Modeling and control of PWM converters - Tutorial - Part 2 VM control

This is a recording of Part 2 of a three part tutorial delivered at Texas A&M university to a class of graduate students of the EE department.
I thank Prof Prasad Enjeti for inviting me to share this knowledge with the students of the course
“ ECEN 710 Switching Power Supplies ”
Outline of Part 2
PWM converters transfer functions
Fundamentals of system stability
Voltage mode control

[burakapaydin]

I highly appreciate the content of your work 👏👏

[sergepetrov]

This lecture and some other had motivated me to read Control Theory textbook. And for that to renew Complex Analysis knowledge. Now I seem to understand what is happening here.

[mohammadhassanzade]

thank you mr professor
very good video clip
best job ever

[two_number_nines]

Basically both Nyquist criterion and the bode plot say that the gain should be less than 1 when the phase is 90deg+. This sounds reasonable, because 90deg+ phase lag means the polarity of the signal is starting to reverse, therefore the error amplifier would be correcting the exact opposite of the signal it is designed to correct and with gain above 1 this mistake will get into a positive feedback loop throwing the system off of stability.

[MrBubblegumx]

Hello, thank you for this video. I have a question about 1:05:42. We put an ac source into the loop, while not breaking the loop open. Is leaving the loop closed the right way to measure loop gain? I would assume it is, because otherwise we would disregard the (probably really small) loading our feedback circuit puts on the output node.

[sparkanew]

Great Video!!!
What gain do we set for the voltage dependent source as i see it only defined as a table. I designed one for my buck converter but due to the unit gain of Vout to Don i cant get it working correctly. What is the remedy for this?

[EngineeringEssentials]

A highly valuable resource, Thank you.

[kiq]

When you say "encircling" I am assuming you mean the response is inside or ON the unit circle ? "On" I would think is same as poles on the j Omega axis and would possibly oscillate a sine wave ?

I know the response must be inside the unit circle to be stable.

[luzhouyang]

great ，but I have a question，Is there any relationship between oscillation frequency and cutoff frequency ？thank you！

[kkh]

Hello, Professor. Thanks for this video. I have some questions at 1:05:10. I don't really get this point at all. Why is the external AC source necessary? Why are these sources cannot be defined in the circuit? I understand that Vo*R1/R2 = Sf, Ve=Se. Is it wrong?