What is the difference of having type 1, 2, 3 opamp compensator?

[Patrick66]

Hello everyone, I would like to ask what is the difference between having type 1, 2, 3 opamp compensator for a flyback converter in LED driver? If not mistaken the system of the LED driver in DCM as shown in the figure below is a type two compensator with opamp and optocoupler. Is it possible to build an LED driver in DCM with a flyback converter having a compensator circuit with either type 1 or type 3 compensation? Thank you everyone for your time and guidance.

[MathWizard]

I've seen some of this stuff but I barely remember it, and I still haven't tried to find the loop gain around any sort of switching circuit with magnetics.


Actually I just bought some cheap transconductance amplifier chips, so whatever their spec's will allow, some day I'll experiment with them, and I'll thank myself for already having them.

Demystifying Type II and Type III Compensators Using Op-Amp and OTA for DC/DC Converters
https://www.ti.com/lit/an/slva662/slva662.pdf?ts=1709406965653&ref_url=https%253A%252F%252Fwww.google.com%252F

[David Hess]

The advantage of type 2 and type 3  compensation is higher bandwidth for better line and load regulation.  Type 1 compensation can work, but its bandwidth may be unacceptably low.

[Konkedout]

One big hazard of too slow a compensation loop (very likely problem with type 1) is overshoot on turn on.  You might briefly get too much current through the LED and damage something before the output settles on its proper value.

The design you present sorta looks like type 2 but there are one or two questionable parts in there....