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6F3A4768
5.5 Optional Function According to Application (TMdrive-30)
5.5.1 Auto Field Weakening Control
Operation shown in Fig. 5.5.1 a) to make the magnetic flux constant is used for general operation method of the
induction motor. In TMdrive-30, operation is performed with the magnetic flux and ID_REF made constant. At
this time, the induced voltage is calculated by multiplying the speed by the magnetic flux. The voltage is then
increased in proportion to the speed.
In the auto field weakening control, when operating at a higher speed, the induced voltage is controlled at a
constant level based on the magnetic flux reference in inverse proportion to the speed feed back after the
voltage has reached the rated voltage.
If the speed exceeds the start speed of the field weakening control, the induced voltage becomes constant and
the motor output shows the constant output characteristics. (Fig. 5.5.1 b))
V, f
Speed
Magnetic flux
Speed
V, f
Speed
Magnetic flux
Speed
V
f
V,f
a) Constant magnetic flux b) Field weakening control
Fig. 5.5.1 Field Weakening Control Characteristics
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