[TCML] Question for solid-staters

[Ken Herrick <kchdlh@xxxxxxxxx>]

Continuing on this SSSR scheme of mine, I've now mounted two primary 
modules, each consisting essentially of 3T on 12"-diameter driven by a 
p-p pair of MOSFETs, with power source capable of up to ~330 VDC to the 
MOSFETs and operating at ~125 KHz.  There has been discussion here as to 
whether to connect those two primary drivers effectively in series, 
using a bifilar choke or chokes to deliver the DC power to them, or 
whether it will produce just as many ampere-turns merely to connect the 
two driversto the same DC power source, directly in parallel.  In both 
cases, the gate drives are transformer-coupled. The primaries are 
coaxial, co-planar, wound with turns close together, and are located 
directly against the bottom of the secondary.
Fortunately I've made provision for the bifilar chokes because 
initially, following the simpler connection, I find that a) each primary 
+ driver produces the expected primary currentwhen operated by itself 
(measured by a current transformer through which 1 turn of each primary 
passes).  However, b) when I connect both of them similarly I get a 
total primary current increase of only around 10%.  This seems to tell 
me what I had rather suspected, namely that the primaries must be 
connected effectively in series by means of "floating" at least 3 of the 
final 4 primary drivers as I describe while galvanically connecting the 
primaries themselves in series.  That's the scheme I'd used years back 
when I actually got nice spark breakout from the 6x24 toroid, with no 
breakout point, which I am aiming for again.
I'm guessing that the ~10% increase in current is due to the decrease 
ineffective dc resistance of the resultant primary, nothing more. So...a 
little re-wiring will be in order.
Commentswelcome, of course.

Ken Herrick
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