Control and Automation Exam for Bachelor of Engineering in Electrical Engineering, Exams of Control Systems

Download Control and Automation Exam for Bachelor of Engineering in Electrical Engineering and more Exams Control Systems in PDF only on Docsity! 1 Cork Institute of Technology Bachelor of Engineering in Electrical Engineering – Award (National Diploma in Engineering in Electrical Engineering – Award) (NFQ – Level 7) Summer 2005 Control & Automation (Time: 3 Hours) INSTRUCTIONS: Answer Five Questions, at least Two from each section. All formula and calculations must be shown. The use of electronic calculators is permitted. Examiners: Mr. K. O Connell Mr. M. Ahern Mr. R. Daly Mr. P. O Murchú Section A (Control) Please use answer book A! Q1 (a) Give an example a system, either electrical, mechanical or otherwise which can be classified as a second order system, and explain why. (5marks) (b) A second order system which is subjected to a unity step input is found to give an exponentially decaying sinusoidal response, with an over shoot of 40% and at a frequency of 2 Hz. The final settling value of the response is unity. Evaluate the system transfer function. (15marks) Q2 A series connected R-L-C circuit consisting of a resistor of 10Ω, an inductor of 2H and a capacitor of 0.02F. This circuit is now connected to a 12 Volt d.c. supply through a single pole switch. Given that the voltage across the capacitor is the circuit output, and that the switch has been closed at t = 0, (a) Show that the system transfer function is given by: T(s) = 25 s2 + 5s+ 25 (8marks) (b) (i) Show the location of the systems poles and zeros on the s-plane. (ii) Evaluate the system natural radiancy, damped radiancy, and damping co-efficient. (6marks) (c) Using Laplace tables, evaluate an expression for the circuit output in the time domain. (6marks) Q3 A Proportional + Integral (PI) Controller is shown in Fig.1 below. 2 Obtain expressions for K p and Ki in terms of the other plant constants, including ζ and ω. (20marks) Q4 Explain clearly, with the aid of appropriate block diagrams, the meaning of the following terms as applied to control systems (a) System disturbance; (4marks) (b) Feed-forward control; (4marks) (c) Ratio control; (5marks) (d) Cascade control. (7marks) )1( s K K ip + 1+S A τ β INPUT OUTPUT SENSOR CONTROLLER PLANT + - Fig.1