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Author Topic: CNC control spin mills  (Read 2196 times)
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coboltino
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« on: March 17, 2008, 12:42:05 00:42 »

If someone succeeds to help me.
I would want to control the speed of spin of the cutter of my CNC. The motor of the cutter works to 220 V Power 600 W 50Hz.
I have realized the sensor that finds 8 impulses for every spin (10000RPM = 1333 impulses).
I would be oriented to use a PIC16F876The regulation of the spin speed I would want to set up it through a tension from 0-5 volt through a pin analogic of the PIC.
My problem I do not know as to setting PIC to generate one it marks them PWM in order to pilot a TRIAC through a MOC3020 optoisolator driver that or synchronized with the mains net frequency it must read the impulses of spin of the spin and must correct the PWM in order to maintain the speed constant.
Practically I through an Analogic door of the PIC tax a tension from 0-5 volt that could be the speed of my cutter (2000-20000RPM).
The PIC must vary the PWM in order to catch up the established turns, if the varied cutter the spin the optical reader supplies the impulses and the PIC must correct the spin.
Perhaps I ask too much?
I must use a PIC of advanced class?
I make excuses for my very bad iglese and thanks for the aid
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fernandodiaz
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« Reply #1 on: March 17, 2008, 07:14:10 07:14 »

HI

You need use timer pic  as counter pulse and define period to size speed take value timers, next set timer0H timer0L  = 0
and need sync the crozing 0 phase when do this start delay no more to .01s --  min 0s in all phase  @50hz

Cuantify the desviation setpoint seed with real speed  and subtract
this = error speed desviation, make scaling

need make a pwm inverse for make angle start phase, is very diferent to pwm and hpwm normality used in CD
control ( is more easy use DC and igbt,or power mosfet, to control, speed )
the change  increments in AC is no Linear is senoidal, need make a funtion to iguality increments to keep
lineality numeric changes
when you using triacs with motors brushed ther is very much noise in the brush,  some times the microcontrollers
no run well, veri erratic operation.

see this links:

http://www.picbasic.org/forum/printthread.php?t=4199
http://list.picbasic.com/forum/messages/6851/6860.html?1073315426
http://www.picbasic.org/forum/showthread.php?t=4792
   
 
 
best regards
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coboltino
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« Reply #2 on: March 18, 2008, 11:35:14 23:35 »

Me document thanks
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