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SHORT CIRCUIT PROTECTION

Nithin N
Prodigy 170 points
Other Parts Discussed in Thread: UCD7100, UCC21750, UCC21732

Respected sir/madam,

I am building a short circuit protection for my H-bridge inverter, I tried to do by measuring the gate charge of the mosfet, As the gate charge decreases when short circuit happens.

But I am unable to measure the gate charge of the mosfet. I am referring to a paper for my project. which I will attach along with this.

If there is some another way for short circuit protection, please say. 

Kindly please help me to resolve my problemhoriguchi2015.pdf

  • 0
    Guru 284590 points

    What exactly do you mean with "I am unable to measure the gate charge"? What did you try?

    TI makes gate drivers with integrated protection features (e.g., UCD7100), and separate current sense comparators.

  • 0
    Guru 140200 points

    Hi Nithin,

    such publications are often a bit too optimistic. What did work in the laboratory under very controlled conditions need not necessarily be a useful method for daily life praxis. Have a look at the published detection scheme:

    At least 4 independent parameters (degrees of freedom) must be coordinated well, the gate resistor plus differential amplifier, the integrator and two threshold voltages. And the publication doesn't give any concrete numbers...

    So I would not use this concept.

    Kai

  • 0 in reply to kai klaas69
    TI__Guru**** 189399 points

    Hi, Nithin, Kai, Clemens,

    Thank you all for this discussion! Very interesting.

    We offer two manners of over current detection in our gate drivers: vds sensing and measuring current thru a current sensing resistor.

    For example, UCC21750 overs VDS sensing (aka desat) and UCC21732 has shunt resistor sensing.

    I would recommend you start with one of these solutions.

  • 0 in reply to Clemens Ladisch
    Prodigy 170 points

    AS I was making a fault protection individually without taking gate driver into account using the above research article mentioned above using the gate charge of the MOSFET.

    As the short circuit happens the Qgate decreases, so By measuring the charge of the gate by using an integrator  we can turn of the mosfet by cutting gate voltage.

    But the problem I am facing is I am not able to measure the gate charge.

    If there is an another method for short circuit protection Please let me know.

  • 0 in reply to Don Dapkus
    Prodigy 170 points

    Thank you so much for suggesting  me the gate driver.

    Is there a way to do without the gate driver IC? 

  • 0 in reply to kai klaas69
    Prodigy 170 points

    Thank you sir, can you suggest me any another method for this please?

  • 0 in reply to Nithin N
    TI__Guru**** 189399 points

    Unfortunately, I am unaware of any TI collateral that discusses other techniques.