| Abstract |
Self-commutated converters can be considerably simplified and improved by the use of turnoff thyristors (GTO's). In order to exploit the advantages of the GTO's in practica, concepts concerning their gating, circuitry and protection are required which take their special requirements into account. The gating requirements of a GTO thyristor are described, as is a modular gating unit with integrated protective functions which fulfills all the requirements and operates the GTO optimally under all conditions. To ensure safe operating conditions, particular circuits are required which reduce switching losses in the GTO. However, the energy converted in the resistors of conventional switching aid networks raises the total losses of a GTO equipment considerably. An auxiliary circuit for an inverter is described by means of which a large proportion of this energy can be fed back into the dc-link with only minor design and operational limitations. At present the fault-protection of the GTO's has usually more influence on their dimensioning than the operational demands. On the other hand a high level of protection should be realized with little additional circuit complexity and nevertheless a good use of the GTO capacity. The GTO inverter protection system presented here takes these partially contradictory demands into account. |
