Rotation angle detection device and method for deriving rotation angle

Abstract

To obtain a rotation angle detection device and a rotation angle derivation method capable of highly accurately detecting a rotation angle of a rotation shaft of a rotary electric machine with a simple structure.SOLUTION: A magnetic flux of a rotor constituted of a permanent magnet 80 of a rotary electric machine 100 is detected by a rotation angle sensor 10 mounted at a position separated from a rotating shaft 60 of a rotor. The rotation angle of the rotating shaft 60 derived on the basis of change in the magnetic flux detected is corrected and outputted by a correction value correcting an error between the rotation angle and an ideal angle varying equally from 0 to 360 degrees.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a rotation angle detection device that detects the rotation angle of a rotating shaft of a rotating electric machine and a method for deriving the rotation angle. [Background technology]

[0002] In a three-phase synchronous rotating electric machine such as a brushless motor, it is necessary to detect the position of the magnetic poles of a rotor that is made of permanent magnets and rotates together with a rotating shaft. A control device for the rotating electric machine controls the supply of current to windings arranged near the rotor based on the detected magnetic pole position.

[0003] Patent Document 1 discloses a position detection unit that detects the position of the magnetic poles of a rotor of a rotating electric machine by a sensor using a Hall element. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP2014-75889A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the position detection unit described in Patent Document 1 requires a complex structure in which three sensors are used to detect the magnetic field of a metal part that is temporarily magnetized by the rotor's magnetic flux. In addition, since the information required to control the current flow to the windings of each of the three phases, U, V, and W, is sufficient to be able to detect the position of the rotor's magnetic poles, there is a problem that it cannot detect the rotation angle of the rotating shaft of the rotating electric machine that rotates together with the rotor.

[0006] The present invention has been created in consideration of the above-mentioned problems, and has an object to provide a rotation angle detection device and a method for deriving a rotation angle that are simple in structure and capable of detecting the rotation angle of a rotating shaft of a rotating electric machine with high accuracy. [Means for solving the problem]

[0007] In order to achieve the above object, the rotation angle detection device of the present invention includes a magnetic flux detection unit (10) that detects the magnetic flux of a rotor formed of a permanent magnet (80) of a rotating electric machine (100) at a position away from a rotation shaft (60) of the rotor, and a rotation angle derivation unit that corrects the rotation angle of the rotation shaft (60), derived based on the change in the magnetic flux detected by the magnetic flux detection unit (10), with a correction value that corrects the error between the rotation angle and an ideal angle that changes equally from 0 to 360 degrees, and outputs the rotation angle.

[0008] By configuring in this manner, it is possible to obtain a rotation angle detection device that can detect the rotation angle of the rotating shaft of a rotating electric machine with high accuracy using a simple structure. [Brief description of the drawings]

[0009] [Figure 1] 1A is a schematic diagram of an example of the configuration of a rotating electric machine according to this embodiment, viewed from one end face direction of the rotating shaft, and FIG. 1B is a schematic diagram of the rotating electric machine according to this embodiment, viewed from the radial direction of the rotating shaft. [Diagram 2] FIG. 2A is a schematic diagram showing an example of a package for a rotation angle sensor, and FIG. 2B is a schematic diagram showing an example of a configuration of a rotation angle sensor. [Diagram 3] FIG. 2A is a schematic diagram showing the configuration of a magnetic flux detection unit included in a rotation angle sensor, and FIG. 2B is a schematic diagram showing an output waveform of the magnetic flux detection unit. [Figure 4] FIG. 1A is an explanatory diagram showing a case where a rotation angle sensor is mounted near the radial end of the outer periphery of a rotating permanent magnet or near the axial end of a rotating permanent magnet, FIG. 1B is an explanatory diagram showing the density components of the magnetic flux of a rotating permanent magnet, and FIG. 1C is a schematic diagram showing the output waveform of the rotation angle sensor. [Diagram 5] 5 is a flowchart showing an example of a process for deriving a rotation angle of the rotation angle detection device according to the present embodiment. [Figure 6] 11 is a flowchart showing an example of a correction value setting process. [Figure 7]FIG. 1A is a schematic diagram showing an example of an ideal angle, an angle error, and a detected angle; FIG. 1B is an example of an angle error map in which detected angles and correction values ​​are mapped according to a determined map point number; and FIG. 1C is an explanatory diagram showing one aspect of correcting a mechanical angle using the angle error map. [Figure 8] 11A and 11B are explanatory diagrams for determining the map points and the range of the mechanical angle error. [Figure 9] 1A is a schematic diagram showing an example of the configuration of a rotating electric machine that is a first modified example of this embodiment, and FIG. 1B is a schematic diagram showing an example of the configuration of a rotating electric machine that is a second modified example of this embodiment. [Figure 10] 1A is a schematic diagram showing an example of the configuration of a rotating electric machine that is a third modified example of this embodiment, and FIG. 1B is a schematic diagram showing an example of the configuration of a rotating electric machine that is a fourth modified example of this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the present embodiment will be described with reference to the drawings. Fig. 1(A) is a schematic diagram of an example of the configuration of a rotating electric machine 100 according to the present embodiment, seen from one end face direction of a rotating shaft 60, and Fig. 1(B) is a schematic diagram of the rotating electric machine 100 according to the present embodiment, seen from the radial direction (side direction) of the rotating shaft 60. As shown in Figs. 1(A) and 1(B), the rotating electric machine 100 according to the present embodiment is an inner rotor type three-phase synchronous rotating electric machine including a rotor that is provided coaxially with the rotating shaft 60, which is an object of detection of the rotation angle, and that is constituted by a permanent magnet 80 that can rotate together with the rotating shaft 60, a rotation angle sensor 10 mounted on an annular substrate 84 disposed in the circumferential direction of the permanent magnet 80, and a stator 90 that includes a winding that is energized according to the rotation angle of the rotating shaft 60 derived based on the magnetic flux change detected by the rotation angle sensor 10. A signal indicating a change in magnetic flux detected by the rotation angle sensor 10 is input to a control device of the rotating electric machine 100 mounted on, for example, the substrate 84, and the rotation angle of the rotating shaft 60 is derived in the control device. In this embodiment, the rotation angle sensor 10 and the control device configure a rotation angle detection device. The control device may be provided at a location other than the substrate 84.

[0011] 1(B), a stator 90 having windings wound thereon that generate a so-called rotating magnetic field by controlling the flow of current is disposed in the circumferential direction of the permanent magnet 80. Electric power for generating a rotating magnetic field is supplied to the windings of the stator 90 from a substrate 84 via a conductive member such as a bus bar.

[0012] The rotation angle sensor 10 is mounted on a surface of the substrate 84 facing the stator 90, and detects the magnetic flux of the permanent magnet 80. The rotation angle sensor 10 detects the magnetic flux of the permanent magnet 80 and outputs an electric signal, which is input to a control device 12 mounted on the substrate 84 or the like. The control device 12 derives the rotation angle of the rotating shaft based on the electric signal output by the rotation angle sensor 10. In this embodiment, the control device 12 functions as a rotation angle derivation unit that corrects the rotation angle of the rotating shaft 60 derived based on the change in the magnetic flux of the permanent magnet 80 detected by the rotation angle sensor 10 with a correction value that corrects the error between the rotation angle and an ideal angle that changes at an equal interval from 0 to 360 degrees, and outputs the corrected rotation angle.

[0013] The rotating shaft 60 may have a hollow structure. When the rotating shaft 60 has a hollow structure, piping for a hydraulic device, cables, etc. can be arranged inside the rotating shaft 60.

[0014] Fig. 2(A) is a schematic diagram showing an example of a package for the rotation angle sensor 10, and Fig. 2(B) is a schematic diagram showing an example of the configuration of the rotation angle sensor 10. As shown in Fig. 2(A), the rotation angle sensor 10 is a lead type in which linear conductive terminals protrude from the package in approximately the same direction over a certain length. The conductive terminals of the lead type rotation angle sensor 10 have a degree of rigidity that prevents buckling when the conductive terminals are fixed and the rotation angle sensor 10 is held horizontally or vertically with the package facing up.

[0015] As shown in FIG. 2B, the rotation angle sensor 10 includes a plurality of magnetic flux detection units, ie, magnetic flux detection unit 20A and magnetic flux detection unit 20B, in a package.

[0016] FIG. 3A is a schematic diagram showing the configuration of magnetic flux detection units 20A and 20B included in the rotation angle sensor 10, and FIG. 3B is a schematic diagram showing output waveforms 70 and 72 of the magnetic flux detection units 20A and 20B.

[0017] As shown in Fig. 3(A), the magnetic flux detection units 20A and 20B are composed of MR (magnetoresistance) elements, for example. The magnetic flux detection units 20A and 20B are a type of Wheatstone bridge in which four resistors are arranged in a bridge shape, and when a magnetic flux is received in a state in which a voltage Vcc is applied, the resistance value of each resistor changes. As a result, the magnetic flux detection unit 20A outputs an electric signal having an output waveform 70 in which the voltage changes in a sinusoidal manner from terminals Sin+ and Sin-, and the magnetic flux detection unit 20B outputs an electric signal having an output waveform 72 in which the voltage changes in a phase different from that of the output waveform 70 from terminals Cos+ and Cos-.

[0018] The phase difference between the output waveform 70 and the output waveform 72 depends on the mounting positions of the magnetic flux detection units 20A and 20B. As shown in Fig. 3(A), when the magnetic flux detection unit 20B is mounted in a position where the direction in which it receives the magnetic flux differs by 90 degrees from that of the magnetic flux detection unit 20A, if the output waveform 70 is a sine wave, the output waveform 72 will be a cosine wave.

[0019] If the phase difference between the output waveforms 70 and 72 is 90 degrees, the tangent (tan) of the rotation angle of the rotating shaft 60 can be found from the output waveforms 70 and 72. Furthermore, by finding the value of the inverse tangent function (arctan), the rotation angle can be derived.

[0020] In this embodiment, the magnetic flux detection units 20A and 20B employ MR elements, but other magnetic detection elements such as Hall elements may also be used.

[0021] Fig. 4(A) is an explanatory diagram showing a case where the rotation angle sensor 10 is mounted near the radial end of the outer periphery of the rotating permanent magnet 80 or near the axial end of the rotating permanent magnet 80, Fig. 4(B) is an explanatory diagram showing the density components of the magnetic flux 88 of the rotating permanent magnet 80, and Fig. 4(C) is a schematic diagram showing output waveforms 74, 76 of the rotation angle sensor 10. In Figs. 4(A) to (C), the permanent magnet 80 is depicted as a one-pole pair magnet for the sake of simplicity. If the permanent magnet 80 is a one-pole pair magnet, the electrical angle and mechanical angle of the rotation angle of the rotating shaft 60 will be the same.

[0022] 4(A), the package of the rotation angle sensor 10 including two magnetic flux detection units is mounted in a sensor arrangement region 82 provided outside a gap Δd from the outer periphery of a cylindrical permanent magnet 80. As a result, the two magnetic flux detection units are each mounted in a state parallel to a tangent to the outer periphery of the permanent magnet 80. The rotation angle sensor 10 may also be mounted in a region spaced a gap Δe away from the axial end of the permanent magnet 80.

[0023] As shown in FIG. 4A, the case where the rotation angle sensor 10 is mounted in the radial direction of the rotating magnet or near the end of the magnet is called off-axis.

[0024] In the off-axis case, as an example, one magnetic flux detection unit of the rotation angle sensor 10 is mounted at a position where the magnetic flux density waveform is close to an ideal sine wave in the normal direction B(R) of the permanent magnet 80. In addition, the other magnetic flux detection unit of the rotation angle sensor 10 is mounted at a position where the magnetic flux density waveform is close to an ideal sine wave in the tangential direction B(θ) of the permanent magnet 80. If the normal direction B(R) and the tangential direction B(θ) are shifted from each other by 90 degrees, for example, the output waveform 74 will be sine wave-like and the output waveform 76 will be cosine wave-like.

[0025] The case where the rotation angle sensor is mounted in the axial direction of the rotating magnet is called on-axis. With on-axis, an output waveform in which the amplitudes of the sine wave and cosine wave are approximately equal compared to the off-axis output waveforms 74, 76 shown in Fig. 4(C) can be obtained, but the rotation angle sensor 10 must be mounted on the axis of the rotating shaft. However, if the rotating shaft 60 is hollow and cables or the like are arranged therein, it becomes difficult to mount the rotation angle sensor on-axis.

[0026] In this embodiment, the rotation angle sensor 10 is mounted off-axis, which allows various cables and the like to be arranged inside the rotating shaft 60. However, when the rotation angle sensor 10 is mounted off-axis, distortion occurs in the output waveforms 74, 76 indicating the change in magnetic flux, as shown in Fig. 4(C). In this embodiment, as will be described later, the rotation angle of the rotating shaft 60 calculated from the output waveforms 74, 76 is corrected, which allows the rotation angle to be derived with high accuracy.

[0027] Figures 5(A) and 5(B) are flow charts showing an example of a process for deriving a rotation angle in the rotation angle detection device according to this embodiment, with Figure 5(A) showing the processing steps for analog data and Figure 5(B) showing the processing steps for digital data. In step 100 of Figure 5(A), the magnetic flux of the permanent magnet 80, which is the rotor of the rotating electric machine 100, is detected by the rotation angle sensor 10. The rotation angle sensor 10 outputs an electrical signal that changes in a sinusoidal shape as shown in Figure 4(C).

[0028] In step 102, the electrical signal output by the rotation angle sensor 10 is amplified using, for example, an amplifier. Then, in step 104, a low-pass filter is used to remove high-frequency components from the electrical signal amplified in step 102, and the process ends. Then, the process proceeds to computer processing using the digital data in FIG. 5(B).

[0029] In step 106 of FIG. 5B, the electrical signal from which the high frequency components have been removed in step 104 is converted from an analog signal to a digital signal.

[0030] In step 108, the rotation angle of the rotating shaft 60 is calculated using the electrical signal converted into a digital signal. As described above, in this embodiment, the tangent (tan θ) of the rotation angle θ is found from the sine wave output waveform 74 and the cosine wave output waveform 76 as shown in Fig. 4(C), and the arctangent function (arctan) of tan θ is found to derive the rotation angle θ.

[0031] In step 110, a preset correction value is used to correct the rotation angle calculated in step 108. Setting of the correction value and application of the correction value to the calculated rotation angle will be described later.

[0032] In step 112, the process ends by determining the position of the magnetic poles of the permanent magnets 80, which are the rotor of the rotating electric machine 100. If the correspondence between the position of the magnetic poles of the permanent magnets 80 and the derived rotation angle is known in advance, the position of the magnetic poles of the permanent magnets 80 is determined from the rotation angle derived based on the correspondence.

[0033] The correspondence between the position of the magnetic pole of the permanent magnet 80 and the derived rotation angle is, for example, as follows. Assume that the position of the magnetic pole of the permanent magnet 80 is as shown in FIG. 4B, and the rotation angle sensor 10 is located at the intersection of the arrow B(R) and the arrow B(θ) shown in FIG. 4B. In this case, if the output waveform 74 indicates 1, which is the maximum value, and the output waveform 76 indicates 0 in FIG. 4C, the tangent derived from the output waveforms 74 and 76 is 0, and the rotation angle, which is its arctangent, is 0 degrees. Therefore, if the derived rotation angle is 0 degrees, it can be estimated that the magnetic pole of the permanent magnet 80, which is the rotor of the rotating electric machine 100, facing the rotation angle sensor 10 is an S pole. Similarly, by previously grasping the correspondence between the position of the magnetic pole of the permanent magnet 80 and the derived rotation angle, the position of the magnetic pole of the permanent magnet 80 can be determined from the derived rotation angle.

[0034] Hereinafter, a description will be given of the setting of the correction value used in step 110 in Fig. 5. In this embodiment, the correction value is set for each individual rotating electrical machine 100.

[0035] 6 is a flow chart showing an example of a process for setting the correction values. In step 200, the rotary shaft 60 is rotated once to calculate the ideal angle, the angle error, and the detected angle.

[0036] FIG. 7(A) is a schematic diagram showing an example of an ideal angle, an angle error, and a detected angle. As shown in FIG. 7(A), when calculating the ideal angle, the angle error, and the detected angle, a mechanical angle error score is set in advance. As an example, the mechanical angle error score in FIG. 7(A) is 500, but the mechanical angle error score is set to a resolution equal to or greater than the resolution of the rotation angle (mechanical angle) in the rotation angle detection device. In FIG. 7(A), the index is set from 0 to 499 according to the rotation angle error score.

[0037] The ideal angle is calculated using the mechanical angle error score and the index value by the following formula so that it changes from 0 to 360 degrees at equal intervals (0.72 degrees in this embodiment). Ideal angle=index×360 / mechanical angle error points

[0038] The detected angle in Fig. 7(A) is calculated by performing steps 100 to 108 in Fig. 5 when the rotating shaft 60 rotates once. The mechanical angle error in Fig. 7(A) is a value obtained by subtracting the ideal angle from the detected angle.

[0039] In step 202, a map score is determined, which is the number of correction values ​​to be recorded in the angle error map in which the correction values ​​are recorded. FIG. 8 is an explanatory diagram for determining the map score and the range of the mechanical angle error. The map score is determined based on the resolution required for the rotation angle detection device and the memory capacity for storing the angle error map. In FIG. 8, as an example, the map score is set to 8 bits (2 8 = 256) and dividing 360 degrees by 8 bits calculates a unit detection angle of 1.4 degrees, which corresponds to the resolution of the rotation angle detection device.

[0040] In addition, as an example, the range of the mechanical angle error is assumed to be divided into 8 bits, which is 1 byte, on the vertical axis of FIG. 8, and 360 degrees is divided into 16 bits, which is 2 bytes (216 = 65536), we get 5.49 × 10 -3 Then, as an example, 127 mechanical angle error segments are set in the positive direction of the vertical axis, one at 0 on the vertical axis, and 128 mechanical angle error segments are set in the negative direction of the vertical axis, thereby setting a mechanical angle error range from -0.703 degrees to 0.698 degrees.

[0041] In step 204, the detected angle and the correction value are mapped onto an angle error map in accordance with the determined number of map points, and the process ends.

[0042] Fig. 7(B) is an example of an angle error map in which detection angles and correction values ​​are mapped according to the determined map points. Since the map points of the angle error map in Fig. 7(B) are 256, the index is set from 0 to 255, and the detection angle is set from 0 to 358.6 (≒360) in increments of the unit detection angle described above. Therefore, the detection angle of the angle error map is calculated by the following formula using the map points and the index value. 360 / map point on the right side of the following formula indicates the unit detection angle described above. Detection angle = index x 360 / map score

[0043] The correction value in FIG. 7(B) is calculated based on the mechanical angle error in FIG. 7(A), but the number of mechanical angle error points in FIG. 7(A) is 500, while the number of map points in the angle error map in FIG. 7(B) is 256, so two detection angles in FIG. 7(A) closest to the detection angle in FIG. 7(B) are selected (in other words, the closest detection angle in FIG. 7(A) and the second closest detection angle in FIG. 7(A) are selected), and the correction value is calculated by linearly interpolating the mechanical angle errors corresponding to the two selected detection angles. For example, the detection angles in FIG. 7(A) closest to the detection angle 1.4 degrees in FIG. 7(B) are 1.15 degrees and 1.88 degrees, so the mechanical angle error 0.43 corresponding to the detection angle 1.15 degrees and the mechanical angle error 0.44 corresponding to the detection angle 1.88 degrees are linearly interpolated to obtain a correction value of 0.43.

[0044] Similarly, two detection angles in Fig. 7(A) closest to the detection angle in Fig. 7(B) are selected, and the mechanical angle errors corresponding to the two selected detection angles are linearly interpolated to calculate correction values, thereby mapping the correction values ​​of the angle error map. The angle error map for which mapping has been completed is stored in a storage unit (not shown) mounted on the board 84 or the like. Alternatively, it may be stored in a storage unit of a higher-level control device, and when correction of the rotation angle is required, it may be downloaded from the higher-level control device to the storage unit mounted on the board 84 or the like for use in correcting the rotation angle.

[0045] Fig. 7(C) shows one aspect of the correction of the mechanical angle using the angle error map in step 110 of Fig. 6. Since the detected value of the mechanical angle calculated in step 108 of Fig. 6 does not correspond to the unit detected angle increment of 1.4 degrees of the angle error map, two detected angles of the angle error map closest to the detected value are selected (in other words, the closest detected angle of Fig. 7(C) and the second closest detected angle of Fig. 7(C) are selected), and a correction value corresponding to the detected value is calculated by linearly interpolating the correction values ​​corresponding to the two selected detected angles. For example, when the detected value is 2 degrees, the detected angles of the angle error map closest to 2 degrees are 1.4 degrees and 2.8 degrees, so a correction value of 0.43 corresponding to the detected angle of 1.4 degrees of the angle error map and a correction value of 0.45 corresponding to the detected angle of 2.8 degrees of the angle error map are linearly interpolated to obtain a correction value of 0.44.

[0046] In step 110 of FIG. 5, the angle is corrected by subtracting a correction value obtained by linear interpolation from the mechanical angle calculated in step .

[0047] In this embodiment, as shown in Fig. 7C, linear interpolation of the correction value is performed, but this is not limited to this. If the number of map points is sufficiently greater than 256, one detection angle from the angle error map that is closest to the detection value may be selected without linear interpolation of the correction value, and the correction value corresponding to the selected detection angle may be applied to the detection value.

[0048] A modified example of this embodiment will be described below. In the modified example, the same components as those shown in Figures 1(A) and 1(B) are denoted by the same reference numerals as in Figures 1(A) and 1(B), and detailed descriptions thereof will be omitted.

[0049] 9(A) is a schematic diagram showing an example of the configuration of a rotating electric machine 200A which is a first modified example of this embodiment. The rotating electric machine 200A shown in FIG. 9(A) is an inner rotor type three-phase synchronous rotating electric machine like the rotating electric machine 100 shown in FIG. 1(A) and FIG. 1(B). The rotating electric machine 200A is different from the rotating electric machine 100 shown in FIG. 1(A) and FIG. 1(B) in that the substrate 184A protrudes toward the end side in the axial direction of the permanent magnet 80 which is the rotor, and the rotation angle sensor 10 detects the magnetic flux of the permanent magnet 80 in the vicinity of the end of the permanent magnet 80. In addition, the windings provided in the stator 90 are supplied with power for generating a rotating magnetic field from the substrate 184A via a bus bar 186.

[0050] Fig. 9(B) is a schematic diagram showing an example of the configuration of a rotating electric machine 200B which is a second modified example of this embodiment. The rotating electric machine 200B shown in Fig. 9(B) is an inner rotor type three-phase synchronous rotating electric machine similar to the rotating electric machine 100 shown in Fig. 1(A) and Fig. 1(B). The rotating electric machine 200B differs from the rotating electric machine 100 shown in Fig. 1(A) and Fig. 1(B) in that a substrate 184B is provided between the permanent magnet 80 which is the rotor and the winding of the stator 90, and the rotation angle sensor 10 detects magnetic flux in the radial direction of the permanent magnet 80.

[0051] Fig. 10(A) is a schematic diagram showing an example of the configuration of a rotating electric machine 300A which is a third modified example of this embodiment. The rotating electric machine 300A shown in Fig. 10(A) is an outer rotor type three-phase synchronous rotating electric machine in which a permanent magnet 180 which is a rotor is provided on the outer periphery of a stator 180. In the rotating electric machine 300A, a substrate 284A protrudes toward the end side in the axial direction of a permanent magnet 80 which is a rotor, and a rotation angle sensor 10 detects the magnetic flux of the permanent magnet 80 near the end of the permanent magnet 80. In addition, power for generating a rotating magnetic field is supplied from the substrate 284A to the windings provided in the stator 190 via a bus bar 286.

[0052] Fig. 10(B) is a schematic diagram showing an example of the configuration of a rotating electric machine 300B which is a fourth modified example of this embodiment. The rotating electric machine 300B shown in Fig. 10(B) is an outer rotor type three-phase synchronous rotating electric machine like the rotating electric machine 100 shown in Fig. 10(A). The rotating electric machine 300B differs from the rotating electric machine 300A shown in Fig. 10(A) in that a substrate 284B is provided on the outer periphery of a permanent magnet 180 which is a rotor, and a rotation angle sensor 10 detects magnetic flux in the radial direction of the permanent magnet 80.

[0053] 9(A), 9(B), 10(A) and 10(B) are all off-axis cases in which the rotation angle sensor 10 is mounted in the radial direction of the rotating magnet or near the end of the magnet. Therefore, like the rotating electric machine 100, the rotating shafts of the rotating electric machines 200A, 200B, 300A and 300B are hollow, making it possible to install various cables inside the rotating shaft.

[0054] As mentioned above, when the rotation angle sensor 10 is off-axis, distortion is likely to occur in the waveform indicating the change in magnetic flux output by the rotation angle sensor 10. However, by correcting the distortion using a method similar to that used for the rotating electric machine 100, it is possible to derive the rotation angle with high accuracy.

[0055] As described above, according to this embodiment, the change in magnetic flux detected in an off-axis state is detected using a rotation angle sensor 10 capable of outputting a sinusoidal signal having a phase difference that allows the tangent to be calculated, and the calculated rotation angle is corrected with a preset correction value, making it possible to derive the rotation angle of the rotating shaft of a rotating electric machine with a simple structure and high accuracy.

[0056] In this embodiment, the correction value is set for each of the rotating electric machines 100, 200A, 200B, 300A, and 300B. Since the rotation angle is calculated based on the change in the magnetic flux of the permanent magnet 80, the correction value for each of the rotating electric machines is set for each magnetic pole of the permanent magnet 80 based on the difference between the ideal angles arranged at equal intervals from 0 degrees to 360 degrees with a predetermined difference and the detected angle obtained by rotating the rotating shaft 60 once.

[0057] The set correction values ​​are not continuous but discrete values, so they do not completely match the rotation angle detected by the rotation angle detection device. In this embodiment, the two correction values ​​closest to the detected rotation angle are selected, and the detected rotation angle is corrected with the correction value obtained by linearly interpolating the two correction values, thereby making it possible to obtain the rotation angle of the rotating shaft 60 with high accuracy.

[0058] According to the rotation angle detection device according to this embodiment, which can derive the rotation angle of the rotation shaft 60 with high accuracy, it becomes possible to accurately control the rotation of the actuators that the robot and the autonomous vehicle are equipped with.

[0059] In this embodiment, it is assumed that a microcomputer executes the process shown in FIG. 5 by software (program), but various processors other than a microcomputer may execute the process shown in FIG. 5. In this case, examples of the processor include a PLD (Programmable Logic Device) such as an FPGA (Field-Programmable Gate Array) whose circuit configuration can be changed after manufacture, and a dedicated electric circuit such as an ASIC (Application Specific Integrated Circuit) which is a processor having a circuit configuration designed exclusively for executing a specific process. In addition, the process may be executed by one of these various processors, or may be executed by a combination of two or more processors of the same or different types (e.g., multiple FPGAs, etc.). In addition, the hardware structure of these various processors is, more specifically, an electric circuit that combines circuit elements such as semiconductor elements. [Explanation of symbols]

[0060] 10 rotation angle sensor, 20A, 20B magnetic flux detection unit, 60 rotating shaft, 70, 72, 74, 76 output waveform, 80 permanent magnet, 82 sensor arrangement area, 84 substrate, 88 magnetic flux, 90 stator, 100 rotating electric machine, 180 permanent magnet, 184A, 184B substrate, 186 bus bar, 190 stator, 200A, 200B rotating electric machine, 284A, 284B substrate, 286 bus bar, 300A, 300B rotating electric machine

Claims

1. a magnetic flux detection unit (10) that detects magnetic flux of a rotor formed of a permanent magnet (80) of a rotating electric machine (100) at a position away from a rotation shaft (60) of the rotor; a rotation angle derivation unit that corrects the rotation angle of the rotating shaft (60) derived based on the change in the magnetic flux detected by the magnetic flux detection unit (10) with a correction value that corrects an error between the rotation angle and an ideal angle that changes at equal intervals from 0 to 360 degrees, and outputs the corrected rotation angle; Including, The rotation angle derivation unit is an angle error map that maps, in association with each other, a detection angle that is discretely set between 0 degrees and 360 degrees, a map score that is a score of the correction value, and a correction value obtained by linearly interpolating a mechanical angle error corresponding to the detection angle closest to the rotation angle before correction and a mechanical angle error corresponding to the detection angle second closest to the rotation angle before correction; a correction value corresponding to the detection angle in the angle error map that is closest to the rotation angle before correction, and a correction value corresponding to the detection angle in the angle error map that is second closest to the rotation angle before correction, and a correction value obtained by linearly interpolating the correction value corresponding to the detection angle in the angle error map that is closest to the rotation angle before correction,

2. 2. The rotation angle detection device according to claim 1, wherein the magnetic flux detection unit (10) is provided within a predetermined range from an outer periphery of the rotor in a radial direction of the rotor.

3. 2. The rotation angle detection device according to claim 1, wherein the magnetic flux detection unit (10) is provided in the vicinity of an axial end of the rotor within a predetermined range from the end.

4. The magnetic flux detection unit (10) outputs two sinusoidal signals having a phase difference of 90 degrees from each other based on a change in the magnetic flux, The rotation angle detection device according to any one of claims 1 to 3, wherein the rotation angle derivation unit calculates the rotation angle of the rotating shaft (60) based on the change in the magnetic flux by calculating the arc tangent of a quotient of the two sinusoidal signals.

5. 5. The rotation angle detection device according to claim 1, wherein the magnetic flux detection unit (10) is mounted on a substrate electrically connected to a winding of a stator (90) of the rotating electric machine (100).

6. 6. The rotation angle detection device according to claim 1, wherein the magnetic flux detection unit (10) has an output terminal formed of a linear member having a predetermined rigidity.

7. 7. The rotation angle detection device according to claim 1, further comprising a magnetic pole position estimating unit that estimates a position of a magnetic pole of the rotor based on the rotation angle corrected by the correction value.

8. The rotation angle detection device according to any one of claims 1 to 6, wherein the rotating shaft (60) of the rotating electric machine (100) has a hollow structure, and the magnetic flux detection unit (10) is mounted away from the axis of the rotating shaft (60).

9. A detection step of detecting a magnetic flux of a rotor constituted by a permanent magnet (80) of a rotating electric machine (100) at a position away from a rotation shaft (60) of the rotor; a calculation step of calculating based on the detected change in magnetic flux; a correction step of correcting the rotation angle of the rotating shaft (60) with a correction value for correcting an error between the rotation angle and an ideal angle that changes at equal intervals from 0 to 360 degrees, and outputting the result; Including, The correction step uses an angle error map which maps, in association with each other, a detection angle which is discretely set between 0 degrees and 360 degrees, a map score which is a score of the correction value, and a correction value obtained by linearly interpolating each of a mechanical angle error corresponding to the detection angle closest to the rotation angle before correction and a mechanical angle error corresponding to the detection angle second closest to the rotation angle before correction, and includes a step of correcting the rotation angle before correction with a correction value obtained by linearly interpolating each of a correction value corresponding to the detection angle in the angle error map which is closest to the rotation angle before correction and a correction value corresponding to the detection angle in the angle error map which is second closest to the rotation angle before correction.

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