JP2021023035A - motor - Google Patents

Abstract

To provide a small motor capable of generating high torque or high power with high efficiency suitable for high-speed operation.SOLUTION: A motor has a coreless structure stator 1 provided with a lead wire 2 wound around a yoke and a mover provided with a permanent magnet 3 to face the stator. A soft magnetic material 21 is provided between the lead wire in any winding and the lead wire in the winding adjacent to a movable direction of the mover. The soft magnetic material may be a magnetic composite material obtained by mixing a resin with magnetic powder and solidifying it.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a small motor capable of generating high torque with high efficiency suitable for high speed operation.

In recent years, with the increase in energy consumption, interest in the problem of global warming has increased internationally, and reduction of energy consumption is required. It is said that about 40% of the world's energy consumption is related to motors, and with the progress of electrification in each field, it is an urgent task to improve the efficiency of motors. Higher efficiency of the motor can be achieved to some extent by increasing the size of the motor, but increasing the size limits the applications.

Small motors include turbochargers used in automobile engines, turbo molecular pumps, and motors used in medical robots. In addition to efficiency, these motors are required to have an ultra-high speed, for example, a rotation speed exceeding 100,000 rpm. It is said that a slotless (coreless) motor is suitable as a means for realizing ultra-high-speed rotation with a small size (Non-Patent Document 1). This is because it is necessary to suppress the increase in the induced voltage under ultra-high speed rotation, and therefore it is advantageous to reduce the inductance of the winding portion.

However, on the other hand, since the slotless motor does not have a core, the magnetic flux density in the gap between the stator and the rotor is low, and therefore the torque is small. Further, the magnetic flux from the permanent magnet is interlinked with the winding, and the current density in the winding is biased, so that AC copper loss occurs. To solve such a problem, an IPM motor in which a magnetic sheet is attached to the entire winding (coil) to reduce AC copper loss has been studied (Non-Patent Document 2).

In addition, as a method of improving torque, there is also a technique for increasing torque by mixing magnetic powder with a mold resin for fixing the coil to the rotor of a moving coil type coreless motor and arranging the magnetism in the direction of the rotation axis. It is disclosed (Patent Document 1).

Japanese Unexamined Patent Publication No. 2006-25594

Komori et al., "High Power Density Design of Slotless Ultra High Speed PM Motor", IEEJ Industrial Application Division Conference, 2013 Torishima, Mizuno, et al., "Reduction of Copper Loss on Flat Wires Using Magnetic Flux Path Control Technology", Institute of Electrical Engineers of Japan, MAG-19-008, 2019

However, the high efficiency technique of Non-Patent Document 1 covers the side of the coil previously wound in the slot so that the magnetic flux does not directly enter the coil with a magnetic material on the side close to the rotor (permanent magnet). That is, the configuration is premised on the use of slots, and even if it is applied to a slotless motor as it is, there is no effect, or the efficiency is rather reduced. Further, in the technique of Patent Document 1, the magnetic molding material is magnetized and arranged in order to realize high torque, but there is a problem that this causes an increase in inductance and is not suitable for ultra-high speed rotation. It was. Further, when the periphery of the coil is magnetized, there is a problem that magnetic saturation occurs under a high magnetic field.

The motor according to one aspect of the present disclosure is a motor having a stator having a coreless structure provided with a conducting wire wound around a yoke and a mover provided with a permanent magnet so as to face the stator. It is characterized in that a soft magnetic material is provided between the lead wire in an arbitrary winding and the lead wire in a winding adjacent to the movable direction of the mover.

The soft magnetic material may be any of an electromagnetic steel plate, a nanocrystal plate, a dust powder, and a magnetic composite material.

The magnetic composite material may be a binder mixed with magnetic powder and solidified.

The magnetic powder may be any of Fe-based amorphous, pure iron, Fe—Si, nanocrystals, and sendust.

The cross section of the lead wire may be flat.

The cross section of the lead wire may be circular.

The lead wire may be wound around α.

The soft magnetic material has a surface in contact with the yoke, and a groove for accommodating the lead wire is formed on the surface side of the soft magnetic material in contact with the yoke in a direction perpendicular to the movable direction of the mover. May be good.

The yoke may be made of a soft magnetic material.

The yoke may be formed by laminating electromagnetic steel sheets.

According to one aspect of the present disclosure, torque and power are increased by controlling the magnetic flux path in the stator of a slot (core) -less motor operating at ultra-high speed with a soft magnetic material provided between the conductors. In addition, it is possible to reduce the eddy current loss in the winding, and it is possible to realize a compact and highly efficient motor. Further, since the soft magnetic material contains a metal or alloy such as Fe, it has relatively good thermal conductivity, plays a role of dissipating heat generated in the conducting wire, and can prevent an increase in DC resistance due to heat generation.

Cross-sectional view and detailed cross-sectional view of the motor according to the embodiment of the present disclosure. Configuration diagram of the main part of the motor according to the embodiment of the present disclosure Explanatory drawing showing the magnetic flux path of a general slotless motor Explanatory drawing which shows the effect of one Embodiment of this disclosure Cross-sectional view of the soft magnetic material and its surroundings in the motor of Example 1 of the present disclosure. Configuration diagram of the main part of the stator in the motor of Example 1 of the present disclosure Configuration diagram of the main part of the stator in the motor of the second embodiment of the present disclosure Configuration diagram of the main part of the stator in the motor of Example 3 of the present disclosure Dimensional drawing of the motor of Example 4 of the present disclosure A graph showing the characteristics of the soft magnetic material of Example 4 of the present disclosure. Dimensional drawing of Example 4 and Comparative Example of the present disclosure Magnetic flux density and magnetic flux line distribution diagram of Example 5 and Comparative Example of the present disclosure Current density and magnetic flux line distribution diagram of Example 5 and Comparative Example of the present disclosure Graph showing the effect of Example 5 of the present disclosure Graph showing the effect of Example 5 of the present disclosure Graph showing the effect of Example 5 of the present disclosure Graph showing the effect of Example 6 of the present disclosure A partial configuration diagram of a comparative example with respect to Example 7 of the present disclosure and a graph showing AC copper loss. A partial configuration diagram of one model of Example 7 of the present disclosure and a graph showing AC copper loss. A partial configuration diagram of another model of Example 7 of the present disclosure and a graph showing AC copper loss. A partial configuration diagram of another model of Example 7 of the present disclosure and a graph showing AC copper loss. A partial configuration diagram of a comparative example with respect to Example 8 of the present disclosure and a graph showing AC copper loss. A partial configuration diagram of one model of Example 8 of the present disclosure and a graph showing AC copper loss. A partial configuration diagram of another model of Example 8 of the present disclosure and a graph showing AC copper loss. A partial configuration diagram of another model of Example 8 of the present disclosure and a graph showing AC copper loss.

Hereinafter, embodiments according to one aspect of the present disclosure will be described in detail with reference to the drawings. In the present embodiment, the motor is a rotary motor. FIG. 1 shows a cross-sectional view of the motor according to the present embodiment and a detailed cross-sectional view inside a circle drawn by a broken line. In FIG. 1, reference numeral 1 denotes a (stator) yoke, which constitutes a stator together with a wound lead wire (hereinafter, winding) 2. Reference numeral 3 denotes a permanent magnet, which constitutes a mover (hereinafter referred to as a rotor) together with the yoke 4 and the shaft 5. The permanent magnet 3 is provided so as to face the stator and is magnetized in advance in the direction indicated by the white arrow in the figure.

In the detailed cross-sectional view of FIG. 1, reference numeral 21 denotes a soft magnetic material, which is provided between the lead wire 2 in an arbitrary winding and the conducting wire in a winding adjacent to the yoke 1 in the circumferential direction. In other words, in the yoke 1, the conducting wires are not wound in contact with each other without the soft magnetic material 21 (simply only the insulating layer). The material of the soft magnetic material 21 may be, for example, an electromagnetic steel plate, a nanocrystal plate, a dust powder, or a magnetic composite material. Electrical steel sheets and dust powders are suitable as materials for the soft magnetic material 21 in terms of the large relative permeability, but magnetic composite materials are superior in terms of ease of molding. Further, the yoke 1 may also be formed of a soft magnetic material such as an electromagnetic steel plate, a nanocrystal plate, a dust powder, or a magnetic composite material.

The magnetic composite material may be solidified by mixing magnetic powder with a binder such as resin. For example, an epoxy resin and a diluent may be mixed, stirred, and cast into a spherical magnetic powder and heat-cured. As the magnetic powder, for example, Fe-based amorphous, pure iron, Fe-Si, nanocrystals, and sendust can be used. The shape is preferably spherical. This is because the flat magnetic powder may be oriented by a strong magnetic field and the magnetic flux density may be saturated. The amount of magnetic powder in the magnetic composite material is preferably 30 to 60% by volume. If it is lower than this range, the magnetic flux path is not sufficiently controlled, and if it is higher than this range, the rigidity of the material itself decreases. The specific structure of the soft magnetic material 21 and specific examples of the magnetic composite material will be described again in Examples 1 to 4.

In the detailed cross-sectional view of FIG. 1, reference numeral 20 denotes a conducting wire that is a part of the winding 2. The cross section of the lead wire 20 may be flat or circular. The details of the cross-sectional shape will be described again in Examples 1 and 2. In the present embodiment, it is assumed that the lead wire 20 has a flat cross section. Here, the flat shape may be a rectangular shape or a polygon with the corners of the rectangle cut off. Winding 2 is a two-layer α winding, which is a U-U'(U upper bar in the figure) phase, a VV'(V upper bar in the figure) phase, and a W-W'(W upper bar in the figure). Bar) It may be distributed and wound for each phase.

FIG. 2 shows a configuration diagram around the lead wire 20. In FIG. 2, a soft magnetic material 21 is always provided between the lead wire 20 and the lead wire 20 adjacent to the yoke 1 circumferential direction (directions on the left and right sides of the drawing). The lead wire 20 and the soft magnetic material 21 do not have to be in direct contact with each other. A non-magnetic insulating layer 23 (for example, an adhesive layer) may be provided as long as it does not affect the magnetic characteristics. Further, the soft magnetic material 21 may be provided between the winding of the first layer (yoke 1 side) and the winding of the second layer, and between the winding of the second layer and the rotor 3 (not shown). Good.

The operation (operation) of the motor configured as described above will be described below. First, FIG. 3 shows a conceptual diagram depicting the path of magnetic flux lines in a general slotless motor (one that does not use the soft magnetic layer 21) (hereinafter, Rectangle Copper Wire: RCW for short). In FIG. 3, the magnetic flux φm from the permanent magnet (3) interlinks in the conductor (20), and an eddy current is generated in the winding, which causes a bias in the current density and reduces the effective cross-sectional area through which the current flows. .. As a result, winding resistance increases and AC copper loss occurs.

On the other hand, if the winding 2 is embedded in the soft magnetic member 21 (such as a magnetic composite material) (hereinafter, M agnetic M old C oil: short the MMC) showed the path of magnetic flux φm in Figure 4. A motor having a structure in which the winding 2 is embedded in the soft magnetic material 21 as described above is hereinafter referred to as an embedded winding type synchronous motor (IWSM). The magnetic composite material used as the raw material of the soft magnetic material 21 has a higher magnetic permeability than air, and most of the magnetic flux passes through the soft magnetic material 21, so that the AC copper loss generated in the winding is reduced accordingly. Further, since the magnetic flux can be concentrated on the soft magnetic material 21, the gap magnetic flux density increases, and an increase in torque can be expected. The specific configuration and operation of the conductor 20 and the soft magnetic material 21 will be described in detail in the following examples.

In the present embodiment, the motor is a rotary motor, but the motor is not limited to the rotary motor. For example, it may be a so-called linear motor in which the yoke is long and the mover moves parallel to the yoke along the rail.

Hereinafter, examples of the present disclosure will be described.
(Example 1)
In this embodiment, a specific configuration of the soft magnetic material 21 in the rotary motor will be described. FIG. 5 shows a cross-sectional view of the soft magnetic material 21 and its peripheral parts. In FIG. 5, the soft magnetic material 21 has a cylindrical shape inscribed in the yoke 1 (partially indicated by a dotted line). A groove for accommodating the wound lead wire 20 is formed on the surface of the soft magnetic material 21 inscribed in the yoke 1 in a direction perpendicular to the rotation direction of the rotor, that is, in a direction perpendicular to the paper surface in the drawing.

The configuration diagram of the main part of FIG. 5 is shown in FIG. A flat lead wire 20 is wound along a groove provided in the soft magnetic material 21. For example, in the case of W-phase α winding, the lead wire 20 is embedded in a groove provided in the soft magnetic material 21 and wound from the outer circumference to the inner circumference while straddling the W phase and the W'(indicated by a bar in the figure) phase. The first layer may be formed, then the second layer may be wound from the innermost circumference, and the winding may be completed at the outermost circumference. After winding all the other phases, the cylindrical yoke 1 is put on the wire, and each lead wire 20 is sealed by the yoke and the soft magnetic material 21 as shown in FIG. In FIG. 6, the blank around the conductor 20 may be an insulating layer or an adhesive layer. Considering that the heat generated inside the lead wire 20 is released to the soft magnetic material 21, it is preferable that the insulating layer or the like is as thin as possible and has good thermal conductivity.

(Example 2)
FIG. 7 shows a cross-sectional view of a main part of the stator (stator) in the motor of the second embodiment of the present disclosure. As shown in FIG. 7, a conducting wire having a circular cross section may be used instead of the flat wire. Since the soft magnetic material 21 is provided with a groove in advance, if the lead wire 20 is wound in multiple layers so as to be embedded in the groove, the winding is as shown in the figure. It is preferable that the surface of the lead wire 20 is insulated in advance. Further, after winding, the gap between the lead wire 20 and the soft magnetic material 21 may be filled with a resin such as epoxy.

(Example 3)
In this embodiment, an example in which a soft magnetic tape is used as the soft magnetic material 21 will be described. In FIG. 8, soft magnetic tapes 24a and 24b are previously attached to both sides of the flat lead wire 20. When this is wound around α as it is, the soft magnetic tapes are brought into close contact with each other at the positions indicated by the dotted lines in the figure, and finally the soft magnetic material 21 is formed. The soft magnetic sheet 24c may be sandwiched between the lead wire wound on the first layer (yoke 1) side and the lead wire wound on the second layer side. Further, the soft magnetic sheet 24d may be provided on the rotor 3 (not shown) side of the conducting wire wound on the second layer side. An adhesive layer may be provided on the surfaces of each soft magnetic tape and each soft magnetic sheet. Further, the non-magnetic insulator 23 may be partially provided.

(Example 4)
In this embodiment, specific specifications of the motor, material composition, and the like will be described. First, the shape and dimensions of the entire motor are shown in FIG. 9 and Table 1. 9, the motor is a rotary motor, and the outer diameter _{D s} of the (stator) yoke 1 and 32 mm, the total length l (el) (in Table 1 Stack Thickness) is 60 mm. The outer diameter of the rotor (permanent magnet 3) _{D m} is assumed to be 20.2 mm, the gap _{l g} between the stator and the rotor was set at 0.3 mm.

An electromagnetic steel plate may be used for the yoke 1 in order to suppress the eddy current loss in the high speed range as much as possible. The material of the winding 2 (lead wire 20) may be copper or aluminum. Further, an insulating film may be provided on the surface. As the permanent magnet, an Nd-Fe-B-based bond magnet having a high resistivity may be used in order to reduce the internal eddy current loss.

Regarding the winding 2, the number of turns N is U, V, W for each phase, 7 turns x 2 layers = 14 turns in total. The width W _c (long side of the rectangular cross section) of the conductor 20 was 1.0 mm, and the thickness t _c (short side of the rectangular cross section) was 0.32 mm. Details are shown in Table 1 and FIG.

The (stator) yoke 1 was made by laminating a 0.1 mm thick electromagnetic steel plate (JFE Steel, Inc. 10JNHF600) in order to reduce eddy current loss, which is a problem in the high speed range. Further, a spherical Fe-based amorphous alloy powder (average powder diameter of about 2.6 μm) is used as the magnetic composite material. HIDENCE-1000 manufactured by NEOMAX Co., Ltd. is used as the permanent magnet 3. Table 2 shows the details of the yoke and the magnetic material.

In this example and subsequent examples, a composite magnetic material is used as the soft magnetic material 21. FIG. 10 (a) shows the static magnetic properties of the composite magnetic material, and FIG. 10 (b) shows the iron loss characteristics of the same material. This characteristic was measured using the inductor canceling method. As is clear from FIG. 10A, the composite magnetic material used in this embodiment does not show saturation of the magnetic flux density up to H = 180 kA / m. Further, from FIG. 3B, it can be seen that the iron loss at the frequency used (3.3 kHz) is at a negligible level.

(Example 5)
In this embodiment, the magnetic characteristics of the rotary motors of the comparative example (FIG. 11 (a)) and the present embodiment (FIG. 11 (b)) are calculated, and the results will be described. In this embodiment, the thickness of the lead wire 20 is set to t _c = 0.32, and the width is set to w _c = 1.0 mm. The calculation is based on JMAG-Designer Ver. This was done using the finite element (FEM) method according to 18.0. The material of the lead wire 20 was copper. The magnetic properties of the soft magnetic material 21 were obtained from FIG. 10A according to the strength of the magnetic field. It is assumed that the rotor is rotating at 100,000 rpm, and that a three-phase alternating current of 3.3 kHz with a phase shift of 120 ° is flowing in each of the W, U, and V phases. Other detailed parameters are shown in Table 3. In this embodiment, the non-magnetic insulator 23 is not provided.

12 (a) and 12 (b) show the magnetic flux density distributions inside the motor of the comparative example and the present embodiment, respectively. At this time, it is assumed that the maximum current is flowing in the U phase. Compared with the comparative example (FIG. 12 (a)), in the motor (FIG. 12 (b)) of the present embodiment in which the soft magnetic material 21 is arranged around the winding 2, the magnetic flux passes through the soft magnetic material 21. , It can be confirmed that the magnetic flux interlinking with the winding is reduced. Further, since the magnetic flux is concentrated on the soft magnetic material 21, the gap magnetic flux density also increases. Further, FIGS. 13 (a) and 13 (b) show the respective current density distributions. It can be confirmed that by arranging the soft magnetic material 21, the magnetic flux interlinking the windings is reduced and the bias of the current density distribution is reduced.

FIG. 14A shows the torque-current characteristics of the motors of the comparative example and the present embodiment, respectively. Since the motor of this example (MMC in the figure) has an improved gap magnetic flux density as compared with the comparative example (RCW in the figure), the torque increased by 43% when the same current was applied. Needless to say, the torque constant Kt also increases. In order to confirm the torque ripple, FIG. 3B shows the time change of the torque when the motor (MMC in the figure) of this embodiment is used. Similar to traditional slot (core) less motors, torque ripple has been shown to be negligibly small enough.

15 (a) to 15 (c) show a comparison of copper loss of the motors of the comparative example and the present embodiment, respectively. In both cases, the effective value of the current is I = 3.5 _Arms . FIG. 15A shows the total value of DC / AC copper loss, which is 58% lower than that of Comparative Example (RCW). Since the soft magnetic layer 21 is provided so as to overlap with the winding 20, it is considered that the biggest factor is that the bias of the current density is reduced and the AC copper loss is reduced.

FIG. 15B is a comparison of iron loss. In this embodiment (MMC), the iron loss is increased by 82% as compared with the comparative example (RCW in the figure). It is considered that this is because the provision of the soft magnetic layer 21 facilitates the flow of magnetic flux from the permanent magnet 3 to the (stator) yoke 1, and as a result, the magnetic flux density of the (stator) yoke 1 increases. Among the iron losses, the eddy current loss P _{e_r} and hysteresis loss P _{h_r of} the (rotor) yoke, the eddy current loss P _{e_m} of the permanent magnet, the eddy current loss P _{e_mm} and the hysteresis loss P _{h_mm} of the magnetic material are ignored. The value was as small as possible.

FIG. 15C is a graph comparing the overall efficiency including the copper loss and the iron loss. In addition, detailed comparisons for each loss are shown numerically in Tables 4 and 5.


FIG. 15C compares the currents required to produce the same torque. The current required to generate the same torque is smaller in this embodiment (MMC) than in the comparative example (RCW). Therefore, the DC copper loss represented by the square of the current is smaller in this embodiment (MMC). Further, as described above, the AC copper loss is also reduced. Even if the increase in iron loss is taken into consideration, the overall efficiency is improved by 2.2%. FIG. 16 shows the phase voltage of the U phase for one cycle of the electric angle. In the case of this embodiment (MMC), the phase voltage increases by 35% due to the increase in the counter electromotive force constant and the increase in the winding inductance.

(Example 6)
In this embodiment, in the motors shown in FIGS. 11A and 11B, the thickness of the lead wire 20 is changed to t _c = 0.26 mm, 0.28 mm, 0.30 mm, 0.32 mm, and the lead wire is further changed. The loss when the width of 20 was changed to w _c = 0.7 mm, 0.8 mm, 0.9 mm, and 1.0 mm was calculated, and the optimum values for the width and thickness of the lead wire 20 were obtained. This will be described below.

FIG. 17A shows three-dimensionally the calculation result of the torque when the width and the thickness of the conductor 20 constituting the winding 2 are changed. The torque does not change significantly even if the width of the conductor 20 is changed. Further, FIG. 17B shows the copper loss when the width of the winding 2 (conductor 20) is changed. The copper loss decreases as the thickness t _c × width w _c of the winding 2 becomes smaller. This is because the cross-sectional area becomes smaller, so that the interlinkage magnetic flux also decreases. If the current is fixed, the DC copper loss will increase. However, considering that the proportion of the soft magnetic material increases as the cross-sectional area is reduced, it becomes easier to induce magnetic flux, and the AC copper loss decreases. However, as the conductor cross-sectional area is reduced, DC copper loss occupies a large proportion. Therefore, when t _c = 0.30 mm and w _c = 0.8 mm, the copper loss is the optimum condition.

The above results are summarized in Table 6.

By embedding the winding in the soft magnetic material and winding it, most of the magnetic flux can be guided to the soft magnetic material, and as a result, both improvement of torque and reduction of AC loss can be achieved. In the examples, the torque constant increased by 43% and the copper loss decreased by 58%. At this time, the iron loss increased by 82%, but since the torque constant increase and the copper loss reduction effect were larger than the increase in iron loss, the efficiency when the output was fixed was compared. Example (MMC) was 97.4% compared to 95.2% of RCW), and an improvement of 2.2% was confirmed. At this time, the output power density at 1 kW output was 2.9 W / g.

Further, it was confirmed that the torque does not change so much depending on the winding cross-sectional area and the copper loss has an optimum value in the characteristics when the winding cross-sectional dimension is used as a parameter. Finally, in this study, a motor of the type in which a permanent magnet is placed on the surface of the rotor, so-called SPM, was used for the rotor, but IWSM changes only the stator winding, and the rotor is inside the rotor. It can also be applied to a rotor such as an IPM in which a permanent magnet is embedded.

(Example 7)
In this embodiment, the copper loss of the rotary motor, other electromagnetic characteristics, and the torque constant when the winding pattern of the lead wire 20 having a flat cross-sectional shape is changed are calculated. The changes in copper loss when the calculation model and the rotor (permanent magnet 3) are rotated at 0 to 100,000 rpm are shown in FIGS. 18 to 21. The shape and dimensions of the entire motor are the same as those shown in FIG. Table 7 shows the calculation results of copper loss, iron loss, output and efficiency when the rotor is rotated at 100,000 rpm by supplying an electric current to the winding. In Table 7, the indications of R-0, R-1, R-2, and R-3 correspond to the models shown in FIGS. 18, 19, 20, and 21, respectively.

The model shown in FIG. 18A is a general slotless (coreless) motor in which a lead wire is wound in 12 turns × 2 layers for each of the U phase, the V phase, and the W phase, which is a comparative example in this embodiment. Is. The relationship of AC copper loss with respect to the number of revolutions in this model is shown in FIG. Here, the 24 conductors are connected in parallel by two each, which is substantially 12 turns. Further, FIG. 19A shows a cross-sectional view of a motor in which a lead wire is embedded in a soft magnetic material. Comparing FIG. 18 (b) and FIG. 19 (b), the copper loss (Pc) is reduced to about 40% in the rotation speed range of 0 to 100,000 rpm.

In Table 7, the AC copper loss in the comparative example (R-0 in Table 7) was 46.19 W, whereas in the model (R-1) in which the lead wire was embedded in a soft magnetic material, it improved to 17.48 W. doing. Further, even when the torque constants are compared, the soft magnetic material model (R-1) is 0.0229 Nm / A, which is an improvement of 30% or more, compared with 0.0174 Nm / A in the comparative example (R-0). There is.

Models of further improvements of the motor shown in FIG. 19 (a) are shown in FIGS. 20 (a) and 21 (a). In both cases, the number of parallel turns is reduced so that the number of turns for each phase is the same. The motor shown in FIG. 20 (a) is characterized in that one parallel portion is removed while maintaining the pitch of the remaining windings, and a soft magnetic material is filled instead (R-2 in Table 7). .. On the other hand, in the motor shown in FIG. 22 (a), a soft magnetic material is filled between the conductors by doubling the winding pitch (R-3 in Table 7).

In each model, the AC copper loss is reduced to 10% or less as compared with the motor of the comparative example of this example (FIGS. 20 (b), 21 (b), and Table 7). It is considered that the main reason is that the magnetic flux path is controlled by the soft magnetic material and the magnetic flux interlinking with the conducting wire is reduced. Comparing the characteristics other than the AC copper loss, the DC copper loss is about half that of the comparative example (R-0), and the torque constant is about 40% higher than that of the comparative example. Regarding the efficiency, the efficiency was 93.28% in the comparative example (R-0), 97.68% in the model (R-2) of FIG. 20 (a), and 97.68% in the model (R-3) of FIG. 21 (a). An improvement effect of 97.80%, or 4% or more, was confirmed.

(Example 8)
In this embodiment, the copper loss and other electromagnetic characteristics and torque constant of the rotary motor when one wire having a flat cross section is replaced with three wires having a circular cross section are calculated. The changes in copper loss when the calculation model and the rotor (permanent magnet 3) are rotated at 0 to 100,000 rpm are shown in FIGS. 22 to 25. Table 8 shows copper loss, iron loss, output, and efficiency when the rotor is rotated at 100,000 rpm by supplying an electric current to the winding. In Table 8, the indications C-0, C-1, C-2, and C-3 correspond to the models shown in FIGS. 22, 23, 24, and 25, respectively.

FIG. 22A shows a cross-sectional view of a general slotless (coreless) motor in which a lead wire is wound in each of the U phase, the V phase, and the W phase in 12 turns × 6 layers, which is a comparative example in this embodiment. Shown. In addition, Fig. (B) shows the relationship of AC copper loss with respect to the number of revolutions. Here, the number of conductors for each phase is 72, and this number is reduced by having 6 conductors and winding them 12 times. The models shown in FIGS. 22 (a) to 25 (a) are exactly the same as the models shown in FIGS. 18 (a) to 21 (a) except for the shape of the lead wire and the number of turns. Suppose there is.

When comparing the comparative examples (R-0 in Table 7 and C-0 in Table 8), the AC copper loss is 39.59 W and the flat cross-section lead wire is better when the flat cross-section lead wire is replaced with three circular cross-section lead wires. It is about 20% smaller than 46.19W. This is because the cross-sectional area of one conductor is smaller in the three circular cross-sectional conductors, so that the eddy current path in the winding due to the magnetic flux of the magnet becomes smaller. Comparing the models (R-1 and C-1) in which the circular cross-section lead wire is embedded in the soft magnetic material, the AC copper loss of R-1 is 17.48 W, while that of C-1 is reduced to 12.05 W. Will be done.

However, in the models with a reduced number of turns (C-2 and C-3), the AC copper loss is slightly higher than that in the flat cross-section lead wires (R-2 and R-3). Further, the DC copper loss is 6.65 W in the C-3 model, which is worse than the 5.81 W in the comparative example (C-0). In terms of iron loss, the circular cross-section lead wire is slightly more advantageous. The final efficiency comparison is 97.68% for the R-2 model, 97.61% for the C-2 model, and 97.80% for the R-3 model. In the C-3 model, it is 97.87%, which is a small difference.

The present invention can be applied to a turbocharger for a gasoline engine, a turbo molecular pump, an ultra-high speed rotary motor or a linear motor used in a medical robot. Further, since the loss is low and the heat dissipation performance is high, it can be used for industrial applications in which heat generation is particularly disliked.

1 (Stator) Yoke 2 Winding 20 Conductor 21 Soft magnetic material 24a, 24b Soft magnetic tape 24c Soft magnetic sheet 3 Permanent magnet 4 (Rotor) Yoke 5 Shaft

Claims (10)

A motor having a stator having a coreless structure provided with a lead wire wound around a yoke and a mover provided with a permanent magnet so as to face the stator.
A motor characterized in that a soft magnetic material is provided between the lead wire in an arbitrary winding and the lead wire in a winding adjacent to the movable direction of the mover. The motor according to claim 1, wherein the soft magnetic material is any one of an electromagnetic steel plate, a nanocrystal plate, a dust powder, and a magnetic composite material. The motor according to claim 2, wherein the magnetic composite material is a binder mixed with magnetic powder and solidified. The motor according to claim 3, wherein the magnetic powder is any one of Fe-based amorphous, pure iron, Fe-Si, nanocrystals, and sendust. The motor according to claim 1, wherein the cross section of the conducting wire has a flat shape. The motor according to claim 1, wherein the cross section of the conducting wire is circular. The motor according to claim 5 or 6, wherein the lead wire is wound around α. The soft magnetic material has a surface in contact with the yoke, and a groove for accommodating the lead wire is formed on the surface side of the soft magnetic material in contact with the yoke in a direction perpendicular to the movable direction of the mover. The motor according to any one of claims 1 to 7. The motor according to claim 1, wherein the yoke is made of a soft magnetic material. The motor according to claim 9, wherein the yoke is formed by laminating electromagnetic steel sheets.