I.E. Chabu

Mitigation of the Torque Ripple of a Switched Reluctance Motor Through a Multiobjective Optimization

The purpose of this work is to perform a multiobjective optimization in a 4:2 switched reluctance motor aiming both to maximize the mitigation of the torque ripple and to minimize the degradations of the starting and mean torques. To accomplish this task the Pareto Archived Evolution Strategy was implemented jointly with the Kriging Method, which acts as a surrogate function. The technique was applied on the optimization of some rotor geometrical parameters with the aid of finite element simulations to evaluate the approximation points for the Kriging model. The numerical results were compared to those from tests.

Spectral Analysis Using a Hall Effect Sensor for Diagnosing Broken Bars in Large Induction Motors

This paper presents the use of an invasive method specially applied for broken rotor bars diagnosis in large induction machines, considering the frequency domain analysis of the magnetic flux density variation in a low-cost Hall effect sensor. The proposed method is based on the Fast Fourier transform, or spectral analysis of the resultant magnetic flux density, to contribute to a crack and bar breaks diagnosis on large squirrel cage motors. More particularly, this paper considers the use of a method capable of overcoming some drawbacks from traditional diagnostic techniques, such as motor current signature analysis during operation at very low slip. The results from the computational simulation and some experimental tests are presented and could be considered for rotor failure diagnostics in induction motors.

A new design technique based on a suitable choice of rotor geometrical parameters to maximize torque and power factor in synchronous reluctance motors. I. Theory

The influence of rotor geometry of synchronous reluctance motors (SRMs) on the x/sub d//x/sub q/ ratio, electromagnetic torque and iron losses is studied. Both air-gap length and rotor pole are are taken into account as parameters. First, a new theoretical approach is developed which neglects saturation effects (Part I). In a companion paper (Part II), a complete finite-element analysis of a particular SRM is carried out, followed by a comparison with results obtained by tests performed in a prototype machine, which was constructed in order to validate the proposed methodology.

A multi‐objective analysis of a special switched reluctance motor

Purpose – The design of electrical machines includes the computation of several requirements and, in general, the improvement of one requirement implies in a degradation of another one: this is a typical multi‐objective scenario. The paper focuses on the multi‐optimization analysis of a special switched reluctance motor.Design/methodology/approach – Two design requirements were analyzed: the average torque and the ripple torque. The electromagnetic field computation was performed by the finite element method and the torque was computed by the Coulombs Virtual Work for several positions. This allows us to calculate the average torque and the ripple torque. Three different methods were used to obtain the Pareto set: a min‐max approach, the non‐dominated sorting genetic algorithm (NSGA) and the strength Pareto evolutionary algorithm (SPEA). In order to save the computation time, the objective functions (the average torque and the ripple torque) were replaced with surrogate functions. Kriging models were use...

Design aspects of 4:2 pole-2 phase switched reluctance motors

Switched reluctance motors (SRM) are nowadays a well established choice for rugged and reliable variable speed drive applications. The 4:2 pole-2 phase configuration is particularly suited for low cost drives due to simpler motor construction and simpler driver topology with only two power switches. This solution has been proposed for fractional horsepower and relatively high speed applications like hand tools and light domestic appliances. In this paper some design aspects are treated, concerned with the SRM magnetic circuit. An analytical approach is first utilized for main geometric parameters definition and torque evaluation. In the sequence, a numerical approach utilizing finite element method is carried out to precise torque and inductance characteristics determination.

Thermal characterization of long electrical devices-application to a tubular linear induction motor

This paper presents a new modeling technique to simulate temperature rise in long electrical devices. The usual circuit description of thermal processes in electrical machines is studied and a new representation to account for beat exchange by moving fluids is proposed. The model is applied in the evaluation of temperature rise in a long tubular linear induction motor, utilized in the drive system of a sucker rod pump in oil exploitation.

Modeling study of an Implantable Centrifugal Blood Pump actuator with redundant sensorless control

The permanent magnet brushless direct current motor (BLDC), have been the main component in most of the Ventricular Assist Devices (VAD) development. An Implantable Centrifugal Blood Pump is being developed at the Institute Dante Pazzanese of Cardiology (IDPC) as VAD to assist patients with cardiovascular diseases. To develop a high performance controller is necessary to have a reliable virtual model of the BLDC. Toolbox SimPowerSystems software package was used to study the dynamic system. Permant Magnet Synchronous Machine (PMSM)block implements the differential equations for the motor through a state-space model, this is main contribution of this work. Sensorless control was used as redundant position rotor control. The model showed satisfactory results when compared with data given by the manufacturer in its catalog. In future works, the results presented in this work will be used to improve the motor model. Thus, it will allow reliable simulations of new proposed controllers.

Analytical modeling of shaded pole motors with non-uniform air gap

The great utilization of non-uniform gap shaded pole motors has imposed the creation of a method to simulate its performance. This work has as proposal the introduction of an analytical-method to simulate the performance of non-uniform gap shaded pole motors. In the analytical section, it is proposed a method that employs an equivalent electrical circuit and the non-uniformity of the gap is taking in account by the decomposition of self and mutual inductances of and between each winding in harmonic components. The interactions between components of different harmonic orders are also considered. Lastly, it is described a proceeding to introduce the iron material permeability and its losses as function of the power source and the motor slip.

Eddy-current brake analysis using analytic and FEM calculations. II. Application

For pt.I see ibid., p.454-7 (2001). In this second part is shown the practical application of the model for eddy-current brakes, presented in the first part of the work. Initially a finite element analysis is made of a commercial brake to obtain the coefficients that adjust the derived equation for the brake. With these coefficients, the mathematical model is applied to evaluate the characteristic curves of the brake. At the end, a comparison is made of the models results with the tests results in the prototype. A comparison is also made among the pure finite element analysis and the experimental results.

A new design technique based on a suitable choice of rotor geometrical parameters to maximize torque and power factor in synchronous reluctance motors. II. Finite-element analysis and measurements

The influence of rotor geometry of synchronous reluctance motors (SRMs) on the x/sub d//x/sub q/ ratio, electromagnetic torque and iron losses is studied. Both air-gap length and rotor pole arc are taken into account as parameters. In the first part, a new theoretical approach was developed neglecting saturation effects. Here, the analytical determination of the parameters and the machine behaviour is performed for a particular SRM, on the statement of Part I, including saturation effects. Also a complete finite-element analysis is carried out, followed by a comparison with results obtained by tests performed in a prototype machine, which was constructed in order to validate the proposed methodology.