AC SPINDLE MOTOR AND METHOD OF CHANGING THE REVOLVING SPEED THEREOF

Title:

AC SPINDLE MOTOR AND METHOD OF CHANGING THE REVOLVING SPEED THEREOF

Document Type and Number:

WIPO Patent Application WO/1990/006617

Kind Code:

A1

Abstract:

An AC spindle motor (10) used for driving the spindle of a machine tool has a rotor (14) with an output shaft (12) that can be coupled to the spindle, and a stator (16) arranged to surround the rotor (14), the stator (16) having a laminated core (20) that forms a yoke and three-phase (U, V, W) stator windings accommodated in the winding grooves (22) of the laminated core (20) to form a revolving magnetic field. The windings (18u, 18v, 18w) of three-phase stator windings for forming the revolving magnetic field have: a first set of windings (C2, C4) served with a drive current in either a low-speed region where the revolving speed is smaller than a predetermined value and a high-speed region where the revolving speed is larger than the predetermined value; a second set of windings (C1, C3 served with a drive current in the low-speed region only; and electric contact means (S1 to S4 which so switch the circuit that the drive current is supplied to the first and second sets of windings (C2, C4, C1, C3) simultaneously during the low-speed operation to form a first plural-pole revolving magnetic field and that the drive current is supplied to the first set of windings (C2, C4) only during the high-speed operation to form a second plural-pole revolving magnetic field, the number of the second plural poles being smaller than the number of the first plural poles. The ampers turns of the windings and the number of poles are changed depending upon the low-speed operation and the high-speed operation.

Inventors:

NAKAMURA KOSEI (JP)
HAYASHI YOSHIYUKI (JP)
NUMAI KAZUHISA (JP)
KIMIJIMA MASAMI (JP)

Application Number:

PCT/JP1989/001204

Publication Date:

June 14, 1990

Filing Date:

November 29, 1989

Export Citation:

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Assignee:

FANUC LTD (JP)

International Classes:

H02K17/12; H02K17/14; (IPC1-7): H02K17/14

Foreign References:

JP2000001260Y

Other References: