Design Optimization and Control of High-Power Wireless Power Transfer Systems for Electric Vehicle Applications

The employment of power electronics systems is essential in the development of environmentally-friendly electric technologies and more specifically for energy-efficient transportation systems. Given the volume of road transportation worldwide, electric mobility in the form of passenger cars, buses, trucks, etc., is an excellent alternative to conventional vehicles based on internal combustion engine (ICE). Benefits can be achieved regarding the polluting emissions (i.e. exhaust levels and geo-location), vehicle drivetrain efficiency, and fossil-fuel dependency. However, there is still a strong need for high performance electric vehicle drivetrains that are reliable, user-friendly and cost-effective. The main issue that still needs to be tackled, is the heavy and costly battery in an electric vehicle (EV). Moreover, in the EV drivetrains, the battery charging process up to now involves the possession of dedicated cables to connect the vehicle to a supply and considerable down-time to replenish the battery state of charge (SoC). Nowadays, wireless power transfer (WPT) systems are one of the promising charging technologies that cannot only improve the charging process, but also can reduce the on-board battery systems thanks to the introduction of dynamic charging system. This WPT comprises two parts: 1) on-board part (defined as secondary WPT winding and its power electronics interfaces that are installed inside the vehicle) and 2) off-board (defined as primary winding and its power electronics interfaces that are mounted on ground and connected to the grid. There are many design and control challenges; resulting in oversizing the drivetrain system and in low power quality and efficiency that should be overcome and improved. Thus, one of the main objectives of this PhD thesis is to improve the battery charging process by making it more user-friendly and by reducing the charging process and time. This might result in simultaneously re-scaling of the required battery pack in electric vehicles with improved charging concepts. Therefore, the research focuses on the development of wireless power transfer (WPT) systems for the charging and of the propulsion systems of electric vehicles (such electric buses with wirelessly connected picking-up coils) and their charging energy-management strategies. These wirelessly connected picking-up coils are well-known as secondary winding of the WPT system. In addition, this study also includes the investigation of various (plug-in hybrid) electric vehicle drivetrains and their components. Where the literature study phase is followed by evaluation and measurement of the newest generation of electric vehicles. During this PhD research, to optimally design the charging management strategy and to define the technical specifications of a WPT system, advanced vehicle simulation models are developed, fine-tuned and implemented by use of a commercial software package (Matlab/Simulink). With these simulations, insight is gained in the power flows in electric vehicles that might use different energy sources (i.e. batteries, ultra-capacitors, inductive charging systems, etc.). The requirements for electric vehicles (especially electric buses propelled by inductive power transfer systems) are investigated thoroughly by way of simulation. This research also provides the required power and energy levels along the trajectories during driving. Moreover, advanced charging management strategies for the combined use of inductive power transfer systems and rechargeable energy-storage systems like batteries are developed. This serves as a motivation for the dimensioning and configuration of the proposed WPT systems. Dur

Jaar van publicatie:2018

Trefwoorden:Electric Vehicles