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Sliding Mode 4-Quadrant DCDC Converter for a Flywheel Application
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. (Energy Storage)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. (Energy Storage)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
2013 (English)In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 21, no 4, 473-482 p.Article in journal (Refereed) Published
Abstract [en]

A sliding mode control system for a 4-quadrant DCDC converter was designed and a low voltage prototype was constructed. The target application is a flywheel based all-electric driveline. Important qualities are current and voltage control, bidirectionality, and stability for a broad input voltage range, focusing on a smooth transition between operating quadrants. The control decisions were based entirely on the latest available measurements, implying that no memory needs reinitializing when changing quadrant. The boost control was based on a topology specific current source approximation. The control was found to be parameter invariant, regardless of high input/output dynamics variance.

Place, publisher, year, edition, pages
2013. Vol. 21, no 4, 473-482 p.
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
URN: urn:nbn:se:uu:diva-157065DOI: 10.1016/j.conengprac.2012.12.012ISI: 000316036500012OAI: oai:DiVA.org:uu-157065DiVA: diva2:434393
Available from: 2011-08-15 Created: 2011-08-15 Last updated: 2017-12-08Bibliographically approved
In thesis
1. Power Control Systems in a Flywheel based All-Electric Driveline
Open this publication in new window or tab >>Power Control Systems in a Flywheel based All-Electric Driveline
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Flywheel systems are attractive in hybrid and electric vehicles due to their ability to handle power during acceleration and braking. The combination of a flywheel device with a battery source has several advantages such as high peak power capacity, high energy density and reduction in the number of charge/discharge cycles of the battery.

A flywheel based all-electric driveline is investigated in this thesis. The novelty of the system consists in the use of a double wound flywheel machine, which divides the system in two different power levels. Due to this configuration, the system becomes efficient and can handle the power developed during fast dynamical processes.

The complete driveline consists of three main components: the battery, the flywheel machine and the wheel motor. The High-Power (HP) side of the driveline connects the flywheel machine to the wheel motor, whereas the Low-Power (LP) side connects the flywheel machine to the battery. The connections of different components of the system are made electrically through power converter devices.

The present thesis focuses on the electrical converters and control strategies used in the flywheel based all-electric driveline. The control of power converters is responsible for the logic and functionality of the driveline, being a challenging step within this project.

Different power converter topologies have been investigated: a DC/DC plus a DC/AC converter on the LP side, and an AC/DC/AC converter on the HP side. The design and assembly of the power electronics and their control scheme have been successfully implemented. Different control strategies have been suggested and a complete scaled driveline has been assembled and tested based on previous simulation results.

Results have confirmed the functionality of the driveline, where smoothed output power has been obtained from the battery, whereas the flywheel handles power transients on the traction side. An average efficiency of about 87% (battery to wheels) has been obtained. The power converter systems have been shown to be efficient and robust, with control strategies able to handle the peak energy flow in the system. A regenerative braking strategy has been simulated and a wheel-to-wheel efficiency of about 80% has been estimated.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2011. 102 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 844
Keyword
Flywheels, batteries, electric vehicles, control systems, power electronics, electric machines, efficiency.
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Other Electrical Engineering, Electronic Engineering, Information Engineering Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-157074 (URN)978-91-554-8133-9 (ISBN)
Public defence
2011-09-30, Polhemsalen, Ångström Laboratory, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2011-09-09 Created: 2011-08-15 Last updated: 2011-11-03Bibliographically approved
2. Electrified Integrated Kinetic Energy Storage
Open this publication in new window or tab >>Electrified Integrated Kinetic Energy Storage
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The electric car is a technically efficient driveline, although it is demanding in terms of the primary energy source. Most trips are below 50 km and the mean power required for maintaining speed is quite low, but the system has to be able to both provide long range and high maximum power for acceleration. By separating power and energy handling in a hybrid driveline, the primary energy source, e.g. a battery can be optimised for specific energy (decreasing costs and material usage). Kinetic energy storage in the form of flywheels can handle the short, high power bursts of acceleration and decceleration with high efficiency.

This thesis focuses on the design and construction of flywheels in which an electric machine and a low-loss magnetic suspension are considered an integral part of the composite shell, in an effort to increase specific energy. A method of numerically optimising shrink-fitted composite shells was developed and implemented in software, based on a plane stress assumption, with a grid search optimiser. A composite shell was designed, analysed numerically and constructed, with an integrated permanent magnet synchronous machine. Passive axial lift bearings were optimised, analysed numerically for losses and lift force, and verified with experiments. Active radial electromagnets optimised for high stiffness per ohmic loss were built and analysed in terms of force and stiffness, both numerically and experimentally. Electronics and a high-speed measurement system were designed to drive the magnetic bearings and the electric machine. The control of these systems were implemented in an FPGA, and a notch-filter was designed to suppress eigenfrequencies to achieve levitation of the rotor. The spin-down losses of the flywheel in vacuum were found to be 1.7 W/Wh, evaluated at 1000 rpm.

A novel switched reluctance machine concept was developed for hollow cylinder flywheels. This class of flywheels are shaft-less, in an effort to avoid the shaft-to-rim connection. A small-scale prototype was built and verified to correspond well to analytical and numerical models, by indirect measurement of the inductance through a system identification method.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2017. 93 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1504
Keyword
flywheel energy storage, magnetic bearings, carbon composite
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-319622 (URN)978-91-554-9891-7 (ISBN)
Public defence
2017-06-08, Ång/80101, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Funder
StandUpSwedish Energy Agency
Available from: 2017-05-15 Created: 2017-04-06 Last updated: 2017-05-16

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Hedlund, MagnusGoncalves de Oliveira, JanainaBernhoff, Hans

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