Proper driver for unipolar 2.5a stepper motor control..??

Discussion in 'The Projects Forum' started by bhargav shankhalpara, Jun 22, 2013.

  1. bhargav shankhalpara

    Thread Starter Member

    May 9, 2010
    18
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    hello everyone, i need help in my sliding mechanism project...

    actually i am going to made one slider mechanism for one machine. Torque require for that is around 10KG. so i select stepper motor for turning shaft. and specification of that motor is...(SANYO DENKI MODEL NO. 103H7123-8653, 2.5A DC, 1.8 DEG/ STEP). i am going to control this stepper motor using ATMEGA8 micro controller ,due to motor higher current rating i am not sure that which type of driver i need for this type application.

    please send me link if you find any circuit for that or any particular IC for this application...
     
  2. BillO

    Well-Known Member

    Nov 24, 2008
    985
    136
    Any decent power MOSFET should do the job nicely. If you were to use something like a FQP50N06 you would not even need a heat sink on them with that motor. They can be had for under $2.00 each. Of course, the ATmega8 can handle the stepping pattern easily.
     
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  3. bhargav shankhalpara

    Thread Starter Member

    May 9, 2010
    18
    0
    Hello bill...

    thanks for your reply...

    as your suggestion I made circuit using power MOSFET. but I used P30NF10 instead of what you suggest FQP50N06 because this is not available in my hometown area so I use P30NF10. Now problem with that arrangement is stepper motor is only get very low torque even that cant run itself. to run motor I use 1.2amp and 12v power supply, is this happen due to this lower value supply or any other thing is not proper...

    I send you circuit which I made...

    [​IMG]


    please give any suggestion.. thank you advance...
     
  4. BillO

    Well-Known Member

    Nov 24, 2008
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    136
    The P30NF10 should be just fine, and your circuit looks good. The power supply seems a little weak.

    Since the motor is rated at 2.5 Amps and you will need two coils energized at once, then the power supply must be able to deliver 5 Amps.
     
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  5. bhargav shankhalpara

    Thread Starter Member

    May 9, 2010
    18
    0
    hello bill...

    i connect my circuit as above, and i give input to MOSFET through 10K resistor from ATMEGA8. I connect large current source as you suggest but still motor is not capable to rotate it self. but when i touch shaft of motor i feel some torque is porduce but it can't rotate. To verify that MOSFET switching proper or not, i connect LED followed by 10k resistor to drain of MOSFET instead of motor terminals... but LED glow fine as per proper sequence as i program. but i thing MOSFET not give much current path (should give full close path) for motor. please suggest any idea...!!!

    thank you...bill
     
  6. shortbus

    AAC Fanatic!

    Sep 30, 2009
    4,015
    1,531
    Are you saying that you are using a 10k as a gate resistor? If so that may be the problem. Gate resistors should be in the 5 to 10 ohm range for most circuits. There are exceptions to this rule of thumb, but starting in the 5 to 10 ohm range is a good starting place. Using a high ohm gate resistor slows the "turn on time" of the mosfet, so the mosfet may not get to full "on" before it is told to shut off. This would give the results your getting.
     
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  7. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    What diodes are you using for D1 through D4?
     
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  8. BillO

    Well-Known Member

    Nov 24, 2008
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    It would also be interesting to see the drive sequence you are using.

    Another thing you can try is switch one of the coil pairs around. In other words, put A+ where A- is now and A- to where A+ is now.

    I also agree that 10K is way too much for the gate resistor. Try maybe 150 Ohms or less.
     
    Last edited: Jun 25, 2013
  9. BobTPH

    Active Member

    Jun 5, 2013
    785
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    The MOSFET you are using is not a logic level, so you may need a higher gate voltage than your micro is providing to turn it on fully.

    Bob
     
  10. BillO

    Well-Known Member

    Nov 24, 2008
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    According to my datasheet, the P30NF10 has a typical gate threshold voltage of 3V and will pass 24 amps or more with a Vgs of 5V at a Vds of anything over 4V. The requirement here is for only 2.5 amps. It should be fine.
     
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  11. bhargav shankhalpara

    Thread Starter Member

    May 9, 2010
    18
    0
    hello SgtWookie...

    I am using general diode. part no. is 1N4007. Please suggest me if other than this is prefer for my requirement...!!

    Thank you...
     
  12. bhargav shankhalpara

    Thread Starter Member

    May 9, 2010
    18
    0
    hello shortbus...

    i will suruly change my gate resistor in my circuit and than check condition of stepper motor rotation...!!

    thank you...
     
  13. BobTPH

    Active Member

    Jun 5, 2013
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    114
    Unless the micro is running at 3.3V as many do these days.

    Bob
     
  14. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    What's the value of the Zener? I wonder why D1-4 the clamp diodes simply aren't tied to 12V?
     
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