Computationally Efficient Optimization of a Five-Phase Flux-Switching PM Machine Under Different Operating Conditions

This paper investigates the comparative design optimizations of a five-phase outer-rotor flux-switching permanent magnet (FSPM) machine for in-wheel traction applications. To improve the comprehensive performance of the motor, two kinds of large-scale design optimizations under different operating conditions are performed and compared, including the traditional optimization performed at the rated operating point and the optimization targeting the whole driving cycles. Three driving cycles are taken into account, namely, the urban dynamometer driving schedule (UDDS), the highway fuel economy driving schedule (HWFET), and the combined UDDS/HWFET, representing the city, highway, and combined city/highway driving, respectively. Meanwhile, the computationally efficient finite-element analysis (CE-FEA) method, the cyclic representative operating points extraction technique, as well as the response surface methodology (in order to minimize the number of experiments when establishing the inverse machine model), are presented to reduce the computational effort and cost. From the results and discussion, it will be found that the optimization results against different operating conditions exhibit distinct characteristics in terms of geometry, efficiency, and energy loss distributions. For the traditional optimization performed at the rated operating point, the optimal design tends to reduce copper losses but suffer from high core losses; for UDDS, the optimal design tends to minimize both copper losses and PM eddy-current losses in the low-speed region; for HWFET, the optimal design tends to minimize core losses in the high-speed region; for the combined UDDS/HWFET, the optimal design tends to balance/compromise the loss components in both the low-speed and high-speed regions. Furthermore, the advantages of the adopted optimization methodologies versus the traditional procedure are highlighted

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

Design study and analysis of a conventional radial-field flux-switching permanent magnet machine for a medium-speed wind turbine

A conventional radial-field FSPM machine was designed and studied. The research focussed on the effectiveness of using a parametric study to obtain an optimized solution compared to using a computerized optimizer; as well as an in-depth core loss analysis. The designing process started with an analytical design that was used for initial design purposes, and this was followed by numerical simulations to get an optimized solution. Within the numerical simulations, the parametric analysis and optimization were performed. The final optimized design was designed to be manufactured and compared to both the analytical and numerical results for validation. The analytical and numerical results were obtained using MathWorks MATLAB 2019a and Ansys Maxwell 19.1 respectively. The results show that an optimizer is more effective in finding an optimized solution in the design space, however, the parametric analyses are still useful in order to determine the design regions for the optimizer and how sensitive certain parameters are towards the FSPM machine's performance. In the end, these analyses are used to speed up the design process by minimizing computational time, and also provides an understanding to the designer of parameter changes on the FSPM machine's performance

Optimal design of gearless flux-switching generator with ferrite permanent magnets

In this paper, the optimal design of the Flux-Switching Generator with ferrite magnets based on a two-mode substituting load profile for a gearless wind generator is considered. A onecriterion Nelder-Mead method is used to optimize the generator design. The optimization function is constructed mainly so as to minimize the average losses in the generator and the required AC-DC converter power. Also, the Flux-Switching Generator torque-ripple and the ferrite magnets volume are minimized. Using substituting profiles instead of initial ones reduces the calculation efforts substantially. The paper contains the analysis of the optimal design of the Flux-Switching Generator with ferrite magnets. © 2020 by the authors.Ministry of Education and Science of the Russian Federation, MinobrnaukaThe research was conducted on theme no. 8.9549.2017/8.9. within the frame of the government task of the Ministry of Education and Science of the Russian Federation in R&D. The authors thank the editors and reviewers for careful reading, and constructive comments

Design of Outrunner Eectric Machines for Green Energy Applications

Interests in using rare-earth free motors such as switched reluctance motors (SRMs) for electric and hybrid electric vehicles (EV/HEVs) continue to gain popularity, owing to their low cost and robustness. Optimal design of an SRM, to meet specific characteristics for an application, should involve simultaneous optimization of the motor geometry and control in order to achieve the highest performance with the lowest cost. This dissertation firstly presents a constrained multi-objective optimization framework for design and control of a SRM based on a non-dominated sorting genetic algorithm II (NSGA-II). The proposed methodology optimizes SRM operation for high volume traction applications by considering multiple criteria including efficiency, average torque, and torque ripple. Several constraints are defined by the application considered, such as the motor stack length, minimum desired efficiency, etc. The outcome of this optimization includes an optimal geometry, outlining variables such as air gap length, rotor inner diameter, stator pole arc angle, etc as well as optimal turn-on and turn-off firing angles. Then the machine is manufactured according to the obtained optimal specifications. Finite element analysis (FEA) and experimental results are provided to validate the theoretical findings. A solution for exploring optimal firing angles of nonlinear current-controlled SRMs is proposed in order to minimize the torque ripple. Motor torque ripple for a certain electrical load requirement is minimized using a surrogate-based optimization of firing angles by adjusting the motor geometry, reference current, rotor speed and dc bus voltage. Surrogate-based optimization is facilitated via Neural Networks (NN) which are regression tools capable of learning complex multi-variate functions. Flux and torque of the nonlinear SRM is learned as a function of input parameters, and consequently the computation time of design, which is crucial in any micro controller unit, is expedited by replacing the look-up tables of flux and torque with the surrogate NN model. This dissertation then proposes a framework for the design and analysis of a coreless permanent magnet (PM) machine for a 100 kWh shaft-less high strength steel flywheel energy storage system (SHFES). The PM motor/generator is designed to meet the required specs in terms of torque-speed and power-speed characteristics given by the application. The design challenges of a motor/generator for this architecture include: the poor flux paths due to a large scale solid carbon steel rotor and zero-thermal convection of the airgap due to operation of the machine in vacuum. Magnetic flux in this architecture tends to be 3-D rather than constrained due to lack of core in the stator. In order to tackle these challenges, several other parameters such as a proper number of magnets and slots combination, number of turns in each coil, magnets with high saturated flux density and magnets size are carefully considered in the proposed design framework. Magnetic levitation allows the use of a coreless stator that is placed on a supporting structure. The proposed PM motor/generator comprehensive geometry, electromagnetic and mechanical dimensioning are followed by detailed 3-D FEA. The torque, power, and speed determined by the FEA electromagnetic analysis are met by the application design requirements and constraints for both the charging and discharging modes of operation. Finally, the motor/generator static thermal analysis is discussed in order to validate the proposed cooling system functionality

Automated Design Optimization of Synchronous Machines: Development and Application of a Generic Fitness Evaluation Framework

A rotating synchronous electric machine design can be described to its entirety by a combination of 17 to 24 discrete and continuous parameters pertaining the geometry, material selection, and electrical loading. Determining the performance attributes of a design often involves numerical solutions to thermal and magnetic equations. Stochastic optimization methods have proven effective for solving specific design problems in literature. A major challenge to design automation, however, is whether the design tool is versatile enough to solve design problems with different types of objectives and requirements. This work proposes a black-box approach in an attempt to encompass a wide variety of synchronous machine design problems. This approach attempts to enlist all possible attributes of interest (AoIs) to the end-user so that the design optimization problem can be framed by combination of such attributes only. The number of ways the end-user can input requirements is now defined and limited. Design problems are classified based on which of the AoI’s are constraints, objectives or design parameters. It is observed that regardless of the optimization problem definition, the evaluation of any design is based on a common set of physical and analytical models and empirical data. Problem definitions are derived based on black-box approach and efficient fitness evaluation algorithms are tailored to meet requirements of each problem definition. The proposed framework is implemented in Matlab/C++ environment encompassing different aspects of motor design. The framework is employed for designing synchronous machines for three applications where designs based on conventional motor construction did not meet all design requirements. The first design problem is to develop a novel bar-conductor tooth-wound stator technology for 1.2 kW in-wheel direct drive motor for an electric/hybrid-electric two wheeler (including practical implementation). The second design problem deals with a novel outer-rotor buried ferrite magnet geometry for a 1.2 kW in-wheel geared motor drive used in an electric/hybrid-electric two wheeler (including practical implementation). The third application involves design of an ultra-cost-effective and ultra-light-weight 1 kW aluminum conductor motor. Thus, the efficacy of automated design is demonstrated by harnessing the framework and algorithms for exploring new technologies applicable for three distinct design problems originated from practical applications

Development of a scaled doubly-fed induction generator for assessment of wind power integration issues

Years of experience have been dedicated to the advancement of thermal power plant technology, and in the last decade the investigation has focused on the wind energy conversion system (WECS). Wind energy will play an important role in the future of the energy market, due to the changing climate and the fossil fuel crisis. Initially, wind energy was intended to cover a small portion of the energy market, but in the long term it should compete with conventional fossil fuel power generation. The movement of the power system towards this new phenomena has to be investigated before the wind energy share increases in the network. Therefore, the wind energy integration issues serve as an interesting topic for authors to improve the perception of integration, distribution, variability and power flow issues. Several simulation models have been introduced in order to resolve this issue, however, the variety in types of wind turbines and the network policies result in these models having limited accuracy or being developed for specific issues. The micro-machine is introduced in order to overcome the challenges of simulation models and the costs involved in field tests. In the past, the grid integration issue of large turbo-alternators was solved by the micro-machines. A variety of tests are possible with the micro-machines and they also increase the flexibility of the system. The increased accuracy as well as the ability to carry out real-time analysis and compare actual field test data are strengths worth utilizing. This project involves the designing and the prototyping of a scaled doubly-fed induction generator (micro-DFIG). The machine is also analysed and tested. The scaling of the micro-machine is achieved by means of a dimensional analysis, which is a mathematical method that allows machines and systems to be downscaled by establishing laws of similitude between the reference model and its scaled model. MATLAB/SIMULINK, Maxwell and Solid Work are employed to achieve the objectives of this project

Advanced design methodology for permanent magnet synchronous machines in power applications

Most of the world electrical energy is consumed by electric motors, and then, the improvement in their performance leads to essential savings in the global energy consumption, required to reduce the CO2 emissions. Actually, the policies of governments and institutions are becoming more demanding and the manufacturers are forced to offer more and more optimized products. Moreover, many applications are increasingly demanding high performance in terms of power density, reliability or dynamic response, as in the case of electric vehicle, wind power generation or railway traction. The high energetic content of neodymium magnets causes that the permanent magnet machines (PMSM) are the more attractive option with respect to power density. In addition, thanks to the almost complete elimination of the rotor losses they are the most energetically efficient machines. The PMSM design requires of a multiphysical approach since it comprises electric, magnetic and thermal aspects. In this work, a comprehensive review of the technical literature regarding these machines has been done, and some areas for improvement have been found. Firstly, it is common that the procedure starts from a quite defined machine and just an optimization of a specific part is realized. Moreover, excessive dependence on designer’s experience and knowhow is observed, without giving clear instructions for taking design decisions. Finally, excessive dependence on time consuming FEM models is found. Hence, the main objective of this thesis is to develop and propose an advanced design methodology for PMSM design, characterized by being clear and complete, considering whole the design process and giving criteria and tools for taking decisions which lead to an optimum choice of the final solution. A PMSM design methodology has been proposed that enables the evaluation of large amounts of configurations in an automatic manner, easing to the designer the process of taking the final design decision. To implement this methodology, several tools have been developed and explained in detail: electromagnetic models coupled to thermal models and lumped parameter electromagnetic models. Some important modifications were done in the thermal models taken as a reference in order to consider different cooling conditions. In addition, a basis permeance network model was adapted to the selected machine topology and it was used to demonstrate its suitability to be used in combination with Frozen Permeability technique. Following the proposed design methodology, a 75 kW PMSM prototype was designed and validated at the IK4‐IKERLAN medium voltage laboratory. The obtained results have validated both the proposed design methodology and the developed and employed tools.La mayor parte de la energía eléctrica mundial es consumida en motores eléctricos, por lo que la mejora de sus prestaciones conduce a ahorros en el consumo energético esenciales si se quieren reducir las emisiones de CO2. De hecho, las políticas de gobiernos y asociaciones cada vez son más exigentes, y los diseñadores se ven forzados a lanzar productos cada vez más optimizados. Además, cada vez hay más aplicaciones que son muy exigentes en términos de densidad de potencia, fiabilidad o prestaciones dinámicas, como son el vehículo eléctrico, la generación eólica o la tracción ferroviaria. El altísimo contenido energético de los imanes de neodimio provoca que las máquinas imanes permanentes (PMSM) sean las más atractivas en términos de densidad de potencia. Además, debido a la casi total eliminación de pérdidas en el rotor se convierten en las máquinas más eficientes energéticamente. El diseño de una PMSM requiere de un enfoque multidisciplinar, ya que engloba aspectos eléctricos, magnéticos y térmicos. En este trabajo, se ha realizado una revisión exhaustiva de la literatura técnica publicada hasta la fecha en relación con el diseño de estas máquinas, y se han encontrado ciertos puntos de mejora. En primer lugar, muchas veces se parte de un diseño bastante definido y se optimiza una parte concreta del mismo. Además, se aprecia excesiva dependencia de la experiencia y knowhow del diseñador, sin establecer pautas claras para la toma de decisiones de diseño. Finalmente, dependen excesivamente del temporalmente costoso FEM. Por lo tanto, el objetivo principal de esta tesis es desarrollar una metodología avanzada de diseño de PMSMs que sea clara y completa, abarcando todo el proceso de diseño y aportando criterios y herramientas para la toma de decisiones que conduzcan a una elección óptima de la solución final. Se ha propuesto una metodología de diseño que permite la evaluación de gran cantidad de configuraciones de PMSM de forma automática, facilitando la decisión de diseño final por parte del diseñador. Para la implementación de esta metodología, diversas herramientas han tenido que ser desarrolladas y son explicadas en detalle: modelos analíticos electromagnéticos acoplados con modelos térmicos, y modelos electromagnéticos de parámetros concentrados. Importantes modificaciones fueron realizadas sobre los modelos térmicos adoptados para considerar diferentes refrigeraciones. Además, el circuito electromagnético de parámetros concentrados fue adaptado a la topología seleccionada y demostró su validez para ser utilizado en combinación con la técnica de Frozen Permeability. Siguiendo la metodología propuesta, se ha diseñado y fabricado un prototipo de 75 kW y se ha realizado la validación experimental en el laboratorio de media tensión de IK4‐IKERLAN. Los resultados obtenidos han servido para validar tanto la metodología de diseño como las herramientas empleadas en la misma.Munduko energia elektrikoaren zatirik handiena motor elektrikoetan kontsumitzen da, eta, ondorioz, prestazioak hobetzeak lagundu egiten du kontsumo energetikoan funtsezko aurrezpenak egiten, CO2 igorpenak murriztu nahi badira. Berez, gobernuen eta elkarteen eskakizunak gero eta zorrotzagoak dira, eta diseinatzaileak produktu gero eta optimizatuak atera beharrean daude. Gainera, gero eta aplikazio gehiago daude zorroztasun handia eskatzen dutenak potentzi dentsitateari, fidagarritasunari edo prestazio dinamikoei dagokienez, esaterako, ibilgailu elektrikoan, sorkuntza eolikoan edo tren trakzioan. Neodimiozko imanen eduki energetiko itzelaren ondorioz, iman makina iraunkorrak (PMSM) dira erakargarrienak potentzi dentsitateari dagokionez. Gainera, errotorearen galerak ia guztiz deuseztatzen direnez, energetikoki makinarik eraginkorrenak dira. PMSM bat diseinatzeko diziplina askoko ikuspegia behar da, alderdi elektrikoak, magnetikoak eta termikoak hartzen baititu bere baitan. Lan honetan orain arte honelako makinen diseinuari buruz argitaratutako literatura teknikoaren azterketa zehatza egin da, eta hobetzeko hainbat puntu aurkitu dira. Lehenik eta behin, askotan, abiapuntua nahiko definituta dagoen diseinu bat izaten da, eta egiten dena da horren zati jakin bat optimizatu. Gainera, gehiegizko mendekotasuna egoten da diseinatzailearen esperientzia eta knowhow‐arekiko, diseinuaren inguruko erabakiak hartzeko jarraibide argiak ezarri gabe. Azkenik, mendekotasun handia dago FEMek behin‐behinean duen kostu handiarekiko. Horrenbestez, tesiaren helburu nagusia da PMSMak diseinatzeko metodologia aurreratu bat garatzea, argia eta osatua, diseinuaren prozesu osoa hartuko duena, eta erabakiak hartzeko irizpideak eta tresnak eskainiko dituena, amaierako soluziorik onena aukeratu ahal izateko. Diseinurako proposatu den metodologiarekin PMSMko konfigurazio kopuru handi bat ebaluatu daiteke automatikoki, diseinatzaileari amaierako diseinua erabakitzen laguntzeko. Metodologia inplementatzeko, hainbat tresna garatu behar izan dira, eta horiek zehatz esplikatzen dira: eredu analitiko elektromagnetikoak, eredu termikoekin uztartuta, eta parametro kontzentratuen bidezko eredu elektromagnetikoak. Hautatutako eredu termikoetan aldaketa garrantzitsuak egin behar izan ziren, hozkuntza desberdinak lantzeko. Horrez gain, parametro kontzentratuen zirkuitu elektromagnetikoa hautatutako topologiara egokitu zen, eta bere balioa frogatu zuen, Frozen Permeability teknikarekin konbinatuta erabiltzeko. Proposatutako metodologiari jarraituz, 75 kW‐eko prototipo bat diseinatu eta fabrikatu da, eta balioztapen esperimentala egin da IK4‐IKERLANeko tentsio ertaineko laborategian. Lortutako emaitzek diseinuaren metodologia zein bertan erabilitako tresnak balioztatzeko balio izan dute

On the Modeling, Analysis and Development of PMSM: For Traction and Charging Application

Permanent magnet synchronous machines (PMSMs) are widely implemented commercially available traction motors owing to their high torque production capability and wide operating speed range. However, to achieve significant electric vehicle (EV) global market infiltration in the coming years, the technological gaps in the technical targets of the traction motor must be addressed towards further improvement of driving range per charge of the vehicle and reduced motor weight and cost. Thus, this thesis focuses on the design and development of a novel high speed traction PMSM with improved torque density, maximized efficiency, reduced torque ripple and increased driving range suitable for both traction and integrated charging applications. First, the required performance targets are determined using a drive cycle based vehicle dynamic model, existing literature and roadmaps for future EVs. An unconventional fractional–slot distributed winding configuration with a coil pitch of 2 is selected for analysis due to their short end–winding length, reduced winding losses and improved torque density. For the chosen baseline topology, a non–dominated sorting genetic algorithm based selection of optimal odd slot numbers is performed for higher torque production and reduced torque ripple. Further, for the selected odd slot–pole combination, a novel star–delta winding configuration is modeled and analyzed using winding function theory for higher torque density, reduced spatial harmonics, reduced torque ripple and machine losses. Thereafter, to analyze the motor performance with control and making critical decisions on inter–dependent design parameter variations for machine optimization, a parametric design approach using a novel coupled magnetic equivalent circuit model and thermal model incorporating current harmonics for fractional–slot wound PMSMs was developed and verified. The developed magnetic circuit model incorporates all machine non–linearities including effects of temperature and induced inverter harmonics as well as the space harmonics in the winding inductances of a fractional–slot winding configuration. Using the proposed model with a pareto ant colony optimization algorithm, an optimal rotor design is obtained to reduce the magnet utilization and obtain maximized torque density and extended operating range. Further, the developed machine structure is also analyzed and verified for integrated charging operation where the machine’s winding inductances are used as line inductors for charging the battery thereby eliminating the requirement of an on–board charger in the powertrain and hence resulting in reduced weight, cost and extended driving range. Finally, a scaled–down prototype of the proposed PMSM is developed and validated with experimental results in terms of machine inductances, torque ripple, torque–power–speed curves and efficiency maps over the operating speed range. Subsequently, understanding the capabilities and challenges of the developed scaled–down prototype, a full–scale design with commercial traction level ratings, will be developed and analyzed using finite element analysis. Further recommendations for design improvement, future work and analysis will also be summarized towards the end of the dissertation