Permanent magnet field, rotating machine, linear motor, control system

Abstract

To provide a technology capable of more appropriately suppressing thermal demagnetization of a permanent magnet field.SOLUTION: A magnetic field 20 according to an embodiment of the present disclosure includes a permanent magnet 21 that generates a magnetic field for an armature 10, and a thermoelectric conversion element 23 attached to the permanent magnet 21. For example, the thermoelectric conversion element 23 is a magnetic thermoelectric conversion element that generates a voltage signal by a magneto-thermoelectric effect such as the anomalous Nernst effect or the spin Seebeck effect, and is attached to a surface different from the magnetic pole surface of the permanent magnet 21.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to permanent magnet fields and the like. [Background technology]

[0002] For example, a technique for suppressing thermal demagnetization of a permanent magnet field in an electric motor such as a rotating machine or a linear motor is known (see Patent Document 1).

[0003] In Patent Document 1, a thermoelectric conversion element is placed in thermal contact between the high-temperature side armature coil and the low-temperature side shaft to generate electricity and lower the temperature of the coil, thereby suppressing thermal demagnetization of the permanent magnet field. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-153036 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the configuration of Patent Document 1, for example, if an unexpected overcurrent flows in the armature coil, the cooling effect of the power generation by the thermoelectric conversion element cannot respond quickly, and as a result, the temperature of the magnets in the permanent magnetic field may rise to a level that causes demagnetization. Therefore, there is room for improvement in terms of suppressing thermal demagnetization of the permanent magnetic field.

[0006] In view of the above-mentioned problems, an object of the present invention is to provide a technique that can more appropriately suppress thermal demagnetization of a permanent magnet field. [Means for solving the problem]

[0007] In order to achieve the above object, in one embodiment of the present disclosure, a first permanent magnet that generates a magnetic field relative to the armature; a second permanent magnet adjacent to the first permanent magnet and enhancing the magnetic flux of the magnetic pole of the first permanent magnet facing the armature; a thermoelectric conversion element attached to the first permanent magnet, 、 The thermoelectric conversion element is provided on a surface of the first permanent magnet that is different from the surface adjacent to the second permanent magnet. Ru, A permanent magnet field is provided.

[0008] In another embodiment of the present disclosure, the permanent magnet field as described above; the armature, A rotating machine is provided.

[0009] In still another embodiment of the present disclosure, the permanent magnet field as described above; The armature is provided. A linear motor is provided.

[0010] In still another embodiment of the present disclosure, a rotating machine or linear motor including the permanent magnet field and the armature; a control device that controls the rotating machine or the linear motor based on the output of the thermoelectric conversion element, A control system is provided. [Effects of the Invention]

[0011] According to the above-described embodiment, it is possible to more appropriately suppress thermal demagnetization of the permanent magnet field. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a side cross-sectional view showing an example of a linear motor. [Figure 2] FIG. 2 is a plan cross-sectional view showing an example of an armature. [Figure 3] FIG. 2 is a side view showing a first example of a field magnet. [Figure 4] FIG. 10 is a front cross-sectional view showing a second example of a field magnet. [Figure 5] FIG. 10 is a side view showing a third example of a field magnet. [Figure 6] FIG. 1 is a diagram illustrating an example of a control system for a linear motor. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment will be described with reference to the drawings.

[0014] [Linear motor overview] An overview of a linear motor 100 according to this embodiment will be described with reference to FIGS.

[0015] Fig. 1 is a side cross-sectional view showing an example of a linear motor 100. Specifically, Fig. 1 is a cross-sectional view taken along a plane parallel to the X-axis and Z-axis of the linear motor 100. Fig. 2 is a plan cross-sectional view showing an example of an armature 10. Specifically, Fig. 2 is a cross-sectional view taken along line AA in Fig. 1.

[0016] Hereinafter, explanations may be made using a Cartesian coordinate system defined by the X-axis, Y-axis, and Z-axis in the drawings. Furthermore, the positive X-axis direction and the negative X-axis direction may be collectively referred to as the X-axis direction, the positive Y-axis direction and the negative Y-axis direction may be collectively referred to as the Y-axis direction, and the positive Z-axis direction and the negative Z-axis direction may be collectively referred to as the Z-axis direction.

[0017] The linear motor 100 according to this embodiment may be incorporated into the opening and closing mechanisms of various sliding doors, such as railway car doors, station platform doors, etc. Furthermore, the linear motor 100 according to this embodiment may be mounted on, for example, semiconductor manufacturing equipment.

[0018] As shown in Fig. 1 and Fig. 2, the linear motor 100 includes an armature 10 and a field magnet 20. In Fig. 1, the letters "N" and "S" drawn on the field magnet 20 represent the magnetic poles (north and south poles) of a permanent magnet 21. The same applies to Figs. 3 to 5 described below. In Fig. 2, the dashed lines drawn on the armature 10 represent the cross-sectional shapes of both ends of the core 11 in the Z-axis direction.

[0019] The armature 10 is disposed opposite the field magnet portions 20A and 20B in the Z-axis direction via a predetermined air gap AG. In this example, the armature 10 is a mover. The armature 10 is supported by a support mechanism such as a slide rail or a linear guide so as to be movable in the X-axis direction. This allows the armature 10 to move in the X-axis direction by a magnetic force acting between the armature 10 and the field magnet 20. The armature 10 includes a core (also referred to as an "iron core") 11, a coil (also referred to as a "winding") 12, and a holding portion 13.

[0020] The core 11 functions as a magnetic path for the magnetic field generated by the armature current of the coil 12 and the magnetic field from the permanent magnet 21 of the field 20. The core 11 is made of a soft magnetic material such as an electromagnetic steel sheet or a powder magnetic core. In this example, a plurality of cores 11 (12 pieces) are provided, the same number as the number of the coils 12.

[0021] 1 and 2, core 11 has a rectangular column shape extending in the Z-axis direction, and is configured so that the cross-sectional shapes of both ends in the Z-axis direction are larger than the cross-sectional shape of the center in the Z-axis direction. As a result, even if core 11 attempts to move in the positive direction of the Z-axis, the end of core 11 in the negative direction of the Z-axis abuts against retaining portion 13, and as a result, core 11 cannot move in the positive direction of the Z-axis, thereby preventing core 11 from falling off from armature 10 as it moves in the positive direction of the Z-axis. A similar effect can also prevent core 11 from falling off from armature 10 as it moves in the negative direction of the Z-axis.

[0022] When an armature current flows through coil 12, the coil generates a driving force for the mover (armature 10) by interacting with the magnetic field generated by field magnet portions 20A and 20B. Coil 12 is formed by winding a conducting wire around core 11.

[0023] In this example, a plurality of (12) coils 12 are provided. The plurality of coils 12 are arranged in the X-axis direction. For example, three-phase AC power of U-phase, V-phase, and W-phase is supplied to the plurality of coils 12. Specifically, three-phase AC power of U-phase, V-phase, W-phase, U-phase, V-phase, W-phase, ... may be supplied to the coils 12 in order from the coil 12 at the end in the negative X-axis direction in the drawing toward the positive X-axis direction.

[0024] The number of coils 12 may be 11 or less, or 13 or more.

[0025] The holding portion 13 integrally holds the cores 11 and the coils 12. The holding portion 13 is made of, for example, molded resin, and holds the cores 11 so that both ends in the axial direction (Z-axis direction) are exposed from the holding portion 13.

[0026] The field 20 (an example of a permanent magnet field) generates a magnetic field that acts on the armature 10. In this example, the field 20 is a stator. As shown in FIG. 1, the field 20 is provided so as to extend in the X-axis direction, and the dimension of the field 20 in the X-axis direction is determined in accordance with the amount of movement of the armature 10 as a mover in the X-axis direction.

[0027] The field magnet 20 includes field magnet portions 20A and 20B.

[0028] Field magnet portions 20A and 20B are arranged to extend substantially parallel to each other in the X-axis direction. The term "substantially" is intended to allow for, for example, manufacturing errors, and will be used in the same manner hereinafter. A predetermined gap is provided between field magnet portions 20A and 20B in the Z-axis direction, and this gap is set to be somewhat larger than the dimension of armature 10 in the Z-axis direction. For example, the gap between field magnet portions 20A and 20B corresponds to the dimension of armature 10 in the Z-axis direction plus the amount of movement of a support mechanism for armature 10 (e.g., a slide rail or linear guide) in the Z-axis direction plus a predetermined margin. This allows armature 10, as a mover, to move in the X-axis direction without coming into contact with field magnet portions 20A and 20B.

[0029] Field magnet portions 20A and 20B are arranged to face each other in the positive and negative Z-axis directions when viewed from armature 10. Field magnet portions 20A and 20B each generate magnetic flux that links with the multiple coils 12 of armature 10.

[0030] Each of the field magnet portions 20A and 20B includes a plurality of permanent magnets 21, a back yoke 22, and a thermoelectric conversion element 23.

[0031] The multiple permanent magnets 21 (an example of first permanent magnets) are arranged side by side in the X-axis direction so as to face the armature 10 in the Z-axis direction. For example, as shown in FIG. 1, the multiple permanent magnets 21 each have a substantially rectangular parallelepiped shape with sides in the X-axis direction, Y-axis direction, and Z-axis direction, and are arranged side by side at substantially equal intervals in the X-axis direction. Spacers may be sandwiched between adjacent permanent magnets 21. Each of the multiple permanent magnets 21 is magnetized in the Z-axis direction facing the armature 10, and is arranged so that the magnetic pole of the end face in the Z-axis direction facing the armature 10 is different from that of other permanent magnets 21 adjacent in the X-axis direction. The multiple permanent magnets 21 are, for example, neodymium sintered magnets, ferrite magnets, etc.

[0032] Field magnet portion 20A and field magnet portion 20B are configured so that the magnetic specifications (e.g., shape, dimensions, residual magnetic flux density, etc.) and arrangement specifications (e.g., arrangement positions of permanent magnets 21 in the X-axis direction and arrangement method including presence or absence of Halbach array, etc.) of each other's permanent magnets 21 are substantially the same. This allows field magnet portion 20A and field magnet portion 20B to generate substantially symmetrical magnetic fields in spaces facing each other in the Z-axis direction.

[0033] The back yoke 22 is disposed adjacent to the surface of the permanent magnet 21 opposite to the end face in the Z-axis direction that faces the armature 10. The back yoke 22 functions as a magnetic path between adjacent permanent magnets 21. The back yoke 22 is made of a soft magnetic material, such as an electromagnetic steel plate or a powder magnetic core.

[0034] The thermoelectric conversion element 23 converts thermal energy into electrical energy and outputs an electrical signal. The thermoelectric conversion element 23 is attached to the permanent magnet 21. This allows the thermoelectric conversion element 23 to output an electrical signal in response to the inflow of thermal energy from the permanent magnet 21, thereby making it possible to detect a temperature rise of the permanent magnet 21. The attachment position of the thermoelectric conversion element 23 relative to the permanent magnet 21 can be set arbitrarily as long as the desired performance in detecting a temperature rise of the permanent magnet 21 can be ensured.

[0035] The thermoelectric conversion element 23 is, for example, a magneto-thermoelectric conversion element capable of outputting a voltage signal corresponding to the heat flow from the permanent magnet 21 by utilizing the magneto-thermoelectric effect. This allows the thermoelectric conversion element 23 to output a relatively large response signal (electrical signal) in a direction perpendicular to the heat flow from the permanent magnet 21. Specifically, the thermoelectric conversion element 23 may be a magneto-thermoelectric conversion element capable of generating a voltage signal by utilizing the anomalous Nernst effect or the spin Seebeck effect. For example, the thermoelectric conversion element 23 is a thin film of Co2MnGa or the like having the anomalous Nernst effect, and generates a voltage signal in a direction perpendicular to both the direction of the heat flow and the magnetization direction of the thin film. Alternatively, the thermoelectric conversion element 23 may be, for example, a double-layer film of a magnetic insulator and a metal. A spin current flows in response to the heat flow generated in the magnetic insulator. The spin current flows into the metal layer, generating a voltage signal in the metal layer perpendicular to both the direction of the heat flow and the magnetization direction of the magnetic insulator. The following description will be focused on the case where the thermoelectric conversion element 23 is a magneto-thermoelectric conversion element having the anomalous Nernst effect or the spin Seebeck effect.

[0036] The thermoelectric conversion element 23 may be attached to all or only some of the multiple permanent magnets 21. In other words, it is sufficient that the thermoelectric conversion element 23 is attached to at least one permanent magnet 21 for which temperature rise needs to be monitored.

[0037] Furthermore, if the permanent magnet 21 that requires monitoring of temperature rise is located in only one of the field magnet sections 20A, 20B, the thermoelectric conversion element 23 may be provided in only one of the field magnet sections 20A, 20B that has the target permanent magnet 21.

[0038] [First example of a magnetic field] Next, a first example of the field 20 according to this embodiment will be described with reference to FIG.

[0039] FIG. 3 is a side view showing a first example of the field magnet 20. As shown in FIG.

[0040] In FIG. 3, only the field magnet portion 20B is depicted, and the field magnet portion 20A is omitted.

[0041] 3, the thermoelectric conversion element 23 is attached to the end face of the permanent magnet 21 facing the negative X-axis so that the magnetization direction MD substantially coincides with the Z-axis direction. Alternatively, the thermoelectric conversion element 23 may be attached to the end face of the permanent magnet 21 facing the positive X-axis so that the magnetization direction MD substantially coincides with the Z-axis direction. This allows the thermoelectric conversion element 23 to be positioned by utilizing the space between the permanent magnets 21.

[0042] When the temperature of the permanent magnet 21 rises, a heat flow HF is generated that flows into the thermoelectric conversion element 23, which has a relatively low temperature. For example, as shown in FIG. 3 , the direction of the heat flow HF is approximately in the negative direction of the X-axis. Furthermore, when the thermoelectric conversion element 23 is attached to the end face of the permanent magnet 21 facing the positive X-axis, the direction of the heat flow HF is approximately in the positive X-axis direction. That is, in this example, the direction of the heat flow HF is approximately in the X-axis direction. Therefore, when the temperature of the permanent magnet 21 rises, a voltage signal is generated in the thermoelectric conversion element 23 in the approximately Y-axis direction, which is perpendicular to both the magnetization direction MD and the direction of the heat flow HF. Furthermore, the magnitude of the voltage signal increases as the heat flow increases, i.e., the degree of temperature rise of the permanent magnet 21 increases. Therefore, by using the output (voltage signal) of the thermoelectric conversion element 23, it is possible to determine whether or not the temperature of the permanent magnet 21 has risen and to what extent. That is, the thermoelectric conversion element 23 can detect whether or not the temperature of the permanent magnet 21 has risen and to what extent.

[0043] As shown in FIG. 3, the magnetic flux on the pole face of the permanent magnet 21 facing the armature includes main magnetic flux MF that interlinks with the armature 10 and leakage magnetic flux LF that connects different magnetic poles of the same permanent magnet 21.

[0044] 3, the leakage magnetic flux LF interlinks the thermoelectric conversion element 23 in approximately the Z-axis direction so as to be approximately aligned with the magnetization direction MD of the thermoelectric conversion element 23. Therefore, it is possible to prevent, for example, a situation in which the thermoelectric conversion element 23 is demagnetized due to an external disturbance or the like, causing a decrease in the thermoelectric conversion function or even loss of the thermoelectric conversion function.

[0045] [Second example of a magnetic field] 4 is a front cross-sectional view showing a second example of the field 20. Specifically, FIG. 4 is a cross-sectional view of the field 20 taken along a plane parallel to the Y-axis and Z-axis at a position in the X-axis direction where the permanent magnet 21 to which the thermoelectric conversion element 23 is attached is located.

[0046] In FIG. 4, only the field magnet portion 20B is depicted, and the field magnet portion 20A is omitted.

[0047] 4, the thermoelectric conversion element 23 is attached to the end face of the permanent magnet 21 facing the negative Y-axis so that the magnetization direction MD substantially coincides with the Z-axis direction. Alternatively, the thermoelectric conversion element 23 may be attached to the end face of the permanent magnet 21 facing the positive Y-axis so that the magnetization direction MD substantially coincides with the Z-axis direction. This allows the thermoelectric conversion element 23 to be attached to the permanent magnet 21 even if, for example, a spacer or the like is present between the permanent magnets 21.

[0048] When the temperature of the permanent magnet 21 rises, a heat flow HF is generated that flows into the thermoelectric conversion element 23, which has a relatively low temperature, as in the first example described above. For example, as shown in FIG. 4, the direction of the heat flow HF is approximately in the negative Y-axis direction. Furthermore, when the thermoelectric conversion element 23 is attached to the end face of the permanent magnet 21 facing the positive X-axis, the direction of the heat flow HF is approximately in the positive Y-axis direction. In other words, in this example, the direction of the heat flow HF is in the Y-axis direction. Therefore, when the temperature of the permanent magnet 21 rises, a voltage signal is generated in the thermoelectric conversion element 23 in the approximately X-axis direction, which is perpendicular to both the magnetization direction MD and the direction of the heat flow HF. Therefore, as in the first example described above, the output (voltage signal) of the thermoelectric conversion element 23 can be used to determine whether or not the temperature of the permanent magnet 21 has risen and to what extent. In other words, the thermoelectric conversion element 23 can detect whether or not the temperature of the permanent magnet 21 has risen and to what extent.

[0049] 4, similarly to the first example described above, the leakage magnetic flux LF interlinks the thermoelectric conversion element 23 in approximately the Z-axis direction so as to be approximately aligned with the magnetization direction MD of the thermoelectric conversion element 23. Therefore, it is possible to prevent, for example, a situation in which the thermoelectric conversion element 23 is demagnetized due to an external disturbance or the like, resulting in a decrease or loss of the thermoelectric conversion function.

[0050] [Third example of magnetic field] Next, a third example of the field 20 will be described as shown in FIG.

[0051] In FIG. 5, only the field magnet portion 20B is depicted, and the field magnet portion 20A is omitted.

[0052] In this example, the field 20 includes an auxiliary yoke 24 .

[0053] 5, the thermoelectric conversion element 23 is attached to the end face of the permanent magnet 21 facing in the negative X-axis direction, as in the first example described above. Alternatively, the thermoelectric conversion element 23 may be attached to the end face facing in the positive X-axis direction, as in the first example described above.

[0054] The auxiliary yoke 24 (an example of a yoke portion) is made of any soft magnetic material. The auxiliary yoke 24 is made of, for example, general structural steel, electromagnetic steel sheet, powder magnetic core, etc. The auxiliary yoke 24 includes auxiliary yokes 24A and 24B.

[0055] 5, the auxiliary yoke 24A is attached to the end face of the permanent magnet 21 facing the negative X-axis direction so as to be disposed in the positive Z-axis direction of the thermoelectric conversion element 23. When the thermoelectric conversion element 23 is attached to the end face of the permanent magnet 21 facing the positive X-axis direction, the auxiliary yoke 24A may be attached to the end face of the permanent magnet 21 facing the positive X-axis direction so as to be disposed in the positive Z-axis direction of the thermoelectric conversion element 23.

[0056] 5, the auxiliary yoke 24B is attached to the end face of the permanent magnet 21 facing the negative X-axis direction so as to be disposed in the negative Z-axis direction of the thermoelectric conversion element 23. When the thermoelectric conversion element 23 is attached to the end face of the permanent magnet 21 facing the positive X-axis direction, the auxiliary yoke 24B may be attached to the end face of the permanent magnet 21 facing the positive X-axis direction so as to be disposed in the negative Z-axis direction of the thermoelectric conversion element 23.

[0057] The auxiliary yokes 24A and 24B function as a magnetic path for the leakage magnetic flux LF. Therefore, the leakage magnetic flux LF can be reliably linked to the thermoelectric conversion element 23 located between the auxiliary yokes 24A and 24B in the Z-axis direction. In other words, the auxiliary yoke 24 can induce the leakage magnetic flux LF of the permanent magnet 21 to the thermoelectric conversion element 23. Therefore, for example, by appropriately setting the material, size, shape, etc. of the auxiliary yoke 24, it is possible to efficiently link only the required amount of leakage magnetic flux LF to the thermoelectric conversion element 23.

[0058] [Linear motor control system] Next, the control system 1 for the linear motor 100 will be described with reference to FIG.

[0059] As shown in FIG. 6, the control system 1 includes a linear motor 100, a power conversion device 200, and a control device 300.

[0060] As described above, the linear motor 100 includes the thermoelectric conversion element 23 .

[0061] The output (voltage signal) of the thermoelectric conversion element 23 is input to the control device 300 via a predetermined communication line.

[0062] The predetermined communication line includes, for example, a one-to-one communication line. The predetermined communication line also includes, for example, a local area network (LAN) installed in a predetermined device including the linear motor 100 and the control device 300. The predetermined communication line also includes, for example, a local network (for example, a factory field network) established in a location (for example, a factory) where a predetermined device including the linear motor 100 is installed. The predetermined communication line also includes, for example, a short-distance communication line based on a predetermined wireless communication standard such as WiFi or Bluetooth (registered trademark). The predetermined communication line also includes, for example, a wide area network (WAN). Wide area networks include, for example, a mobile communication network terminated at a base station, a satellite communication network using a communication satellite, the Internet, and the like.

[0063] The power conversion device 200 converts the power supplied from the power supply PS into power for driving the linear motor 100 and outputs the power to the linear motor 100.

[0064] 6, the power conversion device 200 converts three-phase AC power having R, S, and T phases supplied from the power supply PS into three-phase AC power having U, V, and W phases of a predetermined voltage and a predetermined frequency. In this case, the power conversion device 200 may include a rectifier circuit that converts the three-phase AC power supplied from the power supply PS into DC power, a smoothing circuit that smooths the output of the rectifier circuit, and an inverter circuit that converts the output of the smoothing circuit into three-phase AC power having U, V, and W phases. The power conversion device 200 may also be a matrix converter.

[0065] Furthermore, the power conversion device 200 may be an inverter device that converts DC power supplied from the power source PS into three-phase AC power of U-phase, V-phase, and W-phase at a predetermined voltage and a predetermined frequency.

[0066] The control device 300 outputs a control command to the power conversion device 200 to drive and control the linear motor 100 .

[0067] Furthermore, the control device 300 is communicably connected to the thermoelectric conversion element 23, and determines whether there is a sign of thermal demagnetization of the permanent magnet 21, based on a voltage signal received from the thermoelectric conversion element 23. The determination of whether there is a sign of thermal demagnetization of the permanent magnet 21 includes determining whether there is a sign of thermal demagnetization of the permanent magnet 21, determining the degree (level) of the sign of thermal demagnetization of the permanent magnet 21, and the like.

[0068] For example, when the voltage signal of the thermoelectric conversion element 23 exceeds a predetermined threshold, the control device 300 determines that there is a sign of thermal demagnetization of the permanent magnet 21. The predetermined threshold is determined, for example, based on a computer simulation using a three-dimensional model of the linear motor 100 or an experiment using an actual machine model, since the susceptibility to demagnetization varies depending on the material and shape of the permanent magnet 21 and the arrangement of the surrounding soft magnetic material.

[0069] Alternatively, multiple threshold levels may be provided, and the control device 300 may determine the degree of the sign of thermal demagnetization of the permanent magnet 21 according to the relationship between the voltage signal of the thermoelectric conversion element 23 and the multiple threshold levels. Specifically, the control device 300 may determine that the sign of thermal demagnetization of the permanent magnet 21 is at a first level when the voltage signal of the thermoelectric conversion element 23 exceeds the smallest threshold level of the multiple threshold levels. Then, the control device 300 may increase the level of thermal demagnetization of the permanent magnet 21 stepwise each time the voltage signal exceeds a threshold level, and may determine that the sign of thermal demagnetization of the permanent magnet 21 is at the highest level when the voltage signal exceeds the largest threshold level.

[0070] For example, when the control device 300 determines that there is a sign of demagnetization of the permanent magnet 21, it stops the linear motor 100. This makes it possible to suppress the occurrence of thermal demagnetization of the permanent magnet 21.

[0071] Furthermore, when the control device 300 determines that the degree of signs of thermal demagnetization of the permanent magnets 21 is at a first level, it begins restricting the operation of the linear motor 100. Restrictions on the operation of the linear motor 100 include, for example, restrictions on the operating speed or thrust of the linear motor 100. The control device 300 may gradually increase the degree of restriction on the operation of the linear motor 100 each time the degree (level) of thermal demagnetization of the permanent magnets 21 increases, and may stop the linear motor 100 when it determines that the degree of signs of thermal demagnetization of the permanent magnets 21 is at the highest level. On the other hand, the control device 300 may release the restriction on the linear motor 100 when the voltage signal of the thermoelectric conversion element 23 falls below a first threshold before the degree of signs of thermal demagnetization of the permanent magnets 21 reaches the highest level. This makes it possible to suppress the occurrence of thermal demagnetization of the permanent magnets 21 while continuing operation of the linear motor 100.

[0072] [Other embodiments] The above-described embodiment may be modified or changed as appropriate.

[0073] For example, the auxiliary yoke 24 of the third example of the field 20 described above may be combined with the field 20 of the second example described above.

[0074] Furthermore, for example, in the above-described embodiment and its modified examples, in addition to the permanent magnets 21, auxiliary permanent magnets (hereinafter referred to as "auxiliary magnets") (an example of a second permanent magnet) may be added to relatively strengthen the magnetic flux of the magnetic poles of the permanent magnets 21 at their end faces in the Z-axis direction facing the armature 10. That is, the field 20 may have a Halbach array magnetic circuit structure by the permanent magnets 21 as main magnets and the auxiliary magnets. In this case, for example, the auxiliary magnets may be arranged between the permanent magnets 21 arranged in the X-axis direction so that their magnetization directions are in the X-axis direction. Furthermore, the auxiliary magnets may be arranged adjacent to each permanent magnet 21 in both the positive Y-axis direction and the negative Y-axis direction so that their magnetization directions are in the Y-axis direction. Specifically, the auxiliary magnets adjacent to the permanent magnets 21 whose magnetization directions face the armature 10 are arranged so that their magnetization directions face the permanent magnets 21, and the auxiliary magnets adjacent to the permanent magnets 21 whose magnetization directions face away from the armature 10 are arranged so that their magnetization directions are away from the permanent magnets 21. In this case, the thermoelectric conversion element 23 is attached to a surface of the permanent magnet 21 that is not adjacent to an auxiliary magnet, for example, the end face in the Y-axis direction, as in the second example described above.

[0075] Furthermore, for example, in the above-described embodiment and its modified examples, one of field magnet portions 20A, 20B may be omitted.

[0076] Furthermore, for example, in the above-described embodiment and its modified examples, the back yoke 22 may be omitted.

[0077] Furthermore, for example, in the above-described embodiment and its modified examples, the core 11 may be omitted, and the armature 10 may have a coreless structure.

[0078] Furthermore, the configurations of the above-described embodiments and their modified examples may be employed in a linear motor in which the field magnet is the mover and the armature is the stator. In this case, the field magnet as the mover may be disposed at the position of armature 10 as the mover in FIG. 1, and the armature as the stator may be disposed at the positions of field magnet sections 20A and 20B as the stator. In other words, the field magnet as the mover and the armature as the stator may be disposed in such a way that two armatures sandwich one field magnet in the Z-axis direction.

[0079] Furthermore, the configurations of the above-described embodiments and their modifications may be employed in a rotary motor (rotating machine) including a field that generates a magnetic field using permanent magnets and an armature. In this case, the X-axis direction, Y-axis direction, and Z-axis direction in the above-described embodiments and their modifications correspond to the circumferential direction, axial direction, and radial direction of the rotary motor, respectively.

[0080] Furthermore, in the above-described embodiment and its variations, the control system 1 may include a monitoring device different from the control device 300, and the monitoring device may monitor signs of thermal demagnetization of the permanent magnets 21 in accordance with a voltage signal received from the thermoelectric conversion elements 23. In this case, for example, when the voltage signal received from the thermoelectric conversion elements 23 exceeds a predetermined threshold, the monitoring device may determine that there is a sign of thermal demagnetization in the permanent magnets 21 and send a stop signal to the control device 300 instructing the linear motor 100 to stop. Furthermore, when the voltage signal received from the thermoelectric conversion elements 23 exceeds one of a plurality of thresholds, the monitoring device may send a restriction signal to the control device 300 instructing the control device to restrict operation of the linear motor 100 at a level corresponding to the threshold. Furthermore, in this case, the function of the monitoring device may be incorporated into the linear motor 100 or the rotary motor. Furthermore, in this case, the monitoring device may monitor multiple linear motors 100 for thermal demagnetization of the permanent magnets 21. Furthermore, in this case, the monitoring device may be installed in a location different from the location where the equipment in which the linear motor 100 is used is installed. For example, the monitoring device is a server device such as an on-premise server or a cloud server, and monitors the thermal demagnetization of the permanent magnet 21 from a remote location.

[0081] [Effect] Next, the operation of the linear motor 100 (field 20) and the control system 1 according to this embodiment will be described.

[0082] For example, the magnetic circuit may be designed to suppress thermal demagnetization due to overheating of the permanent magnet 21. Also, for example, it is possible to detect signs of thermal demagnetization of the permanent magnet 21 by attaching a temperature sensor to the surface of the permanent magnet 21 to monitor the temperature of the permanent magnet 21. Also, for example, it is possible to suppress thermal demagnetization of the permanent magnet 21 due to overheating by generating electricity by bringing a thermoelectric conversion element into thermal contact with the coil 12.

[0083] However, no matter how appropriately the magnetic circuit is designed, if an unexpected excessive current flows through the coil 12, the temperature of the permanent magnet 21 may rise suddenly, possibly resulting in thermal demagnetization of the permanent magnet 21. Furthermore, if the temperature of a certain portion of the permanent magnet 21 rises suddenly, the temperature sensor on the surface of the permanent magnet 21 may not be able to detect the temperature rise quickly, which may result in a delayed response and thermal demagnetization of the permanent magnet 21. Furthermore, even if the coil 12 is cooled by causing the thermoelectric conversion element to generate power using the heat of the coil 12, if an unexpected excessive current flows through the coil 12, the cooling effect of the power generation by the thermoelectric conversion element may not be able to respond quickly, and as a result, the temperature of the permanent magnet 21 may rise to a level that causes demagnetization.

[0084] In contrast to this, in this embodiment, the field magnet 20 includes a permanent magnet 21 and a thermoelectric conversion element 23. Specifically, the permanent magnet 21 generates a magnetic field for the armature 10. The thermoelectric conversion element 23 is attached to the permanent magnet 21.

[0085] This allows the thermoelectric conversion element 23 to output an electric signal in response to the heat flow from the permanent magnet 21. Therefore, it is possible to quickly detect signs of a temperature rise that may lead to thermal demagnetization of the permanent magnet 21 in response to the output of the thermoelectric conversion element 23, and take measures to suppress thermal demagnetization of the permanent magnet 21, such as stopping the linear motor 100. Therefore, it is possible to more appropriately suppress thermal demagnetization of the permanent magnet 21 of the field 20.

[0086] In this embodiment, the thermoelectric conversion element 23 may be provided on a surface different from the magnetic pole surface of the permanent magnet 21.

[0087] This makes it possible to prevent the thermoelectric conversion element 23 from affecting the magnetic flux of the permanent magnet 21. It is also possible to prevent a situation in which the direction of the heat flow from the permanent magnet 21 and the direction of the magnetic flux are substantially the same, thereby hindering the thermoelectric conversion function of the thermoelectric conversion element 23, which has a magneto-thermoelectric effect based on the premise that the direction of the heat flow and the magnetization direction are perpendicular to each other.

[0088] In this embodiment, the field magnet 20 may be provided with an auxiliary magnet that is adjacent to the permanent magnet 21 and enhances the magnetic flux of the magnetic pole of the permanent magnet 21 that faces the armature 10. The thermoelectric conversion element 23 may be provided on a surface of the permanent magnet 21 that is different from the surface that is adjacent to the auxiliary magnet.

[0089] This allows the thermoelectric conversion element 23 to be attached to the permanent magnet 21 while realizing a Halbach array magnetic circuit structure using the permanent magnet 21 and the auxiliary magnet.

[0090] In this embodiment, the thermoelectric conversion element 23 may be a magneto-thermoelectric conversion element that generates a voltage signal by the magneto-thermoelectric effect, such as the anomalous Nernst effect or the spin Seebeck effect.

[0091] This allows the thermoelectric conversion element 23 to generate a relatively large response signal (voltage signal) in response to the heat flow from the permanent magnet 21. Therefore, it is possible to quickly detect signs of a temperature rise that may lead to thermal demagnetization of the permanent magnet 21 in response to the voltage signal of the thermoelectric conversion element 23. Furthermore, because the magneto-thermoelectric effect allows a voltage signal to be generated in a direction perpendicular to the direction of the heat flow, it is possible to reduce the size and simplify the thermoelectric conversion element 23.

[0092] In this embodiment, the field magnet 20 may also include an auxiliary yoke 24 that guides leakage magnetic flux of the permanent magnet 21 to the thermoelectric conversion element 23.

[0093] This allows the leakage magnetic flux of the permanent magnet 21 to be efficiently linked to the thermoelectric conversion element 23. Therefore, for example, by constantly linking the leakage magnetic flux of the permanent magnet 21, which is in approximately the same direction as the magnetization direction of the thermoelectric conversion element 23, to the thermoelectric conversion element 23, it is possible to suppress a decrease in the performance of detecting a temperature rise in the permanent magnet 21 that is caused by demagnetization of the thermoelectric conversion element 23 due to external disturbances or the like.

[0094] In addition, in this embodiment, the control system 1 includes a rotating machine or linear motor 100 including a field magnet 20 and an armature 10, and a control device 300 that controls the rotating machine or linear motor 100 based on the output of the thermoelectric conversion element 23.

[0095] This allows the control device 300 to quickly recognize signs of a temperature rise that may lead to thermal demagnetization of the permanent magnet 21, based on the output of the thermoelectric conversion element 23. Therefore, the control device 300 can more appropriately suppress thermal demagnetization of the permanent magnet 21 by performing control such as stopping the rotating machine or the linear motor 100 in response to signs of a temperature rise that may lead to thermal demagnetization of the permanent magnet 21.

[0096] Although the embodiments have been described in detail above, the present disclosure is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist described in the claims. [Explanation of symbols]

[0097] 1. Control System 10 Armature 11 cores 12 coils 13 Holding part 20 Field 20A field magnet 20B Field magnet part 21 Permanent magnets 22 Back Yoke 23 Thermoelectric conversion element 24 Auxiliary yoke 24A Auxiliary Yoke 24B Auxiliary Yoke 100 Linear Motor 200 Power conversion device 300 control device AG void HF heat flow LF magnetic flux MD magnetization direction MF main magnetic flux PS power supply

Claims

1. a first permanent magnet that generates a magnetic field relative to the armature; a second permanent magnet adjacent to the first permanent magnet and enhancing the magnetic flux of the magnetic pole of the first permanent magnet facing the armature; a thermoelectric conversion element attached to the first permanent magnet, the thermoelectric conversion element is provided on a surface of the first permanent magnet different from a surface adjacent to the second permanent magnet; Permanent magnet field.

2. the thermoelectric conversion element is provided on a surface different from a magnetic pole surface of the first permanent magnet; 10. The permanent magnet field of claim 1.

3. The thermoelectric conversion element is a magneto-thermoelectric conversion element that generates a voltage signal by a magneto-thermoelectric effect.

3. A permanent magnet field according to claim 1 or 2.

4. The magneto-thermoelectric effect is the anomalous Nernst effect or the spin Seebeck effect.

4. The permanent magnet field of claim 3.

5. a yoke portion that guides leakage magnetic flux of the first permanent magnet to the thermoelectric conversion element, 5. A permanent magnet field according to claim 3 or 4.

6. A permanent magnet field according to any one of claims 1 to 5; the armature, Rotating machine.

7. A permanent magnet field according to any one of claims 1 to 5; the armature, Linear motor.

8. a rotating machine or a linear motor including the permanent magnet field according to any one of claims 1 to 5 and the armature; a control device that controls the rotating machine or the linear motor based on the output of the thermoelectric conversion element, Control system.

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