Passive Magnetic Bearings

The 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

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

Numerical Comparison of the Polarization Curve Contributions and Simulation of Proton Exchange Membrane Fuel Cells

This paper addresses the review and the numerical comparison of different state-of-the-art methods for the steady-state calculation of the polarization curve in Proton Exchange Membrane Fuel Cells (PEMFCs). The main available methods to model the different losses contribution affecting the fuel cell output voltage are described, and their performances are compared in detail in order to draw important conclusions about the best-performing simulation model to implement. A sensitivity analysis of the polarization curve to different parameters is then performed, followed by the verification of the conclusions obtained in terms of best-performing method to compute the polarization curve in a dynamic scenario as well

Software-in-the-loop Simulation of a Test System for Automotive Electric Drives

The 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