Iron losses and rotor teeth number 1

[dazhoid]

Hi,

Is it possible to make a general rule on the evolution of the total iron losses of a squirrel-cage induction motor with its rotor teeth number Nr ?? (in two cases: 1-considering that the rotor slot shape remains unchanged, which makes the rotor teeth section decrease when Nr increases, and 2-considering that the rotor slots surface decreases when Nr is increased)

Thanks for your remarks.

 

[7anoter4]

Hi dazhoid,
The iron losses of an induction motor
are linked with the magnetization process
and consists of three parts. The so-called separation
of losses implies that the average power loss
per unit volume of any material is decomposed into
the sum of hysteresis and a dynamic contribution. For
several alloys and sinusoidal excitation with a given
frequency and magnetization the specific losses can
be appreciated from the manufacturer data.

The total iron losses depends also not only on rotor teeth flux density but on the total magnetic circuit[inductor armature teeth ,inductor yoke, rotor yoke]
We have to calculate a huge no. of flux density all around.
Also, there are a lot of harmonics of the magnetic field due to inductor current spreading and the induced reaction. They may interfere in a dangerous mode.
The are a lot of synchronous and asynchronous parasitic torques and also magnetic unilateral forces due to this interaction.
So ,we can not choose any number of slots .
There is, with respect to inductor number of slots[Z1], a discrete no. of permitted rotor slots[Z2]
There is some of the indications:
Z2<1.25*Z1 Z2<>Z1,Z1/2,2*Z1 Z2<>6*p*g

p=no. of pole pairs ; g any integer number

There are many differences if the slots are straight [parallel to the motor axis] or the are inclined.
As a conclusion I doubt if it is possible to find a coherent function.
Best regards

 

[electricpete]

great answer 7anoter4.

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[7anoter4]

Thank you,electricpete !