# Controlling a shunt wound motor



## jackbauer (Jan 12, 2008)

Friend of mine is looking at doing an ev conversion. He has an 9" forklift pump motor and from what I can see its shunt wound. I'm just wondering whats is the best (if indeed any) control setup for such a motor. I'm a bit afraid to give it a run on my igbt based controller as I'm thinking it may have a weird characteristic. Any advice much appreciated.


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## major (Apr 4, 2008)

jackbauer said:


> Friend of mine is looking at doing an ev conversion. He has an 9" forklift pump motor and from what I can see its shunt wound. I'm just wondering whats is the best (if indeed any) control setup for such a motor. I'm a bit afraid to give it a run on my igbt based controller as I'm thinking it may have a weird characteristic. Any advice much appreciated.


Hi jack,

I doubt that a forklift pump was using a shunt wound motor. It may well be unidirectional (meaning 2 terminals). Most pump motors were (back in my day) series wound or compound wound motors. But shunt, no. It is possible that it was some new type of variable speed pump motor and is actually a SepEx.

So, before getting into a control design, find out what the motor is 

If you can get to the field separately, you can run a test like I describe here to figure proper field excitation. 

http://www.diyelectriccar.com/forum...unning-larger-sepex-out-thereiii-34283p2.html 

Regards,

major


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## jackbauer (Jan 12, 2008)

Thanks major thats good news. It has two terminals and what led me to believe its shunt was the fact that I could see two thick wires leading to the brushes and two thin wire going to the field. Field and brush connections being in parallel. its rated at 18kw at 72v.It spins up fine on a 12v battery but obviously in one direction. The wrong one of course


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## major (Apr 4, 2008)

jackbauer said:


> Thanks major thats good news. It has two terminals and what led me to believe its shunt was the fact that I could see two thick wires leading to the brushes and two thin wire going to the field. Field and brush connections being in parallel. its rated at 18kw at 72v.It spins up fine on a 12v battery but obviously in one direction. The wrong one of course


Sounds like a compound wound motor. Might be a real chore to reverse rotation direction. But if you get that accomplished, and it is compound, you would have at least about half a series winding and make the PWM controller happier. You could then bring out the shunt (half of the compound) winding and provide it 72V separately from the armature circuit. 

major


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## jackbauer (Jan 12, 2008)

I'll have a better look at it. Thanks again.


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