# Bombardier Shunt/SepEx motor question



## mtcookson (Aug 31, 2011)

Hello everyone, I'm actually posting this for my dad as he doesn't do forums that much. He bought a Bombardier NEV in parts and has been trying to make it work for a while now. Most of the parts were there but someone butchered some of the wires so he had to trace everything and, long story short, accidentally sent 72v to a 12v wire killing the 12v board and almost killing the gauge cluster.

Sooo, the controller is out and he doesn't want to put much money into this to get it running meaning he doesn't want to buy a controller. I'm trying to talk him into a Kelly SepEx controller as, from what I find, it might not work out so well without a controller but I'm trying to find if his idea will work or what the worst case scenario would be.

Originally we thought it was a straight shunt motor but after further research I found that its actually a sepex as the armature and field are separately wired. The Bombardier manual says its a shunt sepex motor and says its actually a shunt motor because it is sepex, which doesn't make sense nor does that even seem correct to me but anyway he's trying to find out if there's any possible way to drive it without a controller.

Currently he has 7 solenoids, 4 to switch between forward and reverse and the other 3 to control voltage to the armature in steps. One thing we're stuck on is how many volts is supplied to the field. From what I can find the field gets the same voltage as the armature in a shunt motor but other sources are saying the field gets less voltage in a sepex motor. One source I found was this very forum, posted here: http://www.diyelectriccar.com/forums/showthread.php/evdl-sepex-vs-shunt-17596.html

Would it be safe to start by just applying 24 volts to the field and from there, would he be able to vary the voltage of the armature with those solenoids by switching from 24, to 48, then up to 72 volts for speed control?

I have a bad feeling about doing it this way since, from what I can find, the field and armature current is controlled using PWM with the controllers and supplying a direct connection in my mind would end up bad but I have basically no knowledge of EV's and electric motors period so am not sure what the true outcome would be. Any insights into whether this will work or if it will just end in fire and brimstone?


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## DavidDymaxion (Dec 1, 2008)

I have run my sepex EV around with just a contactor switch straight to a 48V pack, so it is possible. It is actually surprisingly usable in that mode, and does regen. Note I have an 11 inch Kostov so your smaller motor likely isn't up to as much voltage. Here are some thoughts for you:


Can you get specs for this particular motor?
I have a clutch -- how are you going to start without a huge jerk and current spike? You might need to switch in a starting resistor.
On 48V my fields get hot in about 10 minutes.
A rule of thumb I read was a shunt motor is designed to run its field at full voltage, but a sepex is designed to typically run it at about 1/3 of max voltage. This allows the sepex to do brief, temporary over voltages on the field for regen or a higher torque start. I'd humbly suggest you start with 12V on the field, and keep checking the motor to see if it starts to get hot. Remember for each doubling in Voltage the fields will get hot in 1/4 the time. The rule of thumb would be 24V (1/3 of 72V) and brief surges above that, but I would start more conservatively with a lower voltage.
Higher field and lower armature voltage is more conservative
I bought a handheld tachometer from Harbor Freight, it has been a great way to check rpm during testing.
The reason I bought a Kelly Sepex controller is because charts showing contactor life showed contactors don't last very long switching at high voltages. It's less power than I want but I'll "limp along" for a couple years this way.



mtcookson said:


> Hello everyone, I'm actually posting this for my dad as he doesn't do forums that much. He bought a Bombardier NEV in parts and has been trying to make it work for a while now. Most of the parts were there but someone butchered some of the wires so he had to trace everything and, long story short, accidentally sent 72v to a 12v wire killing the 12v board and almost killing the gauge cluster.
> 
> Sooo, the controller is out and he doesn't want to put much money into this to get it running meaning he doesn't want to buy a controller. I'm trying to talk him into a Kelly SepEx controller as, from what I find, it might not work out so well without a controller but I'm trying to find if his idea will work or what the worst case scenario would be.
> 
> ...


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## mtcookson (Aug 31, 2011)

DavidDymaxion said:


> I have run my sepex EV around with just a contactor switch straight to a 48V pack, so it is possible. It is actually surprisingly usable in that mode, and does regen. Note I have an 11 inch Kostov so your smaller motor likely isn't up to as much voltage. Here are some thoughts for you:
> 
> 
> Can you get specs for this particular motor?
> ...


Thanks for the reply, definitely helpful.

As for the motor I believe the basics are this:
72v, 300A (based on the controller)
4kW, according to my dad. Based on the book I'd say its normally around 4kW or so and up to ~20kW under full acceleration, based on power numbers of 5 hp normally and up to 20 to 25 hp under full acceleration.

Normally it uses one of the Curtis PMC controllers and controls the motor with PWM. From what I can tell looking at the FSM it simply supplies a constant 72v to the armature and varies current with the PWM but it doesn't explain at all what it supplies or does to the field. I would think voltage and current would be controlled but I just have no idea on that area.

I'll definitely have to look into a starting resistor as the jerk was definitely one of my concerns. Considering the power Bombardier says it produces and its potential top speed of around 45 mph I would definitely be a little hesitant to see what kind of initial torque its capable of producing... could make for a nice, smoky burnout though. 

Do you know if stepping the voltage from the 24, 48, up to 72 would help with the torque surge and limit the speed or would it likely cause more issues rather than just giving it a constant voltage like you did with yours?

He currently has a switch hooked up, basically like a gear shifter, to control the solenoids providing those voltage steps with each click of the switch.


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## electriccarbill (Sep 16, 2013)

I started with a NEV that sounds just like yours.
I have learned quite a lot about it and mine is running now.
Give me a call and we can talk about it.
I hate typing!!!
call Bill at 850-893-7226


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