Moeller DF51 - PID Control

10/05 AWB8230-1541GB
PID control
131
PID control
The DF51 frequency inverters have a PID controller, which you can
enable with PNU A071 = 1 or through a digital input (PNU C001
to C005 = 23, PID).
h
PID control is superimposed on the frequency inverter
function. You should therefore set all of the frequency
inverter’s drive-related parameters, such as maximum
output frequency (motor speed), acceleration and
deceleration ramps (mechanical load, belts). Frequency
inverter and motor are process-integrated actuators. The
output frequency to the motor (which determines the
speed) is specified as manipulated variable from the PID
controller.
h
When PID control is enabled, the reference and actual
values become process variables and are automatically
converted into percentages. The specified reference value
(0 – 100 %) corresponds with, for example, a volume
flow rate (0 – 50 m
3
/h). The process variable is the
reading (m
3
/h) from a sensor and is again evaluated as a
percentage (0 100 %). If this process data is to be
output as a physical unit (m
3
/h), you can set the
conversion with PNU A075 (see display factor A075 in
table below).
PNU Function RUN b031 =
10
Value Function DS
A001 Reference value source
selection
– – 00 The setting range is limited by PNU b082 (raised
starting frequency) and A004 (maximum frequency).
• Potentiometer (keypad)
• Frequency [Hz]
• Process variable [%] with active PID control
(PNU A071 = 1)
01
01 Analog input: Control signal terminals O and OI
02 Set value (PNU F001) of the keypad (arrow keys
Í/Ú). To save the set value, press the ENTER key
(PNU A020).
03 Serial interface (Modbus)
10 Calculator: Calculated value (CAL) (a section
“Mathematical functions”, page 127).
A071 PID control – j Activating PID control 00
00 OFF, disabled
01 ON, enabled
A072 PID controller – P-
component
j j 0.2 – 5.0 Proportional gain (K
P
)
• Low values attenuate the control action
• High values can cause oscillation.
0.1
A073 PID controller – I-
component
j j 0.0 – 150 s Integral time constant 0.1
A074 PID controller – D-
component
j j 0.00 – 100 s Differential time constant 0.01
A075 PID control, display factor
– j 0.01 – 99.99 Actual value indication, multiplication factor for
displaying process variables.
1.00
A076 PID controller – actual
value signal PV input
– j Selection of actual value input 00
00 Analog input OI (4 – 20 mA)
01 Analog input O (0 – 10 V)
02 Serial interface (Modbus)
10 Calculated value (PNU A143)
(a section “Mathematical functions”, page 127 )
A077 PID control – invert input
signals
– j 00 OFF, disabled, reference value (+), actual value (–) 00
01 ON, enabled, reference value (–), actual value (+)