Electrical Machines
Emphasis in the electrical machines activity is on advanced motor technologies, performance, low-cost materials, and thermal control systems that will yield higher power densities and cost-effective solutions. Induction motors have the advantage of being the most widely manufactured and used, but they cannot currently meet the U.S. DRIVE Partnership requirements of cost, weight, volume, and efficiency. Permanent magnet motors have the highest power density; but they do not have a sufficient constant power speed range, and their cost is too high. Switched reluctance motors are potentially the lowest-cost candidate but have serious problems of high torque ripple, high noise, and low power factor.
Various motor designs are being developed to address the U.S. DRIVE targets. Recent concerns over the limited supplies and high costs of rare earth permanent magnet material have opened up research areas into new types of motors with a goal towards the elimination or reduction in the amount of these types of magnet material. Research is being conducted on polymer-bonded permanent magnets with the objectives of increasing the useful operating temperature from 150°C to 200°C and decreasing the cost.
In parallel with these efforts, high speed designs that result in increased power levels with reduced material costs are also being pursued.
Other research projects are currently underway involving designs that utilize novel means of flux injection resulting in increased torque density without the use of additional magnet material.
Future research will focus on alternate designs for permanent magnet motors, methods to reduce manufacturing costs, as well as novel motors that achieve similar performance as that of a PM motor without the rare earth magnets.