JP2012229981A - Position detecting device - Google Patents

Abstract

A position detection device that has a simple configuration and can be easily miniaturized is realized.
In a position detection device for detecting a rotational position of a motor based on a detection signal of a magnetic resolver,
A resolver stator in which a plurality of teeth are formed, each of which is arranged in an annular shape around the rotation center axis of the motor, each of which is wound with a detection coil at a rotation position;
A resolver rotor having n teeth (n is an integer of 2 or more) arranged in an annular shape facing the resolver stator and decentered from the rotation center axis;
An arithmetic unit that calculates the absolute rotational position of the motor based on the signal amplitude and phase of the detection signal;
Is provided.
[Selection] Figure 1

Description

  The present invention relates to a position detection device that detects a rotational position of a motor based on a detection signal of a magnetic resolver. Specifically, the position detection is obtained by converting the magnetic characteristic change of the magnetic resolver into an electric signal, and detecting the rotational position of the motor based on a plurality of detection signals that change periodically due to the movement of the magnetic resolver and have different phases. Relates to the device.

  An actuator that performs a positioning operation includes a combination of a motor and an encoder. In this actuator, the rotational position of the motor is detected by an encoder, and the positioning operation is performed by feedback-controlling the rotational position of the motor using the detection signal as a feedback signal. As such an actuator, there is one in which an encoder has a function of detecting an absolute rotational position.

FIG. 5 is a schematic configuration diagram of an actuator having a conventional absolute position detection function.
In FIG. 5, 500 is a motor unit, and 600 is a magnetic resolver unit as an encoder. The magnetic resolver unit 600 includes an nX resolver 610 and a 1X resolver 620.

  In the 1X resolver 620, when the rotor 520 makes one rotation, the phase of the detection signal changes by one cycle. In the nX resolver 610, when the rotor 520 rotates 1 / n (n is an integer of 2 or more), the phase of the detection signal changes by one cycle.

  In the magnetic resolver unit 600, the absolute rotation position is detected by the 1X resolver 620 with resolution of 1 / n rotation and the rotation position within the detected 1 / n rotation is detected by the nX resolver 610. Is detected.

  The motor unit 500, the nX resolver 610, and the 1X resolver 620 are all outer rotor type, and the inner stator 510 has a hollow structure. The hollow portion is used as a wiring space or the like.

  6 is a detailed view of the magnetic resolver unit 600. FIG. 6A is a top view of the nX resolver 610, and FIG. 6B is a top view of the 1X resolver 620. FIG.

  In FIG. 6A, n teeth are formed on the resolver rotor 611 of the nX resolver 610 in an annular shape with a constant pitch around the rotation center axis of the motor 500. A resolver stator 612 having a plurality of salient poles and one or more teeth on each salient pole is disposed opposite to the teeth of the resolver rotor 611.

  When the positional relationship between the teeth of the resolver rotor 611 and the salient poles of the resolver stator 612 changes, the inductance of the coil wound around the resolver stator 612 changes. Using the fact that the inductance changes by one period per resolver rotor 1 / n rotation, the rotational position within the motor 1 / n rotation is detected.

  In FIG. 6B, the 1X resolver 620 is provided with four salient poles on the resolver stator 622. The resolver rotor 621 has a ring shape, and the ring width changes by one period per ring circumference. As a result, the gap between the resolver rotor 621 and the resolver stator 622 changes by one period per resolver rotor rotation.

  When the gap between the resolver rotor and the resolver stator changes, the magnetic characteristics of the coil wound around the resolver stator 622 change. The rotational position within one rotation of the motor is detected using the fact that the inductance changes by one period per one rotation of the resolver rotor.

  The following patent document describes an actuator having the absolute position detection function as described above.

Japanese Utility Model Publication No. 05-11776 Japanese Patent Laid-Open No. 05-324075

However, in the configuration as described above, since there are two systems of resolvers, nX resolver 610 and 1X resolver 620, the magnetic resolver unit 600 is increased in size.
In order to suppress magnetic interference between resolvers, (1) the distance between the nX resolver 610 and the 1X resolver 620 is increased, (2) a magnetic shield is provided between the nX resolver 610 and the 1X resolver 620, and (3) the nX resolver 610. And the 1X resolver 620 are time-divided, and the control of (1) to (3) must be performed alone or in combination, such as controlling the other excitation to be cut off while one is excited. The configuration of the detection unit becomes complicated.

  It is an object of the present invention to realize a position detection device that eliminates the conventional problems and can be easily miniaturized with a simple configuration.

In order to achieve such a subject, the present invention has the following configuration.
(1) In a position detection device that detects the rotational position of a motor based on a detection signal of a magnetic resolver,
A resolver stator in which a plurality of teeth are formed, each of which is arranged in an annular shape around the rotation center axis of the motor, each of which is wound with a detection coil at a rotation position;
A resolver rotor having n teeth (n is an integer of 2 or more) arranged in an annular shape facing the resolver stator and decentered from the rotation center axis;
An arithmetic unit that calculates the absolute rotational position of the motor based on the signal amplitude and phase of the detection signal;
A position detection device comprising:

(2) The calculation unit determines a position within one rotation of the motor based on a change in signal amplitude of the detection signal caused by a gap between the resolver rotor and the resolver stator changing by one period per one rotation of the motor. The position detection device according to (1), wherein the position detection device calculates the position detection device.

(3) The calculation unit calculates a position within 1 / n rotation of the motor based on a change of the phase of the detection signal by one cycle with respect to the motor 1 / n rotation. The position detection device according to 1) or (2).

(4) The calculation unit divides the detection coil group wound around the plurality of teeth of the resolver stator into a plurality of channels by combining adjacent phases, and calculates the rotational position of the motor for each channel. The position detection device according to any one of (1) to (3), wherein the calculated values are averaged.

(5) The total number of teeth formed on the resolver stator is set to m times the channel × the number of phases (m is an integer of 2 or more), according to any one of (1) to (4), Position detector.

According to the present invention, the following effects can be expected.
(1) A resolver stator having a plurality of teeth each having teeth formed on a rotation center axis of the motor, and an annular shape opposed to the resolver stator and decentered from the rotation center axis A resolver rotor having n teeth (n is an integer equal to or greater than 2) and an arithmetic unit that calculates the absolute position of the motor based on the signal amplitude and phase of the detection signal of the magnetic resolver. Thus, the absolute rotational position of the motor can be detected with a single resolver, and a position detection device that can be easily miniaturized with a simple configuration can be realized.

(2) Further, since the absolute rotational position is detected by a single resolver, it is not necessary to consider magnetic interference between conventional resolvers having a plurality of configurations, and the configuration of the detection unit can be simplified and reduced in cost.

(3) The plurality of teeth of the resolver stator has a structure in which the detection coil is wound around each of the teeth, so that the structure of the teeth and the coil becomes small. It is possible to improve the accuracy of the average detection of each channel and contribute to the improvement of the accuracy of position detection.

It is a figure which shows Example 1 of this invention. 3 is a block diagram illustrating a configuration of a calculation unit 2. FIG. It is an image figure of the state of a magnetic resolver 1, and a detection signal. 5 is an image diagram of the operation of the phase detection circuit 23. FIG. It is a schematic block diagram of the actuator with the absolute position detection function in the past. 2 is a detailed view of a magnetic resolver unit 101. FIG.

  FIG. 1 is a diagram showing a first embodiment of the present invention. FIG. 1 is a top view of a magnetic resolver 1 according to the present invention, wherein 1a is a resolver rotor and 1b is a resolver stator. The magnetic resolver 1 is an outer rotor type, and the inner resolver stator 1b has a hollow structure.

  The resolver stator 1b is composed of laminated steel plates, and is formed in an annular shape centering on the rotation center axis of a motor (not shown). A plurality of teeth 1b1 are formed at the tip of the resolver stator 1b, and a detection coil 1b2 is wound around each of the teeth.

  The number of teeth is 4 phases × 2 (m1, m2) = 8 for each of channels ch0 to ch3 obtained by dividing the circumference into 90 degrees every 90 degrees, and a total of 32 teeth are formed in 4 channels. The detection coil 1b2 wound around each tooth 1b1 is connected to the calculation unit 2 described later, and the absolute rotation position of the motor is calculated.

  The resolver rotor 1a has a ring shape made of laminated steel plates, and the ring width is formed so as to change by one period per ring circumference. Then, n (40 in FIG. 1) teeth 1a1 are formed at a constant pitch at positions facing the teeth of the resolver stator 1b inside the ring shape. That is, the resolver rotor 1a has a configuration in which n teeth are formed in an annular shape that faces the resolver stator 1b and is eccentric from the rotation center axis of the motor.

  The magnetic resolver 1 is divided into four channels ch0 to ch3 every 90 degrees, and the tooth 1b2 of the resolver stator 1b is composed of a set of four adjacent phases of sin0 phase, sinπ phase, cos0 phase, and cosπ phase. Corresponding to each channel.

  The teeth 1b1 of the resolver stator 1b are provided at positions where the mechanical angle is 90 ° different from the teeth 1a1 of the resolver rotor 1a, and four phases of sin0 phase, sinπ phase, cos0 phase, and cosπ phase are formed for each adjacent phase. To do.

  The detection coil 1b2 wound around each tooth 1b1 is connected to a calculation unit 2 described later, and calculates the absolute rotational position of the motor.

  The gap between the teeth 1a1 of the resolver rotor 1a and the teeth 1b1 of the resolver stator 1b changes by one period per revolution of the resolver rotor 1a. In FIG. 1, the gap near the center of ch0 is indicated by d0, the gap near the center of ch1 is indicated by d1, the gap near the center of ch2 is indicated by d2, and the gap near the center of ch3 is indicated by d3.

  When the resolver rotor 1a rotates, the gap between the teeth 1a1 of the resolver rotor 1a and the teeth 1b1 of the resolver stator 1b changes continuously as d0 → d1 → d2 → d3 → d0 →.

  When the gap between the tooth 1a1 of the resolver rotor 1a and the tooth 1b1 of the resolver stator 1b changes, the amplitude of the detection signal is inversely proportional to the gap, so the magnetic characteristics of the detection coil 1b2 wound around the tooth 1b1 of the resolver stator 1b change. To do. The amplitude of the detection signal changes by one period per revolution of the resolver rotor 1a.

  Using the change in the amplitude of the detection signal due to this gap change, the rotational position within one rotation of the motor is detected. The rotational position within one rotation of the motor is specified based on the detected position relationship for n teeth, and the motor 1 / n rotation is detected as the resolution.

  When the relative position of the resolver rotor teeth 1a1 and the resolver stator 1b teeth 1b1 changes, the magnetic characteristics of the detection coil wound around the resolver stator change. The phase of the detection signal changes by one cycle per resolver rotor 1 / n rotation. Using the phase change of the detection signal, the rotational position within the motor 1 / n rotation is detected.

  That is, the rotational position of the motor is detected with a resolution of 1 / n rotation based on the amplitude change of the detection signal, and the rotational position within the 1 / n rotation is obtained with high accuracy based on the phase change of the detection signal.

  FIG. 2 is a block diagram showing the configuration of the arithmetic unit 2, wherein 200 to 203 are detection circuits, 210 to 213 are phase amplitude detection circuits, 22 is an averaging means, and 23 is a phase detection circuit.

  The detection circuits 200 to 201 output excitation signals to the respective channels ch0 to ch3 of the magnetic resolver 1, and the detection signals from the respective channels are input. The detection circuits 200 to 203 take out a change in magnetic characteristics as an amplitude change of the detection signal based on the detection signal and output it to the phase amplitude detection circuits 210 to 213.

Specifically, the detection circuits 200 to 203 perform the following calculations based on the detection signals, and output the results to the phase amplitude detection circuits 210 to 213.
In the detection circuit 200,

In the detection circuit 201,

In the detection circuit 202,

In the detection circuit 203,

  A is an average value of motor rotation of magnetic characteristics, B is an amplitude of fluctuation due to gap change during motor rotation of magnetic characteristics, θ is a rotation angle obtained by detecting a rotation position within one rotation of the motor with resolution 1 / n, θn0 ˜θn3 is a rotation angle within the motor 1 / n rotation detected by each channel ch0 to ch3.

  The phase amplitude detection circuits 210 to 213 calculate the rotation angles θn0 to θn3 within 1 / n rotation for each channel based on the inputs from the detection circuits 200 to 203. Further, an amplitude value is obtained by a mean square of outputs from the detection circuits 200 to 203.

を算出する。 Specifically, the phase amplitude detection circuit 210 performs tan ⁻¹ processing based on the equations (0-1) and (0-2), and calculates the rotation angle θn0 within 1 / n rotation. Further, the phase amplitude detection circuit 210 takes the root mean square of the equations (0-1) and (0-2),

Is calculated.

を算出する。 Similarly, the phase amplitude detection circuit 211 performs tan ⁻¹ processing based on the equations (1-1) and (1-2), and calculates the rotation angle θn1 within 1 / n rotation. Furthermore, the phase amplitude detection circuit 211 takes the root mean square of the equations (1-1) and (1-2),

Is calculated.

を算出する。 The phase amplitude detection circuit 212 performs tan ⁻¹ processing based on the equations (2-1) and (2-2), and calculates the rotation angle θn2 within 1 / n rotation. Further, the phase amplitude detection circuit 212 takes the root mean square of the equations (2-1) and (2-2),

Is calculated.

を算出する。 The phase amplitude detection circuit 213 performs tan ⁻¹ processing based on the equations (3-1) and (3-2), and calculates the rotation angle θn3 within 1 / n rotation. Further, the phase amplitude detection circuit 213 takes the root mean square of the equations (3-1) and (3-2),

Is calculated.

The equation (1-3) is subtracted from the equation (0-3) to obtain 2B · sin θ. Further, 2B · cos θ is obtained by subtracting Expression (3-3) from Expression (1-3). The calculated 2B · sin θ and 2B · cos θ are input to the phase detection circuit 23, and the rotation angle θ within one rotation of the motor is calculated by tan ⁻¹ processing.

  Further, θn0 to θn3 calculated by the phase amplitude detection circuits 210 to 213 are input to the averaging means 22. The averaging means 22 takes the average of θn0 to θn3 and calculates the rotation angle θn within the motor 1 / n rotation. Further, the absolute rotation position of the motor is detected with high accuracy by combining θ calculated by the phase detection circuit 23 and θn calculated by the averaging means 22.

FIG. 3 is a conceptual diagram of the state of the magnetic resolver 1 and detection signals. In FIG. 3, (a) to
A state in which the magnetic resolver 1 is rotated toward (d) is shown. In FIG. 3A, the distance between the resolver stator 1b and the resolver rotor 1a is the smallest in the channel ch1.

  As the resolver rotor 1a rotates, the channel having the smallest distance between the resolver stator 1b and the resolver rotor 1a moves. The channel ch0 in FIG. 3B, the channel 3 in FIG. In (d), the distance is the smallest in channel 2.

  In the channel ch0 to ch3 diagram of FIG. 3, the size of the circle indicates the magnitude of the amplitude B of the fluctuation due to the gap change during the motor rotation of the magnetic characteristics of the detection signal, and the arrow indicates the equation (0) at the rotation angle θn. -1) and formula (0-2), formula (1-1) and formula (1-2), formula (2-1) and formula (2-2), formula (3-1) and formula (3- The vector of 2) is shown.

  In FIG. 3A, since the distance between the resolver stator 1b and the resolver rotor 1a is the smallest in the channel ch1, the size of the circle of the channel ch1 is maximum (that is, the amplitude B of the magnetic characteristics is maximum).

  On the other hand, in the channel ch3 opposite to the channel ch1, the distance between the resolver stator 1b and the resolver rotor 1a is maximized, and the size of the circle of the channel ch3 is minimized (that is, the amplitude B of the magnetic characteristics is minimized).

  In the channels ch0 and ch2, the distance between the resolver stator 1b and the resolver rotor 1a is just about the middle. Therefore, the size of the circles of channels ch0 and ch2 is about the middle of channel 1 and channel 3.

  In FIG. 3B, the distance between the resolver stator 1b and the resolver rotor 1a is minimum for the channel ch0, maximum for the channel ch2, and intermediate between the channels ch1 and ch3. Therefore, the circle size of each channel is maximum for channel ch0, minimum for channel ch2, and intermediate between channels ch1 and ch3.

  In FIG. 3C, the distance between the resolver stator 1b and the resolver rotor 1a is the minimum in the channel ch3, the maximum in the channel ch1, and the middle in the channels ch0 and ch2. Therefore, the circle size of each channel is the maximum for channel ch3, the minimum for channel ch1, and the middle for channels ch0 and ch2.

  In FIG. 3D, the distance between the resolver stator 1b and the resolver rotor 1a is the minimum for the channel ch2, the maximum for the channel ch0, and the middle for the channels ch1 and ch3. Therefore, the circle size of each channel is the maximum for channel ch2, the minimum for channel ch0, and the middle for channels ch1 and ch3.

  Thus, since the amplitude B of the magnetic characteristics changes by one cycle per rotation, the rotation position within one rotation of the motor can be obtained by detecting this change. Note that the sizes of the circles of the channels ch0 to ch3 in FIG. 3 correspond to the equations (0-3), (1-3), (2-3), and (3-3), respectively. .

  FIG. 4 is an image diagram of the operation of the phase detection circuit 23. 4A, the upper diagram shows ch0 amplitude−ch2 amplitude (2B · sin θ), and the lower diagram shows ch1 amplitude−ch3 amplitude (2B · cos θ). FIG. 4B is a diagram showing the relationship between the rotation angle θ and the ch0 amplitude−ch2 amplitude and the ch1 amplitude−ch3 amplitude as vectors.

In the phase detection circuit 23, the calculation result of ch0 amplitude−ch2 amplitude (2B · sin θ) and ch1 amplitude−ch3 amplitude (2B · cos θ) is calculated as the angle formed by the vector tan ⁻¹ as shown in FIG. By processing, the rotation angle θ within one rotation of the motor is obtained.

This embodiment is configured as described above,
A resolver stator 1b having a plurality of salient poles 1b3 arranged in an annular shape around the rotation center axis of the motor, and n pieces arranged in an annular shape facing the resolver stator 1b and decentered from the rotation center axis By providing the resolver rotor 1a having the teeth 1a1 and the calculation unit 2 that calculates the absolute rotational position of the motor based on the signal amplitude and phase of the detection signal of the magnetic resolver 1, the absolute resolution of the motor can be obtained with a single resolver. A rotational position can be detected, and a position detecting device that can be easily miniaturized with a simple configuration can be realized. Further, since the absolute rotational position is detected by a single resolver, it is not necessary to consider magnetic interference between resolvers, and the configuration of the detection unit can be simplified and reduced in cost.

  The configuration for obtaining the rotation angle θn within the rotation of the motor 1 / n is equivalent to the position detection by the conventional normal nX resolver. In the present invention, the resolver rotor 1a is further decentered relative to the resolver stator 1b so that absolute position information within one revolution of the resolver rotor can be detected from a change in the amplitude of the detection signal, and a single magnetic resolver is used. Absolute position detection with high resolution is possible.

  In this embodiment, the magnetic resolver 1 is divided into four channels ch0 to ch3, but the number of divisions is not limited to four. If the total number of teeth 1b1 is increased and the number of divisions is increased, the rotation angle θn can be obtained with higher accuracy.

DESCRIPTION OF SYMBOLS 1 Magnetic resolver 1a Resolver rotor 1a1 tooth | gear 1b Resolver stator 1b1 tooth | gear 1b2 Detection coil 2 Calculation part

Claims (5)

In the position detection device that detects the rotational position of the motor based on the detection signal of the magnetic resolver,
A resolver stator in which a plurality of teeth are formed, each of which is arranged in an annular shape around the rotation center axis of the motor, each of which is wound with a detection coil at a rotation position;
A resolver rotor having n teeth (n is an integer of 2 or more) arranged in an annular shape facing the resolver stator and decentered from the rotation center axis;
An arithmetic unit that calculates the absolute rotational position of the motor based on the signal amplitude and phase of the detection signal;
A position detection device comprising:   The calculation unit calculates a position within one rotation of the motor based on a change in signal amplitude of the detection signal caused by a change in the gap between the resolver rotor and the resolver stator by one period per one rotation of the motor. The position detection device according to claim 1.   The said calculating part calculates the position in 1 / n rotation of the said motor based on the phase of the said detection signal changing for 1 period per said motor 1 / n rotation. 2. The position detection device according to 2. The computing unit is
The detection coil group wound around each of the plurality of teeth of the resolver stator is divided into a plurality of channels by combining adjacent phases, the rotational position of the motor is calculated for each channel, and the calculated values are averaged. The position detection device according to claim 1, wherein   5. The position detection according to claim 1, wherein the total number of teeth formed on the resolver stator is m times the number of channels × the number of phases (m is an integer of 2 or more). apparatus.

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