Designing a simple Treadmill Controller based on Power Track Pro 97370

Discussion in 'Embedded Systems and Microcontrollers' started by nestbulala, Apr 19, 2017.

  1. nestbulala

    Thread Starter Member

    Dec 12, 2015
    104
    4
    My treadmill broke down and I want to design a controller and LCD display using PIC16F88. I started on the power for the DC Motor that is being controlled by a mosfet with the current sense circuit in case it is overloaded. My concern is the current sense which I get from this forum is of a different ground potential from PIC. My question is, can it sense even if of different ground potential and what is the reference if you measure it? Please find the attached drawing for your reference.
    Power Track Pro 97370 Treadmill Main Board.png Power Track Pro 97370 Treadmill Display Board.png
     
  2. nestbulala

    Thread Starter Member

    Dec 12, 2015
    104
    4
    Attached a picture of the board. Actually, the display board fails and i brought it to the supplier for testing the board. They swapped it to the running board and it was ok. But I misplaced the display board. I might have thrown it on the garbage. Now since I am learning on PIC programming why don't we give it a try. After some searching, I have come up with this circuit and with this forum of experts I have come for help. Any comments or suggestions would be highly appreciated. And I Thank You in advance for your help.
    Power Track Pro 97370M Treadmill back PCB.jpg Power Track Pro 97370M Treadmill.jpg
     
  3. nestbulala

    Thread Starter Member

    Dec 12, 2015
    104
    4
    Simulated from LTSpice for the current sense for the board to trip the relay when it reached 12A. Any advice on this circuit Guys.
    Current Sense 190V at 12A.png
     
  4. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    In your post #3 circuit M1 would need to be an NMOS device.
    By the way, posting your .asc files is generally helpful.
     
  5. nestbulala

    Thread Starter Member

    Dec 12, 2015
    104
    4
    Yes Alec_t, Thank You and I have changed it to NMOS and asc as attached.
     
  6. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    I don't see why you need a FET at all if you just want to activate a relay when sensed current is >12A. What FET will you use? It will need a Vdsmax rating considerably higher than 380V. If Q1 will be used to drive the relay, don't forget the free-wheel diode across its coil.
     
  7. nestbulala

    Thread Starter Member

    Dec 12, 2015
    104
    4
    In the main board, Q1 is FET that will drive the DC Motor rated 190VDC. Q3 will drive the relay that will trip the supply when it reach 12A. This is the main board schematics.
    Power Track Pro 97370 Treadmill Main Board.png
     
  8. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Diodes D1-4 are shown back-to-front. Q3 collector and emitter connections seem wrong.?
     
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