Influence of Skewed Squirrel Cage Rotor with Intermediate Ring on Magnetic Field of Air Gap in Induction Machine

Ferková, Želmíra; Kindl, Vladimir

doi:10.5755/j01.eie.23.1.17580

Cited by 5 publications

(4 citation statements)

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“…Third, as shown in (18), the winding factor considering straight rotor bars is still given by (22), hence the magnitude of ν-th harmonics can be calculated from fundamental harmonic using (23).…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, as shown in [18][19][20][21][22], the multiphase motors may be powered with additional time harmonics injected into the winding to decrease the input current (rms value) while keeping the same torque, which is particularly relevant to the traction battery applications.The main disadvantage lies in limited slots number available for given stator diameter, the greater number of phases, the lower the number of slots per pole per phase and consequently higher magnitudes of space harmonics. This may be even more problematic in case of outer-rotor machines with narrow-shaped slots.No matter what number of phases is considered, electric motors are always accompanied by non-linearities and parasitic effects, usually connected with harmonics [23][24][25][26], that cause ripple of the input current and the torque, produce noise and increase losses.These harmonics are often produced by dead times in pulse width modulation (PWM), supply voltage unbalance, magnetic circuit saturation, non-sinusoidal winding distribution, lamination slotting and some other non-linearities and asymmetries.According to the nature of their origin, we can classify these harmonics as time harmonics and space harmonics [27], while their mutual interaction cannot be neglected [28]. This study describes/recapitulates occurrence and behavior of time/space harmonics in multiphase induction machines.…”

mentioning

confidence: 99%

“…No matter what number of phases is considered, electric motors are always accompanied by non-linearities and parasitic effects, usually connected with harmonics [23][24][25][26], that cause ripple of the input current and the torque, produce noise and increase losses.…”

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confidence: 99%

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Review of Time and Space Harmonics in Multi-Phase Induction Machine

et al. 2020

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Modern multiphase electric machines take advantage of additional degrees of freedom for various purposes, including harmonic current injection to increase torque per ampere. This new approach introduces a non-sinusoidal air gap flux density distribution causing additional technical problems and so the conventional assumptions need to be revised. The paper presents a methodology for synthesis of air gap magnetic field generated by a symmetrically distributed multiphase windings including the rotor field reaction due to the machine’s load. The proposed method is suitable either for single-layer or double layer windings and can be adopted either for full-pitched or chorded winding including slots effects. The article analyses the air gap flux density harmonic content and formulates conclusions important to multiphase induction motors. It also discusses effects of time harmonic currents and illustrates the principle of changing number of pole-pairs typical for harmonic currents being injected to increase torque.

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Section: Discussionmentioning

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Review of Time and Space Harmonics in Multi-Phase Induction Machine

et al. 2020

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“…The internal shape of the rotor bars and their overall arrangement can also be very varied, e.g., single straight bars, skewed bars, and single or double cage rotors. The shape of arrowed rotor bars with a middle ring is also often found [10,11]. The rotor slots can be open, semi-closed, or fully closed [12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Utilization of Two Sensors in Offline Diagnosis of Squirrel-Cage Rotors of Asynchronous Motors

2021

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In the manufacture squirrel-cage rotors of asynchronous motors, a high standard of quality is required in every part of the production cycle. The die casting process usually creates porosity in the rotor bars. This most common defect in the rotor often remains hidden during the entire assembly of the machine and is usually only detected during final testing of the motor, i.e., at the end of the production process. This leads to unnecessary production costs. Therefore, the aim is to conduct a continuous control immediately after the rotor has been cast before further processing. In our paper, we are interested in selecting a suitable method of offline rotor diagnostics of an asynchronous motor that would be effective for these needs. In the first step, the selection of the method and its integration into the overall manufacturing process is carried out. The arrangement of the sensors and their calibration is then simulated on a 2D Finite Element Model of the rotor. The proposed offline measurement procedures and technologies are finally validated by testing measurements on a rotor that simulates the most frequently occurring faults. A test system is also developed that provides the operator continuous information about the running rotor measurements and makes it easier to evaluate the quality of the cast rotor by means of graphical visualization of the faults.

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