20 Khz 800 volts power supply for ultrasonic welder

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#2
Look for sine wave inverter schematics. I am not sure if the ultrasonic welder uses sine wave but is most probable.

Having the diagram of the inverter, just modify the output voltage by changing the number of turns.

Also be aware that the power required from this supply is also to be considered.

Gajanan Phadte
 
#6
things could be a bit complicated - the piezo ceraimc stack can want to see a series L to cancel some of the stack's C - but the maker sugests some controllers are "smart" - so you may need broader band drive to the stack to allow the controller's tuning of the drive for the mechanical parts resonance properties

I would want to see the exitsing unit schematic before recommending a replacement
 
#7
here is the welder schematic
welder.JPG
 
#13
“what if I use this schematic :http://ludens.cl/Electron/PS40/Figure1.gif
just some changes to secondary of output transformer to generate 1000 volt 20khz ac? “

I am not trying to insult you, but if you do not know how silly that question is, you have no business trying to make your own power supply. and you will never make it work.

Lets try to keep this as simple as possible. Did this welder ever work properly? How long does it last after you replace the power switches?

When you replaced the power switches did you do a really good job of inspecting the contacts of the sockets the power switches plug in to. You must visually inspect each socket pin and mechanically verify each pin by mechanical feel, trying each pin one at a time.

Do you have an electrical schematic of this power supply. If you do post it.

Do you have a good oscilloscope and do you know how to use it.

If you have a scope, monitor the primary waveform of the transformer when the welder is under full load and no load and show us the waveform.

Let us know what the voltage scale is for the waveform and what part number the power switches are so we can find the specs.

The problem may be as simple as a bad snubber on the power switches or transformer.
 
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#14
Not sure about this welder, but usually its the current that does the "welding" not the voltage. (The metal your welding shorts the welder output so the power delivered is from the high current). Dont understand why you need the high voltage or the high freq. Any one know why?
 
#15
cbdb said:
Not sure about this welder, but usually its the current that does the "welding" not the voltage. (The metal your welding shorts the welder output so the power delivered is from the high current). Dont understand why you need the high voltage or the high freq. Any one know why?
Click to expand...

Because this is an ultrasonic welder. It welds plastic. The high voltage at 20 to 40khz energizes a piezo electric transducer. That transducer vibrates a metal horn that clamps two pieces of plastic together. The mechanical vibration causes the plastics to melt together.

Now is that super cool or what!
 
#17
unfortunately there is no oscope to observe the waveform.
i connected my dc to dc converter (8 IRFZ44N Mosfets) to the welder from the transformer secondry and i got very poor vibration in the welder.cause it obtained 2 ampers 12v in primary.
and my transformer was 220 to 12 volts 50hz.with EE85 Ferrite Core.
 
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