Introduction to Lead/lag compensator
first, what's the difference between a compensator and a controller?
There is no definite boundary, the two are similar. There's no need to tangle with this concept
I've been looking for some ideas on this subject, and there's a very "popular" commentary .
Lutz von Wangenheim· Hochschule BremenHere is a excerpt from "G. Ellis, Control System Design Guide":
"Compensators is specialized filters ... designed to provide a specific gain and phase shift, usually at one frequency. The effects on gain and phase either above or below that frequency is secondary. "
My Opinion:there is no clear threshold between "compensators" and "controllers".
Some authors use one or the other term (or mixed). Am I wrong?
To is more precise:i think, each compensator (P, I, PI, PID) can is regarded as a controller-but not vice versa. The Bang-bang controller certainly is a compensator.Jul,
There are no definite boundaries, and some authors use these two nouns at the same time.
What is phase advance. The yellow sine function in the figure is ahead of 90° to the blue cosine function.
Differential controller S, is the advance phase adjustment 90 degrees
For lag correction, the integral effect is an example. Pole, 1/s, phase lag 90 degrees
The form of compensator is the same.
Ahead or lag depends on the relative size of WP and WZ
for advanced correction, Wz < Wp so the Green Line of the first picture is closer to the origin than the turning point of the Yellow Line, and the addition of the composite turns into a red line.
It is worth noting that the red line at this time than the green and yellow lines in the high frequency of the gain greatly reduced, can effectively suppress high-frequency noise! How cool! Suppresses high-frequency noise!
When 0 points are closer to the origin than the Poles, the Bode
when the 0 point is moved close to the pole, but still maintain 0 points on the right side of the pole, it can be found that the phase ahead of the frequency band is reduced, the gain starts non-zero where the right shift
What if 0 points coincide with the poles?
If you move the 0 point to the left of the pole, the lag is corrected.
Lake Tahoe
