I have now a working half bridge circuit, and Im driving it with sinusoidal complementary pwm with proper dead time using arduino.



So far i have managed to solder two pieces of IR2104 ICs on a breakout board for testing and they are working fine.



But since then none of the breakout boards are working. I have broke maybe 8 of them by now.



The LO output signal is always working fine but the HI side is giving zero volts. Also HIN and LIN are working.
I have tried to solder the ICs with extra care using 350 C temperature and just for 1 or 2 seconds per pin. Also tried heat gun with solder paste 350 C with no help...

What am I doing wrong?!?

Thanks in advance!

 

You should have either zero signal on HIN or a valid PWM signal.
is this how you have it?

 

Yo only gave us half the information we need to be able to make a guess.
What is the load, and how is it connected?
What is the part No. of the output FETs?
You mention IR2104 ICs but the diagram shows IR2110. Which are you using?

 

I work at much higher speeds than you do but.....
U1-3 add capacitors.
U1-2 and U1-5 must connect to the Sources with a short wire. Not a loop up in the air.
C4 and C4a must connect to with short wires.

It is hard to make a bridge work on a bread board.
I cannot see well. I drew a red line how I think your grounds are connected. That is a very long run.

 

The load is a low pass filter with 0.8Mohms to ground.
But the circuit I believe is not the problem, since its working fine with 2 of the breadboards, before and after the broken ones... The IR2104 circuit is pretty much the same as in the pic but without the SD, VDD and VSS pins... The mosfets are IRF520. I thought maybe this is a known problem of the heat sensitivity of the IR2104...

 

the heat sensitivity of the IR2104..

The IC is hot?

but without the SD, VDD and VSS pins

more information. With out these pins?

 

The IC is hot?


more information. With out these pins?

No the ICs are not getting hot.
Yes IR2104 is 8 pin only...

So i am only changing the green breadboards, where the IR2104 is soldered. Rest of the circuit is the same...

 

Should we be using this schematic?

 

The mosfets are IRF520.

They have an absolute maximum Vds rating of 100V. If your supply is 300V it's no wonder the magic smoke is escaping.

 

Should we be using this schematic?
View attachment 318413

Yes its that circuit. With diodes at the gates.

 

They have an absolute maximum Vds rating of 100V. If your supply is 300V it's no wonder the magic smoke is escaping.

I only supply 15v to the upper mosfet at the moment. Idea is to supply 90V at the end...

 

Maybe this clarification helps?

I have now a working half bridge circuit, and I am driving it with sinusoidal complementary pwm with proper dead time using arduino. Here is an image of a working circuit, the load is a low pass filter with 0.8 Mohm resistor to ground. The IR2104s are soldered to the green breakout boards for testing purposes. Mosfets are IRF520. Input voltage is the same for IR2104 and mosfets: 15v. So the actual circuit seems fine and working.

But when I only change the IR2104, the green breadboard, the HI signal is always low. I have now tested it with some 8 different IR2104 ICs. The circuit works fine again after inserting the 'working' IR2104.
The circuit is pretty much this one:

But with diodes and 1k resistors at the gates of the mosfets like in this circuit:

The bootstrap capacitor is 22uF (50v). Lower capacitance values worked ok for the frequency of the output ac signal above 100hz, but became distorted below that...
The LO output signal is always working fine but the HI side is giving zero volts. Also HIN and LIN are working.
I have tried to solder the ICs with extra care using 350 C temperature and just for 1 or 2 seconds per pin. Also tried heat gun with solder paste 350 C with no help... I always test the ICs after soldering for continuity and I discharge the capacitors between changes...

 

I measured about 1.4Mohm between the pins Vb and Vs, and about 10Mohms between Vs and HO on the working IR2104. In all the broken ones I measured open loop on both pins. So i guess the ICs are fried ...

 

If you are attempting to build an H bridge on a plug breadboard you will suffer greatly.

The types of high current/high speed signals that the MOSFETs require necessitates a total rethink of the physical wiring.

Use a heavy Ground plane
bypass capacitors as close as possible to IC and FET leads.
Gate connections - as short as possible
Source and Drain connections - as short as possible

Otherwise... the parasitic inductance/capacitance/resistance of your circuit layout will cause endless problems.
It's MUCH more than just connecting point A to point B.

Read the details of the data sheet and even better, the APPLICATION NOTES - which talk at length about the physical layout requirements.

 

I am driving it with sinusoidal complementary pwm with proper dead time

How is that possible? The IR2104 doesn't have separate Hin and Lin inputs, and any dead time is managed inside the IC itself.

 

My bad.
I did not fry any of the ICs.
The working circuit IC was IR2106. The ones not working were IR2104. Putting Lin to +5v and sinusoidal pwm to Hin, the IR2104 works now.
I will also make a valid pcb from now on...

Thanks for help and sorry for this embarrassing mistake...