JP7718334B2 - Stator and motor - Google Patents

Description

This disclosure relates to a stator and a motor.

In recent years, electrification has progressed in the automotive field to reduce _CO2 emissions, and it is predicted that electrification will continue to advance in the future. Here, motors, which provide driving force, are required to be highly efficient in order to reduce energy consumption. Furthermore, miniaturization of motors is also required in order to make them easier to install in automobiles.

To make effective use of metal resources, the copper winding material and iron-based electromagnetic steel sheets are separated from used motor cores and reused in products. However, to improve motor performance, the windings must be wound around the motor core with a high space factor. Completely separating windings wound with a high space factor from the motor core and reusing the resources requires a great deal of effort and cost. In some cases, the windings are molded in resin, making it impossible to separate the iron and copper, which can lead to copper being mixed with the iron. Furthermore, the spread of electric vehicles as mentioned above is putting a strain on the supply and demand of copper. Not only is the unit price of copper increasing rapidly, but there is also the possibility of resource depletion. Therefore, in order to reduce motor costs and utilize other resources, a switch from copper to aluminum as the winding material is being considered.

Aluminum has an electrical resistivity approximately 1.6 times that of copper, so simply replacing copper with aluminum as the winding material increases copper loss by approximately 1.6 times, resulting in a decrease in motor efficiency. Against this background, Patent Document 1 proposes a technology to reduce copper loss by using permanent magnets containing rare earth elements such as dysprosium and having a residual magnetic flux density of 1.32 T to 1.39 T.

Patent No. 6692896 specification

However, using permanent magnets containing rare earth elements such as dysprosium increases costs, negating the cost reduction benefits of changing the winding material to aluminum.

Furthermore, from the perspective of resource recyclability, aluminum has a lower cost per weight than copper, so the cost of separating and recovering aluminum from used motors is not worth the material's value.

As described above, when using aluminum as the winding material, it was difficult to achieve both good motor characteristics, economic efficiency, and resource recyclability.

This disclosure was made in light of these circumstances, and aims to provide a stator that uses aluminum as the winding material and has excellent motor characteristics, economy, and resource recyclability.

The inventors conducted extensive research to achieve the above objectives. As a result, they discovered the following and arrived at the present invention.

A winding made of an aluminum alloy containing 99.6% or more of Al;
By using a stator core made of electromagnetic steel sheet with an integrated magnetic flux density IB(500) of 90,000 (TA/m) or more and an integrated magnetic flux density IB(5) of 550 (TA/m) or more, the stator core and winding material can be effectively recycled as scrap iron without separating them, and excellent motor characteristics can be achieved.

This disclosure is based on the above findings. Specifically, the gist of this disclosure is as follows:

[1] A stator core formed by laminating electromagnetic steel sheets;
a winding wound around the stator core,
the winding is made of an aluminum alloy containing, by mass%, 99.6% or more of Al and 0.001% or more and 0.15% or less of Cu,
The stator, wherein the integrated magnetic flux density IB(500) of the electromagnetic steel sheet is 90,000 TA/m or more and the integrated magnetic flux density IB(5) is 550 TA/m or more.
Here, the integrated magnetic flux density IB(500) refers to the integral value of the magnetic flux density (T) in the range where the magnetic field strength H is 0 A/m to 50,000 A/m,
The integrated magnetic flux density IB(5) indicates the integral value of the magnetic flux density (T) in the range of the magnetic field strength H from 0 A/m to 500 A/m.

[2] The stator described in [1], wherein the ratio D/h of the stack height h of the stator core to the outer diameter D is 1.0≦D/h≦3.0.

[3] The slot space factor of the winding is 60% or more,
The stator according to [1] or [2], wherein an iron loss W _10/400 (W/kg) when an external stress of 10 MPa is applied in a direction perpendicular to the magnetic flux of the electromagnetic steel plate is equal to or less than an iron loss W _10/400 (W/kg) when an external stress of 0 MPa is applied.

[4] A stator described in any one of [1] to [3] above, wherein the layers of the electromagnetic steel sheets are bonded together at an area ratio of 85% or more.

[5] The electromagnetic steel sheet has a punched shear surface,
a corner of the electromagnetic steel sheet that comes into contact with the winding is on the punched shear surface side,
The stator according to any one of [1] to [4], wherein the stator does not include insulating paper.

[6] The stator according to any one of [1] to [5], wherein the electromagnetic steel sheet contains, by mass%, Cu: 0.001% or more and 1.0% or less.
[7] A motor having the stator according to any one of [1] to [6].

This disclosure makes it possible to provide a stator that uses aluminum as the winding material and has excellent motor characteristics, economy, and resource recyclability.

10A and 10B are diagrams for explaining a measurement example of a DC BH curve and a method for determining an integrated magnetic flux density IB. FIG. 10 is a diagram showing an example of measurement of DC BH curves for a plurality of electrical steel sheets. FIG. 2 is a diagram schematically illustrating the configuration of a test motor. 10 is a diagram for explaining the positional relationship between a winding and a punched shear surface of an electromagnetic steel sheet. FIG. 1 is a graph showing the relationship between integrated magnetic flux density and torque in Example 1. 10 is a graph showing the relationship between D/h and torque in an example of the invention according to Example 2. 10 is a graph showing the relationship between the ratio of iron loss (W _10/400 ) when a stress of 10 MPa is applied to iron loss (W _10/400 ) when no stress is applied and the change in motor efficiency in Example 3. 10 is a graph showing the relationship between the adhesive area ratio (%) and the changes in motor noise (dB) and motor efficiency in Example 4.

Embodiments of the present disclosure are described below. Note that the present invention is not limited to the following embodiments. In the following description, "%" representing the content of a component element means "% by mass" unless otherwise specified. Furthermore, in this specification, a numerical range expressed using "to" means a range that includes the numerical values written before and after "to" as the lower and upper limits.

The stator comprises a stator core made of laminated electromagnetic steel sheets and windings wound around the stator core. As shown in Figure 3, in one example, the stator core 10 has a circular or cylindrical back yoke 11 and teeth 13 spaced apart in the circumferential direction on the inner surface of the back yoke 11 to define slots 12, with windings wound around the teeth 13.

[Winding]
First, the windings wound around the stator core will be described.

The windings are made of an aluminum alloy with 99.6% or more Al. The high Al content of the windings reduces the resistance of the windings and reduces copper loss (aluminum loss). Of the losses in a motor, copper loss (aluminum loss) is generally expressed by the following formula (1): P _Cu = RI ²
=ρL/S×I ² ...Formula (1)
Here, R (Ω): winding resistance, I (Arms): motor current, ρ (Ω·m): specific resistance of the winding material, L (m): winding length, and S (m ² ): winding cross-sectional area.

Furthermore, by using an aluminum alloy with a high Al content, i.e., with few impurity elements, for the windings, the windings from used motors can be disposed of as scrap iron without having to be separated from the motor core. This is because Al is used as an element to improve the magnetic properties of electrical steel sheets, and is an element that is actively added when manufacturing electrical steel sheets in electric furnaces, etc.

The Cu content of the aluminum alloy must be between 0.001% and 0.15%. If a large amount of Cu is mixed in when a used motor is turned into iron scrap, it is difficult to remove the Cu from the steel. This mixed Cu hinders grain growth when the iron scrap is turned back into electrical steel sheet, degrading the magnetic properties of the electrical steel sheet. Therefore, the Cu content of the aluminum alloy must be 0.15% or less. On the other hand, adding Cu to the aluminum alloy has the effect of improving strength, which is effective when winding the windings around the stator core with a high space factor. For this reason, the Cu content must be 0.001% or more.

[Stator core]
Next, we will explain the requirements for the electromagnetic steel sheets that make up the stator core and the reasons for their limitations. Note that the effects of the invention can be achieved as long as the electromagnetic steel sheets have the specified magnetic properties, and the effects of the invention do not depend on other components, sheet thickness, or manufacturing method.

The Cu content of electrical steel sheet is preferably 0.001% or more and 1.0% or less. Reducing the amount of Cu mixed in when used motors are turned into iron scrap makes it easier to remove Cu from the steel. Furthermore, reducing the amount of Cu mixed in iron scrap effectively prevents Cu from interfering with grain growth when the iron scrap is turned into electrical steel sheet again, further improving the magnetic properties of the electrical steel sheet. Therefore, the Cu content of electrical steel sheet is preferably 1.0% or less. On the other hand, because Cu increases the strength of the steel sheet and contributes to higher motor rotation speeds, the Cu content is preferably 0.001% or more.

Integral magnetic flux density IB(500): 90,000 TA/m or more Integral magnetic flux density IB(5): 550 TA/m or more In order to reduce the current in the above formula (1), it is important to reduce the motor current. By using a material with an integral magnetic flux density IB(500) of 90,000 TA/m and an integral magnetic flux density IB(5) of 550 TA/m or more, motor torque can be improved over a wide range from low to high torque, motor current can be reduced, and copper loss (aluminum loss) can be reduced. The integral magnetic flux density IB(500) is preferably 95,000 or more, more preferably 100,000 or more. The integral magnetic flux density IB(5) is preferably 600 or more, more preferably 620 or more. The upper limit of the integral magnetic flux density IB(500) is not particularly limited, but in one example, it is 150,000 or less. The upper limit of the integrated magnetic flux density IB(5) is not particularly limited, but is 700 or less in one example.

Here, the integrated magnetic flux density IB is a value obtained by the following measurement method.
(1) Measurement of DC B-H Curve The DC B-H curve is measured by measuring the magnetic flux density B (T) of the iron core material at the following magnetic field strengths H (A/m): For example, the DC B-H curve is measured using data at 0, 10, 20, 30, 40, 50, 60, 70, 80, 100, 125, 150, 175, 200, 250, 300, 400, 500, 800, 1000, 1500, 2000, 2500, 3000, 4000, 5000, 8000, 10000, 15000, 20000, 30000, and 50000 A/m.

(2) Perform numerical integration. The obtained DC B-H curve is integrated over the range of magnetic field strength H from 0 A/m to 500 A/m, and the obtained value is designated as IB(5). Similarly, the obtained B-H curve is integrated over the range of magnetic field strength H from 0 A/m to 50,000 A/m, and the obtained value is designated as IB(500).

The DC B-H curve can be measured by a ring measurement using an excitation coil and a search coil wound around the back yoke of the stator core, or by an Epstein test using the electromagnetic steel sheet to be used in the stator core. Figure 1 shows an example of a DC B-H curve measurement. The integrated magnetic flux density IB(5) corresponds to the area of the shaded area in Figure 1. Furthermore, Figure 2 shows examples of the integrated magnetic flux density evaluation using the above method for four types of electromagnetic steel sheet (corresponding to materials A, B, C, and D in Table 1). The integrated magnetic flux density IB does not necessarily tend to be larger or smaller than indicators such as _B50 , which are traditionally used as indicators of the magnetic flux density of electromagnetic steel sheets. When copper is used as the winding material, it is relatively easy to reduce the resistance of the winding. In contrast, when aluminum is used as the winding material, copper loss (aluminum loss) at low currents (torque conditions) can become an issue, which was not a problem when copper was used as the winding material. Through their own intensive research, the inventors have found that using electrical steel sheets with high integrated magnetic flux densities IB(5) and IB(500) is effective in improving loss at low currents.

The ratio D/h of the stack height h of the motor core to the outer diameter D: 1.0≦D/h≦3.0
According to Equation (1), thickening and shortening the winding wire is effective in reducing copper loss (aluminum loss). Adjusting the integral magnetic flux density IB(500) and the integral magnetic flux density IB(5) of the magnetic steel sheets to reduce the motor current and thickening and shortening the winding wire to reduce the winding resistance effectively reduces copper loss (aluminum loss). Shortening the lamination height h also shortens the winding length L, which is advantageous for reducing copper loss (aluminum loss). Furthermore, increasing the outer diameter D and expanding the slot area allows for the use of thicker winding wire, thereby increasing the cross-sectional area S of the winding while maintaining the winding length L, which is advantageous for reducing copper loss (aluminum loss). Therefore, a larger ratio D/h of the lamination height h to the outer diameter D is preferable from the perspective of suppressing copper loss (aluminum loss). Furthermore, to effectively prevent magnetic flux leakage in the lamination direction and further reduce copper loss (aluminum loss), D/h is set to 3.0 or less. More preferably, 1.5≦D/h. More preferably, D/h≦2.0.

- Slot space factor of the winding is 60% or more It is preferable that the slot space factor of the winding is 60% or more. By improving the slot space factor, the cross-sectional area S of the winding can be made larger, which is effective in reducing copper loss (aluminum loss). It is more preferable that the slot space factor is 50% or more. The slot space factor of the winding is defined by the following equation (2):
Slot space factor (%) = (conductor cross-sectional area + coating cross-sectional area) / (slot cross-sectional area - insulator cross-sectional area) × 100 (2)

The slot space factor can be evaluated by cutting the stator and performing image analysis of the cross section.

In particular, it is preferable that the cross-sectional shape of the winding wire is rectangular (flat wire). A rectangular cross-sectional shape of the winding wire makes it easier to apply the winding wire to the stator core with a high space factor.

While there is no particular upper limit to the slot space factor of the winding, it is preferable to set it at 90% or less. Setting the slot space factor at 90% or less effectively prevents the winding from applying stress to the electromagnetic steel sheets during sudden heat generation and temperature increases. When a large current is applied during driving, such as when starting or traveling uphill, sudden heat generation due to heat generation from the winding can occur. Compared to copper, aluminum has a higher resistance to the winding, so a large amount of heat is generated when current is passed through it. Furthermore, aluminum has a low thermal conductivity, making it difficult to cool and prone to temperature increases. Furthermore, the thermal expansion coefficient of aluminum (23.9 x 106/°C) is greater than that of copper (16.5 x 106/°C). During sudden heat generation and temperature increases, the thermally expanded winding can apply stress to the electromagnetic steel sheets. However, setting the slot space factor at 90% or less provides sufficient space, effectively preventing the winding from applying stress to the electromagnetic steel sheets.

The iron loss W10 _/400 (W/kg) when an external stress of 10 MPa is applied in a direction perpendicular to the magnetic flux of the electromagnetic steel sheets is less than or equal to the iron loss W10 _/400 (W/kg) when an external stress of 0 MPa is applied It is preferable that the iron loss W10 _/ 400 (W/kg) when an external stress of 10 MPa is applied in a direction perpendicular to the magnetic flux is less than or equal to the iron loss W10 _/400 (W/kg) when an external stress of 0 MPa is applied. Even when stress is applied to the electromagnetic steel sheets due to thermal expansion of the windings, by keeping the iron loss less than or equal to the iron loss when no stress is applied, it is possible to preferably prevent the motor characteristics from deteriorating when the above-mentioned stress is applied.

The iron loss W10 _/400 (W/kg) when an external stress of 10 MPa is applied in a direction perpendicular to the magnetic flux of the electrical steel sheet, and the iron loss W10 _/400 (W/kg) when an external stress of 0 MPa is applied, are evaluated as follows. The evaluation method is single sheet evaluation. The iron loss is evaluated when an external stress of 10 MPa is applied in a direction perpendicular to the magnetic flux and the sheet is excited at 1.0 T and 400 Hz. In the case of Epstein evaluation, surface pressure is applied according to the single sheet evaluation method shown in Reference 1.
[Reference 1] Senda et al., "Study on magnetic measurement method under stress of electrical steel sheet," IEEJ Transactions on Electrical Engineering, Vol. 137, No. 11, pp. 654-660 (2017)

It is preferable that the electrical steel sheets are laminated by bonding (glue lamination). This is because adhesive lamination allows the electrical steel sheets to be free of areas that have been plastically processed, such as by crimping, and allows for a higher integrated magnetic flux density to be obtained.

The layers of the electromagnetic steel sheets are bonded with an area ratio of 85% or more. When adhesively laminated, it is preferable that the layers of the electromagnetic steel sheets be bonded with an area ratio of 85% or more. Adhesively laminating with an area ratio of 85% or more can increase the rigidity of the stator core. Therefore, when the high-space-factor windings thermally expand, the stress applied to the stator core is more uniform than when laminated using caulking or other methods, and deterioration of magnetic properties when stress is applied can be more effectively suppressed. In particular, even when the D/h ratio is 1.0≦D/h≦3.0, the rigidity of the stator core can be increased compared to when laminated using caulking or other methods, and increases in motor vibration and noise due to electromagnetic excitation force can be more effectively suppressed. Note that adhesives commonly used for cut cores can be used, including acrylic and epoxy-based adhesives. The adhesive area ratio between the layers of the electromagnetic steel sheets is measured as follows. The laminated electromagnetic steel sheets are peeled off, and the area of adhesive remaining on the peeled surface of the two previously bonded electromagnetic steel sheets is evaluated. The reason for evaluating the two electromagnetic steel sheets is that there is a possibility of peeling at the interface between the electromagnetic steel sheets and the adhesive when they are peeled off. The ratio of the adhesive area evaluated in this way to the area of the stator core is evaluated as a percentage.

The corners of the electromagnetic steel sheets that come into contact with the windings are positioned on the punched shear surface side. When electromagnetic steel sheets are punched into a stator core, each electromagnetic steel sheet S after processing has a punched shear surface and a fracture surface, as shown in FIG. 4 . The fracture surface may have burrs, and if the burrs come into contact with the windings A, the insulation of the windings A may be destroyed. In particular, when the windings A have a rectangular cross section, the windings A may be shaped by inserting a hairpin-shaped winding A into a slot, bending the tip that protrudes from the electromagnetic steel sheet, and welding it to the tip of the adjacent winding A. In such a process, if the burrs are present on the end surface on the bent side, they may come into contact with the bent windings, causing insulation breakdown. Therefore, by positioning the punched shear surface side on the bent side of the windings as shown in FIG. 4 , a stator with a lower risk of insulation breakdown can be provided.

To prevent dielectric breakdown, it is common to apply insulating paper to cover the cross section of the electromagnetic steel sheet in the slot before winding the winding. By placing the corners of the electromagnetic steel sheet that come into contact with the winding on the punched shear surface side, the stator does not need to have insulating paper. Not using insulating paper in the stator can further reduce manufacturing costs. Furthermore, not using insulating paper allows the winding to be designed to be thicker, which reduces copper loss (aluminum loss) that is a problem with windings made from aluminum alloys, and further improves motor performance.

It is preferable that the stator be subjected to a varnish impregnation treatment after windings are applied to the stator core.

Example 1: Effect of Integral Magnetic Flux Density. The magnetic steel sheets shown in Table 1 were laminated and punched to prepare the stator shown in Figure 3. An 8-pole, 48-slot IPM motor with an outer diameter D of 200 mm and a lamination thickness h of 100 mm was fabricated. The DC B-H curves for the magnetic steel sheets were determined in advance using an Epstein test, and the integral magnetic flux density IB(5) and the integral magnetic flux density IB(500) were evaluated. The windings used rectangular aluminum alloy wires composed of 99.7% Al and 0.05% Cu. The slot space factor of the windings was 65%. The torque of the motors fabricated using each magnetic steel sheet was measured at a rotational speed of 1500 rpm and currents of 300 A and 50 A. The motors were mechanically connected to a load tester via a coupling and measured using a torque meter installed between the motor and the load tester. The torque for Material B was set to 100 (reference value), and the results are shown in Table 1. FIG. 5 shows a graph in which the horizontal axis represents the integrated magnetic flux density IB(5) and the integrated magnetic flux density IB(500) and the vertical axis represents the torque.

The results showed that the higher the integral magnetic flux density IB(5), the higher the torque at 50 A, and the higher the integral magnetic flux density IB(500), the higher the torque at 300 A. Furthermore, electrical steel sheets with an integral magnetic flux density IB(500) of 90,000 TA/m or more and an integral magnetic flux density IB(5) of 550 TA/m or more can deviate from the above correlation and produce significantly higher motor torque.

(Example 2) Effect of D/h A motor was fabricated with the outer diameter D and inner diameter d of the stator core as shown in Figure 3, and the D/h was varied by changing the stacking height. A rectangular aluminum alloy wire consisting of 99.7% Al and 0.05% Cu was used for the windings. The slot space factor was 65%, equivalent to that of Example 1. Table 2 shows the results of evaluating the torque when driven at a rotational speed of 1500 rpm and a current of 300 A, with the measured value for Material B set at 100 (reference). Figure 6 also shows the relationship between D/h and torque for Example 2, an example of the invention. Figure 6 reveals that the torque improvement effect is particularly significant when the condition 1.0≦D/h≦3.0 is satisfied.

(Example 3) Effect of iron loss under surface pressure For materials B, E, F, and G of Example 1, iron loss was evaluated in a single-plate test when an external stress of 10 MPa was applied in the direction perpendicular to the magnetic flux (surface pressure) and the materials were excited at 1.0 T and 400 Hz. Table 4 shows the ratio of iron loss when a stress of 10 MPa was applied to iron loss when no stress was applied. In addition, the efficiency of a motor using a stator having the outer diameter D and inner diameter d shown in Figure 3 and a lamination height h of 170 mm was evaluated using the following procedure. The slot space factor of the winding was 65%.
(1) Driven at 4000 rpm - 50 A: Motor efficiency measured in steady state (2) Driven at 4000 rpm - 300 A: Driven for 20 seconds (3) Driven at 4000 rpm - 50 A: Motor efficiency measured immediately after current change Note that motor efficiency is the ratio (Po(W)/Pi(W)) of the input power Pi (W) to the motor and the motor output Po (W) = torque T (Nm) x rotation speed (rpm) x 2π/60, evaluated as a percentage.

Table 3 shows the change in motor efficiency (percentage difference, hereafter referred to as points) between (1) and (3). Figure 7 also shows the relationship between the ratio of iron loss (W _10/400 ) when a stress of 10 MPa is applied to iron loss (W _10/400 ) without stress and the change in motor efficiency. The smaller the ratio of iron loss (W _10/400 ) when a stress of 10 MPa is applied to iron loss (W _10/400 ) without stress, the smaller the change in motor efficiency. In other words, the decrease in motor efficiency is small even immediately after driving under high current conditions such as (2). The reason for this difference in motor efficiency change depending on the material of the electromagnetic steel sheet is thought to be as follows: When the motor is driven in (2), the windings instantly heat up, and the aluminum used for the windings thermally expands, generating stress on the teeth, which changes the iron loss of the material itself and ultimately the motor iron loss. However, for materials E and F, which have good iron loss characteristics under surface pressure, there is little change in motor iron loss, i.e., motor efficiency, due to stress. On the other hand, for materials B and G, which have poor iron loss characteristics under surface pressure, there was a large change (deterioration) in motor efficiency. Note that in materials E and F, material evaluation showed that iron loss decreased when stress was applied, but motor efficiency decreased. This is thought to be because the increase in copper loss (aluminum loss) caused by an increase in resistivity ρ due to a rise in winding temperature offset the decrease in iron loss, with the former being greater.

(Example 4) Effect of Adhesion Area The effect of the processing method of the electromagnetic steel sheets on motor efficiency and noise was evaluated for the IPM motor shown in Figure 3. Using material F or B from Example 1 and using either caulking or adhesive lamination as the lamination method, motor noise (dB) and motor efficiency (%) were evaluated at a rotation speed of 4500 rpm and a torque of 50 Nm.
Here, the motor noise was evaluated by placing a sound level meter 0.5 m from the coil end in the extension direction of the motor's rotating shaft and comparing the overall noise value. The evaluation results of the motor manufactured by crimping were used as the standard, and the changes from these evaluation results are shown in Table 4. The relationship between the bonding area, motor noise (dB), and motor efficiency (%) is also shown in Figure 8.

In terms of motor efficiency and motor noise, better characteristics were obtained than in motors manufactured using crimping under all conditions. In particular, with material F, the greater the adhesive area, the greater the improvement in motor efficiency and motor noise. On the other hand, as shown in Table 3, under the conditions of material B, where iron loss increases with the application of stress, adhesive lamination achieved better motor characteristics than lamination using crimping, but no further improvement in motor characteristics was observed even when the adhesive area was increased. This is thought to be because the compressive stress caused by adhesive lamination had an adverse effect on magnetic properties, leading to increased iron loss and increased current due to reduced magnetic permeability.

Example 5: Effects of punched shear surfaces and insulating paper Next, the effects of punched shear surfaces and insulating paper on the IPM motor characteristics shown in Figure 3 were examined using Material A. Stators were formed from electromagnetic steel sheets by punching, laminated under the conditions shown in Table 5, and then windings were applied. Ten motors were fabricated for each condition, varying the winding material and whether or not insulating paper was used. The results of evaluating the rate at which short circuits occurred between the electromagnetic steel sheets and the windings are shown in Table 5. The rate at which short circuits occurred was determined by evaluating the resistance between the UVW phase motor terminals and the outer periphery of the stator core using a megaohm tester. A resistance of 1 kΩ or less was detected, determining that a short circuit had occurred.

When insulating paper was inserted, no short circuits occurred under any conditions. On the other hand, when insulating paper was not used and the winding was inserted in a direction that would cause contact with the burrs, short circuits occurred between the electromagnetic steel sheet and the winding. The rate of short circuits was higher for aluminum alloy windings than for windings made of copper (Cu ≥ 99.95%), a commonly used magnet wire material. This is thought to be due to the low strength of the aluminum alloy winding material, which causes the winding to stretch due to stress applied to the winding material during the winding process, thereby stretching the insulating coating and reducing its insulation performance. However, when the winding was inserted from the opposite direction to the burrs, i.e., when the corner of the electromagnetic steel sheet that contacts the winding was on the punched shear surface side, short circuits were suppressed even when the aluminum winding was wound without insulating paper. Thus, controlling the winding insertion direction can effectively suppress short circuits between the electromagnetic steel sheet and the winding without using insulating paper, thereby improving motor manufacturing yields. Furthermore, by not using insulating paper, the windings can be designed to be thicker, which reduces copper loss (aluminum loss), which is a problem when using windings made from aluminum alloy, and is effective in further improving motor performance.

10 stator core 11 back yoke 12 slot 13 teeth S electromagnetic steel sheet A winding

Claims (7)

a stator core formed by laminating electromagnetic steel sheets;
a winding wound around the stator core,
the winding is made of an aluminum alloy containing, by mass%, 99.6% or more of Al and 0.001% or more and 0.15% or less of Cu,
The integrated magnetic flux density IB(500) of the electromagnetic steel sheet is 90,000 TA/m or more and the integrated magnetic flux density IB(5) is 550 TA/m or more,
A stator in which the iron loss W _10/400 (W/kg) when an external stress of 10 MPa is applied in a direction perpendicular to the magnetic flux of the electromagnetic steel plate is 0.98 or less relative to the iron loss W _10/400 (W/kg) when no external stress is applied to the electromagnetic steel plate.
Here, the integrated magnetic flux density IB(500) refers to the integral value of the magnetic flux density (T) in the range where the magnetic field strength H is 0 A/m to 50,000 A/m,
The integrated magnetic flux density IB(5) indicates the integral value of the magnetic flux density (T) in the range where the magnetic field strength H is 0 A/m to 500 A/m. The stator of claim 1, wherein the ratio D/h of the stack height h to the outer diameter D of the stator core is 1.0≦D/h≦3.0. 3. The stator according to claim 1, wherein the slot space factor of the winding is 60% or more. A stator as described in claim 1 or 2, wherein the layers of the electromagnetic steel sheets are bonded together at an area ratio of 85% or more. the electromagnetic steel sheet has a punched shear surface,
a corner of the electromagnetic steel sheet that comes into contact with the winding is on the punched shear surface side,
3. The stator according to claim 1, wherein the stator does not include insulating paper. A stator as described in claim 1 or 2, wherein the electromagnetic steel sheet contains, by mass%, Cu: 0.001% or more and 1.0% or less. A motor having a stator according to claim 1 or 2.