Unison Duty-Phase Peak Current Control for Pole Point Inductor-Based Dual Active Bridge Converter With Zero DC Bias Current

The DC-DC converters capable of high gain with bidirectional capability are used in the grid in conjunction with energy storage systems consisting of fuel cells, batteries, and supercapacitors to support the peak load times. This paper proposes a DC-DC converter having features like high gain, single-stage, bidirectional, and is derived from the reference topology of a dual active bridge (DAB) converter. The proposed converter is called the pole point inductor-based dual active bridge (PPI-DAB) converter. The primary bridge is a boost full bridge (BFB), which is current-fed, and the secondary bridge is a typical full bridge (FB). The gain of the PPI-DAB is twice of a DAB. The converter dynamics are studied by modeling using the generalized averaged modeling (GAM) method. The averaged equivalent circuit, as well as the small-signal model, are derived from the GAM. The converter is designed for an input voltage of 80 V DC and an output voltage of 800 V DC with a power of 1.5 kW. Alongside this, due to different average currents flowing through each of the switches, different drain-to-source resistance of the switches, changes in phase-shift leading to transients, etc., there is an unbalanced volt-second balance equation, which results in a DC bias current in the auxiliary inductor, saturating the high-frequency transformer (HFT). The paper presents a current mode control method to address this issue. The HFT is protected during transients due to the direct current control method. This control strategy is applicable for normal DAB converters where the current DC bias issues are observed. The topology along with the control is simulated in PLECS and the control as well as the functioning of the topology is verified. The control method is then implemented on an experimental setup of a PPI-DAB converter to validate the controller performance. The simulation and experimental results are presented to validate the efficacy of the proposed method for the PPI-DAB converter.