Just getting started, on the learning curve. First project, an electric go kart.
Included in this project is getting my 14yr old son interested in something other than video games, he’s supposed to learn too.
Got the cart, got a 2hp, 28v 2600rpm shunt wound dc motor (free). I wanted to start with this motor and upgrade after I solve problems. I started looking at controllers, hmm, it seems there are different controllers for shunt vs series motors. When I buy a controller I’d like to be able to reuse it on a motorcycle
or NEV.
I only want to buy one controller so is there a standard type of motor for EVs (shunt or series)?
What happens if try a series controller on a shunt motor or vise versa?
What is the general opinion of Curtis motor controllers, they seem to be readily available at lower prices than something like an Alltrax.
I like the Alltrax because of the programable ability, I’ll have a 36 v system, so I could program in a limited drive for my 26v motor. But I’m sure there is a way with the Curtis.
Thanks, Qmavam
shunt field windings aren’t made to have the same current go through them as a series. Series the armature is in series with the field. In a shunt, the armature and field are in parallel. Only a portion of the current goes through it.
The best way that people have found is to excite the field and armature separately with a sepex controller. Alltrax, Curtis and Sevcon all make a sepex controller.
Hi Frodus,
Yes to your descriptions. What I don’t know is, why not connect the shunt field
to the armature connections and then PWM the motor connections.
Thanks, Qmavam
[QUOTE=Qmavam;4614]Hi Frodus,
Yes to your descriptions. What I don’t know is, why not connect the shunt field
to the armature connections and then PWM the motor connections.
Thanks, Qmavam[/QUOTE]
well, are you talking about connecting in series? or parallel?
A Shunt motor is designed to put them in parallel, but requires a different controller, as the torque curve and excitation curve is different from a series motor. You cannot put it in series, it will melt the shunt winding.
You can try it, but there are design considerations that must be addressed, you should talk to the manufacturer of the motor and ask if it can be excited the way you propose.
Thanks Frodus,
I was talking about putting the shunt in parallel with the armature.
I’ll have to see if I can find some torque curves of series vs shunt, do you know of any?
I don’t think you would melt the shunt winding if you put it in series with the armature, the shunt already has full battery voltage across it, so I don’t think you could hurt it by putting the armature in series. The motor won’t run though.
I have written to the manufacturer, no response, I see others say Baldor doesn’t respond to questions.
I was talking about putting the shunt in parallel with the armature.
gotcha, that’s how they’re designed to work
I’ll have to see if I can find some torque curves of series vs shunt, do you know of any?
nope, people don’t use them in EV’s much, they require a different curve. You have to excite them differently.
I don’t think you would melt the shunt winding if you put it in series with the armature, the shunt already has full battery voltage across it, so I don’t think you could hurt it by putting the armature in series. The motor won’t run though.
if you put the armature in series with the field, it might take full voltage, but it won’t take the amperage that the armature is designed for. You put anything over 50A and its going to melt those windings. Its got smaller wire wrapped more turns in the field winding to get the same flux.
Hi,
I can’t figure out how you do the quote/response, quote/response thing.
Anyway,
This is the first time I’ve got a hint that series motors are the common motor for EVs.
My point was you can’t get the amperage because the resistance of the shunt is high. My shunt is about 40 ohms, if you put that in series with the armature you might have 40.1 ohms. at 36v it wouldn’t even draw a 1 amp. As I said the motor wouldn’t work!
Labels A2, F2 and F1 Only three wires.
F2 is internally connected to A1.
Thanks Qmavam
[QUOTE=Qmavam;4610]Just getting started, on the learning curve. First project, an electric go kart.
Included in this project is getting my 14yr old son interested in something other than video games, he’s supposed to learn too.
Got the cart, got a 2hp, 28v 2600rpm shunt wound dc motor (free). I wanted to start with this motor and upgrade after I solve problems. I started looking at controllers, hmm, it seems there are different controllers for shunt vs series motors. When I buy a controller I’d like to be able to reuse it on a motorcycle
or NEV.
I only want to buy one controller so is there a standard type of motor for EVs (shunt or series)?
What happens if try a series controller on a shunt motor or vise versa?
What is the general opinion of Curtis motor controllers, they seem to be readily available at lower prices than something like an Alltrax.
I like the Alltrax because of the programable ability, I’ll have a 36 v system, so I could program in a limited drive for my 26v motor. But I’m sure there is a way with the Curtis.
Thanks, Qmavam[/QUOTE]
Go with a SEPEX controller, if you really want to you CAN use a PM controller and provide the power to the field winding yourself. You would generally use a lower voltage like a dedicated battery just on the field 1/2 to 1/3 the voltage of armature winding, but using the correct controller would give you more flexability
