Three-phase squirrel-cage AC induction motors are the workhorses for the industrial market. However, their development is reaching the limits of physics for efficiency.
A new technology must be adopted to reach the next levels, and this could be permanent magnet motors using some type of rare-earth magnets in the rotor, switched reluctance, synchronous reluctance, or some new technology yet to be identified. Most of these new technologies offer power density improvements over standard induction motors. But most require some form of adjustable speed drive for their operation, which can further aid in energy savings.
At this time, these new technologies are available from motor manufacturers, but have yet to become available through distribution as standard drop-in replacements for existing NEMA or IEC motor designs. Both NEMA and IEC have yet to complete standards for these new technologies, and only CSA has developed an approved test method.