A Novel Dual Phase Shift Modulation for Dual-Active- Bridge Converter

The isolated dual active bridge (DAB) dc-dc converter with conventional dual-phase-shift (DPS) modulation exhibits large variations of currents under a small change of phase shift ratio at light load and larger peak current and reactive power at non-heavy load. To solve this problem, this paper proposes a novel dual phase shift (NDPS) modulation method based on two degrees of freedom under non-heavy load conditions. By redefining the constraints of two inner phase shift ratios and one outer phase shift ratio, NDPS modulation achieves a wider phase shift adjustment range at non-heavy load, and basically eliminates reactive power. By establishing mathematical models of transmission power, the paper introduces and analyzes the operating principle of the NDPS modulation in detail, and provides the operation mode analysis of the converter. Finally, the effectiveness of the proposed method is verified by experimental result.