Electro-thermal Design of a Solid-State MVDC Circuit Breaker

This paper investigates the impact of several design parameters on the electro-thermal performance of a solid-state circuit breaker (CB) for medium voltage DC (MVDC) grids. The parameters studied are the cooling system design along with the ambient temperature under steady-state. The impact of the current limiting inductor and the threshold current that trips the breaker on the CB operation under short circuit condition was also investigated. The performance of the breaker is evaluated in terms of conduction power losses, dissipated power and junction temperature in the power electronic devices used. Four electro-thermal models for heat flux and junction temperature estimation have been developed and presented. The simulations highlighted the superiority of the "RC" equivalent thermal network in terms of required computational time and accuracy. Finally, the importance of designing the breaker according to the electrical and thermal limitations of the power electronic devices used is also highlighted.