# Useing Sep ex motor inverted controller



## Georgia Tech (Dec 5, 2008)

Hey has anyone thought of taking a Sep Ex motor and controlling it inversley through the field coil and using the 5 speed transmision? It sort of weird inthat the less current you provide the field the faster the motor will turn. This way you don't have to have the High power IGBT's or Mosfets to control the motor. Just fire of the fleid and connect the Armature directly to the Battery pack.
what are your thoughts on this....wierd huh???, but it could work? Just different, and hey Regen would be a nothing to it...

I don't know what do yall think?


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## Georgia Tech (Dec 5, 2008)

As you decrease the field current the motor would run faster but have less torque.... Kind of how a motor works normally really..


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## major (Apr 4, 2008)

Georgia Tech said:


> Hey has anyone thought of taking a Sep Ex motor and controlling it inversley through the field coil and using the 5 speed transmision?


Yes, it has been discussed extensively at times. David is trying it. Use the search function and it should be pretty easy to find those threads.


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## DavidDymaxion (Dec 1, 2008)

Major: Jinx, we were posting at the same time.

That's an old school way to do an electric car.

I have done that with my sepex car, with rheostats on the field. It's a little crude -- if you floor it too soon you accelerate slower, and if you lift too suddenly at high rpm it'll do throw-you-through-the-windshield regen (well, that's exaggerating, but not by much, it will do skid-the-rear-wheels regen). You have to slip the clutch to get going. You have less rpm range so you shift more often. I would be reluctant to just throw the keys to someone and have them drive away, an unknowing driver could burn something up, or start skidding sideways in a turn with the intensity of the regen.

On the flip side, it's cheap, it works, and I get regen! I can draw 1000+ Amps for a $400 controller!

I have thought this could represent a business opportunity. It would be greatly improved with a microcontroller that translated pedal movements to commanded torque (more like a regular gas car). Have the microcontroller also interface wiht the automatic transmission computer. You could build such a controller much cheaper than a typical controller.


Georgia Tech said:


> Hey has anyone thought of taking a Sep Ex motor and controlling it inversley through the field coil and using the 5 speed transmision? It sort of weird inthat the less current you provide the field the faster the motor will turn. This way you don't have to have the High power IGBT's or Mosfets to control the motor. Just fire of the fleid and connect the Armature directly to the Battery pack.
> what are your thoughts on this....wierd huh???, but it could work? Just different, and hey Regen would be a nothing to it...
> 
> I don't know what do yall think?


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## jockepocke (Nov 24, 2009)

I was thinking about doing something similar before I got help from Major programming the controller properly (thanks again!). 

My plan was using a PWM controller for the field and adjust field current manually, but I believe it is harder than it seems to get off smooth and achieve the right regen... 

Would not using a high field current produce torque from hell at the start, when the armature is first connected? This way seems more like a way to control speed (which is proportional to field current), and not torque, or am I wrong again?


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## DavidDymaxion (Dec 1, 2008)

Right on both accounts. If you start with a high field current you'll get quite a jerk if you suddenly switch on the armature. You can start in neutral and slip the clutch, or use a starting resistor on the armature, or use a controller to ramp up the armature.

If you just vary the field, your speed is a function of the pedal position. That's not wrong, per se, just not what most drivers would expect, and could lead to a skid if you lifted suddenly.


jockepocke said:


> ... Would not using a high field current produce torque from hell at the start, when the armature is first connected? This way seems more like a way to control speed (which is proportional to field current), and not torque, or am I wrong again?


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