YASKAWA A1000 Technical Manual page 168

5.2 b: Application

I Control
The output of I control is the integral of the deviation. It minimizes the offset between target and feedback value that
typically remains when pure P control is used. The integral time (I time) constant determines how fast the offset is
eliminated.

D Control
D control predicts the deviation signal by multiplying its derivative (slope of the deviation) with a time constant, then
adds this value to the PID input. This way the D portion of a PID controller provides a braking action to the controller
response and can reduce the tendency to oscillate and overshoot.
Be aware that D control tends to amplify noise on the deviation signal, which can result in control instability. D control
should therefore only be used when necessary.

PID Operation
To better demonstrate how PID works,
jumps from 0 to a constant level.
Figure 5.25

Using PID Control
Applications for PID control are listed in
Application
Machinery speed is fed back and adjusted to meet the target value. Synchronous control is performed using speed data from
Speed Control
other machinery as the target value
Pressure Maintains constant pressure using pressure feedback.
Fluid Control Keeps flow at a constant level by feeding back flow data.
Temperature Control Maintains a constant temperature by controlling a fan with a thermostat.

PID Setpoint Input Methods
The PID setpoint input can be input from one of the sources listed in
If none of the sources listed in
listed in Table 5.9 becomes the PID setpoint.
PID Setpoint Source
Analog Input A1
Analog Input A2
Analog Input A3
MEMOBUS/Modbus Register 0006H
Pulse Input RP
Parameter b5-19
Note: A duplicate allocation of the PID setpoint input will cause an oPE07 (Multi-Function Analog Input Selection Error) alarm.
168
Figure 5.25 shows how the PID output changes when the PID input (deviation)
PID input
D control
PID Output
Figure 5.25 PID Operation
Table 5.8.
Table 5.8 Using PID Control
Description
Table 5.9 are used, the frequency reference source in b1-01 (or b1-15) or one of the inputs
Table 5.9 PID Setpoint Sources
Set H3-02 = C
Set H3-10 = C
Set H3-06 = C
Set bit 1 in register 000FH to 1 and input the setpoint to register 0006H
Set H6-01 = 2
Set parameter b5-18 = 1 and input the PID setpoint to b5-19
YASKAWA ELECTRIC SIEP C710616 27G YASKAWA AC Drive A1000 Technical Manual
Time
PID output
I control
P control
Time
Table 5.9.
Settings
Sensors Used
Tachometer
Pressure sensor
Flow rate sensor
Thermocoupler, Thermistor