132 Rockwell Automation Publication PFLEX-RM003E-EN-E - January 2011
Chapter 1 Detailed Drive Operation
FIR Filter
The recommended setting for the FIR filter is eight taps when parameter 146
[FW TaskTime Sel] is set to 0 or 1 (0.5ms for task 1). When parameter 146 [FW
TaskTime Sel] is set to 2 (0.25 ms for task 1) the recommended setting for the
FIR filter is 16 taps. This sets the noise bandwidth for 120 radians/second. The
recommended setting reduces the effect of noisy feedback on the system, but
values above 120 radians/second for the speed regulator bandwidth may not be
effective.
In some cases, it may be desirable to increase the noise bandwidth in order to
allow a speed regulator bandwidth higher than 120 radians/second. The setting
of the FIR filter and parameter 89 [Spd Err Filt BW] can be changed to achieve a
higher noise bandwidth according to the following tables:
FIR and P89 [Spd Err Filt BW] Settings when P146 [FW TaskTime Sel] = 0 or 1:
FIR and P89 [Spd Err Filt BW] Settings when P146 [FW TaskTime Sel] = 2:
Sensorless
Sensorless mode is used when zero speed or more than a 120:1 speed range is not
required.
Parameter 226 [Motor Speed Est] contains the estimated motor speed, used
when sensorless mode is selected. The estimated speed feedback is based on
voltage feedback from the motor.
Parameter 227 [Motor Posit Est] is an estimated position for sensorless mode. It
is calculated based on parameter 226 [Motor Speed Est] and the value in
parameter 225 [Virtual Edge/Rev]. [Virtual Edge/Rev] is a user-defined value
for the number of pulses per motor revolution.
FIR filter setting (taps) 1 2 4 8 16 32 64 127
Spd Err Filt BW (rad/sec) 2000 1500 1300 600 300 150 75 38
Noise bandwidth (rad/sec) 400 300 220 120 60 30 18 8
FIR filter setting (taps) 1 2 4 8 16 32 64 127
Spd Err Filt BW (rad/sec) 4100 3200 2200 1300 600 300 150 75
Noise bandwidth (rad/sec) 690 530 380 240 120 60 30 15
227
225
Virtual Edge/Rev
Motor Posit Est
to Feedbac
Selection
226
Accum
1
1-Z
-1
Motor Speed Est
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