Gate turn-off thyristor

Bayne, S. B., et ah, Inductive Switching of 4H-SiC Gate Turn-Off Thyristors, IEEE Electron Device Letters, Vol. 23, 2002, pp. 318-320. 

The power conditioner was an 18-pulse, stepped-wave, gate-turn-off thyristor (GTO) converter manufactured by GE. It was capable of four-quadrant operation, i.e., it was bi-directional and VAR capable. It was configured with three, six-pulse converters which were connected in series on the a.c. side and in parallel on the d.c. side. It was rated at 10 MW, and the input window voltage was rated 1750 Vdc to 2800 Vdc. A Westinghouse monitoring and control system provided the BESS with a highly automated supervisory control and data-acquisition capability [18,19]. 

Reference 2 also describes the on-off characteristics of the power semiconductors used in the bridges e.g. diodes, thyristors, triads, gate turn-off thyristors and bipolar power transistors. Only the steady state operations of bridges are described herein. For such operations it is assumed that the load is well matched to the rating of the bridge. The remainder of this section is an introduction to the subject of harmonic voltages and currents that are caused by variable speed systems for DC and AC motors. It emphasises the main aspects that affect the supply power systems. 

The thyristor is a semiconductor device made of germanium or silicon wafers and comprises three or more Junctions, which can be switched from the OFF state to the ON state or vice versa. Basically it is a ptipn junction, as shown in Figure 6.20(a) and can be considered as composed of two transistors with npn and pnpjunctions, as illustrated in Figure 6.20(b). It does not turn ON when it is forward biased, unlike a diode, unless there is a gate firing pulse. Thyristors are forced commutated (a technique... 

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