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Browse Prior Art Database

Grooved Rotor for Hysteresis Motor

IP.com Disclosure Number: IPCOM000076676D
Original Publication Date: 1972-Apr-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 22K

Publishing Venue

IBM

Related People

Ratajski, JM: AUTHOR

Abstract

Longitudinal grooves 10, 11 are provided in the outside surface of the hollow cylindrical rotor 12 which is utilized in a hysteresis motor. The grooves improve the motor's operating torque characteristic.

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Grooved Rotor for Hysteresis Motor

Longitudinal grooves 10, 11 are provided in the outside surface of the hollow cylindrical rotor 12 which is utilized in a hysteresis motor. The grooves improve the motor's operating torque characteristic.

The grooves induced in rotor 12 reduce the eddy currents. The longer grooves 10 are related to the third-harmonic eddy currents, which are generally predominant and can reach 28% of the fundamental frequency square wave applied to the armature windings, not shown, of the motor. Third-harmonic grooves 10 are symmetrically located on the circumference of the rotor 12. The exact number N of grooves required for any particular harmonic is determined by the following: (1) N = H x P, where P = number of fundamental poles, and H = number of the particular harmonic. For example, in a ten-pole machine, that is five-pole pairs, there would be thirty third-harmonic grooves 10 provided. The grooves 10 are symmetrically spaced, fifteen on each end 13, 14 of rotor 12. These grooves act as a thirty-pole rotor and coact synchronously with the third harmonic rotating field, thereby contributing to the overall operating torque of the rotor.

The rotor can be provided with additional grooves for higher harmonics. For example, a fifth harmonic can be utilized by providing fifty shorter grooves for the ten pole example. If in the given example, both the third and fifth harmonics are to be utilized, the rotor 12 can be configured as having the aforem...