JP2002206949A - Angle detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an angle detector capable of detecting a high-resolution incremental angle signal using a magnetizing arrangement and a signal process which are relatively simple, and of detecting the absolute angle from the moment that a sensor system is power supplied. SOLUTION: The angle detector includes first and second tracks 1 and 2 magnetized as N- and S-poles at first and second equal intervals on the outer peripheral surface of the drum 4; a magnetic sensor 5 fixed in position opposite to the first and second tracks; and a processing circuit for determining the rotational angle of a rotating shaft 3 by processing detection signals of the magnetic sensor 5. The processing circuit detects the absolute rotational angle of the rotating shaft 3 based on a phase difference between first and second magnetic field signals, and detects a microscopic angle of the relative rotation of the rotating shaft 3 based on the first or second magnetic field signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angle detecting device used for drive control of, for example, a brushless motor, and more particularly to detecting an absolute rotation angle by a relatively simple process even when a magnetized track on a magnetic drum is stationary. The present invention relates to an angle detection device that can perform the angle detection.

[0002]

2. Description of the Related Art Generally, a brushless motor is used for an electric power steering mounted on an automobile, and an angle detecting device for detecting a rotation angle with high accuracy is used for controlling the brushless motor.

FIG. 14 is a perspective view schematically showing a conventional angle detecting device described in, for example, Japanese Patent Application Laid-Open No. Hei 6-94475, and shows a case where it is constituted by an 8-bit magnetic absolute value encoder. .

In FIG. 14, reference numeral 3 denotes a rotating shaft whose angle is to be detected, which is driven to rotate by a motor (not shown). Reference numeral 4 denotes a magnetic drum supported on the rotating shaft 3. The magnetic drum 4 is made of aluminum having a diameter of 20 mm and a width of 2 mm.

[0005] On the outer peripheral side surface of the magnetic drum 4, two series of tracks 1A and 2A each comprising an incremental pattern and a random magnetic pattern magnetized in the direction of the arrow are formed.

Each magnetic pattern on the tracks 1A and 2A is formed by applying a magnetic film of Ba-ferrite to the outer periphery of the magnetic drum 4 to a thickness of 100 μm and magnetizing it with a ring head.

That is, an incremental pattern at equal intervals is written on the track 1A.
Above, an M-sequence random pattern is written.

Reference numeral 5A denotes a magnetic sensor fixedly disposed so as to face the tracks 1A and 2A. Reference numeral 50 denotes an arithmetic processing circuit for processing a detection signal from the magnetic sensor 5A (an electric signal detecting a resistance change based on a change in magnetic flux). It is.

The magnetic sensor 5A is arranged at a portion closest to the magnetic drum 4 at a right angle to a tangent to the surface of the magnetic drum 4. In addition, the magnetic sensor 5A
Is composed of a glass sensor base 51 and two MR elements 52 formed on the sensor base 51.

Each of the MR elements 52 has a width of 20 μm,
It has a pitch of 30 μm and a total length of 3 mm, and constitutes a pattern having the illustrated shape.

FIG. 15 is an explanatory diagram schematically showing a part of the M-sequence magnetization pattern formed on the track 2A in FIG. In FIG. 15, the magnetization pattern of the track 2A includes a magnetized part 221 and a non-magnetized part 222, and the size of one pitch P corresponding to one bit indicates the minimum resolution.

Here, since an 8-bit magnetic absolute value encoder is taken as an example, one pitch corresponds to one pitch. When the magnetic drum 4 moves by one pitch P, the pattern of the track 2A changes. At this time, 256 patterns are generated without overlapping the patterns.

The magnetic flux leakage from the magnetized portion 221 for one pitch P is orthogonal to the sense current flowing through one MR element 52, thereby generating a resistance change, that is, an output signal.
A signal of “1” is output to the magnetized portion 221, and a signal of “0” is output to the non-magnetized portion 222.

Therefore, in the arithmetic processing circuit 50, the first 8-bit pattern "01111111" is called "1", the second pattern "11111111" is called "2", and the third pattern "11111110" is called "3". In this way, the addresses are stored.

On the other hand, in the incremental pattern formed on the track 1A, although not shown here, magnetized portions and non-magnetized portions are alternately repeated at a pitch corresponding to the minimum resolution.

In the conventional apparatus constructed as shown in FIGS. 14 and 15, when the absolute angular position of the rotating shaft 3 is detected, the random pattern on the track 2A is 8 bits. Is rotated, and one address is output by the arithmetic processing circuit 50 at the time when it is rotated by eight pitches from the first position, so that the first position is obtained at this time.

After that, every time it rotates by one pitch,
The position is obtained from the latest eight pitch patterns stored in the arithmetic processing circuit 50.

[0018]

As described above, the conventional angle detecting device detects the absolute angle based on the signal pattern corresponding to the eight pitches of the magnetized pitch P, as described above. In addition to the need for continuous rotation in one direction for 8 pitches, it is necessary to magnetize a complex M-sequence random pattern on the track 2A on the magnetic drum 4, and the arithmetic processing circuit 50 supports absolute angular resolution. However, there is a problem in that the matching of the number of bits required becomes necessary, and the processing becomes complicated.

The present invention has been made to solve the above-mentioned problems, and has a relatively simple magnetizing structure and signal processing, so that the absolute position of the rotating shaft can be maintained even when the magnetized track on the magnetic drum is stationary. The purpose of the present invention is to obtain an angle detection device that has a configuration capable of detecting a rotation angle (electrical angle of a motor), detects a high-resolution incremental angle signal, and can detect an absolute angle from a moment when power is supplied to a sensor system. I do.

[0020]

According to a first aspect of the present invention, there is provided an angle detecting device comprising: a magnetic drum supported on a rotating shaft driven by a motor;
A first track NS-magnetized at the same pitch, a second track NS-magnetized at a second equal pitch wider than the first equal pitch on the outer peripheral side surface of the magnetic drum, A magnetic sensor fixedly disposed so as to face the second track; and a processing circuit for processing a detection signal from the magnetic sensor to obtain a rotation angle of the rotation shaft, wherein the magnetic sensor includes first and second magnetic sensors. Output as detection signals the first and second magnetic field signals that change at a constant period in accordance with the rotation of the track, and the arithmetic processing circuit outputs the first and second magnetic field signals based on the phase difference between the first and second magnetic field signals. In addition to detecting the absolute rotation angle, a minute relative rotation angle of the rotation shaft is detected based on only one of the first and second magnetic field signals.

According to a second aspect of the present invention, in the first aspect, the magnetic sensor includes an A-phase sensor and a B-phase sensor that are 90 ° out of phase with respect to the rotation angle of the first track. It detects a signal and C-phase and D-phase signals that are 90 ° out of phase with respect to the rotation angle of the second track.

According to a third aspect of the present invention, in the second aspect, the arithmetic processing circuit is configured to square the difference or sum of the signals of the A-phase and the C-phase with the B-phase and the B-phase. The absolute rotation angle is detected based on the sum of the difference or sum of the D-phase signals and the squared value.

According to a fourth aspect of the present invention, in the second aspect, the arithmetic processing circuit compares the signals of the A phase and the B phase with a first reference value, and outputs the signals of the A phase and the B phase.
By dividing the first equal pitch into eight based on the magnitude relationship between the signals of the phases, the phase of the first track can be detected with a resolution of 1/8 of the first equal pitch, and the C and D phases can be detected. Is compared with a second reference value, and the second equal pitch is divided into eight based on the magnitude relationship between the C-phase and D-phase signals, so that the resolution is 1/8 of the second equal pitch. To detect the phase of the second track and set the motor current based on the phase difference between the first and second tracks.

According to a fifth aspect of the present invention, in the second aspect, the arithmetic processing circuit compares each signal of the A-phase and the B-phase with a first reference value, and By dividing the equal pitch into four, 1/4 of the first equal pitch
While detecting the phase of the first track with a resolution of
By comparing each signal of the C phase and the D phase with the second reference value and dividing the second equal pitch into four, the phase of the second track can be changed with a resolution of 1/4 of the second equal pitch. This is to detect and set the motor current from the phase difference between the first and second tracks.

According to a sixth aspect of the present invention, in the angle detecting device according to any one of the second to fifth aspects, the magnetic sensor includes a magnetoresistive element, and the arithmetic processing circuit includes a magnetoresistive element. A midpoint potential compensating means for compensating the midpoint potential, wherein the midpoint potential compensating means is configured such that the average value of the A-phase signal during the rotation of the rotation axis by the first equal pitch, and the rotation axis has the The midpoint potential of the magnetoresistive element is detected from the average value of the B-phase signal during the rotation of one equal pitch, and the midpoint potential is corrected to a reference value.

According to a seventh aspect of the present invention, in the sixth aspect, the arithmetic processing circuit includes a detection PWM modulation circuit, and the detection PWM modulation circuit includes a detection PWM detection circuit. The signal is input to the midpoint potential compensating means after the PWM modulation.

According to an eighth aspect of the present invention, in the angle detection device according to the sixth or seventh aspect, the arithmetic processing circuit includes a reference value PWM modulation circuit, and the reference value P
The WM modulation circuit generates a reference value by PWM modulating the midpoint potential obtained by the midpoint potential compensating means.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, Embodiment 1 of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view schematically showing Embodiment 1 of the present invention, and the same components as those described above are designated by the same reference numerals and the detailed description thereof will be omitted.

In FIG. 1, reference numeral 1 denotes a first track formed on the outer peripheral side surface of the magnetic drum 4, which is NS-magnetized at a first equal pitch. Reference numeral 2 denotes a second track formed on the outer peripheral side surface of the magnetic drum 4, which is NS-magnetized at a second equal pitch wider than the first equal pitch.

Hereinafter, the first and second tracks 1 and 2
Are simply referred to as "tracks", respectively. In this case, each of the tracks 1 and 2 is magnetized in the rotation direction of the magnetic drum 4, and the magnetic sensor 5 changes the first and second tracks, which change at a constant cycle according to the rotation of each of the tracks 1 and 2. A magnetic field signal is output as a detection signal.

The magnetic sensor 5 is fixedly arranged so as to face the tracks 1 and 2 on the magnetic drum 4 in the same manner as described above (see FIG. 14). Although not shown here, the magnetic sensor 5 is connected to an arithmetic processing circuit similar to that described above, and processes the detection signal from the magnetic sensor 5 to obtain the rotation angle of the rotating shaft 3. Has become.

That is, the arithmetic processing circuit detects the absolute rotation angle of the rotating shaft 3 based on the phase difference between the first and second magnetic field signals corresponding to each of the tracks 1 and 2, and detects the first or second rotation angle. A small relative rotation angle of the rotating shaft 3 is detected based on only one of the magnetic field signals.

Further, the magnetic sensor 5 has A-phase and B-phase signals that are 90 degrees out of phase with respect to the rotation angle of the track 1 and C signals that are 90 degrees out of phase with respect to the rotation angle of the track 2. Phase and D-phase signals.

FIG. 2 is an explanatory diagram schematically showing the relative phase relationship between each of the tracks 1 and 2 and the magnetic sensor 5 in FIG.
In FIG. 2, P1 and P2 are the magnetization pitches of the tracks 1 and 2, respectively.

R11a to R14a, R11b to R14
b, R21c to R24c and R21d to R24d correspond to the magnetoresistive elements in the magnetic sensor 5, and are shown in relation to the magnetization pitches P1 and P2 of the tracks 1 and 2.

The magnetoresistive elements R11a to R14a,
R11b-R14b, R21c-R24c, R21d-
In R24d, the first suffix following “R” corresponds to tracks 1 and 2, the second suffix corresponds to the number of elements, and the third suffix is A phase, B phase, C phase, D Corresponds to the phase.

Here, the magnetic resistance elements R11a to R1a in the magnetic sensor 5 correspond to the track 1 having the magnetization pitch P1.
4a, R11b to R14b are opposed to each other, and the magnetization pitch P2
Tracks 2 of the magnetic resistance elements R21a to R24
a, R21b to R24b are opposed to each other.

The magnetization pitch P2 of the track 2 is set wider than the magnetization pitch P1 of the track 1. As a result, the phase relationship between the magnetization position of the track 1 and the magnetization position of the track 2 changes depending on the absolute position.

For example, at the left end in FIG. 2, the phase relationship between track 1 and track 2 is the same, but as it moves to the right in the figure, the magnetization position of track 2 becomes It can be seen that it shifts to the right side.

Here, the diameter of the magnetic drum 4 is about 25.8.
When the number of poles of the track 1 is set to “108” and the number of poles of the track 2 is set to “104”, the magnetization pitch P
1, P2 are about 0.75 mm and about 0.78 m, respectively.
m.

At this time, since the difference in the number of poles of each track 1 and 2 is "4", the phase of each track 1 and 2 coincides four times while the rotation shaft 3 makes one rotation. Therefore, when used for an eight-pole (four-pole pair) motor, its electrical angle is four times the mechanical angle, so that an absolute electrical angle (corresponding to an absolute rotation angle) can be detected.

FIG. 3 shows a magnetic resistance element (M) in the magnetic sensor 5.
FIG. 3 is a circuit connection diagram illustrating a configuration example of an R element), and illustrates a full bridge configuration including four magnetoresistive elements as an example.

Here, four sets of magnetoresistive elements R11a to
R14a, R11b to R14b, R21c to R24c,
Since the same is applied to all of R21d to R24d, only one full bridge is typically shown.

Therefore, in FIG. 3, the first subscript (tracks 1, 2) following "R" indicating each magnetoresistive element is used.
) And the third subscript (corresponding to phase A, phase B, phase C, phase D) are indicated by “で”, respectively.

E is a DC power supply for supplying power to the full bridge composed of the magnetoresistive elements R ○ 1 ○ to R ○ 4 ○. e1, e
Reference numeral 2 denotes an output terminal of the magnetic sensor 5, which is drawn out in pairs for each full bridge.

Next, the operation according to the first embodiment of the present invention shown in FIG. 1 will be specifically described with reference to FIGS.

First, each of the magnetoresistive elements RＲ1 ○ to R ○ 4 ○
The relationship between the magnetic resistances of the tracks 1 and 2 is set as shown in FIG.
Are の of the corresponding magnetization pitches P1 and P2, respectively.
Are arranged at intervals.

Therefore, as shown in FIG. 2, when the magnetoresistive element R ○ 1 ○ is opposed to one end (N pole) of the magnetized pitch, the magnetoresistive element R ○ 3 ○ is connected to the other end (Negative pole) of the magnetized pitch. S
Pole), the magnetoresistive element R ○ 2 ○ and the magnetoresistive element R
４4 ○ is located at the center of the magnetized pitch.

Since the resistance value of each magneto-resistive element decreases when a magnetic field is applied, the magneto-resistive elements R ○ 1Ｒ and R ○
At the center of the magnetized pitch where the resistance value of ３3 な り is small and no magnetic field is generated, the magnetoresistive elements R ○ 2 ○ and R
The resistance value of ○ 4 ○ increases.

Therefore, when a full bridge as shown in FIG. 3 is formed, the potential of the output terminal e1 increases and the potential of the output terminal e2 decreases.

On the other hand, after that, when the magnetic drum 4 rotates and the track 1 advances by １ ／ of the magnetization pitch P1, the magnetic field strength of the magnetoresistive elements RＲ1１ to R ○ 4 ○ becomes equal,
The potentials of the output terminals e1 and e2 become equal.

Track 1 is 1/1 / magnetized pitch P1.
When the position is advanced by 2, the magnetoresistance elements R1 and R3 move to the center of the magnetized pitch P1, and the potential of the output terminal e1 decreases and the potential of the output terminal e2 increases.

Further, when the track 1 advances by the magnetization pitch P1, the magnetic fields of the magnetoresistive elements R1 and R3 become strong, and the potentials of the output terminals e1 and e2 return to the initial state.

In this manner, a signal that changes at a cycle corresponding to the magnetization pitch can be extracted as a potential difference between the output terminals e1 and e2. The A phase and the B phase are shifted by 1/4 of the magnetization pitch P1 of the track 1, and the A phase signal and the B phase signal are shifted by 90-phase from each other.

Similarly, the C phase and the D phase are shifted by 1/4 of the magnetization pitch P2 of the track 2, and the C phase signal and the D phase signal are shifted by 90-phase from each other.

The period of the detection signal from the track 1 is slightly shorter than the period of the detection signal from the track 2, and the amount of deviation between them, that is, the phase difference, corresponds to the absolute position of the rotating shaft 3 as described above. .

Although the full bridge of the magnetoresistive element is formed here as shown in FIG. 3, a half bridge may be formed.

That is, the magnetoresistive element R ○ 3 ○ shown in FIG.
And R ○ 4 ○ are omitted, and a half bridge is constituted only by the magnetoresistive elements R ○ 1 ○ and R ○ 2 ○, and the output terminal e1
You may use only.

As described above, the magnetic sensor 5 is fixedly arranged so as to face the rotating magnetic drum 4, and generates a magnetic field signal having a constant period corresponding to the magnetization patterns of the equal pitches P1 and P2 on the tracks 1 and 2. By detecting the absolute electrical angle from the phase difference between the magnetic field signals, the absolute rotation angle (the absolute electrical angle of the motor 7) can be detected even when the rotating shaft 3 is stationary.

At this time, signals of phase A and phase B (Lissajous rotation) which are 90 ° out of phase with each other with respect to the rotation angle of the track 1 are detected. -The phase-shifted C-phase and D-phase signals are detected, and the arithmetic processing of FIG.
The absolute rotation angle can be detected from the sum of the difference or sum of the phase signal outputs and the square of the difference or sum of the B-phase signal output and the D-phase signal output.

The minute relative rotation angle (incremental angle) can be detected from the output of the magnetic sensor corresponding to one of the track 1 and the track 2.

Therefore, even when the motor is started,
From the state where the motor shaft is stationary, the rotation can be started immediately and smoothly, and the magnitude of the motor torque can be controlled from the start.

Embodiment 2 In the first embodiment, the specific detection processing of the absolute rotation angle in the arithmetic processing circuit is not described, but the value obtained by squaring the difference or the sum of the signals of the A phase and the C phase and the B phase Alternatively, the absolute rotation angle may be detected based on the sum of the difference or the sum of the signals of the D phase and the value obtained by squaring the difference.

FIG. 4 is a circuit diagram showing the structure of the arithmetic processing circuit according to the second embodiment of the present invention. In FIG. 4, reference numeral 6 denotes an operational amplifier connected to the magnetic sensor 5,
They are provided in parallel corresponding to the phases A to D, and output amplified voltages va to vd, respectively.

Reference numeral 7 denotes a motor including a magnetic drum 4, a magnetic sensor 5, and an operational amplifier 6. Reference numeral 8 denotes an ECU connected to the motor 7, which constitutes a main body of the arithmetic processing circuit, and includes an A / D converter 9 and a microcomputer 10.

The A / D converter 9 A / D converts the output voltages va to vd of the operational amplifiers 6 and takes them in.
Enter 0.

In FIG. 4, the motor 7 and the ECU 8
In order to reduce the influence of noise when the sensors are spaced apart from each other, an operational amplifier 6 is provided in the motor 7 so that the output voltage of the magnetic sensor 5 is amplified and input to the ECU 8.

The potential difference between the output terminals e1 and e2 of the magnetic sensor 5 can be made sinusoidal with respect to the rotation angle position by devising the magnetization pattern and the arrangement of the magnetoresistive elements.

Therefore, if the rotation angle is set to θ in correspondence with the output voltages va to vd of the operational amplifiers 6 of the A to D phases,
The following equation (1) holds.

[0070]

(Equation 1)

In the equation (1), n1 and n2 are the number of poles of the tracks 1 and 2 (the number of magnetized patterns).

The phase A of track 1 and the phase C of track 2
The difference voltage between the phases is ve, the difference voltage between the B phase of track 1 and the D phase of track 2 is vf, the A phase of track 1 and track 2
The following equation (2) is obtained from the above equation (1), where vg is the sum voltage of the C phase and Vh is the sum voltage of the B phase of the track 1 and the D phase of the track 2.

[0073]

(Equation 2)

In equation (2), the term [｛(n1-
n2) / 2} .theta.] is set to ". +-. 2", a trigonometric function of the absolute mechanical angle .theta. is obtained. Also,
If “n1−n2” is multiplied by the number of motor poles, a trigonometric function of the absolute electric angle θ can be obtained.

If the sum of the squares of the difference voltages ve and vf and the sum of the squares of the sum voltages vg and vh are calculated to extract only the term on the right side, the following equation (3) is obtained.

[0076]

[Equation 3]

In the equation (3), “hat 2” represents a square. From Expression (3), the rotation angle θ is obtained as in Expression (4) below.

[0078]

(Equation 4)

In equation (4), “vg ² + v
When “h ² ” becomes sufficiently small, the following equation (5) may be used.

[0080]

(Equation 5)

Here, the A / D converter 9 is provided in the arithmetic processing circuit associated with the magnetic sensor 5, but the A / D converter 9
Alternatively, a PWM modulation circuit may be provided, the output voltage of the magnetic sensor 5 is PWM-modulated, and the pulse width of the PWM signal is detected by a digital timer.

As described above, based on the instantaneous values of the A-phase to D-phase output signals, the difference or sum of the A-phase and C-phase signals is calculated by 2
And the difference or sum of the B-phase and D-phase signals by 2
By detecting the absolute electrical angle (absolute rotation angle × the number of motor pole pairs) based on the value added to the raised value, the motor 7 can be smoothly started to rotate from the stationary state, as described above.

Embodiment 3 In the second embodiment, the specific processing of detecting the absolute electrical angle required for starting the motor 7 is not described. However, the absolute electrical angle is detected by the following digital processing, and the first magnetization pitch is detected. P1 of 1
The phase of track 1 may be detected with a resolution of / 8.

FIG. 5 is a circuit diagram showing an arithmetic processing circuit according to Embodiment 3 of the present invention, in which the output signal of the magnetic sensor 5 is digitally processed. In FIG. 5, reference numeral 16 denotes a digital signal generation circuit corresponding to the A phase and the B phase, which includes comparators 11 to 14 and an operational amplifier 1
And 5.

The comparators 11 to 14 generate digital signals D0 to D3 and input them to the ECU 8. 17 is C
Digital signal generation circuit corresponding to the phase and the D phase,
It has the same circuit configuration as the digital signal generation circuit 16.

In this case, the arithmetic processing circuit including the comparators 11 and 12 compares each of the A-phase and B-phase signals with a first reference value (ground potential), and compares the magnitude of each of the A-phase and B-phase signals. By dividing the first magnetized pitch P1 into eight based on the above, the phase of the track 1 is detected with a resolution of 1/8 of the magnetized pitch P1.

The arithmetic processing circuit including the comparators 13 and 14 compares each signal of the C phase and the D phase with a second reference value (ground potential, output voltage of the operational amplifier 15), and outputs the signals of the C phase and the D phase. Second based on the magnitude relationship of each signal
By dividing the magnetized pitch P2 into eight, the phase of the track 2 is detected with a resolution of 1/8 of the magnetized pitch P2.

Thus, the arithmetic processing circuit sets the current of the motor 7 based on the phase difference between the tracks 1 and 2.

The comparators 11 and 12 in the digital signal generation circuit 16 compare the A-phase and B-phase output voltages with the ground potential, respectively, and convert them into digital signals D0 and D1 of "H" and "L" levels. I do.

The comparator 13 compares the A-phase and B-phase output voltages and converts them into a digital signal D2. Further, the comparator 14 compares the A-phase output voltage with the B-phase output voltage inverted by the operational amplifier 15, and converts the output voltage into a digital signal D3.

Similarly, digital signals are generated from the digital signal generation circuit 17 for the C and D phases.

First, assuming that the phases of the A-phase and B-phase output voltages va and vb are φ, the phase φ is expressed by the following equation (6).

[0093]

(Equation 6)

The following relationship exists between the phase φ and the rotation angle θ. φ = θ / n where n is the number of magnetized patterns. The relationship between the phase φ and each digital signal at this time is shown in the waveform diagram of FIG.

In FIG. 6, the output voltage va changes by one period while the phase φ advances by 2π, but the digital signals D0 to D3 from the digital signal generation circuit 16
The phase changes by dividing a period of a into eight equal parts.

Therefore, as shown in FIG. 6, if the exclusive OR of the digital signals D0 and D1 is obtained, the output voltage va
A digital signal that changes to “H” or “L” in a half cycle of is obtained. Similarly, if the exclusive OR of the digital signals D2 and D3 is calculated, a digital signal advanced by 90-phase with respect to the exclusive OR of the digital signals D0 and D1 is obtained.

As described above, by taking the exclusive OR, a digital signal obtained by multiplying the output voltages va and vb by 8 is obtained. Hereinafter, high-resolution angle detection can be realized by performing an incremental process on the digital signal multiplied by 8 using an up / down counter.

Next, a specific process for detecting the absolute electrical angle from the digital signal multiplied by 8 will be described. First, as is well known, the following relationship exists between the number of pole pairs p of the motor 7 and the absolute electric angle θe. θe = θ / p

Here, if the difference between the numbers n1 and n2 of the magnetization patterns of the tracks 1 and 2 is made equal to the number of pole pairs p, while the absolute electric angle θe changes from 0 to 2π, the tracks 1 and 2
, The phase difference between the phases φ1 and φ2 detected is changed by 2π.

This relationship is shown in detail in the waveform diagram of FIG. In FIG. 7, a digital signal obtained by multiplying the phase φ by 8 is indicated by ψ. For example, “$ 1” in FIG.
When −ψ2 ”is 0, the absolute electric angle θe is −π / 4 to π
/ 4.

Each time “ψ1−ψ2” increases by “1”, the range of the corresponding absolute electric angle θe moves by π / 4. “Ψ1-ψ2” takes a value from “0” to “7”,
The range of the absolute electrical angle θe corresponding to each value of “0” to “7” is indicated by the symbols “A” to “H”, respectively.

On the other hand, when the motor 7 is a three-phase motor, the generated torque is represented by the following equation (7).

[0103]

(Equation 7)

In the equation (7), the suffixes u, v, w
Represents the u, v, w phases of the three-phase motor, and the torque T of each phase
u, Tv, Tw are represented by the following equation (8).

[0105]

(Equation 8)

In the equation (8), iu, iv, i
w is the u, v, w phase current. The above equation (7),
FIG. 8 shows the state of generation of the torques Tu, Tv, Tw from (8).

In FIG. 8, each curve shows the case where each phase current is held at a constant current value i0 (that is, iu = iv = i
(when w = io)). Here, To = K · io.

As is apparent from the above equation (7) and FIG. 8, the value of “0” to “7” of “ψ1-ψ2” is
In order to obtain a torque of o to √2 · To, a current of each phase may be given as shown in Table 1 below.

[0109]

[Table 1]

For example, in the region indicated by the symbol “A” in Table 1, the generated torque “Tw-Tv” (reverse polarity waveform with reference to the broken line in FIG. 0), the maximum value (= √3 · To) is obtained, and (√3 / √2) · To is obtained at both ends (θe = aπ / 4) of the area A.

Therefore, if the generated torque “Tw−Tv” is multiplied by (√2 / √3), in the range (A), ToＴ√2
・ To torque is obtained.

In the area indicated by the symbol "b" in Table 1,-
The sum of Tw and (−Tw + Tv) / √3 is given by ｛−√2 / 2s
in (5π / 12)} times, the center of the area b (θe =
(π / 4) takes the maximum value (= √2 · To), and becomes a sine wave having To at both ends (θe = 0, π / 2) of the area b.

That is, from the following equation, by setting the current values as shown in Table 1, a torque of To√√2 · To can be obtained. sin (5π / 12) = (1 + √3) / 2√2

Therefore, assuming that the torque command is (1 + ／ 2) / 2To using Table 1, it is possible to realize torque control based on the value of “ψ1-ψ2” with an accuracy of ± 20.7%. it can.

Further, the motor 7 rotates and the magnetic drum 4
Are rotated by the magnetization pitch, two regions can be distinguished. That is, for example, when the object that was stationary at θe = 0 rotates by θ / n1, “ψ1−ψ2”
Changes from “0” to “1”.

Therefore, it can be determined that the rotation axis 3 is in the common area of the area A and the area B. At this time, the range of the rotating shaft 3 is limited to the range of π / 4 in electrical angle, so that the torque setting accuracy can be further improved.

That is, if the current is set so as to be centered on the maximum value within a limited range of π / 4, the maximum value is obtained at both ends by the following equation. 1 / {1-sin (3π / 8)} = 1 / 0.9239

Here, if the torque command is set to the average value of the maximum value and the values at both ends, the torque error can be reduced to ± 4.1%.

Further, the absolute electric angle θe of the motor 7 becomes “π /
4 + pθ / n1, the value of “ψ1−ψ2” becomes “2”. When the value of “ψ1−ψ2” becomes “2” for the first time, the absolute electrical angle θe becomes “π / 4 + p”.
θ / n1 ”. That is, the absolute electrical angle θe can be set with a resolution of “pθ / n1”.

Although the case where the first absolute electrical angle θe is “0” has been described here, the same determination can be made even when the initial angle is arbitrary. For example, when the first angle is θe = −π / 4, “{1-ψ}
Since the value of “2” is “6”, it can be determined that it is in the area “G”.

Thereafter, when the electric angle is rotated in the negative direction by pθ / n1, the value of “ψ1−ψ2” becomes “5”, and it is determined that the area “g” and the area “f” are in a common area. Can be.

Further, when the electric angle is rotated by -π / 4, the value of “ψ1-ψ2” becomes “4”, and the absolute electric angle θ
e can be determined to be “−3π / 4−pθ / n1”.

As described above, by performing the rotation angle detection by digital signal processing, the A / D converter 9 (see FIG. 4) becomes unnecessary, and is less affected by noise. can do.

That is, the magnetization pitch P1 of the track 1 is divided into eight based on a comparison between the A-phase and B-phase signal outputs and the reference value (the magnitude relationship between the A-phase and B-phase signal outputs) and The phase of the track 1 is detected at a resolution of 1/8 of P1, and the track 2 is similarly detected based on a comparison between the C-phase and D-phase signal outputs and the reference value (the magnitude relationship between the C-phase and D-phase signal outputs). Is divided into eight, the phase of track 2 is detected with a resolution of 1/8 of the magnetization pitch P2, and the motor current is set from the difference between the phase of track 1 and the phase of track 2. it can.

Embodiment 4 In the third embodiment, the sine wave output of the magnetic sensor 5 is multiplied by 8, but may be multiplied by 4. FIG. 9 is a circuit configuration diagram showing an arithmetic processing circuit according to Embodiment 4 of the present invention, showing a case where the sine wave output of the magnetic sensor 5 is quadrupled.

In FIG. 9, the same components as those described above (see FIG. 5) are denoted by the same reference numerals, and detailed description is omitted. In this case, the comparators 13 and 14 that output the digital signals D2 and D3 described above (see FIG. 5), the operational amplifier 15, and the digital signal generation circuit 17 are not required.

The arithmetic processing circuit shown in FIG.
By comparing each signal of the phase with a first reference value (ground potential) and dividing the first magnetized pitch P1 into four, the phase of the track 1 is detected with a resolution of 1/4 of the magnetized pitch P1. I do.

Further, each of the C-phase signal and the D-phase signal is compared with a second reference value (ground potential), and the second magnetized pitch P1 is divided into four to obtain a quarter of the magnetized pitch. The phase of the track 2 is detected with the resolution, and the current of the motor 7 is set from the phase difference between the tracks 1 and 2.

In FIG. 9, similarly to the comparators 11 and 12 for the A and B phases, the C and D phases are also
Digital signals D4 and D5 are output from comparators 21 and 22.
Is generated.

[0130] Each digital signal D is supplied to the ECU 8.
0, up / down counter 23 that operates in response to D1
Is built-in. The microcomputer 10 in the ECU 8 captures the digital signals D0, D1, D4, and D5, and detects the high-resolution rotation angle by the up / down counter 23 based on the counter signal that has been subjected to the incremental processing.

Next, the operation of detecting the absolute electrical angle based on the quadrupled digital signal according to the fourth embodiment of the present invention shown in FIG. 9 will be described with reference to the waveform diagram of FIG.

In FIG. 10, the same components as those described above (see FIG. 7) are denoted by the same reference numerals. As described above, if the difference between the numbers n1 and n2 of the magnetization patterns of the tracks 1 and 2 is p, the phase φ1 detected from the tracks 1 and 2 while the absolute electric angle θe changes from 0 to 2π. , Φ
The difference of 2 will change by 2π.

A digital signal obtained by multiplying the phase φ by 4 in relation to the above phase relationship is represented by Ω in FIG. For example, when “Ω1−Ω2” is “0”, the absolute electric angle θe is −π / 4 to π / 4.

Here, every time “Ω1−Ω2” is incremented by “1”, the range of the corresponding absolute electrical angle θe moves by π / 4. Therefore, "Ω1-Ω2"
Takes a value in the range of “0” to “3”.

In FIG. 10 as well (FIG. 7), the range of the absolute electric angle θe is represented by the symbols “b”, “d”,
"F" and "J" are shown. That is, Ω1-Ω2
= 0 corresponds to the regions “H” and “B”, and Ω1−Ω2 = 1
Corresponds to the regions “b” and “d”, and Ω1−Ω2 = 2 is
Ω1−Ω2 = 3 correspond to the regions “d” and “f”, respectively.

Since the range of these electrical angles is π, the magnitude of the torque cannot be set, but the sign of the torque, that is, the direction can be controlled. Here, as is apparent with reference to FIG.
Ω2 = 0 region “h” and b, − (− Tw + T
v) is positive.

The above relationships are summarized in Table 2 below.
become that way.

[0138]

[Table 2]

The direction of the torque can be controlled by controlling the sign of the phase current as shown in Table 2. When the motor 7 rotates and the magnetic drum 4 rotates by the magnetization pitch, the range of the corresponding electrical angle region can be limited to 限定.

For example, when the object that was stationary at θe = 0 rotates by θ / n1, the value of “Ω1−Ω2” becomes
Since it changes from “0” to “1”, it can be determined that the rotating shaft 3 is in the area “b”.

At this time, the range of the rotation axis 3 is π / electrical angle.
2, the setting accuracy of the torque can be further improved. That is, the values of “b”, “d”, “f”, and “h” in Table 1 described above may be used.

The torque setting accuracy at this time is in the range of To to √2 · To, as in the third embodiment. Further, when the motor 7 rotates and passes through a boundary between the regions, for example, a switching angle between the regions “b” and “d”, the absolute electric angle is changed to the resolution of pθ / n1 as in the third embodiment. Can be set with.

As described above, immediately after the start, the relationship shown in Table 2 is used.
The motor 7 can be driven smoothly by setting the absolute electric angle at the boundary between the areas by using the values of d, f, and h.

That is, based on the comparison between the A-phase and B-phase signal outputs and the reference value, the magnetization pitch P1 of the track 1 is set to 4
The track 1 is divided and the phase of the track 1 is detected at a resolution of 1/4 of the magnetization pitch P1. Similarly, the magnetization pitch P2 of the track 2 is determined based on the comparison between the C-phase and D-phase signal outputs and the reference value.
Is divided into four, the phase of track 2 is detected with a resolution of 1/4 of the magnetization pitch P2, and the phase of track 1 and
The motor current can be set from the difference from the phase.

Further, the direction of the generated torque of the motor 7 can be set at the time of startup by the digital signal processing, and the absolute electric angle of the motor 7 can be detected after the rotation of the magnetization pitches P1 and P2.

Furthermore, in this case, the third embodiment is used.
Compared with (see FIG. 5), the number of comparators is four and the number of operational amplifiers is two, so that the processing circuit can be simplified, the reliability can be improved, and the cost can be reduced.

Embodiment 5 FIG. It should be noted that the first to the above embodiments
In No. 4, the midpoint potential compensating means for compensating the midpoint potential of the magnetoresistive element constituting the magnetic sensor 5 is not specifically mentioned, but may be configured in the microcomputer 10 as follows. .

FIG. 11 is a circuit diagram showing an arithmetic processing circuit according to the fifth embodiment of the present invention. The same components as those described above (see FIGS. 4, 5, and 9) are denoted by the same reference numerals. I have.

In FIG. 11, the microcomputer 1 in the ECU 8
0 has a D / A converter 24 for outputting a compensation voltage of the midpoint potential of the magnetoresistive element, in addition to the A / D converter 9 and the up / down counter 23 described above.

The ECU 8 also includes comparators 11C and 12C for converting the A-phase and B-phase detection signals into digital signals.
Having. The comparators 11C and 12C are connected to the microcomputer 1
In relation to 0, a midpoint potential compensating means is configured.

The output signals corresponding to each phase from the magnetic sensor 5 are amplified by the operational amplifier 6 and then taken into the microcomputer 10 via the A / D converter 9.

The microcomputer 10 is a software / software (S / W)
The midpoint potential is detected by the processing, and a compensation potential is generated from the D / A converter 24 so as to compensate for the deviation of the midpoint potential, and is input as a reference (reference value) of the comparators 11C and 12C.

That is, the microcomputer 10 in the arithmetic processing circuit
And the D / A converter 24 constitute a midpoint potential compensating means for compensating for the midpoint potential of the magnetoresistive element. Specifically, while the rotating shaft 3 rotates by the magnetization pitch P1. From the average value of the A-phase signal and the average value of the B-phase signal while the rotating shaft 3 rotates by the magnetization pitch P1. To be corrected.

Here, the magnetic sensor 5 shown in FIG.
The necessity of compensating the midpoint potential of the magnetoresistive element will be described with reference to the equivalent circuit of FIG. In FIG. 3, if the magnetoresistance elements R ○ 1 ○ and R ○ 2 ○ are equal,
The potential of the output terminal e1 is の of the DC power supply E.

Similarly, the magnetoresistive elements R ○ 4 ○ and R ○ 3 ○
If they are equal, the potential of the output terminal e2 is の of the DC power supply E. As described above, the potentials of the output terminals e1 and e2 are １ ／ of the DC power supply E, and thus are called midpoint potentials.

However, due to variations in the work of the magnetoresistive element (MR element), the magnetoresistive element R
And R ○ 2 ○ have slightly different values. For example, when E = 5V, the potentials of the output terminals e1 and e2 are 2.47V to 2..
Variation may occur in the range of 53V.

Therefore, in such a case, FIG.
It is necessary to compensate for the midpoint potential using the circuit configuration shown in FIG. Next, the compensation operation of the midpoint potential using the S / W processing of the microcomputer 10 according to the fifth embodiment of the present invention shown in FIG. 11 will be described with reference to the flowchart of FIG.

Here, the A-phase output is set on the x-axis, the B-phase output is set on the y-axis, and Lissajous's figure is used.
Considering the case of drawing e), since the output waveform of each phase A and B is a sine wave, the Lissajous is a circle.

However, the center of the circle is set at the origin when there is no deviation of the midpoint potential, so that the deviation of the midpoint potential is the difference between the center of the circle and the origin. In FIG. 12, first, the initial output immediately after the start is set to point 0 (vao, vbo) (step 1), and the A-phase and B-phase output voltages (va, vb).
Is imported (step 2).

Subsequently, the difference between the captured value and the initial value, that is, the output voltage (va, vb) and the point 0 of the initial output
It is determined whether the distance Δvo to (vao, vbo) is greater than a predetermined value d (step 3). If it is determined that Δvo ≦ d (that is, no), the process returns to step 2 and the next output voltage ( va, vb).

In step 3, Δvo> d
If it is determined to be “yes”, the output voltage value (va, vb) captured at that point is set to the point 1 (va1, v
b1) (step 4).

Next, the output voltage (va, vb) and the point 1 (v
a1, vb1) is determined to be greater than a predetermined value d and the distance Δvo to the point 0 (vao, vbo) is greater than 1.5d (step).
5), Δv1 ≦ d or Δvo ≦ d (ie, n
If it is determined to be o), step 5 is repeated to enter a standby state.

In step 5, Δv1> d,
If it is determined that Δvo> d (that is, yes), the output voltage values (va, vb) captured at that point in time
Is set to point 2 (va2, vb2) (step 6).

Thereafter, after setting the counter value k to "3", the output voltages (va, vb) are fetched in the same manner as in step 2 (step 7), and the points 1 and 0 in step 5 are respectively set to points k, The determination process (ste
p8) and a setting process (step 9) in which point 2 in step 6 is set to point k are repeatedly executed.

Next, the output voltage values (va, v
b) and the distance Δvo between the point 0 (vao, vbo) is d / 2
Is determined (step 10), and Δvo ≧
If it is determined to be d / 2 (that is, no), the counter value k is incremented to k + 1, the process returns to step 7, and s
Steps 7 to 10 are repeated.

On the other hand, in step 10, Δvo <d
If it is determined to be / 2 (that is, yes), it is determined that the Lissajous figure has made one rotation and returned to its original state, and the Lissajous capture is terminated.

That is, after setting the counter value k to the number n of the magnetization patterns, each point, that is, the point 0 (vao, vb
o), point 1 (va1, vb1),..., point n (va
The center (xo, yo) of the Lissajous is determined from the average value for each coordinate of (n, vbn) (step 11).

At this time, the center of the Lissajous (xo, y
The coordinates of o) are obtained from the following equation (9).

[0169]

(Equation 9)

Finally, the microcomputer 10 compares the center (xo, yo) of the Lissajous obtained from equation (9) with the A-phase and B-phase comparators 11C through the D / A converter 24.
Output to the reference input terminal of 12C.

As described above, the midpoint potential of the magnetoresistive element is detected from each average value of the A-phase and B-phase signals while the rotating shaft 3 rotates by the magnetization pitch P1, and the midpoint potential is set to the reference value. , The midpoint potential can be automatically compensated while the sensor is operating.

Further, when compensating for the midpoint potential, it is not necessary to adjust the trimmer of the variable resistor, and the angle detector can be manufactured at low cost.

Embodiment 6 FIG. In the fifth embodiment, the microcomputer 10 captures the detection signal of each phase via the A / D converter 9 and outputs the correction reference value of the midpoint potential compensating means via the D / A converter 24. However, the PWM-modulated detection signal may be taken in through the digital input port, and the digital output port may be used as the compensation output section of the midpoint potential compensating means.

FIG. 13 is a circuit diagram showing an arithmetic processing circuit according to a sixth embodiment of the present invention. The arithmetic processing circuit fetches a PWM-modulated digital signal and outputs a PWM signal as a compensation output (reference value) of a midpoint potential compensating means. The case where the digital signal obtained is used is shown. 13, the same components as those described above (see FIG. 11) are denoted by the same reference numerals.

In this case, the microcomputer 10 in the ECU 8
In addition to the above-mentioned up / down counter 23, a digital input port 9D for taking in a PWM modulation signal and a digital output port 25 for outputting a compensation voltage reference value of the midpoint potential of the magnetoresistive element after PWM modulation are provided. Have.

The ECU 8 is connected to the digital output port 2
5, and a detection PWM modulation circuit for converting the detection signal of each phase into a PWM signal and inputting it to the digital input port 9D.

The detection PWM modulation circuit is composed of a carrier signal generation circuit 28 for generating a carrier signal, and a comparator 29 for each phase which uses the carrier signal as a reference input. Is PWM-modulated and input to the midpoint potential compensating means in the microcomputer 10.

The microcomputer 10 has a PWM for reference value.
A PWM circuit for a reference value, which includes a modulation circuit (not shown), converts the midpoint potential obtained by the midpoint potential compensating means to P
After the WM modulation, the signal is generated as a reference value for the comparators 11C and 12C via a low-pass filter. The low-pass filter includes a resistor 26 and a capacitor 27.

The microcomputer 10 constituting the midpoint potential compensating means
Converts a digital signal (PWM signal) having a duty ratio corresponding to a compensation signal (center of Lissajous) xo, yo into a digital output port 2 instead of the D / A converter 24 described above.
5 is output.

After the output voltage from the digital output port 25 is blunted by a low-pass filter circuit including a resistor 26 and a capacitor 27,
C and 12C are applied to reference input terminals.

The reference input terminals of the comparators 11C and 12C are used for adjustment for compensating the midpoint potential, and the response frequency may be low. Therefore, for example, the frequency of the carrier signal for PWM modulation is set to a low value of about 100 Hz, so that the load on the microcomputer 10 can be reduced.

At this time, the constants of the low-pass filter circuit are, for example, a cutoff frequency of 1 Hz and a resistance value of 100 k.
Ω and the capacitance of the capacitor may be set to 1.6 μF.

As described above, the A-phase to D-phase output signals are PWM-modulated using the carrier signal generation circuit 28 and the comparator 29, and the PWM signals are
By taking the data into the microcomputer 10 via D, each PW
The duty ratio of the M signal can be detected by a timer counter (not shown) in the microcomputer 10, and the output signal levels of the A to D phases can be easily detected.

Also, as compared with the fifth embodiment, during the operation of the magnetic sensor 5, the A / D converter 9 or the D /
Since the midpoint potential can be automatically compensated without using the A converter 24, the A / D converter 9 and the D / A
The converter 24 becomes unnecessary, and the processing circuit system can be configured at lower cost.

When the output signals of the A-phase to D-phase are used for absolute angle detection and midpoint potential compensation, the motor 7 starts rotating from a standstill at the time of starting, and the response speed of the detection is slow. No problem occurs even if the duty ratio is subjected to S / W processing. Further, as the carrier signal, for example, a triangular wave of 100 Hz to 1000 Hz may be used.

Further, in FIG. 13, the magnetic sensor 5
A PWM modulation circuit (comparator 29) for detection for PWM-modulating the output signal of
Both a reference value PWM modulation circuit for outputting a correction signal (reference value) from the microcomputer 10 as a PWM signal to the sensor processing circuits (comparators 11C and 12C) are provided, but either one of the PWM modulation circuits is provided. Only one may be provided.

[0187]

As described above, according to the first aspect of the present invention, the magnetic drum supported by the rotating shaft driven by the motor and the NS drum mounted on the outer peripheral side surface of the magnetic drum at the first equal pitch. NS on a magnetized first track and a second equal pitch wider than the first equal pitch on the outer peripheral side surface of the magnetic drum.
A magnetized second track, a magnetic sensor fixedly disposed to face the first and second tracks, and an arithmetic processing circuit for processing a detection signal from the magnetic sensor to obtain a rotation angle of a rotation shaft The magnetic sensor outputs first and second magnetic field signals that change at a constant cycle in accordance with the rotation of the first and second tracks as detection signals, and the arithmetic processing circuit outputs the first and second magnetic field signals. The relative rotation angle of the rotary shaft is detected based on only one of the first and second magnetic field signals, and the absolute relative rotation angle of the rotary shaft is detected based on the phase difference between the two magnetic field signals. With a simple magnetizing configuration and signal processing, the absolute rotation angle of the rotating shaft (motor electrical angle) can be detected even when the magnetized track on the magnetic drum is stationary. As well as out, the effect of the angle detecting device is obtained which can detect the absolute angle from the moment of power-on to the sensor system.

According to a second aspect of the present invention, in the first aspect, the magnetic sensor includes an A-phase signal and a B-phase signal which are shifted from each other by 90-phase with respect to the rotation angle of the first track; 90 relative to each other for the rotation angle of the second track
-Detection of phase-shifted C-phase and D-phase signals enables detection of high-resolution incremental angle signals and detection of absolute angles from the moment power is supplied to the sensor system. There is an effect that the device can be obtained.

According to a third aspect of the present invention, in the second aspect, the arithmetic processing circuit includes a value obtained by squaring the difference or the sum of the signals of the A-phase and the C-phase, and the values of the B-phase and the D-phase. Since the absolute rotation angle is detected based on the sum of the difference or sum of the signals and the squared value, a high-resolution incremental angle signal is detected, and the absolute angle is detected from the moment the power is supplied to the sensor system. There is an effect that an angle detection device capable of detecting an angle can be obtained.

According to a fourth aspect of the present invention, in the second aspect, the arithmetic processing circuit compares each signal of the A phase and the B phase with the first reference value, and By dividing the first equal pitch into eight based on the magnitude relationship of the signals, the phase of the first track is detected with a resolution of 1/8 of the first equal pitch, and each of the C-phase and D-phase signals is detected. Is compared with the second reference value, and the second equal pitch is divided into eight based on the magnitude relationship between the C-phase and D-phase signals, so that the second equal pitch can be divided by 1/8 of the second equal pitch. , And the motor current is set based on the phase difference between the first and second tracks, so that a high-resolution incremental angle signal is detected,
There is an effect that an angle detection device capable of detecting an absolute angle from the moment when power is supplied to the sensor system is obtained.

According to a fifth aspect of the present invention, in the second aspect, the arithmetic processing circuit compares each signal of the A-phase and the B-phase with the first reference value to determine the first equal pitch. By dividing into four, the phase of the first track is detected with a resolution of 1/4 of the first equal pitch, and the C phase and D phase are detected.
By comparing each signal of the phase with the second reference value and dividing the second equal pitch into four, the phase of the second track is detected with a resolution of 1/4 of the second equal pitch, 1st and 2nd
The motor current is set based on the phase difference of the tracks, so the high-resolution incremental angle signal is detected, the absolute angle is detected from the moment the sensor system is turned on, and the direction in which the motor generates torque is detected. There is an effect that an angle detection device that can perform the operation is obtained.

According to a sixth aspect of the present invention, in any one of the second to fifth aspects, the magnetic sensor includes a magnetoresistive element, and the arithmetic processing circuit includes the midpoint potential of the magnetoresistive element. And a middle point potential compensating means for compensating the average value of the A-phase signal during the rotation of the rotation axis by the first equal pitch, and the midpoint potential compensation means Since the midpoint potential of the magnetoresistive element is detected from the average value of the B-phase signal during rotation by the pitch and the midpoint potential is corrected to a reference value, a high-resolution incremental angle signal is detected. At the same time, there is an effect that an angle detection device capable of detecting an absolute angle from the moment when power is supplied to the sensor system is obtained.

According to a seventh aspect of the present invention, in the sixth aspect, the arithmetic processing circuit includes a detection PWM modulation circuit, and the detection PWM modulation circuit converts a detection signal from the magnetic sensor into a PWM signal. Input to the mid-point potential compensator after modulation so that high-resolution incremental angle signals can be detected while reducing cost, and the absolute angle is detected from the moment the sensor system is powered on to control the motor. There is an effect that an angle detection device that can perform the operation is obtained.

According to an eighth aspect of the present invention, in the sixth or seventh aspect, the arithmetic processing circuit includes a reference value PWM modulation circuit, and the reference value PWM modulation circuit includes The midpoint potential obtained by the potential compensating means is PW
Since the M-modulation is used to generate the reference value, it is possible to detect high-resolution incremental angle signals and detect the absolute angle from the moment when power is supplied to the sensor system, while realizing cost reduction. There is an effect that the device can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram schematically showing a relative phase relationship between each of the tracks 1 and 2 in FIG. 1 and a magnetic sensor 5;

FIG. 3 is a circuit connection diagram showing a configuration example of a magnetoresistive element in the magnetic sensor according to Embodiment 1 of the present invention;

FIG. 4 is a circuit configuration diagram showing a configuration of an arithmetic processing circuit according to Embodiment 2 of the present invention;

FIG. 5 is a circuit configuration diagram showing an arithmetic processing circuit according to Embodiment 3 of the present invention.

FIG. 6 is a waveform diagram showing a relationship between a phase in a magnetization pattern (when a sensor output voltage cycle is changed by a phase divided into eight) and each digital signal according to the third embodiment of the present invention.

7 is a digital signal し た obtained by multiplying the phase φ in FIG. 6 by 8
FIG. 4 is a waveform diagram showing in detail.

FIG. 8 is an explanatory diagram showing generated torque of a three-phase motor when each phase current is held at a constant current value according to Embodiment 3 of the present invention.

FIG. 9 is a circuit configuration diagram showing an arithmetic processing circuit according to Embodiment 4 of the present invention.

FIG. 10 is a waveform diagram showing an absolute electric angle detection processing operation based on a digital signal (in the case of quadrupling a sensor sine wave output) according to a fourth embodiment of the present invention.

FIG. 11 is a circuit configuration diagram showing an arithmetic processing circuit according to a fifth embodiment of the present invention.

FIG. 12 is a flowchart showing a midpoint potential compensation operation according to Embodiment 5 of the present invention.

FIG. 13 is a circuit diagram showing an arithmetic processing circuit according to Embodiment 6 of the present invention.

FIG. 14 is a perspective view showing a schematic configuration of a conventional angle detection device.

FIG. 15 is an explanatory view schematically showing a part of an M-sequence magnetization pattern formed on a track 2A in FIG. 14;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 1st track, 2nd track, 3 rotation axes, 4 magnetic drums, 5 magnetic sensors, 7 motors, 8
ECU (arithmetic processing circuit), 9D digital input port,
10 microcomputer (mid-point potential compensation means, PWM for reference value)
Modulation circuit), 11C, 12C comparator (midpoint potential compensation means), 16, 17 digital signal generation circuit, 25
Digital output port, 28 carrier signal generation circuit (PWM modulation circuit for detection), 29 comparator (PWM modulation circuit for detection), P1 first magnetization pitch (equal pitch), P2 second magnetization pitch (etc.) Pitch), R1
1a to R14a, R11b to R14b, R21c to R2
4c, R21d to R24d MR elements (magnetic resistance elements),
va to vd A-phase to D-phase signals, φ, φ1, φ2 phases,
ψ, ψ1, ψ28 Digital signal multiplied by 8, Ω, Ω1,
Ω24 Digital signal multiplied by 4.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazumichi Tsutsumi 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Takayuki Kifuku 2-3-2 Marunouchi, Chiyoda-ku, Tokyo No. 3 Mitsubishi Electric Co., Ltd. (72) Inventor Takeshi Sugiyama 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. No. 3 Mitsubishi Electric Corporation (72) Inventor Hideki Yonegata 2-6-1 Otemachi, Chiyoda-ku, Tokyo Inside Mitsubishi Electric Engineering Co., Ltd. (72) Inventor Satoru Akutsu Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 2-3, Mitsubishi Electric Corporation 2F063 AA35 BA30 CA40 DA05 DD05 EA03 GA52 GA67 GA72 KA02 KA04 LA03 LA30 2F077 AA27 CC02 CC07 CC08 N N03 NN26 PP14 QQ03 TT09 TT52 TT81 5H019 BB03 BB05 BB23 CC03 5H560 AA10 DA08 DA20 TT01 TT02 TT05 TT07 TT08 TT15

Claims (8)

[Claims] 1. A magnetic drum supported on a rotating shaft driven by a motor, a first track NS-magnetized at a first equal pitch on an outer peripheral surface of the magnetic drum, and an outer periphery of the magnetic drum A second track NS-magnetized on a side surface at a second equal pitch wider than the first equal pitch, and a magnetic sensor fixedly arranged to face the first and second tracks; An arithmetic processing circuit for processing a detection signal from the magnetic sensor to obtain a rotation angle of the rotating shaft, wherein the magnetic sensor changes at a constant cycle according to rotation of the first and second tracks, respectively. First and second
The arithmetic processing circuit detects an absolute rotation angle of the rotation shaft based on a phase difference between the first and second magnetic field signals, and outputs the first or second magnetic field signal. An angle detection device for detecting a small relative rotation angle of the rotation shaft based on only one of the magnetic field signals of the first and second magnetic fields. 2. The magnetic sensor according to claim 1, further comprising: an A-phase signal and a B-phase signal having a phase difference of 90 degrees with respect to the rotation angle of the first track; The angle detection device according to claim 1, wherein the C-phase and D-phase signals having different phases are detected. 3. The arithmetic processing circuit according to claim 1, wherein
Detecting the absolute rotation angle based on an addition value of a value obtained by squaring the difference or the sum of each signal of the phase and a value obtained by squaring the difference or the sum of each signal of the B phase and the D phase. The angle detection device according to claim 2, wherein 4. The arithmetic processing circuit compares each of the A-phase and B-phase signals with a first reference value,
Detecting the phase of the first track at a resolution of 1/8 of the first equal pitch by dividing the first equal pitch into eight based on the magnitude relationship between the A-phase and B-phase signals And comparing each of the C-phase and D-phase signals with a second reference value,
Detecting the phase of the second track at a resolution of 1/8 of the second equal pitch by dividing the second equal pitch into eight based on the magnitude relationship between the C-phase and D-phase signals The angle detection device according to claim 2, wherein the motor current is set based on a phase difference between the first and second tracks. 5. The first equal pitch by comparing each signal of the A phase and the B phase with a first reference value and dividing the first equal pitch by four. Detecting the phase of the first track with a resolution of 1/4 of the above, comparing each of the C-phase and D-phase signals with a second reference value, and dividing the second equal pitch into four. The phase of the second track is detected with a resolution of 1/4 of the second equal pitch, and the current of the motor is set from the phase difference between the first and second tracks. The angle detection device according to claim 2. 6. The magnetic sensor includes a magneto-resistive element, the arithmetic processing circuit includes a mid-point potential compensator for compensating a mid-point potential of the magneto-resistive element, The average value of the A-phase signal while the rotation axis rotates by the first equal pitch, and the average of the B-phase signal while the rotation axis rotates by the first equal pitch. 6. The angle detecting device according to claim 2, wherein a midpoint potential of the magnetoresistive element is detected from the value and the midpoint potential is corrected to a reference value. 7. The arithmetic processing circuit includes a detection PWM modulation circuit, and the detection PWM modulation circuit inputs a detection signal from the magnetic sensor to the midpoint potential compensation means after PWM modulation. The angle detection device according to claim 6, wherein: 8. The arithmetic processing circuit according to claim 1, wherein the reference value PWM is
7. The PWM circuit for a reference value, wherein the PWM circuit for the reference value generates the reference value by PWM modulating the midpoint potential obtained by the midpoint potential compensation means. 7
An angle detection device according to item 1.