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Original question:

TIDA-01063: PCB Rogowski Coil Design

TIDA-01063: Rogowski coil for High current pulse measuring

fateh MONDER
Prodigy 10 points
Part Number: TIDA-01063
Other Parts Discussed in Thread: LMC6001, UCC21521,

For a defense project, we need  to measure a 2500 Amps pulse current with a rise time of 2-3 micro secs.

This pulse is produced by discharging a 0.3 uF capacitor charged to 5000Volts- the load being a small impedance of >2 ohms.

The switch to do this discharge is an Infineon IGBT -FZ750R65KE3.  The pulse frequency is low - every 10 secs or so.

The event sequence is-  Arm the HT( a voltage doubler )  feed to 5600V,  Charge the Capacitor to 5000V ( sensing by measuring current  through a 1 Gohm Resistor and V drop

across a 100K resistor). An Electrometer grade LMC6001, op amp gives a low imp. signal for display and control.

Then  one can chose to FIRE  or  ABORT the run. High Voltage Reed switches are used with appropriate resistors for CHARGE and ABORT functions.

For FIRE , a 18V -100 microsec - pulse from an IGBT driver chip ( UCC21521) is used.

Inspired by your TIDA-01063 and related efforts using Rogowski Coil, We  have designed and made a few pieces of this Coil.

For signal amplification, we are using  AD8421- Ins. Amp at a Gain of 100.

Beyond this we, need a little hand holding for Calibration etc.

Your expert comments will be of great help.

Fateh Singh   +919988111195-  ( fs_monder@yahoo.com)

MONTECH INSTRUMENTS, 181/31, Ind. Area CHANDIGARH-160002. INDIA.

  • 0
    TI__Prodigy 240 points

    Hello Fateh SIngh,

    Thanks for referring our reference design for you application.

    Based on system description shared by you i assume the application is to sense high frequency, high current amplitude pulse current (Square shape) using isolated current sensing. 

    If you the query is if rogowski coil can support high frequency high magnitude current sensing. As mentioned in reference design the output will derivative of input signal so sensor output will have transient pulses during every change of step. An integrated will be required to reconstruct the signal. OPAMP low pass region beyond it's gain bandwidth can be used to get integration or high speed, high gain bandwidth op amp paired with ADC with digital integration can be used to reconstruct the signal. 

    An instrumentation amp from TI portfolio can be used instead of ADI device. You many need to look into sensor output magnitude for pulse frequency as output voltage is proportional to signal frequency to determine signal condition gain. In case of instrumentation AMP with high gain usually high frequency will lie in low pass curve. Cross verify the gain magnitude from AC plot and sensor gain can help you to determine if signal is sufficient with respect to ADC minimum resolution for determine need of calibration. Using the equation 10 mentioned in reference design sensor gain can be computed for square pulse signal or gain plot of figure 8 circuit can be used.

    I hope this answer you query and look forward to assist in your design.

    Regards,

    Srinivasan