Richard Magdalena Stephan - Academia.edu (original) (raw)

Papers by Richard Magdalena Stephan

2023 14th International Symposium on Linear Drivers for Industry Applications (LDIA)

One main point in designing small permanent magnet DC motors is to determine the operation point ... more One main point in designing small permanent magnet DC motors is to determine the operation point of the permanent magnet. This is done by a modern finite element analysis or the intersection of the linearized model of demagnetization curve with operation line, which characterizes the magnet stressing in a general case. In the latter method iron saturations are mostly neglected, but especially for small motors this simplification is no longer valid. So we present a fast method to determine the operation point of a permanent magnet with respect to iron saturation using the nonlinear iron characteristic of its permeability. Based on this approach we give an example for an already designed motor for a heart assist device and compare these results with results using a finite element analysis.

Superconductor Science and Technology, 2016

This paper describes the design and experimental test of a passive magnetic bearing system compos... more This paper describes the design and experimental test of a passive magnetic bearing system composed by a Superconductor Magnetic Bearing (SMB) and a Permanent Magnet Bearing (PMB). This bearing setup is part of a flywheel energy storage system. The advantage of using a passive bearing system is that it offers low friction without the need of a magnetic bearing controller, increasing the reliability and decreasing the energy consumption. The first set of tests were quasi-static radial and axial force measurements of the PMB operating alone and together with the SMB. As the PMB is intrinsically unstable in one degree of freedom, the operation of the SMB together with the PMB is necessary to stabilize the system. After that, dynamic measurements were made for the SMB operating alone and together with the PMB. The resonant speeds were identified and the bearing radial and axial forces were also measured for the SMB and SMB + PMB operation. These results indicate that the studied bearing set is technologically feasible to be used in flywheel energy storage systems.

IFAC Proceedings Volumes, 1987

A new approach to the armature current control of a thyristor driven DC-motor, based on robust po... more A new approach to the armature current control of a thyristor driven DC-motor, based on robust pole-placement concepts, is proposed_ The principal difficulty in this control problem arises due to the two different conduction modes of the current. As long as the current is continuous the armature may be modelled practica l ly as a first order system, but as the current becomes discontinuous it exhibits nonlinear gain behaviour. These plant variations are classicaly compensated with a dual-mode adaptive current controller. It will be shown that the proposed scheme can substitute with success the old one. Moreover, because the robust controller has fixed structure and coefficients, independently of the current operation mode , its realization is simpler than that of a dual-mode adaptive controller. Simulation as well as experimental results are presented. Keywords. Robust control, DC-motor current control, control of time-variant systems, comparison o f robust and adaptive schemes.

IEEE Transactions on Applied Superconductivity, 2016

The Brazilian project MagLev-Cobra proposes a superconducting levitation vehicle for urban transp... more The Brazilian project MagLev-Cobra proposes a superconducting levitation vehicle for urban transportation in highly populated cities. The levitation technology is based on the diamagnetic behavior and flux pinning property of Y-Ba-Cu-O blocks in the proximity of the magnetic field of Nd-Fe-B magnets. The traction is given by a short primary linear induction motor. In previous editions of EUCAS conference, laboratory tests were presented to validate the levitation method and vehicle design. In this paper, recent operational results of the MagLev-Cobra traveling along an outdoor 200-m test facility constructed in the university campus will be reported. The full-scale vehicle is composed of four modules, interconnected by mechanical links. The transportation capacity is equivalent to 5 passengers/m2, a limit of transportation comfort and quality. Acceleration, braking, and also cruising speed conditions were analyzed. A data acquisition system monitored the levitation gap and other parameters along the track. This effort is an important step to certificate the operational safety, an indispensable condition before industrialization and commercialization.

38th Midwest Symposium on Circuits and Systems. Proceedings

... A simulation problem here is to model the TCR control. Some models, as the one described in [... more ... A simulation problem here is to model the TCR control. Some models, as the one described in [5], use the actual control system hardware. ... Page 4. References [1] Oliveira, GS G "Simulation of TCR for Transient Studies" - Comparison Between Digital and Analog Model, M.Sc. ...

Physics Procedia, 2012

The unique properties of high critical temperature superconductors (HTS) make possible the develo... more The unique properties of high critical temperature superconductors (HTS) make possible the development of an effective and self-stable magnetic levitation (MagLev) transportation system. In this context, a full scale MagLev vehicle, named MagLev-Cobra, has been developed at the Laboratory for Applied Superconductivity (LASUP/UFRJ). The vehicle is borne by a linear superconducting magnetic bearing (LSMB). The most important design constraint of the levitation system is the force that appears due to the interaction between the HTS and the permanent magnetic (PM) rail, which composes the LSMB. Static and dynamic characteristics of this force must be studied. The static behavior was already reported in previous work. The dynamic operation of this kind of vehicle, which considers the entry and exit of passengers and vibration movements, may result in the decrease of the gap between the superconductor and the PM rail in LSMB. In order to emulate the vehicle operation and to study the gap variation with time, the superconductors are submitted to a series of vertical displacements performed with the help of an experimental test rig. These movements are controlled by a time-variant reference force that reproduces the vehicle dynamic. In the present work, the results obtained for the dynamic gap behavior are presented. These measurements are essential to the commissioning process of a superconducting MagLev full scale vehicle.

Proceedings of IEEE International Symposium on Industrial Electronics

Pumping crude oil from wells on deep ocean waters is a challenge that the oil industry is facing.... more Pumping crude oil from wells on deep ocean waters is a challenge that the oil industry is facing. To achieve this goal, a better assessment of the electrical and mechanical parts involved in the process is needed. This paper analyses the behaviour of a special type of induction motor, the ESP (electrical submersible pump) motor, when supplied by an inverter

Physica C: Superconductivity, 2000

A superconducting/electromagnetic hybrid bearing system is currently under development and test. ... more A superconducting/electromagnetic hybrid bearing system is currently under development and test. This system consists of a thrust superconducting magnetic bearing and a double radial active electromagnetic bearing/motor devices. The thrust bearing has been designed using NdFeB permanent magnets levitating on a set of superconducting monoliths of YBCO, prepared by top seeded melt texturing technique, which supports the weight of the rotor. The bearing/motor devices were conceived as 4-pole 2-phase induction machine using stator windings for delivering torque and radial positioning simultaneously. Using this superconducting axial bearing and the active bearings for the rotor radial positioning, a fully levitating vertical-shaft inductive machine has been tested. The tests were successful in reaching a controlled levitation up to 6,300 rpm.

Journal of Physics: Conference Series, 2014

ABSTRACT The superconducting MagLev technology for transportation systems is becoming mature due ... more ABSTRACT The superconducting MagLev technology for transportation systems is becoming mature due to the research and developing effort of recent years. The Brazilian project, named MagLev-Cobra, started in 1998. It has the goal of developing a superconducting levitation vehicle for urban areas. The adopted levitation technology is based on the diamagnetic and the flux pinning properties of YBa2Cu3O7−δ (YBCO) bulk blocks in the interaction with Nd-Fe-B permanent magnets. A laboratory test facility with permanent magnet guideway, linear induction motor and one vehicle module is been built to investigate its operation. The MagLev-Cobra project state of the art is presented in the present paper, describing some construction details of the new test line with 200 m.

Journal of Physics: Conference Series, 2010

A Brazilian real scale magnetically levitated transport system prototype is under development at ... more A Brazilian real scale magnetically levitated transport system prototype is under development at the Federal University of Rio de Janeiro. To test this system a 180 m long line has been projected and it will be concluded by the end of 2010. A superconducting linear bearing (SLB) is used to replace the wheels of a conventional train. High temperature superconductor bulks placed inside cryostats attached to the vehicle and a magnetic rail composes the SLB. To choose the magnetic rail for the test line three different rails, selected in a previous simulation work, were built and tested. They are composed by Nd-Fe-B and steel, arranged in a flux concentrator topology. The magnetic flux density for those magnetic rails was mapped. Also, the levitation force between those rails and the superconductor cryostat, for several cooling gaps, were measured to select the best rail geometry to be used in the real scale line. The SLB allows building a light vehicle with distributed load, silent and high energy efficient. The proposed vehicle is composed of four modules with just 1.5 m of length each one and it can transport up to 24 passengers. The test line having two curves with 45 m radius and a 15% acclivity ramp is also presented.

IEEE Transactions on Magnetics, 2000

ABSTRACT A frictionless electromagnetic-superconducting hybrid bearing for induction machine has ... more ABSTRACT A frictionless electromagnetic-superconducting hybrid bearing for induction machine has been designed and is currently in development and tests. The vertical and radial stiffnesses have been investigated by dynamic method for different air gaps of the axial superconducting bearing. The measured low value of the radial elastic constant appeared to be responsible for the instability of the rotating shaft. That instability has been controlled using double motor-bearing devices assembled on the same shaft. This fully frictionless system reached a spinning speed of 6300 RPM

IEEE Transactions on Industrial Electronics, 1994

The induction motor (IM) is a high-efficiency machine when working close to its rated operating p... more The induction motor (IM) is a high-efficiency machine when working close to its rated operating point. However, at torques and/or speeds far from the rated values the efficiency is greatly reduced. In this work a new approach is proposed that minimizes the total copper and iron losses in a variable speed andor torque IM drive, while keeping a good dynamic response. This method is based on a simple IM model that includes iron losses. The model, which only requires the knowledge of conventional IM parameters, is referred to a field-oriented frame. Using this model, the IM losses are quantified and an algorithm, based on a field-oriented scheme, is deduced. Simulation and experimental results are presented to validate the proposed method.

IEEE Transactions on Applied Superconductivity, 2013

In a superconducting magnetically levitated vehicle, the conventional wheel-rail system is substi... more In a superconducting magnetically levitated vehicle, the conventional wheel-rail system is substituted by a permanent magnet guideway (PMG) made with Nd-Fe-B magnets and carbon-steel interacting with bulk superconductors installed in the vehicle to promote the levitation. The main cost of this levitation system is the PMG. Two geometries that minimizes the total cost, for a given static levitation force (LF min), are dynamically investigated and compared in this paper. Impulse response on time and frequency domains, stiffness, damping, and oscillation frequency are presented for different conditions. The experimental apparatus is also described.

IEEE Transactions on Applied Superconductivity, 2013

ABSTRACT Based on the magnetic characteristics of HTS superconductors, the group of the Laborator... more ABSTRACT Based on the magnetic characteristics of HTS superconductors, the group of the Laboratory of Applied Superconductivity from COPPE/UFRJ in Brazil has proposed and developed a full-scale superconducting MagLev vehicle. The levitation system of this vehicle consists of a superconducting magnetic linear bearing, which is composed of a permanent magnetic guideway (PMG) and YBCO bulks superconductors. The levitation and guidance forces that appear due to the interaction between the superconductor and the PMG keep the vehicle passively levitating in a stable equilibrium point. However, under operational conditions, which include the entry and exit of passengers, vibrations and curves performed by the vehicle, this equilibrium point may be changed. One of the critical consequences caused by this change is the reduction in the levitation gap of the superconductor in relation to the PMG. In order to emulate the vehicle operation, the superconducting bearing is submitted to a series of vertical and horizontal displacements around the equilibrium point and the levitation gap and guidance position are monitored. These movements are controlled by time-variant reference forces that reproduce the operational conditions and the behavior for the levitation gap and guidance position are shown. These measurements are essential to the development process of a full-scale superconducting MagLev vehicle.

IEEE Transactions on Applied Superconductivity, 2013

ABSTRACT Approximately a decade ago, superconducting maglev train prototypes started to be develo... more ABSTRACT Approximately a decade ago, superconducting maglev train prototypes started to be developed. Researchers from China, Germany, and Brazil have built prototypes carrying people based on superconducting levitation technology. The Brazilian MagLev project, named MagLev-Cobra, started in 2000 with a small-scale prototype that was concluded in 2006. After that, efforts toward a full-scale test vehicle for 30 passengers began. This vehicle will be composed of 4 modules, each one 1.5 m long, with six levitation cryostats and a linear induction motor. The first module and 12 m of test track are already constructed and this paper will describe the following tests: air gap as a function of load, temporal air gap stability, linear motor traction force, and vehicle acceleration. The paper will also describe the construction details of module, linear motor, and the rail.

International Journal of Electrical Engineering Education, 2011

The objective of this paper is to present a didactic approach to the calculation of forces genera... more The objective of this paper is to present a didactic approach to the calculation of forces generated on permanent magnets, ferromagnetic and diamagnetic materials, superconductors and conductors. A phenomenological view is applied to simplify the understanding needed in undergraduate courses of electromagnetic theory and electric energy conversion. Simple mathematical relations and experiments support the basic concepts.

IEEE Transactions on Appiled Superconductivity, 1999

... 970, Brazil. E-mail: nicolsky@if.ufrJ.br D. FB David, A. Santisteban, R M. Stephan, A. Ripper... more ... 970, Brazil. E-mail: nicolsky@if.ufrJ.br D. FB David, A. Santisteban, R M. Stephan, A. Ripper, and R. de Andrade Jr. EE/COPPE , Universidade Federal do Rio de Janeiro, Cx. P. 68515, Rio de Janeiro 21945-970, Brazil W. Gawalek ...

This work analyses via simulation and experimental results the impact on the motor terminal volta... more This work analyses via simulation and experimental results the impact on the motor terminal voltage of inverter-fed industrial drives. After the validation of the modeling some overvoltage mitigation techniques are implemented and evaluated. In several industrial plants the cable connecting the converter and the machine may have a length of some hundreds of meters. While for conventional steady-state studies a

2023 14th International Symposium on Linear Drivers for Industry Applications (LDIA)

One main point in designing small permanent magnet DC motors is to determine the operation point ... more One main point in designing small permanent magnet DC motors is to determine the operation point of the permanent magnet. This is done by a modern finite element analysis or the intersection of the linearized model of demagnetization curve with operation line, which characterizes the magnet stressing in a general case. In the latter method iron saturations are mostly neglected, but especially for small motors this simplification is no longer valid. So we present a fast method to determine the operation point of a permanent magnet with respect to iron saturation using the nonlinear iron characteristic of its permeability. Based on this approach we give an example for an already designed motor for a heart assist device and compare these results with results using a finite element analysis.

Superconductor Science and Technology, 2016

This paper describes the design and experimental test of a passive magnetic bearing system compos... more This paper describes the design and experimental test of a passive magnetic bearing system composed by a Superconductor Magnetic Bearing (SMB) and a Permanent Magnet Bearing (PMB). This bearing setup is part of a flywheel energy storage system. The advantage of using a passive bearing system is that it offers low friction without the need of a magnetic bearing controller, increasing the reliability and decreasing the energy consumption. The first set of tests were quasi-static radial and axial force measurements of the PMB operating alone and together with the SMB. As the PMB is intrinsically unstable in one degree of freedom, the operation of the SMB together with the PMB is necessary to stabilize the system. After that, dynamic measurements were made for the SMB operating alone and together with the PMB. The resonant speeds were identified and the bearing radial and axial forces were also measured for the SMB and SMB + PMB operation. These results indicate that the studied bearing set is technologically feasible to be used in flywheel energy storage systems.

IFAC Proceedings Volumes, 1987

A new approach to the armature current control of a thyristor driven DC-motor, based on robust po... more A new approach to the armature current control of a thyristor driven DC-motor, based on robust pole-placement concepts, is proposed_ The principal difficulty in this control problem arises due to the two different conduction modes of the current. As long as the current is continuous the armature may be modelled practica l ly as a first order system, but as the current becomes discontinuous it exhibits nonlinear gain behaviour. These plant variations are classicaly compensated with a dual-mode adaptive current controller. It will be shown that the proposed scheme can substitute with success the old one. Moreover, because the robust controller has fixed structure and coefficients, independently of the current operation mode , its realization is simpler than that of a dual-mode adaptive controller. Simulation as well as experimental results are presented. Keywords. Robust control, DC-motor current control, control of time-variant systems, comparison o f robust and adaptive schemes.

IEEE Transactions on Applied Superconductivity, 2016

The Brazilian project MagLev-Cobra proposes a superconducting levitation vehicle for urban transp... more The Brazilian project MagLev-Cobra proposes a superconducting levitation vehicle for urban transportation in highly populated cities. The levitation technology is based on the diamagnetic behavior and flux pinning property of Y-Ba-Cu-O blocks in the proximity of the magnetic field of Nd-Fe-B magnets. The traction is given by a short primary linear induction motor. In previous editions of EUCAS conference, laboratory tests were presented to validate the levitation method and vehicle design. In this paper, recent operational results of the MagLev-Cobra traveling along an outdoor 200-m test facility constructed in the university campus will be reported. The full-scale vehicle is composed of four modules, interconnected by mechanical links. The transportation capacity is equivalent to 5 passengers/m2, a limit of transportation comfort and quality. Acceleration, braking, and also cruising speed conditions were analyzed. A data acquisition system monitored the levitation gap and other parameters along the track. This effort is an important step to certificate the operational safety, an indispensable condition before industrialization and commercialization.

38th Midwest Symposium on Circuits and Systems. Proceedings

... A simulation problem here is to model the TCR control. Some models, as the one described in [... more ... A simulation problem here is to model the TCR control. Some models, as the one described in [5], use the actual control system hardware. ... Page 4. References [1] Oliveira, GS G "Simulation of TCR for Transient Studies" - Comparison Between Digital and Analog Model, M.Sc. ...

Physics Procedia, 2012

The unique properties of high critical temperature superconductors (HTS) make possible the develo... more The unique properties of high critical temperature superconductors (HTS) make possible the development of an effective and self-stable magnetic levitation (MagLev) transportation system. In this context, a full scale MagLev vehicle, named MagLev-Cobra, has been developed at the Laboratory for Applied Superconductivity (LASUP/UFRJ). The vehicle is borne by a linear superconducting magnetic bearing (LSMB). The most important design constraint of the levitation system is the force that appears due to the interaction between the HTS and the permanent magnetic (PM) rail, which composes the LSMB. Static and dynamic characteristics of this force must be studied. The static behavior was already reported in previous work. The dynamic operation of this kind of vehicle, which considers the entry and exit of passengers and vibration movements, may result in the decrease of the gap between the superconductor and the PM rail in LSMB. In order to emulate the vehicle operation and to study the gap variation with time, the superconductors are submitted to a series of vertical displacements performed with the help of an experimental test rig. These movements are controlled by a time-variant reference force that reproduces the vehicle dynamic. In the present work, the results obtained for the dynamic gap behavior are presented. These measurements are essential to the commissioning process of a superconducting MagLev full scale vehicle.

Proceedings of IEEE International Symposium on Industrial Electronics

Pumping crude oil from wells on deep ocean waters is a challenge that the oil industry is facing.... more Pumping crude oil from wells on deep ocean waters is a challenge that the oil industry is facing. To achieve this goal, a better assessment of the electrical and mechanical parts involved in the process is needed. This paper analyses the behaviour of a special type of induction motor, the ESP (electrical submersible pump) motor, when supplied by an inverter

Physica C: Superconductivity, 2000

A superconducting/electromagnetic hybrid bearing system is currently under development and test. ... more A superconducting/electromagnetic hybrid bearing system is currently under development and test. This system consists of a thrust superconducting magnetic bearing and a double radial active electromagnetic bearing/motor devices. The thrust bearing has been designed using NdFeB permanent magnets levitating on a set of superconducting monoliths of YBCO, prepared by top seeded melt texturing technique, which supports the weight of the rotor. The bearing/motor devices were conceived as 4-pole 2-phase induction machine using stator windings for delivering torque and radial positioning simultaneously. Using this superconducting axial bearing and the active bearings for the rotor radial positioning, a fully levitating vertical-shaft inductive machine has been tested. The tests were successful in reaching a controlled levitation up to 6,300 rpm.

Journal of Physics: Conference Series, 2014

ABSTRACT The superconducting MagLev technology for transportation systems is becoming mature due ... more ABSTRACT The superconducting MagLev technology for transportation systems is becoming mature due to the research and developing effort of recent years. The Brazilian project, named MagLev-Cobra, started in 1998. It has the goal of developing a superconducting levitation vehicle for urban areas. The adopted levitation technology is based on the diamagnetic and the flux pinning properties of YBa2Cu3O7−δ (YBCO) bulk blocks in the interaction with Nd-Fe-B permanent magnets. A laboratory test facility with permanent magnet guideway, linear induction motor and one vehicle module is been built to investigate its operation. The MagLev-Cobra project state of the art is presented in the present paper, describing some construction details of the new test line with 200 m.

Journal of Physics: Conference Series, 2010

A Brazilian real scale magnetically levitated transport system prototype is under development at ... more A Brazilian real scale magnetically levitated transport system prototype is under development at the Federal University of Rio de Janeiro. To test this system a 180 m long line has been projected and it will be concluded by the end of 2010. A superconducting linear bearing (SLB) is used to replace the wheels of a conventional train. High temperature superconductor bulks placed inside cryostats attached to the vehicle and a magnetic rail composes the SLB. To choose the magnetic rail for the test line three different rails, selected in a previous simulation work, were built and tested. They are composed by Nd-Fe-B and steel, arranged in a flux concentrator topology. The magnetic flux density for those magnetic rails was mapped. Also, the levitation force between those rails and the superconductor cryostat, for several cooling gaps, were measured to select the best rail geometry to be used in the real scale line. The SLB allows building a light vehicle with distributed load, silent and high energy efficient. The proposed vehicle is composed of four modules with just 1.5 m of length each one and it can transport up to 24 passengers. The test line having two curves with 45 m radius and a 15% acclivity ramp is also presented.

IEEE Transactions on Magnetics, 2000

ABSTRACT A frictionless electromagnetic-superconducting hybrid bearing for induction machine has ... more ABSTRACT A frictionless electromagnetic-superconducting hybrid bearing for induction machine has been designed and is currently in development and tests. The vertical and radial stiffnesses have been investigated by dynamic method for different air gaps of the axial superconducting bearing. The measured low value of the radial elastic constant appeared to be responsible for the instability of the rotating shaft. That instability has been controlled using double motor-bearing devices assembled on the same shaft. This fully frictionless system reached a spinning speed of 6300 RPM

IEEE Transactions on Industrial Electronics, 1994

The induction motor (IM) is a high-efficiency machine when working close to its rated operating p... more The induction motor (IM) is a high-efficiency machine when working close to its rated operating point. However, at torques and/or speeds far from the rated values the efficiency is greatly reduced. In this work a new approach is proposed that minimizes the total copper and iron losses in a variable speed andor torque IM drive, while keeping a good dynamic response. This method is based on a simple IM model that includes iron losses. The model, which only requires the knowledge of conventional IM parameters, is referred to a field-oriented frame. Using this model, the IM losses are quantified and an algorithm, based on a field-oriented scheme, is deduced. Simulation and experimental results are presented to validate the proposed method.

IEEE Transactions on Applied Superconductivity, 2013

In a superconducting magnetically levitated vehicle, the conventional wheel-rail system is substi... more In a superconducting magnetically levitated vehicle, the conventional wheel-rail system is substituted by a permanent magnet guideway (PMG) made with Nd-Fe-B magnets and carbon-steel interacting with bulk superconductors installed in the vehicle to promote the levitation. The main cost of this levitation system is the PMG. Two geometries that minimizes the total cost, for a given static levitation force (LF min), are dynamically investigated and compared in this paper. Impulse response on time and frequency domains, stiffness, damping, and oscillation frequency are presented for different conditions. The experimental apparatus is also described.

IEEE Transactions on Applied Superconductivity, 2013

ABSTRACT Based on the magnetic characteristics of HTS superconductors, the group of the Laborator... more ABSTRACT Based on the magnetic characteristics of HTS superconductors, the group of the Laboratory of Applied Superconductivity from COPPE/UFRJ in Brazil has proposed and developed a full-scale superconducting MagLev vehicle. The levitation system of this vehicle consists of a superconducting magnetic linear bearing, which is composed of a permanent magnetic guideway (PMG) and YBCO bulks superconductors. The levitation and guidance forces that appear due to the interaction between the superconductor and the PMG keep the vehicle passively levitating in a stable equilibrium point. However, under operational conditions, which include the entry and exit of passengers, vibrations and curves performed by the vehicle, this equilibrium point may be changed. One of the critical consequences caused by this change is the reduction in the levitation gap of the superconductor in relation to the PMG. In order to emulate the vehicle operation, the superconducting bearing is submitted to a series of vertical and horizontal displacements around the equilibrium point and the levitation gap and guidance position are monitored. These movements are controlled by time-variant reference forces that reproduce the operational conditions and the behavior for the levitation gap and guidance position are shown. These measurements are essential to the development process of a full-scale superconducting MagLev vehicle.

IEEE Transactions on Applied Superconductivity, 2013

ABSTRACT Approximately a decade ago, superconducting maglev train prototypes started to be develo... more ABSTRACT Approximately a decade ago, superconducting maglev train prototypes started to be developed. Researchers from China, Germany, and Brazil have built prototypes carrying people based on superconducting levitation technology. The Brazilian MagLev project, named MagLev-Cobra, started in 2000 with a small-scale prototype that was concluded in 2006. After that, efforts toward a full-scale test vehicle for 30 passengers began. This vehicle will be composed of 4 modules, each one 1.5 m long, with six levitation cryostats and a linear induction motor. The first module and 12 m of test track are already constructed and this paper will describe the following tests: air gap as a function of load, temporal air gap stability, linear motor traction force, and vehicle acceleration. The paper will also describe the construction details of module, linear motor, and the rail.

International Journal of Electrical Engineering Education, 2011

The objective of this paper is to present a didactic approach to the calculation of forces genera... more The objective of this paper is to present a didactic approach to the calculation of forces generated on permanent magnets, ferromagnetic and diamagnetic materials, superconductors and conductors. A phenomenological view is applied to simplify the understanding needed in undergraduate courses of electromagnetic theory and electric energy conversion. Simple mathematical relations and experiments support the basic concepts.

IEEE Transactions on Appiled Superconductivity, 1999

... 970, Brazil. E-mail: nicolsky@if.ufrJ.br D. FB David, A. Santisteban, R M. Stephan, A. Ripper... more ... 970, Brazil. E-mail: nicolsky@if.ufrJ.br D. FB David, A. Santisteban, R M. Stephan, A. Ripper, and R. de Andrade Jr. EE/COPPE , Universidade Federal do Rio de Janeiro, Cx. P. 68515, Rio de Janeiro 21945-970, Brazil W. Gawalek ...

This work analyses via simulation and experimental results the impact on the motor terminal volta... more This work analyses via simulation and experimental results the impact on the motor terminal voltage of inverter-fed industrial drives. After the validation of the modeling some overvoltage mitigation techniques are implemented and evaluated. In several industrial plants the cable connecting the converter and the machine may have a length of some hundreds of meters. While for conventional steady-state studies a