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Current Regulation into a heavy inductive load

Fabrice Seuret
Prodigy 30 points

Other Parts Discussed in Thread: OPA549

Good morning,

I am looking for a solution in order to drive a current into a heavy inductive load and I would like to know if a High-Voltage, High-Current OPERATIONAL AMPLIFIER like OPA549 could be a good way.

On railway track there are magnet which send 2 Status by induction.  Depending on the Speed of the Train, a current wave is created on the track magnet.

In order to simulate the Speed of the Train in laboratory, we would like to drive a current into the track magnet.

The track magnet is an inductance of 800mH / 55ohm and we would like to drive a current up to 1A. The command Signal is a voltage Signal between 0-10V.

The power supply is 60V. As the Train drives up to 200km/h, the current should increase and decrease in 4ms.

Can anybody confirm that an High-Voltage, High-Current OPERATIONAL AMPLIFIER like OPA549 can be suitable.

And can you help me to choose the right Driver circuit.

 

Thanks a lot in advance for your advice.

Best Regards

Fabrice

Magnet.pdf

  • 0
    TI__Guru* 93105 points

    Hello Fabrice,

    The OPA549 is our highest output current operational amplifier. It is rated as being able to deliver a mimimum of 8 Amperes of output current. The OPA549 is capable of driving an resistive/ inductive (RL) load providing the safe operating area (SOA) limits are not exceeded (correct thermal environment), the circuit is properly stabilized, and appropriate transient protection is applied to protect the OPA549 output. It is often used as a motor driver where the motor represents a compex RL load impedance that can change in relation to where the motor is its run cycle, and with its loading. 

    You mention a command voltage of 0 to 10 V, and a drive current up to 1 Ampere. Are these dc levels, or are ac signals involved? Are you trying to control output current with a voltage input (V to I conversion)?

    Also, you mention using a 60 V supply and assume that means a single polarity, +60 Vdc supply. The OPA549 has a common-mode input voltage range that extends to 0 V on the low end. That covers the low-end of 0 to 10 V input range. However, the output may only be able to swing within +2 to +5 V of ground depending on the load current. Using a dual polarity supply would allow the output to swing to 0 V, and even negative. The supplies might be +/-30 V, or something asymmetrical such as +50/-10 V. Reducing the supplies to the minimum required will help reduce power dissipation and help keep the OPA549 operating within its SOA limits.

    Your information indicated the current should increase and decrease in 4 ms. The OPA549 has a rated gain-bandwidth product of 900 kHz, and slew rate of 9 V/us. The circuit configuration, load and any required compensation would determine if the OPA549 could ultimately provide the required ac performances.

    Regards, Thomas

    PA - Linear Applications Engineering

  • 0 in reply to Thomas Kuehl
    Prodigy 30 points

    Hello Thomas,

    Thank you for your information.

    I need to go a bit further in my thinking, but it seems that the OPA549 is not powerful enough.

    Kind Regards.

    Fabrice

  • 0 in reply to Fabrice Seuret
    TI__Guru* 93105 points

    Hello Fabrice,

    Indeed, you want to make sure that any solution you settle on will do what is needed and is reliable.

    Should you find you do require a higher power operational amplifier than our OPA549, Apex Microtechnology has a wide selection of power operational amplifiers that you may want to review and consider for your application. TI is not associated with Apex Microtechnology, and I mention them solely to assist you with finding a solution for your application.

     Regards, Thomas

    PA - Linear Applications Engineering