Input Terminal For Pid Feedback - Honeywell VFD CORE Installation Instructions Manual

08 High-function PID Parameters
08 - 00

Input Terminal for PID Feedback

Settings
• Negative feedback means: +target value – feedback. It is used for the detection value will be increased by increasing the
output frequency.
• Positive feedback means: -target value + feedback. It is used for the detection value will be decreased by increasing the output
frequency.
• Common applications for PID control
1. Flow control: A flow sensor is used to feedback the flow data and performs accurate flow control.
2. Pressure control: A pressure sensor is used to feedback the pressure data and performs precise pressure control.
3. Air volume control: An air volume sensor is used to feedback the air volume data to have excellent air volume regulation.
4. Temperature control: A thermocouple or thermistor is used to feedback temperature data for comfortable temperature
control.
5. Speed control: A speed sensor or encoder is used to feedback motor shaft speed or input another machines speed as a
target value for closed loop speed control of master-slave operation.
Pr.10.00 sets the PID set point source (target value). PID control operates with the feedback signal as set by Pr.10.01 either
0~+10V voltage or 4-20mA current.
• PID control loop:
• Concept of PID control
1. Proportional gain (P): the output is proportional to input. With only proportional gain control, there will always be a steady-
state error.
2. Integral time (I): the controller output is proportional to the integral of the controller input. To eliminate the steady-state error,
an "integral part" needs to be added to the controller. The integral time decides the relation between integral part and error.
The integral part will be increased by time even if the error is small. It gradually increases the controller output to eliminate the
error until it is 0. In this way a system can be stable without steady-state error by proportional gain control and integral time
control.
3. Differential control (D): the controller output is proportional to the differential of the controller input. During elimination of the
error, oscillation or instability may occur. The differential control can be used to suppress these effects by acting before the
error. That is, when the error is near 0, the differential control should be 0. Proportional gain (P) + differential control (D) can be
used to improve the system state during PID adjustment.
0: No function
1: Negative PID feedback: input from external terminal AVI1 (Pr.03-00)
4: Positive PID feedback from external terminal AVI1 (Pr.03-00)
+
SETPOINT
K (1 +
p
–
DRIVE EXECUTE PID CONTROL
FEEDBACK
SIGNAL
K : PROPORTIONAL GAIN (P) T
p
T : DERIVATIVE CONTROL (D) S: OPERATOR
d
CHAPTER 12: DESCRIPTION OF PARAMETER SETTINGS
~
The parameter can be set during operation.
OUTPUT
VALUE
1
+ T x S)
I M
d
T x S
i
SENSOR
: INTEGRAL TIME (I)
i
205
Factory Setting: 0
M33689
63-4528—04