JP7782289B2 - Permanent magnet field, rotating machine, linear motor, control system - Google Patents

Description

This disclosure relates to permanent magnet fields, etc.

For example, technology is known for suppressing thermal demagnetization of permanent magnet fields in electric motors such as rotating machines and linear motors (see Patent Document 1).

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, thereby lowering the temperature of the coil and suppressing thermal demagnetization of the permanent magnet field.

Japanese Patent Application Laid-Open No. 2002-153036

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

In view of the above issues, the objective is to provide technology that can more appropriately suppress thermal demagnetization of permanent magnet fields.

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 different from a surface adjacent to the second permanent magnet ;
A permanent magnet field is provided.

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

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

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.

The above-described embodiment makes it possible to more appropriately suppress thermal demagnetization of the permanent magnet field.

FIG. 1 is a side cross-sectional view showing an example of a linear motor. FIG. 2 is a plan cross-sectional view showing an example of an armature. FIG. 2 is a side view showing a first example of a field magnet. FIG. 10 is a front cross-sectional view showing a second example of a field magnet. FIG. 10 is a side view showing a third example of a field magnet. FIG. 1 is a diagram illustrating an example of a control system for a linear motor.

The following describes the embodiment with reference to the drawings.

[Linear motor overview]
An overview of a linear motor 100 according to this embodiment will be described with reference to FIGS. 1 and 2. FIG.

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

In the following, explanations may be given using a Cartesian coordinate system defined by the X-axis, Y-axis, and Z-axis in the figures. Furthermore, the positive X-axis direction and negative X-axis direction may be collectively referred to as the X-axis direction, the positive Y-axis direction and negative Y-axis direction may be collectively referred to as the Y-axis direction, and the positive Z-axis direction and negative Z-axis direction may be collectively referred to as the Z-axis direction.

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

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

The armature 10 is positioned 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 so that it can move in the X-axis direction by a support mechanism such as a slide rail or linear guide. This allows the armature 10 to move in the X-axis direction due to the magnetic force acting between it and the field magnet 20. The armature 10 includes a core (also called an "iron core") 11, a coil (also called a "winding") 12, and a holding portion 13.

The cores 11 function as magnetic paths for the magnetic fields generated by the armature current in the coils 12 and the magnetic fields from the permanent magnets 21 of the field 20. The cores 11 are made of a soft magnetic material, such as an electromagnetic steel sheet or a powder magnetic core. In this example, multiple cores 11 (12 pieces) are provided, the same number as the coils 12.

For example, as shown in Figures 1 and 2, the core 11 has a rectangular column shape extending in the Z-axis direction, and is configured so that the cross-sectional shape of both ends in the Z-axis direction is larger than the cross-sectional shape of the center in the Z-axis direction. As a result, even if the core 11 attempts to move in the positive Z-axis direction, the end of the core 11 in the negative Z-axis direction abuts the retaining portion 13, preventing the core 11 from moving in the positive Z-axis direction. This prevents the core 11 from falling off the armature 10 as it moves in the positive Z-axis direction. A similar effect can also prevent the core 11 from falling off the armature 10 as it moves in the negative Z-axis direction.

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

In this example, multiple (12) coils 12 are provided. The multiple coils 12 are aligned in the X-axis direction. For example, the multiple coils 12 are supplied with three-phase AC power of U-phase, V-phase, and W-phase. Specifically, three-phase AC power of U-phase, V-phase, W-phase, U-phase, V-phase, W-phase, ... may be supplied in order from the coil 12 at the end on the negative side of the X-axis in the figure toward the positive side of the X-axis.

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

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

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 Figure 1, the field 20 is arranged to extend in the X-axis direction, and its dimension in the X-axis direction is determined according to the amount of movement of the armature 10 as a mover in the X-axis direction.

The field magnet 20 includes field magnet portions 20A and 20B.

Field magnet portions 20A, 20B are arranged to extend approximately parallel to each other in the X-axis direction. The term "approximately" is intended to allow for manufacturing errors, for example, and will be used in the same manner hereinafter. A predetermined gap is provided between field magnet portions 20A, 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, 20B corresponds to the dimension of armature 10 in the Z-axis direction plus the amount of movement of the armature 10's support mechanism (e.g., 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, 20B.

Field magnet sections 20A and 20B are arranged to face each other in the positive and negative Z-axis directions, respectively, when viewed from the armature 10. Field magnet sections 20A and 20B each generate magnetic flux that interlinks with the multiple coils 12 of the armature 10.

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

The multiple permanent magnets 21 (an example of first permanent magnets) are arranged in a line 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 roughly rectangular parallelepiped shape with sides in the X-axis, Y-axis, and Z-axis directions, and are arranged in a line at roughly equal intervals in the X-axis direction. Spacers may also 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 or ferrite magnets.

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., the arrangement position of permanent magnets 21 in the X-axis direction and the arrangement method, including the presence or absence of a Halbach array, etc.) of each permanent magnet 21 are substantially the same. This allows field magnet portion 20A and field magnet portion 20B to generate substantially symmetrical magnetic fields in the spaces facing each other in the Z-axis direction.

The back yoke 22 is arranged in the Z-axis direction adjacent to the surface of the permanent magnet 21 opposite 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.

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 in 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 for detecting a temperature rise in the permanent magnet 21 is ensured.

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 Co ₂ MnGa 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 a double-layer film of a magnetic insulator and a metal, in which 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.

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

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

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

Figure 3 is a side view showing a first example of the field magnet 20.

Note that in Figure 3, only the field magnet portion 20B is depicted, and the field magnet portion 20A is omitted.

As shown in FIG. 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 is approximately aligned 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 is approximately aligned with the Z-axis direction. This allows the thermoelectric conversion element 23 to be positioned by utilizing the space between the permanent magnets 21.

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. In other words, 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, the thermoelectric conversion element 23 generates a voltage signal 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, 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.

Furthermore, as shown in Figure 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.

As shown in Figure 3, leakage magnetic flux LF interlinks the thermoelectric conversion element 23 in approximately the Z-axis direction, so as to approximately coincide with its magnetization direction MD. This prevents situations in which the thermoelectric conversion element 23 is demagnetized due to external disturbances, resulting in a decrease or loss of thermoelectric conversion function.

[Second example of field]
4 is a front cross-sectional view showing a second example of the field magnet 20. Specifically, FIG. 4 is a cross-sectional view of the field magnet 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.

Note that in Figure 4, only the field magnet portion 20B is depicted, and the field magnet portion 20A is omitted.

As shown in FIG. 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 is approximately aligned 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 is approximately aligned 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.

As 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, if 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, as the temperature of the permanent magnet 21 rises, the thermoelectric conversion element 23 generates a voltage signal 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.

Furthermore, as shown in Figure 4, similar to the first example described above, leakage magnetic flux LF interlinks the thermoelectric conversion element 23 in approximately the Z-axis direction so as to approximately coincide with its magnetization direction MD. Therefore, it is possible to prevent situations in which the thermoelectric conversion element 23 is demagnetized due to, for example, external disturbances, resulting in a decrease or loss of thermoelectric conversion function.

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

Note that in Figure 5, only the field magnet portion 20B is depicted, and the field magnet portion 20A is omitted.

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

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

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, or powder magnetic core. The auxiliary yoke 24 includes auxiliary yokes 24A and 24B.

For example, as shown in FIG. 5, the auxiliary yoke 24A is attached to the end face of the permanent magnet 21 facing the negative X-axis so that it is positioned in the positive Z-axis direction of the thermoelectric conversion element 23. Also, when the thermoelectric conversion element 23 is attached to the end face of the permanent magnet 21 facing the positive X-axis, the auxiliary yoke 24A may be attached to the end face of the permanent magnet 21 facing the positive X-axis so that it is positioned in the positive Z-axis direction of the thermoelectric conversion element 23.

For example, as shown in FIG. 5, the auxiliary yoke 24B is attached to the end face of the permanent magnet 21 facing the negative X-axis so as to be positioned in the negative Z-axis direction of the thermoelectric conversion element 23. Also, if the thermoelectric conversion element 23 is attached to the end face of the permanent magnet 21 facing the positive X-axis, the auxiliary yoke 24B may be attached to the end face of the permanent magnet 21 facing the positive X-axis so as to be positioned in the negative Z-axis direction of the thermoelectric conversion element 23.

The auxiliary yokes 24A and 24B function as a magnetic path for leakage magnetic flux LF. This ensures that 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 leakage magnetic flux LF from the permanent magnet 21 to the thermoelectric conversion element 23. Therefore, for example, by appropriately selecting 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.

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

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

As described above, the linear motor 100 includes a thermoelectric conversion element 23.

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

The specified communication line includes, for example, a one-to-one communication line. It also includes, for example, a local area network (LAN) installed in specified equipment including the linear motor 100 and the control device 300. It also includes, for example, a local network (for example, a factory field network) established in a location (for example, a factory) where specified equipment including the linear motor 100 is installed. It also includes, for example, a short-range communication line based on a specified wireless communication standard such as Wi-Fi or Bluetooth (registered trademark). It also includes, for example, a wide area network (WAN). Wide area networks include, for example, mobile communication networks terminated at base stations, satellite communication networks using communication satellites, and the Internet.

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

For example, as shown in FIG. 6, the power conversion device 200 converts three-phase AC power of R, S, and T phases supplied from the power source PS into three-phase AC power of U, V, and W phases at 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 source 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 of U, V, and W phases. The power conversion device 200 may also be a matrix converter.

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

The control device 300 outputs control commands to the power conversion device 200 and controls the drive of the linear motor 100.

The control device 300 is also communicatively connected to the thermoelectric conversion element 23 and determines whether there are signs of thermal demagnetization of the permanent magnet 21 based on the voltage signal received from the thermoelectric conversion element 23. Determining whether there are signs of thermal demagnetization of the permanent magnet 21 includes determining whether there are signs of thermal demagnetization of the permanent magnet 21, and determining the degree (level) of the signs of thermal demagnetization of the permanent magnet 21.

For example, if the voltage signal of the thermoelectric conversion element 23 exceeds a predetermined threshold, the control device 300 determines that there are signs of thermal demagnetization of the permanent magnet 21. The predetermined threshold is determined, for example, based on computer simulations using a three-dimensional model of the linear motor 100 or experiments using an actual 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.

In addition, multiple threshold levels may be provided, and the control device 300 may determine the degree of signs of thermal demagnetization of the permanent magnet 21 based on the relationship between the voltage signal of the thermoelectric conversion element 23 and the multiple threshold levels. Specifically, when the voltage signal of the thermoelectric conversion element 23 exceeds the smallest of the multiple threshold levels, the control device 300 may determine that the signs of thermal demagnetization of the permanent magnet 21 are at a first level. Then, the control device 300 may increase the level of thermal demagnetization of the permanent magnet 21 in a stepwise manner each time the voltage signal exceeds the threshold level, and when the largest threshold level is exceeded, determine that the signs of thermal demagnetization of the permanent magnet 21 are at the highest level.

For example, if the control device 300 determines that there are signs 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.

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 and thrust of the linear motor 100. The control device 300 then gradually increases 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 the first threshold before the degree of signs of thermal demagnetization of the permanent magnets 21 reaches the highest level. This allows the linear motor 100 to continue operating while suppressing the occurrence of thermal demagnetization of the permanent magnets 21.

Other Embodiments
The above-described embodiment may be modified or changed as appropriate.

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

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 with 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 aligned in the X-axis direction so that their magnetization direction is in the X-axis direction. Furthermore, the auxiliary magnets may be arranged adjacent to each permanent magnet 21 in both the positive and negative Y-axis directions so that their magnetization direction is in the Y-axis direction. Specifically, the auxiliary magnets adjacent to the permanent magnets 21 whose magnetization direction faces the armature 10 are arranged so that their magnetization direction faces the permanent magnet 21, and the auxiliary magnets adjacent to the permanent magnets 21 whose magnetization direction faces away from the armature 10 are arranged so that their magnetization direction faces 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 surface in the Y-axis direction, as in the second example described above.

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

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

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

Furthermore, the configurations of the above-described embodiments and their variations may be employed in a linear motor in which the field is the mover and the armature is the stator. In this case, the field 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 position of field magnet portions 20A and 20B as the stator. In other words, the field as the mover and the armature as the stator may be disposed in such a way that two armatures sandwich one field in the Z-axis direction.

Furthermore, the configurations of the above-described embodiments and their variations may be employed in a rotary motor (rotating machine) that includes 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 variations correspond to the circumferential direction, axial direction, and radial direction of the rotary motor, respectively.

In the above-described embodiment and its variations, the control system 1 may include a monitoring device separate from the control device 300, and the monitoring device may monitor for signs of thermal demagnetization of the permanent magnet 21 in response to a voltage signal received from the thermoelectric conversion element 23. In this case, for example, if the voltage signal received from the thermoelectric conversion element 23 exceeds a predetermined threshold, the monitoring device may determine that the permanent magnet 21 is showing signs of thermal demagnetization and send a stop signal to the control device 300 instructing it to stop the linear motor 100. Furthermore, if the voltage signal received from the thermoelectric conversion element 23 exceeds one of multiple thresholds, the monitoring device may send a restriction signal to the control device 300 instructing it to restrict operation of the linear motor 100 at a level corresponding to the threshold. In this case, the monitoring device's functionality may be incorporated into the linear motor 100 or a rotary motor. In this case, the monitoring device may monitor multiple linear motors 100 for thermal demagnetization of the permanent magnet 21. In this case, the monitoring device may be installed in a location separate from the location where the equipment using the linear motor 100 is installed. For example, the monitoring device is a server device such as an on-premise server or cloud server, and remotely monitors the thermal demagnetization of the permanent magnet 21.

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

For example, the magnetic circuit may be designed to suppress thermal demagnetization due to overheating of the permanent magnet 21. It is also possible to detect signs of thermal demagnetization of the permanent magnet 21 by, for example, attaching a temperature sensor to the surface of the permanent magnet 21 to monitor the temperature of the permanent magnet 21. It is also possible to suppress thermal demagnetization of the permanent magnet 21 due to overheating by, for example, suppressing heat generation in the coil 12 by placing a thermoelectric conversion element in thermal contact with the coil 12 to generate electricity.

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, potentially leading to thermal demagnetization of the permanent magnet 21. Furthermore, if the temperature of a certain part 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 could result in a delayed response and lead to thermal demagnetization of the permanent magnet 21. Furthermore, even if an attempt is made to cool the coil 12 by using the heat of the coil 12 to generate electricity in the thermoelectric conversion element, if an unexpected, excessive current flows through the coil 12, the cooling effect of the power generation by the thermoelectric conversion element cannot respond quickly enough, and as a result, the temperature of the permanent magnet 21 may rise to a level that causes demagnetization.

In contrast, 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.

This allows the thermoelectric conversion element 23 to output an electrical signal in response to the heat flow from the permanent magnet 21. Therefore, signs of a temperature rise that could lead to thermal demagnetization of the permanent magnet 21 can be quickly detected in response to the output of the thermoelectric conversion element 23, and measures can be taken to suppress thermal demagnetization of the permanent magnet 21, such as stopping the linear motor 100. This makes it possible to more appropriately suppress thermal demagnetization of the permanent magnet 21 of the field 20.

In addition, in this embodiment, the thermoelectric conversion element 23 may be provided on a surface other than the magnetic pole surface of the permanent magnet 21.

This prevents the thermoelectric conversion element 23 from affecting the magnetic flux of the permanent magnet 21. It also prevents a situation in which, for example, the direction of heat flow from the permanent magnet 21 and the direction of magnetic flux are roughly the same, thereby hindering the thermoelectric conversion function of the thermoelectric conversion element 23, which has a magnetothermoelectric effect based on the premise that the direction of heat flow and the magnetization direction are perpendicular to each other.

In addition, in this embodiment, the field magnet 20 may be provided with an auxiliary magnet adjacent to the permanent magnet 21, which increases 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 adjacent to the auxiliary magnet.

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 auxiliary magnet.

In addition, 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. The magneto-thermoelectric effect is, for example, the anomalous Nernst effect or the spin Seebeck effect.

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, signs of a temperature rise that could lead to thermal demagnetization of the permanent magnet 21 can be quickly detected in response to the voltage signal from 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, the thermoelectric conversion element 23 can be made smaller and simpler.

In addition, in this embodiment, the field magnet 20 may be provided with an auxiliary yoke 24 that guides leakage magnetic flux from the permanent magnet 21 to the thermoelectric conversion element 23.

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 ability to detect temperature increases in the permanent magnet 21 due to demagnetization of the thermoelectric conversion element 23 caused by external disturbances, etc.

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.

This allows the control device 300 to quickly recognize signs of a temperature rise that could 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 linear motor 100 in response to signs of a temperature rise that could lead to thermal demagnetization of the permanent magnet 21.

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.

REFERENCE SIGNS LIST 1 Control system 10 Armature 11 Core 12 Coil 13 Holding section 20 Field magnet 20A Field magnet section 20B Field magnet section 21 Permanent magnet 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 Air gap HF Heat flow LF Magnetic flux MD Magnetization direction MF Main magnetic flux PS Power supply

Claims (8)

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. 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. 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 . The magneto-thermoelectric effect is the anomalous Nernst effect or the spin Seebeck effect.
4. The permanent magnet field of claim 3 . 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 . A permanent magnet field according to any one of claims 1 to 5 ;
the armature,
Rotating machine. A permanent magnet field according to any one of claims 1 to 5 ;
the armature,
Linear motor. 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.