching boundary with a simple lead network. A servo system using the same 1/50 h.p. induction motor was built according to this method. This approach results in a simpler circuit than the former; however, it has a larger dead zone and is only applicable with an a-c servo motor. A brief discussion of the possiblity of employing the generated function technique to the analysis of a 3rd order system was also made.

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