Divide power using triac ; formula ; calculation

[Vindhyachal.takniki]

1. I am using a pure resistive load & have to divide output power by using triac. Ckt has 220V ac

2. I have a zero crossing detector output signal at every zero so I get two signal in once complete cycle.

3. User can select 0.0 – 1.0 value & according to that I have to output the power .
e.g if user have selected 0.5 then I have to output half power during 0-180 phase of ac signal.

4. I have some calculation on when to turn on triac which i have attached.

5. Plz check if I doing it right.

6. If I am doing it right, currently I am calculating angle by hit & trial. But I have to do it in MCU, I don't know how to calculate it otherwise because formula contain arithmetic & trigonometry function as in attached .

[Andy Watson]

Looks good. I would avoid the real-time calculation and use a look-up table.

[Zero999]

Do you not have libraries for the trigonometry?

Yes, use a look up table. Pre-calculate x for the different fractions, using a spreadsheet and include them in an array in your program.

[Vindhyachal.takniki]

1. I have attached a file, in which it is explained how to do phase control.
2. First one is equal phase division. Which I have done correctly.
3. Second is equal power division. this is what I am trying to achieve, its calculation I had described in post#1.
I want to know if I am doing it correctly.