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TIDA-00917: electro magnetic field does not effect on gate drive board?!!!

Dave Hunson
Expert 1740 points
Part Number: TIDA-00917

Hi everyone

good day!

one thing that really  shocked me is ,how electro magnetic field does not effect on gate drive board?!!!

the first question that comes to my mind is 900Ampers /700volt IGBT switches  around 10 KHZ   generate enormous amount of electromagnetic field!

how this gate drive which is located in the center of the board can tolerate electro magnetic field and does not effect on gate drive outputs?!!!

would you please explain more about it ?

is that any note or factor to put on consideration in designing such a gate drive boards ? 

thanks for attention

Dave. 

  • 0
    TI__Prodigy 550 points

    Hi Dave, 

    Like with many things also here is the answer: "It depends ..."

    TI's isolators are not so sensitive to magnetic fields which can really be strong if one of the main conductors is close to the gate driver. This might probably affect transformer based solutions or gate drivers with magnetic coupling for isolation but not isolators with capacitive coupling. Our concern is more on the side of the rise time of the voltage between hot and cold side as well as strong electric field transients in proximity of the gate driver.

    The transients you may see from IGBTs switching 700V in like 100ns are still some order of magnitude away from the capabilities of the device on the TIDA you are referring to. It could handle 50kV/us straight through the isolation.

    So the question splits into two individual questions:

    • Can I ignore electromagnetic field effects altogether? Probably not. They would still affect the PCB and if the layout hasn't been designed taking care of all possible side effects then you might get a smoky surprise at first turn-on with large load. The high current transients could easily induce significant voltage in some traces nearby leading to false readings of current sensing amplifiers, short circuit protection, temperature sensing or other parts of the system with sensitive functions.
    • Do I need to be worried about the isolating gate driver device? As long as you stay within the datasheet limits the device will function properly. If in certain circumstances safe distances can't be obeyed then it is eventually necessary to simulate these effects in 3D space. 

    Does this answer your question? Do you have a concrete application you would want to discuss? Let me kow and we find some way to take the discussion into private message where we could add more experts for the individual themes.

    Thanks for bringing up the topic!

    Ingolf

  • 0 in reply to Ingolf Frank
    Expert 1740 points

    Ingolf

    thanks for your help .

    although in this TDA some important point about how to routing PCB for this application are pointed ,but do you have any reference design to know more about ,how to design HV High current switching PCB design 

    thanks for attention please   do not close the thread  to see if I have any more question about it or not then I will do it ,thanks :)

    Dave.