Electricity: electrical systems and devices – Safety and protection of systems and devices – With specific voltage responsive fault sensor
Patent
1997-10-27
1999-08-31
Gaffin, Jeffrey
Electricity: electrical systems and devices
Safety and protection of systems and devices
With specific voltage responsive fault sensor
363132, H02H 320
Patent
active
059461780
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an overvoltage protection device of transient protection type intended to reduce the risk of overvoltage across a power semiconductor, which among other things may occur in connection with turn-on and turn-off of the power semiconductor, when a plurality of such power semiconductors have been connected in series to build up a high voltage by voltage division.
BACKGROUND OF THE INVENTION
Self-commutated converters are used at present in a number of applications, for example in static converters for motor drives, switched supply devices, UPS systems, etc. Normally, in such applications, an individual power semiconductor is utilized for building up the occurring relatively high voltages. In certain applications, however, it is desired to switch off or on such a high voltage and this cannot be managed with a single power semiconductor. Power semiconductors then have to be capable of being series-connected with a good voltage division. As examples of applications in which it may be of interest to series-connect power components, it may be mentioned converters for high-voltage motors, traction motors or high-voltage generators. Further, there are applications within distribution and transmission of electric power wherein very high voltages (typically 20-500 kV) are switched on or off. High-voltage converters are used here, among other things as controlled rectifiers and inverters for transmission of high-voltage direct current (HVDC). It is considered that self-commutated converters of a voltage-source type will be used to an increasing extent in transmission and distribution applications. Besides in HVDC there may be mentioned, as examples, converters for reactive power compensation, phase angle control, improvement of the network quality (e.g. compensation of harmonics induced by non-linear loads), for transmission of power between the phases during a phase error, etc. In more general terms, these converters may be used to control power flows, provide better availability and higher network quality in existing AC systems.
In self-commutated converters there are used gate turn-off power semiconductors of GTO thyristor type or controllable power semiconductors of transistor type, for example IGBT, MOSFET, bipolar transistors (BJT), or Darlington transistors. In the higher power range, especially GTO thyristors and IGBT transistors, respectively, are at present the most interesting components. IGBT transistors are predicted to handle increasingly larger powers and successively to replace or supplement GTO thyristors in converters intended for high powers and high voltages.
In series connection of power semiconductors, which are in the form of components as IGBT or GTO, however, it is difficult to obtain a uniform voltage distribution between the components. This applies especially to turn-off of the current, but problems with voltage division may also arise during blocking and turn-on. For the IGBT case, a good voltage division is also required during a possible short circuit of a DC intermediate-link capacitor since the IGBT builds up voltage and limits the current. Taken together, these have contributed to the fact that the number of commercial applications using series-connected power components of the GTO or IGBT type is still very small.
The problems in connection with turn-off arise from the fact that the series-connected power components tend not to build up voltage completely synchronously. Certain components tend to turn off earlier than others, which easily causes overvoltages to arise for those components which turn off early in a valve, by valve being meant the chain of series-connected components.
Similar problems may also arise during turn-on of the power components. Certain components turn on later than others, which may lead to a brief overvoltage across the components which turn on later. However, the problems are normally smaller in the case of turn-on of the valve than in the case of its turn-off.
Further, during blocking of the valve, certain
REFERENCES:
patent: 5077651 (1991-12-01), Kobayashi et al.
patent: 5465190 (1995-11-01), Meunier et al.
patent: 5616970 (1997-04-01), Dittrich
patent: 5650906 (1997-07-01), Marquardt et al.
patent: 5737200 (1998-04-01), Miyashita et al.
Chokhawala et al., Switching Voltage Transient Protection Schemes for High Current IGBT Modules, International Rectifier Corporation, Applications Engineering, El Segunda, CA, 1994, pp. 459-468.
Eschrich, Protection of IGBT Modules in Inverter Circuits, EPE Journal, vol. 1, No. 1, 1991, pp. 57-60.
Hefner, Jr., An Investigation of the Drive Circuit Requirements for the Power Insulated Gate Bipolar Transistor, (IGBT)*, IEEE Transactions on Power Electronics, vol. 6, No. 2, 1991, pp. 208-219.
ABB Research Ltd.
Gaffin Jeffrey
Huynh Kim
LandOfFree
Protective circuit for series-connected power semiconductors does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Protective circuit for series-connected power semiconductors, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Protective circuit for series-connected power semiconductors will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2427828