Inrush current reduction technology of DAB converter for low‐voltage battery systems and DC bus connections in DC microgrids

Abstract

Low-voltage battery energy storage system and dual active bridge (DAB) converter control method for DC bus connection in DC microgrid. To use power efficiently in a DC microgrid, power must be easily transferred in both directions. DAB converters can easily transfer power in both directions using only the phase shift of the gate at 50% fixed duty on the primary and secondary sides. In the transient state, however, an overcurrent occurs to charge the output capacitor. A soft start algorithm is used to overcome this overcurrent problem. In the conventional method, the control complexity and response characteristics are slow because the duty control is included and the algorithm is performed in several stages. In this study, a gate drive circuit is constructed using a pulse transformer for 50% fixed duty control and short circuit protection. A soft start control algorithm is proposed, including a first-order phase shift scheme for the stable soft start at 50% fixed duty. The 3 kW prototype DAB converter is designed and implemented for bidirectional power conversion testing. The experimental results show that stable power transfer is achieved in the initial transient state through bidirectional output control and soft start.

Optimal Tuning of Fractional Order Controllers for Dual Active Bridge-Based DC Microgrid Including Voltage Stability Assessment

“…Several research activities have been focused on the control techniques of the DAB during the past few years, see [1][2][3][4][5][6][7][8][9][10][11][12][13]. A comprehensive overview of different modulation strategies of DAB converters is presented in [1].…”

“…The authors of [7] proposed a simple phase-shift modulation technique based on the parabolic carrier concept that has been implemented digitally through Verilog and hardware digital circuits. Investigators in [8,9] suggested several modulation methods for the DAB converter to avoid transformer saturation.…”

“…In Reference [7], the DAB converter average and small-signal models have been validated through both simulations and experimental tests for the four different control modes. The DABs have also been the object of study in [9][10][11][12][13][14][15][16][17][18][19][20]. Even though several control strategies have been explored for the DAB, the most common among practitioners is the simple phase shift modulation technique [17,18] based on conventional PI controllers [20,21].…”

Simple low‐cost ZVS bidirectional forward converter with phase shift control and voltage matching for low power applications

“…In these systems, the energy is transferred between energy storage elements like batteries and a DC bus. Many isolated bidirectional DC–DC converters are presented in the literature for high power applications with many switches and complex control [3–9]. Some of them like dual active bridge converters operate under soft switching [8, 9].…”

“…Many isolated bidirectional DC–DC converters are presented in the literature for high power applications with many switches and complex control [3–9]. Some of them like dual active bridge converters operate under soft switching [8, 9]. In low power applications, both forward and flyback topologies are employed due to their simple structure [3].…”