PLI (at standstill): Current amplitude set higher for individual motor types, e.g. for M850 motors. (corrected from V01.08.00)

Corrected from:

Servo Inverter i950 FW: from V01.08.00

Response of the new version:

Commissioning function "PLI without movement":

The calculation of the width of the test pulses is now carried out taking into account the saturation characteristic, in a similar way to the servo control.

This now prevents the overcurrent monitoring from responding.

What happens?

Commissioning function "PLI without movement":

Depending on the parameterisation of the synchronous motor, the overcurrent monitoring may respond when the test pulses are output.

With the synchronous motors of the M850 series, the setting of parameter 0x2C01:3 is relatively large because this value is specified for operation in no-load operation (motor current approx. 0A). This increases the probability of the overcurrent threshold being reached.

Background:

The pulse widths of the test pulses are calculated via the current DC voltage in the DC link and the set stator inductance (0x2C01:3).

If the stator inductance is set too high, wider pulses result, which can cause the current to rise to the overcurrent threshold in unfavourable cases.

In normal operation in servo control, the product of stator inductance (0x2C01:3) and saturation characteristic (0x2C04) is always effective, whereby a balance is established.

This compensation does not yet take place in a similar way with the PLI function.

When does the behaviour occur?

Commissioning function to identify the pollage "PLI without movement" and
the stator inductance (0x2C01:3) of the synchronous motor is set too high.

Which products are affected?

Servo-Inverter i950 FW

Short-term measures / Evaluation / recommendations:

As a short-term remedy, the following can be done:

Reduce parameter 0x2C01:3 and
increase the entire characteristic curve in 0x2C04 to the same extent.
Example:
- Synchronous motor with stator inductance = 10mH and start of the saturation characteristic at 65%.
- The stator inductance can be lowered to 6.5 mH and in return all values of the saturation curve can be raised by a factor of 1 / 0.65 = 1.54.

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