Ansoft Maxwell - Multi terminal excitation on 3D Transient

1. Jul 29, 2015

Valerio

Hello everybody,

I am busy with a magnetic transient 3D model and quite new in the use of Maxwell.

I am simulating a 6 pulse rectifier in double star connection (connection number 5 as per IEC 146-1-1). Each of the 6 arms of rectifier foresee 8 paralleled diodes.

I am interested to see the current distribution among the parallels for each of rectifier arm considering the topology of the mechanical structure.

I built the external circuit to generate the 6 pulsating currents for each arm.

Each of the 6 pulse has 120 electrical degree duration, each pulse time spaced by 60 electrical degree (so two pulses always overlap during a period).

In practice my circuit has 6 separate windings. Each winding has as an input (the anode of the diode) and the other terminals of each winding are all short circuited closing the circuit.

My 3D geometry is made of only conductor materials. It has 6 input terminals which are the AC connection of the arms of the rectifier.

Along the conduction path, each one of these arms subdivide itself in 8 different geometrical paths (the 8 paralleled diodes), resulting in 6x8 conduction paths.

All 6x8 paths ends in only one output common conductor which is the DC output of the rectifier.

When I create the 6 windings I assigned 6 separate input terminals and I tried to assign 6 output terminals the same output terminal surface of the geometry.

The problem is Maxwell didn't allow me, message was something like: "it is not possible to use different windings that belong to the same conduction path".the point is that I cannot separate each winding because the porpoise of the analysis is to see how currents distribute among parallels (as happens in a rectifier current arm) but let them merge in one end (DC current output)

The common bus has, geometrically, great influence on the current distribution among the 6x8 parallels, because its path is orthogonal to the 6x8 parallels. It greatly affect the current distribution of currents.

I need to estimate in which way the current decide to subdivide into these 6x8 =48 parallels, entering cyclically from each one of the 6 input arm terminals, then merging and going out through the common path, the DC busbar.

It is important therefore that I find a way to merge the 6 arm currents in some way inside my geometry and not keeping the 6 windings separate, because I need to obtain for the final path, a DC current and not a pulse current (which is the arm current)

How can I model this?

If there are some good ideas I will be glad to discuss.

Thank you for any suggestions and useful information

Valerio

2. Aug 3, 2015