JP3284712B2 - Rotor structure of synchronous machine and 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 rotor structure of a synchronous machine such as a synchronous motor or a synchronous generator having a permanent magnet as a field magnet in a rotor and a synchronous motor employing the rotor structure.

[0002]

2. Description of the Related Art Conventionally, taking a synchronous motor as an example of a synchronous machine of this type, a synchronous motor, for example,
As shown in Japanese Patent No. -60906, a permanent magnet is provided on the surface or inside of the rotor, a rotating magnetic field is generated by a coil wound around a slot on the stator side, and the rotor is rotated by this interaction. .

[0003] As shown in FIG. 3, there has been proposed a configuration in which salient poles A3 are provided in a rotor core between permanent magnets A2 provided on the outer periphery of a rotor A1. In this configuration, the magnetic flux in the q-axis direction due to the armature current is generated by the
In this case, the reluctance torque (reaction torque) is to be used effectively by making it easier to pass through the iron core 1 and making the inductance Lq of the q axis larger than the inductance Ld of the d axis.

[0004]

The output torque of the synchronous motor is obtained by synthesizing the magnet torque due to the magnetic field of the permanent magnet and the reluctance torque. The peak times did not match, which prevented the desired torque amplification. Therefore, there is room for increasing the output torque of the motor by making the peak times of both torques coincide with each other and for reducing the size of the motor at the same torque.

[0005] These points also apply to a synchronous generator having a similar configuration. An object of the present invention is to examine the positional relationship between a permanent magnet and salient poles and make the peak time of the magnet torque coincide with the peak of the reluctance torque.

[0006]

Means for Solving the Problems In order to achieve such an object, the following structure is adopted as means for solving the above-mentioned problems.

That is, the rotor structure of the synchronous machine according to the present invention comprises a plurality of permanent magnets on the outer periphery of the rotor and a salient pole having a projecting shape made of a material having high magnetic permeability between the plurality of permanent magnets. In the rotor structure of the synchronous machine provided with, the center of the salient pole is shifted from the center of the permanent magnet by an angle of 45 degrees or more and less than 90 degrees in electrical angle in the rotation direction of the rotor. It is characterized by being arranged so that

The angle between the center of the permanent magnet and the center of the salient pole is preferably 45 degrees in electrical angle.

A synchronous motor according to the present invention includes a rotor having the above-described rotor structure. It is preferable that the synchronous motor is provided with control means for obtaining the maximum torque by setting the phase of the field current to zero. A synchronous machine according to the present invention includes a stator having a stator winding, and a rotor rotatably held inside the stator.
A plurality of permanent magnets arranged concentrically around the center of rotation of the material, and a material having a high magnetic permeability between the plurality of permanent magnets.
By a structure and a site capable of generating a reluctance torque consists fee, a usable and the synchronous machine magnet torque and reluctance torque, the rotor has a portion capable of generating the reluctance torque,
The center of the portion is 45 electrical degrees from the center of the permanent magnet.
In the direction of rotation of the rotor by an angle not less than 90 degrees
It is characterized in that it is a structure arranged so as to be in a staggered position .

[0010]

[Function] As a synchronous machine using a permanent magnet, a synchronous motor,
That is, taking the synchronous motor as an example, the output torque of the synchronous motor is obtained by the sum of the magnet torque and the reluctance torque. Here, a conventional synchronous motor will be described first. FIG. 5 shows changes in the output torque TPR of the synchronous motor. Magnet torque T
m changes in proportion to cos θ as shown by the one-dot chain line in the figure, and the reluctance torque Tr changes in proportion to sin2θ as shown by the two-dot chain line in the figure. As a result, both torques T
The output torque TPR, which is the sum of m and Tr, changes as shown by the solid line in the figure.

Since the magnet torque Tm takes a peak value at 0 degree and the reluctance torque Tr takes a peak value at -45 degree, the output torque TPR which is the sum of the two torques Tm and Tr is larger than -45 degree. The peak value is obtained in a range less than 0 degree. The peak value of the output torque TPR is smaller than the sum of the peak value of the magnet torque Tm and the peak value of the reluctance torque Tr because the peak times of the two torques Tm and Tr are different.

According to a first aspect of the present invention, there is provided a synchronous motor including a rotor having a rotor structure according to the present invention, wherein the center of each of the permanent magnet and the salient pole has an electrical angle of 45 degrees or more and less than 90 degrees. Since it is arranged at a shifted position, the change curve of the reluctance torque Tr is changed from the position shown in FIG.
Can Las not in the right direction at a range of positions to which the peak value is the current phase theta = 0 degrees. As a result, the peak of the reluctance torque Tr is moved to the peak of the magnet torque Tm, and the maximum value of the output torque T, which is the sum of the two torques Tm and Tr, is increased as compared with the conventional example shown in FIG. Work on.

[0013] synchronous motor having a rotor of the rotor structure of the present invention according to claim 2, central and salient pole of the permanent magnet
Is located at a position deviated by 45 degrees in electrical angle from the center of
As shown in FIG. 7, a peak value is determined at a current phase θ = 0 degrees.

The magnet torque Tm changes in proportion to cos θ as shown by a one-dot chain line in FIG. 7, and the reluctance torque Tr changes in proportion to cos 2θ as shown by a two-dot chain line in FIG. As a result, the peak times of both torques Tm and Tr coincide. Therefore, when the peak times of both torques Tm and Tr coincide, that is, when θ is 0 degree, the maximum output torque T obtained by adding the peak value of magnet torque Tm and the peak value of reluctance torque Tr is obtained. . Therefore, the synchronous motor described in claim 3 works to increase the output torque. In the case of a synchronous generator, the power generation efficiency is increased with the same torque.

The synchronous motor according to the present invention functions to obtain the maximum torque by maintaining the phase at 0 regardless of the magnitude of the field current by the control means. In the synchronous machine according to the fifth aspect of the present invention, the center of the portion where reluctance torque can be generated and the center of the permanent magnet
Is shifted by 45 degrees or more and less than 90 degrees in electrical angle
The reluctance torque peak
Shift to the peak torque side of the magnet torque,
It works to increase the maximum value of the output torque, which is the sum of the torques, as compared with the conventional example .

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to further clarify the structure and operation of the present invention described above, preferred embodiments of the present invention will be described below.

1. FIG. 1 is a plan view showing the structure of a three-phase synchronous motor 10 incorporating a rotor 20 as one embodiment of the present invention, and FIG.
It is sectional drawing.

First, referring to FIG.
Will be described. This three-phase synchronous motor 10
Comprises a stator 30, a rotor 20, and a case 40 for accommodating them. The rotor 20 includes a rotating shaft 22 provided at the center of the shaft and bearings 41 and 42 provided on the case 40.
To be rotatably supported.

The rotor 20 is formed by laminating a plurality of rotors 24 formed by stamping non-oriented electrical steel sheets.
As shown in FIG. 1, the rotor 20 is provided with permanent magnets 26 and 27 at two locations on the outer periphery thereof facing each other. These permanent magnets 26 and 27 are magnetized in the thickness direction.

Further, the rotor 24 has two salient poles 5.
1, 52 are formed. The position of the salient pole 51 is shifted by 45 degrees in the rotation direction of the rotor 20 (clockwise in FIG. 1) with respect to the position where the permanent magnet 26 is disposed. Here, the shifted angle of 45 degrees is
Since the number of permanent magnets is a pair, the same 45 in electrical angle
Degree. The position of the salient pole 52 on the other side is similarly shifted from the position where the permanent magnet 27 is arranged by 45 degrees in the rotation direction of the rotor 20.

The rotors 24 are stacked in the axial direction of the rotating shaft 22 using a jig, and then the rotating shaft 22 is press-fitted and the stacked rotors 24 are temporarily fixed. An insulating layer and an adhesive layer are formed on the surface of the rotor 24 made of the magnetic steel sheet. After lamination, the rotor 20 is formed by heating to a predetermined temperature to melt and fix the adhesive layer. You.

On the other hand, the stator 32 constituting the stator 30
Is formed by punching a thin sheet of non-oriented electrical steel sheet, similarly to the rotor 24, and includes a total of six teeth 34 as shown in FIG. A coil 36 for generating a rotating magnetic field in the stator 30 is wound between the teeth 34 (see FIG. 2).

The stator 30 is fixed by heating and melting the adhesive layer in a state where the plate-shaped stators 32 are stacked and pressed against each other. In this state, the coil 36 is wound around the teeth 34 to complete the stator 30, which is then assembled to the case 40. Further, the three-phase synchronous motor 10 is completed by rotatably assembling the rotor 20 with the bearings 41 and 42 of the case 40.

In the three-phase synchronous motor 10 having such a configuration, when a field current is applied to the coil 36 of the stator 30 so as to generate a rotating magnetic field, the rotating magnetic field causes magnetic induction to the salient poles 51 and 52 of the stator 30. , Which are rotated by the rotating magnetic field. As a result, the rotor 20 rotates clockwise.

2. Next, the positions of the salient poles 51 and 52 will be described in detail.
In this embodiment, the positions of the salient poles 51 and 52 are
The positions are shifted by 45 electrical degrees in the rotation direction of the rotor 20 with respect to the positions where the positions 6 and 27 are arranged. The reason why this position is determined will be described in detail below. .

The output torque T of a synchronous motor of a synchronous machine using a permanent magnet is obtained by the following equation (1) as a general equation. T = Tm + Tr (1) Here, Tm is a magnet torque due to the magnetic field Φm of the permanent magnet, and Tr is a reluctance torque. Tm,
Tr is obtained by the following equations (2) and (3).

Tm = P · Φm · Iq (2) Tr = P (Ld−Lq) · Id · Iq (3) where P is the number of pole pairs of the permanent magnet, Lq is q-axis inductance, and Ld is d The shaft inductances Iq and Id are the respective axis components of the armature current (field current). Here,
The direction of the d-axis is determined so that the d-axis component of the armature current takes a negative value.

From the equations (1) to (3), the output torque T of the synchronous motor is obtained by the following equation (4).

(Equation 1)

Here, the synchronous motor described in the prior art will be described. In a conventional synchronous motor, a permanent magnet and a salient pole are arranged at positions shifted by 90 degrees in electrical angle.
Therefore, as shown in the armature current vector diagram in FIG. 4, the respective axis components Iq and Id of the armature current are calculated from the armature current I and its direction θ (<0) by the following equations (5) and (5). 6). Id = Isinθ (5) Iq = Icosθ (6)

From the equations (4) to (6), the output torque TPR of the conventional synchronous motor is obtained by the following equation (7).

(Equation 2)

Since sin2θ = 2sinθ · cosθ, the following equation (8) is derived.

(Equation 3)

FIG. 5 shows the change of the output torque TPR of the conventional synchronous motor obtained by the equation (8). The part of the first term related to the magnet torque Tm in the equation (8) changes in proportion to cos θ as shown by the one-dot chain line in the figure, and the second term related to the reluctance torque Tr in the equation (8) The portion changes in proportion to sin2θ as shown by a two-dot chain line in the figure.
As a result, the output torque T which is the sum of the two torques Tm and Tr is obtained.
PR changes as shown by the solid line in the figure.

In FIG. 5, the magnet torque Tm is 0
Take the peak value in degrees and the reluctance torque Tr is -4
Since the peak value is obtained at 5 degrees, both torques Tm and Tr
The output torque TPR, which is the sum of the above, has a peak value in a range greater than -45 degrees and less than 0 degrees. The peak value of the output torque TPR is smaller than the sum of the peak value of the magnet torque Tm and the peak value of the reluctance torque Tr because the peak times of the two torques Tm and Tr are different.

In turn, the three-phase synchronous motor 10 of this embodiment
Is located at a position where the permanent magnets 26 and 27 and the salient poles 51 and 52 are shifted from each other by 45 degrees in electrical angle.
The peak times of the magnet torque Tm and the reluctance torque Tr can be matched. Hereinafter, the reason will be described.

Shifting the angle between the permanent magnets and the salient poles by 45 degrees in electrical angle means that the angle is 90 degrees in the conventional synchronous motor (see FIG. 3). As shown in the schematic diagram of FIG. 6, it is inevitable to rotate the qd axis by 45 degrees in the direction opposite to the rotation direction of the rotor. This new qd axis is shown in FIG. 6 as the q'-d 'axis. Accordingly, the direction of the magnetomotive force of the armature current on the q'-d 'axis can be obtained as the value of the qd-axis coordinate by setting θ to θ-π / 4. Accordingly, the output torque T of the synchronous motor 10 of the present embodiment can be obtained by the following equation (9) by substituting θ-π / 4 for θ in equation (8) and deforming.

[0036]

(Equation 4)

In the equation (9), Ld ', Lq'
Are the q-axis inductance and the d-axis inductance of the synchronous motor 10 of the present embodiment.

FIG. 7 shows a change in the output torque T of the synchronous motor 10 according to the present embodiment obtained by the equation (9). The portion of the first term relating to the magnet torque Tm in the equation (9) changes in proportion to cos θ as shown by a dashed line in the figure,
The portion of the second term relating to the reluctance torque Tr in the equation (9) changes in proportion to cos2θ as shown by the two-dot chain line in the figure. As a result, it can be seen that the peak times of both torques Tm and Tr match.

Therefore, when the peak times of both torques Tm and Tr coincide with each other, that is, when θ is 0 degree, the output torque T shown by the solid line in FIG. 7 is the peak value of magnet torque Tm and the peak value of reluctance torque Tr. It is the value obtained by adding the value. Therefore, the synchronous motor 10 of the present embodiment amplifies the output torque T as compared with the conventional example.

3. Comparison with Conventional Example The following describes how the output torque of the synchronous motor 10 of the present embodiment is amplified as compared with the conventional example. First, with respect to the conventional synchronous motor, a current phase θ at which the output torque becomes maximum is obtained from Expression (8). This current phase θ is given by the following equation (1)
0), and the maximum torque TPR (ma
x) is determined by equation (11).

[0041]

(Equation 5)

On the other hand, regarding the synchronous motor 10 of this embodiment,
Since the current phase θ at which the output torque becomes maximum is 0 degree,
From equation (9), the maximum torque T (max) at this time is given by equation (1)
2).

[0043]

(Equation 6)

From equations (11) and (12), T (max) / TP
R (max) is obtained by the following equation (13). Here, in the synchronous motor of the present invention and the conventional synchronous motor, the magnetic field Φm and the armature current I are equal, and Ld′−
It is assumed that Lq ′ = Ld−Lq = △ L.

[0045]

(Equation 7)

Here, assuming that ΔL · I / 2Φm = Y,
T (max) / TPR (max) is obtained by the following equation (13).

(Equation 8)

T (max) / TPR obtained by equation (13)
The change in the value of (max) is shown in FIG. From this figure, Y
When (= △ LI / 2φm) takes a negative value, T (max)
It can be seen that / TPR (max) is greater than 1.0. Here, the values of I and Φm are positive values, and Y always takes a negative value because the synchronous machine exhibiting the reverse saliency has a relation of Ld <Lq. Therefore, T (max) / TPR
(Max) is always larger than the value 1.0, and it can be seen that the output torque of the synchronous motor 10 of the present embodiment is larger than that of the conventional synchronous motor. And the difference in the size is ΔL
-It changes as shown in FIG. 8 according to I / Φm.

FIG. 9 is a graph showing a change in the output torque TPR in the conventional synchronous motor according to the magnitude of the armature current I. As can be seen from this figure, the current phase value θ at which the output torque TPR becomes maximum changes as points P1, P2,..., Pn according to the magnitude of the armature current I. The points P1, P2,..., Pn are as described in (10) above.
The current phase θ obtained from the equation is shown. Therefore, in the current control of the conventional synchronous motor, the maximum output torque is obtained by optimally controlling the current phase θ to the points P1, P2,..., Pn according to the magnitude of the armature current I. Can be

FIG. 10 is a graph showing the change of the output torque T in the synchronous motor 10 according to the present embodiment according to the magnitude of the armature current I. As shown in this figure, the peak of the output torque TPR is at points Q1, Q2,..., Qn, and the current phase θ at that time is always zero. Therefore, in the current phase control of the synchronous motor 10 of this embodiment, the maximum output torque can be obtained by controlling the current phase θ to 0.

4. Configuration of Control Unit Next, a control unit that performs maximum torque control by controlling the phase of the armature current of the synchronous motor 10 to zero will be described. FIG. 11 is a schematic configuration diagram of the control unit 70 provided in the synchronous motor 10 of the present embodiment. As shown in the figure, the control unit 70 includes a torque-current conversion unit 71, an arithmetic circuit 73, and a PWM inverter 75. The torque-current converter 71 receives the torque signal T sent from the host controller, and converts the torque signal T into the respective axis components Id and Iq of the armature current. Is set to 0 degree, the d-axis component Id of the armature current is set to a value of 0, the armature current I is obtained from the torque T based on the relationship of the above-mentioned equation (9), and this value is set to Iq. , Iq.

The respective axis components Id and Iq of the armature current are sent to an arithmetic circuit 73 and receive a phase signal θ from a rotation sensor 77 provided in the synchronous motor 10 to filter currents of various stator windings. Control to an appropriate position (phase) with respect to magnetic flux.
Then, each phase voltage command Vu output from the arithmetic circuit 73
*, Vu *, Vu * are applied to the synchronous motor 10 as three-phase AC voltages Vu, Vu, Vu by the PWM inverter 75.

In the above configuration, the torque signal T sent from the host controller has a magnitude corresponding to the operation amount of the accelerator pedal in an electric vehicle, for example, and the output torque corresponding to the operation amount of the accelerator pedal. , The synchronous motor 10 rotates.

5. Effects of Embodiment As described above in detail, the synchronous motor 10 of the present embodiment can increase the output torque as compared with the conventional synchronous motor. As a result, the synchronous motor 10 of the present embodiment
If the same torque is obtained, the motor shape can be reduced in size and weight. This means that the performance (e.g., mileage, maximum speed per hour, etc.) of a device equipped with the three-phase synchronous motor 10 of the embodiment, for example, an electric vehicle can be improved. Further, the efficiency of the motor is increased, which contributes to energy saving, and heat generation can be suppressed by the improved efficiency.

The control unit 70 provided in the synchronous motor 10 of this embodiment is configured to control the armature current phase to 0 to perform the maximum torque control. It is sufficient to control only the q-axis component Iq of the daughter current, and extremely easy controllability can be obtained while having a reverse saliency that is relatively difficult to control.

In this embodiment, the position of the salient pole 51 is
Although the position is shifted by 45 degrees in the rotation direction of the rotor 20 with respect to the position where the permanent magnet 26 is arranged, an angle of 45 degrees or more and less than 90 degrees may be used instead. According to this configuration, the peak of the reluctance torque can be made closer to the peak of the magnet torque, as compared with the conventional configuration in which the angle is 90 degrees, and the output torque is increased as compared with the conventional synchronous motor. be able to.

The embodiments of the present invention have been described above.
The present invention is not limited to such embodiments. For example, the number of permanent magnets provided on the outer periphery of the rotor is set to two pairs, and the angle between the permanent magnet and the salient pole is set to two in the rotation direction of the rotor.
The present invention can be implemented in various modes, such as a configuration having an angle of 2.5 degrees, a configuration in which the number of permanent magnets is further increased, and a configuration applied to a synchronous generator, without departing from the gist of the present invention. Of course. When the motor according to the present invention is used in an electric vehicle or the like, it is more effective to make the motor rotate in a fixed direction and to use a combination of gears and the like to rotate the vehicle forward and backward using a rotation direction switching unit.

[0057]

As described above, according to the rotor structure of the synchronous machine of the present invention, a synchronous machine in which the peak times of the magnet torque and the reluctance torque coincide with each other can be easily manufactured. Further, the synchronous motor adopting the rotor structure of the present invention and the synchronous machine of the present invention can increase the output torque. Therefore, if the torque is the same, the shape can be reduced, the efficiency as a motor can be increased, and energy can be saved. In addition, it is possible to improve various performances of a device equipped with the motor.

[Brief description of the drawings]

FIG. 1 is a plan view showing the structure of a three-phase synchronous motor according to one embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a structure of a three-phase synchronous motor 10 incorporating a rotor 20 according to the embodiment.

FIG. 3 is an explanatory view schematically showing the structure of a conventional synchronous motor.

FIG. 4 is an explanatory diagram showing a vector component of an armature current.

FIG. 5 is a graph showing a change in output torque TPR of a conventional synchronous motor.

FIG. 6 is an explanatory diagram schematically showing the structure of the synchronous motor of the embodiment.

FIG. 7 is a graph showing a change in output torque T of the synchronous motor 10 according to the embodiment.

FIG. 8 is a graph showing a change in a ratio between a conventional peak value of the output torque and a peak value of the output torque of the embodiment.

FIG. 9 is a graph showing a change in output torque TPR in a conventional synchronous motor according to the magnitude of an armature current I;

FIG. 10 is a graph showing a change in an output torque T in the synchronous motor 10 according to the embodiment according to the magnitude of an armature current I;

FIG. 11 is a schematic configuration diagram of a control unit 70 provided in the synchronous motor 10 of the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Three-phase synchronous motor 20 ... Rotor 22 ... Rotating shaft 24 ... Rotor 26, 27 ... Permanent magnet 30 ... Stator 32 ... Stator 34 ... Teeth 36 ... Coil 40 ... Case 41, 42 ... Bearing 51, 52 ... Salient pole Reference numeral 70: control unit 71: current conversion unit 73: arithmetic circuit 75: PWM inverter 77: rotation sensor I: armature current Id: d-axis component Iq: q-axis component Ld: inductance Lq: inductance TPR, T: output torque Tm ... Magnet torque Tr: Reluctance torque Φm: Magnetic field θ: Current phase

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02K 1 / 17,1 / 24 H02K 1/27-1/27 503 H02K 15/03 H02K 19/00-19/38

Claims (5)

(57) [Claims] 1. A synchronous machine rotor structure comprising: a plurality of permanent magnets on an outer periphery of a rotor; and a protruding salient pole made of a material having high magnetic permeability between the plurality of permanent magnets. The center of the salient pole is 45 degrees in electrical angle from the center of the permanent magnet.
A rotor structure for a synchronous machine, wherein the rotor structure is arranged so as to be shifted from the rotation direction of the rotor by an angle of at least 90 degrees and less than 90 degrees. 2. The rotor structure of a synchronous machine according to claim 1 , wherein the angle between the center of the permanent magnet and the center of the salient pole is 45 degrees in electrical angle. 3. A synchronous motor provided with a rotor having the rotor structure according to claim 1. 4. The synchronous motor according to claim 3, further comprising control means for setting the phase of the field current to 0 to obtain a maximum torque. 5. A stator having a stator winding and a rotor rotatably held inside the stator,
The rotor has a concentric circle centered on the rotation center of the rotor.
A plurality of permanent magnets arranged in Jo, the plurality several permanent magnetic
A synchronous machine that can use magnet torque and reluctance torque by using a structure made of a material having high magnetic permeability between the stones and a part capable of generating reluctance torque, wherein the rotor has the reluctance The center where the torque can be generated is 45 degrees in electrical angle from the center of the permanent magnet.
In the direction of rotation of the rotor by an angle not less than 90 degrees
Synchronous machine that has a structure that is arranged at the position where it is located.