Nuestros investigadores

Miguel Martínez-Iturralde Maiza

Publicaciones científicas más recientes (desde 2010)

Autores: Artetxe Ballejo, Gurutz (Autor de correspondencia); Paredes, J.; Prieto Rocandio, Borja; et al.
ISSN 1996-1073  Vol. 11  Nº 1  2018 
This paper studies the feasibility of using synchronous reluctance machines (SynRM) for low speed-high torque applications. The challenge lies in obtaining low torque ripple values, high power factor, and, especially, high torque density values, comparable to those of permanent magnet synchronous machines (PMSMs), but without resorting to use permanent magnets. A design and calculation procedure based on multistatic finite element analysis is developed and experimentally validated via a 200 Nm, 160 rpm prototype SynRM. After that, machine designs with different rotor pole and stator slot number combinations are studied, together with different winding types: integral-slot distributed-windings (ISDW), fractional-slot distributed-windings (FSDW) and fractional-slot concentrated-windings (FSCW). Some design criteria for low-speed SynRM are drawn from the results of the study. Finally, a performance comparison between a PMSM and a SynRM is performed for the same application and the conclusions of the study are summarized.
Autores: Satrustegui de Legarra, Marco (Autor de correspondencia); Artetxe Ballejo, Gurutz; Elosegui Simón, Ibon; et al.
ISSN 1359-4311  Vol. 129  2018  págs. 93 - 105
A computational fluid dynamics (CFD) model representing the effect of wafters in a totally enclosed electric machine is presented, introducing the most relevant theoretical assumptions and simplifications. The validation of the model is conducted through experimental measurements. From the CFD simulation data, a second-order response surface is developed using statistical tools, from which the wafters' influence on the convective heat transfer from the stator end windings is predicted. Wafter design criteria are obtained from the response surface information. Finally, a specific case is analysed, showing through CFD simulations that temperatures in the machine are reduced by including wafters in the design. (C) 2017 Elsevier Ltd. All rights reserved.
Autores: Caballero, D. , (Autor de correspondencia); Prieto Rocandio, Borja; Artetxe Ballejo, Gurutz; et al.
ISSN 1996-1073  Vol. 11  Nº 9  2018  págs. 2294
Interior Permanent Magnet Synchronous Machine (IPMSM) are high torque density machines that usually work under heavy load conditions, becoming magnetically saturated. To obtain properly their performance, this paper presents a node mapping criterion that ensure accurate results when calculating the performance of a highly saturated IPMSM via a novel magnetic reluctance network approach. For this purpose, a Magnetic Circuit Model (MCM) with variable discretization levels for the different geometrical domains is developed. The proposed MCM caters to V-shaped IPMSMs with variable magnet depth and angle between magnets. Its structure allows static and dynamic time stepping simulations to be performed by taking into account complex phenomena such as magnetic saturation, cross-coupling saturation effect and stator slotting effect. The results of the proposed model are compared to those obtained by Finite Element Method (FEM) for a number of IPMSMs obtaining excellent results. Finally, its accuracy is validated comparing the calculated performance with experimental results on a real prototype.
Autores: Satrustegui de Legarra, Marco; Martínez-Iturralde Maiza, Miguel; Ramos González, Juan Carlos; et al.
ISSN 1359-4311  Vol. 114  2017  págs. 1018 - 1028
An analytical thermal model of an IC71W Induction Machine (IM) is presented, introducing the most relevant theoretical assumptions and equations. The validation of this model is conducted through experimental measurements. Some criteria for design of the most critical parts of the cooling system are provided using both a model based on Computational Fluid Dynamics (CFD) techniques and the analytical thermal model. First, the design of the water jacket and its main parameters are broadly analysed and some correlations for the design of the cooling ducts are presented. The influence of wafters on this cooling arrangement is also discussed. (C) 2016 Elsevier Ltd. All rights reserved.
Autores: Lindh, P.; Petrov, I.; Jaatinen-Varri, A. ; et al.
ISSN 0278-0046  Vol. 64  Nº 8  2017  págs. 6086 - 6095
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 coolingmethod 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.
Autores: González Prada, Jorge; López de Sabando, A.; Antón Remírez, Raúl; et al.
ISSN 0949-149X  Vol. 31  Nº 1  2015  págs. 209 - 219
Formula Student (also known as Formula SAE) is an international competition for universities that challenges the students with a comprehensive engineering problem. Most of the participant universities and all the companies involved in the organization of the competition have identified this event as the most suitable tool for hard and soft skills development. This paper evaluates this development by means of two different objective assessments in the frame of a specific team, identifying the potential of the competition and showing a particular approach to enhance soft skills development.
Autores: Malumbres Ruiz, José Ángel; Satrustegui de Legarra, Marco; Elosegui Simón, Ibon; et al.
ISSN 1751-8660  Vol. 9  Nº 8  2015  págs. 513 - 522
The prediction of the thermal behaviour of electric motors in the early stages of their design is a critical factor for reducing time and cost in the design process. In complex machine topologies such as open self-ventilated machines, there are several phenomenas to take into account in order to predict the correct thermal behaviour of the machine. In this study, a thermal model coupled with a hydraulic model is presented. These models provide information of the thermal behaviour of the machine. First, the complete thermal circuit is described, with some emphasis in the specially modelled parts. Then, the heat transfer coefficients for each surface inside the machine are presented, by the use of dimensionless correlations that avoids the need of previous knowledge. Moreover, the hydraulic model of the machine is studied, and also the coupling methodology between the two models is described for both steady state and transient calculations. Finally, the results from the model are validated using the data from two experimental runs, the first one with constant torque and speed, and the other with variable power, in a standardised service cycle, with a difference in the rotor bars and the stator winding below +/- 10 degrees C.
Autores: Prieto, B.; Martínez-Iturralde Maiza, Miguel; Fontán Agorreta, Luis; et al.
ISSN 0278-0046  Vol. 62  Nº 5  2015  págs. 2742 - 2752
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.
Autores: Prieto, B.; Martínez-Iturralde Maiza, Miguel; Fontán Agorreta, Luis; et al.
ISSN 1751-8660  Vol. 9  Nº 2  2015  págs. 138 - 149
Interest in permanent magnet synchronous machines for safety-critical applications has been increasing over the years. One of the most common methods for providing fault tolerance to a permanent magnet machine is the active control from the drive side. This method requires designing machines with the lowest possible mutual coupling between phases and a self-inductance that is high enough to limit the fault currents. Fractional-slot concentrated windings have been proposed as the most advantageous solution to meet these requirements. When comparing the numerous combinations of phases, poles and slots that give rise to a fractional-slot concentrated winding, the usual criteria only focus on obtaining a single-layer winding and do not actually consider the relationship between the self-inductance and the mutual inductance between phases. Moreover, they give no recommendations regarding the optimal number of phases from a magnetic point of view. The present work aims to cover this gap by obtaining analytical expressions for the calculation of the inductances in a permanent magnet machine. The derived expressions are investigated regardless of the geometry of the machine, and the criteria for selecting the most promising combinations in terms of the machine's fault tolerance are extracted.
Autores: Malumbres Ruiz, José Ángel; Satrustegui, M.; Elosegui Simón, Ibon; et al.
ISSN 1359-4311  Vol. 75  2015  págs. 277 - 288
Prediction of the thermal behavior of electric motors in the early design stage is crucial in any design process. The most popular prediction methods are analytical, and based on the lumped parameter model approach. These methods require experimental data in order to obtain accurate results, but this data is often not available. This paper deals with the problem of the lack of experimental data for an Open Self-Ventilated (OSV) Induction motor and reviews some of the most controversial parameters in thermal modeling, such as the bearings model and the axial conductivity of the lamination stack. Due to the nature of the OSV machine, through ventilation is also investigated, and a hydraulic model with improvements focused on rotational effects observation is presented. Moreover, the heat transfer in end spaces and ducts is studied, using dimensionless analysis correlations, along with focusing on new hydraulic phenomena, such as the development of the flow and the roughness effect. An implementation of a thermal circuit for an OSV machine that has good agreement with reference results is used to compare heat transfer coefficients used regularly for Totally Enclosed Fan Cooled (TEFC) enclosures. Finally, a sensitivity analysis is carried out on some parameters to determine their importance. (C) 2014 Elsevier Ltd. All rights reserved.
Autores: Jiménez Pérez, Jorge; Malumbres Ruiz, José Ángel; Elosegui Simón, Ibon; et al.
ISSN 1827-6660  Vol. 8  Nº 5  2013  págs. 1416 - 1426
The design process for permanent magnet linear motors (PMLM) is similar to that used for their rotary counterparts. A number of electro-technical equations are used to get the best design for a specific application. Nevertheless, there are two issues that differ from the design of a standard rotary machine that must be considered. The first one is the intrinsic asymmetry of the magnetic circuit, which makes the flux distribution different from pole to pole. The second one is the particular geometry and constraints of the thermal circuit, which is crucial for the design of miniaturize linear motors. This paper presents an analytical method for computing the flux distribution in a surface-mounted PMLM. The method, based on the equivalent magnetic circuit method, considers the saturation of the material, the leakage at the end of the motor and the asymmetrical distribution of the magnetic flux. Additionally, an analytical lumped parameter thermal model for linear drives that gives results for both transient and steady-state temperatures is described. Validation of the models is performed by using Finite Element and Computer Fluid Dynamics software. Finally, both magnetic and thermal circuits have been used to design a miniaturized PMLM to drive a sliding door to experimentally verify its goodness
Autores: Satrustegui de Legarra, Marco; Martínez-Iturralde Maiza, Miguel; Rivas Nieto, Alejandro; et al.
ISSN 1974-9821  Vol. 6  Nº 5  2013  págs. 1446 - 1451
This paper describes an algebraic model for predicting the air flow-rate in the cooling system of an open self-ventilated machine. The method is easily applicable to any type of air-cooled electrical machine. The air flow-rates in different areas of the machine as well as the head losses of the hydraulic system were obtained, and the results were compared with a more detailed model developed with Computational Fluid Dynamic (CFD) techniques. Moreover, a sensitivity analysis was carried out in order to compare the different topologies of the machine studied
Autores: Caballero González, Damián; Zeberio, I.; Fontán Agorreta, Luis; et al.
ISSN 1827-6660  Vol. 8  Nº 4  2013  págs. 1181 - 1188
In this paper, an analytical method to obtain the magnetic flux in the air gap and the flux densities in surface mounted permanent magnet synchronous machines is described. The particularity of the method, which is based on the magnetic lumped parameter circuit approach, is that it is capable of predicting the magnetic decrease in the air gap due to the cross coupling between the d-axis and the q-axis (cross-magnetizing effect), shifting the angle of the magnetic axis. Moreover, the presented method can also evaluate the local flux density level at the sides of the pole magnets, which is very useful for preventing local magnet demagnetization at load conditions. The methodology is compared with Finite Element Method based simulations, with very good results.
Autores: Ibañez, Federico; Vadillo Landajuela, Javier; Martínez-Iturralde Maiza, Miguel; et al.
ISSN 1598-2092  Vol. 12  Nº 2  2012  págs. 233 - 241
This paper presents a design of a 30kW 250V/530V bidirectional DC-DC converter to be used in an electrical car. A detailed explanation of the design is given. The system uses two phase shifted half bridge (boost and buck) topologies to reduce the ripple current in the output capacitor. The converter has an efficiency of 95% at nominal power. It works as a constant voltage in one direction and as a constant current in the other to charge the batteries. Simulations and measurement are done at high power to test the efficiency.
Autores: Egaña Arregui, Juan María; Elosegui Simón, Ibon; Echeverria Ormaechea, José Martín; et al.
ISSN 1827-6660  Vol. 6  Nº 3  2011  págs. 1228 - 1238
This paper presents an analytical method to compute the magnetic flux distribution in spoke interior permanent-magnet (IPM) machines with non-magnetic shaft from no-load to short-circuit conditions. Despite non-magnetic shaft gets significant reduction of the PM leakage flux, this cannot be neglected to calculate correct flux distribution; thus, shaft leakage flux is analyzed and modelled. Moreover, as the demagnetization characteristic of the machine depends on the magnetic circuit, simple mathematical equations to estimate the demagnetization level of the magnets are also given. Based on this approach, protection against demagnetization due to short-circuit current and maximum field-weakening level achievable are easily estimated. The presented formulation and methods are used to optimize the rotor of an IPM machine in order to maximize the electromagnetic torque (30% higher), minimize the amount of PM material, and protect PMS against demagnetization under field-weakening and short-circuit conditions. Analytical results are compared with finite-element software, showing errors lower than 4% in the no-load magnetic circuit and lower than 12% at short-circuit conditions. Presented formulation and methods have very low computation time, so the design process time of spoke IPM machines is significantly reduced. The proposed analytical approach is also applicable to other PM machines. Copyright (C) 2011 Praise Worthy Prize S.r.L - All rights reserved.