Gap Magnetic Flux Research Articles

Optimal Design of Line-Start Permanent Magnet Synchronous Motor Based on Magnetic Equivalent Parameters

This paper used a lumped magnetic parametric approach-based analytical technique to design the 7.5 kW, three-phase line start permanent magnet (LSPM) motor. In order to enhance the efficiency and power factor (PF) of the prototype LSPM machine, an optimized slot shape of rotor permanent magnet (PM) was selected. The lumped magnetic circuit model is developed to present the magnetic characteristics, and analytical expressions are derived under the open circuit condition. The impact of the design variables on the analytical model air gap flux density distribution and magnetic flux leakage is studied for the LSPM. The design variables have a significant influence on the steady-state performance characteristics of the LSPM motor. Therefore, to verify the output results of the purposed model, the two-dimensional finite element analysis (FEA) was evaluated for the numerical solution of the analytical model.

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

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.

Electromagnetic Characteristic Analysis and Optimization Design of a Novel HTS Coreless Induction Motor For High-Speed Operation

We develop a novel high-temperature superconducting (HTS) induction motor with saddle-shaped HTS armature windings, which adopts the structure with a coreless stator and a conventional squirrel-cage rotor that is aimed to lightweight and higher speed. In this paper, the saddle-shaped HTS armature windings is composed of three layers of coils, of which each layer is arranged in six along circumferential direction. Moreover, the detailed production method of the coil is illustrated. According to the electromagnetic field theory, the electromagnetic characteristic of the newly designed HTS coreless induction motor is investigated including the flux density distribution and the torque ripple under the condition of no-load and rated load. Then, based on the initial geometry model, the arrangement structure of the HTS coils is optimized and analyzed. By optimizing the rotation angle of the HTS coil layer along the circumferential direction, it is found that the magnetic field perpendicular to the tape surface in the optimized shape coils significantly decreases compared with that in the initial shape coils. In addition, it is also noticed that not only the torque ripple becomes smaller, but also the distortion of the air- gap magnetic flux density is improved. Finally, a satisfactory coils arrangement structure model is obtained, which is intended to be utilized for HTS coreless motor.

Computer Aided Design of New Type PMSM Based on ISAD

Integrated starter alternator damper (ISAD) system requires motor: high-efficient, high-power density, low-ripple torque. Halbach motor is a new type of PMSM: unique permanent magnet structure makes motor have a sinusoidal magnetic field, can increase magnetic flux density of air gap and decrease magnetic flux density of rotor, which could enhance the power density and efficiency of motor as well as reduce its size. Software of Halbach motor design is given, also with the finite element analysis software with ANSYS language. Experiment proves the advantage of Halbach motor in ISAD system.

Optimization of the magnetic circuit in the MFL inspection system for storage-tank floors

Magnetization is the key to inspection of a tank floor via the magnetic-flux-leakage (MFL) technique. In order to optimize the magnetic circuit of the MFL detector and obtain the best detection effects, the influences of the magnet size on the floor magnetization condition, the gap magnetic flux density, and the magnetic force were studied with the help of the finite element method (FEM) and the effects of some other parameters, such as the magnet pole spacing and pole-piece thickness, on the signal-to-noise ratio were analyzed. The simulation results indicate that variation of the magnet width affects the magnetization much more than variation of the magnet thickness and that the detector can reach a trade-off between the magnetization effects and the driving force when the magnet is about 30 mm thick and 40 mm wide. On condition that the floor has reached its magnetizing saturation, an increase in the magnet-pole spacing and the pole-piece thickness can improve the testing sensitivity and the signal-to-noise ratio.