Christopher Spargo | Newcastle University (original) (raw)
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Papers by Christopher Spargo
IEEE Transactions on Energy Conversion, 2015
ABSTRACT
http://eprint.ncl.ac.uk 2014-EMC-0125.R2 -SUBMISSION 15/07/2014 Abstract-This paper presents an... more http://eprint.ncl.ac.uk 2014-EMC-0125.R2 -SUBMISSION 15/07/2014 Abstract-This paper presents an investigation into the application of fractional slot-concentrated windings (FSCW) to synchronous reluctance motors (SynRM). The advantages and disadvantages of the synthesis of such a machine are explored with thermal aspects included and a comparison with a similar topology, the switched reluctance motor (SRM) is also presented where appropriate. The differences in electric drive between the two reluctance motors are briefly explored. Finite element studies show that the fractional slot-concentrated wound machine can exhibit a higher efficiency and torque density when compared to conventional synchronous reluctance and the induction motor and the electromagnetic model is validated through testing of a prototype machine with thermal results also reported. Despite the many benefits, high torque ripple and low power factor reduce the topologies desirability and are identified as an area of further research.
2014 International Conference on Electrical Machines (ICEM), 2014
A novel finite element solution post-processing technique to determine the effects of rotor skewi... more A novel finite element solution post-processing technique to determine the effects of rotor skewing is presented in this paper. It was previously proposed that a post-processing semi-numerical method to calculate the harmonic torque components in synchronous machines is useful to machine designers. Harmonic Maxwellian stress components create parasitic effects during machine operation such as torque ripple, which is extremely undesirable in many applications and is a major cause of acoustic noise and vibration which can limit the machine's application. Rotor skewing usually allows reduction of this torque ripple and this paper expands previous work to include a good approximation of skewing effects using a single 2D time stepping Finite Element (FE) study with the developed post-processing method. The method reduces computation time for skew effect calculation where a large 3D FE simulation would usually be required.
7th IET International Conference on Power Electronics, Machines and Drives (PEMD 2014), 2014
This paper presents an examination of the advantages, disadvantages and remaining challenges of t... more This paper presents an examination of the advantages, disadvantages and remaining challenges of the application of fractional slot concentrated windings to higher pole number (pole-pairs > 2) synchronous reluctance machines. It extends previous work by assessing the effects of the available slotpole combinations on machine performance and construction. Finite element studies and figures of merit derived from d-q axis theory are used to compare and assess performance. Manufacturing and constructional issues are also discussed.
IEEE Transactions on Industry Applications, 2015
Abstract-This paper presents an investigation into the application of fractional slot-concentra... more Abstract-This paper presents an investigation into the application of fractional slot-concentrated windings (FSCW) to synchronous reluctance motors (SynRM). The advantages and disadvantages of the synthesis of such a machine are explored with thermal aspects included and a comparison with a similar topology, the switched reluctance motor (SRM) is also presented where appropriate. The differences in electric drive between the two reluctance motors are briefly explored. Finite element studies show that the fractional slot-concentrated wound machine can exhibit a higher efficiency and torque density when compared to conventional synchronous reluctance and the induction motor and the electromagnetic model is validated through testing of a prototype machine with thermal results also reported. Despite the many benefits, high torque ripple and low power factor reduce the topologies desirability and are identified as an area of further research.
2012 XXth International Conference on Electrical Machines, 2012
Abstract -Winding configurations are investigated for a six phase, 12-10 switched reluctance ma... more Abstract -Winding configurations are investigated for a six phase, 12-10 switched reluctance machine having single tooth wound coils and being driven from a conventional three phase full bridge converter with the addition of six diodes. A new winding configuration is proposed and shown to develop more torque with less torque ripple than a conventional winding in this application. Finite element modelling is used to investigate the electromagnetic behaviour and compare the performance of different winding configurations. Initial experimental tests are described in verification of the modelling. The novel drive and new winding configuration offer significant advantages over a standard three phase machine and drive, giving increased mean torque with lower torque ripple and acoustic noise, as well as reduced converter complexity and potentially cost.
6th IET International Conference on Power Electronics, Machines and Drives (PEMD 2012), 2012
This paper explores how the use of a modified full bridge converter, coupled to a 6 phase switche... more This paper explores how the use of a modified full bridge converter, coupled to a 6 phase switched reluctance motor, can produce a torque dense drive with low torque ripple, combined with standard drive electronics and a good converter VA rating. A description is provided of the new drive configuration: a prototype motor and drive are constructed and test results provided. Results are compared with those to be expected from the same switched reluctance machine driven from a conventional, asymmetric half bridge converter.
Materials Science Forum, 2012
ABSTRACT We show that it is possible to obtain information relating to deep level interface traps... more ABSTRACT We show that it is possible to obtain information relating to deep level interface traps, or so called 'slow states', by using the photo-CV characterisation method. Sub-bandgap illumination has been chosen in order to avoid band-to-band excitation for the creation of minority carriers. This enables information to be extracted from trapping states at the SiO2/SiC interface that are energetically deep within the band gap. Empirical observations of deep level trapping states with life times in the order of tens of hours are reported and the interface trap density as a function of energy has been extracted using the Terman method. Characterisation of these interface states will aid the development of new fabrication processes, with the aim of reducing the interface trap density to the same level as that of the SiO2/Si interface and facilitating the production of higher quality SiC based devices.
IET Electrical Systems in Transportation, 2014
ABSTRACT Over the last 20 years, conventional automotive engine ancillaries have migrated from be... more ABSTRACT Over the last 20 years, conventional automotive engine ancillaries have migrated from being mechanically powered to electrically powered in order to meet market demand. To adopt this trend in heavy trucks requires a higher power electrical system in order to cope with the higher loads placed upon it. Until the advent of the hybrid electric heavy truck (HET) this power infrastructure has not been available. HET??s require a higher voltage system in order to reduce losses and provide adequate power and voltage levels for the traction motor. This study investigates for the first time the benefit of electrifying a hydraulic power assisted steering system in an HET. The developed electrical hydraulic power steering (EHPS), using a high-voltage traction battery, is found to drastically reduce the consumed energy over a drive cycle by optimal operation of the pump over the driving cycle. Empirical data from a prototype HET with EHPS confirms the simulation results from Dymola.
IEEE Transactions on Energy Conversion, 2015
ABSTRACT
2014 IEEE Energy Conversion Congress and Exposition (ECCE), 2014
2014 IEEE Energy Conversion Congress and Exposition (ECCE), 2014
IEEE Transactions on Magnetics, 2000
ABSTRACT A novel method to calculate the harmonic torque components in synchronous machines is pr... more ABSTRACT A novel method to calculate the harmonic torque components in synchronous machines is presented. Harmonic torque components create a torque ripple, which is undesirable in many applications. This torque ripple is a major cause of acoustic noise and vibration and can limit the machine's application range. A seminumerical method is developed to calculate and analyze harmonic torque components based on Maxwell stress tensor theory. Development of the Maxwell stress expressions leads to a simple algebraic expression for the calculation. Finite-element (FE) analysis is used to determine the equation variables. It is shown that postprocessing of the FE solution provides valuable information regarding the composition of the torque waveform, based upon field harmonics, which was previously unavailable. A deeper insight can be gained into more direct electromagnetic design changes to reduce torque ripple in synchronous machines, improving their torque quality. As an example, the developed method is applied to a synchronous reluctance machine with fractional slot concentrated windings that is known to exhibit high torque ripple.
IEEE Transactions on Energy Conversion, 2000
ABSTRACT This paper reports a propulsion motor for a solar-powered aircraft. The motor uses preco... more ABSTRACT This paper reports a propulsion motor for a solar-powered aircraft. The motor uses precompressed aluminum stator windings, with a fill factor of greater than 75%, in a permanent magnet synchronous machine. The motor performance is compared empirically to an identical machine with conventionally wound copper windings. It is shown that there are many advantages to using compressed aluminum windings in terms of weight reduction, thermal improvement, and lower cost, for the same loss and electromagnetic performance, provided a sufficiently high slot fill factor can be achieved. The design and manufacture of the compressed coils is also discussed. A modular stator arrangement is used, in the form of a solid coreback with keyed teeth to allow easy assembly of the compressed windings. It is noted that the electromagnetic performance of the machine is unaffected by the modular nature of the magnetic core. Two prototype motors, one wound with conventional copper and the other with precompressed aluminum windings, are constructed and tested.
IEEE Transactions on Energy Conversion, 2015
ABSTRACT
http://eprint.ncl.ac.uk 2014-EMC-0125.R2 -SUBMISSION 15/07/2014 Abstract-This paper presents an... more http://eprint.ncl.ac.uk 2014-EMC-0125.R2 -SUBMISSION 15/07/2014 Abstract-This paper presents an investigation into the application of fractional slot-concentrated windings (FSCW) to synchronous reluctance motors (SynRM). The advantages and disadvantages of the synthesis of such a machine are explored with thermal aspects included and a comparison with a similar topology, the switched reluctance motor (SRM) is also presented where appropriate. The differences in electric drive between the two reluctance motors are briefly explored. Finite element studies show that the fractional slot-concentrated wound machine can exhibit a higher efficiency and torque density when compared to conventional synchronous reluctance and the induction motor and the electromagnetic model is validated through testing of a prototype machine with thermal results also reported. Despite the many benefits, high torque ripple and low power factor reduce the topologies desirability and are identified as an area of further research.
2014 International Conference on Electrical Machines (ICEM), 2014
A novel finite element solution post-processing technique to determine the effects of rotor skewi... more A novel finite element solution post-processing technique to determine the effects of rotor skewing is presented in this paper. It was previously proposed that a post-processing semi-numerical method to calculate the harmonic torque components in synchronous machines is useful to machine designers. Harmonic Maxwellian stress components create parasitic effects during machine operation such as torque ripple, which is extremely undesirable in many applications and is a major cause of acoustic noise and vibration which can limit the machine's application. Rotor skewing usually allows reduction of this torque ripple and this paper expands previous work to include a good approximation of skewing effects using a single 2D time stepping Finite Element (FE) study with the developed post-processing method. The method reduces computation time for skew effect calculation where a large 3D FE simulation would usually be required.
7th IET International Conference on Power Electronics, Machines and Drives (PEMD 2014), 2014
This paper presents an examination of the advantages, disadvantages and remaining challenges of t... more This paper presents an examination of the advantages, disadvantages and remaining challenges of the application of fractional slot concentrated windings to higher pole number (pole-pairs > 2) synchronous reluctance machines. It extends previous work by assessing the effects of the available slotpole combinations on machine performance and construction. Finite element studies and figures of merit derived from d-q axis theory are used to compare and assess performance. Manufacturing and constructional issues are also discussed.
IEEE Transactions on Industry Applications, 2015
Abstract-This paper presents an investigation into the application of fractional slot-concentra... more Abstract-This paper presents an investigation into the application of fractional slot-concentrated windings (FSCW) to synchronous reluctance motors (SynRM). The advantages and disadvantages of the synthesis of such a machine are explored with thermal aspects included and a comparison with a similar topology, the switched reluctance motor (SRM) is also presented where appropriate. The differences in electric drive between the two reluctance motors are briefly explored. Finite element studies show that the fractional slot-concentrated wound machine can exhibit a higher efficiency and torque density when compared to conventional synchronous reluctance and the induction motor and the electromagnetic model is validated through testing of a prototype machine with thermal results also reported. Despite the many benefits, high torque ripple and low power factor reduce the topologies desirability and are identified as an area of further research.
2012 XXth International Conference on Electrical Machines, 2012
Abstract -Winding configurations are investigated for a six phase, 12-10 switched reluctance ma... more Abstract -Winding configurations are investigated for a six phase, 12-10 switched reluctance machine having single tooth wound coils and being driven from a conventional three phase full bridge converter with the addition of six diodes. A new winding configuration is proposed and shown to develop more torque with less torque ripple than a conventional winding in this application. Finite element modelling is used to investigate the electromagnetic behaviour and compare the performance of different winding configurations. Initial experimental tests are described in verification of the modelling. The novel drive and new winding configuration offer significant advantages over a standard three phase machine and drive, giving increased mean torque with lower torque ripple and acoustic noise, as well as reduced converter complexity and potentially cost.
6th IET International Conference on Power Electronics, Machines and Drives (PEMD 2012), 2012
This paper explores how the use of a modified full bridge converter, coupled to a 6 phase switche... more This paper explores how the use of a modified full bridge converter, coupled to a 6 phase switched reluctance motor, can produce a torque dense drive with low torque ripple, combined with standard drive electronics and a good converter VA rating. A description is provided of the new drive configuration: a prototype motor and drive are constructed and test results provided. Results are compared with those to be expected from the same switched reluctance machine driven from a conventional, asymmetric half bridge converter.
Materials Science Forum, 2012
ABSTRACT We show that it is possible to obtain information relating to deep level interface traps... more ABSTRACT We show that it is possible to obtain information relating to deep level interface traps, or so called 'slow states', by using the photo-CV characterisation method. Sub-bandgap illumination has been chosen in order to avoid band-to-band excitation for the creation of minority carriers. This enables information to be extracted from trapping states at the SiO2/SiC interface that are energetically deep within the band gap. Empirical observations of deep level trapping states with life times in the order of tens of hours are reported and the interface trap density as a function of energy has been extracted using the Terman method. Characterisation of these interface states will aid the development of new fabrication processes, with the aim of reducing the interface trap density to the same level as that of the SiO2/Si interface and facilitating the production of higher quality SiC based devices.
IET Electrical Systems in Transportation, 2014
ABSTRACT Over the last 20 years, conventional automotive engine ancillaries have migrated from be... more ABSTRACT Over the last 20 years, conventional automotive engine ancillaries have migrated from being mechanically powered to electrically powered in order to meet market demand. To adopt this trend in heavy trucks requires a higher power electrical system in order to cope with the higher loads placed upon it. Until the advent of the hybrid electric heavy truck (HET) this power infrastructure has not been available. HET??s require a higher voltage system in order to reduce losses and provide adequate power and voltage levels for the traction motor. This study investigates for the first time the benefit of electrifying a hydraulic power assisted steering system in an HET. The developed electrical hydraulic power steering (EHPS), using a high-voltage traction battery, is found to drastically reduce the consumed energy over a drive cycle by optimal operation of the pump over the driving cycle. Empirical data from a prototype HET with EHPS confirms the simulation results from Dymola.
IEEE Transactions on Energy Conversion, 2015
ABSTRACT
2014 IEEE Energy Conversion Congress and Exposition (ECCE), 2014
2014 IEEE Energy Conversion Congress and Exposition (ECCE), 2014
IEEE Transactions on Magnetics, 2000
ABSTRACT A novel method to calculate the harmonic torque components in synchronous machines is pr... more ABSTRACT A novel method to calculate the harmonic torque components in synchronous machines is presented. Harmonic torque components create a torque ripple, which is undesirable in many applications. This torque ripple is a major cause of acoustic noise and vibration and can limit the machine's application range. A seminumerical method is developed to calculate and analyze harmonic torque components based on Maxwell stress tensor theory. Development of the Maxwell stress expressions leads to a simple algebraic expression for the calculation. Finite-element (FE) analysis is used to determine the equation variables. It is shown that postprocessing of the FE solution provides valuable information regarding the composition of the torque waveform, based upon field harmonics, which was previously unavailable. A deeper insight can be gained into more direct electromagnetic design changes to reduce torque ripple in synchronous machines, improving their torque quality. As an example, the developed method is applied to a synchronous reluctance machine with fractional slot concentrated windings that is known to exhibit high torque ripple.
IEEE Transactions on Energy Conversion, 2000
ABSTRACT This paper reports a propulsion motor for a solar-powered aircraft. The motor uses preco... more ABSTRACT This paper reports a propulsion motor for a solar-powered aircraft. The motor uses precompressed aluminum stator windings, with a fill factor of greater than 75%, in a permanent magnet synchronous machine. The motor performance is compared empirically to an identical machine with conventionally wound copper windings. It is shown that there are many advantages to using compressed aluminum windings in terms of weight reduction, thermal improvement, and lower cost, for the same loss and electromagnetic performance, provided a sufficiently high slot fill factor can be achieved. The design and manufacture of the compressed coils is also discussed. A modular stator arrangement is used, in the form of a solid coreback with keyed teeth to allow easy assembly of the compressed windings. It is noted that the electromagnetic performance of the machine is unaffected by the modular nature of the magnetic core. Two prototype motors, one wound with conventional copper and the other with precompressed aluminum windings, are constructed and tested.