Characterization of Magnetic Components

Overview

Source: Ali Bazzi, Department of Electrical Engineering, University of Connecticut, Storrs, CT.

The objective of this experiment is to achieve hands-on experience with different magnetic components from design and material perspectives. This experiment covers B-H curves of magnetic material and inductor design through identifying unknown design factors. The B-H curve of a magnetic element, such as an inductor or transformer, is a characteristic of the magnetic material forming the core around which windings are wrapped. This characteristic provides information about the magnetic flux density that the core can handle with respect to the current flowing in the windings. It also provides information about limits before the core is magnetically saturated, i.e. when pushing more current through the coil leads to no further magnetic flux flow.

Procedure

1. Relative Permeability Identification

Follow the procedure to find the relative permeability of the small inductor (yellow/white ferrite core). The core dimensions are shown in Fig. 2, and the number of turns is N=75.

Using a LCR meter, measure the inductance of the inductor at both 120 Hz and 1000 Hz.
Build the circuit in Fig. 1 on a proto-board, but keep the function generator output disconnected from the proto-board.
Check a differential voltage pr

Results

In order to find the relative permeability of the core material, two approaches can be used. The first approach is to use an LCR meter, where the inductance (L) of a coil made with a known number of turns (N) is measured, and then the relative permeability can be calculated as follows:

Reluctance of the core: Equation 7 (7)

Application and Summary

Even though inductors and other electro-magnetic devices (e.g., transformers) are very common in many electrical, electronic, and mechanical systems, buying inductors for a specific application is not trivial. Even when an inductor is bought, datasheet information may still have ambiguities on the actual material, number of turns, and other details. The tests in this experiment are especially useful for engineers and technicians who plan to build their own inductors or characterize off-the-shelf ones. This is co