Increased Short-Circuit Capability of SiC-MOSFETs by Gate-Drive Unit

Inhalt:
High-power MOSFETs, especially silicon carbide devices, can be operated at high gate-source voltages to reduce the RDS-on further which results in a lack of short-circuit capability. Moreover, high-speed detection of a short-circuit and turn-off is necessary to avoid thermal destruction. Within this paper, a two-step gate-drive unit is presented which reduces the gate-source voltage to a safe level when an abnormal di/dt occurs. With this lowered gate-source voltage a desaturation and a normal turn-off of the device is possible. This increases the short-circuit capability drastically while the RDS-on is still low. The paper shows short-circuit-measurements of different types. Concerning the reliability of power converters, the short-circuit-protection of the belonging semiconductors is rich in significance.