Autophasing - ABB ACS880 Firmware Manual

It is recommended to activate 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.
See also section Operating modes of the drive
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 break-away torque.
In Direct Torque Control (DTC), no IR
compensation is possible or needed as
it is applied automatically.
Settings
• Parameters 19.20 Scalar control reference unit
compensation (page 300) and
• Parameter group


Autophasing

Autophasing is an automatic measurement routine to determine the angular position
of the magnetic flux of a permanent magnet synchronous motor or the magnetic axis
of a synchronous reluctance motor. The motor control requires the absolute position
of the rotor flux in order to control motor torque accurately.
Sensors like absolute encoders and resolvers indicate the rotor position at all times
after the offset between the zero angle of rotor and that of the sensor has been
established. On the other hand, a standard pulse encoder determines the rotor
position when it rotates but the initial position is not known. However, a pulse encoder
can be used as an absolute encoder if it is equipped with Hall sensors, albeit with
coarse initial position accuracy. The Hall sensors generate so-called commutation
99.04 Motor control mode
28 Frequency reference chain
(page 22).
Motor voltage
IR compensation
No compensation
(page 142),
(page 303)
(page 182).
Program features 45
f (Hz)
97.13 IR