PERMANENTMAGNET-SYNCHRONMOTOR

Abstract

A permanent magnet synchronous motor (50) is a permanent magnet synchronous motor comprising a stator (8), several teeth (2T) arranged at equal angles to the stator (8), and coils (1) wound in a concentrated winding manner around the respective several teeth (2T), the coils (1) forming a three-phase delta connection. A closed magnetic circuit is present in which a magnetic flux generated by a coil (1) wound around one tooth of two concrete teeth adjacent to each other in the several teeth (2T) passes through end sections of the two concrete teeth, passes through a coil (1) wound around another tooth of the two concrete teeth, passes through a back section of each of the two concrete teeth, and flows back to the coil (1) wound around the one tooth.In the closed magnetic circuit, the magnetic resistance of the closed magnetic circuit is lower when the coils (1) wound around the two specific teeth have the same phase than the magnetic resistance of the closed magnetic circuit when the coils (1) wound around the two specific teeth have different phases.

Description

Area

[0001] The present disclosure relates to a permanent magnet synchronous motor including a delta connection. background

[0002] In recent years, a motor with a reduced degree of torque ripple has been demanded in various applications. For example, a motor with a reduced degree of torque ripple is required for use in an industrial servo motor, an elevator drive, an electric power steering system for a vehicle, or the like. The connection configuration for use in a motor driven by a three-phase power supply is generally selected from a star connection and a delta connection, and the delta connection is advantageous for reducing the terminal voltage. Patent Literature 1 discloses a technique related to a permanent magnet motor incorporating a delta connection.

[0003] A permanent magnet motor incorporating a delta connection has a problem with the cyclic current flowing in the delta connection circuit. Since this causes torque ripple, the cyclic current must be reduced as much as possible. Patent Literature 2 discloses a technique in which a means for reducing the space harmonic components of a magnetic flux density generated by permanent magnets is provided on the rotor to reduce the cyclic current flowing in the delta connection. List of citationsPatent literature Patent Literature 1: Japanese Patent Application Laid-Open No. 2005-348522 Patent Literature 2: Japanese Patent Application Laid-Open No. 2008-301652 Brief description of the inventionProblem to be solved by the invention

[0004] However, providing a means to reduce the space harmonic components on the rotor imposes a limitation on rotor production. Furthermore, providing a means to reduce the space harmonic components, such as a rotor twist, not only reduces harmonics but also the fundamental frequency. This poses a problem regarding a decrease in the average torque of the motor.

[0005] The present disclosure has been made in view of the foregoing, and an object of the present disclosure is to provide a permanent magnet synchronous motor that enables reduction of a cyclic current flowing in a delta connection and reduction of a torque ripple due to the cyclic current with a smallest possible decrease in average torque. Ways to solve the problem

[0006] To solve the problems described above and achieve the object, a permanent magnet synchronous motor according to the present disclosure includes: a stator; a plurality of teeth arranged equiangularly on the stator; and coils wound around the plurality of respective teeth in a concentrated winding manner, the coils forming a three-phase delta connection. A closed magnetic circuit is provided in which a magnetic flux generated by a coil wound around one tooth of two adjacent specific teeth included in the plurality of teeth passes through end portions of the two specific teeth, passes through a coil wound around another tooth of the two specific teeth, passes through a stack back portion of each of the two specific teeth, and flows back to the coil wound around the one tooth.In the closed magnetic circuit, a magnetic resistance of the closed magnetic circuit when the coils wound around the two concrete teeth have the same phase is smaller than a magnetic resistance of the closed magnetic circuit when the coils wound around the two concrete teeth have different phases. Effects of the invention

[0007] A permanent magnet synchronous motor according to the present disclosure provides an advantage of enabling a reduction of a cyclic current flowing in a delta connection and a reduction of a torque ripple due to the cyclic current with a minimum decrease in the average torque. Short description of the drawings Fig. 1 is a schematic view illustrating a configuration of a permanent magnet synchronous motor according to a first embodiment. Fig. 2 is a cross-sectional view of the permanent magnet synchronous motor according to the first embodiment. Fig. 3 is a first diagram illustrating a connection of the coils included in the permanent magnet synchronous motor according to the first embodiment. Fig. 4 is a second diagram illustrating the connection of the coils included in the permanent magnet synchronous motor according to the first embodiment. Fig. 5 is a schematic diagram illustrating the teeth of the stator of the permanent magnet synchronous motor according to the first embodiment. Fig. 6 is a cross-sectional view illustrating a main portion of the teeth of the stator in an example of the permanent magnet synchronous motor according to the first embodiment. Fig. 7 is a cross-sectional view illustrating a main portion of the teeth of the stator in another example of the permanent magnet synchronous motor according to the first embodiment. Fig. 8 is a cross-sectional view illustrating a main portion of the teeth of the stator in still another example of the permanent magnet synchronous motor according to the first embodiment. Fig. 9 is a cross-sectional view illustrating a main portion of the teeth of the stator in the permanent magnet synchronous motor according to a second embodiment. Fig. 10 is a cross-sectional view illustrating a main portion of the teeth of the stator in the permanent magnet synchronous motor according to a third embodiment. Fig. 11 is a cross-sectional view illustrating a main portion of the teeth of the stator in the permanent magnet synchronous motor according to a fourth embodiment. Fig. 12 is a cross-sectional view illustrating a main portion of the teeth of the stator in an example of the permanent magnet synchronous motor according to a fifth embodiment. Fig. 13 is a cross-sectional view illustrating a main portion of the teeth of the stator in another example of the permanent magnet synchronous motor according to the fifth embodiment. Fig. 14 is a cross-sectional view illustrating a main portion of the teeth of the stator in another example of the permanent magnet synchronous motor according to the fifth embodiment. Fig. 15 is a cross-sectional view illustrating a main portion of the teeth of the stator in the permanent magnet synchronous motor according to a sixth embodiment. Fig. 16 is a cross-sectional view illustrating a main portion of the teeth of the stator in the permanent magnet synchronous motor according to a seventh embodiment. Fig. 17 is a three-dimensional view illustrating a main portion of a tooth of the stator in the permanent magnet synchronous motor according to an eighth embodiment. Fig. 18 is a cross-sectional view illustrating a main portion of stator teeth used in a permanent magnet synchronous motor having a tapered tooth structure. Description of embodiments

[0008] A permanent magnet synchronous motor according to embodiments will be described in detail below with reference to the drawings. First embodiment.

[0009] Fig. 1 is a schematic view illustrating a configuration of a permanent magnet synchronous motor 50 according to a first embodiment. The permanent magnet synchronous motor 50 includes a stator 8 and a rotor 9. The stator 8 includes a stator core 2 and coils 1 concentratedly wound around the stator core 2. The stator 8 is fixed to a frame 6 using a method such as shrink fitting or press fitting. A part of the stator core 2 is in the form of teeth. The permanent magnet synchronous motor 50 includes a plurality of teeth arranged equiangularly on the stator 8. The coils 1 are each wound around a corresponding one of the plurality of teeth in a concentrated winding manner. The permanent magnet synchronous motor 50 is a permanent magnet synchronous motor whose coils 1 form a three-phase delta connection.The rotor 9 includes a rotor core 3 and permanent magnets 4 and is attached to a shaft 7. A rotation sensor 5 for detecting the angle of rotation is provided on the shaft 7. The rotation sensor 5 can be, for example, a coordinate converter or a component that includes a magnet and a Hall element.

[0010] Fig. 2 is a cross-sectional view of the permanent magnet synchronous motor 50 according to the first embodiment. Fig. Figure 2 schematically illustrates a plane of the permanent magnet synchronous motor 50 according to the first embodiment, taken along the line II-II of Fig. 1. In the drawings referred to in the following embodiments, reference numerals which are the same as the reference numerals in Fig. 1, components which are the same as the components indicated by the corresponding reference numerals in Fig. 1, or are equivalent to them. As described above, the coils 1 are concentratedly wound around teeth 2T of the stator core 2. The coils 1 are wound around the teeth 2T using a pattern called "concentrated winding." The permanent magnet synchronous motor 50 includes twelve teeth 2T arranged at equal intervals in mechanical angle. The twelve teeth 2T are an example of the plurality of teeth. The permanent magnet synchronous motor 50 is a 10-pole, 12-slot motor including a total of ten permanent magnets 4 arranged around the rotor core 3 and twelve coils 1 arranged along a circumferential direction of the stator 8. The ten permanent magnets 4 are magnetized in a radial direction of the rotor 9.A specific one of the permanent magnets 4 is magnetized in a direction opposite to a magnetization direction of another one of the permanent magnets 4 adjacent to the specific one of the permanent magnets 4.

[0011] The permanent magnet synchronous motor 50 includes three-phase coils 1. Each of the three phases is one of phase U, phase V and phase W.

[0012] A reference symbol U1+, a reference symbol U1-, a reference symbol U2+, a reference symbol U2-, a reference symbol V1+, a reference symbol V1-, a reference symbol V2+, a reference symbol V2-, a reference symbol W1+, a reference symbol W1-, a reference symbol W2+, and a reference symbol W2-, each of which has no reference line thereto, indicate the coils 1. The symbol "+" or "-" is added to distinguish coils subject to different directions of a magnetomotive force generated when a current flows. For example, coils U1+ and U1- are two of the coils 1 that are adjacent to each other and have the same phase.The use of opposite winding directions in the two coils U1+ and U1- of the coils 1, or the use of a well-designed connection of connecting lines to cause currents to flow in opposite directions through these two coils 1, causes the magnetomotive force of the coil U1+ to have a direction opposite to the direction of the magnetomotive force of the coil U1-. In the first embodiment, the coils 1 are arranged in the order U1+, U1-, W1-, W1+, V1+, V1-, U2-, U2+, W2+, W2-, V2-, and V2+. By connecting these coils 1 in this way, the three-phase permanent magnet synchronous motor 50 is formed.

[0013] Fig. Fig. 3 is a first diagram illustrating a connection of the coils 1 included in the permanent magnet synchronous motor 50 according to the first embodiment. In Fig. 3, the coils U1+, U1-, U2+ and U2-, which are the coils 1 of phase U, are connected in series with each other and the coils 1 of the other two phases are also connected in a similar way. Fig. Figure 3 illustrates a case of a so-called delta connection, in which the coils 1 of the phases are connected in a circle. In a delta connection, in contrast to the case of a star connection, a cyclic current flows. The cyclic current is a current that flows in such a way that it circulates through the three-phase coils 1, as indicated by the black curved arrow in the center of Fig. 3. The relationship Iu=Iv=Iw applies, where Iu represents a current 10 of phase U, Iv represents a current 11 of phase V, and Iw represents a current 12 of phase W of the cyclic current. Other connection methods include the one described in Fig. 4 illustrated procedures. Fig. Figure 4 is a second diagram illustrating the connection of the coils 1 included in the permanent magnet synchronous motor 50 according to the first embodiment. The coils U1+ and U1- are connected in series with each other, and the coils U2+ and U2- are connected in series with each other, while a group of coils "U1+ and U1-" and a group of coils "U2+ and U2-" are connected in parallel with each other. In this case, too, current flows similarly to the case of Fig. 3 a cyclic current, as indicated by the black curved arrow in the middle of Fig. 4 is specified.

[0014] A mechanism for generating a cyclic current is described in more detail next. Assume that i u , i v and i w denote currents flowing in the respective phases of the delta connection, and then i u can be expressed by equation (1) below, i vcan be expressed by equation (2) below and i w can be expressed by equation (3) below. Formula 1: iu=iu1+icyc Formula 2: iv=iv1+icyc Formula 3: iw=iw1+icyc

[0015] The symbols i u1 , i v1 and i w1 represent fundamental frequency components of the respective phases, which are specified to have phase differences of 120 degrees from each other in electrical angle. The symbol i cycrepresents the cyclic current. The cyclic current generally represents harmonics, each of which has an order 3n times the order of the fundamental frequency, and has an equal value, including its phase, among the three phases, where n is an integer greater than or equal to 1. The voltage equation for these phases is expressed by equation (4) below. Formula 4: [VuVvVw]=[R+pLuMuvMwuMuvR+pLvMvwMwuMvwR+pLw][iuiviw]+[EuEvEw]

[0016] In the above equation, V u , V v and V w Voltages between terminals of the respective phases; indicate E u , E v and E w induced open circuit voltages of the respective phases; R represents the resistance of each of the phases; L u , L v and L w Self-inductances of the respective phases; give M uv, M vw or M wu Mutual inductances of uv, vw, and wu; and p is a differential operator with respect to time.

[0017] The voltages between terminals, the currents, and the induced open-circuit voltages each contain the fundamental frequency and harmonic components, and the harmonic components can be separated from the fundamental frequency components. Separating only the harmonic components from the voltage equation of equation (4) results in equation (5) below. Formula 5: [VuhVvhVwh]=[R+pLuMuvMwuMuvR+pLvMvwMwuMvwR+pLw][icycicycicyc]+[EuhEvhEwh]

[0018] In the above equation, V uh , V vh and V wh represent the harmonic components of the voltages between terminals of the respective phases; and give E uh , E vh and E whthe harmonic components of the induced open-circuit voltages of the respective phases.

[0019] Due to the configuration of a delta connection in which the three phases are connected in a circle, the delta connection is characterized by the fact that the voltages between terminals always sum to 0. That is, the following equation (6) applies. Formula 6: Vu+Vv+Vw=0

[0020] The relationship of equation (6) applies to both the fundamental frequency and the harmonics and thus equation (7) below applies. Formula 7: Vuh+Vvh+Vwh=0

[0021] Calculating the sum of the voltages between terminals of the respective phases using equation (5) results in equation (8) below. Formula 8: 0=3Ricyc+3plaicyc+(Euh+Evh+Ewh)

[0022] The parameter l arepresents a leakage inductance. Equation (8) is obtained using the relationship formulas from equation (9) below. Formula 9: Lu+Muv+Mwu=laLv+Muv+Mvw=laLw+Mwu+Mvw=la

[0023] Since E uh , E vh and E wh have phase differences of 120 degrees from each other, these sums have non-zero values ​​only at orders that are multiples of 3. This means that the equation (10) below is obtained. Formula 10: Euh+Evh+Ewh=3∑n=1∞E3nsin(3nωt+α3n)

[0024] The value n is an integer greater than or equal to 1; E 3n represents the amplitude of a 3n-th harmonic component of the induced open-circuit voltage; α 3nrepresents the phase of the 3n-order harmonic component of the induced open-circuit voltage; and ω represents the angular velocity as an electrical angle. Given the above, equation (8) can be more simply rewritten as equation (11) below. Formula 11: Ricyc+lα(picyc)+∑n=1∞E3nsin(3nθ+α3n)=0

[0025] By solving the differential equation of equation (11), the magnitude of the cyclic current can be obtained as equation (12) below. Formula 12: icyc=−∑n=1∞E3nR2+(3nωlα)2sin(3nωt+α3n−atan3nωlαR)

[0026] When the speed of the engine is high to a certain extent, ωl a generally larger than R, allowing the magnitude of the cyclic current to be approximated as equation (13) below. Formula 13: icyc∼∑n=1∞E3n3nωlαcos(3nθ+α3n)

[0027] The above shows that a low cyclic current can be achieved by reducing E 3n , which is the 3n-th order harmonic of the induced voltage, or by increasing l a , which is the leakage inductance, can be achieved.

[0028] The simplest method to increase the leakage inductance is to increase the number of turns of each coil. However, if the number of turns is increased, for example, by r times, the leakage inductance increases to r 2 -fold, but at the same time, the induced open-circuit voltage also increases by r-fold. This causes the magnitude of the cyclic current to decrease to approximately 1 / r-fold. However, since the magnitude of the torque ripple depends on the product of the induced voltage and the cyclic current, the magnitude of the torque ripple remains the same.

[0029] An object of the present disclosure is to increase the leakage inductance without changing the induced voltage. The following description describes a structure of a magnetic circuit in the stator that can increase the leakage inductance. The term leakage inductance refers to inductance generated due to a magnetic flux flowing back to the coil from which the magnetic flux originated, without passing through a coil of a different phase than the phase of the coil that generated this magnetic flux, among the magnetic fluxes generated by the coils of the phases U, V, and W.Accordingly, in order to increase the leakage inductance, it is desirable to reduce a magnetic flux passing through a coil of another phase and increase a magnetic flux flowing back to the coil from which the magnetic flux originates without passing through the coil of another phase among the magnetic fluxes generated by the coils of the phases of phase U, phase V, and phase W.

[0030] A process is described with reference to Fig. 5 for reducing a magnetic flux passing through a coil of another phase and increasing a magnetic flux flowing back to the coil from which the magnetic flux originates without passing through the coil of another phase, among the magnetic fluxes generated by the coils of the phases of phase U, phase V, and phase W. Fig. Fig. 5 is a schematic diagram illustrating the teeth of the stator 8 of the permanent magnet synchronous motor 50 according to the first embodiment. For ease of understanding, Fig. 5, the twelve teeth are shown as extending along a line. A coil is wound around each of the teeth, and the phases of the coils are, from left to right, U+, U-, W-, W+, V+, V-, U-, U+, W+, W-, V-, and V+. Among them, when viewing a tooth 21, which is the second tooth from the left, the magnetic flux generated by a coil wound around tooth 21 has a component that crosses the gap and interacts with the rotor, and in addition, a component flowing from the end portion of tooth 21 into the end portion of an adjacent tooth passes through the coil wound around the adjacent tooth, passes through the stack back portion, and then flows back to tooth 21 from which this component originates.

[0031] The magnetic fluxes relating to the tooth 21 include a magnetic flux passing through a closed magnetic circuit 13 passing through a tooth 22 of the same phase (hereinafter referred to as in-phase tooth 22) adjacent to the tooth 21, and a magnetic flux passing through a closed magnetic circuit 14 passing through a tooth 23 of a different phase (hereinafter referred to as out-of-phase tooth 23) adjacent to the tooth 21. In contrast to the closed magnetic circuit 14 contributing to both the self-inductance L u the phase U as well as the mutual inductance M UW between phase U and phase W, the closed magnetic circuit 13 only contributes to the self-inductance L uof phase U. Accordingly, the leakage inductance can be increased by increasing the magnetic flux passing through the closed magnetic circuit 13 and decreasing the magnetic flux passing through the closed magnetic circuit 14.

[0032] That is, there is a closed magnetic circuit in which a magnetic flux generated by a coil wound around one tooth of two adjacent specific teeth included in a plurality of teeth passes through end portions of the two teeth, passes through a coil wound around another tooth of the two teeth, passes through a stack back portion of each of the two teeth, and flows back to the coil wound around the one tooth that is the tooth from which the magnetic flux originates.In the closed magnetic circuit, by reducing the magnetic resistance of the closed magnetic circuit when the coils wound around these two adjacent teeth have the same phase to less than the magnetic resistance of the closed magnetic circuit when the coils wound around these two adjacent teeth have different phases, it is possible to increase the amount of leakage inductance. This then enables a reduction in the amount of cyclic current and the amount of torque ripple due to the cyclic current.The magnetic resistance of a magnetic circuit when the coils wound around two adjacent teeth have the same phase is hereinafter referred to as “magnetic resistance between in-phase coils” and the magnetic resistance of a magnetic circuit when the coils wound around two adjacent teeth have different phases is hereinafter referred to as “magnetic resistance between different-phase coils”.

[0033] Next, a concrete structure of the permanent magnet synchronous motor 50 is described, which causes the magnetic resistance between in-phase coils to be smaller than the magnetic resistance between different-phase coils.

[0034] Fig. Fig. 6 is a cross-sectional view illustrating a main portion of the teeth of the stator in an example of the permanent magnet synchronous motor 50 according to the first embodiment. For convenience of illustration, Fig. 6 only some teeth as extending along a line. Fig. Figure 6 illustrates only the three consecutive teeth 22, 21 and 23. Although in Fig. 6, the illustration of coils is omitted, a phase U coil is wound around the tooth 21 illustrated in the center, a phase U coil is wound around the tooth 22, which is one of the teeth adjacent to the tooth 21, and a phase W coil is wound around the tooth 23, which is another of the teeth adjacent to the tooth 21. The use of phase U and phase W as the combination of phases in the three teeth 21, 22, and 23 is merely an example. The use of a combination of U and V or a combination of V and W instead of the above combination is also easily applicable. What is important is that the tooth 21 and the tooth 22, which are adjacent to each other, have the same phase, and the tooth 21 and the tooth 23, which are adjacent to each other, have different phases.

[0035] The tooth 21 can be considered a combination of a stack back portion 211 connected to the teeth 22 and 23 on the side away from the rotor, a straight portion 212 extending from the stack back portion 211 toward the rotor in the radial direction, a flange portion 213a of the straight portion 212 extending circumferentially toward the in-phase tooth at the end closer to the rotor, and a flange portion 213b of the straight portion 212 extending circumferentially toward the out-of-phase tooth at the end closer to the rotor. However, it should be noted that the stack back portion 211, the straight portion 212, the flange portion 213a, and the flange portion 213b are merely terms for describing features of the shape of the tooth 21.The stack back portion 211, the straight portion 212, and the flange portions 213a and 213b of the tooth 21 do not necessarily have to be separate parts in reality. The tooth 21 may be configured as a one-piece component including the stack back portion 211, the straight portion 212, and the flange portions 213a and 213b joined together as a single piece, or may be configured such that the stack back portion 211, the straight portion 212, and the flange portions 213a and 213b are actually separate.

[0036] The flange portion closer to the in-phase tooth (hereinafter referred to as "on the in-phase side") has a circumferential direction length 31a that is longer than a circumferential direction length 31b of the flange portion closer to the other-phase tooth (hereinafter referred to as "on the other-phase side"). That is, the circumferential direction length of the flange portion located circumferentially from the end portion closer to the rotor of a specific tooth among the plurality of teeth in the direction of the in-phase tooth adjacent to the specific tooth may be longer than the circumferential direction length of the flange portion extending circumferentially from this end portion in the direction of the other-phase tooth adjacent to the specific tooth. The specific tooth is any tooth among the plurality of teeth.Such a configuration allows the magnetic resistance between in-phase coils to be smaller than the magnetic resistance between out-of-phase coils.

[0037] Fig. Fig. 7 is a cross-sectional view illustrating a main portion of the teeth of the stator in another example of the permanent magnet synchronous motor 50 according to the first embodiment. In the embodiment shown in Fig. 7, the flange portion 213a, which protrudes circumferentially, is provided on the side facing the in-phase tooth 22 adjacent to the tooth 21, while a cutout portion 31c is formed on the side facing the other-phase tooth 23 adjacent to the tooth 21, at the end of the straight portion 212 of the tooth 21. Such a configuration also allows the magnetic resistance between in-phase coils to be smaller than the magnetic resistance between other-phase coils. The use of the cutout portion 31c can be interpreted as a case where the circumferential direction length 31b of the flange portion is closer to the other-phase tooth in Fig. 6 has a negative value.

[0038] Fig. 8 is a cross-sectional view illustrating the main portion of the teeth of the stator in yet another example of the permanent magnet synchronous motor 50 according to the first embodiment. Tooth 21 is configured such that, on the in-phase side, a flange portion 31d is fitted to a flange portion 32e of the adjacent tooth 22, that is, a closed slot is formed, while on the out-of-phase side, a gap is formed between a flange portion 31e and a flange portion 33d of the adjacent tooth 23, that is, an open slot is formed. Such a configuration also allows the magnetic resistance between in-phase coils to be smaller than the magnetic resistance between out-of-phase coils.

[0039] In the first embodiment, as described above, there is provided a closed magnetic circuit in which a magnetic flux generated by a coil wound around one tooth of two adjacent concrete teeth included in a plurality of teeth passes through end portions of the two teeth, passes through a coil wound around another tooth of the two teeth, passes through a stack back portion of each of the two teeth, and flows back to the coil wound around the one tooth that is the tooth from which the magnetic flux originates.In the closed magnetic circuit, the magnetic resistance of the closed magnetic circuit when the coils wound around these two adjacent teeth have the same phase is smaller than the magnetic resistance of the closed magnetic circuit when the coils wound around these two adjacent teeth have different phases. This enables the permanent magnet synchronous motor 50 according to the first embodiment to reduce a cyclic current flowing in a delta connection and reduce torque ripple due to the cyclic current while minimizing the decrease in average torque.

[0040] The examples given in the first embodiment have another common feature regarding the volume of the teeth. As shown in Fig. As illustrated in Fig. 6, a line dividing the circumferential direction width of the straight portion of each of the teeth 21, 22, and 23 into equal halves is defined as a tooth center line 40, and a line dividing the tooth center lines 40 of two respective teeth adjacent to each other into equal halves in the circumferential direction angle is defined as a tooth boundary line 45. The total volume of the stack back portion, the straight portion, and the flange portions in a region surrounded by two of the tooth boundary lines 45 adjacent to each other can be interpreted as the volume of one tooth.Each of the examples in the first embodiment has a feature that, when one of two teeth adjacent to a specific tooth has a same phase and the other of the two teeth has a different phase, and the volume of the one specific tooth is divided into two portions at the tooth center line 40, the volume included in the portion closer to the adjacent in-phase tooth with respect to the tooth center line 40 of the volume of the one specific tooth is larger than the volume included in the portion closer to the adjacent different-phase tooth with respect to the tooth center line 40 of the volume of the one specific tooth.

[0041] That is, if one of two teeth adjacent to a specific tooth of a plurality of teeth has a phase equal to the phase of the specific tooth and the other of the two teeth adjacent to the specific tooth has a phase different from the phase of the specific tooth, the volume included in the section closer to the adjacent in-phase tooth with respect to the tooth center line 40 of the volume of the specific tooth is greater than the volume included in the section closer to the adjacent different-phase tooth with respect to the tooth center line 40 of the volume of the specific tooth. In particular, in the example of Fig. 6 the volume included in the portion closer to the adjacent in-phase tooth 22 with respect to the tooth centerline 40 of the volume of the tooth 21 is greater than the volume included in the portion closer to the adjacent out-of-phase tooth 23 with respect to the tooth centerline 40 of the volume of the tooth 21. Second embodiment.

[0042] In each of the examples given in the first embodiment, the distance between facing flange portions of respective adjacent teeth, i.e., a slot opening width, differs between the distance on the in-phase side and the distance on the different-phase side. A primary object of the present disclosure is to reduce a cyclic current and reduce a torque ripple due to the cyclic current. However, a difference in the slot opening width depending on the position results in a break in the rotational symmetry of the magnetic structure. This may result in a disadvantage such as an increase in the cogging torque under no load or an increase in the electromagnetic oscillation force under load.

[0043] In a second embodiment, all pairs of adjacent teeth in the plurality of teeth each have slot opening widths therebetween that are equal to each other. The second embodiment will be described below with respect to a configuration that provides a similar advantage to that described in the first embodiment while the slot opening widths on the in-phase side and on the opposite-phase side are equal to each other. In other words, a configuration will be described that enables a reduction of a cyclic current and a reduction of a torque ripple due to the cyclic current by making the magnetic resistance between in-phase coils smaller than the magnetic resistance between opposite-phase coils while making the slot opening widths for every two adjacent teeth among all the teeth equal to each other.

[0044] Fig. 9 is a cross-sectional view illustrating a main portion of the teeth of the stator in the permanent magnet synchronous motor according to the second embodiment. The tooth 21 is configured such that, in the circumferentially projecting flange portions, a radial height 31f in an edge portion farthest from the straight portion on the in-phase side is greater than a radial height 31g in an edge portion on the opposite-phase side, and a radial height 31h in a root portion on the in-phase side is greater than a radial height 31j in a root portion on the opposite-phase side. Moreover, the radial height 31f in the edge portion on the in-phase side is greater than the radial height 31j in the root portion on the opposite-phase side.That is, in the second embodiment, the height in the radial direction of the flange portion, which extends circumferentially from the end portion closer to the rotor, of a specific tooth of the plurality of teeth toward the in-phase tooth adjacent to the specific tooth is greater than the height in the radial direction of the flange portion, which extends circumferentially from this end portion toward the opposite-phase tooth adjacent to the specific tooth. The specific tooth is any tooth among the plurality of teeth. The root portions each form a boundary between the straight portion and a flange portion. Such a configuration also enables the magnetic resistance between in-phase coils to be smaller than the magnetic resistance between opposite-phase coils.

[0045] Fig. 9 illustrates an example where the height in the edge portion and the height in the foot portion of the flange portion on the in-phase side are each larger than the respective corresponding heights on the opposite-phase side. As similar examples, a configuration where the height in the edge portion of the flange portion on the in-phase side is still larger than the corresponding height on the opposite-phase side, but the height in the foot portion of the flange portion on the in-phase side is equal to the corresponding height on the opposite-phase side, also allows the magnetic resistance between in-phase coils to be smaller than the magnetic resistance between opposite-phase coils.A configuration in which the height in the foot portion of the flange portion on the in-phase side is still greater than the corresponding height on the other-phase side, but the height in the edge portion of the flange portion on the in-phase side is equal to the corresponding height on the other-phase side, also allows the magnetic resistance between in-phase coils to be smaller than the magnetic resistance between other-phase coils. Third embodiment.

[0046] Fig. 10 is a cross-sectional view illustrating a main portion of the teeth of the stator in the permanent magnet synchronous motor according to a third embodiment. The core back portion 211 of the tooth 21 has a radial direction thickness 34a in a portion adjacent to the in-phase tooth 22 that is larger than a radial direction thickness 34b in a portion adjacent to the out-of-phase tooth 23. That is, in the third embodiment, a radial direction thickness of the core back portion between a specific tooth of the plurality of teeth and the in-phase tooth adjacent to the specific tooth is larger than a radial direction thickness of the core back portion between the specific tooth and the out-of-phase tooth adjacent to the specific tooth. The specific tooth is any tooth among the plurality of teeth.Such a configuration also allows the magnetic resistance between in-phase coils to be smaller than the magnetic resistance between out-of-phase coils. Fourth embodiment.

[0047] Providing a magnetic resistance-increasing portion in a portion of the closed magnetic circuit on the opposite-phase side also makes it possible to make the magnetic resistance between in-phase coils smaller than the magnetic resistance between opposite-phase coils. Examples of how the magnetic resistance between in-phase coils is made smaller than the magnetic resistance between opposite-phase coils by providing a magnetic resistance-increasing portion will be described sequentially in fourth to sixth embodiments.

[0048] Fig. 11 is a cross-sectional view illustrating a main portion of the teeth of the stator in the permanent magnet synchronous motor according to the fourth embodiment. A spacer 41, which is a magnetic resistance increasing portion, is interposed between the core back portion 211 of the tooth 21 and a core back portion 231 of the opposite-phase tooth 23 adjacent to the tooth 21. There is no spacer between the core back portion 211 and a core back portion 221 of the same-phase tooth 22 adjacent to the tooth 21. Therefore, the core back portion 211 and the core back portion 221 are in direct contact with each other. The core back portion 211 has a circumferential direction length reduced by the circumferential direction length of the spacer 41.The spacer 41 is formed of a non-magnetic material or a material having a magnetic resistance higher than the magnetic resistance of the stator core. The spacer 41 is formed, for example, by using a plastic, a resin, a magnetic paste, or the like. That is, the permanent magnet synchronous motor according to the fourth embodiment includes a spacer disposed between the core back portion of a specific tooth among the plurality of teeth and the core back portion of the opposite-phase tooth adjacent to the specific tooth, the spacer having a magnetic permeability lower than the magnetic permeability of the material of each of the plurality of teeth. Such a configuration also enables the magnetic resistance between in-phase coils to be smaller than the magnetic resistance between opposite-phase coils.

[0049] Furthermore, as a similar example to the fourth embodiment, a configuration may be used in which a spacer is interposed not only between the stack back portion of a specific tooth and the stack back portion of the other-phase tooth adjacent to the specific tooth, but also between the stack back portion of the specific tooth and the stack back portion of the in-phase tooth adjacent to the specific tooth, and the circumferential direction length of the spacer on the in-phase side is smaller than the circumferential direction length of the spacer on the other-phase side. Fifth embodiment.

[0050] Fig. 12 is a cross-sectional view illustrating a main portion of the teeth of the stator in an example of the permanent magnet synchronous motor according to a fifth embodiment. A groove portion 42 is formed in the end portion closer to the rotor of each of the teeth 21, 22, and 23. The groove portion 42 of the tooth 21 is formed such that the center thereof is located at a position closer to the other-phase tooth 23 adjacent to the tooth 21 with respect to the tooth center line 40 positioned at the circumferential center of the straight portion 212 of the tooth 21. The groove portion 42 of each of the teeth 22 and 23 is also formed such that the center thereof is located at a position closer to the adjacent other-phase tooth with respect to the tooth center line 40 positioned at the circumferential center of the corresponding one of the straight portions 222 and 232.That is, in the fifth embodiment, the groove portion 42 is formed in each of the plurality of teeth, and the center point of the groove portion 42 is positioned at a position closer to the opposite-phase tooth adjacent to a specific tooth where the groove portion 42 is formed with respect to the tooth center line 40 positioned at the center of the circumferential width of the straight portion of the specific tooth. The specific tooth is any tooth among the plurality of teeth. Such a configuration also allows the magnetic resistance between in-phase coils to be smaller than the magnetic resistance between opposite-phase coils.

[0051] Fig. 12 illustrates an example in which the groove portion 42 is positioned at a position on the boundary between the straight portion and a flange portion. However, if the center point of the groove portion 42 is positioned at a position closer to the adjacent other-phase tooth with respect to the tooth centerline 40, the groove portion 42 may be positioned either in the straight portion or in the flange portion. Fig. 12 illustrates an example in which the groove portion 42 has an opening on the rotor side of the end of each of the teeth 21, 22 and 23, however, the groove portion 42 may have an opening toward the coil slot, or the groove portion 42 may be replaced by a cavity portion having no opening.

[0052] Fig. 13 is a cross-sectional view illustrating a main portion of the teeth of the stator in another example of the permanent magnet synchronous motor according to the fifth embodiment. The groove portion 42 is formed in a portion facing the coil slot of each of the stack back portions 211, 221, and 231 of the teeth 21, 22, and 23. The center point of the groove portion 42 is positioned at a position closer to the adjacent different-phase tooth with respect to the tooth center line 40, which is positioned in the circumferential direction center, of the straight portion. Specifically, the center point of the groove portion 42 formed on the tooth 21 is positioned at a position closer to the different-phase tooth 23 adjacent to the tooth 21 with respect to the tooth center line 40, which is positioned in the circumferential direction center, of the straight portion 212.Such a configuration also allows the magnetic resistance between in-phase coils to be smaller than the magnetic resistance between out-of-phase coils. Forming the groove portion 42 in a portion facing the coil slot of each of the stack back portions 211, 221, and 231 provides a secondary advantage of allowing the groove portion 42 to be used as a winding area.

[0053] Fig. 14 is a cross-sectional view illustrating a main portion of the teeth of the stator in another example of the permanent magnet synchronous motor according to the fifth embodiment. The groove portion 42 is formed in an outer peripheral portion of each of the stack back portions 211, 221, and 231 of the teeth 21, 22, and 23. The center of the groove portion 42 is located at a position closer to the adjacent different-phase tooth with respect to the tooth center line 40, which is positioned in the circumferential direction center, of the straight portion. Specifically, the center of the groove portion 42 formed on the tooth 21 is located at a position closer to the different-phase tooth 23 adjacent to the tooth 21 with respect to the tooth center line 40, which is positioned in the circumferential direction center, of the straight portion 212.Such a configuration also allows the magnetic resistance between in-phase coils to be smaller than the magnetic resistance between opposite-phase coils. The formation of the groove portion 42 in an outer peripheral portion of each of the stack back portions 211, 221, and 231 provides a secondary advantage of allowing the groove portion 42 to be used as a positioning or fixing groove in the assembly process, such as stacking magnetic steel sheets, which are materials of the teeth 21, 22, and 23, or inserting the teeth 21, 22, and 23 into the frame.

[0054] In the examples of Fig. 13 and Fig. 14, the formation of a cavity portion having no opening instead of the groove portion 42 in each of the package back portions 211, 221 and 231 also enables the magnetic resistance between in-phase coils to be smaller than the magnetic resistance between different-phase coils. Sixth embodiment.

[0055] Fig. 15 is a cross-sectional view illustrating a main portion of the teeth of the stator in the permanent magnet synchronous motor according to a sixth embodiment. The tooth 21 is formed by caulking. Caulking portions 44 include a caulking portion positioned closer to the in-phase tooth 22 adjacent to the tooth 21 with respect to the tooth centerline 40, a caulking portion positioned closer to the out-of-phase tooth 23 adjacent to the tooth 21 with respect to the tooth centerline 40, and a caulking portion positioned on the tooth centerline 40.Considering the entire tooth 21, the area of ​​the portions positioned closer to the other-phase tooth 23 adjacent to the tooth 21 with respect to the tooth center line 40, of the total area of ​​all the caulking portions 44, is larger than the area of ​​the portions positioned closer to the in-phase tooth 22 adjacent to the tooth 21 with respect to the tooth center line 40, of the total area of ​​all the caulking portions 44.That is, in the sixth embodiment, a specific tooth among the plurality of teeth includes one or more caulking portions 44, and the total area of ​​the caulking portions 44 included in the portion closer to the other-phase tooth adjacent to the specific tooth with respect to the tooth center line 40, which is positioned at the center of the circumferential direction width of the straight portion, of the specific tooth is larger than the total area of ​​the caulking portions 44 included in the portion closer to the in-phase tooth adjacent to the specific tooth with respect to the tooth center line 40 of the specific tooth. The specific tooth is any tooth among the plurality of teeth. Such a configuration also enables the magnetic resistance between in-phase coils to be smaller than the magnetic resistance between other-phase coils. Seventh embodiment.

[0056] Fig. 16 is a cross-sectional view illustrating a main portion of the teeth of the stator in the permanent magnet synchronous motor according to a seventh embodiment. In the seventh embodiment, an additional magnetic member 43 is disposed between the flange portions positioned adjacent to each other between the tooth 21 and the tooth 22 of a same phase. The additional magnetic member 43 has a shape elongated along the rotational axis direction of the motor, such as a cylindrical shape or a prismatic shape. The additional magnetic member 43 may be a rod-shaped member formed of a single magnetic body or may be a stack of steel sheets stacked along the axial direction.In any of these cases, the permanent magnet synchronous motor according to the seventh embodiment includes the additional magnetic element 43 so as to be positioned in a space between a flange portion of a specific tooth among the plurality of teeth and a flange portion of the in-phase tooth adjacent to the specific tooth. The specific tooth is any tooth among the plurality of teeth. Such a configuration causes a closed magnetic circuit to be created in which a magnetic flux flows more easily from a flange portion of the tooth 21 to a flange portion of the in-phase tooth 22 adjacent to the tooth 21 via the additional magnetic element 43, and allows the magnetic resistance between in-phase coils to be smaller than the magnetic resistance between out-of-phase coils.In order to form an effective closed magnetic circuit, the center of the additional magnetic element 43 is desirably positioned between a straight line 431 and a straight line 432, the straight line 431 connecting end portions 331 each closer to the coil in the radial direction at a root of the flange portion facing the adjacent in-phase tooth, and the straight line 432 connecting end portions 332 each closer to the rotor in the radial direction at a root of such a flange portion of a corresponding one of the tooth 21 and the tooth 22 of a same phase that are adjacent to each other. Eighth embodiment.

[0057] Fig. 17 is a three-dimensional view illustrating a main portion of a tooth of the stator in the permanent magnet synchronous motor according to an eighth embodiment. Fig. Figure 17 schematically illustrates a situation of two magnetic steel plates stacked on top of each other to form a single tooth. Although not illustrated, a tooth in phase with the tooth of Fig. 17 adjacent in the direction indicated by “A” in Fig. 17, and is a different phase tooth to the tooth from Fig. 17 adjacent in the direction indicated by “B” in Fig. 17. The tooth includes two pieces, i.e., an upper-stage piece and a lower-stage piece, which are separated in the rotation axis direction. The upper-stage piece and the lower-stage piece have different shapes in the flange portion of the tooth. In the upper-stage piece, the flange portion on the in-phase side has a circumferential direction length 311a that is longer than a circumferential direction length 311b of the flange portion on the other-phase side. In the lower-stage piece, the flange portion on the in-phase side has a circumferential direction length 312a that is equal to a circumferential direction length 312b of the flange portion on the other-phase side. Such a configuration also enables the magnetic reluctance between in-phase coils to be smaller than the magnetic reluctance between other-phase coils.

[0058] By providing a set, an advantage can be expected that a cogging torque and an electromagnetic vibration force are reduced. Fig. 17 illustrates an example in which the flange portions on the in-phase side and on the out-of-phase side of the upper stage portion of a two-stage set have different circumferential direction lengths from each other. Furthermore, a tooth having the feature described in each of the second to sixth embodiments provides an advantage similar to the advantage provided in each of the second to sixth embodiments. Fig. 17 illustrates a tooth having a set that is a two-stage set, however, a tooth may have a three- or more-stage set, of which one stage has the feature, or two or more stages have the feature, that the magnetic resistance between in-phase coils is smaller than the magnetic resistance between opposite-phase coils. The set may be a continuous set in which the shape of the tooth changes continuously, and the tooth may have the feature that the magnetic resistance between in-phase coils is smaller than the magnetic resistance between opposite-phase coils at least in a partial section in the rotation axis direction. The aforementioned continuous set is an oblique set.

[0059] That is, a specific tooth among the plurality of teeth may have an interlaced structure that differs from continuous to discontinuous depending on its position in the rotation axis direction. The specific tooth is any tooth among the plurality of teeth. In this case, at least in a partial region in the rotation axis direction, the magnetic reluctance of a closed magnetic circuit when coils wound around two adjacent teeth, including the specific tooth among the plurality of teeth, have the same phase is smaller than the magnetic reluctance of a closed magnetic circuit when coils wound around these two teeth have different phases.

[0060] Two or three or more elements in the examples given in the first to eighth embodiments can be easily implemented in combination.

[0061] As described, the first embodiment has a common feature that, when a tooth is divided into two sections at the tooth centerline 40, the volume included in the section closer to the adjacent in-phase tooth with respect to the tooth centerline 40 is larger than the volume included in the section closer to the adjacent out-of-phase tooth with respect to the tooth centerline 40. The characteristic that the volume included in the section closer to the adjacent in-phase tooth with respect to the tooth centerline 40 is larger than the volume included in the section closer to the adjacent out-of-phase tooth with respect to the tooth centerline 40 is hereinafter described as "the volume on the in-phase side is larger than the volume on the out-of-phase side."The above feature is also applicable to all of the examples described in the second to fifth embodiments and the eighth embodiment. The feature is also applicable to the sixth embodiment in which the volume on the in-phase side is larger than the volume on the out-of-phase side when the volume of the caulking portions 44 in the original tooth volume is ignored and the volume of the portion without the caulking portions 44 is considered as the effective tooth volume, because the caulking portions 44 reduce the fundamental role of the tooth as a magnetic conductor for forming a closed magnetic circuit for passing magnetic flux therethrough.The feature is also applicable to the seventh embodiment in which the volume on the in-phase side is larger than the volume on the out-of-phase side when the volume of the additional magnetic element 43 is considered as a part of the volume of the corresponding teeth, because the additional magnetic element 43 is a component having a role equal to the basic role of the teeth as a magnetic conductor for forming a closed magnetic circuit for passing a magnetic flux therethrough.

[0062] The second embodiment has been described with reference to an advantage of equalizing the slot opening widths on the in-phase side and the out-of-phase side. Making all slot opening widths equal to each other is easy to implement in each of the examples of the third to seventh embodiments, similar to the second embodiment, regardless of whether two adjacent teeth have the same phase or different phases.

[0063] In motor design, a tapered tooth structure is often selected to, for example, mitigate magnetic saturation in tooth portions, increase the wire fill factor in the coil slot area, or the like. In the tapered tooth structure, the circumferential direction width of the straight portion of each tooth changes along the radial direction. The features of the present disclosure are applicable to a permanent magnet synchronous motor having a tapered tooth structure, an example of which is described in Fig. 18 is illustrated. Fig. 18 is a cross-sectional view illustrating a main portion of the stator teeth used in a permanent magnet synchronous motor with a tapered tooth structure. The teeth 21, 22, and 23 have a tapered shape in which the circumferential width of the straight portion gradually decreases in a direction from the outer circumference to the inner circumference. The circumferential length 31a of the flange portion on the in-phase side is longer than the circumferential length 31b of the flange portion on the opposite-phase side. Thus, even a permanent magnet synchronous motor with a tapered tooth structure can make the magnetic resistance between in-phase coils smaller than the magnetic resistance between opposite-phase coils.The circumferential length of a flange portion can be defined, for example, as the distance in the circumferential direction from the end portion closest to the outer circumference at the base of the flange portion to the edge portion of the flange portion. The tooth centerline 40 can be defined as the straight line that divides the adjacent boundaries facing the coil slot into equal halves of the angle.

[0064] With reference to Fig.In FIG. 18, an example was described in which a permanent magnet synchronous motor with a tapered tooth structure employs a configuration in which the flange portions on the in-phase side and on the other-phase side have different circumferential direction lengths from each other, as described in the first embodiment. Obviously, the use of any of the configurations described in the second to eighth embodiments or a combination of two or more of the configurations described in the first to eighth embodiments in a tapered tooth structure also provides an advantage similar to that provided in the first embodiment. A common feature is also applicable to the tapered tooth structure, namely that the volume on the in-phase side is larger than the volume on the other-phase side.

[0065] The examples of the above embodiments were each described using a surface permanent magnet synchronous motor (SPMSM) as an example, which includes permanent magnets mounted on the outer peripheral surface of the rotor. An interior permanent magnet synchronous motor (IPMSM) including permanent magnets installed inside the rotor also provides an advantage similar to those provided in the above embodiments.

[0066] In all of the examples of the embodiments described above, the motor has 10 poles and 12 slots. Combinations of a different number of poles and a different number of slots are also contemplated below. For example, if the motor has 8 poles and 12 slots, the coils wound around the 12 teeth are arranged in the phase order of U+, W+, V+, U+, W+, U+, W+, V+, U+, W+, W+, and V+. Any two adjacent teeth have different phases, that is, there is no adjacent tooth in phase. Therefore, the present disclosure is not applicable. In contrast, if, for example, the motor has 8 poles and 9 slots, the coils wound around the 9 teeth are arranged in the phase order of U+, U-, U+, W+, W+, W+, V+, V-, and V+.Some pairs of two adjacent teeth have the same phase and some pairs have different phases, which is why the present disclosure is applicable.

[0067] In general, it is known that when a motor having a concentrated winding configuration has a ratio of the number of poles to the number of slots of 3m±1:3m, where m is an integer greater than or equal to 2, the sequence of phases of the coils in the stator includes m consecutive in-phase coils. That is, some pairs of two adjacent teeth have the same phase, and some pairs thereof have different phases, thereby allowing the present disclosure to be applied to a motor having a ratio of the number of poles to the number of slots of 3m±1:3m, where m is an integer greater than or equal to 2.

[0068] This is not limited to the case where the ratio of the number of poles to the number of slots is 3m±1:3m. It is known that the sequence of phases of the coils in the stator between when P=Sk and when P=S+k is generally simply opposite, where P is the number of poles, S is the number of slots, and k is an integer greater than or equal to 1. When these sequences include two adjacent teeth with the same phase and two adjacent teeth with different phases, it is believed that the application of the present disclosure will not result in any significant difference between when P=Sk and when P=S+k with respect to the effect of increasing the leakage inductance from the perspective of a closed magnetic circuit in the stator.However, as expressed by equation (12), the magnitude of the cyclic current with an order of 3n is expressed by the ratio between the magnitude of the 3n-th order harmonic of the induced voltage and the impedance in the electrical circuit in a delta connection, that is, by the following equation (14). Formula 14: Ratio=E3n / R2+(3nωla)2

[0069] E 3n is proportional to the electrical angular velocity ω. Thus, although the magnitude of the cyclic current at a sufficiently high speed is only slightly dependent on ω, since R is R«3nωl a can be considered, the magnitude of the cyclic current is positive with ω at a low speed, when the magnitude of R with respect to 3nωl ais not negligible. For a given mechanical speed, a higher number of poles results in a higher electrical angular velocity ω. Accordingly, by comparing when P=Sk and when P=S+k, the magnitude of the cyclic current, particularly at a low speed, can be lower in the case of P=Sk, i.e., a case of a lower number of poles, in other words, a case where the number of poles is smaller than the number of slots, and this case is therefore more suitable.

[0070] The configurations described in the above embodiments are merely examples. These configurations may be combined with other known techniques, and configurations of different embodiments may be combined with each other. Furthermore, some of such configurations may be omitted or modified without deviating from their essence. List of reference symbols

[0071] 1 coil; 2 stator core; 2T, 21, 22, 23 tooth; 3 rotor core; 4 permanent magnet; 5 rotation sensor; 6 frame; 7 shaft; 8 stator; 9 rotor; 10 current from phase U; 11 current from phase V; 12 current from phase W; 13, 14 closed magnetic circuit; 31f height in the radial direction in the edge section on the in-phase side; 31g height in the radial direction in the edge section on the other-phase side; 31h height in the radial direction in the root section on the in-phase side; 31j height in the radial direction in the root section on the other-phase side; 34a thickness in the radial direction of the section adjacent to the in-phase tooth; 34b thickness in the radial direction of the section adjacent to the other-phase tooth; 31a circumferential direction length of the flange section on the in-phase side; 31b Circumferential length of the flange portion on the opposite phase side; 31d, 31e, 32e, 33d, 213a, 213b Flange portion; 31c Cut-out portion; 40 Tooth centerline; 41 Spacer;42 groove portion; 43 additional magnetic element; 44 caulking portion; 45 tooth boundary line; 50 permanent magnet synchronous motor; 211, 221, 231 core back portion; 212, 222, 232 straight portion; 311a, 312a circumferential direction length of the flange portion on the in-phase side; 311b, 312b circumferential direction length of the flange portion on the opposite-phase side; 331 end portion closer to the coil in the radial direction at the base of the flange portion; 332 end portion closer to the rotor in the radial direction at the base of the flange portion; 431, 432 straight; QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2005-348522

[0003] JP 2008-301652

[0003]

Claims

[1] Permanent magnet synchronous motor, comprising: a stator; a plurality of teeth arranged equiangularly on the stator; and Coils wound in a concentrated winding manner around the plurality of respective teeth, wherein the coils form a three-phase delta connection, wherein in a closed magnetic circuit in which a magnetic flux generated by a coil wound around one tooth of two mutually adjacent specific teeth included in the plurality of teeth passes through end portions of the two specific teeth, passes through a coil wound around another tooth of the two specific teeth, passes through a stack back portion of each of the two specific teeth, and flows back to the coil wound around the one tooth, a magnetic resistance of the closed magnetic circuit when the coils wound around the two specific teeth have the same phase is smaller than a magnetic resistance of the closed magnetic circuit when the coils wound around the two specific teeth have different phases. [2] A permanent magnet synchronous motor according to claim 1, wherein a ratio of a number of poles to a number of slots is 3m±1:3m, where m is an integer greater than or equal to 2. [3] A permanent magnet synchronous motor according to claim 1, wherein a number of poles is smaller than a number of slots. [4] A permanent magnet synchronous motor according to claim 1, wherein pairs of adjacent teeth in the plurality of teeth have slot opening widths between the respective pairs, the slot opening widths being equal to each other in all of the pairs. [5] Permanent magnet synchronous motor according to one of claims 1 to 4, wherein one of two teeth adjacent to a specific tooth among the plurality of teeth has a phase the same as a phase of the specific tooth, and another of the two teeth adjacent to the specific tooth has a phase different from the phase of the specific tooth, and a volume included in a portion closer to the tooth having a same phase adjacent to the specific tooth with respect to a tooth centerline, of a volume of the specific tooth is larger than a volume included in a portion closer to the tooth having a different phase adjacent to the specific tooth with respect to the tooth centerline, of the volume of the specific tooth. [6] Permanent magnet synchronous motor according to one of claims 1 to 3, wherein a specific tooth among the plurality of teeth includes a flange portion that extends circumferentially from an end portion closer to a rotor toward a tooth having a same phase adjacent to the specific tooth, and a flange portion that extends circumferentially from the end portion toward a tooth having a different phase adjacent to the specific tooth, and the flange portion that extends circumferentially toward the tooth having a same phase has a circumferential direction length that is longer than a circumferential direction length of the flange portion that extends circumferentially toward the tooth having a different phase, and the concrete tooth is any tooth among the multitude of teeth. [7] Permanent magnet synchronous motor according to one of claims 1 to 4, wherein a specific tooth among the plurality of teeth includes a flange portion that extends circumferentially from an end portion closer to a rotor toward a tooth having a same phase adjacent to the specific tooth, and a flange portion that extends circumferentially from the end portion toward a tooth having a different phase adjacent to the specific tooth, and the flange portion that extends circumferentially toward the tooth having a same phase has a height in the radial direction that is greater than a height in the radial direction of the flange portion that extends circumferentially toward the tooth having a different phase, and the concrete tooth is any tooth among the multitude of teeth. [8] Permanent magnet synchronous motor according to one of claims 1 to 4, wherein a stack back portion between a specific tooth among the plurality of teeth and a tooth having a same phase adjacent to the specific tooth has a thickness in the radial direction that is greater than a thickness in the radial direction of a stack back portion between the specific tooth and a tooth having a different phase adjacent to the specific tooth, and the concrete tooth is any tooth among the multitude of teeth. [9] Permanent magnet synchronous motor according to one of claims 1 to 4, further comprising: a spacer interposed between a stack back portion of a specific tooth among the plurality of teeth and a stack back portion of a tooth having a different phase adjacent to the specific tooth, the spacer having a magnetic permeability lower than the magnetic permeability of material of each of the plurality of teeth. [10] Permanent magnet synchronous motor according to one of claims 1 to 4, wherein a groove portion or a cavity portion is formed in each of the plurality of teeth, and the groove portion or the cavity portion has a center point, the center point being positioned at a position closer to a tooth having a different phase with respect to a tooth center line, the tooth center line being positioned at a center of a circumferential width of a straight portion of a specific tooth in which the groove portion or the cavity portion is formed, the tooth having a different phase being adjacent to the specific tooth, and the concrete tooth is any tooth among the multitude of teeth. [11] Permanent magnet synchronous motor according to one of claims 1 to 4, further comprising: an additional magnetic element positioned in a space between a flange portion of a specific tooth among the plurality of teeth and a flange portion of a tooth having a same phase adjacent to the specific tooth, wherein the concrete tooth is any tooth among the multitude of teeth. [12] Permanent magnet synchronous motor according to one of claims 1 to 4, wherein a specific tooth among the plurality of teeth includes one or more caulking sections, a total area of ​​the caulking portions included in a portion closer to a tooth having a different phase adjacent to the specific tooth with respect to a tooth centerline of the specific tooth is larger than a total area of ​​the caulking portions included in a portion closer to a tooth having a same phase adjacent to the specific tooth with respect to the tooth centerline of the specific tooth, wherein the tooth centerline is positioned at a center of a circumferential width of a straight portion of the specific tooth, and the concrete tooth is any tooth among the multitude of teeth. [13] Permanent magnet synchronous motor according to one of claims 1 to 3, wherein a specific tooth among the plurality of teeth has an interlaced structure, wherein the interlaced structure differs from continuous to non-continuous depending on a position in a rotational axis direction, the concrete tooth is any tooth among the plurality of teeth and at least in a partial region in the rotation axis direction, a magnetic resistance of the closed magnetic circuit when coils wound around two adjacent teeth, including the specific tooth among the plurality of teeth, have the same phase is smaller than a magnetic resistance of the closed magnetic circuit when coils wound around these two teeth have different phases.

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