CN117007086B

CN117007086B - High-precision magnetoelectric encoder and method for detecting absolute angle of magnetoelectric encoder

Info

Publication number: CN117007086B
Application number: CN202311269244.5A
Authority: CN
Inventors: 郝斌; 赵屹涛; 吕迎玺; 闫宪峰; 范浩; 苏跃龙; 岳小云; 乔康定; 张长千; 康健
Original assignee: Shanxi Mechanical And Electrical Design And Research Institute Co ltd
Current assignee: Shanxi Mechanical And Electrical Design And Research Institute Co ltd
Priority date: 2023-09-28
Filing date: 2023-09-28
Publication date: 2023-12-08
Anticipated expiration: 2043-09-28
Also published as: CN117007086A

Abstract

The invention relates to the technical field of encoders, in particular to a high-precision magnetoelectric encoder and a detection method of an absolute angle of the magnetoelectric encoder. The high-precision magneto-electric encoder comprises a second plurality of pairs of pole magnets, a first plurality of pairs of pole magnets and a third plurality of pairs of pole magnets which are coaxially and radially annularly arranged, and a first group of Hall elements, a second group of Hall elements and a third group of Hall elements; the first group of Hall elements are arranged adjacent to the first multi-pair pole magnets and output a first group of detection signals according to magnetic pole signals of the first multi-pair pole magnets; a second group of hall elements disposed adjacent to the second plurality of pairs of pole magnets and outputting a second group of detection signals according to the magnetic pole signals of the second plurality of pairs of pole magnets; and a third group of Hall elements disposed adjacent to the third plurality of pairs of pole magnets and outputting a modified third group of detection signals based on the magnetic pole signals of the third plurality of pairs of pole magnets. According to the invention, the actual angle of the outermost ring magnet is calibrated by acquiring the mechanical angle with certain precision, so that the measurement precision is greatly improved.

Description

High-precision magnetoelectric encoder and method for detecting absolute angle of magnetoelectric encoder

Technical Field

The invention relates to the technical field of encoders, in particular to a high-precision magnetoelectric encoder and a detection method of an absolute angle of the magnetoelectric encoder.

Background

The angular displacement sensor widely adopted by the high-precision servo platform in the current industrial control field comprises a rotary transformer, a photoelectric encoder and a magneto-electric encoder. The magneto-electric encoder mainly comprises a permanent magnet and a magneto-sensitive element. The magnetic sensor can induce the spatial magnetic field change caused by the rotary motion of the permanent magnet through the Hall effect or the magnetic resistance effect, can convert the magnetic field change into the change of a voltage signal, and can achieve the aim of detecting the angular displacement of the rotary component through a subsequent signal processing system. Compared with rotary transformers and photoelectric encoders, the magneto-electric encoder has the advantages of simple structure, high temperature resistance, oil stain resistance, impact resistance, small volume, low cost and the like, and has unique advantages in miniaturized and severe environmental conditions of application places.

The magneto-electric encoder mainly comprises a magnetic signal generating structure and a signal processing circuit, wherein a magnetic signal generating source is called a magnet. The magneto-electric encoder may be classified into a single-pair pole magneto-electric encoder and a multi-pair pole magneto-electric encoder according to the number of magnetic poles of the magnet. The current commonly used multi-pair-pole magnetoelectric encoder adopts radially arranged double multi-pair pole permanent magnets with inner and outer ring pole pairs mutually, wherein the inner ring multi-pair pole permanent magnets are reference magnetic poles, the outer ring multi-pair pole permanent magnets are measurement magnetic poles, after original magnetic field signals are acquired through the reference magnetic poles and the measurement magnetic poles which coaxially rotate, the magnetic pole interval where the measurement magnetic poles are currently located is judged through the position relation between the measurement magnetic poles and the reference magnetic poles, namely the magnetic pole position characteristic value, and then the absolute angle of the magnetoelectric encoder can be obtained through an absolute angle value calculation formula.

In the practical application process, if a magneto-electric encoder with higher precision is needed, for example, when the magneto-electric encoder is used on a large-diameter motor shaft or a large-diameter hollow rotating shaft, the pole pair number of the magnet needs to be increased, and the more the pole pair number is, the higher the precision is. However, when the number of pole pairs of the measuring magnetic pole and the reference magnetic pole is increased to a certain number, the angle measurement of the reference magnetic pole and the measuring magnetic pole has random errors and noise, and the magnetic pole position characteristic values are overlapped in a certain interval, so that the magnetic pole position characteristic values are invalid, the absolute angle of the magneto-electric encoder cannot be obtained, and the requirement of higher precision of the encoder cannot be met.

Disclosure of Invention

In view of the above, the present invention aims to provide a high-precision magnetoelectric encoder, which aims to overcome the problem that in the practical application process of a radial inner-outer ring multi-pair magnetoelectric encoder, the characteristic value of the magnetic pole position is invalid due to the increase of the number of pole pairs, so that the requirement of higher precision of the encoder cannot be realized.

The invention further aims to provide a method for detecting the absolute angle of the high-precision magnetoelectric encoder, which aims to solve the problem that the precision of the magnetoelectric encoder cannot be improved due to the increase of the pole logarithm of the existing inner and outer ring multi-pair-pole magnetoelectric encoder.

In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:

the invention provides a high-precision magneto-electric encoder, which comprises:

a second plurality of pairs of pole magnets, a first plurality of pairs of pole magnets and a third plurality of pairs of pole magnets coaxially and radially arranged in a ring shape, wherein the first plurality of pairs of pole magnets comprises m pairs of magnetic poles and 3.ltoreq.m < 23, the second plurality of pairs of pole magnets comprises n pairs of magnetic poles and 3.ltoreq.n < 23, m is greater than n and is a natural number mutually equal to each other, and the third plurality of pairs of pole magnets comprises p pairs of magnetic poles and p.ltoreq.100;

a first group of hall elements including a first linear hall sensor and a second linear hall sensor, disposed adjacent to the first plurality of pairs of pole magnets, and outputting a first group of detection signals according to magnetic pole signals of the first plurality of pairs of pole magnets;

a second group of hall elements including a third linear hall sensor and a fourth linear hall sensor, disposed adjacent to the second plurality of pairs of pole magnets, and outputting a second group of detection signals according to the magnetic pole signals of the second plurality of pairs of pole magnets;

and a third group of Hall elements including a fifth linear Hall sensor, a sixth linear Hall sensor and a seventh linear Hall sensor, disposed adjacent to the third multi-pair pole magnet, and outputting a modified third group of detection signals according to the magnetic pole signals of the third multi-pair pole magnet.

Further, the output signals of the first linear Hall sensor and the second linear Hall sensor are 90 degrees different in phase; the output signals of the third linear Hall sensor and the fourth linear Hall sensor are 90 degrees different in phase; the output signals of the fifth linear Hall sensor, the sixth linear Hall sensor and the seventh linear Hall sensor are 120 degrees in phase difference.

Still further, the first linear hall sensor is aligned with the third linear hall sensor and the fifth linear hall sensor at one end.

Further, the third plurality of pairs of pole magnets is located on the outermost ring, the second plurality of pairs of pole magnets is located on the innermost ring, and the first plurality of pairs of pole magnets is interposed between the third plurality of pairs of pole magnets and the second plurality of pairs of pole magnets.

Preferably, m and n are prime numbers and mn < 23X 19.

More preferably, the magnetization directions of the first and second pairs of pole magnets are radial or axial, and the initial magnetic pole mounting positions of the first and second pairs of pole magnets have an angle difference.

Still more preferably, the magnetization direction of the third plurality of pairs of pole magnets is radial or axial.

In addition, the invention also provides a detection method of the absolute angle of the magnetoelectric encoder, which is applied to the magnetoelectric encoder with the tricyclic structure, and comprises the following steps:

The first group of detection signals, the second group of detection signals and the modified third group of detection signals are respectively obtained through the first group of Hall elements, the second group of Hall elements and the third group of Hall elements;

respectively performing angle calculation on the first group of detection signals, the second group of detection signals and the modified third group of detection signals to obtain a first electrical angle value, a second electrical angle value and a third electrical angle value;

obtaining a magnetic pole position characteristic value corresponding to the first multi-pair pole magnet according to the magnetic pole pair number m of the first multi-pair pole magnet, the magnetic pole pair number n of the second multi-pair pole magnet, the first electrical angle value and the second electrical angle value;

determining a first magnetic pole interval where the first electric angle value is currently located according to the magnetic pole position characteristic value;

determining an initial mechanical angle formed by the first and second pairs of pole magnets based on the first pole segment, the pole pair number m of the first plurality of pairs of pole magnets, and the first electrical angle value；

Calibrating a third magnetic pole interval where the third electric angle value is currently located according to the initial mechanical angle;

and determining the absolute angle of the magnetoelectric encoder by using the determined third magnetic pole interval, the magnetic pole pair number p of the third plurality of pairs of magnetic poles and the third electrical angle value.

Further, the first set of detection signals includes: the first linear Hall sensor and the second linear Hall sensor output a first detection signal and a second detection signal according to magnetic pole signals of the first multi-pair pole magnets;

the second set of detection signals includes: the third linear Hall sensor and the fourth linear Hall sensor output a third detection signal and a fourth detection signal according to magnetic pole signals of the second multi-pair magnetic body;

the modified third set of detection signals includes: the fifth linear hall sensor, the sixth linear hall sensor and the seventh linear hall sensor output detection signals of d axis and q axis according to the magnetic pole signals of the third multi-pair pole magnet.

Further, the detection signals of d-axis and q-axis output by the fifth linear hall sensor, the sixth linear hall sensor and the seventh linear hall sensor according to the magnetic pole signals of the third multi-pair pole magnet specifically include:

acquiring magnetic pole signals of a third multi-pair pole magnet by a fifth linear Hall sensor, a sixth linear Hall sensor and a seventh linear Hall sensor to obtain an original three-phase Hall signal, wherein the original three-phase Hall signal is a fifth detection signal, a sixth detection signal and a seventh detection signal;

And performing zero drift processing on the obtained original three-phase Hall signals, and outputting detection signals of d axis and q axis.

Still further, the method for processing zero drift of the obtained original three-phase hall signal and outputting d-axis and q-axis detection signals specifically comprises the following steps:

processing zero drift of the collected original three-phase Hall signals according to the following formula (1);

outputting a third set of detection signals of d-axis and q-axis according to the following formula (2):

，

in the method, in the process of the invention,、/>、/>is an original three-phase Hall signal; />Is the signal drift amount; />、/>、/>The three-phase Hall voltage signals after the drift amount is removed; />Is the included angle between the electric angle of the detection signal of any one of the linear Hall sensors in the third group of Hall elements and the horizontal direction, and is +.>、/>Is an output two-phase hall voltage signal.

Further, performing an angle calculation on the first set of detection signals, the second set of detection signals, and the modified third set of detection signals to obtain a first electrical angle value, a second electrical angle value, and a third electrical angle value, where the method specifically includes:

performing A/D conversion on the first group of detection signals, the second group of detection signals and the modified third group of detection signals to obtain a first group of voltage values, a second group of voltage values and a third group of voltage values;

Obtaining the angle interval where the first group of detection signals, the second group of detection signals and the corrected third group of detection signals are located according to the positive and negative properties and the numerical values of the voltage values in the first group of voltage values, the second group of voltage values and the third group of voltage values;

and according to the angle interval, obtaining a first electric angle value, a second electric angle value and a third electric angle value by adopting an arctangent algorithm on the first group of voltage values, the second group of voltage values and the third group of voltage values.

Further, obtaining a magnetic pole position characteristic value corresponding to the first multi-pair pole magnet according to the magnetic pole pair number m of the first multi-pair pole magnet, the magnetic pole pair number n of the second multi-pair pole magnet, the first electrical angle value and the second electrical angle value, specifically including:

calculating the characteristic value of the magnetic pole position according to the following formula：

，

In the method, in the process of the invention,for obtaining the first electrical angle value, +.>To obtain a second electrical angle value.

Further, determining an initial mechanical angle formed by the first and second pairs of pole magnets based on the first pole segment, the pole pair number m of the first plurality of pairs of pole magnets, and the first electrical angle valueThe method specifically comprises the following steps:

the initial mechanical angle is calculated according to the following formula ：

，

In the method, in the process of the invention,for a first electrical angle value->The number of the magnetic pole section currently located, +.>。

Further, calibrating a third magnetic pole interval where the third electric angle value is currently located according to the initial mechanical angle; and then determining the absolute angle of the magnetoelectric encoder by using the determined third magnetic pole interval, the magnetic pole pair number p of the third plurality of pairs of magnetic poles and the third electric angle value, wherein the absolute angle comprises the following specific steps:

and according to the obtained initial mechanical angle, marking a third magnetic pole interval where a third electric angle value is currently located through looking up a table index.

Determining the absolute angle of the magnetoelectric encoder by using the determined third magnetic pole interval, the magnetic pole pair number p of the third plurality of pairs of magnetic poles and the third electrical angle value according to the following formula:

，

in the method, in the process of the invention,for the absolute angle of the magneto-electric encoder output, +.>For a third electrical angle value->The number of the magnetic pole section currently located, +.>。

The invention has the beneficial effects that: according to the invention, the multi-pair pole magnets with the magnetic pole pair number far larger than that of the inner and outer rings are additionally arranged on the outermost ring of the original radial inner and outer ring multi-pair pole magnets, and the actual rotation angle of the outermost ring multi-pair pole magnets is calibrated by utilizing the mechanical angle with certain precision obtained by the original inner and outer ring multi-pair pole magnets, so that the measurement precision of the magnetoelectric encoder is greatly improved, and the actual requirement of angle detection of large-diameter shaft parts is met.

Drawings

In order to more clearly illustrate the embodiments of the application or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the application, and that other drawings can be obtained according to these drawings without inventive faculty for a person skilled in the art.

FIG. 1 illustrates a plan view of a high precision magneto-electric encoder structure in accordance with an exemplary embodiment of the present application;

FIG. 2 illustrates a perspective view of a high precision magneto-electric encoder structure in accordance with an exemplary embodiment of the present application;

FIG. 3 illustrates a flow chart of a method for absolute angle detection of a magneto-electric encoder in accordance with an exemplary embodiment of the present application;

FIG. 4 illustrates a schematic diagram of two linear Hall sensor signal detection in an exemplary embodiment of the application;

FIG. 5 shows a schematic diagram of two linear Hall element detection signals in an exemplary embodiment of the application;

FIG. 6 illustrates a schematic diagram of three linear Hall sensor signal detection in an exemplary embodiment of the present application;

FIG. 7 shows a schematic diagram of three linear Hall sensor detection signals in an exemplary embodiment of the application;

FIG. 8 shows a schematic diagram of zero drift cancellation using three Hall signals in an exemplary embodiment of the application;

FIG. 9 shows a schematic diagram of synthesizing a two-phase Hall signal in an exemplary embodiment of the application;

fig. 10 is a diagram showing the number of magnetic pole position feature values according to an exemplary embodiment of the present application.

Detailed Description

Example embodiments are described more fully below with reference to the accompanying drawings. However, the exemplary embodiments may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. These embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar parts, and thus a repetitive description thereof will be omitted.

Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the application.

It will be understood that, although the terms first, second, third, etc. may be used herein to describe various components, these components should not be limited by these terms. These terms are only used to distinguish one from another. As used herein, the term "and/or" includes all combinations of any and one or more of the associated listed items.

Those skilled in the art will appreciate that the drawings are schematic representations of example embodiments only. The modules or flow paths in the drawings are not necessarily required to practice the application and therefore should not be taken to limit the scope of the application.

The existing radial inner and outer ring pole pair mutually-quality multi-pair magneto-electric encoder inevitably encounters the situation of large-diameter shafts in the practical application process. In this case, for a plurality of pairs of pole magnets of the radially inner and outer rings fitted over the large diameter shaft, it is necessary to correspondingly increase the pole pair number of its own magnets. Under ideal conditions, namely under the conditions that the inner ring and the outer ring are provided with a plurality of pairs of pole magnets without installation errors and noise influence, the inner ring and the outer ring are provided with a plurality of pairs of pole magneto-electric encoders with mutually-quality pole pairs, the rotation angles of large-diameter shaft parts can be completely measured, but the technical staff of the application find that in the practical application process, when the pole pairs of the inner ring and the outer ring are increased to a certain number, detection signals obtained through the Hall element are completely consistent in a certain angle interval, which leads to the fact that the inner ring and the outer ring are provided with mutually-quality pole pairs of the plurality of pairs of pole magneto-electric encoders with mutually-quality pole pairs, the rotation angles of the large-diameter shaft parts cannot be measured, and therefore the measurement accuracy of the magneto-electric encoder is invalid.

In order to solve the above problems, the present application provides a high-precision magneto-electric encoder. The high-precision magneto-electric encoder is characterized in that a plurality of pairs of pole magnets with the pole pair number far larger than that of the inner and outer rings are additionally arranged on the radial outermost ring of the original inner and outer ring pairs of pole magnets, and the actual rotation angle of the outermost ring pairs of pole magnets is calibrated by utilizing the mechanical angle with certain precision obtained by the original inner and outer ring pairs of pole magnets, so that the measurement precision of the magneto-electric encoder is greatly improved, and the actual requirement of angle detection of large-diameter shaft parts is met. The technical scheme of the present application will be described in detail below with reference to the accompanying drawings.

Fig. 1 shows a plan view of a high-precision magneto-electric encoder structure of an embodiment of the present application.

Fig. 2 shows a perspective view of a high-precision magneto-electric encoder structure of an embodiment of the present application.

As shown in fig. 1 and 2, the present application provides a high-precision magneto-electric encoder 100, including: a second plurality of pole magnets 120, a first plurality of pole magnets 110, and a third plurality of pole magnets 130 coaxially and radially annularly disposed in a first spatial plane. The first plurality of pairs of pole magnets 110 includes m pairs of poles and 3.ltoreq.m < 23, the second plurality of pairs of pole magnets 120 includes n pairs of poles and 3.ltoreq.n < 23, m is greater than n and mn < 23 x 19, and the third plurality of pairs of pole magnets 130 includes p pairs of poles and p.gtoreq.100. P may be 100, 200, 300, 400, 500, 600, 700, 800, or even more, the greater the number of P, the greater the accuracy of the final magneto-electric encoder. For example, according to some embodiments, m and n are prime numbers and are mutually prime. As shown in fig. 1 and 2, m is 5, n is 3, and p is 100 in the present embodiment, but the present application is not limited thereto.

According to an example embodiment of the application, the third plurality of pairs of pole magnets 130 are located at the outermost ring, the second plurality of pairs of pole magnets 120 are located at the innermost ring, and the first plurality of pairs of pole magnets 110 are interposed between the third plurality of pairs of pole magnets 130 and the second plurality of pairs of pole magnets 120. For convenience of description, the outer ring, the middle ring, and the inner ring correspond to the third plurality of pairs of pole magnets 130, the first plurality of pairs of pole magnets 110, and the second plurality of pairs of pole magnets 120, respectively. The pole pair number m of the first plurality of pole magnets 110 is greater than the pole pair number n of the second plurality of pole magnets 120. This is because the diameter of the intermediate ring is larger than the diameter of the inner ring, and the number of intermediate ring magnet pole pairs is larger than the number of inner ring magnet pole pairs in order to make the magnet size uniform.

The application defines the pole pair number m of the middle ring and the pole pair number n of the inner ring, so that effective detection signals can be obtained in the practical application process, and the detection signals are prevented from overlapping in a certain angle interval.

According to some embodiments of the application, the magnetization direction of the first plurality of pairs of pole magnets 110 may be radial or axial. In the embodiment shown in fig. 1, 2, the magnetization direction of the first plurality of pairs of pole magnets 110 is set to be axial. The magnetization direction of the second plurality of pole magnets 120 may also be radial or axial. In the embodiment shown in fig. 1 and 2, the magnetization direction of the second plurality of pairs of pole magnets 120 is set to be axial. Similarly, the magnetization direction of the third plurality of pole magnets 130 may be radial or axial. In the embodiment shown in fig. 1 and 2, the magnetization direction of the third plurality of pairs of pole magnets 130 is set to be axial. The present application does not limit the magnetization direction.

The first, second, and third pluralities of pole magnets 110, 120, 130 may each be formed of a plurality of pole pairs bonded, but are not limited thereto. According to the embodiment of the application, the magnets can be made of neodymium iron boron permanent magnet materials, and a plurality of magnets can be attached to the base plate or directly attached to the end part of the rotating shaft. According to some embodiments, a plurality of magnets may be disposed on the support plate. The support plate may have a ring-shaped structure, and the second, first and third pairs of pole magnets 120, 110 and 130 may be sequentially disposed along a circumferential normal direction of the inner hole thereof. The fixing means may be glue joint, and when the fixing means is installed, there is an installed angle difference between the initial poles of the first and second pairs of pole magnets 110 and 120.

As shown in fig. 1 and 2, the high-precision magnetoelectric encoder 100 further includes a first set of hall elements, a second set of hall elements, and a third set of hall elements for detecting magnetic signals generated by the plurality of pairs of pole magnets.

A first group of hall elements including a first linear hall sensor 111 and a second linear hall sensor 112 are disposed adjacent to the first plurality of pairs of pole magnets 110, and output a first group of detection signals according to magnetic pole signals of the first plurality of pairs of pole magnets 110. The output signals of the first linear hall sensor 111 and the second linear hall sensor 112 are 90 degrees out of phase.

A second group of hall elements including a third linear hall sensor 121 and a fourth linear hall sensor 122 are disposed adjacent to the second plurality of pairs of pole magnets 120, and output a second group of detection signals according to the magnetic pole signals of the second plurality of pairs of pole magnets 120. The output signals of the third linear hall sensor 121 and the fourth linear hall sensor 122 are out of phase by 90 degrees.

A third group of hall elements including a fifth linear hall sensor 131, a sixth linear hall sensor 132, and a seventh linear hall sensor 133 are disposed adjacent to the third plurality of pairs of pole magnets 130, and output a modified third group of detection signals according to the magnetic pole signals of the third plurality of pairs of pole magnets 130. The output signals of the fifth, sixth and seventh linear hall sensors 131, 132 and 133 are phase-separated by 120 degrees.

According to some embodiments, in the above encoder structure, the first and third linear hall sensors 111 and 121 and the fifth linear hall sensor 131 are aligned at one end; and the encoder is operated such that the first, second and third pluralities of pole magnets 110, 120 and 130 rotate along with the rotation shaft, while the three sets of hall elements remain stationary.

Fig. 3 shows a flow chart of a method for detecting absolute angles of a magneto-electric encoder according to an embodiment of the application.

The application also provides a method for detecting the absolute angle of the magnetoelectric encoder, which is shown in fig. 3 and comprises the following steps:

in step S310, the first set of detection signals, the second set of detection signals, and the modified third set of detection signals are obtained by the first set of hall elements, the second set of hall elements, and the third set of hall elements, respectively.

The magneto-electric encoder provided by the application comprises an inner ring, a middle ring and an outer ring which are coaxially and radially sequentially annularly arranged, wherein the magnetic pole pairs of the inner ring and the middle ring are mutually similar, and the three groups of magnets are coaxially arranged on a rotating shaft and are isolated by adopting an isolation means so as to prevent magnetic field coupling. The magnetic field around the three sets of multi-pair pole magnets appears as a sinusoidal distribution in the circumferential direction.

The two linear Hall sensors in the first group of Hall elements and the second group of Hall elements which are respectively arranged corresponding to the plurality of pairs of pole magnets of the middle ring and the inner ring are arranged at an included angle of 90 degrees. The principle of detecting the magnetic signal of the inner or intermediate ring magnet using two linear hall sensors is described below in connection with fig. 4 and 5.

Fig. 4 shows a schematic diagram of signal detection of two linear hall sensors in an embodiment of the application.

Fig. 5 shows a schematic diagram of detection signals of two linear hall elements in an embodiment of the present application.

The magnet rotates along with the rotating shaft for one circle, the magnetic field change at any point in the space where the magnet is positioned is regular, the change can be converted into sine and cosine electric signals by using two linear Hall sensors with the electric angle difference of 90 degrees, and the frequency of the electric signal change is the same as the frequency of the magnetic pole rotation. As shown in fig. 4 and 5, for the 3-pole inner ring magnet, the third linear hall sensor 121 and the fourth linear hall sensor 122 detect three periods of sine and cosine signals, respectively, i.e., a set of detection signals, for one revolution of the magnet. The first set of detection signals is obtained by a first set of hall elements arranged in an intermediate loop. A second set of detection signals is obtained by a second set of Hall elements arranged in the inner ring.

In the practical process, the two hall arrangement modes are usually arranged by adopting an included angle with an electric angle of 90 degrees. However, the two hall method is difficult to eliminate errors due to machining or assembly, and also difficult to suppress for harmonic errors existing in the magnetic field. The number of the Hall is increased or the Hall is symmetrically arranged, and the main effect is that the mechanical error is reduced by using a symmetrical counteracting mode, and meanwhile, harmonic components can be counteracted. Therefore, the three-Hall arrangement mode is arranged on the multi-pair pole magnet of the outer ring, and meanwhile, the three Hall electric angles can obtain higher calculation precision when the electric angles are 120 degrees.

The third group of Hall elements are arranged adjacent to the outer ring multi-pair pole magnets, and three linear Hall sensors are arranged at intervals at an included angle of 120 DEG in electrical angle. The principle of detecting magnetic signals of the outer ring multi-pair pole magnets by three linear hall sensors is described below in connection with fig. 6-9.

Fig. 6 shows a schematic diagram of three linear hall sensor signal detection in an embodiment of the application.

Fig. 7 shows a schematic diagram of detection signals of three linear hall sensors in an embodiment of the present application.

Fig. 8 shows a schematic diagram of zero drift cancellation using three hall signals in an embodiment of the application.

Fig. 9 shows a schematic diagram of synthesizing a two-phase hall signal in an embodiment of the application.

According to the principle, it is easy to know that the magnetic field change can be converted into sine and cosine electric signals by using three linear Hall sensors with 120-degree electric angle difference. As shown in fig. 6 and 7, for a group of multi-pole magnets having 6 pairs of poles in the outer ring, the magnets rotate one revolution, and the fifth, sixth and seventh linear hall sensors 131, 132 and 133 detect six periods of sine and cosine signals, respectively, that is, original three-phase hall signals. The original three-phase Hall signals are respectively adopted in FIG. 8 、/>、/>Make representation and +.>A detection signal corresponding to the fifth linear hall sensor 131;a detection signal corresponding to the sixth linear hall sensor 132; />Corresponds to the detection signal of the seventh linear hall sensor 133.

Original three-phase Hall signal due to problems of Hall arrangement, mechanical assembly and the like、/>、/>Superimposed with some error signal, the component of the phase difference of 90 DEG between the two phases is synthesized->、/>At this time, zero drift occurs with a high probability.

Therefore, the acquired original three-phase hall signal needs to be subjected to zero drift treatment, and as shown in fig. 8, the zero drift treatment is specifically calculated according to the following formula:

，

in the method, in the process of the application,、/>、/>is an original three-phase Hall signal; />Is the signal drift amount; />、/>、/>And the three-phase Hall voltage signals after the drift amount are removed.

Then synthesizing the three-phase Hall voltage signals without zero drift into two-phase 90 DEG phase difference、/>The signals, as shown in fig. 9, are specifically converted using the following formula:

，

in the method, in the process of the application,is the included angle between the electric angle of the detection signal of any one of the linear Hall sensors in the third group of Hall elements and the horizontal direction, and is +.>、/>The two-phase hall voltage signal is the corrected third group detection signal.

At this time, the corrected third group of detection signals with the two-phase difference of 90 ° can be approximately regarded as sine and cosine detection signals acquired by the two linear hall sensors. For convenience of subsequent text, the application regards the third group of hall elements as two linear hall sensors arranged at an electrical angle of 90 °.

Of course, the inner ring and the middle ring of the application can also adopt a three-Hall sensor arrangement mode to improve the measurement precision, and then the acquired detection signals are converted into detection signals with the two-phase difference of 90 degrees by utilizing the formula.

In step S320, the first set of detection signals, the second set of detection signals, and the modified third set of detection signals are respectively subjected to angle calculation to obtain a first electrical angle value, a second electrical angle value, and a third electrical angle value.

After the sine and cosine signals are obtained by using the linear Hall sensor, a digital voltage value with a certain number of bits can be obtained through an A/D conversion circuit. That is, the first set of voltage values, the second set of voltage values, or the third set of voltage values are obtained after a/D conversion is performed on the first set of detection signals, the second set of detection signals, or the modified third set of detection signals, respectively. The digital voltage value at this time has a certain relation with the measured angle value of the encoder, but is not the measured angle value of the encoder, and an angle calculation is required.

For the signals of each group of magnetic poles, the positions of the two linear Hall sensors are different by 90 degrees in space, so that the sine and cosine signals output by the two linear Hall sensors are different by 90 degrees in phase. In this case, the phase-advanced signal is regarded as a sine signal, and the phase-retarded signal is regarded as a cosine signal. The tangent value of the point signal can be obtained by dividing the sine signal by the cosine signal, and then the electric angle value of the point can be obtained by performing arctangent processing on the tangent value.

Since the interval of the tangent function is [ -90 DEG, 90 DEG ], the direct angle calculation according to the above procedure will lead to the interval error of the angle calculation. Therefore, the problem of interval error needs to be solved by an interval partitioning method, that is, an electrical angle interval where the first set of detection signals or the second set of detection signals or the modified third set of detection signals are located is obtained according to the positive and negative polarities and the numerical magnitudes of the voltage values in the first set of voltage values or the second set of voltage values or the third set of voltage values.

Taking the angular resolution of a set of magnetic poles as an example, 360 ° of the set of magnetic poles may be divided into 8 equal-length sections at 45 ° intervals. The position of the Hall signal at the moment is judged by judging the magnitude and the positive and negative of the voltage values detected by the two linear Hall elements, and the realization principle of the inter-partition arc tangent algorithm is shown in the following table 1. Wherein VA and VB are linear Hall detection signals with phase difference of 90 degrees.

TABLE 1 division of angle intervals

，

Through the division of the angle interval, the conversion from the signal collected by the Hall element to the angle signal can be realized, and the range of the converted electric angle interval is [0 DEG, 360 DEG ].

According to the magneto-electric encoder, the angle interval where the first group of detection signals, the second group of detection signals and the modified third group of detection signals are located can be obtained according to the positive and negative polarities and the numerical values of the voltage values in the first group of voltage values, the second group of voltage values and the third group of voltage values. According to the angle interval, the first electrical angle value, the second electrical angle value and the third electrical angle value can be obtained by adopting an arctangent algorithm on the first group of voltage values or the second group of voltage values or the third group of voltage values according to the table 1. The electric angle value herein refers to an electric angle value of a single pair of magnetic pole periods, which is simply referred to as a single period electric angle value.

In the angle measurement process, three groups of multiple pairs of pole magnets simultaneously rotate along with the rotating shaft, and the linear Hall element is kept static and is used for receiving a magnetic field signal generated by the magnetic poles in the rotating process. The electric angle value of the single-pair magnetic pole period of the measured magnet can be obtained by processing the induction signal of the linear Hall through the arctangent table lookup method. After the single-period electric angle value is determined, the magnetic pole interval where the single-period electric angle value is located is determined, and then the absolute angle value detected by the magneto-electric encoder can be finally obtained.

In the method for detecting the absolute angle of the magneto-electric encoder, an initial mechanical angle with certain precision is determined according to two groups of detection signals of the inner ring magnet and the middle ring magnet, then the initial mechanical angle is used for calibrating a specific magnetic pole interval of the outer ring magnet, in which the single-period electric angle value of the outer ring magnet is currently positioned, and finally the mechanical angle of the magneto-electric encoder is calculated by using a calculation formula of the mechanical angle value. The mechanical angle referred to in the present application is also referred to as absolute angle.

Next, the present application will be described in detail on how to obtain an initial mechanical angle with a certain accuracy.

In the present application, the calculation of the initial mechanical angle may be calculated according to the following formula:

wherein (1)>Or (b)

Wherein (1)>，

In the method, in the process of the application,for the initial mechanical angle>For single period electrical angle values measured by a linear hall sensor on the first multi-pair pole magnet 110,/v>Is->A first magnetic pole section; m is the pole pair number of the first plurality of pole magnets 110. Here, a->Also referred to as a first electrical angle value.

For the encoder shown in fig. 1, there is an angular difference between the initial pole mounting positions of the inner ring magnet and the intermediate ring magnetThe initial mechanical angle can also be expressed as:

wherein (1)>Or (b)

Wherein (1)>，

In the method, in the process of the application,for the initial mechanical angle>For single period electrical angle values measured by a linear hall sensor on the second plurality of pairs of pole magnets 120 +.>Is->The second magnetic pole section is positioned; n is the pole pair number of the second plurality of pole magnets 120.Also referred to as a second electrical angle value.

Therefore, on the basis that the first electrical angle value or the second electrical angle value has been obtained, the initial mechanical angle value can be calculated according to the above-described formula (3) -formula (6) as long as the corresponding magnetic pole section thereof is determined.

In step S330, a first magnetic pole section corresponding to the first electrical angle value is determined according to the magnetic pole pair m of the first plurality of pairs of pole magnets 110, the magnetic pole pair n of the second plurality of pairs of pole magnets 120, the first electrical angle value, and the second electrical angle value.

When the linear hall sensors on the first plurality of pairs of pole magnets 110 measure the same single-period electrical angle value twice, the two single-period electrical angle values measured by the linear hall sensors on the corresponding second plurality of pairs of pole magnets 120 are different, so that the number of pole pairs, i.e. the pole intervals, where the single-period electrical angle of the first plurality of pairs of pole magnets 110 is currently located can be distinguished.

With the magnetic structure of the magneto-electric encoder provided by the application, in the case that the greatest common divisor of the magnetic pole pairs m, n of the first and second pluralities of pole magnets 110, 120 is 1, i.e. mutual quality, each pair of poles of the first plurality of pole magnets 110 has a corresponding non-repeating magnetic pole portion of the second plurality of pole magnets 120. The following is a proof method.

Assuming that there is a positive integer N _m1 ，N _m2 ，N _n1 ，N _n2 ，N _m1 ≠N _m2 The following formula is established:

，

wherein,for single period electrical angle values measured by linear hall sensors on the first plurality of pairs of pole magnets 110, N _m1 ，N _m2 ∈[1，m]For two measurements ∈>The corresponding first magnetic pole interval; />For single period electrical angle values, N, measured by linear Hall sensors on the second plurality of pairs of pole magnets 120 _n1 ，N _n2 ∈[1，n]For two measurements ∈>The corresponding second magnetic pole section;is the difference in mounting angle between the starting points of a pair of poles in the two sets of magnets.

Subtracting the two formulas in the formula (7) can obtain:

，

since m and N are mutually equal, and N _m1 N _m2 ∈[1，m-1]Therefore, equation (8) is constantly not established, i.e., equation (7) is constantly not established.

Further from equation (8):

，

equation (9) for any different N _m And corresponding N thereof _n Neither is true. That is, equation (9) is not true for the magnetic pole pairs in the different first plurality of pole magnets 110 and the corresponding magnetic pole pairs in the second plurality of pole magnets 120. It can be demonstrated that when the linear hall sensors on the first plurality of pairs of pole magnets 110 measure the same single-cycle electrical angle value, the two single-cycle electrical angle values measured by the linear hall sensors on the corresponding second plurality of pairs of pole magnets 120 are different. Thus, the magnetic pole section where the first angle value is currently located can be resolved by the positional relationship between the first plurality of pairs of pole magnets 110 and the second plurality of pairs of pole magnets 120.

Is obtained by combining the formula (3) and the formula (5):

，

it can be seen that the right value of the expression is a single-period electric angle value without the current sampling point, the magnitude of the value is only dependent on the magnetic pole interval numbers of the inner ring and the middle ring, and the number group of the magnetic pole intervals is [ ]，/>) In the fixed case, the value is a constant, and the constant is the characteristic value of the mapping interval number group.

Is provided withAnd defines it as a magnetic pole position feature value. As can be seen from the equation (10), when the number of the pole pairs of the first and second pluralities of pole magnets 110 and 120 is unchanged, the characteristic value of the pole position is unchanged. When at least one of them is changed, the magnetic pole position characteristic value is also changed, otherwise, the equation (9) is established, and contradicts the precondition of mutual quality of the magnetic pole pairs. Thus, the current electrical angle can be determined by calculating the magnetic pole position characteristic valueAnd a magnetic pole section.

When (when)If not equal to 0, that is, if the magnetic pole starting points of a certain pair of the inner ring and the intermediate ring magnet are not overlapped, the magnetic pole position characteristic values λ cannot be overlapped by changing the coordinate starting points, and m+n different values are shared. As shown in fig. 10.

Fig. 10 is a schematic diagram showing the number of values of the magnetic pole position characteristic values according to the embodiment of the application.

In fig. 10, the middle ring magnet has m pairs of poles, m being 5, so 5 boxes are used to represent a planar expansion of 5 pairs of poles. The inner ring magnet has n pairs of poles, n takes 3, and after the inner ring magnet is subjected to plane expansion, 3 vertical lines are introduced into 5 boxes. Since θx+.0, the total of m+n+1 lines will be divided into m+n shares. That is, there are 8 different values of the position characteristic value for an encoder of one 5-pole magnet and one 3-pole magnet. By analogy, for an encoder with 23 pairs of pole magnets and 19 pairs of pole magnets, there are 42 different values for the pole position characteristic values.

After the inner ring and the middle ring magnet are installed,if the value of m+n is already determined, then the value of m+n is already constant. From the number m of the magnetic pole pairs of the first plurality of pole magnets 110 and the number n of the magnetic pole pairs of the second plurality of pole magnets 120, and the first electrical angle value and the second electrical angle value, a magnetic pole position characteristic value corresponding to the first plurality of pole magnets 110 can be determined. Taking the magneto-electric encoder structure shown in fig. 1 as an example,/->When=40° the rotation direction of the magnets is clockwise, the magnetic pole position characteristic value obtained by calibration and the magnetic pole section on the corresponding first plurality of pairs of pole magnets 110 are shown in table 2.

Table 2 corresponding relationship between lambda value and magnetic pole interval of first multi-pair pole magnet

，

The identification of the magnetic pole position can be completed through the corresponding relation between lambda and the magnetic pole section in table 2, namely, the first magnetic pole section where the first electric angle value is currently located is calculated according to the characteristic value of the magnetic pole position.

In step S340, an initial mechanical angle formed by the first and second pairs of pole magnets 110, 120 is determined based on the first pole segment, the number m of pole pairs of the first plurality of pole magnets 110, and the first electrical angle value 。

After determining the first electrical angle value and the first pole section in which the electrical angle value is located, the initial mechanical angle formed by the first plurality of pairs of pole magnets 110 and the second plurality of pairs of pole magnets 120 may be obtained according to equation (3).

In step S350, the third magnetic pole section where the third electrical angle value is currently located is calibrated according to the initial mechanical angle.

On the premise that the initial mechanical angle is obtained, the initial mechanical angle can be used for calibrating a third magnetic pole interval where a third electric angle value of the outer ring magnet is currently located.

In the present application, the third magnetic pole sectionThe following correspondence exists with the initial mechanical angle:

，

therefore, an index table is established according to the corresponding relation between the initial mechanical angle and the third magnetic pole section, the first column of the index table is the value of the initial mechanical angle, and the second column is the section number of the third magnetic pole section corresponding to the initial mechanical angle. Because the initial mechanical angle is an absolute angle, the value range is [0 DEG, 360 DEG ], the first row of the first row has a first behavior number of 0 and the last row of the first row has a last behavior number of 360.

By way of example, assuming a pole pair number of 5 for the outer ring multi-pair magnets, the initial mechanical angle and corresponding third pole interval obtained by calibration are shown in table 3.

TABLE 3 index Table of the relationship between pole intervals in the initial mechanical Angle and third multiple pairs of pole magnets

，

Therefore, only the degree of the initial mechanical angle is determined, and the numerical value of the third magnetic pole interval can be obtained by looking up a table. But it should be noted that: in the case of tabulation, the number of rows of the column of the initial mechanical angle needs to be set to be far greater than the number of pole pairs of the third plurality of pairs of pole magnets 130, so that the accuracy of the magnetoelectric encoder can be greatly improved.

For example: in table 3, the number of rows of the column of the initial mechanical angle is 360 rows, and the number of pole pairs of the third plurality of pole magnets 130 is only 5, satisfying the requirement of being far larger than the number of pole pairs of the third plurality of pole magnets 130.

Assuming that the number of pole pairs of the third plurality of pairs of pole magnets 130 is 360, the number of rows of the column of the initial mechanical angle may be set to 360 rows, i.e., each degree of the initial mechanical angle corresponds to a pole interval of one third plurality of pairs of pole magnets 130; similarly, the number of rows in the column of the initial mechanical angle may be set to 3600 rows, such that every 0.1 degrees of the initial mechanical angle corresponds to a pole segment of the third plurality of pairs of pole magnets 130, and such that the accuracy of the magneto-electric encoder is improved by a factor of 10. Accordingly, the precision can be improved by 20 times, 30 times, even 100 times or more, which is the meaning that the number of lines is far greater than the number of pole pairs.

In step S360, using the determined third magnetic pole interval, the absolute angle of the magnetoelectric encoder is determined according to the following formula by the number p of the magnetic pole pairs of the third plurality of pairs of the magnetic poles 130 and the third electrical angle value:

，

Finally, it should be noted that: the foregoing description is only illustrative of the preferred embodiments of the present invention, and although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described, or equivalents may be substituted for elements thereof, and any modifications, equivalents, improvements or changes may be made without departing from the spirit and principles of the present invention.

Claims

1. High accuracy magnetoelectric encoder, its characterized in that includes:

a second plurality of pairs of pole magnets, a first plurality of pairs of pole magnets and a third plurality of pairs of pole magnets arranged coaxially and radially in a ring shape, wherein the first plurality of pairs of pole magnets comprises m pairs of magnetic poles and 3.ltoreq.m < 23, the second plurality of pairs of pole magnets comprises n pairs of magnetic poles and 3.ltoreq.n < 23, m is greater than n and m and n are prime numbers mutually prime with each other while mn < 23 x 19, and the third plurality of pairs of pole magnets comprises p pairs of magnetic poles and p.ltoreq.100;

2. The high precision magneto-electric encoder of claim 1, wherein: the output signals of the first linear Hall sensor and the second linear Hall sensor are 90 degrees different in phase; the output signals of the third linear Hall sensor and the fourth linear Hall sensor are 90 degrees different in phase; the output signals of the fifth linear Hall sensor, the sixth linear Hall sensor and the seventh linear Hall sensor are 120 degrees in phase difference.

3. The high precision magneto-electric encoder of claim 1, wherein: the first linear hall sensor is aligned with the third linear hall sensor and the fifth linear hall sensor at one end.

4. The high precision magneto-electric encoder of claim 1, wherein: the third plurality of pairs of pole magnets is located on the outermost ring, the second plurality of pairs of pole magnets is located on the innermost ring, and the first plurality of pairs of pole magnets is interposed between the third plurality of pairs of pole magnets and the second plurality of pairs of pole magnets.

5. The high precision magneto-electric encoder of claim 1, wherein: the magnetization directions of the first multi-pair pole magnets and the second multi-pair pole magnets are radial or axial, and the initial magnetic pole installation positions of the first multi-pair pole magnets and the second multi-pair pole magnets have angle differences.

6. The high precision magneto-electric encoder of claim 1, wherein: the magnetization direction of the third plurality of pairs of pole magnets is radial or axial.

7. A method for detecting an absolute angle of a magneto-electric encoder, which is applied to the high-precision magneto-electric encoder as claimed in any one of claims 1 to 6, comprising:

8. The method for detecting an absolute angle of a magneto-electric encoder according to claim 7, wherein: the first set of detection signals includes: the first linear Hall sensor and the second linear Hall sensor output a first detection signal and a second detection signal according to magnetic pole signals of the first multi-pair pole magnets;

9. The method for detecting the absolute angle of a magneto-electric encoder according to claim 8, wherein: the fifth linear hall sensor, the sixth linear hall sensor and the seventh linear hall sensor output d-axis and q-axis detection signals according to magnetic pole signals of the third multi-pair pole magnet, and specifically include:

10. The method for detecting the absolute angle of a magneto-electric encoder according to claim 9, wherein: the method for processing zero drift of the obtained original three-phase Hall signal outputs detection signals of d axis and q axis, and specifically comprises the following steps:

，

11. The method for detecting the absolute angle of a magneto-electric encoder according to claim 10, wherein: performing angle calculation on the first group of detection signals, the second group of detection signals and the modified third group of detection signals to obtain a first electrical angle value, a second electrical angle value and a third electrical angle value, wherein the method specifically comprises the following steps:

12. The method for detecting an absolute angle of a magneto-electric encoder according to claim 11, wherein: obtaining a magnetic pole position characteristic value corresponding to the first multi-pair pole magnet according to the magnetic pole pair number m of the first multi-pair pole magnet, the magnetic pole pair number n of the second multi-pair pole magnet, the first electrical angle value and the second electrical angle value, wherein the magnetic pole position characteristic value specifically comprises:

，

13. The magneto-electric encoder of claim 12, absoluteThe angle detection method is characterized in that: determining an initial mechanical angle formed by the first and second pairs of pole magnets based on the first pole segment, the pole pair number m of the first plurality of pairs of pole magnets, and the first electrical angle value The method specifically comprises the following steps:

the initial mechanical angle is calculated according to the following formula：

，

14. The method for detecting an absolute angle of a magneto-electric encoder according to claim 13, wherein: calibrating a third magnetic pole interval where the third electric angle value is currently located according to the initial mechanical angle; and then determining the absolute angle of the magnetoelectric encoder by using the determined third magnetic pole interval, the magnetic pole pair number p of the third plurality of pairs of magnetic poles and the third electric angle value, wherein the absolute angle comprises the following specific steps:

according to the obtained initial mechanical angle, a third magnetic pole interval where a third electric angle value is currently located is marked by looking up an index table;

，