Self-sensing electric motor and method for measuring position of rotor of electric motor

Abstract

Provided in the present application are a self-sensing electric motor and a method for measuring the position of a rotor of an electric motor. The self-sensing electric motor comprises a rotating shaft, wherein a rotor is provided on the rotating shaft, and a stator is provided outside the rotor in the radial direction of the rotor; a Hall support is provided at one end of the stator in the axial direction of the rotating shaft, a main control circuit board is provided on the Hall support, and a controller is provided on the main control circuit board; three or more Hall sensors are provided on the Hall support, and the Hall sensors are configured to acquire an electrical-angle signal of the rotor; an absolute position encoder comprises a read head and graduation lines, the read head being arranged on the Hall support, and the graduation lines being arranged on an outer wall of a magnet in the rotor; the read head cooperates with the graduation lines, so as to acquire initial position information of the rotor; and both the Hall sensors and the absolute position encoder are connected to the controller, and the controller calculates the mechanical position of the rotor on the basis of the electrical angle signal and the initial position information of the rotor and by using a nonlinear compensation method.

Description

Self-sensing motor and motor rotor position detection method

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on October 24, 2023, with application number 202311382074.1, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application belongs to the field of motors, and for example relates to a self-sensing motor and a method for detecting the position of a motor rotor. Background Art

[0003] In motor control, accurate rotor position information is crucial for achieving field-oriented and feedback control. However, conventional methods for obtaining rotor position information typically require the installation of additional position sensors, which not only increases motor manufacturing costs but also increases system complexity. Furthermore, sampling errors caused by the imperfections of the motor's magnetic field affect the position signal, resulting in significant errors in rotor position estimation.

[0004] Summary of the Invention

[0005] The present application provides a self-sensing motor and a method for detecting the position of a motor rotor.

[0006] According to a first aspect of an embodiment of the present application, the present application provides a self-sensing motor, comprising a rotating shaft, a rotor, a stator, a Hall bracket, a main control circuit board, a Hall sensor, and an absolute position encoder;

[0007] The rotor is provided on the rotating shaft, and the stator is provided on the outside of the rotor along the radial direction of the rotor; the Hall bracket is provided at one end of the stator along the axial direction of the rotating shaft, the main control circuit board is provided on the Hall bracket, and the controller is provided on the main control circuit board;

[0008] The Hall effect sensor is provided on the Hall effect bracket, wherein N is greater than or equal to 3, and the Hall effect sensor is configured to obtain an electrical angle signal of the rotor; the absolute position encoder includes a reader and a scale line, the reader is provided on the Hall effect bracket, and the scale line is provided on the outer wall of the magnet in the rotor; the reader and the scale line cooperate to obtain the initial position information of the rotor;

[0009] The Hall sensor and the absolute position encoder are both connected to the controller. The controller calculates the mechanical position of the rotor according to the electrical angle signal and initial position information of the rotor and adopts a nonlinear compensation method.

[0010] According to a second aspect of the embodiments of the present application, the present application provides a method for detecting the rotor position of a motor based on the above-mentioned self-sensing motor, comprising the following steps:

[0011] The magnetic field of the rotor is detected by a Hall sensor to obtain the rotor's electrical angle signal and send it to the controller. The absolute position encoder is used to obtain the initial position information of the rotor and send it to the controller. Based on the rotor's electrical angle signal and initial position information, the controller uses fusion and nonlinear compensation methods to calculate the mechanical position of the rotor. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG1 is a cross-sectional view of a self-sensing motor provided in an embodiment of the present application;

[0013] FIG2 is a schematic structural diagram of a Hall effect bracket in a self-sensing motor provided in an embodiment of the present application;

[0014] FIG3 is a distribution diagram of black and white coatings on the outer wall of a magnet in a rotor of a self-sensing motor provided in an embodiment of the present application;

[0015] Explanation of the accompanying drawings: 1. rotating shaft; 2. rotor; 3. stator; 4. Hall bracket; 41. first annular body; 411. through hole; 412. notch; 42. second annular body; 421. through groove; 5. main control circuit board; 10. motor main frame; 20. first mounting flange; 30. second mounting flange; 40. first bearing; 50. second bearing; 60. axial pressure plate. DETAILED DESCRIPTION

[0016] The terms “first,” “second,” etc. used herein do not specifically refer to an order or sequence, nor are they intended to limit this application. They are merely used to distinguish elements or operations described with the same technical terms.

[0017] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0018] As used herein, "and / or" includes any and all combinations of the items mentioned.

[0019] Regarding "plurality" in this document, "plurality" includes "two" and "more than two"; regarding "plurality groups" in this document, "plurality groups" includes "two groups" and "more than two groups".

[0020] As shown in Figure 1, the self-sensing motor provided in this application includes a rotating shaft 1, a rotor 2, a stator 3, a Hall effect sensor 4, a main control circuit board 5, a Hall effect sensor 4111, and an absolute position encoder. The rotor 2 is disposed on the rotating shaft 1, and the stator 3 is disposed radially and externally of the rotor 2. A Hall effect sensor 4 is disposed axially at one end of the stator 3, and a main control circuit board 5 is disposed at the end of the Hall effect sensor 4 away from the stator 3. A controller is disposed on the main control circuit board 5.

[0021] N Hall sensors 4111 are provided on the Hall bracket 4, where N ≥ 3. The Hall sensors 4111 are configured to obtain the electrical angle signal of the rotor 2, and the electrical angle between adjacent Hall sensors 4111 is 360 / N. By processing the signals of the multiple Hall sensors 4111, the robustness to sampling errors can be greatly improved. The absolute position encoder includes a read head 4112 and a scale line 211, wherein the read head 4112 is provided on the Hall bracket 4, and the scale line 211 is provided on the outer wall of the magnet 21 in the rotor 2. The read head 4112 cooperates with the scale line 211 to obtain the initial position information of the rotor 2. By providing an absolute position encoder, the problem of inconsistency between the electrical angle and the mechanical angle of the rotor 2 can be solved.

[0022] The Hall sensor 4111 and the absolute position encoder are both connected to the controller. The controller calculates the mechanical position of the rotor 2 according to the electrical angle signal of the rotor 2 and the initial position information of the rotor 2 and adopts a nonlinear compensation method.

[0023] In this embodiment, as shown in FIG2 , the Hall stent 4 includes a first annular body 41 and a second annular body 42 , wherein the inner diameter of the first annular body 41 is equal to the inner diameter of the second annular body 42 , and the outer diameter of the first annular body 41 is larger than the outer diameter of the second annular body 42 . The first annular body 41 and the second annular body 42 are integrally formed, or one end of the first annular body 41 is fixedly connected to one end of the second annular body 42 . The second annular body 42 is configured to axially position the rotor 2 .

[0024] A through hole 411 is formed on the first annular body 41 along its axial direction, and is configured to accommodate a Hall sensor 4111. A through groove 421 is formed on the inner walls of the first annular body 41 and the second annular body 42 along its axial direction, and is configured to accommodate a reader 4112.

[0025] In order to reduce the weight of the Hall bracket 4 , notches 412 may be provided on the first annular body 41 between adjacent through holes 411 , so that a plurality of arc-shaped blocks spaced apart from each other are formed on the first annular body 41 .

[0026] In this embodiment, when N=3, the three Hall sensors 4111 may be placed at positions of 0, 120, and 240 electrical angles, respectively.

[0027] In the above embodiment, the self-sensing motor provided in the present application further includes a motor main frame 10 , a first mounting flange 20 , a second mounting flange 30 , a first bearing 40 , a second bearing 50 and an axial pressure plate 60 .

[0028] The motor main frame 10 is provided with a first mounting flange 20 and a second mounting flange 30 at each end. Together, the first and second mounting flanges 20 and 30 form a closed cavity. The rotor 2, stator 3, Hall effect holder 4, main control circuit board 5, Hall effect sensor 4111, and absolute position encoder are all housed within this cavity. A first bearing 40 is provided within the first mounting flange 20, and a second bearing 50 is provided within the second mounting flange 30. An axial pressure plate 60 is provided within the Hall effect holder 4, pressing against the end of the rotor 2 closest to the Hall effect holder 4. One end of the rotating shaft 1 extends through the axial pressure plate 60 and the first bearing 40, respectively.

[0029] In the above embodiment, the encoding method of the absolute position encoder can be magnetic pole, photoelectric, eddy current, etc., and can also be encoded using the eddy current characteristics of asymmetric magnetic conductive materials, or using capacitance, inductance, sound characteristics, etc.

[0030] In the above embodiment, it is assumed that the absolute position encoder uses a photoelectric encoding method, and the lines 211 on the outer wall of the magnet 21 in the rotor 2 are implemented using a black and white coating. As shown in FIG3 , the coating on the outer wall of the magnet 21 is divided into 10 patterns, each pattern comprising four black and white coatings. Four consecutive coatings starting from the starting position constitute a pattern, and these 10 patterns are 0001, 0010, 0011, 0100, 0101, 1000, 1001, 1010, 1011, and 1100.

[0031] The self-sensing motor provided in the present application is provided with a Hall sensor, an absolute position encoder and a controller; and the Hall sensor is used to detect the magnetic field of the rotor to obtain the electrical angle of the rotor; the absolute position encoder is used to obtain the initial position information of the rotor; the controller uses the electrical angle and initial position information of the rotor and adopts fusion and nonlinear compensation methods to calculate the actual mechanical position value of the motor rotor with high precision, thereby accurately realizing the detection and control of the motor rotor position, and thus promoting the development of the motor control field.

[0032] Based on the self-sensing motor provided in the embodiment of the present application, the embodiment of the present application also provides a method for detecting the position of a motor rotor, comprising the following steps:

[0033] S1. Use the Hall sensor 4111 to detect the magnetic field of the rotor 2, obtain the electrical angle signal of the rotor 2 and send it to the controller.

[0034] S2. Use the absolute position encoder to obtain the initial position information of the rotor 2 and send it to the controller.

[0035] The absolute position encoder obtains the initial position information of the rotor 2 through the absolute position encoding between the 0 and 1 phases.

[0036] S3. Based on the electrical angle signal and initial position information of rotor 2, the controller calculates the mechanical position of rotor 2 using a fusion and nonlinear compensation method. The calculation process is as follows:

[0037] S31 , filtering the electrical angle signal of the rotor 2 , and performing a baseband discrete Fourier transform on the filtered electrical angle signal to obtain the electrical angle of the rotor 2 .

[0038] S32 . Taking the initial position information of the rotor 2 as the initial value, integrate the electrical angle of the rotor 2 to obtain an estimated mechanical position value of the rotor 2 .

[0039] S33 , compensating the estimated mechanical position value of the rotor 2 by looking up a preset mode table to obtain a transitional mechanical position value of the rotor 2 .

[0040] S34 , filtering the mechanical position transition value of the rotor 2 to obtain a high-precision mechanical position of the rotor 2 .

[0041] In the above step S3, the fusion and nonlinear compensation method can be implemented by an observer or a lookup table compensation followed by filtering.

[0042] The following uses an example to illustrate the process of the controller calculating the high-precision mechanical position of the rotor 2 in the motor rotor position detection method provided in the embodiment of the present application.

[0043] Assume that each pair of magnetic poles in rotor 2 has four position values, where an electrical angle of 0° corresponds to position value 1, an electrical angle of 90° corresponds to position value 2, an electrical angle of 180° corresponds to position value 3, and an electrical angle of 270° corresponds to position value 4. The motor's rotor 2 includes multiple sets of magnets, each of which produces north and south poles. Since magnetic poles appear in pairs, rotor 2 has multiple pairs of magnetic poles.

[0044] The controller processes the electrical angle signal of the rotor 2 to obtain the electrical angle of the rotor 2 and converts the electrical angle into a position value.

[0045] While continuously detecting the position value sequence of the rotor 2, the controller samples the state value 0 or 1 output by the read head 4112 in the absolute position encoder.

[0046] The controller searches for the mode number corresponding to the current position value sequence and state value in the preset mode table according to the continuous position value sequence and state value, obtains the mode code according to the mode number, and obtains the mechanical position transition value of the rotor 2 according to the mode code.

[0047] For example, assuming that the continuous position values ​​1, 2, 3, and 4 indicate forward rotation of the rotor 2, then the continuous position values ​​4, 3, 2, and 1 indicate reverse rotation of the rotor 2. Assuming that the continuous position values ​​are 4, 3, 2, and 1, and the state values ​​are 0, 0, 0, and 1, by searching a preset mode table (not shown) for the mode number corresponding to the current position value sequence and state value, the mode number is obtained to be 7; the mode code obtained by calculating the mode number is (7+1)*12-11=85, and the mechanical position transition value of the rotor 2 is obtained by looking up the table based on the mode code.

[0048] The mechanical position transition value of the rotor 2 is filtered to obtain a high-precision actual value of the mechanical position of the rotor 2 .

Claims

1. A self-sensing motor, comprising a rotating shaft (1), a rotor (2), a stator (3), a Hall bracket (4), a main control circuit board (5), a Hall sensor (4111) and an absolute position encoder; The rotor (2) is arranged on the rotating shaft (1), and the stator (3) is arranged outside the rotor (2) along the radial direction of the rotor (2); the Hall bracket (4) is arranged at one end of the stator (3) along the axial direction of the rotating shaft (1), the main control circuit board (5) is arranged on the Hall bracket (4), and the main control circuit board (5) is arranged on the controller; The Hall support (4) is provided with N Hall sensors (4111), wherein: N≥3, the Hall sensor (4111) is configured to obtain an electrical angle signal of the rotor (2); the absolute position encoder comprises a reader (4112) and a scale line (211), the reader (4112) is arranged on the Hall bracket (4), and the scale line (211) is arranged on the outer wall of the magnet (21) in the rotor (2); the reader (4112) cooperates with the scale line (211) to obtain initial position information of the rotor (2); The Hall sensor (4111) and the absolute position encoder are both connected to the controller, and the controller calculates the mechanical position of the rotor (2) based on the electrical angle signal and initial position information of the rotor (2) and adopts a nonlinear compensation method.

2. The self-sensing motor according to claim 1, wherein: The electrical angle between adjacent Hall sensors (4111) is 360 / N.

3. The self-sensing motor according to claim 1, wherein: The Hall bracket (4) comprises a first annular body (41) and a second annular body (42); the inner diameter of the first annular body (41) is equal to the inner diameter of the second annular body (42), and the outer diameter of the first annular body (41) is greater than the outer diameter of the second annular body (42); the second annular body (42) is configured to axially position the rotor (2); A through hole (411) is provided on the first circular body (41) along the axial direction of the first circular body (41), and the through hole (411) is configured to accommodate the Hall sensor (4111); and a through groove (421) is provided on the inner walls of the first circular body (41) and the second circular body (42) along the axial direction of the first circular body (41), and the through groove (421) is configured to accommodate the reader (4112).

4. The self-sensing motor according to claim 3, wherein: A notch (412) is provided on the first annular body (41) between adjacent through holes (411), so that a plurality of arc-shaped blocks spaced apart from each other are formed on the first annular body (41).

5. The self-sensing motor according to any one of claims 1 to 4, further comprising a motor main frame (10), a first mounting flange (20), a second mounting flange (30), a first bearing (40), a second bearing (50) and an axial pressure plate (60); The first mounting flange (20) and the second mounting flange (30) are respectively arranged at both ends of the motor main frame (10), and the first mounting flange (20) and the second mounting flange (30) and the motor main frame (10) form a closed cavity; the rotor (2), the stator (3), the Hall bracket (4), the main control circuit board (5), the Hall sensor (4111) and the absolute position encoder are all arranged in the cavity; the first mounting flange (20) is arranged with the first bearing (40), and the second mounting flange (30) is arranged with the second bearing (50); the Hall bracket (4) is arranged with the axial pressure plate (60), and the axial pressure plate (60) is pressed on one end of the rotor (2) close to the Hall bracket (4); one end of the rotating shaft (1) passes through the axial pressure plate (60) and the first bearing (40) in sequence.

6. The self-sensing motor according to any one of claims 1 to 4, wherein: The encoding method of the absolute position encoder is one of magnetic pole, photoelectric and eddy current forms, or the eddy current characteristics of asymmetric magnetic conductive materials are used for encoding, or the capacitance, inductance and sound characteristics are used for encoding.

7. The self-sensing motor according to claim 6, wherein: In response to the encoding method of the absolute position encoder being a photoelectric form, the engraved lines (211) on the outer wall of the magnet (21) in the rotor (2) are implemented by a black and white coating.

8. The self-sensing motor according to claim 7, wherein: The black and white coatings on the outer wall of the magnet (21) are divided into 10 patterns, each pattern including 4 black and white coatings.

9. A method for detecting the rotor position of a motor based on the self-sensing motor according to any one of claims 1 to 8, comprising: Using a Hall sensor (4111) to detect the magnetic field of the rotor (2), obtaining an electrical angle signal of the rotor (2) and sending it to a controller; Using an absolute position encoder to obtain initial position information of the rotor (2) and sending it to a controller; According to the electrical angle signal and initial position information of the rotor (2), the controller adopts fusion and nonlinear compensation The mechanical position of the rotor (2) is calculated using a compensation method.

10. The motor rotor position detection method according to claim 9, wherein: The process in which the controller calculates the mechanical position of the rotor using a fusion and nonlinear compensation method based on the electrical angle signal and initial position information of the rotor (2) is as follows: Filtering the electrical angle signal of the rotor (2), and performing a baseband discrete Fourier transform on the filtered electrical angle signal to obtain the electrical angle of the rotor (2); Using the initial position information of the rotor (2) as an initial value, integrating the electrical angle of the rotor (2) to obtain an estimated mechanical position value of the rotor (2); By looking up a preset mode table, the estimated value of the mechanical position of the rotor (2) is compensated to obtain a transition value of the mechanical position of the rotor (2); The mechanical position transition value of the rotor (2) is filtered to obtain a high-precision actual value of the mechanical position of the rotor (2).

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