Search

Hybrid electric propulsion could be the solution to the ambitious environmental targets of the aerospace industry. Fully-superconducting machines have the potential to deliver the step-change in specific torque, power, and efficiency capabilities required for large civil transport aircraft applications. However, fully-superconducting machines are still in their infancy. This article investigates the electromagnetic design of two different stator design concepts for an ac fully-superconducting machine for an aerospace distributed fan motor application. A benchmark aerospace specification of 1 MW was chosen and the design of a conventional permanent-magnet machine was used to assess the performance of the two equivalent fully-superconducting ac motor designs. Following the guidelines from an experimental study of the losses in a small ac stator prototype with MgB 2 coils, a fully-superconducting air-cored stator design and a new yokeless stator design are proposed. Both ac superconducting machine designs use superconducting bulk magnets mounted on a rotor core and an MgB 2 superconducting stator winding. This article discusses the key design issues of the two stator layouts in relation to the current aerospace targets for efficiency and power density.

This paper addresses the concept of designing and implementing the power management system (PMS) for electrical power system (EPS) of more electric engine/aircraft (MEE/MEA). An optimization model for the PMS in MEE/MEA is formulated. Various PMS solutions are required to meet different performance expectations. In order to have least possible electrical network losses, two types of PMS solutions are proposed, i.e., to optimize the generator efficiency and to optimize the EPS level efficiency, as single objective optimization problem (SOOP) and multiple objective optimization problem (MOOP), respectively. The SOOP is solved as a mixed integer programming problem while the MOOP is solved with a modified non-dominated genetic algorithm. The proposed PMS algorithm is implemented in the MEE/MEA simulation model and results show the effectiveness of the proposed algorithm.

International audience; Hybrid electric propulsion has been identified as a potential solu-tion to the ambitious environmental emissions and noise targets of the aerospace industry. Superconducting machines may be the key component of that topology enabling the high power densities and efficiencies needed in aerospace. Fully superconducting ma-chines, however, are not a mature technology. This paper looks at the different machine design configurations focusing on the stator magnetic circuit of a fully superconducting motor. The motor has been designed for an aerospace distributed fan propulsion motor with an aerospace benchmark specification of 1 MW. The AC ful-ly superconducting machine includes superconducting bulk magnets mounted on a conventional rotor core and an MgB2 su-perconducting wire wound stator. The AC losses in the stator winding are particularly sensitive to exposure to the main rotor field so different screening solutions were used to shield the su-perconducting windings from the rotor field. The effectiveness of the screening techniques for the stator coils and the impact on the machine performance and weight were evaluated for different stator designs, such as full stator core and air core with and without flux diverters. Various combinations of pole numbers, diverter geometries and magnetic materials have been checked. Results show that there is a trade-off between stator iron losses and superconducting losses.

The aerospace industry has ambitious environmental emissions and noise reduction targets that have led to some radical proposals for future aerospace transportation technologies. One of the disruptive technologies identified is hybrid electric propulsion. The use of electrical machines for aerospace propulsion is not a new concept. Fully superconducting machines have the potential to deliver the step-change in specific torque, power and efficiency capabilities required for large civil transport aircraft applications. However fully superconducting machines are still in their infancy. This paper looks at the electromagnetic design of two different stator design concepts for an AC fully superconducting machine for an aerospace distributed fan motor using a benchmark aerospace specification. A benchmark aerospace specification of 1 MW was chosen and the design of a conventional permanent-magnet machine was used to assess the performance of the two equivalent fully superconducting AC motor designs. The AC fully superconducting machine includes superconducting bulk magnets mounted on a conventional rotor core and an MgB2 superconducting wire wound stator in a non-magnetic core. The paper looks at a fully superconducting air-cored stator design to reduce weight and a new yokeless stator design is proposed to reduce the armature losses. The paper will look at the key design issues of the different motor designs in relation to the current aerospace targets for efficiency and power densities.

Superconducting fault-current limiters are being considered as a potential technology for restricting fault current to acceptable levels without extensive and costly network asset replacement. Such an issue currently arises primarily from the connection of a distributed generation. This paper first investigates the fault studies of an active medium-voltage distribution network with several superconducting fault-current-limiter deployment strategies and then considers their impact on circuit-breaker transient recovery voltage. These circuit-breaker characteristics at various voltage levels have been studied, and it is demonstrated that the superconducting fault-current limiter is capable of reducing both the magnitude and the rate of rise of the transient recovery voltage.

In order to minimise the environmental impact of increased air traffic substantial developments in civil aircraft electrical power systems must occur. NASA have set a target to reduce noise by 71dB, NOx emissions by 80% and fuel consumption by 60% for the N+3 generation of aircraft entering into service sometime between 2030 and 2035. Turboelectric Distributed Propulsion (TeDP) is expected to enable these goals to be met. NASA's N3-X concept aircraft comprises gas turbine engines which drive electrical generators and a DC network distributes power to an array of fans, which provide thrust. Interconnection and protection technologies will also be included to achieve desired levels of reliability of supply to the propulsion motors. This paper outlines the architecture of a generic TeDP system, explores its benefits, describes technical challenges that will need to be overcome and discusses the technical implications of implementing TeDP with regards to electrical system power density and safety.

The design of a line-start rim-driven induction motor specifically for use in a marine propulsor/thruster is described. This paper explores the use of a hybrid ‘canned’ induction rotor design in which a conventional ‘deep-bar’ cage is replaced by a simple cage with a low radial depth, along with a series of air-gap cans to provide environmental shielding, and a conducting rotor can to simplify the rotor design. An overview of the design process to the ‘final’ design for the proposed induction rim-drive is explained, along with details of the two-dimensional finite element models and simulation results. An appraisal of the merits of the rim-driven design, compared to a benchmark industrial induction motor, is also discussed.

Superconducting machines offer the significant advantage of smaller volume, lighter weight, and increased operating efficiencies compared with traditional electrical machines. To date, superconducting machines have utilized a superconducting dc field winding on the rotor of a synchronous machine. This increases the system complexity because it requires cryogenic cooling on the rotating part of the machine. The stator in these machines is generally composed of a set of conventional ac copper wire coils. Round magnesium diboride (MgB2) wire however has the potential to form low-cost ac stator coils for a superconducting machine. This could enable a stationary superconducting ac stator winding to be fabricated, reducing the complexity associated with the cryogenic cooling. This paper presents initial test results on a prototype ac solenoidal coil to represent a typical ac stator coil for a superconducting machine using MgB2 wire. The diameter of the wire with insulation was 1 mm and the coil was wound in a double-layer solenoidal arrangement. The magnetic flux density distribution, quench current level, long duration operating current level, and the ac losses of the coil were measured and discussed. This paper demonstrates the potential of MgB2 wire to develop a superconducting ac stator winding for a superconducting machine.