How to sense inductive energy storage

Why should you use an inductor for energy storage?

Because the current flowing through the inductor cannot change instantaneously, using an inductor for energy storage provides a steady output current from the power supply. In addition, the inductor acts as a current-ripple filter. Let’s consider a quick example of how an inductor stores energy in an SMPS.

How is the energy stored in an inductor calculated?

The energy stored in the magnetic field of an inductor can be written as E = 0.5 * L * I^2, where L is the inductance and I is the current flowing through the inductor.

What is the rate of energy storage in a Magnetic Inductor?

Thus, the power delivered to the inductor p = v *i is also zero, which means that the rate of energy storage is zero as well. Therefore, the energy is only stored inside the inductor before its current reaches its maximum steady-state value, Im. After the current becomes constant, the energy within the magnetic becomes constant as well.

How does an inductor store energy in an SMPS?

Let’s consider a quick example of how an inductor stores energy in an SMPS. Closing the switch for a switched mode power supply increases the current flowing to the load and allows energy to store in the inductor. Opening the switch disconnects the output of the supply from the input.

When does the energy stored by an inductor stop increasing?

The energy stored by the inductor increases only while the current is building up to its steady-state value. When the current in a practical inductor reaches its steady-state value of Im = E/R, the magnetic field ceases to expand.

How does Linear Technology affect inductor energy storage?

While one inductor’s current is increasing, the other’s is decreasing. There is also a significant reduction in the required inductor energy storage (approximately 75%). The inductor’s volume, and therefore cost, are reduced as well. See Linear Technology’s Application Note 77 for complete details.