Magnet temperature information output device and rotating motor

Abstract

The present invention relates to a magnet temperature information output device and a rotating electric machine. The magnet temperature information output device is arranged on a rotating electric machine having a stator and a rotor equipped with a permanent magnet. The magnet temperature information output device outputs temperature information related to the temperature of the permanent magnet. The magnet temperature information output device includes an element arranged on the stator. The element detects magnetic flux and outputs an electrical signal corresponding to the detected magnetic flux as temperature information.

Description

Technical Field

[0001] One embodiment of the present invention relates to a magnet temperature information output device. Another embodiment of the present invention relates to a rotating electrical machine including the magnet temperature information output device. Background Art

[0002] A known rotating electrical machine includes a stator and a rotor on which permanent magnets are arranged (for example, see Japanese Patent Application Laid-Open No. 2000-134842).

[0003] Generally speaking, when a rotating electrical machine is driven, the temperature of the permanent magnets rises. If a change in the magnetic field is applied to the permanent magnets while they are at a specified temperature or above, the permanent magnets may become demagnetized. Because the permanent magnets are located in the rotor, accurate temperature information related to the permanent magnets is difficult to obtain. Therefore, when designing rotating electrical machines, it is assumed that the permanent magnets will reach temperatures exceeding the specified temperature, and magnets with higher heat resistance than specified are sometimes selected.

[0004] In contrast, a configuration is being considered that acquires temperature information related to the temperature of the permanent magnets and controls the driving state of the rotating electrical machine so that the permanent magnets do not reach the predetermined temperature. The permanent magnets are disposed on the rotor. Therefore, even in a configuration where a temperature sensor for detecting the temperature of the permanent magnets is disposed on the rotor, it is difficult to appropriately and easily output temperature information related to the temperature of the permanent magnets. Summary of the Invention

[0005] One embodiment of the present invention is to provide a magnet temperature information output device that appropriately and simply outputs temperature information related to the temperature of permanent magnets disposed on a rotor. Another embodiment of the present invention is to provide a rotating electrical machine that appropriately and simply outputs temperature information related to the temperature of permanent magnets disposed on a rotor.

[0006] A magnet temperature information output device according to one embodiment is disposed on a rotating electrical machine including a stator and a rotor equipped with permanent magnets, and outputs temperature information related to the temperature of the permanent magnets. The magnet temperature information output device includes an element that detects magnetic flux and outputs an electrical signal corresponding to the detected magnetic flux as temperature information. The element is disposed on the stator.

[0007] In the above embodiment, the element arranged in the stator detects magnetic flux and outputs an electrical signal corresponding to the detected magnetic flux as temperature information. Therefore, in the above embodiment, temperature information related to the temperature of the permanent magnet arranged in the rotor can be output appropriately and easily.

[0008] A rotating electrical machine according to another embodiment includes the magnet temperature information output device described above.

[0009] In the above-mentioned another embodiment, the element arranged in the stator detects magnetic flux and outputs an electrical signal corresponding to the detected magnetic flux as temperature information. Therefore, the above-mentioned another embodiment can appropriately and easily output temperature information related to the temperature of the permanent magnet arranged in the rotor.

[0010] The magnet temperature information output device may also include a temperature sensing element disposed on the rotor and a first coil disposed on the rotor. In this case, the resistance of the temperature sensing element changes according to the temperature of the permanent magnet, and the first coil is electrically connected to the temperature sensing element. The element may also include a second coil and a current detection element. In this case, the second coil excites the first coil, and the current detection element outputs an electrical signal corresponding to the magnitude of the current flowing through the second coil.

[0011] The first coil is excited by the second coil, supplying power to the first coil. The resistance of the temperature-sensing element electrically connected to the first coil changes according to the temperature of the permanent magnet. Consequently, the current flowing through the second coil changes in accordance with the change in resistance of the temperature-sensing element. The current detection element outputs an electrical signal corresponding to the magnitude of the current flowing through the second coil. Therefore, the electrical signal output from the current detection element changes according to the temperature of the permanent magnet. As a result, even with a configuration where the temperature-sensing element is located within the rotor, the element can more appropriately and simply output temperature information related to the temperature of the permanent magnet.

[0012] The magnet temperature information output device may include a capacitor that forms an LC resonance circuit with the first coil. In this case, the capacitor is disposed on the rotor.

[0013] The element may include a magnetic induction element that detects the magnetic flux of the permanent magnet. When the element includes the magnetic induction element, a magnet temperature information output device that appropriately and simply outputs temperature information related to the temperature of the permanent magnet can be easily constructed.

[0014] The present invention will become more apparent from the following detailed description and accompanying drawings, which are for illustrative purposes only and therefore should not be considered as limiting the present invention.

[0015] Further applicability of the present invention will become apparent from the detailed description provided below. However, it should be understood that the detailed description and specific examples describing the embodiments of the present invention are intended to be illustrative only, and that various changes and modifications within the spirit and scope of the present invention will be readily apparent to those skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram showing the structure of a magnet temperature information output device according to one embodiment.

[0017] Figure 2This is a circuit diagram showing an example of a magnet temperature information output device.

[0018] Figure 3 It is a schematic diagram showing the structure of a magnet temperature information output device according to a modification of the present embodiment.

[0019] Figure 4 This is a circuit diagram showing another example of the magnet temperature information output device. DETAILED DESCRIPTION

[0020] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same elements or elements having the same functions are denoted by the same reference numerals, and repeated descriptions are omitted.

[0021] Reference Figure 1 and Figure 2 The configuration of the magnet temperature information output device 1A according to this embodiment will be described. Figure 1 This is a schematic diagram showing the structure of the magnet temperature information output device according to this embodiment. Figure 2 This is a circuit diagram showing an example of a magnet temperature information output device.

[0022] like Figure 1 As shown, the magnet temperature information output device 1A is disposed in the rotating electrical machine MT. Specifically, the rotating electrical machine MT includes the magnet temperature information output device 1A. The rotating electrical machine MT is, for example, a motor. Examples of motors include IPM motors and SPM motors. The rotating electrical machine MT includes a stator 10 and a rotor 20. The rotor 20 is disposed inside the stator 10.

[0023] The rotor 20 includes a shaft 21, a rotor core 23, and a plurality of permanent magnets 25. The shaft 21 is cylindrical. The rotor core 23 is cylindrical. The rotor core 23 is formed with an axial hole into which the shaft 21 is inserted. The shaft 21 and the rotor core 23 rotate integrally around the central axis of the shaft 21. Each permanent magnet 25 is arranged on the rotor core 23 so that its extension direction is parallel to the central axis of the shaft 21. The extension direction of each permanent magnet 25 is approximately parallel to the central axis of the shaft 21. 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 direction of the rotation axis of the rotor 20. The plurality of permanent magnets 25 are arranged at equal angular intervals with respect to the rotation axis of the rotor 20.

[0024] When the rotating electrical machine MT is an IPM motor, multiple permanent magnets 25 are arranged within the rotor core 23. When the rotating electrical machine MT is an SPM motor, multiple permanent magnets 25 are arranged on the surface of the rotor core 23. Each permanent magnet 25 comprises a rare-earth permanent magnet. Each permanent magnet 25 is, for example, a neodymium-based sintered magnet. Each permanent magnet 25 may also be a sintered magnet other than a rare-earth permanent magnet, or a magnet other than a sintered magnet. Examples of magnets other than a sintered magnet include bonded magnets and hot-worked magnets.

[0025] Stator 10 includes a cylindrical stator core (not shown) and multiple coils 11. The stator core is arranged to surround the outer circumference of rotor 20. An air gap of uniform width is provided between stator 10 and rotor 20. The stator core holds multiple coils 11. Each coil 11 is arranged on the inner circumference of the stator core. Multiple coils 11 are arranged at equal angular intervals about the rotation axis of rotor 20.

[0026] The rotating electrical machine MT is connected to a control circuit 41. The control circuit 41 is connected to a power supply 43. The control circuit 41 adjusts the drive current from the power supply 43 and supplies three-phase AC current to each coil 11. The control circuit 41 controls the value of the three-phase AC current supplied to each coil 11. The control circuit 41 includes, for example, an inverter circuit. By supplying three-phase AC current to each coil 11, each coil 11 forms a rotating magnetic field that rotates the rotor 20. The power supply 43 includes, for example, an electrical energy storage device. The electrical energy storage device includes, for example, a secondary battery or a capacitor.

[0027] The magnet temperature information output device 1A includes a first element 50 and a second element 60. In this embodiment, there is one first element 50 and one second element 60. The first element 50 is disposed on the rotor 20. The second element 60 is disposed on the stator 10. The second element 60 is disposed, for example, on the stator core. The magnet temperature information output device 1A outputs temperature information related to the temperature of the permanent magnets 25. The first element 50 and the second element 60 are disposed so as to face each other in a direction substantially parallel to the rotation axis of the rotor 20 when the rotor 20 is at a predetermined rotational angle position.

[0028] like Figure 2As shown, the first element 50 includes a temperature sensing element 51 and a coil 53. The temperature sensing element 51 and the coil 53 are arranged on the rotor 20. The temperature sensing element 51 is arranged on at least one permanent magnet 25 among the multiple permanent magnets 25. In this embodiment, the temperature sensing element 51 is arranged only on one permanent magnet 25. The temperature sensing element 51 is arranged in contact with the permanent magnet 25. The temperature sensing element 51 can also be arranged near the permanent magnet 25. The resistance of the temperature sensing element 51 changes according to the temperature of the permanent magnet 25. The resistance of the temperature sensing element 51 decreases as the temperature of the permanent magnet 25 rises. The temperature sensing element 51 includes, for example, a thermistor. The temperature sensing element 51 includes, for example, an NTC thermistor. The coil 53 is electrically connected to the temperature sensing element 51. Both ends of the coil 53 are electrically connected to both ends of the temperature sensing element 51.

[0029] The second element 60 includes a coil 61 and a current detection element 63. The coil 61 is arranged on the stator 10 (stator core) so as to face the coil 53 when the rotor 20 is at a predetermined rotational angle position. The AC power supply 65 is electrically connected to the coil 61. An AC signal (AC voltage) of a predetermined frequency is applied to the coil 61 from the AC power supply 65. The current detection element 63 outputs an electrical signal corresponding to the magnitude of the current flowing through the coil 61. The current detection element 63 includes, for example, an AC current sensor. For example, when the coil 53 constitutes the first coil, the coil 61 constitutes the second coil. The above-mentioned predetermined frequency is higher than the driving frequency of the rotating motor MT. The above-mentioned predetermined frequency is, for example, 10 to 200 times the driving frequency of the rotating motor MT.

[0030] Coil 61 generates magnetic flux corresponding to the AC voltage applied from AC power supply 65. When rotor 20 rotates and coil 61 approaches coil 53, the magnetic flux generated by coil 61 passes through coil 53. When the magnetic flux generated by coil 61 passes through coil 53, electric power corresponding to the magnetic flux passing through coil 53 is generated in coil 53. In other words, coil 61 excites coil 53, supplying electric power to coil 53.

[0031] The resistance of the temperature sensing element 51 changes depending on the temperature of the permanent magnet 25. As the resistance of the temperature sensing element 51 changes, the magnetic flux generated in the coil 61 changes. Consequently, the current flowing through the coil 61 changes. When the temperature of the permanent magnet 25 rises and the resistance of the temperature sensing element 51 decreases, the magnetic flux generated in the coil 61 increases. Consequently, the current flowing through the coil 61 increases. When the temperature of the permanent magnet 25 drops and the resistance of the temperature sensing element 51 increases, the magnetic flux generated in the coil 61 decreases. Consequently, the current flowing through the coil 61 decreases.

[0032] The current detection element 63 detects the magnetic flux generated by the coil 61 as a change in the current flowing through the coil 61. That is, the current detection element 63 indirectly detects the magnetic flux generated by the coil 61. The change in current detected by the current detection element 63 corresponds to the change in the resistance of the temperature sensing element 51, that is, the change in the temperature of the permanent magnet 25. Therefore, the electrical signal output from the current detection element 63, that is, the output signal of the current detection element 63, contains temperature information related to the temperature of the permanent magnet. The second element 60 indirectly detects the generated magnetic flux and outputs the electrical signal corresponding to the indirectly detected magnetic flux as the aforementioned temperature information. As a result, information related to the temperature of the permanent magnet 25 is wirelessly transmitted between the first element 50 and the second element 60.

[0033] The electrical signal output from the current detection element 63 is input to the control circuit 41. The control circuit 41 controls the driving state of the rotating electrical machine MT based on the electrical signal output from the current detection element 63. For example, the control circuit 41 controls the driving state of the rotating electrical machine MT as follows. If the control circuit 41 determines that the electrical signal output from the current detection element 63 indicates that the temperature of the permanent magnet 25 has risen to a predetermined first threshold value, the control circuit 41 controls the power supply to limit the rotational speed of the rotating electrical machine MT. If the control circuit 41 determines that the electrical signal output from the current detection element 63 indicates that the temperature of the permanent magnet 25 has fallen to a predetermined second threshold value, the control circuit 41 controls the power supply to remove the restriction on the rotational speed of the rotating electrical machine MT. In this case, the second threshold value is, for example, lower than the first threshold value.

[0034] The control circuit 41 may also control the driving state of the rotating electrical machine MT as described below. Specifically, the control circuit 41 may control the driving frequency input to the rotating electrical machine MT, for example. If the control circuit 41 determines that the electrical signal output from the current detection element 63 indicates that the temperature of the permanent magnet 25 has risen to a predetermined first threshold value, the control circuit 41 reduces the driving frequency to limit the rotational speed of the rotating electrical machine MT. If the control circuit 41 determines that the electrical signal output from the current detection element 63 indicates that the temperature of the permanent magnet 25 has fallen to a predetermined second threshold value, the control circuit 41 increases the driving frequency to remove the restriction on the rotational speed of the rotating electrical machine MT. In this case, the second threshold value is, for example, lower than the first threshold value.

[0035] As described above, in magnet temperature information output device 1A, second element 60 disposed in stator 10 detects magnetic flux and outputs an electrical signal corresponding to the detected magnetic flux as temperature information. Therefore, magnet temperature information output device 1A can appropriately and easily output temperature information related to the temperature of permanent magnets 25 disposed in rotor 20.

[0036] The rotating electrical machine MT includes the magnet temperature information output device 1A. Therefore, the rotating electrical machine MT appropriately and easily outputs temperature information related to the temperature of the permanent magnets arranged in the rotor.

[0037] The magnet temperature information output device 1A includes a first element 50 including a temperature sensing element 51 and a coil 53 . The second element 60 includes a coil 61 and a current detection element 63 .

[0038] Coil 53 is excited by coil 61, supplying power to coil 53. The resistance of temperature sensing element 51 changes according to the temperature of permanent magnet 25. Therefore, the current flowing through coil 61 changes according to the change in resistance of temperature sensing element 51. Current detection element 63 outputs an electrical signal corresponding to the magnitude of the current flowing through coil 61. Therefore, the electrical signal output from current detection element 63 changes according to the temperature of permanent magnet 25. As a result, even with a configuration in which temperature sensing element 51 is located within rotor 20, second element 60 can more appropriately and simply output temperature information related to the temperature of permanent magnet 25.

[0039] The first element 50 and the second element 60 are arranged to face each other in a direction substantially parallel to the rotation axis of the rotor 20 when the rotor 20 is at a predetermined rotation angle position. In this case, the magnetic flux generated in the coil 11 is less likely to affect the coils 53 and 61.

[0040] like Figure 4 As shown, the first element 50 may also include a capacitor 55 . Figure 4 This is a circuit diagram showing another example of a magnet temperature information output device. Capacitor 55 is located on rotor 20. Coil 53 and capacitor 55 form an LC resonant circuit. Capacitor 55 is connected in parallel with coil 53, for example. The inclusion of capacitor 55 in first element 50 allows for even greater sensitivity in detecting changes in temperature sensing element 51.

[0041] The following configuration is considered as a structure for acquiring the output signal of the temperature sensing element 51 disposed on the rotor 20. A transmitter for transmitting the output signal of the temperature sensing element 51 is disposed on the rotor 20, and a receiver for receiving the signal from the transmitter is disposed on the stator 10. This configuration requires the transmitter to be disposed on the rotor 20, hindering the miniaturization of the rotating electrical machine MT. Furthermore, a power supply path must be constructed to the transmitter, complicating the structure of the rotating electrical machine MT.

[0042] In contrast, the magnet temperature information output device 1A is unlikely to hinder the miniaturization of the rotating electrical machine MT and is unlikely to complicate the structure of the rotating electrical machine MT.

[0043] Next, refer to Figure 3The configuration of a magnet temperature information output device 1B according to a modified example of the present embodiment will be described. Figure 3 This is a schematic diagram showing the structure of the magnet temperature information output device according to this modification.

[0044] like Figure 3 As shown, the magnet temperature information output device 1B is configured in the rotating electrical machine MT. Specifically, the rotating electrical machine MT includes the magnet temperature information output device 1B. The magnet temperature information output device 1B includes an element 70. In this modification, there is only one element 70. The element 70 is configured in the stator 10. For example, the element 70 is configured in the stator core. Similar to the magnet temperature information output device 1A, the magnet temperature information output device 1B outputs temperature information related to the temperature of the permanent magnets 25.

[0045] Element 70 includes a magnetic sensing element that detects the magnetic flux of permanent magnet 25. Element 70 is positioned on stator 10 (stator core) so that it is closest to permanent magnet 25 when rotor 20 is at a predetermined rotational angle position. Alternatively, element 70 may be positioned on stator 10 (stator core) so that it faces permanent magnet 25 when rotor 20 is at a predetermined rotational angle position. Element 70 and permanent magnet 25 are positioned so that they face each other in a direction substantially parallel to the rotation axis of rotor 20 when rotor 20 is at a predetermined rotational angle position. Element 70 includes, for example, a Hall effect element or a magnetoresistive element.

[0046] Element 70 directly detects the magnetic flux of permanent magnet 25. As the temperature of permanent magnet 25 increases, the magnetic flux generated by permanent magnet 25 decreases. Changes in the magnetic flux of permanent magnet 25 detected by element 70 correspond to changes in the temperature of permanent magnet 25. Therefore, the electrical signal output from element 70, i.e., the output signal of element 70, contains temperature information related to the temperature of the permanent magnet. Element 70 directly detects the magnetic flux generated by permanent magnet 25 and outputs the electrical signal corresponding to the directly detected magnetic flux as the aforementioned temperature information.

[0047] The electrical signal output from the element 70 is input to the control circuit 41. The control circuit 41 controls the driving state of the rotating electrical machine MT based on the electrical signal output from the element 70. For example, the control circuit 41 controls the driving state of the rotating electrical machine MT as follows. If the control circuit 41 determines that the electrical signal output from the element 70 indicates that the temperature of the permanent magnet 25 has risen to a predetermined first threshold value, the control circuit 41 controls the power supply to limit the rotational speed of the rotating electrical machine MT. If the control circuit 41 determines that the electrical signal output from the element 70 indicates that the temperature of the permanent magnet 25 has fallen to a predetermined second threshold value, the control circuit 41 controls the power supply to remove the restriction on the rotational speed of the rotating electrical machine MT.

[0048] As described above, in the magnet temperature information output device 1B, the element 70 disposed on the stator 10 detects magnetic flux and outputs an electrical signal corresponding to the detected magnetic flux as temperature information. Therefore, the magnet temperature information output device 1B appropriately and easily outputs temperature information related to the temperature of the permanent magnet 25.

[0049] Since the element 70 is a magnetic induction element, the magnet temperature information output device 1B that outputs temperature information appropriately and simply can be easily configured.

[0050] The magnet temperature information output device 1B is also similar to the magnet temperature information output device 1A in that it is unlikely to hinder the miniaturization of the rotating electrical machine MT and it is unlikely to complicate the structure of the rotating electrical machine MT.

[0051] The rotating electrical machine MT includes the magnet temperature information output device 1B. Therefore, the rotating electrical machine MT appropriately and easily outputs temperature information related to the temperature of the permanent magnets arranged in the rotor.

[0052] Although the embodiment and the modified examples of the present invention have been described above, the present invention is not limited to the embodiment and the modified examples, and various changes can be made to the embodiment without departing from the gist of the present invention.

[0053] There may be a plurality of first elements 50. For example, the number of first elements 50 may be the same as the number of permanent magnets 25. In this case, there may be only one second element 60.

[0054] The number of the elements 70 may be plural. For example, the number of the elements 70 may be the same as the number of the permanent magnets 25.

Claims

1. A device for outputting magnet temperature information, wherein: The magnet temperature information output device is a magnet temperature information output device that is disposed in a rotating electrical machine having a stator and a rotor having permanent magnets disposed thereon and outputs temperature information related to the temperature of the permanent magnets. The magnet temperature information output device comprises: A first element, which is disposed on the rotor; as well as a second element, which is arranged on the stator, detects magnetic flux and outputs an electrical signal corresponding to the detected magnetic flux as the temperature information, The first element comprises: a temperature sensing element whose resistance varies according to the temperature of the permanent magnet; and A first coil is electrically connected to the temperature sensing element. The second element comprises: a second coil configured to excite the first coil; and a current detection element that outputs an electrical signal corresponding to the magnitude of the current flowing through the second coil, The first element and the second element are arranged so as to face each other in a direction substantially parallel to a rotation axis line of the rotor when the rotor is at a predetermined rotation angle position.

2. The magnet temperature information output device according to claim 1, wherein: The magnet temperature information output device further includes: a capacitor that is disposed on the rotor and forms an LC resonance circuit with the first coil.

3. A device for outputting magnet temperature information, wherein: The magnet temperature information output device is a magnet temperature information output device that is disposed in a rotating electrical machine having a stator and a rotor having permanent magnets disposed thereon and outputs temperature information related to the temperature of the permanent magnets. The magnet temperature information output device comprises: a second element, which is disposed on the stator, detects magnetic flux and outputs an electrical signal corresponding to the detected magnetic flux as the temperature information; a temperature sensing element disposed on the rotor and having a resistance that changes according to the temperature of the permanent magnet; A first coil, which is disposed on the rotor and electrically connected to the temperature sensing element; as well as a capacitor, which is arranged on the rotor and forms an LC resonance circuit with the first coil, The second element comprises: a second coil configured to excite the first coil; and The current detection element outputs an electric signal corresponding to the magnitude of the current flowing through the second coil.

4. A rotating electrical machine, wherein: The rotating electrical machine includes the magnet temperature information output device according to any one of claims 1 to 3.

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