Francisco Jose Pérez-Cebolla

Design, Characterization, and Validation of a 1-kW AC Self-Excited Switched Reluctance Generator

The switched reluctance machine (SRM) has certain advantages such as robustness and the absence of permanent magnets which have encouraged its use in recent years. One of its applications is as a self-excited generator. This behavior is produced when a capacitor is series or parallel connected to each single phase forming a nonlinear pseudoresonant circuit. This application can be used in isolated sites with a wind turbine for energy generation. This paper describes a novel method used for the specific design of a 1-kW self-excited SRM for wind power applications based on torque considerations. The machine volume, dimensions, finite-element analysis, model verification, simulations, and experimental results are all presented.

3D FEM characterization of a switched reluctance motor from direct experimental determination of the material magnetization curve

Analytical characterization of a switched reluctance motor (SRM) by means of magnetic circuit theory can be a tedious task. Specific software based on the finite elements method (FEM) for solving non linear magneto-static problems has proved very useful for this characterization. However, to solve the Maxwell equations it is necessary first to know the magnetization curve of the material used for building the motor, which may not be available in the program materials library. A simple and low cost method for a direct determination of the first magnetization curve of a magnetic material is presented in this communication. Through one single test of short duration, (which allows to reach high values of the magnetic field strength while keeping the material temperature practically constant), we obtain a B-H curve that fits correctly to the samples obtained by a traditional method requiring the identification of multiple hysteresis loops. This B-H curve has been included in a FEM program to determine the flux linkage-current-position characteristic of a SRM prototype. The results again fit those obtained experimentally, confirming the validity of the proposed method.

Nonlinear Lumped-Circuit Model for Switched Reluctance Motors Exhibiting Core Losses

A new nonlinear lumped parameter model is proposed for a switched reluctance motor (SRM) with core losses. The components of the model and their origin are justified by finite-element simulations and experimental tests. The winding resistance and the leakage inductance are analyzed by different methods taken from the literature, and a new algorithm is proposed to overcome their shortcomings such as the nonbiunivocal flux linkage versus current relationship. In contrast to previous works, the nonlinear elements for modeling the magnetic core, such as the incremental magnetizing inductance and the core-loss resistance, are determined together and simultaneously for each value of the phase current and the rotor position. The performance of the new model and the methodology proposed for estimating its components are analyzed for different excitation types and rotor positions. The core losses are evaluated by the proposed model and by two well-known predictive models, and the results are compared to illustrate the suitability of the former. Finally, the dynamic behavior of the model, acting as an ac self-excited generator, is considered.

Influence of excitation in the experimental equivalent circuit parameters identification of a switched reluctance motor

This paper analyzes the influence of excitation in the experimental determination of flux linkage vs. current vs. position relationship of a switched reluctance motor. Results of the experimental characterization of the SRM in the cases of rectangular bipolar excitation, rectangular unipolar excitation and sinusoidal excitation are compared. An equivalent model of a motor phase including magnetic flux leakage and core losses is presented and the simulation results are discussed. The component values obtained experimentally with sinusoidal excitation are maintained for both cases of rectangular excitation. The good fit between the phase current obtained experimentally and that obtained from the simulation in all three cases demonstrates the validity of the model. This enables the study of the dependence of the effects of the magnetic core on the behavior of a phase of the SRM using the same model.

Influence of non-ideal magnetic core effects on the experimental determination of the magnetic characteristics of a switched reluctance motor

This paper proposes an alternative method to obtain the experimental determination of the flux linkage-current-position characteristics of a switched reluctance motor. Simulations are performed using different models of a phase of the motor. The results are compared with experimental measurements showing the influence of non-ideal effects associated with the magnetic core on determining the flux-current-position characteristics.

Experimental determination of torque-current- position characteristics of a switched reluctance motor with high number of poles

A knowledge of the electromagnetic characteristics of switched reluctance motors (SRM) is crucial for the simulation, analysis, control and development of drive systems based on these machines. Various experimental methods for determining flux-linkage-current-position characteristics can be found in the literature. References relating to the experimental determination of torque-current-position characteristics are few and focus on motors with a low number of poles. Moreover, in all of them the procedure uses the same number of tests as current and position samples necessary for the motor characterization (NI*NP tests, NI being the number of current samples and NP the number of position samples). This paper analyzes the problems related to the application of classical methods for torque experimental determination in a SRM with a high number of poles. We present a new method that avoids these problems and reduces the number of tests (independently of the number of current samples) to one for each position sample. The results are compared with those of classical methods, showing the improvements provided by the proposed experimental determination of the torque-current-position characteristics of a SRM.

Control of a 1 kW switched reluctance generator using triac

A Switched Reluctance Machine can be used as a self-excited generator if a capacitor is connected in parallel to each phase forming an L-C resonant circuit. In this case, the energy generated is related to the scanned area in the flux-current trajectory. This paper proposes a simple control of the energy that can be extracted from the system with a triac. This is the control element of current setting, that implies control of the flux-current area and, consequently, in the generated energy. The control technique described in this paper is patent pending.

Proposals for implementing a new degree on electronics and automation engineering

A new academic curriculum for the Electronics and Automation Enginering Degree at the University of Zaragoza, Spain has been developed in the contest of the European Space for Higher Education. We analyse the distribution and weight of basic contents (subjects related to Mathematics, Physics, Chemistry, Mechanics, Fluids...) and specialized contents (electronics and automation), pointing strengths and weaknesses. Finally, we propose some actions and methodologies for the implementation of this new academic curriculum, Intended to achieve a balance between basic and speclallsed contents oriented to educating Engineers for the European marker.