Hi.
I write if you can help me with my problem:
I feed my full bridge MOSFET B25NM60N, Mosfet 600 V, with 29.3 VDC, and working good, but I feed the circuit with 29.8 VDC and my signal in the output (with resistance as load) is very wrong. My circuit gate is with 2 IR2111 with boostrap capacitor is .1 uF.
The signal i show the next:
Without problem:


This is my problem:

If you can help me, very thank.

 

Try lowering your supply back down to the tolerances specified in the datasheet: 25V or less. 29V is too much.

 

Try lowering your supply back down to the tolerances specified in the datasheet: 25V or less. 29V is too much.

But the MOSFET is for 600 VDC?? I dont understand, as this mosfet I want to feed with 600 VDC. Now, the 25 V is the max Gate-source voltage. The feed is VDS, different that Gate supply. Gate supply voltage is VGS, is the 15 VDC, as I feed the drivers IR2111.
My pulses I generate is a PWM signal the 40 KHZ, I dont believe that this frequency is a problem.
If you gcan help me, very thank.

 

Perhaps a schematic would help. Where are you putting your 29V?

 

Perhaps a schematic would help. Where are you putting your 29V?

I Attach the schematic of my circuit.



Beetwen nodes a and b exist a resistance of 100 ohms 250 W as load.
The voltage Vgs is 15 V, supply the drivers IR2111, as show the next schematic.


If you can help me, very thank.

 

I apologize for misunderstanding your comments earlier.

This is indeed a mystery. If you have connected everything according to your schematic, and if your drive signal is correct, the Vdd of your bridge should not matter.

 

Your UD4007 diode may be breaking down, or the voltage rating of your 0.1uF bootstrap capacitor may not be high enough, or the cap may be defective.

 

Do you have VS connected to either "a" or "b"?

 

Julius, please attach your files to your posts. They are no longer showing up from the site you posted them on.

I suggest saving them in .PNG format before you upload them, as the files will be quite compact.

 

Do you have VS connected to either "a" or "b"?

Yes I have conected VS in this point

 

The only thing connected to a and b should be the load. The schematic does not show Vs connected to a or b. Nor should it.

 

The only thing connected to a and b should be the load. The schematic does not show Vs connected to a or b. Nor should it.

Thingmaker3,
Attached is a typical application suggestion from page 1 of International Rectifier's datasheet for the IR2111. Please note that VS is connected to the middle of the bridge.

The bootstrap circuit will not work properly unless that connection exists.

 

Ah. Wrong "Vs." Never mind.

 

Ah. Wrong "Vs." Never mind.

I have conected as datasheet. My apologize

 

My apologies, actually. I misunderstood "Vs." You had it right.

I really have no idea why the circuit would not be working, save that some components or connections may be faulty.