HV PSU / Jacobs ladder

Solid State HV PSU
 8 Turns 1mm stranded wire
Secondary: 2x250 Turns 0.125mm Enameled Copper Wire wound over 2 x 50mm diameter tubes
Driver: SLC type capacitor charging power supply
Fres: 50Khz

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Inspired by the Steve Ward I thought Id have a go at making a large HV Switch mode PSU.

I had a pair of N27 Ferrite U cores. so I wound a couple of secondaries around drain pipe, allowing a good 20mm creapage on each winding. The Windings are center tapped, so no more than 10Kv to earth should be on each output. The primary is 8 turns of 1mm mains cable.

I measured the inductances of the windings and got a figure of 0.26mH for the primary and just under 1H for the secondary. Shorting out the secondary I got a leakage inductance figure of 0.042mH.

Aiming for a resonant frequency of 100khz I chose a 0.1uF cap, the allows me to run the coil in SLC at 1/2 fres or 50Khz.

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The Power supply consists of a full bridge of IRG4PC30KD and a GDT driven by 2 IXYDD414's and a SG3525 controller. The bridge has full rectified mains (315Vac) via a variac for testing.

The picture shows the test set up with an additional 0.2mH of external inductance and my first GDT, which I later found to be wound on a really poor core taking out 2x IXYDD414's in the process.

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After A little playing I get the SMPSU stable and played with a Jacobs ladder as a test load. The current regulation is excellent, as the arc widens the PSU puts more and more power into it. So far I have had up to 1.5KW into a silent hot white plasma.

Jacobs ladder test

Now to find a real use for this supply.

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