Hamilton Sundstrand Corporation

Sundstrand Corporation

Mark Wesley Bailey

Leif William Cannell

An AC squirrel cage motor runs with a rotor current frequency equal to the slip of the motor times its excitation frequency. It is desirable to reduce the rotor current on start up by means of an increased resistance, and then to run the motor with a reduced resistance once it is started. This invention takes advantage of the skin effect of high frequency currents by increasing rotor end ring resistance during startup. After the motor has started up, and has reached full speed, the rotor frequency is reduced to merely the slip multiplied by the stator frequency. The skin effect on the rotor current is less, and the motor runs with reduced resistance.

High torque reduced starting current electric motor

A rotor (10) is provided for a dynamoelectric machine. The rotor (10) includes a rotor shaft (12) and a laminated core (14). The rotor shaft (12) is adapted to mount the rotor (10) for rotation about an axis (13) of rotation in a dynamoelectric machine. The laminated core (14) includes a shaft receiving opening (42) extending along the axis (13). The opening (42) is defined by a plurality of helical lands (44) separated by a plurality of helical grooves (46), with both the lands (44) and the grooves (46) extending along the shaft (12). The lands (44) are engaged with a shaft (12) to mount the core (14) to the shaft (12) for rotation therewith about the axis (13). The grooves (46) are equally angularly spaced about the axis (13) and extend radially outward from the lands (44) and the shaft (12), whereby rotation of the shaft (12) pumps coolant through the grooves (46) to cool the rotor (10).

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Rockford, IL, United States of America

Mark Wesley Bailey