BEE BEE Bachelor of Electrical Engineering Control Systems Theory Questions and Answers 2

Question 1

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

Accepted Answer

Increase phase margin and improve transient response

Answer

Reduce steady-state error only

Answer

Eliminate all overshoot

Answer

Decrease the system bandwidth

Question 2

In a Nyquist plot, what does an encirclement of the point (-1, 0) indicate?

Accepted Answer

The closed-loop system may be unstable

Answer

The system has zero steady-state error

Answer

The gain margin is infinite

Answer

The system is always overdamped

Question 3

Which matrix equation represents the state-space model of a linear time-invariant system?

Accepted Answer

ẋ = Ax + Bu, y = Cx + Du

Answer

ẋ = Ax² + Bu, y = Cx + Du

Answer

ẋ = A + Bx, y = C + Dx

Answer

ẋ = ABx + u, y = CDx + u

Question 4

What does a system's gain margin represent?

Accepted Answer

The factor by which gain can increase before the system becomes unstable

Answer

The maximum output amplitude at resonance

Answer

The DC gain of the closed-loop transfer function

Answer

The ratio of output to input at the natural frequency

Question 5

A second-order underdamped system has a damping ratio of 0.5. What is the approximate percent overshoot of its step response?

Accepted Answer

16.3%

Answer

5.0%

Answer

25.4%

Answer

0%

Question 6

What is the transfer function of a PID controller?

Accepted Answer

Kp + Ki/s + Kd·s

Answer

Kp · Ki · Kd · s

Answer

Kp / (1 + Ki·s + Kd·s²)

Answer

Ki·s + Kd/s + Kp·s²