Limiting The Maximum Dc Link Voltage - Siemens SINAMICS G110D Operating Instructions Manual

6.8.4

Limiting the maximum DC link voltage

How does the motor generate overvoltage?
An induction motor can operate as a generator if it is driven by the connected load, In this
case, the motor converts mechanical energy into electrical energy. The motor feeds the
regenerative energy back to the inverter.
As a consequence, the DC link voltage is increased. The inverter can only reduce the
increased DC link voltage if it is capable of regenerative feedback into the line supply or is
equipped with a braking resistor.
Without being capable of regenerating into the line supply, only extremely low or brief
regenerative loads – relative to the inverter power – are possible because the inverter may
be damaged if the DC link voltage reaches critical levels. Before the voltage can reach
critical levels, however, the inverter shuts down with the fault message "DC link overvoltage".
When the V
reaction to DC link overvoltage is within acceptable limits for their specific application.
Protecting the motor and inverter against overvoltage
The V
reaching critical levels.
The V
regenerative mode, e.g. in hoisting gear or when large flywheel masses are subject to
braking. For applications such as these, you must select an inverter that is equipped with a
braking resistor or that can feed energy back into the line supply.
Table 6- 35
Parameter
P0003 = 3
P1240 = ...
r1242
P1243 = ...
P1250 = ...
P1251 = ...
P1252 = ...
P1253 = ...
P1254 = ...
For more information about this function, see function diagram 4600 in the List Manual.
SINAMICS G110D
Operating Instructions, 07/2016, FW V3.63, A5E36768472B AB
controller is enabled, it is imperative that the user ensures that the Inverter
DC max
controller prevents – as far as is technically possible – the DC link voltage from
DCmax
controller is not suitable for applications in which the motor is permanently in the
DCmax
V controller parameters
DCmax
Description
User access level
3: Expert
Enables the V
DCmax
0: disables V
DCmax
1: Enables the V
Shows the value of the DC link voltage above which the V
Multiplier for the output of V
(scaling of the V
Proportional gain of the V
Integral time of the V
Derivative time of the V
Limits the output of the V
Activates or deactivates automatic detection of the switch-on levels of the V
controller
controller
controller (default setting)
controller
DCmax
controller
DCmax
controller output)
DCmax
controller
DCmax
controller
DCmax
controller
DCmax
controller
DCmax
Functions
6.8 Protection functions
controller is active
DCmax
DCmax
127