Fault‐tolerant DC‐DC converter interconnected with energy storage device for bipolar distribution system: Working modes and optimizing control strategy

Abstract

Abstract DC short‐circuit fault has become one of the major concerns in bipolar DC system operation under complicated conditions. Compared with conventional two‐port DC‐DC converter, fault‐tolerant DC‐DC converter with multiple external ports is evaluated as a preferential choice for high reliability, availability and flexibility required bipolar DC system due to its capability of fault reconfiguration. This article focuses on a type of fault‐tolerant DC‐DC converter interconnected with DC bus and integrated energy storage devices applied in bipolar DC system and theoretical analyses on transmitted power characteristics under bipolar mode and monopolar mode are also carried out in this article. For bipolar mode, the minimized‐peak‐current control strategy is proposed to reduce current stress on switching devices. As for monopolar mode and source‐port fault mode, the fault reconfiguration method and constant‐transmitted‐power control strategy are designed to eliminate fault impaction and achieve the constant transmitted power of output port connected with critical load, by means of power sharing between input port and normal output port or between the normal output ports. Furthermore, intersection of zero‐voltage‐switching (ZVS) operation area under different working modes is depicted with consideration of two optimizing control. Finally, the performance of the proposed fault reconfiguration method and optimizing control have been tested in PLECS environment and experimental prototype to verify the reliability and flexibility.

Keywords

• DC distribution systems
• DC transformers
• DC‐DC power convertors
• fault tolerant control