3 phase spwm inverter

[Mahmoud AbdElgleel]

Hello I have used Tahmid's code to generate single phase spwm without using eccp and it worked well
https://tahmidmc.blogspot.com.eg/2013/02/generation-of-sine-wave-without-eccp_16.html
how can i use this method to generate 3 phase spwm ? or how can i make phase shift 120degree
to generate 3 phase ?

 

[pradhan.rachit]

Which microcontroller will you be using?

You will require 3 PWM channels and 3 phase shifted look up tables to create SPWM for a 3-Phase Inverter.

 

[Mahmoud AbdElgleel]

First thanks for reply
I use pic16f877a
when i generated single phase spwm there were 32 sample for sin table when i tried it for three phase each sin has 32 sample but the o/p showed that there were only 3 sample per sin

Is there any other method except editing the code ?
thanks in advance

 

[abc_de]

Hello Mahmoud AbdElgleel
for three phase SPWM pic16f877a is not sufficent because of less efficent power module. you need very much hard work if you will use pic16f877

- - - Updated - - -

there are also many microcontroller which have 3 pwm module

 

[c_mitra]

Did you consider IR2130 or similar drivers? They are easily interfaced with microcontrollers.

 

[chuckey]

Sounds as though you have got your table names and table positions mixed up.
Frank

 

[c_mitra]

Use the idea but write your own code. It is not trivial to debug code written by some one else.

Few suggestions:

1. No need to store 360 sine table. One quadrant is sufficient. Keep 15 values for 0-90 degree in the lookup table and use that value to generate the other 3 quadrants.

2. For 360 degrees you will have 60 values. The next phase will start at 20th position.

3. The third phase will begin from the 40th position.

4. All of them will loop through 0-60 continuously. You will need to keep a lots of variables as counters.

5. You are doing software PWM and you will be needing timing details.