Overload protection circuit in tl494 and sg3524 inverter

[hamid159]

I have made an inverter using tl494 and sg3524 chips but there is no overload protection circuit.what changes should I make for the protection circuit.

 

[Fidelis Anyanti]

Pin 10 of SG3524 is shutdown pin. You need to sense your load either from the sources of your fets or from the output of the inverter. logical 1 on pin 10 will shutdown the inverter and protect your output.

 

[hamid159]

i have a circuit in which pin 10 is grounded by a resistor of 10k...what should i do?inverters output is modified sine wave...so can it be used for sensing??

 

[milind.a.kulkarni]

In my view post your circuit diagram here so one can suggest you on this....it's very hard to imagine from only the post.....

with regards,

milind

 

[hamid159]

Here's the circuit diagram

 

[schmitt trigger]

you should do as Fidelis indicated:

"Pin 10 of SG3524 is shutdown pin. You need to sense your load either from the sources of your fets or from the output of the inverter. logical 1 on pin 10 will shutdown the inverter and protect your output."

The secret is how to sense the current....you could use either a low valued resistor or a hall-cell based sensor. See the Allegro's semiconductor website for suitable devices.
I suggest using the hall sensor since it provides isolation.
The output of the hall sensor may be fed to a comparator circuit, which will pull pin 10 "high" whenever the current is exceeded.

 

[kabeer02]

You can also use a current transformer to do that....

 

[hamid159]

Thanks schmitt trigger,,,,,,i'm using full bridge mosfet at the output..so source of which mosfet i have to join with pin 10 through small resistor???

- - - Updated - - -

can i connect pin 10 with reference voltage pin by a resistor????????

 

[schmitt trigger]

I believe I know what your circuit looks like, but without a full circuit diagram, I cannot provide an accurate suggestion.

 

[hamid159]

that's the circuit...both files contain the complete circuit....

 

[schmitt trigger]

A possible resistor location.

You must use a comparator like a LM393 to trip at voltages above 1 volt (with hysteresis). The comparator output will then drive pin 10 high. I chose V= 1 volt arbitrarily, you may use a value which will provide a standard resistor value.
Calculate the resistor value R =V/Imax and its power P =R*Imax^2

This is an absolutely basic circuit. Many further refinements are possible.