Solid-State Circuit Protection Using SiC JFETs
Modern power electronics are growing in both power capacity and density, making circuit protection more important than ever. There's increasing interest in solid−state circuit breakers and power controllers, especially those using wide-bandgap (WBG) semiconductors like silicon carbide (SiC).
SiC JFETs have shown themselves to be well-suited for the task, given their low on-state resistance at high voltage ratings without compromising the ability to limit current.
Solid-state circuit breakers fall roughly into two categories: hybrid breakers and completely solid-state breakers with no mechanical parts. A major advantage of solid-state breakers is that they can interrupt current nearly instantaneously, rather than in the milliseconds needed for mechanical breakers. This is very important in cases such as interrupting power sources with very low internal impedance, like electric-vehicle (EV) batteries. They can also interrupt DC circuits without the need for elaborate arc-prevention measures.
The absence of moving parts and degradation of contacts is another major benefit, although solid−state circuit breakers do have higher resistance than mechanical contacts. As the voltage rating of the semiconductors rises, so does the resistance, directly impacting the cost as the voltage class of the breaker increases. WBG semiconductor switches have lower on-state losses and higher efficiency during normal operation compared to silicon-based semiconductors.
