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Original question:

DRV401: Evaluation method of probe interface without coil

DRV401: Fluxgate probe use of DRV401

Pengfei Yao
Prodigy 20 points
Part Number: DRV401

I am evaluating DRV401 for developing a residual current sensor. I want to use a ungapped ring core as the probe to avoid magnetic unblance caused by multiple primary conductor, but I find it hard to choose a proper core because the DRV401 probe drive power is limited and the working frequency is high. A ring core with high permeability means high inductance, which is hard to be saturated by DRV401. Can I use a external circuit like push-pull to amplifier the voltage and current of probe? In such way it can be easier to drive probe core into saturated with a high frequency.

  • 0
    TI__Mastermind 32260 points

    Pengfei,

    Hello and thanks for using the forum.  The question I have is are you planing to use only one core.  Where will the probe be placed.  You need to have a gap in order to force the field onto the field probe.  The field probe and the compensation core are two different items.  The compensation coil drives the field across the field probe to zero.  The field probe needs to measure a magnetic field generated by your primary conductors.  If you trap the whole field inside a closed core you cannot measure the field.

      

  • 0 in reply to Javier Contreras4
    Prodigy 20 points

    I have some questions on it, 1.I think the compensation winding should be on the same core with the field probe to produce flux compensating the primary winding flux, making the core(or the probe) zero flux, isn't it? 2. I think a secondary core is used to improve transformer effect with compensation winding, and it is not related to zero flux compensation is it? 3. I find some fluxgate sensor design with a ungapped core, they typically use a higher excitation voltage and a lower excitation frequency to saturate the core, but using DRV401, I think with its low excitation voltage and high excitation frequency, it cannot saturate a ungapped core, thus working unproperly, is it?

  • 0 in reply to Pengfei Yao
    TI__Mastermind 32260 points

    Pengfie Yao,

    You are correct in the the DRV401 is limited on the flux gate probe drive and it must saturate the core with limited current and voltage.  On the transformer effect the ungapped and single core has better transformer effect because the magnetic coupling should be improved than an air gapped core.

    You are also correct in that the high frequency expected to saturate the probe is a limitations.  If you can find some core that can saturate with the limited drive of the DRV401 if may work but I do not know if the interaction will cause issues as that is not the way it was designed to be used.