Induction heater IR2184 overheating H-bridge

Induction heater IR2184 overheating H-bridge

Hello,

I'm currently building an inductive heater, basing on the attached schematic. It's a slightly modified version of the neon-john heater (neon-john.com/Induction/heater.htm) and dandyk (danyk.cz/induk3_en.html). My resonance frequency is about 271kHz.
Sadly I have a few problems with this circuit.
1st of all, it worked once, when the coil L3 was 6.8µH/20A and supply voltage ca. 70V. When supply voltage was driven higher, the L3 coil was getting extremely hot. Then I decided to change to choke for a bigger one. I used a core TX32/19/13, made of 3E25 material. I made 3 turns at this core, so inductance was about 130µH (measurement was done at 100kHz). From this point, the circuit doesn't work anymore. IR2184 delivers signals to gates, but nothing more happens. What makes my life much more complicated, is fact, that when I'm trying to make any measurements with my oscilloscope, main fuse in a room (B16 :shock: ) is falling down. I suppose there is some problem with PE/N line :???: The main voltage (+300V) is supplied from regulated autotransformer.
2nd - IR2184 is getting really hot. When I put 3k3 resistors instead of gates, the supply current of IR2184 is about 70-75mA. When I connect the gates, it's rising up to 110-120mA (!). Does anyone have an idea, why IR2184 is getting the temperature like 80°C? Now also SD input has +15V. Should I change that to +5V That was mentioned in given below topic:
https://www.edaboard.com/showthread.php?288782-use-of-ir2184-to-igbt-inverter&highlight=ir2184

Best regards from Poland!

Hi,

There are a lot of issues:
* the fact the the mains fuse trips tells me you don't understand your gruonding system.
* the bootstrap circuit us completely wrong. Never connect VCC and VB in a halfbridge system.
* bypass capacitors at VCC are missing
* an open_emitter without proper pulldown resistor (value) is not suitable to drive these clock signals.
....

Klaus

Hi Klaus,

thanks for your reply.

1) yes, you are right, in this case, I completely don't know why the main fuse trips. At my previous project, when I was measuring circuits by this scope, everything was ok. This time is not, so it makes me :bang::bang:

2) you are perfectly right, it was quite late when I was drawing this circuit in Eagle. Normally I'm working in an old-fashion way (paper +pencil) but for the forum, I prefer to draw schematic in Eagle (much more clean drawing plus all elements have already names).

3) Do you mean C4 and C5?

4)68k would be ok? I also added snubbers for STGWs.

Nevertheless, I'm still confused with the optimal parameters of coil L3. Is there any source describing proper calculations?