Please refer to published version for the most recent bibliographic citation information. If a pu... more Please refer to published version for the most recent bibliographic citation information. If a published version is known of, the repository item page linked to above, will contain details on accessing it.
2021 IEEE Energy Conversion Congress and Exposition (ECCE), 2021
Please refer to published version for the most recent bibliographic citation information. If a pu... more Please refer to published version for the most recent bibliographic citation information. If a published version is known of, the repository item page linked to above, will contain details on accessing it.
An investigation of temperature sensitive electrical parameters for SiC power MOSFETs. IEEE Trans... more An investigation of temperature sensitive electrical parameters for SiC power MOSFETs. IEEE Transactions on Power Electronics.
2014 IEEE Energy Conversion Congress and Exposition (ECCE), 2014
Schottky diodes are known to have lower conduction and switching losses compared to PiN diodes, h... more Schottky diodes are known to have lower conduction and switching losses compared to PiN diodes, however, are prone to ringing in the output characteristics. In this paper, analytical models have been developed to calculate the turn-off switching energy of SiC Schottky and silicon PiN diodes. The models account for the reverse recovery current and diode voltage overshoot in the case of the PiN diode as well as the output oscillations for the Schottky diodes. PiN diodes during turn-off exhibit significant reverse current which increases with the switching rate and temperature whereas Schottky diodes exhibit output oscillations due to RLC resonance in the circuit. By combining these models with thermal networks derived from transient thermal impedance curves of the diodes, a fast and accurate method of predicting the temperature transient for different switching frequencies and electrical time constants has been developed. These models can be used by application engineers to predict the energy dissipation when designing converters and can take account of temperature and switching rate dependencies of the diodes.
Integration of distributed generation (DG) such as photovoltaics (PV) represents a challenge for ... more Integration of distributed generation (DG) such as photovoltaics (PV) represents a challenge for the traditional operation of distribution power systems. As the installed power of DGs grows, grid codes are being modified to involve DGs in the provision of ancillary services. This includes the ability to ride-through large disturbances. In this paper, the behavior of a single-stage PV system under unbalanced voltage conditions is studied, and a fault ride-through control scheme is proposed which is able to support the grid through the injection of reactive power. Furthermore, adjustable power quality is enabled as a trade-off between power ripple and current harmonics. The control scheme makes use of a current controller based on the space vector Fourier transform concept. No rotational transformation is required, and zero steady-state error is ensured when tracking distorted current references. The controller was tested in detailed PSCAD/EMTDC computer simulations, and implemented in a real grid-connected PV system to demonstrate its performance under unbalanced voltage conditions.
Thermal coupling analysis for a multi-chip paralleled IGBT module in a doubly fed wind turbine po... more Thermal coupling analysis for a multi-chip paralleled IGBT module in a doubly fed wind turbine power converter. IEEE Transactions on Energy Conversion .
Please refer to published version for the most recent bibliographic citation information. If a pu... more Please refer to published version for the most recent bibliographic citation information. If a published version is known of, the repository item page linked to above, will contain details on accessing it.
The version presented here may differ from the published version or, version of record, if you wi... more The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP URL' above for details on accessing the published version and note that access may require a subscription.
16th International Conference and Exhibition on Electricity Distribution (CIRED 2001), 2001
Metal oxide varistors are widely used in many power electronics circuits to protect against trans... more Metal oxide varistors are widely used in many power electronics circuits to protect against transient over voltages. Certain applications are very demanding on the energy handling capability of the varistors. This paper gives an overview of the failure modes of ZnO varistors and investigates their characteristics when subjected to repetitive current pulses. It describes the puncture failure mode caused by melting of a region in the varistor of local current concentration. Experimental tests are performed to evaluate the puncture energy using an infrared imaging camera. A relationship between the energy absorption and the varistor maximum surface temperature is obtained. It is shown that the destructive energy depends strongly on the uniformity of the varistor; the more uniform, the higher the energy handling capability. The paper also presents the results of nondestructive tests using a scanning acoustic microscope to evaluate the uniformity of the varistor.
This paper illustrates an effect of sampling in an encoderless vector-controlled induction motor ... more This paper illustrates an effect of sampling in an encoderless vector-controlled induction motor drive with a digital controller. The analysis focuses on the speed observer and the speed control loop which is executed at discrete instants. It is shown that the estimated speed can fluctuate between samples in the speed loop and cause a sustained resonance via feedback. The shaft inertia is not available to smooth the ripple of the estimated speed and the associated resonance could adversely affect the inverter and machine. An analytical model is proposed to evaluate the risk of such a condition in the design and on-site adjustment of control gains. The requirement for a smoothing filter in the speed loop is identified.
This paper describes the design build and test of a linear test rig for demonstrating novel topol... more This paper describes the design build and test of a linear test rig for demonstrating novel topology linear machines. The work is aimed at aiding the developments of power take off for wave and tidal energy converters. The rig consists of three parts: prime mover, test machine and converter. Experience and method for the design manufacture and initial testing of each of these components is detailed. AUTHORS' BIOGRAPHIES Dr Baker has a mechanical engineering degree from Birmingham and a PhD in electrical aspects of wave energy conversion from Durham. He is currently an engineering lecturer within the Lancaster University Renewable Energy Group, pursuing research in power capture and control of wave energy devices and the economic capture of low head hydro power.
The thermomechanical reliability of SiC power devices and modules is increasingly becoming of int... more The thermomechanical reliability of SiC power devices and modules is increasingly becoming of interest especially for high power applications where power cycling performance is critical. Press-pack assemblies are a trusted and reliable packaging solution that has traditionally been used for high power thyristorbased applications in FACTS/HVDC, although press-pack IGBTs have become commercially available more recently. These press-pack IGBTs require anti-parallel PiN diodes for enabling reverse conduction capability. In these high power applications, paralleling chips for high current conduction capability is a requirement, hence, electrothermal stability during current sharing is critical. SiC Schottky diodes not only exhibit the advantages of wide bandgap technology compared to silicon PiN diodes, but they have significantly lower zero temperature coefficient (ZTC) meaning they are more electrothermally stable. The lower ZTC is due to the unipolar nature of SiC Schottky diodes as opposed to the bipolar nature of PiN diodes. This paper investigates the implementation and reliability of SiC Schottky diodes in press-pack assemblies. The impact of pressure loss on the electrothermal stability of parallel devices is investigated.
The version presented here may differ from the published version or, version of record, if you wi... more The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP url' above for details on accessing the published version and note that access may require a subscription.
Please refer to published version for the most recent bibliographic citation information. If a pu... more Please refer to published version for the most recent bibliographic citation information. If a published version is known of, the repository item page linked to above, will contain details on accessing it.
This study presents a new technique for detecting rotor electrical faults in wind turbine doubly-... more This study presents a new technique for detecting rotor electrical faults in wind turbine doubly-fed induction generators (DFIGs), controlled by a stator field-oriented vector control scheme. This is a novel method aimed at detecting and identifying rotor electrical asymmetry faults from within the rotor-side inverter control loop, using the error signal, to provide a future method of generator condition monitoring with enhanced detection sensitivity. Simulation and experimental measurements of the proposed signals were carried out under steady-state operation for both healthy and faulty generator conditions. Stator current and power were also investigated for rotor electrical asymmetry detection and comparison made with rotor-side inverter control signals. An investigation was then performed to define the sensitivity of the proposed monitoring signals to fault severity changes and a comparison made with previous current, power and vibration signal methods. The results confirm that a simple spectrum analysis of the proposed control loop signals gives effective and sensitive DFIG rotor electrical asymmetry detection.
As a renewable energy source, wind turbine generators are considered to be important generation a... more As a renewable energy source, wind turbine generators are considered to be important generation alternatives in electric power systems because of their non-exhaustible nature. As wind power penetration increases, power forecasting is crucially important for integrating wind power in a conventional power grid. A short-term wind farm power output prediction model is presented using fuzzy modeling derived from raw data of wind farm. Using wind data from a wind farm in Inner Mongolia of China, an interpretable model which reveal a useful qualitative description of the prediction system is developed, and a power forecasting map is illustrated. The comparative study of model prediction with different periods is conducted.
The version presented here may differ from the published version or, version of record, if you wi... more The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP URL' above for details on accessing the published version and note that access may require a subscription.
The version presented here may differ from the published version or, version of record, if you wi... more The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP URL' above for details on accessing the published version and note that access may require a subscription.
The version presented here may differ from the published version or, version of record, if you wi... more The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP URL' above for details on accessing the published version and note that access may require a subscription.
Please refer to published version for the most recent bibliographic citation information. If a pu... more Please refer to published version for the most recent bibliographic citation information. If a published version is known of, the repository item page linked to above, will contain details on accessing it.
2021 IEEE Energy Conversion Congress and Exposition (ECCE), 2021
Please refer to published version for the most recent bibliographic citation information. If a pu... more Please refer to published version for the most recent bibliographic citation information. If a published version is known of, the repository item page linked to above, will contain details on accessing it.
An investigation of temperature sensitive electrical parameters for SiC power MOSFETs. IEEE Trans... more An investigation of temperature sensitive electrical parameters for SiC power MOSFETs. IEEE Transactions on Power Electronics.
2014 IEEE Energy Conversion Congress and Exposition (ECCE), 2014
Schottky diodes are known to have lower conduction and switching losses compared to PiN diodes, h... more Schottky diodes are known to have lower conduction and switching losses compared to PiN diodes, however, are prone to ringing in the output characteristics. In this paper, analytical models have been developed to calculate the turn-off switching energy of SiC Schottky and silicon PiN diodes. The models account for the reverse recovery current and diode voltage overshoot in the case of the PiN diode as well as the output oscillations for the Schottky diodes. PiN diodes during turn-off exhibit significant reverse current which increases with the switching rate and temperature whereas Schottky diodes exhibit output oscillations due to RLC resonance in the circuit. By combining these models with thermal networks derived from transient thermal impedance curves of the diodes, a fast and accurate method of predicting the temperature transient for different switching frequencies and electrical time constants has been developed. These models can be used by application engineers to predict the energy dissipation when designing converters and can take account of temperature and switching rate dependencies of the diodes.
Integration of distributed generation (DG) such as photovoltaics (PV) represents a challenge for ... more Integration of distributed generation (DG) such as photovoltaics (PV) represents a challenge for the traditional operation of distribution power systems. As the installed power of DGs grows, grid codes are being modified to involve DGs in the provision of ancillary services. This includes the ability to ride-through large disturbances. In this paper, the behavior of a single-stage PV system under unbalanced voltage conditions is studied, and a fault ride-through control scheme is proposed which is able to support the grid through the injection of reactive power. Furthermore, adjustable power quality is enabled as a trade-off between power ripple and current harmonics. The control scheme makes use of a current controller based on the space vector Fourier transform concept. No rotational transformation is required, and zero steady-state error is ensured when tracking distorted current references. The controller was tested in detailed PSCAD/EMTDC computer simulations, and implemented in a real grid-connected PV system to demonstrate its performance under unbalanced voltage conditions.
Thermal coupling analysis for a multi-chip paralleled IGBT module in a doubly fed wind turbine po... more Thermal coupling analysis for a multi-chip paralleled IGBT module in a doubly fed wind turbine power converter. IEEE Transactions on Energy Conversion .
Please refer to published version for the most recent bibliographic citation information. If a pu... more Please refer to published version for the most recent bibliographic citation information. If a published version is known of, the repository item page linked to above, will contain details on accessing it.
The version presented here may differ from the published version or, version of record, if you wi... more The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP URL' above for details on accessing the published version and note that access may require a subscription.
16th International Conference and Exhibition on Electricity Distribution (CIRED 2001), 2001
Metal oxide varistors are widely used in many power electronics circuits to protect against trans... more Metal oxide varistors are widely used in many power electronics circuits to protect against transient over voltages. Certain applications are very demanding on the energy handling capability of the varistors. This paper gives an overview of the failure modes of ZnO varistors and investigates their characteristics when subjected to repetitive current pulses. It describes the puncture failure mode caused by melting of a region in the varistor of local current concentration. Experimental tests are performed to evaluate the puncture energy using an infrared imaging camera. A relationship between the energy absorption and the varistor maximum surface temperature is obtained. It is shown that the destructive energy depends strongly on the uniformity of the varistor; the more uniform, the higher the energy handling capability. The paper also presents the results of nondestructive tests using a scanning acoustic microscope to evaluate the uniformity of the varistor.
This paper illustrates an effect of sampling in an encoderless vector-controlled induction motor ... more This paper illustrates an effect of sampling in an encoderless vector-controlled induction motor drive with a digital controller. The analysis focuses on the speed observer and the speed control loop which is executed at discrete instants. It is shown that the estimated speed can fluctuate between samples in the speed loop and cause a sustained resonance via feedback. The shaft inertia is not available to smooth the ripple of the estimated speed and the associated resonance could adversely affect the inverter and machine. An analytical model is proposed to evaluate the risk of such a condition in the design and on-site adjustment of control gains. The requirement for a smoothing filter in the speed loop is identified.
This paper describes the design build and test of a linear test rig for demonstrating novel topol... more This paper describes the design build and test of a linear test rig for demonstrating novel topology linear machines. The work is aimed at aiding the developments of power take off for wave and tidal energy converters. The rig consists of three parts: prime mover, test machine and converter. Experience and method for the design manufacture and initial testing of each of these components is detailed. AUTHORS' BIOGRAPHIES Dr Baker has a mechanical engineering degree from Birmingham and a PhD in electrical aspects of wave energy conversion from Durham. He is currently an engineering lecturer within the Lancaster University Renewable Energy Group, pursuing research in power capture and control of wave energy devices and the economic capture of low head hydro power.
The thermomechanical reliability of SiC power devices and modules is increasingly becoming of int... more The thermomechanical reliability of SiC power devices and modules is increasingly becoming of interest especially for high power applications where power cycling performance is critical. Press-pack assemblies are a trusted and reliable packaging solution that has traditionally been used for high power thyristorbased applications in FACTS/HVDC, although press-pack IGBTs have become commercially available more recently. These press-pack IGBTs require anti-parallel PiN diodes for enabling reverse conduction capability. In these high power applications, paralleling chips for high current conduction capability is a requirement, hence, electrothermal stability during current sharing is critical. SiC Schottky diodes not only exhibit the advantages of wide bandgap technology compared to silicon PiN diodes, but they have significantly lower zero temperature coefficient (ZTC) meaning they are more electrothermally stable. The lower ZTC is due to the unipolar nature of SiC Schottky diodes as opposed to the bipolar nature of PiN diodes. This paper investigates the implementation and reliability of SiC Schottky diodes in press-pack assemblies. The impact of pressure loss on the electrothermal stability of parallel devices is investigated.
The version presented here may differ from the published version or, version of record, if you wi... more The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP url' above for details on accessing the published version and note that access may require a subscription.
Please refer to published version for the most recent bibliographic citation information. If a pu... more Please refer to published version for the most recent bibliographic citation information. If a published version is known of, the repository item page linked to above, will contain details on accessing it.
This study presents a new technique for detecting rotor electrical faults in wind turbine doubly-... more This study presents a new technique for detecting rotor electrical faults in wind turbine doubly-fed induction generators (DFIGs), controlled by a stator field-oriented vector control scheme. This is a novel method aimed at detecting and identifying rotor electrical asymmetry faults from within the rotor-side inverter control loop, using the error signal, to provide a future method of generator condition monitoring with enhanced detection sensitivity. Simulation and experimental measurements of the proposed signals were carried out under steady-state operation for both healthy and faulty generator conditions. Stator current and power were also investigated for rotor electrical asymmetry detection and comparison made with rotor-side inverter control signals. An investigation was then performed to define the sensitivity of the proposed monitoring signals to fault severity changes and a comparison made with previous current, power and vibration signal methods. The results confirm that a simple spectrum analysis of the proposed control loop signals gives effective and sensitive DFIG rotor electrical asymmetry detection.
As a renewable energy source, wind turbine generators are considered to be important generation a... more As a renewable energy source, wind turbine generators are considered to be important generation alternatives in electric power systems because of their non-exhaustible nature. As wind power penetration increases, power forecasting is crucially important for integrating wind power in a conventional power grid. A short-term wind farm power output prediction model is presented using fuzzy modeling derived from raw data of wind farm. Using wind data from a wind farm in Inner Mongolia of China, an interpretable model which reveal a useful qualitative description of the prediction system is developed, and a power forecasting map is illustrated. The comparative study of model prediction with different periods is conducted.
The version presented here may differ from the published version or, version of record, if you wi... more The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP URL' above for details on accessing the published version and note that access may require a subscription.
The version presented here may differ from the published version or, version of record, if you wi... more The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP URL' above for details on accessing the published version and note that access may require a subscription.
The version presented here may differ from the published version or, version of record, if you wi... more The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP URL' above for details on accessing the published version and note that access may require a subscription.
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