Setting
up Compax3
Positioning via digital I/Os
170
192-120101 N11 C3I11T11 November 2007
Frequency response of the notch filter.
Center frequency = 500Hz
Bandwitdh = 50Hz
Depth = 0.99 (-40dB)
Parameterization by 3 objects.
In this chapter you can read about:
Frequency filter 1 (O2150.1) / frequency filter 2 (O2150.4) .............................................................170
Bandwidth filter 1 (O2150.2) / bandwidth filter 2 (O2150.5).............................................................170
Depth filter 1 (O2150.3) / depth filter 2 (O2150.6) ...........................................................................171
Frequency filter 1 (O2150.1) / frequency filter 2 (O2150.4)
This defines the frequency at which the notch filter attenuation is highest. In
practice it shows that notch filters can only sensibly be used if the distance
between the controller bandwidth (velocity loop) and the center frequency is long
enough (at least factor 5). This permits to deduce the following recommendation:
4
x
or
1
x
]
[
17
.
2210
2
5000000
.
2150
=
=
⋅
≥
µs
O
x
O
π
Obj2210.17: Recplacement time constant of the velocity loop in µs.
If this distance is too small, the stability of the control can be very negatively
influenced!
Bandwidth filter 1 (O2150.2) / bandwidth filter 2 (O2150.5)
This defines the width of the notch filter.
The value refers to the entire frequency band, where the attenuation of the filter is
higher than (-)3dB.
In practice it shows that even if there is enough distance towards the control, it can
be negativley influenced by too high bandwidths (higher than 1/4 of the center
frequency).
5
x
or
2
x
4
4
/
1
.
2150
.
2150
=
=
≤
O
x
O
Note:
