129 research outputs found

    Reduction in Eddy Current Loss of Special Rectangular Windings in High-Torque IPMSM Used for Wind Generator

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    A special rectangular winding structure, which has different cross-sectional shape but the same cross-sectional area for each turn, has been adopted in a high-torque IPMSM used for a wind generator to improve slot factor and heat dissipation. However, large eddy current loss occurs to the rectangular windings. According to this problem, this paper proposes three improvements to reduce the eddy current loss. Among them, removing a portion of windings and replacing a portion of windings with aluminum are discussed to realize a tradeoff between eddy current and copper losses. And adjusting the tooth-tip shape is discussed to suppress the magnetic flux passing through the windings by mitigating magnetic saturation around the tooth-tip. Additionally, manufacturing costs can also be reduced by adopting a portion of aluminum windings. Moreover, a 3-step-skewed rotor structure is discussed to reduce cogging torque and lower the start-up wind speed. And its influence on losses is also discussed. Furthermore, three models adopting round windings are made and discussed for comparison. The FEM (Finite Element Method) results show that compared with the three round windings models, the proposed model still has a better performance in the reduction of windings eddy current loss. Finally, a prototype machine is manufactured to verify the FEM results, and the experimental results show that the maximum efficiency of the prototype can exceed 97.5%

    Magnetic Material Modelling of Electrical Machines

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    The need for electromechanical energy conversion that takes place in electric motors, generators, and actuators is an important aspect associated with current development. The efficiency and effectiveness of the conversion process depends on both the design of the devices and the materials used in those devices. In this context, this book addresses important aspects of electrical machines, namely their materials, design, and optimization. It is essential for the design process of electrical machines to be carried out through extensive numerical field computations. Thus, the reprint also focuses on the accuracy of these computations, as well as the quality of the material models that are adopted. Another aspect of interest is the modeling of properties such as hysteresis, alternating and rotating losses and demagnetization. In addition, the characterization of materials and their dependence on mechanical quantities such as stresses and temperature are also considered. The reprint also addresses another aspect that needs to be considered for the development of the optimal global system in some applications, which is the case of drives that are associated with electrical machines

    Multiple Objective Co-Optimization of Switched Reluctance Machine Design and Control

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    This dissertation includes a review of various motor types, a motivation for selecting the switched reluctance motor (SRM) as a focus of this work, a review of SRM design and control optimization methods in literature, a proposed co-optimization approach, and empirical evaluations to validate the models and proposed co-optimization methods. The switched reluctance motor (SRM) was chosen as a focus of research based on its low cost, easy manufacturability, moderate performance and efficiency, and its potential for improvement through advanced design and control optimization. After a review of SRM design and control optimization methods in the literature, it was found that co-optimization of both SRM design and controls is not common, and key areas for improvement in methods for optimizing SRM design and control were identified. Among many things, this includes the need for computationally efficient transient models with the accuracy of FEA simulations and the need for co-optimization of both machine geometry and control methods throughout the entire operation range with multiple objectives such as torque ripple, efficiency, etc. A modeling and optimization framework with multiple stages is proposed that includes robust transient simulators that use mappings from FEA in order to optimize SRM geometry, windings, and control conditions throughout the entire operation region with multiple objectives. These unique methods include the use of particle swarm optimization to determine current profiles for low to moderate speeds and other optimization methods to determine optimal control conditions throughout the entire operation range with consideration of various characteristics and boundary conditions such as voltage and current constraints. This multi-stage optimization process includes down-selections in two previous stages based on performance and operational characteristics at zero and maximum speed. Co-optimization of SRM design and control conditions is demonstrated as a final design is selected based on a fitness function evaluating various operational characteristics including torque ripple and efficiency throughout the torque-speed operation range. The final design was scaled, fabricated, and tested to demonstrate the viability of the proposed framework and co-optimization method. Accuracy of the models was confirmed by comparing simulated and empirical results. Test results from operation at various torques and speeds demonstrates the effectiveness of the optimization approach throughout the entire operating range. Furthermore, test results confirm the feasibility of the proposed torque ripple minimization and efficiency maximization control schemes. A key benefit of the overall proposed approach is that a wide range of machine design parameters and control conditions can be swept, and based on the needs of an application, the designer can select the appropriate geometry, winding, and control approach based on various performance functions that consider torque ripple, efficiency, and other metrics

    Optimal Design of Special High Torque Density Electric Machines based on Electromagnetic FEA

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    Electric machines with high torque density are essential for many low-speed direct-drive systems, such as wind turbines, electric vehicles, and industrial automation. Permanent magnet (PM) machines that incorporate a magnetic gearing effect are particularly useful for these applications due to their potential for achieving extremely high torque density. However, when the number of rotor polarities is increased, there is a corresponding need to increase the number of stator slots and coils proportionally. This can result in manufacturing challenges. A new topology of an axial-flux vernier-type machine of MAGNUS type has been presented to address the mentioned limitation. These machines can attain high electrical frequency using only a few stator coils and teeth, which can simplify construction and manufacturing under certain conditions. Additionally, the inclusion of auxiliary small teeth within the stator main teeth can generate a noteworthy increase in output torque, making it a unique characteristic of this motor. By analyzing the operating principle of the proposed VTFM PM machine, possible pole-slot combinations have been derived. The process of designing an electric machine is complicated and involves several variables and factors that must be balanced by the designer, such as efficiency, cost, and performance requirements. To achieve a successful design, it is crucial to employ multi-objective optimization. Using a 3D FEA model can consider the impact of magnetic saturation, leakage flux, and end effects, which are not accounted for in 2D. Optimization using a 3D parametric model can offer a more precise analysis. Validating the machine\u27s performance requires prototyping a model and testing it under different operating conditions, such as speed and load, which is a crucial step. This approach provides valuable insights into the machine\u27s behavior, allowing the identification of any areas for improvement or weaknesses. A large-scale multi-objective optimization study has been conducted for an axial-flux vernier-type PM machine with a 3-dimensional (3D) finite element analysis (FEA) to minimize the material cost and maximize the electromagnetic efficiency. A detailed study for torque contribution has indicated that auxiliary teeth on each stator main teeth amplify net torque production. A prototype of optimal design has been built and tested

    RECENT TECHNIQUES ON OBSERVER DESIGN FOR DISTURBANCE ESTIMATION AND REJECTION IN PERMANENT MAGNET SYNCHRONOUS MOTORS

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    Permanent magnet synchronous machines (PMSMs) (either motor or generator) have attracted attention of research community comparing to other types of AC machines in the recent two decades. PMSMs are preferable than other AC machines in terms of large power-factor, broad speed of operation, compact proportions, and effective operation. Unfortunately, different sources of nonlinearities, model uncertainties, and external perturbations determine severity in a design of accurate speed control scheme for PMSMs. In the era of developing science and technologies, many advanced control solutions are proposed to control PMSMs. Although new solutions show their advantages comparing to traditional methods in terms of performance evaluation, practical realization of those algorithms could require expensive hardware with high computational capabilities. Furthermore, people in industry with less knowledge about the motor control may experience difficulties in using such advanced controllers on their own. Traditional PI/PID control schemes still work as a major control technique in modern industry, and in motor control as well. Numerous positive facts about the PI/PID schemes make such superiority of these control schemes. Firstly, the PI/PID can be implemented easily on most industrial software and hardware components. Secondly, while its scheme has clear mechanism of operation, most industrial processes could be controlled via the PI/PID scheme. These schemes are good in terms of small number of parameters to tune and tuning process itself could be very straightforward. Finally, implementation of the PI/PID controllers would require smaller time comparing to most proposed complex control solutions. It is studied that the traditional PI/PID controllers usually cannot deal with unpredictable disturbances, which in turn leads to degraded performance of an overall control system. Inspired by the advantages and widespread application of PI/PID control structure in industry, we propose a disturbance observer based composite control scheme which uses the PI-like controller for the feedback regulation and disturbance observer for estimation of lumped disturbances presented in a PMSM control system. Under this circumstance, this thesis work proposes three different control solutions for PMSM such as High-order disturbance observer-based composite control (HDOBCC), Disturbance rejection PI (DR-PI) control, and Hierarchical optimal disturbance observer-based control (HODOBC). Furthermore, to deeply understand the similarity and difference between the traditional disturbance observer-based control (DOBC) and active-disturbance rejection control (ADRC) schemes, this thesis also presents results of unification of these two control approaches in the speed control of a PMSM. The HDOBCC as the first method proposed in this thesis is designed to improve reference speed tracking performance of a PMSM under various operational conditions. A structure of the HDOBCC comprises a fuzzy-PI controller in a feedback stabilization part and novel high-order disturbance observer in a feedforward compensation part of the speed control system. The proposed controller is designed based on the research questions such as: firstly, although a fixed gain traditional PI controller is able to present satisfactory performance at some extent, still it does not guarantee such performance when sudden disturbances occur in a system; secondly, many disturbance observers designed for a PMSM in literature consider only a load torque as a disturbance, neglecting model uncertainties and parameter variations in design stage. Therefore, the HDOBCC is proposed such that it utilizes a fuzzy approach to determine parameters of the PI controller to overcome limitations of the fixed gain PI controller. Furthermore, the proposed scheme includes a high-order disturbance observer, which estimates not only the load torque, but also disturbances due to model uncertainties and parameter variations. Moreover, extended simulation and experimental studies are conducted to affirm performance of the HDOBCC under various form of the load torque. In addition to commonly tested step form of a load torque, severe forms of the load torque such as triangular form and sinusoidal form are tested with the proposed controller. Stability analysis of the closed-loop HDOBCC system is further provided. The next proposed method, DR-PI control, is designed by seeking answer for questions such as: firstly, although the traditional DOBC scheme applied for PMSM shows reasonable results in a PMSM control, its design can be limited to known actual parameters of the PMSM. In practice, actual parameters are usually not available, hence it could be hard to design the traditional DOBC in the absence of a plant information; secondly, for tuning a PI controller the traditional Ziegler-Nichols tuning approach still remains as one of the popular tuning approaches, however it does not give a rigorous explanation on selection of parameters during its design. Consequently, to answer these questions, the DR-PI control is designed for the PMSM speed control. The DR-PI control is designed such that it has a simple PI-like structure with intrinsic disturbance rejection mechanism determined by the parameters of a filtering element, desired plant model, and desired closed-loop system. Simulation and experimental validations are provided to validate the performance of the DR-PI. Furthermore, gain tuning mechanism and stability analysis of the closed-loop DR-PI-based speed control are also presented. The HODOBC scheme as a third proposed control scheme targets on the next research questions as: first, parameters of the traditional PI controller are mostly obtained by trial-and-error approach, which in turn may not guarantee satisfactory results; in a cascaded PMSM control, the outer speed loop performance highly depends on the performance of the inner current loop. The well-tuned speed control loop may degrade in performance, if the inner current loop is not tuned properly. To address these questions, we propose the HODOBC scheme, which consists of optimal PIlike controller in the feedback stabilization part and optimal extended-state observer (ESO) in the disturbance compensation part. The proposed HODOBC showed better performance when it is compared with other traditional controllers via experiments. Stability analysis is provided via the root locus approach. The study on unification of the DOBC and ADRC schemes has the following research question: the DOBC and ADRC are both used in estimation of total disturbance, but these two schemes are considered differently in literature. Hence, the study of both scheme is conducted to show the condition at which these two schemes show identical performance. The analysis of the traditional DOBC and ADRC schemes concludes that both scheme are equivalent in terms of performance characteristics if the dynamical delays of disturbance observers in each scheme are same. The results of analysis reveal that both scheme can be utilized to design a robust control system for PMSM, i.e. once the gains of disturbance observers can be calculated under the DOBC framework, further the disturbance rejection mechanism can be achieved via the ADRC framework. The results of PMSM control with the proposed control schemes have been tested on the Lucas-Nuelle DSP-based experimental setup

    Design, construction, analysis and control of a 3D printed permanent magnet motor prototype

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    Este proyecto de tesis comienza resaltando la importancia de la reducción de la huella de carbono y la disminución del uso de combustibles fósiles, para ello se hace una revisión exhaustiva de los diferentes tipos de motores eléctricos que se utilizan actualmente en la industria, con especial énfasis en los motores utilizados en el campo de la movilidad eléctrica, se explican los diferentes tipos de materiales magnéticos utilizados en la construcción de los motores, los imanes permanentes, y el conjunto Halbach. Además, este barrido incluye una explicación de las nuevas técnicas de fabricación emergentes, las diferentes tecnologías de impresión 3D, y la relevancia que la construcción de un motor eléctrico puede tener para la industria y el mundo académico local, regional y nacional. Tras el barrido inicial, se explican los diferentes tipos de motores síncronos de imanes permanentes (PMSM), partiendo de su modelo matemático hasta explicar el flujo magnético esperado a partir de la implementación del conjunto Halbach. Una vez que se dispone de estos elementos iniciales, se propone el modelo 3D inicial del motor y se realizan las primeras pruebas de impresión. Una vez construido el rototipo, se realizan las primeras pruebas para identificar la función de transferencia, se implementa el control PI en el motor para el control de velocidad, y se realiza un análisis termográfico para evaluar el comportamiento de la temperatura del motor funcionando sin carga. Finalmente, se muestran las conclusiones y el trabajo futuro del proyecto.This thesis project begins by highlighting the importance of reducing the carbon footprint and reducing the use of fossil fuels, for this a thorough review of the different types of electric motors currently used in the industry, with particular emphasis on the motors used in the field of electric mobility, the different types of magnetic materials used in the construction of motors, permanent magnets, and the Halbach array are explained. Additionally, this sweep includes an explanation of the new emerging manufacturing techniques, the different 3D printing technologies, and the relevance that the construction of an electric motor can have for the local, regional and national industry and academia. After the initial sweep, the different types of permanent magnet synchronous motors (PMSM) are explained, starting from their mathematical model to explaining the expected magnetic flux from implementing the Halbach array. Once these initial elements are available, the initial 3D model of the motor is proposed, and the first printing tests are performed. Once the prototype is built, initial tests are performed to identify the transfer function, PI control is implemented on the motor for speed control, and a thermographic analysis is performed to evaluate the temperature behavior of the motor running without load. Finally, the conclusions and future work of the project are shown.MaestríaMagíster en Ingeniería EléctricaContents 1 Introduction 2 1.1 Problem Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2 Justification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.3 Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.3.1 General objective . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.3.2 Specific objectives . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.4 State of the art . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.5 Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2 Permanent Magnet Synchronous Motor (PMSM) 13 2.1 Mathematical description of PMSM model . . . . . . . . . . . . . . . 13 2.1.1 Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2.1.2 Simplified Electrical Equations . . . . . . . . . . . . . . . . . 17 2.2 Surface mounted PMSM . . . . . . . . . . . . . . . . . . . . . . . . . 18 2.2.1 Projecting type . . . . . . . . . . . . . . . . . . . . . . . . . . 18 2.2.2 Inset type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 2.3 Interior PMSM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 2.4 Inner rotor PMSM . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 2.5 Outer rotor PMSM . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 2.6 Radial Halbach array . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 3 Design and Construction of the 3D Printed PMSM 25 3.1 Preliminary design of the PMSM prototype . . . . . . . . . . . . . . . 25 3.2 Optimization of 3D printing parameters . . . . . . . . . . . . . . . . 28 3.3 Stator winding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 3.4 Selection of permanent magnets . . . . . . . . . . . . . . . . . . . . . 32 3.5 Rotor weight balancing . . . . . . . . . . . . . . . . . . . . . . . . . . 39 3.6 Halbach array check . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 3.7 PMSM initial prototype design variation . . . . . . . . . . . . . . . . 43 4 Analysis and Control of a 3D Printed PMSM 47 4.1 Closed-loop control system implementation . . . . . . . . . . . . . . . 47 4.2 Speed control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 4.3 Temperature Analysis at steady state . . . . . . . . . . . . . . . . . . 62 5 Conclusions and Final Remarks 6

    Novel Rotor Structure Employing Large Flux Barrier and Disproportional Airgap for Enhancing Efficiency of IPMSM Adopting Concentrated Winding Structure

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    Interior permanent magnetic synchronous motors (IPMSMs) adopting concentrated windings have been widely used in industrial applications. To reduce operating costs, it is an important issue to enhance the efficiency of an IPMSM as much as possible while maintaining manufacturing costs. In general, an IPMSM used for an industrial application always operates in a specific operating area according to the required load. Therefore, this paper has two purposes. The first purpose is to propose a novel rotor structure which can enhance efficiency at the target wide-speed middle-torque operating area without additional manufacturing costs. The second purpose is to clarify the design method for a suitable rotor structure depending on its target operating area. Reducing losses is the key to enhancing efficiency. This paper first examines the effects of adopting large flux barriers and a disproportional airgap on copper and iron losses, and clarifies their merits and respective high-efficiency operating areas. Furthermore, to take advantage of the two rotor structures, a novel rotor structure which employs both large flux barriers and a disproportional airgap has been proposed. 2D-FEM (Finite-Element Method) is used for discussion first, and a prototype machine is manufactured to verify the 2D-FEM results. Both 2D-FEM and experimental results show that the proposed rotor structure can enhance the efficiency of an IPMSM most effectively at the target operating area. Moreover, for a low-speed high-torque operating area, adopting only large flux barriers is most suitable. And for a high-speed low-torque operating area, adopting only a disproportional airgap is most suitable

    Design and Application of Electrical Machines

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    Electrical machines are one of the most important components of the industrial world. They are at the heart of the new industrial revolution, brought forth by the development of electromobility and renewable energy systems. Electric motors must meet the most stringent requirements of reliability, availability, and high efficiency in order, among other things, to match the useful lifetime of power electronics in complex system applications and compete in the market under ever-increasing pressure to deliver the highest performance criteria. Today, thanks to the application of highly efficient numerical algorithms running on high-performance computers, it is possible to design electric machines and very complex drive systems faster and at a lower cost. At the same time, progress in the field of material science and technology enables the development of increasingly complex motor designs and topologies. The purpose of this Special Issue is to contribute to this development of electric machines. The publication of this collection of scientific articles, dedicated to the topic of electric machine design and application, contributes to the dissemination of the above information among professionals dealing with electrical machines

    High Speed Permanent Magnet Assisted Synchronous Reluctance Machines - Part I: A General Design Approach

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    The design of synchronous reluctance machines with and without permanent magnets assistance constitutes a challenging engineering task due to the numerous design variables and performance indexes to be considered. The design complexity increases even further when the application requires high speed operation, with consequent rotor structural constraints and and related effects on the electromagnetic performance. Structured as two-parts companion papers, this first part proposes a comprehensive design procedure able to consider all the non-linear aspects of the machine behaviour, greatly reducing the number of independent design variables, without worsening the computational burden. In particular, the non linear behaviour of the rotor iron ribs and the effect of the permanent magnets on the structural design are all taken into account with the proposed iterative design procedure targeting the achievement of a desired power factor. The proposed method will be then used to draw some preliminary design considerations highlighting the several trade-offs involved in the design of high speed permanent magnet assisted synchronous reluctance machine. Part I is setting the theoretical bricks that will be further expanded and experimentally validated in the companion paper Part II

    Design of a Bearingless Permanent Magnet Synchronous Machine with a Star Point-Connected Axial Active Magnetic Bearing

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    The bearingless synchronous machine is considered with slotted stator, cylindrical rotor with sleeve-protected surface-mounted permanent magnets and six actively controlled degrees of freedom as high-speed drive. The focus is set on two key aspects: The machine design under consideration of size-dependent scaling effects and a novel kind of feeding the excitation winding of the axial active magnetic bearing. Since the considered bearingless PM machines typically exhibit a low degree of magnetic saturation and are equipped with distributed windings, the two-dimensional analytical calculation is used to calculate the rotor suspension force and disturbing rotor forces. These calculations are used in the subsequent electromagnetic design process. At the beginning of the design process, boundary conditions are discussed, that are derived geometrically for the combined drive and suspension winding, structural mechanically for the sleeve height and thermally for the loss and output power density. On the basis of two different machine sizes, on the one hand approximately 1.5 kW and on the other hand approximately 60 kW at 75 mm and 130 mm outer diameter, respectively, at corresponding active axial length of 40 mm and 125 mm, this work shows, how the choice of pole count, bore diameter and magnet height influences the properties relevant for the rotor position control. It is concluded that an increase in pole count, a reduction in bore diameter and an increase in magnet height reduce the undesired parasitic lateral rotor forces, caused by rotor eddy currents and armature reaction. In order to investigate scaling effects, an analytical calculation is used, where the focus is set on the two-dimensional electrodynamic field calculation. By means of a 1 kW / 60000 rpm-prototype drive, consisting of a bearingless machine and a combined active radial-axial magnetic bearing, the accuracy of the results from calculation and simulation is verified. In order to reduce the number of required power electronic half-bridges, a concept is investigated, in which the axial magnetic bearing is supplied by a current between the star points of the combined winding sections in the bearingless machine. To do so the concept of the widely used space vector pulse-width modulation for 3-phase systems is extended to a double 3-phase system in a way that the axial magnetic bearing current corresponds to the sum current in the star point of one 3-phase system. This current can be controlled by the variation of the two star point electric potentials. However, additional current oscillations in the axial bearing current and in the 3-phase current can occur if the inverter is operated close to its voltage limit or if relatively high axial bearing currents must be provided at high dynamics. Anyway, the concept is considered a promising approach, since in this application as turbo-charger drive the disturbing effects do not occur
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