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High current, three-phase

Former Member

Hi everyone,

 

I am trying to create a three-phase current system. I will control a linear induction motor with it. I have managed to have three signals with three different phases using the PWM outputs of an Arduino. The problems is that I need high current: 10 amperes, or 20 amperes if possible.

 

My question is: is there any shield or any device I can use to supply such a current and control it? I have seen shields as this one: http://www.newark.com/infineon/dcmotorcontrbtn8982tobo1/evaluation-board-btn8982-dc-motor/dp/93X8231

They say they can work with 10 amperes but I do not understand how they can supply 10 amperes.

Any ideas?

 

Thank you in advance for your time guys!

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  • 0

    These sheilds are not working in a linear region, they are switching the output either all on or all off so power is really only dissipated during the transision (It works as a switch)

     

    when a MOSFET (The switching device) is on, it has a resistance measures in milli ohms so even 10Amps will only dissipate 10 - 100mW. obviously when off, there is no current and therefor no power disspiation

     

    As you hae already noted, using PWM is how the "Average" voltage is varied

     

    now for current limiting, a sense resister in the power circuit measures the current in the motor and when it reaches a preset value, will turn off the switch . because the load is inductive, the current is not instantly I=V/R, it builds up over time allowing the control circuit to limit the current but still provide the power to the motor.

     

    This is also how modern stepper motor drivers work. I am currently working with NEMA23 Steppers that are rated at 3V and 2.9Amps but the supply is 48V @ 10Amps, the system relies on the properties of an inductor to be able to control the power and not fry the motor

     

    Hope this helps

  • 0 in reply to Robert Peter Oakes

    Thank you for your answer Peter!

     

    I think I have understood more or lessimage.

     

    I just want to have three signals with different phase. My motor is a linear induction motor, and there is any danger for my coils to fry. I want to have constantly through my coils a signal that will be maximum 10Amps. I am thinking on using maybe an ESC (used for brushless motors) but they use the position of the roto to work. I find the same problem with other standard systems used for commercial motors (brushless, induction). Do you know any commercial device that will give me a three-phase signal whose amplitude and frequency I can manage? image

  • 0 in reply to gadget.iom

    Nice one Paul, you beat me to it,

    I was about to suggest VFDs (Variable Frequency Drives)

     

    I dont know what the motor Power / Voltage is yet but your suggestions should cover any Mains rated motors for sure

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