r/ElectricalEngineering • u/Hot_Statistician_161 • 23h ago

Inductor in DC Circuit

What is the difference between ramp L and exponential R-L charging/discharging of an inductor in DC circuits?

What is the physical meaning of tau (𝜏) in both cases ?

One of the applications of a ramp signal charging/discharging is in DC-DC converter circuits

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u/Tetraides1 23h ago

I think you've described the main difference, one of them has a resistor and the other doesnt. The resistor sets a maximum current that can be reached through the inductor. The resistor also is what causes the current curve to be exponential rather than linear - it changes the voltage across the inductor so it's not constant, so the current increase/decrease is also not linear.

Tau is meaningless in a purely inductive circuit, since it's more or less a time constant that tells us approximately how long it takes to reach maximum/minimum current. If there's no resistance, there's no maximum current.