Design of Powder Core Motors

The goal of the study presented in this thesis is to evaluate the advantages and drawbacks of using powder technology in the design of the iron core of small claw-pole electric motors. The use of soft magnetic composites (SMC) and compaction technology allows the creation of complex 3D iron cores. The additional dimension opens for new solutions of the electromechanical energy conversion. A claw-pole motor among the transversal flux machines that has particularly high specific torque is in the focus of research interest. Generally, as the iron core can be more complicated, the winding is chosen to be simpler in the powder core motors. The thesis focuses on the machine design of a single-phase and a two-phase low-power claw-pole motor. The predicted results compare well with measurements of the prototype motors. The motor design process in this thesis uses a magnetic equivalent circuit (MEC) model of the outer-rotor claw-pole motors that is accurate enough to describe the physics of the electromagnetic conversion. Additional equivalent circuits are made to evaluate the mechanic and thermal loading of the machines. The outcome of the equivalent circuit models is enough to estimate roughly the optimal size of the motor and the motor output according to the materials selected. After the rough design process, which is based on equivalent circuits, is finished, a series of FE magnetostatic analyses are made in order to evaluate the static characteristics of the motors, to specify the magnetization losses and to carry out a sensitivity study for the proposed size of the motors. Finally, the magnetic, mechanic and thermal design is analyzed dynamically and statically by the use of coupled multiphysics. The task of the coupled multiphysics is to find out the cooling capability and the thermal limit of the motor as well as the mechanic stress in the motor parts due to magneto-mechanic loading. It is discussed how the discrepancy between the calculated and measured cogging torque depends on the fineness of the 3D FE air gap mesh. Iron loss estimation based on the results of the FE-analysis is made taking the local rotation, and not only pulsation, of the magnetic flux into consideration. It is shown that the loss coefficients in the material model must be adapted to account for flux rotation. A part from the output of the machine as an electromechanical energy converter is their controllability in the electric drive system. Based on the static characteristics, which are calculated in the FE-analysis and verified in prototype measurements, a tailor made control method is developed for the machines designed. Results are presented of extensive simulations and experimental verifications of the proposed control strategy and power electronic circuitry. The high-speed four-pole single-phase motor shows satisfactory results. The other motor, which has 20 poles and two phases, has a main weakness in its complex assembling and a large cogging torque

Multidisciplinary assessment of a year 2035 turbofan propulsion system

A conceptual design of a year 2035 turbofan is developed and integrated onto a year 2035 aircraft model. The mission performance is evaluated for CO2, noise and NOx and is compared with a notional XWB/A350-model. An OGV heat exchanger is then studied rejecting heat from an electric generator, and its top-level performance is evaluated. The fan, the booster and the low-pressure turbine of the propulsion system are subject to more detailed aero design based on using commercial design tools and CFD-optimization. Booster aerodynamic modelling output is introduced back into the performance model to study the integrated performance of the component. The top-level performance aircraft improvements are compared to top-level-trends and ICAO estimates of technology progress potential, attempting to evaluate whether there is some additional margin for efficiency improvement beyond the ICAO technology predictions for the same time frame

Unconventional Magnetic Actuators for Automatic Transmission Shifted by Wire

This report has its focus on development of an unconventional magnetic actuator for vehicular application more specific for gearbox actuators namely: Automatic Transmission Shifted by Wire (ATSbW). The application requires a compact an inexpensive electrically actuated drive that provides high torque over limited angle of movement. The specific research focus of this project is related to development of a novel and unconventional solution for a transmission actuator. The central part part of the system is an electromagnetic actuator that either directly performs the system requirements or is integrated into a mechanical transmission such as harmonic drive, cycloid gears, etc, to complete the task. Even though the project is connected into vehicular application it has bearing in robotics, mechatronics and so forth and on

Aerospace electric generator design considerations

This article explores four preselected permanent magnet synchronous machine (PMSM) topologies suitable for direct mounting on low pressure spool in a turbo fan engine. The challenge of contributing to More Electric Engine (MEE) development is that the electrical machine needs to operate over wide speed range, take advantage of available space that forces to use a high number of poles and last but not least a high-power density is anticipated. The initialization of these PMSM topologies fulfills the space requirements, evaluates and compares different core materials, FeCo and FeSi, and addresses mechanical load and cooling integration aspects. The design goal is to find affordable and rational set of materials and manufacturing methods in combination with machine characteristics that suits the best for the mission. It is found that PMSM with FeCo core with distributed winding and Halbach magnet arrangement would meet best the low ripple, high efficiency and power requirement while concentrated winding machine would provide appealing option of individually controlled direct cooled hollow conductor coils for better thermal management