# Separately Exited Motor question



## Xringer (Oct 12, 2008)

Motor, D&D ES-80A 12-48 VDC 4+ HP http://www.electricvehiclesusa.com/product_p/mo-es-80a.htm

I like the idea of a Separately Exited Motor using an electromagnetic coil,
instead of a PM..

My question is about the free-wheeling load. Is the free-wheeling load
of this motor heavy or light ? Light like an AC induction motor? 

If the controller is off, would this motor spin easily or load up like a PM motor??


Thanks,


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## frodus (Apr 12, 2008)

well, its got a similar free wheeling load as a PM motor, although not as small as an AC induction motor. Its still got brushes and Copper on the armature.

Another thing to consider, you need a special controller for sepex, and they typically don't go as high of a voltage as series wound motors. Controllers are typically more complex, but DO offer regen.

Whats it going in?


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## Xringer (Oct 12, 2008)

frodus said:


> well, its got a similar free wheeling load as a PM motor, although not as small as an AC induction motor. Its still got brushes and Copper on the armature.
> 
> Another thing to consider, you need a special controller for sepex, and they typically don't go as high of a voltage as series wound motors. Controllers are typically more complex, but DO offer regen.
> 
> Whats it going in?


Dang, I was hoping it wouldn't load up like a PM. Since, the electromagnetic effect is gone once the power is off.. (Unlike the field from a PM).

My project is to convert my Honda CRV into a weak hybrid. 
http://www.diyelectriccar.com/forums/showthread.php?p=80450#post80450

Since battery pack doesn't need to be real powerful, but has to be lightweight, I'm not too worried about the voltage limitations of the
controller. 
I posted to the controller forum, to maybe find out what voltage I should be shooting for with this app.
http://www.diyelectriccar.com/forum...ately-exicited-controller-question-22799.html


I've been thinking about the Netgain EMIS system and wondering how a DIYer could implement a similar system. 
Something that be semi-transparent to the driver.. And just feel like an ICE that got good MPG for short trips around town.. 

Maybe, program that could check the MPH and tell if the car was on the highway or buzzing around town. Maybe a Scangauge10.0 

If it was in town, it would check via the OBDII, if calculated the MPG was under 25, it would turn on the assist motor. 
Anytime it saw over 30 MPG (in town) AND SOC was needful, it would regen.. 

If it was on the highway(above 48 MPH), and found the MPG was under 31, it would turn on the assist. 

ICE alone getting 40 MPG on the highway? Time to do some regen IF SOC is down, otherwise, just keep on coasting..


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## frodus (Apr 12, 2008)

Xringer said:


> Dang, I was hoping it wouldn't load up like a PM. Since, the electromagnetic effect is gone once the power is off.. (Unlike the field from a PM).


By freewheeling I mean no load. Its going to have similar inertial load. Pretty sure the Electrical load of a PM is more than a series.


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## Xringer (Oct 12, 2008)

frodus said:


> By freewheeling I mean no load. Its going to have similar inertial load. Pretty sure the Electrical load of a PM is more than a series.


My experience with large DC motors is *very* limited.

I know about the mechanical loading due to bearings, weight and brushes etc.

But, I've been told there is a considerable internal_ electrical _type loading in PM motors,
due to the magnets causing power generation, even if there is no electrical load.

That's main reason I'm not looking at PM motor for my app.
I was hoping that the loading effect wouldn't be so bad 
in a sepex motor.. Since it has no magnets.

Since this motor needs to be directly connected to the transfer case, (always turning). 
I would not want it to be cutting heavily into my MPG when to ICE only mode..


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## frodus (Apr 12, 2008)

Xringer said:


> My experience with large DC motors is *very* limited.
> 
> I know about the mechanical loading due to bearings, weight and brushes etc.
> 
> ...


series motors are ideal for that, they don't load heavily (hence no regen) on the vehicle. Another thing to consider with sepex, is even if it does load, you'll be getting all that back into the pack, so its not "lost".


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## Xringer (Oct 12, 2008)

frodus said:


> series motors are ideal for that, they don't load heavily (hence no regen) on the vehicle. Another thing to consider with sepex, is even if it does load, you'll be getting all that back into the pack, so its not "lost".



Getting some back juice was my hope..
If the controller can be programmed to precisely control the amount of power generated,
using the input coil, that would be sweet. 
Being able to change the voltage/amps coming out of the motor during regen
with consideration of the SOC would be fantastic..

Maybe I should go rent a Prius for a few months and study it.. 

--edit--
Maybe I'm worried about over-charge cut-off for nothing.. 
If the pack starts getting too full for comfort.. I can start putting the petal to the metal a little..


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## frodus (Apr 12, 2008)

Xringer said:


> Getting some back juice was my hope..
> If the controller can be programmed to precisely control the amount of power generated,
> using the input coil, that would be sweet.
> Being able to change the voltage/amps coming out of the motor during regen
> ...


those are AC motors....

AC, Perm and Sepex do regen, series do not. Sepex controllers usually stop about 84V, perm about 72V and AC goes up to 500+V.

stop looking at motors first, you need to figure out drag and calculate what power you need to push the car to xx mph at xx ft/s^2, then find HP and torque needed, and find a motor with those specs.

Would you blindly buy a power supply for your cell phone if you don't know what voltage and amperage you need? Same idea.


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## Xringer (Oct 12, 2008)

frodus said:


> those are AC motors....
> 
> AC, Perm and Sepex do regen, series do not. Sepex controllers usually stop about 84V, perm about 72V and AC goes up to 500+V.
> 
> ...


Not knowing a lot about 'weak Hybrids', my starting point is, I don't need to find out what kind of power is needed to propel the car at xx mph. 
I just want to help the ICE propel the car.

The way I've been thinking, for a simple ICE assist motor/pack, it can be almost any HP that can do more a bit more than propel it's own weight to 65 MPH. 

As of now, this viewpoint is leading me to look at EV motorcycle hardware and EV-go-karts and golf-cart motors & packs. Those have the power range that could be useful to me. 

I've dumped about 120-150 pounds off my CRV, pulling out the rear drive.
I don't want to add so much weight that I have to install a stronger suspension. The less weight I have to add, means I'm not hammering
my MPG too badly if the Hybrid drive system is turned off for some reason.

I have no need for EV mode only. My ICE is in great shape, it only has 33k on it.


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## major (Apr 4, 2008)

Xringer said:


> I like the idea of a Separately Exited Motor using an electromagnetic coil,
> instead of a PM..
> 
> My question is about the free-wheeling load. Is the free-wheeling load
> ...


Hi Xringer,

The SepEx motor, or any wound field motor, will have no magnetic drag when unexcited. You will always have friction and windage from the rotating member. Having a commutator and brushes will have more friction than an induction motor, which has no sliding contact parts. The commutator PM motor will have some reluctance torque when driven with the armature open due to the armature slots cutting the magnetic field. It will also have iron losses due to the magnetic field reversals in the core.

Regards,

major


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## Xringer (Oct 12, 2008)

major said:


> Hi Xringer,
> 
> The SepEx motor, or any wound field motor, will have no magnetic drag when unexcited. You will always have friction and windage from the rotating member. Having a commutator and brushes will have more friction than an induction motor, which has no sliding contact parts. The commutator PM motor will have some reluctance torque when driven with the armature open due to the armature slots cutting the magnetic field. It will also have iron losses due to the magnetic field reversals in the core.
> 
> ...


*"Reluctance torque*" That's the term I've been wanting to hear..
Nothing but mechanical drag from the SepEx motor is the good news! Thanks for the info.


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## frodus (Apr 12, 2008)

Xringer said:


> I have no need for EV mode only. My ICE is in great shape, it only has 33k on it.


Missed your comment about weak hybrid...


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## Xringer (Oct 12, 2008)

frodus said:


> Missed your comment about weak hybrid...


I guess it's not too common. Google DIY Hybrid and you get a ton of
Hydrogen generator hits. 

Since I don't drive a lot (more miles on my bicycle over the last two summers),
this is kind of a hobby project for me.

But, if a weak-hybrid conversion could be done cheaply by a DIYer,
I'll bet there are a lot of gen1 CRV owners around here that might
be interested in better MPG and being _green_. (Honda sold a bunch of CRVs in New England).


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