Evaluating the reduction in snubbing with soft-recovery devices and the effect of resistor inductance

The effects of current-fall shapes on RC-snubber performance are examined to determine if smaller snubbers that remain tolerant to varying current-fall shapes and durations and give lower power-losses can be used. The effects of component imperfections on RC-snubber performance, the optimization of RC-snubbers with nonabrupt current-falls, the sensitivity of nonabrupt snubbers to current-fall variations, and the energy losses associated with nonabrupt snubbers are discussed. It is shown that finely tuning RC-snubber components to take into account nonabrupt current fall, allows reduced snubber capacitance to be used under certain operating conditions. However, voltage-responses become more sensitive to current-fall shape, diode switching-loss is increased by several orders of magnitude, and there appears to be no significant energy-loss advantage with sinusoidally modulated current.<
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