SiC JFET Parallel Connection And Its Application In Self-Powered Solid-State Circuit Breakers

In the DC power distribution system,the circuit breaker is an important device to protect the circuit safety.When the circuit system has a short circuit fault,the circuit breaker can quickly disconnect the fault circuit and protect other equipment on the circuit.As early as the 1970 s,a circuit breaker based on power semiconductor device appeared in the big family of circuit breakers.The main switch of the circuit breaker is a power semiconductor device instead of a mechanical switch,so it is called a solid-state circuit breaker.Solid-state circuit breakers attracts the attention of electrical engineers because of its small size,fast action speed,no arc and so on.At the beginning of the development of solid-state circuit breakers,the main switches of solid-state circuit breakers is mainly power semiconductor devices based on silicon(Si)materials.With the increasing operating voltage of DC distribution system and the higher requirements of users for power quality,the disadvantages of power semiconductor devices based on Si materials are increasingly prominent,such as low withstand voltage,high loss,low junction temperature,and so on.This has caused users can't avoid to rethink the use of solid-state circuit breakers.As a typical third-generation semiconductor material,silicon carbide(SiC)material has the characteristics of large forbidden band width,high electron drift saturation speed,small dielectric constant and good electrical conductivity.It is widely used in the development of power semiconductor devices,so it is based on power semiconductor devices of SiC materials have excellent properties and create space for improving the performance of solid-state circuit breakers.This paper introduces a self-powered solid-state circuit breaker whose main switch is a normally-on SiC JFET and the protection drive circuit is a self-excited flyback transformer circuit.The main switch of the circuit breaker is directly connected in series in the main circuit,the input end of the protection drive circuit is connected in parallel with the drain source of the main switch,and the output end is connected to the gate source of the main switch to provide a driving voltage to the main switch.Unlike the previous solid-state circuit breakers,the working energy of the self-powered solid-state circuit breakers conmes from short-circuit faults and does not require additional auxiliary power supply.The working principle of self-powered solid-state circuit breaker is analyzed in detail.The simulation circuit is built by LTspice simulation software to verify the feasibility and rationality of self-powered solid-state circuit breaker.Based on the simulation,the experimental platform is built,the optimal scheme of parallel design is explored.In the optimal scheme,10 SiC JFET parallel experiments are carried out,and the turn-off current value of 670 A is obtained.Finally,the factors affecting the operating speed of the circuit breaker are explored.The obtained results have certain reference value for the design of high-power solid-state circuit breakers.