Electric vehicle charger for future DC Grids

Design of a 10kW isolated bidirectional DC-DC converter with wide output voltage range

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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.