# converting alternator to hybrid brushless



## manic_monkey (Jun 24, 2008)

hi, i've got a spare alternator from my VW TDI, and am considering converting it to a hybrid brushless motor (powered rotor) for an E bike. i was thinking that the wound rotor could have controlable voltage, say 100%, 75%, 50% and 25% of system voltage to give some sort of rudimentry gearing. The alternator is rated at 14v and 70A, so ~1kw. my questions are;

how much over that voltage is it likely to be able to go? ive seen an Ekart on evalbum with 2 alternator motors running at 60v but i dont know how modded they are. Im very tempted to just pull the wiring and rewind with a couple of turns of 2mm insulated copper for super power handling. 

Can anyone point me in the direction of information regarding hall sensors for brushless motors? ie, how many are required, their positioning, etc. I have been looking but havent found much good information so far.


----------



## frodus (Apr 12, 2008)

> hi, i've got a spare alternator from my VW TDI, and am considering converting it to a hybrid brushless motor (powered rotor) for an E bike. i was thinking that the wound rotor could have controlable voltage, say 100%, 75%, 50% and 25% of system voltage to give some sort of rudimentry gearing. The alternator is rated at 14v and 70A, so ~1kw.


 It should handle even more than that... We have two in a go-kart and one in a mini bike.



> how much over that voltage is it likely to be able to go?


 We run at 60V no problem.


> ive seen an Ekart on evalbum with 2 alternator motors running at 60v


 Is it Tony McCormick's?



> but i dont know how modded they are.


you have to reqire it a little, but not much. After its modded it'l run like a brushless DC motor, except you excite the rotor. We have a custom controller for this, PM me. It doesn't need hall sensors. its 60V 150A.


----------



## manic_monkey (Jun 24, 2008)

frodus said:


> It should handle even more than that... We have two in a go-kart and one in a mini bike.
> 
> We run at 60V no problem.


brilliant, i think you just made my day



frodus said:


> Is it Tony McCormick's?


yup. it looks like a real blast too...



frodus said:


> you have to reqire it a little, but not much. After its modded it'l run like a brushless DC motor, except you excite the rotor. We have a custom controller for this, PM me. It doesn't need hall sensors. its 60V 150A.


thanks for the info frodus, very helpfull. you say the modified alternators are running at 60v 150A, what was the rating of the alternator before it was converted?

im also interested in how your sensing the rotor position without hall sensors. i have heard you can use the coils in the stator, as the movement of the rotor induces a current in them?


----------



## frodus (Apr 12, 2008)

> yup. it looks like a real blast too...


 if you're ever near portland, its in the shop at Synkromotive right now...



> thanks for the info frodus, very helpfull. you say the modified alternators are running at 60v 150A, what was the rating of the alternator before it was converted?


 They're small car alternators, I'll see if I can get the specs on them for you

PM me and get my email.



> im also interested in how your sensing the rotor position without hall sensors. i have heard you can use the coils in the stator, as the movement of the rotor induces a current in them?


It slowly rotates the fields A-B-C and looks at the current to sense where the field is. I think he said he used Back EMF, but I could be wrong. Its also got regen capability... which is nice.


----------



## evrob (Dec 3, 2009)

im new to all this so please be kind,so if a alternator puts out 1kw of power unconverted at 12v,converted to a motor it should put out 1kw for every 12v is feed to it ie:48v =4kw?


----------



## automd (Feb 5, 2010)

I've been living in portland & frequently pass at Synkromotive though, I really I think I've seen it once.


----------



## Salty9 (Jul 13, 2009)

Widodo at endless sphere is using a similar alternator in a go-kart at:

http://endless-sphere.com/forums/viewtopic.php?f=30&t=16328&sid=23253ec5b86c5814f6c476e2786486ea

He is varying voltage to the rotor to change torque and speed.


----------

