Yes that's an improvement, but I think that the largest energy leak is in D1
Ok, i checked out severall diodes for lowest forward voltage and this RU4D
diode came out as lowest; 0.439V, together with a mica spacer between the pot core halfs to create a "much longer rising ramp than the falling ramp" current through L1, i redid the efficiency tests which now came out at 89%, see screenshot 1 data
The pulse period was set at 1.369,863,0ms
C1 39.82uF @ 30V = 17919uJ
30V - 4V = 26V
C1 39.82uF @ 26V = 13459.2uJ
C1 lost 17919 - 13459.2 = 4459.8uJ
C2 1.154uF @ 83V = 3974.95uJ
Eff = 3974.95 / 4459.8 = 89%
The voltage across this RU4D and the current through L1 can be seen in screenshot 2
Look at the little red area that I marked on the scopeshot below. The current should not be reversing through D1 at all.
The negative current excursion is a leak and a fuel for oscillations that follow it.
That ringing signal on the current (through L1, not D1) appears only when attaching the ground lead of the probe at the anode of
the diode when measuring the voltage across the diode.
It is NOT there when removing the probe, see screenshot 3
See screenshot 4 for comparing current through L1 (green) and D1 (purple)
Also, the current through L1 should have much longer rising ramp than the falling ramp. More like the proportions here.
Ok, as mentioned, i had to add a mica spacer to get a similar current pattern like that.
CH1 should not be inverted in your latest scopeshots because it creates a graphical illusion that C2 absolute voltage is decreasing while in fact the absolute voltage across C2 is increasing with time (albeit it's a negative voltage)
Ok, done that at screenshot 1.
« Last Edit: 2015-02-26, 07:48:33 by Itsu »