Electronic – Can you store energy in an inductor and use it later

capacitorinductorpower

My company uses supercaps to power the device if power is cut. I was wondering if you could do the same thing with an inductor. If you can't, why not?

Best Answer

The magnetic field which stores the energy is a function of the current through the inductor: no current, no field, no energy. You'll need an active circuit to keep that current flowing, once you cut the current the inductor will release the magnetic field's energy also as a current, and the inductor becomes a current source (whereas its dual, the capacitor is a voltage source).

Aspects of the capacitor-inductor duality in energy storage terms:

\begin{array}{ll} \mbox{Capacitor} & \mbox{Inductor} \\ \mbox{* stores energy in electric field} & \mbox{* stores energy in magnetic field} \\ \mbox{* must be open loop (infinite resistance) } & \mbox{* must be closed loop (zero resistance)} \\ \mbox{* loses energy through parallel resistance} & \mbox{* loses energy through series resistance} \end{array}

A superconductor can sustain a magnetic field in a zero resistance current loop, however.

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Unfortunately you'll always see the fumes of water vapor caused by the liquid nitrogen in pictures like this, which means temperatures below -183 °C.