ABB ACS880 N5700 Series, Firmware Manual, Page: 92 / 662

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Flux braking
WARNING!
The motor needs to be rated to absorb the thermal energy generated by 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
T
Br
/ T
N
(%)
No flux braking
Flux braking
t(s)
f (Hz)
Flux braking
No flux braking
60
40
20
T
Br
= Braking torque
T
N
= 100 Nm
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.
• Full braking exploits almost all available current to convert the mechanical
braking energy to motor thermal energy. Braking time is shorter compared to
moderate braking. In cyclic use, motor heating may be significant.
Settings and diagnostics
Parameter: 97.5 Flux braking (page 528) .
92 Program features