Axial Motor Research Articles

Magnetic equivalent circuit and finite element modelling of anisotropic rotor axial flux permanent magnet synchronous motors with fractional slot distributed winding

AbstractAxial flux motors have been in the focus of many research work due to their promising properties when compared to conventional radial flux machines. Axial flux permanent magnet synchronous motors (AFPMSM) studied in the literature were mostly limited to surface‐mounted permanent magnet machines (SPMSM), excluding only a few studies about axial flux internal permanent magnet (AFIPM) or permanent magnet‐assisted synchronous reluctance (AFPMaSynRM) machines. Since numerous rotor topologies have been proposed and investigated in case of radial flux motors, analogous design methodologies can be developed in case of axial flux motors with rotor saliency. The parametrisation and modelling of a magnetically anisotropic rotor axial flux motor are presented. This approach is described generally and the method is applied to an example motor geometry. The results were validated by FEA (Finite Element Analysis), using the 2D multi‐slice and 3D modelling approaches. The modelling error was calculated and the analytical and numerical methods were compared. It was found that the proposed model was suitable for calculating important parameters of the anisotropic rotor axial flux permanent magnet synchronous motor (AnR‐AFPMSM) during the design process.

Nomogram to Predict the Probability of Functional Dependence in Early Parkinson's Disease.

Early identification of Parkinson's disease (PD) patients at risk for becoming functionally dependent is important for patient counseling. Several models describing the relationship between predictors and outcome have been reported, however, most of these require computer software for practical use. Here we report the development of a risk nomogram allowing an approximate graphical computation of the risk of becoming functionally dependent in early PD. We analyzed data form the Parkinson's Progression Markers Initiative cohort of newly diagnosed PD patients from baseline through the first 5 years of follow-up. Functional dependence was defined as a score < 80 on the Schwab & England Activities of Daily Living scale. A binary logistic model was developed to estimate the risk of functional dependence and based on the results, a nomogram for the prediction of functional dependence was drawn in order to provide an easy-to-use tool in clinical and academic settings as a part of personalized medicine approach to PD treatment. At baseline, three patients and over the five-year follow-up, 85 (22%) out of 395 patients were functionally dependent as scored by the Schwab & England Activities of Daily Living rating scale. The binary logistic model showed that clinical parameters such as MDS-UPDRS I (rater part), MDS-UPDRS II, and MDS-UPDRS axial motor score were significant predictors for functional dependence within 5 years. We here provide an easy-to-use tool to estimate the risk of functional dependence in PD patients based on the MDS-UPDRS part I, II and axial motor score.

Criterion validity of the spatial exploration test of upper limb mobility to evaluate the active horizontal workspace of children with spinal muscular atrophy

Purpose To determine the criterion validity of the SET-ULM (Spatial Exploration Test of Upper Limb Mobility), a functional workspace test. Materials and Methods A prospective study from July 2017 to November 2018 in 30 children with SMA type 1 or 2. All children underwent assessment with the SET-ULM and the Motor Function Measure (MFM). Results We included 30 children. Median (Q1; Q3) MFM D1 (standing ability, ambulation and transfers), D2 (axial and proximal motor function), D3 (distal motor function) scores, Total MFM and Total SET-ULM active score were respectively 2.6% (2.6–3.8); 45.8% (19.9–65.3); 57.7% (36.9–80.9); 35.4% (16.7–43.2) and 70.2% (49.7–97.9). Total SET-ULM active score was strongly correlated with the MFM D2 dimension score (rho 0.82; p < 001), with the D3 dimension (rho 0.86; p < 0.001) and with the Total MFM score (rho 0.89; p < 0.005). Total SET-ULM active score differed between SMA types (p < 0.01). Conclusion The SET-ULM has good criterion validity for the evaluation of available horizontal active upper limb workspace in children with SMA1 and SMA2. Future studies should evaluate reliability and sensitivity to change during a longitudinal follow-up study, as well as in a longitudinal trial of therapeutic effectiveness. Clinical Trials NCT03223051 IMPLICATIONS FOR REHABILITATION The Spatial Exploration Test for Upper Limb Mobility is a useful adjunct to the Motor Function Measure. It provides a precise evaluation of horizontal reaching ability. The Spatial Exploration Test for Upper Limb Mobility will be of great clinical utility for the evaluation of the effects of treatments for spinal muscular atrophy.

Optimal design of a yoke-less axial flux switching PM motor based on multi-objective PSO

PurposeIn this paper, an improved multiobjective particle swarm optimization (PSO) algorithm is proposed to optimize a three-phase, 12-slot, 19-pole, yokeless axial-field flux-switching permanent magnet (YASA-AFFSPM) motor.Design/methodology/approachBased on the structural characteristics of the YASA-AFFSPM, a mathematical model is established to calculate the main size of the YASA-AFFSPM motor. The split ratio, stator axial length, sandwiching pole angle, rotor pole angle, PM arc and number of conductors per slot are selected as optimization variables. Also, the efficiency, power factor, cogging torque and average torque are considered as the optimization objectives. The objectives are optimized by combining the improved multiobjective PSO algorithm with electromagnetic calculation.FindingsBased on the proposed algorithm, the investigated motor is optimized. The on-load efficiency, power factor and average torque of the motor performance have increased by 0.87%, 3.13% and 10.39%, respectively. Moreover, the cogging torque and slot fill factor have undergone decreases of 8.57% and 3.34%, respectively. Finally, the effectiveness of the algorithm is verified using experiment results.Originality/valueSo far, no comprehensive report has been observed on the optimization of the YASA-AFFSPM motor using evolutionary algorithms and the study of the effect of the motor parameters. Therefore, in this paper, the authors decided to investigate the effect of YASA-AFFSPM motor parameters and improve motor performance with the improved PSO method.

Review on Thermal Behavior and Cooling Aspects of Axial Flux Permanent Magnet Motors–A Mechanical Approach

With the increasing demand for high-energy density motors for applications such as electric vehicles and aircraft propulsion, axial flux permanent magnet motors are promising. However, utmost care should be taken when designing an axial flux permanent magnet motor with a higher torque density because of thermal effects. To enhance the reliability and overall performance of a motor, efficient thermal management is important, because the torque density is restricted by maximum temperature. Therefore, this study comprehensively reviews different techniques used for the thermal modeling of motors. Computational fluid dynamics, the lumped parameter method, and finite element analysis were used to calculate the total heat transfer inside the motor. Various heat enhancement techniques for an axial flux permanent magnet motor have been presented, including core cooling (water jacket cooling, air cooling, and oil cooling) and winding cooling (direct slot cooling, end winding cooling, and fins). Finally, two case studies of an 8kW AFPM motor and a 65kW AFPM motor with a cooling arrangement are discussed.

Design and Optimization of Axial Field Flux-Switching Magnetic Gear Composite Motor Based on Varying-Network Magnetic Circuit

Design and Optimization of Axial Field Flux-Switching Magnetic Gear Composite Motor Based on Varying-Network Magnetic Circuit

Corrections to “Design and Optimization of Axial Field Flux-Switching Magnetic Gear Composite Motor Based on Varying-Network Magnetic Circuit”

Corrections to “Design and Optimization of Axial Field Flux-Switching Magnetic Gear Composite Motor Based on Varying-Network Magnetic Circuit”

Axial Gap Motor Shape Optimization Using Multi-Objective Based Genetic Programming Technique

Axial Gap Motor Shape Optimization Using Multi-Objective Based Genetic Programming Technique

Lower gastrointestinal dysfunction in patients with Parkinson's disease

To assess the lower gastrointestinal tract dysfunction in patients with Parkinson's disease (PD) and to reveal its relationships with motor and non-motor symptoms. One hundred and eighteen patients with PD of I-III Hoehn and Yahr (H&Y) stages were studied using UPDRSI-IV, Sch&En, PDQ-39, MMSE, BDI, STAI-S and STAI-T, PFS-16, NMSQ, GSRS, BSFS, AUA. Body mass index and saliva amount and lacrimation (Schirmer's test) were assessed. Constipation from mild to moderate intensity was present in 71.2% of the patients; predominantly mild diarrhea occurred in 27.9%; alternations of diarrhea with the difficulty in intestine emptying were observed in 25.4%. We found significant correlations of constipation with the following parameters: Sch&En scales (rS=-0.291) and PDQ-39 (rS=0.478), patient's age (rS=0.275), H&Y stage (rS=0.2604), UPDRS (rS=0.254), axial motor symptoms of parkinsonism, and a number of affective and autonomic disorders, most of which were partly dopamine-resistant. Diarrhea did not affect the quality of patient's life, or depend on age, PD stage, main digital and non-motor symptoms, but directly correlated with the severity of constipation (rS=0.263) and other gastrointestinal disorders. There were no effects of dopaminergic therapy, including levodopa, dopamine-receptor-agonists, and amantadine, on the lower gastrointestinal tract dysfunction. Dysfunction of the lower gastrointestinal tract (predominantly from mild to moderate intensity) was detected in most PD patients of I-III stages. Our data indicate a complex pathogenesis of the PD impaired bowel emptying, involving degeneration of non-dopaminergic structures, and the predominant influence of concomitant diseases and inadequate laxative therapy on the formation of diarrhea syndrome in PD.

Research on Modeling Method for Eccentric Axial Force of Axial Flux Permanent Magnet Motor with Single-Rotor–Single-Stator Structure

Research on Modeling Method for Eccentric Axial Force of Axial Flux Permanent Magnet Motor with Single-Rotor–Single-Stator Structure

Thermal Analysis and Test of Axial Flux Permanent Magnet Synchronous Motor Performances

The axial flux permanent-magnet synchronous motor with amorphous alloy stators has the advantages of high power density, high efficiency, large starting torque. But the PMSM has poor performance in heat resistant and radiation. And the electromagnetic loss has a significant impact on in-wheel motor’s heat generation. To demonstrate the influence of electromagnetic loss on winding coils of the PMSM, the mathematical model of the thermal transformation was founded to illustrate the progress of temperature rising. The mathematical model and experimental test were verified mutually. The experimental prototype was manufactured and tested, including the output power model and braking energy recovery model. And the experimental prototype performed working in low rotation speed mode and middle rotation speed mode separately, when the revolving speed increased by 50% the thermal of winding raise approximately 23.5%. Further, the analytic formulas and experimental results consistent with each other approximately, in which the mathematical analysis method was verified by test value.

Three-dimensional Analytical Modeling of Axial Flux Permanent Magnets Maglev Motor

The three-dimensional(3D) analytical model of the magnetic field in an Axial Flux Permanent Magnets Maglev Motor(AFPMMM) is proposed and investigated the influence of the structural parameters on electromagnetic characteristics. Firstly, the topology and working principle of the AFPMMM is introduced, and the model is transferred into a mathematical model in 3D cartesian coordinate. Then, the volume integral method and equivalent current sheets model is applied to find the 3D magnetic field distribution function of Halbach rotor. A unified form expression can be obtained by two dimensional discrete fourier transform (2-D DFT) is applied on the 3D magnetic field distribution function. Thirdly, the conductive and nonconductive regions of AFPMMM will be formulated by the second order vector potential (SOVP) to built the 3D analytic model. The expression of the lift force, torque and power losses was derived. Besides, the relationship between electromagnetic characteristics and structural parameters of the AFPMMM were analyzed based on 3D analytic model and validated using the 3D finite element analysis(FEA). Finally, the experiments based on a small scale prototype are carried out to verify the analytical results.

Multi-Objective Optimization of an Axial Flux Permanent Magnet Brushless DC Motor with Arc-Shaped Magnets

To get a better electromagnetic performance of an axial flux permanent magnet brushless DC motor (AFPMBLDC), an AFPMBLDC with arc-shaped magnets and its multi-objective optimization design are researched. Firstly, the main design parameters of the AFPMBLDC are proposed, and the initial designs are carried out according to the given requirements. Furthermore, the pole arc coefficient, permanent magnet thickness, permanent magnet arc radius, and air-gap length are selected as optimization factors. Then, an orthogonal experiment table is established, in which the flux density, no-load back EMF, harmonic distortion rate, and output torque ripple are selected as optimization targets. The Taguchi optimization method is adopted to optimize the performance indexes and the optimal parameters are obtained. Finally, the optimized model is constructed, and some simulations are carried out to verify the optimal design. The research results have shown that the air-gap flux density of the optimized AFPMBLDC is reduced to 31.8%, the total harmonic distortion rate of no-load back EMF is less than 7.5%, and the torque ripple is reduced to 4.3%.

Depressive symptoms and axial motor disorders in individuals with Parkinson's disease: a cross-sectional study.

Depression is an important nonmotor symptom of Parkinson's disease (PD) and has been associated with the motor symptoms in these individuals. To determine whether there are relationships between depressive symptoms and abnormalities in axial postural alignment and axial motor deficits, especially postural instability, and trunk rigidity in PD. In this cross-sectional study, 65 individuals were evaluated using the Beck Depression Inventory-II (BDI-II) for the analysis of depressive symptoms and underwent a postural assessment of head, trunk, and hip sagittal alignment through computerized photogrammetry. The MDS-UPDRS was used to assess clinical aspects of PD, the Trunk Mobility Scale was used to assess axial rigidity, and the MiniBESTest to assess balance. To determine the relationship between depressive symptoms and postural alignment, multiple linear regression analysis was performed. The participants with depressive symptoms had more severe motor deficits as well as greater trunk rigidity and worse postural instability (p < 0.05). When the postural angles were compared between men and women using Student's t-test, it was found that men had greater flexion angles of the head (p = 0.003) and trunk (p = 0.017). Using multiple linear regression analysis corrected for the age and sex of the participants, we verified that the anterior trunk inclination was significantly larger in the PD population with depressive symptoms (R2 = 0.453, β = 0.116, and p = 0.045). PD individuals with depressive symptoms have more severe flexed trunk posture, mainly in older men. Additionally, more severe depressive symptoms are associated with worsening postural instability, trunk rigidity and motor deficits in this population.

Electromagnetic Design Characterization of a Dual Rotor Axial Flux Motor for Electric Aircraft

This article presents and evaluates a dual rotor axial flux permanent magnet motor for electric aircraft applications. Several features, including grain-oriented electrical steel, Halbach arrays, and wires with rectangular cross sections, are used to improve torque density and efficiency. A novel winding arrangement is used to mitigate interturn short-circuit faults. Rather than simply optimizing the motor by itself, this article evaluates the tradeoffs between motor performance and its interfaces with the drive, thermal management system (TMS), and mechanical structure. This information can be used along with similar analyses of these subsystems to select the design with the system-level optimal performance. This article uses finite-element simulations to characterize tradeoffs among active mass, efficiency, fundamental frequency, power factor, axial forces on the rotors, and cooling surface area. Several designs exceed 95% efficiency at takeoff with less than 8 kg of active mass. While high pole counts, a large outer radius, and short stator teeth tend to optimize the magnetic performance at takeoff, this can reduce cruise efficiency, reduce the surface area through which the TMS can extract heat, increase the fundamental frequency the drive must supply, increase the structural mass required to support the rotors, and introduce complexity to the manufacturing process. Further analysis for a selected design reveals that the power factor can be significantly improved with a minimal torque penalty via field weakening due to significant saturation in the stator teeth.

Association of cholesterol level with dopamine loss and motor deficits in Parkinson disease: A cross-sectional study.

Cholesterol is vital in neuronal function; however, the influence of cholesterol levels on parkinsonism is unclear. This study investigated the relationship between baseline total cholesterol (TC) levels, dopamine loss, and motor symptoms in drug-naïve Parkinson disease (PD). This cross-sectional study enrolled 447 drug-naïve patients with PD who underwent dopamine transporter (DAT) imaging. Multivariate linear regression was used to investigate the effect of cholesterol levels on Unified Parkinson's Disease Rating Scale Part III (UPDRS-III) total score and each subscore after adjusting for the covariates. An interaction analysis was performed to examine the interaction between TC levels and statin use on the UPDRS-III scores. No significant correlation was found between TC levels and DAT availability after adjusting for potential confounders. Multivariate linear regression showed that TC levels were significantly and negatively associated with the UPDRS-III total score (β=-0.116, p=0.013) and bradykinesia subscore (β=-0.145, p=0.011). Dichotomized analysis according to TC levels showed that TC levels were significantly associated with UPDRS-III total score, and rigidity, bradykinesia, and axial subscores only in the low TC group. There was an interaction effect between TC levels and statin use for the axial subscores (β=-0.523, p=0.025). Subgroup analysis showed that TC levels were significantly and negatively associated with the axial subscore in statin users; however, no association was found in statin nonusers. This study suggests that TC levels affect parkinsonian motor symptoms, especially in subjects with low cholesterol status, whereas the severity of axial motor symptoms is negatively associated with TC levels only in statin users.

P.73 Structural damage in dystrophinopathies: a multimodal neuroimaging study

Dystrophinoapthies are characterized by central nervous system damage, but pattern and extent of such damage are not yet clear. For this reason, we designed a cross-sectional multimodal MRI-based study to address this point. We enrolled 50 patients (40 Duchenne and 10 Becker) and 40 age-sex matched controls. All subjects underwent 3T MRI to assess gray (GM) and white matter (WM). To evaluate the cerebral and cerebellar cortices, we used FreeSurfer. DTI-multiatlas was used to investigate microstructural-abnormalities in cerebral WM. All analyses were corrected for multiple comparisons. Mean age of patients and disease duration were 12 and 8, respectively. Group analyses showed WM microestructural abnormalities at bilateral fornix, seen as increased axial, mean and radial diffusivities, with large effect sizes (>0.8). We also found a negative correlation between fornix axial diffusivity and Motor Functional Measure scores (r=-0.338, p=0.022). Regarding volumetric analyses, there was volumetric reduction of both left thalamus and cerebellar cortex in the patient group. Dystrophinopathies are characterized by fornix, thalamus, and cerebellar cortex damage. Such structural signature helps us to understand some phenotypic traits in this disease.

Efficiency Analysis of Axial Flux SynRM in Variable Speed Applications

Electrical machines find their place in every field, such as industrial, transportation, home, and commercial sectors. The suitability of the electrical machine for the area in which it will be used is important in terms of energy efficiency. The selection of the motor to be used for variable speed applications such as electric vehicles is also very important. Torque and power are the determining factors in the required speed/torque or speed/power combination for electric vehicles. For this reason, the efficiency map of the motor to be used in electric vehicles should be known in detail. In this study, due to its advantages such as its lighter structure, absence of magnet, and rotor winding loss, among others, the Axial Flux Synchronous Reluctance Motor (AF-SynRM) was preferred, and it was aimed at creating an efficiency map. The motor parameters for the determined speed/torque combinations were first obtained with FEM. Then, the FEM results were experimentally verified. In order to make the obtained results more meaningful, the experimental results were compared with radial flux motors with the same output power. In addition, using FEM, von Mises stress analysis and displacement analysis were performed on the motor shaft under overload conditions to observe the mechanical effects on the moving parts of the AF-SynRM. Furthermore, mechanical load analysis on the bearings was also performed. The results show that AF-SynRM can be preferred as an alternative to other motor types, especially for applications requiring variable speed, such as electric vehicles. The study has created the efficiency map of the AF-SynRM topology for the first time.

Research on Simulation Method for Wear for Dynamic Seal in Axial Flux Hub Motor

A simulation method for the wear of a dynamic seal in an axial flux hub motor is proposed in this work. A quasi-3D magnetic model without deflection between the axes of a stator and a rotor is built. An analytical model for unbalanced magnetic force considering the cogging effect and axial deflection is presented based on the quasi-3D magnetic model. Boundary conditions of the dynamic seal are obtained through solving the FE model of a hub motor. Both the structural and thermal FE model of a dynamic seal are built and the thermal–structural coupling method is given. A dynamic wear simulation method is displayed based on the mesh reconstruction method proposed previously. It is proved through the contrast with the experimental results that the presented method is feasible.

Topologies comparison and rotor optimization of the hybrid axial transverse flux permanent magnet motor

With the advantages of high power density, the hybrid axial transverse flux permanent magnet motor (HATF-PMM) is investigated in this paper. Eight topologies of the novel HATF-PMM are proposed, analysed and compared. The applicable scopes of different topologies are summarized and the optimal topology is selected. Based on the characteristics of hybrid flux motor, an indirect optimization method through magnetic circuit decoupling and recombination is proposed. The rotor parameter optimization is performed by the proposed indirect optimization method. In the end, the HATF-PMM scheme with high power density is obtained, and the optimization law of HATF-PMM rotor parameters is revealed through the optimization process, which proves that the HATF-PMM has great potential in the application of more-electric aircraft.