Professor Geraint Jewell
PhD, BEng
Department of Electronic and Electrical Engineering
Professor
Electrical Machines and Drives Research Group
Lecturer for Aerospace Engineering

+44 114 222 5845
Full contact details
Department of Electronic and Electrical Engineering
- Profile
-
I am a graduate of the Department (BEng 1988, PhD 1992) and have been a member of the academic staff since 1994. During my time on the academic staff I held an EPSRC Advanced Research Fellowship (2000-2005) and a Royal Society Industry Fellowship at Rolls-Royce (2006-2008).
I have been Director of the Rolls-Royce University Technology Centre in Advanced Electrical Machines since 2006 and Director of the EPSRC Future Electrical Machines Manufacturing Hub since 2019.
Alongside my mainstream academic roles within the Department, I served as the Faculty of Engineering’s first Faculty Director of Research and Innovation from 2008-2011 and as Head of the Department from 2013 to 2019.
My PhD research was concerned with the electromagnetic modelling and design of capacitor- discharge multipole magnetizing fixtures for NdFeB magnets, which at that time were a relatively recent development that posed many magnetization challenges.
I then applied the underpinning transient modelling to the problem of eddy currents in pulsed magnetometry for permanent magnet characterisation.
Since becoming a member of academic staff my interests have broadened to cover many aspects of electromechanical devices including electrical machines (permanent magnet, switched reluctance, synchronous reluctance) and linear actuators.
Much of this research has been directed towards aero-engine applications in collaboration with Rolls-Royce. This research has included high temperature devices (many around 400℃ but with one up to 800℃) and several demonstrator starter-generators for aero-engines.
I have also had a long-standing interest in core loss calculation methods for electrical machines. I have supervised ~20 PhD students to completion across a wide range of electromagnetic and electro-mechanical topics.
- Research interests
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- Power dense electrical machines for aerospace applications
- Linear electromagnetic actuators
- Electromagnetic modelling of novel devices
My PhD research was concerned with the electromagnetic modelling and design of capacitor- discharge multipole magnetizing fixtures for NdFeB magnets, which at that time were a relatively recent development that posed many magnetization challenges.
I then applied the underpinning transient modelling to the problem of eddy currents in pulsed magnetometry for permanent magnet characterisation.
- Publications
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Journal articles
- Analytical modelling of dynamic performance with harmonic current injection for doubly salient SynRMs. IEEE Transactions on Industry Applications. View this article in WRRO
- Systematic design study into the influence of rotational speed on the torque density of surface-mounted permanent magnet machines. The Journal of Engineering, 2019(17), 4595-4600. View this article in WRRO
- Design, construction, and testing of an aero-engine starter-generator for the more-electric aircraft. The Journal of Engineering, 2019(17), 3474-3478. View this article in WRRO
- Investigation on Contribution of Inductance Harmonics to Torque Production in Multiphase Doubly Salient Synchronous Reluctance Machines. IEEE Transactions on Magnetics, 55(4). View this article in WRRO
- Comparative Studies of Torque Performance Improvement for Different Doubly Salient Synchronous Reluctance Machines by Current Harmonic Injection. IEEE Transactions on Energy Conversion. View this article in WRRO
- Quantitative Analysis of Contribution of Air-Gap Field Harmonics to Torque Production in Three-Phase 12-Slot/8-Pole Doubly Salient Synchronous Reluctance Machines. IEEE Transactions on Magnetics, 54(9). View this article in WRRO
- Recent development of reluctance machines with different winding configurations, excitation methods, and machine structures. China Electrotechnical Society Transactions on Electrical Machines and Systems, 2(1), 82-92. View this article in WRRO
- Novel Modular Switched Reluctance Machines for Performance Improvement. IEEE Transactions on Energy Conversion, 33(3), 1255-1265. View this article in WRRO
- Investigation on Synchronous Reluctance Machines with Different Rotor Topologies and Winding Configurations. IET Electric Power Applications. View this article in WRRO
- Influence of Conduction Angles on Single-Layer Switched Reluctance Machines. IEEE Transactions on Magnetics, 52(12). View this article in WRRO
- Comparative Study of Torque Production in Conventional and Mutually Coupled SRMs Using Frozen Permeability. IEEE Transactions on Magnetics, 52(6). View this article in WRRO
- Performance Comparison of Doubly Salient Reluctance Machine Topologies Supplied by Sinewave Currents. IEEE Transactions on Industrial Electronics, 63(7), 4086-4096. View this article in WRRO
- View this article in WRRO
- Performance investigation of hybrid excited switched flux permanent magnet machines using frozen permeability method. IET Electric Power Applications, 9(9), 586-594. View this article in WRRO
- Model Specific Characterization of Soft Magnetic Materials for Core Loss Prediction in Electrical Machines. IEEE Transactions on Magnetics, 50(11), 1-4.
- Comparison of flux switching and surface mounted permanent magnet generators for high-speed applications. IET Electrical Systems in Transportation, 1(3), 111-116.
- Hybrid-excited flux-switching permanent-magnet machines with iron flux bridges. IEEE Transactions on Magnetics, 46(6), 1726-1729.
- Optimal split ratio in fractional-slot interior permanent-magnet machines with non-overlapping windings. IEEE Transactions on Magnetics, 46(5), 1235-1242.
- Alternate poles wound flux-switching permanent-magnet brushless AC machines. IEEE Transactions on Industry Applications, 46(2), 790-797.
- Analytical modeling and finite-element computation of radial vibration force in fractional-slot permanent-magnet brushless machines. IEEE Transactions on Industry Applications, 46(5), 1908-1918.
- Enhanced optimal torque control of fault-tolerant PM machine under flux-weakening operation. IEEE Transactions on Industrial Electronics, 57(1), 344-353.
- Multiphase flux-switching permanent-magnet brushless machine for aerospace application. IEEE Transactions on Industry Applications, 45(6), 1971-1981.
- Cogging torque in flux-switching permanent magnet machines. IEEE Transactions on Magnetics, 45(10), 4708-4711.
- Proximity loss study in high speed flux-switching permanent magnet machine. IEEE Transactions on Magnetics, 45(10), 4748-4751.
- Variable-airgap, cylindrical, linear variable reluctance actuators for high-force, medium-stroke applications. IET Electric Power Applications, 3(4), 352-362.
- An online winding fault detection technique for fault-tolerant PM machines. International Journal of Systems Science, 40(3), 289-296.
- Analytical prediction of the short-circuit current in fault-tolerant permanent-magnet machines. IEEE Transactions on Industrial Electronics, 55(12), 4210-4217.
- Testing of a 250-kilowatt fault-tolerant permanent magnet power generation system for aeroengines. Journal of Propulsion and Power, 24(2), 330-335.
- High temperature permanent magnet actuator for fail-safe applications. IEEJ Transactions on Industry Applications, 128(10).
- Effect of axial segmentation of permanent magnets on rotor loss in modular permanent-magnet brushless machines. IEEE Transactions on Industry Applications, 43(5), 1207-1213.
- Static performance of a polarized permanent-magnet reluctance actuator for internal combustion engine valve actuation. IEEE Transactions on Magnetics, 42(8), 2063-2070.
- Full-field pulsed magnetophotoelasticity - experimental implementation. Journal of Strain Analysis for Engineering Design, 41(2), 171-182. View this article in WRRO
- Full-field pulsed magnetophotoelasticity - a description of the instrument. Journal of Strain Analysis for Engineering Design, 41(2), 161-170. View this article in WRRO
- Prediction and measurement of core losses in a high-speed switched-reluctance machine. IEEE Transactions on Magnetics, 41(11), 4288-4298.
- Design of a miniature permanent-magnet generator and energy storage system. IEEE Transactions on Industrial Electronics, 52(5), 1383-1390. View this article in WRRO
- Enhancing the force capability of permanent magnet latching actuators for electromechanical valve actuation systems. Journal of Applied Physics, 97(10).
- Design features for enhancing the performance of electromagnetic valve actuation systems. IEEE Transactions on Magnetics, 41(3), 1163-1168.
- Iron loss in a modular rotor switched reluctance machine for the 'more-electric' aero-engine. INTERMAG ASIA 2005: Digests of the IEEE International Magnetics Conference, 42.
- An evaluation of alternative stator lamination materials for a high-speed, 1.5 MW, permanent magnet generator. IEEE Transactions on Magnetics, 40(4 II), 2041-2043.
- Analysis and design optimization of an improved axially magnetized tubular permanent-magnet machine. IEEE Transactions on Energy Conversion, 19(2), 289-295. View this article in WRRO
- Electromagnetic design optimization of a powder aligning fixture for a compression-molded anisotropie NdFeB ring magnet. IEEE Transactions on Magnetics, 40(3), 1702-1707.
- A spherical permanent magnet actuator for a high-fidelity force-feedback joystick. Mechatronics, 14(3), 327-339.
- Design and control of a novel spherical permanent magnet actuator with three degrees of freedom. IEEE/ASME Transactions on Mechatronics, 8(4), 457-468.
- Fringing in tubular permanent-magnet machines: Part I. Magnetic field distribution, flux linkage, and thrust force. IEEE Transactions on Magnetics, 39(6), 3507-3516.
- Fringing in tubular permanent-magnet machines: Part II. Cogging force and its minimization. IEEE Transactions on Magnetics, 39(6), 3517-3522. View this article in WRRO
- Comparison of Halbach magnetized brushless motors equipped with air-cored and iron-cored rotors. Journal of Applied Physics, 93(10), 8692-8694.
- Dynamic modeling of tubular moving-magnet linear actuators. Journal of Applied Physics, 93(10), 8787-8789.
- Rotor topologies for a switched-reluctance machine for the 'more-electric' aircraft engine. IEE Proceedings: Electric Power Applications, 150(3), 311-318.
- Calculation of centrifugal stress in four-pole switched-reluctance rotors. IEE Proceedings: Electric Power Applications, 150(1), 97-105.
- Influence of an aperture on the performance of a two-degree-of-freedom iron-coded spherical permanent-magnet actuator. IEEE Transactions on Magnetics, 38(6), 3650-3653.
- Transient performance of a short-stroke linear solenoid actuator. IEE Proceedings - Electric Power Applications, 149(5), 379-384.
- Tailoring force-displacement characteristics in medium-stroke linear variable reluctance actuators. IEEE Transactions on Magnetics, 38(5), 3267-3269.
- A low-power, linear, permanent-magnet generator/energy storage system. IEEE Transactions on Industrial Electronics, 49(3), 640-648. View this article in WRRO
- Design of powder aligning systems for the compression molding of radially anisotropic permanent magnet rings. Journal of Applied Physics, 91(10), 8837-8839.
- Design optimisation and comparison of tubular permanent magnet machine topologies. IEE Proceedings: Electric Power Applications, 148(5), 456-464.
- Aerodynamic losses in switched reluctance machines. IEE Proceedings: Electric Power Applications, 147(6), 443-448.
- Analysis of anisotropic bonded NdFeB Halbach cylinders accounting for partial powder alignment. IEEE Transactions on Magnetics, 36(5), 3575-3577. View this article in WRRO
- Powder alignment system for anisotropic bonded NdFeB Halbach cylinders. IEEE Transactions on Magnetics, 36(5), 3349-3352. View this article in WRRO
- Short-stroke, bidirectional linear actuator for high temperature applications. IEE Proceedings: Electric Power Applications, 147(3), 175-180.
- View this article in WRRO
- Design of a high speed switched reluctance machine for automotive turbo-generator applications. SAE Technical Papers.
- Design and experimental characterisation of a linear reciprocating generator. IEE Proceedings: Electric Power Applications, 145(6), 509-518.
- The design and analysis of axial field multipole impulse magnetizing fixtures. Journal of Applied Physics, 83(11), 7112-7114.
- A novel spherical permanent magnet actuator with three degrees-of-freedom. IEEE Transactions on Magnetics, 34(4(1)), 2075-2077.
- Analysis, design and control of a novel spherical permanent-magnet actuator. IEE Proceedings: Electric Power Applications, 145(1), 61-71.
- A novel spherical actuator: Design and control. IEEE Transactions on Magnetics, 33(5(2)), 4209-4211. View this article in WRRO
- Design considerations for permanent magnet polarized electromagnetically actuated brakes. IEEE Transactions on Magnetics, 31(6(2)), 3743-3745.
- An accurate pulsed field hystersograph. Physica B: Physics of Condensed Matter, 211(1-4), 348-350.
- Design, analysis, and simulation of impulse magnetization systems based on solenoid magnetizing fixtures. COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, 11(1), 225-228.
- Simulation of Capacitor Discharge Magnetisation. IEEE Transactions on Magnetics, 26(5), 1638-1640.
Chapters
- Rare-earth magnets: Properties, processing and applications, Functional Materials for Sustainable Energy Applications (pp. 600-639).
- Rare-earth magnets: properties, processing and applications, Functional Materials for Sustainable Energy Applications (pp. 600-639). Elsevier
- Contributor contact details, Functional Materials for Sustainable Energy Applications (pp. xiii-xvii). Elsevier
Conference proceedings papers
- Dynamic Performance Investigation of Doubly Salient Synchronous Reluctance Machines with Current Harmonic Injection. 2019 22nd International Conference on Electrical Machines and Systems (ICEMS), 11 August 2019 - 14 August 2019.
- Losses in Different Doubly Salient Synchronous Reluctance Machines with Current Harmonic Injection. 2019 22nd International Conference on Electrical Machines and Systems (ICEMS), 11 August 2019 - 14 August 2019.
- Comparison of Magnetically Geared and Surface-mounted PM machines - Influence of Machine Size and Current Density. 2019 22nd International Conference on Electrical Machines and Systems (ICEMS), 11 August 2019 - 14 August 2019.
- Torque Performance Improvement of Doubly Salient Synchronous Reluctance Machines by Current Harmonic Injection. 2019 IEEE International Electric Machines & Drives Conference (IEMDC), 12 May 2019 - 15 May 2019.
- Modelling of dynamic machine behavior in peripheral milling operations. 2017 IEEE International Electric Machines and Drives Conference (IEMDC), 21 May 2017 - 24 May 2017.
- Cogging torque reduction in hybrid-excited axial field flux-switching fault-tolerant machines. 2017 IEEE International Electric Machines and Drives Conference (IEMDC), 21 May 2017 - 24 May 2017.
- Comparative study of short-pitched and fully-pitched SRMs supplied by sine wave currents. 2015 IEEE International Conference on Industrial Technology (ICIT), 17 March 2015 - 19 March 2015.
- Effects of load conditions on rotor eddy current loss in modular permanent magnet machines. IEEE International Electric Machines and Drives Conference, IEMDC 2011 (pp 1328-1333)
- Comparison of radial vibration forces in 10-pole/12-slot fractional-slot surface-mounted and interior PM brushless AC machines. 19th International Conference on Electrical Machines, ICEM 2010
- Comparison of flux switching and surface mounted permanent magnet generators for aerospace applications. IET Conference Publications, Vol. 2010(563 CP)
- Influence of slot and pole number combination on radial force and vibration modes in fractional slot PM brushless machines having single- and double-layer windings. IEEE Energy Conversion Congress and Exposition, ECCE 2009 (pp 3443-3450)
- Optimal split ratio in fractional-slot interior permanent magnet machines with non-overlapping windings. IEEE International Electric Machines and Drives Conference, IEMDC '09 (pp 1721-1728)
- Analytical modelling and finite element computation of radial vibration force in fractional-slot permanent magnet brushless machines. 2009 IEEE International Electric Machines and Drives Conference, IEMDC '09, Vol. 1-3 (pp 144-151)
- Enhanced optimal torque control of fault-tolerant PM machine under flux weakening operation. Proceedings of the 2008 International Conference on Electrical Machines, ICEM'08, Vol. 1-4 (pp 1608-1613)
- Analysis of switching loss of an AC fed direct converter for a switched reluctance machine. Proceedings of the 2008 International Conference on Electrical Machines, ICEM'08, Vol. 1-4 (pp 1931-1936)
- Fault-tolerant flux-switching permanent magnet brushless AC machines. Conference Record - IAS Annual Meeting (IEEE Industry Applications Society), Vol. 1-5 (pp 1965-1972)
- Multi-phase flux-switching permanent magnet brushless machine for aerospace application. Conference Record - IAS Annual Meeting (IEEE Industry Applications Society), Vol. 1-5 (pp 1949-1956)
- Experimental testing of a 250 kW fault-tolerant permanent magnet power generation system for large civil aero-engines. Collection of Technical Papers - 5th International Energy Conversion Engineering Conference, Vol. 2 (pp 1076-1083)
- Thermal modeling of flooded rotor electrical machines for electro-hydrostatic actuators. Proceedings of IEEE International Electric Machines and Drives Conference, IEMDC 2007, Vol. 2 (pp 1632-1637)
- Analysis of an AC fed direct converter for a switched reluctance machine in aerospace applications. Conference Proceedings - IPEMC 2006: CES/IEEE 5th International Power Electronics and Motion Control Conference, Vol. 2 (pp 977-982)
- Analysis of an AC fed direct converter for a switched reluctance machine in aerospace applications. 2006 CES/IEEE 5th International Power Electronics and Motion Control Conference, 14 August 2006 - 16 August 2006.
- Current ripple minimisation in switched reluctance (SR) machines for aerospace applications. INTERMAG 2006 - IEEE International Magnetics Conference (pp 768)
- Iron loss in a modular rotor switched reluctance machine for the "more-electric" aero-engine. IEEE Transactions on Magnetics, Vol. 41(10) (pp 3934-3936)
- Iron loss in a modular rotor switched reluctance machine for the 'more-electric' aero-engine. INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005., 4 April 2005 - 8 April 2005.
- Design of a 250kW, fault-tolerant PM generator for the more-electric aircraft. Collection of Technical Papers - 3rd International Energy Conversion Engineering Conference, Vol. 2 (pp 1173-1182)
- An investigation into the corrosion behaviour of Zn coated NdFeB powder. INTERMAG Europe 2002 - IEEE International Magnetics Conference
- The influence of magnetization pattern on the performance of a cylindrical moving-magnet linear actuator. IEEE Transactions on Magnetics, Vol. 36(5) (pp 3571-3574)
- View this article in WRRO
- Tailoring force-stroke characteristics in medium-stroke linear reluctance actuators. IEEE International Digest of Technical Papers on Magnetics Conference
- The Design and analysis of axial field multipole impulse magnetizing fixtures. 7th Joint MMM-Intermag Conference. Abstracts (Cat. No.98CH36275)
- Analysis of a Novel Spherical Permanent Magnet Actuator with Three Degrees-of-Freedom. 7th Joint MMM-Intermag Conference. Abstracts (Cat. No.98CH36275)
- A Novel Spherical Actuator Design And Control. 1997 IEEE International Magnetics Conference (INTERMAG'97)
- A method for assessing eddy current effects in pulsed magnetometry. 1992. Digests of Intermag. International Magnetics Conference
- The computer-aided design of magnetizing fixtures for the post-assembly magnetization of rare-earth permanent brushless DC motors. 1992. Digests of Intermag. International Magnetics Conference
- Professional activities
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- Rolls-Royce University Technology Centre in Advanced Electrical Machines
- Research students
I have supervised ~20 PhD students to completion across a wide range of electromagnetic and electro-mechanical topics.
Student
Degree Status Primary/Secondary Balachandran B PhD Graduated Primary Duke A PhD Graduated Primary Forrest S J PhD Graduated Primary Menon K G PhD Graduated Primary Nie C PhD Graduated Primary Pan Q PhD Graduated Primary Rodrigues L K PhD Graduated Primary Shortte M O P PhD Graduated Primary Alwash M A M PhD Graduated Secondary Azar Z PhD Graduated Secondary Chu W PhD Graduated Secondary Conway A R PhD Graduated Secondary Gladwin D T PhD Graduated Secondary Guan Y PhD Graduated Secondary Lee B PhD Graduated Secondary Ma Xiyun PhD Graduated Secondary Owen R L PhD Graduated Secondary Ren Y PhD Graduated Secondary Rogers D J PhD Graduated Secondary Suppharangsan W PhD Graduated Secondary Thomas A S PhD Graduated Secondary Wu Z PhD Graduated Secondary Xue S PhD Graduated Secondary Zheng M PhD Graduated Secondary