Control System (INDSC6C) — DU B.Sc. (Hons) Instrumentation Previous Year Question Papers

Q.2 (a) Reduce the system in figure-2 to a single block representation. (6) (b) Using Routh -Hurwitz criterion determine the relation between K and T so that (6 unity feedback control system whose open-loop transfer function given below is stable (c) The block diagram representation of a control system is given in figure-3; (6) Draw the signal flow graph to determine the overall transfer function Q.3 (a) Derive and plot the expressions for the output response c(t) for a first order (6) control system when subjected to the following inputs; )Unit step function ii)Unit ramp function (b) Define the peak time (tp), rise time (t.), maximum overshoot (M.) and settling (4) time (t.) along with their respective expressions. Also, mark these parameters in the output response of a second order control system when subjected to unit step input. (c) The block diagram of a unity feedback control system is shown in figure-4; (8) Determine the characteristic equation of the system, 0g.S, @a,p, Mp, the time a which the first undershoot occurs, the time period of oscillations and the numbe of cycles completed before reaching the steady state. (a) Using Nyquist criterion investigate the closed loop stability of the system whose (8) open-loop transfer function is given below for K=1.25. Also, determine the limiting value of K for stability. (b) Determine the value of gain K for the open loop transfer function given below so (6) that i) the gain margin is 15dB and il) the phase margin is 60°. (c) Explain force-voltage analogy using RLC circuit (4) Q.5 (a) Define state variables, state and state vector. (6) (b) Obtain the state space equations for the transfer function given as; (6) (c) For the electrical network shown in figure-5, determine the state model (6) Consider 4g, Iz and v, as state variables. The output variables are iy and iz. Q.6 (a) Differentiate between derivative control and derivative feedback control. (4) The overall transfer function of a control system is given by; (8) The desired damping ratio is 0.8. Determine the derivative rate feedback constant Ki and compare the rise time (tr),peak time (tp), maximum overshoot (Mp) and steady state error for unit ramp input without and with derivative feedback control. (C) Sketch the polar plot of G(s) = 10 (6) Draw the electrical equivalent circuit of lag compensation and obtain its transfer (6) function. Draw the pole-zero plot for the response also. (b) For the system represented by the given equations, find the transfer function (6) 5/x, with the help of signal flow graph technique. Where xy is input variable and X5 is output variable. The forward path transfer function of a unity feedback control system is given (6) Obtain an expression for unit step response of the system.