Demstifing the code working of the feed back from ADC to change the PWM dutycycle (See the link)

Status
Not open for further replies.

thannara123

Advanced Member level 5
Joined
Jan 7, 2010
Messages
1,602
Helped
122
Reputation
244
Reaction score
116
Trophy points
1,353
Activity points
10,615
I am confusing the following code which working in feedback control of an inverter
C: 
                    FBV = ADC_Get_Sample(FBCh);
                    if (FBV < 512){
                       FB_Step++;
                       if (FB_Step > 12) FB_Step = 12;
                    }
                    else{
                         if (FB_Step > 0){
                            FB_Step--;
                         }
                    }
adder = FB_Step << 5;
                    TMR1L = 0;
                    TMR1H = 0;
                    T1IF_bit = 0;

see more about the code


The above code is updating the ADC values repeatedly in a while loop and change the dutycyle with the "adder" b

My doubt is that the adder value is varying from 0 to 384 .

Then how achive the voltage stabilization ?
can anybody clear my doubt ?
 

Sort by date Sort by votes
Yes sir I seen it , but the table_offset value is not sustine any other value ,its only sustain "0" or "384"
it moves up 65% ,67.5%,70% ...... 95 % 97.5% 100% and vice versa .
not stay any other value
is it enough to stable the output voltage .

or may i need to give Offset_value according to each ADC volatge

ie is something like that

if(FBV<128)
{ set offset_value to 65% }
else if(FBV<256)
{ set offset_value to 75% }

which is better method
 

Upvote 0 Downvote
FB_Step can take integer values between 0 and 12, resulting in respective output voltage steps. Similar to voltage control with a tapped transformer. Expect that in steady state FB_step will jump up and down between two adjacent positions.
 
Upvote 0 Downvote
Is that jumping is better for stabilization ?
I feel it's not good may i wrong
--- Updated ---

May that jumping lead to a fluctuations ?
 
Last edited:

Upvote 0 Downvote
Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…