Search

The increase of power and speed requirement on the electric machine has imposed a concern on the high losses at high speed, especially on the winding AC losses. To deal with this, a flat rectangular wire is proposed to minimize the winding AC loss due to the skin effect and proximity effect. The impact of conventional circular wire strands on AC loss are analyzed and compared with the proposed flat rectangular wire configuration. Both open slot and semi-closed slot stator structures are evaluated. Finally, a 24 slots, 16 poles fractional slot concentrated winding (FSCW) permanent magnet (PM) synchronous machine prototype using flat rectangular wire and open slot stator is built to demonstrate the manufacturing of flat rectangular wire.

This work aims to study the design principle of hairpin winding topology with high parallel path numbers per phase. Hairpin winding offers the advantages of high slot fill factor and automated winding process, which promote its application in the traction motors. As the motor power and speed continuously going up, the large size of the conductors are prone to proximity loss and eddy current loss due to the non-uniform current distribution, and the series connected turn numbers per phase are limited by the DC voltage. Therefore, this work is to investigate the hairpin winding design approach with high parallel path numbers per phase to meet the voltage and current constraints, and to keep the front and back connections having equal coil length as much as possible, respectively. The effect of parallel path numbers on the AC loss will be analyzed using finite-element analysis. The impact of asymmetric conductor configurations has also been evaluated.

This paper presents a novel electric motor solution to tackle the increasing demand on the traction motor for electric vehicles. The proposed electric motor has a 24 slots 10 poles fractional slot two-slot pitch winding and a PM-assisted synchronous reluctance (PMaSynR) rotor with arc-shaped barriers. First, the winding layout will be introduced. Then, a comparison with other winding layouts will be detailed. The benefits of the proposed solution including low torque ripple and high reluctance torque capability will be demonstrated. All this confirms that it is a good trade-off solution for traction application.

In recent years, synchronous reluctance (Syn-Rel) machines are research hotspots in variable speed motor drives due to their robust rotor structure and wide constant power speed range (CPSR). More practically, when kVA limitation is considered, embedded permanent magnets (PMs) have been widely adopted in Syn-Rel rotors to further increase power density as well as power factor. In this paper, the authors have investigated the potential of PM-assisted Syn-Rel machine to be the next generation electrical propulsion motor topology for automotive application, with special attention put on a key geometric parameter, i.e., airgap length. In MTPA region, the influence of airgap length on different torque components has been analyzed in detail based on the frozen permeability method. In field weakening region, the variation trend of several key performance such as peak power, iron loss and torque ripple have been investigated along with airgap length. It is found that with specifically high level of electric and magnetic loading, there exists optimal value of airgap length to achieve high power density based on specific cooling and kVA limitation. Numerical FEA and experimental tests are associated to validate the conclusions.

This paper presents a five-phase permanent magnet (PM) vernier machine topology equipped with a two-slot pitch winding. The two-slot pitch winding provides a trade-off between fractional slots concentrated winding (FSCW) and integrated slot distributed winding (ISDW) PM vernier machines. First, the development and basic structure of the fivephase PM vernier machine with auxiliary teeth are depicted. Then, the PM vernier machine with proposed two-slot pitch fractional slot winding is explained. Finally, the five-phase PM vernier machines with conventional ISDW and FSCW configuration are analyzed and compared with the proposed PM vernier machines with two-slot pitch fractional slot winding. The benefits of introducing two-slot pitch windings are quantitatively analyzed and verified by finite-element analysis (FEA). This analysis confirms that a higher back EMF and torque density can be achieved in this topology while keeping a reasonable power factor.

The hierarchically structured zeolite with high surface area and a large number of mesoporosities has attracted tremendous attention. Particularly, the morphology and structural tailoring of a diverse mesoporous zeolite with a single template is regarded as a crucial step toward the realization of an environmentally friendly synthesis. Herein, crystalline silicoaluminophosphate (SAPO-5) of the AFI framework type with a bimodal pore system was hydrothermally synthesized using di-n-butylamine (DBA) as a single template. The structural and catalytic properties of the hierarchical SAPO-5 were extensively characterized and compared to those of a conventional SAPO-5 using triethylamine (TEA) as a template. After loading Pt nanoparticles by incipient wetness impregnation, due to the promoting effect of hierarchical SAPO-5 in which the reactant and product were rapidly contacted with the acidity sites and metal sites, the 0.5 wt% Pt/SAPO-5-1.0DBA catalyst exhibits an enhanced hydroisomerization performance, with heptane conversion of 76.1% and iso-C7 yields of 48.4%, compared to a conventional 0.5 wt% Pt/SAPO-5-1.0TEA catalyst. The crystallization evolution under a series of hydrothermal times was also studied here. More importantly, this green, sustainable and economical strategy will extend the application of the synthesis of a silicoaluminophosphate-based zeolite.

This paper presents a novel tubular flux-reversal transverse flux permanent magnet linear machine (FR-TFPMLM), in which both magnet and armature winding are located at the short primary side whereas the secondary side is composed of only magnetic steel. This configuration is typically used in long stroke applications to save magnet material. With different configurations of phase winding, the machine can have two topologies, viz. axial three-phase and circumferential three-phase. The structure and operational principle of both topologies are firstly introduced; And then both theoretical and numerical analyses are performed. The electromagnetic characteristics of both machines, with particular focus on thrust force and force ripple, are optimized. Finally, the performances of optimal schemes of these two topologies are summarized and compared.

A free-piston energy converter (FPEC) integrated by a combustion engine and a linear electric machine is suitable for series HEV or other applications stand-alone generators. The transverse-flux machine (TFM) is considered advantageous for such application because of its high specific power and force density [1]. The finite element method (FEM) is widely used in the machine analysis, which is time-consuming. The equivalent magnetic circuit analysis is a time-effective method compared with FEM.

The free-piston Stirling-engine linear-generator system can make efficient use of multiple energy resources, so it has great application potential in the fields of aeronautics and astronautics including space station, human lunar exploration, space vehicle, etc. This paper investigates the control strategy of the free-piston Stirling-engine permanent-magnet (PM) linear-generator system. The mathematical models of PM linear generator and free piston Stirling engine are established. The control strategies at starting and generating stages are proposed. The system simulation and experiment verification are also made.

A single-phase oscillating permanent-magnet (PM) alternator is proposed for free-piston stirling engines. According to its sinusoidal kinetic characteristic, the design principle of this machine is proposed. On this basis, the finite-element model is built. Since the no-load back EMF and no-load thrust are two key indexes for the single-phase oscillating PM machine, the influence of PM thickness on the no-load back EMF and no-load thrust is further investigated. Then an optimal scheme of single-phase oscillating PM machine is obtain. Because this machine has two working modes, the electromagnetic performance of two working modes is analyzed. In the generator mode, no-load and load back EMF, voltage harmonics distortion ratio, the voltage regulation ratio and kinetic characteristics are deeply analyzed. Then in the motor mode, the electromagnetic force versus current is investigated. That proves the electromagnetic thrust per current can reach 35.7 N/A.

© 2015 AIP Publishing LLC. This paper describes a tubular dual-stator flux-switching permanent-magnet (PM) linear generator for free-piston energy converter. The operating principle, topology, and design considerations of the machine are investigated. Combining the motion characteristic of free-piston Stirling engine, a tubular dual-stator PM linear generator is designed by finite element method. Some major structural parameters, such as the outer and inner radii of the mover, PM thickness, mover tooth width, tooth width of the outer and inner stators, etc., are optimized to improve the machine performances like thrust capability and power density. In comparison with conventional single-stator PM machines like moving-magnet linear machine and flux-switching linear machine, the proposed dual-stator flux-switching PM machine shows advantages in higher mass power density, higher volume power density, and lighter mover.