Dr Paul Lefley
- MSc Senior Tutor and Admissions Coordinator
- Formula Student Coordinator
Lecturer in the
Electrical Power and Power Electronics Group
BSc (Eng), PhD (Nottingham), CEng, MIET, MIEEE, MRI
T: +44 (0)116 252 2526
F: +44 (0)116 252 2619
Location: Room 1002, Engineering Tower
Main Research Interests:
Dr. Lefley’s research interests are principally in three areas: novel electrical machines, drives and control, and the application of power electronics and pulsed power to new areas, for example, ultra-rapid battery recharging for various kinds of batteries and electric vehicles. Dr. Lefley has an international reputation on all of this work, and much of it has been commercialized through two spin-out companies. Dr. Lefley would like to encourage interested parties to make contact to find out how they can become involved with his research.
Electrical Machines and Drives:
Recent work in the field of electrical machines has lead to the development of a new type of brushless electric motor that is energy efficient, electronically controlled and has a low manufacturing cost, with the intention to make OEM manufacturers aware of an alternative to the world’s reliance on inefficient single phase induction motors. These energy efficient motors are based on new patented designs and are essentially permanent magnet based brushless DC motors with very low electronic component count. The new designs have been developed for low torque ripple and quiet operation. The new motors are attracting growing commercial interest worldwide. See also the link to the Centre for Advanced Electrical Machines and Drives at Leicester.
Traditionally Dr. Lefley has developed electric motors for electric and hybrid vehicles. However, recently he has also developed new bespoke motor/generator technologies for aerospace applications where high power densities at very high speeds are essential. Such machines are designed to be directly coupled to gas-turbines for power generation and APU applications. The machine performs initially as a high speed starter and then as a generator after the gas-turbine has fired up. This is a new field and is of considerable interest not only in aerospace but in military applications as well. Dr. Lefley has also developed in conjunction with colleagues from the Electrical and Electronic Power Engineering Group a complete fuel cell based electric vehicle drive system using a Nexa fuel cell, ultra-capacitors for energy storage, and an energy efficient permanent magnet brushless DC motor.
Fig 1: Nexa fuel cell; part of the electric vehicle traction drive system developed in the Electrical and Electronic Power Engineering Group
Current Major Research Projects:
Power Electronics and Pulsed Power
Dr. Lefley has considerable experience in the development of power electronic based systems including recently, the application of pulsed power both at very high currents and high voltages. The work on ultra-rapid battery recharging stemmed from fundamental work on how a rechargeable battery may accept charge at a high rate without causing deleterious effects to the battery such as overheating, gassing, active material shedding, etc. A new recharging scheme has been devised to inject charge into the battery at a very high rate.
The work on very high current power electronics (up to 2,500 amps) is applicable to all large scale energy storage media, and interested parties are encouraged to contact Dr. Lefley. Much of the ultra-rapid battery recharging development is currently seeing commercial interest. The work on electrostatic precipitation was an application of modern high frequency switched mode power electronics to replace the traditional low frequency transformer/rectifier set, but also, to improve the dust collection efficiency in the precipitator by applying a controllable pulsed waveform from the new power supply. This system was implemented in a pilot project at Didcot B power station in Oxfordshire, UK.
Dr. Lefley continues to develop low cost, energy efficient electric motors based on the single phase BLDC motor design, as well as high power density machines for aerospace applications. The most recent project is the development of an electromagnetic torque amplifier (or converter). This is a very novel idea intended for hybrid electric vehicles. It combines aspects from both a series hybrid and a parallel hybrid drive trains, with the intention to reduce the weight and cost of existing hybrid vehicle power plant and transmission systems.
Fig 2: A CAD model of a new energy efficient electric motor
Total income to date (research, KTPs, business development, consultancies): £ 867k.
• Optimal Design of a Novel Single Phase PM BLDC Motor Using Genetic Algorithm, Lefley P, Ahmed S, EPE-PEMC 2012, Novi-Sad, September 2012.
• Cogging Torque Minimization in the Double Stator Cup Rotor Machine, Diryak E, Lefley P, 4th Symposium on Applied Electromagnetics SAEM'12, 3rd to 6th June 2012, Sopron Hungary.
• High Voltage, High Frequency Transformer Design, Lefley P, Devine P. Transformers Analysis Design and Measurement, CRC Press, Monograph Ch 21, ISBN 9781466508248.
• Synthesis and Analysis of a High-performance Low-cost Permanent Magnet Brushless DC Motor, Lefley P, International journal for Computation and Mathematics in Electrical and Electronic Engineering (COMPEL).
• Fault Detection of a Series Compensated Line during the Damping Process of Inter-area Mode of Oscillation, Lami F, Lefley P. IET DPSP 2012 - Protecting the Smart Grid. The 11th International Conference on Developments in Power System Protection. 23-26 April 2012.
• Rechargeable batteries – Part 4: Battery graveyard, Energize April 2012 Lefley P, Soge A, Starkey J
• Rechargeable batteries – Part 3: Lithium-ion batteries, Energize April 2012 Lefley P, Soge A, Starkey J
• Rechargeable Batteries Part 2: Nickel based batteries, Energize March 2012 Lefley P, Soge A, Starkey J
• Rechargeable Batteries – The Evolution and Beyond, Energize Jan/Feb 2012 Lefley P, Soge A, Starkey J
• A New Design of Low Cost Energy Efficient Single Phase Brushless DC Motor, Lefley P, Ahmed S, Journal of Electrical Research Review, ISSN 0033-2097, 2/2012.
• Static Characteristics of a Novel Low Cost Brushless DC Permanent Magnet Motor, Lefley P, Journal of Electrical Research Review, ISSN 0033-2097, R88 NR 1a/2012.
• A Novel Three-Phase Buck-Boost Power Quality Converter, Lefley P, Starkey J, Seventh Mako/CIGRE Conference October 2 – 4, 2011.
• Synthesis and Analysis of a High Performance Low-Cost Permanent Magnet Brushless DC Motor L. Petkovska, P. Lefley, G. Cvetkovski XV International Symposium on Electromagnetic Fields in Mechatronics, Electrical and Electronic Engineering – ISEF'2011 Funchal, Madeira September 2011.
• Optimisation of the Design Parameters of an Asymmetric Brushless DC Motor for Cogging Torque Minimisation, Lefley P, Petkovska L, Cvetkovski G, European Power Electronics Conference EPE 2011, Birmingham, September 2011.
• From Dynamic Modelling to Experimentation of an Induction Motor Powered by a Doubly-Fed Induction Generator by Passivity based Control, Electrical Machines and Drives, InTech, Monograph Ch 7, ISBN 978-953-307-548-8.
• Design and Control of the Brushless Doubly Fed Twin Induction Generator (BDFTIG) - Part 2, Bensadeq A, Lefley P, IEEE 14th International Power Electronics and Motion Control Conference 6th to 8th September 2010, (EPE-PEMC 2010), Ohrid.
• Finite Element Analysis of a Novel Single Phase Permanent Magnet Brushless DC Motor, Lefley P, Ahmed S, IEEE 14th International Power Electronics and Motion Control Conference 6th to 8th September 2010, (EPE-PEMC 2010), Ohrid.
• Study of the Impact of Asymmetrical Stator Pole Arc on the Cogging Torque for Single Phase Permanent Magnet BLDC Motor, Ahmed S, Lefley P, IEEE International Conference on Electric Power and Energy Conversion Systems 10th to 12th November 2009, (EPECS09), Al Sharjah.
• Design and Control of the Brushless Doubly Fed Twin Induction Generator (BDFTIG), Bensadeq A, Lefley P, IEEE 11th Spanish Portuguese Conference on Electrical Engineering 1st to 4th July 2009, (11CHLIE), Zaragoza.
• Development of a Single Phase PM BLDC Motor from a Novel Generic Model, Ahmed S, Lefley P, IEEE 11th Spanish Portuguese Conference on Electrical Engineering 1st to 4th July 2009, (11CHLIE), Zaragoza.
• Energy Efficiency Advantages of a Brushless DC Motor for a Variable Speed Compressor. Lefley P , Currington I, International Rotating Equipment Conference, Dusseldorf, 27th to 29th October 2008.
• Transformers in Practice, Lopez-Fernandez, Turowski, Kazmierski, Lesniewska, Ertan, Lefley, et al, monograph ISBN 978-84-609-9515-9.