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I have an ESC that powers 36v 3 phase BLDC motor. The ESC has limited functionality and can power motor only in one direction. If I switch manually two of the ESC to Motor phase connections, than the motor direction will change. Now, I want to do the same i.e. switching phase to phase connections with 4 power mosfets.

As in scheme, the blue ESC phase will be connected to Mosfet source and the drain will be connected to Motors yellow phase. The next mosfet will connect to ESC yellow at source and motor blue at drain. Two other mosfets will connect blue to blue and yellow to yellow.

I won't do the switching while motor is on so I assume it should be safe.

How can I connect MOSFET's gate to Arduino ? I need no pwm just ON/OFF.

enter image description here

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  • you want a "mosfet driver", opto-isolated if possible. i make my own with 3 red LEDs in series used as a photovolatic source driven by a white LED at 3.3v, which results in ~5v output. then the red cathode is connected to source, and the annode to gate. that way, there's no electrical connection to the MCU and Vgs never gets far from Vd... A small solar cell can work as well, light it with the MCU.
    – dandavis
    Mar 31, 2017 at 18:48
  • the Mosfet I am using is logical level so the gate voltage is about the same as arduino output
    – Naho
    Mar 31, 2017 at 19:37
  • well if you can share the ground with the MCU it's not an issue; but if you have to power it inline, you need to watch the max VGS
    – dandavis
    Mar 31, 2017 at 21:05
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    This is not going to be practical given that you basically need to switch AC power, you would far, far, far better off getting a bidirectional ESC or seeing if it is one of those which can have an unofficial aftermarket open source firmware installed. Additionally, this is an electronics question that has nothing really to do with Arduino.
    – Chris Stratton
    Apr 1, 2017 at 6:12
  • if it's AC, you need two mosfets back to back to allow current in both polarities.
    – dandavis
    Apr 1, 2017 at 13:48

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This is covered fairly well in an EDN.com “MOSFET pair makes simple SPDT switch” article. You would use two of the SPDT circuits to make a DPDT. Attach switch commons to yellow and blue, and attach the “switch points” of one circuit to motor yellow and blue, and those of the other vice versa. Attach both control pins to one Arduino IO pin. The picture below comes from the referenced article, which shows the circuit in use for a primary-power vs secondary-power application. See the article for details.

details and overview of circuit

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    Sorry I can't still understand the control part. In most switch schemes I have seen the MOSFET is used on ground wire, and the mosfet source is connected to arduino ground. But in case the source/drain is V+ how can arduino & mosfets have common ground?
    – Naho
    Mar 31, 2017 at 19:59
  • @Naho, I don't know. The capacitor may be related to having a common reference. But l guess I don't know enough about the ESC wiring to know whether grounds can be common. You might have to use optoisolators as someone suggested.
    – James Waldby - jwpat7
    Mar 31, 2017 at 20:39
  • This will not work, the requirement is effectively for an AC switch. Driving two of them in complement is the trivially easy part.
    – Chris Stratton
    Apr 1, 2017 at 6:10

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