# Projects:2018s2-293 Detailed Analysis of Ferromagnetism in the Periodic Domain

**Abstract**

In electrical engineering, we habitually apply linear models with constant parameters to devices that we plan to design and optimise. For a low-frequency choke, these parameters are the series resistance, R, and the series inductance, L. The resistance is normally considered to represent the linear part of the relationship between the measured voltage and the measured current, v(t) = R * i(t). The inductance is normally considered to represent the linear relationship between the measured voltage and the time-derivative of the measured current v(t) = L * (d.i(t)/d.t).

**Introduction**

In this project, the properties of practical inductors, known as “chokes”, will be carefully investigated. Ideally, we habitually apply linear models with constant parameters to devices that we plan to design and optimise. However, according to the Investigations from the previous project group, it has been found that the inductance, L, varies greatly with the operating condition of the choke. This apples even in the situations where saturation is not an issue.

**Project Team**

Project Students

- Lei Yi
- Jinhua Wang
- Zhengqian Lu

Supervisor

- Andrew Allison

**Objectives**

- To prove (or dis-prove) the hypothesis that R and L vary with operating condition.

- To separate out the various parts of the resistive loss, into copper loss, hysteresis loss and eddy-current loss.

- To enable students to get familiar with data capture and analysis, phasor analysis, Complex Fourier analysis and the statistical treatment of errors.

- To devise scaling laws, through which measurements, using small voltages and currents, could be scaled to obtain corrected estimates of parameters for the same devices under rated conditions.