Elektrikli araçlar için gömülü mıknatıslı senkron motor tasarım metodolojisi ve gerçeklenmesi
Design methodology and implementation of interior permanent magnet synchronous motor for electric vehicles
Yazar: HATİCE KURNAZ ARAZ
Danışman: DR. ÖĞR. ÜYESİ MURAT YILMAZ
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Elektrik Mühendisliği Ana Bilim Dalı
Derece: Yüksek Lisans, 2018
Konu: Elektrik ve Elektronik Mühendisliği = Electrical and Electronics Engineering

Özet:
Bu tez çalışması, bir araca çekiş sağlayacak elektrik makinesinin tasarımı, üretimi ve test edilmesi üzerinedir. Çalışmada öncelikle elektrikli araçlarda kullanılan elektrik makineleri incelenmiş ve tez kapsamında gömülü kalıcı mıknatıslı senkron motor çalışılmasına karar verilmiştir. Ardından, elektrik motorunun tasarım akış diyagramı oluşturularak oluşturulan akış diyagramı doğrultusunda elektrik makinesi tasarımı yapılmıştır. Bu kapsamda, uygulama yapılacak aracın gereksinimleri belirlenerek tasarlanan elektrik makinesinin parametreleri belirlenmiştir. Parametreleri belirlenen elektrik makinesinin tasarımında detaylı analitik hesaplar yapılmıştır. Yapılan analitik hesaplar doğrultusunda elektrik makinesi temel parametrelerin belirlenmesi, boyutlarının belirlenmesi, sargı yapısının belirlenmesi, manyetik devrenin hesaplanması ve endüktans hesaplanması gibi alt başlıklarda bir süreç olarak tasarlanmış ardından sonlu elemanlar yöntemi kullanılarak analitik hesaplar doğrulanmıştır. Sonlu elemanlar yöntemi kullanılarak elektrik makinesinin çeşitli koşullardaki analizleri koşturularak çeşitli çalışma noktalarındaki çalışma detayları öngörülmüştür. Elektrik makinesinin vuruntu momenti, moment dalgalanması ve üretilen harmonikler incelenmiştir. Ayrıca sonlu elemanlar yöntemi kullanılarak elektrik makinesinin sac malzemesi optimizasyonu, oluk sayısı optimizasyonu ve oluk ağzı optimizasyonu yapılmıştır. Verim haritası çıkartılmış ve yapısal dayanım analizi yapılmıştır. Analitik hesaplar ile sonlu elemanlar yöntemi kullanılarak yapılan analizler karşılaştırılmıştır.
Analitik hesabı yapılan ve sonlu elemanlar yöntemi ile de doğrulanan elektrik makinesinin üretimi gerçekleştirilmiştir. Elektrik makinesinin üretimi, stator ve rotor üretimi olmak üzere iki bölümde detaylandırılarak gerçekleştirilmiştir. Üretilen elektrik makinesinin deney düzeneği üzerinde boşta çalışma, motor modda yükleme, generatör modda yükleme ve sıcaklık yükselme deneyleri yapılmıştır. Yapılan deneylerde, uygulama yapılan araç üzerindeki düzeneklerin aynısı deney düzeneğine yerleştirilerek deneyler yapılmıştır. Deney düzeneğinde deneyleri gerçekleştirilen elektrik makinesi, uygulama yapılan araca monte edilerek aracın elektrikli araca dönüşümü sağlanmıştır.
Deneyleri tamamlanan elektrik makinesinin sonuçları analitik ve nümerik sonuçlar ile karşılaştırılmıştır. Sonuçlanan elektrik makinesinde stator oluklarında tek oluk sayısı kullanılarak oluşturulan simetrik olmayan sargı yapısı sayesinde uzay harmonikleri, radyal kuvvetler ve vuruntu momentinin etkisi azaltılmıştır. Dolayısıyla, 57 oluk kullanımı ile moment dalgalanması ve vuruntu momenti azaltılmıştır. Gelecek çalışmalarda alan zayıflatmanın iyileştirilmesi ve relüktans momenti üretiminin artırılması üzerine çalışılacaktır.

Abstract:
In this thesis, an interior permanent magnet synchronous machine design and implementation studied for battery electric vehicle application. This electrical machine is the driving force of the selected vehicle, as well as battery charged with this machine in regenerative braking.
First, all of the electrical machines, which used in the electrical vehicles, are studied. Pros and cons of those electrical machines in use of electrical vehicle investigated. Therefore, mechanical topologies like inner rotor, outer rotor, radial flux and axial flux electrical machines also examined. All of these investigations made to choose the most suitable electrical machine in our application. Because of the high demand like high efficiency, wide torque speed range and high torque density has led us to the interior permanent magnet synchronous machine (IPMSM). Inner rotor and radial flux topologies of IPMSM is selected based on its robust structure and acceptable characteristics.
Next, the materials used in IPMSM investigated. Electrical steel sheets, which have different thicknesses and different loss values, examined. The thinnest electrical steel sheet material that can produced as a non-grain oriented electrical steel, which has 0.127 mm thickness, also investigated. New technology iron core material soft magnetic composite (SMC) materials also investigated. All of these iron core materials compared to each other in case of iron losses in different frequencies, magnetic permeabilities, B-H curves and the price per unit values. Therefore, conductive materials and permanent magnet materials are studied. In conductive materials the best conductive is silver. Due to price issues silver is not applicable in our application. The most suitable conductive material is copper in our application. Permanent magnet materials, which are NdFeB, SmCo, ferrite and alnico, also investigated. In electrical machines used for electrical vehicles permanent magnets are need to have high coercivity, high remanence, high knee magnetic flux density and maximum magnetic energy per unit of volume. For this reasons, NdFeB permanent magnet N45SH that has high coercivity, high remanence, high knee magnetic flux density and maximum magnetic energy per unit of volume selected in our application.
After investigating the materials, phasor diagrams, equivalent circuit, main equations and circle diagrams of IPMSM studied to understand the characteristics of this electrical machine. Torque equations and flux weakening capabilities investigated within this purpose.
After that, design process of traction machine IPMSM started. Design flow diagram generated and IPMSM designed based on this flow diagram. In flow diagram, stator design process and rotor design process divided from main flow diagram because these processes have many parameters, which connected to each other. That is why those processes divided from the main diagram. After generating design flow diagram, vehicle requirements and determination of electrical machine parameters stage started as stated in the design flow diagram. Vehicle required torque is determined according to the permissible highway slope at 90 km/h and slope at full load. Maximum local road gradient is 7% and implemented vehicle should climb that slope at 90 km/h. Maximum speed is determined 90 km/h because this is the maximum speed limit for the vehicle to be electrified. In order to calculate the vehicle's maximum speed and gradeability some equations presented and the forces on the vehicle are calculated. After some calculations, electrical machine specification table presented. A 290 Nm nominal torque and 1500-rpm nominal speed selected. After determining the electrical machine parameters, electrical machine analytical design stage started. Main design parameters explained and examined in detail. Determination of electrical machine dimensions based on coefficient of utilization and other dimensional constraints are studied. Stator winding structure determination done based on given formulas. Consantrated and distributed winding structures examined and distributed winding selected for torque ripple reduction. Losses and reduction of losses on the conductor examined in detail and AC and DC resistance equations are given. The issues that need to taken into account about the conductor losses explained and considered in the design. Magnetic circuit calculation, d- and q-axis inductance calculation, magnetic noise causes and cogging torque reduction is detaily examined.
Design process begins once all attention paid and formulas are given. Systematically design process explained. The electrical machine parameters are calculated or determined based on given formulas and criterias. After that, losses and efficiency calculated in nominal speed and torque. Analytical calculation process is finished after those calculations.
After that, analytically designed electrical machine icreated to be able to design with a program based on finite element methot. Different situations of the electrical machine are analysed with that program. First, analytical design module is used to analyse the electrical machine. Then, electromagnetic design made with generating a constant mesh with constant materials. No-load operation, full-load operation, inductance calculation and segregation analysis of torque components is completed.
Iron core material optimization made with seven different materials and M360-35A material selected for production because it has low material costs, has the highest efficiency, and delivers very good results at other comparisons. Stator slot number optimization made with seven different slot numbers. Rotor pole number and the shapes is the same but stator slot numbers are changing. These seven different electrical machines compared in terms of cogging torque, torque ripple, torque, iron losses and efficiency. When examining the results of the the analyses, it is found that the electrical machine with the highest torque, the lowest cogging torque and the highest efficiency is in the 57 stator slot numbers electrical machine. Slot tip optimization also made with 24 different slot tips. Thermal analysis, structural strength analysis made and finally efficiency map generated.
After that, analytical calculation results and finite element method analysis results compared. Because of the results in differences are acceptable, production stage started. Production stage divided into two stages, production of stator and production of rotor.
After electrical machine production is completed, experiment mechanism presented and experiment stage started. Electrical machine is experimented in the experiment mechanism at no-load operation, full-load operation in motor mode, full-load operation in generator mode and temperature rise conditions. Therefore, electrical machine mounted on the vehicle. Experiments are performed on-vehicle. Regenerative braking provided and 155 km range performed.
Finally, analytical calculation results and finite element method analysis results are compared with experimental results. In the resulting electrical machine, the effect of space harmonics, radial forces and cogging torque reduced due to the non-symmetrical winding structure created by using single slot number. Therefore, with the use of 57 slot, torque ripple and cogging torque reduced. Future work will focus on improving flux weakening and increasing reluctance moment production.