GE AF-650 GP Programming Manual page 171

PI-06 Speed PID Lowpass Filter Time
Range:
10.0 ms* [1.0 - 100.0 ms]
3
PI-07 Speed PID Feedback Gear Ratio
Range:
1.0000* [0.0001 - 32.0000]
170
Function:
Set a time constant for the speed control low-pass filter. The low-pass filter improves steady-state per-
formance and dampens oscillations on the feedback signal. This is an advantage if there is a great amount
on noise in the system, see illustration below. For example, if a time constant (τ) of 100 ms is programmed,
the cut-off frequency for the low-pass filter will be 1/0.1= 10 RAD/sec., corresponding to (10/2 x π) = 1.6
Hz. The PID regulator only regulates a feedback signal that varies by a frequency of less than 1.6 Hz. If
the feedback signal varies by a higher frequency than 1.6 Hz, the PID regulator does not react.
Practical settings of par. PI-06 Speed PID Lowpass Filter Time taken from the number of pulses per revo-
lutions from encoder:
Encoder PPR
512
1024
2048
4096
Note that severe filtering can be detrimental to dynamic performance.
This parameter is used with par. H-40 Configuration Mode Speed closed loop [1] and Torque [2] control.
The filter time in flux sensorless must be adjusted to 3-5 ms.
Function:
AF-650 GP Programming Guide
par. PI-06 Speed PID Lowpass Filter Time
10 ms
5 ms
2 ms
1 ms