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There are various designs on this, some complicated. The basic one is similar to a RCD snubber but with the R replaced by a series L and D combination returning to ground instead of supply. Look at the pdf file
The energy that is stored in the capacitor during turn-off is transferred later to the L as stored current. When the device turns on again the LC combination will cause a damped oscillation with freq=1/2*pi(sqrtLC) and the energy will be returned to the supply bus via the diodes.
Choose C large enough to slow the voltage on the device as for RCD type. Then choose L so that the one period of the oscillation is less than the device on-time