Rockwell-automation MD65 User Manual Version 2.0 Manual de usuario descargar pdf (Pagina 175)

PID Set Up

I-7

PID Gains

The proportional, integral, and differential gains make up the PID

regulator.

• PID Prop Gain (A134)

The proportional gain (unitless) affects how the regulator reacts

to the magnitude of the error. The proportional component of

the PID regulator outputs a speed command proportional to the

PID error. For example, a proportional gain of 1 would output

100% of max frequency when the PID error is 100% of the

analog input range. A larger value for PID Prop Gain (A134)

makes the proportional component more responsive, and a

smaller value makes it less responsive. Setting PID Prop Gain

(A134) to 0.00 disables the proportional component of the PID

loop.

• PID Integ Time (A135)

The integral gain (units of seconds) affects how the regulator

reacts to error over time and is used to get rid of steady state

error. For example, with an integral gain of 2 seconds, the

output of the integral gain component would integrate up to

100% of max frequency when the PID error is 100% for 2

seconds. A larger value for PID Integ Time (A135) makes the

integral component less responsive, and a smaller value

makes it more responsive. Setting PID Integ Time (A135) to 0

disables the integral component of the PID loop.

• PID Diff Rate (A136)

The Differential gain (units of 1/seconds) affects the rate of

change of the PID output. The differential gain is multiplied by

the difference between the previous error and current error.

Thus, with a large error the D has a large effect and with a

small error the D has less of an effect. This parameter is scaled

so that when it is set to 1.00, the process response is 0.1% of

Maximum Freq (P035) when the process error is changing at

1% / second. A larger value for PID Diff Rate (A136) makes the

differential term have more of an effect and a small value

makes it have less of an effect. In many applications, the D

gain is not needed. Setting PID Diff Rate (A136) to 0.00

(factory default) disables the differential component of the PID

loop.

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Rockwell-automation MD65 User Manual Version 2.0 Manual de usuario Pagina 175