A Bi-Directional Dual-Input Dual-Output Converter for Voltage Balancer in Bipolar DC Microgrid

Abstract

Bipolar DC microgrids (BDCMGs) have several issues related to the voltage and require numerous converters to supply power to both poles. To solve these issues, a bidirectional dual-input dual-output (DIDO) converter is proposed for the voltage balancer in BDCMG. The DIDO converter has dual-input sources and a dual-output port connected to the grid. Additionally, the DIDO converter simultaneously performs independent bidirectional power control and voltage balancing control. Based on the input voltages, this paper proposes modulation methods for three cases. The modulation method of the second case has a wide operating range and low balancing current ripple without increasing the switching frequency. Moreover, only voltage balancer mode without active input sources is proposed, considering the intermittent source. Therefore, it can operate as a voltage balancer under all conditions. The voltage balancing performance of the three cases was analyzed. Finally, the proposed modulation and control method of the DIDO converter were verified through experimental results.

Keywords

• bipolar DC microgrid
• dual-input dual-output converter
• bidirectional converter
• voltage balancer