ABB ACQ810, Firmware Manual

Page: 76 / 376

76 Program features
DC voltage control
„
Overvoltage control
Overvoltage control of the intermediate DC link is needed with two-quadrant line-side
converters when the motor operates within the generating quadrant. 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
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 the
operation after the break if the main contactor 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.
„
Voltage control and trip limits
The control and trip limits of the intermediate DC voltage regulator are relative either
to a supply voltage value provided by the user, or to an automatically-determined
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)