PID Loop for Single Phase Inverter

Bhuvaneshwar kanade54447

Dear All,

I have implimented PI loop for inverter to generate 230Vac in output. (ommited D term)

While configuring Voltage PI with Current PI and apply short circuit test Voltage PI value increases a lot and vice-versa.

Please Suggest what to do in this case. If system in Current PI (Current Limit) what should be done for Voltage PI calculation.

And if System in Voltage PI loop what to do of Current PI loop.

I am new in PI loops and code written by me working fine in stand alone.

Thank You

over 12 years ago

0 Gautam Iyer over 12 years ago

Guru 192875 points

Hi Bhuvan,

Please go through the basic fundamentals first

Refer: http://perso.uclouvain.be/anthony.papavasiliou/public_html/LCL.pdf

Secondly, check for the correct algorithms for when these loops should be used. I'm using both these loops for the inverter application and follow a particular algorithm.

Regards,

Gautam

0 Bhuvaneshwar kanade54447 over 12 years ago in reply to Gautam Iyer

Intellectual 680 points

Hi Gautam,

Thanks for your suggestion.

Tha PI loop implemented by me is as follows and as per standard (i think, might not be perfect)

error = ref - feedback

prop_term = error * Kp

sum of error = sum of error + error

Integral term = sum of error * Ki

integral term > max value

integral term = max value

PID out = prop_term + integral term

this PID out i am using as multiplication factor (modulation index) for sine table.

I am running this loop after receiving ADC sample in same rate of PWM for sine wave generation.

I have omitted Derivative term.

Is this correct ? or need any modification ?

I have omitted Derivative term because it will make system slow (i think) that's why omitted it.

Should i include Derivative term in Single Phase sine wave inverter is it recommended or usefull ?

How to set Kp and Ki because in my case i have set Kp first then changed Ki to get good response ?

When i am applying certain havy load 50% on system it gives spikes at output and stables later.

How can i improve it ?

Sorry for so many questions because i am struggling with it from past 1 month.

Thank You in advance.

Bhuvaneshwar

0 Gautam Iyer over 12 years ago in reply to Bhuvaneshwar kanade54447