Transient DC bias suppression strategy of dual active bridge based on dual integral sliding mode‐direct power control

Abstract

Abstract The transient DC bias current will be generated when the input voltage or load of the dual active bridge (DAB) converter suddenly changes, resulting in the excessive peak value of the inductor current and saturation of the transformer core. An improved three‐phase‐shift (ITPS) strategy based on double integral sliding mode‐direct power control (DISM‐DPC) is proposed in this paper to suppress DC bias current without additional hardware. The proposed ITPS determines the steady‐state phase shift ratio through an inductor RMS current optimisation strategy. The transient phase shift strategy can be determined by the transient DC bias current model, which eliminates the DC bias within one switching cycle and effectively reduces the current impact. In addition, a dual‐loop compensation control method of power inner loop and output voltage outer loop is proposed. Compared with the steady‐state control method, the transient optimisation method of double‐loop compensation control can stabilise the output voltage quickly, effectively reduce the transient impact of the current and improve the dynamic performance of the circuit operation. The experimental results verify the theoretical analysis and prove the effectiveness of the scheme.

Keywords

• dual active bridges (DAB)
• sliding mode‐direct power control (DISM‐DPC)
• transient DC bias