GaN-Based Tri-Mode Intelligent Solid-State Circuit Breakers for Low-Voltage DC Power Networks

The purpose of this article is to provide a comprehensive and integrated discussion on the basic concept and general design methodology of a gallium nitride (GaN)-based, tri-mode, intelligent solid-state circuit breaker, referred to as iBreaker. The iBreaker concept explores the use of GaN devices in the low-voltage (<; 1000 V), mΩ-resistance SSCB designs and new SSCB topology and control techniques beyond the commonly used on/off switch configuration in order to integrate more intelligent functions without increasing component count. The iBreaker adopts a distinct pulsewidth modulation (PWM) current limiting (PWM-CL) state in addition to the conventional on and off states to facilitate soft startup, fault authentication, and fault location functions. Key design elements, such as use of wide bandgap (particularly GaN) switches, tri-mode operation, combined digital and analog control, and universal hardware/software architecture, are discussed in detail. In particular, the bidirectional buck topology, changes among operation states, variable PWM frequency control, fault locating techniques, GaN FET hardware, and thermal design are discussed. Two iBreaker prototypes, rated at 380 V/20 A and 1000 V/10 A, respectively, are built and tested to validate the proposed SSCB design concept. 99.95% transmission efficiency, passive cooling, and μs-scale response time are demonstrated experimentally.