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KEB COMBIVERT F4-F
8
Name: Basis
11.05.99
Chapter
Section
Page
Date
©
KEB Antriebstechnik, 1999
All Rights reserved
Functional Description
Motor Data and Controller Adjustment
6.5.9
Modulation Rate
(dS.12) and
Overmodulation
(dS.14)
6.5.10 Operating
Frequency (dS.13)
The operating frequency with which the power modules are clocked can be changed
in dependence on the application. The max. possible operating frequency as well as
the factory setting is defined by the used power stage. Effects and consequences of
the operating frequency are listed in the following table:
small operating frequency
- little inverter heating
- little leakage current
- little switching losses
- less radio interferences
- improved concentricity at small
speed
high operating frequency
- less noise development
- improved sine-wave simulation
- less motor losses
Representation of the modulation rate. Since the current control always requires a
voltage reserve in order to react to control deviations, the modulation rate should not
exceed static approx. 90…95 % (short-time peaks are not critical).
To judge the modulation rate at activated output voltage, the value of dS.10 must
correspond to the input voltage.
U
Output
»
dS.10 * dS.12/100
or at dS.10 = off
=>
U
Output
»
0,95 * U
Input
* dS.12/100
(The calculation of the output voltage applies only to modulation rate < 100 %)
Overmodulation and block modulation can be switched on/off with
dS.14
dS.14
Overmodulation
0
Over and block modulation switched off
1
Over and block modulation switched on (factory setting)
The operating frequency must be changed in „noP“ status.
dS.13
Function
0
8 kHz
1
16 kHz
A heat sink temperature dependent derating is realized with rated operating frequency
of 8 kHz and max. operating frequency of 16 kHz. Derating is only permissible for
short-time operating to protect the inverter against overheat.