A Time-domain Unified Calculation Model for Power Transmission Characteristics of Dual Active Bridge Topology with TPS Modulation Strategy

Dual Active Bridge (DAB) converter is widely used in isolated DC/DC power conversion systems. Its power transmission characteristics are closely related to modulation strategy including single phase shift (SPS), double phase shift (DPS), extended phase shift (EPS) and triple phase shift (TPS). And common modulation strategies including SPS, DPS, and EPS which can be regarded as special cases of TPS. Various phase shift angle relations and dc voltage gain between dc output and input will affect the system power transmission characteristics. These make a wide variety of mathematical expressions between power transmission characteristics and phase shift angles and voltage gain. This paper presents a time-domain unified calculation model to describe the power transmission characteristics of the DAB converters under TPS modulation strategy. In this model, piecewise functions are used to track the real-time high-frequency voltages of the
$D$
AB converter. On this basis, the current of series inductor current can be determined synchronously. And then, by integrating the product of high-frequency voltage and inductor current, the mathematical relationship between the power transmission and phase shift angles of DAB converters can be derived in a single-cycle. To further optimize the calculation time, an equivalent expression after discretization for the integral expression is given. Finally, a comparison is established to verify the feasibility and correctness of proposed method.