A method for detecting the position angle of a rotor of a skew-pole axial flux permanent magnet motor

Abstract

The application provides a rotor position angle detection method of a skew-pole axial flux permanent magnet motor, the skew-pole axial flux permanent magnet motor comprising a permanent magnet with skew poles, a ring winding, a stator tooth and a rotor, wherein a stator slot is formed between any two stator teeth, and a same-phase ring winding is arranged in the stator slot; the method further comprises two groups of linear Hall sensors which are arranged at equal intervals in the stator slot of the stator in the circumferential direction, wherein the radius of one group of linear Hall sensors relative to the center of the shaft is a first radius; the radius of the other group of linear Hall sensors relative to the center of the shaft is a second radius; the first radius is not equal to the second radius; after the voltage signals output by the two groups of linear Hall sensors are subjected to analog-digital conversion, the voltage signals are subjected to preprocessing of grouping signal superposition and linear combination to obtain a pair of orthogonal signals; and the rotor angle value and the speed value are estimated based on the pair of orthogonal signals in a synchronous reference frame phase-locked loop.

Description

Technical Field

[0001] This invention relates to a rotor angle detection technology for a skewed-pole axial flux permanent magnet motor, specifically, to a method for detecting the rotor position angle of a skewed-pole axial flux permanent magnet motor. Background Technology

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

[0003] Vector control of traditional AC axial flux motors requires precise rotor angle and rotational speed. Linear Hall effect sensors, with their advantages of small size and high sensitivity, are often installed inside compact devices such as pan-tilt units and oil pump motors to estimate rotor position by detecting the leakage magnetic field of the permanent magnets inside the motor.

[0004] For example, CN117674662A first determines the linear Hall sensor installation scheme: installing one set of three Hall sensors or two sets of six linear Hall sensors; then, pre-harmonic suppression processing is performed on the raw output signal of the Hall sensors to obtain a set of high sinusoidal orthogonal signals; finally, the motor rotor angle is calculated based on the pre-processed orthogonal signals, achieving high compactness and high-precision angle detection, meeting the angle and speed measurement requirements of axial flux motors. However, due to the use of a pre-filter, this electromagnetic radiation system has a large angle estimation error in the low-speed region, resulting in weak dynamic response performance.

[0005] The skewed-pole permanent magnet synchronous motor (SMR) is a novel type of permanent magnet motor that uses permanent magnets as its rotor, effectively reducing cogging torque and torque ripple. However, because the magnetic field of the skewed-pole SMR is generated by permanent magnets, it is more susceptible to external magnetic fields, temperature changes, and wear than traditional motors, leading to magnetic field instability. This presents a new challenge for accurate rotor position detection. Traditional rotor position detection methods, such as those based on Hall sensors or incremental encoders, are typically placed at specific locations on the motor. However, due to the complexity of the skewed-pole design, achieving high-precision rotor position detection across the entire operating range is difficult.

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

[0007] The purpose of this invention is to address the shortcomings of existing technologies by providing 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 cross-sections of the stator slots, changes in the magnetic field can be captured in real time, enabling precise measurement of the rotor position angle. This method effectively improves the accuracy of rotor position angle detection, especially in skewed-pole axial flux permanent magnet motors, significantly enhancing the motor's operating performance and control precision.

[0008] To achieve the above objectives, 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 includes a permanent magnet with skewed poles, an annular winding, stator teeth, and a rotor, wherein the permanent magnet with skewed poles is uniformly mounted on the rotor circumferentially, and the magnetization directions of two adjacent permanent magnets are opposite; a stator slot is formed between any two stator teeth, and an annular winding of the same phase is provided in the stator slot;

[0009] The stator includes 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 equally spaced along the circumferential direction within the stator slots of the stator; the magnetic sensitive surface of any linear Hall sensor is opposite to the salient pole structure surface of the mover.

[0010] Wherein, the radii of the first linear Hall sensor, the second linear Hall sensor, and the third linear Hall sensor relative to the axis center are the first radius; the radii of the fourth linear Hall sensor, the fifth linear Hall sensor, and the sixth linear Hall sensor relative to the axis center are the second radius; wherein, the first radius is not equal to the second radius;

[0011] After the voltage signals output by the six linear Hall sensors are converted from analog to digital, they are then preprocessed by grouping signal superposition and linear combination to obtain a pair of orthogonal signals.

[0012] Step 3: Estimate the rotor angle and rotational speed from a pair of orthogonal signals obtained in Step 2 based on the synchronous reference system phase-locked loop.

[0013] Preferably, the first linear Hall sensor is installed in any one of the stator slots; the second linear Hall sensor is installed in the stator slot M times away from the first linear Hall sensor along a preset direction; the third linear Hall sensor is installed in the stator slot M times away from the second linear Hall sensor along a preset direction; the fourth linear Hall sensor is installed in the stator slot M times away from the third linear Hall sensor along a preset direction; the fifth linear Hall sensor is installed in the stator slot M times away from the fourth linear Hall sensor along a preset direction; and the sixth linear Hall sensor is installed in the stator slot M times away from the fifth linear Hall sensor along a preset direction.

[0014] M= ks / 6p ,in, k Integer and k≠3n,n=1,2,... , s The number of slots in the stator. p This represents the number of pole pairs of the motor.

[0015] Preferably, after performing analog-to-digital conversion on the voltage signals output by the six linear Hall sensors, the following is obtained:

[0016]

[0017] in, V ACFD1 The digital signal is the output voltage signal of the first linear Hall sensor after analog-to-digital conversion. V ACFD2 The digital signal is the output voltage signal of the second linear Hall sensor after analog-to-digital conversion. V ACFD3 The digital signal is the output voltage signal of the third linear Hall sensor after analog-to-digital conversion. V ACFD4 The output voltage signal of the fourth linear Hall sensor is converted into a digital signal by analog-to-digital conversion. V ACFD5 The digital signal is the output voltage signal of the fifth linear Hall sensor after analog-to-digital conversion. V ACFD6 The digital signal is the output voltage signal of the sixth linear Hall sensor after analog-to-digital conversion. B 1i , B 2i , B 3i , B 4i , B 15i , B 6i This represents the amplitude of each harmonic of the digital signal array formed by the analog-to-digital conversion of the output voltage signals of the first, second, third, fourth, fifth, and sixth linear Hall sensors. 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, and the electrical angle difference between the first and fourth linear Hall sensors is [value missing]. e ( i 1 )= f 2- f 1= 2kπ±π / 6,k =0,1,2,…, i It is the actual electrical angle of the rotor.

[0018] Preferably, the preprocessing of grouping and superimposing the six voltage signals after analog-to-digital conversion and linearly combining them includes the following steps:

[0019] Based on the grouping and superposition model, the six voltage signals after analog-to-digital conversion are analyzed. V ACFD1 、V ACFD2 、V ACFD3 、V ACFD4 、 V ACFD5 、V ACFD6 By superimposing the grouped signals, a sinusoidal signal of the third harmonic of two phases is obtained;

[0020] The group overlay model is as follows:

[0021] ;

[0022] The electrical angle between the phase difference between the first linear Hall and the fourth linear Hall is . e ( i 1 ); V FD-3α , V FD-3β For two mutual differences e (3 i 1 The sinusoidal signal of the third harmonic of the electrical angle. V ACFD1 、V ACFD2 、V ACFD3 、V ACFD4 、V ACFD5 、V ACFD6 The output signals of the first, second, third, fourth, fifth, and sixth linear Hall sensors. U m The amplitude of the third harmonic of the Hall signal output is represented. i The actual electrical angle of the rotor; based on linear combination, the sinusoidal signals of the two-phase third harmonics are processed to obtain a pair of orthogonal signals.

[0023] This invention has outstanding substantive features and significant progress compared to the prior art. Specifically,

[0024] (1) This technology can directly provide two-phase orthogonal third harmonic signals from the six-phase Hall signal without the need for Clark transformation and filtering.

[0025] (2) This technology reduces the dynamic response time of the decoding algorithm, especially in slanted pole axial flux permanent magnet motors, which can significantly improve the motor's operating performance and control accuracy. Attached Figure Description

[0026] Figure 1 This is a flowchart of the rotor position angle detection method for a slanted-pole axial flux permanent magnet motor proposed in Embodiment 1 of the present invention.

[0027] Figure 2 This is a module connection diagram of the rotor position angle detection method for the slanted pole axial flux permanent magnet motor proposed in Embodiment 1 of the present invention.

[0028] Figure 3 This is a block diagram of the synchronous reference system phase-locked loop involved in Embodiment 1 of the present invention.

[0029] Figure 4 This is a schematic diagram of the axial flux permanent magnet motor with skewed permanent magnet poles in Embodiment 2 of the present invention.

[0030] Figure 5 This is a schematic diagram of the permanent magnet on the rotor disk of the axial flux permanent magnet motor in Embodiment 2 of the present invention.

[0031] Figure 6 This is a diagram showing the axial magnetic field distribution of the six linear Hall detection points in Embodiment 2 of the present invention.

[0032] Figure 7 This is a waveform diagram of the signal after superposition and linear combination of grouped signals in Embodiment 2 of the present invention.

[0033] Figure 8 This is a waveform diagram of the angle signal obtained by solving in Embodiment 2 of the present invention.

[0034] In the diagram: 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 tooth; 12. In-phase toroidal winding; 13. Phase detector; 14. Loop filter; 15. Voltage-controlled oscillator; 16. Synchronous reference system phase-locked loop. Detailed Implementation

[0035] The technical solution of the present invention will be further described in detail below through specific embodiments.

[0036] Example 1

[0037] This embodiment provides a method for detecting the rotor position angle of a skew-pole axial flux permanent magnet motor, such as... Figure 1-3As shown, the skewed-pole axial flux permanent magnet motor includes a permanent magnet 9 with skewed poles, an annular winding 12, stator teeth 11 and a rotor 8. The permanent magnet 9 with skewed poles is uniformly mounted on the rotor 8 in 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 an annular winding 12 of the same phase is provided in the stator slot 7.

[0038] Furthermore, the method for detecting the rotor position angle of the skewed-pole axial flux permanent magnet motor includes the following steps:

[0039] 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 along the circumferential direction in the stator slot 7 of the stator; the magnetic sensitive surface of any linear Hall sensor is opposite to the salient pole structure surface of the mover.

[0040] Wherein, the radii 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 are the first radius; the radii 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 are the second radius; wherein, the first radius is not equal to the second radius. Due to the presence of the skew poles of the permanent magnet, at different radii of different slots, 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 φ1 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.

[0041] Specifically, both the first and second radii are larger than the stator inner diameter and smaller than the rotor outer diameter to ensure that the magnetic sensitive surfaces of the first to sixth linear Hall sensors are opposite to the slot openings.

[0042] In one embodiment, assuming counterclockwise is the positive direction, when the rotor rotates at a constant speed in the forward direction, the magnetization of the permanent magnet causes the air gap magnetic flux density near the stator slot 7 to exhibit a near-sinusoidal waveform distribution. Therefore, a linear Hall sensor can be installed to detect the air gap magnetic flux.

[0043] Specifically, the first linear Hall sensor 1 is installed in any one of the stator slots 7; the second linear Hall sensor 2 is installed in the stator slot 7 located M times 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 located M times 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 located M times 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 located M times 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 located M times away from the fifth linear Hall sensor 5 along a preset direction.

[0044] M= ks / 6p ,in, k Integer and k≠3n,n=1,2,... , s The number of slots in the stator. p This represents the number of pole pairs of the motor.

[0045] Step 2: After performing analog-to-digital conversion on the voltage signals output by the six linear Hall sensors, the signals are then preprocessed by grouping signal superposition and linear combination to obtain a pair of orthogonal signals.

[0046] 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 to a digital signal via analog-to-digital conversion. Assuming counterclockwise is considered positive, 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°, while the phase difference between the first, second, and third linear Hall sensors is 2π / 3, and the phase difference between the fourth, fifth, and sixth linear Hall sensors is 2π / 3.

[0047] Then as Figure 3 As shown, after performing analog-to-digital conversion on the voltage signals output by the six linear Hall sensors, the resulting digital signal is:

[0048]

[0049] in, V ACFD1 The digital signal is the output voltage signal of the first linear Hall sensor 1 after analog-to-digital conversion. V ACFD2 The digital signal is the output voltage signal of the second linear Hall sensor 2 after analog-to-digital conversion. V ACFD3 The digital signal is the output voltage signal of the third linear Hall sensor 3 after analog-to-digital conversion. VACFD4 The output voltage signal of the fourth linear Hall sensor 4 is converted into a digital signal by analog-to-digital conversion. V ACFD5 The digital signal is the output voltage signal of the fifth linear Hall sensor 5 after analog-to-digital conversion. V ACFD6 The digital signal is the output voltage signal of the sixth linear Hall sensor 6 after analog-to-digital conversion. B 1i , B 2i , B 3i , B 4i , B 15i , B 6i This represents the amplitude of each harmonic of the digital signal array formed by the analog-to-digital conversion of the output voltage signals of the first, second, third, fourth, fifth, and sixth linear Hall sensors. 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 It is the actual electrical angle of the rotor.

[0050] It should be noted that, with proper installation, the electrical angle difference between the first linear Hall sensor 1 and the fourth linear Hall sensor 4 is [value missing]. e ( i 1 )= f 2- f 1= 2kπ±π / 6,k =0,1,2,… i It is the actual electrical angle of the rotor, thus ensuring that the two-phase signals after grouping and superposition are orthogonal signals.

[0051] After the analog signal is converted into a digital signal, 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 signals are the superposition of the third harmonic signals, which are used for subsequent closed-loop control of the pair of orthogonal signals.

[0052] Specifically, based on the grouped superposition model, the six voltage signals after analog-to-digital conversion are... V ACFD1 , V ACFD2 , V ACFD3 V ACFD4 , V ACFD5 , V ACFD6By superimposing the grouped signals, a sinusoidal signal of the third harmonic of two phases is obtained;

[0053] The group overlay model is as follows:

[0054] ;

[0055] The electrical angle between the phase difference between the first linear Hall and the fourth linear Hall is . e(θ 1 ) ; V FD-3α , V FD-3β The sinusoidal signals are the third harmonics of two electrical angles that differ from each other by ε(3θ1). V ACFD1 , V ACFD2 , V ACFD3 , V ACFD4 , V ACFD5 , V ACFD6 The output signals of the first, second, third, fourth, fifth, and sixth linear Hall sensors. U m The amplitude of the third harmonic of the Hall signal output is represented by θ, where θ is the actual electrical angle of the rotor.

[0056] The sinusoidal signals of two-phase third harmonics are processed by linear combination to obtain orthogonal signals.

[0057] Step 3: Estimate the rotor angle and rotational speed from a pair of orthogonal signals obtained in Step 2 based on the synchronous reference system phase-locked loop.

[0058] Specifically, such as Figure 3 As shown, the synchronous reference system phase-locked loop 16 includes a phase detector 13, a loop filter 14, and a voltage-controlled oscillator 15. The loop filter 14 uses a conventional PI controller, with a proportional gain Kp = 100 and an integral gain Ki = 5000 to meet the system's fast performance requirements. The voltage-controlled oscillator 15 uses an integral module.

[0059] The input terminal of phase detector 13 is connected to the two-phase stationary coordinate system obtained through the linear combination model. and The output terminal is used to calculate the rotor angle value fed back by the voltage-controlled oscillator 15. right and Perform a 2s / 2r transformation to output the coordinates in the two-phase rotating coordinate system. U d and Uq The specific formula is as follows:

[0060]

[0061] U d It is the d-axis component in a two-phase rotating coordinate system, and the d-axis direction is consistent with the rotor direct axis direction; U q It represents the q-axis component in a two-phase rotating coordinate system and is the output signal of the phase detector. The q-axis direction is consistent with the rotor's quadrature axis direction and leads the d-axis direction by an electrical angle of 90°; S is a 2s / 2r transformation. U m yes and A pair of amplitudes, It is the output signal of the voltage-controlled oscillator and the estimated electrical angle of the rotor, where θ is the actual electrical angle of the rotor.

[0062] The input terminal of loop filter 14 is connected to the output terminal of phase detector 13 to measure the q-axis voltage in a two-phase rotating coordinate system. U q Perform PI regulation to output rotor speed value The input terminal of the voltage-controlled oscillator 15 is connected to the output terminal of the loop filter 14 to output the rotor speed value. After integration, the rotor angle value is output. .

[0063] comprehensive Figure 3 The above equation leads to the following conclusion:

[0064] 1) U q Adjusted to 0 by the negative feedback system, i.e. Converging to 0 indicates that the estimated angle value follows the actual angle value.

[0065] 2) When When it is close to 0, It exhibits a linear behavior, that is ;

[0066] 3) When When approaching 0, Approaching 1, we arrive at U q ≈U m , U d This indicates the amplitude of the three-phase Hall sensor signal;

[0067] It should be noted that, in practice, analog-to-digital conversion, group signal superposition, linear combination, and synchronous reference system phase-locked loop 16 can be integrated into the same digital signal processor 10.

[0068] Example 2

[0069] This embodiment uses a three-phase, 24-slot, 16-pole axial flux permanent magnet motor as an example for verification. Figure 4 and 5 As shown, the stator 11 of the axial flux permanent magnet motor contains 24 slots, with slot 7 having a width of 4mm, which can accommodate a linear Hall sensor in a DRV5055 package. When k=4, according to M= ks / 6p We can obtain, M=24*4 / 6*16=1 .

[0070] The first linear Hall sensor 1 is installed in any slot 7 of the stator 11 along a uniform direction. The second linear Hall sensor 2 is one slot 7 away from the first linear Hall sensor 1, and the third linear Hall sensor 3 is one slot 7 away from the second linear Hall sensor 2. The first, second, and third linear Hall sensors are installed at a position of 42mm on the same cut surface of the slot 7. The fourth linear Hall sensor 4 is three slots 7 away from the first linear Hall sensor 1, the fifth linear Hall sensor 5 is one slot 7 away from the fourth linear Hall sensor 4, and the sixth linear Hall sensor 6 is one slot 7 away from the fifth linear Hall sensor 5. The fourth, fifth, and sixth linear Hall sensors are installed at a position of 51.67mm on the same cut surface of the slot 7.

[0071] Figure 6 The axial magnetic field at six linear Hall effect detection points is given when the rotational speed is set to 300 r / min. Figure 7 The waveforms are of a pair of orthogonal signals obtained after group superposition and linear combination. Figure 8 This is the estimated value of the rotor angle obtained from the calculation.

[0072] As can be seen, this invention achieves high-precision angle detection, meeting the angle and speed measurement requirements of high-performance permanent magnet motors with permanent magnet inclined poles and axial flux.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A method for detecting rotor position angle of a skewed pole axial flux permanent magnet motor, the skewed pole axial flux permanent magnet motor comprising a permanent magnet with skewed poles, a ring winding, stator teeth and a rotor, wherein, The permanent magnets with inclined poles are evenly installed on the rotor in the circumferential direction, the magnetization directions of two adjacent permanent magnets are opposite; any two stator teeth form a stator slot, and a same-phase annular winding is arranged in the stator slot; characterized in that: Step 1, first, second, third, fourth, fifth and sixth linear Hall sensors are arranged in the stator slots of the stator in the circumferential direction at equal intervals; the magnetic sensitive surface of any linear Hall sensor is opposite to the surface of the convex pole structure of the mover; Wherein, the radius of the first, second and third linear Hall sensors relative to the axis center is the first radius; the radius of the fourth, fifth and sixth linear Hall sensors relative to the axis center is the second radius; wherein, the first radius is not equal to the second radius; Step 2, after the voltage signals output by the six linear Hall sensors are analog-digital converted, a pair of orthogonal signals are obtained through the preprocessing of grouping signal superposition and linear combination; Step 3, based on the synchronous reference frame phase-locked loop, the rotor angle value and the speed value are estimated from the pair of orthogonal signals obtained in step 2.

2. The method 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 which is the Mth stator slot away from the first linear Hall sensor in the preset direction, the third linear Hall sensor is installed in the stator slot which is the Mth stator slot away from the second linear Hall sensor in the preset direction; the fourth linear Hall sensor is installed in the stator slot which is the Mth stator slot away from the third linear Hall sensor in the preset direction, the fifth linear Hall sensor is installed in the stator slot which is the Mth stator slot away from the fourth linear Hall sensor in the preset direction, and the sixth linear Hall sensor is installed in the stator slot which is the Mth stator slot away from the fifth linear Hall sensor in the preset direction; M= ks / 6p wherein, k is an integer and k≠3n, n=1,2,... , s is the number of notches of the stator, p is the number of motor pole pairs.

3. The method according to claim 1, characterized in that: After the voltage signals output by the six linear Hall sensors are analog-digital converted, the following are obtained: wherein, V ACFD1 is a digital signal of the output voltage signal of the first linear Hall sensor after analog-digital conversion, V ACFD2 is a digital signal of the output voltage signal of the second linear Hall sensor after analog-digital conversion, V ACFD3 is a digital signal of the output voltage signal of the third linear Hall sensor after analog-digital conversion, V ACFD4 is a digital signal of the output voltage signal of the fourth linear Hall sensor after analog-digital conversion, V ACFD5 is a digital signal of the output voltage signal of the fifth linear Hall sensor after analog-digital conversion, V ACFD6 is a digital signal of the output voltage signal of the sixth linear Hall sensor after analog-digital conversion, B 1i , B 2i , B 3i , B 4i , B 15i , B 6i denotes the amplitude of the m-th harmonic of the digital signal of the output voltage signal of the first, second, third, fourth, fifth, sixth linear Hall sensor after analog-digital conversion, φ 1denotes the electrical angle value of the first linear Hall sensor relative to the initial position of the electric machine, φ 2denotes the electrical angle value of the fourth linear Hall sensor relative to the initial position of the electric machine, 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. The method according to claim 3, characterized in that, After the six voltage signals are analog-digital converted, the preprocessing of grouping signal superposition and linear combination is carried out, including the following steps: Based on the packet superposition model to six voltage signals after analog-digital conversion V ACFD1 、V ACFD2 、V ACFD3 、V ACFD4 、V ACFD5 、 V ACFD6 The packet signal superposition is carried out, and a two-phase third harmonic sine signal is obtained. Wherein, the grouping superposition model is: ； The first linear Hall and the fourth linear Hall are phase-difference electric angles of ε θ 1 V FD-3α V FD-3β The third harmonic of the sine signal of the two-phase difference ε 3θ 1 V ACFD1 、V ACFD2 、V ACFD3 、V ACFD4 、V ACFD5 、V ACFD6 The first, second, third, fourth, fifth, and sixth linear Hall sensors are output signals U m The amplitude of the third harmonic of the Hall signal output θ The actual electric angle of the rotor​​​​​ Based on the linear combination, the sinusoidal signals of two-phase third harmonics are processed to obtain a pair of orthogonal signals.

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