Analysis and Design of DC System Protection Using Z-Source Circuit Breaker

A modified Z-source breaker topology is introduced to minimize the reflected fault current drawn from a source while retaining a common return ground path. Conventional Z-source breaker topologies do not provide steady-state overload protection and can only guard against extremely large transient faults. The Z-source breaker can be designed for considerations affecting both rate of fault current rise and absolute fault current level, analogous in some respects to a thermal-magnetic breaker. Detailed analysis and design equations are presented to provide a framework for sizing components in the Z-source breaker topology. In addition, the proposed manual tripping mechanism enables protection against both instantaneous current surges and longer-term overcurrent conditions. The fault operation intervals of the proposed Z-source breaker topologies are both demonstrated in SPICE simulation and validated in experimental characterization.