Regen (again)

[Art Mander <ARTMAN@TRISTATEGT.ORG>]

     OOPS. In my post yesterday I mixed up "single-pole" with "single set
     of poles".  Sorry Dale, I don't have a bag full of monopole motors!
     The formula for AC machine speed versus poles is
     rpm=(freq)(120)/(number of poles).  The subject aircraft generator
     rpm=(400 Hz)(120)/(6 poles) = 8,000 rpm as stated by Rich Rudman.

     When I bring up technoid AC motors with regen, some folks make the
     leap to 150kW AC drives costing $30K plus.  Is there nothing
     in-between?  Take the 400 Hz 25 kW generator for $195.  Power it with
     a comparable sized three phase variable freq AC inverter, with 25 kW
     continuous rating and maybe 75 kW short term rating.  Dale, how much
     would this cost?  Not $30K I hope.  An industry standard 30 hp 60 Hz
     variable frequency inverter is only about $5,500 and it includes a
     rectifier section that wouldn't be needed in a battery EV.

     As stated in several posts yesterday, EV conversions aren't catching
     on very well.  Wouldn't regen give EV another edge over IC?  Diesel
     school buses used in the foothills and mountains around here have a
     "retarder" for extra safety.  Its a shunt wound DC motor mounted on
     the output of the transmission and connected to a big resistor.  In
     reality a dynamic braking system.  Now wouldn't it be great if more EV
     could brag about the added safety and energy efficiency of regen?  It
     sure wouldn't hurt our cause.

     Art Mander, Denver
Regen (again)