Abelardo Martinez-Iturbe

Ultracapacitor-based plug & play energy-recovery system for elevator retrofit

Vertical transportation is a promising field in terms of efficiency improvement opportunities. Several manufacturers are working on the development of new and efficient elevator lifts based on energy-recovery schemes. This paper is focused on the retrofit of already existing inverter-based non-efficient elevator actuators. This purpose is achieved through a) the connection of only two wires to the DC bus of the existing inverter, and b) a very simple but robust control based on several voltage hysteresis-bands. Simulation and experimental results show the validity of the approach.

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 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.