Search

We present a simulation study on power device structures based on a dualization of the thyristor equivalent circuit. This dualization results in new power devices, namely, "circuit breaker" and "safe controlled power switch". Both the circuit breaker and the safe controlled power switch can be used to protect against over currents. The circuit breaker exhibits self protection against over currents while the safe controlled power switch with inherent over current turn-off capability is controlled by the MOS gates of the device. These novel power devices have very good on-state characteristics that are comparable to the on-state characteristics of the injection enhancement IGBTs.

We describe the operation and application of a new class of power devices which have regenerative turn-off capability. The presented regenerative turn-off devices are (1) circuit breaker (2) safe controlled power switch and (3) regenerative diode. Regenerative turn-off devices are conceptually "dual" to regenerative turn-on devices like the Shockley diodes or thyristor type devices. Regenerative turn-off devices are normally ON and enable current flow until a certain current/voltage level above which the regenerative turn-off action starts. Therefore, they can be developed as circuit breakers, safe controlled power switches and regenerative diodes. Regenerative diodes are "normally open" and block at small reverse current/voltage levels (Vemulapati, 2007). Regenerative turn-off devices can be realized from a series connection of normally ON type JFETs which are connected as controlled source ballasts. Full gate controlled device (safe controlled power switch) can be obtained with the addition of MOS gates to the circuit breaker. High injection (thyristor) versions of the circuit breaker and safe controlled power switch can be developed and they exhibit good plasma concentration which is comparable to that of the advanced IGBTs (Rosensaft, 2007). Regenerative diode can also be developed from the basic structure of a Dual Thyristor which has a low or neglectable threshold voltage and closes at reverse polarity. Regenerative diode is superior compared to Schottky diodes and junction barrier controlled Schottky (JBS) rectifier both in forward and reverse directions (Vemulapati, 2007), but of course, requires a more complicated technology. JBS rectifiers are obtained with a good compromise between p-n and Schottky diodes (Baliga, 1998). Though regenerative diode has inferior on-state behavior when compared to that of the synchronous rectifier, it does not require any external triggering.