Dc Voltage Control; Overvoltage Control; Undervoltage Control (Power Loss Ride-Through) - ABB ACQ580 Firmware Manual

80 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.


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.
T f U
out
M DC
(N·m) (Hz) (Vdc)
160 80 520
120 60 390
80 40 260
40 20 130
U = Intermediate circuit voltage of the drive, f
DC
T = Motor torque
M
Loss of supply voltage at nominal load (f
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.
1.6 5.8
= 40 Hz). The intermediate circuit DC voltage
out
8 11.2
= Output frequency of the drive,
out
U
input power
U
DC
f
out
T
M
t (s)
15.4