I know AC motors have some advantages over DC in some applications, and the opposite is true in other applications. Most cars use DC motors when converted, but there was one professional model, The Sunrise by Solectra that had a huge range and highway speeds that used an AC motor. Why would that be the exception and not the rule?
DC motors will cost you a lot less in terms of control circuitry and the motors themselves. The new brushless DC motors are essentially AC motors with some control circuitry built in. It would also be easier to implement regenerative braking with DC motors. DC motors and their corresponding control circuitry are easy to find due to their use in forklifts. Unless you want something like the Tesla and have the corresponding budget, go with DC, the batteries are DC anyways so you save the energy loss of the inverter.
Generally any professionally built electric vehicle uses an AC motor and home conversions most often use DC motors. DC motors are already in the type of current produced by the batteries. Therefore the controls used by a DC motor are easier to make and therefore cheaper. The RAV4ev had a DC motor. 1 AC motors have been used in the Tesla and EV1. 2 For an excellent breakdown on the pros and cons of each of 3 types of motors check out these sites. 3 Like many things in life what is better depends upon which selection criteria you give more priority to. DC motors are cheaper but can't climb hills as well and might be noisy. AC motors are more efficient but more expensive and perform very well.
You're asking a lot from people who aren't on hand. You would probably be better off looking at some of the hobby sites where they've already done conversions and such.
Alternating Current. Direct Current has a history of being dangerous.
