SiC JFET/P-MOSFET cascode for SSCB and inrush current limiter in 300V DC power systems

This work presents a solid-state distribution and protection switch based on the SiC JFET/P-MOSFET cascode structure. The concept is aimed for 300V applications, but it can be adapted easily to other voltages. Detailed circuit design and simulation is discussed, as well as the potential application in 300V bus voltage satellite

2017 Intern Experience [at] Neil A. Armstrong Flight Research Center

These detailed individual abstracts are being included in the summer 2017 abstract book, demonstrating the knowledge learned during the summer 2017 AFRC STEM program

Phase-shift-modulation for a current-fed isolated DC-DC converter in more electric aircraft

A Phase-Shift-Modulation (PSM) technique is proposed for an Active-Bridge-Active-Clamp (ABAC) topology. This topology is aimed for high power more-electric-aircraft applications. The proposed PSM has a complete switching harmonics cancellation on the low voltage terminal, independently of the operating conditions by effectively interleaving inductor currents. This results in a DC current at the low voltage terminal without any AC components, thus minimizing the passive filtering requirements. Additionally, when terminal voltages vary from their nominal values, the maximum power transfer capability of the ABAC converter can be greatly improved by using the proposed PSM. In this paper, the limitations of the conventional modulation technique for the ABAC converter are introduced and analysed. Then, a PSM scheme is proposed, which can provide high quality power on the low voltage terminal whilst maintaining high power transfer capability and efficiency in a wide operating range. The theoretical claims are validated by both simulation and experimental results on a 10kW 270V/28V ABAC converter

Inductive interconnecting solutions for airworthiness standards and power-quality requirements compliance for more-electric aircraft/engine power networks

Driven by efficiency benefits, performance optimization and reduced fuel-burn, the aviation industry has witnessed a technological shift towards the broader electrification of on-board systems, known as the More-Electric Aircraft (MEA) concept. Electrical systems are now responsible for functions that previously required mechanical, hydraulic or pneumatic power sources, with a subset of these functions being critical or essential to the continuity and safety of the flight.;This trend of incremental electrification has brought along benefits such as reductions in weight and volume, performance optimization and reduced life-cycle costs for the aircraft operator. It has however also increased the necessary engine power offtake and has made the electrical networks of modern MEA larger and more complex. In pursuit of new, more efficient electrical architectures, paralleled or interconnected generation is thought to be one platform towards improved performance and fuel savings.;However, the paralleling of multiple generation sources across the aircraft can breach current design and certification rules under fault conditions. This thesis proposes and evaluates candidate interconnecting solutions to minimize the propagation of transients across the interconnected network and demonstrates their effectiveness with reference to current airworthiness standards and MIL-STD-704F power quality requirements.;It demonstrates that inductive interconnections may achieve compliance with these requirements and quantifies the estimated mass penalty incurred on the electrical architecture, highlighting how architectural and operating strategies can influence design options at a systems level. By examining the impact of protection operation speed on the electrical network, it determines that fast fault protection is a key enabling technology towards implementing lightweight and compliant interconnected architectures.;Lastly, this thesis addresses potential implications arising from alternate standards interpretations within the framework of interconnected networks and demonstrates the impact of regulatory changes on the electrical architecture and interconnecting solutions.Driven by efficiency benefits, performance optimization and reduced fuel-burn, the aviation industry has witnessed a technological shift towards the broader electrification of on-board systems, known as the More-Electric Aircraft (MEA) concept. Electrical systems are now responsible for functions that previously required mechanical, hydraulic or pneumatic power sources, with a subset of these functions being critical or essential to the continuity and safety of the flight.;This trend of incremental electrification has brought along benefits such as reductions in weight and volume, performance optimization and reduced life-cycle costs for the aircraft operator. It has however also increased the necessary engine power offtake and has made the electrical networks of modern MEA larger and more complex. In pursuit of new, more efficient electrical architectures, paralleled or interconnected generation is thought to be one platform towards improved performance and fuel savings.;However, the paralleling of multiple generation sources across the aircraft can breach current design and certification rules under fault conditions. This thesis proposes and evaluates candidate interconnecting solutions to minimize the propagation of transients across the interconnected network and demonstrates their effectiveness with reference to current airworthiness standards and MIL-STD-704F power quality requirements.;It demonstrates that inductive interconnections may achieve compliance with these requirements and quantifies the estimated mass penalty incurred on the electrical architecture, highlighting how architectural and operating strategies can influence design options at a systems level. By examining the impact of protection operation speed on the electrical network, it determines that fast fault protection is a key enabling technology towards implementing lightweight and compliant interconnected architectures.;Lastly, this thesis addresses potential implications arising from alternate standards interpretations within the framework of interconnected networks and demonstrates the impact of regulatory changes on the electrical architecture and interconnecting solutions

Resilient power and propulsion system design for eVTOL aircraft

The continuous increase in population in megacities has led to a more pronounced issue of road congestion. Electrical vertical take-off and landing (eVTOL) aircraft have been proposed as a solution to alleviate road congestion by enabling greener and quieter aviation, providing a more time-efficient commuting option compared to helicopters. However, the realization of innovative eVTOL aircraft heavily relies on advancements in high-power and energy-dense power system technologies for lightweight electrical power systems (EPS). The limited maturity of lightweight EPS technologies and their safe integration into the aircraft pose challenges in terms of payload capacity and achievable range for eVTOL aircraft. This significantly impacts the performance of fully electric eVTOL aircraft for Urban Air Mobility (UAM) missions. Therefore, it is crucial to explore innovative approaches and new technologies for optimized EPS architecture and aerodynamic design at an early stage of the design process to achieve economical flight for UAM. These unique attributes of eVTOL aircraft differ significantly from conventional aircraft technologies and systems, emphasizing the need for a comprehensive understanding of aerodynamic-electrical failure interdependencies and EPS protection methodology to ensure a reliable EPS Therefore, the main research contributions of this thesis include the development of a novel design methodology to capture a certification-compliant EPS architecture for an eVTOL at the preliminary design phase. This methodology integrates mission requirements, aircraft aerodynamics, projected future availability of EPS technologies, and safety requirements. The development of the EPS architecture is carried out in parallel to the design of non-electrical systems to ensure future compliance with certification requirements. The methodology enables the identification of key design trades that minimise EPS system weight while ensuring that baseline safety criteria are met and future compliance with certification requirements. The results show that incorporating safety measures at a later stage will have a snowball effect on the aircraft design to meet certification requirements or stay within design constraints, such as weight. Furthermore, a novel abstract design methodology was developed to enable critical assessment of different aircraft aerodynamic configurations and explore new design spaces and novel architecture options. This methodology summarizes the relationship between aircraft aerodynamics and EPS requirements in a readily usable format. By combining the preliminary design methodology for a certification-compliant EPS architecture with the abstract design methodology, the complete assessment of various aircraft configurations and reliable EPS architecture designs and their weight for economic UAM missions can be achieved. Other main contributions of this thesis include the development of a preliminary certification compliance assessment for the use of non-resettable protection devices, specifically the Pyrofuse protection device, in eVTOL concept designs. The non-resettable nature of the device poses a challenge in the certification process for its integration into eVTOL electrical system protection. The assessment results demonstrate that the Pyrofuse protection device can achieve airworthiness in various roles as the primary protection for eVTOL EPS. However, the airworthiness is heavily influenced by the physical design of the aircraft, the proposed location of non-resettable protection devices, and their ability to withstand common mode and common cause failures to maintain minor failures. Model-based analysis plays a critical role in supporting this evaluation. Consequently, a comprehensive design methodology has been developed to transiently model Pyrofuse operation, which is publicly available. The results indicate that the Pyrofuse offers a significant level of resilience against transient events, minimising nuisance-tripping, while swiftly clearing short circuit faults. This model enables further assessment of Pyrofuse performance and susceptibility to different failure modes, including common mode failures.The continuous increase in population in megacities has led to a more pronounced issue of road congestion. Electrical vertical take-off and landing (eVTOL) aircraft have been proposed as a solution to alleviate road congestion by enabling greener and quieter aviation, providing a more time-efficient commuting option compared to helicopters. However, the realization of innovative eVTOL aircraft heavily relies on advancements in high-power and energy-dense power system technologies for lightweight electrical power systems (EPS). The limited maturity of lightweight EPS technologies and their safe integration into the aircraft pose challenges in terms of payload capacity and achievable range for eVTOL aircraft. This significantly impacts the performance of fully electric eVTOL aircraft for Urban Air Mobility (UAM) missions. Therefore, it is crucial to explore innovative approaches and new technologies for optimized EPS architecture and aerodynamic design at an early stage of the design process to achieve economical flight for UAM. These unique attributes of eVTOL aircraft differ significantly from conventional aircraft technologies and systems, emphasizing the need for a comprehensive understanding of aerodynamic-electrical failure interdependencies and EPS protection methodology to ensure a reliable EPS Therefore, the main research contributions of this thesis include the development of a novel design methodology to capture a certification-compliant EPS architecture for an eVTOL at the preliminary design phase. This methodology integrates mission requirements, aircraft aerodynamics, projected future availability of EPS technologies, and safety requirements. The development of the EPS architecture is carried out in parallel to the design of non-electrical systems to ensure future compliance with certification requirements. The methodology enables the identification of key design trades that minimise EPS system weight while ensuring that baseline safety criteria are met and future compliance with certification requirements. The results show that incorporating safety measures at a later stage will have a snowball effect on the aircraft design to meet certification requirements or stay within design constraints, such as weight. Furthermore, a novel abstract design methodology was developed to enable critical assessment of different aircraft aerodynamic configurations and explore new design spaces and novel architecture options. This methodology summarizes the relationship between aircraft aerodynamics and EPS requirements in a readily usable format. By combining the preliminary design methodology for a certification-compliant EPS architecture with the abstract design methodology, the complete assessment of various aircraft configurations and reliable EPS architecture designs and their weight for economic UAM missions can be achieved. Other main contributions of this thesis include the development of a preliminary certification compliance assessment for the use of non-resettable protection devices, specifically the Pyrofuse protection device, in eVTOL concept designs. The non-resettable nature of the device poses a challenge in the certification process for its integration into eVTOL electrical system protection. The assessment results demonstrate that the Pyrofuse protection device can achieve airworthiness in various roles as the primary protection for eVTOL EPS. However, the airworthiness is heavily influenced by the physical design of the aircraft, the proposed location of non-resettable protection devices, and their ability to withstand common mode and common cause failures to maintain minor failures. Model-based analysis plays a critical role in supporting this evaluation. Consequently, a comprehensive design methodology has been developed to transiently model Pyrofuse operation, which is publicly available. The results indicate that the Pyrofuse offers a significant level of resilience against transient events, minimising nuisance-tripping, while swiftly clearing short circuit faults. This model enables further assessment of Pyrofuse performance and susceptibility to different failure modes, including common mode failures

Large space structures and systems in the space station era: A bibliography with indexes

Bibliographies and abstracts are listed for 1372 reports, articles, and other documents introduced into the NASA scientific and technical information system between January 1, 1990 and June 30, 1990. Its purpose is to provide helpful information to the researcher, manager, and designer in technology development and mission design according to system, interactive analysis and design, structural and thermal analysis and design, structural concepts and control systems, electronics, advanced materials, assembly concepts, propulsion, and solar power satellite systems

Advanced control of dual active bridge converter for more electric aircraft applications

Within more-electric aircraft (MEA) electrical power systems, dual-active-bridge (DAB) converters are used to manage power flow between different DC buses or power to/from energy storage devices, such as batteries. Conventionally, this functionality is achieved through hierarchical linear control loops using proportional integral (PI) controllers. However, this method fails to achieve fast enough dynamic responses needed for future aircraft applications. This thesis addresses this issue by introducing a multi-dimensional moving discretised control set model predictive control (MDCS-MPC) approach. This proposed method demonstrates flexible multi-objective control and rapid dynamic response. The investigation covers three specific control scenarios. Firstly, the multi-dimensional MDCS-MPC is applied to DAB converters for steady-state DC offset suppression and output current regulation. Additionally, an artificial neural network (ANN)-based parameter estimation approach is proposed to minimise the steady-state error of the MDCS-MPC controller by improving the accuracy of the developed discretised model. Secondly, the MDCS-MPC is used for transient DC offset suppression and output current regulation. Detailed models for three different transient conditions, including power transfer increase, decrease and reversal are developed. Finally, the impact of interlinking and stray inductances of the DAB converter is considered, resulting in a modified mathematical model for control designs. The proposed control scheme is validated through comprehensive simulation and experimental studies

Advanced control of dual active bridge converter for more electric aircraft applications

Within more-electric aircraft (MEA) electrical power systems, dual-active-bridge (DAB) converters are used to manage power flow between different DC buses or power to/from energy storage devices, such as batteries. Conventionally, this functionality is achieved through hierarchical linear control loops using proportional integral (PI) controllers. However, this method fails to achieve fast enough dynamic responses needed for future aircraft applications. This thesis addresses this issue by introducing a multi-dimensional moving discretised control set model predictive control (MDCS-MPC) approach. This proposed method demonstrates flexible multi-objective control and rapid dynamic response. The investigation covers three specific control scenarios. Firstly, the multi-dimensional MDCS-MPC is applied to DAB converters for steady-state DC offset suppression and output current regulation. Additionally, an artificial neural network (ANN)-based parameter estimation approach is proposed to minimise the steady-state error of the MDCS-MPC controller by improving the accuracy of the developed discretised model. Secondly, the MDCS-MPC is used for transient DC offset suppression and output current regulation. Detailed models for three different transient conditions, including power transfer increase, decrease and reversal are developed. Finally, the impact of interlinking and stray inductances of the DAB converter is considered, resulting in a modified mathematical model for control designs. The proposed control scheme is validated through comprehensive simulation and experimental studies

Aeronautical Engineering: A continuing bibliography with indexes

This bibliography lists 529 reports, articles, and other documents introduced into the NASA Scientific and Technical Information System in May 1980