Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Mixing high currents/voltages.

Status
Not open for further replies.

sae140

New Member
I'm currently working on a design to convert a DC inverter welder to AC, and have just completed the low voltage (25-50V), high current (5-140A) circuitry using EWB5.

It's desirable to also have a built-in high frequency/high voltage (c.10-20KV, negligible current) arc facility across the output cables to make starting the welding arc that much easier, especially when using TIG. However, my output switching stage uses cross-coupled high power MOSFETs which are intolerant of such high voltages. (they *do* have reverse diodes built-in, but it's the forward direction when not conducting I'm concerned about)

Does anyone know of a method of preventing such a high frequency/voltage from finding it's way back down the cable to the MOSFETs ? Maybe it's obvious, but my brain's dried-up. Would a fistful of ferrite rings do it ?


Colin
 
A friend of mine was a fabricator for GM and NASA and he taught me a little about the way welders work. He explained that the Hi-Freq component would eat the switching transistors. AFAIR the schema was a filter of a Hi-V cap and a 10 or so watt Resistor making a ground path for the noise backfeed . I really can't help you but my suggestion would be to find a source of schematics for any welder and study the methods use by those manufacturers to eliminate that effect . I'm sorry that I can't give you any more information.
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top