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what is the formula of gain loop meter in PLECS small signal analysis tools?

+1 vote
hello everyone,

I was trying to understand the closed loop gain which is given by Vout(s)/Vin()s when implementing the gain loop meter, it says it measures the closed loop gain. my question is it the Vout(s)/Vin(s)? because when used I see an input from the Vout and the perturbation is outputted from the gain loop meter to the +/- block ,could it be the bode plot given by the gain loop metr is just the Vout/Verr as shown in this figure


best regards,
asked May 2, 2018 by EMdude (75 points)

1 Answer

+4 votes
Please read the chapter "Analysis Tools" in the PLECS manual and see the application example in this chapter.

If you right-click the Loop Gain Meter and choose "Look under mask" you see how the Loop Gain Meter is implemented. It adds a perturbation to the feedback signal and measures the response.

The result of the loop gain analysis is Vout(s)/Vin(s), where Vout(s) is the input of the Loop Gain Meter (output of the system under test) and Vin(s) is the output of the Loop Gain Meter (input of the system under test). Verr from your drawing is not available to the loop gain analysis and therefore is not considered.
answered May 3, 2018 by Oliver Schwartz (622 points)
Thak you Oliver, I just noticed it. however, as I stated in my question, I was trying to get the loop gain of Vout(s)/Verr(s), I placed it after the +/- block but found out that it is the same as placing it before the +/- block which means it is exactly as Vout(s)/Vin(s) because i just addition. my question How can obtain the Vout/Verr in this circumstances?

best regards,