Faulty DC-injection braking in case of ASM servo control. Configuration of DC-injection braking has now been improved (corrected from V1.6.3)

Corrected from:
- i700 servo inverter V01.06.03.9953

Response of the new version:
DC-injection braking is now also working in the 'Servo control - ASM' motor control mode.
The settings required to execute DC-injection braking instead of quick stop (QSP) as error response have been optimised. The functionality is now easier to understand and to use.

Now, DC-injection braking is activated as error response via the parameter 'Response to error' 0x605E = -2 (new selection).

The previous parameters for DC-injection braking 0x2B81 'Current at quick stop' and 0x2B82 'Active at quick stop' are now inoperable. To ensure that existing projects can be loaded without error message (compatibility), both parameters are, however, still available in the firmware. Since the parameters are no longer required for new projects, they are no longer visible in the PLC Designer.

 


What happens?
At the end of DC-injection braking, the motor continues to rotate, the motor does not come to standstill.
Cause: The selected DC-injection braking current (0x2B81) is injected correctly, but the rotating field is not stopped properly. To come to standstill, the rotating field angle would have to be 'frozen' to a fixed value. 

 

When does the problem occur?
The problem occurs under the following conditions:
  • 0x2C00 = 2: Servo control - ASM is set as motor control mode
  • 0x2B82 = 1: DC-injection braking active at quick stop
Which products are affected?
- i700 servo inverter ≤ V01.05.06.9665

Short-term measures/recommendations:
Do not use the DC-injection braking function for 'Servo control - ASM'. 

Evaluation:
DC-injection braking is mainly used for drives without feedback system in V/f characteristic control.
For fed back drives in the 'Servo control - ASM' motor control mode, in general, the quick stop function is used. Here, the DC-injection braking function is only useful in the rare case of an encoder failure.
 

URL for linking this AKB article: https://www.lenze.com/en-de/go/akb/201400234/1/
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