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In early papers about Permanent Magnet Synchronous Machines (PMSMs) it was often stated that there are no rotor losses in PMSMs. Later, eddy current analyses for sintered permanent magnets (PMs) have been dominating the rotor loss analyses. However, in some designs also hysteresis losses can be possible in PMs. This paper uses 2D Finite Element Method (FEM) program and 2D slotless analytical model...
It is well known that the magnetic properties of a stator core in a rotating machine such as an induction motor are influenced by residual stress and external force. Residual stress is generated during manufacturing processes such as punch, laminate, and shrink fit processes. Magnetic properties such as iron loss of the stator core increases dramatically during the punching process and the shrink...
An accurate estimation of losses becomes more and more important in the design process of permanent-magnet (PM) synchronous machines (PMSM). This estimation is also a key issue of thermal design. Therefore, the study of losses (in particular non-conventional losses) is of great importance. In this paper, the authors present a calculation of the stator, rotor and PMs losses for different types of fed...
This paper investigates the voltage distribution in form wound windings of large electrical machines due to fast transient voltage steps, usually produced by (multi-level) voltage source inverters. Measurements are conducted on a stator core of a large prototype machine with voltage step rise times between 0.1 and 10 The measurement results of the voltage distribution in one phase string of the stator...
This paper presents an approach to the thermal design of an AC machine where the application requires a low-duty transient operation. To provide accurate temperature predictions the design process has been informed with experimental data from tests on a stator-winding sector (motorette). These have been shown to be a time and cost-effective means of calibrating the thermal model of a full machine...
In this paper, the design criteria and an extensive losses analysis of a novel High-Speed Permanent Magnet Synchronous Machine (HS-PMSM) is presented. The proposed machine topology has been designed for a Flywheel Energy Storage System (FESS) with the aim of optimizing the integration between the flywheel and the HS-PMSM rotor, minimizing the overall losses at the same time. Thus, the conceptual design...
In this paper, an interior permanent magnet synchronous machine with a damping coil in the rotor for improved self-sensing capabilities at low speed and standstill is evaluated. Methods for measuring the differential inductive and resistive anisotropies are discussed. The measured load characteristics of these anisotropies, the additional PR losses and the dynamic behaviour are analysed and discussed...
When using amorphous material in an electric motor, the losses are often higher than expected. This paper investigates the effect of cutting and annealing on the performance of amorphous material. The BH-curve and losses are compared before and after an annealing treatment. Furthermore, the properties are compared for material cut with a plate shear and cut by laser, followed by an annealing treatment...
A novel recycling strategy, direct reuse, for rare earth permanent magnets were investigated in this article. Direct reuse uses small, unit-cell (segmented) magnets to replace the normal solid pole configuration, which is not directly reusable due its unique shape and size. The unit-cell magnets are directly reusable due to their standard shape and size, and direct reuse effectively bypasses a number...
This paper aims to provide some useful instructions to electromagnetic design of high-speed permanentmagnet machines. In this paper, the electromagnetic design procedure is illustrated with a 2 poles 40,000 rpm prototype machine. In order to determine a rotor structure with good performance, rotor design including rotor structure, pole arc and magnetization direction of magnets are analyzed respectively...
In variable-speed pumped-storage power plants, a promising solution is to connect the synchronous hydro-generator to the grid via a full-rated frequency converter. In this case, the nominal frequency of the hydrogenerator can be chosen independently from the grid. The purpose of this paper is to investigate how the nominal frequency affects generator efficiency using the converter-fed synchronous...
This paper focuses on a thermal analysis of Direct Driven Hydraulics (DDH). DDH combines the benefits of electric and hydraulic technologies in a compact package with high power density, superior performance and increased controllability. It enables a reduction of hydraulic losses therefore achieves better fuel efficiency. The main advantages of the presented architecture compared to a conventional...
This paper details the design process of a high performance electrical machine with the objective of achieving US Department of Energy FreedomCar 2020 targets, namely meeting the high speed efficiency requirement without sacrificing performance elsewhere. The FreedomCar targets are detailed, with a short discussion of the challenges involved. All feasible machine topologies are considered, and qualitatively...
This paper demonstrates a workflow for multi-physical simulation and design optimization of electrical machines using open-source tools. The workflow demonstrates applicability of open-source tools for all steps of complex 3D Finite Element Method modelling of an electrical machine — geometry production, meshing, pre-processing, solving (even in massively parallel environment), and post-processing...
In this paper we propose an original technique based on the finite element method to couple electromagnetic and thermal homogenisation of multiturn windings. The model accurately accounts for skin and proximity effects considering the temperature dependence of electrical resistivity. We validate the approach by modelling a reference electrical machine open slot with representative boundary conditions...
Epoxy resin constitutes a vital insulating element for electrical machine insulation. The present paper deals with the phenomenon of flashover in nanocomposite epoxy resin (with TiO2 nanoparticles) under the influence of uniform electric fields. As is known, water droplets on insulating surfaces may cause dry zones, local discharges and eventually arcs. Several parameters, affecting the flashover...
This paper deals with the performance analysis of a high-speed (HS) permanent magnet (PM) machine for an automotive application. Electromagnetic performances in terms of torque, power and losses have been calculated. In order to reduce PM eddy-current losses, tangential and axial segmentation have been studied. Besides electromagnetic performances, the mechanical integrity of the rotor has been analyzed...
This paper presents the design optimization procedure of a high power-density, permanent magnet synchronous machine for industrial pump applications. The designed machine drives an electric, oil flooded pump. In order to achieve higher torque-density, a fractional slot machine (8 poles, 9 slots) with double layer (concentrated) winding has been selected after a preliminary trade-off study, which considered...
Removal of the gear-box from a conventional all-electric vehicle (EV) power-train and incorporating direct-drive topology is expected to improve motor-to-wheel efficiency. Firstly, this paper discusses the merits and challenges of a novel direct-drive scheme employing a single on-board motor in an EV. Thereafter, motor design targets established for such an application in a typical super-mini EV are...
This paper focuses on the improved thermal performance of electrical machines by increasing the conductor fill factor. A comparative design study of integrated starter generator (ISG) considering different pole/slot combinations and magnet topologies is used as a case study to fix slot dimensions. Compressed stator windings coupled with segmented stator structure are introduced to reduce copper losses...
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