variation on the measurement

[IñigoP]

Hello,

I want to implement a MPPT algorithm. The logic of the algorithm is already working properly, my problem comes from the measurement of the electrical power. The measurement of the power value change on the same duty point, I can't get a stable measurement. This makes the MPPT algorithm work in a wrong way. Any ideas to solve this?

[GerdW]

Hi Inigo,

my problem comes from the measurement of the electrical power. The measurement of the power value change on the same duty point, I can't get a stable measurement. … Any ideas to solve this?

Improve this power measurement to solve your problem!

Which answer do you expect when you don't provide any substantial information?

How do you measure the power? Which kind of sensors? Which kind of DAQ hardware?

Any VI you could attach? How do you define "stable"?

[IñigoP]

Hi Gerd,

I'm sorry for the lack of information.

We have a circuit designed by us, with 6 LEMs (3 for the voltage and 3 for the current). Then after the signal conditioning we use the NI9205 to adquire the analog signals. This module is connected to a cRIO 9025. We filter the signal in the FPGA and we send the values to the RT, here we calculate the electrical power.

How can we attenuate the variations on the measurement (to hace a stable measurement)? Can this variations be noise?

[GerdW]

Hi Inigo,

after the signal conditioning … We filter the signal in the FPGA

Which signal conditioning?

Which filters in the FPGA?

we send the values to the RT, here we calculate the electrical power.

How do you calc the power?

Still no information on your VIs…

Can this variations be noise?

Yes, that's possible…

- You mentioned some PWM duties: do you synchronize the power calculation with your PWM cycles?

- To reduce noise you could implement some filters, either in hardware (preferred) or in software…

[IñigoP]

Hi everyone,

I have a really strange problem. I'm measuring some analog signals with a ni9205 and a cRIO9025. I actually know that the value of the signals is 0 because I have measured it with an oscilloscope, but intead of zero I obtain the waveform of the attached image. The Vr is filtered with a butterworth filter of 100Hz. You can see that the amplitude is almost zero but the waveform is still there. I also add the programe.

Any ideas?

[RTSLVU]

I would say it is noise, but without knowing the scale I am only guessing...

BTW: The vi you posted is nothing but variables and indicators. Where's the part that is taking the measurement?