Hi,
You have type 1, 2 & 3 error amps for SMPS feedback compensation...
But what is the error amp called that is just a high gain inverting amp?...ie, not an integrating error amp.

Also, can you confirm, that using this (unknown name) error amplifer, there is no gaurantee in eg a Buck battery charger that you would reduce the chances of instability, by using it, instead of a type 1, 2 or 3 error amp?

 

It's known as the "release the smoke" error amplifier.

 

A SMPS that uses linear feedback will not be stable without compensation in the feedback error amplifier.
The inductor in the output causes a phase-shift in the feedback voltage that otherwise will cause instability or oscillation.

One exception is a hysteretic type (bang-bang) SMPS which does not require compensation since it does not use linear feedback, but has a comparator for feedback.
They tend to have more ripple in the output voltage, but that's usually not a problem for applications like powering digital circuits or battery charging.

The simulation of a simple buck regulator example is below:

 

Thanks, but i believe you are aware that current mode control gets rid of the output pole caused by the output inductor...it cancels it out.
What i am asking is how , generally, does an inv amp error amp compare with a type 1,2 or 3 error amp for stability?...better or worse?

 

Current mode has ONE pole at ωo, voltage mode has two, so current modes still needs to have a 6dB/octave slope
It's all in here:
https://www.ti.com/seclit/ml/slup340/slup340.pdf