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UCC21732-Q1: Drive Parallel IGBT Modules & Thermal Didoes Sensing

Part Number: UCC21732-Q1
Other Parts Discussed in Thread: UCC5870-Q1, UCC21732

Hi team,

  1. Can UCC21732-Q1 drive parallel IGBT modules? 
  2. If yes, can AIN be used to sense thermal diodes from individual IGBT modules in parallel? Objective is to sense high temperature from any module. However, I don't think parallel diodes would work. 
    1. What is the best way of sensing temperature from parallel IGBT modules? 
  • PY, 

    • Can UCC21732-Q1 drive parallel IGBT modules? 

    Yes. Note that you may need an external buffer in some cases depending on IGBTs Qg, number in parallel, switching fr3equency, and ambient temperature. 

    If yes, can AIN be used to sense thermal diodes from individual IGBT modules in parallel? Objective is to sense high temperature from any module. However, I don't think parallel diodes would work. 

    Without extra circuitry, you would not be able to distinguish the temperature in each one.

    You would need to mux the signals in order to do that.

    The only time the temperatures would not be close is if one driver fails and shorts drain to source or something like that, in which case, the thermal protection would not matter anyways and the event would be ended by the upper. 

    What is the best way of sensing temperature from parallel IGBT modules? 
    f yes, can AIN be used to sense thermal diodes from individual IGBT modules in parallel? Objective is to sense high temperature from any module

    UCC5870-Q1 has muxable 6-input 10-bit ADC which is perfect for this application (though the part is more expensive and complex than UCC217xx). 

    There are a few different solutions you can use if you absolutely must know temperature in each seperately. 

    You can do analog muxing and USE UCC217xx (I have not seen this done before, but it is possible and does not necessarily require any control from cold-side). 

    E.g. you could switch the NTC reading twice per PWM cycle, you wouldn't necessarily know which IGBT temp is which but you would be able to have 2 seperate readings. 

    Again, I do not think this is valuable enough for the cost. 

    You can also use an isolated amplifier to do the job, and rely on half. These are expensive however. 

    It might end up being cheaper to just use 2 seperate UCC21732 drivers to drive the IGBTs seperate so you can have 2 isolated channels. 

    However, I don't think parallel diodes would work.

    They can, you probably would just want a Resistor in series in case there is a difference. I assume you are talking about thermal diodes here, correct?

    Please let me know if there are any more questions. 

    Best

    Dimitri