Resolver with pole pair number >= 2: Incorrect extrapolation of the detected position values (corrected from V01.08.00)
Corrected from:
Servo Inverter i950 FW: from V01.08.00
Response of the new version:
In the resolver evaluation, the number of resolver pole pairs is now correctly taken into account in the calculated compensation.
What happens?
When synchronous motors (SM) are operated, a misorientation of the magnetic field occurs as a function of the speed.
As a result, especially at high speeds in the corner speed range, the torque yield is lower and the current requirement of the motor is higher.
At low speeds, the effect of the misorientation is hardly noticeable.
The described misorientation is caused by the fact that the number of resolver pole pairs is incorrectly not taken into account in the resolver evaluation during the calculated compensation of the existing running time. Especially with synchronous motors, an exact orientation of the field is necessary in order to achieve the highest possible efficiency.
When does the behaviour occur?
Synchronous motor (SM) and
Resolver with number of pole pairs >= 2 (corresponds to number of poles >= 4).
Asynchronous motors (ASM) are less affected because they are partially compensated by the motor model.
If possible, use a standard resolver with pole pair number = 1 (2 poles).
The behaviour during operation of a synchronous motor (SM) can be improved manually under certain conditions:
If the SM is operated at a constant operating point (full torque and speed close to the corner speed) and the highest efficiency is to be achieved at this operating point, then the angular error described above can be corrected by manually adjusting the pole angle (+/- a few degrees!).
The adjustment must be carried out in small steps and with the necessary caution; there is a risk of the synchronous motor running away if incorrect entries are made.
