A Dual-Consequent-Pole Vernier Memory Machine

This paper proposes a novel dual-consequent-pole Vernier memory machine (DCP-VMM) featuring alternatively arranged NdFeB and low coercive-force (LCF) magnet poles on the rotating and stationary sides, respectively. Due to the presence of LCF magnets that can be repetitively magnetized or demagnetized via a simple current pulse, the extra-high torque density at low-speed, and excellent high-efficient high-speed flux-weakening performance can be simultaneously realized. The configuration and operating principle, as well as the design considerations of the proposed machine are introduced, respectively. The finite element method (FEM) coupled with a nonlinear analytical hysteresis model for LCF magnets is employed to investigate the electromagnetic performance of the machine, which verifies the effectiveness of machine design and the feasibility as a competent candidate for automotive applications

Design and Analysis of Axial and Radial Flux Magnetic Gears and Magnetically Geared Machines

Over the last two decades, magnetic gears and magnetically geared machines gained interest as a promising technology for use in high torque, low speed applications. Magnetic gears accomplish the same task as mechanical gears, but they do so without mechanical contact between the moving components, instead relying on the modulated interaction between the flux generated by magnets on the rotors. Consequently, magnetic gears offer the potential to combine the compact size and cost effectiveness of mechanically geared systems with the reliability and quieter operation of larger direct drive machines. This work focuses on the development of analysis and design techniques for axial and radial flux magnetic gears and magnetically geared machines. Prototypes of an axial flux magnetic gear, a new compact axial flux magnetically geared machine topology, and a large scale inner stator radial flux magnetically geared machine were constructed and tested to calibrate and validate the analysis tools and investigate the practical considerations associated with the technology. Despite conservative design practices, the largest of these machines achieved a torque density of 82.8 kN∙m/m^3. Additionally, a MATLAB-based infrastructure was developed for controlling various simulation models and analyzing their results. Specifically, parametric 2D and 3D finite element analysis (FEA) models were employed for most of the studies, including the designs of the magnetically geared machine prototypes. This system was also used to conduct other simulation studies focused on a plethora of critical design trends and multi-faceted characterizations of the technology’s potential. Spurred on by the long simulation times required for FEA models, the later stages of the study describe the development and evaluation of generalized, parametric 2D and 3D magnetic equivalent circuit (MEC) magnetic gear models. These MEC models proved extremely accurate, matching the torque predictions of corresponding FEA models with an average error of less than 2%. The MEC models also achieved simulation speeds up to 300 times faster than those of corresponding FEA models. Collectively, this work provides the tools and methodology for the systematic evaluation of radial and axial flux magnetic gears. It also characterizes design trends for both topologies and validates the results with experimental prototypes

Linear Permanent Magnet Vernier Generators for Wave Energy Applications: Analysis, Challenges, and Opportunities

© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).Harvesting energy from waves as a substantial resource of renewable energy has attracted much attention in recent years. Linear permanent magnet vernier generators (LPMVGs) have been widely adopted in wave energy applications to extract clean energy from oceans. Linear PM vernier machines perform based on the magnetic gearing effect, allowing them to offer high power/force density at low speeds. The outstanding feature of providing high power capability makes linear vernier generators more advantageous compared to linear PM synchronous counterparts used in wave energy conversion systems. Nevertheless, they inherently suffer from a poor power factor arising from their considerable leakage flux. Various structures and methods have been introduced to enhance their performance and improve their low power factor. In this work, a comparative study of different structures, distinguishable concepts, and operation principles of linear PM vernier machines is presented. Furthermore, recent advancements and innovative improvements have been investigated. They are categorized and evaluated to provide a comprehensive insight into the exploitation of linear vernier generators in wave energy extracting systems. Finally, some significant structures of linear PM vernier generators are modeled using two-dimensional finite element analysis (2D-FEA) to compare their electromagnetic characteristics and survey their performance.Peer reviewe

NASA SBIR abstracts of 1991 phase 1 projects

The objectives of 301 projects placed under contract by the Small Business Innovation Research (SBIR) program of the National Aeronautics and Space Administration (NASA) are described. These projects were selected competitively from among proposals submitted to NASA in response to the 1991 SBIR Program Solicitation. The basic document consists of edited, non-proprietary abstracts of the winning proposals submitted by small businesses. The abstracts are presented under the 15 technical topics within which Phase 1 proposals were solicited. Each project was assigned a sequential identifying number from 001 to 301, in order of its appearance in the body of the report. Appendixes to provide additional information about the SBIR program and permit cross-reference of the 1991 Phase 1 projects by company name, location by state, principal investigator, NASA Field Center responsible for management of each project, and NASA contract number are included

Magnetically Geared Electrical Machines

Considerable research efforts are being carried out worldwide to develop technologies which meet the increasing demand for the efficient utilisation of energy resources. Modern applications, such as renewable energy and electrical vehicles, place a premium on electro-mechanical energy conversion in a power dense and high efficiency manner. Magnetic gears (MG) and magnetically geared machines, offer an attractive alternative to existing systems which may favour the combination of a high speed electrical machine with a mechanical gearbox. This has led to the opportunity to use Pseudo Direct Drives (PDDs) and MGs to be developed for use on an industrial scale. Therefore, in this thesis techniques for facilitating the manufacture and robustness of PDDs are presented, for both radial and axial field topologies. This includes use of alternative windings and soft magnetic composites. PDDs and MGs has so far mainly been developed in the radial topology and little attention has been given to axial topologies. The pole piece (PP) rotor required for MG operation, represents the main difference between PDD/MG and a conventional electrical machine. As such the PP shape and supporting structures have been investigated both in terms of electromagnetic and mechanical performance. Furthermore, detailed electromagnetic and thermal design and analysis of an axial field PDD (AFPDD) with improved robustness was undertaken, and a prototype was manufactured to demonstrate the operation of the AFPDD and validate the predictions

Modulation transfer functions of A.C. servomechanism components

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Magnetic gears numerical modelling and optimization

The 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

Two-phase auto-piloted synchronous motors and actuators

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