Miguel Martínez-Iturralde

Analytical Calculation of the Slot Leakage Inductance in Fractional-Slot Concentrated-Winding Machines

This paper obtains analytical expressions for the calculation of the slot leakage inductance for fractional-slot concentrated-winding (FCSW) machines with one-, two-, or four-layer windings. The formulas are derived from solving the 2-D Poisson problem associated with the slot region, making them more accurate than classically used expressions that assume a leakage flux path parallel to the placement of the conductors in the slot. Explicit formulas are given in the case of one- and two-layer FSCWs with a number of phases ranging from 3 to 7. The obtained analytical expressions are validated by a finite-element analysis, showing excellent agreement between both calculation methods, even for large slot-opening-to-slot-pitch ratios. A brief comment with regard to the fault-tolerant capability of permanent-magnet FSCW machines with respect to the number of layers is also given.

Reduction of detent force in flat permanent magnet linear synchronous machines by means of three different methods

This paper proposes two different techniques to reduce detent force in flat permanent magnet linear synchronous motors (PMLSM). The first one is the choice of an optimal constructive design, taking into account the width and arrangement of the magnets, and the length and shape of the solid iron core. The second is the employment of a force compensator in the control algorithm, which counteracts the detent force effects. Both methods are based on a Fourier analysis of the detent force curve as a function of the machine position. The curve is broken down into harmonics. The constructive method considers that each harmonic has its peculiar source and is independent from the others. The force compensator employs a detent force model based on the Fourier series of the curve. The two methods were tested separately, and their results were compared. Experimental tests were performed to verify the effectiveness of the methods. A very important reduction with a constructive optimization of the machine was achieved. The reduction by means of a compensator in the control scheme also reaches excellent results. In order to achieve the maximum reduction of detent force, both techniques can be combined. This measure will increase the precision features of this kind of machine.

Analytical design of synchronous permanent magnet motor/generators

The main purpose of the work presented in this paper is to obtain a simple and reliable analytical method for the pre-design of surface permanent magnet synchronous generators. With this aim in mind, a design algorithm based on several methods from the bibliography has been developed and programmed. The results from this pre-design have been contrasted by Finite Element Method models and also by testing a built-in permanent magnet synchronous generator prototype. The rotor of this prototype has been designing to get and skewed rotor in order to check data between skewed and non skewed rotor position.

Modelling and simulation of indirect space vector modulated matrix converter using MATLAB®/Simulink®

This article describes a MATLAB®/Simulink® simulation model which analyses the fundamentals about a direct AC–AC power converter with an important research interest at the moment: the matrix converter (MC). The article is focused on space vector modulation modelling applied to this particular converter. The power circuit model is completely implemented using the power library in Simulink, contributing to the simplicity and clearness of the whole model. MC is modulated using the Indirect Space Vector Modulation (ISVM) model which is implemented and explained step-by-step following the space vector basic theory. The model is flexible about changing the modulation technique, the load or removing the input filter, becoming an effective simulation tool in the first stage of a real implementation. It can also be used in an educational environment to present the basic space vector modulation theory applied to the MC.

Modeling of linear induction motors as linear drives

There is a large bibliography in simulation models for linear induction motors (LIMs). However, most of them only consider steady state performance. LIMs working as linear drives generally operate under transient conditions. The aim of this paper is to investigate the suitability of different mathematical models to simulate LIMs as linear drives. A study of most major techniques of calculating lumped parameters is provided. The most representative models capable of simulating transients of LIMs are described and applied to a laboratory prototype. Finally, the results obtained are compared to experimental data.

Direct Liquid Cooling Method Verified With an Axial-Flux Permanent-Magnet Traction Machine Prototype

Efficient cooling is needed, for example, in traction motors which face regularly high torque peaks and generate high stator Joule losses. This paper studies the feasibility of the direct liquid cooling in the thermal management of a low-power low-voltage permanent-magnet machine. A tooth-coil axial-flux permanent-magnet double-stator-single-rotor test machine was first equipped with indirect liquid cooling using water cooling jackets and then with direct winding cooling. The winding material used is a hybrid conductor comprising a stainless steel coolant conduit tightly wrapped with stranded Litz wire. The performance of the motor is examined at various power levels using oil or water as the cooling fluid. The results confirm that the proposed direct cooling method is practical also in small machines, and furthermore, it offers significant improvements in the machine thermal management, especially, in cases where stator Joule losses dominate.

5kW–100 kHz resonant converter prototype for a 40kW energy system unit on tramways

This project has been oriented to the development of an energy system unit for powering tramways during shorts periods of time. The aim of this work is to present the results obtained for a high frequency DC-DC converter which is included in the energy unit. The energy unit will consist on two type of energy storage devices: a battery stack and a supercapacitor stack. A comparison of the simulated model of the DC-DC converter and the real measurement on both topologies, resonant switching and hard switching, has been done. The system works at high frequencies to reduce the weight. In addition, the efficiency should be optimized to reduce the heat sink area and the volume of the whole system. In this case, a 5kW–100 kHz bidirectional DC-DC converter was developed and the results of the first stage are presented.

Control strategies for positioning of linear induction motor: tests and discussion

The target of this paper is to establish the main problems and goals of the four most popular control strategies for induction motor drives, applied to the special case of linear motors: scalar control, direct field-oriented control (direct FOC), indirect field-oriented control (indirect FOC) and direct torque control (DTC). We introduce the peculiarities of the implementation of the different strategies for linear induction motors, the results of experimental tests of the speed controller and position controller, and a discussion of the experiments.

Analysis and comparison of algebraic approaches for highly saturated Surface PMSM

In the present work, two algebraic approaches to calculate magnetic flux linkage of Surface Permanent Magnets Synchronous Machines, (SPMSM), are described. The first one is based on a developed magnetic circuit for load condition, and the second one consists on a magnetic permeance network. Although both approachess base is algebraic, the existing complexity difference between them, makes interesting to perform an analysis of their effectiveness in predicting magnetic flux linkage under highly saturation conditions, when the cross-saturation effect may occur. With this aim, various operation point are calculated at three proposed machine geometries, making them to work at different magnetic saturation level. Obtained d-q axes magnetic flux linkage by presented approaches, are compared with the obtained by finite elements software.

Analytical sizing methodology for inductive power transfer systems

In this paper an analytical sizing methodology for inductive power transfer (IPT) systems is proposed. The methodology is based on the inductance coupling principle. It allows to obtain the geometry (dimension of the coil, number of turns, according to the geometry type: circular, rectangular, square...) and the performance of an IPT system from just a few parameters: nominal power, nominal voltage in primary and secondary winding, air gap and operation frequency. This procedure has been implemented using Matlab, where different prototypes can be obtained in a very short time, reducing significantly the effort during the design process. The validation of the methodology has been carried out through finite element method (FEM) software and the construction and experimentation on a prototype. This paper includes a sensitivity analysis regarding coil sizing methodology, with the introduction of misalignment between windings.