ABB ACS880-01 Series, Firmware Instructions

Page: 112 / 664

112 Program features
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 4.8 8 11.2 14.4
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 mains 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
mains
20
40
60
80
40
80
120
160
U
DC
(V DC)
f
out
(Hz)
T
M
(Nm)