Calculation of Synchronous Torques and Radial Magnetic Forces for Pole-Changing Winding Using the 3//Y / 3//Y Method

The harmonics that appear in the squirrel cage asynchronous machine have been discussed in great detail in the literature for a long time. However, the systematization of the phenomenon is still pending, so we made an attempt to fill this gap in the previous parts of our study by elaborating formulas for calculation of parasitic torques. It was a general demand among those who work in this field towards the author to verify his formulas with measurements. In the literature, it seems, only one detailed, purposeful series of measurements has been published so far, the purpose of which was to investigate the effect of the number of rotor slots on the torque-speed characteristic curve of the machine. The main goal of this study is to verify the correctness of the formulas by comparing them with the referred series of measurements. Relying on this, the expected synchronous parasitic torques were developed for the frequently used rotor slot numbersas a design guide for the engineer. Thus, together with our complete table for radial magnetic pull published in our previous work, the designer has all the principles, data and formulas available for the right number of rotor slots for his given machine and for the drive system. This brings this series of papers to an end.

“…Order of harmonics per definition: Va=6g1+I µa=eZ2/p+va=e•2mq~+va vb= 6g2 +I The formula is see [1] (13):…”

Section: A Calculation Of Synchronous Parasitic Torquesmentioning

confidence: 99%

Section: G Examination Of Allowed and Not Allowed Or Forbidden Slot N...mentioning

confidence: 99%

Harmonics in the Squirrel Cage Induction Motor Analytic Calculation Part III: Influence on the Torque-speed Characteristic

Kovács

2024

“…μ0 permeability of vacuum δ' equivalent air-gap N1 stator turn number τp circumferential dimension of a pole li equivalent length of stator iron core Synchronous torque relative to breakdown torque of the machine [1] (4)…”

Section: A Calculation Of Synchronous Parasitic Torquesmentioning

confidence: 99%

“…The issue has been discussed in detail in [1], but without attenuation. The essence and the final result will be repeated, and then the effect of attenuation will be considered.…”

Section: A Calculation Of Radial Magnetic Forcesmentioning

confidence: 99%

Harmonics in the Squirrel Cage Induction Motor, Analytic Calculation Part II: Synchronous Parasitic Torques, Radial Magnetic Forces

Kovács¹

2023

The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field, as well as the synchronous parasitic torques, radial magnetic forces have been discussed in great detail in the literature, but always separately, for a long time. However, systematization of the phenomenon still awaits. Therefore, it is worth summarizing the completeness of the phenomena in a single study -with a new approach at the same time -in order to reveal the relationships between them. The role of rotor slot number is emphasized much more than before. New formulas derived for both synchronous torques and radial magnetic forces are used for further investigation. It will be shown that both phenomena in subject must be treated together. Formulas will be provided to take into account attenuation. Design guide will be provided to avoid dangerous rotor slot numbers. It will be shown that the generation of synchronous torques and radial magnetic forces do not depend -in this new approach -on the slot combination, but on the rotor slot number itself.

“…The article is a continuation of the Author's previous works [1], [2]. Those articles were developed mainly based on [3] as a very basic work.…”

Section: Introductionmentioning

confidence: 99%

Harmonics in the Squirrel Cage Induction Motor Analytic Calculation - Part I: Differential Leakage, Attenuation, Asynchronous Parasitic Torques

Kovács¹

2023

The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field, as well as the related differential leakage, attenuation, asynchronous parasitic torques have been discussed in great detail in the literature, but always separately, for a long time. However, systematization of the phenomenon still awaits. Therefore, it is worth summarizing the completeness of the phenomena in a single study -with a new approach at the same time -in order to reveal the relationships between them. The role of rotor slot number is emphasized much more than before. An existing, commonly used, but still impractical basic figure has been modified to more clearly demonstrate the response of the rotor for the harmonics of the stator. The need to treat differential leakage, asynchronous parasitic torques and attenuation together will be demonstrated: new formula for asynchronous parasitic torque is derived; the long-used characteristic curves for differential leakage and attenuation used separately so far was merged into one, correct curve in order to provide a correct design guide for the engineers.