Rotary electrical machine, and method for manufacturing rotary electrical machine

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

Rotating electric machine and method of manufacturing the same

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

[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 well-known inverter driving method is a voltage-type PWM (Pulse Width Modulation) 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 devices, the carrier frequency of voltage-type PWM inverters has become increasingly higher. Therefore, when inverter-driven systems are used, high-frequency voltages are generated due to inverter switching. This high-frequency voltage is, for example, a high-frequency voltage (shaft voltage) caused by a potential difference between the outer and inner rings of a bearing due to voltage division by the electrostatic capacitance inside the rotating electrical machine. When this shaft voltage exceeds the dielectric breakdown voltage of the bearing lubricant, a high-frequency current (shaft current) flows between the outer and inner rings. The flow of shaft current causes corrosion, known as electrolytic corrosion, on the inner and outer ring raceways and the rolling surfaces of the bearing balls, thereby reducing the durability of the bearing. Therefore, in inverter-driven rotating electrical machines, it is necessary to reduce the shaft voltage to prevent problems 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 electric 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. To achieve this connection, a through-hole is formed by cutting into a portion 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 portion 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.

[0005] International Publication No. 2009 / 001546

[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, because a through hole is formed by cutting a part of the molding material, there is a problem in that the manufacturing process is 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 process from becoming complicated.

[0008] The rotating electric machine according to the present disclosure comprises a stator having a stator winding wound around a stator core and a stator winding portion where the stator winding protrudes axially from the stator core, a rotor arranged at a distance inside the stator, 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, and a conductive member that is electrically connected to the bearing, is provided inside the molding material in a position where at least a portion of the conductive member faces the stator winding portion, and forms a capacitance between the stator winding portion and the molding material.

[0009] The manufacturing method of 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 axially from the stator core; arranging a bearing and providing a conductive member that is electrically connected to the bearing and has at least a portion facing the stator winding portion to form a capacitance between the bearing and the conductive member; integrally molding the stator and the conductive member using a molding material; and arranging a rotor and a shaft with a gap between them inside the stator.

[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 in 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 preventing electrolytic corrosion from occurring in the bearing and avoiding complicated manufacturing operations.

[0011] Furthermore, according to the manufacturing method of 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 forms a capacitance 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 bearing and preventing the manufacturing process from becoming complicated.

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

[0013] First Embodiment 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 and 8, brackets 9 and 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) is interposed between the stator winding 3 and the stator core 4 to insulate 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 and a second stator winding portion 3b, which protrude axially from the stator core 4. The first stator winding portion 3a is located axially toward the bearing 7 and bracket 9, while the second stator winding portion 3b is located axially toward the bearing 8 and bracket 10. The stator winding 3, the stator core 4, and the stator core 4 are integrally molded using a molding material 11 and are disposed within 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. Alternatively, the rotor 5 may be formed of a magnetic and insulating material containing, for example, a resin. The rotor 5 may be formed of a magnetic and insulating material that is a mixture of an insulating resin material such as nylon, elastomer, or polyphenylene sulfide (PPS) and a magnetic material such as ferrite, neodymium, or samarium-cobalt alloy. The rotor 5 may be formed of a permanent magnet, which is a hard magnetic material. The rotor 5 may be formed, for example, by integrally molding an insulating material or a magnetic and insulating material with the permanent magnet.

[0016] A shaft 6 is provided at the center of the rotor 5. The shaft 6 is fastened to the radially inner side of the rotor 5. The shaft 6 is made 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, multiple rolling elements 7c, and a lubricant 7d. The outer ring 7a of the bearing 7 is fixed to a molding material 11 and a bracket 9. The shaft 6 is fixed to the inside of the inner ring 7b of the bearing 7 via multiple rolling elements 7c and a lubricant 7d. The bearing 8 has an outer ring 8a, an inner ring 8b, multiple rolling elements 8c, and a lubricant 8d. The outer ring 8a of the bearing 8 is fixed to a molding material 11 and a bracket 10. The shaft 6 is fixed to the inner ring 8b of the bearing 8 via multiple rolling elements 8c and a 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 secures bearing 7, and bracket 10 secures 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. 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. 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 incorporates a 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 axially between the stator 2 and the bracket 9. 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 inverter drive circuit is mounted on the circuit board 13. The supply of current 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 in a position facing the first stator winding portion 3a of the stator winding 3, and forms a capacitance between the conductive member 12 and the first stator winding portion 3a. The conductive member 12 is joined to the bracket 9 and electrically connected thereto. The bracket 9 and the conductive member 12 are joined by welding, pressure welding, brazing, or other welding methods. The bracket 9 and the conductive member 12 may also be chemically joined, for example, with an adhesive. The bracket 9 and the conductive member 12 may also be mechanically joined, for example, with rivets, bolts, or shrink fitting. The bracket 9 and the conductive member 12 may also be formed from 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 located 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 located in a position 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 that is a uniform mixture of unsaturated polyester resin as the main component, a thermoplastic polymer as a low-profile agent, a curing agent, a filler, and a mold release agent. SMC (Sheet Molding Compound) is a thermosetting molding material that is impregnated with a mixture of a resin matrix to which a low-profile agent, filler, additives, etc. are added, and processed 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 supply 15, a smoothing capacitor 16, an inverter circuit 17, a positive line 18, a negative line 19, and a control circuit 20. The power supply 15 is connected to the positive line 18 and the negative line 19. The power supply 15 is, for example, a DC power supply. The smoothing capacitor 16 is connected to the positive line 18 and the negative line 19. The smoothing capacitor 16 stabilizes the DC power between the positive line 18 and the negative 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 freewheeling diode 24 connected in anti-parallel to the semiconductor switching element 23.

[0026] When the semiconductor switching elements 23 are IGBTs, the collector terminals of the IGBTs of the upper arm are connected to the positive input terminal 17a, and the emitter terminals of the IGBTs of the lower arm are 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 the gate terminals of each of the semiconductor switching elements 23. The inverter circuit 17 is controlled by the control circuit 20, for example, using pulse width modulation (PWM). The inverter circuit 17 converts DC power input to the inverter circuit 17 from the power supply 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 the u-phase AC power to the u-phase stator winding 3u. The inverter circuit 17 outputs the v-phase AC power to the v-phase stator winding 3v. The inverter circuit 17 outputs the w-phase AC power to the w-phase stator winding 3w. Supplying the three-phase AC power to the stator winding 3 rotates the rotor 5 and the shaft 6 to which the rotor 5 is fixed.

[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 capacitance C mainly depends on the dielectric constant of the molding material 11 and the insulation distance. 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 mainly depends 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 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 plurality of rolling elements 7c, the capacitance between the outer ring 7a of the bearing 7 and the plurality of rolling elements 7c, the capacitance between the inner ring 8b of the bearing 8 and the plurality of rolling elements 8c, and the capacitance between the outer ring 8a of the bearing 8 and the plurality of rolling elements 8c. ｂｅａｒ The value of depends mainly on the insulation distance between the inner ring 7b of the bearing 7 and the plurality of rolling elements 7c, the insulation distance between the outer ring 7a of the bearing 7 and the plurality of rolling elements 7c, the insulation distance between the inner ring 8b of the bearing 8 and the plurality of rolling elements 8c, the insulation distance between the outer ring 8a of the bearing 8 and the plurality of 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 on the circuit board 13, when the rotating electric machine 1 is in operation. The neutral point potential V, which is the potential of the neutral point 25 of the stator winding 3, when the rotating electric machine 1 is in operation ＣＯＭ is the average value of the voltages of the three-phase AC power (u-phase voltage of the u-phase AC power, v-phase voltage of the v-phase AC power, and w-phase voltage of the w-phase AC power). In an inverter circuit controlled by a 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 as shown in the following equation (1).

[0033]

[0034] In FIG. 3, the inner ring potential of the bearings 7 and 8 (the inner ring potential of the bearing) V Ｉｎｎｅｒis 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 are expressed as the following equations (2) and (3).

[0035]

[0036]

[0037] In FIG. 3, the potential difference generated in the electrostatic 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]

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

[0040] Next, the principle of electrolytic corrosion prevention in the present disclosure will be described with reference to Figures 1 and 3. In this embodiment, as shown in Figure 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, in the circuit A1, the capacitance C Ｗ－Ｂ is connected in parallel.

[0041] Outer ring potential V of bearing 7 Ｏｕｔｅｒ is 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 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 are expressed as equations (5) and (6).

[0042]

[0043]

[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 of the bearing 7, Ｏｕｔｅｒ The inner ring potential V of the 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 This can prevent the voltage from reaching the breakdown voltage of the lubricant 7d inside the bearing 7, thereby preventing electrolytic corrosion.

[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, bearings 7 and 8 are arranged, and conductive member 12 is electrically connected to bearing 7, and at least a portion of conductive member 12 is arranged to face the stator winding portion 3a of the stator winding 3 that protrudes axially from the stator core 4. By arranging conductive member 12 in this manner, a capacitance is formed between conductive member 12 and stator winding portion 3a. In step S3, the stator winding 3, stator core 4, and conductive member 12 are integrally molded using molding material 11. In step S4, the rotor 5 and 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 in 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 avoid complicating the manufacturing process. Furthermore, 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 a capacitance is formed between the conductive member 12 and 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 process from becoming complicated.

[0048] In the rotating electric machine 1 of this 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 electrically connecting the multiple conductive members 12 to the bearings 7 and 8 and providing them inside the molding material 11 in positions where at least a portion of them faces the stator winding portions 3 a and 3 b, multiple capacitances are formed between the stator winding portions 3 a and 3 b, which not only prevents the occurrence of electrolytic corrosion and prevents the work after integral molding from becoming complicated, but also makes it possible to reduce 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 and 8 via the brackets 9 and 10, but it may also be electrically connected directly to the bearings 7 and 8 without going through the brackets 9 and 10.

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

[0051] 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 portion 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.

[0052] In the rotating electric machine 1b of this embodiment, there is a capacitance C 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 Ｏｕｔｅｒ The inner ring potential V of the bearing Ｉｎｎｅｒ Therefore, the shaft voltage V, which is the potential difference between the outer ring potential of the bearing and the inner ring potential of the bearing, Ａｘｉｓ This makes it possible to keep the shaft voltage V Ａｘｉｓ The occurrence of electrolytic corrosion can be prevented by preventing the voltage of the lubricants 7d, 8d inside the bearings 7, 8 from reaching the breakdown voltage of the lubricants 7d, 8d inside the bearings 7, 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 integral molding from becoming complicated.

[0053] Furthermore, in the rotating electric machine 1b of this 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 the value of 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] Third Embodiment In a third embodiment, the same components as those in the first embodiment of the present disclosure are designated by the same reference numerals, and descriptions of the same or corresponding parts 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 portion of the conductive member 12 is a conductive pattern 26 integrally molded with a circuit board 13. The conductive pattern 26 is located opposite a first stator winding portion 3a of the stator winding 3 and forms a capacitance with the first stator winding portion 3a. A shaft 6 penetrates the center of the circuit board 13, but the circuit board 13 is not fixed to the shaft 6. Because 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 by changing the axial position of the circuit board 13 during integral molding.

[0056] In the rotating electric machine 1c of this embodiment, there is a capacitance C 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 Ｏｕｔｅｒ The inner ring potential V of the bearing Ｉｎｎｅｒ Therefore, the shaft voltage V, which is the potential difference between the outer ring potential of the bearing 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 voltage of the lubricants 7d, 8d inside the bearings 7 and 8 from reaching the breakdown voltage of the lubricants 7d, 8d inside the bearings 7 and 8. Since the conductive pattern 26, which is 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 integral molding from becoming complicated.

[0057] Furthermore, in the rotating electric machine 1c of this embodiment, the circuit board 13 is not fixed to the shaft 6, so 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 this embodiment, 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.

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

[0059] In the rotating electric machine 1d according to this embodiment, the conductive member 12 is electrically connected to the bearing 7 via the bracket 9. A part of the conductive member 12 is a conductive pattern 26 that is integrally formed with the 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] 7 is a top view of a conductive pattern of a rotating electric machine according to a fourth embodiment 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. Each of these plurality of conductive patterns 26 has a different pattern width and a different pattern length, and therefore, a plurality of conductive patterns 26 with different areas are provided on circuit board 13. Therefore, in rotating electric machine 1d of this embodiment, at least one conductive pattern 26 with different areas is provided on the surface of circuit board 13 facing bracket 9, and conductive pattern 26 that is to be electrically connected to bearing 7 is selected.

[0061] In the rotating electric machine 1d of this embodiment, there is a capacitance C 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 Ｏｕｔｅｒ The inner ring potential V of the bearingＩｎｎｅｒ Therefore, the shaft voltage V, which is the potential difference between the outer ring potential of the bearing and the inner ring potential of the bearing, Ａｘｉｓ This makes it possible to keep the shaft voltage V Ａｘｉｓ The occurrence of electrolytic corrosion can be prevented by preventing the voltage from reaching the 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 integral molding from becoming complicated.

[0062] Furthermore, in the rotating electric machine 1d of this embodiment, the conductive patterns 26 having different areas are provided on the circuit board 13, so that 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 this embodiment, the 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] Fifth Embodiment In a fifth embodiment, the same components as those in the first embodiment of the present disclosure are designated by the same reference numerals, and descriptions 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] 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 portion 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. ａｄｊ２A 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. ａｄｊ２ At 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 spacing 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. 9, the capacitance C 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 inner ring potential V of the bearing Ｉｎｎｅｒ Therefore, the shaft voltage V, which is the potential difference between the outer ring potential of the bearing 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 and 8d inside the bearings 7 and 8, thereby preventing electrolytic corrosion.

[0067] Furthermore, in the rotating electric machine 1e of this embodiment, a capacitance C generated between the stator winding 3 and the conductive pattern 26 provided on the surface of the circuit board 13 facing the stator winding 3 is ａｄｊ and the 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 the conductive patterns 26 to which the conductive members 12 are connected on the 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 spacing between them, 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 The shaft voltage can also be easily reduced by adjusting

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

[0070] 10 is a cross-sectional view showing the structure of a rotating electric machine according to embodiment 6 of the present disclosure. As shown in FIG. 10 , in a rotating electric machine 1f, conductive member 12 is electrically connected to bearing 7 via bracket 9. A portion 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.

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

[0072] 11 is a circuit diagram showing the capacitance between the components of a rotating electric machine according to the sixth embodiment of the present disclosure. As shown in FIG. 11, in the 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 V Ｏｕｔｅｒ The inner ring potential V of the bearing ＩｎｎｅｒTherefore, the shaft voltage V, which is the potential difference between the outer ring potential of the bearing 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 and 8d inside the bearings 7 and 8, thereby preventing 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 Not only that, but also the capacitance C Ｃａｐ The shaft voltage can also be easily reduced by adjusting

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

[0075] In the rotating electric machine 1g according to this embodiment, the conductive member 12 is electrically connected to the bearing 7 via the bracket 9. A part of the conductive member 12 is a conductive pattern 26 that is integrally formed with the 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 the 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 embodiment 7 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 inner ring potential V of the bearing Ｉｎｎｅｒ Therefore, the shaft voltage V, which is the potential difference between the outer ring potential of the bearing 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 and 8d inside the bearings 7 and 8, thereby preventing 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, and the capacitor 27 can be put into a no-voltage state. By putting the capacitor 27 into a no-voltage state, safety can be ensured by preventing electric shock, and it is possible to prevent damage to the circuit due to overvoltage suppression when the power is turned on again.

[0080] Eighth Embodiment 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 descriptions of the same or corresponding parts will be omitted. A rotating electric machine 1h according to the eighth embodiment will be described below with reference to the drawings. In this embodiment, a multilayer circuit board 29 is provided in place of the circuit board 13 of the first embodiment.

[0081] Eighth embodiment of the present disclosure relates to a rotary electric machine. As shown in Fig. 13, in a rotary 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 disposed in a position facing the first stator winding portion 3a of the stator winding 3, and forms a capacitance with 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 on 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 differ from one another in at least one of the area of ​​the conductive patterns 26 and the spacing 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 inner ring potential V of the bearing Ｉｎｎｅｒ Therefore, the shaft voltage V, which is the potential difference between the outer ring potential of the bearing 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 and 8d inside the bearings 7 and 8, thereby preventing electrolytic corrosion.

[0084] Furthermore, the rotating electric machine 1h of this embodiment has a multilayer circuit board 29 in which at least one pair of conductive patterns 26 is provided on the cross section of the circuit board, so that the capacitance C ａｄｊ 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 described in the above embodiments are merely examples of the contents of the present disclosure, and may be combined with other known technologies. Furthermore, parts of the configurations may be omitted or modified without departing from the scope of the present disclosure.

[0086] REFERENCE SIGNS LIST 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 member, 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 pattern, 27 capacitor, 28 discharge resistor, 29 multilayer circuit board

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 conductive member that is electrically connected to the bearing, that is provided inside the molding material at a position where at least a portion of the conductive member faces the stator winding portion, and that forms a capacitance between the conductive member and the stator winding portion; a circuit board provided inside the molding material as a separate body from the conductive member, the circuit board controlling the supply of current to the stator windings.

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. 3. The rotating electric machine according to claim 1, wherein a plurality of conductive patterns are provided on the circuit board, and a capacitor is connected between the conductive patterns.

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; a step of disposing a bearing, and providing a conductive member in electrical communication with the bearing, at least a portion of the conductive member facing the stator winding portion, and forming a capacitance between the conductive member and the stator winding portion; molding the stator and the conductive member integrally with a molding material; disposing a rotor and a shaft in spaced relation within the stator; disposing a circuit board inside the molding material as a separate body from the conductive member, the circuit board controlling current supply to the stator winding; A manufacturing method for a rotating electric machine comprising: