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    Ac motor speed control

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    Hai friends,
    In my project I have to control speed of AC230V,50HZ,4A,single phase motor.I tried TRIAC BT136 with optocoupler 3041 but it switching on when the PWM is high but in low pulse its not working.....Then removed the optocoupler it working fine.
    Then used IRF540 but it always in ON condition.Its not responsible with PWM.


    Please provide suggestion to control the motor speed by using PWM controls

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    Re: Ac motor speed control

    MOC3041 is zero crossing detector device, use MOC3021.



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    Re: Ac motor speed control

    For starters..... you don't trigger a Triac with PWM. You trigger it with phase control.

    Phase control is a trigger delay from zero the zero crossing.
    Additionally, not all single-phase motors are suitable for speed control. They are limited mostly to shaded pole ones.
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    Re: Ac motor speed control

    Quote Originally Posted by FvM View Post
    MOC3041 is zero crossing detector device, use MOC3021.
    MOC3021 with BT136 is suitable for speed control or have to change any other TRIAC also..?



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    Re: Ac motor speed control

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    This is my circuit used to control the speed of the motor.
    But I not working...Motor is either switching ON or OFF condition only....

    I can't control the speed of the motor by using the PWM pin..
    PWM is working fine,i checked it by connecting an LED with PWM pin which used for control the speed of the motor.

    - - - Updated - - -

    Quote Originally Posted by schmitt trigger View Post
    For starters..... you don't trigger a Triac with PWM. You trigger it with phase control.

    Phase control is a trigger delay from zero the zero crossing.
    Additionally, not all single-phase motors are suitable for speed control. They are limited mostly to shaded pole ones.
    No already speed of the motor is controlled by an mechanical switch...



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    Re: Ac motor speed control

    Hi,

    as schmittt trigger already mentioned: donīt use PWM. It wonīt work.

    Read basics about phase control.
    In short: You need to detect zero cross of line voltage --> Then use a variable delay (the shorter the delay, the higher the speed) --> then trigger the Triac with the use of MOC3021.

    Klaus
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    Re: Ac motor speed control

    Quote Originally Posted by KlausST View Post
    Hi,

    as schmittt trigger already mentioned: donīt use PWM. It wonīt work.

    Read basics about phase control.
    In short: You need to detect zero cross of line voltage --> Then use a variable delay (the shorter the delay, the higher the speed) --> then trigger the Triac with the use of MOC3021.

    Klaus
    If we SWITCHED the TRIAC using delay function means controller have to do that work only,because it will comes under infinite while loop.
    To avoid this one I need PWM control..

    Is their any other way to control the speed of the motor by using the PWM control..?



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    Re: Ac motor speed control

    Variable delay doesn't necessarily mean software delay loop, it can also use zero crossing interrupt and hardware timer.



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    Re: Ac motor speed control

    Hi,

    A microcontroller PWM usually is not aligned (synchronized) to an external signal.

    But for phase control you need the mains zero cross as timing reference.

    --> any free running PWM (like a PWM usually works) will not work as phase control.

    *****
    Maybe you think the correct way, but in my eyes the phrase "PWM" is not useful (at least: misleading) for phase control.

    Klaus
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    Re: Ac motor speed control

    Quote Originally Posted by venkates2218 View Post
    If we SWITCHED the TRIAC using delay function means controller have to do that work only,because it will comes under infinite while loop.
    To avoid this one I need PWM control..

    Is their any other way to control the speed of the motor by using the PWM control..?
    No
    It is not synchronized with the zero crossing.
    My batteries are recharged by "Helpful Post" ratings.
    If you feel that I've helped you, please indicate it as a Helpful Post



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    Re: Ac motor speed control

    you have to check for zero crossing signal and switch on the triac with a delay from 0-10 ms . 0ms full on and 10ms full off



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