1,720,971 research outputs found
Magnetic gears numerical modelling and optimization
Full text linkThe main focus of this thesis is to provide efficient modelling and optimization strategies for a certain electro-magnetic device known as magnetic gear. In particular, magnetic, thermal and mechanical models are discussed and the non-linear material models are examined, including permanent magnets demagnetization algorithms and hysteresis models in laminated sheets. From the magnetic modelling point of view, an analytic approach for the initial simplified gear design is presented. A special focus is given to the computational burden of the method that is especially tailored for stochastic optimization procedures. For the detailed analysis of magnetic gears, an algorithm based on Finite Element / Boundary Element coupling is proposed, including ferromagnetic non-linearities, mechanical ordinary differential equations, eddy currents and circuit equations. Detailed models are introduced and discussed to analyze the effects of soft material hysteresis and permanent magnets magnetization, demagnetization and recoil. Loss mechanisms in magnetic gears are also investigated, and the transmission losses at varying rotational speeds and load angles are analyzed. A simplified mechanical model of the magnetic gear is presented and formulated as a set of inequality constraints, thus giving a direct link to optimization strategies. The mechanical constraints include the iron poles displacements and stresses and the limitations on the rotational speed due to excessive stresses, resonances and vibrations. A simplified analysis based on an equivalent thermal network is also presented, where the axial cooling flux is also considered. Stochastic optimization techniques are discussed for a multi-physic optimized machine design, and the analytic model is embedded in a Differential Evolution scheme. Finally, the optimized results are discussed and compared to commercial mechanical gearboxes. A solution based on the stiffness rods connection is also proposed and analyzed to provide a damping effect when the gear operation becomes asynchronous. During the PhD, there has been a constant effort aimed at building a prototype for the validation of the numerical models but, for different reasons, none of the manufacturers finalized the project. Thus, all the algorithms have been validated by comparing their output with commercial codes or, when possible, with data from experiments retrieved from literature. Because of this reasons and since the major objective of this thesis regards the numerical techniques for magnetic gears simulation, different magnetic transmissions have been adopted as numerical test cases for the validation of the algorithms
Multi-objective optimization of coaxial magnetic gears
No full textIn this paper multi-objective optimization techniques are applied to the design of magnetic gears in order to maximize the performances and to obtain a competitive device. A parallelized stochastic algorithm is implemented and an analytical tool based on magnetic fields computation and losses estimation is used to compute the multi-objective function. This FEM-free computational model can be used in the initial stages of product development
An optimization tool for coaxial magnetic gears
No full text
Purpose
This paper aims to show a complete optimization tool that can be used for the design of coaxial magnetic gears. In the first part, the paper deals with the semi-analytic modelling of these machines and also discusses how to reduce the computational efforts. In the second part, an optimization algorithm is adopted for finding the Pareto optimal geometries.
Design/methodology/approach
The machine is subdivided into a set of domains according to their physical and geometrical properties, and the potential distribution is found semi-analytically in them under some simplifying hypothesis. A loss estimation is performed for both ferromagnetic and permanent magnet regions. A stochastic differential evolution (DE) algorithm for multi-objective constrained problems is then applied.
Findings
It is shown that the presented design tool gives results in accordance to finite element method (FEM)-based analysis keeping the advantages of robustness and simplicity of the analytical methods. The DE-based strategy performs well on the magnetic gear optimization problem.
Practical implications
The proposed tool appears to be a good starting point when designing coaxial magnetic gears. The optimal Pareto points can be used as initial seeds of FEM-based optimizations, resulting in a cheaper computational method with respect to a full FEM optimization.
Originality/value
This paper takes inspiration from recent works on magnetic gear modelling and completes the design procedure with a suitable efficiency estimation. The paper also shows how to use mature optimization strategies to solve the constrained multi-objective magnetic gear design problem.
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DIFFERENTIAL AND VEHICLE COMPRISING SUCH DIFFERENTIAL
No full textA differential (12) comprises two magnetic gears (20, 30) each comprising an internal rotor (22, 32), an external rotor (24, 34), and a rotor of the ferromagnetic poles (26, 36) interposed between the internal rotor ( 22, 32) and the external rotor (24,34). The internal rotor (22, 32), the external rotor (24, 34) and the ferromagnetic pole rotor (26, 36) are coaxial and suitable to rotate about a gear axis (28, 38). The internal rotors (22, 32) are suitable to be connected to a drive (40), to be placed in rotation about the respective gear axis (26, 36) by the drive motor (40) itself. The external rotors (24, 34) are suitable to be connected to respective output semi-axes (25, 35) to place them in rotation or are connected to adjustment means (50) suitable to adjust their rotation speed. In the event that the external rotors (24, 34) are suitable to be connected to respective output semi-axes (25, 35) for placing them in rotation, the rotors of the ferromagnetic poles (26, 36) are connected to adjustment means (50) suitable to adjust the rotation speed of the rotors of the ferromagnetic poles (26, 36). In the event that the external rotors (24, 34) are connected to the adjustment means (50) suitable for adjusting their rotation speed, the rotors of the ferromagnetic poles are suitable to be connected to respective output semi-axes (25, 35) to place them in rotatio
A flexible power electronics configuration for coupling renewable energy sources
Full text linkA combination of series, parallel and multilevel power electronics has been investigated as a potential interface for two different types of renewable energy sources and in order to reach higher power levels. Renewable energy sources are typically dispersed in a territory, and sources, like wind and solar, allow small to medium-scale generation of electricity. The configuration investigated in this article aims at adapting the coupling solution to the specific generation characteristics of the renewable energy source to make it fit the electrical network. The configuration consists of a combination of three-phase multilevel converters and single-phase inverters, which are designed to provide flexibility, high power quality and high efficiency. A detailed analysis and simulation is performed to identify the properties in conjunction with the electrical grid requirements and the potential challenges encountered during operation. An optimized operation example of wind generation combined with solar PV generation is presented to exemplify the flexibility and benefits of the proposed configuration
Parametric Design and Optimization of Magnetic Gears with Differential Evolution Method
No full textRecently, magnetic gears have drawn wide attention due to their inherit merits, such as high torque density and overload protection. In this paper, an analytical calculation based on MMF-permeance theory is adopted to analyze the modulation effect in magnetic gear. After that, an automatic drawing procedure is built to rapidly analyze the parameters. The effects of some key parameters on magnetic gear performance are investigated, including air slot opening to pole pitch ratio c0, magnet-arc to PM pole pitch ratio and PM thickness hm. In particular, three types of steel pole-pieces are considered, which are radial slots, parallel teeth and parallel slots. At last, a global optimization design is carried out by using differential evolution algorithm, and some useful suggestions are given for the design and optimization of coaxial magnetic gear
Magnetic transmission gear finite element simulation with iron pole hysteresis
No full textAbstract
Ferromagnetic poles in a magnetic transmission gear require particular attention during their design process. Usually, during the numerical simulation of these devices the effects of hysteresis for loss estimation are neglected and considered only during post-processing calculations. Since the literature lacks hysteresis models, this paper adopts a homogenized hysteretic model able to include eddy current and hysteresis losses in 2D laminated materials for iron poles. In this article the results related to the hysteresis in a magnetic gear are presented and compared to the non-hysteretic approach.</jats:p
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