LABORATORIO DE INVESTIGACIÓN EN MÁQUINAS ELÉCTRICAS

 
Tesis Doctorales y Publicaciones
  

      
Tesis doctorales:

  • Atencia J., "Diseño, Modelización, Construcción y Control de Motor Lineal de Inducción". Tesis Doctoral. San Sebastián. Abril 2002.

Resumen de la tesis:

Design, Modelling, Construction and Control of Linear Induction Motor. 2002. F. Javier Atencia Fernández. Escuela Superior de Ingenieros, University of Navarra (Spain). Calificación: Sobresaliente Cum Laude.

The objective of this Doctoral Thesis is to achieve a deep knowledge of Linear Induction Motors, from the point of view of the new possible applications due to the modern control strategies of rotary machines. Thus, an exhaustive bibliographical review has been made, a laboratory prototype has been constructed, and new ways of characterizing it have been explored.

After that, a comparative study of modelling LIMs as actuators has been performed. The importance of this study has been recognised with a Price at the LDIA2001 (Linear Drives for Industry Applications). This symposium has taken place in Nagano, Japan, and it is the only international congress specific of linear actuators.

In order to compare the advantages and problems involved in controlling LIMs, several control strategies have been implemented with the prototype. The results of speed and position control are presented, as well as the criteria used in order to compare the controls.

From all the information obtained by modelling and controlling the prototype, some design guides are proposed, and also some criteria for setting the specifications of LIMs.

Key words: Linear Induction Motor. Linear Machines. Drives Control.

  • Martínez-Iturralde, M., "Diseño de una nueva Estrategia de Control Vectorial para Motores Lineales de Inducción". Tesis Doctoral. San Sebastián. Junio 2005.

Resumen de la tesis:

Design of a new Vectorial Control Strategy for Linear Induction Motors. 2005. Miguel Martínez-Iturralde Maiza. Escuela Superior de Ingenieros, University of Navarra (Spain). Calificación: Sobresaliente Cum Laude.

The linear induction motor (LIM) adds up all the advantages of being a direct drive to the known characteristics of their rotary counterparts, that is, robustness and low cost.

 Traditionally, this kind of motors has been used in conveyance and transportation applications. However, in the last years, the reduction of the cost of power electronics and microprocessors, has made these motors suitable for tasks which require high speed and accurate positioning.

Dealing with speed and position control of linear induction motors, most strategies in bibliography are based on Secondary Flux Oriented Control (SFOC) and Direct Thrust Control (DTC). However, SFOC of linear induction motors needs complex identification methods to compensate parameter variation during operation, mainly due to local heating and end-effects. On the other hand, DTC based methods for LIMs introduce thrust ripple and have problems at low and zero speed.

In this doctoral thesis, a new speed and position control strategy for linear induction motors that makes up for these drawbacks is presented.

The primary flux control algorithm is stated for normal and full-voltage operation. Moreover, the speed and position control loops design methodology and the method for automatic adjustment of compensators are presented.

Experimental results are presented to evaluate the performance of the control strategy and, also, its sensitivity to the variation of the linear induction motor parameters.

Finally, some conclusions are drawn about the applicability of the new algorithm that demonstrate the main advantages versus Secondary Flux Oriented Control and Direct Thrust Control.

Key words: linear motors, parameter identification, field oriented control, position control.

  • Martínez, G., "Optimización del comportamiento dinámico de motores lineales síncronos de imanes permanentes". Tesis Doctoral. San Sebastián. Octubre 2005.

Resumen de la tesis:

Dynamic performance optimization of permanent magnet linear synchronous motors. 2005. Gonzalo Martínez Díez. Escuela Superior de Ingenieros, University of Navarra (Spain). Calificación: Sobresaliente Cum Laude.

Linear synchronous motors are a very interesting option when thinking about linear actuators. The conventional linear systems consisting of a rotary motor and mechanical devices used to convert rotation to displacement are being replaced by linear electric motors in many industrial applications. Among linear synchronous motors, permanent magnet motors are the most commonly used in industry.

In Permanent Magnet Linear Synchronous Motors, the magnetic field of the secondary is produced by permanent magnets instead of other methods such as DC coils. This kind of motors presents some characteristic forces that are usually undesired because they produce disturbances in the motor motion. These forces reduce the dynamic features and the precision of the motor, and they are the cogging force (or detent force) and the normal forces between the primary and the secondary of the motor. Normal forces also generate big stresses in the structure.

Cogging force has the same direction as the motor motion and cause disturbances in the production of thrust. Normal forces are perpendicular to the motor motion and cause big stresses in the structure, increase friction losses and audible noise. They also can generate undesired mechanical vibrations. First of all, cogging force was analysed, and various methods to reduce it were developed. Secondly, normal forces were studied, and a control strategy to control these forces was developed. All the tasks were validated by means of the Finite Element Method and experimental tests.

The target of this thesis is to obtain a method of designing, constructing and controlling Permanent Magnet Linear Synchronous Motors that can achieve the more and more demanding dynamic features that industry requires for this kind of actuators.

Key words: linear motors, cogging force, attraction forces, optimization.

 

Listado de Publicaciones:

Desde la creación del grupo se han publicado veinte papers, entre artículos y comunicaciones a congresos, uno mereció el Premio a la Excelencia en la conferencia sobre accionamientos lineales, LDIA, en Nagano (Japón), Octubre de 2001.

  • Atencia J., Martínez G., García Rico A., Flórez J., (2000) "Electrical performance analysis of three different types of linear machines", Proceedings of the IASTED International Conference, Power and Energy Systems, Marbella (Spain), September 2000.

ABSTRACT: In this paper we present a Linear prototype Induction Motor (LIM), an iron core armature Permanent Magnet Linear Synchronous Motor (PMLSM), and an ironless armature PMLSM, all of them with the same primary parameters. The electromagnetic properties of these three prototypes are compared, and the thrust and dynamic performance discussed.

  • García Rico A., Atencia J., Martínez G., (2000) "Modelización y simulación de máquinas lineales asíncronas, y síncronas de imanes permanentes", III Conferencia anual Elementos Finitos. Cosmos, Zamudio (Spain), Septiembre 2000.

ABSTRACT: Se demuestra cómo el programa COSMOS/M resulta de gran ayuda en la búsqueda de diseños de máquinas lineales síncronas y asíncronas, facilitando el conseguir correcciones que permiten mejorar, a priori, el comportamiento que acabarán teniendo los prototipos; ahorrándose así multitud de recursos, tanto de tiempo como económicos. Los prototipos diseñados están en funcionamiento como herramienta experimental dentro de un proyecto global a largo plazo que abarcará el diseño, construcción, alimentación, control y análisis del comportamiento electrodinámico de máquinas eléctricas lineales.

  • Atencia J., García Rico A., Flórez J., (2001) "A low cost linear induction motor for laboratory experiments", Int. J. Electr. Eng. Educ. (UK), vol. 38, nº 2, pp. 117-34, April 2001.

ABSTRACT: In this paper we present a Linear Induction Motor (LIM) prototype for education. LIMs allow to easy identification and study of the different concepts and parameters of the electromagnetic circuit that they have in common with any other types of electrical machines. Some experiments are presented that highlight the proposed approach.

  • Atencia J., Martínez-Iturralde M., García Rico A., Flórez J., (2001) "Modeling of linear induction motors as linear drives", Proceedings of the IEEE Porto Powertech Conference, Porto (Portugal), September 2001.

ABSTRACT: There is a large bibliography in simulation models for Linear Induction Motors (LIMs). However, most of them only consider steady state performance. LIMs working as Linear Drives generally operate under transient conditions. The aim of this paper is to investigate the suitability of different mathematical models to simulate LIMs as Linear Drives. An study of most major techniques of calculating lumped parameters is provided. The most representative models capable of simulating transient of LIMs are described and applied to a laboratory prototype. Finally, the results obtained are compared to experimental data.

  • Martínez-Iturralde M., Atencia J., García Rico A., Flórez J., (2001) "Analysis of different models of linear induction drives", Proceedings of the IEEJ LDIA Conference, Nagano (Japan), October 2001. ISBN 84-699-3253-5, pp. 135-139.  Esta publicación mereció el premio a la excelencia por parte de la IJEE, organizadores de la conferencia.

ABSTRACT: Many authors have developed different models to simulate Linear Induction Motors (LIMs). Nonetheless, these models usually only focus on the steady state performance of the machine. The increasing demand for LIMs in industry, working as linear drives, makes it necessary to use models capable of simulating LIMs under transient conditions. The objective of this paper is to draw some conclusions about the suitability of different mathematical models to simulate LIMs as linear drives. Three representative models are described and applied to a laboratory prototype. Finally, the results obtained are compared to experimental data.

  • Atencia J., Martínez G., García Rico A., Flórez J., (2001) "Minimization of cogging force in flat permanent magnet linear motors", Proceedings of the IEEJ LDIA Conference, Nagano (Japan), October 2001. ISBN 84-699-3253-5, pp. 441-444.

ABSTRACT: This paper proposes a technique to reduce cogging force choosing the optimal size of the magnets, and the optimal geometry of the primary iron. The feasibility of the proposed technique is confirmed both by finite element analysis and by the experimental results obtained with laboratory prototypes.

  • Atencia J., "Diseño, Modelización, Construcción y Control de Motor Lineal de Inducción". Tesis Doctoral. San Sebastián. Abril 2002. Codirectores de tesis: Julián Flórez Esnal y Andrés García Rico. Ver resumen.
     

  • Martínez G., Atencia J., García Rico A., Flórez J., (2002) "Electrical performance of two different types of Permanent Magnet Linear Machines with Vector Control", Proceedings of the 17th International Conference on Magnetically Levitated Systems and Linear Drives (MAGLEV2002), Lausanne (Switzerland), September 2002.

ABSTRACT: There is a dilemma about employing or not employing iron in the primary core of synchronous linear actuators. To give some guidance about the convenience of using iron or ironless primary cores, two prototypes of Permanent Magnet Linear Machines (PMLSM) geometrically identical were built. The prototypes were tested in order to get reliable comparative conclusions. The purpose of this paper is to analyse the performance of two different topologies of linear synchronous machines, using vector control techniques. Several tests were performed to determine the electromagnetic properties and the static forces of the prototypes involved. The paper concludes with a discussion of their performances and dynamics, and their suitability for different applications.

  • Martínez G., Atencia J., García Rico A., Flórez J., (2002) "Vector control of Permanent Magnet Linear Synchronous Machines with detent force compensation", Proceedings of the IEE MEDPower 2002 Conference, Athens (Greece) November, 2002.

ABSTRACT: The aim of this paper is the design and analysis of a control algorithm for Permanent Magnet Linear Synchronous Motors (PMLSM) which takes into account the detent force characteristic of this kind of machines. The control algorithm includes a compensator that minimizes the negative effects caused by detent force. This study is part of a more extensive project that seeks the complete cancellation of these forces working simultaneously in two separate fields: the constructive design of the machine and the control system. A very important reduction of detent force with a constructive optimization of the machine has been achieved. The next target is to eliminate the forces completely by a suitable control algorithm. The elimination of detent force will increase the high precision features of these actuators. Rotor Flux Oriented Control (RFOC) strategy was employed. Detent force was measured in a PMLSM prototype, and a control algorithm that minimizes the undesired effects has been designed. Experimental tests were performed to verify the effectiveness of the method. The electrical and dynamic performance of a prototype are compared under two different conditions: firstly including the force compensation in its control algorithm, and secondly without force compensation. The influence of the force compensator alone is analysed in this paper. The following step is to combine the optimized constructive design and the developed control algorithm in order to supress completely the force and speed ripple.

  • Martínez-Iturralde M., Simón I., García Rico A., Flórez J., (2002) "Parameter identification of vector controlled linear induction motor", Proceedings of the IEE MEDPower 2002 Conference, Athens(Greece), November 2002.

ABSTRACT: The special geometry of Linear Induction Motors (LIMs) produces some specific effects (i.e. end effects and asymmetric field distribution) that affect the value of their lumped parameters. Because of this, it is usual to control LIMs by means of scalar control, instead of using the more efficient vector control techniques. The aim of this paper is to test the influence of the LIMs specific effects in the lumped parameters of the machine and, therefore, in their vector control. A parameter identification technique based on the Least Squares method was developed and applied to a LIM prototype under various operating conditions. Moreover, the influence of vector control parameters variation in the LIM performance was evaluated. Rotor Field Oriented Control (RFOC) was applied to a laboratory prototype. Different experimental tests were performed.

  • Atencia J., Martínez-Iturralde M., Martínez G., García Rico A., Flórez J., (2003) "Control strategies for positioning of Linear Induction Motors: tests and discussion", Proceedings of the IEEE IEMDC 2003 Conference, Madison, Wisconsin (USA), June 2003. ISBN 0-7803-7818-0, pp. 1651-1655.

ABSTRACT: The target of this paper is to establish the main problems and goals of the four most popular control strategies for induction motor drives, applied to the special case of Linear Motors: Scalar Control, Direct field-oriented control (direct FOC), indirect Field-oriented Control (indirect FOC) and Direct Torque Control (DTC). We introduce the peculiarities of the implementation of the different strategies for Linear Induction Motors, the results of experimental tests of the speed controller and position controller, and a discussion of the experiments.

  • Martínez G., Atencia J., Martínez-Iturralde M., García Rico A., Flórez J., (2003) "Reduction of detent force in flat Permanent Magnet Linear Synchronous Machines by means of three different methods", Proceedings of the IEEE IEMDC 2003 Conference, Madison, Wisconsin (USA), June 2003. ISBN 0-7803-7818-0, pp. 1105-1110.

ABSTRACT: This paper proposes two different techniques to reduce detent force in flat Permanent Magnet Linear Synchronous Motors (PMLSM). The first one is the choice of an optimal constructive design, taking into account the width and arrangement of the magnets, and the length and shape of the solid iron core. The second is the employ of a force compensator in the control algorithm, which counteracts the detent force effects. Both methods are based on a Fourier analysis of the detent force curve as a function of the machine position. The curve is broken down into harmonics. The constructive method considers that each harmonic has its peculiar source and is independent from the others. The force compensator employs a detent force model based on the Fourier series of the curve. The two methods were tested separately, and their results were compared. Experimental tests were performed to verify the effectiveness of the methods. A very important reduction with a constructive optimization of the machine was achieved. The reduction by means of a compensator in the control scheme also reaches excellent results. In order to achieve the maximum reduction of detent force, both techniques can be combined. This measure will increase the precision features of this kind of machines.

  • Martínez-Iturralde M., Martínez G., Atencia J., García Rico A., Flórez J., (2003) "Analysis of voltage measurement techniques for Direct Torque Control of induction motors", Proceedings of the IEEE IEMDC 2003 Conference, Madison, Wisconsin (USA), June 2003. ISBN 0-7803-7818-0, pp. 1151-1155.

ABSTRACT: The knowledge of the real stator voltages is basic for a correct estimation of stator flux and torque in Direct Torque Controlled induction motors. In this paper, two different low-cost and effective techniques are presented for stator voltage acquisition: one based on an electronic circuit and the other based on software programming. Both of them have been developed and applied to a direct torque control (DTC) scheme. Experimental tests demonstrate their suitability when controlling an induction motor. A comparative of the two mentioned techniques is presented.

  • Martínez-Iturralde M., Martínez G., García Rico A., Flórez J., (2003) "Estrategias de control para accionamientos eléctricos lineales", Sección española de ISA (International Society for Measurement and Control, Instrumentation, and Automation), Ponencia Invitada para sesión especial, Madrid, 17 de Junio de 2003.

RESUMEN: En este artículo se presentan estrategias de control específicas para los dos tipos de motores lineales más comunes en la industria: el motor lineal de inducción (LIM) y el motor lineal síncrono de imanes permanentes (PMLSM).

  • Martínez G., García Rico A., Flórez J., (2003) "Simultaneous position and levitation control of Permanent Magnet Linear Synchronous Machines using vector control techniques", Proceedings of the IEEJ LDIA 2003 Conference, Birmingham (UK), September 2003. ISBN 0-9535228-1-4, pp. 311-315.

ABSTRACT: The aim of this paper is to analyse the normal forces characteristic of flat Permanent Magnet Linear Synchronous Machines (PMLSMs). The results of this study allow to take several conclusions and to develop control strategies able to reach a decoupled control of thrust and attraction / repulsion forces in this kind of linear machines. The control of the normal forces can provide multiple advantages, such as the reduction of friction forces, or even their suppression. The main purposes of this study are to achieve the simultaneous and decoupled control of the thrust and the normal forces in PMLSMs and draw some conclusions.

  • Martínez-Iturralde M., García Rico A., Flórez J., (2003) "Control strategies for linear induction motors", Proceedings of the IEEJ LDIA 2003 Conference, Birmingham (UK), September 2003. ISBN 0-9535228-1-4, pp. 319-323.

ABSTRACT: Rotor Flux Oriented Control (RFOC) of linear induction motors needs complex identification methods to compensate parameter variation during operation, mainly due to local heating and end effects. Direct Torque Control (DTC) based methods for LIMs introduce thrust ripple and have problems at low and zero speed. In this paper, a new control strategy for linear induction motors that makes up for these drawbacks is presented. The new algorithm for normal and full-voltage operation is described. Simulation and experimental results demonstrate the main advantages against RFOC and DTC. The strategy is also applicable to rotary motors.

  • G. Martínez, M. Martínez-Iturralde, A. García Rico, J. Flórez, "Motores lineales en Máquina – Herramienta. Tipología y características electromagnéticas y dinámicas", XV Congreso de Máquinas – Herramienta y Tecnologías de Fabricación, vol. 1, pp. 381 - 400 San Sebastián, 20,21 y 22 de octubre de 2004, I.S.B.N. 931828-7-7.

ABSTRACT: Los accionamientos lineales empleados en máquinas-herramienta basados en husillos a bolas están siendo progresivamente reemplazados por motores eléctricos lineales. Estos motores se pueden clasificar según su principio de funcionamiento (síncronos, asíncronos, paso a paso, de reluctancia, de corriente continua,..) y según su estructura (planos, tubulares...), resultando una gran cantidad de configuraciones electromagnéticas diferentes. Sin embargo, se ha constatado que el abanico de motores lineales más ampliamente utilizados para máquina-herramienta es muy reducido.

Este documento pretende arrojar más luz sobre los diferentes tipos de motores lineales que existen en el mercado y sus sistemas de control. Por un lado se describirán las características fundamentales de cada uno a la hora del diseño de una máquina industrial: fuerza, velocidad, aceleración, precisión, repetibilidad y necesidad de refrigeración. Por otro lado, se comentarán los diferentes problemas electromagnéticos específicos de cada tipo de motor: fuerzas de reluctancia y de atracción, variación de su comportamiento con la velocidad, etc..., que pueden afectar al comportamiento de la máquina industrial, sobre todo a la hora de exigir gran precisión de funcionamiento.

Se aportará información relevante obtenida de publicaciones científicas recientes, catálogos comerciales y, sobre todo, de la experimentación realizada desde hace 6 años en el Laboratorio de Investigación en Máquinas Eléctricas de TECNUN (Universidad de Navarra), donde se han diseñado y construido varios prototipos de motores lineales.

  • Martínez, G., Martínez-Iturralde, M., Castelli, M., García Rico, A., Flórez, J., "Simultaneous motion and normal forces control of Flat Permanent Magnet Linear Synchronous Motors employed as actuators ", Proceedings of the IEEJ LDIA Conference, Kobe-Awaji (Japan), September 2005.

ABSTRACT: This paper analyses the dynamic performance of flat single-sided Permanent Magnet Linear Synchronous Motors (PMLSMs) employed as actuators, when the motion and the attractive or repulsive forces between the primary and the secondary are controlled simultaneously. The control of the normal forces when the motor is in dynamic operation provides multiples advantages, such as the reduction of friction forces and audible noise, and the minimization of mechanical stresses of guides and supports. Two PMLSM prototypes, one with a ferromagnetic primary core, and another with a non-magnetic armature, were tested under these special operation conditions. A modified Rotor Flux Oriented Control (RFOC) strategy was employed to carry out the tests, and several conclusions were taken. The main purposes of this study are to show the feasibility of the simultaneous control of motion and normal forces employing vector control techniques and to analyse the dynamic response of the prototypes.

  • Martínez-Iturralde, M., Martínez, G., Castelli, M., García Rico, A., Flórez, J., "Simple and Robust Indirect Thrust Control for Positioning of Linear Induction Motors ", Proceedings of the IEEJ LDIA Conference, Kobe-Awaji (Japan), September 2005.

ABSTRACT: Dealing with position control of Linear Induction Motors (LIM), most strategies in bibliography are based on Secondary Flux Oriented Control (SFOC) and Direct Thrust Control (DTC). However, SFOC of linear induction motors needs complex identification methods to compensate parameter variation during operation, mainly due to local heating and end-e ects. On the other hand, DTC based methods for LIMs present thrust ripple and have problems at low and zero speeds.

In this paper, a new Indirect Thrust Control (ITC) based strategy for position control of linear induction motors that makes up for these drawbacks is presented. The position control loop design methodology and the method for automatic adjustment of compensators are described. Experimental results are presented to evaluate the performance and sensitivity of the control strategy. Finally, some conclusions are drawn about the applicability of the new algorithm that demonstrate the main advantages versus SFOC and DTC.

  • Castelli, M., Martínez-Iturralde, M., Martínez, G., García Rico, A., Flórez, J., "Design, Construction and Control of a High Performance XY Positioner ", Proceedings of the IEEJ LDIA Conference, Kobe-Awaji (Japan), September 2005.

ABSTRACT: Linear motors offer several advantages over their rotary counterparts in many industrial applications requiring linear motion and positioning accuracy (1); linear motors can achieve a higher value of the position loop gain, and thus higher accelerations and speeds, due to the elimination of mechanical transmission devices. However, dealing with precision machinery, it is not possible to make simple replacement of conventional systems to linear servomotors. Mechanical vibration, thermal expansion, regenerative energy dissipation or electromagnetic compatibility are only a few problems that could appear if not taken into account through the design process of the precision machine. Interesting conclusions are drawn form the project realized, as the fact of being able to use only one linear scale to control two motors in one axis, or need of using external regenerative resistors.

  • Castelli, M., Martínez-Iturralde, M., Martínez, G., García Rico, A., Flórez, J., "Linear Induction Motor Control for Simultaneous Propulsion and Levitation of an Aluminium Plate ", Proceedings of the IEEJ LDIA Conference, Kobe-Awaji (Japan), September 2005. 

ABSTRACT: This paper presents interesting results about the aplication of an innovative control strategy of an aluminium plate, using both levitation and horizontal movements. Construction simplicity and economy are among some of its main advantages, since it only uses one AC source. Another feature is the utilization of the same algorithm to control both movements, propulsion and levitation. The aluminium plate has a vectorial, primary flux oriented control. The algorithm for propulsion and levitation described in this article was based in a new LIM control strategy developed in TECNUN(1). Also simulation and experimental results are presented in order to validate the new control strategy. Finally some conclusions are drawn about the advantages of the new control method and future works are presented.

 
 

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