Pulse Frequency Wobbling - Siemens SINAMICS S120 Function Manual

Basic functions

6.8 Pulse frequency wobbling

6.8 Pulse frequency wobbling
The function is available for Motor Modules in chassis format with DRIVE-CLiQ (order
numbers: 6SL3xxx-xxxxx-xxx3) available in vector control.
Pulse frequency wobbling damps the spectral components, which can generate unwanted
noise in the motor. Wobbling can be activated only for pulse frequencies that are lower than
or equal to the current controller frequency (see also p0115[0]).
Wobbling causes the pulse frequency in a modulation interval to deviate from the setpoint
frequency. This means that the actual pulse frequency might be higher than the average
pulse frequency required.
A noise generator can be used to vary the pulse frequency around an average value. In this
case, the average pulse frequency is equal to the setpoint pulse frequency. The pulse
frequency can be varied in every current controller cycle if the cycle is constant. Current
measurement errors resulting from asynchronous pulse and control intervals are
compensated by a correction in the actual current value.
Pulse frequency wobbling can be parameterized with parameter p1810 "Modulator
configuration".
Parameter p1811[0...n] "Pulse frequency wobbling amplitude" can be set to adjust the
magnitude of variation in the pulse frequency wobble to between 0 and 20%. The factory
setting is 0%. For a wobble amplitude of p1811 = 0%, the maximum possible pulse
frequency is p1800 = 2 * 1/current controller cycle (1000/p0115[0]). With a wobble amplitude
setting of p1811 > 0, the maximum possible pulse frequency is p1800 = 1/current controller
cycle (1000/p0115[0]). These conditions apply to all indices.
Note
If pulse frequency wobbling is deactivated, parameter p1811 is set to "0" in all of the indices.
Overview of important parameters (see SINAMICS S120/S150 List Manual)
• p1810
• p1811[0...n]
284
Modulator configuration
Pulse frequency wobbling amplitude
Function Manual, (FH1), 01/2013, 6SL3097-4AB00-0BP3
Drive functions