Motor Control Current Sense & Amplification

Discussion in 'The Projects Forum' started by jameseraymond, Oct 8, 2013.

  1. jameseraymond

    Thread Starter New Member

    Oct 25, 2012
    I have a motor control schematic and have some questions regarding how the current sense and amplification circuit works. From what i understand it is measuring the voltage difference across the Current Sense Resistor and then amplifying it to some degree for the DSP to handle. How much is it amplifying? Can someone walk me through its operation?
  2. jameseraymond

    Thread Starter New Member

    Oct 25, 2012
    I have browsed around and think I may have figured it out....

    The amplifier is multiplying the voltage across the Current Sense Resistor by a factor of 19.53 (R4/R1). The resulting voltage (call it Vout) is then sent two directions:

    1) To a Unity Gain amplifier where it is serving to help with the capacitive load???? The resulting voltage Vout is then sent to the DSP.

    2) To a Comparator where it checks to see if Vout is greater than 3.36V [R7/(R7+R6)]. The result is sent to the DSP. Working backwards, I can see that the current limit is 17.2A [(3.36/19.53)/10m].

    Anyone around that has experience with amplifiers and comparators?
  3. MaxHeadRoom


    Jul 18, 2013
    The .01Ω (10mili Ohm) sense resistor will be in series with the motor supply leads so the volt drop will represent the current through the motor.
    Last edited: Oct 8, 2013