Inductance type absolute position encoder and motor

Abstract

The invention relates to an inductance type absolute position encoder and a motor. The encoder comprises an excitation module, an inductance module, a detection module, an analog-to-digital conversion module and an absolute position calculation unit. The inductance module comprises a stator and a rotor, the rotor comprises inner and outer base coils, and the stator comprises an excitation coil and inner and outer induction coils; the inner group of induction coils and the outer group of induction coils of the inner induction coil and the outer induction coil are respectively composed of three induction coils with the phase difference of 120 degrees; and the absolute position calculation unit is used for carrying out dimension reduction processing on the input digital signals through matrix transformation so as to eliminate errors and output absolute position information. According to the invention, the three-coil internal and external combination mode with the phase difference of 120 degrees is adopted, and the coupling influence of the internal and external coils is eliminated through matrix transformation, so that absolute position information with higher precision and resolution can be obtained through electromagnetic induction.

Description

Technical Field

[0001] The present application relates to the technical field of encoders, and in particular to an inductive absolute position encoder and a motor. Background Art

[0002] The inductive position encoder is a key device used to measure the rotational position of an object. Through the principle of electromagnetic induction, it converts the displacement of the rotating parts into precise induced voltage changes to achieve high-precision position measurement. It has been widely used in industrial automation, intelligent manufacturing, robotics, and automobiles.

[0003] Traditional incremental encoders can only provide relative position information, and the system needs to be reset after power failure, which easily leads to cumulative errors. In addition, the mutual inductance coupling of the encoder coils will also interfere with the measurement results. Therefore, due to the influence of the mutual inductance coupling and errors of the encoder coils, the current inductive position encoder still has the problem of low accuracy and resolution.

[0004] With regard to the problem of low accuracy and resolution of inductive position encoders in related technologies, no effective solution has been proposed so far. Summary of the invention

[0005] Based on this, it is necessary to provide an inductive absolute position encoder and a motor that can improve the accuracy and resolution of the inductive position encoder in order to solve the above technical problems.

[0006] In a first aspect, an inductive absolute position encoder is provided in this embodiment, comprising an excitation module, an inductance module, a detection module, an analog-to-digital conversion module, and an absolute position calculation unit;

[0007] The inductor module includes a stator and a rotor, the rotor includes inner and outer base coils, and the stator includes an excitation coil and inner and outer induction coils; the inner and outer induction coils of the inner and outer induction coils are each composed of three induction coils with a phase difference of 120 degrees;

[0008] The excitation module is used to generate an excitation signal and apply it to the excitation coil to generate a magnetic field in the stator, and generate an induction signal through electromagnetic induction of the inner and outer base coils and the inner and outer induction coils;

[0009] The detection module is used to demodulate the induction signal generated by the inductance module;

[0010] The analog-to-digital conversion module is used to convert the signal processed by the detection module into a digital signal;

[0011] The absolute position calculation unit is used to perform dimensionality reduction processing on the input digital signal through matrix transformation to eliminate errors and output absolute position information.

[0012] In some of the embodiments, the number of periods of the outer group of induction coils is not divisible by the number of periods of the inner group of induction coils.

[0013] In some of the embodiments, in the absolute position calculation unit, the digital signal is subjected to dimension reduction and error elimination processing by Clarke transform to obtain linearly changing angle information; and the absolute position information within a single rotation period is determined based on the number of periods of the internal and external induction coils and the angle information.

[0014] In some embodiments, the excitation signal generated by the excitation module is a sine wave signal, and the detection module is used to perform envelope detection on the induced signal.

[0015] In some of the embodiments, the excitation module includes a crystal oscillator for providing a high-frequency sinusoidal wave signal.

[0016] In some of the embodiments, the detection module includes a diode;

[0017] The unidirectional conductivity of the diode is used to perform envelope detection on the induced signal, so as to retain the positive half cycle of the induced signal and extract the original signal that varies with the carrier amplitude.

[0018] In some of the embodiments, the excitation module and the detection module are arranged independently from the absolute position calculation unit.

[0019] In some of the embodiments, the excitation module, the inductance module, the detection module, the analog-to-digital conversion module and the absolute position calculation unit are connected in sequence, and the encoder further includes a front-end filtering module and a back-end filtering module;

[0020] The front-end filter module is connected after the inductor module and is used to filter the induction signal; the low-pass threshold of the front-end filter module is the frequency of the excitation signal;

[0021] The back-end filtering module is connected between the detection module and the analog-to-digital conversion module, and is used to filter the signal processed by the detection module; the low-pass threshold of the back-end filtering module is determined by the maximum rotation speed of the detection object and the number of cycles of the external induction coil.

[0022] In some of the embodiments, an amplification module is also included;

[0023] The amplification module is connected between the front-end filtering module and the detection module, and is used to amplify the filtered sensing signal.

[0024] In a second aspect, a motor is provided in this embodiment, comprising the inductive absolute position encoder described in the first aspect.

[0025] Compared with the related art, the inductive absolute position encoder and motor provided in this embodiment include an excitation module, an inductance module, a detection module, an analog-to-digital conversion module and an absolute position calculation unit; the inductance module includes a stator and a rotor, the rotor includes inner and outer base coils, and the stator includes an excitation coil and inner and outer induction coils; the inner group of induction coils and the outer group of induction coils of the inner and outer induction coils are both composed of three induction coils with a phase difference of 120 degrees; the excitation module is used to generate an excitation signal and apply it to the excitation coil to generate a magnetic field in the stator, and generate an induction signal through electromagnetic induction of the inner and outer base coils and the inner and outer induction coils; the detection module is used to demodulate the induction signal generated by the inductance module; the analog-to-digital conversion module is used to convert the signal processed by the detection module into a digital signal; the absolute position calculation unit is used to reduce the dimension of the input digital signal through matrix transformation to eliminate errors and output absolute position information. Through this embodiment, a three-coil internal and external combination with a phase difference of 120 degrees is adopted, and the influence of the coupling between the internal and external coils is eliminated through matrix transformation, so that absolute position information with higher accuracy and resolution can be obtained through electromagnetic induction.

[0026] Details of one or more embodiments of the present application are set forth in the following drawings and description to make other features, objects, and advantages of the present application more readily apparent. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0028] Figure 1 is a schematic diagram of the structure of an inductive absolute position encoder in an embodiment;

[0029] Figure 2 FIG. 1 is a schematic diagram of the electromagnetic effect of the inner and outer induction coils in an embodiment. DETAILED DESCRIPTION

[0030] In order to more clearly understand the purpose, technical solutions and advantages of the present application, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments.

[0031] Unless otherwise defined, the technical terms or scientific terms involved in this application shall have the general meaning understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the", "these" and the like in this application do not represent quantitative restrictions, and they can be singular or plural. The terms "include", "comprise", "have" and any variants thereof involved in this application are intended to cover non-exclusive inclusions; for example, a process, method and system, product or device comprising a series of steps or modules (units) is not limited to the listed steps or modules (units), but may include unlisted steps or modules (units), or may include other steps or modules (units) inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether directly or indirectly. The "multiple" involved in this application refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, "A and / or B" can mean: A exists alone, A and B exist at the same time, and B exists alone. Usually, the character " / " indicates that the objects associated with each other are in an "or" relationship. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific ordering of the objects.

[0032] The inductive position encoder is a key device used to measure the rotational position of an object. Through the principle of electromagnetic induction, it converts the displacement of the rotating parts into precise induced voltage changes to achieve high-precision position measurement. It has been widely used in industrial automation, intelligent manufacturing, robotics, and automobiles.

[0033] Traditional incremental encoders can only provide relative position information, and the system needs to be reset after power failure, which easily leads to cumulative errors. In addition, the mutual inductance coupling of the encoder coils will also interfere with the measurement results. Therefore, due to the influence of the mutual inductance coupling and errors of the encoder coils, the current inductive position encoder still has the problem of low accuracy and resolution.

[0034] In this embodiment, an inductive absolute position encoder is provided. Figure 1 Schematic diagram of the structure of the inductive absolute position encoder in this embodiment. Figure 1 As shown, the encoder includes an excitation module, an inductance module, a detection module, an analog-to-digital conversion module and an absolute position calculation unit.

[0035] The inductor module includes a stator and a rotor. The rotor includes inner and outer base coils. The stator includes an excitation coil and inner and outer induction coils. The inner and outer induction coils are composed of three induction coils with a phase difference of 120 degrees.

[0036] An excitation module, used for generating an excitation signal and applying it to the excitation coil to generate a magnetic field in the stator, and generating an induction signal through electromagnetic induction of the inner and outer base coils and the inner and outer induction coils;

[0037] A detection module, used for demodulating the induction signal generated by the inductance module;

[0038] The analog-to-digital conversion module is used to convert the signal processed by the detection module into a digital signal;

[0039] The absolute position calculation unit is used to perform dimension reduction processing on the input digital signal through matrix transformation to eliminate errors and output absolute position information.

[0040] The inductor module includes a stator and a rotor. The rotor and the stator are located on the same axis. The rotor includes inner and outer base coils. The stator includes an excitation coil and inner and outer induction coils. A periodic cycle structure is built through a multi-layer PCB (Printed Circuit Board). The excitation coil generates a rotating magnetic field under the excitation signal applied by the excitation module. The rotor generates an induction signal in the rotating magnetic field through the inner and outer base coils and the inner and outer induction coils.

[0041] The inner and outer induction coils include an inner group of induction coils and an outer group of induction coils, and correspondingly, the inner and outer base coils include an inner group of base coils and an outer group of base coils. The inner and outer induction coils and the outer group of induction coils of the inner and outer induction coils are composed of three induction coils with a phase difference of 120 degrees. The inner and outer base coils of the rotor correspond to the positions and period numbers of the inner and outer induction coils of the stator, so as to induce an envelope waveform with a peak value as position information in the inductance module. The excitation signal applied to the excitation coil by the excitation module is used to generate a magnetic field, and as the carrier frequency of the envelope waveform output by the inductance module, the six induction coils in the stator all generate corresponding modulation signals, i.e., induction signals, at this carrier frequency. Figure 2 Schematic diagram of the electromagnetic effect of the internal and external induction coils in this embodiment. Figure 2 As shown, the excitation coil generates a magnetic field under the action of the excitation signal, the three induction coils in the inner group of induction coils and the outer group of induction coils have a phase difference of 120 degrees, there is an intra-phase mutual inductance in the inner group of induction coils and the outer group of induction coils, and there is a phase-to-phase mutual inductance between the inner and outer groups of induction coils.

[0042] The induction signal generated by the inductor module is demodulated in the detection module, wherein the demodulation process includes but is not limited to envelope detection, synchronous detection and square-law detection, etc., and the original signal can be demodulated and restored from the high-frequency modulated signal.

[0043] The analog-to-digital conversion module maps the six-phase induced voltage (analog signal) processed by the front-end circuit to the corresponding digital voltage value interval to convert it into voltage data (digital signal), and uses the obtained voltage data as the input of the absolute position calculation unit. The absolute position calculation unit can be set in the MCU, and the six-phase induced voltage is input to the MCU through the analog-to-digital conversion module. In the absolute position calculation unit, the input voltage data is reduced in dimension through matrix transformation to eliminate errors and output absolute position information, wherein the voltage data can be reduced in dimension through Clarke transformation and Park transformation, and the symmetry of the three coils with a phase difference of 120 degrees is used to eliminate errors, generate linear rotation information corresponding to the inner group of induction coils and the outer group of induction coils, and further calculate the absolute position information of the rotor.

[0044] Furthermore, in order to achieve a higher encoder resolution, the frequency of the excitation signal of the excitation module and the number of cycles of the internal and external induction coils may be increased accordingly to obtain an inductive absolute position encoder with a higher resolution.

[0045] Through this embodiment, a three-coil internal and external combination with a phase difference of 120 degrees is adopted in the inductance module, which enhances the anti-interference ability of the encoder. Through the principle of electromagnetic induction, the displacement of the rotating part is converted into an accurate induced voltage change, and the influence of the internal and external coil coupling is eliminated through matrix transformation in the absolute position calculation unit, so that the absolute position information with higher accuracy and resolution can be obtained through electromagnetic induction. It has the characteristics of non-contact measurement, high anti-interference, high reliability and excellent measurement accuracy, and is particularly suitable for harsh environments such as high temperature, high humidity, strong vibration and dust.

[0046] In some of the embodiments, the number of periods of the outer group of induction coils is not divisible by the number of periods of the inner group of induction coils.

[0047] Specifically, the period numbers of the outer induction coil and the inner induction coil of the stator are not divisible, that is, there is no integer multiple relationship between the period number of the outer induction coil and the period number of the inner induction coil, wherein the period number of the outer induction coil W and the period number of the inner induction coil N specifically satisfy the following relationship: and W, N, and Z are integer sets. In this way, in the absolute position calculation unit, the angle information of the inner and outer induction coils can be combined to obtain the unique angle position information within a single rotation cycle of the rotor, thereby realizing the absolute position determination of a single turn.

[0048] In this embodiment, the period number of the outer group induction coil is made non-divisible with the period number of the inner group induction coil. In this way, the absolute position information within a single rotation period can be obtained based on the non-divisible period numbers of the inner and outer induction coils, thereby improving the accuracy and resolution of the encoder.

[0049] In some of the embodiments, in the absolute position calculation unit, Clarke transform is used to reduce the dimension and eliminate errors of digital signals to obtain linearly changing angle information; and the absolute position information within a single rotation period is determined based on the period number and angle information of the internal and external induction coils.

[0050] Specifically, the absolute position calculation unit obtains linearly changing angle information based on the input of six sinusoidal digital signal voltage data and Clarke transformation, and obtains absolute position information within a single rotation period based on the non-integer number of periods of the inner and outer induction coils.

[0051] Among them, the three input voltage data with a phase difference of 120 degrees in the inner group induction coil and the outer group induction coil are converted into inputs with a phase difference of 90 degrees through Clarke matrix transformation, so as to obtain the angle information of the inner group induction coil and the outer group induction coil respectively through arctan inverse tangent calculation, and obtain the absolute position information according to the angle information. The following is the calculation process of the angle information of the inner group induction coil and the outer group induction coil:

[0052]

[0053] in, is the Clarke matrix; X n,1 , X n,2 , X n,3 Indicates the three voltage data of the inner induction coil input, X w,1 , X w,2 , X w,3 Represents the three voltage data of the external induction coil input; error represents the coupling inductance error of each input; θ w and θ n They are the angle information of the outer group of induction coils and the inner group of induction coils respectively.

[0054] In the above dimensionality reduction process of converting three inputs with a phase difference of 120 degrees into two inputs with a phase difference of 90 degrees through Clarke transform, the symmetry of the three inputs can be used to eliminate the influence of errors such as mutual inductance coupling between the inner and outer coils. Finally, the absolute position information of the rotor within a single rotation period is calculated based on the angle information of the inner and outer induction coils.

[0055] In this embodiment, the matrix transformation is used to eliminate errors in the process of reducing the input dimension, thereby obtaining absolute position information with higher accuracy.

[0056] In some of the embodiments, the excitation signal generated by the excitation module is a sine wave signal, and the detection module is used to perform envelope detection on the induced signal.

[0057] Specifically, the excitation signal applied by the excitation module to the excitation coil is a sine wave, which is used to generate a magnetic field to induce a sine envelope waveform with a peak value as position information in the inductance module. The six induction coils in the stator of the inductance module all generate corresponding modulation signals, i.e., induction signals, at this carrier frequency. The excitation module can be implemented using any device capable of generating a sine wave, such as a sine wave generator, a crystal oscillator, a voltage-controlled oscillator, etc. The excitation module can adopt an independent hardware design, and the excitation module can be further set independently from the absolute position calculation unit.

[0058] The induction signal is an envelope waveform with a sine wave as the carrier frequency. In the detection module, the induction signal generated by the inductance module is demodulated by envelope detection. Envelope detection mainly recovers the modulation information by detecting the envelope of the signal. Envelope detection only requires basic signal rectification and filtering operations, and the amount of calculation is small. Compared with complex demodulation methods such as synchronous demodulation, it is suitable to be implemented by hardware or a lower-performance MCU (Microcontroller Unit) to complete the reception and preliminary processing of the waveform signal.

[0059] In some of the embodiments, the excitation module includes a crystal oscillator for providing a high-frequency sinusoidal wave signal.

[0060] Specifically, the crystal oscillator includes a quartz crystal and an operational amplifier. The quartz crystal provides a fixed oscillation frequency, and the operational amplifier amplifies the voltage signal to generate an excitation signal with a natural frequency, so that the sinusoidal excitation signal is applied to the excitation coil of the stator. The frequency F of the excitation signal is calculated as follows:

[0061] F≥2 R

[0062] Where R is the encoder resolution.

[0063] In some of the embodiments, the detection module includes a diode; wherein the unidirectional conductivity of the diode is used to perform envelope detection on the sensing signal to retain the positive half cycle of the sensing signal and extract the original signal that varies with the carrier amplitude.

[0064] Specifically, the unidirectional conductivity of the diode is used in the detection module to remove the negative cycle of the high-frequency modulated induction signal, retain the positive half cycle, extract the original signal that changes with the carrier amplitude, and realize signal demodulation through envelope detection with low calculation requirements, which can be realized by hardware or low-performance MCU. Furthermore, the detection module can be set independently of the absolute position calculation unit of the MCU.

[0065] In some of the embodiments, the excitation module and the detection module are provided independently from the absolute position calculation unit.

[0066] Compared with the prior art that uses an MCU chip to generate the excitation signal and is also responsible for signal reception, waveform processing and calculation, which places high requirements on the MCU performance, in this embodiment, the excitation module and the detection module are separated from the MCU and transferred to a dedicated hardware module, which not only reduces the development and manufacturing costs, but also improves the stability, reliability and maintainability of the encoder, providing an efficient and economical solution for high-precision position detection under complex working conditions.

[0067] In some of the embodiments, the excitation module, the inductance module, the detection module, the analog-to-digital conversion module and the absolute position calculation unit are connected in sequence, and the encoder also includes a front-end filtering module and a back-end filtering module; the front-end filtering module is connected after the inductance module, and is used to filter the induction signal; the low-pass threshold of the front-end filtering module is the frequency of the excitation signal; the back-end filtering module is connected between the detection module and the analog-to-digital conversion module, and is used to filter the signal processed by the detection module; the low-pass threshold of the back-end filtering module is determined by the maximum rotation speed of the detection object and the number of cycles of the external induction coil.

[0068] Specifically, Figure 1 As shown, the front-end filter module is connected to the inductor module, and a low-pass filter is used to filter out high-frequency clutter in the induction signal, reduce the influence of noise and interference, obtain a smoother modulation waveform, and better retain the position information in the induction signal. The low-pass threshold of the front-end filter module can be set to the frequency of the excitation signal emitted by the excitation module. The back-end filter module is connected between the detection module and the analog-to-digital conversion module. The low-pass threshold of the back-end filter module is determined by the maximum rotation speed of the detection object and the number of cycles of the external induction coil. The low-pass threshold F of the back-end filter module out_filter The specific settings can be as follows:

[0069] F out_filter =Wω max

[0070] Where W represents the period number of the outer induction coil, ω max Indicates the maximum rotation speed of the detection object.

[0071] By adopting front-end filtering and back-end filtering in this embodiment, high-frequency clutter in the sensing signal can be filtered out, the influence of noise and interference can be reduced, a smoother modulation waveform can be obtained, and the position information in the sensing signal can be better retained.

[0072] In some of the embodiments, an amplification module is also included; the amplification module is connected between the front-end filtering module and the detection module, and is used to amplify the filtered sensing signal.

[0073] Specifically, Figure 1 As shown, the amplifier module is connected between the front-end filtering module and the detection module, and is used to amplify the weaker induction signal obtained by electromagnetic induction to a voltage range that is easy for the detection module and the analog-to-digital conversion module to process, so as to meet the needs of the subsequent detection module and the analog-to-digital conversion module.

[0074] In some of the embodiments, a communication module is further included; the communication module is connected to the absolute position calculation unit and is used to transmit absolute position information.

[0075] Specifically, Figure 1 As shown, after the communication module is connected to the absolute position calculation unit, it can be set in the MCU to output the current absolute position information of the rotor. The encoder is connected to external electronic devices through the communication module to provide real-time position information. In addition, the communication module supports a variety of standard industrial interfaces and can be customized according to different requirements. It can be seamlessly integrated with various electronic devices such as control systems and automation equipment to achieve accurate rotor position monitoring and control.

[0076] Through the communication module in this embodiment, real-time position information can be provided to various external electronic devices to achieve accurate rotor position monitoring and control.

[0077] The present embodiment is described and illustrated below through preferred embodiments.

[0078] This embodiment provides an inductive absolute position encoder, such as Figure 1 As shown, the encoder includes an excitation module, an inductance module, a front-end filter module, an amplification module, a detection module, a back-end filter module, an analog-to-digital conversion module, an absolute position calculation unit, and a communication module connected in sequence. When the encoder is powered on, each module is started in sequence according to the connection sequence. The excitation module is a carrier that generates a signal. It is a carrier that cannot achieve stable operation instantly when powered on, so it needs to be started first. The sequential startup of the remaining parts is determined by the connection sequence of the circuit, and a startup delay is set in the MCU to ensure that the angle calculation starts after the external circuit works stably, so as to ensure the stability and correctness of the angle output.

[0079] Among them, the inductance module includes a stator and a rotor, the rotor includes inner and outer base coils, and the stator includes an excitation coil and inner and outer induction coils; the inner group of induction coils and the outer group of induction coils of the inner and outer induction coils are both composed of three induction coils with a phase difference of 120 degrees, and the positions and period numbers of the inner and outer base coils of the rotor correspond to the inner and outer induction coils of the stator, so as to induce a high-frequency induction signal of a sinusoidal envelope waveform with a peak value as position information in the inductance module.

[0080] The period number W of the outer induction coil is not divisible by the period number N of the inner induction coil, and specifically meets the following requirements: and W, N, Z are sets of integers.

[0081] The excitation module includes a quartz crystal and an operational amplifier. The quartz crystal provides a fixed oscillation frequency, and then the operational amplifier amplifies the voltage signal to generate a sinusoidal excitation signal with a natural frequency. The excitation signal applied by the excitation module to the excitation coil is used to generate a magnetic field and serves as the carrier frequency of the envelope waveform output by the inductance module. The six induction coils in the stator all generate corresponding modulation signals, i.e., induction signals, at this carrier frequency.

[0082] The front-end filter module is used to filter the induction signal and use a low-pass filter to filter out high-frequency clutter, reduce noise and interference, and better retain the rotor position information. Its threshold is the frequency of the excitation signal.

[0083] The amplifier module is used to amplify the weaker induction signal obtained by electromagnetic induction to meet the needs of subsequent detection module and analog-to-digital conversion module operations.

[0084] The detection module uses the unidirectional conductivity of the diode to remove the negative cycle of the high-frequency modulated induction signal, retain the positive half-cycle, and extract the original signal that changes with the carrier amplitude. Signal demodulation is achieved through envelope detection with low computing requirements, which can be implemented through hardware or low-performance MCU.

[0085] The back-end filtering module is used to filter the demodulated signal, and its threshold is determined by the maximum rotation speed of the detection object and the number of cycles of the external induction coil.

[0086] When the detection object is working and driving the rotor to rotate, the waveforms of the internal and external induction coils are generated into a sinusoidal demodulation waveform with a phase difference of 120 degrees through the front-end filtering module, the amplification module, the detection module and the back-end filtering module.

[0087] The analog-to-digital conversion module is used to map the six-phase induced voltage (analog signal) processed by the front-end circuit to the corresponding digital voltage value interval to convert it into voltage data (digital signal), and use the obtained voltage data as the input of the absolute position calculation unit.

[0088] The absolute position calculation unit is set in the MCU, and the three input voltage data with a phase difference of 120 degrees in the inner group induction coil and the outer group induction coil are converted into inputs with a phase difference of 90 degrees through Clarke matrix transformation, so as to obtain the angle information of the inner group induction coil and the outer group induction coil respectively through arctan inverse tangent calculation. In the process of dimensionality reduction, the symmetry of the three inputs can be used to eliminate the influence of errors such as mutual inductance coupling between the inner and outer coils, and finally the absolute position information of the rotor within a single rotation cycle is calculated based on the angle information of the inner group induction coil and the outer group induction coil.

[0089] The communication module is set in the MCU to output the current absolute position information of the rotor. The encoder is connected to external electronic devices through the communication module to provide real-time position information. In addition, the communication module supports a variety of standard industrial interfaces (such as RS485) and can be customized according to different needs. It can be seamlessly integrated with various control systems, automation equipment and other electronic devices to achieve accurate rotor position monitoring and control.

[0090] Furthermore, the excitation module and the detection module can adopt a dedicated hardware design and be set independently from the absolute position calculation unit of the MCU to reduce the performance requirements on the MCU.

[0091] In order to achieve a higher encoder resolution, the frequency of the excitation signal of the excitation module and the number of cycles of the internal and external induction coils can be increased accordingly to obtain an inductive absolute position encoder with a higher resolution.

[0092] The inductive absolute position encoder provided in this embodiment enhances the anti-interference ability of the encoder by adopting an internal and external combination of three coils with a phase difference of 120 degrees, converts the displacement of the rotating part into an accurate induced voltage change through the principle of electromagnetic induction, and eliminates the influence of the coupling of the internal and external coils through matrix transformation in the absolute position calculation unit, so that absolute position information with higher accuracy and resolution can be obtained through electromagnetic induction. It has the characteristics of non-contact measurement, high anti-interference, high reliability and excellent measurement accuracy, and is particularly suitable for harsh environments such as high temperature, high humidity, strong vibration and dust.

[0093] In addition, compared with the current inductive position encoders that generally use chips to generate excitation signals and a highly integrated architecture responsible for signal reception, waveform processing and calculation, the excitation module and detection module are designed independently of the chip, and a hardware detection module is used to complete signal reception and preliminary processing, which reduces the computing load on the MCU and allows the MCU to focus on absolute position data calculation and communication tasks, simplifies system design and cost, reduces performance requirements for the MCU, makes debugging, fault diagnosis and maintenance easier, shortens downtime, improves reliability and maintainability, and ensures real-time and flexibility of the equipment through the compatibility of independent excitation modules and detection modules with multiple industrial communication protocols.

[0094] In this embodiment, a motor is also provided, comprising the inductive absolute position encoder in any of the above embodiments, that is, the motor is the detection object of the encoder.

[0095] The encoder is installed on the motor to detect the rotation angle of the motor rotor. The motor is suitable for traction machines, industrial automation equipment, robots, CNC machine tools, CT machines, MRI machines, automatic control operating tables and other medical equipment. The high-precision and high-resolution encoder of this application can provide more accurate absolute position information to achieve precise control.

[0096] It should be understood that the specific embodiments described herein are only used to explain the application, rather than to limit it. Based on the embodiments provided in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of this application.

[0097] Obviously, the drawings are only some examples or embodiments of the present application. For ordinary technicians in the field, the present application can also be applied to other similar situations based on these drawings without creative work. In addition, it is understandable that although the work done in this development process may be complicated and lengthy, for ordinary technicians in the field, certain changes in design, manufacturing or production based on the technical content disclosed in this application are only conventional technical means and should not be regarded as insufficient content disclosed in this application.

[0098] The term "embodiment" in this application refers to a specific feature, structure or characteristic described in conjunction with the embodiment that can be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily mean the same embodiment, nor does it mean that it is mutually exclusive with other embodiments and is independent or optional. It is clearly or implicitly understood by those of ordinary skill in the art that the embodiments described in this application can be combined with other embodiments without conflict.

[0099] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of patent protection. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the scope of protection of the present application. Therefore, the scope of protection of the present application shall be subject to the attached claims.

Claims

1. An inductive absolute position encoder, characterized in that: It includes an excitation module, an inductance module, a detection module, an analog-to-digital conversion module and an absolute position calculation unit; The inductor module includes a stator and a rotor, the rotor includes inner and outer base coils, and the stator includes an excitation coil and inner and outer induction coils; the inner and outer induction coils of the inner and outer induction coils are each composed of three induction coils with a phase difference of 120 degrees; The excitation module is used to generate an excitation signal and apply it to the excitation coil to generate a magnetic field in the stator, and generate an induction signal through electromagnetic induction of the inner and outer base coils and the inner and outer induction coils; The detection module is used to demodulate the induction signal generated by the inductance module; The analog-to-digital conversion module is used to convert the signal processed by the detection module into a digital signal; The absolute position calculation unit is used to perform dimensionality reduction processing on the input digital signal through matrix transformation to eliminate errors and output absolute position information.

2. The inductive absolute position encoder according to claim 1, characterized in that: The number of periods of the outer group of induction coils is not divisible by the number of periods of the inner group of induction coils.

3. The inductive absolute position encoder according to claim 1, characterized in that: In the absolute position calculation unit, the digital signal is subjected to dimension reduction and error elimination processing by Clarke transformation to obtain linearly changing angle information; and the absolute position information within a single rotation period is determined according to the period number of the internal and external induction coils and the angle information.

4. The inductive absolute position encoder according to claim 1, characterized in that: The excitation signal generated by the excitation module is a sine wave signal, and the detection module is used to perform envelope detection on the induced signal.

5. The inductive absolute position encoder according to claim 4, characterized in that: The excitation module includes a crystal oscillator for providing a high-frequency sine wave signal.

6. The inductive absolute position encoder according to claim 4, characterized in that: The detection module includes a diode; The unidirectional conductivity of the diode is used to perform envelope detection on the induced signal, so as to retain the positive half cycle of the induced signal and extract the original signal that varies with the carrier amplitude.

7. The inductive absolute position encoder according to claim 1, characterized in that: The excitation module and the detection module are arranged independently from the absolute position calculation unit.

8. The inductive absolute position encoder according to claim 1, characterized in that: The excitation module, the inductance module, the detection module, the analog-to-digital conversion module and the absolute position calculation unit are connected in sequence, and the encoder also includes a front-end filtering module and a back-end filtering module; The front-end filter module is connected after the inductor module and is used to filter the induction signal; the low-pass threshold of the front-end filter module is the frequency of the excitation signal; The back-end filtering module is connected between the detection module and the analog-to-digital conversion module, and is used to filter the signal processed by the detection module; The low-pass threshold of the back-end filtering module is determined by the maximum rotation speed of the detection object and the number of cycles of the external induction coil.

9. The inductive absolute position encoder according to claim 8, characterized in that: Also included is an amplification module; The amplification module is connected between the front-end filtering module and the detection module, and is used to amplify the filtered sensing signal.

10. A motor, characterized in that: The invention comprises an inductive absolute position encoder as claimed in any one of claims 1 to 9.

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