JP2012032313A - Rotation detector and phase error correction method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To offer a rotation detector capable of correcting a phase error of a two-phase signal by only an easy calculation.SOLUTION: A phase error φ between an A-phase sensor signal Va0 and a B-phase signal sensor Vb0 generated from a sensor section 3 of a rotation detector 1 is kept to be measured beforehand. The amplitudes A, B to be used for creating an A-phase signal Va(=A sinθ) of the amplitude A and a B-phase signal Vb(=B cos(θ-φ)) of the amplitude B which are offset corrected from the two-phase signal, and adjustment gains r1, r2 to be used for creating an A-phase correction signal Va1(=r1.A sinθ) and a B-phase correction signal Vb1(=r2*B cos(θ-φ)by performing the gain correction to the A-phase signal Va and the B-phase signal Vb, are kept to be adjusted in these values so as to satisfy both of {(r2*B/r1*A)}cosθ=1 and (r2*B)/A=1. Thus, the A-phase correction signal Va1 and B-phase correction signal Vb1, the phase errors of which are corrected, can be obtained and a rotation angle θ are calculated based on these obtained signals.

Description

  The present invention relates to a rotation detector that detects a rotation position of a rotating member based on two-phase sine wave signals of A and B phases obtained from a magnetic sensor and having a phase difference of 90 degrees. More specifically, the phase of the rotation detector that can detect the rotation angle position with high accuracy by removing the phase error of the two-phase signal caused by the assembly pitch error of the magnetic detection element of the magnetic sensor by a simple calculation method. The present invention relates to an error correction method.

  In a rotation detector that detects the rotational position of a rotating member such as a motor shaft based on the output of a two-phase sine wave type magnetic sensor, the following two methods are known as methods for improving the angular position detection accuracy. Yes.

  In the first method, the angle error for one rotation of the motor shaft is acquired and stored in advance as a numerical string, and the stored angle error data is read and corrected when calculating the actual angular position. It is a method of applying. This method is effective for a magnetic sensor excellent in reproducibility of a detection position. However, a highly functional digital circuit is required, which is disadvantageous in terms of space saving and cost reduction. In addition, there is a restriction that the combination of the angle calculation unit and the magnetic sensor is fixed one-to-one.

  The second method is a method for individually correcting and improving components that cause errors by increasing the assembly accuracy. In this method, it is necessary to individually solve the error components of various factors included in the two-phase signal. However, since the correction circuit can be configured only by an analog circuit, the above-mentioned method is used in terms of space saving and cost reduction. This is more advantageous than the first method.

  Here, Patent Document 1 discloses a rotational position detector that corrects a phase error of a two-phase signal by digital arithmetic processing. Patent Document 2 similarly describes an encoder signal that corrects a phase error of a two-phase signal. A correction circuit is disclosed.

JP 2001-296142 A JP 2008-58252 A

  However, no method has been proposed that can correct a phase error of a two-phase signal by a simple calculation using an analog circuit.

  An object of the present invention is to propose a rotation detector capable of correcting a phase error included in a two-phase signal only by simple calculation and a phase error correction method for the rotation detector.

In order to solve the above problems, the present invention provides:
In calculating the rotation angle θ of the detection object using the A-phase sensor signal Va0 and the B-phase sensor signal Vb0 that are different in phase by 90 degrees according to the rotation of the detection object, the A-phase sensor signal Va0 is calculated. A rotation detector phase error correction method for removing a rotation angle calculation error caused by the phase error φ of the B phase sensor signal Vb0,
The phase error φ is measured from the A-phase sensor signal Va0 and the B-phase sensor signal Vb0,
From the A-phase sensor signal Va0 and the B-phase sensor signal Vb0, the A-phase signal Va (= Asinθ) and the B-phase signal Vb (= Bcos (θ−φ)) having the amplitude B, which have been offset-corrected, are obtained. The amplitudes A and B used for generation, the A-phase signal Va and the B-phase signal Vb are subjected to gain correction, and an A-phase correction signal Va1 (= r1 · Asinθ, r1: adjustment gain) and B-phase correction The adjustment gains r1 and r2 used to generate the signal Vb1 (= r2 · Bcos (θ−φ), r2: adjustment gain) are:
{(R2 · B) / (r1 · A)} cosφ = 1 and (r2 · B) / A = 1
Adjust these values to satisfy
The value Vb2 is
Vb2 = Vb1-Va1√ {1 / (r1) ² −1}
Calculated by
The rotation angle θ is
θ = tan ⁻¹ (Va1 / Vb2)
It is characterized by calculating by.

  In the method of the present invention, for example, the amplitude ratio A / B of the two-phase signal is an appropriate value from the A-phase sensor signal Va0 and the B-phase sensor signal Vb0 in the manufacturing stage after the rotation detector is mounted on the detection target. The amplitudes A and B can be adjusted so that Furthermore, the adjustment gains r1 and r2 can be adjusted based on the amplitudes A and B so as to satisfy the above conditional expression.

  In the phase correction operation at the time of actual rotation angle detection, phase error correction can be performed by simple calculation (only four arithmetic operations). That is, the A-phase correction signal Va1 and the B-phase correction signal Vb1 from which the phase error has been removed can be calculated from the sensor signals Va0 and Vb0. Therefore, phase error correction can be performed by an analog circuit. Also, based on these correction signals, for example, by calculating the value Vb2 in an angle calculation circuit composed of a digital circuit, the rotation angle θ can be calculated from Va1 and Vb2 by the same calculation as in the prior art.

  Here, as the rotation detector to which the correction method of the present invention can be applied, a detector provided with a magnetic sensor including at least two Hall elements for detecting a rotating magnetic field of a magnet attached to the detection object. Can be mentioned. In this case, the phase error φ includes a phase error component caused by an assembly pitch error of the Hall element and a phase error component caused by a phase shift of the magnetized waveform of the magnet. According to the method of the present invention, such a phase error component can be reliably removed.

Next, the rotation detector of the present invention includes:
A magnetic sensor that outputs an A-phase sensor signal Va0 and a B-phase sensor signal Vb0 whose phases are different from each other by 90 degrees according to the rotation of the detection object;
A signal correction circuit that corrects the A-phase sensor signal Va0 and the B-phase sensor signal Vb0 output from the magnetic sensor to generate and output an A-phase correction signal Va1 and a B-phase correction signal Vb1;
An angle calculation circuit that calculates a rotation angle θ of the detection object based on the A phase correction signal Va1 and the B phase correction signal Vb1 output from the signal correction circuit;
The signal correction circuit includes:
An amplitude correction unit that generates an A-phase signal Va of amplitude A and a B-phase signal Vb of amplitude B subjected to offset correction from the A-phase sensor signal Va0 and the B-phase sensor signal Vb0 output from the sensor unit; ,
The A phase signal Va and the B phase signal Vb are subjected to gain correction, and the A phase signal r1 · Va (r1: adjustment gain) and the B phase signal r2 · Vb (r2: adjustment gain) are respectively converted into the A phase. A gain correction unit that generates the correction signal Va1 and the B-phase correction signal Vb1,
The phase A signal Va and the phase B signal Vb are expressed as follows, assuming that the phase error of these signals obtained by measuring the phase A sensor signal Va0 and the phase B sensor signal Vb0 is φ. The B phase signal Vb is defined by the following equation:
Va = Asinθ
Vb = Bcos (θ−φ)
The amplitudes A and B and the adjustment gains r1 and r2 are set so as to satisfy both of the following conditional expressions:
{(R2 · B) / (r1 · A)} cosφ = 1
(R2 · B) / A = 1
The angle calculation circuit includes:
A first calculation unit for calculating the value Vb2 by the following equation;
Vb2 = Vb1-Va1√ {1 / (r1) ² −1}
And a second calculation unit for calculating the rotation angle θ according to the following equation.
θ = tan ⁻¹ (Va1 / Vb2)

Here, in the signal correction circuit, the gain r3 and the value Vb2 may be calculated together with the values Va1 and Vb1.
r3 = Va1√ {1 / (r1) ² −1}
Vb2 = Vb1-Va1 · r3
In this way, the first calculation unit in the angle calculation circuit can be omitted.

  Here, the magnetic sensor may include at least two Hall elements that detect a rotating magnetic field of a magnet attached to the detection target.

  Further, the signal correction circuit can be an analog circuit, and the arithmetic circuit can be a digital circuit. In this case, the AD conversion that converts the output signal of the signal correction circuit into a digital signal and outputs the digital signal to the arithmetic circuit A circuit may be arranged.

  In the present invention, by appropriately setting the relationship between the amplitude and the adjustment gain in the correction signal generated by shaping the waveform of the two-phase sine wave detection signal, the phase included in the detection signal only by the four arithmetic operations The error can be corrected. Therefore, a simple analog circuit can be used as the correction circuit without using a complicated digital arithmetic circuit, and space saving and cost reduction of the rotation detector can be realized.

It is a schematic block diagram which shows the control system of the rotation detector to which this invention is applied. It is a schematic flowchart which shows the adjustment procedure at the time of manufacture in the rotation detector of FIG. It is a schematic flowchart which shows the rotation angle detection operation | movement in the rotation detector of FIG.

  Embodiments of a rotation detector to which the present invention is applied will be described below with reference to the drawings.

(overall structure)
FIG. 1 is a schematic block diagram showing a control system of a rotation detector according to an embodiment of the present invention. The rotation detector 1 includes a magnetic sensor 3 that outputs an A-phase sensor signal Va0 and a B-phase sensor signal Vb0 whose phases are different from each other by 90 degrees according to the rotation of a detection object, for example, the motor shaft 2a of the motor 2. ing. The magnetic sensor 3 is a magnetic sensor provided with at least two Hall elements Ha and Hb for detecting a rotating magnetic field of a multipolar magnet ring 3a attached coaxially to the motor shaft 2a.

  The sinusoidal A-phase sensor signal Va0 output from the Hall element Ha of the magnetic sensor 3 and the sinusoidal B-phase sensor signal Vb0 output from the Hall element Hb are supplied to a signal correction circuit 4 composed of an analog circuit. Is done. The signal correction circuit 4 corrects these signals to generate the A-phase correction signal Va1 and the B-phase correction signal Vb1. The A-phase correction signal Va1 and the B-phase correction signal Vb1 are output from the signal correction circuit 4 and then converted into digital signals via the AD converters 5a and 5b, and then supplied to the angle calculation circuit 6 including a digital circuit. . The angle calculation circuit 6 calculates the rotation angle θ of the motor shaft 2a that is the detection target based on the digitized A-phase correction signal Va1 and B-phase correction signal Vb1.

  The calculated rotation angle θ is supplied to the motor control circuit 7, for example. The motor control circuit 7 controls the rotational position of the motor shaft 2a by feedback controlling the motor 2 based on the detected rotational angle θ.

  The signal correction circuit 4 composed of an analog circuit, from the A-phase sensor signal Va0 and the B-phase sensor signal Vb0 output from the magnetic sensor 3, performs an offset correction on the A-phase signal Va of amplitude A and the B-phase of amplitude B. The amplitude correction unit 4a that generates the signal Vb and the A phase signal Va and the B phase signal Vb are subjected to gain correction, and the A phase signal r1 · Va (r1: adjustment gain) and the B phase signal r2 · Vb (r2: adjustment) Gain correction section 4b for generating (Gain) as A phase correction signal Va1 and B phase correction signal Vb1, respectively.

Here, if the phase error of these signals obtained by measuring the A phase sensor signal Va0 and the B phase sensor signal Vb0 output from the magnetic sensor 3 is φ, the A phase signal Va and the B phase signal Vb are φ. Is defined by the following equation.
Va = Asinθ
Vb = Bcos (θ−φ)

The amplitudes A and B and the adjustment gains r1 and r2 are set so as to satisfy both of the following conditional expressions.
{(R2 · B) / (r1 · A)} cosφ = 1
(R2 · B) / A = 1

Next, the angle calculation circuit 6 includes a first calculation unit 6a that calculates a value Vb2 by the following equation.
Vb2 = Vb1-Va1√ {1 / (r1) ² −1}
Moreover, the 2nd calculating part 6b which calculates rotation angle (theta) by following Formula is provided.
θ = tan ⁻¹ (Va1 / Vb2)

In this example, the value Vb2 is calculated in the first calculation unit 6a of the angle calculation circuit 6 as described above. Instead, the gain correction unit 4b of the signal correction circuit 4 calculates the next value as a constant (gain) r3, and based on this, calculates the value Vb2, and this is converted into an angle calculation circuit 6 via an AD converter. May be supplied.
r3 = √ {1 / (r1) ² −1}
Vb2 = Vb1-Va1 · r3
Thus, if the gain correction unit 4b calculates the adjustment gains r1, r2 and the gain r3 and outputs the values Va1, Vb1, Vb2, the first calculation unit 6a of the angle calculation circuit 6 can be omitted. .

(Derivation of phase correction formula)
Here, a method of deriving an equation for calculating the rotation angle θ with the phase error corrected will be described. First, the definition of each symbol is listed below.
Va: A phase signal (A phase sensor signal after offset / amplitude correction)
Vb: B phase signal (B phase sensor signal after offset / amplitude correction)
θ: Rotation angle (motor shaft angle)
φ: Hall element Ha, Hb pitch error (phase error)
A: A phase amplitude B: B phase amplitude r1: A phase adjustment gain r2: B phase adjustment gain A, B phase signals Va, Vb, A, B phase correction signals Va1, Vb1 are expressed as follows.
Va = Asinθ (1)
Vb = Bcos (θ−φ) (2)
Va1 = r1 · Va (3)
Vb1 = r2 · Vb (4)
From the additive theorem, the following equation is obtained.
cos (θ−φ) = cos θ cos φ + sin θ sin φ (5)
Vb1 = r2 · Bcos θcosφ + r2 · Bsinθsinφ (6)
The following equation is obtained by dividing equation (3) by equation (6).
Va1 / Vb1
= R1 · Asinθ / (r2 · Bcosθcosφ + r2 · Bsinθsinφ) (7)
The following formula is obtained by rearranging the formula (7).
sinθ / cosθ
= [{(R2 · B) / (r1 · A)} Va1cosφ] / [Vb1 − {(r2 · B) / (r1 · A)} Va1sinφ] (8)
Here, A, B, r1, and r2 satisfy both of the following conditional expressions.
{(R2 · B) / (r1 · A)} cos φ = 1, (r2 · B) / A = 1 (9)
Assuming this, the relationship of the following equation (10) is obtained.
cosφ = r1 (10)
From sin ² φ = 1−cos ² φ, the following equation is obtained.
sinφ = √ {1- (r1) ² } (11)
Substituting the formulas (9), (10), and (11) into the formula (8) and rearranging gives the following formula.
sinθ / cosθ
= Va1 / [Vb1-Va1√ {1 / (r1) ² -1}] (12)
here,
When Vb2 = Vb1−Va1√ {1 / (r1) ² −1}, Expression (12) is as follows.
sin θ / cos θ = Va1 / Vb2
Therefore, the calculation formula for the rotation angle θ is as follows.
θ = tan ⁻¹ (Va1 / Vb2) (13)

(Rotation detector adjustment)
FIG. 2 is a flowchart showing the adjustment work in the manufacturing stage after the rotation detector 1 having the above-described configuration is mounted on the motor shaft 2a. After the magnetic sensor 3 is assembled to the motor shaft 2a (ST1), the signal correction circuit 4 adjusts the offset of the outputs (A phase sensor signal Va0, B phase sensor signal Vb0) of the Hall elements Ha and Hb of the motor shaft 2a. In addition, amplitude adjustment is performed so that these amplitude ratios A / B have appropriate values (ST2). Next, based on the A-phase signal Va and the B-phase signal Vb after the offset correction, the phase error φ caused by the Hall element pitch error included in these signals is measured (ST3). The phase error φ may be measured from the sensor outputs Va0 and Vb0. Thereafter, gain adjustment is performed so as to satisfy the conditional expression (9) (ST4). Thereby, the adjustment gains r1 and r2 of the signal correction circuit 4 are set.

(Rotation angle detection operation)
FIG. 3 is a flowchart showing the detection operation of the rotation angle θ of the motor shaft 2a by the rotation detector 1. As the motor shaft 2a rotates, the A-phase sensor signals Va0 and Vb0 are output from the Hall elements Ha and Hb of the magnetic sensor 3 (ST11). These signals are supplied to the signal correction circuit 4 and subjected to offset correction to generate an A-phase signal Va and a B-phase signal Vb (ST12). Further, gain adjustment is performed to generate an A-phase correction signal Va1 and a B-phase correction signal Vb1 (ST13). The phase error of the two-phase signal is corrected by adjusting the amplitude and gain.

  Next, the A-phase correction signal Va1 and the B-phase correction signal Vb1 are digitized and then supplied to the angle calculation circuit 6, the value Vb2 is calculated by the above equation (12) (ST14), and the above equation (13) ) To calculate the rotation angle θ (ST15).

  As described above, in the rotation detector 1, the phase error can be corrected by a simple calculation using only four arithmetic operations in the signal correction circuit 4 including an analog circuit. Therefore, the circuit board can be made small, which is advantageous for space saving and cost reduction.

DESCRIPTION OF SYMBOLS 1 Rotation detector 2 Motor 2a Motor shaft 3 Magnetic sensor 4 Signal correction circuit 4a Amplitude correction part 4b Gain correction part 5a, 5b AD converter 6 Angle calculation circuit 6a First calculation part 6b Second calculation part 7 Motor control circuit Ha , Hb Hall element

Claims (5)

In calculating the rotation angle θ of the detection object using the A-phase sensor signal Va0 and the B-phase sensor signal Vb0 that are different in phase by 90 degrees according to the rotation of the detection object, the A-phase sensor signal Va0 is calculated. A rotation detector phase error correction method for removing a rotation angle calculation error caused by the phase error φ of the B phase sensor signal Vb0,
The phase error φ is measured from the A-phase sensor signal Va0 and the B-phase sensor signal Vb0,
From the A-phase sensor signal Va0 and the B-phase sensor signal Vb0, the A-phase signal Va (= Asinθ) and the B-phase signal Vb (= Bcos (θ−φ)) having the amplitude B, which have been offset-corrected, are obtained. The amplitudes A and B used for generation, the A-phase signal Va and the B-phase signal Vb are subjected to gain correction, and an A-phase correction signal Va1 (= r1 · Asinθ, r1: adjustment gain) and B-phase correction The adjustment gains r1 and r2 used to generate the signal Vb1 (= r2 · Bcos (θ−φ), r2: adjustment gain) are:
{(R2 · B) / (r1 · A)} cosφ = 1 and (r2 · B) / A = 1
Adjust these values to satisfy
The value Vb2 is
Vb2 = Vb1-Va1√ {1 / (r1) ² −1}
Calculated by
The rotation angle θ is
θ = tan ⁻¹ (Va1 / Vb2)
A phase error correction method for a rotation detector, characterized by: In claim 1,
The rotation detector includes a magnetic sensor including at least two Hall elements that detect a rotating magnetic field of a magnet attached to the detection target;
The phase error correction method for a rotation detector, wherein the phase error φ includes a phase error component due to an assembly pitch error of the Hall element. A magnetic sensor that outputs an A-phase sensor signal Va0 and a B-phase sensor signal Vb0 whose phases are different from each other by 90 degrees according to the rotation of the detection object;
A signal correction circuit that corrects the A-phase sensor signal Va0 and the B-phase sensor signal Vb0 output from the magnetic sensor to generate and output an A-phase correction signal Va1 and a B-phase correction signal Vb1;
An angle calculation circuit that calculates a rotation angle θ of the detection object based on the A phase correction signal Va1 and the B phase correction signal Vb1 output from the signal correction circuit;
The signal correction circuit includes:
An amplitude correction unit that generates an A-phase signal Va of amplitude A and a B-phase signal Vb of amplitude B subjected to offset correction from the A-phase sensor signal Va0 and the B-phase sensor signal Vb0 output from the sensor unit; ,
The A phase signal Va and the B phase signal Vb are subjected to gain correction, and the A phase signal r1 · Va (r1: adjustment gain) and the B phase signal r2 · Vb (r2: adjustment gain) are respectively converted into the A phase. A gain correction unit that generates the correction signal Va1 and the B-phase correction signal Vb1,
The phase A signal Va and the phase B signal Vb are expressed as follows, assuming that the phase error of these signals obtained by measuring the phase A sensor signal Va0 and the phase B sensor signal Vb0 is φ. The B phase signal Vb is defined by the following equation:
Va = Asinθ
Vb = Bcos (θ−φ)
The amplitudes A and B and the adjustment gains r1 and r2 are set so as to satisfy both of the following conditional expressions:
{(R2 · B) / (r1 · A)} cosφ = 1
(R2 · B) / A = 1
The angle calculation circuit includes:
A first calculation unit for calculating the value Vb2 by the following equation;
Vb2 = Vb1-Va1√ {1 / (r1) ² −1}
A rotation detector comprising: a second calculation unit that calculates the rotation angle θ according to the following equation.
θ = tan ⁻¹ (Va1 / Vb2) A magnetic sensor that outputs an A-phase sensor signal Va0 and a B-phase sensor signal Vb0 whose phases are different from each other by 90 degrees according to the rotation of the detection object;
A signal correction circuit that corrects the A-phase sensor signal Va0 and the B-phase sensor signal Vb0 output from the magnetic sensor to generate and output an A-phase correction signal Va1 and a B-phase correction signal Vb1;
An angle calculation circuit that calculates a rotation angle θ of the detection object based on the A phase correction signal Va1 and the B phase correction signal Vb1 output from the signal correction circuit;
The signal correction circuit includes:
An amplitude correction unit that generates an A-phase signal Va of amplitude A and a B-phase signal Vb of amplitude B subjected to offset correction from the A-phase sensor signal Va0 and the B-phase sensor signal Vb0 output from the sensor unit; ,
The A phase signal Va and the B phase signal Vb are subjected to gain correction, and the A phase signal r1 · Va (r1: adjustment gain) and the B phase signal r2 · Vb (r2: adjustment gain) are respectively converted into the A phase. A gain correction unit that generates the correction signal Va1 and the B-phase correction signal Vb1, and calculates a constant r3 and a value Vb2 by the following equation:
r3 = Va1√ {1 / (r1) ² −1}
Vb2 = Vb1-Va1 · r3
The phase A signal Va and the phase B signal Vb are expressed as follows, assuming that the phase error of these signals obtained by measuring the phase A sensor signal Va0 and the phase B sensor signal Vb0 is φ. The B phase signal Vb is defined by the following equation:
Va = Asinθ
Vb = Bcos (θ−φ)
The amplitudes A and B and the adjustment gains r1 and r2 are set so as to satisfy both of the following conditional expressions:
{(R2 · B) / (r1 · A)} cosφ = 1
(R2 · B) / A = 1
The angle detector circuit calculates the rotation angle θ according to the following equation.
θ = tan ⁻¹ (Va1 / Vb2) In claim 3 or 4,
The magnetic sensor includes at least two Hall elements that detect a rotating magnetic field of a magnet attached to the detection target.

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