Analysis, design and optimization of electric vehicle wireless chargers
- Autores: José Manuel González González
- Directores de la Tesis: José Antonio Aguado Sánchez (dir. tes.), Alicia Triviño Cabrera (codir. tes.)
- Lectura: En la Universidad de Málaga ( España ) en 2021
- Idioma: inglés
- Tribunal Calificador de la Tesis: José María Maza Ortega (presid.), Pedro Luis Roncero Sánchez-Elipe (secret.), Zhengyu Lin (voc.)
- Programa de doctorado: Programa de Doctorado en Sistemas de Energía Eléctrica por la Universidad de Málaga; la Universidad de Sevilla; la Universidad del País Vasco/Euskal Herriko Unibertsitatea y la Universidad Politécnica de Catalunya
- Materias:
- Enlaces
- Tesis en acceso abierto en: RIUMA
- Resumen
The transition to a decarbonized economy that many countries have undertaken in recent years has focused closely on sustainable transportation. Governments are backing Electric Vehicles (EVs) as a solution that will help to reduce their countries' carbon footprint. As part of this effort, they provide tax benefits and direct aid to promote the acquisition of EVs in order to meet the objectives established in the Paris Agreement.
Nowadays, one of the biggest concerns of potential users of these vehicles is their autonomy, which is limited both by the capacity of the batteries and by their charging. The charging is currently carried out using conductive chargers, which requires user intervention and raises safety concerns. However, wireless charging, especially magnetic-resonance technology, is considered a real alternative to conductive charging as it provides additional advantages such as greater security and ease of charging. This technology has a very rich field of development to which this thesis has contributed in a number of aspects.
The first of these contributions lies in the analytical characterization of the magnetic field generated by inductive chargers. Although there are several complex tools available to carry out this task, the proposed solution allows the magnetic field to be calculated in a simple way at any position in space. This tool, which has been validated with a 3.7-kW wireless charger prototype, facilitates the design tasks of coils, as well as the control of the exposure of external objects to the magnetic field.
One of the main difficulties that wireless chargers will have to face lies in the future transition to this technology. Wireless technology is expected to coexist with conductive technology. This thesis provides a solution for this transition, proposing an \textit{on-board} charger topology in which a large number of components are shared between both technologies. In this way, we can reduce implementation costs and the weight of the vehicle, thereby improving its autonomy.
Developing prototypes is essential for implementing and analysing new solutions. In view of this, a prototype has been developed for the laboratory with the flexibility to test topologies and control strategies. We have also designed and implemented a final prototype for charging an electric bicycle. All the design stages have been taken into account when developing this latest prototype, from the coils to the power electronics, which are regulated to operate following a constant current/constant voltage (CC/CV) strategy. The use of a real vehicle has allowed us to propose and evaluate an analytical model to quantify the impact of the position of the secondary coil.
The charging strategy is not the only relevant aspect that controllers must monitor. The operation of the chargers outside their nominal conditions, such as in the case of misalignment between coils, produces an increase in some electrical variables of the circuit that must be controlled. This problem has been analysed in depth in order to develop a control that limits the most critical variables and prevents damage to system components.
The control of wireless chargers also affects efficiency, which will play a fundamental role in the adoption of this technology as it is the main disadvantage compared to conductive chargers. The final contribution of this Thesis focuses on this aspect, for which a model predictive control (MPC) is proposed. The control maximizes efficiency by simultaneously adjusting variables such as the operating frequency, the phase shift angle of the inverter and the equivalent resistance of the battery.
