Toplinska analiza asinkronog stroja

The temperature distribution over the cross-section of an induction motor is calculated at the steady state and transient condition. In order to develop smaller and more efficient electric motors, there is a necessity to carry out more thermal analysis in parallel with the traditional electromagnetic design. It has been found that attention to the thermal design can be rewarded by major improvements in the overall performance. The developed thermal model for Total Enclosed Fan Cooled (TEFC) induction motors is implemented into the design program called Motor-CADTM. The model produced has been experimentally verified by measurements on industrial machines. The obtained results confirm that the developed thermal model is capable of a sufficient degree of accuracy in the thermal design of (TEFC) induction motors.Predstavljen je proračun razdiobe temperature po presjeku asinkronog stroja za stacionarno opterećenje kao i za slučaj zakočenog rotora. U cilju smanjenja dimenzija i povećanja korisnosti neophodno je primijeniti detaljniju toplinsku analizu uz elektromagnetski proračun. Nalazi se da je rezultat primjene detaljnije toplinske analize poboljšanje operativnih karakteristika motora. Razvijeni toplinski model za potpuno zatvoreni asinkroni motor s prisilnim hlađenjem zrakom izvana (TEFC) je uključen u računalni program za projektiranje naziva Motor-CADTM. Prikazani model je eksperimentalno potvrđen na industrijskim električnim strojevima. Dobiveni rezultati potvrđuju da razvijeni toplinski model posjeduje dovoljan stupanj točnosti u toplinskom projektiranju (TEFC) asinkronih strojeva

A Computationally Efficient Method for Calculation of Strand Eddy Current Losses in Electric Machines

In this paper, a fast finite element (FE)-based method for the calculation of eddy current losses in the stator windings of randomly wound electric machines with a focus on fractional slot concentrated winding (FSCW) permanent magnet (PM) machines will be presented. The method is particularly suitable for implementation in large-scale design optimization algorithms where a qualitative characterization of such losses at higher speeds is most beneficial for identification of the design solutions which exhibit the lowest overall losses including the ac losses in the stator windings. Unlike the common practice of assuming a constant slot fill factor, sf, for all the design variations, the maximum sf in the developed method is determined based on the individual slot structure/dimensions and strand wire specifications. Furthermore, in lieu of detailed modeling of the conductor strands in the initial FE model, which significantly adds to the complexity of the problem, an alternative rectangular coil modeling subject to a subsequent flux mapping technique for determination of the impinging flux on each individual strand is pursued. The research focus of the paper is placed on development of a computationally efficient technique for the ac winding loss derivation applicable in design-optimization, where both the electromagnetic and thermal machine behavior are accounted for. The analysis is supplemented with an investigation on the influence of the electrical loading on ac winging loss effects for a particular machine design, a subject which has received less attention in the literature. Experimental ac loss measurements on a 12-slot 10-pole stator assembly will be discussed to verify the existing trends in the simulation results

Computationally Efficient Strand Eddy Current Loss Calculation in Electric Machines

A fast finite element (FE) based method for the calculation of eddy current losses in the stator windings of randomly wound electric machines is presented in this paper. The method is particularly suitable for implementation in large-scale design optimization algorithms where a qualitative characterization of such losses at higher speeds is most beneficial for identification of the design solutions that exhibit the lowest overall losses including the ac losses in the stator windings. Unlike the common practice of assuming a constant slot fill factor s f for all the design variations, the maximum s f in the developed method is determined based on the individual slot structure/dimensions and strand wire specifications. Furthermore, in lieu of detailed modeling of the conductor strands in the initial FE model, which significantly adds to the complexity of the problem, an alternative rectangular coil modeling subject to a subsequent flux mapping technique for determination of the impinging flux on each individual strand is pursued. Rather than pursuing the precise estimation of ac conductor losses, the research focus of this paper is placed on the development of a computationally efficient technique for the derivation of strand eddy current losses applicable in design optimization, especially where both the electromagnetic and thermal machine behavior are accounted for. A fractional-slot concentrated winding permanent magnet synchronous machine is used for the purpose of this study due to the higher slot leakage flux and slot opening fringing flux of such machines, which are the major contributors to strand eddy current losses in the windings. The analysis is supplemented with an investigation on the influence of the electrical loading on ac winding loss effects for this machine design, a subject that has received less attention in the literature. Experimental ac loss measurements on a 12-slot 10-pole stator assembly will be discussed to verify the existing trends in the simulation result

Integration Methodologies for Disparate Software Packages with an Emphasis on Usability

This paper describes a novel approach to program script generation. The goals are twofold: to allow a number of different software packages to be implemented together and to permit a user with little or no programming skill to produce executable code. The principles and requirements of such a system are discussed and an outline approach is suggested. A case study based on electric motor design is presented for which early results are encouraging. Future development is considered in conclusion

Specificity and sensitivity of the social communication questionnaire lifetime screening tool for autism spectrum disorder in a UK CAMHS service

The Social Communication Questionnaire is used to identify children and young people (CYP) who may require formal ASD assessment. However, there is a paucity of research on its utility in Children and Adolescent Mental Health Services. This evaluation aimed to determine the sensitivity and specificity of the Social Communication Questionnaire (SCQ) in a UK, Midlands CAMHS service. Method: Forty young people (mean age 13.75 years) were screened using the caregiver reported SCQ before completing 'gold standard' assessment. Results: The SCQ had a sensitivity of 80% and a specificity of 25.7%. ROC curve analysis indicated low diagnostic accuracy. Differences in predictive accuracy of SCQ and diagnostic standard were statistically significant (p < 0.0001). Conclusion: This evaluation builds on previous research suggesting that the SCQ may not be an efficient screening tool in CAMHS settings

Electromagnetic performance with and without considering the impact of rotation on convective cooling

Accurate thermal modelling of electrical machines is important for electromagnetic performance determination of a design. This study presents the impact of rotation on convective cooling of a through-ventilated motor – a design equivalent to the Tesla S 60 traction motor design. Machine temperatures after steady state with and without considering rotation effects are compared, and the influence on the machine continuous performance is investigated

Functional Neurological Disorder: A Qualitative Study Exploring Individuals' Experiences of Psychological Services

Objectives: Individuals with a diagnosis of FND report experiencing stigma in medical settings, however, there is a paucity of research exploring their experiences in psychological services. The aim of this research was to explore experiences of accessing UK psychological services, from the perspective of those with FND. Methods: This study utilised a qualitative approach with data collected from semi-structured interviews (n = 15) and analysed using reflexive thematic analysis. Results: One superordinate theme, 'the stigmatised self within the therapeutic relationship', and five interrelated subthemes were identified: 'internalised stigma and self-doubt', 'selective disclosure to professionals', 'perceptions of psychological explanations', 'having to educate the professionals' and 'attunement and trust within the therapeutic relationship'. Positive therapeutic relationships were perceived to mitigate the impact of these perceived barriers. The conceptualisation of FND and the perception of how this was responded to by services and professionals was a central tenet throughout the related themes. Conclusions: Intra-personal, interpersonal and organisational stigma impact access and engagement to psychological treatment. The findings of this study highlight the need for increased training provision for practitioners with a focus on actively challenging FND stigma within services at both an individual and systemic level