Over the last decade the share of electric vehicles has increased and will continue to increase in the future in order to reduce the carbon footprint by transportation. However, the battery voltage is not standardised and can differ per car model. To reduce the charging time, a high power converter is preferred. Moreover, in order to utilise the car as a storage element and enable the Vehicle to Grid functionality, the capability of a bidirectional power flow is needed. In this master thesis a DC-DC converter is designed for a wide output voltage range, with the focus on a high efficiency. Firstly a literature review is done, where the Dual Active Bridge (DAB) converter is chosen as a promising topology. The rectangular (single phase shift), triangular and trapezoidal current modulation are all investigated. For the actual design, two types of transistors are considered, followed by the design of a transformer and inductor. In the end a prototype according to the design is made and the modulation method is implemented in a digital controller.

The worldwide adoption of Electric Vehicles (EV) has gained momentum in recent years, with more than 30% of all EVs being sold last year. Additionally, a new trend of 800 V battery architectures has appeared to allow for faster charging than the now common 400 V architectures. Future proof charging topologies should, therefore, be able to provide a wide output voltage range. This study investigates how DC-DC resonant power converters can be employed to achieve a wide output voltage range of 150-1000 V for EV charging. After the literature study, a two-stage topology consisting of a LLC converter and Interleaved TCM Buck converter is selected for this purpose. Additionally, the competitiveness of an IGBT based solution is examined in comparison with a SiC MOSFET based solution. An analytical model is created in MATLAB and verified using LTSpice, after which different configurations of the 11kW two-stage converter are compared analytically. This comparison is performed by developing a method to assess the efficiency of a converter based on real-world Charging cycles. A trade-off is made between efficiency and costs. In the end, one stage is equipped with IGBTs in the final design. After this, a PCB is designed and used to implement the prototype of the final design. The analytical and simulation models are verified experimentally using the prototype. The maximum measured efficiency of the converter is 97.66%, with a 95+% efficiency over the complete 150-1000 V range at full power. The obtained efficiency for the 11 kW-400 V Charging cycle is 96.85% and 95.67% for the 11 kW-800 V Charging cycle. The proposed converter in this study thus proves to be a highly efficient charging solution that is capable of charging existing, and future Electric Vehicles.