High Country Tek ProValve 200 Series - Manual (Page 13)

021-PV200 Rev A PV200 Uses Manual 13
Copyright © High Country Tek, Inc. – 2013
PV200
Closed Loop Proportional Valve Controller
PID Control
The PV200 utilizes a PID control loop algorithm. PID control uses process feedback to correct for error. The error
correction factors are proportional, integral, and derivative.
In the PV200, the error is the difference between the target and actual position inputs. This error is fed into the PID
loop which results in a signal to drive one of the two solenoid outputs. The output causes a change in position and
therefore reduces the error.
The proportional gain produces an output proportional to the error. If there is a large error, the output will be high. If
there is a small error, the output will be low. In many systems, only proportional error correction is needed.
The integral time produces an output relative to the accumulation of error over time. The integral time can provide a
damping effect which minimizes overshoot. It can also adjust for small offsets. The integral time in the PV200
represents how often the error is added to the integral sum. The lower the time value the faster the integral will
accumulate and therefore, the more effect it will have on the output. The PV200 also incorporates anti-windup
control which prevents integral accumulation when output is at the maximum level.
The derivative gain produces an output proportional to the rate of change of the error. A rapid change in the error
produces a large derivative value while constant error produces no derivative. The derivative gain can be used to
provide fast response to sudden changes in the target set-point.