But you can also get AC motors with permanent magnets. The Oxford YASA motors, for example.AC motors inevitably involve losses in the electrical provision of their static field. Permanent magnets have no such downside. Therefore efficiencies can be higher - up to 93% Check out the Lynch motor - Agnimotors.com
The question is too open-ended. People always ask these types of questions, and invariably get a million (obvious exaggeration) different answers.Whitch is better if im building a track car.. ac or dc motor?