ABB ACS880 - Brake Chopper; Settings and Diagnostics; DC Voltage Boost; Description of the DC Voltage Boost Function

￭ Brake chopper
A brake chopper can be used to handle the energy generated by a decelerating motor.
When the DC voltage rises high enough, the chopper connects the DC circuit to an
external brake resistor. The chopper operates on the pulse width modulation principle.
The brake chopper (43.6) can be enabled with the overvoltage controller (30.30) still
active. In such case, make sure the overvoltage controller limits are set high enough
not to limit before the full braking power is reached. This function in certain applications
avoids unnecessary overvoltage trip and implements a simpler control logic if the resistor
cannot absorb enough energy or when the resistor breaks during breaking.
Some ACS880 drives have an internal brake chopper as standard, some have a brake
chopper available as an internal or external option. See the appropriate hardware manual
or sales catalog.
The internal brake choppers of ACS880 drives start conducting when the DC link voltage
reaches 1.156 × U
DCmax
. 100% pulse width is reached at approximately 1.2 × U
DCmax
,
depending on supply voltage range – see table under Voltage control and trip limits
above. (U
DCmax
is the DC voltage corresponding to the maximum of the AC supply
voltage range.) For information on external brake choppers, refer to their documentation.
Note: For runtime braking, overvoltage control (parameter 30.30) needs to be disabled
for the chopper to operate.
Settings and diagnostics
Parameters: 1.11 DC voltage (page 136) and 30.30 Overvoltage control (page 326).
Parameter group: 43 Brake chopper (page 392).
￭ DC voltage boost
This section describes the use of the DC voltage boost function for the drives which has
separate IGBT supply unit control.
The DC voltage boost require drive derating. See hardware manual of the drive for
derating factors.
Description of the DC voltage boost function
The regenerative and ultra low harmonic drives can boost their DC link voltage. In other
words, they can increase the operating voltage of the DC link from its default value.
The user can take the DC voltage boost function in use by:
1.
Adjusting the user-defined DC voltage reference value (94.22) and
2.
Selecting the user-defined reference (94.22) as the source for the drive DC voltage
reference (94.21).
Benefits of the DC voltage boost function are:
84 Program features