In scalar control, some standard features are not available.
See also section Operating modes of the drive (page 42).
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
Settings and diagnostics
Parameters: 19.20 Scalar control reference unit (page 278), , and 99.4 Motor control
mode (page 621).
Parameter group: 28 Frequency reference chain (page 347).
￭
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. Hall sensors generate so-called
commutation pulses that change their state six times during one revolution, so it
102 Program features
To Next Page
Loading...
