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Leijon, Mats
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Publications (10 of 259) Show all publications
Hultman, E. & Leijon, M. (2018). An updated cable feeder tool design for robotized stator cable winding. Mechatronics (Oxford), 49, 197-210
Open this publication in new window or tab >>An updated cable feeder tool design for robotized stator cable winding
2018 (English)In: Mechatronics (Oxford), ISSN 0957-4158, E-ISSN 1873-4006, Vol. 49, p. 197-210Article in journal (Refereed) Published
Abstract [en]

We have previously suggested a method for robotized stator winding of cable wound electric machines and demonstrated the method successfully in full-scale experiments. The cable feeder tool used to handle the cable during the complete winding process is an essential component of this robot cell. To take the robot winding method to the next level, into an industrial product, require further developments regarding durability, independency, flexibility and implementability. In this paper, we present an updated cable feeder tool design. This tool is designed to be used in a robot cell for cable winding of the third-generation design of the Uppsala University Wave Energy Converter generator stator. In this work, three cable feeder tool prototypes have been constructed, experimentally evaluated and validated for the intended application. Key performance parameters are presented and discussed, including suggestions for further developments. We completed a durable, compact, high performance tool design, with fully integrated control into industrial robot controllers. The experimental results presented in this article are very promising and hence, the updated cable feeder tool design represents another important step towards an industrial solution for robotized stator cable winding.

National Category
Robotics Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-334553 (URN)10.1016/j.mechatronics.2018.01.006 (DOI)
Available from: 2017-11-23 Created: 2017-11-23 Last updated: 2018-04-26Bibliographically approved
Parwal, A., Fregelius, M., Temiz, I., Göteman, M., Oliveira, J. G., Boström, C. & Leijon, M. (2018). Energy management for a grid-connected wave energy park through a hybrid energy storage system. Applied Energy, 231, 399-411
Open this publication in new window or tab >>Energy management for a grid-connected wave energy park through a hybrid energy storage system
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2018 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 231, p. 399-411Article in journal (Refereed) Published
Abstract [en]

The concern for climate change and energy consumption has increased the demand for renewable energy production considerably. Marine energy sources attract attention because of their high energy density. Wave energy is an attractive renewable energy source with large potential. Due to the nature of the ocean waves, a linear wave energy converter generates intermittent power. It is therefore crucial to regularize the power before connecting to the grid. Energy storage systems present effective ways to minimize the power fluctuations and deliver a steady power to the grid. In this paper, we present an energy management control system with a dynamic rate limiter. The method is applied to control a hybrid energy storage system, combining battery and supercapacitor, with a fully active topology controlled by the power converters. The results show that the method is able to control the charging and discharging states of the battery and the supercapacitor, and minimize the power fluctuation to the grid. The algorithm ensures low losses by shifting the required power and the stored power smoothly over the energy storage system.

Keywords
Wave energy converter, Hybrid energy storage system, Energy management control system, Dynamic rate limiter, State of charge
National Category
Energy Systems
Identifiers
urn:nbn:se:uu:diva-361207 (URN)10.1016/j.apenergy.2018.09.146 (DOI)
Available from: 2018-09-21 Created: 2018-09-21 Last updated: 2018-09-21Bibliographically approved
Parwal, A., Fregelius, M., Leijon, J., Chatzigiannakou, M. A., Svensson, O., Temiz, I., . . . Leijon, M. (2018). Experimental Test of Grid Connected VSC to Improve the Power Quality in a Wave Power System. In: : . Paper presented at Fifth International Conference on Electric Power and Energy Conversion Systems (EPECS 2018).
Open this publication in new window or tab >>Experimental Test of Grid Connected VSC to Improve the Power Quality in a Wave Power System
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2018 (English)Conference paper, Published paper (Refereed)
National Category
Ocean and River Engineering Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-361208 (URN)
Conference
Fifth International Conference on Electric Power and Energy Conversion Systems (EPECS 2018)
Available from: 2018-09-21 Created: 2018-09-21 Last updated: 2018-10-15
Potapenko, T., Temiz, I. & Leijon, M. (2018). Optimization of Resistive Load for a Wave Energy Converter with a Linear Generator Power Take Off. In: The 4th Asian Wave and Tidal Energy Conference in Taiper, Taiwan, September 9-13, 2018.: . Paper presented at AWTEC2018.
Open this publication in new window or tab >>Optimization of Resistive Load for a Wave Energy Converter with a Linear Generator Power Take Off
2018 (English)In: The 4th Asian Wave and Tidal Energy Conference in Taiper, Taiwan, September 9-13, 2018., 2018Conference paper, Oral presentation with published abstract (Refereed)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-362233 (URN)
Conference
AWTEC2018
Available from: 2018-10-02 Created: 2018-10-02 Last updated: 2018-10-19
Hultman, E. & Leijon, M. (2018). Robotized stator cable winding. Robotics and Computer-Integrated Manufacturing, 53, 197-214
Open this publication in new window or tab >>Robotized stator cable winding
2018 (English)In: Robotics and Computer-Integrated Manufacturing, ISSN 0736-5845, E-ISSN 1879-2537, Vol. 53, p. 197-214Article in journal (Refereed) Published
Abstract [en]

Automated stator winding assembly has been available for small and medium sized conventional electric machines for a long time. Cable winding is an alternative technology developed for medium and large sized machines in particular. In this paper we present, evaluate and validate the first fully automated stator cable winding assembly equipment in detail. A full-scale prototype stator cable winding robot cell has been constructed, based on extensive previous work and experience, and used in the experiments. While the prototype robot cell is adapted for the third design generation of the Uppsala University Wave Energy Converter generator stator, the winding method can be adapted for other stator designs. The presented robot cell is highly flexible and well prepared for future integration in a smart production line. Potential cost savings are indicated compared to manual winding, which is a backbreaking task. However, further work is needed to improve the reliability of the robot cell, especially when it comes to preventing the kinking of the winding cable during the assembly.

National Category
Robotics
Identifiers
urn:nbn:se:uu:diva-334554 (URN)10.1016/j.rcim.2018.04.009 (DOI)000437037900017 ()
Available from: 2017-11-23 Created: 2017-11-23 Last updated: 2018-09-13Bibliographically approved
Leijon, J., Sjölund, J., Ekergard, B., Boström, C., Eriksson, S., Temiz, I. & Leijon, M. (2018). Study of an Altered Magnetic Circuit of a Permanent Magnet Linear Generator for Wave Power. Energies, 11(1), Article ID 84.
Open this publication in new window or tab >>Study of an Altered Magnetic Circuit of a Permanent Magnet Linear Generator for Wave Power
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2018 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 11, no 1, article id 84Article in journal (Refereed) Published
Abstract [en]

The wave energy converter (WEC) studied and developed at Uppsala University in Sweden is a point absorbing buoy connected to a linear generator (LG) on the seabed. Previous studies have improved the sustainability of the generator, changing its magnets from Nd2Fe14B-magnets to ferrites. In this paper, the magnetic circuit of the linear generator is further studied. Ferrite magnets of two different types (Y30 and Y40) are studied along with different shapes of pole shoes for the system. The finite element method (FEM) simulations in a program called Ace are performed. The results show that a linear generator including both Y30 and Y40 magnets and shortened T-shaped pole shoes can generate a similar magnetic energy in the airgap as a linear generator only containing Y40 magnets and rectangular pole shoes. This shows that the magnetic circuit can be altered, opening up sizes and strengths of magnets for different retailers, and thereby possibly lowering magnet cost and transportation. This work was previously presented as a conference at the European Wave and Tidal Energy Conference (EWTEC) 2017 in Cork, Ireland; this manuscript has been carefully revised and some discussions, on magnet costs for example, have been added to this paper.

Keywords
wave energy converter (WEC), linear generator (LG), ferrite permanent magnets (PMs), renewable energy sources
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-348930 (URN)10.3390/en11010084 (DOI)000424397600084 ()
Funder
Swedish Research Council, 2015-03126Swedish Energy Agency, P42243-1
Available from: 2018-04-26 Created: 2018-04-26 Last updated: 2018-10-15Bibliographically approved
Hultman, E. & Leijon, M. (2017). Automated Cable Preparation for Robotized Stator Cable Winding. MACHINES, 5(2), Article ID 14.
Open this publication in new window or tab >>Automated Cable Preparation for Robotized Stator Cable Winding
2017 (English)In: MACHINES, ISSN 2075-1702, Vol. 5, no 2, article id 14Article in journal (Refereed) Published
Abstract [en]

A method for robotized cable winding of the Uppsala UniversityWave Energy Converter generator stator has previously been presented and validated. The purpose of this study is to present and validate further developments to the method: automated stand-alone equipment for the preparation of the winding cables. The cable preparation consists of three parts: feeding the cable from a drum, forming the cable end and cutting the cable. Forming and cutting the cable was previously done manually and only small cable drums could be handled. Therefore the robot cell needed to be stopped frequently. The new equipment was tested in an experimental robot stator cable winding setup. Through the experiments, the equipment was validated to be able to perform fully automated and robust cable preparation. Suggestions are also given on how to further develop the equipment with regards to performance, robustness and quality. Hence, this work represents another important step towards demonstrating completely automated robotized stator cable winding.

Keywords
cable winding, industrial automation, industrial robot, electric machine assembly, wave energy converter
National Category
Robotics
Identifiers
urn:nbn:se:uu:diva-324239 (URN)10.3390/machines5020014 (DOI)000401525400004 ()
Available from: 2017-06-15 Created: 2017-06-15 Last updated: 2017-12-07Bibliographically approved
Kamf, T. & Leijon, M. (2017). Automated Mounting of Pole-Shoe Wedges in Linear Wave Power Generators-Using Industrial Robotics and Proximity Sensors. MACHINES, 5(1), Article ID 10.
Open this publication in new window or tab >>Automated Mounting of Pole-Shoe Wedges in Linear Wave Power Generators-Using Industrial Robotics and Proximity Sensors
2017 (English)In: MACHINES, ISSN 2075-1702, Vol. 5, no 1, article id 10Article in journal (Refereed) Published
Abstract [en]

A system for automatic mounting of high tolerance wedges inside a wave power linear generator is proposed. As for any renewable energy concept utilising numerous smaller generation units, minimising the production cost per unit is vital for commercialization. The linear generator in question uses self-locking wedges, which are challenging to mount using industrial robots due to the high tolerances used, and because of the fact that any angular error remaining after calibration risks damaging the equipment. Using two types of probes, mechanical touch probes and inductive proximity sensors, combined with a flexible robot tool and iterative calibration routines, an automatic mounting system that overcomes the challenges of high tolerance wedge mounting is presented. The system is experimentally verified to work at mounting speeds of up to 50mms(-1), and calibration accuracies of 0.25mm and 0.1 degrees are achieved. The use of a flexible robot tool, able to move freely in one Cartesian plane, was found to be essential for making the system work.

Place, publisher, year, edition, pages
MDPI AG, 2017
Keywords
automated production, wave power, robotics, calibration, sensors, wedges, linear-generator, touch probe
National Category
Environmental Engineering
Identifiers
urn:nbn:se:uu:diva-324353 (URN)10.3390/machines5010010 (DOI)000401524900009 ()
Funder
VINNOVA
Available from: 2017-06-14 Created: 2017-06-14 Last updated: 2017-10-08Bibliographically approved
Sjökvist, L., Göteman, M., Rahm, M., Waters, R., Svensson, O., Strömstedt, E. & Leijon, M. (2017). Calculating Buoy Response for a Wave Energy Converter - a Comparsion Between Two Computational Methods and Experimental Results [Letter to the editor]. Theoretical and Applied Mechanics Letters, 7(3), 164-168
Open this publication in new window or tab >>Calculating Buoy Response for a Wave Energy Converter - a Comparsion Between Two Computational Methods and Experimental Results
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2017 (English)In: Theoretical and Applied Mechanics Letters, ISSN 2095-0349, Vol. 7, no 3, p. 164-168Article in journal, Letter (Refereed) Published
Abstract [en]

When designing a wave power plant, reliable and fast simulation tools are required. Computational fluid dynamics (CFD) software provides high accuracy but with a very high computational cost, and in operational, moderate sea states, linear potential flow theories may be sufficient to model the hydrodynamics. In this paper, a model is built in COMSOL Multiphysics to solve for the hydrodynamic parameters of a point-absorbing wave energy device. The results are compared with a linear model where the hydrodynamical parameters are computed using WAMIT, and to experimental results from the Lysekil research site. The agreement with experimental data is good for both numerical models.

National Category
Marine Engineering
Identifiers
urn:nbn:se:uu:diva-328498 (URN)10.1016/j.taml.2017.05.004 (DOI)000416966800008 ()
Funder
Natural‐Disaster ScienceSwedish Research Council, 2015-04657
Available from: 2017-08-24 Created: 2017-08-24 Last updated: 2018-03-07Bibliographically approved
Elamalayil Soman, D. & Leijon, M. (2017). Cross-Regulation Assessment of DIDO Buck-Boost Converter for Renewable Energy Application. Energies, 10(7), Article ID 846.
Open this publication in new window or tab >>Cross-Regulation Assessment of DIDO Buck-Boost Converter for Renewable Energy Application
2017 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 10, no 7, article id 846Article in journal (Refereed) Published
Abstract [en]

When medium- or high-voltage power conversion is preferred for renewable energy sources, multilevel power converters have received much of the interest in this area as methods for enhancing the conversion efficiency and cost effectiveness. In such cases, multilevel, multi-input multi-output (MIMO) configurations of DC-DC converters come to the scenario for integrating several sources together, especially considering the stringent regulatory needs and the requirement of multistage power conversion systems. Considering the above facts, a three-level dual input dual output (DIDO) buck-boost converter, as the simplest form of MIMO converter, is proposed in this paper for DC-link voltage regulation. The capability of this converter for cross regulating the DC-link voltage is analyzed in detail to support a three-level neutral point clamped inverter-based grid connection in the future. The cross-regulation capability is examined under a new type of pulse delay control (PDC) strategy and later compared with a three-level boost converter (TLBC). Compared to conventional boost converters, the high-voltage three-level buck boost converter (TLBBC) with PDC exhibits a wide controllability range and cross regulation capability. These enhanced features are extremely important for better regulating variable output renewable energy sources such as solar, wind, wave, marine current, etc. The simulation and experimental results are provided to validate the claim.

Keywords
dual input dual output (DIDO) converter; three-level buck boost converter (TLBBC); pulse delay control (PDC); neutral point clamped inverter; cross-regulation; renewable energy conversion
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-332725 (URN)10.3390/en10070846 (DOI)000406700200017 ()
Funder
SweGRIDS - Swedish Centre for Smart Grids and Energy StorageStandUp
Available from: 2017-11-01 Created: 2017-11-01 Last updated: 2018-09-07Bibliographically approved
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