Induction Motors with Die-Cast Copper Rotors

The main advantage of using copper for the rotor of an induction motor is either cost reduction, or efficiency improvement. Since copper has a higher conductivity than aluminum (57 MS/m compared to 37 MS/m), it is a natural choice. However, its high melting point and the resulting high cost for die casting was for a long time a major barrier. Several technological breakthroughs in copper die-casting have been recently achieved, removing this barrier and clearing the way for industrial production.

Already, regular production at medium volume exists. About 250,000 units with die-cast copper rotors are in use. The efficiency of these motors improves on average around 3% compared to motors with aluminum rotor. This 3% improvement corresponds to a global annual electricity savings potential of 108 TWh. (Annual global electricity consumption = 15000 TWh. Of which 40% or 6000 TWh is industrial consumption. Of which 60% or 3600 TWh is used by motor systems. A savings of 3% on 3600 TWh = 108 TWh.)

A survey among manufacturers, users, researchers, engineers and members of associations, reveals that the copper rotor motor has now become an accepted technology (82%). A majority assess the technology ready for mass production (74%). Higher efficiency (42%), lower heat production (24%) and reduced cost (11%) are seen as major advantages. The main application domain is for industrial low voltage induction motors of 1 up to 100 kW, but the technology also has potential for fractional kW motors.