The doctoral thesis consists of nine chapters which reflect the progress of the research over time, as illustrated in Fig. 1.5.
Chapter 1 starts with an introduction of SMC and electrical traction machine in passenger cars. Subsequently, the targets and the design specifications of the research are presented. Finally, the main scientific contributions and the outline of this thesis are summarized.
Chapter 2 describes the classification of electrical machine depending on the main flux in the air gap and the relative direction between flux path and rotor rotation. Subsequently, the main topologies of PM excited AFM and TFM are described. At last, the most important literatures about the applications of SMC in RFM, AFM and TFM are reviewed and summarized.
A full characterization of SMC is the basis of FEA. Chapter 3 deals with the measurement of the electromagnetic properties of different SMC including the magnetization curve and iron losses. On this basis, an iron loss model has been developed which is then used in the post-process of FEM to calculate the iron losses in electrical machine. In order to validate the model, a test system con-sisting of a yoke and a tooth made from the same SMC has been built.
In Chapter 4, the development of a 3D FEM simulation platform is described.
First of all, the function and structure of the simulation platform are introduced.
Subsequently, the most important components integrated into the simulation platform are explained in details. A winding editor to calculate the most im-portant properties of double layer concentrated winding has been developed.
Furthermore, an efficient method to calculate the iron losses of AFM based on limited FEA for 1/6 electrical period is presented.
1.5 Outline of the work
Based on the measurement of SMC and the developed simulation platform, the electromagnetic designs of an AFM and a TFM have been carried out and de-scribed in Chapter 5 and Chapter 6 respectively. Based on the comparison among the designed novel topologies and current RFM described in Chapter 7, it is concluded that the novel AFM is the most suitable structure for the applica-tion of SMC.
In order to validate the FEM results, a prototype of the designed AFM should be built and measured. For this purpose, a mechanical construction is proposed in Chapter 8 which is very challenging due to the large axial force between the stator and rotor. On this basis, the strength and vibration analyses are performed to validate the mechanical construction. In addition, the temperature plays an important role in AFM because both adhesive and PM are sensitive to it. For this reason, the temperature is calculated based on the coupled thermal and CFD analysis. Subsequently, a lumped parameter thermal model has been developed to calculate the temperature efficiently with acceptable accuracy.
The manufacturing and measurement of the AFM prototype are described in Chapter 9. The experimental data including the back-EMF profiles, the losses, the torque, the informative efficiency map and so on are presented and compared with simulation. The possible reasons rendering the deviation between the mea-surement and simulation are discussed in this chapter as well.
Chapter 10 summarizes the major work carried out during the project. At last, the most relevant conclusions drawn from the previous work about the SMC, the topology of electrical machine and the future work are presented.
SMC measurement (3) Simulation platform (4)
Mechanical construction and analysis (8)
Prototyping and measurement (9) Topology comparison (5,6,7)
Figure 1.5. Structure of the doctoral thesis
2
Topology of Electrical Machine
In the past years, a lot of different topologies of the electrical machine have been developed. These topologies can be classified with many different methods. For instance, electrical machine can be divided into the direct current machine and the alternating current machine depending on the current waveform. Consid-ering the existence of PM, electrical machine can be categorized as PM and electrically excited machine.
As illustrated in Fig. 2.1, the AFM is featured by the main magnetic flux flowing axially in the air gap, while the magnetic flux in RFM flows radially in the air gap. Furthermore, the main magnetic flux path is longitudinal to the rotational direction of the rotor in longitudinal flux machine (LFM), while the TFM has a magnetic flux path transverse to the rotor movement. In this thesis, two different kinds of electrical machines are investigated which are the longitudinal axial flux machine and the radial transverse flux machine respectively. For the sake of simplicity, the abbreviations AFM and RFM are used.
In this chapter, the classification of RFM and the reference machine for the com-parison with novel topologies are introduced at first. Subsequently, the classical topologies of AFM and TFM are presented respectively. Thirdly, the mathemat-ical model of PM excited synchronous machine based on the d-, q-coordinate system is presented which can be utilized to analyze the PM excited RFM, AFM and TFM. Finally, the most relevant literatures about the applications of SMC in the three different kinds of electrical machines are summarized.
Relative direction of the rotor movement to the flux path
LFM Transversalflussmaschine
AFMRFM
Directionofmainmagneticfluxintheairgap
Figure 2.1. Classification of the electrical machines