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Title: High speed electrical machines for the more-electric engine
Author: Gerada, David
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 2012
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With the increasingly stringent emissions legislation as well as the hiking fuel prices, engine electrification is currently a prime path for automotive companies to meet the environmental and efficiency targets, thus placing the need for high-performance automotive electrical machines. This research looks at developing high-speed electrical machines for an electrically-assisted turbocharger to be used within Cummins' heavy duty diesel engines. While the potential benefits of such a system are high, integrating a high speed, high power-density electrical machine within the aggressive turbocharger environment is challenging. In this work detailed system multi-domain models which include the electromagnetic, thermal and mechanical aspects are developed. Using these models, together with knowledge of electrical machine material properties, the capabilities and limitations of different types of electrical machines for use in electrically-assisted turbo-charging are determined. The field weakening properties, robustness and relatively low-cost make the Induction Machine the preferred technology for the application. This work provides a set of design guidelines for maximising the power density of high speed Induction Machines. In particular moving away from the conventionally used round rotor-bar and tailoring the split-ratio together with tailoring the machine IS electrical and magnetic loadings are shown to be important aspects in increasing the power density. An algorithm for increasing the power-density of high-speed induction machines is presented. Design recommendations are also presented for PM machines where tailoring the air-gap length is identified and shown to be important in optimising the distribution of losses. A computationally-efficient PEA-based technique is developed for the analysis of closed rotor-slot IMs. The optimized 9.5kW, 50000rpm IM design is prototyped and experimental results compared to those predicted from analysis.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available