In recent years, the field of electrical machines, electrical drives and power electronics has undergone some serious development and its effect can easily be observed in the fields of transportation (automotive), aerospace, renewable energy generation, domestic appliance and industrial automation. An electrical motor being a device which converts electrical power to mechanical power, it is the largest end consumer of electrical energy consuming more than twice as much as lighting. So, it is very important that the efficiency of such systems be improved as much as possible so as to achieve minimum losses. In many applications today, the main losses involved in the electrical drive systems are the machine losses and the power converter losses. It is important for these losses to be evaluated at the design stage of these systems so as to permit the designers to make a compromise between performance and cost depending on the application. So the losses and the efficiency are two important parameters which cannot be neglected by designers of electrical machines. In recent times, many machine configurations have been developed so as to obtain a suitable power and torque density and high efficiency, which would be employed in many applications. However, these developments have brought to light the advantages and disadvantages of some machines in some given applications. So taking a look at the switched reluctance machine (SRM), its robust structure have gained favors in many applications, but it equally presents some disadvantages which cannot also be neglected in certain fields of application. The Variable flux reluctance machine (VFRM) exhibits some characteristics which might be expected to gain grounds in applications where the SRM had short comings. The main objective of this thesis is to compare the SRM and VFRM with main focus on the evaluation and comparison of the machine losses and to identify which of them can have a higher efficiency. The first chapter of this thesis introduces both SRM and VFRM including their structure, operating principle, advantages and disadvantages. The second chapter is on the method of supplying both the SRM and VFRM. The power converter circuits and the control methods are examined in this chapter. The third chapter is based on the analysis of the VFRM under certain operating conditions so as to have an idea on some of the characteristics of this machine which were not mentioned in the literature. This analysis is carried out by performing 2D FEM transient simulations on ANSYS MAXWELL. A model of the machine is created and the various analyses are performed on the model. In this thesis, no analysis was performed on the SRM as in the case of VFRM because it is a machine with a mature theory and much literature has been written on it. The fourth chapter is about the evaluation of machine losses in the SRM and VFRM, precisely the core losses and the winding losses. The evaluation of the core losses is performed analytically and by FEM for both machines. In this chapter 2D FEM transient simulations are performed on the SRM and VFRM models created in ANSYS MAXWELL. The necessary settings are made on the materials used for the rotor and stator cores of the machines for the evaluation of the core losses. The Steinmetz based core loss model shall be employed by making use of the Steinmetz equation and the improved Steinmetz equation. The results of both machines shall be compared so as to have a view of which of the machine is more efficient. Equally, the winding losses shall also be evaluated for both machines and its components shall also be determined and compared.
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Comparison between the switched reluctance machine and variable flux reluctance machine
YOUNDO, LUCIEN NAMANGA
2017/2018
Abstract
In recent years, the field of electrical machines, electrical drives and power electronics has undergone some serious development and its effect can easily be observed in the fields of transportation (automotive), aerospace, renewable energy generation, domestic appliance and industrial automation. An electrical motor being a device which converts electrical power to mechanical power, it is the largest end consumer of electrical energy consuming more than twice as much as lighting. So, it is very important that the efficiency of such systems be improved as much as possible so as to achieve minimum losses. In many applications today, the main losses involved in the electrical drive systems are the machine losses and the power converter losses. It is important for these losses to be evaluated at the design stage of these systems so as to permit the designers to make a compromise between performance and cost depending on the application. So the losses and the efficiency are two important parameters which cannot be neglected by designers of electrical machines. In recent times, many machine configurations have been developed so as to obtain a suitable power and torque density and high efficiency, which would be employed in many applications. However, these developments have brought to light the advantages and disadvantages of some machines in some given applications. So taking a look at the switched reluctance machine (SRM), its robust structure have gained favors in many applications, but it equally presents some disadvantages which cannot also be neglected in certain fields of application. The Variable flux reluctance machine (VFRM) exhibits some characteristics which might be expected to gain grounds in applications where the SRM had short comings. The main objective of this thesis is to compare the SRM and VFRM with main focus on the evaluation and comparison of the machine losses and to identify which of them can have a higher efficiency. The first chapter of this thesis introduces both SRM and VFRM including their structure, operating principle, advantages and disadvantages. The second chapter is on the method of supplying both the SRM and VFRM. The power converter circuits and the control methods are examined in this chapter. The third chapter is based on the analysis of the VFRM under certain operating conditions so as to have an idea on some of the characteristics of this machine which were not mentioned in the literature. This analysis is carried out by performing 2D FEM transient simulations on ANSYS MAXWELL. A model of the machine is created and the various analyses are performed on the model. In this thesis, no analysis was performed on the SRM as in the case of VFRM because it is a machine with a mature theory and much literature has been written on it. The fourth chapter is about the evaluation of machine losses in the SRM and VFRM, precisely the core losses and the winding losses. The evaluation of the core losses is performed analytically and by FEM for both machines. In this chapter 2D FEM transient simulations are performed on the SRM and VFRM models created in ANSYS MAXWELL. The necessary settings are made on the materials used for the rotor and stator cores of the machines for the evaluation of the core losses. The Steinmetz based core loss model shall be employed by making use of the Steinmetz equation and the improved Steinmetz equation. The results of both machines shall be compared so as to have a view of which of the machine is more efficient. Equally, the winding losses shall also be evaluated for both machines and its components shall also be determined and compared.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/142775