Flux Braking - ABB ACS880 Firmware Manual

The standstill modes can be used if the motor cannot be turned (for example, when
the load is connected). As the characteristics of motors and loads differ, testing must
be done to find out the most suitable standstill mode.
A rotor position offset used in motor control can also be given by the user. See
parameter 98.15 Position offset
The drive is capable of determining the rotor position when started to a running motor
in open-loop or closed-loop modes. In this situation, the setting of
mode has no effect.
Settings
Parameters 21.13 Autophasing mode
220) and 99.13 Identification run request


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
speed
Flux braking
The drive monitors the motor status continuously, also during flux braking. Therefore,
flux braking can be used both for stopping the motor and for changing the speed. The
other benefits of flux braking are:
• The braking starts immediately after a stop command is given. The function does
not need to wait for the flux reduction before it can start the braking.
• The cooling of the induction motor is efficient. The stator current of the motor
increases during flux braking, not the rotor current. The stator cools much more
efficiently than the rotor.
• Flux braking can be used with induction motors and permanent magnet
synchronous motors.
Two braking power levels are available:
• Moderate braking provides faster deceleration compared to a situation where flux
braking is disabled. The flux level of the motor is limited to prevent excessive
heating of the motor.
user.
(page 112),
No flux braking
t (s)
98.15 Position offset user
(page 222).
T
Br
(%)
T
N
60
40
Flux braking
20
No flux braking
Program features 35
21.13 Autophasing
(page
T = Braking torque
Br
T = 100 Nm
N
f (Hz)