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H bridge inverter help

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mrbuell

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Hello, I would like some help selecting an IC to control an H bridge (MOSFET) inverter. This is for a welder, the input is 300 V rectified. I am a bit of a noob, so a circuit diagram would be much appreciated. I've looked all over the internet and have only become confused. Please help.

Thanks :)
 

The original H-bridge is intact, but the gate drive circuitry is fried. I can't obtain parts or schematics so I thought that I would build my own drive. So 240 VAC is rectified to 300VDC and sent to the inverter board. It is a MOSFET based H bridge (full bridge?). Three MOSFETs are paralleled per leg. Each MOSFET is rated 600V, 20 AMP. Each leg has a 47 ohm resistor in series with a capacitor. This is either a snubber or flyback I think, not sure. I would like to build a gate drive with one or two IC's , and the frequency should be around 100KHZ (I think)

C
 

Did you cheak the output of your micro or pic,is their any pwm signal?
 
Yes, and it seems to be dead.
 

Does anyone know what frequency I should be looking for? Also, the IC should be rated for at least 400 volts, am I right?
 

If you are to use pwm then I suggest you programmed a pic it will be the best and safe,and why do you need 400v ic's,a normal H-bridge driver is ok for you.
 
Thank you Tahmid, very helpful. These drivers are for half bridges. I'm unclear on how to used these drivers for a full bridge. Do you know of any example schematics?
Thanks,
Colin
 

If one ic is half bridge then you use two of the ic,or else you use another ic like HIP4081,HIP4082ipz.this ic's are H-bridge ic's.

---------- Post added at 04:52 ---------- Previous post was at 04:45 ----------

you can also download their datasheets it will help you alot.
 
I think I understand now. Thank you for all the help. Regarding the HIP2082, the data sheet rates it at 80volts max. Wouldn't the 300volts in my circuit overpower it?
Colin
 

You can power the ic with 300v,i dont know about you desinge but you can power it with 15v Dc that what i normaly do to power my drivers.

---------- Post added at 05:18 ---------- Previous post was at 05:10 ----------

300v to power just a driver?no i dont think that can be posible,you are to power it with 12v-15v if posible but you can not power it with such voltage else you will end up blowing up you work.
 
you can use also Dual SCR module 25 or 50 amp and 600 to 1200 volts what you get easily.
and one double diode for half bridge, and two identical circuit for full bridge or even three identical circuit for three phase to boost the power,
and nice chip from seimen TCA785 to control half bridge, full bridge or three phase application.
if you go for TCA785 pdf file you will get nice workable examples too.
good luck.
 
Hi,
300v would damage the chip.
The IR2110 and such drivers are hi-lo side drivers, not half-bridge drivers (a few mentioned in the list are half-bridge drivers). There's a difference. You have to use 2 hi-lo side drivers with their inputs appropriately connected to drive a full-bridge at 300v.
I'll be out of town for the next 3 days. I will try to provide a diagram when I'm back.

Hope this helps.
Tahmid.
 

Here is the driver circute using ir2110.
 
Excellent! Thanks so much everyone. Kabiru, in your schematic, what is the "current sensing" supposed to be?

Most designs have some sort of feedback loop. Is this necessary for my purposes? All I need to do is chop the dc at a constant frequency.
 
Last edited:

Normaly a simple op-amp is used to sense the voltage drop across a resistors which control the shut down.

---------- Post added at 04:30 ---------- Previous post was at 04:16 ----------

but if you will use current transformer you dont need any op-amp their you can connect a very low value of resistors their to ground.
 
Here is a simplified sketch of my H-bridge inverter and the voltages taken off the MOSFETS. Output is 0v. The gate driver is a transformer isolated push-pull configuration with a secondary coil for each leg. The gate drive signal is perfect wave and voltage to each gate. Any ideas why I can't get this thing to work?

---------- Post added at 01:24 ---------- Previous post was at 01:21 ----------

Sorry, here's the sketch..
https://obrazki.elektroda.pl/60_1299716590.jpg
 

Yes mrbuel, that's H-bridge arrangment all you need is you HI and LOW side drive and dont forget to connect 10k resistor from gate to source of each mosfet, good luck.
 

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