Special Operation And Frequency Control; Pid Control (Pr. 127 To Pr. 134, Pr. 575 To Pr. 577) - Mitsubishi Electric FR-B-750 to 75K Instruction Manual

Special operation and frequency control

4.20 Special operation and frequency control
Purpose
Perform process control such as pump and air
volume.
Increase speed when the load is light.
Frequency control appropriate for the load torque
Frequency setting by pulse train input
Make the motor speed constant by encoder
Avoid overvoltage alarm due to regeneration by
automatic adjustment of output frequency

4.20.1 PID control (Pr. 127 to Pr. 134, Pr. 575 to Pr. 577)

The inverter can be used to exercise process control, e.g. flow rate, air volume or pressure.
The terminal 2 input signal or parameter setting is used as a set point and the terminal 4 input signal used as a
feedback value to constitute a feedback system for PID control.
Parameter
Name
Number
PID control automatic
127
switchover frequency
128 PID action selection
129 PID proportional band
*1
130 PID integral time
*1
131 PID upper limit
132 PID lower limit
133 PID action set point
*1
228
PID control
Load torque high speed
frequency control
Droop control
Pulse train input
Encoder feedback control
Regeneration avoidance
function
Initial Setting Range
Value
FR-B FR-B3
0 to
120Hz/ 0 to
0 to 120Hz
9999
60Hz
*2
9999
10
11
20
21
10
50
51
60
61
0.1 to 1000%
100%
9999
0.1 to 3600s
1s
9999
0 to 100%
9999
9999
0 to 100%
9999
9999
0 to 100%
9999
9999
Parameter that must be Set
Pr. 127 to Pr. 134,
Pr. 575 to Pr. 577
Pr. 4, Pr. 5, Pr. 270 to Pr. 274
Pr. 286, Pr. 287
Pr. 291, Pr. 384 to Pr. 386
Pr. 144, Pr. 285, Pr. 359,
Pr. 367 to Pr. 369
Pr. 882 to Pr. 886
Description
Set the frequency at which the control is automatically
changed to PID control.
Without PID automatic switchover function
PID reverse action
Deviation value signal input
PID forward action
PID reverse action
Measured value (terminal 4 )
Set point (terminal 2 or Pr. 133)
PID forward action
PID reverse action
Deviation value signal input
(L W
PID forward action
ON
PID reverse action
Measured value, set point input
(L W
PID forward action
ON
If the proportional band is narrow (parameter setting is
small), the manipulated variable varies greatly with a slight
change of the measured value. Hence, as the proportional
band narrows, the response sensitivity (gain) improves but
the stability deteriorates, e.g. hunting occurs.
Gain Kp = 1/proportional band
No proportional control
For deviation step input, time (Ti) required for only the
integral (I) action to provide the same manipulated variable
as that for the proportional (P) action. As the integral time
decreases, the set point is reached earlier but hunting
occurs more easily.
No integral control
Set the upper limit value. If the feedback value exceeds the
setting, the FUP signal is output. The maximum input
(20mA/5V/10V) of the measured value (terminal 4) is
equivalent to 100%.
No function
Set the lower limit value. If the measured value falls below
the setting range, the FDN signal is output. The maximum
input (20mA/5V/10V) of the measured value (terminal 4) is
equivalent to 100%.
No function
Used to set the set point for PID control.
Terminal 2 input is the set point.
Refer
to Page
228
236
238
239
242
244
(terminal 1 )
, CC-Link communication)
ORKS
, CC-Link communication)
ORKS