Ch. 9 Design Of Compensaters

Front 1

1. Briefly distinguish between the design techniques in Chapter 8 and Chapter 9.

Back 1

1. Chapter 8: Design via gain adjustment. Chapter 9: Design via cascaded or feedback filters

Front 2

2. Name two major advantages of the design techniques of Chapter 9 over the design techniques of Chapter 8.

Back 2

2. A. Permits design for transient responses not on original root locus and unattainable through simple gainadjustments. B. Transient response and steady-state error specifications can be met separately and independently without the need for tradeoffs

Front 3

3. What kind of compensation improves the steady-state error?

Back 3

3. PI or lag compensation

Front 4

4. What kind of compensation improves transient response?

Back 4

4. PD or lead compensation

Front 5

5. What kind of compensation improves both steady-state error and transient response?

Back 5

5. PID or lag-lead compensation

Front 6

6. Cascade compensation to improve the steady-state error is based upon what pole- zero placement of the compensator? Also, state the reasons for this placement.

Back 6

6. A pole is placed on or near the origin to increase or nearly increase the system type, and the zero is placed near the pole in order not to change the transient response.

Front 7

7. Cascade compensation to improve the transient response is based upon what pole- zero placement of the compensator? Also, state the reasons for this placement.

Back 7

7. The zero is placed closer to the imaginary axis than the pole. The total contribution of the pole and zero along with the previous poles and zeros must yield 1800 at the design point. Placing the zero closer to the imaginary axis tends to speed up a slow response.

Front 8

8. What difference on the s-plane is noted between using a PD controller or using a lead network to improve the transient response?

Back 8

8. A PD controller yields a single zero, while a lead network yields a zero and a pole. The zero is closer to
the imaginary axis.

Front 9

9. In order to speed up a system without changing the percent overshoot, where must the compensated system's poles on the s-plane be located in comparison to the uncompensated system's poles?

Back 9

. Further out along the same radial line drawn from the origin to the uncompensated poles

Front 10

10. Why is there more improvement in steady-state error if a PI controller is used instead of a lag network?

Back 10

10. The PI controller places a pole right at the origin, thus increasing the system type and driving the error
to zero. A lag network places the pole only close to the origin yielding improvement but no zero error.

Front 11

11. When compensating for steady-state error, what effect is sometimes noted in the transient response?

Back 11

11. The transient response is approximately the same as the uncompensated system, except after the original settling time has passed. A slow movement toward the new final value is noticed.

Front 12

12. A lag compensator with the zero 25 times as far from the imaginary axis as the compensator pole will yield approximately how much improvement in steady-state error?

Back 12

12. 25 times; the improvement equals the ratio of the zero location to the pole location.

Front 13

13. If the zero of a feedback compensator is at and a closed-loop system pole is at , can you say there will be pole-zero cancellation? Why?

Back 13

13. No; the feedback compensator's zero is not a zero of the closed-loop system.

Front 14

14. Name two advantages of feedback compensation.

Back 14

14. A. Response of inner loops can be separately designed; B. Faster responses possible; C. Amplification may not be necessary since signal goes from high amplitude to low.