Parameters: 7-** Controllers - Danfoss VLT AutomationDrive FC 301 Programming Manual

Parameter Descriptions

3.9 Parameters: 7-** Controllers

3.9.1 7-0* Speed PID Ctrl.
3 3
7-00 Speed PID Feedback Source
Option:
[0] Motor feedb. P1-02
[1] 24V encoder
[2] MCB 102
[3] MCB 103
[4] MCO Encoder 1 X56
[5] MCO Encoder 2 X55
[6] Analog Input 53
[7] Analog Input 54
[8] Frequency input 29
[9] Frequency input 33
[11] MCB 15X
NOTICE
If separate encoders are used (FC 302 only) the ramp
settings parameters in the following parameter groups:
3-4*, 3-5*, 3-6*, 3-7* and 3-8* must be adjusted
according to the gear ratio between the 2 encoders.
7-02 Speed PID Proportional Gain
Range:
Size [0
related - 1 ]
*
102
VLT
Function:
NOTICE
This parameter cannot be
adjusted while the motor is
running.
Select the encoder for closed loop
feedback.
The feedback may come from a
different encoder (typically mounted
on the application itself) than the
motor mounted encoder feedback
selected in 1-02 Flux Motor Feedback
Source.
Function:
Enter the speed controller proportional gain.
The proportional gain amplifies the error (i.e.
the deviation between the feedback signal and
the set-point). This parameter is used with
1-00 Configuration Mode [0] Speed open loop
and [1] Speed closed loop control. Quick control
is obtained at high amplification. However if
the amplification is too great, the process may
become unstable.
Use this parameter for values with 3 decimals.
For a selection with 4 decimals, use 3-83 Quick
Stop S-ramp Ratio at Decel. Start.
®
AutomationDrive FC 301/302 Programming Guide
7-03 Speed PID Integral Time
Range:
Size
related 20000
*
ms]
7-04 Speed PID Differentiation Time
Range:
Size
related
*
7-05 Speed PID Diff. Gain Limit
Range:
5 [1 -
*
20 ]
7-06 Speed PID Lowpass Filter Time
Range:
Size
related [0.1
*
-
100
ms]
MG33MH02 - Rev. 2013-09-30
Function:
[1.0 - Enter the speed controller integral time,
which determines the time the internal PID
control takes to correct errors. The greater
the error, the more quickly the gain
increases. The integral time causes a delay of
the signal and therefore a dampening effect,
and can be used to eliminate steady state
speed error. Obtain quick control through a
short integral time, though if the integral
time is too short, the process becomes
unstable. An excessively long integral time
disables the integral action, leading to major
deviations from the required reference, since
the process regulator takes too long to
regulate errors. This parameter is used with
[0] Speed open loop and [1] Speed closed loop
control, set in 1-00 Configuration Mode.
Function:
[0 - Enter the speed controller differentiation
200 time. The differentiator does not react to
ms] constant error. It provides gain proportional
to the rate of change of the speed feedback.
The quicker the error changes, the stronger
the gain from the differentiator. The gain is
proportional with the speed at which errors
change. Setting this parameter to zero
disables the differentiator. This parameter is
used with 1-00 Configuration Mode [1] Speed
closed loop control.
Function:
Set a limit for the gain provided by the differentiator.
Since the differential gain increases at higher
frequencies, limiting the gain may be useful. For
example, set up a pure D-link at low frequencies and
a constant D-link at higher frequencies. This
parameter is used with 1-00 Configuration Mode [1]
Speed closed loop control.
Function:
Set a time constant for the speed control low-
pass filter. The low-pass filter improves steady-
state performance and dampens oscillations on
the feedback signal. This is an advantage if
there is a great amount on noise in the system,
see Illustration 3.44. For example, if a time
constant (τ) of 100 ms is programmed, the cut-
off frequency for the low-pass filter is 1/0.1= 10
RAD/s., corresponding to (10/2 x π) = 1.6 Hz.
The PID regulator only regulates a feedback