Temperature information output device, rotary electric machine, and temperature acquisition device

Abstract

This temperature information output device comprises: an element unit provided to a rotor; an element unit provided to a stator; and an output unit. The electric resistance of a temperature-sensitive element changes according to the temperature of a portion of the rotor. A coil is electrically connected to the temperature-sensitive element. A capacitor constitutes an LC resonance circuit with the coil. A coil is magnetically coupled to the coil. A capacitor constitutes an LC resonance circuit with the coil. The output unit is electrically connected to the element unit. The output unit outputs, as temperature information, the phase difference between the phase of the voltage applied to the element unit and the phase of the voltage at the output unit.

Description

Temperature information output device, rotating electrical machine, and temperature acquisition device

[0001] The present disclosure relates to a temperature information output device, a rotating electric machine provided with the temperature information output device, and a temperature acquisition device including the temperature information output device.

[0002] A temperature information output device is known that is provided in a rotating electric machine having a stator and a rotor and outputs temperature information related to the temperature of a portion of the rotor. For example, the temperature information output device disclosed in Patent Document 1 includes a temperature sensor. The temperature sensor is provided in the rotor and its electrical resistance changes depending on the temperature of the portion.

[0003] Japanese Patent Application Laid-Open No. 2021-39019

[0004] The operation of a rotating electric machine can cause the temperature inside the machine to rise. Temperature changes inside the rotating electric machine can affect the operation of the rotating electric machine. For example, the magnetic force of a magnet can change depending on the temperature of the magnet. Therefore, it is possible to acquire temperature information about the rotor.

[0005] For example, in Patent Document 1, a rotor is provided with a temperature-sensing element and a first coil electrically connected to the temperature-sensing element. A second coil magnetically coupled to the first coil is provided in the stator, and an output unit outputs an electrical signal corresponding to the magnitude of the current flowing through the second coil. In this configuration, the electrical signal output from the output unit may vary due to, for example, variations in the characteristics of the temperature-sensing element and variations in the relative positions of the first coil and the second coil. Therefore, if the electrical signal output from the output unit varies, the accuracy of temperature information in the rotor may decrease.

[0006] An object of one aspect of the present disclosure is to provide a temperature information output device that can ensure the accuracy of temperature information of a rotor.An object of another aspect of the present disclosure is to provide a rotating electric machine that includes the above-described temperature information output device.An object of yet another aspect of the present disclosure is to provide a temperature acquisition device that includes the above-described temperature information output device.

[0007] A temperature information output device according to one aspect is provided in a rotating electric machine having a stator and a rotor, and outputs temperature information related to the temperature of a portion of the rotor. The temperature information output device includes a first element unit provided in the rotor, a second element unit provided in the stator, and an output section. The first element unit has a temperature sensing element, a first coil, and a first capacitor. The temperature sensing element changes its electrical resistance depending on the temperature of the portion. The first coil is electrically connected to the temperature sensing element. The first capacitor forms an LC resonant circuit together with the first coil. The second element unit has a second coil and a second capacitor. The second coil is magnetically coupled to the first coil. The second capacitor forms an LC resonant circuit together with the second coil. The output section is electrically connected to the second element unit. The output section outputs the phase difference between the phase of the voltage applied to the second element unit and the phase of the voltage at the output section as temperature information.

[0008] In one aspect of the temperature information output device, the output unit outputs the phase difference between the phase of the voltage applied to the second element unit and the phase of the voltage at the output unit as temperature information. That is, temperature information relating to the temperature of a portion of the rotor is output from the output unit as a phase difference. In this case, the accuracy of the temperature information at the rotor can be ensured.

[0009] In the above-described one aspect, the capacitance of the first capacitor may be equal to or greater than half the capacitance of the second capacitor, in which case the accuracy of the temperature information in the rotor can be further improved.

[0010] In the above aspect, the temperature information output device may further include an electric resistance element electrically connected to the second element unit, which can further improve the accuracy of the temperature information of the rotor.

[0011] In the one aspect, the temperature information output device according to claim 1, wherein the part is a magnet provided in the rotor. In this case, the accuracy of the temperature information relating to the temperature of the magnet can be ensured.

[0012] A rotating electric machine according to another aspect is provided with the above-described temperature information output device.

[0013] In the above-mentioned another aspect, the temperature information output device is provided, and therefore temperature information on the rotor is output as an electrical signal related to the phase difference.

[0014] A temperature acquisition device according to yet another aspect includes the temperature information output device described above, acquires temperature information output from the temperature information output device, and obtains the temperature of the rotor based on the acquired temperature information. Since the yet another aspect includes the temperature information output device described above, the temperature of the rotor is obtained based on an electrical signal related to the phase difference.

[0015] According to one aspect of the present disclosure, there is provided a temperature information output device capable of ensuring accuracy of temperature information of a rotor. According to another aspect of the present disclosure, there is provided a rotating electric machine including the above-described temperature information output device. According to yet another aspect of the present disclosure, there is provided a temperature acquisition device including the above-described temperature information output device.

[0016] FIG. 1 is a schematic diagram showing the configuration of a temperature information output device and a rotating electric machine according to one embodiment. FIG. 2 is a circuit diagram showing an example of a temperature information output device. FIG. 3 is a graph showing the frequency dependence of the phase difference for each magnet temperature. FIG. 4 is a diagram showing the cross-sectional configuration of a rotor core. FIG. 5 is a diagram showing the cross-sectional configuration of a rotor core in a modified example of this embodiment. FIG. 6 is a diagram showing the cross-sectional configuration of a rotor core in a modified example of this embodiment. FIG. 7 is a circuit diagram showing an example of a temperature information output device in a modified example of this embodiment. FIG. 8 is a graph showing the frequency dependence of voltage for each magnet temperature. FIG. 9 is a graph showing the temperature dependence of detected voltage. FIG. 10 is a graph showing the temperature dependence of detected phase.

[0017] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the description, the same elements or elements having the same functions will be denoted by the same reference numerals, and redundant description will be omitted.

[0018] 1 to 4, the configuration of a temperature information output device 1 according to this embodiment and a rotating electric machine MT provided with the temperature information output device 1 will be described. Fig. 1 is a schematic diagram showing the configuration of the temperature information output device and the rotating electric machine according to this embodiment.

[0019] As shown in FIG. 1 , the temperature information output device 1 is provided in a rotating electric machine MT. The rotating electric machine MT is, for example, a motor. The motor includes, for example, an IPM motor or an SPM motor. The motor may also be a wound-field motor. Unless otherwise specified, the following description will be given of an example in which the rotating electric machine MT is an IPM motor. As shown in FIG. 1 , the rotating electric machine MT includes a stator 10 and a rotor 20. The rotor 20 is located inside the stator 10.

[0020] The rotor 20 includes a shaft 21, a rotor core 23, and a plurality of magnets 25. The shaft 21 has a cylindrical shape. The rotor core 23 has a cylindrical shape. An axial hole into which the shaft 21 is fitted is formed in the rotor core 23. The shaft 21 and the rotor core 23 rotate together around the central axis of the shaft 21.

[0021] Each magnet 25 is arranged in the rotor core 23 so that its extension direction is parallel to the central axis of the shaft 21. "The extension direction of the magnet 25 is parallel to the central axis of the shaft 21" does not necessarily mean that the extension direction of the magnet 25 is parallel to the central axis of the shaft 21. Even if slight differences, manufacturing errors, or measurement errors within a preset range are included, the extension direction of the magnet 25 may be considered to be parallel to the central axis of the shaft 21. If slight differences within a preset range are included, for example, if the angle between the extension direction of the magnet 25 and the central axis of the shaft 21 is within a range of ±2 degrees, the extension direction of the magnet 25 may be considered to be parallel to the central axis of the shaft 21.

[0022] The central axis of the shaft 21 is the rotation axis of the rotor 20. The direction in which the rotation axis of the rotor 20 extends is the rotation axis direction D of the rotor 20. One magnet may constitute one pole, or multiple magnets may constitute one pole. When one magnet constitutes one pole, the multiple magnets 25 are arranged at equal angular intervals with respect to the rotation axis of the rotor 20. "Even angular intervals" does not necessarily mean that the angular intervals are the same. The angular intervals may be considered equal even if slight differences, manufacturing errors, or measurement errors are included within a predetermined range. If slight differences are included within a predetermined range, for example, if each angular interval of the magnets 25 with respect to the rotation axis of the rotor 20 is within a range of ±10% of the average angular interval of all angular intervals, the angular intervals of the magnets 25 with respect to the rotation axis of the rotor 20 may be considered equal.

[0023] When the rotating electric machine MT is an IPM motor, the multiple magnets 25 are arranged inside the rotor core 23. When the rotating electric machine MT is an SPM motor, the multiple magnets 25 are arranged on the surface of the rotor core 23. The magnets 25 are, for example, permanent magnets. The magnets 25 include rare earth permanent magnets. The magnets 25 include, for example, neodymium sintered magnets. The magnets 25 may include sintered magnets other than rare earth permanent magnets, or may include magnets other than sintered magnets. The magnets other than sintered magnets include, for example, bonded magnets or hot-worked magnets.

[0024] The stator 10 includes a cylindrical stator core (not shown) that surrounds the outer periphery of the rotor 20, and multiple stator coils 11. The stator 10 may further include a case that surrounds the stator core, the multiple stator coils 11, and the rotor 20. An air gap of uniform width is provided between the stator 10 and the rotor 20. "Uniform width" does not necessarily mean that the widths of the air gaps between the stator 10 and the rotor 20 are uniform. Even if slight differences within a predetermined range, manufacturing errors, or measurement errors are included, the widths of the air gaps between the stator 10 and the rotor 20 may be considered uniform. Even if slight differences within a predetermined range are included, for example, if the widths of the air gaps between the stator 10 and the rotor 20 are within a range of ±10% of the average width of all the air gaps, the widths of the air gaps between the stator 10 and the rotor 20 may be considered uniform. The stator core holds the multiple stator coils 11. Each stator coil 11 is disposed on the inner periphery of the stator core 20. The stator coils 11 are disposed at equal angular intervals with respect to the rotation axis of the rotor 20.

[0025] The rotating electric machine MT is connected to a control circuit 41. The control circuit 41 is connected to a power source 43. The control circuit 41 adjusts the drive current from the power source 43 and supplies three-phase AC current to each stator coil 11. The control circuit 41 controls the value of the three-phase AC current supplied to each stator coil 11. The control circuit 41 includes, for example, an inverter circuit. When the three-phase AC current is supplied to each stator coil 11, each stator coil 11 forms a rotating magnetic field that rotates the rotor 20. The power source 43 includes, for example, an electrical energy storage device. The power storage device includes, for example, a secondary battery or a capacitor.

[0026] Next, the configuration of the temperature information output device 1 will be described in more detail with reference to Fig. 2. Fig. 2 is a circuit diagram showing an example of a temperature information output device.

[0027] The temperature information output device 1 outputs temperature information related to the temperatures of parts of the rotor 20. For example, the temperature information output device 1 outputs temperature information related to the temperature of the magnet 25. To achieve this function, the temperature information output device 1 includes an element unit 50, an element unit 60, and an output section 80. In this embodiment, there is one element unit 50, and there is also one element unit 60. The element unit 50 is provided on the rotor 20. The element unit 60 is provided on the stator 10. The element unit 60 is provided on, for example, a stator core. For example, when the element unit 50 constitutes a first element unit, the element unit 60 constitutes a second element unit.

[0028] The element unit 50 and the element unit 60 are arranged to face each other in a direction parallel to the rotation axis of the rotor 20 when the rotor 20 is at a predetermined rotation angle position. The "direction parallel to the rotation axis of the rotor 20" does not necessarily mean only a direction parallel to the rotation axis of the rotor 20. Even if slight differences, manufacturing errors, or measurement errors within a preset range are included, the direction may be considered to be parallel to the rotation axis of the rotor 20. If slight differences within a preset range are included, for example, if the angle between the direction and the rotation axis of the rotor 20 is within a range of ±2 degrees, the direction may be considered to be parallel to the rotation axis of the rotor 20.

[0029] As shown in FIG. 2 , the element unit 50 includes a temperature sensor 51, a coil 53, and a capacitor 55. The temperature sensor 51, the coil 53, and the capacitor 55 are provided on the rotor 20. The temperature sensor 51 is provided at a predetermined location on the rotor 20. For example, as shown in FIG. 4 , the temperature sensor 51 is provided on at least one of the magnets 25. In this embodiment, the temperature sensor 51 is provided on only one magnet 25. The temperature sensor 51 is arranged so as to be in contact with the magnet 25. The temperature sensor 51 may be arranged near the magnet 25. For example, a medium having a relatively high thermal conductivity may be arranged between the temperature sensor 51 and the magnet 25. This medium may be, for example, air or a metal member. As a variation of this embodiment, the temperature sensor 51 may be provided on a location on the rotor 20 other than the magnet 25.

[0030] The electrical resistance of the temperature sensor 51 changes in response to the temperature of the rotor 20. For example, a change in the temperature of the magnet 25 indirectly affects the temperature of the rotor 20. Therefore, the electrical resistance of the temperature sensor 51 changes in response to the temperature of the magnet 25. As the temperature of the magnet 25 increases, the electrical resistance of the temperature sensor 51 decreases. When the temperature sensor 51 is provided on the magnet 25, the electrical resistance of the temperature sensor 51 changes more directly in response to a change in the temperature of the magnet 25. The temperature sensor 51 may be, for example, a thermistor or a Hall element. The thermistor may be, for example, an NTC thermistor.

[0031] The coil 53 is electrically connected to the temperature sensitive element 51. In this embodiment, both ends of the coil 53 are electrically connected to both ends of the temperature sensitive element 51.

[0032] The capacitor 55 forms an LC resonant circuit together with the coil 53. The capacitor 55 is inserted so as to be connected in parallel to the coil 53, for example.

[0033] The element unit 60 has a coil 61 and a capacitor 63. The coil 61 is provided on the stator 10 so as to face the coil 53 in the rotational axis direction D of the rotor 20 when the rotor 20 is at a predetermined rotational angle position. The coil 53 and the coil 61 are arranged so as to face each other in the rotational axis direction D of the rotor 20 when the rotor 20 is at the predetermined rotational angle.

[0034] The coil 61 is magnetically coupled to the coil 53. The coil 61 is electrically connected to an AC power supply PS. The AC power supply PS may be, for example, an inverter. An AC signal of a predetermined frequency is applied to the coil 61 from the AC power supply PS. An AC voltage is applied to the coil 61 from the AC power supply PS. The predetermined frequency is higher than the drive frequency of the rotating electric machine MT. The predetermined frequency is, for example, 10 to 2000 times the drive frequency of the rotating electric machine MT.

[0035] Capacitor 63 and coil 61 form an LC resonant circuit. Capacitor 63 may also form an LC resonant circuit with coil 53 and coil 61. Capacitor 63 is inserted, for example, so as to be connected in parallel to coil 61. For example, when coil 53 forms a first coil, coil 61 forms a second coil. The capacitance component of capacitor 55 may be equal to or different from the capacitance component of capacitor 63. For example, the capacitance C1 of capacitor 55 is equal to or greater than half the capacitance C2 of capacitor 63. That is, the condition C1≧0.5×C2 is satisfied.

[0036] A magnetic flux corresponding to the AC voltage applied from the AC power supply PS is generated in the coil 61. When the rotor 20 rotates and the coil 61 and the coil 53 approach each other, the magnetic flux generated in the coil 61 passes through the coil 53. When the magnetic flux generated in the coil 61 passes through the coil 53, power corresponding to the change in the magnetic flux passing through the coil 53 is generated in the coil 53. An induced electromotive force is generated in the coil 53 in response to the change in the magnetic flux passing through the coil 53. In other words, when the rotor 20 rotates and the coil 61 and the coil 53 approach each other, the coils 61 and 53 are magnetically coupled. Alternatively, it can be said that the coil 61 excites the coil 53 and supplies power to the coil 53.

[0037] If the electrical resistance of the temperature sensing element 51 changes in accordance with the temperature of the magnet 25, the magnetic flux generated in the coil 61 changes in accordance with the change in the electrical resistance of the temperature sensing element 51. The current flowing through the coil 61 changes in accordance with the change in the magnetic flux generated in the coil 61.

[0038] When the temperature of magnet 25 rises and the electrical resistance of temperature sensing element 51 decreases, the magnetic flux generated in coil 61 increases, thereby increasing the current flowing through coil 61. When the temperature of magnet 25 falls and the electrical resistance of temperature sensing element 51 increases, the magnetic flux generated in coil 61 decreases, thereby decreasing the current flowing through coil 61.

[0039] The output unit 80 is electrically connected to the element unit 60. The output unit 80 may be electrically connected to the coil 61. The coil 61 is electrically connected to the capacitor 63 and the output unit 80. In this embodiment, the output unit 80 is provided on the stator 10.

[0040] The output unit 80 outputs, as temperature information, an electrical signal related to the phase of the power generated in the coil 61. The output unit 80 includes, for example, a phase detector that detects the phase of the input signal. This phase detector may be, for example, an integrated circuit (IC) or an oscilloscope.

[0041] The output unit 80 outputs, as temperature information, the phase difference between the phase of the voltage applied to the element unit 60 and the phase of the voltage at the output unit 80. For example, the output unit 80 detects the phase difference between the phase of the voltage applied to the coil 61 by the AC power supply PS and the phase of the voltage at the coil 61, and outputs the detected phase difference as temperature information.

[0042] The phase difference detected by the output unit 80 corresponds to a change in the electrical resistance of the temperature sensing element 51, i.e., a change in the temperature of the portion where the temperature sensing element 51 is provided. Therefore, the electrical signal output from the output unit 80 includes temperature information related to the temperature of the portion where the temperature sensing element 51 is provided. The output unit 80 outputs the detected phase difference as an electrical signal indicating the temperature information. As a result, temperature information related to the temperature of the portion where the temperature sensing element 51 is provided is wirelessly transmitted between the element unit 50 and the output unit 80 via the element unit 60. For example, the phase difference detected by the output unit 80 corresponds to a change in the temperature of the magnet 25.

[0043] The phase difference detected by the output unit 80 will be described using FIG. 3. FIG. 3 is a graph showing the frequency dependence of the phase difference for each magnet temperature when the temperature-sensing element 51 is provided on the magnet 25. The vertical axis represents the phase difference output from the output unit 80, and the horizontal axis represents the frequency of the voltage applied by the AC power supply PS. Data D1 to D8 represent the phase difference detected by the output unit 80 at different magnet temperatures. Data D2 represents data when the magnet temperature is higher than data D1. Data D3 represents data when the magnet temperature is higher than data D2. Data D4 represents data when the magnet temperature is higher than data D3. Data D5 represents data when the magnet temperature is higher than data D4. Data D6 represents data when the magnet temperature is higher than data D5. Data D7 represents data when the magnet temperature is higher than data D6. Data D8 represents data when the magnet temperature is higher than data D7. Data D1 represents room temperature.

[0044] Region R1 includes data D1 to D8 at the primary resonance frequency. Region R2 includes data D1 to D8 at the secondary resonance frequency. In regions R1 and R2, data D1 to D8 intersect with each other. The AC power supply PS applies an AC voltage with a frequency between the primary resonance frequency and the secondary resonance frequency at room temperature to the element unit 60. Therefore, the AC power supply PS generates a magnetic flux in the coil 61 with a frequency between the primary resonance frequency and the secondary resonance frequency at room temperature.

[0045] At frequencies between the primary and secondary resonance frequencies at room temperature, the phase difference output from the output unit 80 varies relatively greatly depending on the temperature of the location where the temperature-sensitive element 51 is provided. At frequencies between the primary and secondary resonance frequencies at room temperature, the phase difference output from the output unit 80 increases as the temperature of the location where the temperature-sensitive element 51 is provided increases. The range of frequencies between the primary and secondary resonance frequencies at room temperature includes a relatively stable and wide range in which the phase difference output from the output unit 80 increases as the temperature of the location where the temperature-sensitive element 51 is provided increases. In Figure 3, the phase difference output from the output unit 80 increases as the temperature of the magnet 25 increases.

[0046] The electrical signal output from the output unit 80 is input as the temperature information to the control circuit 41. The control circuit 41 acquires the electrical signal output from the temperature information output device 1, i.e., the electrical signal indicating the phase difference detected by the output unit 80. The control circuit 41 acquires the temperature of the location where the temperature sensing element 51 is provided based on the acquired electrical signal. That is, in this embodiment, the control circuit 41 functions as a temperature acquisition device.

[0047] The control circuit 41 obtains the temperature of the area where the temperature-sensing element 51 is provided, for example, as follows. First, the control circuit 41 refers to data showing the relationship between the temperature and the electrical signal corresponding to the phase difference detected by the output unit 80. The data may be stored in the control circuit 41, or may be stored in an external server different from the control circuit 41. Next, the control circuit 41 obtains the temperature corresponding to the acquired electrical signal from the data as the temperature of the area where the temperature-sensing element 51 is provided. Hereinafter, the temperature of the area where the temperature-sensing element 51 is provided obtained by the control circuit 41 will also be simply referred to as the "obtained temperature."

[0048] The control circuit 41 controls the driving state of the rotating electric machine MT based on the obtained temperature. For example, the control circuit 41 controls the driving state of the rotating electric machine MT as follows: When the control circuit 41 determines that the obtained temperature has risen to a predetermined first threshold, the control circuit 41 controls the supply power to limit the rotation speed of the rotating electric machine MT. When the control circuit 41 determines that the obtained temperature has fallen to a predetermined second threshold that is smaller than the first threshold, the control circuit 41 controls the supply power to release the limit on the rotation speed of the rotating electric machine MT.

[0049] The control circuit 41 may control the drive state of the rotating electric machine MT as follows. That is, the control circuit 41 may control, for example, the drive frequency input to the rotating electric machine MT based on the obtained temperature. When the control circuit 41 determines that the obtained temperature has risen to a predetermined first threshold, the control circuit 41 controls the drive frequency to decrease so as to limit the rotation speed of the rotating electric machine MT. When the control circuit 41 determines that the obtained temperature has fallen to a predetermined second threshold that is smaller than the first threshold, the control circuit 41 controls the drive frequency to increase so as to remove the limit on the rotation speed of the rotating electric machine MT.

[0050] The control circuit 41 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The control circuit 41 obtains the temperature of the portion where the temperature-sensing element 51 is provided and controls the driving state of the rotary electric machine MT, for example, by loading a program stored in the ROM into the RAM and executing the program with the CPU.

[0051] Next, the arrangement of the magnet 25, the temperature sensing element 51, and the coil 53 will be described in more detail with reference to Fig. 4. Fig. 4 is a diagram showing the cross-sectional structure of the rotor core.

[0052] The rotor core 23 includes a pair of end faces 23a, 23b and one side face. The end face 23a is located closer to the element unit 60. That is, the end face 23a is located closer to the coil 61. The end face 23b is located on the opposite side of the end face 23a in the rotational axis direction D. That is, the pair of end faces 23a, 23b are perpendicular to the rotational axis direction D and face in opposite directions. The phrase "the pair of end faces 23a, 23b are perpendicular to the rotational axis direction D" does not necessarily mean that the pair of end faces 23a, 23b are perpendicular to the rotational axis direction D. It is also acceptable to say that the pair of end faces 23a, 23b are perpendicular to the rotational axis direction D even when slight differences, manufacturing errors, or measurement errors within a preset range are included. If there is a slight difference within a predetermined range, for example, if the angle between the pair of end faces 23a, 23b and the rotation axis direction D is within a range of ±1 degree from perpendicular, the pair of end faces 23a, 23b may be considered to be perpendicular to the rotation axis direction D.

[0053] As shown in Fig. 4, the rotor core 23 is configured by stacking a plurality of steel plates M1 in the rotational axis direction D. The rotor core 23 includes a plurality of steel plates M1 stacked in the rotational axis direction D. The steel plates M1 are magnetic. The steel plates M1 may be, for example, silicon steel plates. In this embodiment, of the plurality of steel plates M1, the steel plate M1 located closest to the coil 61 includes an end face 23a as its surface.

[0054] The magnet 25 is disposed in the rotor core 23. In this embodiment, as shown in FIG. 4 , the entire magnet 25 is disposed within the rotor core 23. The magnet 25 has a pair of faces 25a, 25b and four side faces. The face 25a is located closer to the coil 61. The face 25b is located on the opposite side of the face 25a in the rotational axis direction D. That is, the pair of faces 25a, 25b are perpendicular to the rotational axis direction D and face in opposite directions. The phrase "the pair of faces 25a, 25b are perpendicular to the rotational axis direction D" does not necessarily mean that the pair of faces 25a, 25b are perpendicular to the rotational axis direction D. It is also acceptable to consider the pair of faces 25a, 25b to be perpendicular to the rotational axis direction D even when slight differences, manufacturing errors, or measurement errors within a predetermined range are included. If there is a slight difference within a predetermined range, for example, if the angle between the pair of surfaces 25a, 25b and the rotation axis direction D is within a range of ±2 degrees from perpendicular, the pair of surfaces 25a, 25b may be considered to be perpendicular to the rotation axis direction D.

[0055] In this embodiment, the temperature sensing element 51 is arranged so as to be in contact with the magnet 25. The temperature sensing element 51 is arranged on the surface 25a of the magnet 25. In this embodiment, the temperature sensing element 51 is arranged so as to be in contact with the surface 25a of the magnet 25. In this embodiment, the temperature sensing element 51, like the magnet 25, is also arranged entirely within the rotor core 23.

[0056] The coil 53 is also disposed within the rotor core 23, similar to the magnet 25. In this embodiment, at least a portion of the coil 53 is disposed within the rotor core 23. The coil 53 is disposed within the rotor core 23, closer to the end face 23a than the magnet 25. One end 53a of the coil 53 in the rotation axis direction D is exposed from the rotor core 23. The one end 53a is exposed at the end face 23a of the rotor core 23. In this embodiment, only the one end 53a of the coil 53 is exposed from the rotor core 23, and the rest of the coil 53 is embedded in the rotor core 23. As shown in FIG. 4 , in this embodiment, the end face 23a is flush with the one end 53a of the coil 53. "End surface 23a is flush with one end 53a" includes not only that end surface 23a is flush with one end 53a, but also that there is a step between end surface 23a and one end 53a, the step being, for example, 1% or less of the length in the rotational axis direction D of rotor 20. It is sufficient that at least a portion of coil 53 is disposed within rotor core 23, and a portion other than one end 53a may be exposed from rotor core 23. In this case, for example, a portion of the side of coil 53 that is located closer to one end 53a may be exposed from rotor core 23, and end surface 23a does not have to be flush with one end 53a.

[0057] Next, the configuration of a modified example of the rotary electric machine MT will be described with reference to Fig. 5. Fig. 5 is a diagram showing the cross-sectional configuration of the rotor core. This modified example differs from the above-described embodiment in the configuration of the rotor core 23 and the arrangement of the coils 53. The following mainly describes the differences between the above-described embodiment and this modified example.

[0058] In this modification, as shown in FIG. 5 , the rotor core 23 further includes a plate M2 in addition to the multiple steel plates M1. The plate M2 is electrically conductive. The plate M2 may be made of, for example, stainless steel or aluminum. The plate M2 is disposed on the steel plate M1 that is located outermost in the rotation axis direction D and closer to the coil 61 when the rotor 20 is at a predetermined rotation angle. In this modification, the plate M2 includes an end surface 23a as its surface. In this modification, the temperature sensor 51 and the coil 53 are embedded in the plate M2. One end 53a of the coil 53 is exposed at the end surface 23a included in the plate M2. Even in this modification in which the end surface 23a is included in the plate M2, the end surface 23a is flush with the one end 53a of the coil 53. In this modified example, for example, the portion of the side of the coil 53 that is located closer to one end 53a may be exposed from the rotor core 23, and the end surface 23a of the plate M2 may not be flush with the one end 53a.

[0059] Next, the configuration of another modified example of the rotary electric machine MT will be described with reference to Fig. 6. Fig. 6 is a diagram showing the cross-sectional configuration of the rotor core. This modified example also differs from the above-described embodiment in the configuration of the rotor core 23 and the arrangement of the coils 53. Below, the differences between the above-described embodiment and this modified example will be mainly described.

[0060] In this modification, as shown in FIG. 6 , the rotor core 23 further includes, in addition to the plurality of steel plates M1, a plate M2a and a plate M3 separate from the plate M2a. The plate M2a is not electrically conductive, while the plate M3 is electrically conductive. The plate M2a is disposed on the steel plate M1 that is located outermost in the rotation axis direction D and closest to the coil 61 among the plurality of steel plates M1. The plate M3 is disposed on the plate M2a. Therefore, in this modification, the plate M3 is also disposed on the steel plate M1 that is located outermost in the rotation axis direction D and closest to the coil 61 among the plurality of steel plates M1. In this modification, the plate M3 includes an end face 23a as its surface. In this modification, the temperature sensor 51 is embedded in the plate M2a, and the coil 53 is embedded in the plate M3.

[0061] One end 53a of the coil 53 is exposed at the end surface 23a included in the plate M3. Even in this modified example in which the end surface 23a is included in the plate M3, the end surface 23a is flush with the one end 53a of the coil 53. Even in this modified example, for example, a portion of the side of the coil 53 that is located closer to the one end 53a may be exposed from the rotor core 23, and the end surface 23a included in the plate M3 may not be flush with the one end 53a.

[0062] Next, a temperature information output device 1A according to a modification of this embodiment will be described with reference to FIG. 7. FIG. 7 is a circuit diagram showing an example of a temperature information output device according to a modification of this embodiment. This modification is generally similar to or the same as the embodiment described above. This modification differs from the embodiment described above in that an electrical resistance element is provided. The following mainly describes the differences between the embodiment and the modification described above.

[0063] The temperature information output device 1A includes an element unit 50, an element unit 60, an electric resistance element 70, and an output unit 80. The electric resistance element 70 is electrically connected to the element unit 60. The electric resistance element 70 may be electrically connected to the coil 61. In this modification, the electric resistance element 70 is provided on the stator 10 and inserted between the coil 61 and the AC power supply PS. The electric resistance element 70 is inserted between the capacitor 63 and the AC power supply PS.

[0064] In this modification, the output section 80 is electrically connected to the element unit 60 and the electrical resistance element 70. The output section 80 is electrically connected to the coil 61. That is, the coil 61 is electrically connected to the electrical resistance element 70 and the output section 80.

[0065] Next, the effects of the temperature information output device 1, 1A, circuitry, and temperature acquisition device described above will be described. Figure 8 is a graph showing the frequency dependence of voltage for each magnet temperature. The vertical axis represents the voltage detected by the output unit 80, and the horizontal axis represents the frequency of the voltage applied by the AC power supply PS.

[0066] In FIG. 8, data D11 to D18 represent voltages detected at mutually different magnet temperatures. Data D11 to D18 represent voltages output from a voltmeter when the voltmeter is placed in the same position as output unit 80 in place of output unit 80 in temperature information output device 1A. Data D12 represents a case where the magnet temperature is higher than data D11. Data D13 represents data where the magnet temperature is higher than data D12. Data D14 represents data where the magnet temperature is higher than data D13. Data D15 represents data where the magnet temperature is higher than data D14. Data D16 represents data where the magnet temperature is higher than data D15. Data D17 represents data where the magnet temperature is higher than data D16. Data D18 represents data where the magnet temperature is higher than data D17. Data D11 is at room temperature.

[0067] 3 show stable values ​​over a wider frequency range than data D11 to D18. Therefore, it was confirmed that the effect of frequency deviation is less pronounced when the phase difference output from output unit 80 is read as temperature information than when the voltage from the voltmeter is read as temperature information.

[0068] Fig. 9 is a graph showing the temperature dependency of the voltage detected by the above-mentioned voltmeter. The vertical axis shows the voltage detected by the output unit 80, and the horizontal axis shows the temperature of the magnet 25. Fig. 10 is a graph showing the temperature dependency of the phase detected by the output unit 80. The vertical axis shows the phase difference output from the output unit 80, and the horizontal axis shows the temperature of the magnet 25. Figs. 9 and 10 show variations in the detected value depending on the coil characteristics, capacitor characteristics, and inter-coil coupling coefficient depending on the mounting position of the element unit.

[0069] Data D21 and D31 are simulations in which the characteristics of the coils 53 and 61, the characteristics of the capacitors 55 and 63, and the inter-coil coupling coefficient corresponding to the mounting positions of the element unit 50 and the element unit 60 are ideal values. Data D22 and D32 are simulations in which the inductance of the coils 53 and 61 is −5% of the ideal value. Data D23 and D33 are simulations in which the inductance of the coils 53 and 61 is +5% of the ideal value. Data D24 and D34 are simulations in which the capacitance of the capacitor 55 is +5% of the ideal value. Data D25 and D35 are simulations in which the capacitance of the capacitor 55 is −5% of the ideal value. Data D26 and D36 are simulations in which the capacitance of the capacitor 63 is +5% of the ideal value. Data D27 and D37 are simulations in which the capacitance of the capacitor 63 is −5% of the ideal value. Data D28 and D38 are simulations in which the inter-coil coupling coefficient is +5% of the ideal value. Data D29 and D39 are simulation results when the inter-coil coupling coefficient is −5% of the ideal value.

[0070] 10 shows smaller variations in the detected values ​​depending on the coil characteristics, capacitor characteristics, and inter-coil coupling coefficient depending on the mounting position of the element unit than data D41 and D42. Therefore, it was confirmed that the case where the phase difference output from output unit 80 is read as temperature information is less susceptible to the influence of deviations in the coil characteristics, capacitor characteristics, and inter-coil coupling coefficient depending on the mounting position of the element unit than the case where the voltage from the above-mentioned voltmeter is read as temperature information.

[0071] In the temperature information output device 1, the output section 80 outputs the phase difference between the phase of the voltage applied to the element unit 60 and the phase of the voltage at the output section 80 as temperature information. That is, temperature information relating to the temperature of a portion of the rotor 20 is output from the output section 80 as a phase difference. In this case, the accuracy of the temperature information relating to the temperature of the portion of the rotor 20 can be ensured. If the temperature-sensing element 51 is provided in the magnet 25, the accuracy of the temperature information relating to the temperature of the magnet 25 can be ensured. The temperature information output device 1A has a similar configuration and achieves similar effects.

[0072] In the temperature information output device 1, the capacitance of the capacitor 55 may be half or more of the capacitance of the capacitor 63. In this case, the accuracy of the temperature information regarding the temperatures of the parts of the rotor 20 can be further improved. If the temperature sensor 51 is provided on the magnet 25, the accuracy of the temperature information regarding the temperature of the magnet 25 can be further improved. The temperature information output device 1A has a similar configuration and achieves the same effects.

[0073] When the condition that the capacitance of capacitor 55 is at least half the capacitance of capacitor 63 is satisfied, the phase detection in the output section 80 is less affected by the arrangement of element units 50 and 60 and the variations in the characteristics of each component such as coils 53 and 61 and capacitors 55 and 63, and there is also little variation in sensing accuracy across the entire temperature range.

[0074] The temperature information output device 1A further includes an electric resistance element 70 electrically connected to the element unit 60. In this case, the accuracy of the temperature information relating to the temperature of the portion of the rotor 20 can be further improved. If the temperature-sensing element 51 is provided in the magnet 25, the accuracy of the temperature information relating to the temperature of the magnet 25 can be further improved.

[0075] The rotating electric machine MT is provided with the above-described temperature information output device 1, 1A. In this case, temperature information relating to the temperatures of parts of the rotor 20 is output as an electric signal relating to the phase difference.

[0076] The control circuit 41 includes the temperature information output device 1, 1A described above, acquires the electrical signal output from the temperature information output device 1, 1A, and obtains the temperature of the part of the rotor 20 based on the acquired electrical signal. In this case, the temperature of the part of the rotor 20 is obtained based on the electrical signal related to the phase difference.

[0077] While the embodiments of the present disclosure have been described above, the present invention is not necessarily limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention. In the rotating electric machine MT, the coils 53 and 61 do not have to be arranged so as to face each other in the direction of the rotation axis D when the rotor 20 is at a predetermined rotation angle position.

[0078] In a rotating electric machine MT in which coils 53 and 61 are arranged so as to face each other in the direction of the rotation axis D when the rotor 20 is at a predetermined rotation angle position, as described above, the magnetic flux generated in the stator coil 11 is unlikely to affect coils 53 and 61.

[0079] In the rotating electric machine MT, the temperature sensing element 51 does not have to be arranged so as to be in contact with the surface 25a of the magnet 25. The entire magnet 25 and a part of the coil 53 do not have to be arranged inside the rotor core 23.

[0080] The control circuit 41 does not have to function as a temperature acquisition device. The control circuit 41 may control the drive state of the rotating electric machine MT based on the electrical signal input from the output unit 80. In this case, the control circuit 41 may control the drive state of the rotating electric machine MT as follows. When the electrical signal input from the output unit 80 determines that the temperature of the temperature sensing element 51 has risen to a predetermined first threshold, the control circuit 41 controls the drive frequency to decrease so as to limit the rotation speed of the rotating electric machine MT. When the electrical signal input from the output unit 80 determines that the temperature of the temperature sensing element 51 has fallen to a predetermined second threshold that is lower than the first threshold, the control circuit 41 controls the drive frequency to increase so as to remove the limit on the rotation speed of the rotating electric machine MT.

[0081] In the above-described embodiment and modified examples, the magnet 25 is a permanent magnet, but the magnet 25 may be an electromagnet. For example, a wound-field motor may be adopted instead of a motor using a permanent magnet. A wound-field motor has windings that generate a magnetic field when a current is passed through them instead of permanent magnets. The windings are field coils. A wound-field motor includes, for example, multiple field coils provided on a stator.

[0082] As can be seen from the above-described embodiments and modifications, this specification discloses the following aspects. (Supplementary Note 1) A temperature information output device provided in a rotating electric machine having a stator and a rotor, and outputting temperature information related to the temperature of a portion of the rotor, comprising: a first element unit provided on the rotor, the first element unit having a temperature sensor whose electrical resistance changes in response to the temperature of the portion, a first coil electrically connected to the temperature sensor, and a first capacitor forming an LC resonant circuit together with the first coil; a second element unit provided on the stator, the second element unit having a second coil magnetically coupled to the first coil and a second capacitor forming an LC resonant circuit together with the second coil; and an output unit electrically connected to the second element unit, the output unit outputting a phase difference between a phase of a voltage applied to the second element unit and a phase of a voltage in the second element unit as the temperature information. (Supplementary Note 2) The temperature information output device according to Supplementary Note 1, wherein the capacitance of the first capacitor is equal to or greater than half the capacitance of the second capacitor. (Supplementary Note 3) The temperature information output device according to Supplementary Note 1 or 2, further comprising an electric resistance element electrically connected to the second element unit. (Supplementary Note 4) The temperature information output device according to any one of Supplements 1 to 3, wherein the part is a magnet. (Supplementary Note 5) A rotating electric machine provided with the temperature information output device according to any one of Supplements 1 to 4. (Supplementary Note 6) A temperature acquisition device including the temperature information output device according to any one of Supplements 1 to 4, acquiring the temperature information output from the temperature information output device, and obtaining the temperature of the magnet based on the acquired temperature information.

[0083] 1, 1A...temperature information output device, 10...stator, 20...rotor, 25...magnet, 41...control circuit, 51...thermo-sensing element, 70...electrical resistance element, 80...output section, C1, C2...electrostatic capacitance, MT...rotating electric machine

Claims

1. A temperature information output device that is provided in a rotating electric machine having a stator and a rotor and outputs temperature information related to the temperature of a portion of the rotor, comprising: a first element unit provided on the rotor, the first element unit having a temperature sensor whose electrical resistance changes depending on the temperature of the portion, a first coil electrically connected to the temperature sensor, and a first capacitor that forms an LC resonance circuit together with the first coil; a second element unit provided on the stator, the second element unit having a second coil magnetically coupled to the first coil and a second capacitor that forms an LC resonance circuit together with the second coil; and an output unit electrically connected to the second element unit, wherein the output unit outputs the phase difference between the phase of the voltage applied to the second element unit and the phase of the voltage in the second element unit as the temperature information.

2. The temperature information output device according to claim 1, wherein the capacitance of the first capacitor is at least half the capacitance of the second capacitor.

3. The temperature information output device according to claim 1, further comprising an electric resistance element electrically connected to the second element unit.

4. The temperature information output device according to claim 1, wherein the part is a magnet provided on the rotor.

5. A rotating electrical machine provided with a temperature information output device according to any one of claims 1 to 4.

6. A temperature acquisition device including the temperature information output device according to claim 1, which acquires the temperature information output from the temperature information output device and obtains the temperature of the part based on the acquired temperature information.

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