Multi-level-objective design optimization of permanent magnet synchronous wind generator and solar photovoltaic system for an urban environment application

This Ph.D. thesis illustrates a novel study on the analytical and numerical design optimization of radial-flux permanent magnet synchronous wind generators (PMSGs) for small power generation in an urban area, in which an outer rotor topology with a closed-slot stator is employed. The electromagnetic advantages of a double-layer fractional concentration non-overlapping winding configuration are discussed. The analytical behavior of a PMSG is studied in detail; especially for magnetic flux density distribution, time and space harmonics, flux linkages, back-EMF, cogging torque, torque, output power, efficiency, and iron losses computation. The electromagnetic behavior of PMSGs are evaluated when a number of various Halbach array magnetization topologies are presented to maximize the generator’s performance. In addition, the thermal behavior of the PMSG is improved using an innovative natural air-cooling system for rated speed and higher to decrease the machine’s heat mainly at the stator teeth. The analytical investigation is verified via 2-D and 3-D finite element analysis along with a good experimental agreement. Design optimization of electrical machines plays the deterministic role in performance improvements such as the magnetization pattern, output power, and efficiency maximization, as well as losses and material cost minimization. This dissertation proposes a novel multi-objective design optimization technique using a dual-level response surface methodology (D-RSM) and Booth’s algorithm (coupled to a memetic algorithm known as simulated annealing) to maximize the output power and minimize material cost through sizing optimization. Additionally, the efficiency maximization by D-RSM is investigated while the PMSG and drive system are on duty as the whole. It is shown that a better fit is available when utilizing modern design functions such as mixed-resolution central composite (MR-CCD) and mixed-resolution robust (MR-RD), due to controllable and uncontrollable design treatments, and also a Window-Zoom-in approach. The proposed design optimization was verified by an experimental investigation. Additionally, there are several novel studies on vibro-acoustic design optimization of the PMSGs with considering variable speed analysis and natural frequencies using two techniques to minimize the magnetic noise and vibrations. Photovoltaic system design optimization considered of 3-D modeling of an innovative application-oriented urban environment structure, a smart tree for small power generation. The horizon shading is modeled as a broken line superimposed onto the sun path diagram, which can hold any number of height/azimuth points in this original study. The horizon profile is designed for a specific location on the Barcelona coast in Spain and the meteorological data regarding the location of the project was also considered. Furthermore, the input weather data is observed and stored for the whole year (in 2016). These data include, ambient temperature, module’s temperature (open and closed circuits tests), and shading average rate. A novel Pareto-based 3-D analysis was used to identify complete and partial shading of the photovoltaic system. A significant parameter for a photovoltaic (PV) module operation is the nominal operating cell temperature (NOCT). In this research, a glass/glass module has been referenced to the environment based on IEC61215 via a closed-circuit and a resistive load to ensure the module operates at the maximum power point. The proposed technique in this comparative study attempts to minimize the losses in a certain area with improved output energy without compromising the overall efficiency of the system. A Maximum Power Point Track (MPPT) controller is enhanced by utilizing an advanced perturb & observe (P&O) algorithm to maintain the PV operating point at its maximum output under different temperatures and insolation. The most cost-effective design of the PV module is achieved via optimizing installation parameters such as tilt angle, pitch, and shading to improve the energy yield. The variation of un-replicated factorials using a Window-Zoom-in approach is examined to determine the parameter settings and to check the suitability of the design. An experimental investigation was carried out to verify the 3-D shading analysis and NOCT technique for an open-circuit and grid-connected PV module.Esta tesis muestra un novedoso estudio referente al diseño optimizado de forma analítica y numérica de un generador síncrono de imanes permanentes (PMSGs) para una aplicación de microgeneración eólica en un entorno urbano, donde se ha escogido una topología de rotor exterior con un estator de ranuras cerradas. Las ventajas electromagnéticas de los arrollamientos fraccionarios de doble capa, con bobinas concentradas se discuten ampliamente en la parte inicial del diseño del mismo, así como las características de distribución de la inducción, los armónicos espaciales y temporales, la fem generada, el par de cogging así como las características de salida (par, potencia generada, la eficiencia y la distribución y cálculo de las pérdidas en el hierro que son analizadas detalladamente) Posteriormente se evalúan diferentes configuraciones de estructuras de imanes con magnetización Halbach con el fin de maximizar las prestaciones del generador. Adicionalmente se analiza la distribución de temperaturas y su mejora mediante el uso de un novedoso diseño mediante el uso de ventilación natural para velocidades próximas a la nominal y superiores con el fin de disminuir la temperatura de la máquina, principalmente en el diente estatórico. El cálculo analítico se completa mediante simulaciones 2D y 3D utilizando el método de los elementos finitos así como mediante diversas experiencias que validan los modelos y aproximaciones realizadas. Posteriormente se desarrollan algoritmos de optimización aplicados a variables tales como el tipo de magnetización, la potencia de salida, la eficiencia así como la minimización de las pérdidas y el coste de los materiales empleados. En la tesis se proponen un nuevo diseño optimizado basado en una metodología multinivel usando la metodología de superficie de respuesta (D-RSM) y un algoritmo de Booth (maximizando la potencia de salida y minimizando el coste de material empleado) Adicionalmente se investiga la maximización de la eficiencia del generador trabajando conjuntamente con el circuito de salida acoplado. El algoritmo utilizado queda validado mediante la experimentación desarrollada conjuntamente con el mismo. Adicionalmente, se han realizado diversos estudios vibroacústicos trabajando a velocidad variable usando dos técnicas diferentes para reducir el ruido generado y las vibraciones producidas. Posteriormente se considera un sistema fotovoltaico orientado a aplicaciones urbanas que hemos llamado “Smart tree for small power generation” y que consiste en un poste con un generador eólico en la parte superior juntamente con uno o más paneles fotovoltaicos. Este sistema se ha modelado usando metodologías en 3D. Se ha considerado el efecto de las sombras proyectadas por los diversos elementos usando datos meteorológicos y de irradiación solar de la propia ciudad de Barcelona. Usando una metodología basada en un análisis 3D y Pareto se consigue identificar completamente el sistema fotovoltaico; para este sistema se considera la temperatura de la célula fotovoltaica y la carga conectada con el fin de generar un algoritmo de control que permita obtener el punto de trabajo de máxima potencia (MPPT) comprobándose posteriormente el funcionamiento del algoritmo para diversas situaciones de funcionamiento del sistemaLa tesis desenvolupa un nou estudi per al disseny optimitzat, analític i numèric, d’un generador síncron d’imants permanents (PMSGs) per a una aplicació de microgeneració eòlica en aplicacions urbanes, on s’ha escollit una configuració amb rotor exterior i estator amb ranures tancades. Es discuteixen de forma extensa els avantatges electromagnètics dels bobinats fraccionaris de doble capa així com les característiques resultats vers la distribució de les induccions, els harmònics espacials i temporals, la fem generada, el parell de cogging i les característiques de sortida (parell, potencia, eficiència i pèrdues) Tanmateix s’afegeix l’estudi de diferents estructures Halbach per als imants permanents a fi i efecte de maximitzar les característiques del generador. Tot seguit s’analitza la distribució de temperatures i la seva reducció mitjançant la utilització d’una nova metodologia basada en la ventilació natural. Els càlculs analítics es complementen mitjançant anàlisi en 2 i 3 dimensions utilitzant elements finits i diverses experiències que validen els models i aproximacions emprades. Una vegada fixada la geometria inicial es desenvolupen algoritmes d’optimització per a diverses variables (tipus de magnetització dels imants, potencia de sortida, eficiència, minimització de pèrdues i cost dels materials) La tesi planteja una optimització multinivell emprant la metodologia de superfície de resposta i un algoritme de Booth; a més, es realitza la optimització considerant el circuit de sortida. L’algoritme resta validat per la experimentació realitzada. Finalment, s’han considerat diversos estudis vibroacústic treballant a velocitat variable, emprant dues tècniques diferents per a reduir el soroll i les vibracions desenvolupades. Per a finalitzar l’estudi es considera un sistema format per una turbina eòlica instal·lada sobre un pal de llum autònom, els panells fotovoltaics corresponents i el sistema de càrrega. Per a modelitzar l’efecte de l’ombrejat s’ha emprat un model en 3D i les dades del temps i d’irradiació solar de la ciutat de Barcelona. El model s’ha identificat completament i s’ha generat un algoritme de control que considera, a més, l’efecte de la temperatura de la cèl·lula fotovoltaica y la càrrega connectada al sistema per tal d’aconseguir el seguiment del punt de màxima potenciaPostprint (published version

Optimisation of silicon content in Fe-Si alloys processed via Laser Powder Bed Fusion for an additively manufactured soft magnetic core

Additive Manufacturing (AM) of electric motors, specifically, Laser Powder Bed Fusion (LPBF), for rotating soft magnetic cores is of research interest because of its potential benefits in industry sectors such as energy, aerospace and automotive. AM, also commonly known as 3D printing (3DP), offers unrivalled design freedom and the capability to produce components with complex geometries from metal alloys that cannot be processed with conventional manufacturing methods (casting, injection moulding etc.). However, before AM becomes the norm in the production of novel electric drives and power generators, it is necessary to understand how the selection of materials in the motor affects the performance of the 3D printed active components (rotor, stator, windings). This thesis aims at enabling the AM of more compact, lightweight, reliable and efficient electric machines through the development of a comprehensive understanding of the metallurgy and material properties of the additively manufactured components of an electric drive. It focuses on two materials: a soft ferromagnetic alloy, namely silicon steel, for the soft magnetic core and high purity copper for the windings of the electric motor. The study investigated the mechanical, thermal and magnetic properties of high silicon steel (from Fe-3.5%wt Si up to Fe-6.9%wt Si) by adjusting – for the first time – the alloys’ chemistry in order to improve ductility and avoid the risk of in-process cracking; this is achieved by mixing pre-alloyed Fe-6.9%wt Si powder with high-purity Fe powder. Another material investigated, which has lately received increased interest both for electrical applications and heat exchangers, was pure copper. Although high purity copper is challenging to process with LPBF due to its high reflectivity, oxidation and high thermal conductivity, it was included in the study due the potential to further increase a motor’s performance by optimising the design of the windings in a 3DP electric motor. the materials under investigation were subjected to heat treatments. Annealing of the soft magnetic parts produced by LPBF changed their microstructure by increasing the grain size and increased their permeability. Experiments were also performed to investigate how the performance of a Switched Reluctance Motor (SRM) could be improved by manufacturing the soft magnetic rotor core using LPBF. A prototype SRM soft magnetic core was additively manufactured from 5%w.t. silicon steel and tested. We compared the efficiency of the motor with the 3D-printed rotor core to a motor with an identical but traditionally laminated rotor. This investigation has therefore, developed an understanding of the various aspects of the LPBF process for the successful manufacturing of a prototype functional electric motor. The results from this work can be used to advance the implementation of AM in the production of lightweight high-performance electrical machines and revolutionise the way electrical motors are designed and manufactured

Optimisation of silicon content in Fe-Si alloys processed via Laser Powder Bed Fusion for an additively manufactured soft magnetic core

Additive Manufacturing (AM) of electric motors, specifically, Laser Powder Bed Fusion (LPBF), for rotating soft magnetic cores is of research interest because of its potential benefits in industry sectors such as energy, aerospace and automotive. AM, also commonly known as 3D printing (3DP), offers unrivalled design freedom and the capability to produce components with complex geometries from metal alloys that cannot be processed with conventional manufacturing methods (casting, injection moulding etc.). However, before AM becomes the norm in the production of novel electric drives and power generators, it is necessary to understand how the selection of materials in the motor affects the performance of the 3D printed active components (rotor, stator, windings). This thesis aims at enabling the AM of more compact, lightweight, reliable and efficient electric machines through the development of a comprehensive understanding of the metallurgy and material properties of the additively manufactured components of an electric drive. It focuses on two materials: a soft ferromagnetic alloy, namely silicon steel, for the soft magnetic core and high purity copper for the windings of the electric motor. The study investigated the mechanical, thermal and magnetic properties of high silicon steel (from Fe-3.5%wt Si up to Fe-6.9%wt Si) by adjusting – for the first time – the alloys’ chemistry in order to improve ductility and avoid the risk of in-process cracking; this is achieved by mixing pre-alloyed Fe-6.9%wt Si powder with high-purity Fe powder. Another material investigated, which has lately received increased interest both for electrical applications and heat exchangers, was pure copper. Although high purity copper is challenging to process with LPBF due to its high reflectivity, oxidation and high thermal conductivity, it was included in the study due the potential to further increase a motor’s performance by optimising the design of the windings in a 3DP electric motor. the materials under investigation were subjected to heat treatments. Annealing of the soft magnetic parts produced by LPBF changed their microstructure by increasing the grain size and increased their permeability. Experiments were also performed to investigate how the performance of a Switched Reluctance Motor (SRM) could be improved by manufacturing the soft magnetic rotor core using LPBF. A prototype SRM soft magnetic core was additively manufactured from 5%w.t. silicon steel and tested. We compared the efficiency of the motor with the 3D-printed rotor core to a motor with an identical but traditionally laminated rotor. This investigation has therefore, developed an understanding of the various aspects of the LPBF process for the successful manufacturing of a prototype functional electric motor. The results from this work can be used to advance the implementation of AM in the production of lightweight high-performance electrical machines and revolutionise the way electrical motors are designed and manufactured

Magnetic Material Modelling of Electrical Machines

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

Advances in the Field of Electrical Machines and Drives

Electrical machines and drives dominate our everyday lives. This is due to their numerous applications in industry, power production, home appliances, and transportation systems such as electric and hybrid electric vehicles, ships, and aircrafts. Their development follows rapid advances in science, engineering, and technology. Researchers around the world are extensively investigating electrical machines and drives because of their reliability, efficiency, performance, and fault-tolerant structure. In particular, there is a focus on the importance of utilizing these new trends in technology for energy saving and reducing greenhouse gas emissions. This Special Issue will provide the platform for researchers to present their recent work on advances in the field of electrical machines and drives, including special machines and their applications; new materials, including the insulation of electrical machines; new trends in diagnostics and condition monitoring; power electronics, control schemes, and algorithms for electrical drives; new topologies; and innovative applications

Mathematical Approaches to Modeling, Optimally Designing, and Controlling Electric Machine

Optimal performance of the electric machine/drive system is mandatory to improve the energy consumption and reliability. To achieve this goal, mathematical models of the electric machine/drive system are necessary. Hence, this motivated the editors to instigate the Special Issue “Mathematical Approaches to Modeling, Optimally Designing, and Controlling Electric Machine”, aiming to collect novel publications that push the state-of-the art towards optimal performance for the electric machine/drive system. Seventeen papers have been published in this Special Issue. The published papers focus on several aspects of the electric machine/drive system with respect to the mathematical modelling. Novel optimization methods, control approaches, and comparative analysis for electric drive system based on various electric machines were discussed in the published papers

Benzocyclobutene-based Electric Micromachines Supported on Microball Bearings: Design, Fabrication, and Characterization

This dissertation summarizes the research activities that led to the development of the first microball-bearing-supported linear electrostatic micromotor with benzocyclobutene (BCB) low-k polymer insulating layers. The primary application of this device is long-range, high-speed linear micropositioning. The future generations of this device include rotary electrostatic micromotors and microgenerators. The development of the first generation of microball-bearing-supported micromachines, including device theory, design, and modeling, material characterization, process development, device fabrication, and device test and characterization is presented. The first generation of these devices is based on a 6-phase, bottom-drive, linear, variable-capacitance micromotor (B-LVCM). The design of the electrical and mechanical components of the micromotor, lumped-circuit modeling of the device and electromechanical characteristics, including variable capacitance, force, power, and speed are presented. Electrical characterization of BCB polymers, characterization of BCB chemical mechanical planarization (CMP), development of embedded BCB in silicon (EBiS) process, and integration of device components using microfabrication techniques are also presented. The micromotor consists of a silicon stator, a silicon slider, and four stainless-steel microballs. The aligning force profile of the micromotor was extracted from simulated and measured capacitances of all phases. An average total aligning force of 0.27 mN with a maximum of 0.41 mN, assuming a 100 V peak-to-peak square-wave voltage, was measured. The operation of the micromotor was verified by applying square-wave voltages and characterizing the slider motion. An average slider speed of 7.32 mm/s when excited by a 40 Hz, 120 V square-wave voltage was reached without losing the synchronization. This research has a pivotal impact in the field of power microelectromechanical systems (MEMS). It establishes the foundation for the development of more reliable, efficient electrostatic micromachines with variety of applications such as micropropulsion, high-speed micropumping, microfluid delivery, and microsystem power generation

Wireless Tagging and Actuation with Shaped Magnetoelastic Transducers.

The promise and the challenges of patterned, micro-scale magnetoelastic transducers and their integration with silicon is the focus of this thesis. As demonstrations, wireless magnetoelastic chip-scale resonant rotary motors and miniaturized magnetoelastic tags are investigated. The motors consist of a magnetoelastically-actuated stator, a silicon rotor, a “hub” structure, and DC and AC coils. Two generations are described. The first-generation motor uses a stator with a bilayer of silicon (ø8 mm x 65 µm thick) and magnetoelastic foil (Metglas™ 2826MB bulk foil, ø8 mm x 25 µm thick). The motor provides bi-directional rotation capability, and typical resonant frequencies of the clockwise and counterclockwise modes are 6.1 kHz and 7.9 kHz, respectively. The counterclockwise mode provides a rotation rate of ≈100 rpm, start torque of 30 nN∙m, a step size of 74 milli-degree and a capability for driving a 100 mg payload while a 8 Oe DC and a 6 Oe-amplitude AC magnetic field are applied. The second-generation of motors includes bilayer standing wave and traveling wave designs (ø5 mm stators) with integrated capacitive sensors for real-time position measurement and speed estimation. Clockwise and counterclockwise mode shapes with resonant frequencies of 12 kHz and 22.4 kHz, respectively, are measured for the standing wave motor. Two mode shapes (with π/2 spatial phase difference) at resonant frequencies of 30.2 kHz and 31.7 kHz are measured for the traveling wave motor. The wireless actuation capability and the hybrid integration of the bulk magnetoelastic material with silicon show promise for use in many microsystems. A lithographically patterned, frame-suspended hexagonal magnetoelastic tag design (ø1.3 mm x 27 µm thick) is also investigated. These tags provide ≈75x signal amplitude improvement compared to a non-suspended disc tag, while occupying ≈100x smaller area than typical commercial ribbon tags. Signal strength can also be boosted by taking advantage of tag signal superposition. Linear signal superposition of the response has been experimentally measured for clustered sets of frame-suspended tags that include as many as 500 units. Miniaturized tags with sufficient signal strength may enable new applications, such as distributing the tags into a network of cracks and subsequently mapping the distribution.PhDMechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/108961/1/juntang_1.pd