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One possibility for onboard electricity generation in a hybrid vehicle is a free piston engine incorporating an integrated linear generator. This paper presents the modelling and development of the linear engine generator concept, where a linear electrical machine is physically integrated within a free piston engine. Details and results of a multi-physics simulation of this concept are given, with a focus on the design of the electric machine. It is shown that a short translator design can result in the highest power density. This also gives the opportunity for integrating the electric machine physically within the compressor. Details of a prototype demonstrator of the resulting generator-compressor are given.

This work presents a new wave energy converter power take off (PTO) system that combines two recent developments in drive train technology, the consequent pole linear vernier hybrid permanent magnet machine and the linear magnetic gear. The combined system is fully realised in three-dimensional finite element method and compared to a similar direct drive machine. While the resulting system is lighter, reducing the active material mass by 30%, and more efficient, the system requires larger amounts of high cost permanent magnet material and increased PTO complexity. It is summarised that while such a system could be recommended in certain conditions, it is not viable for general application.

This paper presents the testing of an in-wheel permanent magnet Halbach array machine developed for automotive traction. A machine with a Halbach array rotor is experimentally compared to results from a surface mount variant with the same magnet mass and the finite element analysis (FEA) simulations done during its design. A battery emulator and dynamometer is used to mimic the performance in a vehicle. The Halbach version is shown to require between 6% and 15% less current to deliver the same torque across the operational speed range and delivers 20.6% more power during the continuous operation. High static cogging torque was found during testing and an approach to its solution is shown.

Design of direct drive power take off in renewable energy generators tends to focus on force density, naturally leading to the use of relatively expensive permanent magnet machines. Elsewhere in the industrial landscape, induction machines traditionally rule as they are low cost and robust. In this study, the design of a generator for use in an open centred tidal turbine is presented as a case study to directly compare induction and permanent magnet machines. Mechanical constraints in the turbine design enforce a large magnetic gap in the generator, which inherently limits the power density and power factor. A comparison between the permanent magnet design and the induction design in terms of performance and economy has been presented.

More electric is a platform being widely adopted by the current generation of aircraft. It offers significant benefits in terms of fuel savings and flexibility of airframe design but relies on the development of torque dense machines. This paper documents the development of an air-cooled transverse flux machine for use in short-haul aircraft to improve on-ground operational efficiency. If its potential is to be realized, this topology of the machine comes with a new set of manufacturing challenges. Two competing machine layouts with different approaches toward their fabrication are discussed. Experimental results and experiences gained from overcoming the challenges of building the machines are presented. A combined phase topology with soft magnetic composite core-back is shown to give a better rated torque, whereas a separate phase bent lamination concept gives better overload capability.

With the increased electrification of aircraft, the use of motors to replace traditionally mechanical or hydraulic auxiliary systems has increased. Aerospace motor design has the rather unique characteristics of mass and torque density being extremely important, whereas cost is less so. For low maintenance, non-safety critical components, which are only used for short durations of the flight cycle, efficiency also becomes less important, whilst eliminating an external cooling circuit and gearbox can look very attractive. In order to meet a stringent mass target, this paper considers two high torque density machines suitable for low speed applications. As mass is reduced, thermal capability becomes critical and thermal simulations are presented for operational characteristics.

This paper investigates magnet topologies and their susceptibility to demagnetisation in an in-wheel motor for an electric vehicle. The analysed motor is a high torque density, low speed, surface-mounted permanent magnet (SMPM) modular motor with fractional slot concentrated winding (FSCW) and an outer rotor. The rich spatial stator MMF harmonics present in the air gap have two effects: they generate AC losses in the magnets and they can increase the peak demagnetising field which the magnets experience. In this work, methods are first developed to give greater insight into the magnet loss mechanisms, thereby indicating when magnet segmentation is beneficial. The methods are then extended to examine how different rotor designs are affected by both loss and demagnetisation fields, showing major differences between rotor topologies.

This paper describes a motor for use within the wheel of an electric vehicle. It demonstrates the influence of various rotor parameters on an outer rotor permanent magnet motor (ORPM) with Surface-mounted magnets (SM). The aim of this paper is to reduce the magnet volume, while maintaining the torque performance through the complete operating range. Six different magnet topologies are investigated firstly. Then, Semi Surface-mounted Permanent Magnet (SSPM), I shape tangential PM (IPM) and V shape interior PM (VPM) designs are compared in terms of torque capability at certain magnet volume. The VPM gives highest torque performance. The iron shielding concept in VPM can protect the magnets from the opposing armature flux, thus providing increased resistance to demagnetisation, and hence permitting thinner magnets. Furthermore, a new slot/pole combination with higher torque capability has been studied. However, due to the increased inductance, motor with V shape design needs to work at a poorer power factor and consequently a reduced speed range for a given inverter. Lastly, Cost effective and simple manufacture method of the VPM rotor is also addressed with consideration of mechanical feasibility.