1,721,327 research outputs found
An axial passive magnetic bearing using three PM rings
No full textThe 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
Passive Magnetic Bearings
No full textThe analysis of the behaviour of Passive Magnetic Bearing in order to achieve an acceptable magnetic force and stiffness is an interesting topic for rotating systems. Numerical analysis, which is an effective method to investigate the structural parameters of PMB, is applied using Finite Element Method to the two-dimensional model of Passive Magnetic Bearing. Numerical analysis is benefecial to predict the performances of the bearing versus differernt changes in the dimensions of the PMB. An optimization through Genetic Algorithms is then performed.The data gathered from the numerical analysis are therefore transferred to the Genetic Algorithm to facilitate the definition of the fitness and penalty functions which will help a faster convergence to the objective function. Providing a method to improve the magnetic force and consequently the magnetic stiffness of Passive Magnetic Bearings is an important purpose of this chapter. Also, in order to compare Passive Magnetic Bearing with different dimensions, the force to cost ratio is proposed as an index considering magnetic force and economical factors. The Genetic Algorithm is a stochastic optimization method which can be applied to reach the best dimensions according to the considered objective functions
Effects of dynamic eccentricity in Flux Switching Permanent Magnet machines
Full text linkThis 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
Axial Flux Machine Using Passive Magnetic Bearing with Axial Magnetization
No full textDecreasing 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
Analytical and Multiphysics Approach to the Optimal Design of a 10-MW DFIG for Direct-Drive Wind Turbines
No full textElectromagnetic Design and Modeling of a Two-Phase Axial-Flux Printed Circuit Board Motor
No full textSize and cost reduction are among the main issues of electric motor design and fabrication. This paper proposes an original layout for an axial flux permanent-magnet motor with printed circuit board (PCB) winding. In contrast to other axial flux motors of the same type, which are generally made with a three-phase fractional slot winding, the proposed motor has a two-phase wave winding printed on either side of the PCB. This configuration allows increasing the number of pole pairs and the supply frequency so to reduce the stator and rotor core widths. The winding is also characterized by a large copper percentage on the board, which improves the torque density of the motor. The results of the mathematical analysis, of the numerical simulation and of the experiments are compared. A method for the computation of the phase inductances is also proposed and validated. The main dimensions of the magnets are optimized via the finite-element method. The experimental comparison shows the advantages of the proposed motor in comparison to the traditional shaded pole motor for household applications
A nonlinear optimal control approach for PM Linear Synchronous Motors
No full textPermanent Magnet Linear Synchronous Motors are of wide use in industry in applications where actuation through rotational motors and a gears-based transmission system can be costly and prone to failures. In this article, a nonlinear optimal (H-infinity) control method is proposed for Permanent Magnet Linear Synchronous Motors (PMLSM). The dynamic model of the Permanent Magnet Linear Synchronous Motor undergoes approximate linearization around a temporary operating point (equilibrium) which is recomputed at each iteration of the control method. The linearization procedure is based on first-order Taylor-series expansion and on the computation of the Jacobian matrices of the motor's model. For the approximately linearized model of the motor an H-infinity feedback controller is designed. This controller stands for the solution of the motor's optimal control problem under model uncertainty and external disturbances. The computation of the controller's feedback gain requires the solution of an algebraic Riccati equation, which is performed again at each time-step of the control algorithm. The stability properties of the control scheme are proven trough Lyapunov analysis. First, it is confirmed that the controller satisfies the H-infinity tracking performance criterion which ascertains its robustness. Moreover, it is proven that the control loop is globally asymptotically stable. Finally, to implement sensorless control of the motor the H-infinity Kalman Filter is used as a robust state estimator
Software-in-the-loop simulation of a test system for automotive electric drives
No full textThe Automotive market is rapidly changing, as the increasing attention to the engine emissions pushes car makers to use vehicles less dependent on gasoline and diesel fuel, resulting in lower operating costs and emissions. Today, electric vehicles seem to be the best answer to the market demand. In this scenario, electric drives for traction play a key role, thus the necessity to develop effective and flexible test systems, able to ensure performance, quality and safety. In this paper a new automotive electric drives test system is proposed. The test system for electric drives is based on an inverter controlled through a real-time platform in which the Electric Vehicle model is implemented. The inverter emulates the behaviour of the motor and load at the load drive terminals. This paper describes the architecture of the system and shows the real-time simulation results. Three control methods are used for the load drive and compared in the paper
Static eccentricity fault detection in Flux Switching Permanent Magnet machines
Full text linkThis 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
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