Delta ASD-A3-0121, Руководство пользователя

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ASDA-A3 Operation Mode
Revision December, 2017
6-23
6
The ASDA-
A3 provides two types of resonance suppression: one is the Notch filter and the
other is the low-pass filter. See the following diagrams for the results of using these filters.
System open-loop gain with resonance:

Notch Filter
(1) Point of resonance (2) Notch filter (3) Point of resonance suppressed by the Notch filter

Low-pass filter
(1) Point of resonance (2) Attenuation rate (-3 dB)
(3) Low-pass filter (Cutoff frequency of low-pass filter = 1000 / P2.025 Hz)
(4) Resonance point suppressed by the low-pass filter
To conclude from these two examples, if you increase the value of P2.025 from 0, the bandwidth
(BW) becomes smaller. Although it solves the problem of resonance, it also reduces the
response bandwidth and phase margin, and thus the system becomes unstable.
If you know the resonance frequency, you can suppress the resonance by using the Notch filter,
which is better than using the low-pass filter in this condition. If the resonance frequency drifts
significantly with time or due to other cause, using the Notch filter is not suggested.