Half bridge Inverter

Thread Starter

AmanRtx

Joined May 21, 2017
6
Hello
Can anyone help me identifying problem in this circuit,

I am making half bridge inverter using
1 Pulse generation through SG3524 of 1khz. Complementary pulses.
2. Gate driver Ic IR2108 to drive Mosfet IRF630N

SG3524 is working properly facing issues with IR2108. See the circuit diagram
 

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Thread Starter

AmanRtx

Joined May 21, 2017
6
Why are you using the Bc549 transistor, just input both outputs to the Ir2108?
The IR2108 Ic has HIN and LIN Bar as input that's why. So should I remove that BC549 and will give both outputs of SG3524 as inputs to IR2108. Does all ground needs to be connected?
 

Alec_t

Joined Sep 17, 2013
12,906
Because of gate capacitance it takes a while for a MOSFET to switch completely off. Unless you have a dead-time period (several uS) when Hin is low and Lin_bar is high, you will get 'shoot-through' (where a big current pulse passes through both MOSFETs at the same time).
Edit: Although the 2108 does provide some anti-shoot-through dead-time, this may be insufficient for MOSFETS having a large gate capacitance.
 
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Thread Starter

AmanRtx

Joined May 21, 2017
6
sorry i dont know about the dead time. Please let me know if this helps. Using IRF630N as mosfet and 1khz pulse
My guide told there wont be problem of dead-time. Whether all grounds needs to shorted? What should be the drain to source voltage of mosfet connected to high side?
 

ian field

Joined Oct 27, 2012
6,536
Welcome to AAC!

What issues?
How much dead-time are you providing between the Hin and Lin signals?
The chip does that anyway - the 3525 is specified for driving MOSFETs and might manage without a driver chip if the chip has the same Vcc as the half bridge.

Transformer coupling is more usual where the MOSFETs have a higher rail.
 

Dodgydave

Joined Jun 22, 2012
10,366
The IR2108 Ic has HIN and LIN Bar as input that's why. So should I remove that BC549 and will give both outputs of SG3524 as inputs to IR2108. Does all ground needs to be connected?
Yes remove the transistor, and feed both "Complimentary Outputs" to the Ir2108,
 
Hello aman,
I think you have got two problem in your circuit .
1. Remove the transistor.
2. You have not connected vs and com pin of you ir driver.This is your most probable issue.
Try it ,your system should work.
One more thing ,though you have frequency 1 k,you got to check that too,
Once confirm the frequency then do check the boot strap cap to appropriate value.
Again for 1k its ok but for higher frequencies you would need a high speed boot strap diode,
I would suggest to go through tahmids blogg on the same thing ,that would be immensely helpful.
http://tahmidmc.blogspot.in/2013/01/using-high-low-side-driver-ir2110-with.html?m=1

All the best.
 
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