Inference device, inference method, and storage device storing program

Abstract

An inference device for inferring the state of a device for detecting the position of a rotating body comprises: a position sensor which outputs a detection signal as a signal representing a detection result of the position of the magnet based on the magnetic flux of a magnet that can rotate in conjunction with the rotating body; an extraction unit which extracts a feature quantity of the detection signal from the detection signal according to each position; and an inference unit which derives an evaluation value representing a comparison result of the feature quantity of the detection signal representing each position with a reference value for each position, and infers the degree of change in sensitivity for detecting the position based on the evaluation value.

Description

Technical Field

[0001] The present invention relates to an inference device, an inference method, and a storage device storing a program. Background Art

[0002] There is a technology that uses a general-purpose magnetic sensor, standard on motors, to estimate the position of the motor's rotor (see Patent Document 1). Because such magnetic sensors are inexpensive and compact, both the inference device using them and the motor incorporating them can be made inexpensive and compact. Furthermore, the rotor's position can be estimated without the use of expensive and bulky dedicated position sensors such as optical or magnetic encoders.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2016 / 104378

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2007-206018

[0007] Patent Document 3: International Publication No. 2008 / 062778

[0008] Patent Document 4: Japanese Patent Application Laid-Open No. 2011-185747 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] However, the above technology estimates the position of a rotating object (such as a motor rotor) and does not include the ability to estimate the degree of change in position detection sensitivity. If the state and sensitivity of the sensor and rotating object could be estimated, maintenance costs and downtime could be reduced. Therefore, there is a need to estimate the degree of change in position detection sensitivity without requiring an additional, dedicated sensor.

[0011] In view of the above situation, an object of the present invention is to provide a state estimation device, estimation method and program that can estimate the degree of change in position detection sensitivity without having an additional dedicated sensor for estimating the degree of change in position detection sensitivity.

[0012] Means for solving problems

[0013] One embodiment of the present invention is an inference device that infers the state of a device for detecting the position of a rotating body, wherein the inference device comprises: a position sensor that outputs a detection signal as a signal representing the detection result of the position of the magnet based on the magnetic flux of a magnet that can rotate in conjunction with the rotating body; an extraction unit that extracts a characteristic quantity of the detection signal from the detection signal according to each of the positions; and an inference unit that derives an evaluation value of a comparison result of the characteristic quantity of the detection signal representing each of the positions with a reference value of each of the positions, and infers the degree of change in the sensitivity of detecting the positions based on the evaluation value.

[0014] Effects of the Invention

[0015] According to the present invention, an object of the present invention is to provide an estimating device, an estimating method, and a program capable of estimating the degree of change in position detection sensitivity without requiring an additional dedicated sensor for estimating the degree of change in position detection sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a diagram showing a configuration example of the sensor unit in the first embodiment.

[0017] Figure 2 This is a diagram showing an example of the correspondence relationship among pole pair numbers, segments, and partitions in the first embodiment.

[0018] Figure 3 It is a diagram showing a configuration example of a position sensor in the first embodiment.

[0019] Figure 4 1 is a diagram showing an example of sampling points of a detection signal in the first embodiment.

[0020] Figure 5 This is a diagram showing an example of a case where the feature amounts of detection signals of all phases change within one cycle of electrical angle in the first embodiment.

[0021] Figure 6 This is a diagram showing an example of a case where a feature amount of a detection signal of a specific phase changes within one cycle of a mechanical angle in the first embodiment.

[0022] Figure 7 This is a diagram showing an example of a case where the feature amounts of detection signals of all phases change within one cycle of the mechanical angle in the first embodiment.

[0023] Figure 8 This is a flowchart showing an example of the operation of the sensor unit in the first embodiment.

[0024] Figure 91 is a diagram showing an example of a detection signal in a modification of the first embodiment.

[0025] Figure 10 It is a diagram showing a configuration example of a position sensor in the second embodiment.

[0026] Figure 11 It is a diagram showing a configuration example of a sensor unit in a third embodiment.

[0027] Figure 12 It is a diagram showing a configuration example of a position sensor in a third embodiment.

[0028] Figure 13 It is a diagram showing a configuration example of a sensor unit in a fourth embodiment. DETAILED DESCRIPTION

[0029] Embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0030] (First embodiment)

[0031] Figure 1 : This is a diagram showing a structural example of the sensor unit 1a in the first embodiment. The sensor unit 1a has a magnet 2 and an inference device 3a. The magnet 2 is a magnet used for a position sensor that detects the position of a rotating object such as a rotor. In the following, as an example, the number of pole pairs of the magnet 2 is 4. The inference device 3a has a position sensor device 30 and a determination device 31. The position sensor device 30 has M (M is an integer greater than or equal to 3) magnetic sensors 300 and an extraction unit 301. In the first embodiment, as an example, "M" is 3. The position sensor device 30 has M magnetic sensors 300 as position sensors 302. The determination device 31 has a control unit 310, a storage unit 311, an inference unit 312, and an output unit 313. The sensor unit 1a has a magnet 2 and a position sensor device 30 as a device for detecting the position of a rotating body.

[0032] Figure 2 This diagram shows an example of the correspondence between pole pair numbers, segments, and partitions. Each pole pair number corresponds to a segment number group. The number of segment numbers is equal to the number of 12 logical types, including the magnitude relationship of the detection signals output by the M magnetic sensors 300 and the positive and negative signs (zero crossings) of the intermediate signals.

[0033] exist Figure 2 In the figure, the pole pair number "0" corresponds to the segment number "0" to "11". The segment number is a unique number that represents the absolute value of the mechanical angle of the magnet 2. For example, the segment numbers "0" to "11" of the pole pair number "0" correspond to the partition numbers "0" to "11". For example, the segment numbers "0" to "11" of the pole pair number "1" correspond to the partition numbers "12" to "23". Figure 2 The data table showing the correspondence relationship is stored in advance in the storage unit 311 , for example.

[0034] Figure 3 1 is a diagram showing a configuration example of the position sensor 302 in the first embodiment. Figure 3 The upper portion of represents the upper surface of the position sensor 302 . Figure 3 The lower part of shows the side surface of the position sensor 302. The M magnetic sensors 300 are provided on the substrate 100 whose positions are fixed.

[0035] Rotor 201 is a rotating object. This rotating object is, for example, a rotating mechanism, not limited to a motor. Rotor 201 includes a main shaft 200. Magnets 2 are connected to main shaft 200. Rotation of rotor 201 rotates main shaft 200. Magnets 2 can rotate in conjunction with rotor 201 and main shaft 200.

[0036] Next, the sensor unit 1a will be described in detail. Each magnetic sensor 300 outputs a detection signal representing the detection result of the position of magnet 2 (the magnetic flux component of the pole pair) to the extraction unit 301. As an example, magnetic sensor 300-1 outputs a U-phase detection signal representing the position of magnet 2 to the extraction unit 301. Magnetic sensor 300-2 outputs a V-phase detection signal representing the position of magnet 2 to the extraction unit 301. Magnetic sensor 300-3 outputs a W-phase detection signal representing the position of magnet 2 to the extraction unit 301.

[0037] The extraction unit 301 reduces in-phase noise in each detection signal. It extracts the feature value of each detection signal for each position of the magnet 2. The extraction unit 301 outputs the feature value (array data) of the detection signal for each position to the inference unit 312 and the control unit 310.

[0038] Figure 4 This is a diagram showing an example of sampling points of the detection signal in the first embodiment. The horizontal axis represents the rotor angle (the position of the magnet 2). The vertical axis represents the digital value of the detection signal. "HU" represents the detection signal of the U phase. "HV" represents the detection signal of the V phase. "HW" represents the detection signal of the W phase. Figure 4 , sampling points 401 to 424 are shown as an example of sampling points representing n (n is an integer greater than or equal to 1) feature quantities extracted from the detection signal.

[0039] The sampling point 401 , the sampling point 405 , the sampling point 409 , the sampling point 415 , the sampling point 419 , and the sampling point 423 are intersection points of the waveform of the detection signal.

[0040] Sampling points 402, 404, 406, 408, 410, and 412 are points representing characteristic quantities of each of the other detection signals when the digital value of the detection signal is 0 (zero crossing). For example, sampling point 402 represents the digital value of the detection signal "HU" when the digital value of the detection signal "HW" is 0. Sampling points 414, 416, 418, 420, 422, and 424 are points representing characteristic quantities of each of the other detection signals when the digital value of the detection signal is 0 (zero crossing).

[0041] The sampling points 403, 407, and 411 are respectively the maximum values ​​of the digital value of the detection signal, while the sampling points 413, 417, and 421 are respectively the minimum values ​​of the digital value of the detection signal.

[0042] Return to Figure 1 Next, the configuration example of the sensor unit 1a is described. The control unit 310 controls the operation of the storage unit 311. For example, the control unit 310 records the feature value of the detection signal in the storage unit 311 for each sampling point.

[0043] The storage unit 311 stores the characteristic value (digital value) of the detection signal at each sampling point as the characteristic value of the detection signal at each position. Since there are only a few sampling points, the storage capacity of the storage unit 311 can be relatively small. The storage unit 311 pre-stores a reference value for each position. The reference value is, for example, a characteristic value of the detection signal measured at a past time. The past time may be, for example, the time when the magnet 2 and position sensor device 30 were installed or when the device was shipped from the factory. The reference value may also be updated periodically.

[0044] The feature value of the detection signal is input to the estimation unit 312 at each position (sampling point). The estimation unit 312 derives an evaluation value representing the result of comparing the feature value of the detection signal at each position with the reference value at each position. The evaluation value is expressed using the mean square error as shown in Equation (1), for example.

[0045]

Mathematical formula 1

[0046]

[0047] Here, "r i " represents the reference value (reference feature quantity). "d i" represents the characteristic value (measured value) of the detection signal. "n" represents the number of samples contained in a predetermined evaluation unit. The evaluation unit is, for example, one cycle of the mechanical angle or one cycle of the electrical angle. If the evaluation is performed in units (phase units) of the detection signal "Hu", the detection signal "Hv" and the detection signal "Hw", the reference value and the current value are compared in phase units for the maximum and minimum values ​​of each phase, and the changes in the phase unit can be detected based on the evaluation value of the phase unit.

[0048] The inference unit 312 infers the degree of change in the sensitivity of position detection based on the evaluation value. For example, the inference unit 312 compares the evaluation value with a predetermined threshold. If the evaluation value is greater than the threshold, the inference unit 312 may determine that the sensitivity of position detection has changed.

[0049] Figure 5 This diagram shows an example of how the characteristic quantities of the detection signals of all phases change within one electrical angle cycle in the first embodiment. The horizontal axis represents four electrical angle cycles (the position of magnet 2). Four electrical angle cycles correspond to one mechanical angle cycle of magnet 2. The vertical axis represents the digital value of the detection signal.

[0050] In the case where the magnetic flux changes only in one pole pair of the magnet 2, the characteristic quantities of the detection signals (HU, HV, HW) of all phases in one cycle of the electrical angle corresponding to the pole pair change. Therefore, in the case where the evaluation value represents that the characteristic quantity of the detection signal in one cycle of the electrical angle in one cycle of the mechanical angle has changed relative to the reference value of each position, the inference unit 312 determines that the magnetic flux of the pole pair of the magnet corresponding to one cycle of the electrical angle has changed. For example, in the case where the evaluation value such as that of formula (1) is above the threshold, the inference unit 312 may also determine that the magnetic flux of the pole pair corresponding to one cycle of the electrical angle has changed. Figure 5 , the estimation unit 312 determines that the magnetic flux of the pole pairs corresponding to the electrical angles "2π" to "4π" has changed.

[0051] Figure 6 This diagram shows an example of how the characteristic value of a detection signal of a specific phase changes within one cycle of the mechanical angle in the first embodiment. The horizontal axis represents four cycles of the electrical angle (the position of the magnet 2). The vertical axis represents the digital value of the detection signal.

[0052] exist Figure 6In the example above, within one mechanical angle cycle, the characteristic value of the detection signal from magnetic sensor 300, which detects signal "HU," changes relative to the reference value at each position. This change may be due to a change in the distance between magnetic sensor 300, which outputs detection signal "HU," and magnet 2, or a change in the sensitivity of magnetic sensor 300, which outputs detection signal "HU."

[0053] Therefore, if the evaluation value indicates that the characteristic value of the detection signal "HU" from the magnetic sensor 300 has changed relative to the reference value at each position during one mechanical angle cycle, the inference unit 312 determines that the distance between the magnetic sensor 300 outputting the detection signal "HU" and the magnet 2 has changed. The inference unit 312 may also determine that the sensitivity of the magnetic sensor 300 outputting the detection signal "HU" has changed.

[0054] Figure 7 This diagram shows an example of how the characteristic quantities of detection signals for all phases change within one mechanical angle cycle in the first embodiment. The horizontal axis represents four cycles of electrical angle (the position of magnet 2 ). The vertical axis represents the digital value of the detection signal.

[0055] exist Figure 7 In one mechanical angle cycle, the characteristic quantities of the detection signals of all magnetic sensors 300 vary relative to the reference value at each position. This variation is primarily due to the possibility that the magnetic flux of all pole pairs of magnet 2 varies, or that all magnetic sensors 300 are more than a predetermined distance from magnet 2. The predetermined distance is, for example, the designed distance between magnet 2 and magnetic sensor 300.

[0056] Therefore, if the evaluation value indicates that the characteristic quantities of the detection signals "HU," "HV," and "HW" of all magnetic sensors 300 have changed relative to the reference values ​​for each position during one mechanical angle cycle, the inference unit 312 determines that the magnetic flux of all pole pairs of magnet 2 has changed. The inference unit 312 can also determine that the distance between magnet 2 and all magnetic sensors 300 has changed. The inference unit 312 can also determine that the sensitivity of all magnetic sensors has changed.

[0057] The output unit 313 outputs the degree of change in the sensitivity of position detection to an external device (not shown). The output unit 313 may also output the result of comparing the degree of change in the sensitivity of position detection with a threshold to a predetermined external device. For example, if the degree of change exceeds the threshold, the output unit 313 may output a warning message regarding the change in the sensitivity of position detection to the external device (not shown).

[0058] Next, an operation example of the sensor unit 1 a will be described. Figure 8 This is a flowchart illustrating an example of the operation of the sensor unit 1a in the first embodiment. Each magnetic sensor 300 outputs a detection signal for each position of the magnet 2 to the extraction unit 301 (step S101). The extraction unit 301 extracts a feature value from the detection signal for each position of the magnet 2 (step S102).

[0059] The estimation unit 312 derives an evaluation value. The evaluation value represents the result of comparing the characteristic quantity of the detection signal at each position of magnet 2 with the reference value at each position of magnet 2 (step S103). The estimation unit 312 estimates the degree of change in sensitivity for detecting the position of magnet 2 based on the evaluation value (step S104). The output unit 313 outputs the degree of change in sensitivity for position detection to a predetermined external device (not shown) (step S105).

[0060] As described above, the estimation device 3a estimates the state of the position sensor device 30, which is a device for detecting the position of the rotor 201 (rotating body). The estimation device 3a can also estimate the state of the magnet 2 (for example, deterioration of the magnetic flux). The position sensor 302 outputs a detection signal, which is a signal indicating the detection result of the position of the magnet 2, to the extraction unit 301 based on the magnetic flux of the magnet 2, which can rotate in conjunction with the rotor 201 (rotating body). The extraction unit 301 extracts the feature quantity of the detection signal from the detection signal for each position of the magnet 2. The estimation unit 312 derives an evaluation value representing the result of comparing the feature quantity of the detection signal for each position of the magnet 2 with a reference value for each position of the magnet 2. Based on the evaluation value, the estimation unit 312 estimates the degree of change (for example, deterioration) in the sensitivity (for example, sensitivity) for detecting the position of the magnet 2.

[0061] In this way, the estimation unit 312 derives an evaluation value representing the comparison result of the characteristic quantity of the detection signal at each position of the magnet 2 and the reference value at each position of the magnet 2. As a result, the degree of change in the sensitivity of the position detection can be estimated without having an additional dedicated sensor for estimating the degree of change in the sensitivity of the position detection. Here, Figure 4 As shown in FIG. 1 , the degree of change in the sensitivity of the magnetic sensor 300 can be detected in units of pole pairs. Figure 5 As shown, the degree of change in the sensitivity of the magnetic sensor 300 can be detected in units of magnetic sensors (in units of position sensors).

[0062] Modifications

[0063] Figure 9: is a diagram showing an example of detection signals in a modification of Embodiment 1. The extraction unit 301 may directly use the digital value of each detection signal after correcting the in-phase noise as a feature value of the detection signal as follows.

[0064] Storage unit 311 stores array data for each detection signal, such as the U-phase detection signal U[i], the V-phase detection signal V[i], and the W-phase detection signal W[i]. Here, "i" represents the sample number (1 to s). "s" represents the number of samples in one mechanical angle cycle. Furthermore, due to the large number of sampling points, the storage capacity of storage unit 311 can be increased.

[0065] (Second embodiment)

[0066] The second embodiment differs from the first embodiment in that a position sensor 302 is provided on the motor housing. In the second embodiment, the differences from the first embodiment will be mainly described.

[0067] Figure 10 1 is a diagram showing a configuration example of the position sensor 302 in the second embodiment. Figure 10 The upper portion of represents the upper surface of the position sensor 302 . Figure 10 The lower part of shows the side surface of the position sensor 302. M magnetic sensors 300 are provided on the substrate 100 whose positions are fixed. In the second embodiment, "M" is 3 as an example.

[0068] The stator 202 is an electromagnet having a U-phase coil, a V-phase coil, and a W-phase coil. The stator 202 generates magnetic flux by flowing a current corresponding to the command value through each phase coil. The rotor 203 is a magnet. The stator 202 and the rotor 203 constitute a motor. The rotor 203 has a main shaft 200. The magnet 2 is connected to the main shaft 200. The main shaft 200 rotates when the rotor 203 rotates. The magnet 2 can rotate in conjunction with the rotor 203 and the main shaft 200. Figure 10 In the embodiment, the spindle 200 is arranged so as to pass through the substrate 100. That is, the position sensor 302 is not in contact with the spindle 200 but is fixed to the housing 400 to which the stator 202 is fixed.

[0069] Alternatively, the magnet 2 connected to the spindle 200 may be disposed outside the housing 400. In the case where the magnet 2 connected to the spindle 200 is disposed outside the housing 400, the position sensor 302 is disposed between the magnet 2 and the housing 400. Furthermore, the M magnetic sensors 300 are disposed on a surface of the substrate 100 of the position sensor 302 that is closer to the magnet 2.

[0070] As described above, position sensor 302 is fixed to housing 400, to which stator 202 is fixed, without contacting spindle 200. Position sensor 302 outputs a detection signal representing the detection result of magnet 2 to extraction unit 301. In this way, estimation unit 312 derives an evaluation value representing the result of comparing the characteristic quantity of the detection signal at each position of magnet 2 with a reference value for each position of magnet 2. This makes it possible to estimate the degree of change in position detection sensitivity without adding a dedicated sensor to the motor for estimating the degree of change in position detection sensitivity.

[0071] (Third embodiment)

[0072] The third embodiment differs from the first and second embodiments in that the rotor (magnet) of the motor is used as a magnet for the position sensor. In the third embodiment, the differences from the first and second embodiments will be mainly described.

[0073] Figure 11 This diagram shows a configuration example of a sensor unit 1b in a third embodiment. The sensor unit 1b includes an estimation device 3b and a control device 4. The estimation device 3b includes a position sensor device 30 and a determination device 31. The position sensor device 30 includes M magnetic sensors 300 and an extraction unit 301. The position sensor device 30 includes M magnetic sensors 300 as position sensors 302. In the third embodiment, "M" is, as an example, 6. The determination device 31 includes a control unit 310, a storage unit 311, an estimation unit 312, and an output unit 313.

[0074] Figure 12 1 is a diagram showing a configuration example of a position sensor 302 in the third embodiment. Figure 12 The upper portion of represents the upper surface of the position sensor 302 . Figure 12 The lower section shows the side surface of the position sensor 302 .

[0075] The stator 202 is an electromagnet having a U-phase coil, a V-phase coil, and a W-phase coil. When a current corresponding to a command value flows through each phase coil, the stator 202 generates magnetic flux. The rotor 203 is a magnet. The stator 202 and the rotor 203 constitute a motor. The rotor 203 has a main shaft 200. When the rotor 203 (magnet) rotates, the main shaft 200 rotates. Figure 12In the embodiment, the spindle 200 is arranged so as to pass through the base plate 100. That is, the position sensor 302 does not contact the spindle 200 but is fixed to the housing 400 to which the stator 202 is fixed. The rotor 203 is used as a magnet for the position sensor that detects the position of the rotor 203, replacing the magnet 2. The control device 4 determines the current value to be applied to the stator 202 (electromagnet) based on command values ​​such as the rotational speed and torque value and the position information (angle information) of the rotor 203 (magnet) obtained from the position sensor device 30. The control device 4 causes current to flow through the stator 202 (electromagnet) based on the determined current value, thereby generating a magnetic field and controlling the drive of the rotor 203.

[0076] M magnetic sensors 300 are provided on a substrate 100 whose position is fixed. In the third embodiment, as an example, "M" is 6. Magnetic sensors 300-1 to 300-3 (a plurality of first magnetic sensors) are provided near the magnets constituting the rotor 203. Magnetic sensors 300-4 to 300-6 (a plurality of second magnetic sensors) are further away from the main shaft 200 than the distance between the magnetic sensors 300-1 to 300-3 and the main shaft 200, and are provided near the stator 202. Figure 12 In FIG. 3 , magnetic sensor 300-4, magnetic sensor 300-1, and spindle 200 are arranged in a straight line. Magnetic sensor 300-5, magnetic sensor 300-2, and spindle 200 are arranged in a straight line. Magnetic sensor 300-6, magnetic sensor 300-3, and spindle 200 are arranged in a straight line.

[0077] Magnetic sensors 300-1 to 300-3 detect magnetic flux from both rotor 203 (magnet) and stator 202 (electromagnet), and output detection signals to extraction unit 301. The detection signal output from any of magnetic sensors 300-1 to 300-3 is expressed as shown in equation (2).

[0078] Magnetic sensors 300-4 to 300-6 also detect magnetic flux from both rotor 203 (magnet) and stator 202 (electromagnet), and output detection signals to extraction unit 301. The detection result of the magnetic flux component output by any of magnetic sensors 300-4 to 300-6 is expressed as shown in equation (3).

[0079]

Mathematical formula 2

[0080]

[0081]

Mathematical formula 3

[0082]

[0083] Here, "VHA" represents a detection signal (magnetic flux component amount) output from any of the magnetic sensors 300-1 to 300-3. "VHB" represents a detection result (magnetic flux component detection result) output from any of the magnetic sensors 300-4 to 300-6. It shows the magnetic flux component (leakage flux component) of the stator 202. "θ" represents the magnetic flux component of the rotor 203. "θ" represents the electrical angle of the rotor 203. "I" represents the value of the current flowing through the coil of the stator 202.

[0084] The coefficients "x," "y," "j," and "k" depend on the motor structure and the placement of the magnetic sensors, and are determined, for example, based on experimental or simulation results. "x" is a coefficient in the term for the magnetic flux of rotor 203, and is, for example, a coefficient corresponding to each distance between magnetic sensors 300-1 through 300-3 and rotor 203. "y" is a coefficient in the term for the magnetic flux of stator 202, and is, for example, a coefficient corresponding to each distance between magnetic sensors 300-4 through 300-6 and rotor 203.

[0085] "j" is a coefficient in the term of the magnetic flux of stator 202, and is, for example, a coefficient corresponding to each distance between magnetic sensor 300-1 to magnetic sensor 300-3 and stator 202. "k" is a coefficient in the term of the magnetic flux of stator 202, and is, for example, a coefficient corresponding to each distance between magnetic sensor 300-4 to magnetic sensor 300-6 and stator 202.

[0086] Therefore, the extraction unit 301 uses the detection results of the magnetic flux components of the stator 202 to extract a signal representing the detection results of the magnetic flux components of the stator 202 alone from the detection signals output by the magnetic sensors 300-1 to 300-6. The detection results (correction values) of the magnetic flux components of the stator 202 alone are expressed as shown on the right side of equation (4). For example, the extraction unit 301 derives the detection results of the magnetic flux components of the stator 202 alone as shown on the right side of equation (4) based on the detection signal "VHA" output from the magnetic sensor 300-1 and the detection signal (magnetic flux component amount) "VHB" output from the magnetic sensor 300-4.

[0087]

Mathematical formula 4

[0088]

[0089] The extraction unit 301 obtains a command value for the amount of current flowing through the stator 202 from the control device 4. The extraction unit 301 derives an estimated value for the magnetic flux component of the stator 202 alone based on the command value for the amount of current flowing through the stator 202. The estimation unit 312 can estimate the state of the stator 202 by comparing the estimated value for the magnetic flux component of the stator 202 alone with the detection result of the magnetic flux component of the stator 202 alone. The magnetic flux component of the stator 202 is measured during assembly or at the time of shipment and pre-stored in the storage unit 311. The estimation unit 312 can also estimate the state of the stator 202 by comparing the magnetic flux component of the stator 202 pre-stored in the storage unit 311 with the detected magnetic flux component.

[0090] As described above, the estimation device 3b estimates the state of the position sensor device 30, which detects the position of the rotor 203 (rotating body), and the state of the stator 202. The estimation device 3b can also estimate the state of the rotor 203 (for example, deterioration of the magnetic flux). The estimation unit 312 estimates the degree of change in the stator 202 based on the difference between the estimated value of the magnetic flux component of the stator 202 based on the current flowing through the stator 202 and the detection result of the magnetic flux component of the stator 202 alone. This improves the sensitivity of estimating the degree of change in the position detection sensitivity without requiring an additional dedicated sensor for estimating the degree of change in the position detection sensitivity.

[0091] (Fourth embodiment)

[0092] The fourth embodiment differs from the first to third embodiments in that the sensor unit includes a plurality of position sensor devices and a single determination device (the determination device is a central determination type). The fourth embodiment will mainly describe the differences from the first to third embodiments.

[0093] Figure 13 This figure shows an example configuration of a sensor unit 1c in a fourth embodiment. The sensor unit 1c includes P (P is an integer greater than or equal to 2) magnets 2 and an estimation device 3c. The estimation device 3c includes P position sensor devices 30 and a determination device 31. The position sensor device 30 includes M magnetic sensors 300 and an extraction unit 301. The position sensor device 30 includes M magnetic sensors 300 as position sensors 302. The determination device 31 includes a control unit 310, a storage unit 311, an estimation unit 312, and an output unit 313.

[0094] Position sensor 302-p (p is any integer from 2 to P) outputs a detection signal representing the position of magnet 2-p (magnetic flux components of pole pairs) to extraction unit 301. Extraction unit 301 reduces common-phase noise in each detection signal. Extraction unit 301 extracts a feature value from each detection signal for each position of magnet 2. Extraction unit 301 outputs the feature value (array data) of the detection signal for each position to inference unit 312 and control unit 310.

[0095] As described above, the estimation device 3c estimates the state of the position sensor device 30, which detects the position of the rotor 201 or rotor 203 (rotating body). The estimation device 3c can also estimate the state of the magnet 2. There are multiple magnets 2. The position sensor device 30 includes a position sensor 302 for each magnet 2. This eliminates the need for an additional dedicated sensor to estimate the degree of change in position detection sensitivity, and allows estimation of the degree of change in position detection sensitivity for multiple magnets 2.

[0096] Furthermore, changes in the stator 202 (changes in magnetic flux) can be inferred. Changes in the distance between the stator 202 and the magnetic sensor 300 can be inferred. The state of the stator 202 can be inferred. The state of the stator 202 may include, for example, changes in the resistance of the slot windings, the presence of wire breaks, changes in the current flow due to temperature rise, or changes in the magnetic flux component. Furthermore, in the second embodiment described above, the additional magnetic sensor 300 may be provided on the substrate 100. As long as the additional magnetic sensor 300 can detect sufficiently large leakage magnetic flux from the stator 202, the state of the stator 202 can be inferred.

[0097] The program for realizing the functions of the inference device in the present invention may be recorded in a computer-readable recording medium (not shown), and the computer system may read and execute the program recorded in the recording medium (non-temporary recording medium) to perform the various processing steps. In addition, the "computer system" mentioned here includes hardware such as an OS and peripheral devices. In addition, the "computer system" also includes a WWW system having a homepage providing environment (or display environment). In addition, a "computer-readable recording medium" refers to a removable medium such as a floppy disk, a magneto-optical disk, a ROM, a CD-ROM, or a storage device such as a hard disk built into the computer system. Furthermore, a "computer-readable recording medium" also includes a medium that stores a program for a certain period of time, such as a volatile memory (RAM) inside a computer system of a server or client in the case of transmitting a program via a network such as the Internet or a communication line such as a telephone line.

[0098] In addition, the above-mentioned program can also be transmitted from a computer system that stores the program in a storage device or the like via a transmission medium, or by transmission waves in the transmission medium to other computer systems. Here, the "transmission medium" that transmits the program refers to a medium that has the function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. In addition, the above-mentioned program can also be used to implement a part of the above-mentioned functions. Moreover, it can also be a so-called differential file (differential program) that can realize the above-mentioned functions by combining with a program already recorded in a computer system.

[0099] Label Description

[0100] 1a, 1b, 1c: sensor unit; 2: magnet; 3a, 3b, 3c: inference device; 4: control device; 30: position sensor device; 31: determination device; 100: substrate; 200: main shaft; 201: rotor; 202: stator; 203: rotor; 300: magnetic sensor; 301: extraction unit; 302: position sensor; 310: control unit; 311: storage unit; 312: inference unit; 313: output unit; 400: housing; 401-424: sampling points.

Claims

1. An inference device for inferring the state of a device for detecting the position of a rotating body, wherein: The inference device has: a position sensor that outputs a detection signal representing a detection result of an electrical angle position of the magnet in one cycle of a mechanical angle based on a magnetic flux of a magnet rotatable in conjunction with the rotating body; an extraction unit that extracts a feature amount of the detection signal from the detection signal at each electrical angle position in one cycle of the mechanical angle; as well as An estimating unit derives an evaluation value representing a comparison result of a feature quantity of the detection signal for each electrical angular position with a reference value for each electrical angular position, and estimates a degree of change in sensitivity of detecting the electrical angular position in one cycle of a mechanical angle based on the evaluation value.

2. The inference device according to claim 1, wherein: When the evaluation value indicates that a characteristic quantity of the detection signal has changed relative to a reference value for each electrical angle position in one cycle of the mechanical angle representing the electrical angle position, the inference unit determines that the magnetic flux of the pole pair of the magnet corresponding to one cycle of the electrical angle has changed.

3. The inference device according to claim 1, wherein: A plurality of magnetic sensors are arranged at equal intervals along the rotation direction of the rotation axis of the rotating body. When the evaluation value indicates that a characteristic quantity of the detection signal of any of the magnetic sensors in one cycle of the mechanical angle representing the electrical angle position has changed relative to a reference value of each of the electrical angle positions, the inference unit determines that the distance between the magnet and the magnetic sensor has changed or the sensitivity of the magnetic sensor has changed.

4. The inference device according to claim 1, wherein: The position sensor includes a magnetic sensor for detecting the magnetic flux of the magnet in response to each of the detection signals. When the evaluation value indicates that the characteristic quantity of the detection signals of all the magnetic sensors in one cycle of the mechanical angle representing the electrical angle position has changed relative to the reference value of each of the electrical angle positions, the inference unit determines that the magnetic flux of all pole pairs of the magnet has changed, the distance between the magnet and all the magnetic sensors has changed, or the sensitivity of all the magnetic sensors has changed.

5. The inference device according to claim 1, wherein: The position sensor includes a plurality of first magnetic sensors disposed near the magnet constituting a rotor of the motor and a plurality of second magnetic sensors disposed near the stator of the motor. The extraction unit derives a detection result of the magnetic flux component of the stator based on the detection signal input from the first magnetic sensor and a detection result of the magnetic flux component input from the second magnetic sensor. The estimation unit estimates the degree of change in the stator based on a difference between an estimated value of a magnetic flux component of the stator based on a current flowing in the stator and a detection result of the magnetic flux component of the stator.

6. The inference device according to any one of claims 1 to 5, wherein: There are multiple magnets. The position sensor is disposed on each of the magnets.

7. An inference method, the inference method being performed by an inference device for inferring a state of a device for detecting a position of a rotating body, wherein: The inference method includes the following steps: an outputting step of outputting a detection signal as a signal indicating a detection result of an electrical angle position of the magnet in one cycle of a mechanical angle based on a magnetic flux of a magnet rotatable in conjunction with the rotating body; an extraction step of extracting a feature quantity of the detection signal from the detection signal at each electrical angle position in one cycle of the mechanical angle; as well as The inference step derives an evaluation value representing a comparison result of a feature quantity of the detection signal for each of the electrical angle positions and a reference value for each of the electrical angle positions, and infers a degree of change in sensitivity of detecting the electrical angle position in one cycle of the mechanical angle based on the evaluation value.

8. A storage device for storing a program, wherein: This program is for causing a computer to function as the estimation device according to any one of claims 1 to 6.

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