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Hot!BLDC Closed loop using dspic30f3010

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prasanth R
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2020/07/01 10:53:58 (permalink)
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BLDC Closed loop using dspic30f3010

Hi,
      I am trying AN957 closed loop code. Our motor have 23 pole pair , 700 RPM . I changed these parameter only in that code and one more thing TMR3 get overflow in slow speed so that i changed that 16bit timer into 32bit timer mode (TMR2+TMR3).
but when i call speed calculation function, actual speed not get changed quickly so if(actual speed < desired speed) function called so many times PDC get increased so quickly,then after some delay actual speed get increased > desired speed. I used this code for E-Bike but its speed up/down continously on load because of acutal speed delay.
 
timer3value = TMR3;
TMR3 = 0;
timer3avg = ((timer3avg + timer3value) >> 1);
    why we are shifting and adding TIME instead of direct TMR3 for actual speed calculation. Plz anybody help me out to get quick actual speed.  I have no time to complete this project so plz Reply me as soon as possible.
#1

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    JPortici
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    Re: BLDC Closed loop using dspic30f3010 2020/07/01 11:52:23 (permalink)
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    assuming that x is unsigned
    x >> n ---> x / 2^n
    x << n ---> x * 2^n
     
    so
    avg = (avg + tmr) >> 1 means avg = (avg + tmr) / 2
     
    the code stores TMR3 value and then reset TMR3 so that speed measurement is not affected by the time it takes to perform the calculations
     
    The motor speed oscilaltes because you have to adjust the PIC/Compensator parameters. That's your job and will take some time
    post edited by JPortici - 2020/07/01 11:57:32
    #2
    RISC
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    Re: BLDC Closed loop using dspic30f3010 2020/07/01 12:13:09 (permalink)
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    Hi Prasanth,
    dspic30f3010 is a very old...and expensive product..Why don't you use a more recent one like the dsPIC33EP....family ?
    There are lots of new motor algorithms and application notes which can be run on dsPIC33EPxxxxx products...
    If you absolutely want to use 5V products then look at dsPIC33EVyyyyy
    Regards

    For support make sure to check first here : http://microchipdeveloper.com
    There are hundreds of PIC, AVR, SAM...which one do YOU use ?
    #3
    PStechPaul
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    Re: BLDC Closed loop using dspic30f3010 2020/07/01 13:42:49 (permalink)

     
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    prasanth R
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    Re: BLDC Closed loop using dspic30f3010 2020/07/03 23:03:05 (permalink)
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    Hi all,
    Thanks for your reply. I need very frequent speed measurement.
    The time period between two hall signal  can be read using timer.whenever any hall signal comes the timer will start & will reset on other hall interrupt.so i've to do timer calculation in all three hall interrupts?In AN957 application note.it is written as in each rotation only to a particular value the timer will start counting & it's only in hall A interrupt..
                                                    pls reply...
    #5
    mlp
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    Re: BLDC Closed loop using dspic30f3010 2020/07/07 08:04:18 (permalink)
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    prasanth R
                                                   pls reply...

    Post your question in the correct forum (dsPIC is not 8-bit, so should not be here) and you might get more replies.

    Mark (this opinion available for hire)
    #6
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