3  Functions  Issue 10/06 
  MICROMASTER 440      Operating Instructions 
240  6SE6400-5AW00-0BP0 
3.23.1.3  V/f resonance damping 
Parameter range:  P1338 
Warnings - 
Faults - 
Function chart number:  - 
For variable-speed drives, resonance effects can occur in the upper frequency 
range (> 20 Hz). These resonance effects result in an increased noise level and 
also can damage / destroy the mechanical system. These resonance effects can 
occur for: 
¾  Geared motors  
¾ Reluctance motors 
¾ Large motors 
(low stator resistance 
→ poor electrical damping) 
Contrary to the "skip frequency" function (refer to Section 3.12.1 and parameters 
P1091 to P1094), where the resonance frequency is passed through as quickly as 
possible, for the V/f resonance damping (parameter P1338), the resonance effects 
are dampened from a control-related perspective. The advantage of this function is 
that by using this active damping, operation is possible in the resonance range. 
The V/f resonance damping is activated and adjusted using parameter P1338. This 
parameter represents a gain factor that is a measure for the damping of the 
resonance frequency. The following oscillogram indicates the effect of the 
resonance damping function using as an example a reluctance motor with gearbox. 
The phase output currents are displayed for an output frequency of 45 Hz. 
   
  Without V/f resonance damping (P1338 = 0)  V/f resonance damping active (P1338 = 1) 
Fig. 3-99  Effect of V/f resonance damping