Method for detecting rotor position angle of skewed pole axial flux permanent magnet motor

Abstract

The invention provides a skewed pole axial magnetic flux permanent magnet motor rotor position angle detection method, a skewed pole axial magnetic flux permanent magnet motor comprises a permanent magnet with skewed poles, annular windings, stator teeth and a rotor, a stator slot is formed between any two stator teeth, and in-phase annular windings are arranged in the stator slots; the two groups of linear Hall sensors are arranged in a stator groove of the stator at equal intervals in the circumferential direction, and the radius of one group of linear Hall sensors relative to the axis center is a first radius; the radius of the other group of linear Hall sensors relative to the axis center is a second radius; the first radius is not equal to the second radius; after analog-to-digital conversion is carried out on voltage signals output by the two groups of linear Hall sensors, a pair of orthogonal signals is obtained through preprocessing of grouping signal superposition and linear combination; a rotor angle value and a rotation speed value are estimated based on a pair of orthogonal signals of a synchronous reference frame phase-locked loop.

Description

Technical Field

[0001] The invention relates to a technology for detecting the rotor angle of a skew-pole axial flux permanent magnet motor, and in particular to a method for detecting the rotor position angle of a skew-pole axial flux permanent magnet motor. Background Art

[0002] In the field of motors, with the rapid development of electric vehicles, wind power generation and other fields, permanent magnet synchronous motors (PMSM) have become the first choice for these applications due to their high efficiency and high power density. Among PMSMs, axial flux permanent magnet motors have gradually become an important development direction due to their efficient magnetic circuit design and compact structure.

[0003] When vector controlling a traditional AC axial flux motor, it is necessary to provide accurate rotor angle and rotation speed. Linear Hall sensors have the advantages of small size and high sensitivity. They are often installed inside compact devices such as pan / tilts and oil pump motors to estimate the rotor position by detecting the leakage magnetic field of the permanent magnet inside the motor.

[0004] For example, CN117674662A first determines the installation scheme of the linear Hall sensor: install a group of three Hall sensors or two groups of six linear Hall sensors; then, perform pre-harmonic suppression processing on the original output signal of the Hall sensor to obtain a group of high-sinusoidal orthogonal signals; finally, calculate the motor rotor angle based on the pre-processed orthogonal signal, achieving high compactness and high-precision angle detection to meet the angle and speed measurement requirements of the axial flux motor. However, due to the use of a pre-filter, the electromagnetic radiation system has a large angle estimation error in the low-speed area and weak dynamic response performance.

[0005] The skew-pole permanent magnet synchronous motor is a new type of permanent magnet motor that uses permanent magnets as rotors, which can effectively reduce cogging torque and torque pulsation. However, since the magnetic field of the skew-pole permanent magnet synchronous motor is generated by permanent magnets, it is more susceptible to external magnetic fields, temperature changes, wear and other factors than traditional motors, resulting in unstable magnetic fields. This brings new challenges to the accurate detection of rotor position. Traditional rotor position detection methods, such as those based on Hall sensors or incremental encoders, are usually arranged at specific positions on the motor, but due to the complexity of the skew-pole design, it is difficult to achieve high-precision rotor position detection throughout the entire operating range.

[0006] In order to solve the above problems, people have been seeking an ideal technical solution. Summary of the invention

[0007] The purpose of the present invention is to address the deficiencies of the prior art and thus provide a method for detecting the rotor position angle of a skewed-pole axial flux permanent magnet motor. By installing six linear Hall sensors on different sections of the stator slot, the magnetic field changes can be captured in real time and the rotor position angle can be accurately measured. This method effectively improves the accuracy of rotor position angle detection, especially in skewed-pole axial flux permanent magnet motors, and can significantly improve the motor's operating performance and control accuracy.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is: a method for detecting the rotor position angle of a skewed pole axial flux permanent magnet motor, wherein the skewed pole axial flux permanent magnet motor comprises permanent magnets with skewed poles, annular windings, stator teeth and a rotor, wherein the permanent magnets with skewed poles are evenly installed on the rotor along the circumferential direction, and the magnetization directions of two adjacent permanent magnets are opposite; a stator slot is formed between any two stator teeth, and a same-phase annular winding is arranged in the stator slot; It comprises a first linear Hall sensor, a second linear Hall sensor, a third linear Hall sensor, a fourth linear Hall sensor, a fifth linear Hall sensor and a sixth linear Hall sensor which are arranged at equal intervals in the stator slots of the stator along the circumferential direction; the magnetic sensitive surface of any linear Hall sensor is opposite to the salient pole structure surface of the mover; The radius of the first linear Hall sensor, the second linear Hall sensor, and the third linear Hall sensor relative to the center of the axis is a first radius; the radius of the fourth linear Hall sensor, the fifth linear Hall sensor, and the sixth linear Hall sensor relative to the center of the axis is a second radius; wherein the first radius is not equal to the second radius; After the voltage signals output by the six linear Hall sensors are converted into digital form, they are preprocessed by grouping signal superposition and linear combination to obtain a pair of orthogonal signals. Step 3, estimating the rotor angle value and the rotation speed value from a pair of orthogonal signals obtained in step 2 based on the synchronous reference frame phase-locked loop.

[0009] Preferably, the first linear Hall sensor is installed in any stator slot, the second linear Hall sensor is installed in the stator slot M-th away from the first linear Hall sensor along a preset direction, the third linear Hall sensor is installed in the stator slot M-th away from the second linear Hall sensor along a preset direction; the fourth linear Hall sensor is installed in the stator slot M-th away from the third linear Hall sensor along a preset direction, the fifth linear Hall sensor is installed in the stator slot M-th away from the fourth linear Hall sensor along a preset direction, and the sixth linear Hall sensor is installed in the stator slot M-th away from the fifth linear Hall sensor along a preset direction; M= ks / 6p ,in, k is an integer and k≠3n,n=1,2,... , sis the number of slots in the stator, p is the number of motor pole pairs.

[0010] Preferably, after analog-to-digital conversion processing is performed on the voltage signals output by the six linear Hall sensors, the following is obtained: in, V ACFD1 is a digital signal obtained by analog-to-digital conversion of the output voltage signal of the first linear Hall sensor, V ACFD2 is a digital signal obtained by analog-to-digital conversion of the output voltage signal of the second linear Hall sensor, V ACFD3 is a digital signal after the output voltage signal of the third linear Hall sensor is converted into a digital signal. V ACFD4 is a digital signal obtained by analog-to-digital conversion of the output voltage signal of the fourth linear Hall sensor, V ACFD5 is a digital signal obtained by analog-to-digital conversion of the output voltage signal of the fifth linear Hall sensor, V ACFD6 is a digital signal obtained by analog-to-digital conversion of the output voltage signal of the sixth linear Hall sensor, B 1i , B 2i , B 3i , B 4i , B 15i , B 6i It represents the amplitude of each harmonic of the output voltage signal of the first, second, third, fourth, fifth and sixth linear Hall sensors after analog-to-digital conversion. f 1 represents the electrical angle value of the first linear Hall sensor relative to the initial position of the motor, f 2 represents the electrical angle value of the fourth linear Hall sensor relative to the initial position of the motor. The electrical angle difference between the first linear Hall and the fourth linear Hall is e ( i 1 )= f 2- f 1= 2kπ±π / 6,k =0,1,2,…, i is the actual electrical angle of the rotor.

[0011] Preferably, the six voltage signals after analog-to-digital conversion are preprocessed by grouping signal superposition and linear combination, including the following steps: Based on the group superposition model, the six voltage signals after analog-to-digital conversion areV ACFD1 、V ACFD2 、V ACFD3 、V ACFD4 、 V ACFD5 、V ACFD6 Perform group signal superposition to obtain a two-phase third harmonic sinusoidal signal; Among them, the group superposition model is: ; Among them, the electrical angle of the phase difference between the first linear Hall and the fourth linear Hall is e ( i 1 ); V FD-3α , V FD-3β The difference between the two e (3 i 1 ) is a sinusoidal signal of the third harmonic of the electrical angle, V ACFD1 、V ACFD2 、V ACFD3 、V ACFD4 、V ACFD5 、V ACFD6 are the output signals of the first, second, third, fourth, fifth and sixth linear Hall sensors, U m Represents the amplitude of the third harmonic of the Hall signal output, i is the actual electrical angle of the rotor; based on the linear combination, the sinusoidal signals of the two-phase third harmonic are processed to obtain a pair of orthogonal signals.

[0012] The present invention has outstanding substantive features and significant progress compared to the prior art. Specifically, (1) This technology can directly provide two-phase orthogonal third harmonic signals from six-phase Hall signals without the need for Clark transformation and filtering.

[0013] (2) This technology reduces the dynamic response time of the decoding algorithm, especially in the skew-pole axial flux permanent magnet motor, which can significantly improve the motor's operating performance and control accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1This is a flow chart of the rotor position angle detection method of the skew-pole axial flux permanent magnet motor proposed in Example 1 of the present invention.

[0015] Figure 2 This is a module connection diagram of the rotor position angle detection method of the skew-pole axial flux permanent magnet motor proposed in Example 1 of the present invention.

[0016] Figure 3 This is a module diagram of the synchronous reference frame phase-locked loop involved in Example 1 of the present invention.

[0017] Figure 4 This is a schematic structural diagram of an axial flux permanent magnet motor with skewed permanent magnet poles in Example 2 of the present invention.

[0018] Figure 5 This is a schematic diagram of the structure of the permanent magnets on the rotor disk of the axial flux permanent magnet motor in Example 2 of the present invention.

[0019] Figure 6 Schematic diagram of the axial magnetic field distribution of six linear Hall detection points in Example 2 of the present invention.

[0020] Figure 7 This is a signal waveform diagram after the grouped signals are superimposed and linearly combined in Example 2 of the present invention.

[0021] Figure 8 This is a waveform diagram of the angle signal obtained by calculation in Example 2 of the present invention.

[0022] In the figure: 1. first linear Hall sensor; 2. second linear Hall sensor; 3. third linear Hall sensor; 4. fourth linear Hall sensor; 5. fifth linear Hall sensor, 6. sixth linear Hall sensor; 7. stator slot; 8. rotor; 9. permanent magnet; 10. digital signal processor; 11. stator teeth; 12. in-phase annular winding; 13. phase detector; 14. loop filter; 15. voltage-controlled oscillator; 16. synchronous reference frame phase-locked loop. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is further described in detail below through specific implementation methods.

[0024] Example 1 This embodiment provides a method for detecting the rotor position angle of a slanted-pole axial flux permanent magnet motor. Figure 1-3 As shown, the oblique-pole axial flux permanent magnet motor includes a permanent magnet 9 with oblique poles, an annular winding 12, a stator tooth 11 and a rotor 8, wherein the permanent magnet 9 with oblique poles is evenly installed on the rotor 8 along the circumferential direction, and the magnetization directions of two adjacent permanent magnets 9 are opposite; a stator slot 7 is formed between any two stator teeth 11, and a same-phase annular winding 12 is arranged in the stator slot 7.

[0025] Furthermore, the method for detecting the rotor position angle of the skew-pole axial flux permanent magnet motor comprises the following steps: Step 1, a first linear Hall sensor 1, a second linear Hall sensor 2, a third linear Hall sensor 3, a fourth linear Hall sensor 4, a fifth linear Hall sensor 5 and a sixth linear Hall sensor 6 are arranged at equal intervals in the stator slot 7 of the stator along the circumferential direction; the magnetic sensitive surface of any linear Hall sensor is opposite to the salient pole structure surface of the mover; The radius of the first linear Hall sensor 1, the second linear Hall sensor 2, and the third linear Hall sensor 3 relative to the axis center is the first radius; the radius of the fourth linear Hall sensor 4, the fifth linear Hall sensor 5, and the sixth linear Hall sensor 6 relative to the axis center is the second radius; wherein the first radius is not equal to the second radius. Due to the existence of the oblique pole of the permanent magnet, at different radii of different notches, the electrical angle difference between the first linear Hall sensor 1 and the fourth linear Hall sensor 4 is e ( i 1 )= f 2- f 1, f 1 represents the electrical angle value of the first linear Hall sensor relative to the initial position of the motor, and φ2 represents the electrical angle value of the fourth linear Hall sensor relative to the initial position of the motor.

[0026] Specifically, the first radius and the second radius are both larger than the inner diameter of the stator and smaller than the outer diameter of the rotor, so as to ensure that the magnetic sensitive surfaces of the first to six linear Hall sensors are opposite to the slots.

[0027] In one embodiment, assuming that the counterclockwise direction is the positive direction, when the rotor rotates at a constant speed in the positive direction, the magnetization mode of the permanent magnet causes the air gap flux density near the stator slot 7 to present a distribution characteristic close to a sine waveform. Therefore, a linear Hall sensor can be installed to detect the air gap flux.

[0028] Specifically, the first linear Hall sensor 1 is installed in any stator slot 7, the second linear Hall sensor 2 is installed in the stator slot 7 that is M-th away from the first linear Hall sensor 1 along a preset direction, for example, counterclockwise, the third linear Hall sensor 3 is installed in the stator slot 7 that is M-th away from the second linear Hall sensor 2 along a preset direction; the fourth linear Hall sensor 4 is installed in the stator slot 7 that is M-th away from the third linear Hall sensor 3 along a preset direction, the fifth linear Hall sensor 5 is installed in the stator slot 7 that is M-th away from the fourth linear Hall sensor 4 along a preset direction, and the sixth linear Hall sensor 6 is installed in the stator slot 7 that is M-th away from the fifth linear Hall sensor 5 along a preset direction; M= ks / 6p ,in, k is an integer and k≠3n,n=1,2,... , s is the number of slots in the stator, p is the number of motor pole pairs.

[0029] Step 2: After performing analog-to-digital conversion on the voltage signals output by the six linear Hall sensors, a pair of orthogonal signals are obtained through preprocessing of grouped signal superposition and linear combination.

[0030] Specifically, the voltage signal output by the linear Hall sensor is an analog signal. To facilitate subsequent calculations, the analog signal needs to be converted into a digital signal through analog-to-digital conversion. Assuming that the counterclockwise direction is the positive direction, when the rotor 8 rotates at a constant speed in the positive direction, the electrical angle difference between the first linear Hall sensor 1 and the fourth linear Hall sensor 4 is e ( i 1 )=30°, and the phases of the first, second and third linear Hall sensors are 2π / 3 different from each other, and the phases of the fourth, fifth and sixth linear Hall sensors are 2π / 3 different from each other.

[0031] If Figure 3 As shown in the figure, after the voltage signals output by the six linear Hall sensors are converted into digital form, the digital signals obtained are: in, V ACFD1 is a digital signal obtained by analog-to-digital conversion of the output voltage signal of the first linear Hall sensor 1, V ACFD2 is a digital signal obtained by analog-to-digital conversion of the output voltage signal of the second linear Hall sensor 2, V ACFD3 is a digital signal after the output voltage signal of the third linear Hall sensor 3 is converted into a digital signal. V ACFD4 is a digital signal after the output voltage signal of the fourth linear Hall sensor 4 is converted into a digital signal. V ACFD5 is a digital signal after the output voltage signal of the fifth linear Hall sensor 5 is converted into a digital signal. V ACFD6 is a digital signal after the output voltage signal of the sixth linear Hall sensor 6 is converted into a digital signal, B 1i , B 2i , B 3i , B 4i , B 15i , B 6iIt represents the amplitude of each harmonic of the output voltage signal of the first, second, third, fourth, fifth and sixth linear Hall sensors after analog-to-digital conversion. f 1 represents the electrical angle value of the first linear Hall sensor 1 relative to the initial position of the motor, f 2 represents the electrical angle value of the fourth linear Hall sensor 4 relative to the initial position of the motor, i is the actual electrical angle of the rotor.

[0032] It should be noted that, after reasonable installation, the electrical angle difference between the first linear Hall sensor 1 and the fourth linear Hall sensor 4 is e ( i 1 )= f 2- f 1= 2kπ±π / 6,k =0,1,2,… i It is the actual electrical angle of the rotor, thereby ensuring that the two-phase signals after grouping and superposition are orthogonal signals.

[0033] After the analog signal is converted into a digital signal through analog-to-digital conversion, the digital signal is subjected to "group signal superposition" and "linear combination" to obtain a pair of orthogonal signals in a two-phase stationary coordinate system. The orthogonal signal is a superposition of the third harmonic signal for subsequent closed-loop control of the pair of orthogonal signals.

[0034] Specifically, based on the group superposition model, the six voltage signals after analog-to-digital conversion are V ACFD1 , V ACFD2 , V ACFD3 、V ACFD4 , V ACFD5 , V ACFD6 Perform group signal superposition to obtain a two-phase third harmonic sinusoidal signal; Among them, the group superposition model is: ; Among them, the electrical angle of the phase difference between the first linear Hall and the fourth linear Hall is e(θ 1 ) ; V FD-3α , V FD-3β is a sinusoidal signal of the third harmonic with a difference of ε(3θ1) electrical angle between them. V ACFD1 , V ACFD2 , V ACFD3 ,V ACFD4 , V ACFD5 , V ACFD6 are the output signals of the first, second, third, fourth, fifth and sixth linear Hall sensors, U m Represents the amplitude of the third harmonic of the Hall signal output, and θ is the actual electrical angle of the rotor.

[0035] The two-phase third harmonic sinusoidal signals are processed based on linear combination to obtain orthogonal signals.

[0036] Step 3, estimating the rotor angle value and the rotation speed value from a pair of orthogonal signals obtained in step 2 based on the synchronous reference frame phase-locked loop.

[0037] Specifically, Figure 3 As shown, the synchronous reference frame phase-locked loop 16 includes: a phase detector 13, a loop filter 14 and a voltage-controlled oscillator 15; wherein the loop filter 14 adopts a traditional PI controller, and in order to meet the fast performance of the system, the proportional coefficient Kp=100 and the integral coefficient Ki=5000. The voltage-controlled oscillator 15 adopts an integral module.

[0038] The input terminal of the phase detector 13 is connected to the two-phase stationary coordinate system obtained by the linear combination model. and The output terminal is used to determine the rotor angle value according to the feedback of the voltage controlled oscillator 15. right and Perform 2s / 2r transformation and output the two-phase rotating coordinate system U d and U q , as shown in the following formula:

[0039] U d It is the d-axis direction component in the two-phase rotating coordinate system, and the d-axis direction is consistent with the rotor direct axis direction; U q It is the q-axis direction component in the two-phase rotating coordinate system and is the output signal of the phase detector. The q-axis direction is consistent with the rotor quadrature axis direction and leads the d-axis direction by 90° electrical angle; S is the 2s / 2r transformation, U m yes and A pair of amplitudes, is the output signal of the voltage-controlled oscillator and is the estimated electrical angle of the rotor, and θ is the actual electrical angle of the rotor.

[0040] The input end of the loop filter 14 is connected to the output end of the phase detector 13, and the q-axis voltage in the two-phase rotating coordinate system is U q Perform PI regulation and output rotor speed value The input end of the voltage controlled oscillator 15 is connected to the output end of the loop filter 14, and the output rotor speed value Output the rotor angle value after integration processing .

[0041] comprehensive Figure 3 The following conclusions can be drawn from the above formula: 1) U q It is adjusted to 0 by the negative feedback system, that is, Converging to 0 means that the estimated angle value follows the actual angle value; 2) When When it is close to 0, It is a linear expression, that is ; 3) When Near 0 o'clock, Close to 1, we get U q ≈U m , U d That is, it indicates the amplitude of the three-phase Hall sensor signal; It should be noted that, in a specific implementation, analog-to-digital conversion, group signal superposition, linear combination, and synchronous reference frame phase-locked loop 16 can be integrated into the same digital signal processor 10 for implementation.

[0042] Example 2 This embodiment is verified by taking a three-phase 24-slot, 16-pole axial flux permanent magnet motor as an example. Figure 4 and 5 As shown, the stator 11 of the axial flux permanent magnet motor includes 24 slots, and the slot 7 has a width of 4 mm, which can accommodate the linear Hall sensor packaged in DRV5055. When k=4, according to M= ks / 6p Available, M=24*4 / 6*16=1 .

[0043] The first linear Hall sensor 1 is installed in any slot 7 of the stator 11. In the same direction, the second linear Hall sensor 2 is 1 slot 7 away from the first linear Hall sensor 1, the third linear Hall sensor 3 is 1 slot 7 away from the second linear Hall sensor 2, and the first, second and third linear Hall sensors are installed at 42mm on the same cut surface of the slot 7; the fourth linear Hall sensor 4 is 3 slots 7 away from the first linear Hall sensor 1, the fifth linear Hall sensor 5 is 1 slot 7 away from the fourth linear Hall 4, the sixth linear Hall sensor 6 is 1 slot 7 away from the fifth linear Hall 5, and the fourth, fifth and sixth linear Hall sensors are installed at 51.67mm on the same cut surface of the slot 7.

[0044] Figure 6 The axial magnetic field of six linear Hall detection points when the set speed is 300r / min is given. Figure 7 It is the waveform diagram of a pair of orthogonal signals obtained after group superposition and linear combination. Figure 8 is the estimated value of the rotor angle obtained by solution.

[0045] It can be seen that the present invention realizes high-precision angle detection and meets the requirements for angle and speed measurement of a high-performance permanent magnet motor with a permanent magnet oblique pole and axial flux.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present invention, which should be included in the scope of the technical solution for protection of the present invention.

Claims

1. A method for detecting the rotor position angle of a skewed-pole axial flux permanent magnet motor, wherein the skewed-pole axial flux permanent magnet motor comprises a permanent magnet with skewed poles, an annular winding, a stator tooth and a rotor, wherein: Permanent magnets with oblique poles are evenly installed on the rotor along the circumferential direction, and the magnetization directions of two adjacent permanent magnets are opposite; a stator slot is formed between any two stator teeth, and a same-phase annular winding is arranged in the stator slot; the characteristics are: Step 1, a first linear Hall sensor, a second linear Hall sensor, a third linear Hall sensor, a fourth linear Hall sensor, a fifth linear Hall sensor and a sixth linear Hall sensor are arranged at equal intervals in the stator slot of the stator along the circumferential direction; the magnetic sensitive surface of any linear Hall sensor is opposite to the salient pole structure surface of the mover; The radius of the first linear Hall sensor, the second linear Hall sensor, and the third linear Hall sensor relative to the center of the axis is a first radius; the radius of the fourth linear Hall sensor, the fifth linear Hall sensor, and the sixth linear Hall sensor relative to the center of the axis is a second radius; wherein the first radius is not equal to the second radius; Step 2, after performing analog-to-digital conversion on the voltage signals output by the six linear Hall sensors, a pair of orthogonal signals are obtained through preprocessing of grouped signal superposition and linear combination; Step 3, estimating the rotor angle value and the rotation speed value from a pair of orthogonal signals obtained in step 2 based on the synchronous reference frame phase-locked loop.

2. The method for detecting the rotor position angle of a skew-pole axial flux permanent magnet motor according to claim 1, characterized in that: The first linear Hall sensor is installed in any stator slot, the second linear Hall sensor is installed in the stator slot M-th away from the first linear Hall sensor along a preset direction, the third linear Hall sensor is installed in the stator slot M-th away from the second linear Hall sensor along a preset direction; the fourth linear Hall sensor is installed in the stator slot M-th away from the third linear Hall sensor along a preset direction, the fifth linear Hall sensor is installed in the stator slot M-th away from the fourth linear Hall sensor along a preset direction, and the sixth linear Hall sensor is installed in the stator slot M-th away from the fifth linear Hall sensor along a preset direction; M= ks / 6p ,in, k is an integer and k≠3n,n=1,2,... , s is the number of slots in the stator, p is the number of motor pole pairs.

3. The method for detecting the rotor position angle of a skew-pole axial flux permanent magnet motor according to claim 1, characterized in that: After analog-to-digital conversion of the voltage signals output by the six linear Hall sensors, we get: in, V ACFD1 is a digital signal obtained by analog-to-digital conversion of the output voltage signal of the first linear Hall sensor, V ACFD2 is a digital signal obtained by analog-to-digital conversion of the output voltage signal of the second linear Hall sensor, V ACFD3 is a digital signal after the output voltage signal of the third linear Hall sensor is converted into a digital signal. V ACFD4 is a digital signal obtained by analog-to-digital conversion of the output voltage signal of the fourth linear Hall sensor, V ACFD5 is a digital signal obtained by analog-to-digital conversion of the output voltage signal of the fifth linear Hall sensor, V ACFD6 is a digital signal obtained by analog-to-digital conversion of the output voltage signal of the sixth linear Hall sensor, B 1i , B 2i , B 3i , B 4i , B 15i , B 6i It represents the amplitude of each harmonic of the output voltage signal of the first, second, third, fourth, fifth and sixth linear Hall sensors after analog-to-digital conversion. φ 1 represents the electrical angle value of the first linear Hall sensor relative to the initial position of the motor, φ 2 represents the electrical angle value of the fourth linear Hall sensor relative to the initial position of the motor. The electrical angle difference between the first linear Hall and the fourth linear Hall is ε ( θ 1 )= φ 2- φ 1= 2kπ±π / 6, k =0,1,2,…, θ is the actual electrical angle of the rotor.

4. A method for detecting the rotor position angle of a skew-pole axial flux permanent magnet motor according to claim 3, characterized in that: The six voltage signals after analog-to-digital conversion are preprocessed by grouping signal superposition and linear combination, including the following steps: Based on the group superposition model, the six voltage signals after analog-to-digital conversion are V ACFD1 、V ACFD2 、V ACFD3 、V ACFD4 、V ACFD5 、 V ACFD6 Perform group signal superposition to obtain a two-phase third harmonic sinusoidal signal; Among them, the group superposition model is: ； Among them, the electrical angle of the phase difference between the first linear Hall and the fourth linear Hall is ε ( θ 1 ); V FD-3α , V FD-3β The difference between the two ε ( 3θ 1 ) is a sinusoidal signal of the third harmonic of the electrical angle, V ACFD1 、V ACFD2 、V ACFD3 、V ACFD4 、V ACFD5 、V ACFD6 are the output signals of the first, second, third, fourth, fifth and sixth linear Hall sensors, U m Represents the amplitude of the third harmonic of the Hall signal output, θ is the actual electrical angle of the rotor; The two-phase third harmonic sinusoidal signals are processed based on linear combination to obtain a pair of orthogonal signals.

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