JP2014207866A - Three-phase ac motor having improved winding structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a three-phase AC motor in which unbalance of characteristics among individual windings constituting a stator winding can be eliminated, even if the axis of a rotor is deviated from the axis of a stator.SOLUTION: Unit windings of all teeth corresponding to respective phases are not connected in series, but at least a set of unit windings (e.g., U1 and U3) at positions point symmetrical with respect to the axis of rotation of a motor, out of the unit windings, are connected in series as partial windings (e.g., U1-U3), a plurality of the partial windings are connected in star or delta as one winding group (e.g., U1-U3:V1-V3:W1-W3), and the stator winding of the motor is constituted of a plurality of winding groups independent electrically.

Description

  The present invention relates to a winding structure of a three-phase AC motor.

  As a winding structure of a three-phase AC motor, a structure in which all unit windings of each phase arranged on the circumference of a stator (stator) are connected in series according to the number of poles is often used. As a specific example, a motor connected as shown in FIG. 2 is often used for the winding arrangement of each unit winding U1,..., U4, V1,..., V4, W1,. ing.

  In addition, winding is often performed in a state where a plurality of copper wires are bundled. For example, the unit winding U1 is formed as a winding in which two windings U1a and U1b are bundled, and each is configured as a new unit winding. In such a winding structure, unit windings U1a,..., U4a are connected in series, unit windings U1b,..., U4b are connected in series, as shown in FIG. Are connected in parallel to form a U-phase winding.

  In the case of the winding structure of FIG. 3, when attention is paid to each of the partial windings formed by connecting unit windings in series, for example, a partial winding constituted by U1a-U2a-U3a-U4a and U1b-U2b In the partial winding composed of -U3b-U4b, the electromotive voltage, resistance, inductance, etc. are almost the same.

  In the above description, the case where all the unit windings of each phase arranged on the circumference according to the number of poles are connected in series has been described, but depending on the three-phase AC motor, in order to obtain desired characteristics, In some cases, unit windings are not connected in series, but are connected in parallel or series-parallel, or a plurality of electrically independent winding groups (see Patent Document 1 below).

  As specific examples, in the case of the winding arrangement as shown in FIG. 1, the unit windings of each phase are connected in series and parallel and connected as shown in FIG. 4, or the unit windings U1,. U4, V1, ..., V4, W1, ..., W4 are partially connected in series to form a plurality of partial windings U1-U2, U3-U4, V1-V2, V3-V4, W1-W2, W3-W4. In some cases, these partial windings are connected as shown in FIG. 5 to form two electrically independent winding groups. In these connections, generally, adjacent unit windings are generally connected in series to form partial windings so that the connecting wire connecting the unit windings is the shortest.

JP 2006-271018 A

  Regarding the unit windings of each phase arranged on the circumference, if the unit windings equally divided are shifted by 2π in electrical angle, the constants of each unit winding (back electromotive force constant, resistance, inductance, etc.) Are the same in principle. However, in reality, there is a deviation between the axis of the rotor (rotor) and the axis of the stator (stator), so in each unit winding arranged in the circumferential direction, the rotor and stator As a result, the back electromotive force and the inductance are different for each unit winding, and the unit winding does not have the same characteristics.

  Therefore, when the connection as shown in FIG. 4 is made, the partial windings (in the case of the U phase, U1-U2 and U3-U4) have different characteristics due to the shift of the axial center. In this case, since the back electromotive force is different, a circulating current is generated, for example, in the route of U1 → U2 → U4 → U3 when the motor rotates, and the characteristics of the motor are deteriorated due to useless heat generation.

  Even if the same voltage is applied, if the characteristics of the unit windings are different, the current flowing through the partial windings U1-U2 and the current flowing through the partial windings U3-U4 are different. An imbalance occurs, resulting in an imbalance in the motor temperature distribution. Since the motor characteristics are defined by the maximum temperature of the winding, the imbalance of the motor temperature distribution results in a reduction in the motor characteristics. In addition, this circulating current also causes a problem that the generated torque of the motor is lowered due to the dynamic braking effect.

  Further, when each of the winding groups of the three-phase AC motor having a plurality of electrically independent winding groups shown in FIG. 5 is driven by a plurality of motor driving devices as shown in FIG. 10, respectively, It is common to drive with the same parameters under the assumption that the constants of the windings are the same. For this reason, even if the same voltage is applied to winding groups having different characteristics due to axial misalignment, the flowing current value is different, which causes an imbalance in the motor temperature distribution. Moreover, depending on the case, it is necessary to change the parameter to drive for every winding group, and the management becomes complicated.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to constitute a stator winding even when the axis of the rotor and the axis of the stator are misaligned. An object of the present invention is to provide a three-phase AC motor capable of eliminating the unbalance of characteristics between individual windings.

  In order to achieve the above object, according to the present invention, in a three-phase AC motor in which a plurality of unit windings are arranged at equal intervals in the circumferential direction of the stator, all the unit windings corresponding to each phase are connected in series. Without connecting to the unit winding, a unit winding of at least one set of unit windings in a point-symmetrical position about the rotation axis of the motor is a partial winding, and a plurality of the partial windings A three-phase AC motor is provided, which is connected to form a stator winding of the motor.

  In one preferable aspect, the stator winding of the electric motor is configured by star-connecting windings obtained by connecting a plurality of the partial windings corresponding to each phase in parallel.

  In one preferred embodiment, a stator winding of the electric motor is configured by delta connecting windings obtained by connecting a plurality of the partial windings corresponding to each phase in parallel.

  In one preferred embodiment, a winding in which the partial windings are star-connected or delta-connected is made into one winding group, and a stator winding of the electric motor is constituted by a plurality of electrically independent winding groups. The

  In the three-phase AC motor according to the present invention, unit windings that are point-symmetrical with respect to the rotating shaft of the motor are connected in series, and are used to constitute the windings of the motor as partial windings. According to such a partial winding, even when the axis of the rotor and the axis of the stator are misaligned, the difference in winding characteristics due to the misalignment of the axis is offset, and the characteristics are unbalanced between the partial windings. Does not occur.

It is a figure which shows the example (example in which all unit windings are arrange | positioned at a different phase when it sees with a mechanical angle) of the conventional arrangement structure of the stator winding | coil in a three-phase alternating current motor. It is a figure which shows the 1st example of the conventional connection structure of a stator winding | coil. It is a figure which shows the 2nd example of the conventional connection structure of a stator winding | coil. It is a figure which shows the 3rd example of the conventional connection structure of a stator winding | coil. It is a figure which shows the 4th example of the conventional connection structure of a stator winding | coil. It is a figure which shows the connection structure of the stator coil | winding in the three-phase alternating current motor which concerns on 1st embodiment of this invention. It is a figure which shows the connection structure of the stator winding | coil in the three-phase alternating current motor which concerns on 2nd embodiment of this invention. It is a figure which shows the arrangement structure of the stator winding | coil in the three-phase alternating current motor which concerns on 3rd embodiment of this invention. It is a figure which shows the connection structure of the stator coil | winding in the three-phase alternating current motor which concerns on 3rd embodiment of this invention. It is a figure which shows the connection structure in the case of driving the several coil group in a three-phase alternating current motor with the several motor drive apparatus corresponding to each.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 6 is a diagram showing a connection structure of stator windings in the three-phase AC motor according to the first embodiment of the present invention. 6 is applied to a three-phase AC motor in which unit windings U1,..., U4, V1,..., V4, W1,. It is an example.

  As shown in FIG. 1, the unit winding U1 and the unit winding U3 are unit windings that are in point-symmetric positions with respect to the rotation axis. Therefore, as shown in FIG. 6, U1 and U3 are connected in series to become partial windings U1-U3. Similarly, U2 and U4 are connected in series to form another partial winding U2-U4.

  The partial winding U1-U3 and the partial winding U2-U4 are connected in parallel to form the entire U-phase winding. In each of the partial windings, the two unit windings at the point-symmetrical positions are connected in series, so that the difference in characteristics due to the shift of the axis is offset. As a result, since the partial windings have the same characteristics, the connection structure in FIG. 6 has a structure in which no circulating current is generated in the path U1 → U3 → U4 → U2. The same applies to the V phase and the W phase.

  FIG. 7 is a diagram showing a connection structure of stator windings in the three-phase AC motor according to the second embodiment of the present invention. The connection state shown in FIG. 7 is an example applied to a three-phase AC motor having a plurality of electrically independent winding groups. Even in this case, since the partial winding is configured by connecting two unit windings at point symmetry positions in series, each partial winding of each winding group has the same characteristics even if the axis is shifted. Will have.

  8 and 9 are diagrams showing an arrangement structure and a connection structure, respectively, of the stator winding in the three-phase AC motor according to the third embodiment of the present invention. When viewed from the mechanical angle, even when multiple unit windings are wound in the same phase, the unit windings connected in point symmetry are connected in series as partial windings, and they are connected in parallel. They can be connected or they can be independent windings. As an example, for the three-phase AC motor of FIG. 8 in which three unit windings U1a, U1b, and U1c are wound at the same mechanical angle instead of U1 in FIG. Can be connected in series and in parallel as shown in FIG.

  In FIG. 9, the unit windings U1a, U2a, and U3a and the unit windings U3b, U4b, and U1b that are in point symmetry with respect to these unit windings are connected in series. ing. Similarly, the unit windings U2b, U3c, and U4a and the unit windings U4c, U1c, and U2c that are in point symmetry with respect to these unit windings are connected in series to another partial winding. Has been. These two partial windings are connected in parallel to form a U-phase winding. The V-phase and the W-phase are also connected in the same manner to constitute the entire winding.

  As described above, in-phase unit windings in a point-symmetrical position about the rotation axis are connected in series as partial windings, or each partial winding connected in parallel is star-connected, Or, by connecting each partial winding in an independent winding group, the characteristics of each winding and the winding (back electromotive force, inductance) Etc.) will not occur.

  As mentioned above, although embodiment of this invention has been described, of course, this invention is not limited to this, It is possible to employ | adopt various embodiment. For example, although the above-mentioned embodiment is shown as an example in the case of star connection, the present invention is applicable to the case of delta connection.

Claims (1)

In a three-phase AC motor in which a plurality of unit windings are arranged at equal intervals in the circumferential direction of the stator,
Without connecting the unit windings of all the teeth corresponding to each phase in series, at least one set of unit windings at a point-symmetrical position about the rotation axis of the motor is connected in series among the unit windings. A winding formed by star connection or delta connection of a plurality of the partial windings as one winding group, and a stator winding of the electric motor by a plurality of electrically independent winding groups. A three-phase AC motor characterized by comprising.

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