RE: MMC resister problem

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Gary.Lau-at-hp-dot-com>

I fully agree that battery packs can achieve reverse-charges on cells, but
this is very different than a string of caps.  A NiCd cell is not a
capacitor and is not at all a linear device.  A "bad" cell had radically
different V-I properties than the remaining good cells.  Even good cells
have different V-I characteristics depending upon their state of charge.
But in MMC strings, we don't have a "bad" cap that is responsible for the
imbalance.  As far as we understand it, all caps are electrically the same.
 The observed results of course suggest otherwise, but I've not yet seen a
model suggested that can explain the effect.

While iron-core inductors exhibit hysteresis, I wasn't aware that caps had
this property?

Gary Lau
MA, USA


>Original poster: "Crow Leader by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<tesla-at-lists.symmetric-dot-net>
>
>Voltage reversal is possible in a series of capacitors the same was it is in
>"unbalanced" nicad battery packs.
>
>If your cap string is building up voltage due to hysteresis and a few caps
>don't make any voltage themselves (leakage capacitance or combination of
>both) and the entire string has a load of some sort like your transformer
>secondary, they become part of the load and will see a voltage reversal and
>possible charge up from this current flow.
>
>KEN