Re: Q about multi-phase motors.

["William Korthof" <wkorthof@earthlink.net>]

> >Why only up to three-phase motors?
> 
> I think one of the reasons folks on the list are interested in
three-phase
> motors is because inexpensive three-phase industrial motors are available
> 'off the shelf'.
> 
> If you went to 5 or 7 phases, then you'd have to have a custom made
motor.

That would make sense for industrial motors, except that almost 
all of the OEM EV systems that use AC drive trains have custom 
motors specific to the application. You know, much higher RPM, 
higher frequency range, higher desired efficiency, and shorter 
required service life. I know that AC propulsion basically hand 
builds their motors to their own specifications. If there were a 
significant advantage to having 5,6, or more phases, I'm pretty 
sure they would have chosen to go that route. 
 

/wk