Rotary machine and detection method for displacement in rotation axis direction of rotor in rotary machine

Abstract

To detect not only a rotation angle of a rotor but also a displacement of the rotor in a rotation axis direction by using only a Hall sensor.SOLUTION: Disclosed is a rotating machine comprising: a rotor having a plurality of magnetic poles; a motor stator having a plurality of stator coils; a plurality of Hall sensors provided on the motor stator and outputting voltage signals corresponding to magnetic fields from the rotor; and a controller configured to determine the rotation angle of the rotor based on the voltage signals from the plurality of Hall sensors, further configured to calculate a voltage proportional to the axial displacement of the rotor based on the voltage signals from the plurality of Hall sensors, and to determine the axial displacement of the rotor based on the calculated voltage.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a rotary machine and a method for detecting displacement of a rotor in a rotary machine in the direction of a rotation axis. [Background technology]

[0002] In rotating machines such as brushless motors, it is important to detect the rotation angle of the rotor and the displacement of the rotor in the direction of the rotation axis in order to control the rotation of the motor. Conventionally, a Hall sensor has been used to detect the rotation angle of the rotor (see, for example, Patent Document 1), and an eddy current sensor has been used to detect the displacement of the rotor in the direction of the rotation axis. In addition, a method of detecting the displacement of the rotor in the direction of the rotation axis is known in which the amount of displacement is calculated from the change in the current flowing in a magnetic circuit (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-207779 A [Patent Document 2] JP 2019-152593 A Summary of the Invention [Problem to be solved by the invention]

[0004] Regarding detection of the displacement of the rotor in the direction of the rotation axis, there is a problem that the eddy current sensor is expensive. In addition, the eddy current sensor and the magnetic circuit of Patent Document 2 require space for installation, which limits the degree of freedom in the design layout of the device. Therefore, it is desirable to detect not only the rotation angle of the rotor but also the displacement of the rotor in the direction of the rotation axis using only Hall sensors. [Means for solving the problem]

[0005] [Form 1] According to Form 1, there is provided a rotating machine comprising: a rotor having a plurality of magnetic poles; a motor stator having a plurality of stator coils; a plurality of Hall sensors provided on the motor stator and outputting voltage signals corresponding to a magnetic field from the rotor; and a controller configured to determine a rotation angle of the rotor based on the voltage signals from the plurality of Hall sensors, and further configured to calculate a voltage proportional to a displacement of the rotor in the direction of the rotation axis based on the voltage signals from the plurality of Hall sensors, and to determine the displacement of the rotor in the direction of the rotation axis based on the calculated voltage.

[0006] [Feature 2] According to feature 2, in the rotating machine of feature 1, the controller is configured to calculate the voltage proportional to the axial displacement of the rotor as the square root of the sum of the squares of the voltage signals from the multiple Hall sensors.

[0007] [Form 3] According to form 3, in the rotating machine of form 1 or 2, the plurality of Hall sensors include a plurality of Hall sensor pairs arranged opposite each other, and the controller is configured to average voltage signals from the Hall sensor pairs.

[0008] [Feature 4] According to feature 4, in the rotating machine of feature 1 or 2, the controller is configured to perform correction to align the amplitudes of the voltage signals from the different Hall sensors.

[0009] [Feature 5] According to feature 5, in the rotating machine of feature 1 or 2, the controller , and is configured to perform a correction for aligning the phase difference of the voltage signals from the different Hall sensors.

[0010] [Form 6] According to Form 6, in the rotating machine of Form 1 or 2, the voltage signals from the plurality of Hall sensors are three-phase signals, and the controller is configured to convert the three-phase signals into two-phase signals.

[0011] [Form 7] According to Form 7, in the rotating machine of Form 1, the plurality of Hall sensors include a plurality of Hall sensor pairs arranged opposite each other, and the voltage signals from the plurality of Hall sensors are three-phase signals, and the controller is configured to average the voltage signals from the Hall sensor pairs and perform correction to align the amplitudes and phase differences of the averaged voltage signals from different Hall sensor pairs, convert the averaged and corrected three-phase signals into two-phase signals, calculate the square root of the sum of the squares of the two-phase signals, and determine the displacement of the rotor in the rotational axis direction by multiplying the square root of the sum of the squares of the two-phase signals by a predetermined proportionality coefficient and adding a predetermined constant.

[0012] [Feature 8] According to feature 8, in the rotating machine of feature 7, the controller is configured to calculate the rotation angle of the rotor based on the two-phase signals.

[0013] [Form 9] According to Form 9, there is provided a method for detecting a displacement of a rotor in the direction of the rotational axis in a rotating machine, the rotating machine comprising a rotor having a plurality of magnetic poles, a motor stator having a plurality of stator coils, and a plurality of Hall sensors provided on the motor stator and outputting voltage signals corresponding to a magnetic field from the rotor, the detection method including the steps of calculating a voltage proportional to a displacement of the rotor in the direction of the rotational axis based on the voltage signals from the plurality of Hall sensors, and determining the displacement of the rotor in the direction of the rotational axis based on the calculated voltage. [Brief description of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view showing an embodiment of a rotary machine (pump device). [Figure 2A] FIG. 2 is a plan view showing one embodiment of a motor stator. [Figure 2B] FIG. 2 is a plan view showing one embodiment of a rotor. [Figure 2C] FIG. 11 is a plan view showing another embodiment of a motor stator. [Figure 2D] FIG. 11 is a plan view showing another embodiment of a motor stator. [Diagram 3] FIG. 2 is a functional block diagram of a controller 30. [Figure 4] 1A to 1C are diagrams illustrating exemplary signals in a process for detecting a rotation angle and a rotational axial displacement of a rotor. [Diagram 5] 1 is a graph showing the relationship between the rotor's rotational axis direction displacement Δz and voltage vz. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings described below, the same or corresponding components are designated by the same reference numerals and redundant description will be omitted.

[0016] FIG. 1 is a cross-sectional view of a pump device according to an embodiment of the present invention. The pump device includes a motor pump 50 in which a motor and a pump are integrally configured. The pump device and the motor included in the pump device are an example of a rotating machine. Hereinafter, an embodiment of the present invention will be described with reference to a pump device, but the present invention is not limited to the pump device, and can be applied to rotating machines other than the pump device (for example, a motor alone, a fan, a compressor, etc.) without departing from the gist of the present invention.

[0017] The motor pump 50 shown in FIG. 1 is a canned motor equipped with an axial gap type PM motor. 1, the motor pump 50 includes an impeller 1 in which multiple permanent magnets 5 are embedded, a motor stator 6 that generates a magnetic force acting on these permanent magnets 5, a pump casing 2 that houses the impeller 1, a motor casing 3 that houses the motor stator 6, an end cover 4 that closes the open end of the motor casing 3, and a bearing assembly 10 that supports the radial load and thrust load of the impeller 1.

[0018] The motor stator 6 and the bearing assembly 10 are disposed on the suction side of the impeller 1. In this embodiment, a plurality of permanent magnets 5 are provided, but the present invention is not limited to this embodiment, and a single permanent magnet having a plurality of magnetized poles may be used. Specifically, a single annular permanent magnet having a plurality of magnetic poles, in which the south poles and north poles are alternately magnetized, may be used.

[0019] An O-ring 9 serving as a seal member is provided between the pump casing 2 and the motor casing 3. By providing the O-ring 9, leakage of liquid from between the pump casing 2 and the motor casing 3 can be prevented.

[0020] A suction port 15 having a suction port 15a is connected in a liquid-tight manner to the motor casing 3. This suction port 15 has a flange shape and is connected to a suction line (not shown). Liquid flow paths 15b, 3a, and 10a are formed in the center of the suction port 15, the motor casing 3, and the bearing assembly 10, respectively. These liquid flow paths 15b, 3a, and 10a are connected in a row to form a single liquid flow path extending from the suction port 15a to the liquid inlet of the impeller 1. The liquid flow paths 15b, 3a, and 10a are connected to the liquid inlet of the impeller 1.

[0021] The motor pump 50 according to this embodiment is a canned motor pump equipped with an axial gap type PM motor in which a permanent magnet 5 and a motor stator 6 are arranged along these liquid flow paths 15b, 3a, and 10a.

[0022] A discharge port 16 having a discharge port 16a is provided on the side surface of the pump casing 2, and the liquid pressurized by the rotating impeller 1 is discharged through the discharge port 16a. The motor pump 50 according to this embodiment is a so-called end-top type motor pump in which the suction port 15a and the discharge port 16a are perpendicular to each other.

[0023] The impeller 1 is made of a non-magnetic material that is slippery and resistant to wear. For example, resins such as PTFE (polytetrafluoroethylene) and PPS (polyphenylene sulfide) or ceramics are preferably used. The pump casing 2 and the motor casing 3 (including the end cover 4) can also be made of the same material as the impeller 1.

[0024] The impeller 1 is rotatably supported by a single bearing assembly 10. This bearing assembly 10 is a sliding bearing (dynamic pressure bearing) that utilizes the dynamic pressure of a fluid. This bearing assembly 10 is composed of a combination of a rotating side bearing 11 and a fixed side bearing 12 that are loosely engaged with each other. The rotating side bearing 11 is fixed to the impeller 1 and is arranged so as to surround the fluid inlet of the impeller 1. The fixed side bearing 12 is fixed to the motor casing 3 and is arranged on the suction side of the rotating side bearing 11. This fixed side bearing 12 has a cylindrical portion 13 and a flange portion 14 that protrudes outward from the cylindrical portion 13. The cylindrical portion 13 extends in the axial direction of the rotating side bearing 11. The cylindrical portion 13 and the flange portion 14 are integrally configured.

[0025] The cylindrical portion 13 has a radial surface (outer peripheral surface) 12a that supports the radial load of the impeller 1, and the flange portion 14 has a thrust surface (side surface) 12b that supports the thrust load of the impeller 1. The radial surface 12a is parallel to the axis of the impeller 1, and the thrust surface 12b is perpendicular to the axis of the impeller 1. The rotating side bearing 11 is disposed around the cylindrical portion 13 of the fixed side bearing 12.

[0026] The rotating side bearing 11 has an inner surface 11a facing the radial surface 12a of the fixed side bearing 12, an outer surface 11b opposite to the inner surface 11a, and a side surface 11c extending between the inner surface 11a and the outer surface 11b. The side surface 11c of the rotating side bearing 11 faces the thrust surface 12b of the fixed side bearing 12. A small gap is formed between the inner surface 11a of the rotating side bearing 11 and the radial surface 12a, and between the side surface 11c of the rotating side bearing 11 and the thrust surface 12b. A seal member (not shown) is provided between the rotating side bearing 11 and the impeller 1, and the rotating side bearing 11 is fixed to the impeller 1 in a liquid-tight manner. Similarly, a seal member (not shown) is provided between the fixed side bearing 12 and the motor casing 3, and the fixed side bearing 12 is fixed to the motor casing 3 in a liquid-tight manner.

[0027] A portion of the fluid discharged from the impeller 1 is guided to the bearing assembly 10 through a small gap between the impeller 1 and the motor casing 3. When the rotating-side bearing 11 rotates together with the impeller 1, dynamic pressure of the fluid is generated between the rotating-side bearing 11 and the fixed-side bearing 12, and as a result, the impeller 1 is supported in a non-contact manner by the bearing assembly 10. The fixed-side bearing 12 supports the rotating-side bearing 11 by a radial surface 12a and a thrust surface 12b that are perpendicular to each other, so that tilting of the impeller 1 is restricted by the bearing assembly 10.

[0028] The motor stator 6 has a stator core 6A and a plurality of stator coils 6B. The plurality of stator coils 6B are arranged in an annular shape. The impeller 1 and the motor stator 6 are arranged concentrically with the bearing assembly 10 and the suction port 15a.

[0029] Lead wires 25 are connected to the stator coil 6B, and a connector 27 is attached to the outer surface of the motor casing 3. The stator coil 6B is connected to an inverter device 26 via the lead wires 25 and the connector 27. The inverter device 26 is connected to a power source 28.

[0030] This inverter device 26 supplies a current to the stator coil 6B of the motor stator 6, generating a rotating magnetic field in the motor stator 6. This rotating magnetic field acts on the permanent magnets 5 embedded in the impeller 1, driving the impeller 1 to rotate. The torque of the impeller 1 depends on the magnitude of the current supplied to the motor stator 6. As long as the load on the impeller 1 is constant, the current supplied to the motor stator 6 is approximately constant.

[0031] When the impeller 1 rotates, liquid is introduced into the liquid inlet of the impeller 1 from the suction port 15a. The liquid is pressurized by the rotation of the impeller 1 and is discharged from the discharge port 16a. While the impeller 1 is transporting the liquid, the back surface of the impeller 1 is pressed toward the suction side (i.e., toward the suction port 15a) by the pressurized liquid. The bearing assembly 10 is disposed on the suction side of the impeller 1 and therefore supports the thrust load of the impeller 1 from the suction side.

[0032] FIG. 2A is a plan view showing one embodiment of the motor stator 6, and shows the motor stator 6 viewed from a direction parallel to the rotation axis of the impeller 1 (i.e., from the right or left direction in FIG. 1). In this example, the motor stator 6 includes six stator coils 6B1 to 6B6 arranged at 60 degree intervals along the circumferential direction of the stator core 6A. These six stator coils 6B1 to 6B6 are connected to the inverter device 26 as described above. A U-phase sine wave current is supplied from the inverter device 26 to the stator coil 6B1 and the stator coil 6B4 arranged opposite the stator coil 6B1, a V-phase sine wave current is supplied from the inverter device 26 to the stator coil 6B2 and the stator coil 6B5 arranged opposite the stator coil 6B2, and a W-phase sine wave current is supplied from the inverter device 26 to the stator coil 6B3 and the stator coil 6B6 arranged opposite the stator coil 6B3. This generates a rotating magnetic field for driving the impeller 1 to rotate.

[0033] The motor stator 6 further includes a plurality of Hall sensors 6C. For example, as shown in Fig. 2A, a total of six Hall sensors 6C1 to 6C6 are arranged, one between each of the adjacent stator coils 6B, i.e., at 60 degree intervals along the circumferential direction of the stator core 6A. Each of the Hall sensors 6C1 to 6C6 is connected to the controller 30 and outputs a voltage signal proportional to a magnetic field from a permanent magnet (hereinafter referred to as a rotor) 5 provided in the impeller 1 to the controller 30.

[0034] 2B is a plan view showing one embodiment of the rotor 5 provided in the impeller 1, showing the rotor 5 viewed from a direction parallel to the rotation axis of the impeller 1. The rotor 5 in this example is composed of a ring-shaped magnet concentric with the impeller 1, and has eight magnetic poles in which S poles and N poles are alternately arranged along the circumferential direction of the ring (i.e., the number of poles is eight, and the number of pole pairs is four). Therefore, the voltage signal output from each of the Hall sensors 6C1 to 6C6 is a signal having four periods during one rotation of the impeller 1.

[0035] The configuration of the motor stator 6 and the rotor 5 is not limited to the example of Fig. 2A and 2B. The number of stator coils 6B and Hall sensors 6C in the motor stator 6 and the number of magnetic poles in the rotor 5 may be arbitrary. For example, the motor stator 6 may include six stator coils 6B and four Hall sensors 6C as shown in Fig. 2C, or may include twelve stator coils 6B and twelve Hall sensors 6C as shown in Fig. 2D.

[0036] Hereinafter, embodiments of the present invention will be further described with respect to example configurations of motor stator 6 and rotor 5 shown in Figures 2A and 2B.

[0037] Fig. 3 is a functional block diagram of the controller 30 for detecting the rotation angle and the displacement in the direction of the rotation axis of the rotor 5. Fig. 4 is a diagram showing exemplary signals at each stage of the process of detecting the rotation angle and the displacement in the direction of the rotation axis of the rotor 5.

[0038] The voltage signals v1 to v6 from the Hall sensors 6C1 to 6C6 are input to a differential calculation unit 31. The differential calculation unit 31 averages the signals from the Hall sensors arranged at opposing positions (i.e., the Hall sensors 6C1 and 6C4, the Hall sensors 6C2 and 6C5, and the Hall sensors 6C3 and 6C6) according to the following equation (1), and outputs a differential signal v a , v b , v c Output.

[0039]

number

[0040] Here, the Hall sensors 6C1 to 6C6 are arranged at 60 degree intervals along the circumferential direction of the stator core 6A, so that the voltage signals v1 to v6 from the Hall sensors 6C1 to 6C6 are shifted in phase from each other by 60 degrees, as shown in FIG. 4(A). Also, the rotor 5 has eight poles (four pole pairs), and the magnetic poles are arranged point-symmetrically, so that the voltage signals (e.g., v1 and v4) from the Hall sensors arranged at opposing positions have the same phase, as shown in FIG. 4(A). Therefore, by using the above formula (1), the signal v a , v b , v c Generally, the number of pole pairs of the rotor 5 is even. On the other hand, when the number of pole pairs of the rotor 5 is odd, the S poles and N poles are arranged line-symmetrically, so the output signals of the Hall sensors at the opposing positions have opposite phases. Therefore, by using the following equation (2) instead of equation (1), the differential signal v a , v b , v c can be sought.

[0041]

number

[0042] In this way, by averaging the output signals from the Hall sensors arranged in opposing positions, the effects of eccentricity between the motor stator 6 and rotor 5 (misalignment between the center of the motor stator 6 and the center of rotation of the rotor 5) can be canceled, improving the position accuracy of the rotor 5 calculated in processing from this step onwards.

[0043] The Hall sensor 6C outputs a voltage signal proportional to the magnetic field, but the magnetic field detection sensitivity, i.e., the magnitude of the voltage value output for a magnetic field of the same magnitude, may vary from one Hall sensor to another. Also, differences in the voltage values ​​output from each Hall sensor 6C may occur if the mounting positions of the Hall sensors 6C on the motor stator 6 vary in the radial direction of the motor stator 6 (i.e., the distance between each Hall sensor 6C and the rotor 5 varies). The gain / offset adjustment unit 32 corrects for these effects (gain correction) according to the following equation (3), and outputs the corrected differential signal v a ',v b ',v c ' is calculated.

[0044]

number

[0045] Here, a, b, and c are correction coefficients that take into account individual differences in detection sensitivity of the Hall sensors and / or variations in mounting position in the radial direction, and can be obtained in advance by measurement or the like.

[0046] Furthermore, if the mounting positions of the Hall sensors 6C on the motor stator 6 are shifted in the circumferential direction of the motor stator 6 (i.e., the arrangement intervals of the Hall sensors 6C are no longer equal (60 degrees)), the voltage signals v1 to v6 (and the differential signal v a ~v c) also deviates from 60 degrees. The gain / offset adjustment unit 32 may perform a correction (offset correction) to correct this phase shift, in addition to the gain correction described above. FIG. 4B shows a differential signal v a ',v b ',v c Thus, the corrected differential signal v a ',v b ',v c ' have nearly equal amplitudes and the phase between the signals is nearly 60 degrees.

[0047] In an ideal case where there is no individual difference in the detection sensitivity of each Hall sensor 6C and no error in the mounting position thereof, the processing of the gain / offset adjustment unit 32 may be omitted.

[0048] The three-phase to two-phase converter 33 converts the corrected differential signal v a ',v b ',v c ' is converted from three-phase to two-phase according to the following equation (4), and the two-phase signal v α , v β Calculate the following: Figure 4(C) Then, the calculated signal v α , v β In addition, when the motor stator 6 is configured to include a number of Hall sensors 6C different from that in FIG. 2A (see FIGS. 2C and 2D), an appropriate coordinate conversion formula may be used instead of formula (4).

[0049]

number

[0050] As shown in Figure 4(C), the two-phase signal v α , v β are sinusoidal signals with a phase difference of 90 degrees, so the ratio v β / v α is a signal that represents the tangent of the rotation angle θ of the rotor 5. Therefore, the arctangent calculation unit 34 calculates the ratio v of the two-phase signals as shown in the following equation (5).β / v α The rotation angle θ of the rotor 5 can be calculated using the arc tangent of

[0051]

number

[0052] Here, the amplitude of the voltage signals v1 to v6 from each Hall sensor (see FIG. 4(A)) depends on the displacement of the rotor 5 in the rotational axis direction. Specifically, when the impeller 1 (rotor 5) is displaced along its rotation axis in a direction approaching the motor stator 6, the distance between each Hall sensor 6C1 to 6C6 and the rotor 5 becomes uniformly smaller, and the amplitude of the voltage signals v1 to v6 increases. On the other hand, when the impeller 1 is displaced in the opposite direction (a direction away from the motor stator 6), the distance between each Hall sensor and the rotor 5 becomes greater, and the amplitude of the voltage signals v1 to v6 decreases. Then, in response to such amplitude changes of the voltage signals v1 to v6, the two-phase signal v α , v β Therefore, the square root sum calculation unit 35 calculates the amplitude of the two-phase signal v as shown in the following equation (6). α , v β By calculating the square root of the sum of the squares of z can be sought.

[0053]

number

[0054] FIG. 5 shows the relationship between the displacement Δz of the rotor 5 in the direction of the rotation axis and the voltage v calculated according to the above equation (6). z 5 is a graph showing the relationship between the rotational axis direction displacement Δz and the voltage v. For example, the graph in FIG. 5 can be obtained in advance by experiment. Note that the rotational axis direction displacement Δz is positive when the rotor 5 moves away from the motor stator 6. The reference position of the rotational axis direction displacement Δz (i.e., the position where Δz=0) is arbitrary, but for example, the displacement when the rotor 5 is stopped can be set to 0. The relationship between the rotational axis direction displacement Δz and the voltage v zThe relational expression can be expressed as the following equation (7).

[0055]

number

[0056] Here, k and C are constants determined experimentally from the graph in Figure 5. The displacement calculation unit 36 ​​calculates the voltage v z From this, the displacement Δz in the direction of the rotation axis can be calculated.

[0057] As described above, according to the embodiment of the present invention, by utilizing the output signal from the Hall sensor, it is possible to calculate not only the rotation angle θ of the rotor 5 but also the displacement Δz in the direction of the rotation axis of the rotor 5. Therefore, by eliminating the need for an eddy current sensor, it is possible to reduce the cost of the device and improve the freedom of design layout.

[0058] Although the embodiments of the present invention have been described above based on several examples, the above-mentioned embodiments of the present invention are intended to facilitate understanding of the present invention and do not limit the present invention. The present invention may be modified or improved without departing from the spirit thereof, and the present invention naturally includes its equivalents. Furthermore, any combination or omission of each component described in the claims and specification is possible within the scope of solving at least a part of the above-mentioned problems or achieving at least a part of the effects. [Explanation of symbols]

[0059] 1 Impeller 2 Pump casing 3 Motor casing 3a Liquid flow path 4 End cover 5 Permanent magnet (rotor) 6 Motor stator 6A Stator Core 6B Stator coil 6C Hall Sensor 9 O-ring 10 Bearing assembly 10a Liquid flow path 11 Rotating bearing 12 Fixed side bearing 12a Radial surface 12b Thrust surface 13 Cylindrical section 14 Flange 15 Suction port 15a Intake port 15b Liquid flow path 16 Discharge port 16a Discharge port 25 Lead Wire 26 Inverter device 27 Connectors 28 Power supply 30 Controller 31 Differential calculation section 32 Gain / Offset Adjustment Section 33 Three-phase to two-phase converter 34 Arctangent calculation section 35 Sum of Squares Square Root Calculation Section 36 Rotation axis direction displacement calculation section 50 Motor pump

Claims

1. A rotor having a plurality of magnetic poles; a motor stator having a plurality of stator coils; a plurality of Hall sensors provided on the motor stator and outputting voltage signals corresponding to the magnetic field from the rotor; a controller configured to determine a rotation angle of the rotor based on voltage signals from the plurality of Hall sensors, and further configured to calculate a voltage proportional to a displacement of the rotor in the direction of the rotation axis based on the voltage signals from the plurality of Hall sensors, and to determine the displacement of the rotor in the direction of the rotation axis based on the calculated voltage; A rotating machine comprising:

2. The rotating machine of claim 1 , wherein the controller is configured to calculate the voltage proportional to the axial displacement of the rotor as a square root of the sum of the squares of the voltage signals from the plurality of Hall sensors.

3. The plurality of Hall sensors include a plurality of Hall sensor pairs arranged opposite each other, The controller is configured to average voltage signals from the pair of Hall sensors. The rotary machine according to claim 1 or 2.

4. The rotating machine according to claim 1 or 2, wherein the controller is configured to perform correction to align amplitudes of voltage signals from different Hall sensors.

5. The rotating machine according to claim 1 or 2, wherein the controller is configured to perform a correction to align a phase difference of the voltage signals from different Hall sensors.

6. the voltage signals from the plurality of Hall sensors are three-phase signals; The controller is configured to convert the three-phase signal to a two-phase signal. The rotary machine according to claim 1 or 2.

7. The plurality of Hall sensors include a plurality of Hall sensor pairs arranged opposite each other, the voltage signals from the plurality of Hall sensors are three-phase signals; The controller: Averaging the voltage signals from the pair of Hall sensors; performing a correction to align the amplitude and phase difference of the averaged voltage signals from different pairs of Hall sensors; converting the averaged and corrected three-phase signal into a two-phase signal; Calculating the square root of the sum of the squares of the two-phase signals; determining a displacement of the rotor in the direction of the rotation axis by multiplying the square root of the sum of the squares of the two-phase signals by a predetermined proportional coefficient and adding the result to a predetermined constant; The rotary machine according to claim 1 , configured as follows:

8. The rotating machine of claim 7 , wherein the controller is configured to calculate the rotation angle of the rotor based on the two-phase signal.

9. A method for detecting a displacement of a rotor in a rotating machine in a direction of a rotation axis, comprising: The rotating machine includes: A rotor having a plurality of magnetic poles; a motor stator having a plurality of stator coils; a plurality of Hall sensors provided on the motor stator and outputting voltage signals in response to a magnetic field from the rotor; The detection method includes: calculating a voltage proportional to a displacement of the rotor in the rotational axis direction based on voltage signals from the plurality of Hall sensors; determining a displacement of the rotor in the direction of a rotation axis based on the calculated voltage; A detection method comprising:

Images