Stator and electric motor

Abstract

To provide a stator and an electric motor that allow a high number of revolutions.SOLUTION: A stator 23 comprises a stator core 231 in which thick steel plates 233 and thin steel plates 234 are laminated, and a stator coil 232 provided in the stator core 231. The thickness of the thick steel plate 233 is thicker than that of the thin steel plate 234.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a stator and an electric motor. [Background technology]

[0002] Patent Documents 1 and 2 disclose technologies related to sensorless drive motors. Both of the technologies disclosed in Patent Documents 1 and 2 address noise that occurs in induced voltages. Patent Document 1 employs a method of incorporating electrical elements such as capacitors and resistors into the circuit as a countermeasure against noise. Patent Document 2 employs a method using signal processing as a countermeasure against noise. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-126103 A [Patent Document 2] JP 2014-166097 A Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for electric motors to rotate at even higher speeds. To achieve higher speeds, it is important to take measures against noise, as signals with superimposed noise interfere with the rotation control of the motor. As mentioned above, noise countermeasures include a method of incorporating electric elements into the circuit and a method using signal processing. The method of incorporating electric elements into the circuit converts noise components into electrical loss and releases them as heat. Therefore, the electric elements that convert noise components into electrical loss become very hot. Furthermore, with the method using signal processing, there are cases where the signal processing cannot keep up with the high rotation speed of the motor. Therefore, it has been difficult to increase the rotation speed of electric motors.

[0005] Therefore, the present invention provides a stator that enables an electric motor to rotate at high speed, and an electric motor including the stator. [Means for solving the problem]

[0006] A stator according to one embodiment of the present invention comprises a stator body in which a plurality of metal plates, including a first metal plate and a second metal plate, are stacked, and a coil provided in the stator body, wherein the plurality of first metal plates include portions that contact each other without an insulating member therebetween so as to be electrically connected to each other, and the plurality of second metal plates face each other via an insulating member so as to be electrically insulated from each other.

[0007] The stator includes a plurality of first metal plates electrically connected to each other. With this configuration, an electrically thick metal plate is formed. The electrically thick metal plate provides resistance to high-frequency current. As a result, high-frequency noise components superimposed on signals used to control the rotation of the electric motor are reduced. Therefore, this stator can increase the rotation speed of the electric motor.

[0008] In the above stator, the pair of first metal plates may include connection surfaces facing each other, and the connection surfaces may include a conductive portion that contacts each other without an insulating member and an insulating portion that faces each other via an insulating member. With this configuration, it is possible to reduce high-frequency noise components superimposed on a signal used to control the rotation of the electric motor.

[0009] Another embodiment of the present invention provides an electric motor comprising a rotor, the above-mentioned stator, and a cooling section through which a heat medium flows to cool the stator. In the direction in which the heat medium flows, the multiple first metal plates are disposed upstream of the multiple second metal plates. Since this electric motor comprises the above-mentioned stator, it can achieve high speed rotation. Furthermore, this electric motor can reduce high frequency noise components superimposed on signals used to control the rotation of the electric motor.

[0010] A stator according to another embodiment of the present invention includes a stator body including a plurality of laminated metal plates including a first metal plate and a second metal plate, and a coil provided on the stator body, The thickness of the first metal plate is greater than the thickness of the second metal plate.

[0011] The stator includes a physically thick metal plate. The thick metal plate provides resistance to high-frequency current. As a result, high-frequency noise components superimposed on signals used to control the rotation of the motor are reduced. This stator therefore enables the motor to rotate at high speed.

[0012] In the above stator, the stator body may include a first stator end face and a second stator end face opposite to the first stator end face, and the first stator end face and the second stator end face may be formed of a second metal plate. This configuration also reduces high-frequency noise components superimposed on signals used to control the rotation of the electric motor.

[0013] In the above stator, the stator body may include a first stator end face and a second stator end face opposite to the first stator end face, the first stator end face being made of a first metal plate, and the second stator end face being made of a second metal plate. This configuration also reduces high-frequency noise components superimposed on signals used to control the rotation of the electric motor.

[0014] A stator in yet another embodiment of the present invention comprises a stator body in which a plurality of metal plates including a first metal plate and a second metal plate are stacked, and a coil provided in the stator body, wherein the first metal plate is made of a first material, the second metal plate is made of a second material different from the first material, and the resistance value of the first material to high-frequency current is greater than the resistance value of the second material to high-frequency current.

[0015] The stator is made of a material that has a high resistance to high-frequency currents. As a result, high-frequency noise components superimposed on the signals used to control the rotation of the motor are reduced. Therefore, the stator allows the motor to rotate at high speed. Effect of the Invention

[0016] According to the stator of the present invention and an electric motor including the stator, high speed rotation is possible. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic diagram of an electric motor system according to an embodiment. [Diagram 2] FIG. 2 is a circuit diagram of the inverter shown in FIG. [Diagram 3] FIG. 3 is a table for explaining the operation of the inverter and the motor shown in FIG. [Figure 4] Figure 4(a) is a graph showing the rotor phase, Figure 4(b) is a graph showing the U-phase voltage, Figure 4(c) is a graph showing the V-phase voltage, and Figure 4(d) is a graph showing the W-phase voltage. [Diagram 5] FIG. 5 is a circuit diagram showing a first operation of the inverter and the motor shown in FIG. [Figure 6] FIG. 6 is a circuit diagram showing a second operation of the inverter and the motor shown in FIG. [Figure 7] FIG. 7 is an equivalent circuit diagram for explaining the operation of the inverter and the motor shown in FIG. [Figure 8] FIG. 8 is a graph for explaining electrical problems in the inverter and the motor. [Figure 9] Fig. 9(a) is an enlarged cross-sectional view showing a main part of the motor shown in Fig. 1. Fig. 9(b) is a further enlarged cross-sectional view showing the main part of Fig. 9(a). [Figure 10] FIG. 10 is a cross-sectional view of a stator included in a motor according to the second embodiment. [Figure 11]Fig. 11(a) is a cross-sectional view of a stator included in a motor of a third embodiment. Fig. 11(b) is a cross-sectional view of a stator included in a motor of a first modified example. Fig. 11(c) is a cross-sectional view of a stator included in a motor of a second modified example. Fig. 11(d) is a cross-sectional view of a stator included in a motor of a third modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are given the same reference numerals and duplicated descriptions will be omitted.

[0019] First Embodiment 1 is a two-stage centrifugal compressor. The rotating machine system 100 includes a rotating machine 1 and an inverter 9 (power conversion device).

[0020] The rotating machine 1 has a motor 2 (electric motor), a cooling jacket 3, a cooling device 4, and a pair of compressors 6. The motor 2 is provided with a rotating shaft 21, and impellers 61 of the compressor 6 are connected to both ends of the rotating shaft 21. The cylindrical rotating shaft 21 is supported by a pair of bearings 7 and rotates about its axis L relative to a motor housing 26. The cooling jacket 3 recovers heat generated by the operation of the motor 2 using a cooling medium supplied from the cooling device 4. The cooling medium is, for example, water.

[0021] The motor 2 has a motor housing 26. The motor housing 26 accommodates the motor 2, the cooling jacket 3, and the like. The cooling device 4 may be disposed outside the motor housing 26 as shown in FIG. 1, or may be accommodated inside the motor housing 26. The motor housing 26 has, for example, a cylindrical shape. The integrated motor 2 and the cooling jacket 3 are fixed to the inner circumferential surface of the motor housing 26. The motor housing 26 is made of, for example, ductile cast iron (Ferrum Casting Ductile: FCD), etc. A bearing casing 63 supporting the bearings 7 is provided on the inner circumferential side of the motor housing 26 at both ends in the axial direction D.

[0022] The motor 2 is a so-called brushless DC motor. The motor 2 has a rotor 22 and a stator 23. An alternating current is provided to the stator 23. An interaction between the rotor 22 and the stator 23 generates a torque in the rotor 22. As a result, the rotating shaft 21 fixed to the rotor 22 rotates.

[0023] The rotor 22 is attached to the rotating shaft 21. The position where the rotor 22 is fixed is approximately the center of the rotating shaft 21 in the axial direction D (hereinafter simply referred to as the "axial direction D").

[0024] The stator 23 surrounds the rotor 22 along the circumferential direction of the rotating shaft 21. The stator 23 includes a stator core 231 and a stator coil 232. The cylindrical stator core 231 extending along the axis L is provided so as to surround the rotor 22. The stator coil 232 is formed of a conductor wound around the stator core 231. In the stator coil 232, a portion protruding from the stator core 231 is a so-called coil end 232a. The coil end 232a protrudes in the axial direction D beyond both ends of the stator core 231.

[0025] The cooling jacket 3 (cooling portion) is provided around the stator 23. That is, the cooling jacket 3 surrounds the stator 23 in the circumferential direction. The cooling jacket 3 also surrounds a part of the rotating shaft 21 and the rotor 22 that protrudes in the axial direction D beyond the end of the stator 23. The cooling jacket 3 is formed with a cooling flow passage 30 through which a cooling medium flows.

[0026] The cooling flow passage 30 is formed to revolve around the axis L of the rotating shaft 21. The cooling flow passage 30 has a flow passage inlet 301 and a flow passage outlet 302 (see FIG. 9 ). The flow passage inlet 301 of the cooling flow passage 30 is connected to a supply pipe 41. The flow passage outlet 302 is connected to a discharge pipe 42.

[0027] The cooling jacket 3 has a cylindrical inner housing 31 surrounding the stator 23, and a cylindrical outer housing 32 that is fitted to the inner housing 31. The inner housing 31 and the outer housing 32 are, for example, cast metal, and examples of materials include aluminum (Al) or cast iron. The cooling jacket 3 made by casting has a cast surface, and therefore has a relatively large surface roughness. When the surface roughness is large, the surface area tends to increase, which is advantageous from the viewpoint of heat transfer. The cooling jacket 3 may be made by three-dimensional molding instead of casting. The outer housing 32 surrounds the inner housing 31. The inner housing 31 is fixed to the outer housing 32 by bolts.

[0028] The inner housing 31 has a spiral flow passage groove 311 provided on the outer circumferential surface of the inner housing 31. In other words, the flow passage grooves 311 are each formed continuously so as to revolve around the axis L of the rotating shaft 21 as the center.

[0029] The opening of the flow passage groove 311 is closed by the inner circumferential surface of the outer housing 32. In other words, the inner circumferential surface of the outer housing 32 is in close contact with the outer circumferential surface of the inner housing 31.

[0030] The inverter 9 supplies so-called three-phase AC power to the motor 2. The inverter 9 is connected to the motor 2 via three power lines 8. The three power lines 8 correspond to the so-called U phase, V phase, and W phase.

[0031] Fig. 2 is a circuit diagram of the inverter 9 shown in Fig. 1. The inverter 9 outputs three-phase AC power by controlling the on / off of multiple switching elements. The inverter 9 has a power supply unit 91, a U-phase leg 92, a V-phase leg 93, and a W-phase leg 94.

[0032] The power supply unit 91 includes DC power supplies 911 and 912. The DC power supply 911 generates a positive voltage (+Vdc / 2). The DC power supply 912 generates a negative voltage (-Vdc / 2). The negative electrode of the DC power supply 911 is connected to the positive electrode of the DC power supply 912, and the negative electrode of the DC power supply 911 and the positive electrode of the DC power supply 912 are both connected to a reference potential 913.

[0033] U-phase leg 92 has a U-phase upper arm 921 and a U-phase lower arm 922. U-phase upper arm 921 and U-phase lower arm 922 are each formed by a switching element. U-phase upper arm 921 and U-phase lower arm 922 are connected in series. A U-phase output terminal 923 is provided on a line connecting U-phase upper arm 921 to U-phase lower arm 922. U-phase output terminal 923 is connected to U-phase power line 8U.

[0034] The V-phase leg 93 and the W-phase leg 94 have the same configuration as the U-phase leg 92. That is, the V-phase leg 93 has a V-phase upper arm 931 and a V-phase lower arm 932. A V-phase output terminal 933 is provided on the line connecting the V-phase upper arm 931 to the V-phase lower arm 932. The V-phase output terminal 933 is connected to the V-phase power line 8V. The W-phase leg 94 has a W-phase upper arm 941 and a W-phase lower arm 942. A W-phase output terminal 943 is provided on the line connecting the W-phase upper arm 941 to the W-phase lower arm 942. The W-phase output terminal 943 is connected to the W-phase power line 8W.

[0035] 2 also shows an equivalent circuit of the motor 2, which includes the inductor 24 and an induced voltage generating element 25. The induced voltage generating element 25 visualizes the induced voltage generated by the rotation of the rotor 22 for the purpose of explanation.

[0036] The inverter 9 shown in Fig. 2 repeats six operation modes M1 to M6 shown in the table of Fig. 3. Fig. 4(a) shows the phase of the rotor 22 in each of the operation modes M1 to M6. Fig. 4(b), Fig. 4(c), and Fig. 4(d) show the U-phase voltage, V-phase voltage, and W-phase voltage in each of the operation modes M1 to M6.

[0037] When "voltage detection" is written in the table of Fig. 3, the inverter 9 does not operate, but performs an operation of detecting the induced voltage from the motor 2. For example, in the operation mode M1, the U phase is in "voltage detection". Therefore, the pulse-shaped graphs G4b, G4c, and G4d shown in Fig. 4(b), Fig. 4(c), and Fig. 4(d) show the induced voltage of the motor 2.

[0038] The operation modes M1 to M6 are switched in sequence based on the timing when the reference voltage is exceeded. For example, when the phase advances by 30 degrees from the timing when the induced voltage exceeds zero, the operation modes are switched in sequence to the next operation modes M1 to M6. The timing when the induced voltage exceeds zero can be known by judging the so-called zero crossing. The zero crossing can be judged from the induced voltage output by each phase that detects the voltage.

[0039] In the examples shown in Figures 4(b), 4(c), and 4(d), the induced voltage is shown as a pulse-like waveform. Zero-crossings can be determined by either an analog circuit or digital processing. When using an analog circuit, the pulse-like signal indicating the induced voltage is passed through a low-pass filter. When using digital processing, a microcomputer is used to obtain the detected voltage in accordance with the MWM period.

[0040] The reason why the induced voltage is output as a pulse waveform as shown in FIGS. 4(b), 4(c) and 4(d) will be described.

[0041] For example, operation mode M1 will be taken as an example for detailed description. In operation mode M1, the U phase is in a voltage detection operation for detecting an induced voltage, the V phase is in a switching operation for outputting a PWM signal, and the W phase is in a conductive operation in which the W-phase upper arm 941 is always ON. In operation mode M1 in which these operations are performed, the V-phase lower arm 932 repeatedly turns ON or OFF. The V-phase upper arm 931 and the V-phase lower arm 932 operate in a complementary manner. This complementary operation makes it possible to suppress inverter loss during reflux.

[0042] First, when the switching element constituting V-phase lower arm 932 is ON, switching element 931S constituting V-phase upper arm 931 is OFF. Fig. 5 shows a first state in which V-phase lower arm 932 is ON and V-phase upper arm 931 is OFF in operation mode M1. In the first state shown in Fig. 5, the average value of the output voltage of inverter 9 is the reference potential (GND). Furthermore, in the first state, the intermediate potential of motor 2 is also the reference potential (GND). In the first state, the voltage detected in U-phase is only the induced voltage.

[0043] Next, when the switching element constituting V-phase lower arm 932 is OFF, switching element 931S constituting V-phase upper arm 931 is ON. Fig. 6 shows a second state in which V-phase lower arm 932 is OFF and V-phase upper arm 931 is ON in operation mode M1. In the second state shown in Fig. 6, the average value of the output voltage of inverter 9 is a positive voltage (+Vdc / 2). Furthermore, in the second state, the intermediate potential of motor 2 is also a positive voltage (+Vdc / 2). And, in the second state, the voltage detected in U-phase is a positive voltage (+Vdc / 2).

[0044] Here, if the induced voltage is positive, a positive voltage (+Vdc / 2) is added to the induced voltage, which exceeds the positive voltage (+Vdc / 2) output by DC power supply 911. In this case, a flywheel diode (not shown) provided in U-phase upper arm 921 is energized. As a result, the maximum value of the voltage detected in the U-phase becomes a positive voltage (+Vdc / 2).

[0045] To summarise the first and second states, the ON / OFF switching operation of the V-phase lower arm 932 in the operation mode M1 causes the intermediate potential of the motor 2 to become a pulsed signal which goes back and forth between the reference potential (GND) and a positive voltage (+Vdc / 2). As a result, the voltage detected in the U-phase also becomes a pulsed signal.

[0046] As described above, the operation modes M1 to M6 shown in Fig. 2 are switched sequentially based on the zero-cross timing. Therefore, accurately grasping the zero-cross timing is an important issue in controlling the motor 2 in sensorless operation.

[0047] According to an ideal circuit, the waveform of the induced voltage for obtaining the timing of the zero crossing is as shown in FIG. 4(b), FIG. 4(c), and FIG. 4(d). However, in an actual circuit, so-called parasitic resistance and parasitic capacitance exist. FIG. 7 is a circuit diagram showing an equivalent circuit when the U-phase is the voltage detection phase. As shown in FIG. 7, the equivalent circuit for detecting the induced voltage includes an inductor 24 caused by the winding of the motor 2, a parasitic resistance element 8R caused by the U-phase power line 8U connecting the motor 2 and the inverter 9, and parasitic capacitance elements 931C and 932C caused by the switching elements 931S and 932S.

[0048] These electrical elements form a so-called LCR series circuit. The LCR series circuit has a natural resonant frequency. When the switching frequency of the switching element approaches the resonant frequency of the equivalent circuit, the induced voltage contains noise caused by the resonance.

[0049] The graph in Figure 8 is an example of the measured value of the induced voltage. Graph G8 includes several peaks P8. The multiple peaks P8 are high-frequency noise components caused by resonance. If such noise components are included in the waveform of the induced voltage, it will affect the determination of the zero crossing.

[0050] In other words, if the switching frequency of the inverter 9 is increased in accordance with the increased speed of the motor 2, the frequency approaches the resonant frequency of the circuits included in the inverter 9 and the motor 2, and as a result, noise caused by resonance is superimposed on the induced voltage. When noise is superimposed on the induced voltage, it affects the determination of the zero crossings required for controlling the motor 2. As a result, the motor 2 is prevented from rotating at a higher speed.

[0051] Therefore, the rotating machine system 100 of the embodiment has a configuration for suppressing noise caused by resonance. Specifically, the Q value, which indicates the degree to which the amplitude increases due to resonance, is reduced. Refer again to the equivalent circuit shown in Fig. 7. The Q value of this equivalent circuit is expressed by equation (1). Q = ω × L / R (1) Q: Quality factor. ω: switching frequency. L: Motor 2 inductor. R: Parasitic resistance.

[0052] According to the formula (1), it can be seen that in order to reduce the Q value on the left side, the parasitic resistance R included in the denominator on the right side should be increased. Therefore, the rotating machine system 100 has a configuration for increasing the value of the parasitic resistance element 8R shown in the equivalent circuit of FIG.

[0053] FIG. 9(a) is an enlarged cross-sectional view of the stator 23 of the motor 2. The outer periphery of the stator 23 is in contact with the cooling jacket 3. The cooling jacket 3 is provided with a flow groove 311. The flow groove 311 includes a flow inlet 301 connected to the supply pipe 41 to receive fresh cooling medium, and a flow outlet 302 connected to the flow outlet 302 to discharge the cooling medium that has absorbed heat. As described above, the flow groove 311 is formed in a spiral shape as a whole. Strictly speaking, since the shape of the flow groove 311 is spiral, the cooling medium also flows in a spiral shape according to the shape of the flow groove 311. From a macroscopic perspective, the cooling medium flows from the flow inlet 301 to the flow outlet 302. Therefore, it can be said that the cooling medium flows in a direction E1 from the right side of the paper surface to the left side of the paper surface in FIG. 9(a). This direction E1 is based on the rotation axis L. In the following description, the direction E1 in which the cooling medium flows is defined as a direction based on the rotation axis L.

[0054] The stator core 231 (stator main body) includes a plurality of thick steel plates 233 (first metal plates) of two types having different thicknesses and a plurality of thin steel plates 234 (second metal plates). The plurality of thick steel plates 233 and the plurality of thin steel plates 234 are laminated. The number of the thick steel plates 233 is smaller than the number of the thin steel plates 234. In other words, the stator core 231 has a laminated steel plate structure.

[0055] 9(b), which shows an enlarged view of the main part K in FIG. 9(a), an insulating coating 235 (insulating member) is formed on the surface of the thick steel plate 233 and the thin steel plate 234. The insulating coating 235 is, for example, an adhesive that bonds the steel plates together. Therefore, the thick steel plates 233 are not in direct contact with each other. In other words, the thick steel plate 233 is electrically insulated from the adjacent thick steel plate 233. The same is true for the thin steel plates 234. With this configuration, eddy currents generated in the thick steel plate 233 and the thin steel plate 234 can be suppressed. In other words, the stator core 231 includes a plurality of regions that are electrically isolated from each other. With this structure, loss in high-frequency currents can be reduced.

[0056] The thick steel plate 233 has a first thickness, and the thin steel plate 234 has a second thickness. The first thickness is larger than the second thickness. This difference in thickness results in a difference in the degree of loss for high-frequency current. The loss occurring in the thick steel plate 233, which is the first thickness, is larger than the loss occurring in the thin steel plate 234, which is the second thickness. In other words, a normal stator core is made of only the thin steel plate 234 in order to reduce the loss for high-frequency current. On the other hand, the stator core 231 of this embodiment intentionally uses the thick steel plate 233 to bias the degree of loss for high-frequency current. This high-frequency current corresponds to the noise component superimposed on the induced voltage described above. The stator core 231 intentionally uses the thick steel plate 233, which is thicker, in order to suppress the noise component superimposed on the induced voltage.

[0057] According to such a configuration, noise components superimposed on the induced voltage are reduced by being converted into heat in the thick steel plate 233. In other words, the region 233S including the thick steel plate 233 having a large thickness generates more heat than the region 234S including the thin steel plate 234 having a small thickness.

[0058] Here, attention is paid to the structure of the stator core 231 with respect to the cooling jacket 3 described above. In the example of FIG. 9(a), the region 233S with a large amount of heat generation is located on the right side of the paper. In other words, the region 233S with a large amount of heat generation is provided on the flow path inlet 301 side. The amount of heat that moves from the stator core 231 to the cooling medium (heat medium) is determined by the difference (temperature difference) between the temperature of the stator core 231 and the temperature of the cooling medium. Specifically, the larger the temperature difference, the larger the amount of heat that moves. The closer to the flow path inlet 301 that receives the cooling medium with a relatively low temperature, the more advantageous it is for cooling. Therefore, according to a configuration in which a fresh cooling medium with a relatively low temperature is supplied to the region 233S with a large amount of heat generation, higher cooling performance can be obtained. In other words, the heat caused by the noise components superimposed on the induced voltage can be efficiently discharged to the outside.

[0059] The motor 2 includes a rotor 22 and a stator 23 provided with a plurality of coils. The stator 23 includes a stator core 231 in which a thick steel plate 233 and a thin steel plate 234 are laminated. The thickness of the thick steel plate 233 is greater than the thickness of the thin steel plate 234.

[0060] The motor 2 includes a stator 23 including a physically thick steel plate 233. The thick steel plate 233 acts as a resistance to high-frequency current. As a result, high-frequency noise components superimposed on signals used to control the rotation of the motor 2 are reduced. This allows the motor 2 to rotate at high speed.

[0061] <Second embodiment> The noise components superimposed on the induced voltage are reduced by loss occurring in the thick steel plate 233. This loss is determined by the electrical thickness of the thick steel plate 233, not the physical thickness of the thick steel plate 233. In the first embodiment, the multiple thick steel plates 233 are electrically separated by the insulating coating 235. Therefore, the physical thickness of the thick steel plate 233 is the same as the electrical thickness of the thick steel plate 233.

[0062] 10 is an enlarged cross-sectional view of a stator core 231A included in a motor 2A of the second embodiment. The stator core 231 has a plurality of uniform thickness steel plates 237. All of the plurality of uniform thickness steel plates 237 have the same thickness. In other words, the thickness of the uniform thickness steel plates 237 constituting the region 233S that actively generates loss for high-frequency current is the same as the thickness of the uniform thickness steel plates 237 constituting the region 234S that has relatively little loss for high-frequency current.

[0063] The uniform thickness steel plate 237 constituting the region 234S where loss in the high frequency current is relatively small has an insulating coating 235 formed on both sides. In other words, the uniform thickness steel plate 237 is electrically insulated from the adjacent uniform thickness steel plate 237. Therefore, the physical thickness of the uniform thickness steel plate 237 is the same as the electrical thickness of the uniform thickness steel plate 237.

[0064] In contrast, the uniform thickness steel plate 237 constituting the region 233S that actively generates loss for high-frequency current has an insulating surface 236b on which the insulating coating 235 is provided, and a conductive surface 236a (connection surface) on which the insulating coating 235 is not provided. In this way, a configuration is formed in which the conductive surfaces 236a on which the insulating coating 235 is not provided are in contact with each other in the adjacent uniform thickness steel plates 237. As a result, the uniform thickness steel plate 237 can be regarded as electrically equivalent to a single thick steel plate 233 having a large thickness. As a result, the thickness of the uniform thickness steel plate 237 constituting the region 233S that actively generates loss for high-frequency current is electrically greater than the physical thickness of the uniform thickness steel plate 237.

[0065] The two uniform thickness steel plates 237 only need to be electrically conductive. Therefore, the entire surface of the conductive surface 236a may be in direct contact with the conductive surface 236a of another adjacent uniform thickness steel plate 237. Also, a part of the conductive surface 236a may be in direct contact with the conductive surface 236a of another adjacent uniform thickness steel plate 237. In other words, the conductive surfaces 236a include a conductive region 236c (conductive portion) that contact each other without the insulating coating 235 therebetween, and an insulating region 236d that face each other via the insulating coating 235 (insulating portion).

[0066] Motor 2A includes rotor 22 and stator 23 provided with a plurality of coils. Stator 23 includes stator core 231 in which uniform thickness steel plates 237 are laminated. First uniform thickness steel plates 237 include portions that contact each other without insulating coating 235 therebetween so as to be electrically connected to each other. Second uniform thickness steel plates 237 face each other via insulating coating 235 so as to be electrically insulated from each other.

[0067] The motor 2A includes a stator 23 including a plurality of uniform thickness steel plates 237 electrically connected to each other. With this configuration, an electrically thick steel plate is formed. The electrically thick steel plate acts as a resistance to high frequency current. As a result, high frequency noise components superimposed on the signal used to control the rotation of the motor 2A are reduced. Therefore, the motor 2A can be rotated at high speed.

[0068] <Third embodiment> In the first and second embodiments, the electrical thickness of the steel plate is increased to actively cause loss in the high-frequency current. The difference in loss in the high-frequency current is not limited to the difference in electrical thickness of the steel plate. For example, the difference in loss in the high-frequency current may be caused by the difference in the material constituting the steel plate.

[0069] Fig. 11(a) is an enlarged cross-sectional view of a stator core 231B included in a motor 2B of the third embodiment. As shown in Fig. 11(a), the stator core 231B has a first metal plate 238 and a second metal plate 239. The thickness of the first metal plate 238 may be the same as or different from the thickness of the second metal plate 239. For example, a silicon steel plate can be used as the material of the first metal plate 238. For example, ferrite can be used as the material of the second metal plate 239.

[0070] The motor 2B includes a rotor 22 and a stator 23 provided with a plurality of coils. The stator 23 includes a stator core 231B in which a first metal plate 238 and a second metal plate 239 are laminated. The first metal plate 238 is made of a first material. The second metal plate 239 is made of a second material different from the first material. The resistance value of the first material to high-frequency current is greater than the resistance value of the second material to high-frequency current.

[0071] The motor 2B includes a stator 23 including a first metal plate 238 formed of a material having a high resistance to high-frequency current. As a result, high-frequency noise components superimposed on signals used to control the rotation of the motor 2B are reduced. This allows the motor 2B to rotate at a higher speed. In other words, the motor 2B of the third embodiment can also reduce noise components by eddy current loss generated in the first metal plate 238 made of a material having a high resistance to high-frequency current.

[0072] The present disclosure is not limited to the above-described embodiment, and various modifications as described below are possible without departing from the gist of the present disclosure.

[0073] In the stator core 231 of the first embodiment, the first metal plate 238 having a large thickness is disposed on one end side along the direction of the rotation axis L. The arrangement of the first metal plate 238 is not limited to this arrangement.

[0074] For example, as shown in Fig. 11(b), thick steel plates 233 may be disposed on both ends of a stator core 231C included in a motor 2C of Modification 1. That is, the stator core 231C includes a first stator end face 231a and a second stator end face 231b on the opposite side to the first stator end face 231a. The first stator end face 231a is formed of the thick steel plate 233. The second stator end face 231b is also formed of the thick steel plate 233.

[0075] Contrary to the stator core 231C, thin steel plates 234 may be arranged on both ends of a stator core 231D included in a motor 2D of Modification 2, as shown in FIG. 11(c). The stator core 231D includes a first stator end face 231a and a second stator end face 231b. The first stator end face 231a and the second stator end face 231b are formed of thin steel plates 234.

[0076] Furthermore, as shown in FIG. 11(d), a stator core 231E included in a motor 2E of the third modification may include a portion in which thick steel plates 233 and thin steel plates 234 are alternately laminated.

[0077] Furthermore, the configuration for actively generating losses in high-frequency current may be a combination of the configuration based on the thickness of a single steel plate shown in the first embodiment, the configuration in which multiple steel plates are electrically connected as shown in the second embodiment, and the configuration based on the steel plate material as shown in the third embodiment. [Explanation of symbols]

[0078] 1 Rotating Machinery 2. Motor (electric motor) 3 Cooling jacket (cooling section) 9. Inverter (power conversion device) 22 Rotor 23 Stator 231 Stator core (stator body) 232 Stator coil (coil) 233 Thick steel plate (first metal plate) 234 Thin steel plate (second metal plate) 235 Insulating coating (insulating material) 236a Conductive surface (connection surface) 236c Conduction area (conduction part) 236d Insulating area (insulating part) 237 Equal thickness steel plate 238 First Metal Plate 239 Second Metal Plate

Claims

1. a stator body portion in which a plurality of metal plates including a first metal plate and a second metal plate are stacked; a coil provided in the stator body, the first metal plates include portions that are in contact with each other without an insulating member therebetween so as to be electrically connected to each other; A stator, wherein the second metal plates face each other via the insulating member so as to be electrically insulated from each other.

2. The pair of first metal plates includes connection surfaces facing each other, The stator according to claim 1 , wherein the connection surfaces include conductive portions that contact each other without the insulating member therebetween and insulating portions that face each other via the insulating member.

3. A rotor, A stator according to claim 1 or 2; a cooling section through which a heat medium for cooling the stator flows, an electric motor, wherein the first metal plates are arranged upstream of the second metal plates in a flow direction of the heat medium.

4. a stator body portion in which a plurality of metal plates including a first metal plate and a second metal plate are stacked; a coil provided in the stator body, A stator, wherein the thickness of the first metal plate is greater than the thickness of the second metal plate.

5. the stator body portion includes a first stator end surface and a second stator end surface opposite to the first stator end surface, The stator according to claim 4 , wherein the first stator end surface and the second stator end surface are formed by the second metal plate.

6. the stator body portion includes a first stator end surface and a second stator end surface opposite to the first stator end surface, the first stator end surface is formed by the first metal plate, The stator according to claim 4 , wherein the second stator end surface is formed by the second metal plate.

7. a stator body portion in which a plurality of metal plates including a first metal plate and a second metal plate are stacked; a coil provided in the stator body, the first metal plate is made of a first material; the second metal plate is made of a second material different from the first material; A stator, wherein the first material has a resistance to high frequency current that is greater than the resistance of the second material to high frequency current.

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