Rotation angle detection system, rotation angle calculation method, and rotation angle calculation program

Abstract

To provide a rotation angle calculation device, a rotation angle calculation system, a rotation angle calculation method, and a rotation angle calculation program that can reduce, when signals of two orthogonal components with respect to an electrical angle are generated, for a rotation angle of a detection object, the error between a calculation result and the actual rotation angle of the rotated detection object.SOLUTION: A rotation angle calculation device comprises: an acquisition unit (21) that acquires a result of detection of leakage flux generated from one permanent magnet (4) included in a detection object for which a rotation angle is detected, from each of three detection elements (11) arranged at positions having an electrical angle deviated by 120 degrees from the permanent magnet (4); a generation unit (22) that, by using the acquired three detection results, generates orthogonal component signals indicating two orthogonal components representing the intensity of the leakage flux; and a calculation unit (23) that calculates the rotation angle of the detection object by using the orthogonal component signals.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a rotation angle calculation device, a rotation angle calculation system, a rotation angle calculation method, and a rotation angle calculation program for calculating the rotation angle of a detection target. It relates to.

Background Art

[0002] In Patent Document 1, in a permanent magnet synchronous motor, two Hall sensors for detecting the magnetic flux generated from a permanent magnet are arranged at a position where the rotational electrical angle is greater than 0 degrees and less than 180 degrees with respect to a rotor on which the permanent magnet is installed. A permanent magnet synchronous motor device is disclosed. The permanent magnet synchronous motor device generates a current for exciting a winding that drives the rotor in accordance with a signal detected by the Hall sensor.

[0003] The permanent magnet synchronous motor device includes a controller that controls the current for exciting the winding that drives the rotor. Since the controller controls the current for exciting the winding in accordance with the signal detected by the Hall element, torque ripple is suppressed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, it is desirable that the waveform of the signal indicating the strength of the magnetic flux detected by the two Hall elements is a first-order sine wave with respect to the electrical angle, and an error occurs in the calculated rotation angle as it deviates from the first-order sine wave. In other words, when signals of two orthogonal components with respect to the electrical angle are generated using the signals detected by the two Hall elements, noise is included in the signals, and an error may occur between the calculated result and the actually rotated rotation angle of the detection target.

[0006] The purpose of this disclosure is to provide a rotation angle calculation device, a rotation angle calculation system, a rotation angle calculation method, and a rotation angle calculation program that can suppress the error between the calculated result and the actual rotation angle when two orthogonal component signals for an electrical angle are generated. [Means for solving the problem]

[0007] A rotation angle calculation device according to a first aspect of the present disclosure includes: an acquisition unit (21) that acquires detection results from three detection elements (11) positioned at positions where the electrical angle is shifted by 120 degrees with respect to a single permanent magnet (4) provided on a detection target for which a rotation angle is to be detected, by detecting the leakage magnetic flux generated from the permanent magnet (4); a generation unit (22) that uses the three acquired detection results to generate an orthogonal component signal showing two orthogonal components representing the strength of the leakage magnetic flux; and a calculation unit (23) that uses the orthogonal component signal to calculate the rotation angle of the detection target.

[0008] Furthermore, the rotation angle calculation method according to the second aspect of this disclosure involves a computer obtaining detection results from three detection elements positioned at an electrical angle shift of 120 degrees with respect to a single permanent magnet in the motor, which is the object of the rotation angle detection, to detect the leakage magnetic flux generated from the permanent magnet, generating an orthogonal component signal showing two orthogonal components representing the strength of the leakage magnetic flux using the three obtained detection results, and calculating the rotation angle of the motor using the orthogonal component signal.

[0009] Furthermore, the rotation angle calculation program according to the third aspect of this disclosure is configured to have at least one processor perform the following processing: obtain detection results from three detection elements positioned at an electrical angle shift of 120 degrees with respect to a single permanent magnet of the motor whose rotation angle is to be detected; generate an orthogonal component signal showing two orthogonal components representing the strength of the leakage magnetic flux using the three obtained detection results; and calculate the rotation angle of the motor using the orthogonal component signal. [Effects of the Invention]

[0010] According to this disclosure, when two orthogonal component signals are generated for an electrical angle, the error between the calculated rotation angle and the actual rotation angle of the detected object can be suppressed. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram showing an example of the configuration of the rotation angle calculation system according to this embodiment. [Figure 2] This is a block diagram showing an example of the hardware configuration of the rotation angle calculation device according to this embodiment. [Figure 3] This block diagram shows an example of the configuration of the functions of the rotation angle calculation device according to this embodiment. [Figure 4] This graph shows an example of the detection results for the electrical angle according to this embodiment. [Figure 5] This is a schematic diagram showing an example of the synthesized detection results according to this embodiment. [Figure 6] This graph shows an example of the composite detection results for the electric angle according to this embodiment. [Figure 7] This flowchart shows an example of the process for calculating the rotation angle according to this embodiment. [Figure 8] This is a front view showing an example of the configuration of a permanent magnet synchronous motor (SPM) according to this embodiment. [Figure 9] This is a top view showing an example of the configuration of a permanent magnet synchronous motor used to explain the arrangement of Hall elements according to this embodiment. [Figure 10] This is a front view showing an example of the configuration of an embedded permanent magnet synchronous motor (IPM) according to Modification 1. [Figure 11] This is a front view showing an example of the configuration of an outer rotor type permanent magnet synchronous motor according to Modification 2. [Figure 12] This is a front view showing an example of the configuration of an axial gap type permanent magnet synchronous motor according to Modification 3. [Modes for carrying out the invention]

[0012] Hereinafter, embodiments for implementing the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing an example of the configuration of a rotation angle calculation system according to the present embodiment.

[0013] (Configuration of Rotation Angle Calculation System) As shown in FIG. 1 as an example, the rotation angle calculation system 1 includes a permanent magnet synchronous motor 2 and a rotation angle calculation device 10 that calculates the rotation angle of the motor.

[0014] The motor 2 includes a rotor 5 including a rotor core 3 and a permanent magnet 4, and a stator 6.

[0015] For example, the motor 2 is an inner rotor type permanent magnet synchronous motor in which the rotor 5 is installed inside the stator 6 in the radial direction. The permanent magnet 4 is fixed to the rotor core 3 and is installed so that the direction of the magnetic field alternates between adjacent permanent magnets 4. The stator 6 includes teeth 6A around which a winding (not shown) is wound, and slots 6B formed between the teeth 6A. The stator 6 is a stator core around which a winding (not shown) is wound so as to straddle the slots 6B. In the present embodiment, a form of a permanent magnet synchronous motor in which a 8-pole permanent magnet 4 and a stator 6 having 12 slots 6B (windings) are arranged will be described. However, it is not limited to this. The permanent magnet 4 may have 4 poles, the slot 6B (winding) may have 8 slots, and the number of the permanent magnets 4 and the slots 6B may be any number.

[0016] The rotation angle calculation device 10 includes hall elements 11A, hall elements 11B, and hall elements 11C. Hereinafter, when distinguishing each hall element 11, it will be described as hall element 11A, hall element 11B, and hall element 11C, and when not distinguishing, it will be described as hall element 11. Note that the hall element 11 is an example of a "detection element".

[0017] Each Hall element 11 is positioned inside the motor 2 at a location where it can detect leakage flux generated from the permanent magnet 4, with three Hall elements 11 positioned for each single-pole permanent magnet 4. The Hall elements 11 output a signal indicating the strength of the leakage flux as a detection result. Here, each Hall element 11 is positioned at a distance of 120 degrees from the other in terms of electrical angle. When the motor 2 contains multiple permanent magnets 4, the positioning pitch of each Hall element 11 is expressed by the following formula, with respect to one Hall element 11.

[0018]

number

[0019] Here, d is the arrangement pitch of other Hall elements 11 relative to a reference Hall element 11, and p is the number of pole pairs (number of pole pairs) related to the permanent magnet 4 included in the motor 2. s is an identifier for identifying each Hall element for a single-pole permanent magnet 4, and can take either s=1 or 2. n is an identifier for identifying each permanent magnet, and can take any value from 0 to p-1.

[0020] For example, if the motor 2 is equipped with an 8-pole permanent magnet 4, each Hall element 11 is arranged in the circumferential direction of the motor 2 at intervals that result in a mechanical angle of 15 degrees. In the following, to avoid confusion, a configuration in which three Hall elements 11, Hall element 11A, Hall element 11B, and Hall element 11C, each detect a signal will be described.

[0021] The rotation angle calculation device 10 uses the three-phase signals detected by Hall elements 11A, 11B, and 11C to derive the difference between them and generate a sine signal and a cosine signal. The rotation angle calculation device 10 uses the generated sine signal and cosine signal to calculate the rotation angle of the motor. Note that the sine signal and cosine signal are examples of "orthogonal component signals".

[0022] (Configuration of the rotation angle calculation device) Next, the hardware configuration of the rotation angle calculation device 10 will be described with reference to Figure 2. Figure 2 is a block diagram showing an example of the hardware configuration of the rotation angle calculation device according to this embodiment.

[0023] As an example, as shown in Figure 2, the rotation angle calculation device 10 includes a Hall element 11, a control unit 12, a ROM (Read Only Memory) 13, a RAM (Random Access Memory) 14, an input / output interface (hereinafter referred to as "input / output I / F") 15, and an analog-to-digital conversion circuit (hereinafter referred to as "AD conversion circuit") 16. The control unit 12, ROM 13, RAM 14, and AD conversion circuit 16 are each interconnected by a bus 19.

[0024] The Hall element 11 is a sensor that detects the leakage magnetic flux of the permanent magnet 4. The control unit 12 oversees and controls the entire rotation angle calculation device 10. The ROM 13 stores various programs and data. The RAM 14 is memory used as a work area when various programs are executed. The control unit 12 calculates the rotation angle of the object to be detected by loading the program stored in the ROM 13 into the RAM 14 and executing it.

[0025] The input / output interface 15 is connected to the Hall element 11 and the AD conversion circuit 16. The input / output interface 15 outputs the three-phase signals input from Hall elements 11A, 11B, and 11C to the AD conversion circuit 16.

[0026] The AD conversion circuit 16 converts the three-phase analog signal output by the input / output interface 15 into a digital signal and outputs it to the control unit 12.

[0027] Next, the functional configuration of the rotation angle calculation device 10 will be described with reference to Figure 3. Figure 3 is a block diagram showing an example of the functional configuration of the rotation angle calculation device 10 according to this embodiment.

[0028] As an example, as shown in Figure 3, the rotation angle calculation device 10 includes an acquisition unit 21, a generation unit 22, and a calculation unit 23.

[0029] The acquisition unit 21 acquires a digital signal obtained by converting the three-phase analog signal output by the Hall element 11 via the input / output interface 15 and the AD conversion circuit 16. Here, the Hall element 11 outputs three-phase analog signals of U-phase, V-phase, and W-phase, as shown in Figure 4 as an example. Here, each analog signal has a phase difference of 120 degrees from each other.

[0030] The generation unit 22 uses the three-phase digital signals acquired by the acquisition unit 21 to generate mutually orthogonal sine and cosine signals. Specifically, the generation unit 22 derives the difference between the values ​​of two of the three-phase signals and uses the derived differences to generate the sine and cosine signals. The difference between each signal is expressed by the following formula.

[0031]

number

[0032]

number

[0033]

number

[0034]

number

[0035] Here, U' is the difference between the U-phase signal and the V-phase signal, V' is the difference between the V-phase signal and the W-phase signal, W' is the difference between the W-phase signal and the U-phase signal, and V'' is the difference between the V'-phase signal and the W'-phase signal.

[0036] When V″ is expressed using the U phase, V phase, and W phase, the above equation (5) can be expressed by the following formula.

[0037]

number

[0038] The U' phase, represented by equation (2) above, and the V'' phase, represented by equation (6) above, are orthogonal to each other, as shown in Figure 5 as an example. The generation unit 22 generates orthogonal component signals by normalizing the U' phase signal to generate a SIN signal and normalizing the V'' phase digital signal to generate a COS signal. Figure 6 is a graph showing an example of the SIN signal related to the U' phase and the COS signal related to the V'' phase in the analog signal according to this embodiment.

[0039] The calculation unit 23 uses the generated sine and cosine signals to calculate the rotation angle of the object to be detected. Specifically, the calculation unit 23 uses the values ​​of the generated sine and cosine signals to calculate θ = tangent. -1 The rotation angle of the object to be detected is calculated by performing (SINθ / COSθ). Here, θ is the rotation angle of the object to be detected, and tan -1 θ is the inverse function of the tangent. SINθ is the value of the generated sine signal, and COSθ is the value of the generated cosine signal.

[0040] Next, a method for detecting the rotation angle according to this embodiment will be described with reference to Figure 7. Figure 7 is a flowchart showing an example of a method for detecting the rotation angle according to this embodiment.

[0041] In step S101, the rotation angle calculation device 10 acquires a three-phase digital signal detected by the Hall element 11 and converted by the AD conversion circuit 16.

[0042] In step S102, the rotation angle calculation device 10 uses the acquired three-phase digital signals to derive the differences between them and derives the values ​​for the U' phase, V' phase, and W' phase.

[0043] In step S103, the rotation angle calculation device 10 derives the V'' phase using the values ​​of the V' phase and the W' phase.

[0044] In step S104, the rotation angle calculation device 10 normalizes the value of the digital signal of the U' phase to generate a SIN signal, and normalizes the value of the digital signal of the V'' phase to generate a COS signal.

[0045] In step S105, the rotation angle calculation device 10 calculates the rotation angle of the object to be detected using the generated SIN signal and COS signal.

[0046] (Arrangement of Hall elements 11) Next, with reference to Figure 8, the arrangement of the Hall elements 11 inside the motor 2 according to this embodiment will be described. Figure 8 is a schematic diagram showing an example of the configuration of the motor 2 according to this embodiment. In this embodiment, the motor 2 will be described as an inner rotor type permanent magnet synchronous motor in which the rotor 5 is installed radially inside the stator 6.

[0047] As an example, as shown in Figure 8, in the motor 2 according to this embodiment, the rotor 5 includes a rotor core 3 at the axial center and permanent magnets 4 on the radially outer side of the rotor core 3. The stator 6 includes teeth 6A provided on the radially outer side of the rotor core 3 and windings (coils) 7 wound around the teeth 6A. In other words, in the motor 2 according to this embodiment, the rotor core 3, permanent magnets 4, and stator 6 are installed in that order radially from the center of the motor 2.

[0048] The Hall element 11 is positioned so that leakage flux generated from the permanent magnet 4 can be detected. Specifically, if the width (radial length) of the permanent magnet 4 is B, the Hall element 11 in the radial direction is positioned within the range from 3B away from the radially inner end of the permanent magnet 4 (see arrow 31) to 3B away from the radially outer end of the permanent magnet 4 (see arrow 32) so that leakage flux can be detected. Similarly, the Hall element 11 in the axial direction is positioned within the range from the axially upper end of the permanent magnet 4 to 3B away from that end (see arrow 33). It is desirable that the position of the Hall element 11 in the axial direction does not exceed the height (axial length) of the winding 7.

[0049] In this embodiment, the arrangement of the Hall element 11 for detecting the leakage flux of the permanent magnet 4 has been described. However, it is not limited to this arrangement. The height of the permanent magnet 4 may also be changed.

[0050] For example, the height (axial length) M of the permanent magnet 4 is expressed by the following formula.

[0051]

number

[0052] Here, S is the height (axial length) of the stator 6 (teeth 6A), and A is the size of the gap (air gap) between the rotor 5 and the stator 6 in the radial direction.

[0053] As shown in equation (7) above, it is desirable that the height M of the permanent magnet 4 be within a range where the lower limit is the height S of the stator 6 (teeth 6A) plus twice the height A of the air gap, and the upper limit is 1.3 times the height S of the stator 6 (teeth 6A). By setting the height of the permanent magnet 4 to the value of equation (7) above, the position of the Hall element 11 is raised in accordance with the height of the permanent magnet 4. As a result, the distance between the Hall element 11 and the teeth 6A (winding 7) increases, the distortion of the magnetic flux due to the teeth 6A (winding 7) decreases, and the accuracy of leakage flux detection by the Hall element 11 improves.

[0054] Furthermore, Hall elements 11 are placed between adjacent teeth 6A (on slot 6B) of the stator 6. In other words, by placing the Hall elements 11 between windings (coils) 7, the distortion of the magnetic flux caused by the windings (coils) 7 is reduced. Figure 9 is a top view showing an example of the configuration of a permanent magnet synchronous motor used to explain the arrangement of Hall elements according to this embodiment. As an example, as shown in Figure 9, it is desirable that the Hall elements 11 be placed between one tooth 6A and another adjacent tooth 6A in the circumferential direction. By installing the Hall elements 11 between adjacent teeth 6A, the influence of the magnetic flux generated from the windings (coils) 7 is suppressed.

[0055] (Modified example 1 regarding the arrangement of Hall elements 11) The motor 2 in the above embodiment was described as an SPM (Surface Permament Magnet) motor in which permanent magnets 4 are arranged around the rotor core 3. The motor 2 according to this modified example 1 will be described as an IPM (Interior Permament Magnet) motor in which permanent magnets 4 are embedded in the rotor core 3.

[0056] Figure 10 is a schematic diagram showing an example of the configuration of the motor 2 in Modification 1. As an example, as shown in Figure 10, the motor 2 according to Modification 1 includes a rotor 5 which comprises a rotor core 3 at the axial center and permanent magnets 4 inside the rotor core 3. The stator 6 also includes teeth 6A provided on the radially outer side of the rotor core 3 and windings (coils) 7 wound around the teeth 6A.

[0057] In Modification 1, the Hall elements 11 are arranged in the same way as in the above embodiment, within a range from a position 3B away from the radially inner end of the permanent magnet 4 (see arrow 34) to a position 3B away from the radially outer end of the permanent magnet 4 (see arrow 35), relative to the width (radial length) B of the permanent magnet. Similarly, the positions of the Hall elements 11 in the axial direction are arranged within a range from the axially upper end of the permanent magnet 4 to a position 3B away from that end (see arrow 36). It is desirable that the positions of the Hall elements 11 in the axial direction do not exceed the height (axial length) of the winding 7.

[0058] In Modification 1, the height of the permanent magnet 4 is preferably within a range where, given that the size of the gap (air gap) between the rotor 5 and the stator 6 is A, the height M of the permanent magnet 4 is lowered by adding twice the size of the air gap A to the height S of the stator 6 (teeth 6A), and uppered by multiplying the height S of the stator 6 (teeth 6A) by 1.3.

[0059] (Modified example 2 regarding the arrangement of the Hall element 11) The motor 2 described above in the embodiment described is an inner-rotor type permanent magnet synchronous motor in which the rotor 5 is installed radially inside the stator 6. The motor 2 according to this modification will be described in an outer-rotor type permanent magnet synchronous motor in which the rotor 5 is installed radially outside the stator 6.

[0060] Figure 11 is a schematic diagram showing an example of the configuration of the motor 2 in Modification 2. As an example, as shown in Figure 11, the motor 2 according to Modification 2 includes a rotor 5 which comprises a rotor core 3 and permanent magnets 4 installed radially inside the rotor core 3. The stator 6 is composed of teeth 6A provided radially inside the rotor core 3 and windings (coils) 7 wound around the teeth 6A. In other words, in the motor 2 according to this embodiment, the stator 6, permanent magnets 4, and rotor core 3 are installed in that order radially from the center of the motor 2.

[0061] In Modification 2, the Hall element 11 is arranged in the same manner as in the above embodiment, within a range from a position 3B away from the radially inner end of the permanent magnet 4 (see arrow 37) to a position 3B away from the radially outer end (see arrow 38) with respect to the width (radial length) B of the permanent magnet.

[0062] (Modified example 3 regarding the arrangement of Hall elements 11) The motor 2 in the above embodiment was described as a radial gap type permanent magnet synchronous motor in which the permanent magnets 4 are installed so that the direction of the magnetic field is radial. The motor 2 according to this modification will be described as an axial gap type permanent magnet synchronous motor in which the permanent magnets 4 are installed so that the direction of the magnetic field is axial.

[0063] Figure 12 is a schematic diagram showing an example of the configuration of the motor 2 in Modification 3. As an example, as shown in Figure 12, the motor 2 according to Modification 3 includes a rotor 5 which comprises a rotor core 3 of the drive unit and a permanent magnet 4 on the axial upper side of the rotor core 3. The stator 6 also includes teeth 6A provided on the axial upper side of the rotor core 3 and windings (coils) 7 wound around the teeth 6A.

[0064] In Modification 3, the Hall elements 11 are arranged in the same way as in the above embodiment, in the axial direction with respect to the height (axial length) B of the permanent magnet 4, from a position 3B away from the upper axial end of the permanent magnet 4 (see arrow 39) to a position 3B away from the lower axial end of the permanent magnet 4 (see arrow 40). Similarly, the Hall elements 11 in the radial direction are arranged in the range from the radial inner end of the permanent magnet 4 to a position 3B away from that end. It is desirable that the position of the Hall elements 11 in the axial direction does not exceed the width (radial length) of the winding 7.

[0065] Here, the Hall element 11 can be positioned both radially inside and radially outside of the stator 6. When the Hall element 11 is positioned radially inside the stator 6, the range of positions for the Hall element 11 is from a position 3B away from the axially upper end of the permanent magnet 4 (see arrow 41) to the rotor 5. In the radial direction, the position of the Hall element 11 is from a position 3B away from the radially inside end of the permanent magnet 4.

[0066] As described above, according to the above embodiment, when two orthogonal component signals with respect to the electrical angle are generated, the error between the calculated rotation angle and the actual rotation angle of the object to be detected can be suppressed.

[0067] Furthermore, according to the above embodiment, waveform distortion contained in the signal can be removed by deriving the difference of the detected signal. In addition, noise received from the outside can be removed by deriving the difference of the detected signal.

[0068] Furthermore, according to the above embodiment, by detecting the leakage magnetic flux of the permanent magnet 4 installed in the motor 2, it is not necessary to install a magnet for detecting the rotation angle, and the Hall element 11 can be miniaturized.

[0069] Furthermore, according to the above embodiment, by increasing the height of the permanent magnet 4, the distance between the stator 6 and the Hall element 11 increases, and the influence of the magnetic flux from the stator 6 (winding 7) can be suppressed.

[0070] Furthermore, according to the above embodiment, by installing the Hall element 11 between the stators 6, the influence of magnetic flux from the stators 6 (windings 7) can be suppressed.

[0071] Furthermore, although the above-described embodiment describes a configuration in which the rotation angle calculation program is installed in ROM 14, the invention is not limited to this configuration. The rotation angle calculation program according to this disclosure can also be provided in a form recorded on a computer-readable storage medium. For example, the rotation angle calculation program according to this disclosure may be provided in a form recorded on an optical disc such as a CD (Compact Disc)-ROM or DVD (Digital Versatile Disc)-ROM. Alternatively, the rotation angle calculation program according to this disclosure may be provided in a form recorded on a semiconductor memory such as a USB (Universal Serial Bus) memory or memory card. Moreover, the rotation angle calculation device 10 may download the rotation angle calculation program according to this disclosure from an external device connected to a communication line (not shown) via a communication line (not shown).

[0072] The control unit and method described herein may be implemented by a dedicated computer comprising a processor programmed to execute one or more functions embodied by a computer program. Alternatively, the apparatus and method described herein may be implemented by a dedicated computer comprising a processor composed of dedicated hardware logic circuits. Alternatively, the apparatus and method described herein may be implemented by one or more dedicated computers comprising a combination of a processor that executes a computer program and one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium. [Explanation of symbols]

[0073] 1. Rotation Angle Calculation System 2 motors 3 rotor cores 4 Permanent Magnets 5 rotors 6 staters 6A Teeth 6B slot 7. Winding (coil) 10. Rotation Angle Calculation Device 11, 11A, 11B, 11C Hall elements 12 Control Unit 13 ROM 14 RAM 15 Input / Output Interfaces 16 AD conversion circuit 19 bus 21 Acquisition Department 22 Generation part 23 Calculation Section

Claims

1. A rotation angle calculation device that calculates the rotation angle of the object to be detected, A motor having a stator (6) around which windings are wound, and a rotor (5) on which permanent magnets (4) are installed, Equipped with, The rotation angle calculation device is, An acquisition unit (21) acquires detection results from three detection elements (11) positioned at an electrical angle shift of 120 degrees relative to the permanent magnet, which detect leakage magnetic flux generated from the permanent magnet. A generation unit (22) generates an orthogonal component signal that shows two orthogonal components representing the strength of the leakage magnetic flux, using the three detection results obtained, A calculation unit (23) calculates the rotation angle of the object to be detected using the orthogonal component signal, Equipped with, The detection element is positioned in a location where it can detect the leakage magnetic flux generated from the permanent magnet installed between the stator and the rotor. A rotation angle calculation system in which, when the axial length of the permanent magnet is M, the axial length of the stator is S, and the radial gap between the permanent magnet and the stator is A, the rotation angle is expressed as S + 2A ≤ M ≤ 1.3S.

2. The acquisition unit acquires signals U, V, and W, each having a phase difference of 120 degrees, as the detection result. The generation unit generates an orthogonal component signal X obtained from U-V and an orthogonal component signal Y obtained from U+V-2W. The rotation angle calculation system according to claim 1.

3. The detection element is positioned in a range from a position 3B away from one end of the permanent magnet to a position 3B away from the other end, assuming that B is the radial width of the permanent magnet. The rotation angle calculation system according to claim 1.

4. The detection element is further arranged in a range up to a position 3B away from the end of the permanent magnet in the axial direction. The rotation angle calculation system according to claim 3.

5. The detection element is positioned in the axial direction within a range that does not exceed the range of the windings wound around the stator. The rotation angle calculation system according to claim 4.

6. The detection element is positioned in the axial direction of the permanent magnet, from a position 3B away from one end to a position 3B away from the other end, assuming that B is the axial height of the permanent magnet. The rotation angle calculation system according to claim 1.

7. The detection element is further arranged in a range up to a position 3B away from the end of the permanent magnet in the radial direction. The rotation angle calculation system according to claim 6.

8. A rotation angle calculation device that calculates the rotation angle of the object to be detected, A motor (2) is provided, which includes a stator (6) around which windings are wound, and a rotor (5) on which permanent magnets (4) embedded in the rotor core are installed. Equipped with, The rotation angle calculation device is, An acquisition unit (21) acquires detection results from three detection elements (11) positioned at an electrical angle shift of 120 degrees relative to the permanent magnet, which detect leakage magnetic flux generated from the permanent magnet. A generation unit (22) generates an orthogonal component signal that shows two orthogonal components representing the strength of the leakage magnetic flux, using the three detection results obtained, A calculation unit (23) calculates the rotation angle of the object to be detected using the orthogonal component signal, Equipped with, The detection element is positioned in a location where it can detect the leakage magnetic flux generated from the permanent magnet installed between the stator and the rotor. A rotation angle calculation system expressed as S + 2A ≤ M ≤ 1.3S, where M is the axial length of the rotor core as the axial center of the rotor, S is the axial length of the stator, and A is the size of the radial gap between the rotor core and the stator.

9. The detection element is positioned in the radial direction of the motor between adjacent windings wound around the stator. A rotation angle calculation system according to any one of claims 1 to 8.

10. The object to be detected for rotation angle is the stator (6) around which the windings are wound, and the motor (2) is equipped with a rotor (5) on which permanent magnets (4) are installed. From three detection elements positioned at a position where the electrical angle is shifted by 120 degrees with respect to one of the permanent magnets, detection results are obtained for each detection element that detects the leakage magnetic flux generated from the permanent magnet. Using the three detection results obtained, an orthogonal component signal is generated that shows two orthogonal components representing the strength of the leakage magnetic flux. The rotation angle of the motor is calculated using the orthogonal component signal. Let the computer perform the process, The detection element is positioned in a location where it can detect the leakage magnetic flux generated from the permanent magnet installed between the stator and the rotor. A method for calculating the rotation angle expressed as S + 2A ≤ M ≤ 1.3S, where M is the axial length of the permanent magnet, S is the axial length of the stator, and A is the size of the radial gap between the permanent magnet and the stator.

11. At least one processor, The object to be detected for rotation angle is the stator (6) around which the windings are wound, and the rotor of the motor is equipped with permanent magnets (4). Three detection elements are positioned at a position where the electrical angle is shifted by 120 degrees with respect to one of the permanent magnets of the motor, and detection results are obtained from each of these detection elements to detect the leakage magnetic flux generated from the permanent magnet. Using the three detection results obtained, an orthogonal component signal is generated that shows two orthogonal components representing the strength of the leakage magnetic flux. The rotation angle of the motor is calculated using the orthogonal component signal. Execute the process, The detection element is positioned in a location where it can detect the leakage magnetic flux generated from the permanent magnet installed between the stator and the rotor. A rotation angle calculation program where S + 2A ≤ M ≤ 1.3S, where M is the axial length of the permanent magnet, S is the axial length of the stator, and A is the size of the radial gap between the permanent magnet and the stator.

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