[peggus]

I thought the Leaf was using a BLDC motor but I've seen references that it's a DC excited synchronous motor that does not use rare earth magnets, I'm not familiar with those. Anyone know more info?

What you're talking about is also known as a wound rotor synchronous motor. They're similar to sepex motors in the sense that the field strength is directly controlled.

Typically they have high efficiency across a wider RPM range than PM motors but slightly lower peak efficiency.