Novel Current Slope Control in Dual-Active-Bridge Converter Using Periodic Filters and Direct Access Memory in DSP

Abstract

This paper proposes a new current slope control to reduce the current peak in a dual-active-bridge (DAB) converter. It detects the current slope at two specific points in the DAB converter current and uses the current slope ratio as the control command value. We propose a periodic filter method to reduce CPU load and prevent noise and phase delay by implementing high-speed sampling using DSP's DMA (Direct Memory Access) function. The proposed method is based on SPS (Single Phase Shift) modulation rather than the conventional complex control method. It maintains the phase difference of the voltage across the DAB converter to be minimized. Therefore, since the generation of circulating current is suppressed, reactive power is reduced, efficiency is improved, and the current peak is reduced, thereby decreasing switch conduction loss and the core size of the magnetic component. The proposed current slope control method is applied to a dc-to-dc converter composed of a DAB converter and a non-isolated converter. We verify technical feasibility and excellence through simulations and experiments.