54 Rockwell Automation Publication PFLEX-RM003E-EN-E - January 2011
Chapter 1 Detailed Drive Operation
The resonant frequency is defined by the following equation:
• Jm is the motor inertia (seconds).
• Jload is the load inertia (seconds).
• Kspring is the coupling spring constant (rad
2
/sec).
Figure 14
below shows a two mass system with a resonant frequency of 62
radians/second. One Hertz is equal to 2π radians/second.
Figure 14 - Resonance
The small inset shows a better representation of resonant frequency better.
The PowerFlex 700S has a notch filter in the torque reference loop to eliminate
such noise from the system. The notch filter frequency is parameter 118 [Notch
Filt Freq]. Due to the fact that most mechanical frequencies are described in
Hertz, [Notch Filt Freq] is in Hertz as well.
Figure 15 on page 55
shows the same mechanical gear train as in Figure 14 above.
[Notch Filt Freq] is set to 10.
resonance Kspring
Jm Jload+()
Jm Jl oad×
---------------------------------
×=
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