CN1855675A - Permanent-magnet synchronous electric motor and method for manufacturing same - Google Patents

Abstract

To provide a permanent magnet type synchronous motor and a manufacturing method thereof, by allowing the characteristics of controlling the phases of torque ripple or backlash torque to overlap and cancel out, the torque ripple of the ripple component of the same order as the number of poles 2p of the magnet or The backlash torque decreases indefinitely close to zero. This permanent magnet synchronous motor is provided with: a stator (1) formed in an annular shape having Z (Z is a natural number) teeth on which windings (4) are arranged; (p is a natural number) The magnetic pole of the pole, the rotor (6) inserted into the ring of the stator, the energized phase is N-phase, and the shape of the teeth forming each phase is made in at least 1 phase and a maximum of N-1 phases It is a shape different from the shape of each other phase.

Description

Permanent magnet synchronous motor and manufacturing method thereof

technical field

The invention relates to a permanent magnet synchronous motor and a manufacturing method thereof.

Background technique

In the inner rotor type permanent magnet synchronous motor, the cogging torque (also known as cogging torque, cogging torque) is when the winding is not energized, when the rotor magnet (rotor) is rotated by an external drive, it is in contact with the stator The torque ripple component that occurs between the teeth of the core is also the torque ripple that occurs between the stator core and the teeth when the winding is energized and driven.

Theoretically, only the least common multiple of the number of poles 2p of the rotor magnet and the number of teeth (slots) Z of the stator core appears (see Non-Patent Document 1). However, this theory is limited to cases where the rotor (mainly magnets) or the stator core are uniform in shape and material properties, respectively, and manufactured completely symmetrically with respect to the number of poles and slots.

However, in an actual machine, especially at a mass production site, the symmetry of the number of poles and slots is often broken, so the backlash torque or torque ripple component whose order is lower than the least common multiple appears with a large amplitude. In hoisting motors for elevators, this increase in torque ripple causes deterioration of ride comfort of the elevator, or in servo motors, problems arise in constant speed control. In addition, an increase in the backlash torque causes deterioration of positioning accuracy, or in the case of an automotive power control motor, deterioration of the contact performance of the steering wheel, which greatly affects the performance of the product.

Here, returning to the principle of torque generation, the mechanism of generating the pulsating component of torque will be described. The torque is related to the magnetic flux density, and the torque increases when the magnetic flux passes easily. The easiness of passage of magnetic flux is called permeance (reciprocal of reluctance), and torque is generated in proportion to its square. Therefore, if the permeance changes, it becomes torque ripple or backlash torque.

In the case where the magnet that is the source of the magnetic flux has uneven distribution and a symmetry that does not match the number of poles, this phenomenon is induced on the stator side, and pulsations of the number of slots and its higher-order components appear. . The high-order component is a high-order harmonic component caused by the uneven component not necessarily changing in a sine wave.

The main flux is from the magnet through the air and back to the magnet from the teeth of the stator core through the back yoke section, so the channel material is divided into two parts. One part is the air that exists between the rotor and the stator, and the other part is the magnetic body that makes up the core. In recent years, laminated bodies using electrical steel sheets have become more and more magnetic as magnetic materials, and therefore the magnetic properties of the electrical steel sheets have become a problem in many cases. When the distribution of the main magnetic flux flow is not uniform and there is symmetry that does not match the number of slots, this phenomenon is induced on the rotor side, and pulsations of the number of poles and its higher-order components appear.

In the passage of magnetic flux, in the air, the magnetic permeability μ indicating the difficulty of passing the magnetic flux is constant, so the magnetic flux in the air appears as the length of the gap (gap) changes. The physical quantities that affect the main magnetic flux around the rotor magnet and stator teeth are roughly divided into two, one is the gap (called air gap) representing the shortest distance between the outer diameter of the rotor magnet and the stator teeth, and the other is the phase The gap between adjacent stator teeth (generally referred to as the opening width).

In addition, in order to facilitate the winding process, when the stator core is not manufactured with a substantially circular integrated core, but a part or the whole of the core is divided between the teeth, when the divided parts are joined , there is a tiny gap, which becomes the gap between gaps.

In addition, when a part is divided to form a winding and then joined, the shape of this part may differ from other parts depending on the conditions of the joining process, resulting in structural non-uniformity.

Next, the magnetic permeability of iron cores made of magnetic materials such as electromagnetic steel plates varies among individuals due to various reasons, and in the same body, uneven distribution may occur in many cases. As one of the reasons for the difference in the same body, for example, because the magnetic properties of the electromagnetic steel sheet are different in the rolling direction and the vertical direction (called magnetic anisotropy), depending on the method of punching the core shape, there may be a difference in the core shape. Specific parts have different permeability. In addition, when the electromagnetic steel sheet is punched with the blade of the die, the magnetic permeability of the tooth end surface is deteriorated due to the force exerted by the blade, or due to the embedding process of the concave-convex portion (called the caulking portion) for fixing the lamination, the caulking portion and the The magnetic permeability of its periphery deteriorates.

In addition, in most cases, the frame is mounted on the outer periphery of the stator core where the stator will not be displaced due to the torque force generated between the rotating rotor and the stator, and the manufacturing process of fixing it to the bearing frame that supports the bearing is performed. The force exerted by the frame on the outer periphery of the stator core not only affects the vicinity of the outer periphery of the stator core where magnetic flux hardly passes, but also affects the vicinity of the teeth as the main passage, and sometimes affects the magnetic properties of the electromagnetic steel sheet that is the main passage of magnetic flux. Deterioration, or displacement of teeth, changes the shape of the inner diameter of the stator core.

Ideally, if the gap and magnetic characteristics are made uniform with respect to the number of poles and slots, low-order backlash torque can be generated.

As mentioned above, due to the unevenness of the magnet side, the torque ripple or backlash torque whose frequency corresponds to the number of slots Z occurs, due to the unevenness of the air gap, the unevenness of the opening width, and the unevenness of the gap between the gaps Magnetic properties, distribution of magnetic properties related to magnetic anisotropy of electrical steel sheets, stress of punched or riveted parts, frames, distribution of magnetic properties due to local deterioration of magnetic permeability, and unevenness of gaps between gaps between split cores Due to various reasons, such as distribution or structural unevenness of the junction, torque ripple or backlash torque occurs at a frequency corresponding to the number of poles 2p.

In order to improve mass productivity, these reasons are caused by the restriction of the manufacturing method or the working precision in the manufacturing process, which inevitably occurs in the actual motor.

Focusing on the manufacturing process, attempts to reduce torque ripple or backlash torque can be seen. For example, such a countermeasure is proposed: in order to obtain the uniformity of the air gap, when the stator is pressed into the frame, it is fixed by applying pressure evenly from the outer circumference of the iron core to the inner circumference, so as to ensure the roundness of the inner diameter (for example, refer to the patent Literature 1).

In addition, the direction of the magnetic anisotropy is shifted from the central angle of the teeth to reduce torque ripple and backlash torque due to the magnetic anisotropy (for example, refer to Patent Document 2).

In addition, keep the thickness of the frame as uniform as possible, keep the force applied by the frame to the stator uniform, and prevent the inner diameter shape of the stator from becoming uneven, thereby preventing torque ripple or an increase in backlash torque ( For example, refer to Patent Document 3).

In addition, in consideration of the influence of the caulking portion, measures to limit the number of caulking portions have been proposed (for example, refer to Patent Documents 4 and 5).

In addition, by arranging seams at substantially equal intervals in the circumferential direction and laminating them, the non-uniformity of magnetic flux caused by the seams is eliminated (for example, refer to Patent Document 6).

In addition, the terminal portion of the laminated core is formed such that it has a first portion close to the inner peripheral surface of the permanent magnet and a second portion farther from the inner peripheral surface in an asymmetric shape, thereby suppressing backlash torque or torque Pulsation (for example, refer to Patent Document 7).

[Patent Document 1] Japanese Patent Application Laid-Open No. 2001-218429

[Patent Document 2] Japanese Patent Application Laid-Open No. 9-23687

[Patent Document 3] Japanese Patent Application Laid-Open No. 2001-95199

[Patent Document 4] Japanese Patent Application Laid-Open No. 2001-258225

[Patent Document 5] Japanese Patent Application Laid-Open No. 2002-272074

[Patent Document 6] Japanese Patent Application Laid-Open No. 6-52346

[Patent Document 7] Japanese Patent Application Laid-Open No. 9-103062

[Non-Patent Document 1] Akihiro Ohtani et al., "Experimental Discussion on the Backlash Torque of a PM Motor When External Stress Is Applied", Electrical Society Rotating Machine Research Material RM-03-152 (2003), P13-18

As described in the prior art described above, if measures focusing on only one characteristic are taken, the torque ripple or the backlash torque cannot be sufficiently reduced. In particular, in a mass-produced actual motor, it is difficult to infinitely reduce the torque ripple or the backlash torque to zero regardless of the operating accuracy.

In addition, in the case of suppressing the backlash torque or torque ripple by control, since it is necessary to store the information of the backlash torque or torque ripple that the motor has in the memory of the control device and use it, there is a device Problems such as structure and manufacturing management become complicated.

Therefore, there is a demand for a technique for quantifying torque ripple or backlash torque generated by an operating error of a motor and reducing it in a single motor.

In a permanent magnet synchronous motor, the causes of torque ripple or backlash torque equal to the number of poles 2p of the magnet are complex due to various factors such as the unevenness of the gap portion and the unevenness of the magnetic properties. occurred due to the overlap. In this case, it is necessary to separate the various causes, estimate them accurately, and take corrective measures for each reduction. However, in the case of short-term product development at a mass production site, it takes time, labor, and money to individually pursue these various causes and take countermeasures, and it is also technically very difficult.

The present invention has been made to solve the above-mentioned problems, and its purpose is to obtain a motor that will be the same as the number of poles 2p of the magnet without investigating and separating the complicated respective causes of torque ripple or backlash torque and taking countermeasures respectively. A permanent magnet synchronous motor in which the torque ripple or backlash torque of the pulsation component of the order is reduced to infinitely close to 0, and its manufacturing method.

Contents of the invention

In the permanent magnet synchronous motor of the present invention, there are: a stator formed in an annular shape having Z (Z is a natural number) teeth on which windings are arranged; The magnetic pole of the pole and the rotor inserted into the ring of the stator make the energized phase N-phase, and in at least 1 phase and a maximum of N-1 phase, the shape of the teeth forming each phase is in the same shape as that of other phases. different shapes.

In addition, in teeth of at least one phase and at most N-1 phase, caulking portions not formed in other phases are formed.

In addition, in the manufacturing method of the permanent magnet synchronous motor of the present invention, the following steps are included: measuring the backlash torque or rotational speed of a motor whose stator core has symmetrically shaped teeth and other manufacturing conditions are the same as the final specifications. Moment pulsation, as a step of phase information and amplitude information based on the reference position; forming a stator core manufacturing process in which the shape of the tooth in at least 1 phase and the maximum N-1 phase is different from that of other phases, so that the corresponding The generated backlash torque or torque ripple, a step of generating a backlash torque or torque ripple with substantially equal amplitude and opposite phase; and a step of manufacturing a motor by using a stator core manufacturing process.

According to the present invention, for example, in the case of a 3-phase motor, since the core shape of only 1 or 2 phases is changed in the UVW phase, the backlash torque generated by the asymmetrical core shape corresponding to the number of energized phases is utilized Or torque ripple, offset the backlash torque caused by the non-uniformity of the stator that occurs in the structure or in the manufacturing process, and can provide a permanent magnet synchronous motor with reduced overall backlash torque.

Description of drawings

1 is a sectional view showing a section perpendicular to an axial direction of a permanent magnet synchronous motor according to Embodiment 1 of the present invention.

FIG. 2 is an explanatory diagram showing an articulated core of a stator of the permanent magnet synchronous motor according to Embodiment 1 of the present invention.

FIG. 3 is a diagram corresponding to FIG. 1 showing a stator of a conventional permanent magnet synchronous motor trial-produced in a development stage for comparison with the present invention.

4 is a sectional view showing a section perpendicular to the axial direction of a permanent magnet synchronous motor according to Embodiment 2 of the present invention.

5 is a sectional view showing a section perpendicular to the axial direction of a permanent magnet synchronous motor according to Embodiment 3 of the present invention.

5 is a sectional view showing a section perpendicular to the axial direction of a permanent magnet synchronous motor according to Embodiment 4 of the present invention.

7 is a sectional view showing a section perpendicular to the axial direction of a permanent magnet synchronous motor according to Embodiment 5 of the present invention.

8 is a sectional view showing a section perpendicular to the axial direction of a permanent magnet synchronous motor according to Embodiment 6 of the present invention.

9 is a sectional view showing a section perpendicular to the axial direction of a permanent magnet synchronous motor according to Embodiment 7 of the present invention.

10 is a sectional view showing a section perpendicular to the axial direction of a permanent magnet synchronous motor according to Embodiment 8 of the present invention.

11 is a sectional view showing a section perpendicular to the axial direction of a permanent magnet synchronous motor according to Embodiment 9 of the present invention.

12 is a sectional view showing a section perpendicular to the axial direction of a permanent magnet synchronous motor according to Embodiment 10 of the present invention.

13 is a sectional view showing a section perpendicular to the axial direction of a permanent magnet synchronous motor according to Embodiment 11 of the present invention.

14 is a sectional view showing a section perpendicular to the axial direction of a permanent magnet synchronous motor according to Embodiment 12 of the present invention.

In the figure 1: stator core, 2: seam (welding part), 3: riveting part, 4: winding (coil), 5: shaft, 6: rotor core, 7: permanent magnet, 8: rolling of electromagnetic steel plate Arrow of the direction, 9: the riveting pin in the center of the tooth body, 10: the frame

Detailed ways

The present invention is provided with: a stator formed in an annular shape and having Z (Z is a natural number) teeth on which windings (coils) are arranged; and a permanent magnet having 2p (p is a natural number) poles inserted into the annular ring of the stator inner rotor. Specifically, in the case of shrink-fitting or molding, the frame may be a frame having a thickness distribution such as a substantially quadrangular shape instead of a ring shape.

In the process before the frame is installed, an identifiable mark is marked on each tooth of the stator at one or more positions as a reference position. In the case where there is a joint portion joined together as a split core, the joint portion may be used as a reference position.

In the trial production stage, a plurality of normal stator cores having a symmetrical shape corresponding to the number of teeth are manufactured, backlash torque or torque ripple is measured, and the generated state is separated into phase information and amplitude information based on a reference position and grasped.

Corresponding to the backlash torque or torque ripple that occurs, a backlash torque or torque ripple with approximately equal amplitude and opposite phase is generated. For this purpose, for example, in the case of a 3-phase motor, only 1 is changed in the UVW phase. The core shape of the phase or 2 phases is characteristic.

In this way, the backlash torque or torque ripple generated by the asymmetrical core shape corresponding to the number of energized phases can be used to cancel the backlash torque caused by the unevenness of the stator that occurs in the structure or in the manufacturing process. A permanent magnet synchronous motor with reduced overall backlash torque and a manufacturing method thereof are obtained.

(Embodiment 1)

Fig. 1 is a cross-sectional view showing a section perpendicular to the axial direction of the permanent magnet synchronous motor according to Embodiment 1 of the present invention, and Fig. 2 is a articulated view showing the stator of the permanent magnet synchronous motor according to Embodiment 1 of the present invention. An illustration of Iron Heart. In FIG. 1 , the stator core 1 is a joint-type core formed by laminating isotropic electromagnetic steel sheets formed with 12 teeth 1a and 12 slots 1b.

As shown in Figure 2, the joint-type iron core 1 is wound by unfolding the iron core in a straight line, the winding process is easy to automate, and the winding can be oriented, which improves the mass production of the winding process and can improve the winding efficiency. performance.

After winding the wires, the core is closed into a circle and the ends are welded to form the stator. In FIG. 1 , 2 denotes a joint of the stator core 1 , 3 is a caulking portion forming a joint of the stator core 1 , and 4 is a coil wound on each tooth 1 a of the stator core 1 . As shown in FIG. 1 , the winding 4 is wound so that the magnetic poles are concentrated, and the UVW phases are formed sequentially in the clockwise direction with the joint position as a reference position.

A ring-shaped permanent magnet 7 magnetized to 8 poles (the number of pole pairs is 4) is attached to the surface of the rotor core 6 in which the shaft 5 is embedded, thereby constituting the rotor.

In this example, although the frame is not shown in the figure, as a cross-sectional shape of the frame perpendicular to the rotor shaft 5, both the external shape and the internal shape are predetermined circular (hereinafter referred to as circular frame).

In this first embodiment, the width of the main body portion of the four teeth of the V phase is reduced by about 30% compared to the V phase of the U phase, and the asymmetry of the tooth shape between UVW and W is intentionally provided.

Next, the procedure for establishing the above-mentioned asymmetry of the tooth shape will be described.

FIG. 3 shows a stator of a conventional permanent magnet synchronous motor that was trial-produced in the development stage. In FIG. 3 , the tooth (groove) shape is 12 times symmetrical, and in the UVW phase, the shape is the same. For the three prototype machines shown in FIG. 3 , the torque ripple and backlash torque of the load ±100% were measured. As a result, the measurement results of the three units showed that there were 8 peaks in one cycle of the electrical angle, that is, there were many pulsation components having twice the number of pole pairs, and their amplitudes were: for torque pulsation, it was rated rotation 2.0% ± 0.15% of torque, for backlash torque, it is 1.5% ± 0.1%. In addition, the phases of the pulsations when only the pulsation components having twice the number of pole pairs are extracted are 150°±30° with respect to the reference position.

The torque ripple with an amplitude of 2.0% and the backlash torque of 1.5% are too large for the product and must be reduced to 1.0% or less.

As a result of investigation into the cause of these torque ripples appearing as a component twice the number of pole pairs, it was found that the seam part has a different structure from other joint parts. However, regarding the manufacturing method of the jointed core, it is a method to significantly improve the winding process and performance, and it is known that the torque ripple of the component twice the number of pole pairs caused by the difference in the structure of the joint part cannot be reduced by improving the original cause.

Therefore, focusing on the phase of the torque ripple around 150 degrees in the three prototype machines, the torque ripple that occurs when the teeth are made asymmetrical in the UVW phase is studied using the electromagnetic field analysis method. It can be seen that if only four The tooth width of the V phase is narrowed by about 30%, and a torque ripple of 330 degrees with a phase shift of 180 degrees is generated with the same amplitude as the pulse generated in the prototype machine.

In the torque ripple that appears at twice the number of pole pairs, the research of the inventors has revealed that torque ripples that occur due to individual causes can be superimposed, so by making the tooth shape of the UVW phase asymmetrical, it is possible to make Torque ripples due to unavoidable causes that occur due to differences in the structure of the seam can cancel each other out.

Based on the above, a stator core with the tooth shape shown in Fig. 1 changed only for the V-phase was produced, and the torque ripple and backlash torque were measured. The amplitude of the torque ripple was 0.5%, and the amplitude of the backlash torque was 0.5%. 0.1%, can reduce torque ripple.

However, unlike the conventional example, since the tooth width of the first phase is narrowed, the magnetic flux passing through the tooth is slightly less than the conventional example, and the average torque is reduced, but since the reduction is within the specification range, it is not available as a product. question. In addition, with regard to the average torque, other countermeasures such as increasing the strength of the magnet on the rotor side or changing the core material to a material that facilitates the passage of magnetic flux are used.

As described above, unlike the conventional UVW phase, by intentionally asymmetrically forming the portion where the tooth shape should be formed symmetrically, it is possible to reduce torque ripple and backlash torque that inevitably occur in the structure.

In Embodiment 1, although the core shape was changed only in the W phase, the present invention does not limit the asymmetric phase and the number of phases. According to the status of the prototype machine, in the U phase or the V phase, additionally, as necessary, in the U phase It does not matter if the shape is changed between two phases such as UV phase and VW phase.

In addition, in the first embodiment, torque ripple is reduced by changing the tooth width, but the present invention does not limit the changing position in terms of the shape of the iron core. The same asymmetry of the UVW phase can also be formed in the width of both ends of the tooth, that is, the width of the slot opening, and it does not matter if the asymmetry is formed on the left and right of the tooth.

However, regarding the position where the shape is changed, the shape of the tip of the tooth facing the rotor or the opening width of the slot between the teeth is the main passage of magnetic flux. If it is difficult to control the shape due to the size relationship of the error, it is also effective to increase the amount of change and change the part that has little influence on the torque ripple.

In addition, in Embodiment 1, although the torque ripples due to the unique structure of the joint-type core are canceled out by using the asymmetrical shape between the phases, it is also possible to use the asymmetrical shape between the phases in the circular punched integrated core. For example, torque ripples of components appearing twice the number of pole pairs that occur due to differences in magnetic properties in a direction perpendicular to the rolling direction of the electrical steel sheet cancel each other out.

In addition, in Embodiment 1, since the frame with a circular shape is used, there is no torque ripple with a component twice the number of pole pairs caused by the frame. distribution, and when the stress distribution and deformation of the stator core occur after the frame is formed, and as a result, torque ripple with a component twice the number of pole pairs occurs, considering these, it does not matter to form an asymmetric shape between phases.

(Embodiment 2)

4 is a sectional view showing a section perpendicular to the axial direction of a permanent magnet synchronous motor according to Embodiment 2 for carrying out the present invention. In FIG. 4 , the stator core 1 is a joint-type core formed by laminating isotropic electromagnetic steel sheets formed with 12 teeth 1a and 12 slots 1b. The rotor is an 8-pole (4 pole pairs) rotor.

In this example, the frame is not shown, but as a cross-sectional shape of the frame perpendicular to the rotor shaft 5, both the external shape and the internal shape are predetermined circular (hereinafter referred to as circular frame).

The winding 4 is the same as that of the first embodiment.

In this second embodiment, the width of the body portion of two of the four teeth of the V phase is reduced by about 30% compared to the V phase of the U phase, and the asymmetry of the tooth shape is intentionally provided between UV and W.

For the reduction effect of torque ripple and backlash torque, the amplitude of torque ripple becomes 1.0%, and the amplitude of backlash torque becomes 0.3%. Although the reduction amount is smaller than that of Embodiment 1, it is within the necessary specification range Inside, so there is no problem with torque ripple as a product. In addition, compared with Embodiment 1, by reducing the number of thinned teeth, the amount of magnetic flux passing through the teeth is also increased compared with Embodiment 1, so the effect of greater average torque than Embodiment 1 can be obtained.

The same reduction effect can be obtained by making the tooth main body part of four teeth slightly thinner than that of Embodiment 1, but in small and medium-sized motors, the change in the tooth width used as a reference is small, and the degree of manufacturing tolerance is small. In the same case, it is easy to be affected by manufacturing errors and become a cause of deviation, so it is adjusted by reducing the number.

In addition, depending on the wiring method of the winding, in addition to the reduction effect of torque ripple, a greater reduction effect on noise and vibration may be exhibited.

In this way, in the case of making the tooth shape of the UVW phase asymmetric and reducing the torque ripple, when adjusting the amount of reduction, the number of teeth may be more important than changing all the teeth of the phase whose shape is changed. A more efficient way to make adjustments.

(Embodiment 3)

5 is a sectional view showing a section perpendicular to the axial direction of a permanent magnet synchronous motor according to Embodiment 3 for carrying out the present invention. In FIG. 5 , the stator core 1 is an integral core punched out of isotropic electrical steel sheets in a substantially circular shape without joints, and is formed by stacking cores formed with 12 teeth 1a and 12 slots 1b. The rotor is an 8-pole (4 pole pairs) rotor.

In this example, the frame is not shown, but as a cross-sectional shape of the frame perpendicular to the rotor shaft 5, both the external shape and the internal shape are predetermined circular (hereinafter referred to as circular frame).

The winding 4 is the same as that of the first embodiment.

In FIG. 5 , 8 indicates the rolling direction of the electrical steel sheet during punching. In general, it is known that even with isotropic electrical steel sheets, the easiness of passage of magnetic flux differs between the rolling direction and the direction perpendicular thereto. The magnetic asymmetry caused by the difficulty of passing the magnetic flux in the rolling direction and the vertical direction is different, resulting in torque ripple.

In this Embodiment 3, in order to cancel the torque ripples caused by the magnetic asymmetry, the width of the main body portion of the four teeth of the V phase is made smaller than that of the U phase and the W phase, and the width between UVW and W phase is intentionally Establishes the asymmetry of the tooth shape.

(Embodiment 4)

6 is a sectional view showing a section perpendicular to the axial direction of a permanent magnet synchronous motor according to Embodiment 4 for carrying out the present invention. In FIG. 6 , the stator core 1 is an integral core punched out of isotropic electrical steel sheets in a substantially circular shape without joints, and is formed by stacking cores formed with 12 teeth 1a and 12 slots 1b. The rotor is an 8-pole (4 pole pairs) rotor.

The frame is a frame designed such that, as a cross-sectional shape of the frame perpendicular to the rotor shaft 5, the inner shape is circular and the outer shape is quadrilateral (roughly square) (hereinafter referred to as a square frame).

The winding 4 is the same as that of the first embodiment.

The process of mounting the stator to the frame is performed by shrink fitting, but at this time the stator core is subjected to stress from the frame, and eventually the inner diameter of the stator core is deformed, and local residual stress occurs at the same time. The distribution of the residual stress causes the distribution of the deterioration of the magnetic properties of the core steel sheet, which causes torque ripple. In the case of a circular frame, each tooth receives roughly the same change, but in the case of a square frame, the thick and thin parts of the frame give different stresses to the core, so among the 12 teeth, the Asymmetry of large and small parts.

In this fourth embodiment, in addition to the magnetic asymmetry caused by the rolling direction of the steel sheet described in the third embodiment, in order to cancel the asymmetry caused by the stress of the stand, the teeth of the four teeth of the V phase The width of the main body is smaller than that of the U-phase and W-phase, and the asymmetry of the tooth shape is intentionally established between UVW and W-phase.

(Embodiment 5)

7 is a sectional view showing a section perpendicular to the axial direction of a permanent magnet synchronous motor according to Embodiment 5 for carrying out the present invention. In FIG. 7 , the stator core 1 is a joint-type core formed by laminating isotropic electromagnetic steel sheets formed with 12 teeth 1a and 12 slots 1b. The rotor is an 8-pole (4 pole pairs) rotor.

In this example the frame is circular although it is not shown in the figure.

The winding 4 is the same as that of the first embodiment.

In Embodiment 5, the tip thicknesses of the eight teeth of the U-phase and W-phase are made thicker than those of the V-phase, and the asymmetry of tooth shapes between UVW and W is intentionally established. The main body of the tooth is the main passage of the magnetic flux, and a change in the width of the main body of the tooth sensitively affects the torque ripple. Therefore, in small and medium-sized motors, when the variation in the width of the main body is as large as the manufacturing error, the thickness of the tip of the teeth is changed not the width of the main body. In fact, the thickness of the tip of the tooth on the opposite side to the rotor is increased, but compared with changing the width of the main body of the tooth, the same torque ripple reduction effect can be obtained with a larger dimensional change. That is, the influence of manufacturing errors can be reduced.

(Embodiment 6)

8 is a sectional view showing a section perpendicular to the axial direction of a permanent magnet synchronous motor according to Embodiment 6 for carrying out the present invention. In FIG. 8 , the stator core 1 is a joint-type core formed by laminating isotropic electromagnetic steel sheets formed with 12 teeth 1a and 12 slots 1b. The rotor is an 8-pole (4 pole pairs) rotor.

In this example the frame is circular although it is not shown in the figure.

The winding 4 is the same as that of the first embodiment.

In Embodiment 6, the tip widths of the four teeth of the V phase are narrower than those of the U phase and W phase, and the asymmetry of the tooth shape between UVW and W is intentionally established. Changing the width of the front ends of the teeth means changing the width of the gap between the teeth, that is, the slot opening. The slot opening width is the main passage of magnetic flux, so the sensitivity of the torque ripple to the amount of change in size is large. Effective in large motors.

(Embodiment 7)

9 is a sectional view showing a section perpendicular to the axial direction of a permanent magnet synchronous motor according to Embodiment 7 for carrying out the present invention. In FIG. 9 , the stator core 1 is a joint-type core formed by laminating isotropic electrical steel sheets formed with 12 teeth 1a and 12 slots 1b. The rotor is an 8-pole (4 pole pairs) rotor.

In this example the frame is circular although it is not shown in the figure.

The winding 4 is the same as that of the first embodiment.

In Embodiment 7, the lengths of the four teeth between VV are made shorter than those between UU and WW, and the asymmetry of the tooth shape is intentionally established between UVW and WW. Changing the length of the teeth means changing the gap between the tip of the tooth and the rotor magnet, that is, the length of the gap. The gap is the main channel of magnetic flux, so the sensitivity of torque ripple to the amount of change in size is large. Effective in large motors.

(Embodiment 8)

10 is a sectional view showing a section perpendicular to the axial direction of a permanent magnet synchronous motor according to Embodiment 8 for carrying out the present invention. In FIG. 10 , the stator core 1 is a joint-type core formed by laminating isotropic electromagnetic steel sheets formed with 12 teeth 1a and 12 slots 1b. The rotor is an 8-pole (4 pole pairs) rotor.

In this example the frame is circular although it is not shown in the figure.

The winding 4 is the same as that of the first embodiment.

In this eighth embodiment, the angular positions of the four teeth of the V phase are shifted from those of the U phase and W phase, and the asymmetry of tooth shapes between UVW and W phase is intentionally established. Changing the pitch in the rotational direction of the teeth means changing both the length of the magnetic flux inside the teeth and the gap (slot opening and gap) between the rotor magnetic flux and the teeth. It is effective when the torque ripple generated when the UVW phase is formed symmetrically is significantly large.

(Embodiment 9)

11 is a sectional view showing a section perpendicular to the axial direction of a permanent magnet synchronous motor according to Embodiment 9 for carrying out the present invention. In FIG. 11 , the stator core 1 is a joint-type core formed by laminating isotropic electromagnetic steel sheets formed with 18 teeth 1a and 18 slots 1b. The rotor is a rotor with 16 poles (the number of pole pairs is 8).

In this example the frame is circular although it is not shown in the figure.

Winding 4 is U, U , V, V , V, W, W , W in turn from the seam position to the left. Here, U, V, W indicate that the current direction is rotated to the right, and U , V , W indicate that the current direction is rotated to the left, thereby showing a change in the winding direction or wiring of the winding.

In Embodiment 9, although the number of pole slots is different from Embodiment 1, the thickness of the tips of the four V-phase teeth is thinner than that of U -phase, V-phase, V- phase, W-phase, and W- phase, and the thickness between UVW and W-phase is intentionally established. The asymmetry of the tooth shape makes the torque ripples generated by the structural asymmetry or magnetic asymmetry cancel each other out.

(Embodiment 10)

12 is a sectional view showing a section perpendicular to the axial direction of a permanent magnet synchronous motor according to Embodiment 10 for carrying out the present invention. In FIG. 12 , the stator core 1 is a joint-type core formed by laminating isotropic electromagnetic steel sheets formed with 18 teeth 1a and 18 slots 1b. The rotor is a rotor with 16 poles (the number of pole pairs is 8).

In addition, instead of punching a substantially circular shape at once, a laminated product (hereinafter referred to as a block) is manufactured by punching 180 degrees (substantially semicircular). The rolling direction of the electrical steel sheet is punched so that it coincides with the center of the block. After winding each block, the two blocks are combined to form a circle, and the joints are welded to make the stator core.

In this example the frame is circular although it is not shown in the figure.

The winding is the same as that of the ninth embodiment.

In Embodiment 10, only the front ends of the four U-phase and W-phase teeth located at the block end on the block joint side are thinned, and the asymmetry of the tooth shape between UVW and WW is intentionally established, so that The structural asymmetry of the joint portion at each position, or the torque ripple caused by the magnetic asymmetry caused by the coincidence of the rolling direction with the center of the block cancel each other out.

(Embodiment 11)

13 is a sectional view showing a section perpendicular to the axial direction of a permanent magnet synchronous motor according to Embodiment 11 for carrying out the present invention. In FIG. 13 , the stator core 1 is a joint-type core formed by laminating isotropic electrical steel sheets formed with 12 teeth 1a and 12 slots 1b. The rotor is a rotor with 10 poles (the number of pole pairs is 5).

In this example the frame is circular although it is not shown in the figure.

The winding is U, U , V, V , V, W, W , W in turn from the seam position to the left.

In this eleventh embodiment, although the number of pole slots is different from that in the first embodiment, the width of the main body parts of the two teeth of the U phase is made narrower than that of the U phase, V phase, V phase, W phase, and W phase, and the width between the UV and W phases is intentionally narrowed. The asymmetry of the tooth shape is established so that the torque ripples generated by the structural asymmetry or magnetic asymmetry cancel each other out.

(Embodiment 12)

14 is a sectional view showing a section perpendicular to the axial direction of a permanent magnet synchronous motor according to a twelfth embodiment for carrying out the present invention. In FIG. 14, the stator core 1 is a joint-type core formed by stacking cores formed with 12 teeth 1a and 12 slots 1b. The rotor is a rotor with 10 poles (the number of pole pairs is 5).

In this example, although the frame is not shown in the figure, as a cross-sectional shape of the frame perpendicular to the rotor shaft 5, both the external shape and the internal shape are predetermined circular (hereinafter referred to as circular frame).

The winding 4 is the same as that of the first embodiment.

In general, it is known that even isotropic electrical steel sheets have different degrees of difficulty in passing magnetic flux between the rolling direction and the direction perpendicular thereto. Magnetic asymmetrical torque ripple due to the difference in easiness of passage of magnetic flux in the rolling direction and in the perpendicular direction.

In the twelfth embodiment, in order to cancel the torque ripple caused by the magnetic asymmetry, a riveting pin 9 is provided in the center of the tooth body part of the four V-phase teeth, and a tooth structure is intentionally established between UVW and WW. of asymmetry.

Claims (10)

1, a kind of permanent-magnet synchronous electric motor has: form circular, as to have Z the tooth that has disposed winding stator, Z is a natural number; And have utilize permanent magnet carried out the 2p utmost point of excitation magnetic pole, be inserted into the rotor in the annulus of stator, p is a natural number, and makes energising be the N phase mutually, it is characterized in that:

At least 1 phase, maximum N-1 mutually in, make each the variform shape mutually that is shaped as of the tooth that forms this each phase with other.

2, a kind of permanent-magnet synchronous electric motor has: form circular, as to have Z the tooth that has disposed winding stator, Z is a natural number; And have utilize permanent magnet carried out the 2p utmost point of excitation magnetic pole, be inserted into the rotor in the annulus of stator, p is a natural number, and makes energising be the N phase mutually, it is characterized in that:

The direction of current flow that makes at least 1 phase, maximum N-1 phase is the shape of tooth of the phase of dextrorotation, and is different with the shape of the tooth of left-handed phase.

3, permanent-magnet synchronous electric motor according to claim 1 and 2 is characterized in that: make the main part width of the tooth that forms each phase, little or big than other phase.

4, permanent-magnet synchronous electric motor according to claim 1 and 2 is characterized in that: make the nose thickness of the tooth that forms each phase, thick or thin than other phase.

5, permanent-magnet synchronous electric motor according to claim 1 and 2 is characterized in that: make the front end width of the tooth that forms each phase, wide or narrow than other phase.

6, permanent-magnet synchronous electric motor according to claim 1 and 2 is characterized in that: make the length of the tooth that forms each phase, than the weak point or the length of other phase.

7, permanent-magnet synchronous electric motor according to claim 1 and 2, it is characterized in that: the current direction in a certain phase or a certain phase is in the phase or the part for left-handed phase of dextrorotation, make the tooth center of each phase of formation and the angle intervals between the tooth center, be the angle intervals mutually different with other.

8, a kind of permanent-magnet synchronous electric motor has: form circular, as to have Z the tooth that has disposed winding stator, Z is a natural number; And have the 2p utmost point permanent magnet, be inserted into the rotor in the annulus of stator, p is a natural number, and makes energising be the N phase mutually, it is characterized in that:

In the tooth of at least 1 phase, maximum N-1 phase, formed the caulking part that does not form in mutually at other.

9, a kind of permanent-magnet synchronous electric motor has: form circular, as to have Z the tooth that has disposed winding stator, Z is a natural number; And the permanent magnet with 2p utmost point, being inserted into the rotor in the annulus of stator, p is a natural number, and makes energising be the N phase mutually, it is characterized in that:

In the direction of current flow of at least 1 phase, maximum N-1 phase is in a part of tooth or a part of tooth for left-handed phase of phase of dextrorotation, has formed the caulking part that does not form in mutually at other.

10, a kind of manufacture method of permanent-magnet synchronous electric motor, this permanent-magnet synchronous electric motor has: form circular, as to have Z the tooth that has disposed winding stator, Z is a natural number; And have utilize permanent magnet carry out the 2p utmost point of excitation magnetic pole, be inserted into the rotor in the annulus of stator, p is a natural number, and makes energising be the N phase mutually, it is characterized in that comprising the following steps:

Stator core is had tooth and other motor identical with final specification of creating conditions of symmetric shape, measure backlash torque or torque pulsation that its produces, as based on the phase information of reference position and the step of amplitude information;

Form the shape stator core manufacturing process different of at least 1 phase, the maximum N-1 tooth in mutually with the odontoid of other phase, thereby make corresponding to the backlash torque or the torque pulsation that are produced the generation backlash torque that amplitude roughly is equal to, phase place is opposite or the step of torque pulsation; And

With above-mentioned stator core manufacturing process, make the step of motor.

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