Motor control device and motor

Abstract

The invention provides a motor control device and a motor. The motor control device controls a motor, and includes: a calculation unit that calculates angle information related to a rotation angle of a rotor of the motor on the basis of an output from a magnetic sensor; and a correction unit that corrects the angle information calculated by the calculation unit. The magnetic sensor is provided with a magnetoresistive effect element and outputs signals of two systems, the phases of which are shifted by 180 degrees from each other. The correction unit corrects the angle information using a correction amount represented by a function including a current value of a motor current supplied to a stator of the motor, a phase angle of the motor current, a current value of a power supply current supplied to the motor control device, and a mechanical angle of the rotor calculated from an output from the magnetic sensor.

Description

Technical Field

[0001] The invention relates to a motor control device and a motor. Background Art

[0002] Conventionally, there is known a motor that detects the position of a rotor using a sensor magnet and a sensor (for example, Patent Document 1).

[0003] Patent Document 1: Japanese Patent Application Publication No. 2006-158059

[0004] In the above-mentioned motor, in order to improve the accuracy of detecting the rotational position of the rotor, a method of reducing the influence of the external magnetic field by using an MR (Magneto Resistive) sensor that outputs two systems of signals that are 180 degrees out of phase with each other is sometimes used. However, in this method, due to the offset of the position of the MR sensor and the deviation of the characteristics of the MR sensor, the influence of the external magnetic field may not be reduced sufficiently. Therefore, the accuracy of detecting the rotational position of the rotor may not be fully improved. Summary of the invention

[0005] The present invention has been made in view of the above circumstances, and one object of the present invention is to provide a motor control device and a motor capable of improving the detection accuracy of the rotational position of the rotor.

[0006] One embodiment of the present invention is a motor control device that controls a motor, wherein the motor control device has: a calculation unit that calculates angle information related to the rotation angle of the rotor of the motor based on the output from the magnetic sensor; and a correction unit that corrects the angle information calculated by the calculation unit. The magnetic sensor is a sensor that has a magnetoresistive effect element and outputs two systems of signals that are 180 degrees out of phase with each other. The correction unit corrects the angle information using a correction amount represented by a function including the current value of the motor current supplied to the stator of the motor and the phase angle of the motor current, the current value of the power supply current supplied to the motor control device, and the mechanical angle of the rotor calculated based on the output from the magnetic sensor.

[0007] One embodiment of the present invention is a motor, which has: the above-mentioned motor control device; the rotor, which can rotate around the central axis; the stator, which is opposite to the rotor in the radial direction with a gap therebetween; the sensor magnet, which is fixed to the rotor; the magnetic sensor, which is opposite to the sensor magnet in the axial direction with a gap therebetween; and a shielding member, which shields the magnetic flux. The motor control device has a substrate located on one axial side of the rotor. The shielding member has a cylindrical portion that surrounds the sensor magnet. The end of the cylindrical portion on one axial side contacts the surface of the substrate on the other axial side. The magnetic sensor is mounted on a portion of the surface of the substrate on the other axial side that is surrounded by the end of the cylindrical portion on one axial side.

[0008] According to one aspect of the present invention, in a motor control device and a motor, it is possible to improve the detection accuracy of the rotational position of a rotor. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a cross-sectional view showing a motor in one embodiment.

[0010] Figure 2 : is a circuit diagram showing a circuit configuration of a magnetic sensor in one embodiment.

[0011] Figure 3 This is a block diagram showing functional blocks of a motor control device in one embodiment.

[0012] Description of symbols

[0013] 16: connector part; 20: rotor; 23: bearing; 30: stator; 33a: conductive part; 40: shielding member; 41: cylindrical part; 50: motor control device; 51: substrate; 56: calculation part; 57: correction part; 60: sensor magnet; 70: magnetic sensor; 73, 73a, 73b, 73c, 73d: magnetoresistance effect element; 80: power supply terminal; 100: motor; I DC ,I m : current value; J: center axis; θ: rotation angle; θ e : electrical angle; θ f : Correction amount; θ Im : Phase angle; θ m : Mechanical angle. DETAILED DESCRIPTION

[0014] exist Figure 1The center axis J of the motor of the embodiment described below is hypothetically shown in the figure. In the following description, unless otherwise specified, the axial direction of the center axis J is referred to as the "axial direction", the radial direction centered on the center axis J is referred to as the "radial direction", and the circumferential direction centered on the center axis J is referred to as the "circumferential direction". The Z axis shown in each figure indicates the direction in which the center axis J extends. In the following description, the side (+Z side) to which the arrow of the Z axis in the axial direction points is referred to as the "upper side", and the side opposite to the side (-Z side) to which the arrow of the Z axis in the axial direction points is referred to as the "lower side".

[0015] In the following embodiments, the upper side corresponds to "one side in the axial direction", and the lower side corresponds to "the other side in the axial direction". In addition, the upper side and the lower side are merely names used to describe the relative positional relationship of each part, and the actual configuration relationship may also be a configuration relationship other than the configuration relationship represented by these names.

[0016] Figure 1 The motor 100 of the present embodiment shown in FIG. 1 is a mechatronic motor. The motor 100 of the present embodiment is a motor mounted on a steering device of a vehicle. The motor 100 is, for example, a three-phase motor. Figure 1 As shown, the motor 100 of this embodiment includes a housing 10, a rotor 20, a stator 30, a shielding member 40, a motor control device 50, a sensor magnet 60, a magnetic sensor 70, and a power terminal 80. The rotor 20 and the stator 30 constitute a motor body 100a.

[0017] The housing 10 accommodates the rotor 20 , the stator 30 , the shielding member 40 , the motor control device 50 , the sensor magnet 60 , the magnetic sensor 70 , and the power supply terminal 80 . The housing 10 includes a housing body 11 and a cover 12 .

[0018] The housing body 11 is a cylindrical component that is open on the upper side. The housing body 11 has a bottom wall portion 13, a first peripheral wall portion 14, and an extended wall portion 15. The bottom wall portion 13 is located on the lower side of the stator 30. The first peripheral wall portion 14 extends upward from the radial outer edge portion of the bottom wall portion 13. The first peripheral wall portion 14 is in the shape of a cylinder that is centered on the central axis J and is open on the upper side. The extended wall portion 15 extends from the upper end of the first peripheral wall portion 14 to one side in a direction perpendicular to the axial direction. Figure 1In the figure, the X-axis represents the direction in which the extension wall portion 15 extends. The side (+X side) to which the arrow of the X-axis points corresponds to the side in which the extension wall portion 15 extends relative to the first peripheral wall portion 14. In the following description, the direction in which the extension wall portion 15 extends is referred to as "extension direction X", the side (+X side) to which the arrow of the X-axis points in the extension direction X is referred to as "one side of the extension direction", and the side opposite to the side (-X side) to which the arrow of the X-axis points in the extension direction X is referred to as "the other side of the extension direction". In the present embodiment, the extension direction X is one direction in the radial direction.

[0019] The housing body 11 has a connector portion 16. That is, the motor 100 has a connector portion 16. The connector portion 16 protrudes downward from the end portion of the extension wall portion 15 on one side (+X side) of the extension direction. The connector portion 16 is in the shape of a tube that is open on the lower side. The connector portion 16 holds the power terminal 80. The power terminal 80 is a metal component that extends in the axial direction. The lower side portion of the power terminal 80 is exposed inside the connector portion 16. The power terminal 80 is electrically connected to a terminal of an external device connected to the connector portion 16. For example, a plurality of power terminals 80 are provided.

[0020] The cover body 12 is located on the upper side of the housing body 11. The cover body 12 has a cover wall portion 12a and a second peripheral wall portion 12b. The cover wall portion 12a is located on the upper side of the motor control device 50. The cover wall portion 12a covers the motor control device 50 from the upper side. The second peripheral wall portion 12b protrudes downward from the radial outer edge portion of the cover wall portion 12a. The second peripheral wall portion 12b is in the shape of a cylinder opened at the lower side. A flange portion 44 of the shielding member 40, which will be described later, is sandwiched between the second peripheral wall portion 12b and the housing body 11 in the axial direction.

[0021] The rotor 20 can rotate around the central axis J. The rotor 20 includes a shaft 21 and a rotor body 22. The shaft 21 is cylindrical and extends axially around the central axis J. The lower end of the shaft 21 protrudes downward from the housing 10. The shaft 21 is supported by a pair of bearings 23 and 24 so as to be rotatable around the central axis J. The pair of bearings 23 and 24 are rolling bearings such as ball bearings. The bearing 23 supports a portion of the shaft 21 located above the rotor body 22. The upper end of the shaft 21 is located above the bearing 23. The bearing 23 is held by the shielding member 40. The bearing 24 supports a portion of the shaft 21 located below the rotor body 22. The bearing 24 is held by the bottom wall 13. The rotor body 22 is fixed to the outer peripheral surface of the shaft 21. Although not shown in the figure, the rotor body 22 includes a rotor core fixed to the shaft 21 and a magnet held by the rotor core.

[0022] The sensor magnet 60 is fixed to the rotor 20. In the present embodiment, the sensor magnet 60 is fixed to the shaft 21. In more detail, the sensor magnet 60 is fixed to the upper end surface of the shaft 21. The sensor magnet 60 is in the shape of a circular plate centered on the central axis J. In the present embodiment, the outer diameter of the sensor magnet 60 is the same as the outer diameter at the upper end of the shaft 21. The outer diameter of the sensor magnet 60 may also be different from the outer diameter at the upper end of the shaft 21. In the present embodiment, the sensor magnet 60 is a magnet having a plurality of N poles and a plurality of S poles alternately arranged in the circumferential direction. The number of magnetic poles of the sensor magnet 60 is the same as the number of magnetic poles of the rotor 20.

[0023] The stator 30 and the rotor 20 are opposed to each other with a gap in the radial direction. In the present embodiment, the stator 30 is located radially outside the rotor 20. The stator 30 is in a ring shape surrounding the rotor 20. In the present embodiment, the stator 30 is in a substantially circular ring shape centered on the central axis J. The stator 30 has a stator core 31, an insulator 32, and a plurality of coils 33. The plurality of coils 33 are mounted on the stator core 31 with the insulator 32 therebetween. The coil 33 is formed by winding a conductive wire on the teeth of the stator core 31. The conductive portion 33a extends upward from at least one coil 33. That is, the motor 100 has a conductive portion 33a. In the present embodiment, the conductive portion 33a is a coil lead wire drawn upward from the coil 33. The conductive portion 33a is formed by a conductive wire constituting the coil 33. In the present embodiment, the conductive portion 33a is drawn upward from each of the plurality of coils 33.

[0024] The shielding member 40 is a member for shielding magnetic flux. The material constituting the shielding member 40 is not particularly limited as long as it is a material capable of shielding magnetic flux. The shielding member 40 is made of aluminum, for example. The shielding member 40 is grounded by contacting the housing 10. The shielding member 40 is mounted on the upper end of the housing body 11. The shielding member 40 is located between the stator 30 and the motor control device 50 in the axial direction. The shielding member 40 has a cylindrical portion 41, a base 42, a fitting cylindrical portion 43, and a flange portion 44.

[0025] The cylindrical portion 41 is in the shape of a cylinder surrounding the sensor magnet 60. The cylindrical portion 41 is open on both sides in the axial direction. In the present embodiment, the cylindrical portion 41 is in the shape of a cylinder centered on the central axis J and open on both sides in the axial direction. The cylindrical portion 41 is arranged on the upper side of the rotor body 22 in a spaced manner. The cylindrical portion 41 has an upper cylindrical portion 41a and a lower cylindrical portion 41b. The upper cylindrical portion 41a is the upper part of the cylindrical portion 41. The upper end of the upper cylindrical portion 41a is the upper end of the cylindrical portion 41. The upper end of the upper cylindrical portion 41a contacts the lower surface of the substrate 51 described later. The upper end surface of the upper cylindrical portion 41a contacts the lower surface of the substrate 51 over the entire circumference. The upper end surface of the upper cylindrical portion 41a is located above the upper end surface of the sensor magnet 60. The upper tube portion 41a is located radially outside the upper end portion of the shaft 21 and the sensor magnet 60. The upper tube portion 41a surrounds the upper end portion of the shaft 21 and the sensor magnet 60.

[0026] The lower cylinder 41b is the lower part of the cylindrical portion 41. The lower end of the lower cylinder 41b is the lower end of the cylindrical portion 41. The lower cylinder 41b is connected to the lower side of the upper cylinder 41a. The inner diameter of the lower cylinder 41b is larger than the inner diameter of the upper cylinder 41a. A step portion 41c having a step surface 41d facing downward is provided between the inner circumferential surface of the upper cylinder 41a and the inner circumferential surface of the lower cylinder 41b in the axial direction. The lower cylinder 41b is located radially outside the bearing 23. The lower cylinder 41b is a bearing retaining portion that retains the bearing 23 radially inside. By retaining the bearing 23 in the lower cylinder 41b, the bearing 23 that supports the rotor 20 to be rotatable is retained in the cylindrical portion 41. As a result, there is no need to provide a component for retaining the bearing 23 in addition to the shielding component 40. Therefore, the increase in the number of components of the motor 100 can be suppressed.

[0027] In this embodiment, the conductive portion 33a and the connector portion 16 are located radially outward from the cylindrical portion 41. The connector portion 16 is located radially outward from the conductive portion 33a. The distance between the cylindrical portion 41 and the connector portion 16 is greater than the distance between the cylindrical portion 41 and the conductive portion 33a.

[0028] The base 42 extends radially outward from the upper end of the cylindrical portion 41. The base 42 is provided separately from the lower side of the cover wall portion 12a. The base 42 has a cover portion 42a and an extension portion 42b. The cover portion 42a covers the upper opening of the first peripheral wall portion 14. The cover portion 42a is in the shape of a disk centered on the central axis J. The cover portion 42a is provided with a first through hole 45 that penetrates the cover portion 42a in the axial direction. The conductive portion 33a passes through the first through hole 45 in the axial direction. The extension portion 42b extends from the cover portion 42a to one side (+X side) of the extension direction. The extension portion 42b contacts the surface of the upper side of the extension wall portion 15. The extension portion 42b is provided with a second through hole 46 that penetrates the extension portion 42b in the axial direction. The power terminal 80 passes through the second through hole 46 in the axial direction. The upper end portion of the base 42 is fitted into the lower end portion of the second peripheral wall portion 12b.

[0029] The interlocking cylinder 43 protrudes downward from the radial outer edge of the cover 42a. The interlocking cylinder 43 is in the shape of a cylinder centered on the central axis J and open at the lower side. The interlocking cylinder 43 is interlocked in the upper end of the first peripheral wall 14. The flange 44 protrudes radially outward from the base 42. The flange 44 is arranged over the entire circumference of the radial outer edge of the base 42. The flange 44 is in the shape of a ring surrounding the central axis J. The flange 44 is clamped by the housing body 11 and the cover 12 in the axial direction in a state of contact with the housing body 11 and the cover 12.

[0030] At least a portion of the upper surface of the shielding member 40 is in contact with the lower surface of the substrate 51 described later. That is, the shielding member 40 is in contact with the motor control device 50. In the present embodiment, substantially the entire upper surface of the shielding member 40, except for the radial outer edge portion, is in contact with the lower surface of the substrate 51. The heat of the substrate 51 is transferred to the shielding member 40, and is released from the shielding member 40 directly or via the housing 10 to the outside of the motor 100. Thus, in the present embodiment, the shielding member 40 is a heat sink connected to the motor control device 50. Therefore, the shielding member 40 can be used to release the heat of the motor control device 50 to the outside of the motor 100. In addition, the shielding member 40 can also be connected to the motor control device 50 via other components. The shielding member 40 can also be connected to the motor control device 50 by, for example, being fixed to the motor control device 50 using an adhesive having high thermal conductivity.

[0031] In this embodiment, the shielding member 40 and the cover 12 constitute the housing 17 housing the motor control device 50. The interior space of the housing 17 is surrounded by the cover wall 12a, the second peripheral wall 12b and the base 42.

[0032] The motor control device 50 controls the motor 100. In the present embodiment, the motor control device 50 controls the motor 100 by performing vector control in which the motor current supplied to the stator 30 is divided into a d-axis current component and a q-axis current component for control. The motor control device 50 is housed inside the housing portion 17. The motor control device 50 includes a substrate 51, a control unit 52, and an inverter circuit unit 53. The substrate 51 is located on the upper side of the rotor 20. The plate surface of the substrate 51 faces the axial direction. More specifically, the plate surface of the substrate 51 is perpendicular to the axial direction. The control unit 52 and the inverter circuit unit 53 are provided on the upper surface of the substrate 51. The substrate 51 is fixed to the shielding member 40, for example. The lower surface of the substrate 51 contacts the upper surface of the base 42. The lower surface of the substrate 51 closes the upper opening of the cylindrical portion 41.

[0033] A plurality of conductive portions 33a are electrically connected to the substrate 51. Thus, the conductive portions 33a electrically connect the stator 30 and the substrate 51. More specifically, the conductive portions 33a electrically connect the inverter circuit portion 53 and the coil 33. The conductive portions 33a pass through a through hole provided in the substrate 51 in the axial direction and are electrically connected to the substrate 51 by solder or the like. A power terminal 80 is electrically connected to the substrate 51. The power terminal 80 passes through a through hole provided in the substrate 51 in the axial direction and is electrically connected to the substrate 51 by solder or the like. Power is supplied to the substrate 51 from an external device connected to the connector portion 16 via the power terminal 80.

[0034] A magnetic sensor 70 is mounted on the lower surface of the substrate 51. More specifically, the magnetic sensor 70 is mounted on a portion of the lower surface of the substrate 51 that is surrounded by the upper end of the cylindrical portion 41. In the present embodiment, the center axis J passes through the magnetic sensor 70. The magnetic sensor 70 is located at a position separated from the upper side of the sensor magnet 60. The magnetic sensor 70 and the sensor magnet 60 are opposed to each other with a gap in the axial direction. The magnetic sensor 70 and the sensor magnet 60 are surrounded by the cylindrical portion 41 within the entire circumference around the center axis J. The entirety of the magnetic sensor 70, except for the surface mounted on the substrate 51, is located below the upper end surface of the cylindrical portion 41.

[0035] like Figure 2 As shown, the magnetic sensor 70 is an MR sensor having a magnetoresistive effect element 73. The magnetoresistive effect element 73 is a portion of the magnetic sensor 70 that detects a magnetic field. Although not shown in the figure, the magnetoresistive effect element 73 is located at a position lower than the upper end surface of the cylindrical portion 41. The magnetic sensor 70 outputs two system signals whose phases are shifted by 180 degrees from each other. The magnetic sensor 70 has a first bridge circuit 71 and a second bridge circuit 72.

[0036] The first bridge circuit 71 is provided between the input terminal 71v and the ground terminal 71g. The first bridge circuit 71 is formed by connecting two pairs of a pair of magnetoresistance effect elements 73a and 73b connected in series in parallel. The pair of magnetoresistance effect elements 73a and 73b on one side are arranged in the order of magnetoresistance effect element 73a and magnetoresistance effect element 73b from the input terminal 71v toward the ground terminal 71g. The pair of magnetoresistance effect elements 73a and 73b on the other side are arranged in the order of magnetoresistance effect element 73b and magnetoresistance effect element 73a from the input terminal 71v toward the ground terminal 71g. Point P1a connected to the input terminal 71v, point P2a connected to the ground terminal 71g, point P3a between the pair of magnetoresistance effect elements 73a and 73b on one side, and point P4a between the pair of magnetoresistance effect elements 73a and 73b on the other side are respectively connected to point P5a. Zener diodes 74 are provided between the point P5a and each of the points P1a, P2a, P3a, and P4a. The first output terminal 71p is connected to the point P3a. The second output terminal 71m is connected to the point P4a.

[0037] The second bridge circuit 72 is provided between the input terminal 72v and the ground terminal 72g. The second bridge circuit 72 is formed by connecting two pairs of a pair of magnetoresistance effect elements 73c and 73d connected in series in parallel. The pair of magnetoresistance effect elements 73c and 73d on one side are arranged in the order of magnetoresistance effect element 73c and magnetoresistance effect element 73d from the input terminal 72v toward the ground terminal 72g. The pair of magnetoresistance effect elements 73c and 73d on the other side are arranged in the order of magnetoresistance effect element 73d and magnetoresistance effect element 73c from the input terminal 72v toward the ground terminal 72g. Point P1b connected to the input terminal 72v, point P2b connected to the ground terminal 72g, point P3b between the pair of magnetoresistance effect elements 73c and 73d on one side, and point P4b between the pair of magnetoresistance effect elements 73c and 73d on the other side are respectively connected to point P5b. Zener diodes 74 are provided between point P5b and points P1b, P2b, P3b, and P4b, respectively. Point P3b is connected to a first output terminal 72p. Point P4b is connected to a second output terminal 72m. Point P5a and point P5b are connected to each other.

[0038] exist Figure 2In the figure, the arrows shown in each magnetoresistance effect element 73 indicate the magnetization direction of the pinned layer of each magnetoresistance effect element 73. The magnetization direction of the pinned layer of the magnetoresistance effect elements 73a and 73b in the first bridge circuit 71 is 90° different from the magnetization direction of the pinned layer of the magnetoresistance effect elements 73c and 73d in the second bridge circuit 72. The magnetization direction of the pinned layer of the magnetoresistance effect element 73a is opposite to the magnetization direction of the pinned layer of the magnetoresistance effect element 73b. The magnetization direction of the pinned layer of the magnetoresistance effect element 73c is opposite to the magnetization direction of the pinned layer of the magnetoresistance effect element 73d.

[0039] When the rotor 20 rotates, a sine wave (sin wave) is output from the first output terminal 71p and the second output terminal 71m in the first bridge circuit 71, respectively. The phases of the sine wave output from the first output terminal 71p and the sine wave output from the second output terminal 71m are shifted by 180°. A cosine wave (cos wave) is output from the first output terminal 72p and the second output terminal 72m in the second bridge circuit 72, respectively. The phases of the cosine wave output from the first output terminal 72p and the cosine wave output from the second output terminal 72m are shifted by 180°. In this way, the magnetic sensor 70 outputs two systems of sine waves whose phases are shifted by 180° and two systems of cosine waves whose phases are shifted by 180° as signals of two systems.

[0040] The control unit 52 is, for example, a microprocessor such as an MCU (Microcontroller Unit). Figure 3 As shown in FIG. 1 , the control unit 52 includes a calculation unit 56, a correction unit 57, and a current control unit 58. That is, the motor control device 50 includes the calculation unit 56, the correction unit 57, and the current control unit 58. The calculation unit 56 calculates angle information related to the rotation angle θ of the rotor 20 of the motor 100 based on the output from the magnetic sensor 70. In the present embodiment, the calculation unit 56 calculates the electrical angle θ of the rotor 20 calculated based on the output from the magnetic sensor 70. e and the mechanical angle θ of the rotor 20 m Specifically, the calculation unit 56 calculates the mechanical angle θ based on a sine wave having a double amplitude obtained by subtracting the output signal (-sin wave) of the second output terminal 71m from the output signal (+sin wave) of the first output terminal 71p and a cos wave having a double amplitude obtained by subtracting the output signal (-cos wave) of the second output terminal 72m from the output signal (+cos wave) of the first output terminal 72p. m and electrical angle θ e The mechanical angle θ calculated by the calculation unit 56 is m and electrical angle θ e The data is input to the correction unit 57 .

[0041] The correction unit 57 corrects the angle information calculated by the calculation unit 56. In the present embodiment, the angle information corrected by the correction unit 57 is the electrical angle θ e The correction unit 57 receives as input a current value I of a power supply current supplied from an external device connected to the connector unit 16 to the motor control device 50. DC The correction unit 57 receives as input the current value I of the motor current supplied from the inverter circuit unit 53 to the stator 30. m and the phase angle θ of the motor current supplied to the stator 30 Im In the present embodiment, the motor current supplied to the stator 30 is a three-phase alternating current. The current value I of the motor current is m It is the composite value of the current values ​​of the three-phase alternating current. When the current value of the d-axis current component in the motor current is set to I d , let the current value of the q-axis current component in the motor current be I q When the current value I m It is represented by the following formula (1).

[0042]

[0043] The correction unit 57 uses the current value I m and the phase angle θ of the motor current Im , the current value I of the power supply current supplied to the motor control device 50 DC and the mechanical angle θ of the rotor 20 calculated based on the output from the magnetic sensor 70 m The correction amount represented by the function of is used to correct the angle information, that is, the electrical angle θ e .

[0044] When the motor current value is set to I m , let the phase angle of the motor current be θ Im , set the current value of the power supply current to I DC , the mechanical angle of the rotor 20 calculated based on the output from the magnetic sensor 70 is θ m , the electrical angle of the rotor 20 calculated based on the output from the magnetic sensor 70 is θ e , set the correction amount to θ f When , the following formula (2) holds.

[0045] θ f =A sin(θ e +P)+Z…(2)

[0046] A=I m C1(sin(2(θ m +C2))+C3)

[0047] P=-θ m -θ Im +C4

[0048] Z=I DC C5(sin(θ m +C6)+C7)

[0049] Among them, C1, C2, C3, C4, C5, C6 and C7 are constants.

[0050] In the above formula (2), A is the current value I which depends on the motor current. m The P in formula (2) depends on the phase angle θ Im and mechanical angle θ m The Z in formula (2) is the current value I that depends on the power supply current. DC The formula (2) is an experimentally obtained formula. The electrical angle θ of the rotor 20 calculated based on the output from the magnetic sensor 70 is e With respect to the actual electrical angle θ of the rotor 20 ea The error θ er The change of the current value I based on the motor current m 、The phase angle θ of the motor current Im , the current value of the power supply current I DC and the mechanical angle θ of the rotor 20 calculated from the output of the magnetic sensor 70 m The electrical angle θ of the rotor 20 calculated based on the output from the magnetic sensor 70 is e With respect to the actual electrical angle θ of the rotor 20 ea The error of can be approximated by the following formula (3), for example.

[0051] θ er =α1sin(θ ea +β1)+α3sin(3θ ea +β3)+α5sin(5θ ea +β5)

[0052] …(3)

[0053] Among them, α1, α3, α5, β1, β3 and β5 are constants.

[0054] Assume that the error θ obtained from the above formula (3) is er The absolute value of the value is the correction amount θ to be corrected f The absolute value of the electrical angle θ ea Each of them, by combining the error θ er The value of current Im , phase angle θ Im , current value I DC and the mechanical angle θ m By substituting the above formula (2) into the obtained formula, constants C1 to C7 can be calculated.

[0055] The correction unit 57 calculates the electrical angle θ of the rotor 20 based on the output from the magnetic sensor 70. e Add the correction value θ obtained according to formula (2) f , to correct the electrical angle θ e , calculate the corrected electrical angle θ ef The electrical angle θ calculated by the correction unit 57 is ef The current is input to the current control unit 58 .

[0056] The current control unit 58 is based on the electrical angle θ input from the correction unit 57. ef The signal sent to the inverter circuit unit 53 is controlled to control the motor current output from the inverter circuit unit 53. The current control unit 58 controls the motor current output from the inverter circuit unit 53 by feedback control.

[0057] The inverter circuit unit 53 is composed of a plurality of switching elements. The inverter circuit unit 53 is driven by a signal from the current control unit 58 and supplies a motor current to the coil 33 of the stator 30. The plurality of switching elements constituting the inverter circuit unit 53 are, for example, field effect transistors (FET: Field Effect Transistor).

[0058] At least a part of the functions of the components of the motor control device 50 described above is realized by, for example, a processor such as a CPU executing a program stored in a storage unit not shown, that is, software. In addition, at least a part of the functions of the components of the motor control device 50 can be realized by, for example, hardware including circuit units such as LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), and GPU (Graphics Processing Unit), or can be realized by the cooperation of software and hardware. The storage unit not shown is realized by, for example, a storage medium such as RAM (Random Access Memory), ROM (Read Only Memory), HDD (hard disk drive), and flash memory.

[0059] Since the magnetic sensor 70 outputs two signals of a system whose phases are shifted by 180°, the calculation unit 56 can remove a part of the influence of the external magnetic field applied to the magnetic sensor 70 by adding the signals of the two systems. For example, the sine wave output from the first output terminal 71p and the sine wave output from the second output terminal 71m each contain the influence of the external magnetic field as an in-phase component. Therefore, by subtracting the sine wave output from the second output terminal 71m whose phase is shifted by 180° from the sine wave output from the first output terminal 71p, the influence of the external magnetic field contained in each sine wave as an in-phase component can be offset and removed. However, due to the offset of the position of the magnetic sensor 70 and the deviation of the characteristics of the magnetic sensor 70, the influence of the external magnetic field contained in the sine waves output from the first output terminal 71p and the second output terminal 71m is biased, and the influence of the external magnetic field cannot be completely removed only by the above method. Therefore, the rotation position of the rotor 20 cannot be detected with high accuracy sometimes.

[0060] To solve the above problem, according to the present embodiment, the correction unit 57 uses the current value I including the motor current. m and the phase angle θ of the motor current Im , the current value I of the power supply current supplied to the motor control device 50 DC and the mechanical angle θ of the rotor 20 calculated based on the output from the magnetic sensor 70 m The correction value θ is expressed as a function of f To correct the electrical angle θ e The influence of the external magnetic field applied to the magnetic sensor 70 includes the influence caused by the motor current supplied to the stator 30 and the power supply current supplied to the motor control device 50. Therefore, by using the correction amount θ represented by a function including parameters of the motor current and the power supply current f To correct the electrical angle θ e , the influence of the external magnetic field can be appropriately removed. As a result, the detection accuracy of the rotational position of the rotor 20 can be improved. In particular, in the motor 100 mounted on the steering device mounted on the vehicle as in the present embodiment, it is required to detect the rotational position of the rotor 20 with higher accuracy. Therefore, the effect of improving the detection accuracy of the rotational position of the rotor 20 is particularly useful when the motor 100 is mounted on the steering device of the vehicle.

[0061] According to the present embodiment, the angle information corrected by the correction unit 57 is the electrical angle θ e In the present embodiment, the magnetic sensor 70 is a device capable of detecting the electrical angle θ of the rotor 20. e The MR sensor detects the electrical angle θ of the rotor 20. eIn the case of , the number of magnetic poles of the sensor magnet 60 is the same as the number of magnetic poles of the rotor 20. On the other hand, when the mechanical angle θ of the rotor 20 is detected by the MR sensor m In the case of , the sensor magnet 60 becomes a magnet having two poles, one N pole and one S pole, which are opposite to each other in the radial direction. Therefore, the electrical angle θ can be detected by the magnetic sensor 70. e The structure can improve the accuracy of the detected value. Therefore, by using the angle information corrected by the correction unit 57 as the electrical angle θ e , which can further improve the detection accuracy of the rotational position of the rotor 20.

[0062] According to the present embodiment, the above-mentioned equation (2) holds true. By calculating the correction amount θ as in equation (2): f , it is easy to calibrate the electrical angle θ with high accuracy based on the parameters of the motor current and the power supply current e .

[0063] In addition, according to the present embodiment, the shielding component 40 for shielding the magnetic flux has a cylindrical portion 41 that surrounds the sensor magnet 60. The upper end of the cylindrical portion 41 is in contact with the lower surface of the substrate 51. The magnetic sensor 70 is mounted on the portion of the lower surface of the substrate 51 that is surrounded by the upper end of the cylindrical portion 41. Therefore, the cylindrical portion 41 can be used to shield the magnetic flux from the radially outer side of the cylindrical portion 41 toward the magnetic sensor 70. As a result, the magnetic flux generated from the sensor magnet 60 can be detected by the magnetic sensor 70 while reducing the influence of the external magnetic field. Therefore, the detection accuracy of the rotational position of the rotor 20 can be further improved. In addition, the above-mentioned formula (2) is a formula experimentally obtained in a structure in which the sensor magnet 60 and the magnetic sensor 70 are surrounded by the cylindrical portion 41 of the shielding component 40. Therefore, in the motor 100 having this structure, by using the correction amount θ of the formula (2) f To correct the electrical angle θ e , which can correct the electrical angle θ with higher accuracy e In addition, even if the motor 100 does not have this structure, the electrical angle θ is not corrected. e Compared with the case of f To correct the electrical angle θ e , can also increase the electrical angle θ e accuracy.

[0064] In addition, according to the present embodiment, the conductive portion 33a is located radially outward from the cylindrical portion 41. Therefore, it is easy to shield the magnetic flux flowing toward the magnetic sensor 70 among the magnetic fluxes generated by the motor current flowing through the conductive portion 33a by the cylindrical portion 41. Thus, the influence of the external magnetic field applied to the magnetic sensor 70 by the motor current flowing through the conductive portion 33a can be reduced, and the detection accuracy of the rotational position of the rotor 20 can be further improved.

[0065] In addition, according to the present embodiment, the connector portion 16 holding the power terminal 80 is located radially outward from the cylindrical portion 41. Therefore, it is easy to shield the magnetic flux flowing toward the magnetic sensor 70 among the magnetic fluxes generated by the power current flowing through the power terminal 80 by the cylindrical portion 41. Thus, the influence of the external magnetic field applied to the magnetic sensor 70 by the power current flowing through the power terminal 80 can be reduced, and the detection accuracy of the rotation position of the rotor 20 can be further improved.

[0066] The present invention is not limited to the above-mentioned embodiments, and other structures and other methods can also be adopted within the scope of the technical concept of the present invention. The correction amount used when the correction unit corrects the angle information calculated by the calculation unit is not particularly limited as long as it is represented by a function including the current value of the motor current and the phase angle of the motor current, the current value of the power supply current, and the mechanical angle of the rotor calculated based on the output from the magnetic sensor. The angle information corrected by the correction unit may also be the mechanical angle of the rotor.

[0067] The structure of the motor equipped with the motor control device is not particularly limited. The shielding member may not be a heat sink. The conductive portion that electrically connects the stator and the substrate may be of any structure and may be a bus bar. The conductive portion may be arbitrarily arranged relative to the cylindrical portion of the shielding member. The connector portion may be arranged in any manner relative to the cylindrical portion of the shielding member. The motor may not have a shielding member. The purpose of the motor is not particularly limited. The motor may be mounted on a device other than a steering device mounted on a vehicle, or may be mounted on a device other than a vehicle.

[0068] In addition, the present technology can adopt the following structures.

[0069] [1] A motor control device that controls a motor, wherein the motor control device comprises: a calculation unit that calculates angle information related to the rotation angle of the rotor of the motor based on an output from a magnetic sensor; and a correction unit that corrects the angle information calculated by the calculation unit, wherein the magnetic sensor is a sensor having a magnetoresistive effect element and outputting two systems of signals whose phases are shifted by 180 degrees from each other, and the correction unit corrects the angle information using a correction amount represented by a function including a current value of a motor current supplied to a stator of the motor and a phase angle of the motor current, a current value of a power supply current supplied to the motor control device, and a mechanical angle of the rotor calculated based on the output from the magnetic sensor.

[0070] [2] The motor control device according to [1], wherein the angle information is an electrical angle.

[0071] [3] The motor control device according to [2], wherein the current value of the motor current is set to I m , the phase angle of the motor current is set to θ Im , set the current value of the power supply current to I DC , the mechanical angle of the rotor calculated based on the output from the magnetic sensor is set to θ m , the electrical angle of the rotor calculated based on the output from the magnetic sensor is set to θ e , the correction amount is set to θ f , the following formula holds:

[0072] θ f =A sin(θ e +P)+Z

[0073] A=I m C1(sin(2(θ m +C2))+C3)

[0074] P=-θ m -θ Im +C4

[0075] Z=I DC C5(sin(θ m +C6)+C7)

[0076] Among them, C1, C2, C3, C4, C5, C6 and C7 are constants.

[0077] [4] A motor comprising: a motor control device as described in any one of [1] to [3]; a rotor capable of rotating around a central axis; a stator opposed to the rotor in a radial direction with a gap therebetween; a sensor magnet fixed to the rotor; a magnetic sensor opposed to the sensor magnet in an axial direction with a gap therebetween; and a shielding member that shields magnetic flux, wherein the motor control device comprises a substrate located on one axial side of the rotor, the shielding member comprising a cylindrical portion surrounding the sensor magnet, an end portion of the cylindrical portion on one axial side being in contact with a surface of the substrate on the other axial side, and the magnetic sensor is mounted on a portion of the surface of the substrate on the other axial side that is surrounded by the end portion of the cylindrical portion on one axial side.

[0078] [5] The motor according to [4], wherein the motor has a conductive portion that electrically connects the stator and the substrate, and the conductive portion is located radially outward of the cylindrical portion.

[0079] [6] The motor according to [4] or [5], wherein the motor has a connector portion that holds a power terminal electrically connected to the substrate, and the connector portion is located radially outward of the cylindrical portion.

[0080] [7] The motor according to any one of [4] to [6], wherein the shielding member is a heat sink connected to the motor control device.

[0081] [8] The motor according to any one of [4] to [7], wherein a bearing that rotatably supports the rotor is held in the cylindrical portion.

[0082] The structures and methods described above in this specification can be appropriately combined within a range that does not contradict each other.

Claims

1. A motor control device, which controls a motor, wherein: The motor control device has: a calculation unit that calculates angle information related to a rotation angle of a rotor of the motor based on an output from a magnetic sensor; and a correction unit that corrects the angle information calculated by the calculation unit, The magnetic sensor is a sensor having a magnetoresistive effect element and outputting two signals whose phases are shifted by 180 degrees from each other. The correction unit corrects the angle information using a correction amount represented by a function including a current value of a motor current supplied to a stator of the motor and a phase angle of the motor current, a current value of a power supply current supplied to the motor control device, and a mechanical angle of the rotor calculated based on an output from the magnetic sensor.

2. The motor control device according to claim 1, wherein: The angle information is an electrical angle.

3. The motor control device according to claim 2, wherein: When the current value of the motor current is set to I m , the phase angle of the motor current is set to θ Im , set the current value of the power supply current to I DC , the mechanical angle of the rotor calculated based on the output from the magnetic sensor is set to θ m , the electrical angle of the rotor calculated based on the output from the magnetic sensor is set to θ e , the correction amount is set to θ f , the following formula holds: i f =A sin(θ e +P)+Z A=I m C1(sin(2(θ m +C2))+C3) P=-θ m -θ Im +C4 Z=I DC C5(sin(θ m +C6)+C7) Among them, C1, C2, C3, C4, C5, C6 and C7 are constants.

4. A motor comprising: The motor control device according to any one of claims 1 to 3; The rotor is capable of rotating about a central axis; The stator is opposed to the rotor with a gap in the radial direction; a sensor magnet fixed to the rotor; the magnetic sensor being opposed to the sensor magnet with a gap therebetween in the axial direction; and a shielding member which shields the magnetic flux, The motor control device includes a substrate located on one axial side of the rotor. The shielding member has a cylindrical portion surrounding the sensor magnet. The end portion of the cylindrical portion on one axial side is in contact with the surface of the substrate on the other axial side. The magnetic sensor is mounted on a portion of the surface on the other axial side of the substrate that is surrounded by the end portion on one axial side of the cylindrical portion.

5. The motor according to claim 4, wherein: The motor has a conductive portion that electrically connects the stator and the substrate. The conductive portion is located radially outward of the cylindrical portion.

6. The motor according to claim 4, wherein: The motor includes a connector portion for holding a power terminal electrically connected to the substrate. The connector portion is located radially outward of the cylindrical portion.

7. The motor according to claim 4, wherein: The shielding member is a heat sink connected to the motor control device.

8. The motor according to claim 4, wherein: The cylindrical portion holds a bearing that rotatably supports the rotor.

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