Using an AUTOMOTIVE MOSFET IRF1405 to Control Large Current Inductive

Discussion in 'General Electronics Chat' started by SpiroTech, Jul 5, 2009.

  1. SpiroTech

    Thread Starter New Member

    Jul 5, 2009
    1
    0
    Hi, I am after a circuit that will control 12v to 24v inductive loads which draw large currents between 50amps to 150amps.

    I am interested in microcontrollers using PWM (Pulse Width Modulation) to drive a mosfet such as IRF1405 that will in turn control the delivery of current to the inductive load.

    Also using a potentiometer as an input to the microcontroller to control the circuit.

    Any assistants would be most welcomed.

    Cheers for now.
     
  2. millwood

    Guest

    you will need to think about a few things:

    1) is the mosfet good enough? you will likely have Vds of about 1v with the mosfet fully on. that means a power dissipation of 150w at 150amp. assuming PERFECT heatsink, the temperature rise is 150w*0.5c/w=75c. and you derate the rated power dissipation of 330w for temperature at 2.2w/c, you get a maximum power dissipation at 74c delta of 330-2.2*75=160w. leaving no room for error.

    I would go with a beefier to3p or to247 / to264 device.

    2) gate capacitance: Cigs=5480pf. that is one monster to drive for a mcu, even at low speed. I would be very careful on that.

    3) mcu: with such large current inductor near-by, you better make sure that the mcu can operate reliably in this environment. PICs in generally have good resistance to interference.
     
  3. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    I have used the LT1158 half-bridge mosfet driver for motor controllers carrying such currents . It is a bit old now and becoming expensive ($6 to 8 at Digikey). It has feedback control to take care of shoot-through etc. and needs only one pwm input. That is, your mcu will not have to generate pwm for both the top and bottom mosfets.

    Here is its datasheet: http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1142,C1114,P1464,D2064

    Second, if all you want is potentiometer control, consider a dedicated motor controller to generate the pwm, unless of course, you want the mcu for other reasons.

    John
     
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