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UCC28950: current transformers in parallel

yelsing torres
Intellectual 340 points
Part Number: UCC28950

Hello
I am designing a voltage source with a 110Vdc input and a 400Vdc output, with a power of 3000W. The working frequency is 100khz. The input rms current is 50A. To measure this current, the application notes recommend using current transformers, but current transformers that are above this current are quite expensive and large. In the past I have implemented the current sensor with this transformer:

co.mouser.com/.../cst2010-1223901.pdf

the transformer worked perfect, and its price and size are quite good, the problems is that they are manufactured for a maximum current of 40A. My question is to know if it is possible to place 2 of these transformers in parallel in the primary, and in series in the secondary as in the next image

I do not know if the small differences between the transformers can be significant enough so that a large part of the current only passes through 1 transformer.

Thanks

  • 0
    TI__Mastermind 25570 points

    Hello Yelsing

    The parallel/series arrangement you show will work BUT you need to be very careful to make sure that the impedance around the primary connections are the same for the two transformers - in practice this would mean having a completely symmetrical layout for the two transformers. If you don't do this, you won't get equal current sharing between the two primaries and the result will be a measurement error and circulating currents from one primary to the other - the secondary currents must of course be equal.

    I'd suggest a chat with the CT manufacturer.

    Regards

    Colin