Active-Snubbing Or Passive-Snubbing for Fast Switches?

Francis Robinson, Barry Williams

Research output: Chapter or section in a book/report/conference proceedingChapter in a published conference proceeding

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As power-switches improve, the primary function of switching-aid circuits changes from modifying the shape or rate-of-traverse of V-I loci within device
safe-operating-areas (SOA's), to clamping transient current and voltage, at turn-on and turn-off, below peak current and voltage ratings. Also, as device
ruggedness and device parameters are improved, or made less variable between devices and with operating conditions, active-snubbing or active-clamping becomes feasible, whereby the magnitude of peak-current at turn-on and peak-voltage at turn-off are limited by gate or drive-circuit control, or inherently by the devices themselves. Examples have been reported, however, none of these adequately compares active and passive snubbing, or exposes salient disadvantages in active-snubbing. A more objective appraisal of active snubbing
is attempted here, which uses as its basis for comparison; turn-on and turn-off commutation energy-loss, on-state energy-loss, overload capacity,
and turn-on and turn-off delay. Irrespective of whether active or passive snubbers or clamps are used, switch turn-off voltage-waveforms are often characterised by fast voltage-overshoot above the dc-supply voltage, or above the threshold-level of voltage-clamps, when used. High-frequency ringing
inevitably follows turn-off, or the beginning or end of voltage-clamping. The cause and solution are examined.
Original languageEnglish
Title of host publication14 Annual Conference of Industrial Electronics Society. IECON '88.
Place of PublicationSingapore
Number of pages6
Publication statusPublished - 1988
Event14th Annual Conference of Industrial Electronics Society, 1988. IECON 1988 - Singapore, Singapore
Duration: 24 Oct 198827 Oct 1988


Conference14th Annual Conference of Industrial Electronics Society, 1988. IECON 1988


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