Headline: A VFD will NOT work here.

The SR motor in the Neptune is made by Emerson. SR motors are *not*
the same as 3-phase induction motors, not even close. The SR motor
has a sailient pole rotor with no windings. The unique aspect is that
the rotor has a different number of poles than the stator, so some
poles are always slightly out of line when others are lined up. A
stator pole that is slightly misaligned with a nearby rotor pole is
energized. Magnetic attraction "pulls" the misaligned rotor pole to
align it with the stator, thus producing torque. As soon as it is
aligned, torque would stop unless excitation is then switched to a
pole then slightly misaligned -- and so on.

The advantages to such motors a capable of very high speed because
there are no windings on the rotor, good torque at low speeds, wide
range of speed controllability. Disadvantages can be high torque
ripple and acoustic noise. A lot of innovation and good engineering
went into the Neptune to make it accceptably quiet.

A "sensorless" SR motor drive technique was developed and patented
( but never commercialized) by Honeywell.

On 23 Aug 2004 06:25:29 -0700, (Jeridiah) wrote:

Anyone have any ideas on how/if this can be used for something useful
w/o a lot of work?

The drive board in our 3 yr old Neptune killed itself in a big way.
Blew a hole in the main chip(I'm guessing it used to be some sort of
microcontroller, can't read the numbers on it anymore) and smoked a
few drive transistors. W/O the controller board I am not sure how to
drive this motor.

Maytag gave me the replacement board(and motor) under warranty. No
questions asked. It looks like they have made some updates. There is
a AC line filter added, some other tweaks to the drive circuitry, and
a MUCH better enclosure to protect the board.

JW