Snubber capacitor calculator

Here you can calculate the snubber capacitance that is needed to keep transient voltages below the maximum allowed value. Stray inductance is the inductance in the primary circuit of the inverter. If the stray inductance is not known, the two estimates can be used, high estimate for cable/wire primaries or long distances. Low estimate for copper busbar and short distances.

Switch between the input fields to automatically calculate the values.

Stray inductance nH
Peak current A
Max transient voltage V
DC bus voltage V
Results
Snubber capacitance uF
High inductance estimate uF
Low inductance estimate uF

Formulas used

Calculated snubber capacitance = Stray inductance * Peak current^2 / (maximum allowed transient voltage – DC bus voltage)^2

Snubber capacitance is given in Farad, stray indutance is given in Henry and voltage in Volt.

Estimated high inductance snubber capacitance = Peak current / 100

Estimated low inductance snubber capacitance = (Peak current / 100) * 0.5

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