thanatheepan balachandran | University of Peradeniya (original) (raw)

Papers by thanatheepan balachandran

AIAA Propulsion and Energy 2020 Forum, Aug 17, 2020

The aviation industry has been challenged to increase the sustainability of its technologies, whi... more The aviation industry has been challenged to increase the sustainability of its technologies, which is the main driving force in research and exploration of fully electrified propulsion. This paper presents the initial steps in the design and modeling of the Cryogenic High-Efficiency Electrical Technologies for Aircraft (CHEETA) that would form the basis for hybrid-electric aircraft power systems. To this end, different power system configurations for fully electrified propulsion are proposed and analyzed. Novel, multi-domain components used in both the power system model and the cryogenic thermal system model are introduced and explained in detail. This paper also presents initial results for the different power system configurations under steady-state conditions.

IEEE Electrification Magazine, Jun 1, 2022

IEEE Transactions on Applied Superconductivity, 2020

A significant challenge in the design of fully superconducting (SC) machines is managing ac losse... more A significant challenge in the design of fully superconducting (SC) machines is managing ac losses in the SC armature. Recent developments in MgB 2 superconducting conductors promise low ac loss conductors suitable for fully SC machines. This paper presents an optimized design targeting low losses and low weight for a 10-MW fully SC generator suitable for offshore wind turbine applications. An outer rotor air-core machine topology is investigated to optimize the design with low weight and low losses. An active shielding concept is used to minimize the pole count without adding excessive weight. This enables a reduction in the electrical frequency for a practical design by a factor of 4 to 5 over current designs, driving ac losses and active components weight lower by an order of magnitude. In this study, armature current is varied to control electrical and magnetic loading in order to minimize losses. A pole count study is conducted to identify the design space suitable for MW scale machines. A comparison is made between active shield, passive shield and a hybrid topology to address the benefits of an active shield for weight reduction. Results suggest that low-pole-count designs with MgB 2 conductors will enable machines with less than 1 kW of ac losses.

Journal of Propulsion and Power, Sep 1, 2021

Electric aircraft propulsion is a growing research area that looks into achieving propulsion thro... more Electric aircraft propulsion is a growing research area that looks into achieving propulsion through fully electric or hybrid electric systems while achieving low CO2 emissions. The system-level be...

IEEE Transactions on Industry Applications, Mar 1, 2023

Electric aircraft makes aviation more efficient and sustainable. Experimentally demonstrated hybr... more Electric aircraft makes aviation more efficient and sustainable. Experimentally demonstrated hybrid and fully electric aircrafts require high voltage electric systems and high-power density machines for their commercial usage. Insulation life time of these electrical systems should be substantial to make these designs feasible for commercial aircraft applications. While insulation degradation due to the aeronautical environment on high voltage cables are heavily researched, impact on winding insulation is not investigated. Life time of motors significantly depend on the winding insulation quality. This paper presents the insulation qualification analysis and its impact on life time for a form-wound air-core armature winding using partial discharge (PD) test. The windings that were tested and presented in this paper are designed using Litz-wire for a high-speed 1MW permanent magnet synchronous motor(PMSM). In this paper, special attention is given to the high altitude operating condition of the machine and the PD tests are performed under those conditions. These results are used to investigate the impact of voltage induced stress on the life time of the machine. Temperature and pressure variation and its impact on PD activity on the implemented windings insulation scheme are experimentally tested.

Electric propulsion systems for aircraft require electric motors with high power density and high... more Electric propulsion systems for aircraft require electric motors with high power density and high efficiency. This paper presents the design and analysis of a 300 kW slotless permanent magnet synchronous motor for electric aircraft propulsion. The machine consists of a Halbach PM-array structure and an air-cooled slotless stator with custom litz wire formed using cured, ceramic-filled resin. The proposed motor is designed considering multi-physics performance based on electromagnetic field, thermal and mechanical analysis. However, the resulting motor specifications and detailed dimensions are changed for economies of scale and ease of manufacturing by altering the magnet segment number, magnet shape and litz wire shape. The impacts of changing these parameters are addressed in this paper.

This paper presents a methodology to calculate the worst-case reliability of smart distribution s... more This paper presents a methodology to calculate the worst-case reliability of smart distribution system. Impact of communication infrastructure failure on the system reliability is investigated in both substation-centered and decentralized multi-agent restoration management. Different communication infrastructure is also examined to evaluate the impact in the reliability of the substation centered distribution system. Comparison of the Worst-case Expected Energy Not Served (WEENS) is performed for all scenarios. Worst case communication link failure is adopted in reliability evaluation of cyber enabled distribution system.

IOP conference series, Mar 1, 2020

Partial and fully superconducting (SC) machines promise high power density capabilities required ... more Partial and fully superconducting (SC) machines promise high power density capabilities required for electric propulsion. These machines need to achieve high power densities while reducing electrical heat losses to minimize the required cryogenic power and subsequent additional weight. Hydrogen powered all-electric planes provide a design space where ac losses are manageable. However, the high electrical frequencies in high-speed fully superconducting machines pose a significant challenge to reducing armature ac losses. In high-speed applications, coupling loss in the SC armature coils dominates and becomes a barrier for practical application of these machines. In this paper a fully superconducting machine is proposed for a hydrogen powered regional all-electric plane. An air core design is considered utilizing low ac loss MgB2 wires. The design is targeted to achieve 50 kW/kg specific power while requiring ac losses to be less than 3 kW. This study explores the possibility of replacing a passive iron shield with active shielding coils to contain the magnetic flux inside the machine while reducing weight and increasing power density. The study focuses on minimizing weight as well as ac losses in the armature coils. An optimization algorithm is used to determine the trade-offs between iron shield and active shield coil designs. Results show that optimal designs for electric propulsion eliminate the passive shield in favor of active shielding coils - increasing the power density of the machine while maintaining the outside flux density below standard safety limits.

IEEE Transactions on Applied Superconductivity, Aug 1, 2023

Energies, Aug 23, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Iet Generation Transmission & Distribution, Aug 1, 2016

The smart distribution system initiative requires higher usage of a distribution feeder-level com... more The smart distribution system initiative requires higher usage of a distribution feeder-level communication infrastructure to improve system automation. This study proposes a hybrid medium access control (MAC) protocol to manage time-driven and event-driven distribution system applications. This MAC protocol, ALARM, for high-priority events/situational awareness requirements is proposed based on the power system properties. ALARM protocol utilises unique properties of radial feeders and reduces average communication congestion, latency to collect all messages and processing time. This work shows the advantage of using cyber and power system properties to improve automation enabled future distribution system operations.

Thomas K. DeLillo for his valuable time and support. I want to thank my family members who were a... more Thomas K. DeLillo for his valuable time and support. I want to thank my family members who were always supporting and motivating me to continue my higher studies. I also want to thank my friends whose interminable motivation and help brought me this far. Finally, I would like to thank Wichita State University for giving me this opportunity to do my research work. vi ABSTRACT Reliability standards are followed in power system industries as a series of requirement from planning to operation and this necessitates evaluating, improving and reporting reliability indices of the power systems to the regulators on a regular basis. Eighty percent of the power system outages happen due to disturbances caused in the distribution power system. Recent developments in smart grid technologies demonstrate how communication technologies can be used to improve the reliability of the distribution power system. In this research, a distributed sensor network architecture is projected for monitoring the distribution system. A dedicated communication protocol "ALARM" for distributed sensor monitoring network communication is briefly discussed. Furthermore, a Hidden Markov Model (HMM) based local event detection mechanism is proposed to improve the reliability of the distribution power system. The proposed system has the capability of detecting faults locally with a minimum delay time. It is shown that such a local event detection system can improve the reliability of the distribution power system in many aspects. Further, a novel methodology to evaluate the reliability of cyber physical power system is proposed in this research. This work incorporates power component failure, automation component failure, communication failure, communication delay and cyber-attacks to develop a comprehensive equipment level reliability model. From the 36 possible states, a 12-state model is derived to aid the component level reliability analysis. Furthermore, for large network level reliability evaluation purpose, a reduced 2 state model is also obtained. Depending on the application in the power system, smart component categorized into three groups and corresponding 2 state models are obtained for each category. Finally, sensitivity analysis is carried out to evaluate the impact of cyber-failure and cyber-attacks on the reliability of the smart component. vii

A co-design of an electric aircraft powertrain optimization is investigated in this paper. Number... more A co-design of an electric aircraft powertrain optimization is investigated in this paper. Number of propulsors, gear ratio, propeller and motor geometry are considered as system design variables. Optimization of the system design for high overall system efficiency and low mass is attempted with considerations for winding temperature, current density, iron flux density, and machine aspect ratio. The powertrain was sized to deliver thrust according to a simple set of mission requirements at desired flight speed for a representative passenger aircraft. The results suggested that small propulsor counts are optimal for low weight and high efficiency, and that an ideal propeller speed exists for a given co-design problem

AIAA Propulsion and Energy 2020 Forum, Aug 17, 2020

This paper discusses the manufacturing process and qualification procedures of a slotless stator ... more This paper discusses the manufacturing process and qualification procedures of a slotless stator for a 1-MW high-speed permanent magnet synchronous machine. The motor, targeted to reach 13 kW/kg, is assembled with form-wound air-core armature windings which utilize litz wire as the conductor. A prototype is being developed and a full-power test will be done in the near future. The insulation, mechanical and thermal qualification test procedures of the stator are discussed in detail. Results showed that the manufacturing process and tolerances significantly affect the machine performance. Various assembly challenges of this slotless stator and their impacts on performance targets are illustrated.

2021 IEEE Power & Energy Society General Meeting (PESGM), Jul 26, 2021

Reliability evaluation of power components in the presence of automation devices and cyber links ... more Reliability evaluation of power components in the presence of automation devices and cyber links is critical for the improved performance of a smart grid. This work presents a model representing a cyber power component for reliability studies, incorporating interdependency and common-cause failure while reducing computational complexity. Power-component failure, automation-component failure, communication failure, communication delay, and cyberattack are incorporated to develop a comprehensive component-level reliability-evaluation model. A multistate model is proposed with 36 states for a cyber-enabled power component by integrating cyber links as a part of the smart component. Based on the power system reliability analysis, this model is reduced to a 12-state model. Finally, a two-state model is presented for its practical adaptation to specific applications. Due to the nature of the smart component, the following basic applications are considered in this work: (i) health monitoring, (ii) real-time monitoring, and (iii) actuation. A sensitivity analysis is carried out to evaluate the impact of cyber failure and cyberattacks on the reliability of the smart component. Model-reduction techniques, reliability-evaluation procedures, and example case study are provided in order to validate the proposed method

IEEE Transactions on Applied Superconductivity, Aug 1, 2023

The development of low AC loss MgB 2 conductors and the increasing interest in a liquid hydrogen-... more The development of low AC loss MgB 2 conductors and the increasing interest in a liquid hydrogen-based economy have reignited research into high power density fully superconducting (SC) electrical machines. In these machines, the armature winding experiences rotating fields that generate AC losses, making it essential to estimate these losses during machine design. While analytical and finite element analysis (FEA) models are available in the literature for estimating AC losses, these models for multi-filament MgB 2 superconductors have yet to be experimentally validated for machine operating regions. This article presents a high-precision AC-loss test setup to measure AC losses in SC MgB 2 windings under rotating fields at the air-gap field, frequency, and operating temperature levels relevant to electrical machine applications. The experimentally measured AC losses are then compared with analytical and FEA models. Results demonstrate good agreement between measurements and predictions. The paper discusses the experimental setup, sample preparation, calibration, measurement method, and results. The study provides a significant contribution to the development of high power density fully SC electrical machines.

AIAA Propulsion and Energy 2020 Forum, Aug 17, 2020

This paper discusses the co-design of an electric aircraft propulsion system for minimum weight a... more This paper discusses the co-design of an electric aircraft propulsion system for minimum weight and maximum power-to-thrust efficiency. The system under consideration for preliminary exploration of the methodology consists of a fully superconducting synchronous motor and a ducted, fixed-pitch propeller. In order to ensure a viable propulsor, a minimum required thrust bound is imposed on the system design. Both analytical methods and finite-element analysis (FEA) are used to size the motor, and a blade-element momentum (BEM) model is implemented for predicting performance of the ducted propeller. A genetic algorithm optimization scheme is applied on a hydrogen-powered electric aircraft propulsion system proposed for the Center for High-Efficiency Electrical Technologies for Aircraft (CHEETA) project. Sensitivity of the combined system efficiency to motor weight is evaluated.

Fully superconducting (SC)machines hold immense promise for high-power-density and higher efficie... more Fully superconducting (SC)machines hold immense promise for high-power-density and higher efficiency machine solutions for offshore wind turbine applications. In this paper, a 10MW air-core fully SC machine is designed for offshore wind turbine applications. This machine design is considered with inside armature coils and outside rotating field coils. In this topology, shield iron can be eliminated or reduced by replacing it with shield coils which contain the magnetic flux inside the machine. This machine is attractive for off-shore wind turbine application due to its high-power density and high efficiency compared to a conventional shield iron design. However, due to the introduction of additional shield coils, this topology uses relatively more amount of SC material than a conventional shield iron design. Therefore, a tradeoff between the shield coils and the shield iron is explored in this paper. In addition, machine designs with different pole-counts are investigated to identify the optimal pole-count design for a low-speed application. A detailed ac loss calculation is evaluated for the machine and required cryocooler power is evaluated to obtain the machine efficiency.

AIAA Propulsion and Energy 2020 Forum, Aug 17, 2020

The aviation industry has been challenged to increase the sustainability of its technologies, whi... more The aviation industry has been challenged to increase the sustainability of its technologies, which is the main driving force in research and exploration of fully electrified propulsion. This paper presents the initial steps in the design and modeling of the Cryogenic High-Efficiency Electrical Technologies for Aircraft (CHEETA) that would form the basis for hybrid-electric aircraft power systems. To this end, different power system configurations for fully electrified propulsion are proposed and analyzed. Novel, multi-domain components used in both the power system model and the cryogenic thermal system model are introduced and explained in detail. This paper also presents initial results for the different power system configurations under steady-state conditions.

IEEE Electrification Magazine, Jun 1, 2022

IEEE Transactions on Applied Superconductivity, 2020

A significant challenge in the design of fully superconducting (SC) machines is managing ac losse... more A significant challenge in the design of fully superconducting (SC) machines is managing ac losses in the SC armature. Recent developments in MgB 2 superconducting conductors promise low ac loss conductors suitable for fully SC machines. This paper presents an optimized design targeting low losses and low weight for a 10-MW fully SC generator suitable for offshore wind turbine applications. An outer rotor air-core machine topology is investigated to optimize the design with low weight and low losses. An active shielding concept is used to minimize the pole count without adding excessive weight. This enables a reduction in the electrical frequency for a practical design by a factor of 4 to 5 over current designs, driving ac losses and active components weight lower by an order of magnitude. In this study, armature current is varied to control electrical and magnetic loading in order to minimize losses. A pole count study is conducted to identify the design space suitable for MW scale machines. A comparison is made between active shield, passive shield and a hybrid topology to address the benefits of an active shield for weight reduction. Results suggest that low-pole-count designs with MgB 2 conductors will enable machines with less than 1 kW of ac losses.

Journal of Propulsion and Power, Sep 1, 2021

Electric aircraft propulsion is a growing research area that looks into achieving propulsion thro... more Electric aircraft propulsion is a growing research area that looks into achieving propulsion through fully electric or hybrid electric systems while achieving low CO2 emissions. The system-level be...

IEEE Transactions on Industry Applications, Mar 1, 2023

Electric aircraft makes aviation more efficient and sustainable. Experimentally demonstrated hybr... more Electric aircraft makes aviation more efficient and sustainable. Experimentally demonstrated hybrid and fully electric aircrafts require high voltage electric systems and high-power density machines for their commercial usage. Insulation life time of these electrical systems should be substantial to make these designs feasible for commercial aircraft applications. While insulation degradation due to the aeronautical environment on high voltage cables are heavily researched, impact on winding insulation is not investigated. Life time of motors significantly depend on the winding insulation quality. This paper presents the insulation qualification analysis and its impact on life time for a form-wound air-core armature winding using partial discharge (PD) test. The windings that were tested and presented in this paper are designed using Litz-wire for a high-speed 1MW permanent magnet synchronous motor(PMSM). In this paper, special attention is given to the high altitude operating condition of the machine and the PD tests are performed under those conditions. These results are used to investigate the impact of voltage induced stress on the life time of the machine. Temperature and pressure variation and its impact on PD activity on the implemented windings insulation scheme are experimentally tested.

Electric propulsion systems for aircraft require electric motors with high power density and high... more Electric propulsion systems for aircraft require electric motors with high power density and high efficiency. This paper presents the design and analysis of a 300 kW slotless permanent magnet synchronous motor for electric aircraft propulsion. The machine consists of a Halbach PM-array structure and an air-cooled slotless stator with custom litz wire formed using cured, ceramic-filled resin. The proposed motor is designed considering multi-physics performance based on electromagnetic field, thermal and mechanical analysis. However, the resulting motor specifications and detailed dimensions are changed for economies of scale and ease of manufacturing by altering the magnet segment number, magnet shape and litz wire shape. The impacts of changing these parameters are addressed in this paper.

This paper presents a methodology to calculate the worst-case reliability of smart distribution s... more This paper presents a methodology to calculate the worst-case reliability of smart distribution system. Impact of communication infrastructure failure on the system reliability is investigated in both substation-centered and decentralized multi-agent restoration management. Different communication infrastructure is also examined to evaluate the impact in the reliability of the substation centered distribution system. Comparison of the Worst-case Expected Energy Not Served (WEENS) is performed for all scenarios. Worst case communication link failure is adopted in reliability evaluation of cyber enabled distribution system.

IOP conference series, Mar 1, 2020

Partial and fully superconducting (SC) machines promise high power density capabilities required ... more Partial and fully superconducting (SC) machines promise high power density capabilities required for electric propulsion. These machines need to achieve high power densities while reducing electrical heat losses to minimize the required cryogenic power and subsequent additional weight. Hydrogen powered all-electric planes provide a design space where ac losses are manageable. However, the high electrical frequencies in high-speed fully superconducting machines pose a significant challenge to reducing armature ac losses. In high-speed applications, coupling loss in the SC armature coils dominates and becomes a barrier for practical application of these machines. In this paper a fully superconducting machine is proposed for a hydrogen powered regional all-electric plane. An air core design is considered utilizing low ac loss MgB2 wires. The design is targeted to achieve 50 kW/kg specific power while requiring ac losses to be less than 3 kW. This study explores the possibility of replacing a passive iron shield with active shielding coils to contain the magnetic flux inside the machine while reducing weight and increasing power density. The study focuses on minimizing weight as well as ac losses in the armature coils. An optimization algorithm is used to determine the trade-offs between iron shield and active shield coil designs. Results show that optimal designs for electric propulsion eliminate the passive shield in favor of active shielding coils - increasing the power density of the machine while maintaining the outside flux density below standard safety limits.

IEEE Transactions on Applied Superconductivity, Aug 1, 2023

Energies, Aug 23, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Iet Generation Transmission & Distribution, Aug 1, 2016

The smart distribution system initiative requires higher usage of a distribution feeder-level com... more The smart distribution system initiative requires higher usage of a distribution feeder-level communication infrastructure to improve system automation. This study proposes a hybrid medium access control (MAC) protocol to manage time-driven and event-driven distribution system applications. This MAC protocol, ALARM, for high-priority events/situational awareness requirements is proposed based on the power system properties. ALARM protocol utilises unique properties of radial feeders and reduces average communication congestion, latency to collect all messages and processing time. This work shows the advantage of using cyber and power system properties to improve automation enabled future distribution system operations.

Thomas K. DeLillo for his valuable time and support. I want to thank my family members who were a... more Thomas K. DeLillo for his valuable time and support. I want to thank my family members who were always supporting and motivating me to continue my higher studies. I also want to thank my friends whose interminable motivation and help brought me this far. Finally, I would like to thank Wichita State University for giving me this opportunity to do my research work. vi ABSTRACT Reliability standards are followed in power system industries as a series of requirement from planning to operation and this necessitates evaluating, improving and reporting reliability indices of the power systems to the regulators on a regular basis. Eighty percent of the power system outages happen due to disturbances caused in the distribution power system. Recent developments in smart grid technologies demonstrate how communication technologies can be used to improve the reliability of the distribution power system. In this research, a distributed sensor network architecture is projected for monitoring the distribution system. A dedicated communication protocol "ALARM" for distributed sensor monitoring network communication is briefly discussed. Furthermore, a Hidden Markov Model (HMM) based local event detection mechanism is proposed to improve the reliability of the distribution power system. The proposed system has the capability of detecting faults locally with a minimum delay time. It is shown that such a local event detection system can improve the reliability of the distribution power system in many aspects. Further, a novel methodology to evaluate the reliability of cyber physical power system is proposed in this research. This work incorporates power component failure, automation component failure, communication failure, communication delay and cyber-attacks to develop a comprehensive equipment level reliability model. From the 36 possible states, a 12-state model is derived to aid the component level reliability analysis. Furthermore, for large network level reliability evaluation purpose, a reduced 2 state model is also obtained. Depending on the application in the power system, smart component categorized into three groups and corresponding 2 state models are obtained for each category. Finally, sensitivity analysis is carried out to evaluate the impact of cyber-failure and cyber-attacks on the reliability of the smart component. vii

A co-design of an electric aircraft powertrain optimization is investigated in this paper. Number... more A co-design of an electric aircraft powertrain optimization is investigated in this paper. Number of propulsors, gear ratio, propeller and motor geometry are considered as system design variables. Optimization of the system design for high overall system efficiency and low mass is attempted with considerations for winding temperature, current density, iron flux density, and machine aspect ratio. The powertrain was sized to deliver thrust according to a simple set of mission requirements at desired flight speed for a representative passenger aircraft. The results suggested that small propulsor counts are optimal for low weight and high efficiency, and that an ideal propeller speed exists for a given co-design problem

AIAA Propulsion and Energy 2020 Forum, Aug 17, 2020

This paper discusses the manufacturing process and qualification procedures of a slotless stator ... more This paper discusses the manufacturing process and qualification procedures of a slotless stator for a 1-MW high-speed permanent magnet synchronous machine. The motor, targeted to reach 13 kW/kg, is assembled with form-wound air-core armature windings which utilize litz wire as the conductor. A prototype is being developed and a full-power test will be done in the near future. The insulation, mechanical and thermal qualification test procedures of the stator are discussed in detail. Results showed that the manufacturing process and tolerances significantly affect the machine performance. Various assembly challenges of this slotless stator and their impacts on performance targets are illustrated.

2021 IEEE Power & Energy Society General Meeting (PESGM), Jul 26, 2021

Reliability evaluation of power components in the presence of automation devices and cyber links ... more Reliability evaluation of power components in the presence of automation devices and cyber links is critical for the improved performance of a smart grid. This work presents a model representing a cyber power component for reliability studies, incorporating interdependency and common-cause failure while reducing computational complexity. Power-component failure, automation-component failure, communication failure, communication delay, and cyberattack are incorporated to develop a comprehensive component-level reliability-evaluation model. A multistate model is proposed with 36 states for a cyber-enabled power component by integrating cyber links as a part of the smart component. Based on the power system reliability analysis, this model is reduced to a 12-state model. Finally, a two-state model is presented for its practical adaptation to specific applications. Due to the nature of the smart component, the following basic applications are considered in this work: (i) health monitoring, (ii) real-time monitoring, and (iii) actuation. A sensitivity analysis is carried out to evaluate the impact of cyber failure and cyberattacks on the reliability of the smart component. Model-reduction techniques, reliability-evaluation procedures, and example case study are provided in order to validate the proposed method

IEEE Transactions on Applied Superconductivity, Aug 1, 2023

The development of low AC loss MgB 2 conductors and the increasing interest in a liquid hydrogen-... more The development of low AC loss MgB 2 conductors and the increasing interest in a liquid hydrogen-based economy have reignited research into high power density fully superconducting (SC) electrical machines. In these machines, the armature winding experiences rotating fields that generate AC losses, making it essential to estimate these losses during machine design. While analytical and finite element analysis (FEA) models are available in the literature for estimating AC losses, these models for multi-filament MgB 2 superconductors have yet to be experimentally validated for machine operating regions. This article presents a high-precision AC-loss test setup to measure AC losses in SC MgB 2 windings under rotating fields at the air-gap field, frequency, and operating temperature levels relevant to electrical machine applications. The experimentally measured AC losses are then compared with analytical and FEA models. Results demonstrate good agreement between measurements and predictions. The paper discusses the experimental setup, sample preparation, calibration, measurement method, and results. The study provides a significant contribution to the development of high power density fully SC electrical machines.

AIAA Propulsion and Energy 2020 Forum, Aug 17, 2020

This paper discusses the co-design of an electric aircraft propulsion system for minimum weight a... more This paper discusses the co-design of an electric aircraft propulsion system for minimum weight and maximum power-to-thrust efficiency. The system under consideration for preliminary exploration of the methodology consists of a fully superconducting synchronous motor and a ducted, fixed-pitch propeller. In order to ensure a viable propulsor, a minimum required thrust bound is imposed on the system design. Both analytical methods and finite-element analysis (FEA) are used to size the motor, and a blade-element momentum (BEM) model is implemented for predicting performance of the ducted propeller. A genetic algorithm optimization scheme is applied on a hydrogen-powered electric aircraft propulsion system proposed for the Center for High-Efficiency Electrical Technologies for Aircraft (CHEETA) project. Sensitivity of the combined system efficiency to motor weight is evaluated.

Fully superconducting (SC)machines hold immense promise for high-power-density and higher efficie... more Fully superconducting (SC)machines hold immense promise for high-power-density and higher efficiency machine solutions for offshore wind turbine applications. In this paper, a 10MW air-core fully SC machine is designed for offshore wind turbine applications. This machine design is considered with inside armature coils and outside rotating field coils. In this topology, shield iron can be eliminated or reduced by replacing it with shield coils which contain the magnetic flux inside the machine. This machine is attractive for off-shore wind turbine application due to its high-power density and high efficiency compared to a conventional shield iron design. However, due to the introduction of additional shield coils, this topology uses relatively more amount of SC material than a conventional shield iron design. Therefore, a tradeoff between the shield coils and the shield iron is explored in this paper. In addition, machine designs with different pole-counts are investigated to identify the optimal pole-count design for a low-speed application. A detailed ac loss calculation is evaluated for the machine and required cryocooler power is evaluated to obtain the machine efficiency.