To provide a clear structure of carried out research,this dissertation is divided into seven chapters which are summarized as follows.
Chapter 1 considered the reasons and progression of the reactions of climate protection and presents a short history of the development of the electrified vehicle.
In Chapter 2 the general drive techniques of the electric vehicle achieved at the present moment with a special interest on the in-wheel motor is described. A brief overview of the different types of electrical machines and possibilities of their integration of existing electrical power train concepts are described here, with reference to the possible solutions using wheel motors. Additional consideration to principal characteristics of the in-wheel motor and the boundary conditions of the application are discussed and the relevant requirements are derived. To analyze existing in-wheel motor concepts, a comparison with regard to the gravimetric power and torque densities and their presentation date are evaluated. Based on the outlined state of the art, the chapter closes with a problem statement and objective of this work.
In Chapter 3, the requirements on the in-wheel motors are determined. The fundamental requirements for the development include the step-by-step analysis of requirements for the vehicle, requirements of the topology of the in-wheel motor, requirements on the elastic coupling, requirements for the electric motor and requirements on the motor weight. The results of received requirements present a basis for further development.
Chapter 4 is devoted to the development of the in-wheel motor. The development strategy is segmented between an electrical, cooling and mechanical approach based on the geometrical restrictions of the motor and requested motor behavior.
Chapter 5 concentrates on the application of the specific design and focuses on the special factors of manufacturing and determination of the manufacturing of the full-scale motor in order to further validate the findings of this research. The realized technologies, which had been used as a basis for the manufacturing concepts, have proven to be technologically successful.
Chapter 6 includes a validation of the developed in-wheel motor as well as the impact of boundary conditions and assumptions determined in this work. For this reason, the prototypes were metrologically evaluated and the measured properties were analyzed. The prototypes were measured in special test stands regarding their electrical, magnetic and mechanical properties.
Summarizing Chapter 7,the aim of the work was to develop innovative solutions for electrified powertrains in order to further increase the attractiveness and spread of electric vehicles. Technological advances and increased energy efficiency were achieved by optimizing the main component of the drivetrain – the in-wheel motor. Important objectives were defined such as mass reduction, compact designs and reduced material use.
Further great potential was found in the structural optimization and the new motor architecture, whereby the requirement for a compact design was successfully implemented. Due to the relatively small iron content in the stator, the motor losses are accordingly reduced, which contributes to a very high degree of efficiency and thus meets the demands for an increased energy efficiency and range. It can be added that in this dissertation a considerable technological progress was worked out in detail and as a whole, which, through a significant increase in competitiveness, provides the basis for the development of new technologies in the field of the electric drive train.
As one of the final statements in reference to the development of the concept of a novel type of winding, the technical advantages of the lightweight motor were significantly improved. In addition to its low weight, a major advantage of the motor in terms of compactness is the reduction in the dimensions of the stator. For example, the motor has a comparatively large interior space and could thus contain various components (e.g.
control system). Based on the experience and results of the application steps, the respective prototypes were built and assembled. Thus, the practical results of the dissertation are prototypically manufactured and tested in-wheel motors with reduced weight, a more compact design and performance data that meet the requirements
117 of the market. The prototypes were used to test the theoretically proposed solutions. According to the requirements on the motor, a series of the test was carried out. The results of the mechanical tests showed clear advantages in the application of the developed topology and decoupling element with only 0.062 mm or 12.4%
of the air gap at the maximal load. This provides stability of the essential motor parameter such as the consistency of the torque, which also affects the smoothness of the vehicle. An electro-mechanical parameter for the motor, the cogging torque, was successfully reduced with the help of special material and geometric adjusting. Based on the data from the measurements of the prototypes, the maximum efficiency was determined to be 92.8%. As the final result of the work, the used lightweight technologies for the realization of the concepted in-wheel motor were evaluated. An achievable value of torque/weight ratio reaches 30.42 Nm/kg and the value of power/weight ratio is 3.77 kW/kg. Thus, the methodology presented in this thesis was successfully validated. The overall system of the in-wheel motor works according to the expected results of the calculations and simulations on which the concept was based.
Looking ahead, a benchmark analysis with world-renowned and competing in-wheel motors has shown, that the developed motor technology can replace existing in-wheel solutions and traditional drive systems in the automotive sector in the future.
118
Appendix A
Parameters of Modern-Line single section and modular wheel
Appendix B
Parameters of Goodyear Vector 4 Seasons tire
Parameter Value
Tire width 205 mm
Aspect ratio 60%
Wheel diameter 16”
Load-capacity index 92 (max 630 kg)
Speed index H (max speed 210 km/h)
119
Appendix C
Parameters of N45SH material
120
Appendix D
Properties of the NO20 electrical steel
121
Appendix E
Parameters of the foil 70984
Adhesive Carrier film Adhesive
Type Transfer adhesive
Acrylat Kapton 100MT Transfer adhesive
Acrylat
Article CMC 15581 Kapton 100MT CMC 15811
Adhesive strength 5.5 N/cm 1.0 N/cm
Thickness 0.050 mm 0.025 mm 0.020 mm
Width 140 mm
Appendix F
Parameters of the copper wire and insulation for air gap winding SFT-AIW 0.31x0.94
Item
Conductor dimension
Thickness of
insulation Overall dimension
Pinhole
Dielectric breakdown
voltage
Conductor resistance Thickness Width Thickness Width Thickness Width
Unit mm mm mm mm mm mm Pcs/m kV Ω/km
- 0.31 0.94 0.025 0.025 - -
3 3.0 68.131
max 0.319 1.0 0.04 0.04 0.38 1.045
min 0.301 0.88 0.02 0.02 - -
Parameters of the copper wire and insulation for slot winding SFT-AIW 1.0x1.1
Item
Conductor dimension
Thickness of
insulation Overall dimension
Pinhole
Dielectric breakdown
voltage
Conductor resistance Thickness Width Thickness Width Thickness Width
Unit mm mm mm mm mm mm Pcs/m kV Ω/km
- 1.0 1.1 0.025 0.025 - -
3 3.0 20.84
max 1.03 1.16 0.04 0.04 1.08 1.08
min 0.97 1.04 0.01 0.01 - -
122
Appendix G
Properties of bandaging electrical tape 1339
Properties Typical value
Thickness 6.5 mils (0,165 mm)
Breaking Strength 275 lb./in (481 N/10 mm)
Elongation 5%
Adhesion to Steel 35 oz/in (3,81 N/10 mm)
Dielectric Strength 5,500V
Temperature Class 130°C
Insulation Resistance 1x105 megohms
Electrolytic Corrosion Factor 1.0
Appendix H
Typical Electrical Properties of DuPont™ Nomex® 410
123