Re: Homemade Inverter Plasma Cutter
- From: "Bob Eldred" <nsmontassoc@xxxxxxxxx>
- Date: Sun, 17 Apr 2005 17:44:48 GMT
"Jeremy Samuels" <js5301@xxxxxxxxx> wrote in message
news:1113679804.270488.175420@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> After seeing that cheap harbor freight plasma cutter, I was thinking
> how hard is it to make an inverter plasma cutter? So, I've decided to
> build one. I don't expect anything close to a real plasma cutter, this
> is mainly an "educational" project.
>
>
> The torch, of course, I would buy (I'm not that crazy). But the power
> supply is just a 5-20 khz squarewave H bridge into a high frequency
> transformer. Output voltage is about 150 volts. The secondary of the
> transformer is loosly coupled to the primary, as the secondary voltage
> drops considerably while cutting. Secondary current is around 30 amps.
>
>
> For the controller, I was considering using a PIC microcontroller (my
> programming is better than my soldering). Current adjustment would be
> nice, but initially I will just have an adjustable 5-20 khz squarewave
> output. The mains will be rectified and smoothed with a electrolytic.
> An H-bridge IGBT module (600 volts, 25 amps) will be pulsed from the
> PIC. My question is, what type of transformer should I use? Is there
> anything else I should consider? Any good books?
>
I agree with who ever said "not a good project for a beginner." You are in
for no end of nightmares trying to get a high frequency high power H-bridge
to work. The fact that you are asking about the transformer illustrates the
point. Transformer design is critical and H-bridges are notorius for causing
problems like "flux walking" that are guaranteed to destroy your switches
until you get a handle on the design and thoroughly understand it's nuances.
Even experienced engineers have trouble with these things until they learn
the art. I suggest you visit Harbor Freight and save your self a lot of
headaches. It will certainly be cheaper in the long run. I'm all for
education but you need to thoroughly study switching power supply design and
work with low power, easy to understand projects first. Secondly you will
need first rate test equipment like a digital strorage scope to capture
transient events that will plague any design. Good luck.
Bob
.
- References:
- Homemade Inverter Plasma Cutter
- From: Jeremy Samuels
- Homemade Inverter Plasma Cutter
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