Pulse Frequency Wobbling - Siemens SINAMICS S120 Function Manual

6.6

Pulse frequency wobbling

Description
The function is available for Motor Modules in chassis format with DRIVE-CLiQ (order
numbers: 6SL3xxx-xxxxx-xxx3) available as of firmware version 2.6 in vector control mode.
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.
The number of axes that can be implemented for each CU is exactly the same for a non-
wobbled gating unit.
Pulse frequency wobbling can be parameterized with parameter p1810 "Modulator
configuration".
Parameters (see SINAMICS S120/S150 List Manual)
p1810 Modulator configuration
● Bit 0: DC link voltage limitation
● Bit 1: DC link voltage compensation
Drive functions
Function Manual, (FH1), 10/2008, 6SL3097-2AB00-0BP5
Bit 0 = 0:
Voltage limitation derived from DC link voltage minimum (lower ripple in the output
current; reduced output voltage).
Bit 0 = 1:
Voltage limitation derived from mean DC link voltage (increased output voltage with
increasing ripple in the output current).
The selection is valid only if the DC link voltage is not compensated in the CU (Bit 1 = 0).
Bit 1 = 0:
DC link voltage compensation in the modulator.
Bit 1 = 1:
DC link voltage compensation in the closed-loop current control (CU)
This bit can be set only in conjunction with a pulse inhibit and when r0192 bit 14 = 1 (DC
link voltage can be compensated in the power unit).
Basic functions
6.6 Pulse frequency wobbling
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