Modular Scalable Power Electronics Building Block Based MVDC Solid State Circuit Breakers

This paper presents a design methodology of modular medium-voltage direct current (MVDC) solid-state circuit breakers (SSCBs) based on scalable power electronics building block (PEBB) units. Regarding the PEBB, 1) isolated gate drive, 2) natural convection cooling and 3) voltage clamping circuit are introduced. There are three major contributions of this paper. First, the PEBB concept is proposed for MVDC SSCB design for the first time. Second, a novel hybrid MOV based voltage clamping circuit is proposed to increase PEBB voltage rating thence enhancing SSCB efficiency. Third, a PEBB parallel packaging method is proposed based on economic analysis of compromise between efficiency enhancement and cost. A symmetrical busbar layout is proposed to ensure parallel switches consistency. A 1.33kV/40A PEBB prototype is successfully implemented, which is experimentally validated by 40A/1hour continuous conduction test and 1.33kV/200A fault interruption test. A 1.33kV/400A power disk prototype is then implemented based on 10 paralleled PEBBs and symmetrical busbar connections. A 400A/1hour continuous dc conduction test is conducted to verify its state-of-the-art 99.98% steady state efficiency, which paves the way for the next generation of high efficiency ultrafast solid-state breakers for MVDC systems.