I've read that there are discussions about adding another category to the traditional two (AC and DC) motor categories.
It would be called electronically commutated (EC) motor, which would describe brushless DC, stepper, and other motors which cannot function unless there are electronic devices to drive them.
A three-phase induction motor driven from a variable frequency drive would NOT be classified as an EC, because if connected directly to an AC source it will still run. On the other hand, a BLDC cannot run if connected directly to a battery..
Unfortunately, I cannot find the original article...the author made a very compelling argument.
What do you think?