Enhanced Modulation Strategy for a Three-Phase Dual Active Bridge—Boosting Efficiency of an Electric Vehicle Converter

Three-phase dual active bridge (3p-DAB) dc-to-dc converters are typically avoided in low-power applications especially for wide voltage and power ranges. Even so, the 3p-DAB do offer a means to reduce filter costs and volume. The aim of this study is to propose the triangular and trapezoidal modulation for the 3p-DAB to address the problem of poor partial load efficiency. The proposed modulation schemes were compared with two conventional DAB concepts. It was found that the efficiency of the 3p-DAB increased substantially. Moreover, the 3p-DAB showed a considerably lower filter volume than that of the single-phase dual active bridge converter (1p-DAB). In conclusion, a modulation strategy combining the two proposed modulation schemes with the phase-shift modulation is ideal, because they boost efficiency and take most benefit from the inherent low filter volume. Ultimately, the three-phase dual active bridge may offer a promising solution to miniaturize galvanically isolated dc-to-dc converters for electric vehicles.