08-05-2012, 04:49 PM
DESIGN OF LAG AND LEAD COMPENSATOR
[attachment=21602]
APPARATUS REQUIRED
1. Transfer function and compensator
2. Computer interface chord
3. Patch chords
THEORY
LAG COMPENSATOR
A compensator having the characteristics of a Lag network is called a lag
compensator. If a sinusoidal signal is applied to a lag network, then in steady state the output
will have a phase lag with respect to input.
Lag compensation results in a large improvement in steady state performance but
results in slower response due to reduced bandwidth. The attenuation due to the lag compensator
will shift the gain cross over frequency to a lower frequency point where the phase margin is
acceptable.
The general form of lag compensator transfer function is given by:
G(S) = (S+T) / (S+P) = (S + 1/T) / S + 1/BT Where, T > 0 and B >1
LEAD COMPENSATOR
A compensator having the characteristics of a Lead network is called a Lead
compensator. If a sinusoidal signal is applied to the lead network, then in steady state the output
will have a phase lead with respect to input.
Lead compensation increases the bandwidth, which improves the speed of
response and also reduces, whereas there is a small change in steady state accuracy. Generally,
Lead compensation is provided to make an unstable system as a stable system.
A Lead compensator is basically a high pass filter so it attenuates high frequency
noise effects. If the pole introduced by the compensator is not cancelled by a zero in the system,
then lead compensation increases the order of the system by one.
The general form of Lead compensator transfer function is given by:
G(S) = (S+T) / (S+P) = (S + 1/T) / S + 1/aT Where, T > 0 and a<1
PROCEDURE
EC2259 Electrical Engineering And Control System Lab Manual
Prepared by G.Panneerselvam, Vel Tech Multi Tech
Type II Order System Performance
Without Lag Compensator
1. Connections are given as per the circuit diagram.
2. Switch on the power supply.
3. Apply step input.
4. Set Pb = 100%
5. Measure the time domain specification of the II order system from the waveform.
With Lag Compensator
1. Connections are given as per the circuit diagram.
2. Switch on the power supply.
3. Apply step input.
4. Set Pb = 100%
5. Measure the time domain specification of the II order system from the waveform.
6. Compare the performance with and without lag compensator.
[attachment=21602]
APPARATUS REQUIRED
1. Transfer function and compensator
2. Computer interface chord
3. Patch chords
THEORY
LAG COMPENSATOR
A compensator having the characteristics of a Lag network is called a lag
compensator. If a sinusoidal signal is applied to a lag network, then in steady state the output
will have a phase lag with respect to input.
Lag compensation results in a large improvement in steady state performance but
results in slower response due to reduced bandwidth. The attenuation due to the lag compensator
will shift the gain cross over frequency to a lower frequency point where the phase margin is
acceptable.
The general form of lag compensator transfer function is given by:
G(S) = (S+T) / (S+P) = (S + 1/T) / S + 1/BT Where, T > 0 and B >1
LEAD COMPENSATOR
A compensator having the characteristics of a Lead network is called a Lead
compensator. If a sinusoidal signal is applied to the lead network, then in steady state the output
will have a phase lead with respect to input.
Lead compensation increases the bandwidth, which improves the speed of
response and also reduces, whereas there is a small change in steady state accuracy. Generally,
Lead compensation is provided to make an unstable system as a stable system.
A Lead compensator is basically a high pass filter so it attenuates high frequency
noise effects. If the pole introduced by the compensator is not cancelled by a zero in the system,
then lead compensation increases the order of the system by one.
The general form of Lead compensator transfer function is given by:
G(S) = (S+T) / (S+P) = (S + 1/T) / S + 1/aT Where, T > 0 and a<1
PROCEDURE
EC2259 Electrical Engineering And Control System Lab Manual
Prepared by G.Panneerselvam, Vel Tech Multi Tech
Type II Order System Performance
Without Lag Compensator
1. Connections are given as per the circuit diagram.
2. Switch on the power supply.
3. Apply step input.
4. Set Pb = 100%
5. Measure the time domain specification of the II order system from the waveform.
With Lag Compensator
1. Connections are given as per the circuit diagram.
2. Switch on the power supply.
3. Apply step input.
4. Set Pb = 100%
5. Measure the time domain specification of the II order system from the waveform.
6. Compare the performance with and without lag compensator.