Static analysis and control strategies of the Single Active Bridge Converter

In this paper, a brief static analysis of the Single Active Bridge, a unidirectional isolated DC-DC converter, is done. In this initial analysis the SAB is operating at a fixed frequency and controlled by varying the duty cycle. Additionally, two variable frequency control strategies are proposed that extends the soft-switching capabilities. This paper focuses on one of them that fixes the duty cycle and uses the switching frequency as the sole control variable. The conduction modes of the converter using the proposed control are analyzed and expressions for the voltage conversion ratio are obtained, which will be used in a design guide that provides ZVS over the full range of operation. A comparative current analysis is performed in which average, rms and switching currents of both control methods are depicted. Finally theoretical, simulation and experimental results are compared with good agreement.