Year

2024

Degree Name

Master of Philosophy

Department

School of Electrical, Computer and Telecommunications Engineering

Abstract

Due to pressing environmental issues like energy shortages, pollution, and noise, electric vehicles (EVs) have gained significant momentum globally. To address these challenges, EVs are favoured for their simple structure, environmental friendliness, and high efficiency. One critical component in EV architecture is dual clutch transmission (DCT), which preserves the functionality of the traditional manual transmission and demonstrates the advantages of high transmission efficiency as well as almost no power interruption during the shifting process. Studying DCT is essential because it enhances the overall performance of EVs. Consequently, DCT has become a popular choice for automatic transmissions in EVs. As public demand for economic efficiency, dynamic performance, and comfort in EVs rises, optimizing these aspects becomes crucial. In order to advance the performance of EVs, this thesis investigates two speed DCT which is designed for EVs with a focus on the gear optimisation and shifting control.

The investigation of gear optimization and shift control in this thesis is divided into several aspects. In terms of gear optimization, the selection and design of gear ratios play a significant role in influencing vehicle performance. Firstly, by investigating driving cycles that directly reflect road conditions and vehicle capabilities, an approach is proposed to determine the ranges of gear ratios and vehicle parameters. Secondly, an objective function has been established, considering several objectives including acceleration time, power demand under the selected driving cycles, and the sum of average motor efficiency. Subsequently, ant colony optimization (ACO) has been applied to determine the optimized gear ratios based on the designed objective function. It is validated that the optimization has been effective by comparing the optimized ratios with the original ratios.

Regarding the shifting control, the research on the gear shifting can be divided into the study of the gear shifting schedule and the shifting process in this thesis. The gear shifting schedule refers to the design of the gear shifting rules that govern the decision to perform a gear shift. With respect to the study of the gear shifting schedule, in this thesis, the traditional gear shifting schedules that are predominantly applied to two speed EVs have been studied, and these gear shifting schedules are the dual parameter gear shifting schedules in terms of economic and dynamic perspectives. However, these shift plans have apparent limitations in that they only consider some perspectives and do not take into any account the driver's intention. In this study, a three-parameter shifting schedule was developed employing Takagi-Sugeno (T-S) fuzzy control based on the driver's intentions. The proposed shifting schedule incorporated the driver's intentions, vehicle operational velocities, and motor torque. When compared to the traditional two-parameter shifting schedules, it was found that the shifting schedule developed in this thesis demonstrated the improvement in terms of economic efficiency.

FoR codes (2008)

0906 ELECTRICAL AND ELECTRONIC ENGINEERING, 090602 Control Systems, Robotics and Automation

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Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.