Program features 51
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 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 Vector control, no IR compensation is possible or needed as it is applied
automatically.
Settings
• Parameters 19.20 Scalar control reference unit (page 134), 97.12 IR comp step-
up frequency (page 429), 97.13 IR compensation (page 303) and 99.04 Motor
control mode (page 305)
• Parameter group 28 Frequency reference chain (page 186).
Flux braking
The drive can provide greater deceleration by raising the level of magnetization in the
motor. By increasing the motor flux, the energy generated by the motor during
braking can be converted to motor thermal energy.
Motor voltage
f (Hz)
IR compensation
No compensation
T
Br
T
N
20
40
60
(%)
Motor
speed
No flux braking
Flux braking
T
Br
= Braking torque
T
N
= 100 Nm
Flux braking
No flux braking
t (s)
f (Hz)
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