| 摘要 |
1. Process for protecting a power switch present in a power converter, associated with a voltage threshold clipping device, according to which the maximum permissible voltage across the power switch is maintained by snubbing the voltage threshold clipping function when the power switch is turned off. 2. Process according to Claim 1, characterized in that the maximum permissible voltage across the power switch is maintained with the aid of a snubber switch placed between the voltage threshold clipping device and the power switch control means. 3. Process according to Claim 1 or 2, characterized in- that the same control means is used to control the snubber switch and the power switch. 4. Process according to Claim 3, characterized in that the leading edge of the control pulse of the snubber switch is synchronized with that of the control pulse of the power switch and in that the trailing edge of the control pulse of the snubber switch has a delay on that of the power switch pulse. 5. Process according to Claim 4, characterized in that said delay is between 50 and 500 mus and preferably close to 200 mus. 6. Power converter associated with a clipping device, comprising: - at least one power switch, - a control means for said power switch, - a snubber switch placed between the voltage threshold clipping device and the power switch control means, said control means making it possible to control both the power switch and the snubber switch. 7. Converter according to Claim 6, characterized in that it comprises several power switches arranged in series, said switches being associated with a voltage threshold clipping device. 8. Converter according to Claim 6 or 1, characterized in that the power switch (es) is (are) high voltage linear-regime semiconductors such as power IGBTS. 9. Converter according to Claim 8, characterized in that the snubber switch is placed in series with the clipping device, the assembly being connected between the collector and the gate of the power IGBT. 10. Converter according to any one of Claims 6 to 9, characterized in that the snubber switch is a linear-regime semiconductor, preferably an IGBT, or a semiconductor of "on-off" type. 11. Use of the process according to any one of Claims 1 to 5 or of the converter according to any one of Claims 6 to 10 to protect power switches present in a voltage-reducing chopping circuit against overvoltages.
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