how to generate sinusoidal PWM...

[kvrajasekar]

sinusoidal pwm

Hi,

I am using 16f72 asm code to generate sinusoidal PWM.I not getting idea to start,Theory says that sine pwm can be generated by comparing sine and triangular waves.

I know how to use CCP module.can anyone help me how to do the same using software.

Please give me some ideas to start my project

 

[AMK1971]

sinusoidal pulse width modulation

I don't know about the PIC but generally it can be like this.

1. Based on desired frequency (fo) decide the Counter/Timer clock(fc) and Timer overflow rate(ft). ft = fc/MAX(timer value)

2. Make a table of the "PWM duty cycles" for the desired frequency. the number of entries in the Table will be n = ft/fo

3. Enable the timer for PWM output and interrupt on overflow.

4. On overflow of timer, program a new PWM value from table.

 

[FvM]

pwm sinusoidal

There are lots of PIC PWM examples at microchip.com

 

[kvrajasekar]

sinosoidal pwm

Thanks for the reply...

Mr AMK1971 given me good logic..i have tried using CCP1 in compare mode,but i didnt get the correct output.Is the pwm will be generated only using CCP1 in PWM mode?

My input freq is 50HZ and switching freq is 20khz.

 

[hi_hedonist]

sinusoidal pwm

check the link

rbsfm.ej.am/Downloads/APPNOTE/PowerControl/H1105.PDF

 

[daviddlc]

pwm sinusoidal microcontroller

The PWM generated by a microcontroller will give you a square wave, then you will need to apply a process to convert it to sinusoidal, like a filter.

 

[Siniša]

make sinusoidal pwm

I don't know about the PIC but generally it can be like this.

the number of entries in the Table will be n = ft/fo

There is no need for that many entries. 0º to 90º table can be re-used in whole cycle.

 

[kvrajasekar]

pic program for sinusoidal pulse width modulation

Thanks for the above replies.I created 90 degree loop and inverted that according to the requirement.