Circulating Currents in Windings: Fundamental Property

TL;DR

This paper provides a formal proof of the fundamental property of circulating currents in windings, highlighting their causes, effects, and implications for electrical machine efficiency and insulation longevity.

Contribution

It introduces a rigorous mathematical framework for defining circulating currents and demonstrates this with a case application in an electric machine.

Findings

Circulating currents cause increased winding losses.

They can lead to insulation degradation over time.

The paper offers a formal proof of the fundamental property.

Abstract

Circulating currents in windings refer to unwanted electrical currents flowing between the parallel conductors of a winding. These currents arise due to several phenomena such as asymmetries, imperfections in the winding layout, and differences in electric potential between the parallel conductors. This effect is visible typically in windings of transformers, motors, or generators. At on-load condition, this is equivalent to having a current unevenly distributed between parallel conductors. Circulating currents have two main drawbacks: increased losses in windings and potential degradation of insulation over time. The former is an intuitive property that is widely acknowledged in the literature. This paper presents a formal proof of this fundamental property, building upon the authors' previous work and embedding it within a rigorous mathematical framework. The mathematical definition of circulating currents is provided, along with a case application in an electric machine.