A passively cooled 15 kW, 800 V DCDC converter with a peak efficiency of 99.7 %
In this paper a non-isolating high voltage (800 V) bidirectional DCDC-converter with a so far unreached efficiency of up to 99.7 % is built and tested in detail. In order to reach this goal, a SiC-MOSFET half bridge is switched at its technical maximum switching speed (200 V/ns) using an extremely low inductive switching cell. This fast and low loss switching cell is attached to a large and highly efficient custom made inductor and operated at relatively low switching frequencies of 10 to 20 kHz. An unrivaled small dissipation energy (21 W at an output power of 7.5 kW) allows the abandonment of any active water cooling, fans or cooling fins and can, just as it is, be used in almost any environment. This technique does not only save a lot of space and costs for thermal management, it can also decrease the operating costs for electric vehicle charging stations by cutting the wasted and non-saleable dissipation power by an order of magnitude.