I would like to get information about how the frequency domain equivalent circuit of 3-phase I.M are affected when the number of poles are changed by the ratio 2:1.
Hello! I'm interested in researches of induction motor electric drive and this question is obvious from the first sight. There is no direct link between pole pairs and parameters of equivalent circuit in steady state, while rotating emf depends on pole pair in transient modes. But this influence can be avoided by operating in synchronous frame. And in terms of equivalent circuit or performance of induction motor, changing of pole pairs lead to changing of no-load speed. But the more I think, the more I'm concerned if it is so obvious. It will be interesting to track another answers. Regards.
Hallo, change of the number of poles is carried out through changing the connections of the coil groups. The winding is wound fore the largest number of pole, therefore when its connections are changed to have the less number of poles, the winding pitch will be about 90 degree not 180, and it will be distributed in unusal manner. I believe that this will have an effect on the mag. reactance and the leakage reactance. The winding resistances may not be affected, but the core may be affected. This is my opinion, and I need references to calculate the changes.
Ok. I see the question clear now. I didn't get the core of this question initially. This question relates to theory of electric machines much more than of electric drives. Thank you for sharing!
Thank you Alexander, yes the question is related to theory and design of electrical machines.
Fundamentally, from a machine design perspective, the power output / power density of your machine are of critical interest. The motor speed 120f / p changes significant and consequently as the number of poles is changed. The per unit quantities such as slip remain unchanged since Ns also changes with a change in number of poles.Taking that as a reference, the frequency-dependent induction motor equivalent circuit parameters X will be significantly affected, but not R. Core losses (hysteresis especially) will decrease with decreasing frequency, etc. This should provide you with an analytical basis for thought.
Thanks Inno very much. If the generator is connected to the grid, its frequency will be constant having no effect on X. I want to investigate the effect of changing the connection of the wdg to have different number of poles on the leakage inductances and the magnetizing inductance.
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