ABB ACS280, Firmware Manual, Page: 69 / 430

Program features 69
DC voltage control

Overvoltage control
Overvoltage control of the intermediate DC link is typically needed when the
motor is in generating mode. The motor can generate when it decelerates or
when the load overhauls the motor shaft, causing the shaft to turn faster than
the applied speed or frequency. To prevent the DC voltage from exceeding the
overvoltage control limit, the overvoltage controller automatically decreases
the generating torque when the limit is reached. The overvoltage controller also
increases any programmed deceleration times if the limit is reached; to achieve
shorter deceleration times, a brake chopper and resistor may be required.
 Undervoltage control (power loss ride-through)
If the incoming supply voltage is cut off, the drive will continue to operate by
utilizing the kinetic energy of the rotating motor. The drive will be fully
operational as long as the motor rotates and generates energy to the drive. The
drive can continue operation after the break if the main contactor (if present)
remained closed.
Note: Units equipped with a main contactor must be equipped with a hold
circuit (e.g. UPS) to keep the contactor control circuit closed during a short
supply break.
130
260
390
520
1.6 5.8 8 11.2 15.4
t (s)
U
DC
f
out
T
M
U
DC
= Intermediate circuit voltage of the drive,
f
out
= Output frequency of the drive,
T
M
= Motor torque.
Loss of supply voltage at nominal load (
f
out
= 40 Hz). The intermediate circuit DC voltage drops to
the minimum limit. The controller keeps the voltage steady as long as the input power is switched
off. The drive runs the motor in generator mode. The motor speed falls but the drive is operational
as long as the motor has enough kinetic energy.
U
input power
20
40
60
80
40
80
120
160
T
M
(N·m)
f
out
(Hz)
U
DC
(Vdc)