Few confusing things on a circuit that needed to be understood

Other Hardware Motors, Mechanics, Power and CNC
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There are a few things about this circuit that i am having problem to understand, this is an open source BLDC motor driver circuit.
This circuit have both sensor-less and sensor circuit but it is upto us what option to use, in my case i am going to use the sensor-less option because my motor does not have place to put hall effect sensor in it so i am using the back emf to make my programming a little bit smarter.

1-Why have they used N-Channel mosfet for both High and Low Side switching?
2-Why the VS(6) pin of IR2101 is attached to the output of the bridge?
3-Why are they using 74HC08 from arduino output to the Mosfet driver High Side input? why not just simple put it directly to the driver High side?
4-Why is shunt resistor used in this circuit?
5-What is the circuit with LM358? what does it do here?
6-What output does the LM339 is going to give when there is a BACK EMF detected?
7-I have studied that we need bootstrap circuit if we want to use N-Channel Mosfet for High side switching but if we are driving it via driver do we still need a bootstrap circuit or not?

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It does not seem to be an Arduino problem?

...R

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Robin2:
It does not seem to be an Arduino problem?

...R

the motor is being controlled by arduino so it is an arduino problem too.

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Good questions for one of the electronic design forums.

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jremington:
Good questions for one of the electronic design forums.

Sir i am using arduino to control a BLDC motor, it involves arduino, and other electronics.

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But all your questions so far are about "other electronics". Unless you have questions about the Arduino and its operations you need to ask whoever published the driver design about how it works.

Steve

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Mark248:
the motor is being controlled by arduino so it is an arduino problem too.

I suspect the Arduino will only come into the reckoning AFTER you have got your circuit working. In my experience Arduinos don't care what is going on inside any device they are connected to :slight_smile:

...R

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Sir i am using arduino to control a BLDC motor, it involves arduino

What questions do you have about the Arduino portion of the project?

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jremington:
What questions do you have about the Arduino portion of the project?

for starters, how to generate a dead time signal with arduino?

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delayMicroseconds()

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  1. N-channel mosfets generally have better specs than P-channel mosfets.
  2. The gate of the top fet needs a 'higher than motor supply' drive for full saturation.
    This voltage is generated by the bootstrap circuits of the IR2101 (C32/CV4 etc.).
  3. The second inputs of the AND ports can be used to disable all three, probably for driver enable/disable.
  4. Overcurrent protection.
  5. Amplifying that tiny voltage from the shunt, and switching state on a set threshold (R52/53).
  6. There is none. The internal 'diodes' of the fet clamp to supply and gnd.
  7. Don't understand.
    A high-side n-channel fet needs bootstrapping, which the IR2101 and surrounding parts provide.
    Leo..