Working principle analysis and control algorithm for bidirectional DC/DC converter

摘要

A bidirectional DC/DC converter is an important part of the DC micro grid system, playing a key role in the stable operation of the system and the coordinated distribution of power. To solve the problem of unstable busbar voltage when the energy transforms bidirectionally in the DC micro grid system, a control algorithm based on closed-loop proportion integral derivative was proposed in this study. The hardware cinarcuit of the bidirectiol DC/DC converter was designed in the DC micro grid energy storage system, and the characteristics of converter efficiency in charging mode and constant voltage output were studied by small-signal modeling of the bidirectional DC/DC converter in charging and discharging systems. Experimental data were used to prove the correctness of the theoretical analysis. The results demonstrate that the current-controlled precision changes steadily in the charging mode when the output voltage is constant and the charging current is adjustable in ranges between 1 A and 2 A. When the charging current is 2 A and the output voltage ranges from 24 V to 36 V, the change rate of the charging current undergoes stable changes. In the discharge mode, when the output voltage is stable, the converter conversion rate changes steadily. When the output voltage changes in the range between 32 V and 38 V, the bidirectional DC/DC circuit automatically switches over the work patterns and maintains the stability of the output voltage. This study achieves bidirectional transmission of energy by rational hardware design of a bidirectional DC/DC converter and improves the reliability of the DC micro grid energy storage system. The proposed method provides a good prospect of a control scheme for the bidirectional DC/DC converter to optimize practical engineering design.