BEE Control System Principles 2

Question 1

Which of the following best describes the steady-state error of a Type 1 system subjected to a ramp input?

Accepted Answer

A finite constant

Answer

A Type 1 system has one integrator, which eliminates steady-state error for step inputs but produces a finite constant error for ramp inputs.

Question 2

In a second-order control system, if the poles are located at -3 ± j4, what is the damping ratio?

Accepted Answer

0.6

Answer

The poles are at σ ± jω_d where σ = 3 and ω_d = 4, giving ω_n = 5 and ζ = σ/ω_n = 3/5 = 0.6.

Question 3

What is the primary function of a lead compensator in a control system?

Accepted Answer

Improve transient response and increase phase margin

Answer

A lead compensator adds positive phase at crossover frequency, increasing phase margin and improving transient response speed.

Question 4

For a unity feedback system with open-loop transfer function G(s) = K/[s(s+2)(s+5)], what happens to closed-loop stability as K increases beyond a critical value?

Accepted Answer

System becomes unstable

Answer

As K increases, root locus poles migrate into the right-half plane, causing instability; the Routh criterion confirms a finite gain margin.

Question 5

Which parameter is directly read from the Bode magnitude plot at the gain crossover frequency?

Accepted Answer

The magnitude is 0 dB by definition

Answer

The gain crossover frequency is defined as the frequency where the open-loop magnitude equals 0 dB (unity gain).

BEE - Bachelor of Electrical Engineering Practice Test

BEE - Bachelor of Electrical Engineering Practice Test

BEE Control System Principles 2