Unified phasor analytical method for dual-active-bridge DC/DC converter under phase-shift control

A unified model for bi-directional dual-active-bridge (DAB) dc-dc converter under all phase-shift (PS) control strategies based on Fourier transform theory is introduced in this letter; and an accurate complex power mathematic model is achieved. Secondly, phasor analytical method is applied to analyze the PS control strategies and the actual control regions of different PS control is proposed. On this basis, the characteristics and power distributions of active and reactive power, corresponding to transfer power and circulating power respectively of PS control, are presented. The boundary conditions of power distribution are in accordance with that of actual control regions. The drawbacks of PS control that the rms current increases, causing current stress and conduction loss, with addition of control degrees of freedom as the active or reactive power specified are described.