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Losses in Axial-Flux Permanent-Magnet Coreless Flywheel Energy Storage Systems
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
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2008 (English)Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Vilamoura, Portugal, 2008.
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:uu:diva-113430OAI: oai:DiVA.org:uu-113430DiVA: diva2:290834
Conference
18th International Conference on Electrical Machines
Available from: 2010-01-28 Created: 2010-01-28 Last updated: 2016-04-12Bibliographically approved
In thesis
1. FEM Analysis Applied to Electric Machines for Electric Vehicles
Open this publication in new window or tab >>FEM Analysis Applied to Electric Machines for Electric Vehicles
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Electric vehicle technology is an interdisciplinary field in continuous development. It appears to be a margin for improvements. The Division for Electricity at Uppsala University is doing significant research in the field. The present thesis investigates electric machines for vehicular applications, both in the driveline and in the traction motor.

Section 1 presents a driveline with two galvanically isolated voltage levels. A low power side is operated at the optimum voltage of the batteries, while a high power side is operated at a higher voltage leading to higher efficiencies in the traction motor. Both sides are coupled through a flywheel that stabilizes the power transients inherent to a drive cycle.

A review of electric machine topologies for electric vehicles is presented in Section 2. The permanent magnet excited machine is the most suitable technology for an electric driveline.

Section 3 is devoted to numerical models applied to electric machines. The equivalent circuit of a motor/generator with two sets of windings is first presented. This machine couples both sides of the driveline and drives the rotor of the flywheel. The electric parameters are calculated with custom FEM models. A discussion on slotless machines concludes with a simple model to analyze the magnetic field from one static 3D simulation. The tooth ripple losses in solid salient poles are also analyzed with a novel FEM approach. A complete description of the losses in electric machines gives a proper background for further discussion on efficiency.

Section 4 presents the experimental work constructed to validate the theoretical models. The experiments include an axial flux, single wounded prototype, an axial flux, double wound prototype and a planed radial flux coreless prototype.

Section 5 focuses on traction motors for electric vehicles. A simulated prototype illustrates a design and calculation process. The loss theory and the numerical methods presented in Section 3 are applied.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Uppsaliensis, 2011. 54 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 845
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Vehicle Engineering
Identifiers
urn:nbn:se:uu:diva-157879 (URN)978-91-554-8136-0 (ISBN)
Public defence
2011-10-07, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1,, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2011-09-16 Created: 2011-08-24 Last updated: 2011-11-03Bibliographically approved
2. Flywheel in an all-electric propulsion system
Open this publication in new window or tab >>Flywheel in an all-electric propulsion system
2011 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Energy storage is a crucial condition for both transportation purposes and for the use of electricity. Flywheels can be used as actual energy storage but also as power handling device. Their high power capacity compared to other means of storing electric energy makes them very convenient for smoothing power transients. These occur frequently in vehicles but also in the electric grid. In both these areas there is a lot to gain by reducing the power transients and irregularities.

The research conducted at Uppsala university and described in this thesis is focused on an all-electric propulsion system based on an electric flywheel with double stator windings. The flywheel is inserted in between the main energy storage (assumed to be a battery) and the traction motor in an electric vehicle. This system has been evaluated by simulations in a Matlab model, comparing two otherwise identical drivelines, one with and one without a flywheel.

The flywheel is shown to have several advantages for an all-electric propulsion system for a vehicle. The maximum power from the battery decreases more than ten times as the flywheel absorbs and supplies all the high power fluxes occuring at acceleration and braking. The battery delivers a low and almost constant power to the flywheel. The amount of batteries needed decreases whereas the battery lifetime and efficiency increases. Another benefit the flywheel configuration brings is a higher energy efficiency and hence less need for cooling.

The model has also been used to evaluate the flywheel functionality for an electric grid application. The power from renewable intermittent energy sources such as wave, wind and current power can be smoothened by the flywheel, making these energy sources more efficient and thereby competitive with a remaining high power quality in the electric grid.

Place, publisher, year, edition, pages
Uppsala: Uppsala universitet, 2011. 50 p.
Series
Licentiate Thesis, Division of Electricity, Department of Engineering Sciences, ISSN 0349-8352
Keyword
Flywheel, electric vehicle, hybrid vehicle, power management, energy storage
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-222030 (URN)
Presentation
2011-06-10, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2014-04-09 Created: 2014-04-07 Last updated: 2014-04-09Bibliographically approved

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de Santiago Ochoa, JuanGoncalves de Oliveira, JanaínaLundin, JohanLarsson, AndersBernhoff, Hans

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