AutoSpeed - DC to DC converter solution for alt-less modders

[NiHaoMike]

I'm currently working on a DC/DC converter for a small workstation, which converts 12v to 190v to run the existing power supply. (It's quasi-regulated push-pull topology with a rather interesting control circuit to seamlessly transition between AC and battery power, along with provision to always accept alternative energy.)

With a different transformer, I could implement what my friend had in mind. However, the only toroid cores I have are either unsuitable or too small and the only EI cores I have are gapped, which won't work with a push-pull topology. From my understanding, the core doesn't have to very big since it does not handle much power itself. (It is essentially a 1-2.5v power supply connected in series with the battery to boost voltage. Even one rated for 75A is less than 200w.)

I'll see if I can take apart an ATX transformer to use the core and form. The tricky part is melting the glue without cracking the core. Then I'll need an inductor for the output filter, which I can make using a toroid for the same ATX supply.

[JasonG]

any updates NiHaoMike ?

[NiHaoMike]

The DC/DC converter for my PC worked great. I have not started work on the booster since I don't have a use for it now.

I did do a lot of research for constructing power supply transformers. For low voltages, high currents, windings are often made from copper strips instead of wire. Copper tape is commonly available as copper flashing if you don't mind buying a bulk supply of it. High temperature insulation is commonly available in the form of oven bags. The form and core can be obtained from the main transformer in an old PC power supply. How to take it apart without breaking the core is a little tricky. I have had limited success putting the transformer on a stove and slowly ramping up the temperature until a gentle pry with a screwdriver gets it apart. I found out that my cousin disassembles electronic devices for a living (failure and design analysis), so I'm going to ask him for tips on disassembling a transformer.

Basically, rewind the transformer with a few turns of high current center tap winding in the center and continue that with lower current windings (about 3-4 times as many turns as the center winding) at the ends. The center connects to the input, the ends of the high current winding connect to the output rectifier, and the ends of the low current windings connect to two MOSFETs going to ground. The MOSFETs are driven alternatively in current mode like all push pull supplies.