# [EVDL] Synchronous-induction hybrid motor?



## EVDL List (Jul 27, 2007)

> Metric Mind <[email protected]> wrote:
> 
> > Hi all,
> >
> ...


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## EVDL List (Jul 27, 2007)

> Zeke Yewdall wrote:
> > What is the advantage of a synchronous-induction motor in one?
> > And how do you design a motor like that anyway (not that I'm
> > going to try, but just trying to reconcile it with what I know
> ...


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## EVDL List (Jul 27, 2007)

Zeke Yewdall wrote:
>


> Metric Mind <[email protected]> wrote:
> >
> >> Hi all,
> >>
> ...


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## EVDL List (Jul 27, 2007)

Lee,

Neither of these three, this hybrid motor is highly salient,
basically field weakening is achieved by embedding small perm
magnets in certain pattern and shape, leaving air gaps.
So it's far from synchronous motor which distinctively cogs
if you rotate it by hand. Hybrid motor practically doesn't.

I don't know enough about the subject to explain clearly,
this is outside my competence. I can grasp the principle
while it's being explained to me, but half hour later
I can't reproduce the thought outloud 

Read this http://www.patentstorm.us/patents/5455473.html
but BRUSA motor is "inverted" - magnets embedded into the rotor
and the stator is identical to a regular induction machine.
Thus manufacturing is simplified, only rotor gets replaced
with hybrid one. And, given the cost of rare earth magnets
this days, this motor is cheaper than synchronous ones of
the same power.

Victor



> Lee Hart wrote:
> > Zeke Yewdall wrote:
> >> What is the advantage of a synchronous-induction motor in one?
> >> And how do you design a motor like that anyway (not that I'm
> ...


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## EVDL List (Jul 27, 2007)

Although I will probably never be a customer of Metric Mind 
I eagerly read everything posted by Victor.

It is because of people like Victor and Lee, among others
that I am on this list.

Victor's number one priority, like any business, is to
stay in business. He must charge enough to do so.

John in Sylmar, CA
Driving a Jet Electrica, awaiting the
Sunrise

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## EVDL List (Jul 27, 2007)

I have somewhere here(on an old harddrive, might be easier to google for
it) a circuit for using a slip-ring motor in an EV. it regenerates the
slip energy back onto the buss instead of dissipating it in a resistor
bank. It included a way to inject current into the rings to lock the
motor into synchronous mode.

People need to understand that, although slip rings use brushes, there
is no commutation and therfore very little sparking. Since the surface
is smooth a different type of brush and ring material is used. It lasts
a very long time and has less drag. (but usually 6 contact points)

The charts I have on what slip rings can do for torque profiles for are
very impressive. Basically it alters the impedance allowing max torque
at high slip which is encountered at the lower RPMs. Using this
technique could reduce the cost/complexity of a "hobby" or "startup" AC
drive. Newer AC drives are more capable than 20 years ago in effective
low frequency operation and combined with more sophisticated rotors
(that have different impeadences at different slip frequencies). This is
almost as good as a slip-ring motor so the AC drive has pushed out slip
ring motors in smaller applications. Larger motors and controls are
still available, the larger the motor the less the percentage of cost.

I do think an EV sized slip-ring AC induction motor would be the Drag
Race King on the AC side of the fence.
Using a slip ring motor without a slip-ring drive or starting resistance
and it will melt down.

Correct me If I am wrong Lee but shorting the windings is what you do on
a slip ring motor once it is up to speed, Resistance is inserted to
start it.

the chart I have shows

R - %resistance of resistance needed to get full load torque at standstill
T - %speed of 250% full torque 
A - % amps of full load amps

R T A
100% 100% 40% 
80% 125% 50%
60% 160% 65%
40% 210% 90%
30% 230% 110%
20% 250% 130%
10% 210% 165%
1-2% 85% 190%

Now this is at zero rpm, you can see that shorted(1-2%) is almost 2x
amps and less than full load amps where as at 20% of the high resistance
used to get the [email protected] stall gives us the best torque at modest amps
and 40% of max resistance gives us full load torque at less than half amps.

If I could show you the whole chart we would see that torque peaks move
from 0% of to 100% of syncronous rpm 20% resistance peaks at zero rpm,
10% peaks at 50% rpm and 1-2% peaks at 85% rpm.

I believe that this is all at fixed frequency. A good AC drive can
reduce the frequency so the slip percentage is less but it must give up
some of the field strengh. I think it is the 250% at stall that we give
up. Limiting us to full load torque.

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## EVDL List (Jul 27, 2007)

[No message]


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## EVDL List (Jul 27, 2007)

> Metric Mind wrote:
> > this hybrid motor is highly salient, basically field weakening is achieved by embedding small perm
> > magnets in certain pattern and shape, leaving air gaps.
> > So it's far from synchronous motor which distinctively cogs
> ...


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## EVDL List (Jul 27, 2007)

> Bill Dube wrote:
> > With an inverter, you control the frequency. Thus, there is no need
> > for the induction operation.
> 
> ...


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## EVDL List (Jul 27, 2007)

I wonder if this is an implementation of a motor one of the universities
did a while back.
The magnets were buiried in the rotor in such a way as to not be
effected by the high freq slip but able to run syncronous when the load
dropped.

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## EVDL List (Jul 27, 2007)

Check Brusa pages (http://www.brusa.biz/g_datasheets.htm) and look at =

the data sheets for the asynchronous motor (ASM6.17.12_20070414.pdf) =

and the Hybrid-Synchron-Motor (HSM6.17.12_20070414.pdf). You can see =

that the stators look identical but the rotors are different. The =

Hybrid-Synchron-Motor rotor seems to have eight red-and-blue coloured =

rectangles embedded, I would guess that they are permanent magnets.

Seppo


>----Alkuper=E4inen viesti----
>L=E4hett=E4j=E4: [email protected]
>P=E4iv=E4m=E4=E4r=E4: 08.12.2007 21:43
>Vastaanottaja: "Electric Vehicle Discussion List"<[email protected]>
>Aihe: Re: [EVDL] Synchronous-induction hybrid motor?
>


> >Metric Mind wrote:
> >> this hybrid motor is highly salient, basically field weakening is =
> 
> achieved by embedding small perm
> ...


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## EVDL List (Jul 27, 2007)

Yes that is exactly what the rotor looked like! I wonder if since that
was originally done at a university if it is available for others to
implement.

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## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> ...
> > The patent gives the impression that they have movable iron shunts on
> > the rotor. In one position, they "short" the magnets, so it behaves as
> ...


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