Dimensioning of a Three Level Flying Capacitor DCDC Converter for Fuel Cell Vehicles

Three Level Flying Capacitor Topology enables the use of semiconductors with 650 V blocking voltage in DCDC converters for fuel cell vehicles with 800 V system voltage. When the specification demands operation with constant output power, scopes can be utilized for a dimensioning which can partially compensate disadvantages of this topology. In this paper, the focus is set on the use of super junction MOSFETs and their switching behavior in a design with discrete transistors and integrated capacitors on an insulated metal substrate (IMS) board, which is used for first tests for validation of the usability of the chosen semiconductors. A module structure with low inductive commutation loops was selected and verified by measurement of the stray inductances and the switching behavior in boost and buck operation.