This paper examines some of the electromagnetic considerations for achieving near optimum efficiency of a hypothetical 10-Hp industrial motor with a copper rotor cage. The loss budgets for the motor with an aluminum cage and that for a substituted copper cage are calculated using a Matlab program. Rotor bar shape is then varied to improve "pull-up" torque and control starting current of the copper rotor machine. The performance of this modeled motor is then compared to the performance of recently introduced commercial high efficiency copper rotor machines and some of the design considerations used by the manufacturers to achieve the performance are discussed. Advances in the die casting process that have made the copper rotor motor cost effective are reviewed.
Abslmcl-The advantages to motor performance and energy elfidency of substituting copper for alnmIoum in the squirrel cage of the iuduction motor rotor are described in this paper.Performance data on motors equipped with die-cast copper rotors dynamometer tested by several motor manufacturers according to IEEE Specleation 112B are presented. Overail motor losses were 14 to 23% lower in moton with copper rotors compared to the aluminum counterparts. The manufacturing technology for economical production of copper rotors by die casting has also been imwtigated and Is summarized Use of a nickel-base alloy bigb temperature die operated at elevated temperature is shown to greatly extend die We over that experienced with conventional die steels in die casting eopper with its high melting temperature.Because the electrical conductivity of copper is nearly 60% higher than that of aluminum, one would expect the 12R losses in the rotor to be substantially lower if copper were substituted for aluminum as the conductive material of the squirrel cage structure.Motor modeling by several manufacturers has shown that motors with copper-containing rotors would have overall loss reductions of 15 to 20%.Aluminum has been the material of choice for all but very large motors because the intricate squirrel cage is readily manufactured by pressure die casting through the rotor lamination stack. Die casting of the copper will be required for rapid and cost-effective manufacture, but the process has not been practical because of short die life resulting &om the high melting temperature of copper.There were two phases to the work described in this paper. The fM phase addressed the problem of die life in pressure die casting copper by surveying a number of candidate high
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.