Gate circuit for hard driven GTO

Details Gate circuit for hard driven GTO Gate circuit for hard driven GTO

1993-04-28

1996-02-20

Callahan, Timothy P.

Miscellaneous active electrical nonlinear devices, circuits, and

Gating

Utilizing three or more electrode solid-state device

327443, 327330, 327377, 327380, H03K 1756

Patent

active

054932475

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to the field of power electronics. It concerns a GTO thyristor circuit comprising: and which, together with the GTO, forms a gate circuit and is provided for turning the GTO on and off; and first inductance representing the inductance of the conductors and components in the drive circuit and the second inductance the internal inductance of the GTO itself.
Such a is circuit disclosed, for example, in EP-A3-0 228 226.
2. Discussion of Background
At present a multiplicity comprising about 190 types of GTO is available on the market. In application, they essentially divide into three important fields of use, namely traction (for example, in electric locomotives), the UPS (uninterruptible mower system) and industrial drives. This widespread use has taken place even though the GTO is subject to a few problems for the user, particularly from the point of view of circuit engineering. An improvement in the GTO itself or a simplification of its external circuit therefore has an enormous economic significance.
In connection with the GTO, the user sees himself confronted, in particular, with the following problem areas:
Turn-off thyristors (GTOs) had, hitherto to be operated with appreciable circuit networks comprising diodes, inductances and capacitors (snubbers) in order to reliably avoid critical states in the component. Apart from additional weight, increased volume and appreciable losses, this entails, in particular, additional development and manufacturing costs. The development of control software is markedly more expensive as a result of the complicated mode of operation engendered by the snubbers. Attempts are therefore being made to reduce the size of the snubbers (smaller inductances and smaller capacitors) and to simplify them.
In this connection, an important role is played, in particular, by the leakage inductance of the arrangement and the snubber diode. To reduce surge voltages due to inductances, an appreciable design complexity has to be adopted. More recently, very special diodes have also been developed for these applications.
The reason for the snubbers required is generally recognized to consist in the inhomogeneous turning-on and turning-off of GTOs: a multiplicity of studies using infrared, thermal and induction measurements have repeatedly emphasized this state of affairs. The efforts have, therefore been directed to the production of components which are as homogeneous as possible (in particular, in relation to the doping). Despite striking improvements in the doping homogeneity, it has not been possible, however, to simplify the snubbers substantially or to reduce them in size.
The declared objective of users and manufacturers is a rapidly switchable HF-GTO. This should be notable, inter alia, for a markedly smaller circuit complexity, and for low driving power and few turn-off failures. To provide such an HF-GTO, the earlier European Application No. 90123659.6 by the same inventor of the present invention has already proposed a hard driving switching arrangement, in which the turn-off is effected by a pulse-type gate current which rapidly exceeds (in a few .mu.s) the anode current.
FIG. 3 in the earlier application diagrammatically shows a suitable gate circuit for a GTO of known design. In that case, the gate circuit comprised gate terminal of the GTO component; terminal of the GTO; CR1 and a diode D1 upstream of CE1 for isolating the capacitor voltages.
At the same time, the gate circuit inductance is set by the inductance which is unavoidable in conventional housing designs. The circuit functions in a quasi-resonant operating mode: the small first high-voltage (preferably.gtoreq.100 V, for example 200 V) capacitor CR1 initially supplies a gate current which rapidly increases despite the gate circuit inductance present and which, after the discharging of the second capacitor (the maintenance capacitor) CE1 is maintained for a fairly long time (duration of the turn-off process). The capacitor CR1 is rated

REFERENCES:
patent: 3943430 (1976-03-01), Kumano
patent: 4568837 (1986-02-01), Seki
patent: 5077487 (1991-12-01), Iida
patent: 5237225 (1993-08-01), Gruning

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