H bridge using N mosfets torque problem?

Discussion in 'The Projects Forum' started by thekaiser11234, Apr 29, 2012.

  1. thekaiser11234

    Thread Starter New Member

    Apr 29, 2012
    25
    0
    hello im using My1016 motor wich is 14 ampere /24 volt 250 watt rated motor ,,
    im using an H bridge all NMOSFETS transistors and IR2110 driver

    the problem is when i measure the voltage delivered to the motor its 9v when i connect 12 v as volt for driving the mosfets and for the motor

    and the mosfets Drain/ source corresponding to MOTOR terminals have like 10.8 volt

    the problem that i feel tourque is reduced as i can stop the motor using my bare hands
    which i cant do if motor is connected to battery directly

    if im using the Driver and stopping the motor using my hands to stop it it gives 1,15 ampere MAX
    which is too low for the motor

    the mosfets get way too hot im using IRF3205

    im connecting the IR2110 to the gate of transistors using 330 ohm resistor

    im using " Arduino " with pwm frequency 500 hz,and duty cycle 98% (for the bootstrap capacitor )


    i hope its sufficient information for u and if u need more i can provide



    my 1st hope to keep going with the forum and to help others as u doo :)

    Thanx
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,347
    Hello,

    Can you post a schematic of the setup?
    That way we can see if there are corrections needed.

    Bertus
     
  3. praondevou

    AAC Fanatic!

    Jul 9, 2011
    2,936
    488
    Verify if your bootstrap voltages are at the correct level. With a 12V battery they are probably at most around 11V.
    The bootstrap cap is charged when the lower FET is conducting, i.e. it needs to be conducting for a time sufficiently long.

    And, yes, a schematic helps.
     
  4. thekaiser11234

    Thread Starter New Member

    Apr 29, 2012
    25
    0
    thank you guys for replying
    @praondevou wat do u mean with bootstrap voltages like which terminals u mean excatly ??

    @bertus
    yes i will provide u guys with the schematics by mid night as they r not available to me now
    :)

    thanks for showing interest
     
  5. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    488

    Pin 6 to Pin 5 (Vb to Vs).
     
  6. thekaiser11234

    Thread Starter New Member

    Apr 29, 2012
    25
    0
    [​IMG]
    C1, C5, C6 : 100uF
    C3, C4, C7, C8: 10uF
    C2 : 100nF Polyester Capacitor

    D1 : 1N4001 Diode
    D2, D3, D4, D5, D6 : Schottky Diode
    Q1, Q2, Q3, Q4 : IRF3205 Power MOSFET
    R1, R2, R3, R4 : 330 ohm resistor
    U1
    U2, U3 : IR2110 High and Low Side Driver

    PWM are fed into pins 10 and 12 on IR2110

    dc source is the motor battery ,12 v is for mosfets to operate and to be regulated to 5 v and used for ir2110

    im srry i m late and the schematic looks **** but i had do it again cuz the old schematic is not available to me :(

    any thing u wana ask please tell me
    hope u can help me
    thnx
     
  7. wayneh

    Expert

    Sep 9, 2010
    12,128
    3,049
    Maybe not relevant, but you need a good ground line for the motor current. You haven't really indicated any ground connection between motor power and control power. I'm sure you have one, but it needs to be more-than-enough. Use a nice fat wire until you sort this out.
     
    thekaiser11234 likes this.
  8. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    The sources of the upper FETs are not connected to the driver (pin 5 as far as I remember).

    Could you maybe bring this schematic into a more readable format? ;) Something similar to figure 28A in this Application note: http://www.irf.com/technical-info/appnotes/an-978.pdf
     
  9. thekaiser11234

    Thread Starter New Member

    Apr 29, 2012
    25
    0
    Vb to Vs shall be 12v ? for both of 2 ICS ??
     
  10. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    Yes, at least. Their capacitors are charged through the low-side FET.
     
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