Advances in Photon Triggered Thyristors for High Current Applications

Abstract

Thyristors are a semiconductor closing switch with inherent low forward voltage drop and high voltage blocking capability. Typically, these devices are turned on with a current pulse to a gate electrode or by a localized light pulse. Both of these methods limit the rate-of-rise of current (dI/dt), especially for high voltage devices. Increasing the gate area results in an increased dI/dt but at the expense of a reduction in the current carrying area. With the advance of light triggering using "leaky" fibers, quasi-uniform illumination of a thyristor can now be realized resulting in high dI/dt for high voltage (>10kV) devices. The large area illumination is accomplished using fiber-coupled diode laser bars.Examples of test circuits and their corresponding current waveforms are shown using large area illumination thyristors (~100kA, ~1MA 2 -sec).

Direct-Triggering LTT With Monolithic Structure

“…LTTs are meant to be triggered using an optical signal instead of an electrical signal [9][10][11][12][13][14][15][16]. However, most LTTs are each composed of two parts, one of which is of low power and the other is of high power, and the two parts are triggered oneby-one in a cascade manner: only after the low-power part is optically triggered ON, is the high-power part electrically triggered into ON state [17][18][19][20][21].…”