# Series, Shunt, Compound. Pros/Cons Discussion



## Woodsmith (Jun 5, 2008)

In my search for a motor I have been considering series wound motors alone.
However, I am aware that there are also shunt motors and compound motors available.

I know how they are wound to make them different but I don't know how they differently respond to being used in an EV:









Perhaps we need a simple or base level discussion on the pros and cons of each type.
I know most seem to be using series wound and I know jackbauer is using a compound. I don't know what the difference will be in performance, efficiency or control.

Do they need to operate on different principles?
How about voltage and current range for power output?
What to look for when comparing one to another, winding wire size, terminations, specifications in the makers plate.


----------



## major (Apr 4, 2008)

Woodsmith said:


> In my search for a motor I have been considering series wound motors alone.
> However, I am aware that there are also shunt motors and compound motors available.


Hi Wood,

For your typical EV car conversion, you're probably best off to stick with the series wound motor. The controllers which are available are designed to work with series motor.

If you know what you're doing, you can get a compound motor to work using a series motor controller.

I'd stay away from shunt motors.

You don't mention SepEx. There are a few SepEx controllers out there and you might be able to put together a SepEx system.

Some say SepEx and shunt are the same. See http://www.diyelectriccar.com/forums/showpost.php?p=131407&postcount=19 

You can also search this site and find more discussion on the topic.

Regards,

major


----------



## Woodsmith (Jun 5, 2008)

Opps, forgot about the SepEx option.

I know there is bits of discussion and information dotted around the forum but I just thought that some collected thoughts on one thread may help those who are making decisions on DC motors.


----------



## Sunking (Aug 10, 2009)

I work with a lot of golf carts and they use both series and shunt wound motors.

Series is the easiest to work with in respect to controllers using PWM types. However they have two downsides. 1. They must always be operated under a load otherwise they can easily over speed and fly apart. 2. No Regen capability.

Shunt wound motors take a more expensive controller, but you gain regen capability.


----------



## Georgia Tech (Dec 5, 2008)

From My reading the Cons to using a Sep Ex is that you can't run that high a voltage. You need a ep Ex with inter poles. 

I would never consider running a motor like this in the Shunt configuration.


----------



## Qer (May 7, 2008)

Sunking said:


> 2. No Regen capability.


Still not true.

There are controllers out there that can do regen on series wound motors, however the motor can't be advanced (then it'll burn up) and it also seems to be tricky as *.

So it's at least theoretically possible to handle regen with a series wound but it's MUCH harder than if you use for example a SepEx which is, I dare say, the single reason why almost noone has implemented it.


----------



## samborambo (Aug 27, 2008)

Woodsmith said:


> In my search for a motor I have been considering series wound motors alone.
> However, I am aware that there are also shunt motors and compound motors available.
> 
> I know how they are wound to make them different but I don't know how they differently respond to being used in an EV:
> ...


Hey Alfred, yesterday I started a wiki page on motor theory: http://www.diyelectriccar.com/forums/showthread.php?t=36119

Haven't had time to flesh it out yet (and it appears I've left compound DC motors off the diagram). Could you contribute some info on DC motors? I was planning on doing a paragraph on each motor type and a parametric table on features/benefits.

On the shunt/sepex debate, I'll throw my hat in the ring and say that sepex is a control sheme, not a motor type. A motor may be designed to suit sepex control (eg: low voltage field winding) but it's still a shunt wound motor. Technically, the regen scheme on a series wound motor is a form of sepex also.

Sam.


----------



## major (Apr 4, 2008)

samborambo said:


> On the shunt/sepex debate, I'll throw my hat in the ring and say that sepex is a control sheme, not a motor type. A motor may be designed to suit sepex control (eg: low voltage field winding) but it's still a shunt wound motor. Technically, the regen scheme on a series wound motor is a form of sepex also.


So Sam,

What you're saying is that all wound field motors take on the characteristics of the control scheme as opposed to the fixed voltage (or current dependent) winding on which they were originally designed to operate.

The control engineer trumps the motor designer again 

Regards,

major


----------



## major (Apr 4, 2008)

samborambo said:


> Technically, the regen scheme on a series wound motor is a form of sepex also.


Sam,

Not necessarily true. I have seen series motor regen schemes where the armature and field current is kept equal making it fit the classical definition of series motor. (or generator, in this case)

major


----------



## samborambo (Aug 27, 2008)

major said:


> So Sam,
> 
> What you're saying is that all wound field motors take on the characteristics of the control scheme as opposed to the fixed voltage winding on which they were originally designed to operate.
> 
> ...


Yup, a shunt wound motor designed to function with the field and armature connected in parallel run on a simple chopper will have vastly different (and tunable) characteristics when the same motor's field is controlled seperately.

Your explanation seems more elegant though.....perhaps you could contribute to the wiki page?


----------



## Woodsmith (Jun 5, 2008)

samborambo said:


> Hey Alfred, yesterday I started a wiki page on motor theory: http://www.diyelectriccar.com/forums/showthread.php?t=36119
> 
> Haven't had time to flesh it out yet (and it appears I've left compound DC motors off the diagram). Could you contribute some info on DC motors? I was planning on doing a paragraph on each motor type and a parametric table on features/benefits.
> 
> Sam.


I saw that, Sam, looking forward to seeing it develop.

Sorry I can't really contribute anything at all of any use, what I know I read in a Build Your Own EV book and on these forums. I am still not very confident on selecting a good motor of any type so I am keeping it simple and getting a working series wound fork lift motor of some sort. I will still probably get the wrong one and then blow it up or find it doesn't do what I need.

That is one reason I started this thread, to get some basic discussion and information for those who, like me, can work spanners and and poke a few wires through a chassis but is pretty lost in a forest of motor types. They are all cylindrical spinny things!
If I had the money I would just buy 'the one that works for me' from Netgain or similar but I am stuck with whatever I can afford from the fork truck cemetary.

I'm not even going near the AC area for now even though it will probably be better in the long run. Dad is no use either. He knows all there is to know about AC motors so long as it runs on 240v 50hz 1ph or 415v 50hz 3ph.


----------



## major (Apr 4, 2008)

samborambo said:


> Your explanation seems more elegant though.....perhaps you could contribute to the wiki page?


Thanks, Sam,

I did elaborate on the subject here http://www.diyelectriccar.com/forums/showpost.php?p=131407&postcount=19 

I'm not too tuned in to this wiki stuff. But once I post something up, I guess it is fair game to go where ever, if found worthy 

And notice how I started that post 

major


----------

