Rotation angle detection device, motor control device, electric actuator product, electric power steering device, and rotation angle detection method

Abstract

To suppress the impact of noise when correcting a sensor signal including a sine signal and a cosine signal output according to rotation of a rotor on the basis of a peak value of the sensor signal.SOLUTION: A rotation angle detection device comprises: a sensor 19 which outputs a sensor signal including a sine signal and a cosine signal according to rotation of a rotor; lowpass filters (70 to 73) to which the sensor signal is input; peak value acquisition units (76 to 78) which acquire a peak value of the sensor signal having been subjected to filter processing by the lowpass filters (70 to 73) and corrected by gains of the lowpass filters (70 to 73); and a correction amount calculation unit 80 which calculates a correction amount for correcting the sensor signal according to the peak value.SELECTED DRAWING: Figure 15

Description

[Technical Field]

[0001] The present invention relates to a rotation angle detection device, a motor control device, an electric actuator product, an electric power steering device, and a rotation angle detection method. [Background technology]

[0002] Patent Document 1 describes a position detection device that detects the rotational position of a rotating body based on sine and cosine signals corresponding to the rotation of the rotating body. This position detection device acquires the peak values ​​(maximum and minimum values) of the sine and cosine signals and corrects the errors of the sine and cosine signals based on the peak values. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2001-296142 [Overview of the project] [Problems that the invention aims to solve]

[0004] When correcting a sensor signal, which includes sine and cosine signals output from a sensor in response to the rotation of a rotating body (such as the rotating shaft of a motor), based on the peak value of the sensor signal, it may not be possible to detect the accurate peak value due to the influence of noise. This invention has been made in view of these circumstances, and aims to suppress the influence of noise on the detection of peak values ​​when correcting a sensor signal, which includes a sine signal and a cosine signal output from a sensor in accordance with the rotation of a rotating body, based on the peak value of the sensor signal. [Means for solving the problem]

[0005] To achieve the above objective, a rotation angle detection device according to one aspect of the present invention comprises: a sensor that outputs a sensor signal including a sine signal and a cosine signal in accordance with the rotation of a rotating body; a low-pass filter to which the sensor signal output from the sensor is input; a peak value acquisition unit that acquires the peak value of the sensor signal that has been filtered by the low-pass filter and corrected by the gain of the low-pass filter; a correction amount calculation unit that calculates a correction amount for correcting the sensor signal according to the peak value; a correction unit that corrects the sensor signal output from the sensor based on the correction amount; and a rotation angle calculation unit that calculates the rotation angle of the rotating body based on the sensor signal corrected by the correction unit.

[0006] A motor control device according to another aspect of the present invention comprises the above-described rotation angle detection device and a drive unit that drives the motor based on the rotation angle corrected by the rotation angle correction unit. An electric actuator product according to yet another aspect of the present invention comprises a motor control device and a motor controlled by the motor control device. An electric power steering system according to yet another aspect of the present invention comprises a motor control device and a motor controlled by the motor control device, wherein the motor provides steering assistance to the steering system of the vehicle.

[0007] According to yet another aspect of the present invention, a rotation angle detection method is provided for detecting the rotation angle of a rotating body based on a sensor signal including a sine signal and a cosine signal output from a sensor in response to the rotation of the rotating body. In the rotation angle detection method, the sensor signal output from the sensor is filtered by a low-pass filter to obtain a filtered sensor signal, the peak value of the sensor signal that has been filtered by the low-pass filter and corrected by the gain of the low-pass filter is obtained, the sensor signal output from the sensor is corrected based on a correction amount corresponding to the peak value, and the rotation angle of the rotating body is calculated based on the corrected sensor signal. [Effects of the Invention]

[0008] According to the present invention, when correcting a sensor signal, which includes a sine signal and a cosine signal output from a sensor in response to the rotation of a rotating body, based on the peak value of the sensor signal, the influence of noise on the detection of the peak value can be suppressed. [Brief explanation of the drawing]

[0009] [Figure 1] This is a configuration diagram showing an overview of an example of an electric power steering system according to an embodiment. [Figure 2] Figure 1 is a configuration diagram showing an overview of the control device's configuration. [Figure 3] This is an explanatory diagram of a magnet and magnetic sensor fixed to the motor's rotating shaft. [Figure 4] Figure 1 is a block diagram showing an example of the functional configuration of the control device. [Figure 5] Figure 4 is a block diagram showing an example of the functional configuration of the detection signal correction unit. [Figure 6] (a) to (c) are diagrams illustrating the offset error, amplitude error, and phase error of sine and cosine signals, respectively. [Figure 7] Figure 1 is a schematic diagram showing an example of the layout of the magnetic sensor, power supply terminals, and motor output terminals on the power board. [Figure 8] This is an explanatory diagram of magnetic fields, multiphase current fields, and their combined magnetic fields. [Figure 9] Figure 4 is a flowchart illustrating an example of processing performed by the rotation angle correction unit. [Figure 10] (a) and (b) are explanatory diagrams of the first example of simulation results for the direction and strength of the current magnetic field, (c) is a diagram showing the angular error due to the current magnetic field before and after correction by the rotation angle correction unit, and (d) is a magnified view of the angular error after correction. [Figure 11] (a) and (b) are explanatory diagrams of a second example of the simulation results for the direction and strength of the current magnetic field, (c) is a diagram showing the angular error due to the current magnetic field before and after correction by the rotation angle correction unit, and (d) is a magnified view of the angular error after correction. [Figure 12](a) and (b) are explanatory diagrams of a third example of simulation results of the direction and intensity of a current magnetic field, (c) is a diagram showing angular errors caused by the current magnetic field before and after correction by a rotation angle correction unit, and (d) is an enlarged view of the angular error after correction. [Figure 13] (a) and (b) are explanatory diagrams of a fourth example of simulation results of the direction and intensity of a current magnetic field, (c) is a diagram showing angular errors caused by the current magnetic field before and after correction by a rotation angle correction unit, and (d) is an enlarged view of the angular error after correction. [Figure 14] It is a block diagram of an example of the functional configuration of the motor control unit in FIG. 4. [Figure 15] It is a block diagram of an example of the functional configuration of the correction amount setting unit in FIG. 4. [Figure 16] It is a flowchart of an example of processing by the correction amount setting unit. [Figure 17] It is an explanatory diagram of simulation results of amplitudes of a sensor signal before and after correction after passing through a low-pass filter. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0010] Embodiments of the present invention will be described in detail with reference to the drawings. The embodiments of the present invention described below exemplify apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention does not specify the configuration, arrangement, and the like of component parts to those described below. Various changes can be made to the technical idea of the present invention within the technical scope defined by the claims set forth in the claims.

[0011] In the following description, an example of a rotation angle detection device that detects the rotation angle of the rotating shaft of a three-phase AC motor that applies a steering assist force to an electric power steering apparatus will be described. However, the present invention is not limited to application to electric power steering apparatuses, and can be widely applied to rotation angle detection devices that detect the rotation angle of a rotating shaft of a rotating body used in various applications, motor control devices for motors having a rotating shaft, and electric actuator products including a motor.

[0012] (composition) Figure 1 is a schematic diagram showing an example of an electric power steering system according to an embodiment. The column shaft (steering shaft) 2 of the steering wheel (steering handle) 1 is connected to the steering wheels 8L and 8R via hub units 7a and 7b, through a reduction gear (worm gear) 3, universal joints 4a and 4b, a pinion rack mechanism 5, tie rods 6a and 6b that constitute a reduction mechanism.

[0013] The pinion rack mechanism 5 includes a pinion 5a connected to a pinion shaft that receives steering force from a universal joint 4b, and a rack 5b that meshes with the pinion 5a. The rotational motion transmitted to the pinion 5a is converted into straight-line motion in the vehicle width direction by the rack 5b. The steering shaft 2 is equipped with a torque sensor 9 that detects the steering torque Th applied to the steering wheel 1, and a motor 20 that assists the steering force of the steering wheel 1 according to the steering torque Th is connected to the column shaft 2 via a reduction gear 3. For example, a multiphase AC motor may be used as motor 20. In this embodiment, an example is described in which a three-phase AC motor having A phase, B phase, and C phase is used as motor 20.

[0014] The control device 10 is an electronic control unit (ECU) that drives and controls the motor 20. Power is supplied to the control device 10 from the battery 11, which is the power source, and the ignition key signal IGN is input from the ignition key 12. The control device 10 calculates the steering assist command value of the assist command using an assist map or the like based on the steering torque Th detected by the torque sensor 9, and supplies drive current to the motor 20 based on the calculated steering assist command value.

[0015] Figure 2 is a schematic diagram showing the configuration of the control device 10 shown in Figure 1. The control device 10 comprises a control board 13 that performs signal processing for the control system, a power board 14 on which a drive circuit such as an inverter circuit for driving the motor 20 is formed, and a temperature sensor 15. The control board 13 and the power board 14 may be formed as a single board. The control board 13 includes a control circuit that includes, for example, a processor 13a, such as a CPU (Central Processing Unit) or MPU (Micro-Processing Unit), and peripheral components such as a storage device 13b.

[0016] The storage device 13b may include semiconductor storage devices such as registers, cache memory, and main memory such as ROM (Read Only Memory) and RAM (Random Access Memory), as well as magnetic storage devices, optical storage devices, etc. The signal processing of the control device 10 described below is realized, for example, by the processor 13a executing a computer program stored in the storage device 13b. Furthermore, the control board 13 may be equipped with dedicated hardware (for example, a programmable logic device such as an FPGA (Field-Programmable Gate Array)) for performing the information processing described below.

[0017] The power board 14 is equipped with a drive circuit 16, current sensors 17 and 18, and a magnetic sensor 19. The drive circuit 16 includes an inverter circuit for driving the motor 20, and according to the PWM (Pulse Width Modulation) signal output from the control board 13, it generates three phase currents Ia, Ib, and Ic (A, B, and C phases) from the DC power supply provided by the battery 11 and supplies them to the motor 20 as drive current. The current sensor 17 detects the DC power supply current Ibat supplied from the battery 11 to the drive circuit 16 and outputs a detection signal to the control board 13.

[0018] The current sensor 18 detects the three-phase currents Ia, Ib, and Ic supplied from the drive circuit 16 to the motor 20 and outputs a detection signal to the control board 13. The magnetic sensor 19 detects the direction of the magnetic field Bm generated from a magnet fixed to the rotation shaft of the motor 20, and outputs a sensor signal to the control board 13 that includes a sine signal SIN0 and a cosine signal COS0 corresponding to the rotation angle of the rotation shaft.

[0019] Figure 3 is an explanatory diagram of a magnet and magnetic sensor 19 fixed to the rotating shaft of the motor 20. The magnet 24 is fixed, for example, to the end 23 opposite the output end 22 of the rotating shaft 21 of the motor 20, and has different magnetic poles (south pole and north pole) arranged along the circumferential direction of the rotating shaft 21. The magnetic sensor 19 may be, for example, an MR (Magnetic Resistance) sensor whose electrical resistance changes in response to a magnetic field. The magnetic sensor 19 is positioned in close proximity to and opposite to the magnet 24, and by detecting the magnetic flux generated from the magnet 24, it generates a sine signal SIN0 = A × sinθ and a cosine signal COS0 = A × cosθ corresponding to the electrical angle θ of the motor 20.

[0020] Refer to Figure 2. The temperature sensor 15 is positioned near the magnet 24 to measure the temperature Tp in the vicinity of the magnet 24 and outputs the measurement signal to the control board 13. Figure 4 is a block diagram of an example of the functional configuration of the control device 10. The control device 10 includes a detection signal correction unit 30, a rotation angle calculation unit 31, a rotation angle correction unit 32, a linearity correction unit 33, an origin correction unit 34, a motor control unit 35, and a correction amount setting unit 36.

[0021] The detection signal correction unit 30 corrects the sine signal SIN0 and cosine signal COS0, which are output from the magnetic sensor 19 and converted into digital signals by an analog-to-digital converter (not shown), based on the correction amount data G1, Cs, Cc, and G2 calculated in the correction amount setting unit 36. The correction amount data G1, Cs, Cc, and G2 are a first gain for correcting the amplitude error of the cosine signal COS0, a sine offset correction value for correcting the offset error of the sine signal SIN0, a cosine offset correction value for correcting the offset error of the cosine signal COS0, and a second gain for correcting the phase error between the sine signal SIN0 and the cosine signal COS0, respectively. The method for setting the first gain G1, sine offset correction value Cs, cosine offset correction value Cc, and second gain G2 using the correction amount setting unit 36 ​​will be described later.

[0022] Figure 5 is a block diagram of an example of the functional configuration of the detection signal correction unit 30. The detection signal correction unit 30 includes a SIN offset correction unit 40, a COS offset correction unit 41, a COS gain correction unit 42, an adder 43, a subtractor 44, and a phase error correction unit 45. The SIN offset correction unit 40 calculates a SIN signal SIN1 by subtracting the SIN offset correction value Cs from the SIN signal SIN0, thereby removing the offset error (see Figure 6(a)) from the SIN signal SIN0.

[0023] The COS offset correction unit 41 removes the offset error from the cosine signal COS0 by subtracting the cosine offset correction value Cc from the cosine signal COS0. The COS gain correction unit 42 calculates the product obtained by multiplying the cosine signal COS from which the offset error has been removed by the first gain G1 as the cosine signal COS1, thereby making the amplitudes of the sine signal SIN1 and the cosine signal COS1 equal. This corrects the amplitude error between the sine signal SIN0 and the cosine signal COS0 (see Figure 6(b)).

[0024] The adder 43 calculates the sum obtained by adding the sine signal SIN1 and the cosine signal COS1 as the sum signal SA = (COS1 + SIN1). The adder 43 outputs the sum signal SA = (COS1 + SIN1) to the rotation angle calculation unit 31 and the correction amount setting unit 36. The subtractor 44 calculates the difference (COS1-SIN1) between the sine signal SIN1 and the cosine signal COS1. The subtractor 44 outputs the difference (COS1-SIN1) to the correction amount setting unit 36. The phase error correction unit 45 calculates the difference signal SD = G2 × (COS1 - SIN1) by multiplying the difference (COS1 - SIN1) by the second gain G2. This removes the effect of the phase error between the sine signal SIN1 and the cosine signal COS1 (see Figure 6(c)) from the sum signal SA and the difference signal SD. The phase error correction unit 45 outputs the difference signal SD to the rotation angle calculation unit 31.

[0025] Refer to Figure 4. The rotation angle calculation unit 31 calculates the measured electrical angle θ0 of the motor 20 based on the sum signal SA and the difference signal SD. The rotation angle correction unit 32 corrects the angle error that occurs in the measured angle θ0 calculated by the rotation angle calculation unit 31 using the magnetic field generated at the position of the magnetic sensor 19 by the three-phase currents Ia, Ib, and Ic and the power supply current Ibat. The rotation angle correction unit 32 is an example of a "current magnetic field calculation unit," an "angle correction amount calculation unit," and a "rotation angle correction unit."

[0026] Hereinafter, the magnetic field generated at the magnetic sensor 19 by the three-phase currents Ia, Ib, and Ic will be referred to as the "multiphase current magnetic field Bi," and the magnetic field generated at the magnetic sensor 19 by the power supply current Ibat will be referred to as the "power supply current magnetic field Bp." In addition, the multiphase current magnetic field Bi and the power supply current magnetic field Bp may be collectively referred to as the "current magnetic field." In the following description, we show an example in which the rotation angle correction unit 32 corrects both the angular error caused by the multiphase current magnetic field Bi and the angular error caused by the power supply current magnetic field Bp. However, the rotation angle correction unit 32 may correct only one of the angular errors caused by the multiphase current magnetic field Bi or the angular error caused by the power supply current magnetic field Bp.

[0027] Figure 7 is a schematic diagram of an example layout of the magnetic sensor 19 on the power board 14, the power terminal to which the power supply current Ibat is input, and the motor output terminal to which the three-phase currents Ia, Ib, and Ic are output. In Figure 7, the X and Y directions are parallel to the power board 14 and are orthogonal to each other. The Z direction is perpendicular to the power board 14 and parallel to the rotation axis 21 of the motor 20. The orientations in the X and Y directions may be set arbitrarily. In this specification, an example is described in which the direction of the magnetic field Bm of the magnet 24 is set to the positive X direction when the electrical angle of the motor 20 is 0 [deg].

[0028] Furthermore, this specification describes the case where the motor 20 is a double-winding motor having a set of winding pairs consisting of a first motor winding and a second motor winding. The rotation angle correction unit 32 receives the three-phase currents Ia, Ib, and Ic of the two systems and the power supply current Ibat of the two systems as input. Reference numeral 50a, 50b, and 50c are motor output terminals that output the first system of three-phase current (A-phase current Ia, B-phase current Ib, and C-phase current Ic), respectively, and reference numeral 51a, 51b, and 51c are motor output terminals that output the second system of three-phase current. Motor output terminals 50a-50c and 51a-51c are arranged to extend in the Z direction so as to penetrate the power board 14 vertically. Hereinafter, the motor output terminals for the A-phase, B-phase, and C-phase may be referred to as "A-phase terminal," "B-phase terminal," and "C-phase terminal," respectively.

[0029] Furthermore, reference numerals 52p and 52m are power terminals to which the first power supply current Ibat is input, reference numeral 53 is a coil for removing noise contained in the first power supply current Ibat, and reference numerals 53in and 53out are the input and output terminals of coil 53. Reference numerals 54p and 54m are power terminals to which the second power supply current is input, reference numeral 55 is a coil for removing noise contained in the second power supply current, and reference numerals 55in and 55out are the input and output terminals of coil 55.

[0030] The power terminals 52p, 52m, 54p, and 54m, the input terminals 53in and 55in, and the output terminals 53out and 55out are also arranged to extend in the Z direction so as to penetrate the power board 14 vertically. During powering, it is defined that the power supply current flows from the front to the back of the paper through the positive power supply terminals 52p and 54p and the output terminals 53out and 55out, and that the power supply current flows from the back to the front of the paper through the negative power supply terminals 52m and 54m and the input terminals 53in and 55in. During regeneration, the direction of the power supply current is reversed. Furthermore, the signs of the three-phase currents Ia, Ib, and Ic in the two systems were defined as positive when the current direction is from the front to the back of the paper. The definitions of the direction and sign of the power supply current and three-phase current can be changed to suit the mounting conditions on the circuit board. The formulas described later will be modified to match the definitions of direction and sign.

[0031] The A-phase terminal 50a of the first system and the A-phase terminal 51a of the second system are positioned symmetrically with respect to the center point Pc of the magnetic sensor 19. The same applies to the B-phase terminals 50b and 51b, the C-phase terminals 50c and 51c, the positive power supply terminals 52p and 54p, the negative power supply terminals 52m and 54m, the input terminals 53in and 55in, and the output terminals 53out and 55out.

[0032] Therefore, when the magnitude and direction of the three-phase currents of the first and second systems are equal, and the magnitude and direction of the power supply currents of the first and second systems are equal, the current magnetic field generated at the center point Pc of the magnetic sensor 19 by the three-phase current and power supply current of the first system cancels out with the current magnetic field generated by the three-phase current and power supply current of the second system. As a result, no angular error occurs in the measurement angle θ0 due to the three-phase current and power supply current. In this case, correction of the angular error by the rotation angle correction unit 32 is unnecessary. However, if only one of the first or second systems is driven, or if the load distribution between the first and second systems is different, the current-magnetic field generated by the first system and the current-magnetic field generated by the second system will no longer cancel each other out. Therefore, the rotation angle correction unit 32 corrects the angle error that occurs in the measured angle θ0 due to the three-phase current and the power supply current in these cases.

[0033] The following describes the correction of angular errors caused by the three-phase currents Ia, Ib, Ic and the power supply current Ibat of the first system, but the same method can be used to correct angular errors in the second system. When both the first and second systems are driven with different load distributions (i.e., when the currents of the first and second systems are different), the current-magnetic field should be calculated for each of the first and second systems, and the amount of angular error correction should be calculated based on the combined current-magnetic field of the first and second systems.

[0034] First, we will explain how to calculate the first angle correction amount θi, which corrects the angle error caused by the multiphase current magnetic field Bi. Let the distances from the center point Pc to the A-phase terminals 50a, B-phase terminals 50b, and C-phase terminals 50c be distances ra, rb, and rc, respectively, and let the angles θa, θb, and θc be the angles made between the direction from the center point Pc to the A-phase terminals 50a, B-phase terminals 50b, and C-phase terminals 50c and the X-axis, respectively.

[0035] In the example layout shown in Figure 7, the A-phase terminal 50a, B-phase terminal 50b, and C-phase terminal 50c are arranged along the Y-direction perpendicular to the X-direction, with distances ra and rb being equal (ra=rb), C-phase terminal 50c being on the X-axis with the center point Pc as the origin (θc=0), and angles θa and θb being equal in magnitude and opposite in direction (θb=-θa). That is, C-phase terminal 50c is at the midpoint of the line connecting A-phase terminal 50a and B-phase terminal 50b, and the distance d1 between A-phase terminal 50a and C-phase terminal 50c is equal to the distance d2 between B-phase terminal 50b and C-phase terminal 50c. Note that the positive X-axis is used as the reference point, and counterclockwise angles are considered positive in this explanation.

[0036] The rotation angle correction unit 32 calculates the multiphase current magnetic field Bi according to the following equation (1).

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[0037] The rotation angle correction unit 32 calculates the mechanical angle θm of the rotation axis of the motor 20 based on the measured angle θ0 calculated by the rotation angle calculation unit 31. Furthermore, the rotation angle correction unit 32 calculates the absolute value Bt of the magnetic field Bm generated by the magnet 24 at the center point Pc of the magnetic sensor 19, based on the temperature Tp near the magnet 24 detected by the temperature sensor 15. For example, the rotation angle correction unit 32 may calculate the absolute value Bt according to the following equation (2) based on the results of a prior magnetic field strength analysis. Bt = B20 - K(Tp-20) … (2) In equation (2) above, B20 is the magnetic field when the temperature Tp near the magnet 24 is 20°C, and K is the temperature coefficient of the magnet 24. Although a method for detecting temperature using the temperature sensor 15 has been shown, a temperature estimation unit that estimates the temperature near the magnet 24 may be provided instead. For example, the characteristic that the magnitudes of the sine signal SIN0 and cosine signal COS0 generated by the magnetic sensor 19 change proportionally with temperature can be utilized. The temperature may be estimated from the ratio of the amplitudes (square root of the sum of squares) of the sine signal SIN0 and cosine signal COS0 at a reference temperature to the amplitudes of the sine signal SIN0 and cosine signal COS0 when measured. Alternatively, the change in the amplitude of one of the signals may be used. Furthermore, various temperature estimation methods can be used.

[0038] The rotation angle correction unit 32 calculates the magnetic field Bm according to the following equation (3).

number

[0039] Figure 8 shows the magnetic field Bm, the multiphase current magnetic field Bi, and their combined magnetic field Bmi. The sine signal SIN0 and cosine signal COS0 generated by the magnetic sensor 19 are signals indicating the direction of the combined magnetic field Bmi vector. Therefore, the rotation angle correction unit 32 calculates a first angle correction amount θi to correct the direction of the combined magnetic field Bmi vector to the direction of the magnetic field Bm vector. The formula for deriving the first angle correction amount θi is given by the following equation (4).

[0040]

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[0041] Since the multiphase current magnetic field Bi is very small compared to the magnetic field Bm (|Bi| << |Bm|), we approximate the denominator of the fraction in equation (4) above with |Bm|, and tan -1 Approximation formula for x (xx) 3 / 3+x 5 / 5-x 7 Calculating up to the first term of / 7…) yields the approximate formula (5) for the first angle correction amount θi.

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[0042] Next, we will explain how to calculate the second angle correction amount θp, which corrects the angle error caused by the power supply current magnetic field Bp. Refer to Figure 7. The distances from the center point Pc to the negative power supply terminal 52m and the positive power supply terminal 52p are denoted as distance rd and re, respectively, and the angles θd and θe are denoted as the angles made between the direction from the center point Pc to the power supply terminals 52m and 52p and the Y-axis, respectively. Further, let the distances from the center point Pc to the input terminal 53in and the output terminal 53out of the coil 53 be distances rf and rg, respectively, and let the angles formed by the Y-axis and the directions from the center point Pc toward the input terminal 53in and the output terminal 53out be angles θf and θg, respectively.

[0043] In the layout example shown in FIG. 7, the power supply terminal 52m and the power supply terminal 52p are arranged along the X direction, and the midpoint of the straight line connecting the power supply terminal 52m and the power supply terminal 52p lies on the Y-axis with the center point Pc as the origin (rd=re, θd=-θe). Therefore, the distances d3 and d4 between the Y-axis and the power supply terminal 52m and the power supply terminal 52p are equal (d3=d4) Further, the input terminal 53in and the output terminal 53out are arranged along the Y direction, the distances from the X-axis to the input terminal 53in and the output terminal 53out are distances df and dg, respectively, and the distance from the Y-axis to the input terminal 53in and the output terminal 53out is d5. Therefore, rf=(df 2 +d5 2 ) -2 , rg=(dg 2 +d5 2 ) -2 , θf=tan -1 (d5 / df), θg=tan -1 (d5 / dg). Note that counterclockwise angles are defined as positive with reference to the positive Y-axis.

[0044] The rotation angle correction unit 32 calculates the power supply current magnetic field Bp according to the following formula (6).

数学的表記

[0045] The rotation angle correction unit 32 calculates the second angle correction amount θp based on an approximation formula (7) similar to the approximation formula (5) for the first angle correction amount θi.

number

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[0046] Figure 9 is a flowchart illustrating an example of processing performed by the rotation angle correction unit 32. In step S1, the rotation angle calculation unit 31 calculates the measured electrical angle θ0 of the motor 20. In step S2, the temperature sensor 15 measures the temperature Tp near the magnet 24. In step S3, the rotation angle correction unit 32 calculates the magnetic field Bm generated by the magnet 24 at the position of the center point Pc of the magnetic sensor 19. In step S4, the rotation angle correction unit 32 calculates the multiphase current magnetic field Bi generated by the three phase currents Ia, Ib, and Ic at the center point Pc of the magnetic sensor 19.

[0047] In step S5, the rotation angle correction unit 32 calculates the power supply current magnetic field Bp generated at the center point Pc of the magnetic sensor 19 when the power supply current Ibat is generated. In step S6, the rotation angle correction unit 32 calculates a third angle correction amount θip to correct the angle error caused by the combined magnetic field of the multiphase current magnetic field Bi and the power supply current magnetic field Bp. In step S7, the rotation angle correction unit 32 corrects the measured angle θ0 by the third angle correction amount θip and calculates the corrected rotation angle θc0 = θ0 + θip. The process then ends.

[0048] The simulation results of the correction effect by the rotation angle correction unit 32 are shown in Figures 10(a) to 10(d), 11(a) to 11(d), 12(a) to 12(d), and 13(a) to 13(d). The motor has 6 pole pairs. In all of these simulations, only one system was driven. Figures 10(a) to 10(d) show the simulation results when the d-axis current and power supply current Ibat are 70[A] and 52.5[A], respectively.

[0049] Figures 11(a) to 11(d) show the simulation results when the q-axis current and power supply current Ibat are 70[A] and 52.5[A], respectively. Figures 12(a) to 12(d) show the simulation results when the d-axis current, q-axis current, and power supply current Ibat are 18.12[A], 67.61[A], and 52.5[A], respectively. Figures 13(a) to 13(d) show the simulation results when the d-axis current, q-axis current, and power supply current Ibat are 35[A], 60.62[A], and 52.5[A], respectively.

[0050] In each figure, the horizontal axis represents the mechanical angle [deg] of the motor 20. Figures 10(a) to 13(a) and 10(b) to 13(b) show the direction of the current magnetic field and the ratio of the magnitude of the current magnetic field to the magnitude of the magnetic field at each mechanical angle. In Figures 10(c) to 13(c), the dashed lines show the magnitude of the angular error included in the measured angle θ0 before correction by the rotation angle correction unit 32, and the solid lines show the magnitude of the angular error included in the corrected rotation angle θc0. Figures 10(d) to 13(d) are enlarged views of the angular error included in the corrected rotation angle θc0. These simulation results show that the angular error in the corrected rotation angle θc0 can be made significantly smaller compared to the angular error in the uncorrected measured angle θ0.

[0051] Refer to Figure 4. The linearity correction unit 33 corrects the linearity of the corrected rotation angle θc0 based on the linearity correction data that has been created and stored in advance, and outputs it as the corrected rotation angle θc1. The linearity correction data may be, for example, correction map data that associates the value of the corrected rotation angle θc0 output from the rotation angle correction unit 32 with the value of the corrected rotation angle θc1 which has good linearity. The origin correction unit 34 corrects the phase difference between the corrected rotation angle θc1 and the rotation axis 21 of the motor 20 based on linearity correction data that has been created and stored in advance, and outputs it as the corrected rotation angle θc2. As linearity correction data, for example, the amount of phase difference between the corrected rotation angle θc1 and the rotation axis 21 may be measured and used. The origin correction unit 34 outputs the corrected rotation angle θc2 to the motor control unit 35. In this embodiment, the origin correction unit 34 is provided after the linearity correction unit 33, but instead, the linearity correction unit 33 may be provided after the origin correction unit 34.

[0052] The motor control unit 35 receives the corrected rotation angle θc2 calculated by the origin correction unit 34, the detected steering torque Th from the torque sensor 9, and the detected three-phase currents Ia, Ib, and Ic from the current sensor 18. The motor control unit 35 generates a PWM signal, which is a control signal for driving the motor 20 via the drive circuit 16, based on the corrected rotation angle θc2, the steering torque Th, and the three-phase currents Ia, Ib, and Ic. The motor control unit 35 drives the first and second systems, but the following description will focus on one system. A similar configuration can be adopted for the second system.

[0053] Figure 14 is a block diagram of an example of the functional configuration of the motor control unit 35. The motor control unit 35 comprises a differentiator 60, a current command value calculation unit 61, a 3-phase / 2-phase conversion unit 62, subtractors 63 and 64, PI (proportional-integral) control units 65 and 66, a 2-phase / 3-phase conversion unit 67, and a PWM control unit 68. The differentiator 60 calculates the rotational speed of the motor 20 (i.e., the rotational angular velocity of the rotation axis 21) ω by differentiating the corrected rotation angle θc2.

[0054] The current command value calculation unit 61 calculates the d-axis current command value Idref and the q-axis current command value Iqref using the steering torque Th and the rotational speed ω. The 3-phase / 2-phase conversion unit 62 converts the 3-phase currents Ia, Ib, and Ic into 2-phase currents, the d-axis motor current Idm and the q-axis motor current Iqm, using the corrected rotation angle θc2. Subtractor 63 calculates the deviation Id (=Idref-Idm) between the d-axis current command value Idref and the feedbacked d-axis motor current value Idm. Subtractor 64 calculates the deviation Iq (=Iqref-Iqm) between the q-axis current command value Iqref and the feedbacked q-axis motor current value Iqm.

[0055] The PI control unit 65 determines the d-axis voltage command value Vdref based on the deviation Id. Similarly, the PI control unit 66 determines the q-axis voltage command value Vqref based on the deviation Iq. The 2-phase / 3-phase conversion unit 67 uses the corrected rotation angle θc2 to convert the 2-phase voltages, consisting of the d-axis voltage command value Vdref and the q-axis voltage command value Vqref, into 3-phase voltages (A-phase voltage command value Varef, B-phase voltage command value Vbref, and C-phase voltage command value Vcref) by, for example, spatial vector modulation (spatial vector transformation). The PWM control unit 68 generates a control signal (PWM signal) to control the drive circuit 16 by PWM control based on the A-phase voltage command value Varef, the B-phase voltage command value Vbref, and the C-phase voltage command value Vcref.

[0056] Refer to Figure 4. The correction amount setting unit 36 ​​calculates a first gain G1 to correct the amplitude error of the cosine signal COS0, a sine offset correction value Cs to correct the offset error of the sine signal SIN0, and a cosine offset correction value Cc to correct the offset error of the cosine signal COS0, based on the peak values ​​of the sine signal SIN0 and cosine signal COS0 output from the magnetic sensor 19.

[0057] Specifically, the correction amount setting unit 36 ​​acquires the maximum value max(COS0) and minimum value min(COS0), which are the peak values ​​of the cosine signal COS0. It also acquires the maximum value max(SIN0) and minimum value min(SIN0), which are the peak values ​​of the sine signal SIN0. The correction amount setting unit 36 ​​calculates the amplitude of the cosine signal COS0, Ax = (max(COS0) - min(COS0)) / 2, and the amplitude of the sine signal SIN0, Ay = (max(SIN0) - min(SIN0)) / 2.

[0058] The correction amount setting unit 36 ​​calculates the ratio of amplitude Ay to amplitude Ax (Ay / Ax) as the first gain G1. Furthermore, the correction amount setting unit 36 ​​calculates the sine offset correction value Cs = (max(SIN0) + min(SIN0)) / 2 and the cosine offset correction value Cc = (max(COS0) + min(COS0)) / 2.

[0059] Next, the correction amount setting unit 36 ​​calculates a second gain G2 to correct the phase error between the cosine signal COS0 and the sine signal SIN0, based on the peak value of the sum (COS1+SIN1) of the cosine signal COS1, which has been corrected for amplitude error and offset error, and the peak value of the difference (COS1-SIN1) of the sine signal SIN1, which has been corrected for offset error, and the difference between them. Specifically, the maximum value max(COS1+SIN1) and minimum value min(COS1+SIN1) of the sum (COS1+SIN1) are obtained. Additionally, the maximum value max(COS1-SIN1) and minimum value min(COS1-SIN1) of the difference (COS1-SIN1) are obtained.

[0060] The correction amount setting unit 36 ​​calculates the ratio ((max(COS1+SIN1)-min(COS1+SIN1)) / (max(COS1-SIN1)-min(COS1-SIN1))) which matches the amplitude of the difference (COS1-SIN1) to the amplitude of the sum (COS1+SIN1), as the second gain G2. The correction amount setting unit 36 ​​calculates the first gain G1, sine offset correction value Cs, cosine offset correction value Cc, and second gain G2 based on the peak values ​​of the sine signal SIN0, cosine signal COS0, sum (COS1+SIN1), and difference (COS1-SIN1) as described above. However, in order to accurately calculate these correction amount data G1, Cs, Cc, and G2, it is necessary to detect accurate peak values.

[0061] However, simply comparing the previous and current values ​​of these signals using peak hold (i.e., the process of storing the peak value) may not accurately detect the peak value due to the influence of noise. Noise in the signal can be removed by filtering with a low-pass filter, but this filtering process attenuates the signal amplitude, making it impossible to detect the accurate peak value.

[0062] Therefore, the correction amount setting unit 36 ​​applies a low-pass filter to the sine signal SIN0, the cosine signal COS0, the sum (COS1 + SIN1), and the difference (COS1 - SIN1). Furthermore, it calculates the gain of the low-pass filter based on the known frequency characteristics of the low-pass filter and the rotation speed ω of the motor 20. Then, the sine signal SIN0, cosine signal COS0, sum (COS1+SIN1), and difference (COS1-SIN1), which have been filtered by a low-pass filter, are corrected by the gain of the low-pass filter, and the corrected peak value, which is the peak value of the corrected signal, is detected.

[0063] Alternatively, after detecting the peak values ​​of the sine signal SIN0, cosine signal COS0, sum (COS1+SIN1), and difference (COS1-SIN1) filtered by a low-pass filter, the peak values ​​may be corrected using the gain of the low-pass filter to obtain the corrected peak values. This allows for the removal of noise contained in the sine signal SIN0, cosine signal COS0, sum (COS1+SIN1), and difference (COS1-SIN1), while maintaining their amplitudes. The correction amount setting unit 36 ​​calculates correction amount data G1, Cs, Cc, and G2 based on the corrected peak values ​​acquired in this manner.

[0064] Figure 15 is a block diagram of an example of the functional configuration of the correction amount setting unit 36. The correction amount setting unit 36 ​​comprises low-pass filters 70, 71, 72, 73, and 75, an angle difference calculation unit 74, a gain calculation unit 76, an amplitude correction unit 77, a peak hold unit 78, an implementation determination unit 79, and a correction amount calculation unit 80. In the drawing, the low-pass filter is denoted as "LPF". Note that the gain calculation unit 76, amplitude correction unit 77, and peak hold unit 78 are examples of "peak value acquisition units".

[0065] Low-pass filters 70, 71, 72, and 73 apply filtering to the sine signal SIN0, the cosine signal COS0, the sum (COS1 + SIN1), and the difference (COS1 - SIN1), respectively. For example, a first-order LPF, a second-order Butterworth filter, or a four-point moving average filter may be used as the low-pass filters 70, 71, 72, 73, and 75. The frequency characteristics of the low-pass filters 70, 71, 72, 73, and 75 should be set appropriately according to the frequencies in which strong noise is present in the signal. For example, the frequency characteristics of the low-pass filters 70, 71, 72, 73, and 75 may be set to sufficiently attenuate high-frequency components, including the 1000 Hz component.

[0066] In the following, this specification will describe examples in which a four-point moving average filter is used as the low-pass filter 70, 71, 72, 73, and 75. The angle difference calculation unit 74 calculates the rotational speed ω of the motor 20 by calculating (i.e., differentiating) the change in the measured angle θ0 per unit time. The low-pass filter 75 filters the rotational speed ω. The filtered rotational speed ω is input to the gain calculation unit 76. In this embodiment, the low-pass filter 75 is provided after the angle difference calculation unit 74, but instead, the low-pass filter 75 may be provided before the angle difference calculation unit 74.

[0067] The gain calculation unit 76 calculates the gain G3 of the low-pass filter 75 when the rotational speed of the motor 20 is speed ω, based on the rotational speed ω after filtering by the low-pass filter 75. For example, a moving average of four points is calculated using a delay element z. -n Using this, it is given by equation (9). H(z) = (1 + z -1 +z -2 +z -3 ) / 4 …(9) Applying the inverse z-transform using a bilinear transform yields equation (10).

number

[0068] Next, to find the gain characteristics, we substitute jω into the Laplace operator s in equation (10), and obtain equation (11) (where j is the imaginary unit).

number

[0069] By calculating the square root of the sum of the squares of the real and imaginary parts of equation (11) above and determining the gain characteristics, we obtain equation (12).

number

[0070] The above equation (12) involves a square root operation, which may increase the processing load. Therefore, we use the approximation equation (1+a). n By using ≈ 1 + na, the above equation (12) can be approximated as follows: (13).

number

[0071] The amplitude correction unit 77 corrects the sine signal SIN0, cosine signal COS0, sum (COS1+SIN1), and difference (COS1-SIN1), which have been filtered by the low-pass filters 70, 71, 72, and 73, by dividing them by the gain |G(ω)|. The peak hold section 78 obtains the peak values ​​(maximum and minimum values) of the sine signal SIN0, cosine signal COS0, sum (COS1+SIN1), and difference (COS1-SIN1) after they have been filtered by low-pass filters 70, 71, 72, and 73 and corrected by gain |G(ω)|.

[0072] The correction amount calculation unit 80 calculates correction amount data G1, Cs, Cc, and G2 based on the peak values ​​acquired by the peak hold unit 78. Furthermore, the correction amount calculation unit 80 may be equipped with a rate limiter to limit the rate of change of the correction amount data G1, Cs, Cc, and G2 in order to suppress rapid fluctuations in the sum signal SA and difference signal SD output from the detection signal correction unit 30. In other words, the correction amount calculation unit 80 may gradually change the correction amount data G1, Cs, Cc, and G2.

[0073] The execution determination unit 79 determines whether or not to perform correction of the sine signal SIN0 and cosine signal COS0 by the detection signal correction unit 30, depending on whether or not the rotation speed ω is within a predetermined threshold range. For example, if the correction amount data G1, Cs, Cc, and G2 are set when the rotation speed ω is low (including when stopped), it will take a long time to detect the peaks of the maximum and minimum values, resulting in errors due to temperature changes during that time. For this reason, the execution determination unit 79 may prohibit the correction by the detection signal correction unit 30 when the rotation speed ω is below the lower limit. For example, the lower limit may be set based on the rate of temperature rise of the circuit and the temperature-error (offset, gain, phase) characteristics.

[0074] Furthermore, for example, when the rotation speed ω is high, the error in peak detection during sampling is large. For this reason, the execution decision unit 79 may prohibit correction by the detection signal correction unit 30 when the rotation speed ω exceeds the upper limit. For example, the upper and lower limits may be set by simulation based on the allowable angle error and sampling period. If the execution determination unit 79 prohibits correction by the detection signal correction unit 30, the peak hold unit 78 resets the stored peak value (i.e., the peak hold value). In addition, the correction amount calculation unit 80 resets the values ​​of the first gain and the second gain to "1", and resets the values ​​of the sine offset correction value and the cosine offset correction value to "0". As a result, the sine signal SIN0 and the cosine signal COS0 are no longer corrected.

[0075] Figure 16 is a flowchart of an example of processing performed by the correction amount setting unit 36. In step S10, the angle difference calculation unit 74 calculates the rotational speed ω of the motor 20. In step S11, the execution determination unit 79 determines whether the rotation speed ω is within a predetermined threshold range. If the rotation speed ω is within a predetermined threshold range (step S11:Y), the execution decision unit 79 decides to perform correction by the detection signal correction unit 30, and the process proceeds to step S13. If the rotation speed ω is not within a predetermined threshold range (step S11:N), the execution decision unit 79 decides to prohibit correction by the detection signal correction unit 30, and the process proceeds to step S12.

[0076] In step S12, the peak hold unit 78 resets the stored peak value (i.e., the peak hold value). The correction amount calculation unit 80 also resets the values ​​of the first gain G1 and the second gain G2 to "1", and resets the values ​​of the sine offset correction value Cs and the cosine offset correction value Cc to "0". After that, the process returns to step S10. In step S13, the peak hold unit 78 filters the signal using a low-pass filter, and then performs peak hold on the sine signal SIN0, cosine signal COS0, sum (COS1+SIN1), and difference (COS1-SIN1) after dividing by the gain of the low-pass filter, updating the peak hold value.

[0077] In step S14, the correction amount calculation unit 80 determines whether the sine signal SIN0 and cosine signal COS0 for one rotation of the motor 20's electrical angle have been input to the correction amount setting unit 36. If the signal for one rotation has been input (step S14:Y), the process proceeds to step S15. If the signal for one rotation has not yet been input (step S14:N), the process returns to step S10. In step S15, the correction amount calculation unit 80 calculates correction amount data G1, Cs, Cc, and G2 based on the peak values ​​stored in the peak hold unit 78. The peak hold unit 78 also resets the stored peak hold values. After that, the process ends.

[0078] Figure 17 is an explanatory diagram of the simulation results of the correction of the sine signal SIN0 by the low-pass filter 70 and the amplitude correction unit 77. The dashed line shows the amplitude value of the sine signal SIN0 after filtering, when the amplitude of the sine signal SIN0 before filtering by the low-pass filter 70 is set to "1", and the solid line shows the amplitude value after correction by the amplitude correction unit 77. As shown in Figure 17, it can be seen that the amplitude value before filtering by the low-pass filter 70 is maintained by the correction performed by the amplitude correction unit 77.

[0079] (Effects of the embodiment) (1) The rotation angle detection device of the embodiment comprises a magnet 24 fixed to the rotation shaft 21 of the motor 20, a magnetic sensor 19 that detects the direction of the magnetic field generated from the magnet 24, a rotation angle calculation unit 31 that calculates the rotation angle of the rotation shaft 21 based on the detection signal of the magnetic sensor 19, and a rotation angle correction unit 32 that calculates the current magnetic field generated at the position of the magnetic sensor by at least one of the power supply current and the multiphase current of a power converter that outputs a multiphase current to the motor 20, calculates an angle correction amount based on the ratio of the magnitude of the current magnetic field to the magnitude of the magnetic field and the angle difference which is the difference between the direction of the magnetic field and the direction of the current magnetic field, and corrects the rotation angle based on the angle correction amount. This makes it possible to suppress the influence of the power supply current or the magnetic field caused by the multiphase current of the power converter that outputs multiphase current to the motor 20 on the detection accuracy when the rotation angle of the rotation shaft 21 of the motor 20 is detected by the magnetic sensor 19.

[0080] (2) The rotation angle correction unit 32 may calculate the angle correction amount as the product of the ratio of the magnitude of the current magnetic field to the magnitude of the magnetic field and the trigonometric function of the angle difference. This allows for the accurate calculation of the angle correction amount. The rotation angle correction unit 32 may calculate the direction of the magnetic field from the rotation angle calculated by the rotation angle calculation unit 31. This allows the direction of the magnetic field to be calculated. (3) The system may further include a temperature sensor 15 for measuring the temperature near the magnet 24 or a temperature estimation unit for estimating the temperature near the magnet 24. The rotation angle correction unit 32 may calculate the magnitude of the magnetic field of the magnet according to the temperature measured by the temperature sensor 15 or the temperature estimated by the temperature estimation unit. This allows the magnetic field of the magnet 24 to be calculated according to its temperature characteristics.

[0081] (4) The rotation angle detection device of the embodiment also includes a magnetic sensor 19 that outputs a sensor signal including a sine signal and a cosine signal in accordance with the rotation of a rotating body such as the rotation shaft 21 of a motor 20; low-pass filters 70 to 73 to which the sensor signal output from the magnetic sensor 19 is input; a peak hold unit 78 that acquires the peak value of the sensor signal that has been filtered by the low-pass filters 70 to 73 and corrected by the gain of the low-pass filters 70 to 73; a correction amount calculation unit 80 that calculates a correction amount for correcting the sensor signal according to the acquired peak value; a detection signal correction unit 30 that corrects the sensor signal output from the sensor based on this correction amount; and a rotation angle calculation unit 31 that calculates the rotation angle of the rotating body based on the sensor signal corrected by the detection signal correction unit 30. This allows for the removal of noise contained in the sensor signal while maintaining its amplitude, enabling the calculation of the correction amount based on accurate peak values.

[0082] (5) The gain calculation unit 76 may calculate the gains of the low-pass filters 70 to 73 based on the amount of time change of the rotation angle θ0. This allows the gain to be calculated according to the frequency characteristics of the low-pass filters 70-73. (6) An implementation determination unit 79 may be provided that determines not to perform correction of the sensor signal based on the correction amount if the amount of change in the rotation angle over time is outside a predetermined threshold range. This prevents errors caused by temperature changes during the long time it takes to detect the peaks of the maximum and minimum values ​​when setting the correction amount at low rotation speeds (including when stopped). It also prevents errors in peak detection during sampling at high rotation speeds.

[0083] (7) The correction amount calculation unit 80 may limit the rate at which the correction amount changes according to the peak value. This makes it possible to suppress sudden changes in the sensor signal after it has been corrected by the detection signal correction unit 30. (8) The detection signal correction unit 30 may correct at least one of the offset error, amplitude error, and phase error of the sensor signal based on the correction amount. This allows for correction of errors that affect the first and second-order components of the linearity error of the rotation angle calculated based on the sine and cosine signals, respectively. [Explanation of Symbols]

[0084] 1...Steering wheel, 2...Column shaft, 3...Reduction gear, 4a, 4b...Universal joint, 5...Pinion rack mechanism, 5a...Pinion, 5b...Rack, 6a, 6b...Tie rod, 7a, 7b...Hub unit, 8L, 8R...Steering wheels, 9...Torque sensor, 10...Control device, 11...Battery, 12...Ignition key, 13...Control board, 13a...Processor, 13b...Memory device, 14...Power board, 15...Temperature sensor, 16...Drive circuit, 17, 18...Current sensor, 19...Magnetic sensor, 20...Motor, 21...Rotation shaft, 24...Magnet, 30...Detection signal correction unit, 31...Rotation angle calculation unit, 32...Rotation angle 33... Angle correction unit, 34... Linearity correction unit, 35... Origin correction unit, 36... Motor control unit, 40... Correction amount setting unit, 41... SIN offset correction unit, 42... COS offset correction unit, 43... Adder, 44, 63, 64... Subtractor, 45... Phase error correction unit, 60... Differentiator, 61... Current command value calculation unit, 62... 3-phase / 2-phase conversion unit, 65, 66... ​​PI control unit, 67... 2-phase / 3-phase conversion unit, 68... PWM control unit, 70, 71, 72, 73, 75... Low-pass filter, 74... Angle difference calculation unit, 76... Gain calculation unit, 77... Amplitude correction unit, 78... Peak hold unit, 79... Execution decision unit, 80... Correction amount calculation unit

Claims

1. A sensor that outputs a sensor signal including a sine signal and a cosine signal in response to the rotation of a rotating body, A low-pass filter to which the sensor signal output from the aforementioned sensor is input, A peak value acquisition unit that acquires the peak value of the sensor signal that has been filtered by the low-pass filter and corrected with a gain correction value based on the gain of the low-pass filter, A correction amount calculation unit that calculates a correction amount for correcting the sensor signal according to the peak value, A correction unit that corrects the sensor signal output from the sensor based on the correction amount, A rotation angle calculation unit calculates the rotation angle of the rotating body based on the sensor signal corrected by the correction unit, Equipped with, The peak value acquisition unit includes a gain calculation unit that calculates the gain correction value based on the time change amount of the calculated rotation angle, A rotation angle detection device characterized in that, when the amount of change of the rotation angle over time exceeds a predetermined upper limit, no correction of the sensor signal based on the correction amount is performed.

2. The rotation angle detection device according to claim 1, characterized in that the correction amount calculation unit limits the rate of change of the correction amount according to the peak value.

3. The rotation angle detection device according to claim 1 or 2, characterized in that the correction unit corrects at least one of the offset error, amplitude error, and phase error of the sensor signal based on the correction amount.

4. A rotation angle detection device according to any one of claims 1 to 3, which detects the rotation angle of the motor's rotating shaft as the rotating body, A drive unit that drives the motor based on the rotation angle calculated by the rotation angle calculation unit, A motor control device characterized by comprising:

5. The motor control device according to claim 4, A motor controlled by the motor control device, An electric actuator product characterized by having the following features.

6. The motor control device according to claim 4, A motor controlled by the motor control device, An electric power steering system comprising a motor that provides steering assistance to the vehicle's steering system.

7. A rotation angle detection method for detecting the rotation angle of a rotating body based on a sensor signal that includes a sine signal and a cosine signal output from a sensor in response to the rotation of the rotating body, The sensor signal output from the sensor is subjected to filtering by a low-pass filter. The peak value of the sensor signal, which has been filtered by the low-pass filter and corrected with a gain correction value based on the gain of the low-pass filter, is obtained. The sensor signal output from the sensor is corrected based on a correction amount corresponding to the peak value. Based on the corrected sensor signal, the rotation angle of the rotating body is calculated. The gain correction value is calculated based on the time change amount of the calculated rotation angle. A rotation angle detection method characterized in that, if the amount of change of the rotation angle over time exceeds a predetermined upper limit, the sensor signal is not corrected based on the correction amount.

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