Abstract This paper introduces a new concept for surface mount technology (SMT) automated manufacturing of power converters ¿ PCB Power Sandwich. The Power Sandwich manufacturing method employs new x-dimension (x-dim) components, having the same height (x) and double sided SMT electrical terminations. The components are stacked between planar substrates and soldered on both, top and bottom sides using the multilayer Power Sandwich assembly process. By arranging the components in different stack layers an increase in power density, better heat removal and improved EMI performance of power converters can be achieved. New x-dim components enable fully SMT automated power converters manufacturing with short production time and low assembly cost.@en

Abstract High speed electrical machines are central in replacing existing systems in aircraft with electrical counterparts. An integrated, fault tolerant, permanent magnet machine and drive is considered. Aerospace systems require high power density and high reliability from systems. Availability may be increased by adding fault tolerance to the system design and power density may be increased by integration of subparts. Much design flexibility can be found when system subparts are designed jointly. To aid system integration losses are to be kept low. This can be done by selection of a topology which yields low losses, amongst other factors. A three phase inverter and full bridge inverters with bipolar PWM, unipolar PWM and Phase Shifted Full Bridge topologies are investigated, for which switching and conduction losses are calculated. Low frequency modulation is shown to be possible with the use of a Phase Shifted Full Bridge topology. This strategy also enables the use of IGBT devices in high speed machines where switching speeds limits the power level and rotational speed of such fast rotating machines.@en

At the hand of a case study alternative energy sources, methods of transportation and their effect on the electricity grid once fossil fuels have been depleted is discussed. Three methods of sustainable transport are presented. The energy requirement for each is calculated as well as the requirements from the electricity grid for traveling a 200 km route. All three proposed methods are compared to current methods of transport. Specifically, the Superbus, an all electric vehicle, has also been considered as an alternative to future transport. The results obtained indicates that the Superbus is the better option regarding energy requirement from the electricity grid, while at the same time traveling at high speeds to make point to point transportation fast.@en

High speed electrical machines are replacing existing subsystems in aircraft. Electrical drives need to have high availability and good power density to be considered a viable replacement. To achieve high availability fault tolerance is added to the system design. Power density is increased by spatial integration of subparts. Fault tolerance extends to both machine and power electronics design. By use of low frequency modulation in a high speed, multiphase, fault tolerant drive, losses are reduced. High efficiency and power density result. The air cooled converter will be subjected to varying atmospheric conditions during flight. Low air pressure reduces cooling capacity at high altitude and requires increased air velocity to keep temperatures stable.@en

The integration of an electrical machine and power electronics promises many benefits, the largest being an increase in power density. The use of system integration may lead to an increase in loss density and local or component temperatures. For this reason much attention needs to be paid to the thermal design aspects of the system. In the aerospace industry weight and reliability are of significant importance. In this paper the integration of a permanent magnet machine and power electronics into a single structure with joint thermal management is investigated. An overall goal of 2 kW/kg is set for system power density. Additionally in this paper fault tolerance is introduced into the design. This will allow the system to continue functioning should a single electrical fault occur. Principle faults are identified and discussed. A 50 kW, 6 phase, 8 pole permanent magnet machine is presented with a rotor speed of 50 krpm. A symmetrical phase shifted full bridge is used to drive the permanent magnet machine, aiding the functionality of fault tolerance and enabling the use of soft switching. A mathematical model for both machine and power electronics is created and used to calculate phase currents and losses in the machine and power electronics. Finally, spatial integration and thermal management concepts are presented and analysed.@en

Electrical machines used in aerospace applications require fault tolerance to ensure high availability. This frequently includes partitioning, increasing the number of machine and drive phases. Fitting every partitioned phase with a localised controller increases the autonomy of each phase. Using the magnetisation of the rotor as reference, minimal communication between phases is required. An overhead controller is used for open loop startup. Due to the high rotor speed, sensorless control is implemented to avoid reliability problems with encoders. Low frequency commutation is used to lower computational effort and converter loss.@en

The use of concentrated windings in electrical machines leads to significant rotor losses due to severe space harmonics in the airgap. Metallic retaining sleeves and sintered magnets used in high speed rotor construction have low electrical resistivities, leading to larger associated eddy currents loss. Composite materials like carbon fiber and plastic bonded magnets are investigated, due to their relative low conductivity. Analysing eddy current loss in composites can be cumbersome as they are frequently anisotropic. By observing eddy currents induced in a sample material, the material resistivity may be derived for a given direction by reverse finite element modelling. Resistivity values may be further used to calculate rotor eddy current loss.@en

Fractional pitch, concentrated winding machines are recently enjoying attention due to their suitability as basis for fault tolerant machine designs. The concentrated nature of the armature current distribution yields significant rotor eddy current loss production due to the harmonics present in the airgap, leading to significant rotor loss in high power and high speed machines. By using carbon fiber for the retaining sleeve and plastic bonded magnets for rotor magnetization, rotor eddy current loss may be reduced. Both materials require certain tradeoffs between electrical, mechanical and magnetic properties but their high electrical resistivity makes them attractive for use in high speed, fault tolerant, electrical machine design.@en