Paul Lefley

• MSc Coordinator
• IET Liaison Officer
  

Lecturer
Electrical Power and Power Electronics Group

BSc (Eng), PhD (Nottingham), CEng, MIET, MIEEE
T: +44 (0)116 252 2526
F: +44 (0)116 252 2619
E: pwl3@le.ac.uk

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.

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 had 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.

Fig 2: A CAD model of a new energy efficient electric motor

Recent Publications:

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• Transformers in Practice, Lopez-Fernandez, Turowski, Kazmierski, Lesniewska, Ertan, Lefley, et al, monograph ISBN 978-84-609-9515-9, 2007.
• A New Simplified Sensorless Control Method For A Single Phase SR Motor Using HF Signal Injection, Ahmed S, Lefley P W, 42nd International Universities Power Engineering
Conference 2007, Brighton, pp890-894.
• A New Breed of Power Supply for ESPs, Lefley P W, Parker K, SAIEE Energize Power Journal, July 2006, pp 56-61.
• Breathe Easy, Lefley P W and Parker K, IEE Power Engineer, vol.20, (issue 1 February/March), 2006, pp39-43
• Transformer Design for High Voltage, High Frequency, High Power, Lefley P W, Fothergill J C, Devine P J, Advanced Research Workshop on Modern Transformers (ARWtr 2004),
Vigo Spain, October 2004
• Is Lead Dead? Starkey J P, Lefley P W, IEE Power Engineering Journal Dec/Jan 2003/04, pp 30-35
• A Novel High Current, Short Pulse Battery Charging System Using a Variable Pulse Frequency Resonant Converter, Starkey J P, Lefley P W, 10th European Conference on Power
Electronics and Applications, Toulouse, September 2003
• Finite Element Analysis Of Three Dimensional Current Distribution In Pasted Grid Plates For Lead Acid Batteries, Starkey J P, Lefley P W, 37th International Universities Power
Engineering Conference 2002, pp890-894.