Faulhaber 2232***BX4S series, Инструкция по эксплуатации

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Functional Description 4
Motor with SC speed controller 4.3
4.3.5 Technical information
I²t current limiting
The servomotor with integrated SC speed controller is equipped with current limiting which enables
certain motor protection to be achieved.
Peak current (I „
max
)
The current is limited to the peak current, provided that the thermal current model calculates a
non-critical temperature.
Continuous current (I
„
cont
)
If the thermal current model reaches a critical temperature, continuous current is switched to.
How the current limiting works:
When the motor starts, the peak current is preset as the set-point for the current controller. As the
load increases, the current in the motor constantly increases until it finally reaches the peak current.
The current controller then comes into operation and limits the current to this set-point.
A thermal current model operating in parallel calculates a model temperature from the actually
flowing current. If this model temperature exceeds a critical value, continuous current is switched to
and the motor current is regulated to this. Only when the load becomes so small that the tempera-
ture falls below the critical model temperature is peak current permitted again.
The following diagram symbolically shows how the current limiting functions by means of an envelo-
pe curve (I
Limitation
). The current may not rise above the values along this envelope curve.
The aim of this so-called I²t current limiting is not to heat the motor above the thermally allowable
temperature by selecting a suitable continuous current. On the other hand, a high load should be
temporarily possible in order to enable very dynamic movements.
I
I
cont
T
Model
I
Limitation
(envelope curve)
t
t
I
Motor
I
max
T
critical
Laod variation