Actually magmotors are DC current. Trying to convert dc into ac current is a bad bad idea. There rare earth magnets which makes them super expensive.
http://www.robotbooks.com/ Look at his link for more info on magmotors designed for battlebots. 
Since no one form 230 saw this post and replied, I will!! The Van door motor was on the initial bill of parts and we assumed it would be shipped with all the stuff that was “on it’s way”. We found out at LI regionals that it was not legal so we never used the arm (touchdown pole). We then redesigned the teather to not need that motor.
Think of it like this, you have a tether that has a posible entanglement issue, so you dont deploy it. You aren’t d-q’s because the offence never happens.
The sad part is that it wasnt the judges that informed us, it was other teams. And we thank you for that. We’d never intentionally break a rule. We spent tons of time working on a stiff tether to keep away from the “potential” of entanglement (as Woodie described in the Kickoff) only to be surprised at what passed inspection at the regionals. So sorry for any confussion. Good spot, I can bearly make it out in the picture and I know what I’m looking at.
PS: We only made it to the Quarters in LI. it was New England we were in the Semi’s. (with a revised tether). Congrats to all who competed this year, it was challenging and exciting.
Steve