Rotating electric machine and method for manufacturing the same

Abstract

A rotary electrical machine (1) according to the present disclosure comprises: a stator (2) having a stator winding portion, in which a stator winding (3) is wound around a stator core (4), with the stator winding projecting from the stator core in an axial direction; a rotor (5) disposed spaced apart from the stator; a shaft (6) provided at the center of the rotor; bearings (7, 8) that rotatably support the shaft; a molding material (11) which is a resin material and which integrally forms the stator winding and the stator core; and a conductive member (12) that is electrically continuous with the bearings, that is provided, inside the molding material, at a position where at least a portion thereof faces the stator winding portion, and that forms electrostatic capacitance between the conductive member and the stator winding portion.

Description

[Technical field]

[0001] The present disclosure relates to a rotating electric machine and a method for manufacturing a rotating electric machine. [Background technology]

[0002] Conventionally, a method of driving a rotating electric machine using a power converter such as an inverter has been used to control the rotation speed of the rotating electric machine. A voltage-type PWM (Pulse Width Modulation) inverter is well known as a driving method using an inverter. In this type of method, a rectangular voltage pulse train having a constant carrier period and a pulse width proportional to a modulated sine wave signal is applied to the rotating electric machine, and the rotating electric machine is driven so that the current flowing through the stator winding of the rotating electric machine becomes a sine wave with a frequency equal to the frequency of the modulated sine wave signal.

[0003] With the recent development of power semiconductor elements, the carrier frequency of voltage-type PWM inverters has become higher, and therefore, when a drive method using an inverter is used, a high-frequency voltage is generated due to the switching of the inverter. This high-frequency voltage is, for example, a high-frequency voltage (shaft voltage) caused by a potential difference generated between the outer and inner rings of a bearing by voltage division by the electrostatic capacitance inside the rotating electric machine. When this shaft voltage exceeds the dielectric breakdown voltage of the lubricant of the bearing, a high-frequency current (shaft current) flows between the outer and inner rings. When the shaft current flows, corrosion called electrolytic corrosion occurs on the inner and outer raceways of the bearing and on the rolling surfaces of the bearing balls, which deteriorates the durability of the bearing. Therefore, in a rotating electric machine driven by an inverter, it is necessary to reduce the shaft voltage in order to suppress malfunctions caused by electrolytic corrosion.

[0004] In Patent Document 1, an impedance adjusting member is provided to adjust at least one of the impedances between the stator winding and the inner ring of the bearing and the impedance between the stator winding and the outer ring of the bearing. In this motor, a capacitor, which is a dielectric element, is electrically connected between the stator winding and the inner ring of the bearing or between the stator winding and the outer ring of the bearing, and in order to make this connection, a through hole is provided by cutting a part of the molding material located on the side of the stator winding. This process exposes the stator winding, and one end of the capacitor is connected to the part of the stator winding exposed through the through hole. The other end of the capacitor is connected to the inner ring of the bearing or the outer ring of the bearing, and this configuration adjusts the impedance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2009 / 001546 Summary of the Invention [Problem to be solved by the invention]

[0006] In such an electric motor, problems caused by electrolytic corrosion of the bearing can be suppressed by adjusting at least one of the impedances between the stator winding and the inner ring of the bearing and the impedance between the stator winding and the outer ring of the bearing. However, since a through hole is provided by cutting a part of the molding material, there is a problem that the manufacturing process becomes complicated.

[0007] The present disclosure has been made to solve such problems, and aims to provide a rotating electric machine and a method for manufacturing a rotating electric machine that can prevent electrolytic corrosion from occurring in bearings and prevent the manufacturing work from becoming complicated. [Means for solving the problem]

[0008] The rotating electric machine according to the present disclosure includes a stator having a stator winding wound around a stator core, the stator winding having a stator winding portion protruding from the stator core in the axial direction, a rotor disposed inside the stator with a gap therebetween, a shaft provided in the center of the rotor, a bearing for rotatably supporting the shaft, and a molding material which is a resin material that integrally molds the stator winding and the stator core; a circuit board that is provided inside the molding material and controls the current supply to the stator winding; and a coil that is provided separately from the circuit board. Conductive with the bearing, inside the mold material A little At least a part of the wire is positioned opposite the stator winding. Apart from the stator windings It is provided, The shaft voltage generated during rotation must not exceed the dielectric breakdown voltage of the lubricant inside the bearing. Capacitance Between the stator winding and a conductive member formed on the substrate. In addition, the rotating electric machine according to the present disclosure includes a stator having a stator winding wound around a stator core, the stator winding having a stator winding portion protruding axially from the stator core, a rotor arranged at a distance inside the stator, a shaft provided in the center of the rotor, a bearing for rotatably supporting the shaft, a molding material which is a resin material that integrally molds the stator winding and the stator core, a circuit board having a plurality of conductive patterns and capacitors connected between the conductive patterns, and a conductive member that is molded integrally with at least one conductive pattern and is conductive to the bearing, and is provided inside the molding material at a position at least partially facing the stator winding portion, away from the stator winding, and forms a capacitance between the stator winding portion such that the axial voltage generated during rotation is less than the breakdown voltage of the lubricant that lubricates the bearing.

[0009] A method for manufacturing a rotating electric machine according to the present disclosure includes the steps of winding a stator winding around a stator core to form a stator having a stator winding portion in which the stator winding protrudes in an axial direction from the stator core; disposing a circuit board inside the molding material, the circuit board controlling the current supply to the stator winding; a bearing is disposed, the bearing is electrically connected to the bearing, and at least a portion of the bearing faces the stator winding portion; Away from the stator winding, the shaft voltage generated during rotation is kept from exceeding the dielectric breakdown voltage of the lubricant inside the bearing. Capacitance Between the stator winding Formation , which is separate from the circuit board The method includes the steps of providing a conductive member, integrally molding the stator and the conductive member with a molding material, and arranging the rotor and the shaft inside the stator with a gap therebetween. Effect of the Invention

[0010] In the rotating electric machine according to the present disclosure, the conductive member is electrically connected to the bearing, and is provided inside the molding material at a position where at least a portion of the conductive member faces the stator winding portion, forming a capacitance between the conductive member and the stator winding portion, thereby making it possible to prevent electrolytic corrosion from occurring in the bearing and to prevent the manufacturing process from becoming complicated.

[0011] In addition, according to the manufacturing method for a rotating electric machine disclosed herein, a conductive member is provided so that at least a portion of it faces the stator winding portion and a capacitance is formed between it and the stator winding portion, and then the stator and the conductive member are integrally molded with a molding material, thereby preventing electrolytic corrosion from occurring in the bearings and preventing the manufacturing work from becoming complicated. [Brief description of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view showing a structure of a rotating electric machine according to a first embodiment of the present disclosure. [Diagram 2] 1 is a schematic circuit diagram of a rotating electric machine according to a first embodiment of the present disclosure. [Diagram 3] 1 is a circuit diagram showing capacitances between components of a rotating electric machine according to a first embodiment of the present disclosure. [Figure 4] 5 is a flowchart showing a method for manufacturing the rotating electric machine according to the first embodiment of the present disclosure. [Diagram 5] FIG. 11 is a cross-sectional view showing the structure of a rotating electric machine according to a second embodiment of the present disclosure. [Figure 6] FIG. 11 is a cross-sectional view showing the structure of a rotating electric machine according to a third embodiment of the present disclosure. [Figure 7] FIG. 11 is a top view showing a structure of a conductive pattern according to a fourth embodiment of the present disclosure. [Figure 8] FIG. 11 is a cross-sectional view showing the structure of a rotating electric machine according to a fifth embodiment of the present disclosure. [Figure 9] FIG. 11 is a circuit diagram showing capacitances between components of a rotating electric machine according to a fifth embodiment of the present disclosure. [Figure 10] FIG. 13 is a cross-sectional view showing the structure of a rotating electric machine according to a sixth embodiment of the present disclosure. [Figure 11] FIG. 13 is a circuit diagram showing the capacitance between components of a rotating electric machine according to a sixth embodiment of the present disclosure. [Figure 12] FIG. 13 is a circuit diagram showing capacitances between components of a rotating electric machine according to a seventh embodiment of the present disclosure. [Figure 13] FIG. 13 is a cross-sectional view showing the structure of a rotating electric machine according to an eighth embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Embodiment 1 Fig. 1 is a cross-sectional view showing the structure of a rotating electric machine according to a first embodiment of the present disclosure. As shown in Fig. 1, the rotating electric machine 1 includes a stator 2, a rotor 5, a shaft 6, bearings 7, 8, brackets 9, 10, a molding material 11, a conductive member 12, and a circuit board 13. In the following description, the direction in which the shaft 6 extends is referred to as the "axial direction," and the direction extending radially from the center of the shaft 6 is referred to as the "radial direction."

[0014] The stator 2 has a stator winding 3 and a stator core 4 around which the stator winding 3 is wound. An insulator (not shown) for insulating the stator core 4 is interposed between the stator winding 3 and the stator core 4. The stator 2 is disposed outside the rotor 5 with a gap therebetween. The stator 2 surrounds the rotor 5. The stator winding 3 includes a first stator winding portion 3a protruding from the stator core 4 in the axial direction and a second stator winding portion 3b. The first stator winding portion 3a is located on the bearing 7 and bracket 9 side in the axial direction, and the second stator winding portion 3b is located on the bearing 8 and bracket 10 side in the axial direction. The stator winding 3 and the stator core 4 are integrally molded by a molding material 11 and are provided inside the molding material 11. The stator core 4 is formed of a magnetic material. For example, an electromagnetic steel sheet, which is a soft magnetic material, is used for the stator core 4.

[0015] The rotor 5 is disposed radially inside the stator core 4 with a gap therebetween. The rotor 5 is formed of a magnetic material. The rotor 5 may also be formed of a magnetic and insulating material containing, for example, a resin. The rotor 5 may also be formed of a magnetic and insulating material in which an insulating resin material such as nylon, elastomer, or polyphenylene sulfide (PPS) is mixed with a magnetic material such as ferrite, neodymium, or samarium-cobalt alloy. The rotor 5 may also be formed of a permanent magnet, which is a hard magnetic material. The rotor 5 may also be formed by integrally molding, for example, an insulating material, or a magnetic and insulating material, with a permanent magnet.

[0016] A shaft 6 is provided in the center of the rotor 5. The shaft 6 is fastened to the radially inner side of the rotor 5. The shaft 6 is formed of a conductive material such as steel (e.g., carbon steel such as S45C) or alloy steel (e.g., stainless steel).

[0017] Two bearings 7 and 8 are attached to the shaft 6 to rotatably support the shaft 6. The bearing 7 is located at one axial end of the shaft 6, and the bearing 8 is located at the other axial end of the shaft 6. The bearing 7 has an outer ring 7a, an inner ring 7b, a plurality of rolling elements 7c, and a lubricant 7d. The outer ring 7a of the bearing 7 is fixed to a mold material 11 and a bracket 9. The shaft 6 is fixed to the inside of the inner ring 7b of the bearing 7 via the plurality of rolling elements 7c and the lubricant 7d. The bearing 8 has an outer ring 8a, an inner ring 8b, a plurality of rolling elements 8c, and a lubricant 8d. The outer ring 8a of the bearing 8 is fixed to a mold material 11 and a bracket 10. The shaft 6 is fixed to the inner ring 8b of the bearing 8 via the plurality of rolling elements 8c and the lubricant 8d.

[0018] Bracket 9 is located on one axial end side of shaft 6, and bracket 10 is located on the other axial end side of shaft 6. Bracket 9 fixes bearing 7, and bracket 10 fixes bearing 8. Brackets 9 and 10 are formed of a conductive material such as steel (e.g., carbon steel such as S45C) or alloy steel (e.g., stainless steel).

[0019] The stator 2 and the brackets 9, 10 are insulated by a molding material 11. Furthermore, the outer ring 7a of the bearing 7 and the bracket 9 are electrically connected, and the outer ring 8a of the bearing 8 and the bracket 10 are also electrically connected. The inner ring 7b of the bearing 7 and the inner ring 8b of the bearing 8 are electrically connected to the shaft 6. Then, when the rotating electric machine 1 is driven, an insulating state is created inside the bearings 7, 8 by the lubricants 7d, 8d.

[0020] The rotating electric machine 1 has a built-in circuit board 13 on which a drive circuit is mounted. The circuit board 13 is provided so as to extend like a plate perpendicular to the axial direction, and is located between the stator 2 and the bracket 9 in the axial direction. The shaft 6 passes through the center of the circuit board 13. The circuit board 13 is provided inside the molding material 11. A PWM type inverter drive circuit is mounted on the circuit board 13. The supply of electricity to the stator windings 3 is controlled by this inverter drive circuit.

[0021] In this embodiment, a conductive member 12 is provided that is electrically connected to the bearing 7 via the bracket 9. The conductive member 12 is provided inside the molding material 11. At least a portion of the conductive member 12 is provided at a position facing the first stator winding portion 3a of the stator winding 3, and forms a capacitance between the first stator winding portion 3a and the conductive member 12. The conductive member 12 is joined to the bracket 9 and electrically connected. The bracket 9 and the conductive member 12 are joined by welding, such as welding, pressure welding, brazing, etc. The bracket 9 and the conductive member 12 may also be chemically joined by, for example, an adhesive. The bracket 9 and the conductive member 12 may also be mechanically joined by, for example, a rivet, a bolt, or shrink fitting. The bracket 9 and the conductive member 12 may also be formed of a single member.

[0022] Here, Figure 1 shows an example in which conductive member 12 is electrically connected to bearing 7 via bracket 9 and is provided in a position facing first stator winding portion 3a, but conductive member 12 may also be electrically connected to bearing 8 via bracket 10 and provided facing second stator winding portion 3b.

[0023] The conductive member 12 is formed of a conductive material such as aluminum alloy, copper, steel (e.g., carbon steel such as S45C) or alloy steel (e.g., stainless steel). BMC (Bulk Molding Compound) is a thermosetting molding material that uses fibers (mainly glass fibers) as a reinforcing material in a matrix in which unsaturated polyester resin is the main component and a thermoplastic polymer as a low-shrinkage agent, a hardener, a filler, and a release agent are uniformly mixed. SMC (Sheet Molding Compound) is a thermosetting molding material that is made by impregnating a reinforcing material with a mixture of a resin matrix to which a low-shrinkage agent, a filler, an additive, etc. are added, and processing the mixture into a sheet or plate shape with a thickness of 1 to 5 mm.

[0024] The operation of the rotating electric machine 1 will be described below. FIG. 2 is a schematic circuit diagram of the rotating electric machine according to the first embodiment of the present disclosure. As shown in FIG. 2, the rotating electric machine 1 is connected to a power supply device 14. The power supply device 14 supplies AC power, such as three-phase AC power, to the rotating electric machine 1. The power supply device 14 includes, for example, a power source 15, a smoothing capacitor 16, an inverter circuit 17, a positive electrode line 18, a negative electrode line 19, and a control circuit 20. The power source 15 is connected to the positive electrode line 18 and the negative electrode line 19. The power source 15 is, for example, a DC power source. The smoothing capacitor 16 is connected to the positive electrode line 18 and the negative electrode line 19. The smoothing capacitor 16 stabilizes the DC power between the positive electrode line 18 and the negative electrode line 19.

[0025] The inverter circuit 17 includes a positive input terminal 17a, a negative input terminal 17b, legs 21u, 21v, and 21w, a u-phase output terminal 22u, a v-phase output terminal 22v, and a w-phase output terminal 22w. The positive input terminal 17a is connected to a positive line 18. The negative input terminal 17b is connected to a negative line 19. The legs 21u, 21v, and 21w are connected to the positive input terminal 17a and the negative input terminal 17b, respectively. The legs 21u, 21v, and 21w each include an upper arm and a lower arm. The upper arm and the lower arm each include a semiconductor switching element 23 such as an insulated gate bipolar transistor (IGBT), and a free wheel diode 24 connected in reverse parallel to the semiconductor switching element 23.

[0026] When the semiconductor switching element 23 is an IGBT, the collector terminal of the IGBT of the upper arm is connected to the positive input terminal 17a, and the emitter terminal of the IGBT of the lower arm is connected to the negative input terminal 17b. The u-phase output terminal 22u is connected to the leg 21u. The v-phase output terminal 22v is connected to the leg 21v. The w-phase output terminal 22w is connected to the leg 21w. The u-phase stator winding 3u is connected to the u-phase output terminal 22u. The v-phase stator winding 3v is connected to the v-phase output terminal 22v. The w-phase stator winding 3w is connected to the w-phase output terminal 22w.

[0027] The control circuit 20 is connected to each gate terminal of the semiconductor switching elements 23. The inverter circuit 17 is controlled by the control circuit 20, for example, by a pulse width modulation (PWM) method. The inverter circuit 17 converts DC power input to the inverter circuit 17 from the power source 15 into three-phase AC power (u-phase AC power, v-phase AC power, and w-phase AC power). The inverter circuit 17 outputs the three-phase AC power to the stator winding 3. Specifically, the inverter circuit 17 outputs u-phase AC power to the u-phase stator winding 3u. The inverter circuit 17 outputs v-phase AC power to the v-phase stator winding 3v. The inverter circuit 17 outputs w-phase AC power to the w-phase stator winding 3w. By supplying the three-phase AC power to the stator winding 3, the rotor 5 and the shaft 6 to which the rotor 5 is fixed rotate.

[0028] Next, a schematic distribution of the capacitance of the rotating electric machine 1 will be described. FIG. 1 shows a schematic distribution of the capacitance formed by the members constituting the rotating electric machine 1. The capacitance C B-N is the capacitance between the bracket 9 and the reference potential pattern of the circuit board 13. B-N The value of the capacitance C mainly depends on the dielectric constant and the insulation distance of the molding material 11. W-S is the capacitance between the stator winding 3 and the shaft 6. W-S The value of depends mainly on the dielectric constant and insulation distance of the molding material 11 and the dielectric constant and thickness of the rotor 5.

[0029] Capacitance C W-C is the capacitance between the stator winding 3 and the stator core 4. W-C The value of the capacitance C depends mainly on the dielectric constant of the molding material 11 and the insulation distance. C-S is the capacitance between the stator core 4 and the shaft 6. C-S The value of the capacitance C mainly depends on the dielectric constant and insulation distance of the molding material 11 and the dielectric constant and thickness of the rotor 5. S-N is the capacitance between the shaft 6 and the reference potential pattern of the circuit board 13. S-N The value of depends mainly on the dielectric constant of the molding material 11 and the insulation distance.

[0030] Capacitance C bear is the sum of the capacitance between the inner ring 7b of the bearing 7 and the rolling elements 7c, the capacitance between the outer ring 7a of the bearing 7 and the rolling elements 7c, the capacitance between the inner ring 8b of the bearing 8 and the rolling elements 8c, and the capacitance between the outer ring 8a of the bearing 8 and the rolling elements 8c. bear The value of depends mainly on the insulation distance between the inner ring 7b of the bearing 7 and the multiple rolling elements 7c, the insulation distance between the outer ring 7a of the bearing 7 and the multiple rolling elements 7c, the insulation distance between the inner ring 8b of the bearing 8 and the multiple rolling elements 8c, the insulation distance between the outer ring 8a of the bearing 8 and the multiple rolling elements 8c, and the dielectric constant of the lubricants 7d, 8d.

[0031] The mechanism by which electrolytic corrosion occurs will be described below. Fig. 3 is a circuit diagram showing the electrostatic capacitance between the components of the rotating electric machine according to the first embodiment of the present disclosure. The neutral point potential V COM is the potential difference between the stator winding 3 and the negative line 19, which is the reference potential of the inverter circuit 17 in the circuit board 13, when the rotating electric machine 1 is in operation. COM is the average value of the voltage of three-phase AC power (u-phase voltage of u-phase AC power, v-phase voltage of v-phase AC power, and w-phase voltage of w-phase AC power). In an inverter circuit controlled by the pulse width modulation (PWM) method, the neutral point potential V COM The value of may not be zero, which is called neutral point potential fluctuation.

[0032] As shown in FIG. 3, the outer ring potential V Outer is the neutral point potential V COM is the capacitance C between the stator winding 3 and the outer ring 7a or the outer ring 8a. W-B and the capacitance C between the outer ring 7a and the reference potential pattern of the circuit board 13 B-N is divided by the series-connected circuit A1. Outer is shown in the following equation (1).

[0033]

number

[0034] In FIG. 3, the inner ring potential of bearings 7 and 8 (the inner ring potential of the bearing) V Inner is the neutral point potential V COM is the combined capacitance C between the stator winding 3 and the shaft 6. COMB1 and the capacitance C between the shaft 6 and the reference potential pattern of the circuit board 13 S-N is divided by the series-connected circuit A2. Inner and C COMB is expressed as the following equations (2) and (3).

[0035]

number

[0036]

number

[0037] In FIG. 3, the potential difference generated in the capacitance of the bearings 7 and 8, that is, the potential difference (shaft voltage) between the outer ring potential of the bearings 7 and 8 and the inner ring potential of the bearing 7, is V Axis Then, V Axis is as shown in the following equation (4).

[0038]

number

[0039] When the rotating electric machine 1 is in operation, a shaft voltage is applied to the bearings 7, 8. At this time, if the shaft voltage is greater than the dielectric breakdown voltage of the lubricants 7d, 8d inside the bearings 7, 8, a discharge phenomenon occurs due to local dielectric breakdown. This discharge phenomenon forms tiny discharge marks on the rolling surfaces of the bearings 7, 8, and if this continues for a long period of time, it leads to electrolytic corrosion. Therefore, the shaft voltage V Axis This is one of the causes of electrical corrosion.

[0040] Next, the principle of electrolytic corrosion prevention in the present disclosure will be described with reference to Fig. 1 and Fig. 3. In this embodiment, as shown in Fig. 1, the conductive member 12 is electrically connected to the bearing 7 via the bracket 9, and at least a portion of the conductive member 12 is provided inside the molding material 11 at a position facing the first stator winding portion 3a, thereby forming a capacitance C adj This capacitance C adj As shown in FIG. 3, the capacitance C between the stator winding 3 and the outer ring 7a in the circuit A1 is W-B is connected in parallel.

[0041] Outer ring potential of bearing 7 V Outeris the neutral point potential V COM is the capacitance C between the stator winding 3 and the bracket 9. W-B The capacitance C generated between the conductive member 12 and the stator winding 3 is adj The combined capacitance C COMB2 and the capacitance C between the bracket 9 and the reference potential pattern of the circuit board 13 B-N The voltage is divided by V Outer and C COMB2 is expressed as equations (5) and (6).

[0042]

number

[0043]

number

[0044] In the rotating electric machine of the present disclosure, the electrostatic capacitance C generated between the conductive member 12 and the stator winding 3 is adj By appropriately setting the outer ring potential V Outer The inner ring potential V of bearing 7 Inner Therefore, the shaft voltage V, which is the potential difference between the outer ring potential of the bearing 7 and the inner ring potential of the bearing, Axis This makes it possible to keep the shaft voltage V Axis Since it is possible to prevent the voltage from reaching the dielectric breakdown voltage of the lubricant 7d inside the bearing 7, the occurrence of electrolytic corrosion can be prevented. Rotating Electric Machine

[0045] Next, a method for manufacturing the rotating electric machine 1 will be described. FIG. 4 is a flowchart showing a method for manufacturing the rotating electric machine according to the first embodiment of the present invention. In step S1, the stator winding 3 is first wound around the stator core 4. In step S2, the bearings 7 and 8 are arranged, and the conductive member 12 is electrically connected to the bearing 7, and at least a part of the conductive member 12 is arranged to face the stator winding portion 3a of the stator winding 3 that protrudes from the stator core 4 in the axial direction. By arranging the conductive member 12 in this manner, a capacitance is formed between the conductive member 12 and the stator winding portion 3a. In step S3, the stator winding 3, the stator core 4, and the conductive member 12 are integrally molded with the molding material 11. In step S4, the rotor 5 and the shaft 6 are arranged inside the stator 2 with a gap therebetween.

[0046] As described above, in the rotating electric machine 1 of the present disclosure, the conductive member 12 is electrically connected to the bearing 7, and is provided inside the molding material 11 at a position where at least a portion of the conductive member 12 faces the stator winding portion 3a, forming a capacitance between the conductive member 12 and the stator winding portion 3a. This makes it possible to prevent electrolytic corrosion from occurring in the bearings 7, 8, and to prevent the manufacturing process from becoming complicated. In addition, because the conductive member 12 is disposed inside the molding material 11, it is possible to prevent electrolytic corrosion from occurring without increasing the size of the rotating electric machine 1.

[0047] Furthermore, in the manufacturing method of the rotating electric machine 1 disclosed herein, at least a portion of the conductive member 12 is arranged to face the stator winding portion 3a and form a capacitance between the stator winding portion 3a, and then the stator 2 and the conductive member 12 are integrally molded with the molding material 11, thereby preventing electrolytic corrosion from occurring in the bearing 7 and preventing the manufacturing work from becoming complicated.

[0048] In the rotating electric machine 1 of the present embodiment, an example has been shown in which one conductive member 12 is electrically connected to either the bearing 7 or 8 via the bracket 9, but multiple conductive members 12 may be provided. Also, the conductive member 12 may be provided so as to be electrically connected to both the bearing 7 and the bearing 8. By providing multiple conductive members 12 in a position inside the molding material 11 where at least a portion of the conductive members 12 faces the stator winding portions 3a and 3b, multiple capacitances are formed between the stator winding portions 3a and 3b, which makes it possible to prevent the occurrence of electrolytic corrosion and to prevent the work after integral molding from becoming complicated, and further to reduce the variation in the effect of suppressing electrolytic corrosion occurring in the rotating electric machine 1.

[0049] In addition, in the rotating electric machine 1 of this embodiment, an example has been shown in which the conductive member 12 is electrically connected to the bearings 7, 8 via the brackets 9, 10, but the conductive member 12 may be directly connected to the bearings 7, 8 without going through the brackets 9, 10.

[0050] Embodiment 2 In the second embodiment, the same components as those in the first embodiment of the present disclosure are designated by the same reference numerals, and a description of the same or corresponding portions will be omitted. Hereinafter, a rotating electric machine 1b according to the second embodiment will be described with reference to the drawings.

[0051] Fig. 5 is a cross-sectional view showing the structure of a rotating electric machine according to embodiment 2 of the present disclosure. As shown in Fig. 5, in rotating electric machine 1b according to this embodiment, conductive member 12 is electrically connected to bearing 7 via bracket 9. A part of conductive member 12 is conductive pattern 26 formed integrally with circuit board 13. Conductive pattern 26 is provided at a position facing first stator winding portion 3a of stator winding 3, and forms a capacitance with first stator winding portion 3a.

[0052] In the rotating electric machine 1b of the present embodiment, a capacitance C is generated between the conductive pattern 26, which is a part of the conductive member 12, and the stator winding 3. adj As a result, the outer ring potential V of the bearing is generated in the same manner as in the first embodiment. Outer The potential of the inner ring of the bearing V InnerTherefore, the shaft voltage V, which is the potential difference between the outer ring potential and the inner ring potential of the bearing, Axis This makes it possible to keep the shaft voltage V Axis This can prevent electrolytic corrosion from occurring because it is possible to prevent the dielectric breakdown voltage of the lubricants 7d, 8d inside the bearings 7, 8 from reaching the dielectric breakdown voltage of the lubricants 7d, 8d inside the bearings 7, 8. Since the conductive pattern 26 is provided on the inside of the molding material 11 as in the first embodiment, it is possible to prevent the work after the integral molding from becoming complicated.

[0053] Furthermore, in the rotating electric machine 1b of the present embodiment, the conductive pattern 26 is provided as a part of the conductive member 12, so that the capacitance C adj The value of C can be set taking into consideration the dielectric constant and insulation distance of the molding material 11 that is integrally molded, and the dielectric constant and thickness of the circuit board 13. The dielectric constant and thickness of the circuit board 13 also affect C adj Since it is possible to adjust the capacitance C adj This allows for a larger number of parameters to be adjusted, making it possible to easily adjust the capacitance value to an optimum value.

[0054] Embodiment 3 In the third embodiment, the same components as those in the first embodiment of the present disclosure are designated by the same reference numerals, and a description of the same or corresponding portions will be omitted. Hereinafter, a rotating electric machine 1c according to the third embodiment will be described with reference to the drawings.

[0055] FIG. 6 is a cross-sectional view showing the structure of a rotating electric machine according to a third embodiment of the present disclosure. As shown in FIG. 6, in a rotating electric machine 1c according to this embodiment, a conductive member 12 is electrically connected to a bearing 7 via a bracket 9. A part of the conductive member 12 is a conductive pattern 26 integrally formed with a circuit board 13. The conductive pattern 26 is provided at a position facing a first stator winding portion 3a of the stator winding 3, and forms a capacitance between the conductive pattern 26 and the first stator winding portion 3a. A shaft 6 is provided penetrating the center of the circuit board 13, but the circuit board 13 is not fixed to the shaft 6. Since the circuit board 13 is not fixed to the shaft 6, the relative positional relationship between the conductive pattern 26 and the first stator winding portion 3a can be changed depending on the axial arrangement of the circuit board 13 during integral molding.

[0056] In the rotating electric machine 1c of the present embodiment, a capacitance C is generated between the conductive pattern 26, which is a part of the conductive member 12, and the stator winding 3. adj As a result, the outer ring potential V of the bearing is generated in the same manner as in the first embodiment. Outer The potential of the inner ring of the bearing V Inner Therefore, the shaft voltage V, which is the potential difference between the outer ring potential and the inner ring potential of the bearing, Axis This makes it possible to keep the shaft voltage V Axis This can prevent the occurrence of electrolytic corrosion because it is possible to prevent the dielectric breakdown voltage of the lubricants 7d, 8d inside the bearings 7 and 8 from reaching the dielectric breakdown voltage of the lubricants 7d, 8d inside the bearings 7 and 8. Since the conductive pattern 26, which is a part of the conductive member 12, is provided inside the molding material 11 as in the first embodiment, it is possible to prevent the work after the integral molding from becoming complicated.

[0057] Furthermore, in the rotating electric machine 1c of this embodiment, since the circuit board 13 is not fixed to the shaft 6, the C is determined not only by the dielectric constant of the molding material 11 between the circuit board 13 and the stator winding 3 and the dielectric constant and thickness of the circuit board 13, but also by the insulation distance between the circuit board 13 and the stator winding 3. adj In this way, in the rotating electric machine 1c of the present embodiment, the capacitance C adjThis allows for a larger number of parameters to be adjusted, making it possible to easily adjust the capacitance value to an optimum value.

[0058] Embodiment 4 In the fourth embodiment, the same components as those in the first embodiment of the present disclosure are designated by the same reference numerals, and description of the same or corresponding portions will be omitted. Hereinafter, a rotating electric machine 1d according to the fourth embodiment will be described with reference to the drawings.

[0059] In a rotating electric machine 1d according to this embodiment, a conductive member 12 is electrically connected to a bearing 7 via a bracket 9. A part of the conductive member 12 is a conductive pattern 26 that is integrally formed with a circuit board 13. The conductive pattern 26 is provided at a position facing the first stator winding portion 3a of the stator winding 3, and forms a capacitance between the conductive pattern 26 and the first stator winding portion 3a.

[0060] Fig. 7 is a top view of a conductive pattern of a rotating electric machine according to embodiment 4 of the present disclosure. As shown in Fig. 7, a plurality of conductive patterns 26, which are part of conductive member 12, are provided on circuit board 13. Since each of the plurality of conductive patterns 26 has a different pattern width and a different pattern length, a plurality of conductive patterns 26 having different areas are provided on circuit board 13. Therefore, in rotating electric machine 1d of the present embodiment, at least one or more conductive patterns 26 having different areas are provided on the surface of circuit board 13 facing bracket 9, and conductive pattern 26 to be electrically connected to bearing 7 is selected.

[0061] In the rotating electric machine 1d of the present embodiment, a capacitance C is generated between the stator winding 3 and a plurality of conductive patterns 26 that are part of the conductive member 12. adj As a result, the outer ring potential V of the bearing is generated in the same manner as in the first embodiment. Outer The potential of the inner ring of the bearing V Inner Therefore, the shaft voltage V, which is the potential difference between the outer ring potential and the inner ring potential of the bearing, Axis This makes it possible to keep the shaft voltage V AxisIt is possible to prevent the occurrence of electrolytic corrosion because it is possible to prevent the dielectric breakdown voltage of the lubricants 7d, 8d inside the bearings 7 and 8 from reaching the dielectric breakdown voltage of the lubricants 7d, 8d inside the bearings 7 and 8. Since the conductive pattern 26 is provided inside the molding material 11 as in the first embodiment, it is possible to prevent the work after the integral molding from becoming complicated.

[0062] Furthermore, in the rotating electric machine 1d of the present embodiment, the circuit board 13 is provided with conductive patterns 26 having different areas. Therefore, C is determined not only by the dielectric constant of the molding material 11 between the stator winding 3 and the circuit board 13 and the dielectric constant and thickness of the circuit board 13, but also by the area of ​​the conductive pattern 26 that is electrically connected to the outer ring 7a. adj Therefore, in the rotating electric machine 1d of the present embodiment, the electrostatic capacitance C can be adjusted by appropriately selecting the conductive pattern 26 that is electrically connected to the outer ring 7a. adj This allows for a greater number of parameters to be adjusted, making it possible to easily adjust the capacitance value to an optimum value.

[0063] Embodiment 5. In the fifth embodiment, the same components as those in the first embodiment of the present disclosure are designated by the same reference numerals, and the description of the same or corresponding parts will be omitted. Hereinafter, a rotating electric machine 1e according to the fifth embodiment will be described with reference to the drawings.

[0064] Fig. 8 is a cross-sectional view showing the structure of a rotating electric machine according to embodiment 5 of the present disclosure. As shown in Fig. 8, conductive member 12 is electrically connected to bearing 7 via bracket 9. A part of conductive member 12 is conductive pattern 26 that is integrally formed with circuit board 13. Conductive pattern 26 is provided at a position facing first stator winding portion 3a of stator winding 3, and forms a capacitance with first stator winding portion 3a.

[0065] At least two conductive patterns 26 are provided on the surface of the circuit board 13 facing the bracket 9, and a capacitance C is formed between the conductive patterns 26. adj2 A conductive pattern 26 is also provided on the surface of the circuit board 13 facing the stator winding 2, and a capacitance C is formed between the conductive patterns 26. adj2At this time, the conductive pattern 26 provided on the surface facing the bracket 9 and the conductive pattern 26 provided on the surface facing the stator winding 3 are electrically connected. These conductive patterns 26 differ in at least one of the area and the interval at which they are arranged.

[0066] 9 is a circuit diagram showing the capacitance between the components of a rotating electric machine according to a fifth embodiment of the present disclosure. As shown in FIG. adj2 is the capacitance C adj As in the first and subsequent embodiments, the capacitance C adj and capacitance C adj2 By appropriately setting the outer ring potential V Outer The potential of the inner ring of the bearing V Inner Therefore, the shaft voltage V, which is the potential difference between the outer ring potential and the inner ring potential of the bearing, Axis This makes it possible to keep the shaft voltage V Axis This can prevent the voltage from reaching the breakdown voltage of the lubricants 7d, 8d inside the bearings 7, 8, thereby preventing the occurrence of electrolytic corrosion.

[0067] Furthermore, in the rotating electric machine 1e of the present embodiment, a capacitance C adj and a capacitance C generated between at least two conductive patterns 26 provided on the surface of the circuit board 13 facing the bracket 9. adj2 By optimally adjusting the capacitance C, the shaft voltage can be kept low. adj2 The value of can be adjusted by changing conductive patterns 26 to which conductive member 12 is connected in circuit board 13. This is equivalent to adjusting the area of ​​at least one pair of conductive patterns 26 and the spacing between them.

[0068] In this way, in the rotating electric machine 1e, a plurality of conductive patterns 26 are provided on the circuit board 13, and by changing at least one of the area of ​​the conductive patterns 26 and the intervals at which they are arranged, the capacitance C adj2 Therefore, the value of the capacitance C between the stator winding 3 and the conductive pattern 26 can be adjusted. adj In addition, the capacitance C between the conductive patterns 26 adj2 It is also possible to easily reduce the shaft voltage by adjusting

[0069] Embodiment 6 In the sixth embodiment, the same components as those in the first embodiment of the present disclosure are designated by the same reference numerals, and a description of the same or corresponding portions will be omitted. Hereinafter, a rotating electric machine 1f according to the sixth embodiment will be described with reference to the drawings.

[0070] Fig. 10 is a cross-sectional view showing the structure of a rotating electric machine according to a sixth embodiment of the present disclosure. As shown in Fig. 10, in a rotating electric machine 1f, a conductive member 12 is electrically connected to a bearing 7 via a bracket 9. A part of the conductive member 12 is a conductive pattern 26 that is integrally formed with a circuit board 13. The conductive pattern 26 is provided at a position facing the first stator winding portion 3a of the stator winding 3, and forms a capacitance between the conductive pattern 26 and the first stator winding portion 3a.

[0071] At least two conductive patterns 26 are provided on the surface of circuit board 13 facing bracket 9. Capacitor 27 is provided between conductive patterns 26 provided on the surface of circuit board 13 facing bracket 9.

[0072] 11 is a circuit diagram showing capacitances between components of a rotating electric machine according to a sixth embodiment of the present disclosure. As shown in FIG. 11, in a rotating electric machine 1f, the capacitance C Cap is the capacitance C adj As in the first and subsequent embodiments, the capacitance C adj and capacitance C Cap By appropriately setting the outer ring potential VOuter The potential of the inner ring of the bearing V Inner Therefore, the shaft voltage V, which is the potential difference between the outer ring potential and the inner ring potential of the bearing, Axis This makes it possible to keep the shaft voltage V Axis This can prevent the voltage from reaching the breakdown voltage of the lubricants 7d, 8d inside the bearings 7, 8, thereby preventing the occurrence of electrolytic corrosion.

[0073] Furthermore, in the rotating electric machine 1f of this embodiment, the capacitance C Cap The value of the capacitance C between the stator winding 3 and the conductive pattern 26 can be easily changed by replacing the capacitor 27. adj As well as the capacitance C Cap It is also possible to easily reduce the shaft voltage by adjusting

[0074] Embodiment 7 In the seventh embodiment, the same components as those in the first embodiment of the present disclosure are designated by the same reference numerals, and a description of the same or corresponding portions will be omitted. Hereinafter, a rotating electric machine 1g according to the seventh embodiment will be described with reference to the drawings.

[0075] In a rotating electric machine 1g according to this embodiment, a conductive member 12 is electrically connected to a bearing 7 via a bracket 9. A part of the conductive member 12 is a conductive pattern 26 that is integrally formed with a circuit board 13. The conductive pattern 26 is provided at a position facing the first stator winding portion 3a of the stator winding 3, and forms a capacitance between the conductive pattern 26 and the first stator winding portion 3a.

[0076] At least two conductive patterns 26 are provided on the surface of circuit board 13 facing bracket 9. A capacitor 27 is provided between conductive patterns 26 provided on the surface of circuit board 13 facing bracket 9. A discharge resistor 28 is connected in parallel to capacitor 27.

[0077] 12 is a circuit diagram showing the capacitance between the components of a rotating electric machine according to the seventh embodiment of the present disclosure. As shown in FIG 12, a discharge resistor 28 is connected in parallel to a capacitor 27.

[0078] In the rotating electric machine 1g, the capacitance C of the capacitor 27 Cap is the capacitance C adj As in the first and subsequent embodiments, the capacitance C adj and capacitance C Cap By appropriately setting the outer ring potential V Outer The potential of the inner ring of the bearing V Inner Therefore, the shaft voltage V, which is the potential difference between the outer ring potential and the inner ring potential of the bearing, Axis This makes it possible to keep the shaft voltage V Axis This can prevent the voltage from reaching the breakdown voltage of the lubricants 7d, 8d inside the bearings 7, 8, thereby preventing the occurrence of electrolytic corrosion.

[0079] Furthermore, in the rotating electric machine 1g of this embodiment, a discharge resistor 28 is connected in parallel to the capacitor 27. By connecting this discharge resistor 28, the charge stored in the capacitor 27 can be discharged to bring the capacitor 27 into a voltage-free state. By bringing the capacitor 27 into a voltage-free state, safety can be ensured by preventing electric shock, and it becomes possible to prevent damage to the circuit due to overvoltage suppression when the power is turned on again.

[0080] Embodiment 8 In the eighth embodiment, the same components as those in the first embodiment of the present disclosure are designated by the same reference numerals, and the description of the same or corresponding parts will be omitted. Hereinafter, a rotating electric machine 1h according to the eighth embodiment will be described with reference to the drawings. In this embodiment, a multilayer circuit board 29 is provided in place of the circuit board 13 in the first embodiment.

[0081] Fig. 13 is a cross-sectional view showing the structure of a rotating electric machine according to an eighth embodiment of the present disclosure. As shown in Fig. 13, in a rotating electric machine 1h according to this embodiment, a conductive member 12 is electrically connected to a bearing 7 via a bracket 9. A part of the conductive member 12 is a conductive pattern 26 formed on a multilayer circuit board 29. The conductive pattern 26 is provided at a position facing the first stator winding portion 3a of the stator winding 3, and forms a capacitance between the conductive pattern 26 and the first stator winding portion 3a.

[0082] At least two conductive patterns 26 are provided on the multilayer circuit board 29. The conductive patterns 26 are provided on a surface of the multilayer circuit board 29 facing the stator winding 3 and a surface of the multilayer circuit board 29 facing the bracket 9. The conductive patterns 26 are provided in a layer between the surface of the multilayer circuit board 29 facing the stator winding 3 and the surface of the multilayer circuit board 29 facing the bracket 9. The conductive patterns 26 provided on the surface of the multilayer circuit board 29 facing the stator winding 3 and the stator winding 2 are connected by a second conductive member 30. The conductive patterns 26 are different from each other in at least one of the area of ​​the conductive patterns 26 and the interval at which they are arranged. In other words, in the rotating electric machine 1h as well, a capacitance C adj is occurring.

[0083] In the rotating electric machine 1h, as in the first and subsequent embodiments, the capacitance C adj By appropriately setting the outer ring potential V Outer The potential of the inner ring of the bearing V Inner Therefore, the shaft voltage V, which is the potential difference between the outer ring potential and the inner ring potential of the bearing, Axis This makes it possible to keep the shaft voltage V Axis This can prevent the voltage from reaching the breakdown voltage of the lubricants 7d, 8d inside the bearings 7, 8, thereby preventing the occurrence of electrolytic corrosion.

[0084] Furthermore, the rotating electric machine 1h of the present embodiment has a multilayer circuit board 29 in which at least one pair of conductive patterns 26 are provided on the cross section of the circuit board, so that the capacitance Cadj depends on the area of ​​the conductive patterns 26, the spacing between them, and the dielectric constant of the multilayer circuit board 29. Therefore, by changing the combination of the conductive patterns 26 that connect the conductive members 12 and the conductive patterns 26 that are electrically connected to the stator winding 3, the capacitance C adj It becomes possible to adjust

[0085] The configurations shown in the above embodiments are merely examples of the contents of the present disclosure, and may be combined with other known techniques. Furthermore, parts of the configurations may be omitted or modified without departing from the scope of the present disclosure. [Explanation of symbols]

[0086] 1 rotating electric machine, 2 stator, 3 stator winding, 3u u-phase winding, 3v v-phase winding, 3w w-phase winding, 4 stator core, 5 rotor, 6 shaft, 7 8 bearing, 7a 8a outer ring, 7b 8b inner ring, 7c 8c multiple rolling elements, 7d 7d lubricant, 9 10 bracket, 11 molding material, 12 conductive material, 13 circuit board, 14 power supply device, 15 power supply, 16 smoothing capacitor, 17 inverter circuit, 17a positive input terminal, 17b negative input terminal, 18 positive line, 19 negative line, 20 control circuit, 21u 21v 21w leg, 22u u-phase output terminal, 22v v-phase output terminal, 22w w-phase output terminal, 23 semiconductor switching element, 24 freewheeling diode, 25 neutral point, 26 Conductive patterns, 27 Capacitors, 28 Discharge resistors, 29 Multilayer circuit boards

Claims

1. a stator having a stator winding wound around a stator core, the stator winding having a stator winding portion protruding from the stator core in an axial direction; a rotor disposed inside the stator in spaced relation; A shaft provided at the center of the rotor; A bearing that rotatably supports the shaft; a molding material that is a resin material that integrally molds the stator winding and the stator core; a circuit board provided inside the molding material and controlling the supply of current to the stator winding; a conductive member provided separately from the circuit board, electrically connected to the bearing, and provided within the molding material at a position facing the stator winding portion at least in part, away from the stator winding, and forming a capacitance between the conductive member and the stator winding portion such that a shaft voltage generated during rotation does not exceed a breakdown voltage of a lubricant inside the bearing.

2. 2. The rotating electric machine according to claim 1, further comprising a bracket for fixing the bearing and electrically connected to the bearing, the electrically conductive member being joined to the bracket.

3. The rotating electric machine according to claim 1 , wherein a plurality of the conductive members are provided, forming a plurality of capacitances between the conductive members and the stator winding portion.

4. A stator having a stator winding wound around a stator core, the stator winding having a stator winding portion protruding from the stator core in the axial direction; a rotor disposed inside the stator in spaced relation; A shaft provided at the center of the rotor; A bearing that rotatably supports the shaft; a molding material that is a resin material that integrally molds the stator winding and the stator core; a circuit board having a plurality of conductive patterns and a capacitor connected between the conductive patterns; a conductive member that is molded integrally with at least one of the conductive patterns, is electrically connected to the bearing, and is provided inside the molding material at a position facing the stator winding portion at least in part, away from the stator winding, and forms a capacitance between the conductive member and the stator winding portion such that a shaft voltage generated during rotational operation is less than the breakdown voltage of a lubricant that lubricates the bearing.

5. The rotating electric machine according to claim 4 , further comprising a discharge resistor connected in parallel with the capacitor.

6. 6. The rotating electric machine according to claim 4, wherein the circuit board is a multi-layer circuit board having a plurality of the conductive patterns.

7. winding a stator winding around a stator core to form a stator having a stator winding portion protruding axially from the stator core; disposing a circuit board inside a molding material, the circuit board controlling current supply to the stator winding; a step of disposing a bearing, electrically conducting with the bearing, at least a portion of which faces the stator winding portion, being separated from the stator winding, forming a capacitance between the stator winding portion and the bearing such that a shaft voltage generated during rotation does not exceed a breakdown voltage of a lubricant inside the bearing, and providing a conductive member separate from the circuit board; integrally molding the stator and the conductive member with the molding material; disposing a rotor and a shaft in spaced relation within the stator; A manufacturing method for a rotating electric machine comprising:

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