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On Tue, May 6, 2025 at 09:33 AM, Tony Casey wrote:

Assuming you want to calculate the average inductor current:

.MEAS Imax max I(L_filter_dc)
.MEAS Imin min I(L_filter_dc)
.MEAS Imid param (Imax+Imin)/2
.MEAS Tstart when I(L_filter_dc)=Imid rise=2
.MEAS Tstop when I(L_filter_dc)=Imid rise=3
.MEAS Iavg avg I(L_filter_dc) from Tstart to Tstop

If I understand correctly, that would of course find the average inductor current over one complete cycle.

?

But Ankit wants to find the average voltage over three distinct time intervals, each of which is a portion of one cycle:

• The rising inductor current,
• The falling inductor current,
• The interval where the inductor current is zero.

These three intervals are identified as t0-to-t1, t1-to-t2, and t2-to-t3??-- or as d1Ts, d2Ts, and d3Ts -- in the second photo that Ankit uploaded earlier today.

?

That is a little more challenging because one wants to identify the starting and ending times of each of the three semi-linear portion of the I(L) waveform, but there is some noise (ringing) which makes finding the exact corners challenging.

?

That is why I recommended adding guard bands.? Instead of looking for

? ? I(L_filter_DC)=0,

Ankit may want to test for

? ? I(L_filter_DC)=50m

or some other number (75mV, 200mV, ?mV) that is not exactly zero, but large enough to be unaffected by ringing.? Admittedly it requires Ankit to accept the errors caused by measuring over inexact time intervals.? I think it may be a necessary trade-off.

?

The mechanics of putting that into one or a collection of .MEAS commands is another matter.? Perhaps the syntax Ankit used was incorrect (but we may never know because of unwillingness to show the non-working .MEAS commands).? Or perhaps the tested events never happened.? Unfortunately, the error message can be the same in either case, making it challenging to diagnose.? Breaking it up into multiple .MEAS commands does help and you can see where it fails.

The screenshot caption simply states "Calculate average value of a waveform under specific conditions using .meas command". So that's what I did, assuming the interval was 1 cycle.

For finding a good estimate of the start and stop times of the transitions, the best method is to look for the highest and lowest values of the derivative of the repetitive waveform, and then find the time when (say) 98% of those values are achieved, to allow for inconsistent peaks (better with Tmax in the .TRAN directive) , e.g.

.MEAS MaxdV max d( I(L_filter_dc)) ; max +v derivative
.MEAS T1 when d( I(L_filter_dc))=0.98*MaxdV rise=1 ; start of 1st +ve transition
.MEAS MindV min d( I(L_filter_dc)) ; max -ve derivative
.MEAS T2 when d( I(L_filter_dc))=0.98*MindV fall=1 ; start of 1st -ve transition
.MEAS T3 when d( I(L_filter_dc))=0.98*MaxdV td=T2 rise=1 ; start 2nd +ve transition

Then find the averages of whatever intervals are required.

--
Regards,
Tony