Extension of Finite-Control Set Model-Based Predictive Control Techniques to Fault-Tolerant Multiphase Drives: Analysis and Contributions

Las máquinas eléctricas son una de las principales tecnologías que hacen posible las energías renovables y los vehículos eléctricos. La necesidad constante de incrementar la capacidad de potencia para generar más energía o para impulsar vehículos cada vez más grandes, ha motivado la investigación y el desarrollo en el área de las máquinas multifásicas las cuales, gracias a su número de fases, permiten no sólo manejar más potencia con menos pulsaciones de par y contenido armónico en la corriente que las máquinas trifásicas convencionales, sino que también permiten obtener una mayor tolerancia a fallos, aumentando el interés de su implementación en aplicaciones donde la fiabilidad juega un papel importante por razones económicas y de seguridad. La investigación más reciente en el área de sistemas multifásicos se centra en el desarrollo de técnicas que permitan explotar las características específicas y especiales de las máquinas multifásicas, viendo el incremento en el número de fases no como un aumento en la complejidad de implementación, sino como un mayor número de grados de libertad tanto en el diseño como en el control, permitiendo mejorar sus prestaciones y fiabilidad, haciéndolas más atractivas para su uso en aplicaciones industriales. Es así como se han desarrollado técnicas de control que permitan operar a alta velocidad o alto par, tolerancia a diferentes tipos de fallos y máquinas con diferentes conexionados de devanados o con sistemas formados por múltiples variadores y máquinas. El objetivo de esta tesis doctoral es la extensión del control predictivo para máquinas multifásicas (específicamente el control predictivo de estados finitos basado en modelo o FCS-MPC por sus siglas en inglés) a la operación tolerante a fallos, aprovechando la capacidad de tolerancia a fallos que las máquinas multifásicas poseen, asegurando su funcionamiento de una manera eficiente y controlada. Con este fin se estudió el modelo matemático de la máquina en condiciones de pre- y post- falta considerando diferentes tipos de faltas, permitiendo establecer el efecto que las condiciones de fallo tienen en el comportamiento del sistema. Se desarrollaron modelos de simulación de una máquina de inducción de cinco fases, considerando faltas de fase abierta y en el disparo de los IGBT’s de una fase, permitiendo el diseño y validación del controlador FCS-MPC tolerante a fallos, cuyos resultados obtenidos fueron presentados en diversos congresos internacionales. La posterior implementación y validación experimental del control tolerante a fallos propuesto dio lugar a la publicación de dos de los artículos científicos presentados en esta tesis. Del mismo modo, se desarrolló un control tolerante a fallos basado en controladores lineales (de tipo resonante), teniendo en cuenta los esquemas propuestos en publicaciones científicas recientes y se realizó una comparativa entre el control tolerante a fallos basado en FCS-MPC y el controlador resonante ante un fallo de fase abierta, mediante resultados de simulación y experimentales, dando lugar a la publicación en un congreso internacional y en un artículo de revista científica. Las contribuciones de esta tesis doctoral se han publicado en la revista científica IEEE Transactions on Industrial Electronics entre los años 2013/2015

Multiphase induction motor drives - a technology status review

The area of multiphase variable-speed motor drives in general and multiphase induction motor drives in particular has experienced a substantial growth since the beginning of this century. Research has been conducted worldwide and numerous interesting developments have been reported in the literature. An attempt is made to provide a detailed overview of the current state-of-the-art in this area. The elaborated aspects include advantages of multiphase induction machines, modelling of multiphase induction machines, basic vector control and direct torque control schemes and PWM control of multiphase voltage source inverters. The authors also provide a detailed survey of the control strategies for five-phase and asymmetrical six-phase induction motor drives, as well as an overview of the approaches to the design of fault tolerant strategies for post-fault drive operation, and a discussion of multiphase multi-motor drives with single inverter supply. Experimental results, collected from various multiphase induction motor drive laboratory rigs, are also included to facilitate the understanding of the drive operatio

Optimal Fault-Tolerant Control of Six-Phase Induction Motor Drives with Parallel Converters

Multiphase drives and parallel converters have been recently proposed in low-voltage high-power applications. The fault-tolerant capability provided by multiphase drives is then extended with parallel converters, increasing their suitability for safety-critical and renewable uses. This advantageous feature, compared to standard threephase drives, has been analyzed in the event of open-phase faults. However, when using parallel converters, a converter fault does not necessarily imply an open-phase condition, but usually just a limited phase current capability. This work analyzes the fault-tolerant capability of six-phase drives with parallel converter supply. Different scenarios considering up to three faults for single and two neutral configurations are examined, optimizing off-line the post-fault currents and modifying accordingly the control strategies. Experimental results confirm the smooth transition from pre- to post-fault situations and the enhanced post-fault torque capability.Ministerio de Ciencia e Innovación ENE2014- 52536-C2-1-R DPI2013-44278-RJunta de Andalucía P11-TEP-755

Induction Motors

AC motors play a major role in modern industrial applications. Squirrel-cage induction motors (SCIMs) are probably the most frequently used when compared to other AC motors because of their low cost, ruggedness, and low maintenance. The material presented in this book is organized into four sections, covering the applications and structural properties of induction motors (IMs), fault detection and diagnostics, control strategies, and the more recently developed topology based on the multiphase (more than three phases) induction motors. This material should be of specific interest to engineers and researchers who are engaged in the modeling, design, and implementation of control algorithms applied to induction motors and, more generally, to readers broadly interested in nonlinear control, health condition monitoring, and fault diagnosis

Power Sharing Algorithm for Vector Controlled Six-Phase AC Motor with Four Customary Three-Phase Voltage Source Inverter Drive

This paper considered a six-phase (asymmetrical) induction motor, kept 30\ub0 phase displacement between two set of three-phase open-end stator windings configuration. The drive system consists of four classical three-phase voltage inverters (VSIs) and all four dc sources are deliberately kept isolated. Therefore, zero-sequence/homopolar current components cannot flow. The original and effective power sharing algorithm is proposed in this paper with three variables (degree of freedom) based on synchronous field oriented control (FOC). A standard three-level space vector pulse width modulation (SVPWM) by nearest three vectors (NTVs) approach is adopted to regulate each couple of VSIs. The proposed power sharing algorithm is verified by complete numerical simulation modeling (Matlab/Simulink-PLECS software) of whole ac drive system by observing the dynamic behaviors in different designed condition. Set of results are provided in this paper, which confirms a good agreement with theoretical development

A Multifunctional SiC DC-DC Converter Topology with Normalized Fault Detection Strategy for Electric Vehicle Applications

The automotive industry is experiencing a monumental shift in technology and propulsion strategies. More than ever before, car manufacturers and suppliers are shifting development and funding away from combustion engines in favor of electrified powertrains. One of the main obstacles contributing to customers reluctance to buy EVs is the lack of infrastructure for charging. Traditional 110/220VAC outlets equipped at residential buildings are relatively low power compared to the batteries used in EVs today. These AC chargers, classified as level 1 and level 2, will take approximately 12-24 hours to completely charge a battery, depending on battery size and state-of-charge. Additionally, because this method of charging uses alternating current, vehicles must have chargers on-board to convert the energy from AC to DC to recharge the battery because EV batteries are direct current energy sources. Millions of dollars from the government and private companies are being invested to create an adequate DC fast charging infrastructure. The advantages of DC charging are two-fold, much quicker charging times and the elimination of onboard chargers. However, there is one blatant problem with current investments into a DC charging infrastructure – technological advancement. Most electric vehicles in production have battery pack voltages between 300V and 400V and current DC fast chargers are being developed for the current technology. This will likely change rather quickly; the development of wide-bandgap devices will allow for higher voltage devices. Furthermore, the energy densities of batteries will also likely improve, allowing for higher bus voltages. Higher bus voltages will offer several advantages over current architectures – more power, smaller devices, improved efficiencies, and more. The problem is, once higher bus voltages are achieved and popularized, the current fast charging infrastructure will be deemed obsolete. An intermediate solution needs to be developed to allow higher bus voltage vehicles to continue to utilize the current fast chargers being deployed nation-wide. The proposed DC-DC converter is a practical design that offers multiple purposes when implemented in electric vehicles that utilize permanent magnet synchronous machines (PMSM) and bus voltages of ~800V. It consists of a bi-directional interleaved DC-DC cascaded with an isolated full bridge converter. This configuration provides a 12V source with galvanic isolation during normal propulsion. The interleaved converter can boost in reverse to allow for charging of the 800V bus with current generation DC fast chargers operating at ~400V. Finally, an inverter fault detection methodology has been realized to take advantage of the interleaved DC-DC structure. If an open switch fault is detected on any of the 3-phases driving the PMSM, the appropriate phase-leg is isolated, and a phase-leg from the interleaved DC-DC is used to maintain propulsion. This is realized by monitoring the phase currents of the AC motor and analyzing the difference in value between all three. A threshold value is implemented in C-code, not contingent on the system parameters. A difference of phase currents greater than the threshold value is a clear indication that an open switch fault has occurred. The proposed power conversion structure and the motor inverter fault detection, isolation, and compensation approaches are verified by a PSIM simulation. The simulation results successfully validate the feasibility of proposed electric powertrain structure and inverter switch fault detection and compensation methods.Master of Science in EngineeringEnergy Systems Engineering, College of Engineering & Computer ScienceUniversity of Michigan-Dearbornhttp://deepblue.lib.umich.edu/bitstream/2027.42/156398/1/Brandon Pieniozek Final Thesis.pdfDescription of Brandon Pieniozek Final Thesis.pdf : Thesi

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

High Performance Control Techniques for Multiphase eDrives

L'abstract è presente nell'allegato / the abstract is in the attachmen

Multiphase electric drives for "More Electric Aircraft" applications

Advances in power electronic and machine control techniques are making the inverter-fed drives an always more attractive solution. Because of the number of inverter legs is arbitrary, also the number of phases results as a further degree of freedom for the machine design. Therefore, the multiphase winding is often a possible solution. Due to the increasing demand for high performance and high power variable speed drives, the research on multiphase machines has experienced a significant growth in the last two decades. Indeed, one of the main advantages of the multiphase technology is the possibility of splitting the power of the system across a higher number of power electronic devices with a reduced rating. A similar result can be obtained by using multi-level converters. However, the redundancy of the phases leads to an increased reliability of the machine and to the introduction of additional degrees of freedom in the current control and the machine design. This work aims to study and analyze the highly reliable and fault tolerant machines. It proposes innovative solutions for multiphase machine design and control to meet the safety-critical requirements in “More-Electric Aircraft” (MEA) and “More Electric Engine” (MEE) in which thermal, pneumatic or hydraulic drives in aerospace applications are replaced with electric ones. Open phase, high resistance and short circuit faults are investigated. Fault tolerant controls and fault detection algorithms are presented. Radial force control techniques and bearingless operation are verified and improved for various working scenarios. Fault tolerant designs of multiphase machines are also proposed

Fault tolerant vector control of five-phase permanent magnet motors

Equipped with appropriate control strategies, permanent magnet (PM) machines are becoming one of the most flexible types of actuators for many industrial applications. Among different types of PM machines, five-phase BLDC machines are very interesting in fault tolerant applications of PM drives. Torque improvement in five-phase BLDC machines can be accomplished by optimizing their mechanical structure or by enhancing their controlling methods. New current controllers are proposed in this thesis to improve the quality of generated torque under normal operations of five-phase BLDC machines. Proposed current controllers are based on combination of predictive deadbeat controlling strategy and Extended Kalman Filter estimation. These controllers will be the basis for accurate faulty operation of the motor. Operation of five-phase BLDC machines under faulty conditions has also been considered in this study. To improve the generated torque under faulty conditions, both amplitude and phase angle of fundamental and third current harmonics are globally optimized for the remaining healthy phases. Under faulty conditions, appropriate reference currents of a five-phase BLDC machine have oscillating dynamics both in phase and rotating reference frames. As a result, the implemented current controllers under these conditions should be robust and fast. Predictive deadbeat controllers are also proposed for faulty conditions of five-phase BLDC machines. Fault tolerant five-phase BLDC machines are very interesting in automotive applications such as electrical vehicles and more electric aircraft. In addition, these devices are gaining more importance in other fields such as power generation in wind turbines. In all of these applications, the efficiency of PM machine is of most importance. The efficiency of a typical five-phase BLDC machine is evaluated in this thesis for normal and different faulty conditions. Experimental evaluations are always conducted to verify the theoretical developments. These developments include proposed controlling methods, optimized reference currents, and simulated efficiency of five-phase BLDC machine under different operational conditions