Motor Driver Circuit HELP! (FET issues)

Discussion in 'General Electronics Chat' started by Gambler, Aug 2, 2016.

  1. Gambler

    Thread Starter New Member

    Aug 2, 2016
    2
    1
    Good day all,
    Was hoping to tap into the experience of users on here to aid with a motor driver circuit I am having issues with. The driver being used is the IR4428 (low-side) along with an IRFB4615 Power Mosfet. The circuit is being used to drive a spindle motor on a CNC that is rated at 96V and 5.6A. So as far as the ratings go, there should be no issues from a technical standpoint, unless I am missing something very obvious. I have attached a schematic for ease of troubleshooting. I have also attached the PCB design, which is currently being used to test, as well as the data sheets that I have. The PWM signal being fed into the driver is varied between 0-5V. This is done with manual control (10k potentiometer) or Mach3 control (through HyCNC USB to parallel) which sends a computer generated 0-5V PWM. The circuit tends to function well using the potentiometer, for a brief time, as well as through Mach3. Again, it works briefly, and then all of a sudden the motor starts running at full speed and does not stop until the power is disconnected. Any insight as to why the FET seems to (I believe short) not want to work properly would be greatly appreciated!
     
  2. shortbus

    AAC Fanatic!

    Sep 30, 2009
    4,019
    1,542
    You say that your giving a variable 0-5V on the driver input. Your driver is expecting either a 0V or a +5V, not a varying voltage. The diver input is supposed to be a square wave, which is what a PWM signal is, not a steady voltage of a varying value. And the IR4426 is an inverted input, meaning it is on when the input is 0V.
     
  3. Gambler

    Thread Starter New Member

    Aug 2, 2016
    2
    1
    -apparently the wrong data sheet was provided. it's the ir4428 - currently no longer in production. I meant a PWM, not varying. It was getting a 0-5V PWM
     
    shortbus likes this.
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