Open transistors and diodes fault diagnosis strategy for Dual Active Bridge DC-DC converter

The operation of a Dual Active Bridge (DAB) DCDC converter when one of its power semiconductors presents an open circuit fault is analyzed in this paper. In order to be able to detect this sort of failure, a new diagnosis strategy is proposed. The strategy consists basically of two stages: 1) measure the voltage drop in each power semiconductor in on-state by a proper modification in the driver circuits and 2) feedback the fault signal generated in the drive circuits to the microcontroller to decide the next action. Then, the voltage measured is compared with a reference value to determine if a semiconductor presents an open-circuit fault. The proposed strategy has the advantage that it can be implemented without including additional sensors. Simulation and experimental results are included to validate the theory.