
■
Scalar motor control
It is possible to select scalar control as the motor control method instead of DTC
(Direct Torque Control). In scalar control mode, the drive is controlled with a speed
reference. However, the outstanding performance of DTC is not achieved in scalar
control.
It is recommended to activate scalar motor control mode
•
if the nominal current of the motor is less than 1/6 of the nominal output
current of the drive
•
if the drive is used without a motor connected (for example, for test purposes)
•
if the drive runs a medium-voltage motor through a step-up transformer, or
•
in multimotor drives, if
•
the load is not equally shared between the motors,
•
the motors are of different sizes, or
•
the motors are going to be changed after motor identification (ID run)
In scalar control, some standard features are not available.
See also section
Operating modes of the drive (page 26)
.
IR compensation for scalar motor control
IR compensation (also known as voltage boost) is available only when the motor
control mode is scalar. When IR compensation is activated, the drive gives an extra
voltage boost to the motor at low speeds. IR compensation is useful in applications
that require a high breakaway torque. In step-up applications, voltage cannot be
fed through the transformer at 0 Hz, so an additional breakpoint is available for
defining the compensation near zero frequency.
In Direct Torque Control (DTC), no IR compensation is possible or needed as it is
applied automatically.
Motor voltage
f
(Hz)
IR compensation
No compensation
88 Program features
Содержание ACS880 N5700 Series
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