JPH07143694A - Rotor structure of synchronous machine and synchronous motor - Google Patents

Abstract

PURPOSE:To amplify the output torque of a synchronous motor by examining the positional relation between a permanent magnet and salient pole and making the peak time of magnet torque coincident with that of reluctance torque. CONSTITUTION:A three-phase synchronous motor is equipped with a stator 30 and rotor 20. The rotor 24 constituting the rotor 20 has two salient poles 51 and 52. The position of the salient pole 51 is shifted from the position of a permanent magnet 26 by 45 deg. in electrical angle in the rotating direction of the rotor 20. When the synchronous motor is constituted in such a way, the peak time of magnet torque can be made coincident with that of reluctance torque.

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 its rotor, and a synchronous motor adopting this rotor structure.

[0002]

2. Description of the Related Art Conventionally, when a synchronous motor is taken as an example of this type of synchronous machine, the synchronous motor is, for example, Japanese Patent Publication No.
As shown in JP-A-60906, a permanent magnet is provided on the surface or inside of a 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. .

Further, as shown in FIG. 3, it is proposed that salient poles A3 are provided in the rotor core portion between the permanent magnets A2 provided on the outer circumference of the rotor A1. In this configuration, the salient pole A3 causes the magnetic flux in the q-axis direction due to the armature current to flow to the rotor A.
In order to make effective use of reluctance torque (reaction torque), the q-axis inductance Lq is made larger than the d-axis inductance Ld so as to easily pass through the first iron core.

[0004]

The output torque of the synchronous motor is a combination of the magnet torque due to the magnetic field of the permanent magnet and the reluctance torque. However, the output torque of the conventional salient pole is The peak times did not match, and as a result, the desired torque amplification could not be achieved. Therefore, there is still room for increasing the output torque of the motor by matching the peak times of both torques and for downsizing the motor shape at the same torque.

Incidentally, this point is the same in the synchronous generator having the similar structure. An object of the present invention is to examine the positional relationship between a permanent magnet and a salient pole so that the peak times of the magnet torque and the reluctance torque match.

[0006]

In order to achieve such an object, the following constitution is adopted as a means for solving the above problems.

That is, the rotor structure of the synchronous machine of the present invention is provided with a plurality of permanent magnets on the outer circumference of the rotor, and between the plurality of permanent magnets, a salient pole having a protrusion shape made of a material having a high magnetic permeability. In the rotor structure of the synchronous machine, the salient poles are arranged at a position shifted in the rotational direction of the rotor by an electrical angle of 45 degrees or more and less than 90 degrees with respect to the fixed position of the permanent magnet. Characterize.

The angle between the salient poles and the rotor is preferably 45 electrical degrees.

The synchronous motor of the present invention includes the rotor having the rotor structure described above. In addition, it is preferable that the synchronous motor is configured to include a control unit that obtains the maximum torque by setting the phase of the field current to zero.

[0010]

[Operation] As a synchronous machine using a permanent magnet, a synchronous motor,
That is, taking a 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. The change in output torque TPR of the synchronous motor is shown in FIG. Magnet torque T
m changes in proportion to cos θ as indicated by the one-dot chain line in the figure, and reluctance torque Tr changes in proportion to sin 2θ as indicated 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 has a peak value at 0 degrees and the reluctance torque Tr has a peak value at -45 degrees, the output torque TPR which is the sum of both torques Tm and Tr is larger than -45 degrees. It has a peak value in the range of 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 both torques Tm and Tr are different.

On the other hand, in the synchronous motor provided with the rotor of the rotor structure of the present invention as set forth in claim 1, the permanent magnet and the salient pole are located at a position where the electrical angle is deviated by an angle of 45 degrees or more and less than 90 degrees. Since it is arranged, the reluctance torque T
The change curve of r can be traced to the right in the range from the position shown in FIG. 5 to the position where the peak value is the current phase θ = 0 degree. As a result, the peak time of the reluctance torque Tr is moved to the peak time side of the magnet torque Tm,
The maximum value of the output torque T, which is the sum of the two torques Tm and Tr, works so as to be larger than that of the conventional example shown in FIG.

In the synchronous motor provided with the rotor of the rotor structure of the present invention as defined in claim 2, since the permanent magnet and the salient pole are arranged at positions displaced by an electrical angle of 90 degrees, the reluctance torque is increased. As shown in FIG. 7, the change curve of Tr is set so as to take a peak value at the current phase θ = 0 degree.

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

In the synchronous motor of the present invention as defined in claim 4, the control means keeps the phase at 0 regardless of the magnitude of the field current, thereby working to obtain the maximum torque.

[0016]

Preferred embodiments of the present invention will be described below in order to further clarify the structure and operation of the present invention described above.

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

First, referring to FIG. 2, the three-phase synchronous motor 10
The overall structure of will be described. This three-phase synchronous motor 10
Is composed of a stator 30, a rotor 20, and a case 40 for housing them. The rotor 20 includes a rotating shaft 22 provided at the center of the shaft and bearings 41, 42 provided on the case 40.
Is rotatably supported by.

The rotor 20 is formed by laminating a plurality of rotors 24 formed by punching out 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 that face each other. The 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 from the position where the permanent magnet 26 is arranged in the rotation direction of the rotor 20 (clockwise in FIG. 1). Here, the shifted angle of 45 degrees is
Since the number of permanent magnets is a pair, the electrical angle is the same 45
It becomes degree. The position of the salient pole 52 on the other side is also a position shifted by 45 degrees in the rotation direction of the rotor 20 with respect to the position where the permanent magnet 27 is arranged.

The rotor 24 is laminated in the axial direction of the rotary shaft 22 using a jig, and then the rotary shaft 22 is press-fitted to temporarily fix the laminated rotor 24. An insulating layer and an adhesive layer are formed on the surface of the rotor 24 made of this electromagnetic steel sheet, and the rotor 20 is formed by melting and fixing the adhesive layer by heating to a predetermined temperature after lamination. It

On the other hand, the stator 32 which constitutes the stator 30.
Like the rotor 24, is formed by punching a thin sheet of non-oriented electrical steel sheet, 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 while the plate-shaped stators 32 are stacked and pressed against each other. In this state, the coil 36 is wound around the tooth 34 to complete the stator 30, and then the stator 30 is assembled to the case 40. Further, the rotor 20 is rotatably assembled by the bearings 41 and 42 of the case 40, whereby the three-phase synchronous motor 10 is completed.

In the three-phase synchronous motor 10 having such a structure, when a field current is caused to flow in 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. Generate a magnetic pole, which is attracted to a rotating magnetic field to rotate. As a result, the rotor 20 rotates in the clockwise direction.

2. Positions of salient poles 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 set to the permanent magnet 2
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 these positions are determined will be described in detail below. .

The output torque T of the synchronous motor of the synchronous machine using the permanent magnet is obtained by the following expression (1) as a general expression. T = Tm + Tr (1) Here, Tm is the magnet torque due to the magnetic field Φm of the permanent magnet, and Tr is the reluctance torque. Tm,
Tr is calculated 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 the q-axis inductance, and Ld is d. The axis inductances Iq and Id are each axis component of the armature current (field current). In addition, here
The direction of the d-axis is determined so that the d-axis component of the armature current has 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]

Now, the synchronous motor described in the prior art will be described. In the conventional synchronous motor, the permanent magnets and the salient poles are arranged at positions that are displaced by an electrical angle of 90 degrees.
Therefore, the respective axial components Iq and Id of the armature current are calculated from the following equations (5) and (5) from the armature current I and its direction θ (<0) as shown in the vector diagram of the armature current of FIG. The relationship according to 6) is provided. 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 changes in the output torque TPR of the conventional synchronous motor obtained by the equation (8). The portion of the first term relating to the magnet torque Tm of the equation (8) changes in proportion to cos θ as shown by the one-dot chain line in the figure, and the portion of the second term relating to the reluctance torque Tr of the equation (8). The portion changes in proportion to sin2θ as shown by the chain double-dashed line in the figure.
As a result, the output torque T which is the sum of both torques Tm and Tr
PR changes as shown by the solid line in the figure.

In FIG. 5, the magnet torque Tm is 0.
Takes a peak value and the reluctance torque Tr is -4
Since the peak value is taken at 5 degrees, both torques Tm, Tr
The output torque TPR, which is the sum of the above, has a peak value in the range of 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 both torques Tm and Tr are different.

On the other hand, the three-phase synchronous motor 10 of the present embodiment.
Is because the permanent magnets 26 and 27 and the salient poles 51 and 52 are arranged at positions where the electrical angles are shifted by 45 degrees,
The peak times of the magnet torque Tm and the reluctance torque Tr can be matched. The reason will be described below.

The fact that the angle formed by the permanent magnet and the salient pole is shifted by 45 degrees in terms of an 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 nothing but rotating the qd axis by 45 degrees in the direction opposite to the rotation direction of the rotor. This new q-d axis is shown in FIG. 6 as the q'-d 'axis. Therefore, 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. Therefore, by substituting [theta]-[pi] / 4 for [theta] in the equation (8) to transform it, the output torque T of the synchronous motor 10 of the present embodiment can be obtained by the following equation (9).

[0036]

[Equation 4]

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

FIG. 7 shows the change in the output torque T of the synchronous motor 10 of this embodiment, which is obtained by the equation (9). The portion of the first term related to the magnet torque Tm in the equation (9) changes in proportion to cos θ as shown by the one-dot chain 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 coincide.

Therefore, when the peak times of both torques Tm and Tr coincide with each other, that is, when θ is 0 degrees, the output torque T shown by the solid line in FIG. 7 is the peak value of the magnet torque Tm and the peak of the reluctance torque Tr. It becomes the value which added the value and. 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 How the output torque of the synchronous motor 10 of this embodiment is amplified as compared with the conventional example will be described below. First, regarding the conventional synchronous motor, the current phase θ that maximizes the output torque is obtained from the equation (8). This current phase θ is given by the following equation (1
0) and the maximum torque TPR (ma
x) is calculated by the equation (11).

[0041]

[Equation 5]

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

[0043]

[Equation 6]

From equations (11) and (12), T (max) / TP
R (max) is calculated 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 = ΔL.

[0045]

[Equation 7]

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

[Equation 8]

T (max) / TPR obtained by the equation (13)
The change in the value of (max) is shown in FIG. From this figure, Y
If (= ΔL · I / 2Φm) takes a negative value, T (max)
It can be seen that / TPR (max) becomes larger than 1.0. Here, the values of I and Φm are positive values, and since the synchronous machine exhibiting reverse saliency has a relationship of Ld <Lq, Y always takes a negative value. Therefore, T (max) / TPR
(Max) always becomes 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 size is ΔL
-It changes as shown in FIG. 8 according to I / Φm.

FIG. 9 is a graph showing changes 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 varies according to the magnitude of the armature current I, such as points P1, P2, ..., Pn. The points P1, P2, ..., Pn are the same as those described in (10).
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 points P1, P2, ..., Pn according to the magnitude of the armature current I. To be

FIG. 10 is a graph showing changes in the output torque T in the synchronous motor 10 of this 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 the value 0. 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 zero.

4. Configuration of Control Unit A control unit that controls the phase of the armature current of the synchronous motor 10 to 0 and performs maximum torque control will be described next. FIG. 11 is a schematic configuration diagram of the control unit 70 included in the synchronous motor 10 of this 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 inputs the torque signal T sent from the host controller and converts the torque signal T into each axis component Id, Iq of the armature current. Is 0 degrees, the d-axis component Id of the armature current is set to 0, and the armature current I is calculated from the torque T based on the relationship of the above-described equation (9), and this value is set to Iq. , Iq are output.

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

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, for example, an electric vehicle, and the output torque according to the operation amount of the accelerator pedal. Thus, the synchronous motor 10 rotates.

5. Effect of Embodiment As described in detail above, the output torque of the synchronous motor 10 of the present embodiment can be made larger than that of the conventional synchronous motor. As a result, the synchronous motor 10 of this embodiment is
If the same torque is obtained, the motor shape can be made small and lightweight. This means that the performance (driving distance, maximum hourly speed, 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 amount of the improved efficiency.

Further, since the control unit 70 provided in the synchronous motor 10 of the present embodiment is configured to control the phase of the armature current to 0 to perform the maximum torque control, the phase is held at 0 and the electric motor is controlled. It is sufficient to control only the q-axis component Iq of the child current, and it is possible to obtain extremely easy controllability while having reverse salient polarity that is relatively difficult to control.

In the present 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 structure, the peak time of the reluctance torque can be brought closer to the peak time of the magnet torque as compared with the conventional structure in which the angle is 90 degrees, and the output torque is made larger than that of the conventional synchronous motor. be able to.

The embodiment of the present invention has been described above.
The present invention is not limited to such an embodiment. For example, the number of permanent magnets provided on the outer circumference of the rotor is two, and the angle formed by the salient poles is two in the rotational direction of the rotor.
Various configurations such as a configuration with 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 can be implemented in various modes without departing from the scope 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 set the motor rotation direction to a fixed direction and use the rotation direction switching means by combining gears or the like to move the vehicle forward and backward.

[0057]

As described above, according to the rotor structure of the synchronous machine of the present invention, it is possible to easily manufacture the synchronous machine in which the peak times of the magnet torque and the reluctance torque match. Further, the synchronous motor adopting the rotor structure of the present invention can increase its output torque. Therefore, if the torque is the same, the shape can be reduced, and the efficiency as a motor can be improved to contribute to energy saving. In addition, it becomes possible to improve various performances of equipment equipped with this motor.

[Brief description of drawings]

FIG. 1 is a plan view showing the structure of a three-phase synchronous motor that is an embodiment of the present invention.

FIG. 2 is a sectional view showing the structure of a three-phase synchronous motor 10 incorporating a rotor 20 of 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 the ratio between the conventional peak value of output torque and the peak value of output torque of the embodiment.

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

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

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

[Explanation 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 70 ... Control part 71 ... Current conversion part 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

Claims (4)

[Claims] 1. A rotor structure of a synchronous machine, comprising a plurality of permanent magnets on the outer circumference of a rotor, and projecting salient poles made of a material having a high magnetic permeability between the plurality of permanent magnets. The salient pole is at an electrical angle of 45 degrees or more 90 degrees with respect to the fixed position of the permanent magnet.
A rotor structure for a synchronous machine, wherein the rotor structure is arranged at a position displaced by an angle of less than one degree in the rotation direction of the rotor. 2. The rotor structure for a synchronous machine according to claim 1, wherein an angle formed by the salient pole and the rotor is 45 degrees in electrical angle. 3. A synchronous motor comprising a rotor having a rotor structure according to claim 1. 4. The synchronous motor according to claim 3, further comprising control means for obtaining a maximum torque by setting the phase of the field current to zero.