Inductor Energy

Formula

Description

The energy stored in an inductor is held in its magnetic field and is proportional to the inductance and the square of the current. This is analogous to the capacitor energy formula E = ½CV², with inductance replacing capacitance and current replacing voltage. The quadratic current dependence means that doubling the current quadruples the stored energy. This stored magnetic energy is what enables switching power supplies (buck, boost, and buck-boost converters) to efficiently transfer energy between input and output at different voltage levels.

Variables

• E — Energy in joules (J)
• L — Inductance in henries (H)
• I — Current through the inductor (A)

Practical Notes

In switching regulator design, the inductor must be chosen so that its saturation current rating exceeds the peak operating current. When an inductor saturates, its inductance drops dramatically and current spikes, potentially damaging the switching transistor.