universal motor

[eng/ IBRAHIM]

hi all
i try control in ac universal motor speed.i use 16f877,4MHz
and use zero crossing detection to sync puls which trigger the triac
i want us pot to control of phase angle of trigger puls.
when i use PWM without ZCD the motor play unstable not smooth motion.any one know what is the code can used

D0 puls out
D1 ZCD
A0 POT input[/img]

[Bcox]

i am not sure how you would do this using the 16f877. Look into using the build in pwm feature. i am using this feature in another chip but am not trying to adjust phase. You might want to look at using a power pwm module. check out the ex_power_pwm.c example. This might be more up your ally with what you need. Good luck.

[eng/ IBRAHIM]

hi bcox
what is chip you using. and how you cotrol of load current.
wher can find the ex_power_pwm.c example

[Bcox]

For my application, I am just turning a high current solenoid valve on and off. We control the current by varying the duty cycle but it would be the same if you are controlling a motor with PWM. I am using an 18F4520, but we are using this because we needed to have large memory and low power and many ADCs. This has the standard PWM built in like the 877 but i am using the internal clock at 4MHz to achieve frequencies as low as 300Hz for the PWM module. A power PWM pic would be something like the 18F2431. you can find the example in your example directory of your CCS installation. should be something like: C:\Program Files\PICC\Examples depending on where you installed the program to.

All, Please correct me if I am leading Ibrahim in the wrong direction here.

[SherpaDoug]

Look at Microchip application note AN521 for the simplest and most reliable zero crossing detector you will ever find.
_________________
The search for better is endless. Instead simply find very good and get the job done.

[eng/ IBRAHIM]

hi
ok i make ZCD
but what is the code for sync output with ZCD and change phase angle.

[eng/ IBRAHIM]

hi
any one can help me for dimmer project by PIC

[PCM programmer]

You can use http://www.google.com to search the Microchip website
for application notes about dimmers. Use the following search string:

[eng/ IBRAHIM]

hi all
i try this code the phase angle changing sync with ZCD (pulse 50 Hz)
but the output is generated in half cycle only(when input pulse is 0)
i need generate output pulse at 1 & 0 of input pulse.
what is incorrect of this code



#int_ext
void key_interrupt(void)
{
INT phaseangle;
phaseangle=6;
if (input(PIN_B0))
{
OUTPUT_LOW(PIN_D0);
DELAY_MS(phaseangle);
OUTPUT_HIGH(PIN_D0);
DELAY_MS(1);
OUTPUT_LOW(PIN_D0);
}
if (!input(PIN_B0))
{
OUTPUT_LOW(PIN_D0);
DELAY_MS(phaseangle);
OUTPUT_HIGH(PIN_D0);
DELAY_MS(1);
OUTPUT_LOW(PIN_D0);
}

}
VOID MOTOR()
{
ext_int_edge( L_TO_H );
enable_interrupts(int_ext);
enable_interrupts(global);
ext_int_edge( H_TO_L );
enable_interrupts(int_ext);
enable_interrupts(global);
}

void main()
{


MOTOR();
}

[Ttelmah]

The EXT interrupt, can only interrupt on high to low changes, _or_ low to high changes. The best way, would be to move the connection to one of the high PORTB pins, and use the 'interrupt on change' feature, which is present on these, which will interrupt on both edges. However the alternative is:

[eng/ IBRAHIM]

hi all

i find the program in microchip site make a dimmer but this program use PIC12c508 I try convert it to PIC16F877A but it not play
how can use this way by PIC16f877a to control in ac motor?
Code:
http://ww1.microchip.com/downloads/en/AppNotes/40171a.pdf

[eng/ IBRAHIM]

hi all
any one have answer or help?

[umka]

cant a universal motor be run on a dc supply? so you can just use a straight PWM to control it rather than an AC variable frequency drive