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Title: Safety improvement techniques for electric vehicle powertrains
Author: Wu, Tianhao
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2020
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An increasing number of Electric Vehicles (EV) are playing an essential role in everyone's life. However, the relevant technologies are still not entirely mature. Notably, the EV safety issues are attracting significant attention from not only the scholars and manufacturers but also the occupants (drivers and passengers) and even the pedestrians. Because the EVs have to be powered by the rechargeable energy systems and propelled by the electricity-consuming power electronics and components, which usually have high voltage and large output power, the corresponding safety problems are very different from those in the conventional Internal Combustion Engine (ICE) vehicles. Important factors that need to be focused on include the electrical safety issues, such as electric shock, electrolyte leakage, reliable powertrain structure and components, high-reliability system control strategies and qualified post-fault and postcrash electrical protection measures, etc. This thesis has analysed particular safety issues and demonstrated the handling strategies to improve the safety level of different types of EVs. Firstly, the relatively comprehensive review work on EV categories, powertrain components and safety problems considered in the international regulatory activities are completed, illustrating the reasons why EVs are not inherently safe and that there are different varieties of aspects that need to be investigated to ensure a higher EV safety level from the professional perspective. Then, aiming at both the Battery Electric Vehicles (BEV) and Hybrid Electric Vehicles (HEV), more reliable techniques are developed for not just normal working conditions but also post-fault and post-crash cases to improve the vehicle safety. In detail, firstly, tri-port converters characterized by faulttolerance capability are designed for the Switched Reluctance Machine (SRM) based HEVs. Secondly, the Uncontrolled Generation (UCG) problems in the PMSM based BEVs are analysed, and an effective suppression method is proposed. Thirdly, a winding-based discharge method is innovatively studied to safely and quickly dissipate the residual energy stored in the power electronics after a Permanent Magnet Synchronous Machine (PMSM) based BEV crashes, which contributes to avoid electric shock in emergencies. Finally, aiming at the normally working PMSM based EVs (regardless of HEV and BEV), a novel model predictive control strategy endowed with simple implementation and optimal control procedures is developed to improve the reliability of the software part as well as the system control performance.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral