Machines with non-conventional topologies for more electric applications

Dusek, Jiri (2017) Machines with non-conventional topologies for more electric applications. PhD thesis, University of Nottingham.

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Abstract

This thesis investigates the design, performance and fault tolerant capability of electric machines with unconventional topologies used in more electric drive applications. Two different machine topologies are analysed: Flux reversal permanent magnet machine and a field wound flux switching machine.

Initially, unconventional flux reversal machine topology in which the volume of the permanent magnet material is minimised to improve the fault tolerance capability and lower the costs whilst achieving significant improvement in the torque is investigated through a simulation and validated through experimental work. It is shown that although the machine belongs to the fault tolerant category, an inter-turn short circuit fault will be a problematic as the magnetic flux from the magnet cannot be neutralised and can cause severe damage to the machine under certain conditions.

This however, does not mean that the topologies with permanent magnet material are not suitable for the fault tolerant solutions. If the appropriate design selection in terms of slot and pole numbers is made, the negative influence of the permanent magnet material can be minimised. Therefore, the influence of the slot pole combination on both fault tolerance and performance is investigated and the results are demonstrated on the set of permanent magnet synchronous machines. It is shown that low rotor pole number machines have better fault tolerance capability whilst high rotor pole number machines are lighter and provide higher efficiency.

To overcome the challenges related to the short circuit fault, the topology which eliminates the permanent magnet material and works on a basis of the wound excitation is developed. As the short circuit fault cannot be fully eliminated, a solution which prevent the catastrophic failure and minimises the consequences by using wound excitation system on the stator side instead of permanent magnets is proposed. The modification of a permanent magnet synchronous machine towards improvement of the fault tolerance is presented in detail. Different rotor structures are investigated and optimised to maximise the torque performance. It is shown that using stator of existing machine and replacing the current rotor containing permanent magnets not only improves the fault tolerance, but also reduces the manufacturing and material costs.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Gerada, Chris
Arumugam, Puvan
Keywords: Fault tolerance, Torque, Flux reversal permanent magnet machine, Field wound flux switching machine
Subjects: T Technology > TK Electrical engineering. Electronics Nuclear engineering
Faculties/Schools: UK Campuses > Faculty of Engineering
Item ID: 39973
Depositing User: Dusek, Jiri
Date Deposited: 13 Jul 2017 04:40
Last Modified: 18 Oct 2017 17:53
URI: http://eprints.nottingham.ac.uk/id/eprint/39973

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