B5: pi control – Yaskawa AC Drive Z1000 AC Drive HVAC Fan User Manual
Page 37
n
Timer Function Operation
The timer function switches on when the timer function input closes for longer than the value set to b4-01. The timer function
switches off when the timer function input is open for longer than the value set to b4-02.
function operation:
b4-01
b4-02
b4-01
b4-02
Multi-function Contact
Input: Timer Function
On (Closed)
Off (Open)
On (Closed)
Off (Open)
Multi-function Contact
Output: Timer Function
ON
ON
ON
ON
Figure 1.14 Timer Operation
u
b5: PI Control
The drive has a built-in Proportional + Integral (PI) controller that uses the difference between the target value and the feedback
value to adjust the drive output frequency to minimize deviation and provide accurate closed loop control of system variables
such as pressure or temperature.
n
P Control
The output of P control is the product of the deviation and the P gain so that it follows the deviation directly and linearly. With
P control, only an offset between the target and feedback remains.
n
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.
n
PI Operation
To better demonstrate PI functionality, the diagram below illustrates how the PI output changes when the PI input (deviation)
jumps from 0 to a constant level.
PI input
I control
PI Output
Time
PI output
Time
P control
Figure 1.15 PI Operation
n
Using PI Control
Applications for PI control are listed in the following table.
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
PI Setpoint Input Methods
The PI setpoint input depends on the PI function setting in parameter b5-01.
1.2 b: Application
YASKAWA ELECTRIC SIEP YAIZ1U 03A YASKAWA AC Drive – Z1000 Programming Manual
37
1
Parameter Details