In the emergence of switched reluctance motors to the commercial market, two-phase motors have received relatively little attention. Higher power and industrial applications have focused on the use of three and occasionally four phase machines, while low cost applications demanding only modest performance have largely been the domain of single phase machines. By contrast, while two phase systems have been the subject of occasional studies, they have not been widely applied. Two phase systems represent a compromise between the higher cost but higher performance three phase machines, and the lower cost but lower performance single phase systems. They do not suffer from the same magnitude of peak to peak torque ripple that single phase machines experience due to their wide zero torque arcs. Yet two phase systems keep a relatively low component count in their power-converter designs. The primary drawback to two phase motors is the difficulty of torque production at startup speeds. Although sizably reduced from single phase machines, the zero torque regions in two phase machines can still result in rotor lock unless steps are taken to circumvent them. These steps can include measures such as: placement of permanent magnets or other means to ensure the rotor is positioned outside of these zero torque regions when at rest, mechanically spinning the motor before energizing the phase windings on startup, shaping of the rotor or stator poles to extend the positive torque regions of each phase, or use of the machines mutual inductance with both phases energized to produce enough torque to initiate motion. This project is intended to develop a variable speed controller for a 4:6 two-phase switched reluctance motor. The motor is to operate in all four quadrants, and is to demonstrate self starting capability. The controller is also supposed to produce signals needed to operate the motor with multiple converter designs. Two different converter designs will be built and tested with the converter. One makes use of a single switch and two diodes per phase, the other has one switch and one diode per phase plus a common switch and common diode shared by all phases. There are many possible applications of the system being developed in this project. Any application needing four quadrant operation while still being constrained by low cost requirements would be ideal. Some examples include washing machines, power tools, and low power industrial applications. / Master of Science

Switched Reluctance Motors (SRMs) are gaining recognition due to their robust design, cost-effectiveness, fault tolerance, and reliable high-speed performance, positioning them as promising alternatives to traditional electric motors. However, SRMs face high torque ripples, vibration, acoustic noise, and nonlinear modeling complexities. Through careful geometry design optimization, these drawbacks can be mitigated. Design optimization for SRMs is a multi-objective and nonlinear problem that requires an accurate finite element analysis (FEA) model to relate designable parameters to output objectives. The geometric design process follows a multi-stage and iterative approach, leading to prohibitive computational time until the optimal design is reached. Machine learning algorithms (MLAs) have recently acquired attention in electric machine design. This study introduces an extensive analysis of various MLAs applied to SRM modeling and design. Additionally, it presents a robust framework for a comprehensive evaluation of these MLAs, facilitating the selection of the optimal machine learning topology for SRM design. Existing research on the geometry optimization of SRMs using MLAs has focused only on the machine’s static characteristics. This thesis introduces an advanced optimization method utilizing an MLA to act as a surrogate model for both static and dynamic characteristics of the SRM. The dynamic model incorporates conduction angles optimization to enhance the torque profile. The proposed MLA is applied to map out the SRM geometrical parameters, stator and rotor pole arc angles and their dynamic performance metrics, such as average torque and torque ripples. The optimal design improves the average torque and significantly reduces the torque ripples. Radial forces constitute a critical objective that should be considered alongside average torque, efficiency, and torque ripple in the design optimization of SRMs. Accurate modeling of radial forces is a prerequisite for optimizing motor geometry to mitigate their adverse effects on vibrations and acoustic noise. This work presents an MLA-based surrogate model for the most influential radial force harmonic components, facilitating the integration of radial force reduction into a multi-objective optimization framework. The proposed optimization framework employs two MLA-based surrogate models: the first correlates SRM pole arc angles with average torque and torque ripples, while the second models the most significant radial force harmonics. A genetic algorithm leverages these surrogate models to predict new geometrical parameters that enhance the SRM's torque profile and reduce radial forces. The optimization framework significantly reduced torque ripples and radial forces while slightly increasing average torque. The optimal design candidates were verified using FEA and MATLAB simulations, confirming the effectiveness of the proposed method, which offers significant computational time savings compared to traditional FEA techniques. / Thesis / Doctor of Philosophy (PhD)

A máquina a relutância chaveada ganhou considerável atenção da comunidade científica com o desenvolvimento da eletrônica de potência e é considerada hoje uma máquina elétrica promissora para algumas aplicações, principalmente aquelas onde há a necessidade de operação em velocidade variável seja como motor ou como gerador. Sendo assim, este trabalho apresenta a dinâmica de funcionamento de uma máquina a relutância chaveada, com uma estrutura 6 x 4, ou seja contendo seis pólos no estator e quatro pólos no rotor, operando no modo gerador. A dinâmica de funcionamento é apresentada e comparada através de resultados experimentais e resultados simulados em ambiente Matlab/Simulink. Os resultados experimentais foram possíveis devido a construção de um protótipo da máquina e da montagem de uma bancada de testes. O projeto desenvolvido para construção do protótipo e da bancada de testes é apresentado neste trabalho. / Switched reluctance machines have received considerable attention from the scientific community due to advances in power electronics, and now is considered a promising electric machine for some applications, especially where variable speed operations are needed for motor or generator. Therefore, this work presents the dynamics of a switched reluctance machine, operating as a generator, with 6 x 4 structure, i.e., six stator poles and four poles in the rotor. Experimental results, which were obtained from a machine prototype installed on a test bench, were compared with Matlab/Simulink computational simulations. The designing aspects for the prototype construction are also discussed in this work.

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.

A máquina a relutância chaveada ganhou considerável atenção da comunidade científica com o desenvolvimento da eletrônica de potência e é considerada hoje uma máquina elétrica promissora para algumas aplicações, principalmente aquelas onde há a necessidade de operação em velocidade variável seja como motor ou como gerador. Sendo assim, este trabalho apresenta a dinâmica de funcionamento de uma máquina a relutância chaveada, com uma estrutura 6 x 4, ou seja contendo seis pólos no estator e quatro pólos no rotor, operando no modo gerador. A dinâmica de funcionamento é apresentada e comparada através de resultados experimentais e resultados simulados em ambiente Matlab/Simulink. Os resultados experimentais foram possíveis devido a construção de um protótipo da máquina e da montagem de uma bancada de testes. O projeto desenvolvido para construção do protótipo e da bancada de testes é apresentado neste trabalho. / Switched reluctance machines have received considerable attention from the scientific community due to advances in power electronics, and now is considered a promising electric machine for some applications, especially where variable speed operations are needed for motor or generator. Therefore, this work presents the dynamics of a switched reluctance machine, operating as a generator, with 6 x 4 structure, i.e., six stator poles and four poles in the rotor. Experimental results, which were obtained from a machine prototype installed on a test bench, were compared with Matlab/Simulink computational simulations. The designing aspects for the prototype construction are also discussed in this work.

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.

The development of an add-on sensorless position estimator for a 4.8 m Linear Switched Reluctance Machine (LSRM) with minimal modifications to the transducer-based controller is investigated for the first time in this study. LSRMs require position feedback for closed-loop control but present a low cost, high energy efficiency alternative for linear actuation due to their rugged construction and single-sided excitation. Mechanical position transducers mounted on the vehicle are expensive and can impact reliability. The use of a sensorless position estimator removes all electronics from the passive vehicle, resulting in considerable reductions in cost, maintenance, and mechanical complexity. This study examines the use of an add-on processor and data acquisition system for sensorless position estimation. An approach exploiting the active phase windings is used to preserve the normal operation of the transducer-based DSP controller with the goal of limiting reductions in high performance features such as force ripple reduction and velocity control [3]. The estimator system is retrofit to the transducer-based DSP controller by mimicking the output of a mechanical position sensor by emulating a Quadrature encoder. The feasibility and design issues for an add-on or retrofit position estimator are investigated. Although sensorless schemes for rotary Switched Reluctance Machines (SRMs) have been studied in detail, the problem of sensorless implementations for LSRMs has not been addressed. Experimental validation of the proposed sensorless estimation scheme is attempted, but closed-loop operation is not achieved successfully due to air gap fluctuations. In depth analysis of the sources and propagation of error is presented. / Master of Science

Para acompanhar o atual crescimento de demanda energética mundial, novas topologias de geradores estão sendo pesquisadas, estando nesse nicho o Gerador a Relutância Chaveado. Para seu correto funcionamento é necessário que técnicas de controle sejam empregadas para garantir níveis estáveis de tensão gerada mediante variações de velocidade e/ou carga. Portanto, o objetivo deste trabalho é apresentar uma metodologia de um controlador fuzzy da tensão gerada para a máquina em questão. Uma simulação em Matlab Simulink é apresentada para um sistema de geração de energia utilizando um gerador a relutância chaveado integrada com a malha de controle fuzzy. Resultados da dinâmica do funcionamento do controlador fuzzy são apresentados. O Controlador fuzzy proposto apresentou bom desempenho ao manter a tensão gerada em níveis desejáveis frente a distúrbios de carga e de variação de velocidade no eixo do gerador. Trata-se de um controlador robusto e versátil que garante estabilidade de tensão gerada mesmo com a operação do sistema com velocidade variável e/ou variação de carga. / Due to the growing demand of electric power energy, the engineering has to evolve by producing new efficient techniques and low cost equipment. Therefore, new electric power generator topologies have been studied, mainly switched reluctance generators due to their simple structure, reliability and low cost of fabrication. In order for a good operation of a switched reluctance generator, control techniques have to be applied to guarantee stable voltage levels under variable speed and load conditions. Hence, the objective of this work is to present a methodology based on fuzzy voltage controller for switched reluctance machine. Simulations are achieved in Matlab/Simulink for a power energy generation system using a switched reluctance generator with a fuzzy control loop. Results of the dynamic response of such controller are presented. The fuzzy controller could obtain good performance maintaining voltage levels in desired range. Therefore, the proposed controller showed to be robust, versatile and guarantee the voltage stability under speed and load variations.

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.

Para acompanhar o atual crescimento de demanda energética mundial, novas topologias de geradores estão sendo pesquisadas, estando nesse nicho o Gerador a Relutância Chaveado. Para seu correto funcionamento é necessário que técnicas de controle sejam empregadas para garantir níveis estáveis de tensão gerada mediante variações de velocidade e/ou carga. Portanto, o objetivo deste trabalho é apresentar uma metodologia de um controlador fuzzy da tensão gerada para a máquina em questão. Uma simulação em Matlab Simulink é apresentada para um sistema de geração de energia utilizando um gerador a relutância chaveado integrada com a malha de controle fuzzy. Resultados da dinâmica do funcionamento do controlador fuzzy são apresentados. O Controlador fuzzy proposto apresentou bom desempenho ao manter a tensão gerada em níveis desejáveis frente a distúrbios de carga e de variação de velocidade no eixo do gerador. Trata-se de um controlador robusto e versátil que garante estabilidade de tensão gerada mesmo com a operação do sistema com velocidade variável e/ou variação de carga. / Due to the growing demand of electric power energy, the engineering has to evolve by producing new efficient techniques and low cost equipment. Therefore, new electric power generator topologies have been studied, mainly switched reluctance generators due to their simple structure, reliability and low cost of fabrication. In order for a good operation of a switched reluctance generator, control techniques have to be applied to guarantee stable voltage levels under variable speed and load conditions. Hence, the objective of this work is to present a methodology based on fuzzy voltage controller for switched reluctance machine. Simulations are achieved in Matlab/Simulink for a power energy generation system using a switched reluctance generator with a fuzzy control loop. Results of the dynamic response of such controller are presented. The fuzzy controller could obtain good performance maintaining voltage levels in desired range. Therefore, the proposed controller showed to be robust, versatile and guarantee the voltage stability under speed and load variations.