Author Topic: Factory AC Motor Selection (Read First)  (Read 3343 times)

Offline mizlplix

  • Administrator
  • Senior Member
  • ****
  • Posts: 1445
  • Country: us
  • "The more you look, the more you find."
    • The old  build thread....
Factory AC Motor Selection (Read First)
« on: December 10, 2012, 08:40:20 AM »
For many years, the DC motor has been the king in Electric powered Vehicles.  Beginning with the 1899 Baker Electric thru the current batch of DIY cars. 

When the "Big three" American car makers were called upon to produce a modern car, they chose AC Propulsion.

Even with proper gearing, the DC motor is RPM limited by armature design.  All brushed motors suffer from the same affliction. 

Enter the Nicola Tesla invented AC induction motor with no commutators, brushes or the need to mechanically induce magnetism in the rotor.  Automatically, higher speeds were assured with almost no maintenance.

Vehicle rated AC motors are made by a few manufacturers, HPEV, Baldor and Siemens AG, to name a few.  Unfortunately, their offerings are either lower end cost and power,  to extremely high cost and high power with nothing in-between.

This glaring vacant region leaves almost nothing suitable for the D.I.Y. EV builder. 

The current lower end (Affordable) offerings are decent for vehicles up to 3,000Lbs-(IF there are not too many hills). The high end units are not avaliable new from the manufacturers and must be scrounged from wrecks, but still command a high price and a still higher traction pack (Battery) voltage to run.

Enter the Curtis 1238R series controllers.  These are a great inverter/controller unit.  Where they are adequate for the current batch of production AC motors, they are too low voltage for the high-end, higher voltage motors.  My hope is that a higher voltage equivalent to the 1238R  is on the horizon.

The only solution is to build a custom motor that takes advantage of 100% of the capacity the 1238R can deliver and be affordable to the D.I.Y. EV builder.

At this writing, the industry standard is the AC50 by HPEV.  It is a really good, dependable motor for vehicles up to 3,000Lbs.  It is not slow, but it is not fast either.  It has a 0-7000RPM operating speed. The torque band is reasonable and will propel a 3,000Lb car adequately with at least two gears or more in the transmission.  But, your car must be under 2,000Lbs to use a direct drive system with this motor.

Unfortunately, most of our cars (and trucks) are in excess of 3.000Lbs.  What do we do if we want an affordable-adequate  AC propulsion system?

The big car makers got by the weight and transmission issue by going to ultra highvoltage battery packs/motors and controllers, which enabled them to go with a direct drive system.  Their motors ran up to 14,000PRM's, enabled by those higher voltages.  Their 11:1 (or more) final drive ratios allowed normal acceleration and the high RPM's gave them a decent top speed.

Make your own motor.......To some, a daunting thought.  To others, an entirely suitable way to go.

Where do we start?  That is what this forum is all about.

Creating a dependable, powerful, low voltage AC drive motor, without breaking the bank.

1930 Ford Speedster, AC50, full manual powerglide, 6.14gears, 38-130AH CALBs.