Pid Controller - Mitsubishi Electric FR-A800 Series Beginner's Manual

Sample applications (PID controller)
A.2.3

PID controller

The FR-A800 series have integrated PID controllers, which makes it possible to use these inverters for
applications in the process industry like flow and pressure regulation.
The setpoint value is stored internally in an inverter parameter or input as an external signal via input
terminals 2. The actual value is input as an analog current signal (4-20mA) via input terminals 4.
The inverter automatically adjusts its output frequency (the control variable) in response to the dif-
ference between the setpoint and actual values (the control deviation). This increases or decreases
the speed of the motor to bring the actual value closer to the setpoint value.
The PID control action direction (forward/reverse) can be set with a parameter.
Control Direction
Forward
Reverse
The illustration below shows a typical configuration for maintaining a constant pressure in the con-
trolled system. The example shows the setup for this application for the FR-A800 inverter.
Schematic diagrams for two versions are included. In the first version an external setpoint signal is
provided by a potentiometer connected to the input terminals, in the second the setpoint is set with
the control unit and the value is stored in an inverter parameter.
Power supply
A - 22
Controller Behaviour
Actual > Setpoint: Increase control variable
Actual < Setpoint: Decrease control variable
Actual > Setpoint: Decrease control variable
Actual < Setpoint: Increase control variable
Inverter FR-A800
Fuse
Application (temperature control)
Cooling/refrigeration system
Heating system
Motor and pump
Water inlet
Appendix
Water outlet
p
Pressure
measurement