A Dual Active Bridge Topology with Increased Voltage Conversion Range

We present a dual active bridge topology suitable for wide voltage range applications covering all combinations of 200 V to 600 V on the input and 20 V to 60 V on the output with constant power of 1 kW. We employ a stepped inductance scheme to adjust the effective inductance of the converter, thus extending the efficient operation range. Using a variable switching frequency between 35 kHz and 150 kHz with operation-point-dependent limits further increases the performance of the converter. A prototype was built and the proposed changes have been compared to a fixed frequency, fixed inductance implementation. Measurements show a maximum loss reduction of 40 %, leading to a peak efficiency of 97 % while maintaining constant output power over the entire working area.