Corrected from:
Inverter Drives 8400 StateLine, HighLine, and TopLine from firmware version 14.00.00.00
Response of the new version?
Via C2864/1 bit 0, the negative response in the case of a warm ASM and a cold PSM can be improved by setting a warm machine here (motor temperature 90°C).
Which products are affected?
Inverter Drives 8400 StateLine, HighLine, and TopLine with a firmware version lower than 14.00.00.00
What happens?
The torque at the motor shaft does not comply with the torque that is expected and shown in the inverter. If an asynchronous motor is used, the real torque is too low and in the case of synchronous motors it is too high when the motor has warmed up.
When does the problem occur?
The response in particular clearly shows in applications with a torque control.
If the motor winding temperature is not fed back to the controller (no KTY evaluation), the torque in the motor control is calculated with a constant value for the rotor resistance. For an ASM, a rotor resistance at 20°C, and for a SM, a rotor resistance at 150°C is assumed.
The greater the deviation of the real motor temperature compared to these assumed values, the greater the torque errors.
Short-term measures/recommendations?
None. In applications with torque control, a temperature feedback should always be used.
Evaluation:
In applications with torque control, the deviation has a direct impact on the process factors such as the web tension of winding drives. In speed-based applications, torques are not fed forward in an ideal fashion and are displayed incorrectly.
Speed or position setpoints are correctly approached nevertheless.
In applications with a motor encoder, typically also a thermal sensor is evaluated, except for HTL encoders.
