Cogging torque reduction in brushless motors by a nonlinear control technique

This work addresses the problem of mitigating the effects of the cogging torque in permanent magnet synchronous motors, particularly brushless motors, which is a main issue in precision electric drive applications. In this work, a method for mitigating the effects of the cogging torque is proposed, based on the use of a nonlinear automatic control technique known as feedback linearization that is ideal for underactuated dynamic systems. The aim of this work is to present an alternative to classic solutions based on the physical modification of the electrical machine to try to suppress the natural interaction between the permanent magnets and the teeth of the stator slots. Such modifications of electric machines are often expensive because they require customized procedures, while the proposed method does not require any modification of the electric drive. With respect to other algorithmic-based solutions for cogging torque reduction, the proposed control technique is scalable to different motor parameters, deterministic, and robust, and hence easy to use and verify for safety-critical applications. As an application case example, the work reports the reduction of the oscillations for the angular position control of a permanent magnet synchronous motor vs. classic PI (proportional-integrative) cascaded control. Moreover, the proposed algorithm is suitable to be implemented in low-cost embedded control units

Noise and Vibration Reduction in Permanent Magnet Synchronous Motors –A Review

A detailed study of the mechanics of vibration and acoustic noise in permanent magnet synchronous motors due to electromagnetic origins. This paper reviews the various noise and vibrations reduction strategies from classical to state of art techniques. The recent research in development of wavelet controller, starting from brief review and the analytical analysis of acoustic noise and vibrations in Permanent magnet synchronous motor is presented. Application of wavelet transforms in the area of denoising and filtering is also explored.DOI:http://dx.doi.org/10.11591/ijece.v2i3.32

Evolution and Modern Approaches for Thermal Analysis of Electrical Machines

In this paper, the authors present an extended survey on the evolution and the modern approaches in the thermal analysis of electrical machines. The improvements and the new techniques proposed in the last decade are analyzed in depth and compared in order to highlight the qualities and defects of each. In particular, thermal analysis based on lumped-parameter thermal network, finite-element analysis, and computational fluid dynamics are considered in this paper. In addition, an overview of the problems linked to the thermal parameter determination and computation is proposed and discussed. Taking into account the aims of this paper, a detailed list of books and papers is reported in the references to help researchers interested in these topics

Tradeoffs between AC power quality and DC bus ripple for 3-phase 3-wire inverter-connected devices within microgrids

Visions of future power systems contain high penetrations of inverters which are used to convert power from dc (direct current) to ac (alternating current) or vice versa. The behavior of these devices is dependent upon the choice and implementation of the control algorithms. In particular, there is a tradeoff between dc bus ripple and ac power quality. This study examines the tradeoffs. Four control modes are examined. Mathematical derivations are used to predict the key implications of each control mode. Then, an inverter is studied both in simulation and in hardware at the 10 kVA scale, in different microgrid environments of grid impedance and power quality. It is found that voltage-drive mode provides the best ac power quality, but at the expense of high dc bus ripple. Sinusoidal current generation and dual-sequence controllers provide relatively low dc bus ripple and relatively small effects on power quality. High-bandwidth dc bus ripple minimization mode works well in environments of low grid impedance, but is highly unsuitable within higher impedance microgrid environments and/or at low switching frequencies. The findings also suggest that the certification procedures given by G5/4, P29 and IEEE 1547 are potentially not adequate to cover all applications and scenarios

Probabilistic Model-Based Safety Analysis

Model-based safety analysis approaches aim at finding critical failure combinations by analysis of models of the whole system (i.e. software, hardware, failure modes and environment). The advantage of these methods compared to traditional approaches is that the analysis of the whole system gives more precise results. Only few model-based approaches have been applied to answer quantitative questions in safety analysis, often limited to analysis of specific failure propagation models, limited types of failure modes or without system dynamics and behavior, as direct quantitative analysis is uses large amounts of computing resources. New achievements in the domain of (probabilistic) model-checking now allow for overcoming this problem. This paper shows how functional models based on synchronous parallel semantics, which can be used for system design, implementation and qualitative safety analysis, can be directly re-used for (model-based) quantitative safety analysis. Accurate modeling of different types of probabilistic failure occurrence is shown as well as accurate interpretation of the results of the analysis. This allows for reliable and expressive assessment of the safety of a system in early design stages

Design Synthesis and Optimization of Permanent Magnet Synchronous Machines Based on Computationally-Efficient Finite Element Analysis

In this dissertation, a model-based multi-objective optimal design of permanent magnet ac machines, supplied by sine-wave current regulated drives, is developed and implemented. The design procedure uses an efficient electromagnetic finite element-based solver to accurately model nonlinear material properties and complex geometric shapes associated with magnetic circuit design. Application of an electromagnetic finite element-based solver allows for accurate computation in intricate performance parameters and characteristics. The first contribution of this dissertation is the development of a rapid computational method that allows accurate and efficient exploration of large multi-dimensional design spaces in search of optimum design(s). The computationally efficient finite element-based approach developed in this work provides a framework of tools that allow rapid analysis of synchronous electric machines operating under steady-state conditions. In the developed modeling approach, major steady-state performance parameters such as, winding flux linkages and voltages, average, cogging and ripple torques, stator core flux densities, core losses, efficiencies and saturated machine winding inductances, are calculated with minimum computational effort. In addition, the method includes means for rapid estimation of distributed stator forces and three-dimensional effects of stator and/or rotor skew on the performance of the machine. The second contribution of this dissertation is the development of the design synthesis and optimization method based on a differential evolution algorithm. The approach relies on the developed finite element-based modeling method for electromagnetic analysis and is able to tackle large-scale multi-objective design problems using modest computational resources. Overall, computational time savings of up to two orders of magnitude are achievable, when compared to current and prevalent state-of-the-art methods. These computational savings allow one to expand the optimization problem to achieve more complex and comprehensive design objectives. The method is used in the design process of several interior permanent magnet industrial motors. The presented case studies demonstrate that the developed finite element-based approach practically eliminates the need for using less accurate analytical and lumped parameter equivalent circuit models for electric machine design optimization. The design process and experimental validation of the case-study machines are detailed in the dissertation

An innovative natural air-cooling system technique for temperature-rise suppression on the permanent magnet synchronous machines

Peer ReviewedPostprint (author's final draft

Pipeline-Based Power Reduction in FPGA Applications

This paper shows how temporal parallelism has an important role in the power dissipation reduction in the FPGA field. Glitches propagation is blocked by the flip-flops or registers in the pipeline. Several multiplication structures are implemented over modern FPGAs, StratixII and Virtex4, comparing their results with and without pipeline and hardware duplication

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