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PhD in the controlled rotordynamics of electrical machines.

Engineering

Location:  UK Other
Closing Date:  Thursday 26 January 2023
Reference:  ENG1604

Electrification is at the very centre of decarbonisation and the development of electrical machines for converting power between mechanical and electrical forms is central to of low-carbon electricity generation, low-carbon transport of all sorts and low-carbon heating and cooling (using heat-pumping). Although electrical machines have existed for almost 200 years, the pace of development is higher now than it has ever been before as we seek to remove weight, remove cost, improve reliability, use only sustainable materials and exploit the latest manufacturing and material developments. For most electrical machines, concerns about the mechanical dynamics introduce design constraints. Put simply, the machine must not shake itself to bits. Traditionally, the approaches taken to resolving these concerns involve making the system mechanically stiff so that the first major resonance frequency lies comfortably above the highest rotor spin speed. Avoiding this constraint could realise quite substantial reductions in cost and mass. The best way to do this is to get the electrical machine itself to produce forces that can help to control vibration. Said differently, we can make the electrical machine behave like a magnetic bearing also. One way to express this concisely is to call it “vibration control using unbalanced magnetic pull” (VCUMP).

Naturally, some work has already been done on VCUMP machines and there are many different possible designs. The earliest attempts had two completely different sets of windings in the machine and/or they used very non-standard power-electronic arrangements to drive the machine. These arrangements are impractical in most contexts because the introduce more cost, mass and unreliability in the new electrical/electromagnetic arrangement than they save in the mechanical system. This PhD is about engineering VCUMP machines that add virtually zero cost, mass or unreliability in the electrical/electromagnetic arrangement relative to a “standard” electrical machine. By utilising clever connections of coils within the machine stator, we can ensure several desirable attributes: (1) the additional mass of conductors required in the VCUMP machine is minimal (often zero), (2) the machine will act exactly as a “normal” electrical machine if no sideways forces are required on the rotor, (3) that if something goes wrong with the features that either determine what sideways forces should be exerted or that drive the currents to implement those forces, these cannot interfere with the normal operation of the electrical machine and (4) the sideways forces can never cause a problem of their own in the mechanical dynamics. Such VCUMP machines are possible and they have the potential to achieve very widespread deployment in applications including white goods, hand-tools, renewable energy generators, nuclear power generation, electrified aerospace propulsion, laboratory equipment, manufacturing equipment, primary power-train machines and range-extenders in ground-based and water-based transportation and space equipment.

The PhD will be supported by expert supervision from two leading research groups at the University of Nottingham – the power-electronics, machines and control (PEMC) group and the gas turbines transmissions research centre (G2TRC). Both have experience of VCUMP machines. The work will call for understanding of both electrical machines and mechanical dynamics so a first degree in either electrical engineering or mechanical engineering is an essential pre-requisite. Whichever engineering discipline has been studied for the first degree, the candidate will likely have to learn a little of the other but the resource is present to support that learning. The work will involve (i) coupled modelling of the combined electro-mechanical dynamics of the system using tools already developed in MATLAB as well as industry-standard tools such as ANSYS, (ii) experimentation to explore and to prove the efficacy of the methods being investigated, (iii) design developments building on concepts that have been introduced already and conceiving extensions of those to improve practicality. The work will explore a combination of full-active control (where a vibration controller takes in measurements of the rotor position and velocity and returns a command current (or voltage)) and semi-passive approaches where a combination of passive elements like resistors, inductors and capacitors is connected into the motor circuits (possibly with some op-amps) to customise and enhance the natural relationship between UMP forces and rotor motions.

Contact details for further information: Prof Seamus Garvey – seamus.garvey@nottingham.ac.uk

Please apply here https://www.nottingham.ac.uk/pgstudy/how-to-apply/apply-online.aspx

When applying for this studentship, please include the reference number (beginning ENG and supervisors name) within the personal statement section of the application. This will help in ensuring your application is sent directly to the academic advertising the studentship. 

The University actively supports equality, diversity and inclusion and encourages applications from all sections of society.


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