Research on Reverse Recovery Process Protection of Thyristors in Hybrid Circuit Breakers

The thyristor devices in hybrid circuit breakers operate under high pulse current conditions, and power breakdown during reverse recovery is an important cause of device damage. In this paper, the thyristor model is used to analyze the changes of voltage, power density and energy accumulation density at both ends of the thyristor device in the reverse recovery process when the protection circuit adopts three protection schemes: RC buffer, Varistor and RC buffer+Varistor. The results indicate that the RC buffer+varistor protection scheme can effectively reduce the voltage rise rate at both ends of the thyristor device and suppress overvoltage. In one pulse cycle, this protection scheme can reduce the peak power density from 188.8 kW/cm
²
to 60 kW/cm
²
, and the accumulated energy density from 0.589J/cm
²
to 0.19J/cm
²
, ensuring the safe operation of the device and improving the reliability of circuit breaker operation. Finally, a test circuit was built and the on-off characteristics of thyristor devices were tested, verifying the effectiveness of the simulation analysis.