ELECTRIC MACHINE

Abstract

In a rotating electric machine including a field pole unit having ten magnetic poles (P=10) and an armature having twelve teeth (Q=12), armature coils are wound around the successive teeth with phase relationships and winding polarities arranged in the order of U+/U+, U−/V+, V−/V−, W−/V+, W+/W+, W−/U+, U−/U−, U+/V−, V+/V+, W+/V−, W−/W− and W+/U−, where “U,” “V” and “W” represent three phases of the individual armature coils while “+” and “−” denote winding polarities. Among all harmonic components of magnetomotive forces produced by the armature coils, harmonic components of orders lower than a synchronized component can be reduced in this rotating electric machine. This structure decreases eddy currents flowing in the field pole unit, resulting lower eddy current loss in the field pole unit of the rotating electric machine.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional diagram showing the structure of an electric machine according to a first embodiment of the invention;

FIG. 2 is a sectional diagram showing the structure of a conventional rotating electric machine used as a comparative example;

FIG. 3 is a graph showing a distribution of magnetomotive forces produced by an armature of the conventional rotating electric machine of FIG. 2;

FIG. 4 is a graph showing components of individual orders of the magnetomotive forces produced by the armature of the conventional rotating electric machine of FIG. 2;

FIG. 5 is a graph showing a distribution of magnetomotive forces produced by an armature of the electric machine of the first embodiment;

FIG. 6 is a graph showing components of individual orders of the magnetomotive forces produced by the armature of the electric machine of the first embodiment;

FIG. 7 is a vector diagram showing how vectors representing 1st-order spatial harmonic components produced by the armature of the conventional rotating electric machine of FIG. 2 are combined;

FIG. 8 is a vector diagram showing how vectors representing 1st-order spatial harmonic components produced by the armature of the electric machine of the first embodiment are combined;

FIG. 9 is a sectional diagram showing the structure of an electric machine according to a second embodiment of the invention;

FIG. 10 is a graph showing components of individual orders of magnetomotive forces produced by an armature of the electric machine of the second embodiment;

FIG. 11 is a sectional diagram showing the structure of an electric machine according to a third embodiment of the invention;

FIG. 12 is a graph showing components of individual orders of magnetomotive forces produced by an armature of the electric machine of the third embodiment;

FIG. 13 is a sectional diagram showing the structure of an electric machine according to a fourth embodiment of the invention;

FIG. 14 is a graph showing components of individual orders of magnetomotive forces produced by an armature of the electric machine of the fourth embodiment;

FIG. 15 is an enlarged fragmentary sectional diagram showing the structure of an electric machine according to a sixth embodiment of the invention;

FIG. 16 is an enlarged fragmentary sectional diagram showing the structure of an electric machine according to a seventh embodiment of the invention;

FIG. 17 is a sectional diagram showing the structure of an electric machine according to an eighth embodiment of the invention; and

FIG. 18 is a fragmentary sectional diagram showing the structure of an electric machine according to a ninth embodiment of the invention.

Claims

1. An electric machine comprising: an armature; anda field pole unit movable relative to said armature along a magnetic gap between armature and said field pole unit, said armature including:an armature core having a plurality of teeth extending toward the magnetic gap at uniform interval along a moving direction of said armature relative to said field pole unit, anda plurality of armature coils concentratedly wound around respective teeth for the flow of phase currents from a three-phase AC power supply, wherein said field pole unit has a fixed number of magnetic poles arranged along the moving direction, andsaid plurality of teeth include at least one tooth around which at least two armature coils for the flow of different phase currents are wound to reduce harmonic components of magnetomotive forces produced by the armature coils when said electric machine is operated, the reduced harmonic components being of a lower order than a component synchronized with relative moving speed of said armature and said field pole unit.

2. The electric machine according to claim 1, in which said armature rotates relative to said field pole unit, wherein the number of poles “P” of said field pole unit and the number of teeth “Q” of said armature are selected from one of the combinations consisting of P=5n and Q=6n, and P=7n and Q=6n, respectively, where “n” is an even number, andsaid armature coils are wound around successive teeth with phase relationships and winding polarities arranged in the repeating order of U+/U+, U−/V+, V−/V−, W−/v+, W+/W+, W−/U+, U−/U−, U+/V−, V+/+, W+/V−, W−/W− and W+/U−, where “U”, “V” and “W” represent phases of individual armature coils and “+” and “−” denote winding polarities of said armature coils.

3. The electric machine according to claim 1, in which said armature moves linearly relative to said field pole unit, wherein the number of poles “P” of said field pole unit and the number of teeth “Q” of said armature are within a range in which said field pole unit and said armature of said electric machine face each other and magnetic flux can be interlinked and are selected from one of the combinations of P=5m and Q=6m, and P=7m and Q=6m, respectively, where “m” is a natural number, andsaid armature coils are wound around successive teeth with phase relationships and winding polarities arranged in the repeating order of U+/U+, U−/+, V−/V−, W−/V+, W+/W+, W−/U+, U−/U−, U+/V−, V+/V+, W+/V−, W−/W− and W+/U−, where “U,” “V” and “W” represent phases of individual armature coils and “+” and “−” denote winding polarities of said armature oils.

4. The electric machine according to claim 2, wherein, expressing the number of turns of each of two armature coils of a common phase wound around a single tooth by T, the number of turns of two armature coils of different phases wound around another single tooth is 2T.

5. The electric machine according to claim 3, wherein, expressing the number of turns of each of two armature coils of a common phase wound around a single tooth by T, the number of turns of two armature coils of different phases wound around another single tooth is 2T.

6. The electric machine according to claim 4, wherein wires of two armature coils of a common phase wound around a single tooth have a cross-sectional area larger than wires of two armature coils of different phases wound around another single tooth.

7. The electric machine according to claim 5, wherein wires of two armature coils of a common phase wound around a single tooth have a cross-sectional area larger than wires of two armature coils of different phases wound around another single tooth.

8. The electric machine according to claim 2, wherein any two armature coils of a common phase wound around a single tooth are combined into a single winding.

9. The electric machine according to claim 3, wherein any two armature coils of a common phase wound around a single tooth are combined into a single winding.