March 11, 2012

IRF 640 & IRF Z44 triggering with AVR Microcontroller(Proteus Simulation)

I am working with power inverter design for final year project. I am using AVR atmega 8535 microcontroller for triggering MOSFET and PWM control.

I started working with IRF 640 Mosfet (That was the only available to nearer electronics shop at that time).

An optocoupler IC MCT2E is used for isolation between low voltage side(Microcontroller) to the high voltage side (MOSFET side load). It is always suggested to do so.

Here is the circuit configuration i have used to trigger MOSFET. 
optocoupler irf640 triggering with power mosfet
Power mosfet trigger with avr microcontroller by optocoupler in proteus

But while working with optocoupler it is always desirable to use datasheet very carefully. That was the problem with my earlier configuration I blindly put 330 ohm to input side of optocoupler (obviously for current limiting) as we do with normal LED. so I was having 100 uS delay on output side. But that was not proper configuration  according to the MCT2E datasheet. So after studying datasheet and test circuit given in it i come to know that it is 47 ohm is perfect value. And I was able to reduce the delay upto 5 uS(that was desirable to our case).


Then after some successful experiments I replaced IRF 640 with IRF Z44 which was having higher current carrying capacity than the IRF 640.There would be no change in driving circuit as the both MOSFET are pin to pin compatible and gate pulse requirement for both of them is same.

I have tested the circuit in simulations and hardware.

here is the Proteus ISIS simulation of MOSFET triggering 

 

9 comments:

  1. What is the reason of the optocoupler if the ground seems to be common ?

    ReplyDelete
    Replies
    1. Actually there are three ground points in this circuit and all of theme maybe different!!
      1)ground of +5V for microcontroller
      2)ground of +12V for optocoupler
      3)ground of +20V that is high voltage which is to be switched..
      main aim of optocoupler is to isolate (1) from (3)
      here in this circuit shown above (2)and (3)are connected [as we have to apply gate puls to gate with respect to source.]
      main use of optocoupler is in isolating microcontroller ground from high voltage ground.
      if you are looking at fig then don't get confused because all the ground have same symbol(what else could i use?)..
      hope i made the point clear..

      Delete
  2. how to make 240V AC from 6V DC ?

    ReplyDelete
  3. Now I see, thanks for the explanation about the ground.

    ReplyDelete
  4. Hi, can you send the simulation file to my mail id gobinath31@yahoo.com.

    ReplyDelete
  5. THANK U , UR COMMENTS AND CIRCUIT ITSELF HELPS ME A LOT I WANT A C PROGRAM FOR H BRIDGE CAN U SEND IT TO MY MAIL rajeshrameee@gmail.com

    ReplyDelete
  6. cud u please post asm file... nd what is RV1 in d circuit

    ReplyDelete

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