Lust CDA3000 - 69 PM-Modulation

Application Manual CDA3000
5-129
5 Software functions
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5.5.12 _69 PM-
Modulation
As the switching frequency (modulation frequency) increases the power
loss of the inverter module also increases. The reason for this lies in the
common losses in the switching of power semiconductors in the power
stage. This necessitates a reduction in the power of the inverter module in
order to prevent the device from overheating. The power rating is also
influenced by the motor cable length, the ambient temperature and the
mounting height.
Minimum switching frequency of power stage for very smooth
running of the motor
Rule of thumb: The modulation frequency should be 8 to 10 times the
maximum output frequency of the inverter.
Parameters of the modulation frequency
Function Effect
• Setting of switching
frequency of inverter power
stage
The higher the switching
frequency,
• the lower the noise,
• the smoother the motor runs
at high speed and
• the lower the output power of
the inverter module.
Switching frequency of power stage Output frequency of inverter
4 kHz to 400 Hz
8 kHz to 800 Hz
16 kHz to 1600 Hz
Table 5.83 Minimum switching frequency for adequately smooth running
of the motor
Parameter Function Value range FS Unit Online
690-PMFS Switching frequency of power stage 4, 8, 16
dependent
on device
kHz
Table 5.84 Parameters from subject area _69PM Modulation