ABB ACS850-04 series, Firmware Manual

Page: 74 / 296

74 Program features
Scalar motor control
It is possible to select scalar control as the motor control method instead of Direct
Torque Control (DTC). In scalar control mode, the drive is controlled with a frequency
reference. However, the outstanding performance of DTC is not achieved in scalar
control.
It is recommended to activate the scalar motor control mode in the following
situations:
• In multimotor drives: 1) if the load is not equally shared between the motors, 2) if
the motors are of different sizes, or 3) if the motors are going to be changed after
motor identification (ID run)
• 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.
In scalar control, some standard features are not available.
„
IR compensation for a scalar controlled drive
IR compensation is active 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 break-away torque.
In Direct Torque Control (DTC), no IR
compensation is possible or needed.
Signal supervision
Three signals can be selected to be supervised by this function. Whenever the signal
exceeds (or falls below) a predefined limit, a bit of
06.13 Superv status is activated.
Absolute values can be used.
Settings
Parameter group 33 Supervision (page 183 ).
Speed controller tuning
The speed controller of the drive can be automatically adjusted using the autotune
function (parameter
23.20 PI tune mode ). Autotuning is based on the load and inertia
of the motor and the machine. It is, however, also possible to manually adjust the
controller gain, integration time and derivation time.
f (Hz)
Motor Voltage
No compensation
IR Compensation