This paper focuses on influence of design parameters of permanent magnet machines with concentrated windings on cogging torque, torque ripple and mean torque. An efficient approach is presented to estimate the magnet width and slot opening width for minimizing cogging torque and/or maximizing mean torque. Two-dimension nonlinear finite element analysis including rotor motion is used for the calculation. The torque is calculated using different methods: Maxwell's stress tensor and Virtual work method. Comparison of results between linear and nonlinear magnetic circuit show that the torque is sensitive with magnetic saturation. The maximum torque of the linear case is about 15% higher than for the magnetic saturation case. Linkage flux, internal voltage and mean electromagnetic torque calculation are verified by experiments with error margin smaller than 1%, 2% and 3% respectively.@en

The machine under study is a surface-mounted outer rotor permanent magnet (PM) synchronous machine with concentrated windings, which is integrated in a flywheel of a diesel engine. The main objective of this work is to build an accurate nonlinear transient finite element method (FEM) model coupling to circuit model and validate this experimentally. The FEM model is made by scripts, so it is very convenient to change design parameters of PM machine. This will help in design optimization of PM machines. A sample PM machine is investigated for validating no-load voltage, load voltage, electric current, electromagnetic torque, short circuit current and reactance of FEM model. Comparison of simulation and experimental results shows very good agreement with error margin smaller than 3%. Results show that the end effects of a PM machine with concentrated windings having large number of teeth and poles can be neglected, even when its diameter is larger than its length. Analysis of results during three-phase short circuit shows that armature current during short circuit is limited strongly by armature reaction in the d-axis direction, even though the winding resistance is much smaller than the reactance. It can be shown that a PM machine designed with reasonable reactance can avoid demagnetization due to three-phase short circuit.@en

This paper presents the design of an axial flux permanent magnet (AFPM) generator and comparison of cost and energy yield of this generator with an automotive alternator which was adapted for small wind turbine application. The designed AFPM generator is a double-sided (TORUS) machine with air gap winding having 3 coils per pole and one stator disk sandwiched between two external rotor disks. The second generator concept comprises an automotive alternator equipped with a gear system to increase the speed from turbine to alternator. The AFPM generator is directly connected to turbine while a belt drive is used to increase alternator speed to about 3000rpm. Comparison of the two generator systems is made using a 2.8kW, 310rpm wind turbine for a given wind climate. The two generator systems present attractive low-cost options for small scale wind power generation in moderate wind speed areas. Results show that although the automotive alternator concept is a cheaper solution with easily available components, the AFPM generator seems more attractive having high annual energy yield and efficiency.@en

This paper presents feasible options for generators in flywheel of diesel engine for small maritime application. An outer rotor permanent magnet (PM) machine with concentrated windings is preferred for this application since it has good integration in a flywheel, higher power density and efficiency than electrically excited synchronous generators, induction generators, etc. A nonlinear transient finite-element-method (FEM) model is developed to calculate iron losses. Afterwards, the model is used for optimal design of a neodymium PM generator improved in terms of power density. Magnet thickness of redesigned generator is only 2 mm, so it has less possibility to break during maintenance. The FEM model is validated by experiment. Results show good agreement.@en

The aim of this paper is to design and optimize portable axial flux permanent magnet (AFPM) machines for human power generation. To achieve greater portability of a generator, we focus on minimizing active mass of the generator. The generator required is to deliver 60 W at different rated speeds. AFPM generators with concentrated windings and airgap windings are chosen as a generator type. Expressions to decide basic dimensions and parameters of the generators are derived in the paper. Next, optimum design of those generators is done to find the dimensions and parameters minimizing active mass at different speeds and different efficiencies. Based on the results of the design, a generator with concentrated windings (723 g) is heavier than a generator with air-gap windings (TORUS machine, 375 g) at 4000 rpm and 90% efficiency. At 2000 rpm and 80 % efficiency, the generator with concentrated windings (367 g) is lighter than the generator with air-gap windings (419 g).

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This paper presents a review of concepts for harvesting power from human movement and comparison of three axial flux permanent magnet machine (AFPM) designs. Some schemes for human power generating systems have been presented and compared in order to choose the most suitable configuration for our application. From the concepts evaluated, choices were made based on project specifications in the design of three axial flux permanent magnet (AFPM) machines with an output of 60W at a rotational speed of 3000 rpm. Comparison of the three AFPM generators: singled-sided with distributed winding, single-sided with concentrated windings, and double-sided (TORUS) with air gap winding show that the AFPM with concentrated windings and the TORUS are attractive having low mass and low losses.@en

Abstract This paper discusses the possibilities of applying high temperature superconducting (HTS) synchronous motor to Superbus, an alternative and sustainable type of public transportation developed at TU Delft. Two important factors within the Superbus drive that influence the operating range are weight and efficiency: increasing the weight results in larger roll resistance while the better the efficiency the larger the range. HTS rotating machines offer several advantages such as weight reduction and increased efficiency which can be exploited for special applications such as Superbus, where weight and volume reduction is important. In order to highlight the design challenges and potentials achievable by using HTS motor in Superbus an overview of the different approaches in the design of HTS machines is presented. Different rotor and stator topologies available in literature are discussed and comparison is made with conventional machines. The losses expected from the HTS motor are presented in comparison with conventional machines. It is concluded that it seems possible to achieve a reduction in losses and volume of about half compared with conventional machines.@en