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TIDA-01063: Sensing current range of PCB Rogowski sensor

Prodigy 160 points

Replies: 3

Views: 56

Part Number: TIDA-01063

Dear TI expert,

I am finding a low cost sensor to measure a low current for overlaod protection,  current range from 0.16A to 5A, 50/60Hz.  I would like to know if the PCB Rogowski sensor can sense current down to 0.16A, if yes,  how about the accuracy and linearity performance? and how about the PCB size? if the size will be bigger when designed to sense lower current range?

Best regards,

LC

 

  • Linda,

    Can you provide more details on the required accuracy for this system? Rogowski coils have a wide measurement range, but you may have worse readings at the lower currents due to the lower output voltages produced at these currents. In the TIDM-3PHMETER-ROGOWSKI design, external Rogowski coils were used to obtain 0.5% active energy accuracy (see Page 11 of TIDU474 for results). Please note though that TIDM-3PHMETER-ROGOWSKI uses external Rogowski coils instead of fabricating the coils on the PCB.

    In addition to Rogowski coils, there are also other options for current sensors, such as current transformers, shunts, and hall-effect sensors. If a shunt is used, you may need an additional circuit to boost the output voltage from the shunt, which can be done using an external op-amp based circuit or an ADC that has an internal programmable amplifier. If the current sensor must be isolated, you can add isolation to the shunt using isolated amplifiers (such as our AMC3301) or isolated modulators (such as our AMC1106M05 and AMC130x devices). For compact designs that require isolated current sensors, the TMCS1100 hall-effect current sensor is also a good option.

    Regards,
    Mekre

  • In reply to Mekre Mesganaw:

    Thanks for your reply, Mekre.

    Yes, we have products  using  external rogowski coils that can get a good accuray 0.5%, we want to design a PCB rogowski coils sensor ( fabricating the coils on the PCB ) to decrease the cost,  but not sure if this kind of sensor can use to sense a current range 0.16A~5A with a small size PCB, we need an accuracy of about 2%.

    Regards,

    LC

  • In reply to Linda Chen:

    Hello Linda chen 

    The rogowski coil in this TI design TIDA-01063 is designed to measure 1000 A.

    The output of the Rogowski coil   provides  107 µV.for a 10-A 50-Hz sine wave current  input. 

    The output for every amp input is 10.7 uV and with the current rogowski coil the output at 5-A would be  53.5  µV.

    A precision amplifier with high gain and low noise  might be required for scaling the rogowski output as shown in the reference design. 

    The rogowski voltage output is :  V = M  X 4.44 X   Fin X  I RMS  ( equation 13 in the design guide)

    For 0.16 to 5A measurement range, if you are considering using PCB rogowski coild with cost as the main criteria yo may have challenges.

    There is a calculator provided in the Design files (8) section that you could used to optimize the rogowski coil design for your application.

    In the same section all the board design files including  gerber is provided  that can be used to fabricate and test the performance.

    Based on the application and the end equipment, you could consider using alternative approaches for current measurement including using hall sensors.

    Regards,

    Sreenivasa 

     

    Even with the scaling amplifier measuring 0.16A , 

    The dia of the coil  in the current design is 60 mm.

    . For a higher mutual inductance, the PCB coil can be cascaded in series.