Position detection device and position detection method

Abstract

This position detection device comprises a signal processing unit. A period corresponding to one cycle of the mechanical angle of a rotor is divided into a plurality of quadrants. A period corresponding to one cycle of the mechanical angle of the rotor is divided into a plurality of sections. The signal processing unit executes a first acquisition process for acquiring a quadrant number indicating a quadrant, a second acquisition process for acquiring a section number, a mechanical angle calculation process for calculating information relating to the mechanical angle of the rotor, and an abnormality detection process for detecting an abnormality of a first detection signal and abnormality of a second detection signal. The abnormality detection process includes a first abnormality determination process for determining that an abnormal location is present in the first detection signal if the chronological arrangement of quadrant numbers is different from a chronological arrangement of quadrant numbers when normal, and a second abnormality determination process for determining that an abnormal location is present in the second detection signal if the chronological arrangement of section numbers is different from a chronological arrangement of section numbers when normal.

Description

Position detection device and position detection method

[0001] The present invention relates to a position detection device and a position detection method. This application is based on Japanese Patent Application No. 2024-051177, filed on March 27, 2024. This application claims the benefit of priority to that application, the entire contents of which are incorporated herein by reference.

[0002] Conventionally, a rotation detection device is known that has two systems of circuits required to detect motor rotation, so that it can continue to perform rotation detection operations even if an abnormality occurs in part of the circuit (for example, Patent Document 1).

[0003] Japanese Patent Publication No. 2017-191093

[0004] In the rotation detection device as described above, it is necessary to provide a plurality of identical detection circuits, which increases the cost of the rotation detection device.

[0005] In view of the above circumstances, an object of the present invention is to provide a position detection device and a position detection method that can improve redundancy in detecting the rotational position of a motor while suppressing an increase in cost.

[0006] One aspect of the position detection device of the present invention is a position detection device for detecting the rotational position of a rotor of a motor, the position detection device comprising: a first magnet having one magnetic pole pair and rotating together with the rotor; P (P is an integer of 2 or greater) second magnets having magnetic pole pairs and rotating together with the rotor; N1 (N1 is an integer of 2 or greater) first magnetic sensors facing the first magnet and spaced apart in the rotation direction of the first magnet; N2 (N2 is an integer of 3 or greater) second magnetic sensors facing the second magnet and spaced apart in the rotation direction of the second magnet; and a signal processing unit that processes N1 first detection signals output from the N1 first magnetic sensors and N2 second detection signals output from the N2 second magnetic sensors. A period corresponding to one mechanical angle period of the rotor is divided into a plurality of quadrants corresponding to combinations of signal strengths of the N1 first detection signals. A period corresponding to one period in terms of the mechanical angle of the rotor is divided into a plurality of sections separated by intersections between waveforms of the N2 second detection signals and zero-crossing points, which are points where the N2 second detection signals intersect with a reference value. The signal processing unit executes a first acquisition process to acquire quadrant numbers indicating the quadrants based on the N1 first detection signals, a second acquisition process to acquire section numbers indicating the sections based on the N2 second detection signals, a mechanical angle calculation process to calculate information about the mechanical angle of the rotor based on at least one of the quadrant numbers and the section numbers, and an abnormality detection process to detect an abnormality in the first detection signals and the second detection signals. The abnormality detection process includes a first abnormality determination process that determines that an abnormal portion exists in the first detection signal when the chronological arrangement of the quadrant numbers acquired in the first acquisition process differs from the chronological arrangement of the quadrant numbers under normal conditions, and a second abnormality determination process that determines that an abnormal portion exists in the second detection signal when the chronological arrangement of the section numbers acquired in the second acquisition process differs from the chronological arrangement of the section numbers under normal conditions.

[0007] One aspect of the position detection method of the present invention is a position detection method for detecting the rotational position of a rotor in a motor, comprising signal processing for processing N1 first detection signals output from N1 (N1 is an integer of 2 or greater) first magnetic sensors facing a first magnet and N2 second detection signals output from N2 (N2 is an integer of 3 or greater) second magnetic sensors facing a second magnet. The first magnet has one magnetic pole pair and rotates together with the rotor. The second magnet has P (P is an integer of 2 or greater) magnetic pole pairs and rotates together with the rotor. The N1 first magnetic sensors are arranged at intervals in the rotation direction of the first magnet. The N2 second magnetic sensors are arranged at intervals in the rotation direction of the second magnet. A period corresponding to one mechanical angle cycle of the rotor is divided into a plurality of quadrants corresponding to combinations of signal strengths of the N1 first detection signals. A period corresponding to one period in terms of the mechanical angle of the rotor is divided into a plurality of sections separated by intersections between waveforms of the N2 second detection signals and zero-crossing points, which are points where the N2 second detection signals intersect with a reference value. The signal processing includes a first acquisition process that acquires quadrant numbers indicating the quadrants based on the N1 first detection signals, a second acquisition process that acquires section numbers indicating the sections based on the N2 second detection signals, a mechanical angle calculation process that calculates information about the mechanical angle of the rotor based on at least one of the quadrant numbers and the section numbers, and an abnormality detection process that detects an abnormality in the first detection signals and the second detection signals. The abnormality detection process includes a first abnormality determination process that determines that an abnormal portion exists in the first detection signal when the chronological arrangement of the quadrant numbers acquired in the first acquisition process differs from the chronological arrangement of the quadrant numbers under normal conditions, and a second abnormality determination process that determines that an abnormal portion exists in the second detection signal when the chronological arrangement of the section numbers acquired in the second acquisition process differs from the chronological arrangement of the section numbers under normal conditions.

[0008] According to one aspect of the present invention, it is possible to improve the redundancy of the detection of the rotational position of the motor while suppressing an increase in the cost of the position detection device.

[0009] FIG. 1 is a diagram schematically illustrating a position detection device according to a first embodiment. FIG. 2 is a flowchart illustrating an example of a learning process according to the first embodiment. FIG. 3 is a diagram illustrating a first detection signal and a second detection signal according to the first embodiment. FIG. 4 is a diagram illustrating a portion of the second detection signal according to the first embodiment. FIG. 5 is a flowchart illustrating an example of a position detection process according to the first embodiment. FIG. 6 is a diagram illustrating a second detection signal that has been converted into a triangular wave according to the first embodiment. FIG. 7 is a diagram illustrating changes in quadrant numbers according to the first embodiment. FIG. 8 is a diagram illustrating changes in section numbers according to the first embodiment. FIG. 9 is a diagram illustrating changes in first count numbers and second count numbers according to the first embodiment. FIG. 10 is a flowchart illustrating an example of a signal processing procedure of a position detection unit according to the first embodiment. FIG. 11 is a diagram illustrating an example of a UVW signal according to the first embodiment. FIG. 12 is a diagram illustrating an example of an ABZ signal according to the first embodiment. FIG. 13 is a diagram illustrating changes in an output signal according to the first embodiment. FIG. 14 is a flowchart illustrating an example of a signal processing procedure of a position detection unit according to the second embodiment.

[0010] First Embodiment A position detection device 100 of this embodiment shown in FIG. 1 is a device that detects the rotational position of a rotor 20 in a motor 10. A position detection method of this embodiment is a method performed by the position detection device 100. In this embodiment, the motor 10 is a three-phase motor. The rotor 20 is a rotating body that can rotate around a central axis J. In the following description, the axial direction in which the central axis J extends may be simply referred to as the "axial direction," and the circumferential direction around the central axis J may be simply referred to as the "circumferential direction."

[0011] The position detection device 100 includes a first magnet 31, a second magnet 32, a first magnetic sensor 41, a second magnetic sensor 42, and a signal processing unit 50. Although not shown, the position detection device 100 also includes a circuit board. The first magnetic sensor 41, the second magnetic sensor 42, and the signal processing unit 50 are attached to the circuit board, for example.

[0012] The first magnet 31 has one magnetic pole pair. A magnetic pole pair refers to a pair of a north pole and a south pole. In the first magnet 31, one north pole and one south pole are arranged on either side of the central axis J. The first magnet 31 rotates together with the rotor 20. The first magnet 31 is fixed, for example, to the axial end of the shaft of the rotor 20. The first magnet 31 is, for example, disk-shaped and centered on the central axis J.

[0013] The second magnet 32 ​​has multiple magnetic pole pairs. In this embodiment, the second magnet 32 ​​has five magnetic pole pairs. Note that the number of magnetic pole pairs of the second magnet 32 ​​is not particularly limited as long as it is P, where P is an integer greater than or equal to two. In the second magnet 32, five north poles and five south poles are arranged alternately in the circumferential direction. In this embodiment, the second magnet 32 ​​is provided on the rotor 20. The second magnet 32 ​​is, for example, annular and surrounds the central axis J. In this embodiment, the second magnet 32 ​​is a rotor magnet in which magnetic flux of the second magnet 32 ​​flows between the rotor 20 and a stator (not shown) of the motor 10. The second magnet 32 ​​rotates together with the rotor 20.

[0014] The first magnetic sensors 41 face the first magnet 31 in the axial direction. In this embodiment, three first magnetic sensors 41 are provided: a first magnetic sensor 41a, a first magnetic sensor 41b, and a first magnetic sensor 41c. Note that the number of first magnetic sensors 41 is not particularly limited as long as it is N1, where N1 is an integer equal to or greater than two. The three first magnetic sensors 41a, 41b, and 41c are spaced apart in the rotational direction of the first magnet 31, i.e., the circumferential direction around the central axis J. The three first magnetic sensors 41a, 41b, and 41c are, for example, Hall ICs incorporating Hall elements and latch circuits. The three first magnetic sensors 41a, 41b, and 41c each output a digital signal whose level inverts every time the first magnet 31 rotates 180°.

[0015] In this embodiment, the three first magnetic sensors 41a, 41b, and 41c are arranged at 120° intervals along the rotation direction of the first magnet 31. Therefore, the digital signals output from the three first magnetic sensors 41a, 41b, and 41c have a phase difference of 120° relative to each other in mechanical angle θ. Hereinafter, the digital signals output from the three first magnetic sensors 41a, 41b, and 41c will be referred to as first detection signals. The first magnetic sensor 41a outputs a first detection signal HA1 to the signal processing unit 50. The first magnetic sensor 41b outputs a first detection signal HA2 to the signal processing unit 50. The first magnetic sensor 41c outputs a first detection signal HA3 to the signal processing unit 50.

[0016] The second magnetic sensor 42 faces the second magnet 32 ​​in the axial direction. In this embodiment, three second magnetic sensors 42 are provided: a second magnetic sensor 42a, a second magnetic sensor 42b, and a second magnetic sensor 42c. Note that the number of second magnetic sensors 42 is not particularly limited as long as it is N2, where N2 is an integer greater than or equal to three. The three second magnetic sensors 42a, 42b, and 42c are spaced apart in the rotational direction of the second magnet 32, i.e., the circumferential direction around the central axis J. The three second magnetic sensors 42a, 42b, and 42c are each a Hall element or a linear Hall IC. The second magnetic sensors 42a, 42b, and 42c each output an analog signal whose electrical signal fluctuates according to magnetic field strength. One electrical angle cycle of each analog signal output from each of the second magnetic sensors 42a, 42b, and 42c corresponds to 1 / P of one mechanical angle cycle. In this embodiment, since the number of pole pairs P of the rotor 20 is "5", one electrical angle cycle of each analog signal corresponds to 1 / 5 of one mechanical angle cycle, that is, 72° mechanical angle.

[0017] In this embodiment, the three second magnetic sensors 42a, 42b, and 42c are arranged at 24° intervals along the rotational direction of the rotor 20. Therefore, the analog signals output from the second magnetic sensors 42a, 42b, and 42c have a phase difference of 120° electrical angle from one another. Hereinafter, the analog signals output from the second magnetic sensors 42a, 42b, and 42c will be referred to as second detection signals. The second magnetic sensor 42a outputs a second detection signal Hu to the signal processing unit 50. The second magnetic sensor 42b outputs a second detection signal Hv to the signal processing unit 50. The second magnetic sensor 42c outputs a second detection signal Hw to the signal processing unit 50.

[0018] The signal processing unit 50 executes signal processing to process the three first detection signals HA1, HA2, HA3 output from the three first magnetic sensors 41 a, 41 b, 41 c and the three second detection signals Hu, Hv, Hw output from the three second magnetic sensors 42 a, 42 b, 42 c. The signal processing unit 50 detects the rotational position of the motor 10, i.e., the rotational position of the rotor 20, based on the three first detection signals HA1, HA2, HA3 and the three second detection signals Hu, Hv, Hw. The signal processing unit 50 includes a calculation unit 51 and a storage unit 52.

[0019] The calculation unit 51 is a microprocessor such as an MCU (Microcontroller Unit). Three first detection signals HA1, HA2, and HA3 and three second detection signals Hu, Hv, and Hw are input to the calculation unit 51. The calculation unit 51 is connected to the storage unit 52 via a data bus so as to be able to communicate data with the storage unit 52.

[0020] The three second detection signals Hu, Hv, and Hw, which are analog signals, are converted into digital signals via an A / D converter inside the calculation unit 51. For convenience of explanation, the digital signals output from the A / D converter are also referred to as second detection signals Hu, Hv, and Hw. In the following explanation, the three first detection signals HA1, HA2, and HA3 and the three second detection signals Hu, Hv, and Hw input to the calculation unit 51 may be collectively referred to as "input sensor signals."

[0021] The storage unit 52 includes a nonvolatile memory that stores programs, various values, learning data, and the like required for the calculation unit 51 to execute various processes, and a volatile memory that is used as a temporary storage destination for data when the calculation unit 51 executes various processes. The nonvolatile memory is, for example, an EEPROM (Electrically Erasable Programmable Read-Only Memory) or a flash memory. The volatile memory is, for example, a RAM (Random Access Memory).

[0022] The calculation unit 51 is capable of executing various processes in accordance with the programs stored in the storage unit 52. The calculation unit 51 executes a position detection process for calculating the rotational position, i.e., the mechanical angle θ, of the rotor 20. The position detection process is executed based on the learning data stored in the storage unit 52.

[0023] The learning data used in the position detection process is acquired by a learning process. In this embodiment, the calculation unit 51 is capable of executing the learning process. However, the calculation unit 51 does not necessarily have to execute the learning process. In this case, learning data acquired by a learning device different from the calculation unit 51 may be stored in the storage unit 52.

[0024] The learning process will be described below using an example in which the calculation unit 51 executes the learning process. As shown in FIG. 2 , when the calculation unit 51 starts the learning process, it first rotates the rotor 20 (step S1). Next, the calculation unit 51 acquires three first detection signals HA1, HA2, and HA3 via the three first magnetic sensors 41 a, 41 b, and 41 c (step S2). As shown in FIG. 3 , the three first detection signals HA1, HA2, and HA3 are digital signals whose levels are inverted every 180° rotation of the first magnet 31 and which have a phase difference of 120° electrical angle from one another. In FIG. 3 , the period from time t1 to time t11 corresponds to one mechanical angle cycle. In the learning process of this embodiment, one mechanical angle cycle corresponds to the learning period. In FIG. 3 , the periods from time t1 to time t2, from time t2 to time t4, from time t4 to time t6, from time t6 to time t8, from time t8 to time t10, and from time t10 to time t11 each correspond to 1 / 6 of one mechanical angle cycle, i.e., 60° mechanical angle.

[0025] Next, the calculation unit 51 acquires three second detection signals Hu, Hv, and Hw using the three second magnetic sensors 42a, 42b, and 42c (step S3). As shown in FIG. 3 , one electrical angle cycle of each of the three second detection signals Hu, Hv, and Hw corresponds to 1 / 5 of one mechanical angle cycle, i.e., 72° mechanical angle. In FIG. 3 , the periods from time t1 to time t3, from time t3 to time t5, from time t5 to time t7, from time t7 to time t9, and from time t9 to time t11 each correspond to 72° mechanical angle. The three second detection signals Hu, Hv, and Hw have a phase difference of 120° electrical angle from one another.

[0026] Next, the calculation unit 51 divides one mechanical angle cycle into a plurality of quadrants based on the three first detection signals HA1, HA2, and HA3 obtained during one mechanical angle cycle corresponding to the learning period (step S4). Each of the plurality of quadrants has a different "N1"-bit digital value, where "N1" is the number of first magnetic sensors 41. In this embodiment, the number of first magnetic sensors 41 is three, so in step S4, the calculation unit 51 divides one mechanical angle cycle into a plurality of quadrants each having a different 3-bit digital value. In this embodiment, of the 3-bit digital value, the most significant bit value is the value of the first detection signal HA1, the middle bit value is the value of the first detection signal HA2, and the least significant bit value is the value of the first detection signal HA3.

[0027] As shown in FIG. 3 , the calculation unit 51 divides one mechanical angle cycle into six quadrants based on the three first detection signals HA1, HA2, and HA3. The calculation unit 51 divides the period from time t1 to time t2 into a first quadrant having a 3-bit digital value "101 (HLH)." The calculation unit 51 divides the period from time t2 to time t4 into a second quadrant having a 3-bit digital value "100 (HLL)." The calculation unit 51 divides the period from time t4 to time t6 into a third quadrant having a 3-bit digital value "110 (HHL)." The calculation unit 51 divides the period from time t6 to time t8 into a fourth quadrant having a 3-bit digital value "010 (LHL)." The calculation unit 51 divides the period from time t8 to time t10 of one mechanical angle cycle into a fifth quadrant having a 3-bit digital value "011 (LHH)." The calculation unit 51 divides the period from time t10 to time t11 of one mechanical angle cycle into a sixth quadrant having a 3-bit digital value "001 (LLH)." The digital value "0" is the value when the first detection signals HA1, HA2, and HA3 are low (L), and the digital value "1" is the value when the first detection signals HA1, HA2, and HA3 are high (H).

[0028] In FIG. 3 , a digital value of “0” is indicated by “L” and a digital value of “1” is indicated by “H.” When the signal strength of the first detection signal HA1 is high (H), the value of the most significant bit of the 3-bit digital value in the quadrant is “1.” When the signal strength of the first detection signal HA1 is low (L), the value of the most significant bit of the 3-bit digital value in the quadrant is “0.” When the signal strength of the first detection signal HA2 is high (H), the value of the middle bit of the 3-bit digital value in the quadrant is “1.” When the signal strength of the first detection signal HA2 is low (L), the value of the middle bit of the 3-bit digital value in the quadrant is “0.” When the signal strength of the first detection signal HA3 is high (H), the value of the least significant bit of the 3-bit digital value in the quadrant is “1.” When the signal strength of the first detection signal HA3 is low (L), the value of the least significant bit of the 3-bit digital value in the quadrant is “0.”

[0029] As described above, a period corresponding to one mechanical angle cycle of the rotor 20 is divided into a plurality of quadrants corresponding to combinations of signal strengths of the three first detection signals HA1, HA2, and HA3. The first quadrant is a quadrant where the signal strength of the first detection signal HA1 is high (H), the signal strength of the first detection signal HA2 is low (L), and the signal strength of the first detection signal HA3 is high (H). The second quadrant is a quadrant where the signal strength of the first detection signal HA1 is high (H), the signal strength of the first detection signal HA2 is low (L), and the signal strength of the first detection signal HA3 is low (L). The third quadrant is a quadrant where the signal strength of the first detection signal HA1 is high (H), the signal strength of the first detection signal HA2 is high (H), and the signal strength of the first detection signal HA3 is low (L). The fourth quadrant is a quadrant where the signal strength of the first detection signal HA1 is low L, the signal strength of the first detection signal HA2 is high H, and the signal strength of the first detection signal HA3 is low L. The fifth quadrant is a quadrant where the signal strength of the first detection signal HA1 is low L, the signal strength of the first detection signal HA2 is high H, and the signal strength of the first detection signal HA3 is high H. The sixth quadrant is a quadrant where the signal strength of the first detection signal HA1 is low L, the signal strength of the first detection signal HA2 is low L, and the signal strength of the first detection signal HA3 is high H.

[0030] 2, the calculation unit 51 then divides one mechanical angle cycle into five pole pair regions associated with pole pair numbers that represent the pole pair positions of the five magnetic pole pairs of the second magnet 32, based on the three second detection signals Hu, Hv, and Hw obtained during one mechanical angle cycle corresponding to the learning period (step S5). In this embodiment, to detect the rotational position of the rotor 20, pole pair numbers that represent the pole pair positions are assigned to the five magnetic pole pairs of the second magnet 32. For example, as shown in FIG. 1, pole pair numbers that represent the pole pair positions are assigned to the five magnetic pole pairs of the second magnet 32 ​​in clockwise order: "0," "1," "2," "3," and "4."

[0031] As shown in FIG. 3 , in step S5, the calculation unit 51 divides one mechanical angle cycle into five pole pair regions based on the three second detection signals Hu, Hv, and Hw obtained during one mechanical angle cycle. The calculation unit 51 divides the period from time t1 to time t3 within one mechanical angle cycle as a pole pair region associated with pole pair number "0." The calculation unit 51 divides the period from time t3 to time t5 within one mechanical angle cycle as a pole pair region associated with pole pair number "1." The calculation unit 51 divides the period from time t5 to time t7 within one mechanical angle cycle as a pole pair region associated with pole pair number "2." The calculation unit 51 divides the period from time t7 to time t9 within one mechanical angle cycle as a pole pair region associated with pole pair number "3." The calculation unit 51 divides the period from time t9 to time t11 in one mechanical angle cycle as a pole pair region associated with pole pair number "4".

[0032] 2, next, the calculation unit 51 divides each pole pair region into a plurality of sections and associates each section with a segment number that indicates the rotational position of the rotor 20 (step S6). As shown in Fig. 4, in step S6, the calculation unit 51 divides each of the five pole pair regions into 12 sections based on the three second detection signals Hu, Hv, and Hw obtained in one mechanical angle cycle, and associates each of the 12 sections with a segment number that indicates the rotational position of the rotor 20.

[0033] The 12 sections included in each of the five pole pair regions are assigned section numbers from "0" to "11." Meanwhile, consecutive numbers throughout one mechanical angle cycle are associated with each section as segment numbers. Specifically, in the pole pair region associated with pole pair number "0," segment numbers "0" to "11" are associated with section numbers "0" to "11." In the pole pair region associated with pole pair number "1," segment numbers "12" to "23" are associated with section numbers "0" to "11." In the pole pair region associated with pole pair number "2," segment numbers "24" to "35" are associated with section numbers "0" to "11." In the pole pair region associated with pole pair number "3," segment numbers "36" to "47" are associated with section numbers "0" to "11." In the pole pair region associated with pole pair number "4", segment numbers "48" to "59" are associated with section numbers "0" to "11".

[0034] The process of dividing each of the five pole pair regions into 12 sections performed by the calculation unit 51 in step S6 will be described in detail below. In FIG. 4 , the reference value of the amplitude is "0." In FIG. 4 , positive digital amplitude values ​​represent, for example, digital values ​​of the magnetic field strength of the north pole. Furthermore, negative digital amplitude values ​​represent, for example, digital values ​​of the magnetic field strength of the south pole. The calculation unit 51 executes a process of extracting zero-crossing points, which are points where the three second detection signals Hu, Hv, and Hw included in each of the five pole pair regions cross the reference value "0." As shown in FIG. 4 , the calculation unit 51 extracts zero-crossing points P1, P3, P5, P7, P9, P11, and P13 for each pole pair region.

[0035] The calculation unit 51 executes a process of extracting intersections, which are points where the three second detection signals Hu, Hv, and Hw included in each of the five pole pair regions intersect with one another. For each pole pair region, the calculation unit 51 extracts intersections P2, P4, P6, P8, P10, and P12 as intersections. The calculation unit 51 executes a process of determining sections between adjacent zero crossing points as sections. The calculation unit 51 determines the section between zero crossing point P1 and intersection point P2 as a section to be assigned section number "0." The calculation unit 51 determines the section between intersection point P2 and zero crossing point P3 as a section to be assigned section number "1." The calculation unit 51 determines the section between zero crossing point P3 and intersection point P4 as a section to be assigned section number "2." The calculation unit 51 determines the section between the intersection point P4 and the zero cross point P5 as a section to be assigned the section number "3." The calculation unit 51 determines the section between the zero cross point P5 and the intersection point P6 as a section to be assigned the section number "4." The calculation unit 51 determines the section between the intersection point P6 and the zero cross point P7 as a section to be assigned the section number "5." The calculation unit 51 determines the section between the zero cross point P7 and the intersection point P8 as a section to be assigned the section number "6." The calculation unit 51 determines the section between the intersection point P8 and the zero cross point P9 as a section to be assigned the section number "7." The calculation unit 51 determines the section between the zero cross point P9 and the intersection point P10 as a section to be assigned the section number "8." The calculation unit 51 determines the section between the intersection point P10 and the zero cross point P11 as a section to be assigned the section number "9." The calculation unit 51 determines the section between the zero cross point P11 and the intersection point P12 as the section to be assigned the section number "10." The calculation unit 51 determines the section between the intersection point P12 and the zero cross point P13 as the section to be assigned the section number "11."

[0036] As described above, a period corresponding to one cycle of the mechanical angle θ of the rotor 20 is divided into a plurality of sections separated by intersections between the waveforms of the three second detection signals Hu, Hv, and Hw and zero-crossing points, which are points where the three second detection signals Hu, Hv, and Hw intersect with a reference value. In the following description, for example, a section assigned section number "0" may be referred to as the "0th section," and a section assigned section number "11" may be referred to as the "11th section," etc.

[0037] As shown in FIG. 2 , the calculation unit 51 then acquires learning data and stores the learning data in the storage unit 52 (step S7). The learning data acquired in step S7 includes data indicating the correspondence between segment numbers associated with sections included in each of the six quadrants and pole pair numbers that indicate pole pair positions. As shown in FIG. 4 , the first quadrant includes 10 sections, from section 0 to section 9. The learning data includes data indicating the correspondence between segment numbers "0" to "9" associated with sections 0 to 9 included in the first quadrant, respectively, and the pole pair number "0."

[0038] The second quadrant includes two sections, section 10 and section 11, and eight sections, section 0 to section 7. The learning data includes data indicating the correspondence between segment numbers "10" and "11" associated with the two sections, section 10 and section 11, included in the second quadrant, and pole pair number "0." The learning data also includes data indicating the correspondence between segment numbers "12" to "19" associated with sections 0 to 7 included in the second quadrant, and pole pair number "1."

[0039] The third quadrant includes four sections, section 8 to section 11, and six sections, section 0 to section 5. The learning data includes data indicating the correspondence between segment numbers "20" to "23", which are linked to sections 8 to 11, respectively, included in the third quadrant, and pole pair number "1". The learning data also includes data indicating the correspondence between segment numbers "24" to "29", which are linked to sections 0 to 5, included in the third quadrant, and pole pair number "2".

[0040] The fourth quadrant includes six sections, section 6 to section 11, and four sections, section 0 to section 3. The training data includes data indicating the correspondence between segment numbers "30" to "35," which are linked to sections 6 to 11, respectively, included in the fourth quadrant, and pole pair number "2." The training data also includes data indicating the correspondence between segment numbers "36" to "39," which are linked to sections 0 to 3, included in the fourth quadrant, and pole pair number "3."

[0041] The fifth quadrant includes eight sections, from section 4 to section 11, and two sections, section 0 and section 1. The learning data includes data indicating the correspondence between segment numbers "40" to "47," which are linked to sections 4 to 11, respectively, included in the fifth quadrant, and pole pair number "3." The learning data also includes data indicating the correspondence between segment numbers "48" and "49," which are linked to sections 0 and 1, which are included in the fifth quadrant, and pole pair number "4."

[0042] The sixth quadrant includes ten sections from section 2 to section 11. The training data includes data indicating the correspondence between segment numbers "50" to "59" associated with sections 2 to 11 included in the sixth quadrant, respectively, and pole pair number "4."

[0043] The learning data includes values ​​of the mechanical angle θ at each zero-crossing point P1, P3, P5, P7, P9, P11, and P13 for each pole pair number, and values ​​of the mechanical angle θ at each intersection point P2, P4, P6, P8, P10, and P12. The learning data also includes normalization coefficients k[i] corresponding to each segment number, as described in Japanese Patent No. 6233532. i is an integer indicating the segment number. The normalization coefficient k[i] is determined based on the slope of the waveform portions of the second detection signals Hu, Hv, and Hw that connect the intersection points located at the start and end points of each segment with the zero-crossing points. In the following description, the waveform portions of the second detection signals Hu, Hv, and Hw that connect the intersection points located at the start and end points of each segment with the zero-crossing points are referred to as "divided signals." In the method described in Japanese Patent No. 6233532, three second detection signals Hu, Hv, and Hw are converted into triangular waves and corrected, and divided signals for each segment of one mechanical angle cycle are extracted from the three corrected second detection signals Hu, Hv, and Hw and connected to each other in a substantially linear manner.The mechanical angle θ is estimated and detected from the relationship between the digital values ​​of the three second detection signals Hu, Hv, and Hw and the mechanical angle θ.The conversion into triangular waves also involves correction to make the amplitudes of the three second detection signals Hu, Hv, and Hw the same.

[0044] FIG. 5 shows an example of three second detection signals Hut, Hvt, and Hwt corrected to triangular waves as described above. The second detection signal Hut represents the second detection signal Hu converted into a triangular wave. The second detection signal Hvt represents the second detection signal Hv converted into a triangular wave. The second detection signal Hwt represents the second detection signal Hw converted into a triangular wave. FIG. 5 shows three second detection signals Hut, Hvt, and Hwt for pole pair number "0." "No." in FIG. 5 represents the section number and segment number.

[0045] In segment number "0," the zero crossing point P1 and the intersection point P2 are connected by a divided signal U2b of the waveform of the second detection signal Hut. In segment number "1," the intersection point P2 and the zero crossing point P3 are connected by a divided signal W1a of the waveform of the second detection signal Hwt. In segment number "2," the zero crossing point P3 and the intersection point P4 are connected by a divided signal W2a of the waveform of the second detection signal Hwt. In segment number "3," the intersection point P4 and the zero crossing point P5 are connected by a divided signal V1b of the waveform of the second detection signal Hvt. In segment number "4," the zero crossing point P5 and the intersection point P6 are connected by a divided signal V2b of the waveform of the second detection signal Hvt. In segment number "5," the intersection point P6 and the zero crossing point P7 are connected by a divided signal U1a of the waveform of the second detection signal Hut. In segment number "6," the zero crossing point P7 and the intersection point P8 are connected by a divided signal U2a of the waveform of the second detection signal Hut. In segment number "7," the intersection point P8 and the zero crossing point P9 are connected by a divided signal W1b of the waveform of the second detection signal Hwt. In segment number "8," the zero crossing point P9 and the intersection point P10 are connected by a divided signal W2b of the waveform of the second detection signal Hwt. In segment number "9," the intersection point P10 and the zero crossing point P11 are connected by a divided signal V1a of the waveform of the second detection signal Hvt. In segment number "10," the zero crossing point P11 and the intersection point P12 are connected by a divided signal V2a of the waveform of the second detection signal Hvt. In segment number "11," the intersection point P12 and the zero crossing point P13 are connected by a divided signal U1b of the waveform of the second detection signal Hut.

[0046] The divided signal U1a is a first portion between an intersection P6 with one of the other two second detection signals Hvt, Hwt and a zero-crossing point P7. The divided signal U2a is a second portion between the zero-crossing point P7 and an intersection P8 with the other of the other two second detection signals Hvt, Hwt. The divided signal U1b is a first portion between an intersection P12 with one of the other two second detection signals Hvt, Hwt and a zero-crossing point P13. The divided signal U2b is a second portion between the zero-crossing point P1 and an intersection P2 with the other of the other two second detection signals Hvt, Hwt.

[0047] The divided signal V1a is a first portion between an intersection P10 with one of the other two second detection signals Hut, Hwt and a zero-crossing point P11. The divided signal V2a is a second portion between the zero-crossing point P11 and a intersection P12 with the other of the other two second detection signals Hut, Hwt. The divided signal V1b is a first portion between an intersection P4 with one of the other two second detection signals Hut, Hwt and a zero-crossing point P5. The divided signal V2b is a second portion between the zero-crossing point P5 and a intersection P6 with the other of the other two second detection signals Hut, Hwt.

[0048] The divided signal W1a is a first portion between an intersection P2 with one of the other two second detection signals Hut, Hvt and a zero-crossing point P3. The divided signal W2a is a second portion between the zero-crossing point P3 and an intersection P4 with the other of the other two second detection signals Hut, Hvt. The divided signal W1b is a first portion between an intersection P8 with one of the other two second detection signals Hut, Hvt and a zero-crossing point P9. The divided signal W2b is a second portion between the zero-crossing point P9 and an intersection P10 with the other of the other two second detection signals Hut, Hvt.

[0049] As described above, each of the three second detection signals Hu output from the three second magnetic sensors 42a, 42b, and 42c has a first portion and a second portion.

[0050] The normalization coefficient k[i] is determined for each segment according to the slope of each divided signal. When the absolute value of the deviation of the digital value from the start point of each segment at the current time is ΔX and the deviation of the mechanical angle θ from the start point of each segment at the current time is Δθ, the normalization coefficient k[i] satisfies the relationship Δθ = k[i] × ΔX.

[0051] Next, the position detection process executed by the calculation unit 51 will be described. As shown in Fig. 6, when the calculation unit 51 starts the position detection process, it first acquires three first detection signals HA1, HA2, and HA3 using the three first magnetic sensors 41a, 41b, and 41c (step S8). Next, the calculation unit 51 acquires three second detection signals Hu, Hv, and Hw using the three second magnetic sensors 42a, 42b, and 42c (step S9).

[0052] Next, the calculation unit 51 executes a first acquisition process to acquire a quadrant number indicating the quadrant based on the three first detection signals HA1, HA2, and HA3 (step S10). In other words, the signal processing in the position detection method of this embodiment includes the first acquisition process. In the first acquisition process (step S10), the calculation unit 51 identifies the current quadrant from among the six quadrants based on the 3-bit digital value represented by the three first detection signals HA1, HA2, and HA3, and acquires the quadrant number. As an example, if the 3-bit digital value is "100," the first detection signal HA1 is high, the first detection signal HA2 is low, and the first detection signal HA3 is low. Therefore, in the first acquisition process, the calculation unit 51 determines that the current mechanical angle θ of the rotor 20 is included in the second quadrant and acquires "2" as the quadrant number.

[0053] Next, the calculation unit 51 executes a second acquisition process to acquire a section number indicating a section based on the three second detection signals Hu, Hv, and Hw (step S11). In other words, the signal processing in the position detection method of this embodiment includes the second acquisition process. In the second acquisition process (step S11), the calculation unit 51 identifies the current section from the 12 sections and acquires the section number based on, for example, the magnitude relationship between the detection values ​​of the three second detection signals Hu, Hv, and Hw and the positive and negative signs of each detection value. As shown in FIG. 4 , for example, in section 2, the detection value of the second detection signal Hu is the largest and has a positive sign. Also, in section 2, the detection value of the second detection signal Hw is the second largest and has a negative sign. Also, in section 2, the detection value of the second detection signal Hv is the smallest and has a negative sign. In the second acquisition process, if the magnitude relationship between the detection values ​​of the three second detection signals Hu, Hv, and Hw and the positive or negative sign of each detection value meet the conditions for section 2 as described above, the calculation unit 51 identifies section 2 as the current section and acquires "2" as the section number.

[0054] As shown in FIG. 6 , the calculation unit 51 then executes a mechanical angle calculation process to calculate information about the mechanical angle θ of the rotor 20 based on the acquired quadrant number and the acquired section number (step S12). That is, the signal processing in the position detection method of this embodiment includes the mechanical angle calculation process. The information about the mechanical angle θ of the rotor 20 obtained in the mechanical angle calculation process (step S12) of this embodiment is an estimated value of the mechanical angle θ of the rotor 20. For example, as described above, assume that "2" is acquired as the current quadrant number and "2" is acquired as the current section number. The learning data includes data indicating the correspondence between segment numbers "12" to "19" associated with sections 0 to 7 included in the second quadrant and pole pair number "1." Therefore, in the mechanical angle calculation process (step S12), when the quadrant number is "2" and the section number is "2", the calculation unit 51 determines that the rotational position of the rotor 20 is at a position included in the pole pair number "1" and at a position included in the segment number "14" corresponding to the second section in the pole pair number "1".

[0055] As described above, the memory unit 52 pre-stores the mechanical angle θ corresponding to the start point and end point of each segment number and the normalization coefficient k[i] corresponding to each segment number. Therefore, the mechanical angle θ at the current time can be calculated by adding the value of the deviation Δθ of the mechanical angle θ calculated from Δθ = k[i] × ΔX to the value of the mechanical angle θ stored for the start point of the segment number corresponding to the rotational position of the rotor 20. A more specific method for calculating the mechanical angle θ using the three second detection signals Hu, Hv, and Hw can be appropriately adopted, as described in Japanese Patent Publication No. 6233532. In this embodiment, by using the three first detection signals HA1, HA2, and HA3 and the three second detection signals Hu, Hv, and Hw, it is possible to determine which segment of one mechanical angle cycle the current rotational position of the rotor 20 is in, as described above. Therefore, the position detection device 100 can detect the rotational position of the rotor 20 even immediately after power is turned on.

[0056] The signal processing unit 50 executes an abnormality detection process to detect abnormalities in the three first detection signals HA1, HA2, and HA3 and the three second detection signals Hu, Hv, and Hw. That is, the signal processing in the position detection method of this embodiment includes the abnormality detection process. In this embodiment, the abnormality detection process is executed by the calculation unit 51. In this embodiment, the abnormality detection process includes a first abnormality determination process, a second abnormality determination process, and a third abnormality determination process.

[0057] The first abnormality determination process is a process for determining that an abnormality exists in the first detection signals HA1, HA2, HA3 when the chronological arrangement of the quadrant numbers acquired in the first acquisition process described above differs from the chronological arrangement of the quadrant numbers under normal conditions. Figure 7 shows the change in the quadrant numbers over time t while the rotor 20 is rotating. As shown in Figure 7, when the rotor 20 is rotating normally, the quadrant numbers acquired by the first acquisition process (step S10) described above change in increasing order by one from "1" to "6." When the quadrant number reaches "6," it returns to "1" and repeats this change in increasing order by one again.

[0058] For example, in abnormal state 1 shown in FIG. 7 , after the quadrant number becomes "3," it should become "4" under normal circumstances, but instead it remains at "3" and the next time it changes to "5." In this case, in the first abnormality determination process, the signal processing unit 50 determines that the chronological order of the quadrant numbers differs from the chronological order of the quadrant numbers under normal circumstances, and determines that an abnormality exists in the first detection signals HA1, HA2, and HA3. Also, in abnormal state 2 shown in FIG. 7 , after the quadrant number becomes "3," it should become "4" under normal circumstances, but instead it does not become "4," and a state occurs in which a quadrant number cannot be obtained, and the next quadrant number becomes "5." In this case, too, in the first abnormality determination process, the signal processing unit 50 determines that the chronological order of the quadrant numbers differs from the chronological order of the quadrant numbers under normal circumstances, and determines that an abnormality exists in the first detection signals HA1, HA2, and HA3. In the examples of abnormalities 1 and 2 shown in FIG. 7 , the quadrant number does not become "4" but moves from "3" to "5," so the signal processing unit 50 determines that there is an abnormality at the point in one mechanical angle cycle where the quadrant number becomes "4."

[0059] 7 , a case where the quadrant number cannot be obtained occurs when, for example, there is no quadrant corresponding to the combination of the digital values ​​of the three first detection signals HA1, HA2, and HA3. Specifically, this occurs when, for example, the 3-bit digital value indicated by the three first detection signals HA1, HA2, and HA3 is "111 (HHH)." In this case, the signal processing unit 50 can detect that an abnormality has occurred in the three first detection signals HA1, HA2, and HA3 even if the rotor 20 is not rotating.

[0060] The second abnormality determination process is a process for determining that an abnormality exists in the second detection signals Hu, Hv, and Hw when the chronological arrangement of the section numbers acquired in the second acquisition process (step S11) described above differs from the chronological arrangement of the section numbers under normal conditions. Figure 8 shows the change in the section numbers over time t while the rotor 20 is rotating. As shown in Figure 8, when the rotor 20 is rotating normally, the section numbers acquired by the second acquisition process change in increasing order by one from "0" to "11," and when they reach "11," they return to "0" and repeat the change in increasing order by one again.

[0061] For example, in the abnormal state shown in Fig. 8 , after the section number becomes "6," it should normally become "7," but instead remains at "6" and the next time it changes to "9." In this case, in the second abnormality determination process, the signal processing unit 50 determines that the chronological arrangement of the section numbers is different from the chronological arrangement of the section numbers in the normal state, and determines that an abnormal portion exists in the second detection signals Hu, Hv, and Hw. In the abnormal state example shown in Fig. 8 , the quadrant number does not become "7" or "8," but instead moves from "6" to "9." Therefore, the signal processing unit 50 determines that an abnormality exists in the portions of one mechanical angle cycle where the section numbers are "7" and "8."

[0062] As described above, according to this embodiment, by comparing the change in the quadrant number with the change in the normal state in the first abnormality determination process, it is possible to detect the location of the quadrant number at which the first detection signals HA1, HA2, and HA3 are abnormal. Furthermore, by comparing the change in the section number with the change in the normal state in the second abnormality determination process, it is possible to detect the location of the section number at which the second detection signals Hu, Hv, and Hw are abnormal. As a result, when an abnormality occurs in the first detection signals HA1, HA2, and HA3 and the second detection signals Hu, Hv, and Hw, it is possible to identify the location of the abnormality and compensate for the calculation of the mechanical angle θ at the abnormal location based on a location of the first detection signals HA1, HA2, and HA3 and the second detection signals Hu, Hv, and Hw that is not abnormal. Therefore, even when an abnormality occurs in the detection signals, it is easy to continue detecting the rotational position of the rotor 20 using the single-system position detection device 100 including the first magnetic sensor 41 and the second magnetic sensor 42, without providing multiple systems of the same circuit for calculating the mechanical angle θ. This improves the redundancy of the rotational position detection of the motor 10 while suppressing an increase in the cost of the position detection device 100. Furthermore, since an abnormality can be detected simply by comparing the chronological order of the detected quadrant numbers and section numbers with the normal state, it is easy to detect an abnormality.

[0063] The third abnormality determination process determines that an abnormality exists in at least one of the first detection signals HA1, HA2, and HA3 and the second detection signals Hu, Hv, and Hw when the difference between the counts obtained by the first count process and the counts obtained by the second count process is equal to or greater than a predetermined number. The first count process increments the count each time it is determined that the rotor 20 has rotated a predetermined angle based on the three first detection signals HA1, HA2, and HA3. The second count process increments the count each time it is determined that the rotor 20 has rotated a predetermined angle based on the three second detection signals Hu, Hv, and Hw. In this embodiment, the predetermined angle is 360°. However, the predetermined angle is not particularly limited and may be any angle.

[0064] The signal processing unit 50 executes the first counting process and the second counting process. In the first counting process, the signal processing unit 50 advances the count and increments the first count number by one each time it determines that the rotor 20 has rotated once based on the three first detection signals HA1, HA2, and HA3. In the second counting process, the signal processing unit 50 advances the count and increments the second count number by one each time it determines that the rotor 20 has rotated once based on the three second detection signals Hu, Hv, and Hw. Therefore, as shown in FIG. 9 , under normal conditions, the first count number and the second count number increase by one at approximately the same timing as time t changes.

[0065] In the third abnormality determination process of this embodiment, the signal processing unit 50 determines that an abnormality exists in at least one of the first detection signals HA1, HA2, and HA3 and the second detection signals Hu, Hv, and Hw when the difference between the first count and the second count is 2 or more. For example, in the abnormal state shown in FIG. 9 , the first count increases to 4, 5, and 6, while the second count remains at 3. In the third abnormality determination process, the signal processing unit 50 determines that an abnormality exists when the first count reaches 5 while the second count remains at 3. In this case, the signal processing unit 50 determines that an abnormality exists in the second detection signals Hu, Hv, and Hw used to count the second count, which is smaller. The third abnormality determination process allows the signal processing unit 50 to detect that an abnormality exists in at least one of the first detection signals HA1, HA2, and HA3 and the second detection signals Hu, Hv, and Hw without comparing changes in the quadrant number and the section number with those during normal operation.

[0066] For example, if the first magnetic sensors 41a, 41b, and 41c completely stop and the first detection signals HA1, HA2, and HA3 are interrupted, the quadrant number is no longer acquired. In this case, an abnormality cannot be determined using the first abnormality determination process described above. Furthermore, if the second magnetic sensors 42a, 42b, and 42c completely stop and the second detection signals Hu, Hv, and Hw are interrupted, the section number is no longer acquired. In this case, an abnormality cannot be determined using the second abnormality determination process described above. Furthermore, if either the quadrant number or the section number remains stationary at a constant value, it is difficult to distinguish between a stopped rotor 20 and an abnormality. Even in these cases, by comparing the first count number with the second count number in the third abnormality determination process, the signal processing unit 50 can detect an abnormality in at least one of the first detection signals HA1, HA2, and HA3 and the second detection signals Hu, Hv, and Hw.

[0067] As described above, in this embodiment, the difference between the first count number and the second count number when the signal processing unit 50 determines that an abnormality has occurred in the third abnormality determination process, i.e., the predetermined number, is 2. The timing at which the first count number and the second count number are counted up may differ due to errors in the detection signals. Therefore, if the predetermined number is 1, there is a risk that the third abnormality determination process will determine that an abnormality has occurred even when no abnormality has occurred. In contrast, by setting the predetermined number to 2 or more, it is possible to prevent the signal processing unit 50 from falsely detecting an abnormality.

[0068] In this embodiment, the signal processing unit 50 executes fail-safe processing when the abnormality detection processing determines that an abnormal portion exists in one of the first detection signals HA1, HA2, and HA3 and the second detection signals Hu, Hv, and Hw. The fail-safe processing includes an estimation processing that estimates information obtained based on the portion determined to be abnormal in the one detection signal under normal conditions based on at least a portion of the first detection signals HA1, HA2, and HA3 and the second detection signals Hu, Hv, and Hw that is not determined to be abnormal. The fail-safe processing also includes a processing that calculates information related to the mechanical angle θ of the rotor 20 based on the information estimated by the estimation processing at the portion determined to be abnormal in the abnormality detection processing. Therefore, even if an abnormal portion exists in one of the first detection signals HA1, HA2, and HA3 and the second detection signals Hu, Hv, and Hw, the mechanical angle θ of the rotor 20 can be calculated at the abnormal portion. As a result, even if an abnormality occurs in one of the first detection signals HA1, HA2, HA3 and the second detection signals Hu, Hv, Hw, it is possible to continue detecting the rotational position of the motor 10. Note that the signal processing unit 50 may calculate the mechanical angle θ of the location determined to be abnormal by processing similar to the mechanical angle calculation processing described above using information estimated by the estimation processing. Alternatively, the signal processing unit 50 may calculate the mechanical angle θ of the location determined to be abnormal by processing different from the mechanical angle calculation processing described above using information estimated by the estimation processing.

[0069] In this embodiment, the fail-safe processing includes a first fail-safe processing and a second fail-safe processing. The first fail-safe processing is processing that is executed when it is determined in the first abnormality determination processing that an abnormal portion exists in the first detection signals HA1, HA2, HA3. The second fail-safe processing is processing that is executed when it is determined in the second abnormality determination processing that an abnormal portion exists in the second detection signals Hu, Hv, Hw.

[0070] The first fail-safe process includes a process of estimating the quadrant number of a first abnormality location determined to be abnormal among the quadrant numbers acquired in the first acquisition process (step S10) described above, based on the order of the first abnormality location in the chronological order of the quadrant numbers acquired in the first acquisition process. Therefore, even if a first abnormality location occurs in the first detection signals HA1, HA2, and HA3, the quadrant number can be acquired at the first abnormality location in the same way as in a normal case. As a result, the signal processing unit 50 can calculate the mechanical angle θ using the quadrant number estimated at the first abnormality location by a process similar to the mechanical angle calculation process described above.

[0071] Specifically, for example, in the case of abnormality states 1 and 2 shown in FIG. 7 , the first abnormality location is located between quadrant number "3" and quadrant number "5." Based on the context of the first abnormality location, i.e., quadrant number "3" and quadrant number "5," the signal processing unit 50 estimates that the quadrant number of the first abnormality location is "4." As a result, even if the first abnormality determination process determines that an abnormality exists in the first detection signals HA1, HA2, and HA3, the signal processing unit 50 can estimate and acquire the normal quadrant number "4" for the first abnormality location determined to be the abnormal location. Therefore, even if an abnormality occurs in the first detection signals HA1, HA2, and HA3, the signal processing unit 50 can perform the mechanical angle calculation process using the estimated quadrant number at the first abnormality location where the abnormality occurred, and can calculate the mechanical angle θ of the rotor 20.

[0072] When the signal processing unit 50 determines through the first abnormality determination process that there is a first abnormality location in the quadrant number arrangement, the signal processing unit 50 estimates the quadrant number of the first abnormality location through the first fail-safe process when the rotational position of the rotor 20 next or later reaches the first abnormality location, and performs the mechanical angle calculation process based on the estimated quadrant number. Specifically, when the signal processing unit 50 determines that the quadrant before the first abnormality location has ended based on the three second detection signals Hu, Hv, and Hw, the signal processing unit 50 sets the quadrant number of the next quadrant to the quadrant number estimated through the first fail-safe process, rather than the quadrant number derived from the three first detection signals HA1, HA2, and HA3, and performs the mechanical angle calculation process using the estimated quadrant number. Furthermore, when the signal processing unit 50 determines that the quadrant after the first abnormality location has begun based on the three second detection signals Hu, Hv, and Hw, the signal processing unit 50 returns the method of acquiring the quadrant number of the next quadrant to the method of acquiring the quadrant number through the first acquisition process based on the three first detection signals HA1, HA2, and HA3.

[0073] 7 , when the quadrant with quadrant number "4" is the first abnormality location, if the signal processing unit 50 determines that the quadrant with quadrant number "3" has ended based on the three second detection signals Hu, Hv, and Hw, the number to be used as the next quadrant number is the quadrant number "4" estimated by the first fail-safe processing. In this case, if the signal processing unit 50 determines that the quadrant with quadrant number "5" has begun, the method of obtaining the next quadrant number is returned to the method of obtaining the next quadrant number based on the three first detection signals HA1, HA2, and HA3.

[0074] The determination of the end of the quadrant preceding the quadrant containing the first abnormality location and the start of the quadrant following the quadrant containing the first abnormality location are made by determining whether the mechanical angle θ calculated in the mechanical angle calculation process is the same as the mechanical angle θ at the boundary point between the quadrant preceding and following the quadrant containing the first abnormality location, among the intersections and zero-crossing points of the second detection signals Hu, Hv, and Hw stored in the memory unit 52. For example, the boundary point between the third and fourth quadrants is zero-crossing point P7 for pole pair number "2." The signal processing unit 50 determines that the third quadrant has ended when the mechanical angle θ calculated in the mechanical angle calculation process becomes equal to the value of the mechanical angle θ stored for zero-crossing point P7 for pole pair number "2." For example, the boundary point between the fourth and fifth quadrants is zero-crossing point P5 for pole pair number "3." The signal processing unit 50 determines that the fourth quadrant ends and the fifth quadrant begins when the mechanical angle θ calculated by the mechanical angle calculation process becomes the value of the mechanical angle θ stored for the zero-cross point P5 at pole pair number "3."

[0075] The second fail-safe process includes a process of determining which quadrant number includes a second abnormality location determined to be abnormal among the section numbers acquired in the second acquisition process (step S11) described above, and calculating information about the mechanical angle θ of the rotor 20 corresponding to the period of the second abnormality location based on information about the mechanical angle θ of the rotor that is predetermined for the period of the quadrant number that the second abnormality location is included in. Therefore, even if a second abnormality location occurs in the second detection signals Hu, Hv, Hw, the signal processing unit 50 can accurately calculate the mechanical angle θ of the rotor at the second abnormality location.

[0076] The "process of determining which quadrant number contains the second abnormal location determined to be abnormal among the section numbers, and calculating information regarding the mechanical angle θ of the rotor 20 corresponding to the period of the second abnormal location based on information regarding the mechanical angle θ of the rotor that is predetermined for the period of the quadrant number containing the second abnormal location" is a process that includes an estimation process in the fail-safe process and a process of calculating information regarding the mechanical angle θ of the rotor 20 based on the information estimated by the estimation process.

[0077] Specifically, for example, in the case of the abnormality shown in FIG. 8 , the second abnormality locations are the locations with section numbers "7" and "8." In the second fail-safe processing, the signal processing unit 50 determines in which quadrant number the second abnormality locations are included, based on the quadrant numbers acquired based on the first detection signals HA1, HA2, and HA3, for the section numbers "7" and "8" that are the second abnormality locations. For example, if the section numbers "7" and "8" that are the second abnormality locations are included in quadrant number "4," in the second fail-safe processing, the signal processing unit 50 calculates information about the mechanical angle θ of the rotor 20 that corresponds to the section numbers "7" and "8" that are the second abnormality locations, based on information about the mechanical angle θ of the rotor 20 that is predetermined for the period of quadrant number "4," i.e., the fourth quadrant. In this embodiment, the fourth quadrant is the period from the zero-crossing point P7 of pole pair number "2" to the zero-crossing point P5 of pole pair number "3." Therefore, the information on the mechanical angle θ of the rotor 20 predetermined for the fourth quadrant includes angle information from the mechanical angle θ stored corresponding to the zero-crossing point P7 of pole pair number "2" to the mechanical angle θ stored corresponding to the zero-crossing point P5 of pole pair number "3." In the second fail-safe processing, the signal processing unit 50 calculates the mechanical angle θ in section numbers "7" and "8," which are the second abnormality locations, based on the angle information. Note that "calculating information on the mechanical angle θ of the rotor 20 corresponding to the period of the second abnormality location based on information on the mechanical angle θ of the rotor predetermined for the period of the quadrant number including the second abnormality location" simply means calculating information on the mechanical angle θ of the rotor 20 corresponding to the period of the second abnormality location based on at least a part of information on the mechanical angle θ of the rotor predetermined for the period of the quadrant number including the second abnormality location.

[0078] In this embodiment, if the signal processing unit 50 determines through the second abnormality determination process that there is a second abnormality location in the arrangement of section numbers that is abnormal, the signal processing unit 50 calculates the mechanical angle θ at the second abnormality location through the second fail-safe process when the rotational position of the rotor 20 becomes the second abnormality location next time or later. The signal processing unit 50 calculates the mechanical angle θ in the second fail-safe process when it determines that the section number that becomes the second abnormality location has started, in the same way as when the first abnormality location described above has occurred. If the second abnormality location is section number "7" or "8," the signal processing unit 50 starts calculating the mechanical angle θ through the second fail-safe process when it determines that the previous section number "6" has ended, that is, when the section number becomes the second abnormality location.

[0079] In the second fail-safe processing, the signal processing unit 50 calculates the mechanical angle θ of the rotor 20 based on the angle information previously determined for the period of the quadrant number including the second abnormal location, the time elapsed since the section number became the second abnormal location, and the rotational speed of the rotor 20. In other words, in this embodiment, the second fail-safe processing includes a process of calculating information about the mechanical angle θ of the rotor 20 corresponding to the period of the second abnormal location based on the information about the mechanical angle θ of the rotor previously determined for the period of the quadrant number including the second abnormal location, the time elapsed since the section number became the second abnormal location, and the rotational speed of the rotor 20. Therefore, the second fail-safe processing enables the signal processing unit 50 to accurately and easily calculate the mechanical angle θ at the second abnormal location. Note that the method for detecting the rotational speed of the rotor 20 and the method for measuring the time elapsed since the section number became the second abnormal location are not particularly limited.

[0080] The "process of calculating information relating to the mechanical angle θ of the rotor 20 corresponding to the period of the second abnormality location based on information on the mechanical angle θ of the rotor predetermined for the period of the quadrant number that includes the second abnormality location, the time that has elapsed since the section number became the second abnormality location, and the rotational speed of the rotor 20" is a process that includes an estimation process in the fail-safe process and a process of calculating information relating to the mechanical angle θ of the rotor 20 based on the information estimated by the estimation process.

[0081] For example, if the second abnormal location is section number "7" or "8," in the second fail-safe processing, the signal processing unit 50 reads the mechanical angle θ stored at the time when section number became "7," i.e., corresponding to the intersection P8 between section number "6" and section number "7." The signal processing unit 50 calculates the mechanical angle θ of the rotor 20 at the second abnormal location by adding a value obtained by multiplying the time elapsed since section number became "7" by the rotational speed of the rotor 20 to the read mechanical angle θ. When the signal processing unit 50 determines that the section number that becomes the second abnormal location has ended, in the same way as when the first abnormal location described above has occurred, it ends the calculation of the mechanical angle θ in the second fail-safe processing and restarts the calculation of the mechanical angle θ by the normal mechanical angle calculation processing.

[0082] In the second fail-safe processing, the signal processing unit 50 may calculate the mechanical angle θ of the rotor 20 based on the angle information predetermined for the period of the quadrant number including the second abnormality location, the time elapsed since the quadrant number became the quadrant number including the second abnormality location, and the rotational speed of the rotor 20. In other words, the second fail-safe processing may include processing for calculating information about the mechanical angle θ of the rotor 20 corresponding to the period of the second abnormality location based on the information about the mechanical angle θ of the rotor 20 predetermined for the period of the quadrant number including the second abnormality location, the time elapsed since the quadrant number became the quadrant number including the second abnormality location, and the rotational speed of the rotor 20. Even in this case, the signal processing unit 50 can accurately and easily calculate the mechanical angle θ at the second abnormality location by the second fail-safe processing. In this case, the signal processing unit 50 reads the mechanical angle θ stored for the intersection or zero-crossing point where the quadrant number including the second abnormality location starts. The signal processing unit 50 calculates the mechanical angle θ of the rotor 20 for the entire quadrant of the quadrant number including the second abnormality location by adding to the mechanical angle θ a value obtained by multiplying the time elapsed since the quadrant number was reached by the rotational speed of the rotor 20. In this case, when the signal processing unit 50 determines that the quadrant number including the second abnormality location has ended, it ends the calculation of the mechanical angle θ by the second fail-safe processing and restarts the calculation of the mechanical angle θ by the normal mechanical angle calculation processing.

[0083] The signal processing unit 50 executes the above-described abnormality detection processing and fail-safe processing, for example, as shown in the flowchart of FIG. 10 . As shown in FIG. 10 , when the signal processing unit 50 starts the position detection processing (step S13), it executes a third abnormality determination processing to determine whether the difference between the first count number and the second count number is smaller than a predetermined number (step S14). If the third abnormality determination processing (step S14) determines that the difference between the count numbers is equal to or greater than the predetermined number (step S14: NO), the signal processing unit 50 stops using the detection signal in which the abnormality occurred (step S17). In step S17, the signal processing unit 50 compares the magnitude relationship between the first count number and the second count number to determine whether the abnormality occurred in the first detection signal HA1, HA2, HA3 or the second detection signal Hu, Hv, Hw. In step S17, the signal processing unit 50 determines that the abnormality occurred in the detection signal for counting the smaller of the first count number and the second count number, and stops using the detection signal. The signal processing unit 50 continues the position detection process when it determines that the position of the rotor 20 can be detected only by the detection signal different from the detection signal that has been stopped from being used, whereas the signal processing unit 50 stops the position detection process when it determines that the position of the rotor 20 cannot be detected only by the detection signal different from the detection signal that has been stopped from being used.

[0084] If the signal processor 50 determines in the third abnormality determination process (step S14) that the difference in the counts is smaller than a predetermined number (step S14: YES), it executes a first abnormality determination process to determine whether the chronological arrangement of the quadrant numbers is normal (step S15).If the signal processor 50 determines in the first abnormality determination process (step S15) that the chronological arrangement of the quadrant numbers is abnormal (step S15: NO), it executes a first fail-safe process (step S18).

[0085] If the first abnormality determination process (step S15) determines that the chronological arrangement of the quadrant numbers is normal (step S15: YES), the signal processing unit 50 executes a second abnormality determination process to determine whether the chronological arrangement of the section numbers is normal (step S16). If the second abnormality determination process (step S16) determines that the chronological arrangement of the section numbers is abnormal (step S16: NO), the signal processing unit 50 executes a second fail-safe process (step S19). If the second abnormality determination process (step S16) determines that the chronological arrangement of the section numbers is normal (step S16: YES), the signal processing unit 50 continues the position detection process as is.

[0086] In this embodiment, the signal processing unit 50 executes output processing. The output processing is processing in which information related to the mechanical angle θ of the rotor 20 calculated by the mechanical angle calculation processing described above is converted into different signals and output to the outside. The signals output by the output processing are output to, for example, a control device that controls the motor 10. In the output processing, the signal processing unit 50 converts the mechanical angle θ calculated in the mechanical angle calculation processing into U-phase, V-phase, and W-phase signals or A-phase, B-phase, and Z-phase signals and outputs them.

[0087] FIG. 11 shows an example of a U-phase signal PU, a V-phase signal PV, and a W-phase signal PW. As shown in FIG. 11 , the U-phase signal PU, the V-phase signal PV, and the W-phase signal PW are rectangular wave pulse signals that are out of phase with each other. In this embodiment, the U-phase signal PU, the V-phase signal PV, and the W-phase signal PW are out of phase with each other by 120° electrical angle. The U-phase signal PU, the V-phase signal PV, and the W-phase signal PW are rectification signals used to rectify the current supplied to the motor 10 and correspond to "first phase signals." A control device to which the U-phase signal PU, the V-phase signal PV, and the W-phase signal PW are input supplies three-phase AC currents, i.e., U-phase current, V-phase current, and W-phase current, to the motor 10 based on the U-phase signal PU, the V-phase signal PV, and the W-phase signal PW. In the following description, the U-phase signal PU, the V-phase signal PV, and the W-phase signal PW will be collectively referred to as UVW signals.

[0088] FIG. 12 shows an example of an A-phase signal PA, a B-phase signal PB, and a Z-phase signal PZ. As shown in FIG. 12, the A-phase signal PA, the B-phase signal PB, and the Z-phase signal PZ are rectangular wave pulse signals. The A-phase signal PA and the B-phase signal PB have a phase difference of a predetermined value. In this embodiment, the predetermined value is 90° in electrical angle. The Z-phase signal PZ is a pulse signal output each time the rotor 20 rotates once. The A-phase signal PA, the B-phase signal PB, and the Z-phase signal PZ correspond to the A-phase, B-phase, and Z-phase incremental signals output from the rotary encoder, respectively, and are equivalent to "second phase signals." In the following description, the A-phase signal PA, the B-phase signal PB, and the Z-phase signal PZ are collectively referred to as ABZ signals.

[0089] 13 , in the output processing of this embodiment, the signal processing unit 50 outputs UVW signals as output signals when the motor 10 is powered on. In other words, the output processing includes, when the rotor 20 starts to rotate, generating UVW signals used to rectify the current supplied to the motor 10 based on information related to the mechanical angle θ of the rotor 20 calculated in the mechanical angle calculation processing, and outputting the UVW signals as output signals.

[0090] As shown in the normal state in FIG. 13 , in the output process, if no abnormality is detected in the abnormality detection process from the start of rotation of the rotor 20 until the predetermined time ta has elapsed, the signal processing unit 50 switches the output signal from the UVW signal to the ABZ signal. That is, if no abnormality is detected in the abnormality detection process from the start of rotation of the rotor 20 until the predetermined time ta has elapsed, the output process includes generating A-phase, B-phase, and Z-phase signals, i.e., the ABZ signal, based on information about the mechanical angle θ of the rotor 20 calculated in the mechanical angle calculation process and outputting the ABZ signal as the output signal. This allows for a switch in the output signal from the UVW signal to the ABZ signal after the predetermined time ta. Furthermore, if an abnormality is present in the three first detection signals HA1, HA2, and HA3 and the three second detection signals Hu, Hv, and Hw, the information about the mechanical angle θ of the rotor 20 calculated in the mechanical angle calculation process is likely to have a larger error than in a normal state. In the case of the ABZ signal, the mechanical angle θ is obtained by counting the number of pulses in the A and B phases. However, if the ABZ signal is calculated based on information with a large error, an abnormality will occur in the number of pulses in the A and B phases. As a result, an error will occur in the obtained mechanical angle θ by the number of abnormal pulses. In particular, if the pulse output width of the ABZ signal is shortened to increase the resolution, the number of pulses in the A and B phases will be easily affected by the magnitude of the error, and the error in the obtained mechanical angle θ will also likely increase. Therefore, if no abnormality is detected in the abnormality detection process between the start of rotation of the rotor 20 and the elapse of a predetermined time ta, the ABZ signal is output as an output signal. This prevents the output of an ABZ signal with an abnormal number of pulses and prevents the output of information on the mechanical angle θ with a large error. The length of the predetermined time ta is not particularly limited.

[0091] As shown in the abnormality case in FIG. 13 , if an abnormality is detected in the abnormality detection process described above between the start of rotation of the rotor 20 and the elapse of a predetermined time ta, the signal processing unit 50 maintains the UVW signal as the output signal even after the predetermined time ta has elapsed. That is, the output process includes outputting the UVW signal as the output signal without changing it to the ABZ signal if an abnormality is detected in the abnormality detection process between the start of rotation of the rotor 20 and the elapse of the predetermined time ta. The UVW signal has a smaller number of pulses output per one rotation of the rotor 20 than the ABZ signal. Therefore, even if an abnormality exists in the three first detection signals HA1, HA2, and HA3 and the three second detection signals Hu, Hv, and Hw, the UVW signal generated based on information about the mechanical angle θ calculated in the mechanical angle calculation process is less likely to be an abnormal signal than the ABZ signal. Therefore, if an abnormality is detected by the abnormality detection process, the UVW signal is continued to be output instead of the ABZ signal, thereby reducing the effect of the output signal on the processing of the higher-level device to which it is input.

[0092] Second Embodiment In this embodiment, the fail-safe processing includes a third fail-safe processing. In this embodiment, the signal processing unit 50 executes the third fail-safe processing instead of the second fail-safe processing described in the first embodiment. The third fail-safe processing is executed when it is determined in the second abnormality determination processing that an abnormal portion exists in some of the three second detection signals Hu, Hv, and Hw.

[0093] The third fail-safe process includes a process of estimating information about the mechanical angle θ of the rotor 20, which is acquired based on some of the second detection signals determined to contain an abnormal portion under normal conditions, based on the other second detection signals determined not to contain an abnormal portion. Therefore, it is easy to accurately estimate information about the mechanical angle θ of the rotor 20 by using a normal second detection signal out of the three second detection signals Hu, Hv, and Hw instead of the second detection signal in which an abnormality has occurred.

[0094] For example, a case will be described in which sections "7" and "8" are determined to be second abnormal locations by the second abnormality determination process. As shown in FIG. 5 , in sections "7" and "8," if the sections are normal, the mechanical angle θ is calculated based on the divided signals W1b and W2b of the second detection signal Hwt converted into a triangular wave. Therefore, if the signal processing unit 50 determines that an abnormality has occurred in sections "7" and "8" in the second abnormality determination process, it determines that the abnormality has occurred in the second detection signal Hw of the three second detection signals Hu, Hv, and Hw. In this case, the signal processing unit 50 estimates the mechanical angle θ in sections "7" and "8" based on the two second detection signals Hu and Hv that are not determined to be abnormal. In this embodiment, the signal processing unit 50 estimates the mechanical angle θ in sections "7" and "8" using the digital values ​​of the portions of the two second detection signals Hu and Hv converted into triangular waves that are located at section numbers "7" and "8." That is, in this embodiment, the third fail-safe process includes estimating information about the mechanical angle θ of the rotor 20, which is acquired based on a portion of the second detection signals Hu determined to contain an abnormality, based on the other second detection signals Hvt and Hwt that have been converted into triangular waves. In the second detection signals Hut, Hvt, and Hwt converted into triangular waves, the absolute values ​​of the waveform slopes of the second detection signals Hut, Hvt, and Hwt in each section are close to each other. Therefore, the time variations of the absolute values ​​of the digital values ​​of the second detection signals Hut, Hvt, and Hwt are close to each other. Therefore, the mechanical angle θ can be accurately estimated by calculating the mechanical angle θ from the above-described relationship Δθ = k[i] × ΔX using the digital values ​​of the other second detection signals Hut, Hvt, and Hwt and the normalization coefficient k[i] corresponding to the section determined to contain an abnormality.

[0095] The second detection signal Hwt located in section number "7" is the divided signal W1b. The divided signal W1b is a first portion between the intersection P8 with the second detection signal Hut and the zero-crossing point P9. In the third fail-safe processing, the signal processing unit 50 estimates the mechanical angle θ using the third portion U3 located in section number "7" of the waveform of the second detection signal Hut, instead of the divided signal W1b, which is the first portion. Specifically, in the third fail-safe processing, the signal processing unit 50 estimates the mechanical angle θ in section number "7" from the relationship Δθ = k[i] × ΔX described above, using the digital value of the third portion U3 and the normalization coefficient k[i] stored corresponding to the segment number of section number "7."

[0096] The second detection signal Hw located in section number "8" is the divided signal W2b. The divided signal W2b is the second portion between the zero-crossing point P9 and the intersection point P10 with the other second detection signal Hvt. In the third fail-safe processing, the signal processing unit 50 estimates the mechanical angle θ based on the third portion V3 located in section number "8" of the waveform of the second detection signal Hvt, instead of the divided signal W2b, which is the second portion. Specifically, in the third fail-safe processing, the signal processing unit 50 estimates the mechanical angle θ in section number "8" from the relationship Δθ = k[i] × ΔX described above, using the digital value of the third portion V3 and the normalization coefficient k[i] stored corresponding to the segment number of section number "8."

[0097] As described above, in this embodiment, when it is determined that there is an abnormality in one second detection signal Hwt, the third fail-safe processing includes estimating information regarding the mechanical angle θ of the rotor 20, which is obtained under normal conditions based on the divided signal W1b corresponding to the first portion of one second detection signal Hwt, based on one second detection signal Hut that intersects with the first portion, the divided signal W1b, at intersection P8, and estimating information regarding the mechanical angle θ of the rotor 20, which is obtained under normal conditions based on the divided signal W2b corresponding to the second portion of one second detection signal Hwt, based on the other second detection signal Hvt that intersects with the second portion, the divided signal W2b, at intersection P10.

[0098] Here, even in the second detection signals Hut, Hvt, and Hwt converted into triangular waves, the waveforms at and near the peaks of the waveform amplitude are more curved than the portions near the zero-crossing points where the signals intersect with the reference value. Therefore, for example, the third portion U3 of the second detection signal Hut, which intersects with the divided signal W1b used to calculate the mechanical angle θ at intersection P8 in section number "7," is closer to a straight line than the other portions of the second detection signal Hvt that do not intersect with the divided signal W1b in section number "7." Therefore, by using the digital value of the third portion U3 of the second detection signal Hut instead of the divided signal W1b corresponding to the first portion of the second detection signal Hwt determined to have an abnormality, the mechanical angle θ can be more accurately estimated based on the relationship Δθ = k[i] × ΔX. Furthermore, for example, the third portion V3 of the second detection signal Hvt, which intersects with the divided signal W2b used to calculate the mechanical angle θ at the intersection P10 in section number "8," is closer to a straight line than other portions of the second detection signal Hut that do not intersect with the divided signal W2b in section number "8." As a result, by using the digital value of the third portion V3 of the second detection signal Hvt instead of the divided signal W2b corresponding to the second portion of the second detection signal Hwt in which it has been determined that an abnormality has occurred, it is possible to more accurately estimate the mechanical angle θ based on the relationship Δθ = k[i] × ΔX.

[0099] The signal processing unit 50 of this embodiment executes the abnormality detection process and the fail-safe process, for example, as shown in the flowchart of Fig. 14. The flowchart shown in Fig. 14 is the same as the flowchart shown in Fig. 10 except that step S19 is replaced with step S20. As shown in Fig. 14, if it is determined in the second abnormality determination process (step S16) that there is an abnormality in the chronological arrangement of the section numbers (step S16: NO), the signal processing unit 50 executes the third fail-safe process described above (step S20).

[0100] Other configurations and methods in this embodiment are similar to those in the first embodiment. The third fail-safe process in this embodiment may be executed when an abnormality occurs in two of the three second detection signals Hu, Hv, and Hw. In this case, the signal processing unit 50 estimates the mechanical angle θ in each section based on the relationship Δθ = k[i] × ΔX using the digital value of the remaining normal divided signal instead of the divided signals in the two abnormal second detection signals.

[0101] The present invention is not limited to the above-described embodiments, and other configurations and methods may be adopted within the scope of the technical concept of the present invention. The first magnetic sensor may be any magnetic sensor. The first magnetic sensor may be a magnetic sensor that outputs an analog signal as the first detection signal. In this case, the multiple quadrants may be divided, for example, based on combinations of whether the signal strength of the first detection signal is greater or smaller than a predetermined value. The multiple quadrants may be divided in any manner as long as they correspond to combinations of signal strengths of the first detection signal. The second magnetic sensor may be any magnetic sensor. The second magnetic sensor may be a magnetic sensor that outputs a digital signal as the second detection signal. The second magnet may be a separate component from the rotor magnet. In this case, the number of magnetic pole pairs of the second magnet may be different from the number of magnetic pole pairs of the rotor magnet.

[0102] The mechanical angle calculation process may be performed based on at least one of the quadrant number and the section number. In other words, the mechanical angle calculation process may be performed based on only one of the quadrant number and the section number. For example, in the above-described embodiment, when the first detection signals HA1, HA2, and HA3 are interrupted, the signal processing unit 50 may perform the mechanical angle calculation process based only on the second detection signals Hu, Hv, and Hw. The motor whose rotor rotational position is detected by the position detection device may be any motor.

[0103] The present technology can be configured as follows: (1) a signal processing unit that processes N1 first detection signals output from the N1 first magnetic sensors and N2 second detection signals output from the N2 second magnetic sensors, wherein a period corresponding to one period in mechanical angle of the rotor is divided into a plurality of quadrants corresponding to combinations of signal strengths of the N1 first detection signals, and the period corresponding to one period in mechanical angle of the rotor is divided into a plurality of quadrants corresponding to combinations of signal strengths of the N1 first detection signals, and wherein the period corresponding to one period in mechanical angle of the rotor is divided into a plurality of quadrants corresponding to combinations of signal strengths of the N1 first detection signals and zero-crossing points that are points where waveforms of the N2 second detection signals intersect with each other and where the N2 second detection signals intersect with a reference value, the signal processing unit executes a first acquisition process to acquire quadrant numbers indicating the quadrants based on N1 of the first detection signals; a second acquisition process to acquire section numbers indicating the sections based on N2 of the second detection signals; a mechanical angle calculation process to calculate information about a mechanical angle of the rotor based on at least one of the quadrant numbers and the section numbers; and an abnormality detection process to detect abnormalities in the first detection signals and the second detection signals, wherein the abnormality detection process includes a first abnormality determination process to determine that an abnormal portion exists in the first detection signal if a chronological arrangement of the quadrant numbers acquired in the first acquisition process differs from a chronological arrangement of the quadrant numbers in a normal state, and a second abnormality determination process to determine that an abnormal portion exists in the second detection signal if the chronological arrangement of the section numbers acquired in the second acquisition process differs from a chronological arrangement of the section numbers in a normal state.(2) The position detection device according to (1), wherein the signal processing unit executes a first counting process that advances a count each time it is determined that the rotor has rotated a predetermined angle based on N1 of the first detection signals, and a second counting process that advances a count each time it is determined that the rotor has rotated the predetermined angle based on N2 of the second detection signals, and the abnormality detection process includes a third abnormality determination process that determines that an abnormality exists in at least one of the first detection signals and the second detection signals when a difference between the count number acquired by the first counting process and the count number acquired by the second counting process is equal to or greater than a predetermined number. (3) The position detection device according to (1) or (2), wherein the signal processing unit executes a fail-safe process when it is determined in the abnormality detection process that an abnormal portion exists in one of the first detection signal and the second detection signal, and the fail-safe process includes an estimation process that estimates information obtained based on a portion determined to be abnormal in the one detection signal under normal conditions based on at least a part of a portion of the first detection signal and the second detection signal that is not determined to be abnormal, and a process that calculates information about the mechanical angle of the rotor based on the information estimated by the estimation process at the portion determined to be abnormal. (4) The position detection device according to (3), wherein the fail-safe process includes a first fail-safe process that is executed when it is determined in the first abnormality determination process that an abnormal portion exists in the first detection signal, and the first fail-safe process includes a process that estimates the quadrant number of a first abnormal portion determined to be abnormal among the quadrant numbers acquired in the first acquisition process based on a chronological relationship of the first abnormal portion in a chronological order of the quadrant numbers acquired in the first acquisition process.(5) The position detection device according to (3) or (4), wherein the fail-safe processing includes a second fail-safe processing executed when it is determined in the second abnormality determination processing that an abnormal portion exists in the second detection signal, and the second fail-safe processing includes a process of determining which quadrant number includes a second abnormal portion determined to be abnormal among the section numbers acquired in the second acquisition processing, and calculating information on the mechanical angle of the rotor corresponding to a period of the second abnormal portion based on information on the mechanical angle of the rotor predetermined for the period of the quadrant number including the second abnormal portion. (6) The position detection device according to (5), wherein the second fail-safe processing includes a process of calculating information on the mechanical angle of the rotor corresponding to the period of the second abnormal portion based on information on the mechanical angle of the rotor predetermined for the period of the quadrant number including the second abnormal portion, the time elapsed since the section number became the second abnormal portion or the quadrant number became the quadrant number including the second abnormal portion, and the rotational speed of the rotor. (7) The position detection device according to (3) or (4), wherein the fail-safe processing includes a third fail-safe processing executed when it is determined in the second abnormality determination processing that an abnormal portion exists in some of the N2 second detection signals, and the third fail-safe processing includes processing for estimating information about the mechanical angle of the rotor, which is acquired based on the some of the second detection signals in a normal state, based on the other second detection signals that are not determined to have an abnormal portion. (8) The position detection device according to (7), wherein the third fail-safe processing includes processing for estimating information about the mechanical angle of the rotor, which is acquired based on the some of the second detection signals, based on the other second detection signals that have been subjected to processing for conversion into a triangular wave.(9) The position detection device according to (7) or (8), wherein the number of the second magnetic sensors is three, and each of the three second detection signals output from the three second magnetic sensors has a first portion between the intersection with one of the other two second detection signals and the zero-cross point, and a second portion between the zero-cross point and the intersection with the other of the other two second detection signals, and the third fail-safe processing includes, when it is determined that one of the second detection signals has an abnormality, estimating, based on the one second detection signal, information about the mechanical angle of the rotor that is normally obtained based on the first portion of the one second detection signal, and estimating, based on the other second detection signal, information about the mechanical angle of the rotor that is normally obtained based on the second portion of the one second detection signal. (10) The position detection device according to any one of (1) to (9), wherein the signal processing unit executes an output process that outputs an output signal, and the output process includes: when the rotor starts to rotate, generating a first phase signal used to rectify a current supplied to the motor based on information related to the mechanical angle of the rotor calculated in the mechanical angle calculation process, and outputting the first phase signal as the output signal; and when no abnormality is detected by the abnormality detection process from the time the rotor starts to rotate until a predetermined time has elapsed, generating second phase signals of A phase, B phase, and Z phase based on information related to the mechanical angle of the rotor calculated in the mechanical angle calculation process, and outputting the second phase signal as the output signal.(11) A position detection method for detecting a rotational position of a rotor in a motor, the method including signal processing for processing N1 first detection signals output from N1 (N1 is an integer of 2 or more) first magnetic sensors facing a first magnet and N2 second detection signals output from N2 (N2 is an integer of 3 or more) second magnetic sensors facing a second magnet, wherein the first magnet has one magnetic pole pair and rotates together with the rotor, the second magnet has P (P is an integer of 2 or more) magnetic pole pairs and rotates together with the rotor, the N1 first magnetic sensors are arranged at intervals in the rotation direction of the first magnet, and the N2 second magnetic sensors are arranged at intervals in the rotation direction of the second magnet, a period corresponding to one mechanical angle period of the rotor is divided into a plurality of quadrants corresponding to combinations of signal strengths of the N1 first detection signals, and the period corresponding to one mechanical angle period of the rotor is divided into a plurality of quadrants corresponding to combinations of signal strengths of the N1 first detection signals, and zero-crossing points which are points where waveforms of the N2 second detection signals intersect with a reference value. and the signal processing includes a first acquisition process that acquires quadrant numbers indicating the quadrants based on N1 of the first detection signals; a second acquisition process that acquires section numbers indicating the sections based on N2 of the second detection signals; a mechanical angle calculation process that calculates information related to a mechanical angle of the rotor based on at least one of the quadrant numbers and the section numbers; and an abnormality detection process that detects abnormalities in the first detection signals and the second detection signals, and the abnormality detection process includes a first abnormality determination process that determines that an abnormal portion exists in the first detection signal when a chronological order of the quadrant numbers acquired in the first acquisition process differs from a chronological order of the quadrant numbers in a normal state, and a second abnormality determination process that determines that an abnormal portion exists in the second detection signal when the chronological order of the section numbers acquired in the second acquisition process differs from a chronological order of the section numbers in a normal state.

[0104] The configurations and methods described in this specification can be combined as appropriate within the scope of not being mutually contradictory.

[0105] REFERENCE SIGNS LIST 10...motor, 20...rotor, 31...first magnet, 32...second magnet, 41, 41a, 41b, 41c...first magnetic sensor, 42, 42a, 42b, 42c...second magnetic sensor, 50...signal processing unit, 100...position detection device, HA1, HA2, HA3...first detection signal, Hu, Hut, Hv, Hvt, Hw, Hwt...second detection signal, P1, P3, P5, P7, P9, P11, P13...zero cross point, ta...predetermined time, U1a, U1b, V1a, V1b, W1a, W1b...divided signal (first part), U2a, U2b, V2a, V2b, W2a, W2b...divided signal (second part), θ...mechanical angle

Claims

1. A position detection device for detecting the rotational position of a rotor in a motor, comprising: a first magnet having one magnetic pole pair and rotating together with the rotor; a second magnet having P (P is an integer of 2 or greater) magnetic pole pairs and rotating together with the rotor; N1 (N1 is an integer of 2 or greater) first magnetic sensors facing the first magnet and spaced apart in the rotation direction of the first magnet; N2 (N2 is an integer of 3 or greater) second magnetic sensors facing the second magnet and spaced apart in the rotation direction of the second magnet; and a signal processing unit that processes N1 first detection signals output from the N1 first magnetic sensors and N2 second detection signals output from the N2 second magnetic sensors, wherein a period equivalent to one cycle in mechanical angle of the rotor is divided into a plurality of quadrants corresponding to combinations of signal strengths of the N1 first detection signals, a period corresponding to one period in terms of the mechanical angle of the rotor is divided into a plurality of sections separated by intersections between waveforms of the N2 second detection signals and zero-crossing points, which are points where the N2 second detection signals intersect with a reference value; the signal processing unit executes: a first acquisition process that acquires quadrant numbers indicating the quadrants based on the N1 first detection signals; a second acquisition process that acquires section numbers indicating the sections based on the N2 second detection signals; a mechanical angle calculation process that calculates information related to the mechanical angle of the rotor based on at least one of the quadrant numbers and the section numbers; and an abnormality detection process that detects an abnormality in the first detection signals and an abnormality in the second detection signals; and a first abnormality determination process that determines that an abnormal portion exists in the first detection signal when the chronological order of the quadrant numbers acquired in the first acquisition process differs from the chronological order of the quadrant numbers in a normal state. a second abnormality determination process that determines that an abnormal portion exists in the second detection signal if the chronological order of the section numbers acquired in the second acquisition process differs from the chronological order of the section numbers under normal conditions.

2. The signal processing unit executes a first counting process that advances a count each time it is determined that the rotor has rotated a predetermined angle based on N1 of the first detection signals, and a second counting process that advances a count each time it is determined that the rotor has rotated the predetermined angle based on N2 of the second detection signals, and the abnormality detection process includes a third abnormality determination process that determines that an abnormality exists in at least one of the first detection signals and the second detection signals when the difference between the count number obtained by the first counting process and the count number obtained by the second counting process is equal to or greater than a predetermined number.

3. The position detection device according to claim 1, wherein the signal processing unit executes fail-safe processing when it determines in the abnormality detection processing that an abnormal portion exists in one of the first detection signal and the second detection signal, and the fail-safe processing includes: an estimation processing that estimates information obtained based on a portion of the one detection signal determined to be abnormal under normal conditions based on at least a portion of the first detection signal and the second detection signal that is not determined to be abnormal; and a processing that calculates information related to the mechanical angle of the rotor based on the information estimated by the estimation processing at the portion determined to be abnormal.

4. A position detection device as described in claim 3, wherein the fail-safe processing includes a first fail-safe processing that is executed when the first abnormality determination processing determines that an abnormal portion exists in the first detection signal, and the first fail-safe processing includes processing that estimates the quadrant number of a first abnormal portion determined to be abnormal among the quadrant numbers acquired in the first acquisition processing based on the order of the first abnormal portion in the chronological arrangement of the quadrant numbers acquired in the first acquisition processing.

5. The position detection device of claim 3, wherein the fail-safe processing includes a second fail-safe processing that is executed when the second abnormality determination processing determines that an abnormal portion exists in the second detection signal, and the second fail-safe processing includes processing that determines in which quadrant number a second abnormal portion determined to be abnormal among the section numbers acquired in the second acquisition processing is included, and calculates information regarding the mechanical angle of the rotor corresponding to the period of the second abnormal portion based on information regarding the mechanical angle of the rotor that is predetermined for the period of the quadrant number in which the second abnormal portion is included.

6. A position detection device as described in claim 5, wherein the second fail-safe processing includes processing for calculating information regarding the mechanical angle of the rotor corresponding to the period of the second abnormality location based on information regarding the mechanical angle of the rotor predetermined for the period of the quadrant number that includes the second abnormality location, the time that has elapsed since the section number became the second abnormality location or the quadrant number became the quadrant number that includes the second abnormality location, and the rotational speed of the rotor.

7. A position detection device as described in claim 3, wherein the fail-safe processing includes a third fail-safe processing that is executed when it is determined in the second abnormality determination processing that an abnormality exists in some of the N2 second detection signals, and the third fail-safe processing includes processing that estimates information regarding the mechanical angle of the rotor that is normally obtained based on some of the second detection signals, based on the other second detection signals that are not determined to have an abnormality.

8. A position detection device as described in claim 7, wherein the third fail-safe processing includes processing for estimating information regarding the mechanical angle of the rotor obtained based on some of the second detection signals based on the other second detection signals that have been converted into triangular waves.

9. The position detection device according to claim 7, wherein the number of the second magnetic sensors is three, and each of the three second detection signals output from the three second magnetic sensors has: a first portion between the intersection with one of the other two second detection signals and the zero-cross point; and a second portion between the zero-cross point and the intersection with the other of the other two second detection signals, and wherein the third fail-safe processing, when it is determined that one of the second detection signals has an abnormality, includes estimating, based on the one second detection signal, information regarding the mechanical angle of the rotor that is normally obtained based on the first portion of the one second detection signal, and estimating, based on the other second detection signal, information regarding the mechanical angle of the rotor that is normally obtained based on the second portion of the one second detection signal.

10. A position detection device according to any one of claims 1 to 9, wherein the signal processing unit executes output processing to output an output signal, the output processing including: when the rotor starts to rotate, generating a first phase signal used to rectify the current supplied to the motor based on information relating to the mechanical angle of the rotor calculated in the mechanical angle calculation processing, and outputting the first phase signal as the output signal; and when no abnormality is detected by the abnormality detection processing from the time the rotor starts to rotate until a predetermined time has elapsed, generating second phase signals of A phase, B phase, and Z phase based on information relating to the mechanical angle of the rotor calculated in the mechanical angle calculation processing, and outputting the second phase signal as the output signal.

11. A position detection method for detecting the rotational position of a rotor in a motor, comprising signal processing for processing N1 first detection signals output from N1 (N1 is an integer of 2 or greater) first magnetic sensors facing a first magnet and N2 second detection signals output from N2 (N2 is an integer of 3 or greater) second magnetic sensors facing a second magnet, wherein the first magnet has one magnetic pole pair and rotates together with the rotor, and the second magnet has P (P is an integer of 2 or greater) magnetic pole pairs and rotates together with the rotor, the N1 first magnetic sensors are arranged at intervals in the rotation direction of the first magnet, and the N2 second magnetic sensors are arranged at intervals in the rotation direction of the second magnet, and a period equivalent to one mechanical angle cycle of the rotor is divided into a plurality of quadrants corresponding to combinations of signal strengths of the N1 first detection signals, a period corresponding to one period in terms of the mechanical angle of the rotor is divided into a plurality of sections separated by intersections between waveforms of the N2 second detection signals and zero-crossing points, which are points where the N2 second detection signals intersect with a reference value; the signal processing includes: a first acquisition process that acquires quadrant numbers indicating the quadrants based on the N1 first detection signals; a second acquisition process that acquires section numbers indicating the sections based on the N2 second detection signals; a mechanical angle calculation process that calculates information related to the mechanical angle of the rotor based on at least one of the quadrant numbers and the section numbers; and an abnormality detection process that detects an abnormality in the first detection signals and an abnormality in the second detection signals; and a first abnormality determination process that determines that an abnormal portion exists in the first detection signal when the chronological order of the quadrant numbers acquired in the first acquisition process differs from the chronological order of the quadrant numbers in a normal state. a second abnormality determination process that determines that an abnormal portion exists in the second detection signal if the chronological order of the section numbers acquired in the second acquisition process differs from the chronological order of the section numbers under normal conditions.

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