Effects of dynamic eccentricity in Flux Switching Permanent Magnet machines

This paper investigates the effect of rotating eccentricity fault on a 10/12 Flux Switching Permanent Magnet (FSPM) machine. Main characteristics of the studied machine such as air-gap flux density, magnetic force between rotor and stator and torque profile are calculated by using finite element analysis (FEA) which is the most accurate numerical method. Furthermore, Fourier analysis is performed in order to study the impacts of rotating eccentricity faults on magnetic force and torque profiles. In addition, the results of Fourier analysis of the machine in healthy condition are compared with the machine with 40% rotating eccentricity. This studies shows that the eccentricity has significant effects on FSPM characteristics which shows the importance of investigating the fault. To the best awareness of the authors, the effects of the rotating eccentricity on FSPM machines have not been studied before

Static eccentricity fault detection in Flux Switching Permanent Magnet machines

This paper studies the effects of static eccentricity (SE) in Flux Switching Permanent Magnet (FSPM) Machines to propose a criterion for fault detection. SE is one of the most common mechanical faults in electrical machines on. In order to achieve this goal, the proposed machine is studied under different degrees of static eccentricity fault to analyze machine condition. Finite element modeling (FEM) as the most accurate numerical approach is used to obtain precise results. The magnetic flux distribution of rotor and stator are calculated. In addition, air-gap flux density as a parameter which has a direct impact on back-EMF is assessed by using finite element analysis (FEA). It is found that static eccentricity has noticeable influences on back-EMF of coils of the machine. Furthermore, Fourier analysis is performed in order to achieve appropriate index for the diagnosis process. The results are provided for the healthy machine and the machine with different values of SE and the proposed index has been derived for the fault detection process in the machine

Influence of field-dependent critical current on harmonic AC loss analysis in HTS coils for superconducting transformers supplying non-linear loads : harmonic analysis of HTS transformers

There are two main obstacles in front of the development of high temperature superconducting (HTS) technology for electric power network applications; tape price and cooling cost. In order to reduce cooling cost, it is vital to evaluate AC transport current loss of the tapes precisely and then reduce it by some design innovative approaches. In addition, AC transport current loss in HTS material is a critical design variable for large-scale power network applications such as HTS transformers, superconducting fault current limiters, and power cables, since they are continuously carrying the network/load current during their operating life. In existing power networks, harmonic production sources are commonly used and thus, currents are distorted. Therefore, the effect of nonsinusoidal current on the critical apparatus in the network such as transformer must be studied. In this paper, AC transport current loss of a single-turn 2G YBCO HTS coil was modeled and numerically calculated under nonsinusoidal transport current using finite element method. Furthermore, influence of dependency of critical current density to magnetic field on the AC transport current loss of HTS coil when carries distorted currents was considered. It was observed that nonsinusoidal current causes excessive losses in HTS coil. On the other hand, a case study on an HTS transformer supplying non-linear load was considered to study the loss increment as well as heat load change. It was observed that current harmonics increases the AC loss, and heat load of transformer and decreases the efficiency, consequently

Design of a New Structure Passive Magnetic Bearing With Radial Magnetization Using FEM

This paper investigates a new structure of passive magnetic bearings (PMB) that includes three ring shaped permanent magnets which can increase safety and accuracy in holding rotor in its correct position with greater force and stiffness amplitude. According to the axial symmetry around the z-axis in the structure of PMB, it is modeled using two-dimensional finite-element method (2D-FEM). Using this approximation, it becomes possible to calculate magnetic force and stiffness in the minimum computation time than three-dimensional finite-element method (3D-FEM). Sensitivity analysis is done to achieve the best configuration of new structure. Also it investigates prevalent structure of PMB that includes two ring shaped permanent magnets. A good comparison for the force and stiffness amplitude is done between previous structure and proposed structure by FEM. By considering force density as a reference, two structures are compared for the financial matters

An axial passive magnetic bearing using three PM rings

The results of numerical and experimental analysis of passive magnetic bearings are presented. The proposed structure is composed of three radially stacked ring‐shaped permanent magnets. The improvements of stiffness and load capacity are proven in comparison to the classical passive magnetic bearing composed of two rings. A preliminary sensitivity analysis is carried out by means of the 2‐dimensional finite element method (FEM) modelling, which is used to provide the initial points for the stochastic optimisation and also to define the best fitness and penalty functions. Finally, the 2‐dimensional FEM is used to compare the force density and the cost of the proposed structure to those of the classical passive magnetic bearing composed of two rings. The optimised structure was manufactured and validated by experimental measurements. The proposed passive magnetic bearing exerts greater axial force and stiffness than similar structures

A Novel Structure of Passive Magnetic Bearing With Axial Magnetization

This paper presents a new structure of passive magnetic bearings (PMB) using three ring shape permanent magnets that can increase safety and accuracy in holding rotor in its correct position with greater magnetic force and stiffness amplitude. According to the axial symmetry around the z-axis in the structure of PMB, it is modeled using two-dimensional finite-element method (2D-FEM). Use of this approximation it becomes possible to calculate magnetic force and stiffness in the least computation time. This model includes all magnetic and structural characteristics of PMB. A good comparison for the force and stiffness amplitude is done between previous structure and proposed structure by FEM. By considering force density as a reference, two structures are compared for the financial matters

Axial Flux Machine Using Passive Magnetic Bearing with Axial Magnetization

Decreasing the maintenance cost and power losses in Axial Flux Permanent Magnet machine using Passive Magnet Bearing instead of mechanical ball bearing is the purpose of this paper. Two structures of Passive Magnetic Bearing are applied, and the magnetic forces and stiffness are analyzed. The best structure is selected according to the safety, mechanical consistency and economical charges. A balance point is found where the magnetic force of Passive Magnetic Bearing and magnetic force between rotor and stator structure, neutralize each other. Also, magnetic forces are investigated according to the displacements of the middle ring in Passive Magnetic Bearing and according to different air gap width between rotor and stator in the motor. According to the symmetry of Axial Flux Permanent Magnet motor, the motor is modeled using three-dimensional finite-element method. On the other hand, based on the axial symmetry around z-axis in Passive Magnetic Bearing, the bearing is modeled using two-dimensional finite-element method. These simplifications will help the calculation of the magnetic force and stiffness in the least computation tim

Electromagnetic sizing of axial-field flux switching permanent magnet machine

This paper presents a general sizing procedure of axial-field flux switching permanent magnet (AF-FSPM) machine for various topologies. A comprehensive approach is used for design of AF-FSPM machine and the design flowchart is presented. A three phase, 12/10 single-stage AF-FSPM machine is designed and three dimensional finite element analyses are performed to validate the design procedure. The magnetic flux distribution, induced EMF, and cogging torque has been computed. It is found that the results confirm the presented procedure