Importance

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Abstract

A method and apparatus for controlling an induction motor having at least high speed windings and reduced speed windings divides the reduced speed windings into first and second portions. The first and second portions of the reduced speed windings are electrically connected in series and a voltage is applied to the first and second portions of the reduced speed windings when it is desired to operate the induction motor at a reduced speed. The first and second portions of the reduced speed windings are electrically disconnected and a voltage is applied to the high speed windings when it is desired to operate the induction motor at a high speed. The induction motor has three sets of windings extending from a middle region, each set of windings having an inner winding toward the middle region and an outer winding away from the middle region. According to one aspect, a first changeover circuit is electrically connected to each set of windings, between the inner and outer windings for applying a voltage to the outer windings when it is desired to operate the induction motor at a high speed. A second changeover circuit is electrically connected to each set of windings, toward the middle region from the inner windings for applying a voltage to the inner and outer windings when it is desired to operate the induction motor at a reduced speed. It is thus possible to change from a Y configured winding connection to a .DELTA. configured winding connection.

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