Configuration
Parameter manual b maXX BM5800
Document No.: 5.16029.03 Baumüller Nürnberg GmbH
74
of 814
3.4
n The controller specifies an upper limit for the output frequency of 599 Hz so that the
900
Hz, which are technically possible, may not be reached (for details over this limit
refer to the relevant Baumüller sales department. Key word: Export limitation).
n The converter can generate output voltages with frequencies between f
max
and
599
Hz and the controller permits them. The quality of these voltages can't be guar-
anteed.
Change of the PWM frequency during operation
The parameter >130.15< can be changed during continuous operation by the user.
The purpose of the functionality "PWM switching" while using the Ixt model in the over-
load monitoring of the power unit, is to offer the option by switching to a lower PWM fre-
quency, that noise and the Ixt actual value of the power unit is reduced but not to use the
increased power unit peak current of a lower PWM frequency. The maximum total current
of the drive
Z19.6– (being dependent of the power unit peak current) is the standardized
value of several current parameters. A change during the running operation is not practi-
cal and not intended (the parameter is not cyclically writable).
However, there are a few limitations:
m For applications with high demands on the performance (e.g. synchronous operation)
the complexity of the controller setting with variable current controller band width would
be too high. For this reason the PWM switching in enabled operation is restricted to the
speed control and current control operating modes (see
Z109.2–).
m The current controller cycle time may not exceed the RT0 cycle time Z1.8–. The value
will not be accepted if this condition is violated by writing a PWM frequency during the
continuous operation.
m The power unit peak current Z6.25–, depending on the PWM frequency, limits the
maximum drive current Z19.6–. If a higher PWM frequency is entered at continuous
operation, it could happen that Z19.6– should be reduced. In this case the change of
the PWM frequency is rejected. However, the change is allowed in the inhibited state
and
Z19.6– is limited automatically.
m If the PWM frequency is changed in continuous operation with activated dead time
compensation (Dead time compensation factor
Z47.50– > 0%) the adaption of the
dead time compensation must be activated after the PWM frequency Z123.1– bit 3 = 1
and therefore the values of the dead time correction table Z123.15– should be mea-
sured in this mode.
m The switching of the PWM frequency in continuous operation isn't permitted for the
sensorless synchronous motor.
m The PWM frequency should not be changed during the flying restart of the sensorless
asynchronous motor.
The failures at the implementation of the PWM switching during the continuous operation
in the controller were minimized - however, with reference to control engineering, they
can't be excluded completely. Therefore this option is adequate for simple (not critical)
applications, only.
The instantaneous PWM frequency is displayed in the parameter "Instantaneous PWM
frequency" (
Z130.41–). It can deviate from the set PWM frequency >130.15<, if the safe-
ty function of the PU temperature mode "PWM reduction" is operated (see ZOverload
monitoring of the power unit– from page 709).
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