Toshiba TOSVERT VF-S15 series User manual

E6581879

TOSVERT VF-S15
PID control Instruction Manual

E6581879
－Contents －
1. Introduction............................................................................................................................2
2. PID control function ...............................................................................................................3
2.1. Process PID control .......................................................................................................3
2.2. Speed PID control..........................................................................................................5
3. Parameter list of PID control..................................................................................................7
4. Setting for PID control..........................................................................................................10
4.1. Fundamental setting.....................................................................................................10
4.1.1. Feedback value ................................................................................................10
4.1.2. Process value ................................................................................................... 11
4.1.3. Override function ..............................................................................................15
4.1.4. Acceleration and decleration time.....................................................................15
4.2. Set to suit the motor.....................................................................................................16
4.3. Set to suit the system...................................................................................................16
4.3.1. Set if necessary ................................................................................................16
4.3.2. Switch PID characteristic..................................................................................16
4.3.3. Agreement between process and feedback value............................................17
4.3.4. Switch to frequency command operation .........................................................17
5. PID control adjustment ........................................................................................................18
5.1. Summary of adjustment...............................................................................................18
5.2. Fundamental adjustment (common) ............................................................................18
5.2.1. Proportional (P) gain.........................................................................................18
5.2.2. Integral (I) gain..................................................................................................19
5.2.3. Differential (D) gain...........................................................................................19
5.3. Applied adjustment (Common).....................................................................................20
5.3.1. PID integral / differential clear...........................................................................20
5.3.2. PID control waiting time....................................................................................20
5.4. Applied adjustment (for speed PID control).................................................................21
5.4.1. Delay filter.........................................................................................................21
5.4.2. Process increasing rate/ decreasing rate .........................................................21
6. Analog input characteristics.................................................................................................22
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1. Introduction
VF-S15 has two types of PID control function.
You can select the type for your application.
Process PID control: The control is performed gently in response to change in temperature or
pressure for fan and pump.
Speed PID control : The control is performed at high speed in response to change in speed for
winder.
This manual is constructed as follows;
Chapter 2: Explanation of two types of PID control
Chapter 3: Parameter list for PID control
Chapter 4: Setting parameter for PID control
Chapter 5: Adjustment for PID control
Chapter 6: Analog input characteristics
It is necessary to convert process value and feedback value into frequency for setting.
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2. PID control function
Select one from the two types of PID control function for your application.
2.1.Process PID control
Process PID control is selected for temperature or pressure control of fan and pump which is performed
gently in response to change the speed.
[Process PID control (f360=1)]
[Diagram]
[Parameter setting]
Refer to the chapter 4 and 5 for details of parameter setting.
1) Select the input of process value and feedback value.
It is necessary to convert temperature or pressure into frequency for setting.
Item Title Function
f389 PID control reference signal selection Process value
fpid Process input value of PID control (f389=3)
Feedback value f369 PID control feedback signal selection
Frequency free unit conversion function enables to set process value and feedback value easily.
See the chapter 3 for details.
2) Set the following parameters to suit the motor if necessary.
Title Function
fh Maximum frequency
ul Upper limit frequency
ll Lower limit frequency
f270 to f275
Jump frequency 1 to 3
f240
Starting frequency
f241 Operation starting frequency
PID control Jump
frequency
processing
（ul ）
Output frequency upper limit
Process upper limit
（ll ）
（
f367
）Increase/
Decrease
Process lower limit
（
f368
）－
Feedback value
（acc，dec）
Process value
Output frequency lower limit
PID forward/reverse characteristics selection
（f380）
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3) Set the following parameters to suit the system.
a) Set the acceleration time and deceleration time to short for quick response within the range not to
cause inverter trip.
Title Function
acc Acceleration time 1
dec Deceleration time 1
.
b) Set the following parameters if necessary.
Item Title Function
f367 Process upper limit
Limit the input level of
process value. f368 Process lower limit
f380 PID forward /reverse characteristics selection
Switch the PID forward
/reverse characteristics. Input terminal function:
54/55: PID characteristics switching
f167 Frequency command agreement detection
range
Output of agreement signal
between process value
and feedback value. Output terminal function:
144/145: Signal in accordance of frequency command
4) Adjust the PID control gain.
Refer to chapter 5 for details.
a) Fundamental adjustment
Item Title Function
f362 Proportional gain
f363 Integral gain
PID control gain
f366 Differential gain
b) Adjust the following parameter if necessary.
Item Title Function
Start the PID control after
the system becomes
stable.
f359 PID control waiting time
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2.2.Speed PID control
Speed PID control is selected for speed control of a winder to which fast response is required.
Acceleration/ deceleration time is automatically set to the shortest time. It also responds much faster by
controlling with the increase/ decrease rate which is separated from acceleration/ deceleration time.
Delay filter is set to the feedback value for the stable operation.
[Speed PID control (f360=2)]
[Diagram]
Output frequency
upper limit
（ul）
PID control
Delay filte
r
（f361）
Jump
frequency
processing Output frequency
lower limit
（ll）
Process upper limit
Process lower limit
（f368）
－
Process value
Feedback value
Increase/
Decrease
（f372，f373）
（f380）
PID forward/reverse characteristics selection
(f367）
[Parameter setting]
Refer to the chapter 4 and 5 for details of parameter setting.
1) Select the input of process value and feedback value.
It is necessary to convert tension level into frequency for setting.
Item Title Function
f389 PID control reference signal selection Process value
fpid Process input value of PID control (f389=3)
Feedback value f369 PID control feedback signal selection
a) Frequency free unit conversion function enables to set process value and feedback value easily.
Refer to the chapter 3 for detail.
b) It is possible to add or multiply for process value by override function.
Item Title Function
Addition f660 Override addition input selection
Multiplication f661 Override multiplication input selection
2) Set the following parameters to suit the motor if necessary.
Title Function
fh Maximum frequency
ul Upper limit frequency
ll Lower limit frequency
f270 to f275
Jump frequency 1 to 3
f240
Starting frequency
f241 Operation starting frequency
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3) Set the following parameters to suit the system.
Speed PID control set the acceleration time and the deceleration time to the smallest automatically
regardless of parameter (acc,dec) setting. It also responds much faster by controlling with the
increase/ decrease rate which is separated from acceleration/ deceleration time.
Set the following parameters if necessary.
Item Title Function
f367 Process upper limit
Limit the input level of
process value. f368 Process lower limit
f167 Frequency command agreement detection
range
Output of agreement signal
between process value
and feedback value. Output terminal function:
144/145: Signal in accordance of frequency command
4) Adjust the PID control gain.
Refer to the chapter 5 for details.
a) For fundamental adjustment, adjust for stability, and quick response.
Item Title Function
f362 Proportional gain
f363 Integral gain
PID control gain
f366 Differential gain
Steady the PID control
(Feedback filter) f361 Delay filter
f372 Process increasing rate (speed type PID control)
Adjust for quick response f373 Process decreasing rate (speed type PID control)
b) Adjust the following parameter if necessary.
Item Title Function
Start the PID control after
the system becomes
stable. f359 PID control waiting time
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3. Parameter list of PID control
Title Function Adjustment range Default
setting
fmod Frequency setting mode
selection 1
0:Setting dial 1 (save even if power is off)
1:Terminal VIA
2:Terminal VIB
3:Setting dial 2 (press in center to save)
4:RS485 communication
5:UP/DOWN from external logic input
6:CANopen communication
7: Communication option
8: Terminal VIC
9,10: -
11: Pulse train input
12,13: -
14: sr0
0
acc Acceleration time 1 0.0-3600 (s) 10.0
dec Deceleration time 1 0.0-3600 (s) 10.0
fh Maximum frequency 30.0-500.0 (Hz) 80.0
ul Upper limit frequency 0.5-fh (Hz) *1
ll Lower limit frequency 0.0-ul (Hz) 0.0
sr1
to sr7 Preset-speed frequency 1 to 7 ll-ul (Hz) 0.0
fpid Process input value of PID
control f368 – f367(Hz) 0.0
f167 Frequency command
agreement detection range 0.0-fh(Hz) 2.5
f201 VIA input point 1 setting 0-100(%) 0
f202 VIA input point 1 frequency 0.0-500.0(Hz) 0.0
f203 VIA input point 2 setting 0-100(%) 100
f204 VIA input point 2 frequency 0.0-500.0(Hz) *1
f207 Frequency setting mode
selection 2
0-14 (Same as fmod ) 1
f210 VIB input point 1 setting -100-+100(%) 0
f211 VIB input point 1 frequency 0.0-500.0(Hz) 0.0
f212 VIB input point 2 setting -100-+100(%) 100
f213 VIB input point 2 frequency 0.0-500.0(Hz) *1
f216 VIC input point 1 setting 0-100(%) 20
f217 VIC input point 1 frequency 0.0-500.0(Hz) 0.0
f218 VIC input point 2 setting 0-100(%) 100
f219 VIC input point 2 frequency 0.0-500.0(Hz) *1
f240 Starting frequency 0.1-10.0 (Hz) 0.5
f241 Operation starting frequency 0.0-fh (Hz) 0.0
f270 Jump frequency 1 0.0-fh (Hz) 0.0
f271 Jumping width 1 0.0-30.0 (Hz) 0.0
f272 Jump frequency 2 0.0-fh (Hz) 0.0
f273 Jumping width 2 0.0-30.0 (Hz) 0.0
f274 Jump frequency 3 0.0-fh (Hz) 0.0
f275 Jumping width 3 0.0-30.0 (Hz) 0.0
f359 PID control waiting time 0-2400 (s) 0
f360 PID control 0:Disabled
1:Process type PID control
2:Speed type PID control
0
f361Delay filter 0.0-25.0 (s) 0.1
f362Proportional gain 0.01-100.0 (s) 0.30
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f363 Integral gain 0.01-100.0 (s-1) 0.20
f366 Differential gain 0.00-2.55 (s) 0.00
f367 Process upper limit 0.0-fh (Hz) *1
f368 Process lower limit 0.0-f367 (Hz) 0.0
f369 PID control feedback signal
selection 0:Disabled 1:Terminal VIA
2: Terminal VIB
3:Terminal VIC
4 to 6: -
0
f372 Process increasing rate
(speed type PID control) 0.1-600.0 (s) 10.0
f373 Process decreasing rate
(speed type PID control) 0.1-600.0 (s) 10.0
f380 PID forward /reverse
characteristics selection 0:Forward 1:Reverse 0
f389 PID control reference signal
selection 0:fmod/ f207 selected 1:Terminal VIA
2:Terminal VIB
3:fpid
4:RS485 communication
5:UP/DOWN from external logic input
6:CANopen communication
7:Communication option
8: Terminal VIC
9,10: -
11: Pulse train input
0
f660 Override addition input
selection 0:Disabled 1:Terminal VIA
2: Terminal VIB
3:Terminal VIC
4: fc
0
f661 Override multiplication input
selection 0:Disabled 1:Terminal VIA
2: Terminal VIB
3:Terminal VIC
4: f729
0
f702 Frequency free unit display
magnification 0.00:Disabled (display of frequency)
0.01-200.0(times) 0.00
f703 Frequency free unit coverage
selection 0:All frequencies display
1:PID frequencies display 0
f729 Operation panel override
multiplication gain -100-+100 (%) 0
*1: Default setting values vary depending on the setup menu setting.
[Input /Output terminal function]
Positive logic Negative logic Function
36 37 PID control prohibition
52 53 PID integral / differential clear
Input terminal 54 55 PID characteristics switching
Output terminal 144 145 Signal in accordance of frequency command
[FM/ pulse output and monitor output function]
FM/ Pulse output Monitor output
Option No. Communication No. Option No. Communication No. Function
2 FD02 2 FE02 Frequency setting value
23 FD22 23 FE22 PID feedback value
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You need to convert the process value and the feedback value into frequency for the PID control.
f702 (Frequency free unit display magnification) and f703 (Frequency free unit coverage
selection) enable to set process value and feedback value easily. The functions convert frequency display
to temperature or pressure level by calculation.
Value displayed = Frequency displayed on the monitor or specified with a parameter × 
f703 = 0
Frequency on the monitor or specified with parameter is displayed by the value multiplied by .
Note) This setting does not change automatically if you switch from PID control to frequency
command operation. Output frequency is displayed by the value by .
f703 = 1
Frequency of the following parameters and the frequency on the monitor are displayed by the value
multiplied by 
[Parameters]
Title Function
fpid Process input value of PID control
f367 Process upper limit
f368 Process lower limit
[FM/ pulse output and monitor display]
FM/ Pulse output Monitor output
Option No. Communication No. Option No. Communication No. Function
2 FD02 2 FE02 Frequency setting value
23 FD22 23 FE22 PID feedback value
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4. Setting for PID control
First, set the process value and feedback value. : 4.1
Then, set other parameters to suit the motor and the system if necessary. : 4.2, 4.3
Note) Set process value and feedback value by converting each pressure level into frequency.
Actual output frequency is different from setting frequency for PID control.
4.1.Fundamental setting
Make sure to set the process value and the feedback value.
In case of process type PID control, you need to set acceleration time and deceleration time to short for
quick response.
4.1.1. Feedback value
Input the signal from detector as feedback signal.
1. Select the feedback signal at f369.
Description PID control feedback signal selection (f369)
Disabled 0
Terminal VIA 1
Terminal VIB 2
Terminal VIC 3
2. Set feedback value after converting the feedback input level into frequency.
1) Analog input
Refer to the chapter 6 for details of analog input characteristic setting.
[Example of feedback setting]
Condition: Pressure control as PID control.
Input the feedback signal of 1 to 2 atm into VIC terminal by 4 to 20mA signal.
f219
(60Hz)
f217
(0Hz)
4mA
f216
20%
20mA
2 atm
1 atm 4mA 20mA
f218
100%
Feedback value Parameter setting
(Converted frequency)
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It is possible to set or switch the forward/ reverse characteristics.
a) Example of setting reverse characteristic
Parameter setting
(Converted frequency)
f217
b) Example of switching characteristic by S3 input terminal (positive logic)
4.1.2. Process value
Input the target value in relation to the feedback value as process value.
1. Select the process signal at f389.
Description PID control reference signal selection (f389)
fmod / f207 selected 0
Terminal VIA 1
Terminal VIB 2
fpid 3
RS485 communication 4
UP/DOWN from external logic input 5
CANopen communication 6
Communication option 7
Terminal VIC 8
Pulse train input 11
It is possible to add or multiply for process value by override function.
(60Hz)
f219
(0Hz) 4mA
f216
20mA
f218
S3 terminal ON
S3 terminal OFF
f219
(60Hz)
f217
(0Hz)
4mA
f216 20mA
f218
20%
Parameter setting
(Converted frequency)
*When switching the characteristics using
terminals, not only characteristics of process
value but also of feedback value switches.
100%
Title Function Example of setting
Input terminal selection 6 (S3) 54: PID characteristics switching
f116 VIC input point 1 setting 20(%)
f216
f217 VIC input point 1 frequency 0(Hz)
f218 VIC input point 2 setting 100(%)
f219 VIC input point 2 frequency 60(Hz)
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2. Perform the setting of feedback input level after converting it into frequency.
<Note>
Input process value needs to be less than maximum feedback value.
If the input process value is same as maximum feedback value or more, the deviation becomes
zero when the feedback value reaches maximum. The output frequency is fixed even though
actual output becomes even more higher, because the feedback value will not exceed maximum.
Upper limit of process value input can be set by parameter f367: Process upper limit.
1) fpid setting
[Example of process value setting]
Condition: Pressure control as PID control.
Input the feedback signal of 1 to 2 atm into terminal VIC by 4 to 20mA signal.
Input the process value by fpid setting.
Title Function Setting (Example)
fpid Process input value of PID control 30(Hz)
f216 VIC input point 1 setting 20(%)
f217 VIC input point 1 frequency 0(Hz)
f218 VIC input point 2 setting 100(%)
f219 VIC input point 2 frequency 60(Hz)
f389 PID control reference signal selection 3: fpid
Note 1) Value of fpid can be set or changed during operation with the use of setting dial, and then
saved in fpid.
Note 2) Input process value needs to be less than maximum feedback value.
2) Analog input
Refer to the chapter 6 for detail of analog input characteristic setting.
[Example of process value setting]
Condition: Pressure control as PID control.
Input the feedback signal of 1 to 2 atm into Terminal VIC by 4 to 20mAsignal.
Input the process value into Terminal VIB by 0 to 10V signal.
2 atm
1.5 atm
1 atm 4mA 20mA
60Hz
0Hz 4mA 20mA
Feedback value Feedback value
(Converted frequency) Process value
(Converted frequency)
fpid: 30Hz (1.5 atm)
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[Example of system]
[Parameter setting]
Convert the pressure feedback value and pressure process value into frequency.
Actual output frequency is, regardless of the converted frequency, the output frequency as a result
of PID control.
<Note>
Input process value needs to be less than maximum feedback value.
If the process value is 2 atm=10V (60Hz), the deviation becomes zero when the feedback value
reaches 2 atm=20mA (60Hz). The output frequency is fixed even though actual output becomes
even more higher, because the feedback value will not exceed over 20mA (60Hz).
Feedback value
4 to 20mA
Process value
0 to 10Vdc
1 to 2 atm
Pump
P
R/L1
S/L2
T/L3
U/T1
V/T2
Power supply W/T3
VIB
CC
VIC
Pressure
senso
r
M
Inverter
2 atm
1.5 atm
1 atm 4mA 20mA
60Hz
0Hz 4mA 20mA
Feedback value Feedback value
(Converted frequency) 2 atm
1.5 atm
1 atm
0V 10V 0V
60Hz
0Hz 10V
Process value Process value
(Converted frequency)
Pressure
(atm) Feedback value (4-20mA) Process value (0-10V) Converted frequency (Hz)
1 4 0 0
1.25 8 2.5 15
1.5 12 5.0 30
1.75 16 7.5 45
2 20 10 60
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Title Function Setting (Example)
f107 Analog input terminal selection (VIB) 0:0-+10V
f210 VIB input point 1 setting 0(%)
f211 VIB input point 1 frequency 0(Hz)
f212 VIB input point 2 setting 100(%)
f213
VIB input point 2 frequency 60(Hz)
f216 VIC input point 1 setting
20(%)
f217 VIC input point 1 frequency 0(Hz)
f218 VIC input point 2 setting 100(%)
f219 VIC input point 2 frequency 60(Hz)
f389 PID control reference signal selection 2: Terminal VIB
3) Preset speed
[Example of process value setting]
Condition: Pressure control as PID control.
Input the feedback signal of 1 to 2 atm into Terminal VIC by 4 to 20mAsignal.
Input the process value into Terminals S1 and S2 by preset speed 1, 2, and 3 settings.
Note) Input process value needs to be less than maximum feedback value.
Process value
Pressure
(atm) Feedback value (4-20mA) Preset speed
1 to 3 S1 terminal S2 terminal
Converted frequency
(Hz)
1 4 - - - 0
1.25 8 1 ON OFF 15
1.5 12 2 OFF ON 30
1.75 16 3 ON ON 45
2 20 - - - 60
2 atm
1.5 atm
1 atm 4mA 20mA
60Hz
0Hz 4mA 20mA
Feedback value Feedback value
(Converted frequency) Process value
(Converted frequency)
Preset speed 3: 45Hz (1.75 atm)
Preset speed 2: 30Hz (1.5 atm)
Preset speed 1: 15Hz (1.25 atm)
Title Function Setting (Example)
sr1 Preset speed frequency 1 15(Hz)
 Preset speed frequency 2 30(Hz)
 Preset speed frequency 3 45(Hz)
f114 Input terminal selection 4A (S1) 10: Preset speed 1
f115 Input terminal selection 5 (S2) 12: Preset speed 2
f216VIC input point 1 setting 20(%)
f217VIC input point 1 frequency 0(Hz)
f218VIC input point 2 setting 100(%)
f219 VIC input point 2 frequency 60(Hz)
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4.1.3. Override function
Speed type
Override functions (f660, f661) enable to add or multiply for fine adjustment of process value.
It is possible to set multiplication gain by analog input or parameter f729.
Refer to the inverter instruction manual for the detail of the setting.
* This function is valid also for process type PID, but it is rarely used.
4.1.4. Acceleration and deceleration time
Process type
Set the acceleration time (acc) and deceleration time (dec) to short for quick response.
But excessively small setting causes inverter trip.
Speed type
Speed PID control set the acceleration time and the deceleration time to the smallest automatically
regardless of parameter (acc,dec) setting
* Adjust each gain in case that the inverter trips. If you need to extend acceleration time and the
deceleration time, select the process type PID control.
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4.2. Set to suit the motor
Set only the parameters necessary for the motors.
These parameters are valid for actual output frequency as a result of PID control.
Title Function Description
fh Maximum frequency 1) Set the maximum frequency of the output frequency.
2) This is the basis of the acceleration time (acc) and
deceleration time (dec).
Acceleration time (acc): time from 0Hz to fh.
Deceleration time (dec): time from fh to 0Hz.
ul Upper limit frequency This is the upper limit of output frequency.
ll Lower limit frequency This is the lower limit of output frequency.
f270 to
f275
Jump frequency
1 to 3 Set the jump frequency to avoid (jump) resonance of the machinery.
f240 Starting frequency
1) The inverter outputs frequency of f240 immediately. 2) It is useful for quick response of starting torque.
f241 Operation starting
frequency The inverter operates (Run/Stop) by f241 setting frequency
Note) Note that the inverter may run and stop frequently when setting large value for f241.
4.3. Set to suit the system
4.3.1. Set if necessary
Set the following parameters if necessary.
Title Function Description
f367 Process upper limit 1) This is upper limit of process value.
2) If the process value exceeds the upper limit of
feedback value, the output frequency is fixed. (Refer to
4.2.1 for details.)
Set the upper limit of process value when it is difficult to
adjust by the input level of process value.
f368 Process lower limit This is lower limit of process value.
4.3.2. Switch PID characteristics
You can set and switch the PID forward / reverse characteristics.
It is useful for process type PID control including hot / cool switching of temperature control.
Title Function Description
f380 PID forward /reverse
characteristics
selection
You can select the PID forward / reverse characteristics.
You can switch the characteristics of process value and
feedback value by the input signal.
[Input terminal function]
Positive
logic Negative logic Function Description (Positive logic)
54 55
PID characteristics
switching Switch the PID forward / reverse characteristics of the process value and the feedback value.
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4.3.3. Agreement between process and feedback value
It is possible to output agreement signal between the process value and the feedback value. Signal is
output when the frequency command value by f389 and the feedback value by f369 are within ±
f167.
Title Function Description
f167 Frequency command
agreement detection
range
Set the PID frequency command agreement detection
range. 0.0～fh(Hz)
[Output terminal function]
Positive
logic Negative logic Function Description (Positive logic)
144 145
Signal in accordance
of frequency
command
Frequency command by f389 and f369 are
within ±f167.
4.3.4. Switch to frequency command operation
You can switch from PID control to frequency command operation by input terminal signal.
The inverter operates with the frequency set by frequency setting mode selection fmod (or
f207).
Process type
The acceleration time and the deceleration time are set small for quick response of the PID control.
You can use the second acceleration time and deceleration time if necessary.
[Input terminal function]
Positive
logic Negative logic Function Description (Positive logic)
36 37
PID control
prohibition Switch to frequency command operation after PID control is OFF
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5. PID control adjustment
5.1. Summary of adjustment
<In case with the estimate of PID gain>
Set the estimated value of PID gain and check the operation of the system.
Adjust the gain if necessary.
<In case without the estimate of PID gain>
1) First, operate the inverter by default setting gain and check the operation of the system.
2) Adjust the fundamental gain.
(1) Adjust the proportional (P) gain if the response is delayed.
(2) Adjust the integral (I) gain if the unstable condition continues.
(3) Adjust the differential (D) gain if the system always changes or continues unstable condition
even after PI gain adjustment.
3) Apply further adjustment for stability if necessary.
* Adjust the delay filter to stabilize the speed PID control.
5.2. Fundamental adjustment (common)
The fundamental gain of PID control adjusted according to the system.
PID control
dtxd
KddtxKixKpy   
x（Hz）y（Hz）
PID output frequency
Symbol Title Function Set value
Kp f362 Proportional gain f362=1.0: Kp =1.0
Ki f363 Integral gain f363=1.0: Ki =1.0（s-1）
Kd f366 Differential gain f366=1.0: Kd =1.0（s）
5.2.1. Proportional (P) gain
Set the proportional (P) gain of PID control by f362.
The proportional (P) gain, a factor gained by multiplying the deviation (difference between the process
value and the feedback value), is used to perform control so as to make a correction in proportion to the
deviation. Although larger gain is effective for quicker response, excessively high gain may cause an
unstable operation including vibration.
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High proportional
gain f362
Quick response
Low proportional
gain f362
Slow response
Process value reference
Output frequency
Time
5.2.2. Integral (I) gain
Set the integral (I) gain of PID control by f363.
The integral gain reduces the deviation remaining after proportional control (residual deviation offset) to
zero.
Although larger gain reduces the residual deviation, excessively high gain may cause an unstable
operation including vibration.
High integral gain f363
Low integral gain f363
Process value reference
Output frequency
Residual deviation
Time
5.2.3. Differential (D) gain
Set the differential (D) gain of PID control by f366.
The differential gain increases the response speed in case of radical change in deviation.
However, excessively high gain may cause instability including ,considerable fluctuations of output
frequency.
Previous deviation
－Current deviation Time
Hi
g
h differential
g
ain
Low differential gain
Output frequency
Time
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