# Golf cart motor wired with PWM speed controller



## cricketo (Oct 4, 2018)

Folks, 

A question came up about wiring up one of these









with a generic PWM DC controller (as opposed to a controller intended for Golf carts). Is there any special magic needed there ? If hypothetically this were to be wired without a controller altogether to a battery, what would the connection sequence/diagram look like ? Thanks!


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## MattsAwesomeStuff (Aug 10, 2017)

Just to get it to spin?

Presuming it's series-wound and not SepEx

You have 4 terminals.

Jumper one F post to one A post with heavy gauge wire. Doesn't matter which, just any F to any A.

The remaining two terminals, connect to your speed controller. Doesn't matter which way, it'll spin the same direction regardless. (Disconnect one side of your jumper wire and connect it to the opposite peg on that side, the move power lead over to the one it came from, and it will spin in reverse).

Note that if it's series-wound, you won't end up with speed control really, just power control. If that motor has no load on it to slow it down, it'll accelerate into outer space with very little voltage.


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## cricketo (Oct 4, 2018)

MattsAwesomeStuff said:


> Just to get it to spin?
> 
> Presuming it's series-wound and not SepEx
> 
> ...


I guess that's part of the question. I'm not sure if that's a series-wound motor, seems like a regen motor (P/N ju2-h1890-23). The purpose is to wire up the speed controller correctly - if I understand how the battery would connect, it would be more clear how to wire up a generic speed controller as well.


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## MattsAwesomeStuff (Aug 10, 2017)

Certainly looks like a series-wound motor to me. Seems that the coils are rolled up flat bar.

Hard to tell without a spec sheet and too lazy to google more than I did.

Looks like it's rated for 26kw for 30 minutes.


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## brian_ (Feb 7, 2017)

MattsAwesomeStuff said:


> Certainly looks like a series-wound motor to me.


The field windings are not visible, so I can't see if they are very low resistance (to be wired in series with the rotor) or high resistance (to be wired in parallel with the rotor, so separately excited or "SepEx"). Are you just going on the basis of the terminals for the field winding (F1 and F2) being just as large (and so for the same current) as the terminals for the rotor winding (A1 and A2, for "armature")?

If you actually had this motor in your hands, you could measure the DC resistance of the two windings for an indication of the configuration.


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## brian_ (Feb 7, 2017)

cricketo said:


> The purpose is to wire up the speed controller correctly - if I understand how the battery would connect, it would be more clear how to wire up a generic speed controller as well.


The A1 and A2 terminals are the rotor (armature). The F1 and F2 terminals are for the field winding. As Matt said, if it is a series motor the rotor and field are connected in series, and the together they are connected to the controller. Given that, the wiring instructions for the controller will tell you everything you need; if it is a SepEx motor and controller the controller will distinguish between rotor and field outputs.


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## major (Apr 4, 2008)

Just about 100% sure it is SepEx. And best not be spinning it without the drive end bearing. Damage is likely.


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## cricketo (Oct 4, 2018)

major said:


> Just about 100% sure it is SepEx. And best not be spinning it without the drive end bearing. Damage is likely.


So assuming a SepEx motor, what would be the wiring configuration (if possible at all) ? The controller in question is something like this :

https://www.ebay.com/itm/300A-10-50...094972?hash=item28239ba5fc:g:vlYAAOSw5i5cG46Z

There was a discussion thread here about it.

It's not my project, but I will remind the person not to fire it up without the transaxle connected.


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## MattsAwesomeStuff (Aug 10, 2017)

> https://www.ebay.com/itm/300A-10-50V...YAAOSw5i5cG46Z


That's not a SepEx controller.

It has only Motor + and Motor - for outputs.

https://www.dropbox.com/s/isskh3q87vfh8sh/HL50200 v1.03 full.pdf


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## cricketo (Oct 4, 2018)

MattsAwesomeStuff said:


> That's not a SepEx controller.
> 
> It has only Motor + and Motor - for outputs.
> 
> https://www.dropbox.com/s/isskh3q87vfh8sh/HL50200 v1.03 full.pdf


Which I thought was consistent with my original question  That controller is basically for a PM brush motor, if it's not possible to wire it up to a SepEx, then it's not possible, which is also a valid answer.

Found one example that looks like this too :


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## major (Apr 4, 2008)

cricketo said:


> Which I thought was consistent with my original question  That controller is basically for a PM brush motor, if it's not possible to wire it up to a SepEx, then it's not possible, which is also a valid answer.
> ...


A series wound motor has the field current equal to the armature current. A true shunt motor has the field voltage equal to the armature voltage. What we call SepEx, separately excited, decouples field and armature. The two excitations can even come from completely different sources. The relationship between the motor's field and armature excitations (voltage and current) depends on the motor design and application specific controller program. And there is no standard as to either.

Most likely, for a golf cart, armature rated at 36/48 volts, rated field at rated one hour load will be in the 6 to 20 volt range. 

There are ways to test and determine a proper "field map" for the motor. If interested, pursue testing for a no load saturation or magnetization curve.

A SepEx motor could be run using a PM motor controller on the armature and a separate source for the field, either fixed or variable. But it is unwise to connect the field across the armature and use the PM controller. When starting the motor, or stalling the motor, the controller limits current by reducing voltage. This will reduce field strength which is responsible for torque production and successful commutation. 

Hope that helps.

major


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## cricketo (Oct 4, 2018)

major said:


> A series wound motor has the field current equal to the armature current. A true shunt motor has the field voltage equal to the armature voltage. What we call SepEx, separately excited, decouples field and armature. The two excitations can even come from completely different sources. The relationship between the motor's field and armature excitations (voltage and current) depends on the motor design and application specific controller program. And there is no standard as to either.
> 
> Most likely, for a golf cart, armature rated at 36/48 volts, rated field at rated one hour load will be in the 6 to 20 volt range.
> 
> ...


That's a perfect answer, and that totally helps! Thank you!


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