LTspice, in SMPS, how can I plot a parameter averaged in each switching period?

[lastsummer]

Hello everyone,
I have a question about LTspice for power electronics.
how can I plot a parameter along the full simulation time, but it is averaged for each switching period?
That is to say, Can I see this averaged value changes along the time?
I know the .meas command can integrate between the period I set. But how can I have thousands of such integration along the whole simulation time?
Thanks so much!

Update:
PS: sorry for my bad description, I found a name for the type of average that I want to see, it is called "moving average". I want to see the "moving average" by each switching period.

 

[simonbramble]

I dont think I can help you, but what are you trying to average? Do you have an LTspice circuit you could post please so I can have a look at it? LTspice has a variable 'time' and you can edit the plot icon to include 'time' so the waveform is averaged over time. This is about as much I can say without knowing exactly what you are trying to do.

 

[lastsummer]

Hi Simonbramble,
Thanks for your reply. here I attach an LTspice file, for example, how can I plot the inductor current averaged in each switching cycle? which should be a smooth waveform without ripple, and keep changing along the whole simulation.

I dont think I can help you, but what are you trying to average? Do you have an LTspice circuit you could post please so I can have a look at it? LTspice has a variable 'time' and you can edit the plot icon to include 'time' so the waveform is averaged over time. This is about as much I can say without knowing exactly what you are trying to do.

 

[eTech]

Hello everyone,
I have a question about LTspice for power electronics.
how can I plot a parameter along the full simulation time, but it is averaged for each switching period?
That is to say, Can I see this averaged value changes along the time?
I know the .meas command can integrate between the period I set. But how can I have thousands of such integration along the whole simulation time?
Thanks so much!

Hi

Hold the mouse pointer over the inductor until it changes to a current meter, then click to display the inductor current wave form in the waveform viewer. CTL-Left Click the waveform label in the waveform viewer. A pop-up window will appear showing the AVG and RMS values over the length of the simulation.

eT

 

[lastsummer]

Hi

Hold the mouse pointer over the inductor until it changes to a current meter, then click to display the inductor current wave form in the waveform viewer. CTL-Left Click the waveform label in the waveform viewer. A pop-up window will appear showing the AVG and RMS values over the length of the simulation.

eT

thanks for the reply! Yes I can see the average and RMS over the length of simulation(or of the period that shown in the waveform).
But what shoud I do, if I want to see the AVG of each switching period? that is, not only one AVG value for the whole simulation, but many AVG values of each switching period?
Thanks!

 

[eTech]

Your asking for average but I think you mean peak for one cycle. Read the help info on “.measure” directive.

You can also zoom in, point and click to measure a cycle in the waveform viewer.

 

[simonbramble]

I'm not sure if you wanted to average over the complete width of the plot... and just have a number pop up on the screen representing that average, in which case eTech's answer is good. If you want a line passing through the middle of your inductor waveform that represents the average, then the attached will do this. What I did was set up a behavioural voltage source that outputs a voltage equal to the instantaneous current. I then filtered it to give the average. However, this output is a voltage and not a current, so I set up a behavioural current source to output a replica of the voltage, so you get a current. This makes it much easier to fine tune the filter components to increase/decrease the averaging etc. I am sure there are simpler ways of replicating the current directly, but filtering voltage is much easier than filtering current

If you want to zoom in to a precise part of the waveform, right click over the Time axis and set your interval as needed. This works for mine and eTech's answers above.

Have a play with the attached. If you celebrate Christmas where you are, have a good one

 

[lastsummer]

thanks so much you guys!
after I found the correct name for the type of average I want to get("moving average", or "sliding average"), I found this post in another website, which it solves the question by adding some lines of spice commands.

https://electronics.stackexchange.com/questions/140659/how-to-plot-sliding-average-in-ltspice/253337

thanks so much to all of you!
and Merry Christmas!