YASKAWA A1000 HHP, Programming Manual

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n 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.
D control tends to amplify noise on the deviation signal, which can result in control instability. Only use D control when
absolutely necessary.
n PID Operation
To better demonstrate PID functionality, Figure 1.20 illustrates the PID output when the PID input (deviation) is at a constant
level.
PID input
I control
PID Output
D control
Time
PID output
Time
P control
Figure 1.20 PID Operation
n Using PID Control
Applications for PID control are listed in Table 1.18 .
Table 1.18 Using PID Control
Application Description Sensors Used
Speed Control
Machinery speed is fed back and adjusted to meet the target value. Synchronous control is
performed using speed data from other machinery as the target value
Tachometer
Pressure Maintains constant pressure using pressure feedback. Pressure sensor
Fluid Control Keeps flow at a constant level by feeding back flow data. Flow rate sensor
Temperature
Control
Maintains a constant temperature by controlling a fan with a thermostat.
Thermocoupler,
Thermistor
n PID Setpoint Input Methods
The PID setpoint input can be input from one of the sources listed in Table 1.19 .
If none of the sources listed in Table 1.19 are used, the frequency reference source in b1-01 (or b1-15) or one of the inputs
listed in Table 1.19 becomes the PID setpoint.
Table 1.19 PID Setpoint Sources
PID Setpoint Source Settings
Analog Input A1 Set H3-02 = C
Analog Input A2 Set H3-10 = C
Analog Input A3 Set H3-06 = C
MEMOBUS/Modbus Register 0006 H Set bit 1 in register 000F H to 1 and input the setpoint to register 0006 H
Pulse Input RP Set H6-01 = 2
Parameter b5-19 Set parameter b5-18 = 1 and input the PID setpoint to b5-19
Note: A duplicate allocation of the PID setpoint input will cause an oPE07 (Multi-Function Analog Input Selection Error) alarm.
n PID Feedback Input Methods
Input one feedback signal for normal PID control or input two feedback signals can for controlling a differential process value.
1.2 b: Application
34 YASKAWA ELECTRIC SIEP YEAHHP 01B YASKAWA AC Drive – A1000 HHP Programming Manual