Permanent-Magnet Motors and Generators for Aircraft

Electric motors and generators that use permarotating machinery, but aspects of control and power conditioning are also considered. The discussion is structured around three basic areas: rotating machine design considerations presents various configuration and material options, generator applications provides insight into utilization areas and shows actual hardware and test results, and motor applications provides the same type of information for drive systems

POTENTIAL FOR RARE EARTH ELEMENT RESOURCE EFFICIENCY IMPROVEMENTS IN PERMANENT MAGNET MOTORS THROUGH AN EXTENSION OF THE ELECTRIC MOTOR PRODUCT GROUP REGULATION UNDER THE EU ECODESIGN DIRECTIVE

It has been proposed that the EU Ecodesign Directive can promote resource efficiency through relevant ecodesign requirements. This paper examines the potential for rare earth element (REE) resource efficiency improvements in the event the current regulation for electric motors under the Ecodesign Directive is to be extended to comprise REE-based permanent magnet motors. The research is based on literature studies, questionnaires and semi-structured interviews with representatives from industry and academia. It is found that standards addressing the design and use phase could yield highest resource efficiency improvements of REE in permanent magnet motors. Highly ranked are stricter EU energy efficiency ratings and design for dismantling if and when recycling of REE was to be commercialized

Field-weakening performance of interior permanent-magnet motors

Copyright © 2002 IEEEThis paper compares the field-weakening performance under rated and overload conditions of synchronous reluctance and interior permanent-magnet motors against that of a baseline 2.2-kW induction machine. Four prototype rotors based on axially laminated and multiple-barrier designs were built and tested in the same induction machine stator. Field-weakening performance was estimated based on 50-Hz load tests at reduced voltage. It was found that the performance of the axially laminated synchronous reluctance machine was comparable with the induction machine while the interior permanent-magnet motors offered significantly better output power above rated speed. The multiple-barrier interior permanent-magnet motor design gave the most promising field-weakening performance.Wen L. Soong and Nesimi Ertugru

Embedded finite-element solver for computation of brushless permanent-magnet motors

This paper describes the theory underlying the formulation of a “minimum set” of finite-element solutions to be used in the design and analysis of saturated brushless permanent-magnet motors. The choice of finite-element solutions is described in terms of key points on the flux–MMF diagram. When the diagram has a regular shape, a huge reduction in finite-element analysis is possible with no loss of accuracy. If the loop is irregular, many more solutions are needed. This paper describes an efficient technique in which a finite-element solver is associated with a classical $d$– $q$-axis circuit model in such a way that the number of finite-element solutions in one electrical half-cycle can be varied between 1 and 360. The finite-element process is used to determine not only the average torque but also the saturated inductances as the rotor rotates

Cycloconverter on the all-electric airplane

This paper discusses the application of a cycloconverter to a permanent magnet generator. Recent developments, advanced concepts, and advanced technology systems will be covered. Recent developments include permanent magnets, permanent magnet motors and generators, and power semiconductors

Prediction of the electromagnetic torque in synchronous machines through Maxwell stress harmonic filter (HFT) method

For the calculation of torque in synchronous motors a local method is analysed, based on the Maxwell stress theory and the filtered contributions due to the harmonics of the magnetic vector potential in the motor air-gap. By considering the space fundamental field only, the method can efficiently estimate the average synchronous torque for a variety or motor topologies, including concentrated winding designs. This approach employs an analytical filter for the Maxwell stress tensor and `frozen permeability' technique. The proposed method is validated by comparison with FE results for several synchronous motor types: interior permanent magnet motors, wound field motor, synchronous reluctance motor

Robust Non-Permanent Magnet Motors for Vehicle Propulsion

There has been growing interest in electrical machines that reduce or eliminate rare-earth material content. Traction applications are among the key applications where reducing cost and hence reduction or elimination of rare-earth materials is a key requirement. This paper will assess the potential of three non-permanent magnet options in the context of vehicle propulsion applications: 1) a conventional Switched Reluctance Machine (SRM), 2) a DC-biased Reluctance Machine (DCRM) and, 3) a Wound Field Flux Switching Machine (WFFSM). The three machines were designed to achieve the hybrid vehicle traction requirements of 55kW peak and 30kW continuous over a speed range going from 2800rpm to 14000rpm. Their performance will be compared and the key opportunities and challenges will be highlighted. Preliminary experimental results for the DCRM will be presented

Torque ripple minimization of doubly salient permanent-magnet motors

Due to the nature of salient poles in both the stator and rotor, the doubly salient permanent-magnet (DSPM) motor suffers from severe torque ripples. In this paper, the torque ripple of DSPM motors is analyzed, and the torque ripple factor is newly derived. A new approach, namely the conduction angle control, is proposed to minimize the torque ripple. Moreover, the genetic algorithm is employed to optimize the corresponding control angles. Computer simulation and experimental results are given to verify the proposed approach. © 2005 IEEE.published_or_final_versio

Axial-field permanent magnet motors for electric vehicles

The modelling of an anisotropic alnico magnet for the purpose of field computation involves assigning a value for the material's permeability in the transverse direction. This is generally based upon the preferred direction properties, being all that are easily available. By analyzing the rotation of intrinsic magnetization due to the self demagnetizing field, it is shown that the common assumptions relating the transverse to the preferred direction are not accurate. Transverse magnetization characteristics are needed, and these are given for Alnico 5, 5-7, and 8 magnets, yielding appropriate permeability values

Multipolar SPM machines for direct drive application: a comprehensive design approach

A closed-form, per-unit formulation is proposed, for the design of surface mounted permanent magnet motors with high number of poles. The model evaluates the shear stress, the power factor and the specific Joule loss as the indicators of the machine performance, and demonstrates that this is determined by the correct choice of a very limited set of key-geometrical parameters. The design criteria are described analytically and then applied to example designs, FEA validated. Distributed- and concentrated-winding configurations are considered. The conclusions of the paper are consistent with the literature and aim to give a roadmap for designers of PM machines in modern applications, such as wind power synchronous generator