Motor control device and motor

Abstract

To provide a motor control device capable of improving a detection accuracy of a rotational position of a rotor, and provide a motor.SOLUTION: A motor control device 50 controlling a motor includes: a calculation part 56 that calculates angle information in regard to a rotational angle of a rotor of the motor on the basis of an output from a magnetic sensor 70; and a correction part 57 that corrects the angle information calculated by the calculation part. The magnetic sensor is a sensor that includes a magnetic resistance effect element, and outputs a two-system signal in which a phase is deviated by 180° each other. The correction part corrects a current value of a motor current supplied to a stator of the motor and a phase angle of the motor current, the current value of a power supply current supplied to the motor control device, and angle information by using a correction amount expressed by a function containing a machine angle of the rotor calculated on the basis of an output from the magnetic sensor.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] 2. Description of the Related Art Conventionally, there is known a motor that detects the position of a rotor by using a sensor magnet and a sensor (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-158059 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the motor described above, in order to improve the accuracy of detecting the rotational position of the rotor, a method of reducing the influence of an external magnetic field may be adopted, for example, by using an MR (Magneto Resistive) sensor that outputs two signals with a phase difference of 180°. However, with this method, the influence of the external magnetic field may not be sufficiently reduced due to the misalignment of the MR sensor and the variation in the characteristics of the MR sensor. Therefore, the accuracy of detecting the rotational position of the rotor may not be sufficiently improved.

[0005] In view of the above circumstances, an object of the present invention is to provide a motor control device and a motor that can improve the detection accuracy of the rotational position of a rotor. [Means for solving the problem]

[0006] One aspect of the motor control device of the present invention is a motor control device that controls a motor, and includes 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 that has a magnetoresistance effect element and outputs two systems of signals whose phases are shifted by 180° from each other. The correction unit corrects the angle information using a correction amount expressed 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.

[0007] One aspect of the motor of the present invention includes the motor control device described above, the rotor rotatable about a central axis, the stator facing the rotor in the radial direction with a gap therebetween, a sensor magnet fixed to the rotor, the magnetic sensor facing the sensor magnet in the axial direction with a gap therebetween, and a shielding member for shielding magnetic flux. The motor control device has a substrate located on one axial side of the rotor. The shielding member has a cylindrical portion surrounding the sensor magnet. An end portion on one axial side of the cylindrical portion contacts a surface on the other axial side of the substrate. The magnetic sensor is attached to 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. Effect of the Invention

[0008] According to one aspect of the present invention, it is possible to improve the detection accuracy of the rotational position of the rotor in a motor control device and a motor. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view showing a motor according to an embodiment. [Diagram 2] FIG. 2 is a circuit diagram showing a circuit configuration of a magnetic sensor according to an embodiment. [Diagram 3]FIG. 3 is a block diagram illustrating functional blocks of the motor control device according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 1 shows an imaginary central axis J of a motor according to an embodiment described below. In the following description, unless otherwise specified, the axial direction of the central axis J will be simply referred to as the "axial direction", the radial direction about the central axis J will be simply referred to as the "radial direction", and the circumferential direction about the central axis J will be simply referred to as the "circumferential direction". The Z axis shown in each drawing indicates the direction in which the central axis J extends. In the following description, the side in the axial direction toward which the Z axis arrow points (+Z side) will be referred to as the "upper side", and the side opposite to the side toward which the Z axis arrow points (-Z side) will be referred to as the "lower side".

[0011] In the following embodiments, the upper side corresponds to the “one axial side”, and the lower side corresponds to the “other axial side”. Note that the terms “upper side” and “lower side” are names used simply to describe the relative positional relationship of each part, and the actual positional relationship, etc. may be a positional relationship, etc. other than the positional relationship, etc. indicated by these names.

[0012] The motor 100 of this embodiment shown in Fig. 1 is a mechanically and electrically integrated motor. The motor 100 of this embodiment is a motor mounted on a steering device of a vehicle. The motor 100 is, for example, a three-phase motor. As shown in Fig. 1, 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 supply terminal 80. The rotor 20 and the stator 30 form a motor main body 100a.

[0013] The housing 10 accommodates therein 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 has a housing main body 11 and a cover body 12.

[0014] The housing body 11 is a cylindrical member that opens upward. The housing body 11 has a bottom wall portion 13, a first peripheral wall portion 14, and an extension wall portion 15. The bottom wall portion 13 is located below 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 cylindrical and opens upward, centered on the central axis line J. The extension wall portion 15 extends from the upper end portion of the first peripheral wall portion 14 to one side in one direction perpendicular to the axial direction. In FIG. 1, the one direction in which the extension wall portion 15 extends is indicated by the X-axis. The side to which the arrow of the X-axis faces (+X side) corresponds to one side to which the extension wall portion 15 extends relative to the first peripheral wall portion 14. In the following description, the direction in which the extending wall portion 15 extends is referred to as the "extending direction X", the side in the extending direction X toward which the X-axis arrow faces (+X side) is referred to as the "one extending direction side", and the opposite side in the extending direction X to the side toward which the X-axis arrow faces (-X side) is referred to as the "other extending direction side". In this embodiment, the extending direction X is one of the radial directions.

[0015] The housing main body 11 has a connector portion 16. That is, the motor 100 is equipped with the connector portion 16. The connector portion 16 protrudes downward from an end portion on one side (+X side) in the extension direction of the extension wall portion 15. The connector portion 16 is cylindrical and opens downward. The connector portion 16 holds a power terminal 80. The power terminal 80 is a metal member extending in the axial direction. A lower portion of the power terminal 80 is exposed inside the connector portion 16. A terminal of an external device connected to the connector portion 16 is electrically connected to the power terminal 80. For example, a plurality of power terminals 80 are provided.

[0016] The cover body 12 is located above the housing main 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 above the motor control device 50. The cover wall portion 12a covers the motor control device 50 from above. The second peripheral wall portion 12b protrudes downward from the radial outer edge of the cover wall portion 12a. The second peripheral wall portion 12b is cylindrical and opens downward. The second peripheral wall portion 12b sandwiches a flange portion 44 (described later) of the shielding member 40 between itself and the housing main body 11 in the axial direction.

[0017] The rotor 20 is rotatable about the central axis J. The rotor 20 has a shaft 21 and a rotor body 22. The shaft 21 is cylindrical and extends in the axial direction about the central axis J. A lower end of the shaft 21 protrudes downward from the housing 10. The shaft 21 is supported by a pair of bearings 23, 24 to be rotatable about the central axis J. The pair of bearings 23, 24 are rolling bearings such as ball bearings. The bearing 23 supports a portion of the shaft 21 that is 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 that is located below the rotor body 22. The bearing 24 is held by the bottom wall portion 13. The rotor body 22 is fixed to the outer circumferential surface of the shaft 21. Although not shown, the rotor body 22 has a rotor core fixed to the shaft 21 and a magnet held by the rotor core.

[0018] The sensor magnet 60 is fixed to the rotor 20. In this embodiment, the sensor magnet 60 is fixed to the shaft 21. More specifically, the sensor magnet 60 is fixed to the upper end surface of the shaft 21. The sensor magnet 60 is disk-shaped and centered on the central axis J. In this 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 be different from the outer diameter at the upper end of the shaft 21. In this embodiment, the sensor magnet 60 is a magnet having multiple N poles and multiple 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.

[0019] The stator 30 faces the rotor 20 in the radial direction with a gap therebetween. In this embodiment, the stator 30 is located radially outside the rotor 20. The stator 30 is annular and surrounds the rotor 20. In this embodiment, the stator 30 is substantially annular with the central axis J as the center. The stator 30 has a stator core 31, an insulator 32, and a plurality of coils 33. The plurality of coils 33 are attached to the stator core 31 via the insulator 32. The coils 33 are configured by winding a conductor around the teeth of the stator core 31. A conductive portion 33a extends upward from at least one coil 33. That is, the motor 100 includes the conductive portion 33a. In this embodiment, the conductive portion 33a is a coil lead wire drawn upward from the coil 33. The conductive portion 33a is composed of a conductor that constitutes the coil 33. In this embodiment, the conductive portion 33a is drawn upward from each of the plurality of coils 33.

[0020] The shielding member 40 is a member that shields magnetic flux. The material constituting the shielding member 40 is not particularly limited as long as it is a material that can shield 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 attached to the upper end of the housing main body 11. The shielding member 40 is located axially between the stator 30 and the motor control device 50. The shielding member 40 has a cylindrical portion 41, a base portion 42, a fitting cylindrical portion 43, and a flange portion 44.

[0021] The cylindrical portion 41 is cylindrical and surrounds the sensor magnet 60. The cylindrical portion 41 opens on both sides in the axial direction. In this embodiment, the cylindrical portion 41 is cylindrical and has a center on the central axis J and opens on both sides in the axial direction. The cylindrical portion 41 is disposed on the upper side of the rotor body 22 with a gap therebetween. 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 face of the upper cylindrical portion 41a contacts the lower surface of the substrate 51 over the entire circumference in the circumferential direction. The upper end face of the upper cylindrical portion 41a is located above the upper end face of the sensor magnet 60. The upper cylindrical portion 41a is located at the upper end of the shaft 21 and radially outside of the sensor magnet 60. The upper cylindrical portion 41a surrounds the upper end of the shaft 21 and the sensor magnet 60.

[0022] The lower cylinder portion 41b is a lower portion of the cylindrical portion 41. The lower end of the lower cylinder portion 41b is the lower end of the cylindrical portion 41. The lower cylinder portion 41b is connected to the lower side of the upper cylinder portion 41a. The inner diameter of the lower cylinder portion 41b is larger than the inner diameter of the upper cylinder portion 41a. A step portion 41c having a step surface 41d facing downward is provided between the inner peripheral surface of the upper cylinder portion 41a and the inner peripheral surface of the lower cylinder portion 41b in the axial direction. The lower cylinder portion 41b is located radially outside the bearing 23. The lower cylinder portion 41b is a bearing holding portion that holds the bearing 23 radially inside. The bearing 23 is held in the lower cylinder portion 41b, so that the bearing 23 that rotatably supports the rotor 20 is held in the cylindrical portion 41. This eliminates the need to provide a member that holds the bearing 23 separately from the shielding member 40. This makes it possible to suppress an increase in the number of parts of the motor 100.

[0023] 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.

[0024] The base 42 extends radially outward from the upper end of the cylindrical portion 41. The base 42 is provided below the cover wall portion 12a at a distance. The base 42 has a cover portion 42a and an extension portion 42b. The cover portion 42a covers the upper opening of the first circumferential wall portion 14. The cover portion 42a is disk-shaped with the central axis J as its center. 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 in the extension direction (+X side). The extension portion 42b contacts the upper surface 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. A power terminal 80 is passed axially through the second through hole 46. The upper end of the base portion 42 is fitted into the lower end of the second peripheral wall portion 12b.

[0025] The fitting tubular portion 43 protrudes downward from the radial outer edge of the lid portion 42a. The fitting tubular portion 43 is cylindrical and centered on the central axis J, opening downward. The fitting tubular portion 43 is fitted into the upper end portion of the first peripheral wall portion 14. The flange portion 44 protrudes radially outward from the base portion 42. The flange portion 44 is provided around one circumference of the radial outer edge of the base portion 42. The flange portion 44 is annular and surrounds the central axis J. The flange portion 44 is axially sandwiched between the housing body 11 and the lid body 12 while in contact with both.

[0026] At least a part of the upper surface of the shielding member 40 contacts the lower surface of the substrate 51 described later. That is, the shielding member 40 contacts the motor control device 50. In this embodiment, almost the entire upper surface of the shielding member 40, except for the radial outer edge portion, contacts the lower surface of the substrate 51. 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 this embodiment, the shielding member 40 is a heat sink connected to the motor control device 50. Therefore, the heat of the motor control device 50 can be released to the outside of the motor 100 by using the shielding member 40. Note that the shielding member 40 may be connected to the motor control device 50 via other members or the like. The shielding member 40 may be connected to the motor control device 50 by being fixed to the motor control device 50 with an adhesive having high thermal conductivity, for example.

[0027] In this embodiment, the shielding member 40 and the cover 12 form a housing 17 that houses the motor control device 50. The internal space of the housing 17 is a space surrounded by the cover wall 12a of the cover 12, the second peripheral wall 12b of the cover 12, and the base 42.

[0028] The motor control device 50 controls the motor 100. In this embodiment, the motor control device 50 controls the motor 100 by vector control that divides the motor current supplied to the stator 30 into a d-axis current component and a q-axis current component and controls the motor 100. The motor control device 50 is accommodated inside the accommodation portion 17. The motor control device 50 has a substrate 51, a control unit 52, and an inverter circuit unit 53. The substrate 51 is located above 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.

[0029] A plurality of conductive parts 33a are electrically connected to the substrate 51. Thus, the conductive parts 33a electrically connect the stator 30 and the substrate 51. More specifically, the conductive parts 33a electrically connect the inverter circuit part 53 and the coil 33. The conductive parts 33a are passed axially through through holes provided in the substrate 51 and are electrically connected to the substrate 51 by solder or the like. A power supply terminal 80 is electrically connected to the substrate 51. The power supply terminal 80 is passed axially through through holes provided in the substrate 51 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 part 16 via the power supply terminal 80.

[0030] A magnetic sensor 70 is attached to the lower surface of the substrate 51. More specifically, the magnetic sensor 70 is attached to a portion of the lower surface of the substrate 51 that is surrounded by the upper end of the cylindrical portion 41. In this embodiment, the central axis J passes through the magnetic sensor 70. The magnetic sensor 70 is located above the sensor magnet 60 and separated therefrom. The magnetic sensor 70 faces the sensor magnet 60 in the axial direction with a gap therebetween. The magnetic sensor 70 and the sensor magnet 60 are surrounded by the cylindrical portion 41 all around the central axis J. The magnetic sensor 70 is entirely located below the upper end face of the cylindrical portion 41, except for the surface that is attached to the substrate 51.

[0031] 2, the magnetic sensor 70 is an MR sensor having a magnetoresistance effect element 73. The magnetoresistance effect element 73 is a portion of the magnetic sensor 70 that detects a magnetic field. Although not shown, the magnetoresistance effect element 73 is located below the upper end face of the cylindrical portion 41. The magnetic sensor 70 outputs two systems of signals whose phases are shifted by 180° from each other. The magnetic sensor 70 has a first bridge circuit 71 and a second bridge circuit 72.

[0032] The first bridge circuit 71 is provided between the input terminal 71v and the ground terminal 71g. The first bridge circuit 71 is configured by connecting two pairs of magnetoresistance effect elements 73a, 73b in parallel, each pair being connected in series. One pair of magnetoresistance effect elements 73a, 73b is arranged in the order of the magnetoresistance effect element 73a and the magnetoresistance effect element 73b from the input terminal 71v toward the ground terminal 71g. The other pair of magnetoresistance effect elements 73a, 73b is arranged in the order of the magnetoresistance effect element 73b and the magnetoresistance effect element 73a from the input terminal 71v toward the ground terminal 71g. A point P1a to which the input terminal 71v is connected, a point P2a to which the ground terminal 71g is connected, a point P3a between one pair of magnetoresistance effect elements 73a, 73b, and a point P4a between the other pair of magnetoresistance effect elements 73a, 73b are each connected to a point P5a. Between the point P5a and each of the points P1a, P2a, P3a, and P4a, a Zener diode 74 is provided. A first output terminal 71p is connected to the point P3a. A second output terminal 71m is connected to the point P4a.

[0033] The second bridge circuit 72 is provided between the input terminal 72v and the ground terminal 72g. The second bridge circuit 72 is configured by connecting two pairs of magnetoresistance effect elements 73c, 73d connected in series in parallel. One pair of magnetoresistance effect elements 73c, 73d are arranged in the order of the magnetoresistance effect element 73c and the magnetoresistance effect element 73d from the input terminal 72v toward the ground terminal 72g. The other pair of magnetoresistance effect elements 73c, 73d are arranged in the order of the magnetoresistance effect element 73d and the magnetoresistance effect element 73c from the input terminal 72v toward the ground terminal 72g. Point P1b to which the input terminal 72v is connected, point P2b to which the ground terminal 72g is connected, point P3b between one pair of magnetoresistance effect elements 73c, 73d, and point P4b between the other pair of magnetoresistance effect elements 73c, 73d are each connected to point P5b. A Zener diode 74 is provided between the point P5b and each of the points P1b, P2b, P3b, and P4b. A first output terminal 72p is connected to the point P3b. A second output terminal 72m is connected to the point P4b. The points P5a and P5b are connected to each other.

[0034] 2, 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 layers of the magnetoresistance effect elements 73a and 73b in the first bridge circuit 71 is opposite to the magnetization direction of the pinned layers of the magnetoresistance effect elements 73c and 73d in the second bridge circuit 72 by 90°. The magnetization direction of the pinned layer of the magnetoresistance effect element 73a and the magnetization direction of the pinned layer of the magnetoresistance effect element 73b are opposite to each other. The magnetization direction of the pinned layer of the magnetoresistance effect element 73c and the magnetoresistance effect element 73d are opposite to each other.

[0035] When the rotor 20 rotates, a sine wave (sine wave) is output from each of the first output terminal 71p and the second output terminal 71m in the first bridge circuit 71. The sine wave output from the first output terminal 71p and the sine wave output from the second output terminal 71m are out of phase with each other by 180°. A cosine wave (cosine wave) is output from each of the first output terminal 72p and the second output terminal 72m in the second bridge circuit 72. The cosine wave output from the first output terminal 72p and the cosine wave output from the second output terminal 72m are out of phase with each other by 180°. In this way, the magnetic sensor 70 outputs two systems of sine waves whose phases are out of phase with each other by 180° and two systems of cosine waves whose phases are out of phase with each other by 180° as two systems of signals.

[0036] The control unit 52 is, for example, a microprocessor such as an MCU (Microcontroller Unit). As shown in Fig. 3, the control unit 52 has a calculation unit 56, a correction unit 57, and a current control unit 58. In other words, 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 this embodiment, the calculation unit 56 calculates the electrical angle θ of the rotor 20 calculated from the output from the magnetic sensor 70. e and the mechanical angle θ of the rotor 20 mSpecifically, the calculation unit 56 calculates the mechanical angle θ based on a sine wave having twice the amplitude obtained by subtracting the output signal (−sine wave) of the second output terminal 71m from the output signal (+sine wave) of the first output terminal 71p, and a cosine wave having twice the amplitude obtained by subtracting the output signal (−cosine wave) of the second output terminal 72m from the output signal (+cosine wave) of the first output terminal 72p. m and electrical angle θ e The mechanical angle θ calculated by the calculation unit 56 is calculated. m and electrical angle θ e is input to the correction unit 57.

[0037] The correction unit 57 corrects the angle information calculated by the calculation unit 56. In this embodiment, the angle information corrected by the correction unit 57 is the electrical angle θ e The correction unit 57 receives the current value I of the power supply current supplied to the motor control device 50 from the external device connected to the connector unit 16. DC The correction unit 57 receives 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 this embodiment, the motor current supplied to the stator 30 is a three-phase AC current. m is the composite value of the three-phase AC current. The current value of the d-axis current component of the motor current is I d The current value of the q-axis current component of the motor current is I q Then, the current value I m is expressed by the following equation (1).

[0038]

number

[0039] The correction unit 57 calculates the current value I of the motor current supplied to the stator 30 of the motor 100. m and the phase angle θ of the motor current Im and the current value I of the power supply current supplied to the motor control device 50. DCand the mechanical angle θ of the rotor 20 calculated based on the output from the magnetic sensor 70. m The angle information, i.e., the electrical angle θ e Correct the following.

[0040] The motor current value is I m The phase angle of the motor current is θ Im The current value of the power supply current is I DC The mechanical angle of the rotor 20 calculated based on the output from the magnetic sensor 70 is θ m and the electrical angle of the rotor 20 calculated based on the output from the magnetic sensor 70 is θ e The correction amount is θ f Then, the following equation (2) holds.

[0041]

number

[0042] In the above formula (2), A is the motor current value I m In equation (2), P is the phase angle θ Im and mechanical angle θ m In equation (2), Z is the current value I DC The formula (2) is an experimentally obtained formula. ea The electrical angle θ of the rotor 20 calculated based on the output from the magnetic sensor 70 e Error θ er and the motor current I m , phase angle θ of motor current Im , the current value of the power supply current I DC , and the mechanical angle θ of the rotor 20 calculated based on the output from the magnetic sensor 70. m From the relationship, the formula (2) can be experimentally obtained. ea The electrical angle θ of the rotor 20 calculated based on the output from the magnetic sensor 70 eThe error can be approximated, for example, by the following equation (3).

[0043]

number

[0044] The error θ calculated from the above formula (3) er The absolute value of the value is the correction amount θ f Assuming that the absolute value of ea For each error θ er and the current value I m , phase angle θ Im , current value I DC , and mechanical angle θ m The constants C1 to C7 can be calculated by substituting these values ​​into the above equation (2) and solving the resulting equation simultaneously.

[0045] The correction unit 57 corrects the electrical angle θ of the rotor 20 calculated based on the output from the magnetic sensor 70. e The correction amount θ obtained from equation (2) f By adding the electrical angle θ e The corrected electrical angle θ ef The electrical angle θ calculated by the correction unit 57 is calculated. ef is input to the current control unit 58.

[0046] The current control unit 58 calculates the electrical angle θ ef Based on this, the current control unit 58 controls a signal to be sent to the inverter circuit unit 53, thereby controlling 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.

[0047] The inverter circuit unit 53 is configured with a plurality of switching elements. The inverter circuit unit 53 is driven based on 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 that configure the inverter circuit unit 53 are, for example, field effect transistors (FETs).

[0048] At least some of the functions of each component of the motor control device 50 described above are realized by, for example, a processor such as a CPU executing a program, i.e., software, stored in a storage unit (not shown). At least some of the functions of each component of the motor control device 50 may be realized by hardware including circuit units such as a large-scale integration (LSI), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), and a graphics processing unit (GPU), or may be realized by cooperation between software and hardware. The storage unit (not shown) is realized by, for example, a storage medium such as a random access memory (RAM), a read-only memory (ROM), a hard disk drive (HDD), and a flash memory.

[0049] Since the magnetic sensor 70 outputs two signals whose phases are shifted by 180° from each other, the calculation unit 56 described above can remove part of the influence of the external magnetic field applied to the magnetic sensor 70 by adding the two signals. 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, which is shifted in phase 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 positional shift of the magnetic sensor 70 and the variation in the characteristics of the magnetic sensor 70, the influence of the external magnetic field contained in the sine wave output from the first output terminal 71p and the second output terminal 71m varies, and there were cases where the influence of the external magnetic field could not be completely removed by the above method alone. As a result, there were cases where the rotational position of the rotor 20 could not be detected accurately.

[0050] To solve the above problem, according to the present embodiment, the correction unit 57 corrects the motor current value I m and the phase angle θ of the motor current Im and 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 θ expressed as a function including f Using 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, the correction amount θ f Using the electrical angle θ eBy correcting the above, the influence of the external magnetic field can be suitably removed. This improves the detection accuracy of the rotational position of the rotor 20. In particular, in the motor 100 mounted on a steering device mounted on a vehicle as in this 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 described above is particularly useful when the motor 100 is mounted on a steering device of a vehicle.

[0051] According to the present embodiment, the angle information corrected by the correction unit 57 is the electrical angle θ e In this embodiment, the magnetic sensor 70 detects the electrical angle θ of the rotor 20. e The MR sensor is capable of detecting the electrical angle θ of the rotor 20. e When detecting the mechanical angle θ of the rotor 20, the number of magnetic poles of the sensor magnet 60 is the same as the number of magnetic poles of the rotor 20. m When detecting the electrical angle θ, the sensor magnet 60 is a two-pole magnet having an N pole and an S pole facing each other in the radial direction. e Therefore, the accuracy of the detected value is improved by using a configuration capable of detecting the electrical angle θ e This makes it possible to further improve the detection accuracy of the rotational position of the rotor 20.

[0052] Moreover, according to this embodiment, the above-mentioned formula (2) holds true. f By calculating the electrical angle θ e It is easy to accurately correct the motor current and power supply current parameters.

[0053] According to the present embodiment, the shielding member 40 that shields the magnetic flux has a cylindrical portion 41 that surrounds the sensor magnet 60. The upper end of the cylindrical portion 41 contacts the lower surface of the substrate 51. The magnetic sensor 70 is attached to a portion of the lower surface of the substrate 51 that is surrounded by the upper end of the cylindrical portion 41. Therefore, the magnetic flux that is directed from the radial outside of the cylindrical portion 41 toward the magnetic sensor 70 can be shielded by the cylindrical portion 41. This allows the magnetic sensor 70 to detect the magnetic flux generated from the sensor magnet 60 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. Furthermore, the above-mentioned formula (2) is a formula that was 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 member 40. Therefore, in the motor 100 having this structure, the correction amount θ in formula (2) f Using the electrical angle θ e By correcting the electrical angle θ e It should be noted that even if the motor 100 does not have this structure, the electrical angle θ e Compared to when the correction amount θ f Using the electrical angle θ e By correcting the electrical angle θ e The accuracy can be improved.

[0054] Furthermore, according to this embodiment, the conductive portion 33a is located radially outward of the cylindrical portion 41. Therefore, the cylindrical portion 41 can easily shield the magnetic flux flowing toward the magnetic sensor 70 from the magnetic flux generated by the motor current flowing through the conductive portion 33a. This can reduce the effect of the external magnetic field applied to the magnetic sensor 70 by the motor current flowing through the conductive portion 33a, and can further improve the detection accuracy of the rotational position of the rotor 20.

[0055] Furthermore, according to this embodiment, the connector portion 16 that holds the power terminal 80 is located radially outward of the cylindrical portion 41. Therefore, the magnetic flux that flows toward the magnetic sensor 70, out of the magnetic flux generated by the power supply current flowing through the power supply terminal 80, is easily shielded by the cylindrical portion 41. This makes it possible to reduce the effect of the external magnetic field applied to the magnetic sensor 70 by the power supply current flowing through the power supply terminal 80, and further improves the detection accuracy of the rotational position of the rotor 20.

[0056] The present invention is not limited to the above-described embodiment, and other configurations and methods may be adopted within the scope of the technical idea of ​​the present invention. The correction amount used by the correction unit when correcting the angle information calculated by the calculation unit is not particularly limited as long as it is expressed as a function including the current value of the motor current, 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 be the mechanical angle of the rotor.

[0057] The structure of the motor on which the motor control device is mounted is not particularly limited. The shielding member does not have to be a heat sink. The conductive portion electrically connecting the stator and the substrate may have any configuration, and may be a bus bar. The conductive portion may be arranged in any manner with respect to the cylindrical portion of the shielding member. The connector portion may be arranged in any manner with respect to the cylindrical portion of the shielding member. The motor may not include a shielding member. The use of the motor is not particularly limited. The motor may be mounted in equipment other than a steering device among equipment mounted in a vehicle, or in equipment other than a vehicle.

[0058] The present technology can be configured as follows. [1] A motor control device that controls a motor, comprising: a calculation unit that calculates angle information regarding a rotational 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, wherein the magnetic sensor is a sensor having a magnetoresistive effect element and outputting two systems of signals whose phases are shifted by 180° from each other, and the correction unit corrects the angle information using a correction amount expressed 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. [2] The motor control device according to [1], wherein the angle information is an electrical angle. [3] The motor current value is I m and the phase angle of the motor current is θ Im The current value of the power supply current is I DC and the mechanical angle of the rotor calculated based on the output from the magnetic sensor is θ m and the electrical angle of the rotor calculated based on the output from the magnetic sensor is θ e The correction amount is θ f The motor control device according to [2], wherein the following equation holds:

number

[0059] The configurations and methods described in this specification can be combined as appropriate within the scope of not being mutually inconsistent. [Explanation of symbols]

[0060] 16...connector portion, 20...rotor, 23...bearing, 30...stator, 33a...conductive portion, 40...shielding member, 41...cylindrical portion, 50...motor control device, 51...substrate, 56...calculation portion, 57...correction portion, 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

Claims

1. A motor control device for controlling a motor, 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; a correction unit that corrects the angle information calculated by the calculation unit; Equipped with the magnetic sensor is a sensor having a magnetoresistance effect element and outputting two systems of signals whose phases are shifted by 180° from each other; the correction unit corrects the angle information using a correction amount expressed 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 current value of the motor current is I ｍ and the phase angle of the motor current is θ Ｉｍ The current value of the power supply current is I ＤＣ and the mechanical angle of the rotor calculated based on the output from the magnetic sensor is θ ｍ and the electrical angle of the rotor calculated based on the output from the magnetic sensor is θ ｅ The correction amount is θ ｆ 3. The motor control device according to claim 2, wherein the following formula is satisfied: [0010] However, C １ , C ２ , C ３ , C ４ , C ５ , C ６ , and C ７ is a constant.

4. A motor control device according to any one of claims 1 to 3, The rotor is rotatable about a central axis; the stator facing the rotor with a gap in the radial direction; a sensor magnet fixed to the rotor; the magnetic sensor facing the sensor magnet with a gap in the axial direction; A shielding member that shields magnetic flux; Equipped with the motor control device has a board located on one axial side of the rotor, the shielding member has a cylindrical portion surrounding the sensor magnet, an end portion on one axial side of the cylindrical portion contacts a surface on the other axial side of the substrate, The magnetic sensor is attached to 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. a conductive portion electrically connecting the stator and the substrate; The motor according to claim 4 , wherein the conductive portion is located radially outward from the cylindrical portion.

6. a connector portion for holding a power terminal electrically connected to the board; The motor according to claim 4 , wherein the connector portion is located radially outward from 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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