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 12/120V inverter again
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audioguru
Nobel Prize Winner

Canada
4218 Posts

Posted - Nov 24 2005 :  9:03:34 PM  Show Profile  Reply with Quote
48.000 Watts?
Look at what they do on diesel-electric locomotives.

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tim
Mad Scientist

198 Posts

Posted - Nov 24 2005 :  9:03:42 PM  Show Profile  Reply with Quote
hey kizl i worked on that inverter for 2 years and never really got it going the way i wanted it to work it worked but i GAVE UP.

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audioguru
Nobel Prize Winner

Canada
4218 Posts

Posted - Nov 24 2005 :  9:15:37 PM  Show Profile  Reply with Quote
Don't give up, over and over.
Didn't you see the 500W inverter that I heped fix?
http://www.electronics-lab.com/projects/power/033/index.html


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tim
Mad Scientist

198 Posts

Posted - Nov 25 2005 :  9:32:45 PM  Show Profile  Reply with Quote
well i guess all you electronic pros dont know about those mosfets. 34 in paralle shouldnt use much at all there all using the voltage at the same time. the 24 volt controller that im using for the pulse modulater has output of just under 12 volts and it used to push 5 24v 80amp mosfets in paralle.

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audioguru
Nobel Prize Winner

Canada
4218 Posts

Posted - Nov 26 2005 :  07:27:50 AM  Show Profile  Reply with Quote
Hi Tim,
Before you wanted an inverter to use 34 Mosfets so its output could make 120V at 400A which is 48,000W.
Now you are using only 5 Mosfets rated at only 24V?

When the inverter steps up a 12V battery's voltage 10 times, then the current in the Mosfets is also stepped up 10 times. That's 4000A!
Mosfets rated for only 80A would curl-up and die with 800A through each one.

Wait a minute. Is it the controller that uses 5 paralleled Mosfets to drive the gates of 34 power Mosfets?
I thought the quantity of Mosfets in the controller should have an even number so they can operate push-pull. Then they can quickly charge and discharge the huge gate capacitance of the many paralleled power Mosfets.

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tim
Mad Scientist

198 Posts

Posted - Dec 07 2005 :  4:05:38 PM  Show Profile  Reply with Quote
well its tim again this motor controller uses 34 mosfets rated 200v 18 amp each. all in paralle it handles 200v and over 600 amps. waiting for freewheeling diodes for coasting and the circuit is done including the pulse width modulator from a 24 v motor controller that im using.

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atul_jangle
New Member

India
3 Posts

Posted - Dec 13 2005 :  01:44:00 AM  Show Profile  Reply with Quote
HI all,
what should i do to build a invertor 40khz.
does the above ckt. will work as it is for me if i
change time constant of it only.

A.M.Jangle
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audioguru
Nobel Prize Winner

Canada
4218 Posts

Posted - Dec 13 2005 :  06:12:45 AM  Show Profile  Reply with Quote
To make a 40kHz inverter you will need a circuit that works, power Mosfets at its output that drive a special high frequency transformer that is probably bifilar wound on a ferrite core, a fast Mosfet gate driver IC and a power supply PWM driver IC.

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atul_jangle
New Member

India
3 Posts

Posted - Dec 14 2005 :  06:46:39 AM  Show Profile  Reply with Quote
Sir thans for suggestion
does their is any special technique required for recovery of primery side inductor when i will drive that from power mosfet and its driver ic.or does the flybac diode work.

A.M.Jangle
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audioguru
Nobel Prize Winner

Canada
4218 Posts

Posted - Dec 14 2005 :  1:45:32 PM  Show Profile  Reply with Quote
All power Mosfets I've seen have a powerful diode as part of their construction from drain to source that will arrest any flyback voltage from the transformer's primary if the load is suddenly disconnected. The diode is slow to operate so add a 0.01uF capacitor in parallel with the primary to slow down the rate of voltage rise.

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abc
New Member

1 Posts

Posted - Dec 22 2005 :  3:46:34 PM  Show Profile  Reply with Quote
the caps ar inveted in polarity

ther is de original osilator

http://www.interq.or.jp/japan/se-inoue/e_ckt7_1.htm

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audioguru
Nobel Prize Winner

Canada
4218 Posts

Posted - Dec 22 2005 :  5:16:09 PM  Show Profile  Reply with Quote
quote:

the caps ar inveted in polarity

ther is de original osilator

http://www.interq.or.jp/japan/se-inoue/e_ckt7_1.htm




The Japanese engineer shows the capacitors with the correct polarity and explains how the circuit works.
He also explains that the circuit's power supply voltage is limited to the 5V Veb rating of the transistors.

The transistors in the inverter project on this site are operating from a 24V supply due to center-tapped transformer action, but the 2N3055 transistors have an absolute max Veb voltage rating of only 7V. I've never seen a silicon transistor with a higher voltage rating. The circuit would operate fine with old germanium transistors.

Therefore when the emitter-base junctions breakdown due to overvoltage, then a massive current flows in the capacitors which blows them up!

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Gus B
Apprentice

USA
149 Posts

Posted - Dec 23 2005 :  08:26:16 AM  Show Profile  Reply with Quote
Neither of the inverters from that site run on 24V. True the push-pull primary transistors will have 24V on their collectors when they are off, but that's it.

MOSFET body diodes...... this diode is a parasitic diode with the substrate, it wasn't put there by design!! For the most part, you don't want to turn this diode on because it's reverse recovery characteristic "sucks". It is very common for designers to put a schottky in parallel with it so that it NEVER turns on.


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audioguru
Nobel Prize Winner

Canada
4218 Posts

Posted - Dec 23 2005 :  09:54:52 AM  Show Profile  Reply with Quote
[quote]
MOSFET body diodes...... this diode is a parasitic diode with the substrate, it wasn't put there by design!! For the most part, you don't want to turn this diode on because it's reverse recovery characteristic "sucks". It is very common for designers to put a schottky in parallel with it so that it NEVER turns on.
Hi Gus,
The long reverse recovery time of the body diode is bad for a high frequency SMPS, but for this 60Hz inverter would be neglegible.

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John Doe
Apprentece

USA
14 Posts

Posted - Dec 26 2005 :  6:47:52 PM  Show Profile  Reply with Quote
One question... What happens if I have a 12/125 volts 500 watts transformer, also somewhat like an electronic multivibrator, can be a transistor, a mosfett, or a platinum system as the one that uses the old cars. This is for, to trigger transformer and induce 125 volts in the other winding. What would happen if I use an old relay voltage regulator as the vibrator (because they disconnect if a specific current travels it); also, with this disconnection, I could make a system that inverts polarity to simulate a square wave.
Thanks!

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