WO2016031674A1

WO2016031674A1 - Error correction device, rotational-angle detection device, rotational-angle sensor, error correction method, and program

Info

Publication number: WO2016031674A1
Application number: PCT/JP2015/073402
Authority: WO
Inventors: 茂樹岡武; 片岡　誠; 準也田島
Original assignee: 旭化成エレクトロニクス株式会社
Priority date: 2014-08-26
Filing date: 2015-08-20
Publication date: 2016-03-03

Abstract

This invention, which detects and corrects nonlinear error in the angle outputted by an active rotational-angle sensor, provides an error correction device, an error correction method, and a program. The error correction device is provided with the following: an acquisition unit that acquires the amplitude signal from a signal detection device that outputs an amplitude signal and an angle signal for a rotating body in accordance with detection signals from a magnetic-field detection unit that detects a magnetic field along a first axis and a magnetic field along a second axis; a correlation-signal computation unit that computes a correlation signal between a predetermined periodic function corresponding to an error mode of the magnetic-field detection unit and a measurement-target signal based on the aforementioned amplitude signal; and a correction unit that corrects the detection signal corresponding to the aforementioned error mode on the basis of the aforementioned correlation signal.

Description

Error correction device, rotation angle detection device, rotation angle sensor, error correction method, and program

The present invention relates to an error correction device, a rotation angle detection device, a rotation angle sensor, an error correction method, and a program.

Conventionally, a non-contact rotation angle sensor that detects a change in a magnetic field in the X direction and the Y direction and detects a rotation position of a rotating magnet or the like based on the detection result has been known. Since such a rotation angle sensor has an angle nonlinearity error, adjustment and calibration of the error have been performed (see, for example, Patent Documents 1 to 9).
Patent Document 1 JP 2002-71381 A Patent Document 2 JP 2011-158488 A Patent Document 3 US Patent Application Publication No. 2006/0290545 Patent Document 4 JP 9-196699 A Patent Document 5 JP 2010 No. -217151 Patent Document 6 JP 2010-164449 A Patent Document 7 US Pat. No. 6,426,712 Patent Document 8 JP 2010-217150 JP Patent Document 9 JP 2012-181188 Patent Document 10 US Patent No. No. 6288533 Non-Patent Document 1 RS Popovic, “Hall Effect Devices”, Inst of Physics Pub Inc, May 1991 Non-Patent Document 2 Bilotti et al., “Monolithic Magnetic Hall Sensor Using Dynamic Quadrature Offset Cancellation”, IEEE Journal of Solid-State Circuits, Vol.32, No.6, 1997, P. 829-836
Non-Patent Literature 3 by Udo Ausserlechner, “Limits of offset cancellation by the principle of spinning current Hall probe”, Proceedings of IEEE Sensors 2004, Vol. 3, P. 1117-1120
Non-patent document 4 Shin Ichimatsu, “Numerical calculation of elementary functions”, Education Publishing, January 1974 Non-patent document 5 Gert van der Horn, Johan L. Huijsing, “Integrated Smart Sensors, Design and Calibration”, Springer, December 1997

However, since the angle non-linearity error fluctuates according to a change in temperature, etc., even if the sensor is adjusted at the shipping stage, an error may occur according to a change in the ambient temperature or the like if the sensor continues to operate. . In addition, in the rotation angle sensor, a package stress variation or the like due to aging of the package resin occurs, and the angle nonlinearity error may vary. The rotation angle sensor is difficult to detect such a variation in angular nonlinearity error after being mounted on a system or the like, and it has been desired to maintain the angular nonlinearity error while being reduced.

In the first aspect of the present invention, the signal detection device outputs the angle signal and the amplitude signal of the rotating body in accordance with the detection signal of the magnetic field detection unit that detects the magnetic field of the first axis and the magnetic field of the second axis. A correlation signal calculation unit that calculates a correlation signal between a signal to be measured based on the amplitude signal, a predetermined periodic function corresponding to the error mode of the magnetic field detection unit, and a correlation signal An error correction apparatus, an error correction method, and a program are provided that include a correction unit that corrects a detection signal corresponding to an error mode.

In the second aspect of the present invention, the angle of the rotating body is determined according to the detection signal of the error correction device of the first aspect and the magnetic field detection unit that detects the magnetic field of the first axis and the magnetic field of the second axis. There is provided a rotation angle detection device including a signal detection device that outputs a signal and an amplitude signal.

In the third aspect of the present invention, the rotation angle detection device of the second aspect is provided, and the angle signal and the amplitude signal of the rotator according to the detection results of the magnetic field of the first axis and the magnetic field of the second axis. A rotation angle sensor is provided.

(General disclosure)
(Item 1)
The error correction device acquires the output of the signal detection device that outputs the angle signal and the amplitude signal of the rotating body according to the detection signal of the magnetic field detection unit that detects the magnetic field of the first axis and the magnetic field of the second axis. An acquisition unit may be provided.
The error correction apparatus may include a correlation signal calculation unit that calculates a correlation signal between a predetermined periodic function corresponding to the error mode of the magnetic field detection unit and a signal under measurement based on the amplitude signal.
The error correction device may include a correction unit that corrects the detection signal corresponding to the error mode based on the correlation signal.
(Item 2)
The correction unit may correct the detection signal acquired by the acquisition unit, and the corrected detection signal may be supplied to the signal detection device.
(Item 3)
The error mode may include a first mode in which the magnetic field detection unit includes an offset component of a signal corresponding to the first axial direction.
The error mode may include a second mode in which the magnetic field detection unit includes an offset component of a signal corresponding to the second axial direction.
The error mode may include a third mode in which the magnetic field detection unit includes a magnetic sensitivity mismatch between the signal corresponding to the first axis and the signal corresponding to the second axis.
The error mode may include a fourth mode in which the magnetic field detection unit includes a non-orthogonal error between a signal corresponding to the first axis and a signal corresponding to the second axis.
(Item 4)
When the error mode is the first mode, the correlation signal calculation unit may calculate a correlation signal with the signal under measurement using the periodic function as a cosine of 1 × square.
When the error mode is the second mode, the correlation signal calculation unit may calculate a correlation signal with the signal under measurement using the periodic function as a sine of a single angle.
When the error mode is the third mode, the correlation signal calculation unit may calculate a correlation signal with the signal under measurement using the double function cosine as a periodic function.
When the error mode is the fourth mode, the correlation signal calculation unit may calculate a correlation signal with the signal under measurement using the periodic function as a sine of a double angle.
(Item 5)
The correlation signal calculation unit may calculate the Nth power signal of the amplitude signal (N is a natural number of 1 or more) as the signal under measurement.
(Item 6)
The acquisition unit may acquire the output of the non-contact rotation angle sensor.
(Item 7)
The rotation angle detection device may include an error correction device.
The rotation angle detection device may include a signal detection device that outputs an angle signal and an amplitude signal of the rotating body according to detection signals of a magnetic field detection unit that detects a magnetic field of the first axis and a magnetic field of the second axis. .
(Item 8)
The signal detection apparatus may include a first AD conversion unit that converts a detection result of the magnetic field of the first axis into a digital signal.
The signal detection apparatus may include a second AD conversion unit that converts a detection result of the magnetic field of the second axis into a digital signal.
The correction unit may supply a correction signal for correcting the detection signal to the first AD conversion unit and the second AD conversion unit, respectively.
(Item 9)
The first AD conversion unit may output a first 1-bit ΔΣ signal corresponding to the detection result of the magnetic field of the first axis.
The second AD conversion unit may output a second 1-bit ΔΣ signal corresponding to the detection result of the magnetic field of the second axis.
The signal detection device may include a servo loop that calculates an angle signal based on the first and second 1-bit ΔΣ signals.
(Item 10)
The signal detection device may be a CORDIC.
(Item 11)
The rotation angle sensor may include a rotation angle detection device.
The rotation angle sensor may output an angle signal and an amplitude signal of the rotating body according to the detection results of the magnetic field of the first axis and the magnetic field of the second axis.
(Item 12)
An error correction method for a detection signal of a magnetic field detection unit that detects a magnetic field of a first axis and a magnetic field of a second axis that change according to the rotation of the rotating body is calculated according to the detection signal. An angle signal and an amplitude signal may be acquired.
The error correction method may calculate a correlation signal between a predetermined periodic function corresponding to the error mode of the magnetic field detection unit and a signal under measurement based on the amplitude signal.
In the error correction method, the detection signal corresponding to the error mode may be corrected based on the correlation signal.
It should be noted that the above summary of the invention does not enumerate all the necessary features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

The structural example of the magnetic field detection part 100 which concerns on this embodiment is shown. An example in which the first Hall element pair 110 according to the present embodiment detects a magnetic field in the first direction is shown. The structural example of the signal detection apparatus 200 which concerns on this embodiment is shown. The structural example of the error correction apparatus 300 which concerns on this embodiment is shown with the magnetic field detection part 100 and the signal detection apparatus 200. FIG. The operation | movement flow of the error correction apparatus 300 which concerns on this embodiment is shown. An example of the calculation circuit which the correlation signal calculation part 330 which concerns on this embodiment has is shown. An example of Hall electromotive force signals (V _X , V _Y ) is shown. An example of the amplitude of the Hall electromotive force signal (V _X , V _Y ) is shown. An example of the angle nonlinearity error of the Hall electromotive force signal (V _X , V _Y ) is shown. An example of Hall electromotive force signals (V _X , V _Y ) is shown. An example of the amplitude of the Hall electromotive force signal (V _X , V _Y ) is shown. An example of the angle nonlinearity error of the Hall electromotive force signal (V _X , V _Y ) is shown. The modification of the error correction apparatus 300 which concerns on this embodiment is shown. An example of the rotation angle sensor module 400 concerning this embodiment is shown. An example of an assembly error in which a center axis shift has occurred in the rotation angle sensor module 400 according to the present embodiment is shown. An example of an assembly error in which eccentricity has occurred in the rotation angle sensor module 400 according to the present embodiment is shown. An example of an assembly error in which the rotation magnet 410 is inclined in the rotation angle sensor module 400 according to the present embodiment is shown. The example which applied the magnetic field of 8 directions to the magnetic field detection part 100 of the ideal rotation angle sensor module 400 is shown, respectively. The example which applied the magnetic field of 8 directions to the magnetic field detection part 100 of the rotation angle sensor module 400 which has an assembly error of a center axis | shaft deviation is shown, respectively. An example of magnetic field detection signals (V _X (θ), V _Y (θ)) when a center axis shift occurs between the rotating magnet 410 and the magnetic field detection unit 100 is shown. An example of an amplitude signal A (θ) when a center axis deviation occurs between the rotating magnet 410 and the magnetic field detection unit 100 is shown. An example of an angle nonlinearity error (φ (θ) −θ) when a center axis deviation occurs between the rotating magnet 410 and the magnetic field detection unit 100 is shown. An example of the result of correcting the angle nonlinearity error when the center axis deviation occurs is shown. An example of a hardware configuration of a computer 1900 functioning as the error correction apparatus 300 according to the present embodiment is shown.

Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

FIG. 1 shows a configuration example of a magnetic field detection unit 100 according to the present embodiment. For example, the magnetic field detection unit 100 detects the rotation angle of a rotating magnet that rotates around the rotation axis in the vicinity of the sensor in a non-contact manner. The magnetic field detection unit 100 includes a substrate 10, a first Hall element pair 110, a second Hall element pair 120, and a magnetic convergence plate 130.

The substrate 10 is formed of a semiconductor such as silicon and includes a semiconductor circuit and a semiconductor element. The substrate 10 may be an IC chip. In this case, the substrate 10 includes a terminal and is electrically connected to an external substrate, circuit, wiring, and the like. In FIG. 1, one surface of the substrate 10 is an XY plane having an X axis and a Y axis, and an axis perpendicular to the XY plane is a Z axis. That is, the X, Y, and Z axes are coordinate systems orthogonal to each other.

The first Hall element pair 110 is formed on the substrate 10 and connected to a circuit or the like formed on the substrate 10. As an example, the first Hall element pair 110 is arranged in the first direction. Here, the first direction in the present embodiment is the X-axis direction (first axis) in FIG. The first Hall element pair 110 includes a first Hall element 112 and a second Hall element 114, and the two Hall elements are arranged in parallel to the X axis (for example, on the X axis).

As an example, the first Hall element 112 and the second Hall element 114 are elements that generate an electromotive force (Hall effect) in the Y-axis direction corresponding to a magnetic field input in the Z-axis direction when a current flows in the X-axis direction. . The first hall element 112 and the second hall element 114 may be formed of a semiconductor or the like.

As an example, the first Hall element 112 and the second Hall element 114 are arranged in line symmetry with respect to the Y axis on the substrate 10. Alternatively, the first Hall element 112 and the second Hall element 114 may be arranged point-symmetrically with respect to the origin on the substrate 10. In the present embodiment, an example in which the first Hall element 112 and the second Hall element 114 are arranged symmetrically with respect to the Y axis will be described.

As with the first Hall element pair 110, the second Hall element pair 120 is formed on the substrate 10 and connected to a circuit or the like formed on the substrate 10. For example, the second Hall element pair 120 is arranged in the second direction. Here, the second direction in the present embodiment is the Y-axis direction (second axis) in FIG. The third direction is the Z-axis direction (third axis) in FIG. The second Hall element pair 120 includes a third Hall element 122 and a fourth Hall element 124, and the two Hall elements are arranged in parallel to the Y axis (for example, on the Y axis).

As an example, the third Hall element 122 and the fourth Hall element 124 are elements that generate an electromotive force (Hall effect) in the X-axis direction corresponding to a magnetic field input in the Z-axis direction when a current flows in the Y-axis direction. . As an example, the third Hall element 122 and the fourth Hall element 124 are arranged symmetrically with respect to the X axis on the substrate 10. Alternatively, the third Hall element 122 and the fourth Hall element 124 may be arranged point-symmetrically with respect to the origin on the substrate 10. In the present embodiment, an example in which the third Hall element 122 and the fourth Hall element 124 are arranged symmetrically with respect to the X axis will be described.

The first Hall element pair 110 and the second Hall element pair 120 described above may be alternately energized in the X-axis direction and in the Y-axis direction in order to cancel the offset output. Such an offset canceling method is known as the Spinning Current method as described in Non-Patent Document 5.

The magnetic convergence plate 130 is disposed above the first Hall element pair 110 and the second Hall element pair 120 and bends the magnetic field input to the magnetic field detection unit 100. The magnetic converging plate 130 is formed of a magnetic material or the like, and for example, a first hole having a sensitivity in the Z-axis direction by bending a magnetic field in the X-axis direction and / or the Y-axis direction so as to generate a component in the Z-axis direction. Input is made to the element pair 110 and the second Hall element pair 120. The magnetic flux concentrating plate 130 may be formed on the upper surface of the substrate 10, or alternatively, may be formed above the substrate 10 via an insulating layer or the like.

The magnetic field detection unit 100 described above outputs output signals (Hall electromotive force) from the first Hall element pair 110 and the second Hall element pair 120 to the outside. Here, output signals from the first Hall element pair 110 and the second Hall element pair 120 are output according to the rotation angle of the rotating magnet. The output signal will be described with reference to FIG.

FIG. 2 shows an example when the first Hall element pair 110 according to the present embodiment detects a magnetic field in the first direction. In FIG. 2, the horizontal direction (the horizontal direction of the paper surface) is the X axis, and the vertical direction (the vertical direction of the paper surface) is the Z axis direction.

Here, the magnetic field vector H (H _X , H _Y , H _Z ) input to the magnetic field detection unit 100 is bent by the magnetic convergence plate 130 and input to the first Hall element 112, the magnetic flux density vector B (Hall, X 1). Is expressed by the following equation using the magnetic permeability Mu (Hall, X1) at the position of the first Hall element 112. Here, the magnetic permeability Mu (Hall, X1) is a second-order tensor (matrix with 3 rows and 3 columns).

Similarly, the magnetic flux density vector B (Hall, X2) input to the second Hall element 114 is expressed by the following equation using the magnetic permeability Mu (Hall, X2) at the position of the second Hall element 114.

The first hall element 112 and the second hall element 114 detect a magnetic field in the Z-axis direction. Therefore, the first Hall element 112 and the second Hall element 114, as shown in the following equation, thereby to detect the magnetic flux density B _Z of the Z-axis direction that is bent by the magnetic flux concentrator 130.

Here, as shown in FIG. 2, an example in which a magnetic field vector H _in (H _X , 0, 0) _{in the} + X axis direction is input above the magnetic field detection unit 100 will be described. As an example, the magnetic converging plate 130 bends the input magnetic field as shown by a magnetic flux density vector B in the drawing, and causes the first Hall element 112 to input a magnetic flux in the + Z-axis direction.

Further, since the magnetic permeability of the magnetic flux concentrating plate 130 made of a magnetic material or the like is higher than the magnetic permeability of air, the magnetic flux in the magnetic converging plate 130 is compared with the magnetic flux density in the air. Density increases. For example, the magnetic flux density in the Z-axis direction at the position of the first Hall element 112 is approximately 1. as compared with the magnetic flux density obtained by multiplying the input magnetic field _HZ by the air permeability μ, as shown by the following equation. About 4 times higher.

Similarly, as an example, the magnetic flux concentrating plate 130 causes the second Hall element 114 to generate a magnetic flux in the −Z-axis direction, and the magnetic flux density in the Z-axis direction at the position of the second Hall element 114 is expressed by the following equation.

The first Hall element 112 and the second Hall element 114 generate Hall electromotive force according to the magnetic flux density input in the Z-axis direction as described above. Here, when the 1st Hall element 112 and the 2nd Hall element 114 are formed with substantially the same shape and the substantially same material, each magnetic sensitivity becomes substantially equal. Further, since the magnetic flux densities input to the first Hall element 112 and the second Hall element 114 are opposite to each other, the generated hall electromotive forces have different signs.

Therefore, when the magnetic sensitivity is S, the Hall electromotive force signal V _X of the first Hall element pair 110 is converted into the Hall electromotive force V _sig (Hall, X1) of the first Hall element 112 and the Hall electromotive force of the second Hall element 114. It can be defined as the following equation, which is the difference between the power V _sig (Hall, X2).

Thus, the magnetic field detection unit 100 outputs the Hall electromotive force according to the magnetic field vector H _in (H _X , 0, 0) input in the X-axis direction by calculating the Hall electromotive force signal V _X. be able to. Further, since the Hall electromotive force signal V _X is the difference between the Hall electromotive forces of the Hall elements, the first Hall element 112 and the second Hall element 114 are in the same direction (+ Z-axis direction or −Z-axis direction), and The Hall electromotive force generated by the magnetic field having substantially the same absolute value is canceled out and becomes substantially zero.

That is, the magnetic field detection unit 100 calculates the Hall electromotive force signal V _X , so that the magnetic field vector H _XZ (H _X , 0, H _Z ) in the direction parallel to the XZ plane is input. The Hall electromotive force corresponding to the magnetic field vector component H _X (H _X , 0, 0) can be calculated. The first Hall element 112 and the second Hall element 114 are insensitive to the magnetic field in the Y-axis direction, and the magnetic focusing plate 130 ideally converts the magnetic field in the Y-axis direction into the Z-axis direction. do not do. Therefore, the magnetic field detection unit 100 calculates the Hall electromotive force signal V _X so that the three orthogonal components are not zero (arbitrary direction) magnetic field vector H _XYZ (H _X , H _Y , H _Z ). Is input, it is possible to detect the Hall electromotive force according to the component H _X (H _X , 0, 0) of the magnetic field vector in the X-axis direction.

Similarly, the second Hall element pair 120 arranged in the Y-axis direction can calculate the magnetic field in the Y-axis direction. That is, the magnetic field detection unit 100 uses the second Hall element pair 120 to calculate a Hall electromotive force signal V _Y of the following expression, thereby inputting a magnetic field vector H _XYZ (H _X , H _Y , H _Z ). However, it is possible to calculate the Hall electromotive force according to the component H _Y (0, H _Y , 0) of the magnetic field vector in the Y-axis direction.

Similarly, the first Hall element 112 and the second Hall element 114 generate Hall electromotive force according to the magnetic flux density input in the Z-axis direction. Then, the Hall electromotive force signal _{V Z} of the first hall element pair 110, Hall electromotive force _V sig of the first Hall element 112 (Hall, X1) and Hall electromotive force _V sig of the second Hall element 114 (Hall, X2) May be calculated as the sum of. The magnetic field detection unit 100 of the present embodiment will describe an example in which the Hall electromotive force signals V _X and V _Y are output, and the Hall electromotive force signal V _Z will be omitted. for even V _Z, it may be output like the Hall electromotive force signal _{V X} and _{V Y.}

As described above, the magnetic field detection unit 100 is based on the output signals of the first Hall element pair 110 and the second Hall element pair 120, and the X-axis component of the input magnetic field vector H _XYZ (H _X , H _Y , H _Z ). Hall electromotive force signals V _X and V _Y corresponding to H _X (H _X , 0,0) and Y axis component H _Y (0, H _Y , 0) are output. That is, the magnetic field detection unit 100 can calculate the Hall electromotive force corresponding to the magnetic field in the direction parallel to the XY plane by decomposing the Hall electromotive force into an X-axis component and a Y-axis component.

For example, the magnetic field detection unit 100 can detect a magnetic field caused by rotation of a rotating magnet whose rotation axis is parallel to the Z axis in a plane parallel to the XY plane, and output a Hall electromotive force signal corresponding to the rotation angle. it can. Here, as an example, the magnetic field detection unit 100 outputs a Hall electromotive force signal (V _X , V _Y ) represented by the following equation. Here, A _x and A _y are amplitude values of each signal, θ is a rotation angle of the rotating magnet, α is a non-orthogonality error between signals, and V _{os_x} and V _{os_y} are offsets of each signal.
(Equation 8)
V _X (θ) = A _x · cos (θ) + V _os — _x
V _Y (θ) = A _y · sin (θ + α) + V _{os_y}

Using the Hall electromotive force signals (V _X , V _Y ) as described above, an angle signal φ (θ) corresponding to the rotation angle θ of the rotating magnet can be calculated by the following equation as an example.
(Equation 9)
φ (θ) = tan ⁻¹ {V _Y (θ) / V _X (θ)}

Here, although it has been described that the magnetic field detection unit 100 detects a magnetic field in a plane parallel to the XY plane, a change in the magnetic field in another plane may be detected. The magnetic field detection unit 100 can also detect a magnetic field in the Z-axis direction. For example, the magnetic field detection unit 100 detects a magnetic field caused by rotation of a rotating magnet whose rotation axis is parallel to the Y-axis in a plane parallel to the XZ plane. A Hall electromotive force signal corresponding to the angle θ can be output. Similarly, the magnetic field detection unit 100 detects a magnetic field caused by rotation of a rotating magnet whose rotation axis is parallel to the X axis in a plane parallel to the YZ plane, and outputs a Hall electromotive force signal corresponding to the rotation angle θ. You can also

Further, since the magnetic field detection unit 100 can detect a three-dimensional magnetic field of the XYZ axes, it detects a magnetic field due to rotation in a plane that can be expressed by the XYZ axes, and outputs a Hall electromotive force signal corresponding to the rotation angle θ. can do. An example in which the magnetic field detection unit 100 according to the present embodiment outputs a Hall electromotive force signal expressed by Equation (8) will be described.

In the equation (8), for example, when V _{os_x} and V _{os_y} are approximately zero, α is approximately zero, and A _x is approximately equal to A _y , that is, an ideal Hall electromotive force signal (V _X , When V _Y ) is obtained, the angle signal φ (θ) in the equation (9) substantially coincides with the rotation angle θ. However, when the amplitude value difference (A _x −A _y ), non-orthogonality error α, and offsets V _{os_x} and V _{os_y} are not substantially zero, φ (θ) and θ do not match, and φ (θ) and θ (Φ (θ) −θ) is an angle nonlinearity error of the magnetic field detection unit 100.

FIG. 3 shows a configuration example of the signal detection apparatus 200 according to the present embodiment. The signal detection device 200 detects the angle signal φ (θ) of the magnetic field detection unit 100 by executing a closed loop process so as to reduce the angle error signal ε (= φ (θ) −θ). That is, the magnetic field detection unit 100 and the signal detection device 200 function as a rotation angle sensor that detects a magnetic field generated by rotation of a rotating magnet and outputs a rotation angle. Signal detection apparatus 200 includes a first pair of Hall effect devices 110 and the second Hall electromotive force signal from the Hall element pair 120 _{_(V} X, V _Y) receives the angle signal corresponding to the Hall electromotive force signal _{_(V} X, V _Y) Output φ (θ). Further, the signal detection device 200 outputs an amplitude signal A (φ) corresponding to the Hall electromotive force signal (V _X , V _Y ).

The signal detection apparatus 200 includes an amplification unit 210, an amplification unit 212, an AD conversion unit 220, an AD conversion unit 222, a multiplication unit 230, a multiplication unit 232, an accumulation unit 240, an accumulation unit 242, an accumulation unit 244, a phase compensation unit 250, and A storage unit 260 is provided. Amplifying unit 210 is connected to the first Hall element pair 110 receives the Hall electromotive force signal V _X, amplified by a predetermined amplification degree. The amplification unit 210 supplies the amplified Hall electromotive force signal V _X to the AD conversion unit 220. AD conversion unit 220 is connected to the amplifying section 210, converts the Hall electromotive force signal _{V X} received into a digital signal. The AD conversion unit 220 supplies the converted digital signal V _X to the multiplication unit 230.

Similarly, the amplifier 212 is connected to a second pair of Hall effect devices 120, receives Hall electromotive force signal V _Y, amplified by a predetermined amplification degree. The amplification unit 212 supplies the amplified Hall electromotive force signal _VY to the AD conversion unit 222. The AD conversion unit 222 is connected to the amplification unit 212 and converts the received Hall electromotive force signal _VY into a digital signal. The AD conversion unit 222 supplies the converted digital signal V _Y to the multiplication unit 230.

Multiplying unit 230 multiplies the sine wave signal sin (phi) into a digital signal _{V X.} Further, the multiplier 230 multiplies the digital signal _VY by the cosine wave signal cos (φ). The multiplier 230 outputs the difference between the two multiplication results as an angle error signal ε, as shown by the following equation. Here, the amplification degree of the amplification unit 210 and the amplification unit 212 is set to 1.
(Equation 10)
ε = -sin (φ) · V _X + cos (φ) · V _Y

When the Hall electromotive force signals (V _X , V _Y ) are ideal signals, the angle error signal ε is expressed as follows. Here, the amplitude signal A = A _x = A _y .
(Equation 11)
ε = −A · sin (φ) · cos (θ) + A · cos (φ) · sin (θ)
= A · sin (θ-φ)

The multiplication unit 230 supplies the calculated angle error signal ε to the integration unit 240. The integrating unit 240 is connected to the multiplying unit 230, integrates the received angle error signal ε, and supplies the integrated angle error signal ε to the phase compensating unit 250.

The phase compensation unit 250 is connected to the integration unit 240 and performs phase compensation so as to ensure the phase stability of the closed loop circuit. As an example, the signal detection device 200 shown in FIG. 3 is a so-called type 2 servo circuit including two integration units (time integration) in a closed loop circuit. Is an angular velocity signal that is a time derivative of the angle φ. The phase compensation unit 250 supplies the angular velocity signal to the integrating unit 242.

The accumulator 242 is connected to the phase compensator 250 and accumulates the received angular velocity signals to generate an angle signal φ. For example, the integration unit 242 may be a circuit configured by a DCO (Digitally Controlled Oscillator) circuit and an up-down counter that performs an up-count / down-count operation on an output signal of the DCO.

The storage unit 260 previously stores a sine wave signal sin (φ) and a cosine wave signal cos (φ) corresponding to a plurality of angle signals φ. The storage unit 260 is connected to the integration unit 242 and supplies the multiplication unit 230 with a sine wave signal sin (φ) and a cosine wave signal cos (φ) corresponding to the received angle signal φ. That is, the storage unit 260 feeds back the corresponding sine wave signal sin (φ) and cosine wave signal cos (φ) to the multiplication unit 230 in accordance with the acquired angle signal φ.

The signal detection apparatus 200 of the present embodiment described above causes the integrating unit 242 to output the angle signal φ that is closer to θ by a feedback loop that has passed from the multiplying unit 230 through the phase compensating unit 250 and the storage unit 260. Further, the signal detection device 200 outputs an amplitude signal A (φ) of the angle error signal ε based on the angle signal φ.

In this case, the AD conversion unit 220 supplies the digital signal V _X converted from the Hall electromotive force signal V _X to the multiplication unit 230 and also to the multiplication unit 232. Similarly, the AD conversion unit 222 supplies the digital signal V _Y converted from the Hall electromotive force signal V _Y to the multiplication unit 230 and also to the multiplication unit 232.

Multiplying unit 232 multiplies the cosine wave signal cos (phi) into a digital signal _{V X.} Further, the multiplier 232 multiplies the digital signal _VY by the sine wave signal sin (φ). The multiplication unit 232 outputs the sum of two multiplication results as an amplitude signal A (φ) via the integration unit 244, as shown by the following equation. Here, the amplification degree of the amplification unit 210 and the amplification unit 212 is set to 1.
(Equation 12)
A (φ) = cos (φ) · V _X + sin (φ) · V _Y

When the Hall electromotive force signals (V _X , V _Y ) are ideal signals and the angle signal φ is substantially equal to θ, the amplitude signal A (φ) is expressed as follows. Here, the amplitude signal A = A _x = A _y .
(Equation 13)
A (φ) = [A _x ² · {cos (φ)} ² + A _y ² · {sin (φ)} ² ] ^1/2 = A

As described above, the signal detection device 200 according to the present embodiment outputs the angle signal φ (θ) and the amplitude signal A (φ) according to the input Hall electromotive force signals (V _X , V _Y ). When the Hall electromotive force signals (V _X , V _Y ) are ideal signals, the signal detection device 200 can output an angle signal φ (θ) that is substantially the same as the rotation angle θ of the rotating magnet. In addition, when the Hall electromotive force signal (V _X , V _Y ) is deviated from the ideal, the signal detection device 200 outputs an angle signal φ (θ) different from the rotation angle θ (that is, the angle nonlinearity error). (Φ (θ) −θ) becomes non-zero).

Such angular non-linearity errors are due to mismatch in amplitude of the two Hall electromotive force signals (ie, mismatch in magnetic detection sensitivity of the first Hall element pair 110 and the second Hall element pair 120), non-orthogonality, and offset. to cause. Since these factors have temperature dependence, the angle nonlinearity error also varies according to the ambient temperature. Such temperature fluctuations of the angle non-linearity error can be measured at the manufacturing stage and the shipping stage of the magnetic field detection unit 100, so that it can be measured in advance before being mounted on a system or the like, and calibration and correction can be performed. preferable. However, for example, when the magnetic field detection unit 100 is deteriorated, the temperature fluctuation of such an angle nonlinearity error may exceed an error range required for a system or the like on which the magnetic field detection unit 100 is mounted. It may affect the operation.

Such deterioration of the magnetic field detection unit 100, change with time, and the like are difficult to predict at the manufacturing stage and the shipping stage, and therefore, even when the magnetic field detection unit 100 is mounted on the system or the like, the angle nonlinearity It is desirable to be able to detect and correct variations in sex errors. Therefore, the error correction apparatus according to the present embodiment detects an angular non-linearity error based on the detection result of the rotation angle sensor in which the magnetic field detection unit 100 is mounted in a system or the like, and a hole that is a detection signal of the magnetic field detection unit 100. Correct the electromotive force signal.

FIG. 4 shows a configuration example of the error correction apparatus 300 according to the present embodiment, together with the magnetic field detection unit 100 and the signal detection apparatus 200. The magnetic field detection unit 100 and the signal detection apparatus 200 have been described with reference to FIGS. The error correction device 300 detects an angle nonlinearity error based on the angle signal φ and the amplitude signal A (φ) output according to the Hall electromotive force signals (V _X , V _Y ), and Hall according to the detection result. The electromotive force signal (V _X , V _Y ) is corrected. The error correction apparatus 300 includes an acquisition unit 310, a storage unit 320, a correlation signal calculation unit 330, and a correction unit 340.

The acquisition unit 310 outputs an angle signal φ (θ) and an amplitude signal A (φ) of the rotating body according to the detection signal of the magnetic field detection unit 100 that detects the magnetic field of the first axis and the magnetic field of the second axis. The output of the signal detection device 200 is acquired. For example, the acquisition unit 310 is connected to the signal detection device 200 and acquires the angle signal φ and the amplitude signal A (φ). When the magnetic field detection unit 100 includes the signal detection device 200 described with reference to FIG. 3, the acquisition unit 310 may acquire the angle signal φ and the amplitude signal A (φ) from the magnetic field detection unit 100. Here, the acquisition unit 310 may acquire the output of the non-contact rotation angle sensor.

The acquisition unit 310 may be connected to the magnetic field detection unit 100, the signal detection device 200, or the like by wire, wireless, or a network, and may acquire the angle signal φ and the amplitude signal A (φ). The acquisition unit 310 may be connected to a storage device or the like, and may acquire an output of a rotation angle sensor stored in the storage device or the like. The acquisition unit 310 supplies the acquired angle signal φ and amplitude signal A (φ) to the correlation signal calculation unit 330. In addition, the acquisition unit 310 may supply the acquired angle signal φ and amplitude signal A (φ) to the storage unit 320.

The storage unit 320 stores a predetermined periodic function corresponding to the error mode of the magnetic field detection unit 100. The storage unit 320 stores a sine function and a cosine function as a periodic function. The periodic function will be described later. The storage unit 320 may store data or the like generated by the error correction device 300. The storage unit 320 may store intermediate data to be processed in the process of generating the data. In addition, the storage unit 320 may supply the stored data to the request source in response to a request from each unit in the error correction apparatus 300.

For example, when the storage unit 320 is connected to the acquisition unit 310 and receives the angle signal φ and the amplitude signal A (φ) from the acquisition unit 310, the storage unit 320 stores the angle signal φ and the amplitude signal A (φ). Then, the storage unit 320 supplies the angle signal φ and the amplitude signal A (φ) stored in response to the request from the correlation signal calculation unit 330 to the correlation signal calculation unit 330.

Correlation signal calculation section 330 is connected to acquisition section 310 and storage section 320, respectively, and a predetermined periodic function corresponding to the error mode of magnetic field detection section 100 and a signal under measurement based on amplitude signal A (φ). A correlation signal is calculated. The correlation signal calculation unit 330 applies the value of the angle signal φ acquired by the acquisition unit 310 to the periodic function, and calculates a correlation signal using the applied periodic function and the amplitude signal A (φ).

The correlation signal calculation unit 330 calculates the Nth power signal of the amplitude signal (N is a natural number of 1 or more) as the signal under measurement. For example, the correlation signal calculation unit 330 uses the amplitude signal A (φ) as a signal under measurement. Instead, the correlation signal calculation unit 330 may use the square of the amplitude signal A (φ) as the signal under measurement. The correlation signal calculation unit 330 supplies the calculated correlation function to the correction unit 340.

The correction unit 340 is connected to the correlation signal calculation unit 330 and corrects the detection signal corresponding to the error mode based on the received correlation signal. Since the correction unit 340 is connected to the signal detection device 200 and corrects the detection signal acquired by the acquisition unit 310, the corrected detection signal is supplied to the signal detection device 200. The detection signal corrected by the correction unit 340 includes a signal based on the detection signal, such as a detection signal output from the magnetic field detection unit 100, a signal obtained by amplifying the detection signal, and a signal obtained by converting the detection signal into a digital signal. Shall be included.

The correction unit 340 is connected to, for example, the AD conversion unit 220 and the AD conversion unit 222 of the signal detection device 200, respectively, and superimposes correction values on analog signals, threshold values, offsets, and the like when converted into digital signals. Instead, the correction unit 340 may be connected to the amplification unit 210 and the amplification unit 212, respectively, and change the amplification degree according to the correction value.

Instead, the correction unit 340 is connected to the input of the amplification unit 210 and the amplification unit 212 (that is, the input of the signal detection device 200), and corrects the analog signal of the Hall electromotive force signal (V _X , V _Y ). You may have a circuit part which superimposes a value. Instead, the correction unit 340 is connected between the amplification unit 210 and the AD conversion unit 220, and between the amplification unit 212 and the AD conversion unit 222, and analog of the Hall electromotive force signals (V _X , V _Y ). You may have a circuit part which superimposes a correction value on a signal.

Instead, the correction unit 340 is connected between the AD conversion unit 220 and the multiplication unit 230, and between the AD conversion unit 222 and the multiplication unit 230, and is digital of the Hall electromotive force signals (V _X , V _Y ). You may have a circuit part which superimposes a correction value on a signal. In this case, the Hall electromotive force signal (V _X , V _Y ) on which the correction value is superimposed may be connected to be input to the multiplier 230 and the multiplier 232. As described above, since the correction unit 340 corrects the Hall electromotive force signal (V _X , V _Y ), the signal detection device 200 uses the corrected detection signal to accurately detect the angle signal φ (θ) and the amplitude. Signal A (φ) can be output.

The operation of the error correction apparatus 300 according to this embodiment will be described with reference to FIG. FIG. 5 shows an operation flow of the error correction apparatus 300 according to the present embodiment. The error correction apparatus 300 executes the operation flow shown in FIG. 5, detects the angle nonlinearity error of the magnetic field detection unit 100, and corrects the detection signal of the magnetic field detection unit 100.

First, the acquisition unit 310 acquires the angle signal φ and the amplitude signal A (φ) (S400). For example, the acquisition unit 310 is connected to the integration unit 244 of the signal detection device 200 described with reference to FIG. 3 and acquires the amplitude signal A (φ) output from the integration unit 244. Here, the amplitude signal A (φ) acquired by the acquisition unit 310 can be approximated by the following equation.
(Equation 14)
A (φ) ≈A (θ) = {V _X (θ) ² + V _Y (θ) ² } ^1/2
= [{A _x · cos (θ) + V _{os —} _x } ²
+ {A _y · sin (θ + α) + V _{os — y} } ² ] ^1/2

Next, the error correction apparatus 300 detects an offset V _{os_x} of the X axis that is the first axis (S410). In this case, the correlation signal calculation unit 330 calculates a correlation signal between an amplitude signal and a predetermined periodic function corresponding to an error mode for detecting an X-axis offset.

Here, the error correction apparatus 300 sets the error mode as a first mode in which the magnetic field detection unit 100 includes an offset component of a signal corresponding to the first axial direction. In the magnetic field detector 100, when such an error in the first mode increases, the offset V _{os_x of the} X axis increases, so that the Hall electromotive force signal (V _X , V _Y ) in Equation (8) is It can be handled as follows: Here, A _avg was an average value of A _x and A _y .
(Equation 15)
V _X (θ) = A _avg · cos (θ) + V _{os — x}
V _Y (θ) = A _avg · sin (θ)

Therefore, the amplitude signal A (θ) in the equation (14) is calculated as the following equation. Here, C _X represents a constant.
(Equation 16)
A (θ) = {V _X (θ) ² + V _Y (θ) ² } ^1/2
= {A _avg ² + V _{os — x} ² + 2 · A _avg · V _os — _x · cos (θ)} ^1/2
≒ C _X + V _{os_x} · cos (θ)

As described above, the amplitude signal A (θ) has a component that varies like a cosine function in accordance with the rotation angle θ. Therefore, by taking a correlation with the cosine function cos (θ), the offset V _{os_x} of the X axis is _obtained. It is possible to detect a signal corresponding to. That is, when the error mode is the first mode, the correlation signal calculation unit 330 calculates a correlation signal with the signal under measurement using the periodic function as a cosine of 1 × square.

More specifically, the rotation angle θ is a 360 ° (2π) cycle, and when the correlation signal calculation unit 330 discretizes the cycle by M, the correlation signal is expressed by the following equation.

Such correlation signal calculation can be executed by the circuit shown in FIG. 6 as an example. FIG. 6 shows an example of a calculation circuit included in the correlation signal calculation unit 330 according to the present embodiment. The correlation signal calculation unit 330 includes a buffer memory 332, a multiplication unit 334, and an addition unit 336.

As an example, the buffer memory 332 shows an example in which the acquired amplitude signal A (φ) is stored as data of 8 points every 45 °. That is, FIG. 6 shows an example when M in the equation (17) is set to 8.

The multiplication unit 334 includes a number of multipliers corresponding to the number of buffer memories 332 (that is, the number corresponding to the resolution of the rotation angle sensor). The multiplier 334 is preferably connected to the storage unit 320 and the buffer memory 332 and includes at least the same number of multipliers as the number of the buffer memories 332. Each of the multipliers corresponds to a periodic function value obtained by substituting eight angle signals φ at 45 ° intervals into the periodic function received from the storage unit 320 (in the case of the first mode, a cosine function of a single angle). The value of the amplitude signal A (φ) is multiplied and the multiplication result is supplied to the adder 336.

The adder 336 is connected to the multiplier 334 and calculates the sum of the received multiplication results. The adder 336 outputs the sum of the multiplication results as a correlation signal calculation result. As described above, the correlation signal calculation unit 330 of the present embodiment calculates the correlation signal of the amplitude signal A (φ) and the cosine function when detecting the error in the first mode. It has been described using the equations (16) and (17) that such a correlation signal becomes a signal corresponding to the offset V _{os_x of the} X axis. In addition, the angle nonlinearity error in this case will be described with reference to FIGS.

FIG. 7 shows an example of the Hall electromotive force signal (V _X , V _Y ). 7, the horizontal axis shows the Hall electromotive force signal V _X of the X-axis direction, the vertical axis represents the Hall electromotive force signal V _Y of the Y-axis direction. A signal indicated by a dotted line is an ideal Hall electromotive force signal, and has a substantially circular shape on the XY plane. A signal indicated by a solid line is a Hall electromotive force signal having an X-axis offset V _{os_x} , and shows an example in which a substantially circular shape is translated in the V _X direction by a distance corresponding to the offset V _{os_x} . Next, the amplitude of the Hall electromotive force signal (V _X , V _Y ) in the example shown in FIG. 7 will be described.

FIG. 8 shows an example of the amplitude of the Hall electromotive force signal (V _X , V _Y ). In response to the rotation of the rotating magnet by 360 °, the magnetic field detection unit 100 outputs a Hall electromotive force signal (V _X , V _Y ) having a cycle of 360 °. FIG. 8 shows Hall electromotive force signals (V _X , V _Y ) in this case, where the horizontal axis is the angular position θ of the rotating magnet and the vertical axis is the amplitude.

In the case of an ideal Hall electromotive force signal, the amplitude A is constant. However, as the Hall electromotive force signal V _X indicated by the dotted line, one of the Hall electromotive force signal V _X may include an offset V _{Os_x,} the amplitude A will vary depending on θ as indicated by one-dot chain lines. As shown in the example of FIG. 8, the fluctuation is generated by the sum of the cosine wave signal having an offset and the sine wave signal. Therefore, the fluctuation is synchronized with the cosine signal having a period of 360 °, and the fluctuation with the cosine signal having a period of 360 °. Correlation becomes stronger.

FIG. 9 shows an example of the angle nonlinearity error of the Hall electromotive force signals (V _X , V _Y ) shown in FIGS. The horizontal axis represents the angular position θ of the rotating magnet, and the vertical axis represents the angle nonlinearity error (φ−θ). For example, when the angle position θ is 0 °, the angle signal φ (0 °) calculated according to the Hall electromotive force signal (V _X = A + V _{os — x} , V _Y = 0) is also 0 °, and the angle nonlinearity error is 0 °. When the angle position θ is 90 °, the angle signal φ (90 °) calculated according to the Hall electromotive force signal (V _X = V _os — _x , V _Y = A) is smaller than 90 °, and the angle nonlinearity The error is a value smaller than 0 °.

Further, when the angular position θ is 180 °, the angle signal φ (180 °) calculated according to the Hall electromotive force signal (V _X = −A + V _os — _x , V _Y = 0) is also 180 °, and the angle nonlinearity error Becomes 0 °. When the angular position θ is 270 °, the angle signal φ (270 °) calculated in accordance with the Hall electromotive force signal (V _X = V _os — _x , V _Y = −A) is larger than 270 °, and the angle nonlinearity The sex error is a value greater than 0 °. Thus, the angle nonlinearity error fluctuates so as to indicate −sin (θ) with respect to the angle position θ. Since the fluctuation of the angle nonlinearity error shown in FIG. 9 and the fluctuation of the amplitude A shown in FIG. 8 are caused by the offset V _{os_x} of the Hall electromotive force signal, it is impossible to detect the fluctuation of the amplitude A from the correlation signal. This corresponds to detecting a variation in angular nonlinearity error.

Therefore, the correlation signal calculation unit 330 calculates the correlation signal and supplies the calculation result to the correction unit 340 as described with reference to FIG. In this way, the correction unit 340 can detect an angular non-linearity error corresponding to the magnitude of the correlation signal.

Next, the correction unit 340 calculates a correction amount of the Hall electromotive force signal (V _X ) corresponding to the detected angular nonlinearity error in order to reduce the angular nonlinearity error (S420). The correction unit 340 may calculate the correction amount using the Hall electromotive force signals (V _X , V _Y ), and instead of this, the correction amount may be determined with reference to a predetermined table or the like. In this case, a predetermined table may be stored in the storage unit 320 in advance.

Next, the error correction apparatus 300 detects an offset V _{os_y} of the Y axis that is the second axis (S430). In this case, the correlation signal calculation unit 330 calculates a correlation signal between the predetermined periodic function corresponding to the error mode for detecting the Y-axis offset and the amplitude signal. The error correction apparatus 300 sets the error mode as a second mode in which the magnetic field detection unit 100 includes an offset component in the second axial direction. When the error in the second mode increases in the magnetic field detection unit 100, the Hall electromotive force signal (V _X , V _Y ) in Equation (8) is expressed by the following equation as in the error in the first mode. Can be handled as follows.
(Equation 18)
V _X (θ) = A _avg · cos (θ)
V _Y (θ) = A _avg · sin (θ) + V _{os_y}

Therefore, the amplitude signal A (θ) in the equation (14) is calculated as the following equation. Here, _CY represents a constant.
(Equation 19)
A (θ) = {V _X (θ) ² + V _Y (θ) ² } ^1/2
= {A _avg ² + V _{os — y} ² + 2 · A _avg · V _os — _y · sin (θ)} ^1/2
≒ C _Y + V _{os_y} · sin (θ)

As described above, the amplitude signal A (θ) has a component that varies like a sine function in accordance with the rotation angle θ. Therefore, by taking a correlation with the sine function sin (θ), the offset V _{os_y} of the Y axis is _obtained. It is possible to detect a signal corresponding to. That is, when the error mode is the second mode, the correlation signal calculation unit 330 calculates a correlation signal with the signal under measurement using the periodic function as a sine of a single angle.

More specifically, the correlation signal is expressed by the following equation.

In the circuit shown in FIG. 6, the correlation signal is calculated by changing the coefficient corresponding to the angle every 45 ° (that is, the periodic function received from the storage unit 320) from cos (θ) to sin (θ). Can be executed. The correlation signal calculation unit 330 calculates a correlation signal and supplies the calculation result to the correction unit 340. In this way, the correction unit 340 can detect an angular non-linearity error corresponding to the magnitude of the correlation signal.

Next, the correction unit 340 calculates a correction amount of the Hall electromotive force signal (V _Y ) corresponding to the detected angular nonlinearity error in order to reduce the angular nonlinearity error (S440). The correction unit 340 may calculate the correction amount using the Hall electromotive force signals (V _X , V _Y ), and instead of this, the correction amount may be determined with reference to a predetermined table or the like.

Next, the error correction apparatus 300 detects an error of an amplitude value difference (A _x −A _y ) indicating a magnetic sensitivity mismatch between the first Hall element pair 110 and the second Hall element pair 120 (S450). The correlation signal calculation unit 330 calculates a correlation signal between a predetermined periodic function corresponding to a magnetic sensitivity mismatch error mode and an amplitude signal. The error correction apparatus 300 sets the error mode to a third mode in which the magnetic field detection unit 100 includes a magnetic sensitivity mismatch between a signal corresponding to the first axis and a signal corresponding to the second axis. In the magnetic field detection unit 100, when such an error in the third mode increases, the Hall electromotive force signal (V _X , V _Y ) in Expression (8) can be handled as the following expression.
(Equation 21)
V _X (θ) = {A _avg + (A _x −A _y ) / 2} · cos (θ)
V _Y (θ) = {A _avg + (A _x + A _y ) / 2} · sin (θ)

Therefore, the amplitude signal A (θ) in the equation (14) is calculated as the following equation.
(Equation 22)
A (θ) = {V _X (θ) ² + V _Y (θ) ² } ^1/2
≒ A _avg + {(A _x -A _y ) / 2} · cos (2θ)

As described above, the amplitude signal A (θ) has a component that varies like a double angle cosine function in accordance with the rotation angle θ. Therefore, by taking a correlation with the double angle cosine function cos (2θ), A signal corresponding to the magnetic sensitivity mismatch (A _x -A _y ) can be detected. That is, when the error mode is the third mode, the correlation signal calculation unit 330 calculates a correlation signal with the signal under measurement using the periodic function as a cosine of double angle.

Such correlation signal calculation can be executed by changing the coefficient corresponding to the angle of every 45 ° from cos (θ) to cos (2θ) in the circuit shown in FIG. Here, the angle nonlinearity error in this case will be described with reference to FIGS.

FIG. 10 shows an example of the Hall electromotive force signal (V _X , V _Y ). Figure 10 is similar to FIG. 7, the horizontal axis represents the Hall electromotive force signal V _X of the X-axis direction, the vertical axis represents the Hall electromotive force signal V _Y of the Y-axis direction. A signal indicated by a dotted line is an ideal Hall electromotive force signal, and has a substantially circular shape on the XY plane. A signal indicated by a solid line is a Hall electromotive force signal having a magnetic sensitivity mismatch, and shows an example in which (A _x −A _y ) / A _y is 0.1. Next, the amplitude of the Hall electromotive force signal (V _X , V _Y ) in the example shown in FIG. 10 will be described.

FIG. 11 shows an example of the amplitude of the Hall electromotive force signal (V _X , V _Y ). In response to the rotation of the rotating magnet by 360 °, the magnetic field detection unit 100 outputs a Hall electromotive force signal (V _X , V _Y ) having a cycle of 360 °. FIG. 11 shows the Hall electromotive force signals (V _X , V _Y ) with the horizontal axis representing the angular position θ of the rotating magnet and the vertical axis representing the amplitude, as in FIG.

In the case of an ideal Hall electromotive force signal, the amplitude A is constant. However, the amplitude of the Hall electromotive force signal V _X indicated by a dotted line, when about 10% greater than the amplitude of the Hall electromotive force signal V _Y, amplitude A varies depending on θ as indicated by one-dot chain lines. As shown in the example of FIG. 11, the fluctuation is caused by the sum of a sine wave signal and a cosine wave signal having different amplitude values, so that the fluctuation is synchronized with the cosine signal having a period of 180 ° and is correlated with the double angle cosine signal. Becomes stronger.

FIG. 12 shows an example of the angular nonlinearity error of the Hall electromotive force signals (V _X , V _Y ) shown in FIGS. In FIG. 12, as in FIG. 9, the horizontal axis represents the angular position θ of the rotating magnet, and the vertical axis represents the angle nonlinearity error (φ−θ). For example, when the angular position θ is 0 °, the angle signal φ (0 °) calculated according to the Hall electromotive force signal (V _X = 1.1A, V _Y = 0) is also 0 °, and the angle nonlinearity error Becomes 0 °. Similarly, when the angular position θ is 90 °, 180 °, or 270 °, the angle signal φ (θ) calculated according to the Hall electromotive force signal is also 0 °, and the angle nonlinearity error is 0 °.

When the angular position θ is 45 °, the angle signal φ (45 ° calculated according to the Hall electromotive force signal (V _X = 1.1 · 2 ^−1/2 , V _Y = 2 ^−1/2 ) ) Is smaller than 45 °, and the angle nonlinearity error is smaller than 0 °. When the angular position θ is 135 °, the angle signal φ (135 calculated based on the Hall electromotive force signal (V _X = −1.1 · 2 ^−1/2 , V _Y = 2 ^−1/2 ). °) is greater than 135 °, and the angle nonlinearity error is greater than 0 °. Thus, the angle nonlinearity error fluctuates so as to indicate −sin (2θ) with respect to the angle position θ. The fluctuation of the angle nonlinearity error shown in FIG. 12 and the fluctuation of the amplitude A shown in FIG. 11 are caused by the magnetic sensitivity mismatch (A _x −A _y ) of the Hall electromotive force signal. Is detected from the correlation signal is equivalent to detecting a magnetic sensitivity mismatch (A _x -A _y ) component of the angular nonlinearity error.

Therefore, the correlation signal calculation unit 330 calculates a correlation signal and supplies the calculation result to the correction unit 340. In this way, the correction unit 340 can detect an angular non-linearity error corresponding to the magnitude of the correlation signal.

Next, the correction unit 340 calculates a correction amount of the Hall electromotive force signal (V _X , V _Y ) corresponding to the detected angular nonlinearity error in order to reduce the angular nonlinearity error (S460). The correction unit 340 may calculate the correction amount using the Hall electromotive force signals (V _X , V _Y ), and instead of this, the correction amount may be determined with reference to a predetermined table or the like.

Next, the error correction apparatus 300 detects the non-orthogonality error α between the Hall electromotive force signals (V _X , V _Y ) (S470). The correlation signal calculation unit 330 calculates a correlation signal between a predetermined periodic function corresponding to a non-orthogonal error mode and an amplitude signal. The error correction apparatus 300 sets the error mode to a fourth mode in which the magnetic field detection unit 100 includes a non-orthogonal error between a signal corresponding to the first axis and a signal corresponding to the second axis. When the error in the fourth mode increases in the magnetic field detection unit 100, the Hall electromotive force signal (V _X , V _Y ) in Expression (8) can be handled as the following expression.
(Equation 24)
V _X (θ) = A _avg · cos (θ)
V _Y (θ) = A _avg · sin (θ + α)

Therefore, the amplitude signal A (θ) in the equation (14) is calculated as the following equation.
(Equation 25)
A (θ) = {V _X (θ) ² + V _Y (θ) ² } ^1/2
= A _avg · {cos ² (θ) + sin ² (θ + α)} ^1/2
≈ A _avg · [1 + α · {sin (2θ)} / 2]

Thus, since the amplitude signal A (θ) has a component that varies like a double angle sine function in accordance with the rotation angle θ, by taking a correlation with the double angle sine function sin (2θ), A signal corresponding to the non-orthogonal error α can be detected. That is, when the error mode is the fourth mode, the correlation signal calculation unit 330 calculates the correlation signal with the signal under measurement using the periodic function as a double angle sine.

Such correlation signal calculation can be executed by changing a coefficient corresponding to an angle of every 45 ° from cos (θ) to sin (2θ) in the circuit shown in FIG. Therefore, the correlation signal calculation unit 330 calculates a correlation signal and supplies the calculation result to the correction unit 340. In this way, the correction unit 340 can detect an angular non-linearity error corresponding to the magnitude of the correlation signal.

Next, the correction unit 340 calculates a correction amount of the Hall electromotive force signal (V _X , V _Y ) corresponding to the detected angular nonlinearity error in order to reduce the angular nonlinearity error (S480). The correction unit 340 may calculate the correction amount using the Hall electromotive force signals (V _X , V _Y ), and instead of this, the correction amount may be determined with reference to a predetermined table or the like.

Next, the correction unit 340 corrects the Hall electromotive force signal (V _X , V _Y ) based on the calculated correction amount (S490). For example, the correction unit 340 supplies a correction signal to the AD conversion unit 220 and the AD conversion unit 222, and superimposes the correction value on the input analog signal, threshold value, offset, and the like in the process of converting into a digital signal.

Here, the AD conversion unit 220 is a first AD conversion unit that converts the detection result of the magnetic field of the first axis into a digital signal, and as an example, the first 1 corresponding to the detection result of the magnetic field of the first axis. This is a ΔΣ AD converter that outputs a bit ΔΣ signal. The AD conversion unit 222 is a second AD conversion unit that converts the detection result of the magnetic field of the second axis into a digital signal. The AD conversion unit 222 converts the second 1-bit ΔΣ signal corresponding to the detection result of the magnetic field of the second axis. This is a ΔΣ AD converter that outputs. In this case, the signal detection device 200 has a servo loop that calculates the angle signal φ based on the first and second 1-bit ΔΣ signals.

In this case, the correction unit 340 may supply a correction signal for correcting the detection signal to the first AD conversion unit and the second AD conversion unit, respectively. For example, the correction unit 340 can adjust the offset of the first AD conversion unit and / or the second AD conversion unit by supplying the modulated reference current as a correction signal to the first AD conversion unit and / or the second AD conversion unit. The operation of adjusting the offset by supplying the modulated reference current to the ΔΣ AD converter is known as described in Non-Patent Document 5, for example, and thus detailed description thereof is omitted here. .

Further, the correction unit 340 generates a correction voltage by modulating a predetermined voltage from a reference voltage or the like with a duty corresponding to the voltage to be corrected, and adds the correction voltage to the input voltage of the AD conversion unit, thereby performing the AD conversion. The offset of the part may be adjusted. In this case, the correction unit generates the modulation signal by adjusting the duty so that the time average of the correction voltage becomes a voltage corresponding to the correction amount. As described above, the correction unit 340 can correct the errors in the first mode and the second mode, respectively.

Further, the correction unit 340 may correct the magnetic sensitivity mismatch by adjusting the amplification degree of the first AD conversion unit and / or the second AD conversion unit. The correction unit 340 may adjust the amplification degree using, for example, a variable capacitor or a variable resistor. In addition, since the operation | movement which adjusts the amplification degree of a delta-sigma type AD conversion part is known as it describes, for example in patent document 9, detailed description is abbreviate | omitted here. As described above, the correction unit 340 can correct the error in the third mode.

The correction unit 340, an input as an example, to switch the input connections of the first 2AD conversion unit Hall electromotive force signal V _Y is input, only the predetermined time the Hall electromotive force signal V _X to the 2AD conversion unit Thus, the non-orthogonal error α may be corrected. The non-orthogonal error α is generated by mixing a signal corresponding to the magnetic field in the second axial direction into the Hall electromotive force signal Vx that should originally correspond to the magnetic field in the first axial direction (and / or inherently in the second axial direction). This is an error caused by mixing a signal corresponding to the magnetic field in the first axial direction into the Hall electromotive force signal Vy that should correspond to the magnetic field. Therefore, the correction of the non-orthogonal error α can be realized by calculating an appropriate linear sum (linear combination) between the Hall electromotive force signals Vx and Vy so as to cancel the error. The operation of the correction unit 340 is a method for realizing a coupling coefficient on the time axis when calculating the linear sum (linear combination) of the Hall electromotive force signals Vy and Vx.

That is, the correction unit 340, by inputting the hole electromotive force signal V _X or Hall electromotive force signal V _Y in one AD conversion section (first 2AD conversion unit as an example), to correct the non-orthogonality error α it can. In this case, the correction unit 340 corrects the non-orthogonality error α by switching the input of the one AD conversion unit according to the correction amount. As described above, the correction unit 340 can correct the error in the fourth mode.

The error correction apparatus 300 determines whether or not the correction of the angle non-linearity error is finished (S500). When the correction of the angle nonlinearity error is continued (S500: No), the error correction apparatus 300 returns to the step of obtaining the angle signal and the amplitude signal (S400) and continues the correction of the angle nonlinearity error. The error correction apparatus 300 stops the above process when the correction of the angle non-linearity error is terminated by an input from the user or the like (S500: Yes).

As described above, the error correction apparatus 300 according to the present embodiment has the angle nonlinearity caused by the X-axis offset, the Y-axis offset, the magnetic detection sensitivity mismatch, and the non-orthogonality error of the magnetic field detection unit 100 in operation. An error can be detected and fed back to the rotational angle sensor in operation to correct the detection signal. Therefore, the error correction apparatus 300 can detect an error for each error mode even when the magnetic field detection unit 100 is mounted on a rotation angle sensor, a system, and the like, and performs appropriate correction according to the error mode. be able to.

In the error correction apparatus 300 of this embodiment described above, the correlation signal calculation unit 330 has been described as an example in which the first signal of the amplitude signal A (φ) (that is, the amplitude signal itself) is the signal under measurement. Instead, the correlation signal calculation unit 330 may use a square signal of the amplitude signal A (φ) as the signal under measurement.

In this case, the signal under measurement shown by the equation (16) is calculated as the following equation.
(Equation 27)
A ² (θ) = V _X (θ) ² + V _Y (θ) ²
= A _avg ² + V _{os_x} ² + 2 · A _avg · V _{os_x} · cos (θ)

Since the signal under measurement A ² (θ) has a component that varies like a cosine function in accordance with the rotation angle θ, by taking a correlation with the cosine function cos (θ), it corresponds to the X-axis offset V _{os_x} . Signal can be detected. A specific correlation signal is expressed by the following equation.

Similarly, the signal under measurement shown by the equation (19) is calculated as the following equation.
(Equation 29)
A ² (θ) = V _X (θ) ² + V _Y (θ) ²
= A _avg ² + V _{os_y} ² + 2 · A _avg · V _{os_y} · sin (θ)

Since the signal under measurement A ² (θ) has a component that varies like a sine function in accordance with the rotation angle θ, by taking a correlation with the sine function sin (θ), the signal under measurement A ² (θ) corresponds to the offset V _{os_y} of the Y axis. Signal can be detected. A specific correlation signal is expressed by the following equation.

Similarly to the error modes of the first mode and the second mode described above, the signal under measurement A ² (θ) may be used as the signal under measurement in the third mode and the fourth mode. In this case, the periodic function corresponding to the error mode may be a periodic function when the signal under measurement is A (θ). In this case, the correlation signal of the third mode shown in (Expression 23) is expressed by (Expression 31), and the correlation signal of the fourth mode shown in (Expression 26) is expressed by (Expression 32). As shown.

As described above, the correlation signal calculation unit 330 can calculate the periodic function corresponding to the signal under measurement and the error mode for each mode. Therefore, the correlation signal calculation unit 330 can also calculate the Nth power signal (N is a natural number of 1 or more) of the amplitude signal A (φ) as the signal under measurement.

Further, the example in which the error correction apparatus 300 of the present embodiment has the error modes from the first mode to the fourth mode has been described. Instead, the error correction apparatus 300 may have at least one of the error modes from the first mode to the fourth mode, and correct the error in at least one mode.

Further, the example in which the error correction apparatus 300 of the present embodiment is connected to the signal detection apparatus 200 has been described. Instead of this, the error correction device 300 may be a part of the signal detection device 200. In this case, the angle signal φ and the amplitude signal A (φ) of the rotating body are obtained according to the detection signals of the error correction device 300 and the magnetic field detection unit 100 that detects the magnetic field of the first axis and the magnetic field of the second axis. A rotation angle detection device including the signal detection device 200 for outputting may be configured.

Alternatively, the error correction device 300 may be provided in the magnetic field detection unit 100. In this case, the error correction device 300 is preferably provided in the magnetic field detection unit 100 together with the signal detection device 200. That is, the magnetic field detection unit 100 in this case includes a rotation angle detection device including the signal detection device 200 and the error correction device 300, and rotates according to the detection results of the first axis magnetic field and the second axis magnetic field. The body angle signal φ and the amplitude signal A (φ) are output.

In addition, the error correction apparatus 300 according to the present embodiment is connected to the signal detection apparatus 200 illustrated in FIG. 3 and the example in which the angle signal φ and the amplitude signal A (φ) are acquired has been described. Since the error correction device 300 can detect an error if the angle signal φ and the amplitude signal A (φ) can be acquired, the signal detection device 200 is not limited to the example of FIG. For example, the signal detection device 200 may be a calculation circuit such as a CORDIC based on a trigonometric function calculation model.

FIG. 13 shows a modification of the error correction apparatus 300 according to this embodiment. The error correction apparatus 300 of the present modification obtains the angle signal φ and the amplitude signal A (φ) from the signal calculation circuit 500. The signal calculation circuit 500 includes an amplification unit 510, an amplification unit 512, an AD conversion unit 520, an AD conversion unit 522, and a CORDIC circuit unit 530. The amplification unit 510, amplification unit 512, AD conversion unit 520, and AD conversion unit 522 perform substantially the same operations as the amplification unit 210, amplification unit 212, AD conversion unit 220, and AD conversion unit 222 described in FIG. Therefore, the description is omitted here.

The CORDIC (Coordinate Rotation Digital Computing) circuit unit 530 generates an angle signal φ and an amplitude signal A (φ) from the Hall electromotive force signal as an input signal based on an algorithm that performs various operations such as trigonometric functions, multiplication, and division. calculate. The CORDIC circuit unit 530 may be an integrated circuit such as an FPGA (Field-Programmable Gate Array) on which the CORDIC algorithm is mounted, and an ASIC (Application Specific Integrated Circuit).

The CORDIC circuit unit 530 executes a predetermined CORDIC algorithm to calculate the angle signal φ and the amplitude signal A (φ). Here, it is known that the CORDIC circuit unit 530 outputs an amplitude signal that is about 1.6 times larger than the amplitude signal output by the signal detection device 200 shown in FIG.

However, since the correlation signal calculation unit 330 according to the present embodiment calculates the correlation between the signal under measurement based on the amplitude signal and a predetermined periodic function corresponding to the error mode, the amplitude signal is (1.6 times). Correlation signals that have almost no effect even if they become a constant multiple (about) are calculated. Therefore, the error correction apparatus 300 according to the present modification can detect the angular non-linearity error of the magnetic field detection unit 100 with substantially the same operation as the error correction apparatus 300 described with reference to FIGS.

Here, the correction unit 340 may correct the detection signal of the magnetic field detection unit 100 by substantially the same operation as the error correction device 300 described with reference to FIGS. Further, the correction unit 340 may include a correction circuit 342 inside the signal calculation circuit 500 and supply the correction signal to the correction circuit 342 to correct the detection signal. The correction circuit 342 is connected to the AD conversion unit 520 and the AD conversion unit 522, and receives the Hall electromotive force signals (ADC (V _X ), ADC (V _Y )) converted from digital signals. Correction circuit 342, the Hall electromotive force signal in accordance with the correction amount received from the correction unit 340 corrects the _{(ADC (V X), ADC} (V Y)), hole corrected electromotive force signal (ADC _{(V X} ) ′, ADC (V _Y ) ′) is supplied to the CORDIC circuit unit 530.

Here, when the CORDIC circuit unit 530 is an integrated circuit such as an FPGA and an ASIC, the correction circuit 342 may also be incorporated in the integrated circuit. In this case, the signal calculation circuit 500 can execute the signal correction process and the signal calculation process by digital signal processing in one integrated circuit, and the apparatus can be downsized.

It has been described that the error correction device 300 of the present embodiment described above may be a device independent of the rotation angle sensor and may be a part of the magnetic field detection unit 100 instead. Instead of this, the error correction device 300 may be a part of a system or the like in which the magnetic field detection unit 100 is mounted. Further, the error correction apparatus 300 may be a part of a control circuit that controls the system or the like.

In the error correction apparatus 300 of the present embodiment described above, the example in which the magnetic field detection unit 100 includes the first Hall element pair 110 and the second Hall element pair 120 has been described. Here, the error correction apparatus 300 calculates an error based on the output signal of the rotation angle sensor that outputs the angle signal and the amplitude signal of the rotating body according to the detection results of the magnetic field of the first axis and the magnetic field of the second axis. Since it detects, the detection element of a magnetic field is not limited to a Hall element. For example, the magnetic field detection unit 100 may include a plurality of GMR (Giant Magneto-Resistance) elements and / or TMR (Tunnel Magneto-Resistance) elements that detect the magnetic field of the first axis and the magnetic field of the second axis. Good.

The error correction apparatus 300 of the present embodiment described above can detect an error for each error mode and execute an appropriate correction according to the error mode even when the magnetic field detection unit 100 is mounted on a system or the like. I explained what I can do. Instead of this or in addition to this, the error correction device 300 may detect an error of the magnetic field detection unit 100 in a state of being incorporated in the rotation angle sensor module or the like, and execute correction according to the error. Good.

FIG. 14 shows an example of the rotation angle sensor module 400 according to the present embodiment. The rotation angle sensor module 400 includes a magnetic field detection unit 100, a rotating magnet 410, a rotating shaft 412, and a motor 420. Since the magnetic field detection unit 100 has been described with reference to FIGS. 1 to 13, description thereof is omitted here. In this example, it is assumed that the signal detection device 200 is formed inside the magnetic field detection unit 100.

The rotating magnet 410 rotates around the rotating shaft 412. FIG. 14 shows an example in which the rotating magnet 410 is provided above the magnetic field detection unit 100. For example, the rotating magnet 410 has a disk shape and rotates on a plane substantially parallel to the XY plane. The rotating magnet 410 may be divided into two regions each having a semicircular cross section substantially parallel to the XY plane, and forms a magnet in which one region is an S pole and the other region is an N pole. The rotating magnet 410 ideally causes the magnetic field detection unit 100 to generate a rotating magnetic field represented by, for example, Equation (33) by rotating on a plane substantially parallel to the XY plane.

The rotating shaft 412 is formed in a direction substantially perpendicular to the XY plane. For example, the rotation axis 412 has an intersection of the X axis passing through the first Hall element pair 110 and the Y axis passing through the second Hall element pair 120 on the extension line of the central axis on the magnetic field detection unit 100 side. Formed. The rotating shaft 412 has one end connected to the rotating magnet 410 and the other end connected to the motor 420. The motor 420 rotates the rotating shaft 412 and the rotating magnet 410 connected to the rotating shaft.

As described above, the rotation angle sensor module 400 is formed by assembling the magnetic field detection unit 100 and the rotating magnet 410 that rotates about the rotation axis 412. That is, the magnetic field detection unit 100 detects the magnetic field in the X-axis direction and the magnetic field in the Y-axis direction on the XY plane, and detects the rotation angle on the XY plane of the rotating magnet 410 that rotates about the rotation axis 412.

When an assembly error or the like occurs in the process of assembling such a rotation angle sensor module or the like, the magnetic field detection unit 100 is applied with a magnetic field in a direction different from the equation (33), which is caused by the assembly error. An angle nonlinearity error occurs. FIGS. 15 to 17 show examples when such an assembly error occurs.

FIG. 15 shows an example of an assembly error in which the center axis shift occurs in the rotation angle sensor module 400 according to the present embodiment. FIG. 16 shows an example of an assembly error in which eccentricity occurs in the rotation angle sensor module 400 according to the present embodiment. FIG. 17 shows an example of an assembly error in which the rotation magnet 410 is inclined in the rotation angle sensor module 400 according to the present embodiment.

Even when such an error occurs, the magnetic field detection unit 100 generates an angular non-linearity error that varies so as to indicate a periodic function according to the angular position θ of the rotating magnet 410. Therefore, the error correction apparatus 300 according to the present embodiment reduces the angle nonlinearity error caused by the assembly error of the rotation angle sensor module 400, as in the case of reducing the angle nonlinearity error of the magnetic field detection unit 100.

FIG. 18 shows an example in which magnetic fields in eight directions are applied to the magnetic field detector 100 of the ideal rotation angle sensor module 400, respectively. That is, FIG. 18 shows, by arrows, the directions of magnetic fields generated on the XY plane where the magnetic field detector 100 is installed when the rotating magnet 410 rotates at 45 ° intervals. A plurality of circles in FIG. 18 respectively indicate the rotating magnets 410, and a square indicated by a dotted line in the circle indicates the position of the magnetic field detection unit 100. Since the rotation angle sensor module 400 has an ideal arrangement relationship, the center of the circle coincides with the center of the quadrangular region indicated by the dotted line. It can be seen that as the rotation angle changes from 0 ° to 315 ° by 45 °, the direction of the magnetic field vector generated in the region where the magnetic field detection unit 100 is located also rotates by 45 °.

FIG. 19 shows an example in which magnetic fields in eight directions are respectively applied to the magnetic field detection unit 100 of the rotation angle sensor module 400 having an assembly error of the center axis deviation. That is, FIG. 19 shows the magnetic field generated in the XY plane on which the magnetic field detector 100 is installed when the rotating magnet 410 rotates at 45 ° intervals in the rotation angle sensor module 400 in which the center axis deviation shown in FIG. The direction is indicated by arrows. A plurality of circles in FIG. 19 respectively indicate the rotating magnets 410 as in FIG. 18, and a square indicated by a dotted line in the circle indicates the position of the magnetic field detection unit 100. Since the center axis shift has occurred, a shift has occurred between the center of the circle and the center of the quadrangular region indicated by the dotted line.

When the rotating magnet 410 is rotated, when the rotation angle θ is 45 °, 135 °, 225 °, or 315 °, a magnetic field vector in a direction different from the rotation angle θ of the rotating magnet 410 is generated in the rectangular region. It can be seen that an angle nonlinearity error occurs. On the other hand, when the rotation angle θ is 0 °, 90 °, 180 °, or 270 °, the direction of the magnetic field vector generated in the rectangular region and the direction of the applied magnetic field substantially coincide with each other, so that the angle nonlinearity error is reduced. I understand that. That is, it can be seen that the direction of the magnetic field input to the magnetic field detection unit 100 varies according to the rotation angle θ of the rotating magnet 410, and the variation varies so as to indicate sin (2θ) with respect to the angle θ.

That is, the magnetic field detection unit 100 incorporated in the rotation angle sensor module 400 having the assembly error of the center axis deviation has an angular non-linearity error indicating the fluctuation of the periodic function. Therefore, a correlation signal can be calculated by taking a correlation with the periodic function. Similarly, even if the rotation angle sensor module 400 has an assembly error that causes eccentricity and inclination of the rotating magnet 410, when the fluctuation of the generated angle nonlinearity error shows a periodic function, (Equation 17), (Equation 17) 20), (Equation 23), and (Equation 26) can be used to calculate the correlation signal (or (Equation 28) and (Equation 30) to (Equation 32)).

20 to 23 show an example of the result of simulating the correction of the angle nonlinearity error generated by the rotation angle sensor module 400 according to the present embodiment. As an example, the simulation is a result calculated assuming that a center axis deviation of 2 mm occurs between the magnetic field detection unit 100 and the rotating magnet 410 in the X-axis direction and the Y-axis direction, respectively.

FIG. 20 shows an example of the magnetic field detection signals (V _X (θ), V _Y (θ)) when a center axis deviation occurs between the rotating magnet 410 and the magnetic field detection unit 100. The horizontal axis in FIG. 20 indicates the angular position θ of the rotating magnet, and the vertical axis indicates the signal amplitude. The magnetic field detection unit 100 detects magnetic field detection signals (V _X (θ), V _Y (θ)) that change periodically according to the rotating magnetic field. Note that it is difficult to read the influence of the center axis deviation from the signal.

FIG. 21 shows an example of the amplitude signal A (θ) when the center axis deviation occurs between the rotating magnet 410 and the magnetic field detection unit 100. The horizontal axis in FIG. 21 indicates the angular position θ of the rotating magnet, and the vertical axis indicates the amplitude signal intensity. As described with reference to FIG. 19, it can be seen that the amplitude signal A (θ) fluctuates so as to indicate −sin (2θ). Thereby, it can be predicted that an angle nonlinearity error has occurred in the magnetic field detection unit 100.

Actually, using ( _Equation 17), ( _Equation 20), ( _Equation 23), and ( _Equation 26), error parameters (V _os — _x , V _os — _y , A _x −A _y ) that cause an error in the angle nonlinearity error are used. , Α) was calculated to be (0 (% FS), 0 (% FS), 0 (% FS), 1.7 °). Here, “FS” means full scale, and “% FS” indicates percentage intensity with respect to full scale. From the calculation result, it can be seen that the angle nonlinearity error due to the deviation of the central axis in this simulation can be treated as a non-orthogonality error.

FIG. 22 shows an example of an angular non-linearity error (φ (θ) −θ) when a center axis deviation occurs between the rotating magnet 410 and the magnetic field detection unit 100. The horizontal axis of FIG. 22 indicates the angular position θ of the rotating magnet, and the vertical axis indicates the angle nonlinearity error (φ (θ) −θ). From FIG. 22, it can be seen that the angle nonlinearity error fluctuates to indicate cos (2θ). It can be seen from the fluctuation that the center axis deviation is an error that can be handled in the same manner as the non-orthogonal error.

FIG. 23 shows an example of the result of correcting the angle nonlinearity error when the center axis deviation occurs. In FIG. 23, the horizontal axis represents the angular position θ of the rotating magnet, and the vertical axis represents the angle nonlinearity error (φ (θ) −θ). The error correction device 300 corrects the magnetic field detection signal from the error parameter (0, 0, 0, 1.7 °), thereby changing the angle nonlinearity error shown in FIG. 22 into the angle nonlinearity error shown in FIG. It can be seen from the simulation that this can be reduced.

As described above, the error correction apparatus 300 according to the present embodiment can reduce the angle nonlinearity error caused by the assembly error when the magnetic field detection unit 100 is incorporated in the rotation angle sensor module 400. Since the error correction device 300 can dynamically reduce the angle nonlinearity error of the magnetic field detection unit 100 according to the output of the rotation angle sensor, even if the assembly error varies with time, Angular nonlinearity errors can also be reduced. Further, the error correction apparatus 300 can collectively calibrate the angle nonlinearity error caused by the angle nonlinearity error of the magnetic field detection unit 100 and the assembly error of the rotation angle sensor module 400.

FIG. 24 shows an example of a hardware configuration of a computer 1900 that functions as the error correction apparatus 300 according to the present embodiment. A computer 1900 according to this embodiment is connected to a CPU peripheral unit having a CPU 2000, a RAM 2020, a graphic controller 2075, and a display device 2080 that are connected to each other by a host controller 2082, and to the host controller 2082 by an input / output controller 2084. An input / output unit having a communication interface 2030, a hard disk drive 2040, and a DVD drive 2060; a legacy input / output unit having a ROM 2010, a flexible disk drive 2050, and an input / output chip 2070 connected to the input / output controller 2084; Is provided.

The host controller 2082 connects the RAM 2020 to the CPU 2000 and the graphic controller 2075 that access the RAM 2020 at a high transfer rate. The CPU 2000 operates based on programs stored in the ROM 2010 and the RAM 2020 and controls each unit. The graphic controller 2075 acquires image data generated by the CPU 2000 or the like on a frame buffer provided in the RAM 2020 and displays it on the display device 2080. Instead of this, the graphic controller 2075 may include a frame buffer for storing image data generated by the CPU 2000 or the like.

The input / output controller 2084 connects the host controller 2082 to the communication interface 2030, the hard disk drive 2040, and the DVD drive 2060, which are relatively high-speed input / output devices. The communication interface 2030 communicates with other devices via a network. The hard disk drive 2040 stores programs and data used by the CPU 2000 in the computer 1900. The DVD drive 2060 reads a program or data from the DVD-ROM 2095 and provides it to the hard disk drive 2040 via the RAM 2020.

Also, the ROM 2010, the flexible disk drive 2050, and the relatively low-speed input / output device of the input / output chip 2070 are connected to the input / output controller 2084. The ROM 2010 stores a boot program that the computer 1900 executes at startup and / or a program that depends on the hardware of the computer 1900. The flexible disk drive 2050 reads a program or data from the flexible disk 2090 and provides it to the hard disk drive 2040 via the RAM 2020. The input / output chip 2070 connects the flexible disk drive 2050 to the input / output controller 2084 and inputs / outputs various input / output devices via, for example, a parallel port, a serial port, a keyboard port, a mouse port, and the like. Connect to controller 2084.

The program provided to the hard disk drive 2040 via the RAM 2020 is stored in a recording medium such as the flexible disk 2090, the DVD-ROM 2095, or an IC card and provided by the user. The program is read from the recording medium, installed in the hard disk drive 2040 in the computer 1900 via the RAM 2020, and executed by the CPU 2000.

The program is installed in the computer 1900, and causes the computer 1900 to function as the acquisition unit 310, the storage unit 320, the correlation signal calculation unit 330, and the correction unit 340.

The information processing described in the program is read into the computer 1900, whereby the acquisition unit 310, the storage unit 320, and the correlation signal calculation unit 330 are specific means in which the software and the various hardware resources described above cooperate. , And the correction unit 340. The specific error correction apparatus 300 according to the purpose of use is constructed by realizing calculation or processing of information according to the purpose of use of the computer 1900 in this embodiment by this specific means.

As an example, when communication is performed between the computer 1900 and an external device or the like, the CPU 2000 executes a communication program loaded on the RAM 2020 and executes a communication interface based on the processing content described in the communication program. A communication process is instructed to 2030. Under the control of the CPU 2000, the communication interface 2030 reads transmission data stored in a transmission buffer area or the like provided on a storage device such as the RAM 2020, the hard disk drive 2040, the flexible disk 2090, or the DVD-ROM 2095, and sends it to the network. The reception data transmitted or received from the network is written into a reception buffer area or the like provided on the storage device. As described above, the communication interface 2030 may transfer transmission / reception data to / from the storage device by the DMA (Direct Memory Access) method. Instead, the CPU 2000 transfers the storage device or the communication interface 2030 as the transfer source. The transmission / reception data may be transferred by reading the data from the data and writing the data to the communication interface 2030 or the storage device of the transfer destination.

The CPU 2000 also includes all or necessary portions of files or databases stored in an external storage device such as the hard disk drive 2040, DVD drive 2060 (DVD-ROM 2095), and flexible disk drive 2050 (flexible disk 2090). Are read into the RAM 2020 by DMA transfer or the like, and various processes are performed on the data on the RAM 2020. Then, CPU 2000 writes the processed data back to the external storage device by DMA transfer or the like. In such processing, since the RAM 2020 can be regarded as temporarily holding the contents of the external storage device, in the present embodiment, the RAM 2020 and the external storage device are collectively referred to as a memory, a storage unit, or a storage device. Various types of information such as various programs, data, tables, and databases in the present embodiment are stored on such a storage device and are subjected to information processing. Note that the CPU 2000 can also store a part of the RAM 2020 in the cache memory and perform reading and writing on the cache memory. Even in such a form, the cache memory bears a part of the function of the RAM 2020. Therefore, in the present embodiment, the cache memory is also included in the RAM 2020, the memory, and / or the storage device unless otherwise indicated. To do.

In addition, the CPU 2000 performs various operations, such as various operations, information processing, condition determination, information search / replacement, etc., described in the present embodiment, specified for the data read from the RAM 2020 by the instruction sequence of the program. Is written back to the RAM 2020. For example, when performing the condition determination, the CPU 2000 determines whether the various variables shown in the present embodiment satisfy the conditions such as large, small, above, below, equal, etc., compared to other variables or constants. When the condition is satisfied (or not satisfied), the program branches to a different instruction sequence or calls a subroutine.

Further, the CPU 2000 can search for information stored in a file or database in the storage device. For example, in the case where a plurality of entries in which the attribute value of the second attribute is associated with the attribute value of the first attribute are stored in the storage device, the CPU 2000 displays the plurality of entries stored in the storage device. The entry that matches the condition in which the attribute value of the first attribute is specified is retrieved, and the attribute value of the second attribute that is stored in the entry is read, thereby associating with the first attribute that satisfies the predetermined condition The attribute value of the specified second attribute can be obtained.

The programs or modules shown above may be stored in an external recording medium. As a recording medium, in addition to the flexible disk 2090 and the DVD-ROM 2095, an optical recording medium such as a DVD, Blu-ray (registered trademark) or CD, a magneto-optical recording medium such as an MO, a tape medium, a semiconductor such as an IC card, etc. A memory or the like can be used. Further, a storage device such as a hard disk or a RAM provided in a server system connected to a dedicated communication network or the Internet may be used as a recording medium, and the program may be provided to the computer 1900 via the network.

As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

The execution order of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior”. It should be noted that they can be implemented in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for the sake of convenience, it means that it is essential to carry out in this order. is not.

10 substrate, 100 magnetic field detector, 110 first hall element pair, 112 first hall element, 114 second hall element, 120 second hall element pair, 122 third hall element, 124 fourth hall element, 130 magnetic convergence plate , 200 signal detection device, 210 amplification unit, 212 amplification unit, 220 AD conversion unit, 222 AD conversion unit, 230 multiplication unit, 232 multiplication unit, 240 accumulation unit, 242 accumulation unit, 244 accumulation unit, 250 phase compensation unit, 260 Storage unit, 300 error correction device, 310 acquisition unit, 320 storage unit, 330 correlation signal calculation unit, 332 buffer memory, 334 multiplication unit, 336 addition unit, 340 correction unit, 342 correction circuit, 400 rotation angle sensor module, 410 rotation Magnet, 412 rotary shaft, 420 motor, 50 Signal calculation circuit, 510 amplification unit, 512 amplification unit, 520 AD conversion unit, 522 AD conversion unit, 530 CORDIC circuit unit, 1900 computer, 2000 CPU, 2010 ROM, 2020 RAM, 2030 communication interface, 2040 hard disk drive, 2050 flexible disk Drive, 2060 DVD drive, 2070 input / output chip, 2075 graphic controller, 2080 display device, 2082, host controller, 2084 input / output controller, 2090 flexible disk, 2095 DVD-ROM

Claims

An acquisition unit that acquires an output of a signal detection device that outputs an angle signal and an amplitude signal of a rotating body in response to a detection signal of a magnetic field detection unit that detects a magnetic field of a first axis and a magnetic field of a second axis;
A correlation signal calculation unit for calculating a correlation signal between a predetermined periodic function corresponding to an error mode of the magnetic field detection unit and a signal under measurement based on the amplitude signal;
A correction unit that corrects the detection signal corresponding to the error mode based on the correlation signal;
An error correction device comprising:
The error correction device according to claim 1, wherein the correction unit corrects the detection signal acquired by the acquisition unit, and the corrected detection signal is supplied to the signal detection device.
The error mode is
A first mode in which the magnetic field detector includes an offset component of a signal corresponding to the first axial direction;
A second mode in which the magnetic field detector includes an offset component of a signal corresponding to the second axial direction;
A third mode in which the magnetic field detector includes a magnetic sensitivity mismatch between a signal corresponding to the first axis and a signal corresponding to the second axis;
A fourth mode in which the magnetic field detector includes a non-orthogonal error between a signal corresponding to the first axis and a signal corresponding to the second axis;
The error correction device according to claim 1, wherein the error correction device has at least one mode.
The correlation signal calculation unit
When the error mode is the first mode, a correlation signal with the signal under measurement is calculated using the periodic function as a cosine of 1 × square,
When the error mode is the second mode, a correlation signal with the signal under measurement is calculated with the periodic function as a sine of 1 ×
When the error mode is the third mode, a correlation signal with the signal under measurement is calculated using the periodic function as a cosine of a double angle,
The error correction apparatus according to claim 3, wherein when the error mode is the fourth mode, a correlation signal with the signal under measurement is calculated using the periodic function as a sine of a double angle.
The error correction device according to any one of claims 1 to 4, wherein the correlation signal calculation unit calculates an N-th power signal (N is a natural number of 1 or more) of the amplitude signal as the signal under measurement.
The error correction device according to any one of claims 1 to 5, wherein the acquisition unit acquires an output of a non-contact rotation angle sensor.
The error correction apparatus according to any one of claims 1 to 6,
A signal detection device that outputs an angle signal and an amplitude signal of the rotating body according to a detection signal of the magnetic field detection unit that detects a magnetic field of the first axis and a magnetic field of the second axis;
A rotation angle detector.
The signal detection device includes:
A first AD converter that converts a detection result of the magnetic field of the first axis into a digital signal;
A second AD converter for converting the detection result of the magnetic field of the second axis into a digital signal;
Have
The correction unit supplies a correction signal for correcting the detection signal to the first AD conversion unit and the second AD conversion unit, respectively.
The rotation angle detection device according to claim 7.
The first AD conversion unit outputs a first 1-bit ΔΣ signal corresponding to the detection result of the magnetic field of the first axis,
The second AD converter outputs a second 1-bit ΔΣ signal corresponding to the detection result of the magnetic field of the second axis,
The rotation angle detection device according to claim 7 or 8, wherein the signal detection device includes a servo loop that calculates the angle signal based on the first and second 1-bit ΔΣ signals.
The rotation angle detection device according to claim 7 or 8, wherein the signal detection device is a CORDIC.
A rotation angle detection device according to any one of claims 7 to 10,
According to the detection result of the magnetic field of the first axis and the magnetic field of the second axis, the angle signal and the amplitude signal of the rotating body are output.
Rotation angle sensor.
An error correction method for a detection signal of a magnetic field detection unit that detects a magnetic field of a first axis and a magnetic field of a second axis that change according to rotation of a rotating body,
Obtaining an angle signal and an amplitude signal of the rotating body, which are calculated according to the detection signal;
Calculating a correlation signal between a predetermined periodic function corresponding to the error mode of the magnetic field detector and the signal under measurement based on the amplitude signal;
Correcting the detection signal corresponding to the error mode based on the correlation signal;
Error correction method.
The error mode is
A first mode in which the magnetic field detector includes an offset component in the first axial direction;
A second mode in which the magnetic field detector includes an offset component in the second axial direction;
A third mode in which the magnetic field detector includes a magnetic sensitivity mismatch between the first axis and the second axis;
A fourth mode in which the magnetic field detector includes a non-orthogonal error;
The error correction method according to claim 12, comprising at least one mode.
Calculating the correlation signal is
When the error mode is the first mode, a correlation signal with the signal under measurement is calculated using the periodic function as a cosine of 1 × square,
When the error mode is the second mode, a correlation signal with the signal under measurement is calculated with the periodic function as a sine of 1 ×
When the error mode is the third mode, a correlation signal with the signal under measurement is calculated using the periodic function as a cosine of a double angle,
14. The error correction method according to claim 13, wherein when the error mode is the fourth mode, a correlation signal with the signal under measurement is calculated using the periodic function as a sine of a double angle.
A program for causing a computer to execute the error correction method according to any one of claims 12 to 14.
A medium for storing the program according to claim 15.