JP3422643B2 - Synchronous motor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchronous motor usable in a wide speed range.

[0002]

2. Description of the Related Art An example of a conventional synchronous motor will be described with reference to FIGS. 7 and 8 show a conventional 6-pole synchronous motor, and specifically, show an electric motor called a reluctance motor which is a kind of synchronous motor. As is well known, the reluctance motor is a motor that generates torque by magnetic induction. FIG. 7 is a sectional view of the synchronous motor as viewed from the side. In FIG. 7, 6 is a rotor,
7 is a stator and 8 is a shaft. FIG. 8 is a sectional view of the synchronous motor of FIG. 7 viewed from the axial direction. In FIG. 8, 1 is a magnetic path of the rotor, and 2 is a slit for separating the magnetic paths 1. FIG. 11 shows a rotor of another conventional 6-pole synchronous motor, and shows a motor called a permanent magnet type synchronous motor which is a kind of the synchronous motor. Figure 11
FIG. 4 is a cross-sectional view of a rotor of a synchronous motor as seen from an axial direction.
The stator of the synchronous motor having the rotor shown in FIG.
It is the same as that of the reluctance motor shown in. A sectional view of the permanent magnet type synchronous motor as viewed from the side is similar to FIG. 7. In FIG. 11, 6
Is a rotor, 3 is a permanent magnet, and PN and PS indicate the north pole and the south pole in the directions of the magnetic poles. 9 and 10 show the connection state of the stator windings of this synchronous motor. R, S in FIG. 9 and FIG.
T indicates the phase of the power supply, U, V, W indicate one terminal of the stator winding corresponding to those phases R, S, T, and X, Y, Z respectively. The other terminal is connected to each other.

First, of the conventional synchronous motors, a reluctance motor will be described. The rotor 6 is formed by stacking thin disks made of electromagnetic steel plates in multiple layers in the axial direction. The disks are electrically insulated. A state in which this disk is viewed from the axial direction is as shown in the rotor 6 in FIG. 8, and a large number of rotor magnetic paths 1 and slits 2 are alternately arranged. The rotor magnetic path 1 has a pattern that magnetically shorts two adjacent magnetic poles. Slit 2 is
It serves to magnetically insulate the magnetic paths 1 adjacent to each other. A three-phase AC winding is wound around the stator 7 as a stator winding. When an exciting current is passed through the stator winding in accordance with the rotational position of the rotor, torque proportional to the exciting current is generated in the rotor. Next, of the conventional synchronous motors, a permanent magnet type synchronous motor will be described. The rotor 6 has the permanent magnet 3 attached to the outer circumference of the rotor shaft. The permanent magnet 3 attached to the outer periphery of the rotor 6 has an N pole and an S pole.
It is magnetized so that the poles appear alternately in the direction of rotation. Similar to the reluctance motor, a three-phase AC winding is wound around the stator 7 as a stator winding. When an exciting current is passed through the stator winding in accordance with the rotational position of the rotor, torque proportional to the exciting current is generated in the rotor. 9 and 10 show a star connection and a delta connection, respectively. The star connection and the delta connection are selectively realized by switching the terminals of the windings wound in each phase. In FIG. 9, the terminals X, Y and Z are short-circuited. Figure 10
, Terminals U and Z, terminals V and X, and terminals W and Y are short-circuited. In the synchronous motors shown in FIGS. 7 and 8, when the number of rotations of the rotor is increased while keeping the field constant, a counter electromotive force proportional to the number of rotations is generated in the winding. Therefore, regarding the synchronous motor of FIG. 7, the maximum torque and the maximum rotation speed thereof are limited by the voltage and current supply capabilities of the drive unit that supplies electric power to the synchronous motor.

In the low speed rotation range, the synchronous motor is controlled by the star connection shown in FIG. 9, and in the high speed rotation is controlled by the delta connection shown in FIG. 10, that is, the connection state is switched according to the rotation speed, so that the base rotation is performed. For example, the number of 1.
It is possible to use up to about 7 times the speed range. Another method for changing the speed range is control by weakening the field. This is for performing constant power control in the induction motor, and it is a common sense of the current motor control that the field weakening control can be realized even in the control of the reluctance motor. With this control, the reluctance motor can also be controlled to a speed range of about four times the base rotation speed. Furthermore, the synchronous motor can be used in a wider speed range by combining a plurality of the above methods.

[0005]

However, the star connection-
If you try to control the speed in a particularly wide range, such as 10 times the base speed, by combining the delta connection switching and constant power control, the field magnet becomes a very small value in the high-speed rotation range, making it difficult to control the motor. There is a problem that becomes.
Also, in the method that suppresses the field by switching to shorter windings in the high-speed rotation region, when trying to obtain an equivalent field magnetic flux before and after switching the winding length, before and after switching the windings,
It is necessary to increase the field component by an amount that is inversely proportional to the square of the difference in the winding length, and the exciting current value required immediately after switching the winding exceeds the maximum output current value of the drive unit. . Since the reluctance motor itself does not have a mechanism for braking at the time of power failure, a braking mechanism needs to be separately provided in the reluctance motor when it is necessary. The present invention has been made in view of the above conventional problems, and an object thereof is to provide a synchronous motor (especially a reluctance motor) that can stably operate in a wide speed range. Another object of the present invention is to generate a sufficient field, particularly in a high-speed rotation region, without imposing an excessive load on the drive unit. Another object of the present invention is to provide a synchronous motor capable of performing constant power control by weakening the field. Another object of the present invention is to brake the reluctance motor at the time of power failure.

[0006]

In order to achieve the above object, the present invention provides a synchronous motor including a rotor provided with a rotary shaft and a stator provided around the rotor. Includes a first rotor magnetic pole portion having a magnetic direction in which a magnetic path for guiding a magnetic flux is formed, and a second rotor magnetic pole portion composed of a magnetized permanent magnet. And According to the above configuration, the second rotor magnetic pole portion is provided in addition to the first rotor magnetic pole portion, and the second rotor magnetic pole portion is composed of the magnetized permanent magnet. A field is generated (auxiliary field or main field) spontaneously by the second rotor magnetic pole part, for example, even when field weakening control is performed, a necessary and sufficient field is formed and stable high speed is achieved. Can rotate. That is, the torque performance can be improved especially in the high speed rotation region. In a preferred aspect of the present invention, the first rotor magnetic pole portion and the second rotor magnetic pole portion are provided side by side in the rotation axis direction, or the first rotor magnetic pole portion and the second rotor magnetic pole portion are provided. Rotor magnetic pole portions are provided side by side in the circumferential direction of the rotor.
When the second rotor magnetic pole portion is provided side by side with the first rotor magnetic pole portion in the rotation axis direction, the second rotor magnetic pole portion is provided on the load side or the non-load side of the first rotor magnetic pole portion. Or provided in the middle of the first rotor magnetic pole part divided into two. When the second rotor magnetic pole portion is provided side by side with the first rotor magnetic pole portion in the rotation axis direction, the second rotor magnetic pole portion extends along the axis having a width of one magnetic pole or less. Permanent magnet magnetic poles are provided between the first rotor magnetic pole portions. The second rotor magnetic pole portion is composed of one or a plurality of S / N pole pairs. In a preferred aspect of the present invention, the winding group of each phase included in the stator is composed of a plurality of windings having different lengths, and the length of the winding can be selected. By selecting the winding length, the operating conditions are switched and the operable speed range is expanded. Windings of different lengths can be constructed by providing an intermediate tap on one winding or, in fact, by providing multiple windings. In a preferred aspect of the present invention, the first rotor magnetic pole part is made of a magnetic material that guides a magnetic flux along a magnetic path extending between the magnetic poles and has a large magnetic resistance in a direction intersecting the magnetic path. For example, the second rotor magnetic pole portion is composed of a magnetized permanent magnet. The first rotor magnetic pole part and the second rotor magnetic pole part may be magnetically connected in series on the rotor. Then, the field direction is set so that the field of the first rotor magnetic pole part and the field of the second rotor magnetic pole part are opposite to each other, and by the field of the second rotor magnetic pole part, as a whole. The magnitude of the field may be controlled. In a preferred aspect of the present invention, in a synchronous motor including a rotor provided with a rotary shaft and a stator provided around the rotor, the rotor has a plurality of rotations arranged along a circumferential direction. A plurality of rotor magnetic poles, and the plurality of rotor magnetic poles guide the magnetic flux along a magnetic path extending between the magnetic poles.
And the two magnetic poles that are adjacent to each other along the circumferential direction
In one rotor magnetic pole part, two magnetic poles adjacent to each other in the circumferential direction are magnetically short-circuited and extend in a strip shape in the axial direction.
A plurality of rotor magnetic paths, and a first rotor magnetic pole portion in which slits magnetically insulating between the strip-shaped rotor magnetic paths are alternately laminated and arranged, and the first rotor magnetic pole. Division and circumference
And a second rotor magnetic pole portion which is arranged side by side and is composed of a magnetized permanent magnet.

[0007]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described with reference to FIG. In FIG. 1, 6 is a magnetic steel plate rotor,
9 is a permanent magnet rotor. The electromagnetic steel plate rotor 6 and the permanent magnet rotor 9 together constitute a rotor.
In FIG. 1, 7 is a stator and 8 is a rotating shaft.
The electromagnetic steel plate rotor 6 of FIG. 1 corresponds to the first rotor magnetic pole portion. The structure is basically the same as the conventional synchronous motor called reluctance motor. The axial cross section is also the same as the rotor of the conventional synchronous motor shown in FIG. As its name implies, the electromagnetic steel plate rotor 6 is made of an electromagnetic steel plate having a magnetic directivity that guides a magnetic flux along a magnetic path extending between magnetic poles and has a large magnetic resistance in a direction intersecting the magnetic path. The permanent magnet rotor 9 corresponds to the second rotor magnetic pole portion, and its axial cross section is no different from that of the rotor of the conventional permanent magnet type synchronous motor shown in FIG. The operation of the second rotor magnetic pole portion will be described later.

In the reluctance motor, the exciting current is responsible for the field. Therefore, the reluctance motor has a problem that the drive load of the drive unit is larger than that of the permanent magnet field motor. In particular, this problem becomes a problem immediately after switching the stator windings short. Therefore,
In the embodiment shown in FIG. 1, the permanent magnet rotor 9 is provided on the load side on the same rotary shaft 8 as the electromagnetic steel plate rotor 6. The permanent magnet rotor 9 faces the stator 7 similarly to the electromagnetic steel plate rotor 6, and acts magnetically on the stator 7.
A permanent magnet is arranged at the outer edge of the permanent magnet rotor 9 and is magnetized so that a predetermined portion of the outer edge becomes a magnetic pole. According to the above configuration, at the time of high speed rotation, the field magnetic flux is mainly borne by the permanent magnet rotor 9, and the torque can be controlled by the field generated by the exciting current. Therefore, the current burden on the drive unit is reduced, and the conventional problems can be avoided even if high-speed rotation is realized by shortening the stator winding. The axial length of the permanent magnet rotor 9 or the axial length ratio of the permanent magnet rotor 9 and the electromagnetic steel plate rotor 6 can be appropriately set. The permanent magnet rotor 9 includes one or a plurality of pairs of Ss arranged along the circumference of the rotor while corresponding to each magnetic pole.
・ It consists of N poles. According to this embodiment, since the permanent magnet is provided, there is also an advantage that a braking action can be obtained at the time of power failure.

By the way, in FIG. 1, the permanent magnet rotor 9 is located on the load side of the electromagnetic steel plate rotor 6, but the permanent magnet rotor 9 is located on the non-load side of the electromagnetic steel plate rotor 6. It does not matter even if it is between the electromagnetic steel plate rotor and the two. Although the electromagnetic steel plate rotor 6 and the permanent magnet rotor 9 are drawn in contact with each other in FIG. 1, the electromagnetic steel plate rotor 6 and the permanent magnet rotor 9 may be separated from each other in the rotation axis direction. . Further, in FIG. 11 which illustrates the permanent magnet rotor 9, the permanent magnets are arranged on the outer circumference of the rotor. However, by providing the magnetic path 1 and guiding the magnetic poles to the outer circumference, the permanent magnets are arranged inside the rotor. It doesn't matter.

Next, FIG. 2 shows another embodiment. Figure 2
FIG. 4 is a view of a rotor portion of the 6-pole synchronous motor according to the present embodiment, as viewed from the rotation axis direction. Here, the portion that serves as the stator of this synchronous motor is omitted in the figure because it is the same as the stator of a conventional 6-pole synchronous motor. In FIG. 2, 1 is a rotor magnetic path, and 2 is a slit provided for magnetically insulating the magnetic path 1. Reference numeral 3 is a permanent magnet, 4 and 5 are portions that become the outer circumference of the rotor of the permanent magnet 3, 4 is an N pole portion, and 5 is an S pole portion. The magnetic poles of the rotor are between the portions indicated by arrows in FIG. 2, PN constitutes the N pole portion of the rotor, and PS constitutes the S pole portion of the rotor.

Thus, by providing a permanent magnet on a part of the outer periphery of the rotor of the synchronous motor in a shape different from that of the rotor shown in FIG. 1, a part or a considerable part of the field magnetic flux is permanent magnet. Can be borne by. In FIG. 2, the permanent magnet 3 has a width of about one magnetic pole in the rotation direction, and one permanent magnet 3 is symmetrical with the other permanent magnet 3 (opposite side) so that geometrical balance is maintained. Two permanent magnets having the same shape are arranged on the outer circumference of the rotor so that The relationship between the N pole portion and the S pole portion is also symmetrical. The magnetic poles of the electromagnetic steel plate portion are formed by a large number of magnetic paths 1 continuous in a strip shape, as in the rotor of the conventional synchronous motor shown in FIG. In FIG. 2, the permanent magnet 3 is located at a position similar to that of a series of magnetic paths 1 guiding a magnetic flux from one magnetic pole to the adjacent magnetic pole in the rotor as shown in FIG. It is provided. The permanent magnet 3 spans between the magnetic poles at its center, and the PN portion 4 is magnetized to the N pole and the PS portion 5 is magnetized to the S pole in the permanent magnet.

Next, FIG. 3 shows another embodiment. In the rotor of FIG. 3, magnetic poles are formed between the arrows, PN is the N pole portion of the rotor, and PS is the S pole portion of the rotor. Here, PM behind the hyphen represents a permanent magnet magnetic pole, and MM represents an electromagnetic steel sheet magnetic pole. Figure 3
In, the two permanent magnets 3 each serve as one magnetic pole, and the width in the rotation direction is equal to the width of the magnetic poles PN and PS. The positions of the permanent magnets 3 are symmetrically arranged such that one is located on the opposite side of the other, as in the embodiment of FIG. In FIG. 3, an N pole is formed on one side of the outer circumference of the rotor of the permanent magnet 3, and
An S pole is formed on the other side of the outer circumference of the rotor. The electromagnetic steel plate portion includes a plurality of strip-shaped magnetic paths 1,
One end of the magnetic paths 1 extends in the N pole range PN, and the other end of the magnetic paths 1 extends in the S pole range PS.

The rotor shown in FIG. 3 can also be used as a two-pole synchronous motor by combining it with a two-pole stator. At this time, the state of the magnetic poles of the rotor is shown in FIG.
The left half of the rotor in FIG. 6 has an N pole and the right half has an S pole, and a permanent magnet is arranged in the center of each magnetic pole, and both edges of the pole are strip-shaped magnetic paths. Can be considered to be. Here, by setting the width of the permanent magnet magnetic pole in FIG. 6 to a value smaller than the width of the magnetic pole, the field load of the permanent magnet can be set.

Next, FIG. 4 shows another embodiment. It is also possible to control the field by utilizing the magnetic resistance of the electromagnetic steel plate, that is, it is possible to control the magnitude of the field and partially cancel out the desired amount of the permanent magnet field. is there.
If the inverse magnetic field is performed when the magnetic field flux generated by the permanent magnets is somewhat large, it is possible to control the electric motor in a wide speed range by constant power control. In the embodiment shown in FIG. 4, the number of permanent magnet magnetic poles is increased from two to four as compared with the embodiment shown in FIG. 3, and instead, the magnetic pole of the electromagnetic steel plate is reduced from four poles to two poles. Has been done. One end of each magnetic path 1 extends to one magnetic pole, and the other end of each magnetic path 1 faces a permanent magnet (N pole or S pole) arranged on the other magnetic pole. That is, when viewed along the magnetic force line path from one magnetic pole to the other magnetic pole, the magnetic poles of the electromagnetic steel sheet and the magnetic poles of the permanent magnets are magnetically connected in series. Even in the case where the field magnetic flux generated by the permanent magnet is large as described above, control in a wide speed range is possible as in the embodiment of FIGS. 2 and 3. Although the permanent magnet magnetic field and the electromagnetic steel plate magnetic field are set in the opposite directions in the above embodiment, they may be set in the forward direction.

Incidentally, in the embodiments shown in FIGS. 2, 3 and 4, the synchronous motor having 6 poles is shown, but the present invention can be applied to the synchronous motor having the number of poles exceeding 6 poles. is there. That is, in order to make the magnetic field flux generated by the permanent magnet 3 appropriate, the number of poles for performing the permanent magnet field may be increased. Similarly, with respect to the embodiment shown in FIG. 6, the present invention can be applied to a synchronous motor having more than two poles. In the embodiment shown in FIGS. 2, 3, 4, and 6, the permanent magnet 3 is arranged on the outer edge of the rotor, but even when the permanent magnet is embedded inside the rotor 6, the magnetic flux is generated by the magnetic path 1. It is also possible to lead to the outer circumference of the rotor, and even if the permanent magnet does not appear on the outer circumference of the rotor, it is included in this patent.

The operation of the synchronous motor shown in each of the above embodiments will be described with reference to FIG. FIG. 5 is a wiring diagram of the stator windings in the synchronous motor of each embodiment. In FIG. 5, R, S, T indicate the phases of the power source, U1, V1, W1 indicate one terminal of the stator winding corresponding to each phase of R, S, T, and X, Y, Z These are the other terminals of the stator windings of terminals U1, V1 and W1, respectively. U2, V2 and W2 are terminals U1, V1 and W1 and terminals X of the stator winding of each phase,
It is a terminal between Y and Z.

The reluctance motor can be controlled in a wide speed range by switching the stator winding to one having a shorter winding length as the rotation speed of the reluctance motor increases. However, when the stator winding is shortened, the field load of the drive unit increases and the current increases. Therefore, the winding could not be shortened so much. Therefore, in each of the above embodiments,
A rotor including a permanent magnet for a field is used. This reduces the field load on the drive unit, and therefore allows the drive unit current supply capacity to be relaxed.Conversely, the stator winding length can be shortened compared to conventional reluctance motors. Become. By the way, in the conventional synchronous motor, when the method of switching between star connection and delta connection as shown in FIGS. 9 and 10 is adopted, the ratio of the winding lengths of the star connection and the delta connection is, for example, about 1: Although it is 1.7, the ratio cannot be changed in the past, and even when used in combination with field weakening control, the speed range in which the controllable speed band overlaps is wide, so that a great effect can be obtained. There wasn't. Therefore, if a stator winding having a structure capable of switching a plurality of types of winding lengths as shown in FIG. 5 is combined with the motor of each of the above-described embodiments, a stator winding shorter than the conventional one can be used, As a result, a wide speed band can be obtained.
In FIG. 5, the terminals X, Y and Z are short-circuited to be the neutral point of the motor. Terminals U when the power supplies R, S, T rotate at low speed
1, V1, W1 is selected, and terminals U2, V are used during high-speed rotation.
By selecting 2 and W2, wideband speed control becomes possible.

In FIG. 5, the stator winding is one for each phase, and a power supply terminal for high speed rotation is provided at an intermediate point of each winding, but the stator winding has two different lengths. It may be two windings. Further, the number of terminals provided in the middle of the stator winding or the number of windings per phase may be larger. Further, in the above example, U2, V2, and W2 are connected to the power source side at the time of high-speed rotation, but the same result can be obtained by short-circuiting the terminals U2, V2, and W2.

In the above embodiment, the synchronous motor using a rotor made of a magnetic steel plate having many slits has been described, but the present invention is also applicable to reluctance motors having other structures. Are also included in the scope of the present invention.

Further, the present invention can be applied to a linear motor, and the present invention can also be applied to an electric motor in which a plurality of rotors are combined.

[0021]

According to the present invention, since a permanent magnet for a field is provided in a part of the rotor, a reliable operation can be achieved especially in a high speed rotation region, and it is stable over a wide speed range. Speed control can be realized. Further, since the load on the drive unit is reduced, it is possible to use a stator winding shorter than the conventional one. Further, by combining the switching of the stator winding length, speed control of a particularly wide band is facilitated. Further, at the time of power failure, short-circuit braking can be performed by short-circuiting the stator winding.

[Brief description of drawings]

FIG. 1 is a side view of a synchronous motor according to the present invention.

FIG. 2 is a sectional view of a synchronous motor according to the present invention.

FIG. 3 is a sectional view of a synchronous motor according to the present invention.

FIG. 4 is a sectional view of a synchronous motor according to the present invention.

FIG. 5 is a connection diagram of a winding wire according to the present invention.

FIG. 6 is a sectional view of a synchronous motor according to the present invention.

FIG. 7 is a side sectional view of a conventional synchronous motor.

FIG. 8 is an axial sectional view of a conventional synchronous motor.

FIG. 9 is a wiring diagram of a conventional synchronous motor.

FIG. 10 is a wiring diagram of a conventional synchronous motor.

FIG. 11 is an axial sectional view of a conventional synchronous motor.

[Explanation of symbols]

1 rotor magnetic path, 2 rotor slit, 3 rotor permanent magnet, 4 outer circumference has N pole part, 5 outer circumference has S pole,
6 electromagnetic steel plate rotor, 7 stator, 8 axis, 9 permanent magnet rotor, PN rotor N pole, PS rotor S pole, PN-
PM permanent magnet magnetic pole N pole, PS-PM permanent magnet magnetic pole S
Pole, PN-MM electromagnetic steel sheet magnetic pole N pole, PS-MM electromagnetic steel sheet magnetic pole S pole.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-59310 (JP, A) JP-A-7-39091 (JP, A) JP-A-54-79408 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H02K 1/27 H02K 3/28 H02K 19/10 H02K 21/14

Claims (2)

(57) [Claims] 1. A synchronous motor including a rotor having a rotary shaft and a stator provided around the rotor, wherein the rotor has a plurality of rotor magnetic poles arranged along a circumferential direction. The plurality of rotor magnetic poles have a circumferential direction by guiding a magnetic flux along a magnetic path extending between the magnetic poles.
First rotor magnetic pole that constitutes two magnetic poles that are adjacent to each other
A magnetic field between two magnetic poles adjacent to each other in the circumferential direction and magnetically short-circuited between a plurality of rotor magnetic paths extending in a strip shape along the axial direction, and between the respective rotor magnetic paths. A first rotor magnetic pole portion in which slits and insulating layers are alternately laminated and arranged, and the first rotor magnetic pole portion is arranged side by side in the circumferential direction,
A synchronous motor comprising: a second rotor magnetic pole portion formed of a magnetized permanent magnet; 2. The synchronous motor according to claim 1, wherein each phase winding group included in the stator is composed of a plurality of windings having different lengths, and the length of the windings can be selected. And synchronous motor.