Of these 3 which is the most efficient motor, please? The SIRC, ECM or the PSC? Thank you for your help. Obviously I am just learning

 

After googling for a while, I suspect that a SIRC motor does not exist.
In that case, I would choose ECM as the inherently most efficient of those motors.
The problem remains, I am not sure of my answer.

 

I have no idea what a SIRC motor is?
Out of the two remaining I would also pick the ECM (which by the way covers many techniques).
This is in what context?
Max.

 

Thank you for your answer. We could not find out what an SIRC motor was either in the text or on the net. This question is about air conditioner motors. I am helping translate technical terms for a person who speaks English as a second language. Of the other two options offered the best he and I could tell the ECM motor is the most efficient. This site was recommended to me by my best friend. I believe the question has been answered to our satisfaction. Thanks again!