Despite its simple construction, robustness and low manufacturing cost, the application areas of SR motors are remained limited due to the high level of acoustic noise and torque ripple. In this thesis work, two different type of controllers are designed and implemented in order to minimize the acoustic noise and torque ripple which are considered as the major problems of SR motors. In this scope, first the possible acoustic noise sources are investigated. A sliding mode controller is designed and implemented to reduce the shaft torque ripple which is considered as a major source of acoustic noise. The performance of the controller is experimentally tested and it is observed that especially in low speed region reduction of torque ripple is significant. The torque ripple minimization performance of the controller is also tested at different speeds and the acoustic noise levels are recorded simultaneously. Comparing the noise mitigation with the noise reduction the correlation between the acoustic noise and shaft torque ripple is investigated. The results obtained from this investigation indicated that the torque ripple is not a major source of acoustic noise in SR motors. After this finding, radial force which is the other possible acoustic noise source of SRM is taken into consideration. The effects of control parameters on radial force and the motor efficiency are investigated via simulations. With the intuition obtained from this analysis, a switching angle neuro-controller is designed to minimize the peak level of radial forces. The performance of the mentioned controller is verified through noise records under steady state conditions. Regarding to the radial force simulations and the acoustic noise measurements, it is deduced that the radial force is the major source of acoustic noise. On the other hand, another controller is designed and implemented which increases the average torque per ampere value in order to increase the efficiency of the motor. It is seen that this controller has a good effect on increasing the efficiency but does not guarantee to operate at maximum efficiency.

Recently, permanent magnet assisted (PMa)-synchronous reluctance motors (SynRM) have been considered as a possible alternative motor drive for high performance applications. In order to have an efficient motor drive, performing of three steps in design of the overall drive is not avoidable. These steps are design optimization of the motor, identification of the motor parameter and implementation of an advanced control system to ensure optimum operation. Therefore, this dissertation first deals with the design optimization of the Permanent Magnet Assisted Synchronous Reluctance Motor (PMa-SynRM). Various key points in the rotor design of a low cost PMa-SynRM are introduced and their effects are studied. Finite element approach has been utilized to show the effects of these parameters on the developed average electromagnetic torque and the total d-q inductances. As it can be inferred from the name of the motor, there are some permanent magnets mounted in the rotor core. One of the features considered in the design of this motor is the magnetization of the permanent magnets mounted in the rotor core using the stator windings to reduce the manufacturing cost. At the next step, identification of the motor parameters is discussed. Variation of motor parameters due to temperature and airgap flux has been reported in the literatures. Use of off-line models for estimating the motor parameters is known as a computationally intensive method, especially when the models include the effect of cross saturation. Therefore in practical applications, on-line parameter estimation is favored to achieve a high performance control system. In this dissertation, a simple practical method for parameter estimation of the PMa-SynRM is introduced. Last part of the dissertation presents one advanced control strategy which utilized the introduced parameter estimator. A practical Maximum Torque Per Ampere (MTPA) control scheme along with a simple parameter estimator for PMa-SynRM is introduced. This method is capable of maintaining the MTPA condition and stays robust against the variations of motor parameters. Effectiveness of the motor design procedure and the control strategy is validated by presenting simulation and experimental results of a 1.5 kW prototype PMa-SynRM, designed and manufactured through the introduced design method.

In this thesis different methods of optimizing line start permanent magnet motor (LSPM) for magnet cost reduction is studied. Influence of different parameters has been studied by simulating magneto-static and transient FEM models of the machine. Finally a motor design of a LSPM with high rotor saliency has been proposed. The first method investigated is the use of flux barriers in LSPM and its effect on the magnetic flux leakage. The flux barriers reduce the flux leakage and hence help in reducing magnet volume. The second method studied is the use of two different grades of magnets. Using low price magnets help in reducing the total magnet cost without reducing the air gap flux density. The reduction in NdFeB magnet volume is not substantial by using both the methods mentioned above. The third method investigated is increasing the saliency of the rotor by introducing flux barriers and reducing the corresponding magnet volume. Both the magneto static and transient models are used to study the effect of different parameters of the motor. The placement and volume of magnet plays a critical role in motor performance. At first, the developed reluctance torque of the motor is maximized by doing parametric study and then magnets are placed in slots to achieve the required efficiency and power factor. The motor is simulated with NdFeB magnets and with Ferrite magnets. It has been found that using high saliency LSPM motor the NdFeB magnet volume can be reduced significantly. It is also shown that the same performance of motor (as compared to the motor with NdFeB magnets) can be achieved by using Ferrite magnets. The volume of Ferrite magnet required will be larger but still cost-wise using Ferrite is an attractive choice. Therefore, a design of motor is proposed using both NdFeB magnets and Ferrite magnets. Finally, the performance of proposed LSPM motor with high saliency is compared with that of an induction motor.

This dissertation contains a comprehensive analysis of both non-coupled and mutually coupled switched reluctance motors with concentrated windings for an electric bicycle traction application. Multiple pole configurations are analyzed and compared for each motor type. Includes magnetic design, thermal analysis, and structural analysis. A prototype is designed, manufactured, and validated. / This thesis discusses the design of both a conventional non-coupled switched reluctance motor (CSRM) and a mutually-coupled SRM (MCSRM) for an exterior rotor e-bike application. Several novel pole configurations were analyzed for each machine type, and the performance of the final CSRM and MCSRM designs were compared for this application. A commercially available e-bike permanent magnet synchronous motor (PMSM) was purchased, reverse engineered, and validated to define the geometry constraints and performance targets for the designs. Since switched reluctance motors do not use rare-earth permanent magnets, they are often seen as a potential low-cost alternative to permanent magnet machines. The goal of this research is to explain the relative advantages of CSRMs and MCSRMs when compared to PMSM machines for a direct-drive e-bike application. The final CSRM and MCSRM designs are analyzed in detail; electromagnetic, controls, thermal, and structural considerations are all studied. A prototype of the final CSRM design was manufactured and validated experimentally, using a dynamometer setup. The finalized CSRM design is shown to be competitive with the PMSM machine when considering torque output, and is superior in terms of peak efficiency, and high speed torque performance. However, the CSRM noise output and torque ripple were not compared to the PMSM, and a less-common asymmetric-bridge converter is required for the CSRM, which may hinder the ability for the machine to be implemented into existing e-bike packages. The high speed torque performance of the MCSRM is shown to be inferior to both the CSRM and PMSM, as is the torque quality and efficiency. The MCSRM is shown to be highly resistant to saturation which gives it the potential for high torque output at low speed (if thermal limits are not breached), though low saturation levels also contribute to low machine power factor. The MCSRM may be better suited to lower speed, high torque applications, for this reason. / Thesis / Doctor of Philosophy (PhD) / This thesis studies the design process and analysis of two different motor types, for an electric bicycle application. They are designed to replace a commercially available permanent magnet synchronous motor (PMSM). This type of motor is typically expensive due to the rare-earth magnet material it requires. The two motors discussed in this thesis are switched reluctance motors (SRMs), which do not require magnet material, and thus have the potential to save cost (in addition to other benefits). One of the SRMs has magnetic fields that are independently controlled (CSRM), and one has fields that are controlled together to produce torque (MCSRM). The magnetics, control, thermal, and structural aspects of the CSRM and MCSRM are studied in detail. Novel geometry considerations (i.e. novel pole configurations) which impact the magnetics of each machine are compared to find the best-performing configuration for each machine type.

A finalidade inicial deste estudo é desenvolver uma metodologia de análise da ondulação de torque de um motor de relutância chaveado especial bifásico com 4 pólos no estator e 2 no rotor (MRC 4/2) através de dados experimentais de aceleração. De forma a validar o método proposto, são apresentados resultados experimentais de aceleração obtidos com dois rotores: o rotor de referência e o rotor otimizado. Uma vez alcançados os objetivos de otimização do torque através da modificação da geometria do rotor, implementou-se um estudo complementar de modo a explorar a vibração e a ondulação de torque, do ponto de vista do acionamento. Desta forma, desenvolveu-se uma plataforma digital de testes, onde os dados de aceleração podem ser monitorados no domínio da frequência, e os parâmetros de controle do acionamento, tais como, a velocidade, os ângulos de ligamento e condução são flexíveis e podem ser alterados através de programa. A plataforma digital foi concebida a partir de um kit de desenvolvimento (eZdsp LF2407A) associado a uma interface de controle serial, desenvolvida a partir de um aplicativo LabView, instalado num microcomputador. / The initial purpose of this study is to develop a methodology of analysis of the torque ripple of a two-phase special SRM 4/2 using acceleration experimental data. In order to validate the proposed method, acceleration experimental results are presented, these results were obtained with two rotors: the reference rotor and the optimized rotor. Once the torque optimization objectives were reached by modifying the rotor geometry, a complementary study from the point of view of motor drive vibration and torque ripple optimization was carried out. Thus, a test digital setup was developed, where the acceleration data could be monitored, in the frequency domain, and the drive control parameters, such as speed, turn-on and dwell angles, and phase current were flexible and could be altered by program. The test digital setup was conceived using a development kit (eZdsp LF2407A) associated with a serial control interface developed on a LabView application, installed in a microcomputer.

A finalidade inicial deste estudo é desenvolver uma metodologia de análise da ondulação de torque de um motor de relutância chaveado especial bifásico com 4 pólos no estator e 2 no rotor (MRC 4/2) através de dados experimentais de aceleração. De forma a validar o método proposto, são apresentados resultados experimentais de aceleração obtidos com dois rotores: o rotor de referência e o rotor otimizado. Uma vez alcançados os objetivos de otimização do torque através da modificação da geometria do rotor, implementou-se um estudo complementar de modo a explorar a vibração e a ondulação de torque, do ponto de vista do acionamento. Desta forma, desenvolveu-se uma plataforma digital de testes, onde os dados de aceleração podem ser monitorados no domínio da frequência, e os parâmetros de controle do acionamento, tais como, a velocidade, os ângulos de ligamento e condução são flexíveis e podem ser alterados através de programa. A plataforma digital foi concebida a partir de um kit de desenvolvimento (eZdsp LF2407A) associado a uma interface de controle serial, desenvolvida a partir de um aplicativo LabView, instalado num microcomputador. / The initial purpose of this study is to develop a methodology of analysis of the torque ripple of a two-phase special SRM 4/2 using acceleration experimental data. In order to validate the proposed method, acceleration experimental results are presented, these results were obtained with two rotors: the reference rotor and the optimized rotor. Once the torque optimization objectives were reached by modifying the rotor geometry, a complementary study from the point of view of motor drive vibration and torque ripple optimization was carried out. Thus, a test digital setup was developed, where the acceleration data could be monitored, in the frequency domain, and the drive control parameters, such as speed, turn-on and dwell angles, and phase current were flexible and could be altered by program. The test digital setup was conceived using a development kit (eZdsp LF2407A) associated with a serial control interface developed on a LabView application, installed in a microcomputer.

The reluctance torque of switched reluctance motor could drive the rotor directly. Rotor doesn¡¦t need to be made from permanent magnet and the demagnetization and heat emission problems can be avoided. There are also a lot of advantages, such as the low cost, high efficiency, high stability and high hot emission, make it very attractive to the engineers and researchers. The dual-flange-pole rotor structure will induce non-linear magnetic filed in the air gap between armature and rotor, so the reluctance torque is not easy to handle. The switched reluctance motor is considered hard to control at the early stages of development. In recently years, with the rapid improvement of power electronic devices and microprocessor chips, the engineers and researchers pay more attentions to overcome the difficulties encountered in both the software and hardware step by step. It can now exert the motor¡¦s capability to contend with the inductor motor and the alternating current motor. Furthermore, it is more advantageous than others in the high energy density, high temperature and adverse circumstances. It has obviously caught caused the industry¡¦s attention and the academia's research interests. The work of this is to design and develop a drive system for the switched reluctance motor drive system by using the 32-bit floating point Digital Signal Processor, and operate it in coordination with the peripheral circuits. Finally, the study will integrate the graph control programming to design a monitoring and control system with Man-Machinery Interface (MMI) for monitoring voltage, current and speed of the switched reluctance motor drive system.

Switched Reluctance Machine (SRMs) are receiving significant attention for industries and homes in the last decade. Due to their rugged brushless design, high reliable and an outstanding performance over a wide speed range. The stator and rotor of an SRM have a double salient pole and the rotor has no windings and magnets, its torque generating is quite nonlinear and has high torque ripple. Therefore, sophisticated switching and control technologies are needed to improve its driving performance. The cost and performance of SRM drives are highly dependent on the converter topologies and motor structure, so that developments in the convert topologies have been made in parallel with motor design. The objective of this thesis is proposed three phase Switched Reluctance Machine using a fly back resistor C Dump Converter to replace the tradition Bridge Converter. It can reduce switching losses, to reduce converter production cost with a simpler circuit. At the end, a digital signal processor based control system is used to test the laboratory make drives .

The switched reluctance motor (SRM) is receiving attention because of its merits: high operating temperature capability, fault tolerance, inherent shoot-through preventing inverter topology, high power density, high speed operation, and small rotor inertia. Rotor position information plays a critical role in the control of the SRM. Conventionally, separate position sensors, are used to obtain this information. Position sensors add complexity and cost to the control system and reduce its reliability and flexibility. In order to overcome the drawbacks of position sensors, this dissertation proposed and investigated a position sensorless control system that meets the needs of an electric actuator application. It is capable of working from zero to high speeds. In the control system, two different control strategies are proposed, one for low speeds and one for high speeds. Each strategy utilizes a state observer to estimate rotor position and speed and is capable of 4 quadrant operation. In the low speed strategy a Luenberger observer, which has been named the inductance profile demodulator based observer, is used where a pulse voltage is applied to the SRMs idle phases generating triangle shaped phase currents. The amplitude of the phase current is modulated by the SRMs inductance. The current is demodulated and combined with the output of a state observer to produce an error input to the observer so that the observer will track the actual SRM rotor position. The strategy can determine the SRMs rotor position at standstill and low speeds with torques up to rated torque. Another observer, named the simplified flux model based observer, is used for medium and high speeds. In this case, the flux is computed using the measured current and a simplified flux model. The difference between the computed flux and the measured flux generates an error that is input to the observer so that it will track the actual SRM rotor position. Since the speed ranges of the two control stragegies overlap, the final control system is capable of working from zero to high speed by switching between the two observers according to the estimated speed. The stability and performance of the observers are verified with simulation and experiments.

Thermal modeling is an important aspect of electric motor design. Numerous techniques exist to predict the temperatures in a motor, and they can be incorporated in the design of a thermal model for a new type of electric motor. This work discusses the available modeling techniques and determines which methods are applicable for medium-sized motors with either natural convection or forced convective cooling over irregular geometry. A time-dependant thermal model, with thermal transport parameters based upon geometric and simplified air flow information, is developed based on a discrete lumped parameter model with several modifications to improve accuracy. The model was completed with the aid of nine experiments, and the result is a thermal model that exhibits an absolute error of less than 6.1??C for the nine test runs at three different currents between 8.4 A rms and 28.2 A rms and three cooling levels, natural, 10.7 CFM and 24.4 CFM.