Direct torque control for dual three-phase induction motor drives

A direct torque control (DTC) strategy for dual three-phase induction motor drives is discussed in this paper. The induction machine has two sets of stator three-phase windings spatially shifted by 30 electrical degrees. The DTC strategy is based on a predictive algorithm and is implemented in a synchronous reference frame aligned with the machine stator flux vector. The advantages of the discussed control strategy are constant inverter switching frequency, good transient and steady-state performance, and low distortion of machine currents with respect to direct self-control (DSC) and other DTC schemes with variable switching frequency. Experimental results are presented for a 10-kW DTC dual three-phase induction motor drive prototype

Alone Self-Excited Induction Generators

In recent years, some converter structures and analyzing methods for the voltage regulation of stand-alone self-excited induction generators (SEIGs) have been introduced. However, all of them are concerned with the three-phase voltage control of three-phase SEIGs or the single-phase voltage control of single-phase SEIGs for the operation of these machines under balanced load conditions. In this paper, each phase voltage is controlled separately through separated converters, which consist of a full-bridge diode rectifier and one-IGBT. For this purpose, the principle of the electronic load controllers supported by fuzzy logic is employed in the two-different proposed converter structures. While changing single phase consumer loads that are independent from each other, the output voltages of the generator are controlled independently by three-number of separated electronic load controllers (SELCs) in two different mode operations. The aim is to obtain a rated power from the SEIG via the switching of the dump loads to be the complement of consumer load variations. The transient and steady state behaviors of the whole system are investigated by simulation studies from the point of getting the design parameters, and experiments are carried out for validation of the results. The results illustrate that the proposed SELC system is capable of coping with independent consumer load variations to keep output voltage at a desired value for each phase. It is also available for unbalanced consumer load conditions. In addition, it is concluded that the proposed converter without a filter capacitor has less harmonics on the currents

Comparison of Induction and PM Synchronous motor drives for EV application including design examples

Three different motor drives for electric traction are compared, in terms of output power and efficiency at the same stack dimensions and inverter size. Induction motor (IM), surface-mounted permanent-magnet (PM) (SPM), and interior PM (IPM) synchronous motor drives are investigated, with reference to a common vehicle specification. The IM is penalized by the cage loss, but it is less expensive and inherently safe in case of inverter unwilled turnoff due to natural de-excitation. The SPM motor has a simple construction and shorter end connections, but it is penalized by eddy-current loss at high speed, has a very limited transient overload power, and has a high uncontrolled generator voltage. The IPM motor shows the better performance compromise, but it might be more complicated to be manufactured. Analytical relationships are first introduced and then validated on three example designs and finite element calculated, accounting for core saturation, harmonic losses, the effects of skewing, and operating temperature. The merits and limitations of the three solutions are quantified comprehensively and summarized by the calculation of the energy consumption over the standard New European Driving Cycl

Lead pursuit control of multiphase drives

Los accionamientos multifásicos, compuestos por una máquina eléctrica de más de tres fases alimentada por un convertidor de potencia, han atraído recientemente un importante interés en la comunidad investigadora debido a las ventajas que presentan frente a las máquinas trifásicas convencionales. Este es el caso de la mejor distribución de potencia por fase, la menor producción de armónicos en el convertidor de potencia y, la más importante, la tolerancia a fallos, lo cual significa que la máquina multifásica puede seguir funcionando cuando una o varias fases se pierden, siempre que el número restante de fases sea igual o mayor que tres. Debido a esta alta fiabilidad, los accionamientos multifásicos son especialmente adecuados para aplicaciones relacionadas con los vehículos eléctricos (terrestres, marítimos y aéreos) y las energías renovables por razones de seguridad y/o económicas. El uso de controladores avanzados y de alto rendimiento en accionamientos multifásicos es particularmente relevante, ya que las estrategias de control convencionalmente aplicadas a los accionamientos trifásicos no terminan de alcanzar un estándar en su extensión al caso multifásico. La razón es la mayor complejidad y número de variables a controlar. En este contexto, los controladores predictivos han encontrado un interesante nicho de aplicación en convertidores de potencia y accionamientos multifásicos debido a su formulación intuitiva y flexible: un modelo del sistema es usado para calcular las predicciones de las variables controladas, que luego se comparan con las referencias impuestas dentro de una función de coste. Esta estrategia permite incorporar varios objetivos de control y restricciones en el proceso de control a través de la función de coste. Sin embargo, es bien sabido que este tipo de controlador sufre de un alto coste computacional y contenido armónico de corriente que limita su aplicación en los accionamientos multifásicos. La investigación desarrollada en esta Tesis se centra en la mitigación de las limitaciones citadas siguiendo dos objetivos principales: • La incorporación de observadores de corrientes rotóricas en el controlador predictivo para mejorar así la precisión del modelo predictivo y, consecuentemente, el rendimiento del sistema de control, principalmente en términos de contenido armónico y pérdidas por conmutación en el convertidor de potencia. Un observador de Luenberger es construido para este propósito utilizando una estrategia innovadora de posicionamiento de polos en su diseño. • La introducción de un grado de libertad adicional en el controlador predictivo basado en tiempos de muestreo variables e implementado usando el concepto de lead pursuit. El resultado es un controlador novedoso que conduce a una resolución en los tiempos de conmutación más fina en comparación con las técnicas predictivas más convencionales, lo que proporciona una reducción importante en el contenido armónico. Las estrategias de control propuestas son validadas mediante simulación y experimentación utilizando un accionamiento compuesto por una máquina de inducción de cinco fases como caso de ejemplo. Los resultados y conclusiones derivadas de esta investigación han sido presentados en cinco trabajos principales publicados en revistas internacionales de alto impacto, los cuales constituyen las contribuciones de esta Tesis por compendio de artículos. Sin embargo, otros trabajos relacionados con la línea de investigación han sido también publicados en artículos de revista y conferencia y en un capítulo de libro.Multiphase drives, constituted by an electric machine with more than three phases fed by a power converter, have recently attracted an important interest in the research community due to the advantages that they present over the conventional three-phase ones. This is the case of the better power distribution per phase, the lower harmonic production in the power converter, and the most important one, the fault-tolerant capability, which means that the multiphase machine can still be operated when one or several phases are missing, provided that the number of remaining phases is equal or greater than three. Due to this high reliability, multiphase drives are specially well suited for applications related to electric vehicles (terrestrial, maritime and aerial) and renewable energies for safety and/or economical reasons. The use of advanced and high-performance controllers in multiphase drives is particularly relevant, since the control strategies conventionally applied to three-phase drives do not reach a standard in their extension to the multiphase case. The reason is the greater complexity and number of variables that must be controlled. In this context, predictive controllers have found an interesting niche of application in power converters and multiphase drives due to their intuitive and flexible formulation: a model of the system is used to compute predictions of the controlled variables, which are later compared with the imposed references in a cost function. This strategy permits incorporating several control objectives and constraints in the control process through the cost function. However, it is well known that this type of controller suffers from a high computational cost and current harmonic content that limit its application in multiphase drives. The research developed in this Thesis work is focused on the mitigation of the cited limitations following two main goals: • The incorporation of rotor current observers in the predictive controller in order to improve the accuracy of the predictive model and, consequently, the control system performance, principally in terms of harmonic content and commutation losses in the power converter. A Luenberger observer is constructed for that purpose using an innovative pole-placement strategy in its design. • The introduction of an additional degree of freedom in the predictive controller based on variable sampling times and implemented using the lead-pursuit concept. The result is a novel controller that leads to a finer resolution in the commuting times in comparison with more conventional predictive techniques, which provides an important reduction in the harmonic content. The proposed control strategies are validated by simulation and experimentation using a five-phase induction machine drive as case example. The results and conclusions derived from this research have been presented in five main works published in high-impact international journals, which constitute the contributions of this article compendium Thesis. Nevertheless, other related works have also been published in journal and conference papers and a book chapter

Performance of Induction Machines

Induction machines are one of the most important technical applications for both the industrial world and private use. Since their invention (achievements of Galileo Ferraris, Nikola Tesla, and Michal Doliwo-Dobrowolski), they have been widely used in different electrical drives and as generators, thanks to their features such as reliability, durability, low price, high efficiency, and resistance to failure. The methods for designing and using induction machines are similar to the methods used in other electric machines but have their own specificity. Many issues discussed here are based on the fundamental achievements of authors such as Nasar, Boldea, Yamamura, Tegopoulos, and Kriezis, who laid the foundations for the development of induction machines, which are still relevant today. The control algorithms are based on the achievements of Blaschke (field vector-oriented control) and Depenbrock or Takahashi (direct torque control), who created standards for the control of induction machines. Today’s induction machines must meet very stringent requirements of reliability, high efficiency, and performance. Thanks to the application of highly efficient numerical algorithms, it is possible to design induction machines faster and at a lower cost. At the same time, progress in materials science and technology enables the development of new machine topologies. The main objective of this book is to contribute to the development of induction machines in all areas of their applications

Trends in Fault Diagnosis for Electrical Machines

[EN] The fault diagnosis of rotating electrical machines has received an intense amount of research interest during the last 30 years. Reducing maintenance costs and preventing unscheduled downtimes, which result in losses of production and financial incomes, are the priorities of electrical drives manufacturers and operators. In fact, both correct diagnosis and early detection of incipient faults lead to fast unscheduled maintenance and short downtime for the process under consideration. They also prevent the harmful and sometimes devastating consequences of faults and failures. This topic has become far more attractive and critical as the population of electric machines has greatly increased in recent years. The total number of operating electrical machines in the world was around 16.1 billion in 2011, with a growth rate of about 50% in the last five years [1].Henao, H.; Capolino, G.; Fernández-Cabanas, M.; Filippetti, F.; Bruzzese, C.; Strangas, E.; Pusca, R.... (2014). Trends in Fault Diagnosis for Electrical Machines. IEEE Industrial Electronics Magazine. 8(2):31-42. doi:10.1109/MIE.2013.2287651S31428

Semi-Analytical Approach Towards Design and Optimization of Induction Machines for Electric Vehicles

Electric machine design is a comprehensive task depending on the several factors, such as material resource limitations and economic factors. Therefore, an induction machine is a promising candidate because of the absence of magnetic material in the rotor. However, the conventional design approach can neither reflect the advances of the induction machine(IM) design nor exploit the trade-offs between design factors and the multi-physics nature of the electrical machine. Therefore, proposing fast and accurate novel methods to design, develop and analyze IMs using electromagnetic field oriented approaches is competitive to the old-fashion numerical methods. To achieve improved IM design from a baseline design to an optimal design, this dissertation: (1) Investigates the challenges of the high speed IM design specified for the electric vehicle application at the rated operating condition considering electromagnetic boundaries for the reasonable saturation level within a compact volume; (2) Proposes a new design approach of IM using modified equivalent circuit parameters to reduce spatial harmonics because of slotting effect and skewing effect; and also presents the importance of the 3-D analysis over 2-D analysis while developing the IM; (3) Proposes a novel electromagnetic field oriented mathematical model considering the slotting effect and axial flux variation because of skewing rotor bars to evaluate the IM performance with a lower and precise computational effort; (4) developed baseline IM is optimized with genetic algorithm incorporated in proposed subdomain model to improve the torque-speed profile. In order to further simplify the optimization procedure, a parametric and sensitivity based design approach is implemented to reduce the design variables. To evaluate the proposed optimal IM with extended constant power region and high torque density within a compact volume using novel 3-D subdomain model, the machine has been prototyped and tested from low to high speed under no-load and loaded condition. Electrical circuit parameter variation is demonstrated and compared to the one simulated in the FEA environment. This innovation can be applied to a family of electric machines with various topologies

Imitation model of a high-speed induction motor with frequency control

Purpose. To develop the imitation model of the frequency converter controlled high-speed induction motor with a squirrel-cage rotor in order to determine reasons causes electric motor vibrations and noises in starting modes. Methodology. We have applied the mathematical simulation of electromagnetic field in transient mode and imported obtained field model as an independent object in frequency converter circuit. We have correlated the simulated result with the experimental data obtained by means of the PID regulator factors. Results. We have made the simulation model of the high-speed induction motor with a squirrel-cage rotor speed control in AnsysRMxprt, Ansys Maxwell and Ansys Simplorer, approximated to their physical prototype. We have made models modifications allows to provide high-performance computing (HPC) in dedicated server and computer cluster to reduce the simulation time. We have obtained motor characteristics in starting and rated modes. This allows to make recommendations on determination of high-speed electric motor optimal deign, having minimum indexes of vibrations and noises. Originality. For the first time, we have carried out the integrated research of induction motor using simultaneously simulation models both in Ansys Maxwell (2D field model) and in Ansys Simplorer (transient circuit model) with the control low realization for the motor soft start. For the first time the correlation between stator and rotor slots, allows to obtain minimal vibrations and noises, was defined. Practical value. We have tested manufactured high-speed motor based on the performed calculation. The experimental studies have confirmed the adequacy of the model, which allows designing such motors for new high-speed construction, and upgrade the existing ones.Разработана имитационная модель высокоскоростного асинхронного двигателя с короткозамкнутым ротором при скалярном частотном управлении в программном пакете AnsysMaxwell&Simplorer. При моделировании на кластере высокопроизводительных расчетов выполнены параллельные вычисления полевой модели электродвигателя (AnsysMaxwell 2D) и модели, построенной на основе теории цепей (Ansys Simplorer), что позволило создать имитационные модели, приближенные к их физическим прототипам. Выполнен анализ пусковых характеристик, оптимизированы параметры электродвигателя. Даны рекомендации по выбору числа пазов статора и ротора высокоскоростного асинхронного двигателя, что позволило существенно уменьшить вибрации и шумы в режиме пуска

High-speed induction motor with an integrated gearbox for propulsion

Induction motors with a planetary gear are a viable option for the transportation industry as they are a relatively inexpensive electric drive solution. Designing a prototype of a high-speed induction motor with a planetary gear is the focus of this project. This will be the proof of concept, to demonstrate a compact and cost-efficient electric drive solution, when compared to electric drives with lower speeds and no gearbox. Using a high-speed electric motor and gearing it down will provide a high torque density and power. A prototype with a high power density and efficiency will provide a competitive alternative to other electric drive solutions. The design choices of the prototype are covered. 3D modeling software is used for the mechanical design that integrates the planetary gear and the induction motor. Finite Element Method (FEM) simulations are completed to determine the final design. The geometry and properties of the induction motor are optimized using FEM. Electromagnetics, torque, and the losses of the induction motor are analyzed. The prototype design presented in this thesis is analyzed to determine the overall efficiency, cost, and feasibility for the transportation industry. The design allows for future development by ensuring easy changes and additions that can be made to the prototype. The development of the high-speed motor should continue with the use of models and design presented in this thesis. The design presented in this thesis is another step towards the final prototype production. The possibilities for future thesis topics and improvements will be discussed at the end of this thesis. One possibility for future development is the use of additive manufacturing to build the induction motor

Predictive current control in electrical drives: an illustrated review with case examples using a five-phase induction motor drive with distributed windings

The industrial application of electric machines in variable-speed drives has grown in the last decades thanks to the development of microprocessors and power converters. Although three-phase machines constitute the most common case, the interest of the research community has been recently focused on machines with more than three phases, known as multiphase machines. The principal reason lies in the exploitation of their advantages like reliability, better current distribution among phases or lower current harmonic production in the power converter than conventional three-phase ones, to name a few. Nevertheless, multiphase drives applications require the development of complex controllers to regulate the torque (or speed) and flux of the machine. In this regard, predictive current controllers have recently appeared as a viable alternative due to an easy formulation and a high flexibility to incorporate different control objectives. It is found however that these controllers face some peculiarities and limitations in their use that require attention. This work attempts to tackle the predictive current control technique as a viable alternative for the regulation of multiphase drives, paying special attention to the development of the control technique and the discussion of the benefits and limitations. Case examples with experimental results in a symmetrical five-phase induction machine with distributed windings in motoring mode of operation are used to this end