Permanent magnet synchronous joint motor, magnetic encoder thereof and angle detection method with ambiguity elimination

Abstract

Permanent magnet synchronous joint motor, magnetic encoder and angle detection method, relate to motor angle detection technical field. The magnetic encoder contains a magnetic encoder module and an AMR sensor array. The magnetic encoder module is suitable for being installed at the motor shaft end. The magnetic encoder module includes coaxially arranged outer ring magnet and inner ring magnet. The absolute value of the difference between the pole pairs of the outer ring magnet and the inner ring magnet is 2. The AMR sensor array is suitable for being arranged in the magnetic field action area of the outer ring magnet and the inner ring magnet. The AMR sensor array includes two AMR sensors located on the same radius line of the magnetic field action area. Two AMR sensors correspond to the magnetic field area of the outer ring magnet and the inner ring magnet respectively, and are used for synchronously collecting the signals of the respective corresponding magnetic ring. The signals are suitable for realizing high-resolution detection of single-turn absolute angle through double-ring vernier effect and disambiguation algorithm.

Description

Technical Field

[0001] This invention relates to the field of motor angle detection technology, and more specifically, to a permanent magnet synchronous joint motor, its magnetic encoder, and a method for disambiguating angle detection. Background Technology

[0002] Permanent magnet synchronous motors are widely used in robot joints, CNC systems, and servo systems due to their high power density, high efficiency, and excellent dynamic performance. These applications place stringent demands on the real-time and accurate acquisition of rotor position. In applications with limited installation space, such as joint motors, angle detection devices need to simultaneously possess high resolution, strong anti-interference capabilities, and high reliability under strictly controlled axial dimensions. This poses challenges to sensor structure design, signal quality, and environmental adaptability.

[0003] Among existing solutions, optical encoders offer high resolution and stability, but their complex structure, high cost, and susceptibility to dust and oil contamination make them unsuitable for long-term reliable applications in confined spaces. Traditional Hall effect magnetic encoders are simple in structure and inexpensive, but their resolution is insufficient for high-end servo applications.

[0004] AMR / TMR-based magnetic encoders (i.e., AMR magnetoresistive sensors and TMR magnetoresistive sensors) are small in size and have stable output, but when using a single multi-pole magnetic ring, the system resolution is limited by the number of pole pairs. Further increasing the number of pole pairs will lead to problems such as increased magnet processing complexity and waveform distortion. At the same time, this type of solution is sensitive to assembly coaxiality, pole pitch uniformity, and air gap consistency, and is easily affected by external stray magnetic field interference.

[0005] In the field of vernier-type dual-ring magnetic encoders, existing designs often use a difference of 1 between the number of pole pairs of the inner and outer magnetic rings to avoid ambiguity in multiple cycles. Although the calculation process is relatively simplified, the magnetic flux coupling and in-phase distortion are prone to superposition due to the close spatial frequencies of the two magnetic signals. This makes the encoders more sensitive to assembly and environmental vibrations, which in turn affects mass production consistency and engineering robustness.

[0006] In summary, existing technologies struggle to balance high resolution, strong anti-interference capabilities, and high reliability within a compact installation space. There is an urgent need to develop new comprehensive improvement paths in areas such as magnetic circuit structure, sensor layout, and anti-interference isolation to overcome the resolution and robustness bottlenecks caused by the number of single-ring pole pairs, and to improve assembly tolerance and batch consistency. Summary of the Invention

[0007] The present invention provides a permanent magnet synchronous joint motor, a magnetic encoder thereof, and a method for disambiguating angle detection, to improve at least one of the above-mentioned technical problems.

[0008] In a first aspect, the present invention provides a magnetic encoder for a permanent magnet synchronous joint motor, which includes a magnetic encoder module and an AMR sensor array.

[0009] The magnetic encoder module is suitable for mounting on the motor shaft end. The magnetic encoder module includes an outer ring magnet and an inner ring magnet arranged coaxially. The absolute value of the difference in the number of pole pairs between the outer ring magnet and the inner ring magnet is 2.

[0010] An AMR sensor array is adapted to be arranged within the magnetic field interaction region of an outer ring magnet and an inner ring magnet. The AMR sensor array includes two AMR sensors located on the same radius line within the magnetic field interaction region. The two AMR sensors correspond to the magnetic field regions of the outer and inner ring magnets, respectively, and are used to synchronously acquire signals from their respective magnetic rings.

[0011] The signal is suitable for high-resolution detection of single-circle absolute angles through the double-ring vernier effect and disambiguation algorithm.

[0012] As a further aspect of the present invention, the outer ring magnet and the inner ring magnet are arranged with different radii, with the outer ring magnet having a larger radius than the inner ring magnet, thus forming a radius difference.

[0013] The radial mounting positions of the two AMR sensors are matched to this radius difference so that the two sensors can acquire the optimal and stable phase difference signal.

[0014] As a further embodiment of the present invention, the outer ring magnets consist of 19 pairs, and the inner ring magnets consist of 17 pairs. Alternatively, the outer ring magnets consist of 17 pairs, and the inner ring magnets consist of 19 pairs.

[0015] As a further aspect of the present invention, magnetic flux converging elements are provided on both sides of the AMR sensor array to concentrate magnetic lines of force, increase effective magnetic flux density, and enhance the signal-to-noise ratio.

[0016] The magnetic flux converging element is designed with a symmetrical arc shape. The material of the magnetic flux converging element is a soft magnetic material with a relative permeability greater than 5000.

[0017] As a further aspect of the present invention, magnetic field isolation components are provided on both sides of the magnetic encoder module and the AMR sensor array. The magnetic field isolation component is an annular soft magnetic cover with an opening at the top. The opening at the top allows axial magnetic flux to pass through. The cover of the annular soft magnetic cover is used to block radial magnetic leakage interference.

[0018] As a further aspect of the present invention, the outer layer of the annular soft magnetic shield is provided with an outer encapsulation cover. The outer encapsulation cover is made of polycarbonate material, which completely covers the outside of the annular soft magnetic shield and covers the top of the opening of the annular soft magnetic shield, forming a double-layer protective structure of inner isolation and outer protection.

[0019] As a further embodiment of the present invention, the magnetic encoder module is adapted to be fixed to the motor end cover by installing a deep groove ball bearing.

[0020] The AMR sensor array is suitable for mounting on a single PCB. Two AMR sensors are positioned on the same radius line of the PCB. The PCB also includes differential amplification and filtering circuitry.

[0021] Secondly, the present invention provides a permanent magnet synchronous joint motor, which is equipped with a magnetic encoder for a permanent magnet synchronous joint motor as described in any section of the first aspect.

[0022] Thirdly, the present invention provides a method for disambiguation angle detection using a magnetic encoder for a permanent magnet synchronous joint motor. The magnetic encoder also includes differential amplification and filtering circuits.

[0023] The disambiguation angle detection method includes steps S1 to S4.

[0024] S1. Two AMR sensors synchronously acquire the magnetic field information of their respective magnetic rings and output detection signals.

[0025] S2. The detection signal is differentially amplified and low-pass filtered through differential amplification and filtering circuits.

[0026] S3. Based on the two processed detection signals, obtain the vernier phase difference using a vernier algorithm.

[0027] S4. Based on the vernier phase difference, the 180° period vernier phase difference is expanded to a mechanical angle of 0 to 360° through disambiguation mapping to obtain a high-resolution absolute angle signal.

[0028] As a further aspect of the present invention, in step S3, the vernier algorithm employs one or more of the following: the CORDIC algorithm, LUT-based lookup interpolation, or polynomial fitting.

[0029] As a further aspect of the present invention, S3 specifically includes:

[0030] .

[0031] .

[0032] .

[0033] In the formula For mechanical angle, The electrical angle phase obtained by the AMR sensor corresponding to the outer ring magnet, The number of pole pairs of the outer ring magnet, For the electric angle phase error term of the outer ring magnet, The electrical angle phase obtained by the AMR sensor corresponding to the inner ring magnet, The number of pole pairs of the inner ring magnet, For the electric angle phase error term of the inner ring magnet, For phase difference, for and The difference It represents the identity sign.

[0034] As a further aspect of the present invention, S4 specifically includes: recording the absolute value of the difference between the extreme logarithms. .when hour Repeated twice within one revolution (period 180°), thus the mechanical angle is represented by a disambiguation mapping. The only recovery is to the range of greater than or equal to 0 degrees and less than 360 degrees (i.e., [0°, 360°)). .

[0035] By adopting the above technical solution, the present invention can achieve the following technical effects:

[0036] The permanent magnet synchronous joint motor, its magnetic encoder, and the disambiguation angle detection method of the present invention achieve a significant improvement in robustness, consistency, and mass production by sacrificing a small potential loss of theoretical accuracy that can be compensated for through signal processing, thereby realizing superior overall performance. Attached Figure Description

[0037] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the specific embodiments of the present invention will be briefly introduced below. It should be understood that the following drawings only show some specific embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0038] Figure 1 This is an isometric view of a permanent magnet synchronous joint motor.

[0039] Figure 2 This is a front view of a permanent magnet synchronous joint motor.

[0040] Figure 3 This is a front view of the magnetic encoder module.

[0041] Figure 4 This is an isometric view of the magnetic encoder module.

[0042] Figure 5 An isometric view of an AMR sensor array mounted on a PCB.

[0043] Figure 6 An isometric view of the mating state of the AMR sensor array and the flux convergent.

[0044] Figure 7 This is an isometric view of a magnetic field isolator.

[0045] Figure 8 This is a flowchart of the disambiguation angle detection method. Detailed Implementation

[0046] The technical solutions of the present invention will now be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention.

[0047] Example 1, please refer to Figures 1 to 7 The first embodiment of this invention provides a dual-ring vernier AMR magnetic encoder for a permanent magnet synchronous joint motor 1, which can achieve higher resolution and more robust angle detection within a limited space at the motor shaft end, comparable to traditional magnetic encoders. This embodiment of the invention effectively solves the core contradictions of existing technologies—insufficient accuracy due to the limitation of the number of pole pairs of a single magnetic ring and poor anti-interference due to simple structure—in a compact space through a unique dual-ring vernier design and a highly integrated sensor layout. Preferably, the overall thickness of the dual-ring vernier AMR magnetic encoder for a permanent magnet synchronous joint motor 1 of this invention is suitable for compact joint motors.

[0048] The magnetic encoder for the permanent magnet synchronous joint motor 1 of the present invention includes a magnetic encoder module and an AMR sensor array. The magnetic encoder module is adapted to be mounted on the motor shaft end. The magnetic encoder module includes an outer ring magnet 3 and an inner ring magnet 2 arranged coaxially. The absolute value of the difference between the number of pole pairs of the outer ring magnet 3 and the inner ring magnet 2 is 2.

[0049] The AMR sensor array is suitable for arrangement within the magnetic field interaction region of the outer ring magnet 3 and the inner ring magnet 2. The AMR sensor array includes two AMR sensors 4 located on the same radius line within the magnetic field interaction region. The two AMR sensors 4 correspond to the magnetic field regions of the outer ring magnet 3 and the inner ring magnet 2, respectively, and are used to synchronously acquire signals from their respective magnetic rings. The signals are suitable for high-resolution detection of the absolute angle of a single turn through the dual-ring vernier effect and disambiguation algorithm.

[0050] Preferably, the magnetic encoder module is adapted to be fixed to the motor end cover by mounting a deep groove ball bearing 6. The AMR sensor array is adapted to be carried on a single PCB. The two AMR sensors 4 are located on the same radius line of the PCB.

[0051] The rotating component of the magnetic encoder module is interference-fitted with the motor shaft via the inner ring of the deep groove ball bearing 6, while the stationary encoder housing is supported by the outer ring of the bearing, thus achieving relative fixation with the motor end cover. During installation, it is necessary to ensure good coaxiality between the module's shaft hole and the motor shaft, and to ensure that no relative displacement occurs during motor operation through appropriate tightening methods.

[0052] The magnet assembly, serving as the core excitation source, consists of an outer ring magnet 3 and an inner ring magnet 2 coaxially arranged, with the absolute value of the difference between their pole pairs being 2. The magnetization method of the magnetic ring must ensure magnetization accuracy to give the magnetic field waveform good sinusoidal characteristics, which is a crucial prerequisite for ensuring the accuracy of subsequent signal processing.

[0053] Based on the above embodiments, in an optional embodiment of the present invention, such as Figures 2 to 4 As shown, the outer ring magnet 3 consists of 19 pairs, and the inner ring magnet 2 consists of 17 pairs. In another optional embodiment, the outer ring magnet 3 consists of 17 pairs, and the inner ring magnet 2 consists of 19 pairs, with the remaining structure and working principle (i.e., installation and signal processing flow) being the same.

[0054] This invention does not impose specific limitations on the number of pole pairs of the outer ring magnet 3 and the inner ring magnet 2. As long as the absolute value of the difference between the number of pole pairs of the inner and outer magnetic rings is 2 (including schemes such as "17 pairs for the outer ring and 19 pairs for the inner ring" that interchange the number of inner and outer pole pairs), they all fall within the protection scope of this invention.

[0055] This invention, based on the vernier angle measurement principle, utilizes multi-dimensional innovative design to construct a compact and high-performance angle detection system. Compared to a pole pair difference of 1, a pole pair difference of 2 significantly increases the spatial frequency separation of the two magnetic signals, reducing the co-directional influence of magnetic flux coupling and common-mode error on the phase difference. Simultaneously, the increased pole pitch difference facilitates the use of standardized magnets for segmentation, improving assembly tolerance and batch consistency without increasing axial dimensions. This configuration lays the physical foundation for subsequent radial matching and stable phase difference of the AMR sensor 4 along the same radius line.

[0056] The difference in the number of pole pairs is the theoretical basis for generating the vernier effect and achieving angle subdivision. When the motor rotor rotates, due to the different number of pole pairs of the two magnetic rings, there is a slight difference in the number of cycles of the magnetic field signal they generate. By detecting this difference, precise subdivision of the angle can be achieved.

[0057] Preferably, the outer ring magnet 3 and the inner ring magnet 2 are arranged with different radii, with the outer ring magnet 3 having a larger radius than the inner ring magnet 2, forming a certain radius difference. This radius difference design not only facilitates the mechanical arrangement of the magnetic rings, but more importantly, it provides physical space for the subsequent optimized layout of sensors, which is one of the keys to achieving high stability in signal processing (see overall assembly and relative position relationship). Figure 4 ).

[0058] More preferably, both magnetic rings are made of high-performance permanent magnet materials and undergo precise magnetization to ensure that the magnetic field waveform has good sinusoidality and stability, laying the foundation for high-precision signal extraction.

[0059] like Figure 5 and Figure 6As shown, this embodiment of the invention integrates two AMR sensor chips 4 on a single PCB to form a sensor array. This invention abandons the traditional orthogonal or random distribution of sensors, innovatively arranging the two sensors on the same radius line of the PCB. The radial mounting positions of the two AMR sensors 4 are matched with the radius difference, enabling the two sensors to acquire optimized and stable phase difference signals. The sensitive center of one sensor is precisely aligned radially with the effective magnetic field region of the outer ring magnet 3, while the other is precisely aligned with the effective magnetic field region of the inner ring magnet 2.

[0060] The core advantage of this unique "radial matching" layout lies in its ability to directly and stably convert the inherent mechanical spatial difference of the two magnetic rings (determined by the radius difference) into a phase difference between the two electrical signals through the fixed positional relationship of the sensors. This phase difference is guaranteed by the mechanical structure, thus significantly reducing the impact of external factors such as installation eccentricity and temperature drift, making it more reliable than a phase difference generated solely by electrical processing.

[0061] Preferably, the PCB is made of rigid material and has a precise positioning structure to ensure the repeatability of sensor positions and assembly consistency. This layout improves signal quality while greatly simplifying the assembly process, which is beneficial for mass production.

[0062] Single PCB integration and sensor radial matching layout, such as Figure 2 and 5 As shown, a ring-shaped printed circuit board is fixed to the motor end cover by a precision support structure, maintaining an appropriate and uniform axial gap with the rotating magnet assembly. Two AMR sensor chips 4 are integrated on the PCB. These two sensors are precisely arranged on the same radius line of the PCB, respectively used to collect the magnetic signals generated by the outer ring magnet 3 and the inner ring magnet 2, and synchronously output two sine and cosine waveforms with a fixed phase relationship.

[0063] Based on the above embodiments, in an optional embodiment of the present invention, in order to further improve signal quality within a limited installation space, the magnetic encoder of the permanent magnet synchronous joint motor 1 is further provided with a magnetic flux converging element 5 for magnetic flux convergence enhancement. Specifically, as shown... Figure 5 and Figure 6 As shown, magnetic flux converging elements 5 are set on both sides of the AMR sensor array to concentrate magnetic lines of force, increase effective magnetic flux density and enhance signal-to-noise ratio.

[0064] The flux converging element 5 is made of a soft magnetic material with high permeability (such as high-permeability ferrite, silicon steel sheet, etc.). Its shape is designed as a symmetrical arc and a magnetically conductive structure that matches the sensor layout. Soft magnetic materials refer to magnetic materials with a coercivity (Hc) not greater than 1000 A / m (1 kA / m), characterized by "easy magnetization, easy demagnetization, and high saturation magnetic induction." Generally, soft magnetic materials with a relative permeability greater than 5000 are called high permeability materials, and those with a relative permeability greater than 10000 are called ultra-high permeability materials. Relative permeability refers to the ratio of the absolute permeability of a material to the absolute permeability of vacuum (it is a dimensionless unit, a ratio, and therefore has no unit).

[0065] Preferably, the magnetic flux converging element 5 is made of permalloy and has a hyperbolic structure, as shown in the attached specification. Figure 6 As shown.

[0066] Preferably, the thickness of the flux converging element 5 needs to be optimized to ensure that the axial dimension of the system is not excessively increased while converging the magnetic flux. This design is particularly beneficial for ensuring signal strength in applications with large air gaps or using low-energy magnets.

[0067] Preferably, the magnetic flux converging element 5 should maintain a small gap with the surface of the sensor chip to avoid mechanical contact. More preferably, the introduction of the magnetic flux converging element 5 can significantly improve the amplitude of the sensor output signal and effectively suppress common-mode magnetic field interference, thereby improving the overall signal-to-noise ratio and sinusoidal nature of the output waveform of the system.

[0068] The flux converging element 5 concentrates magnetic field lines, improving the signal-to-noise ratio and reducing the impact of installation eccentricity on angle detection. The working mechanism of the flux converging element 5 is to effectively converge and guide the relatively dispersed magnetic field lines emitted by the magnet to the sensitive area of ​​the AMR sensor 4, thereby significantly increasing the effective magnetic flux density at the sensor location. This directly increases the amplitude of the sensor's output signal, reduces signal attenuation, and effectively suppresses interference from external stray magnetic fields, thus improving the overall signal-to-noise ratio of the system (see overall assembly and relative position relationship for details). Figure 5 and Figure 6 ).

[0069] like Figure 5 As shown, magnetic flux converging elements 5, made of a soft magnetic material with high permeability, are disposed on both sides of the sensor array on the PCB. The relative arrangement of the magnetic flux converging elements 5 with respect to the sensor array and the PCB board is shown in [reference]. Figure 6The converging component is designed with a symmetrical arc shape. Its core function is to utilize the high magnetic permeability of soft magnetic materials to effectively converge and guide the magnetic field lines emitted by the magnet to the sensitive area of ​​the AMR sensor 4, thereby significantly increasing the effective magnetic flux density at the sensor location. This directly improves the amplitude of the sensor's output signal, enhances the signal-to-noise ratio, and effectively compensates for signal attenuation caused by slight installation misalignment.

[0070] Specifically, the flux converging element 5 can employ various equivalent structural and material schemes to improve the signal-to-noise ratio and amplitude equalization. Its shape can be one of hyperbolic, arc-transition, or sheet-like structures with decoupling slits, and the material can be permalloy, silicon steel sheet, or iron-nickel alloy, etc. Those skilled in the art can make equivalent substitutions and combinations of the above dimensions and materials without departing from the spirit of the present invention.

[0071] It should be noted that the flux converging element 5 is an optional feature. Even if the flux converging element 5 is omitted, the single-turn absolute angle calculation and the predetermined accuracy index can still be achieved by combining the pole pair difference of 2, the AMR arrangement of the same radius line, and the disambiguation algorithm.

[0072] Based on the above embodiments, in an optional embodiment of the present invention, such as Figure 7 As shown, the permanent magnet synchronous joint motor 1 uses a magnetic encoder with magnetic field isolation components on both sides of the magnetic encoder module and the AMR sensor array. The magnetic field isolation component is an annular soft magnetic cover 7 with a top opening. The top opening is used to allow axial magnetic flux to pass through. The cover of the annular soft magnetic cover 7 is used to block radial magnetic leakage interference.

[0073] To ensure the long-term stability and reliability of the encoder in complex industrial environments, this invention incorporates a magnetic field isolator design to combat interference. Specifically, magnetic field isolators are placed on both sides of the magnet and the PCB sensor array. This isolator is a ring-shaped soft magnetic cover 7 with an open top. Its core function is to utilize the high permeability of the soft magnetic material to effectively block radial stray magnetic fields and leakage magnetic interference from the internal magnetic ring. Simultaneously, its open top structure ensures that the axial magnetic flux required for operation can pass through unimpeded, maintaining the normal operation of the main magnetic circuit.

[0074] Based on the above embodiments, in an optional embodiment of the present invention, the outer layer of the annular soft magnetic cover 7 is provided with an outer encapsulation cover. The outer encapsulation cover is made of polycarbonate (PC) material, which completely covers the outside of the annular soft magnetic cover 7 and covers the top of the opening of the annular soft magnetic cover 7, forming a double-layer protective structure of inner isolation and outer protection, providing mechanical protection, dust and water resistance, and environmental adaptability.

[0075] Specifically, the outer layer of the annular soft magnetic shield 7 is made of polycarbonate (PC) material, forming a two-layer annular shield. PC material possesses excellent impact strength, dimensional stability, and flame retardant properties. Furthermore, the encapsulation layer completely covers and seals the top, providing mechanical protection, dust and water resistance, and environmental adaptability for the internal precision structure. Its non-magnetic nature ensures that it will not interfere with the internal magnetic field distribution. Through this two-layer combination of "inner soft magnetic isolation + outer PC encapsulation," this structure achieves reliable environmental protection and structural simplification while ensuring signal accuracy and anti-interference capabilities.

[0076] In this embodiment, a magnetic field isolator (an annular soft magnetic shield 7 with a top opening) is provided around the magnet and the PCB assembly to effectively suppress interference from external stray magnetic fields. Through the dual-layer combination of magnetic shielding and outer PC packaging, the system can continuously output stable, high-resolution angle signals in complex environments, thereby improving system robustness.

[0077] Preferably, the magnetic field isolator is made of high-performance soft magnetic materials such as permalloy or iron-nickel alloy. This shield must maintain appropriate safety clearances with both the internal rotating magnet and the fixed PCB board. This is to prevent mechanical friction that may occur during high-speed rotation and to prevent excessive short-circuiting of the magnetic flux, which could affect the main magnetic circuit. Its core function is to create a pure magnetic environment, effectively attenuating various interfering magnetic fields from the radial direction.

[0078] Building upon this, a double-ringed structure is formed by encapsulating the soft magnetic shield with a polycarbonate (PC) outer cover using injection molding or other methods. This PC cover not only provides robust mechanical protection, dust and moisture protection, but its stable non-metallic properties also prevent secondary interference with the internal magnetic field. This dual "magnetic-mechanical" protection design significantly improves the system's electromagnetic compatibility and long-term reliability in harsh industrial environments.

[0079] To further enhance mechanical stability, a deep groove ball bearing 6 support structure is installed between the PC package housing and the motor shaft to achieve precise alignment and stable support between the rotating shaft system and the stationary housing, thereby enhancing the entire encoder's vibration resistance and long-term accuracy retention under complex working conditions.

[0080] Specifically, a deep groove ball bearing 6 is located at the top center of the polycarbonate (PC) enclosure. The outer ring of the deep groove ball bearing 6 is interference-fitted with the PC enclosure to provide static support for the entire encoder structure. The inner ring of the deep groove ball bearing 6 is interference-fitted with the motor shaft and rotates with the shaft.

[0081] This design achieves precise mechanical decoupling and alignment between rotating components (shaft, magnetic ring) and stationary components (encoder housing, soft magnetic cover, PCB). Bearing support ensures the positional stability of the stationary components under external forces or vibrations, while maximizing the distance between the radial runout of the shaft and the sensitive components inside the encoder. This fundamentally reduces the impact of shaft wobble on the magnetic field signal and detection accuracy, significantly improving the product's mechanical robustness and long-term operational reliability.

[0082] In summary, the various embodiments of the present invention provide a complete and flexibly configurable high-performance magnetic encoder implementation scheme, from the core signal acquisition and processing steps to optional magnetic flux convergence enhancement, magnetic field isolation and anti-interference, and system-level integration. These embodiments can be implemented individually or combined according to specific application requirements, collectively ensuring that the magnetic encoder achieves the comprehensive performance goals of high resolution, high precision, and high robustness without increasing the installation space constraint.

[0083] Example 2, please refer to Figure 1 The second embodiment of the present invention provides a permanent magnet synchronous joint motor 1, which is equipped with a magnetic encoder for the permanent magnet synchronous joint motor 1 as described in any section of the first embodiment.

[0084] Specifically, such as Figure 4 As shown, the outer ring magnet 3 and the inner ring magnet 2 are coaxially mounted on the motor shaft (preferably 19 pairs of outer rings and 17 pairs of inner rings, with the absolute value of the difference between their pole pairs being 2). Two AMR sensors 4 are arranged along the same radius line on a single PCB and precisely matched with the radius difference of the two magnetic rings to obtain a stable phase difference signal. Magnetic flux converging elements 5 are disposed on both sides of the sensor array to increase the effective magnetic flux density in the sensor's sensitive area.

[0085] Example 3, please refer to Figure 8 The third embodiment of the present invention provides a method for disambiguation angle detection using a magnetic encoder for a permanent magnet synchronous joint motor 1. The magnetic encoder is further equipped with differential amplification and filtering circuits. The AMR sensor output signal is processed by the differential amplification and filtering circuits and then input to a DSP or FPGA for real-time angle calculation.

[0086] Disambiguation angle detection methods include:

[0087] S1. Two AMR sensors synchronously acquire the magnetic field information of their respective magnetic rings and output detection signals.

[0088] S2. The detection signal is differentially amplified and low-pass filtered through differential amplification and filtering circuits.

[0089] S3. Based on the two processed detection signals, obtain the vernier phase difference using a vernier algorithm.

[0090] Preferably, the cursor algorithm employs one or more combinations of the CORDIC algorithm, LUT-based lookup table interpolation, or polynomial fitting. Specifically, the efficient CORDIC algorithm is suitable for applications requiring high-speed real-time computation. Lookup table interpolation can achieve high accuracy with relatively low computational resource consumption. Polynomial fitting can optimize linearity error in specific applications. Users can flexibly choose according to their actual requirements for computational resources, speed, and accuracy, thereby achieving the best balance between system performance and cost.

[0091] S4. Based on the vernier phase difference, the 180° period vernier phase difference is expanded to a mechanical angle of 0 to 360° through disambiguation mapping to obtain a high-resolution absolute angle signal.

[0092] The calculation process in steps S3 and S4 is usually completed in a digital processor (DSP or FPGA) integrated into the motor controller to achieve real-time high-resolution angle output.

[0093] The theoretical analysis and formulas for the disambiguation angle detection method are as follows:

[0094] Let the number of pole pairs of the outer ring magnet be... The number of pole pairs of the inner ring magnet is The mechanical angle is (Unit: °), then the electrical angular phase obtained by the two AMR sensors is:

[0095] .

[0096] .

[0097] In the formula, The electrical angle phase obtained by the AMR sensor corresponding to the outer ring magnet, For the electric angle phase error term of the outer ring magnet, The electrical angle phase is obtained from the AMR sensor corresponding to the inner ring magnet. This is the electric angle phase error term of the inner ring magnet.

[0098] Take the phase difference :

[0099] .

[0100] In the formula, for and The difference. It represents the identity sign.

[0101] Let the absolute value of the difference between the extreme logarithms be... .

[0102] when hour Repeated twice within one revolution (period 180°), thus the mechanical angle is represented by a disambiguation mapping. The only recovery is to the range of greater than or equal to 0 degrees and less than 360 degrees (i.e., [0°, 360°)).

[0103] .

[0104] Small-signal error propagation and theoretical resolution: If the quantization step size of the phase difference is... Then the smallest resolvable step is: In the formula It is the minimum angle.

[0105] When the phase difference is uniformly subdivided within 360° pole hour: .

[0106] thus hour hour In the formula for Minimum angle at time for The minimum angle at that time.

[0107] Conclusion: Under the same phase subdivision capability Below, the minimum step angle with a difference of 2 and the propagation coefficient of angle jitter are both about half that of the difference of 1.

[0108] The disambiguation angle detection method of this invention differentially amplifies and filters two magnetic signals, then extracts the phase based on the difference in pole pairs and radial matching with the same radius line, and calculates the phase difference. Finally, due to the 180° repetition, disambiguation mapping is performed to uniquely map the phase difference to [0, 360°), and the absolute angle of a single turn is output.

[0109] Specifically, the weak differential signal output by the sensor is first amplified by an instrumentation amplifier integrated on the PCB, and then high-frequency noise is filtered out by a low-pass filter. The two processed high-quality sine and cosine signals are transmitted to the signal processing unit. The processing unit uses the phase difference between these two signals due to the difference in the number of pole pairs to perform calculations using a vernier algorithm, achieving high-multiple subdivision of the angle within one mechanical cycle, and finally obtaining a high-resolution absolute angle value. Since the difference in the number of pole pairs is 2, the phase difference repeats periodically at 180°. The system uses a disambiguation algorithm to uniquely map this phase difference to [0, 360°) to achieve single-cycle absolute angle output.

[0110] The core of the system's operation is angle calculation (i.e., vernier signal calculation and processing) utilizing the phase difference between the signals from the two magnetic rings. Two AMR sensors (4) synchronously acquire the magnetic field information of their respective magnetic rings, outputting two approximately sinusoidal and cosine voltage signals. Due to the difference in pole pair numbers, the actual electrical periods of these two signals differ. Combining this with the inherent phase difference generated by the "radial matching" layout, and through a specific vernier algorithm, the angle within one mechanical rotation cycle can be significantly subdivided, thus achieving a theoretical resolution far exceeding the limitations imposed by the number of pole pairs in a single magnetic ring.

[0111] With a pole pair difference of 2, the phase difference repeats twice within one revolution (period 180°). This embodiment of the invention employs a disambiguation algorithm to uniquely map the phase difference to [0, 360°). The algorithm is not limited to specific formulas or source code. After disambiguation is completed, the mechanical angle is obtained by dividing the phase difference by 2.

[0112] Small-signal error propagation can be approximated as angular jitter being about half that of phase difference jitter. Therefore, under the same analog chain noise and quantization step size, the angular jitter of a scheme with an pole-pair difference of 2 is theoretically reduced by half compared to a scheme with a difference of 1. Combined with phase interpolation / phase-locked loop and other processing, it is possible to achieve a visible resolution comparable to or even higher than that of a scheme with a difference of 1 while maintaining robustness.

[0113] In engineering applications, an pole-log difference of 2 results in lower sensitivity to radial eccentricity and air gap inhomogeneity, especially under conditions of slight eccentricity and temperature variations. The common-mode drift of the phase difference is more easily compensated for by filtering and segmented lookup tables. Furthermore, a difference of 2 results in a larger modulation index of the phase difference curve, which is beneficial for improving the reliability of the disambiguation segment decision and reducing the false positive rate. The algorithm does not limit specific formulas or source code.

[0114] This invention sets the absolute value of the difference in the number of pole pairs of the double-ring magnet to 2, and combines it with a radial matching and disambiguation algorithm for AMR dual sensors with the same radius (including but not limited to periodic expansion, lookup table mapping, and logical judgment). Under this condition, the phase difference repeats 180° within one revolution, and the processing unit performs disambiguation mapping to uniquely expand it to [0, 360°). Compared to the traditional vernier structure with a pole pair difference of 1, this invention achieves superior overall performance by trading a small potential loss of theoretical accuracy that can be compensated for through signal processing for a significant improvement in robustness, consistency, and mass production capability through an innovative design trade-off.

[0115] The specific advantages are as follows:

[0116] Firstly, it exhibits excellent robustness and anti-interference capabilities. The spatial frequency separation of the internal and external magnetic fields is significantly increased, effectively reducing the superposition of magnetic flux coupling and co-directional distortion. More importantly, the design with a difference of 2 allows its difference frequency signal (2 pairs of poles) to be separated from the most significant mechanical error in the spectrum, enabling the latter to be effectively suppressed through filtering. This results in stronger immunity to conditions such as radial eccentricity, air gap non-uniformity, and vibration.

[0117] Secondly, it offers superior error propagation characteristics. After disambiguation, the mechanical angle is calculated by dividing the phase difference by 2. This allows small-signal phase jitter caused by analog chain noise, quantization errors, etc., to be approximately attenuated to half its original value when propagated to the final angle, thus achieving better linearity and measurement stability at the system level. With the same phase subdivision capability Below, there are two missing schemes. The minimum step angle and the jitter propagation coefficient are both approximately the difference of a pair. This reduces the angle jitter by half, resulting in lower angle jitter and more stable measurement output after disambiguation.

[0118] Third, improved mass production consistency and assembly tolerance. The increased pole pitch difference facilitates the adoption of standardized magnet segmentation and fixture positioning processes, effectively relaxing assembly accuracy requirements, reducing manufacturing costs, and significantly improving product performance consistency during mass production.

[0119] Fourth, it maintains a compact structure and controllable algorithm overhead. Without increasing the axial dimensions, this invention successfully integrates a single PCB, soft magnetic shielding (ring-shaped soft magnetic cover 7), outer PC packaging, and coaxial bearing positioning, resulting in a simple and reliable overall system. The disambiguation algorithm used is mature, efficient, and easy to implement in standard DSPs or FPGAs.

[0120] Fifth, flexible scalability and calibration advantages. The preferred scheme is 19 pole pairs in the outer ring and 17 pole pairs in the inner ring (or vice versa). This combination of coprime pole pairs increases the least common multiple of the combined states and disperses the repetitive positions, which is beneficial for dispersing and compensating for systematic errors during factory calibration and online calibration, and further improves batch consistency and long-term stability.

[0121] Sixth, in the simplest implementation without interpolation, the native discrete resolution of the two-pair difference scheme may be lower than that of the one-pair difference scheme. However, with the disambiguation mapping and phase interpolation / phase-locked loop processing of this invention, the final visible resolution is no less than that of the one-pair difference scheme, and significant improvements are achieved in robustness and engineering manufacturability.

[0122] Obviously, the embodiments described above are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0123] In the several embodiments provided in this invention, it should be understood that the disclosed apparatus and methods can also be implemented in other ways. The apparatus and method embodiments described above are merely illustrative. For example, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0124] In addition, the functional modules in the various embodiments of the present invention can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0125] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, electronic device, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory, random access memory, magnetic disks, or optical disks. It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0126] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular forms “a,” “the,” and “the” used in the embodiments of this invention are also intended to include the plural forms unless the context clearly indicates otherwise.

[0127] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0128] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0129] The terms "first" and "second" used in the embodiments are merely to distinguish similar objects and do not represent a specific ordering of objects. It is understood that "first" and "second" can be interchanged in a specific order or sequence where permitted. It should be understood that the objects distinguished by "first" and "second" can be interchanged where appropriate so that the embodiments described herein can be implemented in an order other than those illustrated or described herein.

[0130] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A magnetic encoder for a permanent magnet synchronous joint motor, characterized in that, Includes a magnetic encoder module and an AMR sensor array; The magnetic encoder module is installed on the motor shaft end; the magnetic encoder module includes an outer ring magnet (3) and an inner ring magnet (2) arranged coaxially; the absolute value of the difference between the number of pole pairs of the outer ring magnet (3) and the inner ring magnet (2) is 2; The AMR sensor array is arranged in the magnetic field region of the outer ring magnet (3) and the inner ring magnet (2); the AMR sensor array includes two AMR sensors (4) located on the same radius line in the magnetic field region; the two AMR sensors (4) correspond to the magnetic field regions of the outer ring magnet (3) and the inner ring magnet (2) respectively, and are used to synchronously collect the signals of their respective magnetic rings; The signal achieves high-resolution detection of the absolute angle of a single loop through the double-ring vernier effect and disambiguation algorithm.

2. The magnetic encoder for a permanent magnet synchronous joint motor according to claim 1, characterized in that, The outer ring magnet (3) and the inner ring magnet (2) are arranged with different radii, with the outer ring magnet (3) having a larger radius than the inner ring magnet (2), forming a radius difference; The radial mounting positions of the two AMR sensors (4) are matched with the radius difference so that the two sensors can obtain the optimal and stable phase difference signal.

3. The magnetic encoder for a permanent magnet synchronous joint motor according to claim 1, characterized in that, The outer ring magnets (3) consist of 19 pairs, and the inner ring magnets (2) consist of 17 pairs; or, the outer ring magnets (3) consist of 17 pairs, and the inner ring magnets (2) consist of 19 pairs.

4. The magnetic encoder for a permanent magnet synchronous joint motor according to claim 1, characterized in that, Magnetic flux converging elements (5) are set on both sides of the AMR sensor array to concentrate magnetic lines of force, increase effective magnetic flux density and enhance signal-to-noise ratio; The magnetic flux converging element (5) is designed to be symmetrical arc-shaped; the material of the magnetic flux converging element (5) is a soft magnetic material with a relative permeability greater than 5000.

5. The magnetic encoder for a permanent magnet synchronous joint motor according to any one of claims 1 to 4, characterized in that, Magnetic field isolation components are provided on both sides of the magnetic encoder module and the AMR sensor array; the magnetic field isolation component is an annular soft magnetic cover (7) with an opening at the top; the opening at the top is used to allow axial magnetic flux to pass through; the cover of the annular soft magnetic cover (7) is used to block radial magnetic leakage interference.

6. The magnetic encoder for a permanent magnet synchronous joint motor according to claim 5, characterized in that, The outer layer of the annular soft magnetic cover (7) is provided with an outer encapsulation cover; the outer encapsulation cover is made of polycarbonate material, which is completely covered outside the annular soft magnetic cover (7) and covers the top of the opening of the annular soft magnetic cover (7), forming a double-layer protective structure of inner isolation and outer protection.

7. The magnetic encoder for a permanent magnet synchronous joint motor according to any one of claims 1 to 4, characterized in that, The magnetic encoder module is fixed to the motor end cover by installing a deep groove ball bearing (6); The AMR sensor array is carried on a single PCB; two AMR sensors (4) are located on the same radius line of the PCB; the PCB is also equipped with differential amplification and filtering circuits.

8. A permanent magnet synchronous joint motor (1), characterized in that, It is equipped with a magnetic encoder for a permanent magnet synchronous joint motor as described in any one of claims 1 to 6.

9. A method for detecting the disambiguation angle of a magnetic encoder used in a permanent magnet synchronous joint motor, characterized in that, The magnetic encoder is also provided with differential amplification and filtering circuits; Disambiguation angle detection methods include: S1. Two AMR sensors synchronously acquire the magnetic field information of their respective magnetic rings and output detection signals; S2. The detection signal is differentially amplified and low-pass filtered through a differential amplification and filtering circuit; S3. Based on the two processed detection signals, obtain the vernier phase difference using a vernier algorithm; S4. Based on the vernier phase difference, the 180° period vernier phase difference is expanded to a mechanical angle of 0 to 360° through disambiguation mapping to obtain a high-resolution absolute angle signal.

10. The method for disambiguation angle detection of a magnetic encoder for a permanent magnet synchronous joint motor according to claim 9, characterized in that, In step S3, the cursor algorithm employs one or more of the following: the CORDIC algorithm, LUT-based lookup table interpolation, or polynomial fitting. S3 specifically includes: ； ； ； In the formula For mechanical angle, The electrical angle phase obtained by the AMR sensor corresponding to the outer ring magnet, The number of pole pairs of the outer ring magnet, For the electric angle phase error term of the outer ring magnet, The electrical angle phase obtained by the AMR sensor corresponding to the inner ring magnet, The number of pole pairs of the inner ring magnet, For the electric angle phase error term of the inner ring magnet, For phase difference, for and The difference; It is an identity sign; S4 specifically includes: Let the absolute value of the difference between the extreme logarithms be... ;when hour The process repeats twice within one revolution, with a period of 180°. Therefore, the mechanical angle is represented by a disambiguation mapping. The only range that recovers to is greater than or equal to 0 degrees and less than 360 degrees; .

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