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Green technologies have recently gained interest for many reasons. Economic factors in conjunction with an increased social desire to reduce our environmental impact on the Earth have created a desire for more environmentally friendly technologies, especially automotive technologies such as the electric car. While public interest in electric vehicles is growing, there are a number of challenges which must first be addressed before their widespread adoption is possible. Cost, longevity, and range are all important factors which need to be addressed for electric vehicles to compete directly with their gasoline counterparts. By more efficiently using the energy stored within the battery pack, some of these issues can be addressed. This study focuses on the thermal management systems for electric vehicles and the application of design optimization in the early design phase considering the pack in its entirety. A liquid cooling system is considered for a current generation electric vehicle, with time dependent heat generation rates within the battery cells based on vehicle operating conditions. Identifying the most efficient distribution of cooling within the battery pack to achieve uniform temperature is the objective of optimization. Simulations were performed on a complete battery pack model, featuring 288 battery cells and 144 cooling plates. Anisotropic material properties and non-uniform heat generation rates are included as well as energy demands based on a representative vehicle drive cycle. Results have shown that through design optimization, the standard deviation of temperature within the battery cells can be improved by as much as 80% when compared to a conventional design. The standard deviation of temperature saw improvement from an average of 0.2828 K for a conventional design to 0.05318 K after optimization. These results are specific to the given battery pack construction, battery cell, and cooling type. The method of modeling and analysis can be extended to many battery geometries and cooling technologies in the future. Application of design optimization to the problem of thermal iii management system design can yield significant improvements to battery pack thermal management, and thereby incrementally improve the efficiency of electrified vehicles. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2013-10-30 10:49:28.639

Future railway trends require travelling at high speeds without deterioration in the ride quality, but further improvement of the ride quality by optimisation of the passive suspension components has reached its limits. This suggests that active suspensions should be used. Rigorous studies over the past four decades have shown that this technique is able to overcome the passive suspension limitation in terms of improving the overall ride performance of the railway vehicle with the incorporation of additional active elements i.e. actuators, sensors and processors. The work in this thesis investigates a novel method for controlling the actuators within the suspension system, something which has been neglected in previous studies. It is a particular problem because at higher frequencies, when the suspension is providing isolation of the car body from the track irregularities, the actuator must accommodate the suspension movements whilst producing very small forces, otherwise the ride quality substantially deteriorates. Instead of considering more complex active suspension control strategies, which tend to be complex and may be impractical, the performance of the actuator across the secondary suspension is investigated. This research looks into improving actuator technologies for railway secondary suspensions in order to achieve the full benefits of active control. This thesis explores novel methods to improve the ride quality of the railway vehicle through secondary suspension actuator and controller design, with the ultimate aim of integrating this technology into a fully active railway vehicle. The focus of this active suspension research is therefore upon incorporating real actuator technology, instead of the usual assumption of ideal actuators. For meaningful and reliable research a simple, well established active control strategy is used for assessment to highlight the degradation in the suspension performance compared with the ideal actuators. Preliminary investigation demonstrates significant degradation of the ride quality caused by real actuators in the secondary suspension, and this research looks at methods to reduce this effect. Including actuators within a secondary suspension system is a difficult actuator problem compared to the normal application of actuators such as position control. This is because the actuator controller design process requires the consideration of the interaction of the vehicle suspension. The actuators that have been identified as suitable for the application are the electromechanical and servo-hydraulic types, and these are incorporated across the secondary suspension. The effects of the actuator dynamics have been analysed. Practical classical controllers are used to provide force-feedback control of both types of actuator in the secondary suspension. A variety of actuator control techniques are considered including: optimisation of the actuator controller parameters to solve the multi-objective and multivariable problem, the introduction of feed forward techniques and the use of optimal control approaches.

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