Multiphase inductor (01-Oct-2009)

Technical nescl'ption Agnes Choke 11/03/2009

1) Abstract

This document describes a novel multi-phase inductor intended for application within power line fiters. In combination with tine capacitors, the inductor provides line reactance to achieve suitable attenuation of line-borne interference. The mutual and self inductance of each phase winding is proportioned to give a suffcient attenuation in both common and diferential modes. This solution uses a minimal number of conductor tums which leads to shoit winding length and consequently low copper cost and low power loss. The indllCtor is simple and rapid to assemble and is designed to be through-hole PCB mountable \vith solder pins protruding ii'om one plane with a defined pitch.

2) Application and Background

In order to meet the EMC emission and immunity limits, EMI power-line fi1teî's employ inductors and

capacitors connected to the line to attain a suitable insertion Joss. The inductors and capacÌìors are

connected in such a way as to provide both common mode and differential mode attenuation. Tho inductor is typically formed by using a toroidal core wound in the current compensated format. This

format has

of inductor is quite effcient in its use of Core material, but can use a

lengths. Anotherproblell with this type of

3) Benefits of

In addition 2 spiing metal paris are used to keep the assembly together and prevent parts fTom moving:

. Spring Clip fitted externally (2x)

" Spring Washer iìttecl internally (lx).

      a winding for each phase wire with identical number of turns. The winding sense is such that power current is compensated leading too. power current sum of zero. These cores typical have a significant number of windings. The common mode or primary component of inductance is achieved

from the AL of the core multiplied by the number of turns squared. The differential mode Or stray

inductance is provided by the self inductance of each phase winding created by leakage flux. This type

                                        significant quantity of copper, is not efficient to manufacture and is difficult to mount within the filter. In particular the winding process is typically produced manually and requires some fòrce to make each turn, while mounting the inductor is complicated because the copper wire leads are not in defined positions and have varying

                         inductor is to provide sufficient clearance distances between phases in order to meet safety standards. In addition it is usually necessary to pot the filter with resin to hold the inductor in place and to help witn neat removaL. Further, it can be difficult splicing the wires of the inductor togcthcr with interconnecting conductors within the filter as these are not anchored in place.

this product

Thc inductor described here is simple and rapid to assemble, all the paiis being combined in one axis. It is designed to be through-hole PCB mount...