357 research outputs found
Flux switching alternators for small wind generation
This paper considers the application of flux
switching alternators for small wind generation. First, after a
brief presentation of the small wind energy systems, a description
and the fundamentals of flux switching machines is given, then
the state of art of flux switching generators is presented. Finally
a critical assessment is shown, considering the main advantages
and drawbacks of this type of machines as alternator for use in
small wind generation systems.Peer ReviewedPostprint (published version
Design of a segmented switched reluctance drive for a light electric vehicle
The light electric vehicle market requires better performance motors with less or even without permanent magnets. Switched reluctance motors (SRM) are among the best placed to meet this goal, despite they have lower power density, higher torque ripple, and are noisier than synchronous permanent magnet motors. Segmented stator switched reluctance motors (SSSRM) can reduce these drawbacks of conventional SRMs due to their modular construction and shorter flux paths. This paper presents a procedure for designing an SSSRM for a light electric vehicle. First, the output torque equation is derived from a simplified nonlinear energy conversion loop, and then guidelines for its design are given. Once the preliminary sizing of the SSSRM has been carried out, simulation using electromagnetic finite element analysis is performed. Then, the complete drive is simulated and validated using Matlab-Simulink and some results of the definitive finite element analysis (magnetization curves and static torque curves).Peer ReviewedPostprint (published version
Magnetic circuit znalysis of a linear switched reluctance motor
In this paper a magnetic circuit analysis has been developed to obtain flux linkage/current
characteristics in aligned and unaligned positions for a Linear Switched Reluctance Motor. The model
is based on lumped parameters and it takes into account the leakage pole flux and the end effects. The
lumped parameter magnetic analysis proposed can be a useful tool for designing Linear Switched
Reluctance Machines. The procedure has been verified using two dimensional finite element analysis
and experimental measurements.Postprint (published version
Solar photovoltaic water pumping system using a new linear actuator
In this paper a photovoltaic solar pumping system using a new linear actuator is presented. This linear actuator is a
double-sided flat two-phase variable-reluctance linear stepper motor that moves a piston-type water pump with the help of a
rope, a pulley and a counterweight. The entire actuator pump ensemble is controlled by a simple electronic unit that manages
the electric power generated by a photovoltaic array. The proposed system is suitable for rural communities in developing
countries because it is reliable, affordable and easy to maintain.Postprint (published version
Study of end effects on the performance of the linear switched reluctance motor
The purpose of this paper is to study the end
effects in a double-sided linear switched reluctance motor
(LSRM). Switched reluctance motors (SRM) and by extension
their linear counterpart, LSRM, have been widely studied using
two-dimensional finite element analysis (2D FEA). End effects
are not included in 2D FEA, even though these effects
considerably increase unaligned inductance. This paper
describes a procedure that takes into account the end effects in
flux linkage, inductance and force profiles on LSRM. It is based
on 2D FEA corrected by the inclusion of end-winding
inductance and several empirical coefficients. The results of
this approach closely coincide with experimental
measurements.Postprint (published version
High-speed synchronous generators. A critical assessment
Considering that there are electromagnetic, mechanical and thermal constraints that determine the design of high-speed electrical machines, the criteria that lead to adequate selection of the machine are established in this work. Moreover, taking into account the current state of technology, the critical values in the ratio (output power)/(rotation speed), are presented. The paper focuses on the high-speed synchronous generators, especially in permanent magnet generators, inductor alternators and flux switching alternators, emphasizing their constructive fundamentals and their advantages and disadvantages. The analysis is completed with a critical assessment that classifies them according to previously defined requirements. Although the decision of the final choice is largely determined by the application of interest, it can be said that, in general, synchronous generators with permanent magnets in the rotor are the best option.Postprint (published version
Dos reflexiones sobre la actual enseñanza del Derecho
En la actualidad estamos asistiendo a un proceso de profundas reformas dentro de las enseñanzas universitarias, que alcanzan también a los estudios jurídicos. En este trabajo dúplice se presentan dos visiones personales sobre la reforma de tales estudios, realizados por profesionales de la Historia del Derecho, en Portugal y en México.These days we are attending a process of deep reforms within the university studies, that reach also the legal scholarship. Two personal visions and footpaths on the reform of such studies, realised by professionals of the History of Law, in Portugal and Mexico, are presented in this double work.Actuellement nous assistons à un processus de réformes profondes dans les enseignements universitaires, qui atteignent aussi aux études juridiques. Dans ce double travail on présente deux démarches et visions personnelles sur la réforme de telles études, effectués par des professionnels de l’Histoire du Droit, au Portugal et au Mexique. En alemán: Innerhalb des Lehrbetriebs an den Universitäten beobachten wir gegenwärtig einen Prozess tief greifender Reformen, die auch das Jurastudium erfassen. In dieser auf Gegenerwiderung angelegten Arbeit werden Pfade persönlicher Sichtweisen zu den Reformen dieser von Experten der Rechtsgeschichte in Portugal und Mexiko erstellten Studien vorgestellt
A device for improving the immunity of AC contactor during voltage dips
This paper describes an electronic device that enables AC contactors to ride through power quality dsturbances. The proposed device is connected to the contactor
coil and consists of a power conversion excitation and hold-in crcuit, a control circuit, an immunity circuit and a shutdown
circuit. It does not disturb contactor operation, is easy to use nd can be built from cheap, commercially available
components. Experimental tests have demonstrated the efectiveness of the proposed electronic device for improving
the immunity of AC contactors during power quality disturbances, particularly voltage dips.Postprint (published version
Minimization of torque ripple in switched reluctance motor drives using direct instantaneous torque
Torque ripple is an inherent characteristic of switched reluctance motor drives due to its double salient geometry and it is a serious drawback in applications that require
smooth torque and high dynamic performances. This paper presents some contributions to the minimization of torque ripple
in SRM using direct instantaneous torque control (DITC). Direct torque controller is simulated using Matlab/Simulink and then
implemented in a DSPACE ACE kit 1006 CLP that includes a processor board with an AMD OpteronTM running at 2.6 GHz.
Finally, experimental results are shown and they are compared with those obtained using conventional angle control.Postprint (published version
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