Diagnosis of the combined rotor faults using air gap magnetic flux density spectrum for an induction machine

In the linear and planar motors, the 1D Halbach magnet array is extensively used. The sinusoidal property of the magnetic field deteriorates by analyzing the magnetic field at a small air gap. Therefore, a new 1D Halbach magnet array is proposed, in which the permanent magnet with a curved surface is applied. Based on the superposition of principle and Fourier series, the magnetic flux density distribution is derived. The optimized curved surface is obtained and fitted by a polynomial. The sinusoidal magnetic field is verified by comparing it with the magnetic flux density of the finite element model. Through the analysis of different dimensions of the permanent magnet array, the optimization result has good applicability. The force ripple can be significantly reduced by the new magnet array. The effect on the mass and air gap is investigated compared with a conventional magnet array with rectangular permanent magnets. In conclusion, the new magnet array design has the scalability to be extended to various sizes of motor and is especially suitable for small air gap applications.

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DESIGN OF A SINGLE-PHASE RADIAL FLUX PERMANENT MAGNET GENERATOR WITH VARIATION OF THE STATOR DIAMETER

Jurnal Teknologi ◽

10.11113/jt.v81.12889 ◽

2019 ◽

Vol 81 (4) ◽

Author(s):

Hari Prasetijo ◽

Winasis Winasis ◽

Priswanto Priswanto ◽

Dadan Hermawan

Keyword(s):

Magnetic Flux ◽

Permanent Magnet ◽

Flux Density ◽

Single Phase ◽

Air Gap ◽

Wire Diameter ◽

Terminal Phase ◽

Magnetic Flux Density ◽

Phase Voltage ◽

Radial Flux

This study aims to observe the influence of the changing stator dimension on the air gap magnetic flux density (Bg) in the design of a single-phase radial flux permanent magnet generator (RFPMG). The changes in stator dimension were carried out by using three different wire diameters as stator wire, namely, AWG 14 (d = 1.63 mm), AWG 15 (d = 1.45 mm) and AWG 16 (d = 1.29 mm). The dimension of the width of the stator teeth (Wts) was fixed such that a larger stator wire diameter will require a larger stator outside diameter (Dso). By fixing the dimensions of the rotor, permanent magnet, air gap (lg) and stator inner diameter, the magnitude of the magnetic flux density in the air gap (Bg) can be determined. This flux density was used to calculate the phase back electromotive force (Eph). The terminal phase voltage (V∅) was determined after calculating the stator wire impedance (Z) with a constant current of 3.63 A. The study method was conducted by determining the design parameters, calculating the design variables, designing the generator dimensions using AutoCad and determining the magnetic flux density using FEMM simulation. The results show that the magnetic flux density in the air gap and the phase back emf Eph slightly decrease with increasing stator dimension because of increasing reluctance. However, the voltage drop is more dominant when the stator coil wire diameter is smaller. Thus, a larger diameter of the stator wire would allow terminal phase voltage (V∅) to become slightly larger. With a stator wire diameter of 1.29, 1.45 and 1.63 mm, the impedance values of the stator wire (Z) were 9.52746, 9.23581 and 9.06421 Ω and the terminal phase voltages (V∅) were 220.73, 221.57 and 222.80 V, respectively. Increasing the power capacity (S) in the RFPMG design by increasing the diameter (d) of the stator wire will cause a significant increase in the percentage of the stator maximum current carrying capacity wire but the decrease in stator wire impedance is not significant. Thus, it will reduce the phase terminal voltage (V∅) from its nominal value.

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Winding reconstruction based on magnetic flux density in air-gap of IM

2015 International Conference on Renewable Energy Research and Applications (ICRERA) ◽

10.1109/icrera.2015.7418718 ◽

2015 ◽

Author(s):

Radoslav Cipin ◽

Petr Prochazka ◽

Ivo Pazdera

Keyword(s):

Magnetic Flux ◽

Flux Density ◽

Air Gap ◽

Magnetic Flux Density

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Influence of slot geometry on air gap magnetic flux density of rotating machines

2016 IEEE 16th International Conference on Environment and Electrical Engineering (EEEIC) ◽

10.1109/eeeic.2016.7555712 ◽

2016 ◽

Author(s):

Rodrigo Alves de Lima ◽

A. C. Paulo Coimbra ◽

Tony Almeida ◽

Viviane Margarida Gomes ◽

Thiago Martins Pereira ◽

...

Keyword(s):

Magnetic Flux ◽

Flux Density ◽

Air Gap ◽

Magnetic Flux Density ◽

Rotating Machines

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Rotor Power Losses in Planar Radial Magnetic Bearings — Effects of Number of Stator Poles, Air Gap Thickness, and Magnetic Flux Density

Volume 5: Manufacturing Materials and Metallurgy; Ceramics; Structures and Dynamics; Controls, Diagnostics and Instrumentation; Education ◽

10.1115/98-gt-316 ◽

1998 ◽

Cited By ~ 7

Author(s):

P. E. Allaire ◽

M. E. F. Kasarda ◽

L. K. Fujita

Keyword(s):

Magnetic Flux ◽

Flux Density ◽

Eddy Current ◽

Power Loss ◽

Magnetic Bearing ◽

Air Gap ◽

Magnetic Bearings ◽

Magnetic Flux Density ◽

Power Losses ◽

Loss Mechanism

Rotor power losses in magnetic bearings cannot be accurately calculated at this time because of the complexity of the magnetic field distribution and several other effects. The losses are due to eddy currents, hysteresis, and windage. This paper presents measured results in radial magnetic bearing configurations with 8 pole and 16 pole stators and two laminated rotors. Two different air gaps were tested. The rotor power losses were determined by measuring the rundown speed of the rotor after the rotor was spun up to speeds of approximately 30,000 rpm, DN = 2,670,000 mm-rpm, in atmospheric air. The kinetic energy of the rotor is converted to heat by magnetic and air drag power loss mechanisms during the run down. Given past publications and the opinions of researchers in the field, the results were quite unexpected. The measured power losses were found to be nearly independent of the number of poles in the bearing. Also, the overall measured rotor power loss increased significantly as the magnetic flux density increased and also increased significantly as the air gap thickness decreased. A method of separating the hysteresis, eddy current and windage losses is presented. Eddy current effects were found to be the most important loss mechanism in the data analysis, for large clearance bearings. Hysteresis and windage effects did not change much from one configuration to the other.

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Distributed Magnetic Flux Density on the Cross-Section of a Transformer Core

Electronics ◽

10.3390/electronics8030297 ◽

2019 ◽

Vol 8 (3) ◽

pp. 297 ◽

Cited By ~ 1

Author(s):

Lingzhi Li ◽

Xuhao Du ◽

Jie Pan ◽

Adrian Keating ◽

David Matthews ◽

...

Keyword(s):

Magnetic Flux ◽

Flux Density ◽

Cross Section ◽

Air Gap ◽

Magnetic Flux Density ◽

The Core ◽

The Cross ◽

Flux Density Distribution ◽

Transformer Core ◽

The Relationship

In this paper, the magnetic flux density distribution on the cross-sections of a transformer core is studied. The core for this study consists of two identical U-shaped cores joint at their open surfaces with known air gaps. The magnetic flux density at one of their joint boundary surfaces was measured for different air gaps. A finite element model (FEM) was built to simulate the magnetic flux density and compared with experiment data. Using the validated FEM, the distributed magnetic flux density on the cross-section of the core structure can be obtained when the air gap approaches zero. An engineering model of the density based on the Ampere’s circuit law was also developed and used to explain the relationship between air gap and mean magnetic flux density on the cross-section. The magnetic flux density on the cross-section was found to have a convex-shaped distribution and could be described by an empirical formula. Using this approach, the magnetic flux density distribution in cores with different interlayer insulation was obtained and discussed. This method could also examine the leakage of magnetic flux density in the air gap region when the distance is non-zero, and the relationship between the leakage field and the field in the core structure. The proposed method and model can provide a more detailed understanding for the magnetic field of transformer cores and potential application in designing quiet transformers and condition monitoring.

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