A permanent magnet fault-tolerant hub motor based on active position sensorless strategy and its drive and design method

Abstract

The present invention discloses a permanent magnet fault-tolerant hub motor based on an active position sensorless strategy and a drive and design method thereof. In the motor design stage, the present invention considers the position-free operation performance in advance and proposes a permanent magnet fault-tolerant hub motor based on an active position sensorless strategy. By adopting fractional slot concentrated windings and cleverly utilizing alternating poles, multi-layer magnetic barriers and auxiliary permanent magnets, the position-free operation accuracy of the motor is improved while ensuring the fault tolerance of the motor. At the control level, a secondary harmonic suppression strategy based on frequency band adaptation is proposed to suppress the influence of secondary salient pole harmonics on position observation, while improving the dynamic response performance of the system. The present invention breaks through the technical constraints of the traditional hub motor position sensorless drive system, and comprehensively improves the position sensorless operation capability of the motor drive system under multiple working conditions by designing a five-phase permanent magnet fault-tolerant hub motor based on an active position sensorless strategy and combining it with a high-precision position sensorless control algorithm.

Description

Technical Field

[0001] The present invention relates to the technical field of motors and intelligent control thereof, and in particular to a permanent magnet fault-tolerant hub motor based on an active position sensorless strategy and a driving and design method thereof. Background Art

[0002] Climate change is one of the most serious challenges facing the world today, and controlling greenhouse gas emissions, primarily carbon dioxide, is urgent. New energy electric vehicles, due to their low pollution levels, have become a key tool for energy conservation and emission reduction. Permanent magnet in-wheel motors, with their high output torque, high efficiency, and compact size, have garnered widespread attention in the new energy vehicle sector.

[0003] The new generation of new energy electric vehicles places higher demands on the safety and reliability of their motor drive systems. Permanent magnet fault-tolerant hub motors can overcome power switch failures, open circuit failures, and short circuit failures, have good fault tolerance, and effectively improve the reliability of hub motors. The Chinese invention patent "An electrothermal magnetic isolation multi-phase fault-tolerant motor" (patent number CN112510862A) discloses an electrothermal magnetic isolation multi-phase fault-tolerant motor, which uses multi-phase concentrated winding technology and a new stator structure to achieve strong fault-tolerant operation of the motor under fault conditions. However, due to the use of concentrated windings, this type of fault-tolerant motor often has a relatively low salient pole rate, resulting in a narrow motor speed regulation range and poor operation without position sensors, which cannot meet the requirements of electric vehicles for their drive motors. To overcome the problem of low motor saliency, the Chinese invention patent "Design Method of a Five-Phase Permanent Magnet Fault-Tolerant Motor with High Reluctance Torque and High Salient Ratio" (Patent No. CN111654124B) proposes an improved slot-pole matching relationship for a five-phase permanent magnet fault-tolerant motor. This achieves high reluctance torque and high saliency while ensuring superior fault tolerance, which is of great significance for achieving good fault tolerance and steady-state sensorless operation. However, due to the saliency ratio being greater than 1, this type of permanent magnet fault-tolerant motor has a high risk of irreversible demagnetization of the permanent magnets under high-speed field weakening. Furthermore, the saliency characteristics of this type of motor easily disappear with load changes, thereby deteriorating the dynamic performance of sensorless operation. To this end, the document "Design and Analysis of New Five-Phase Flux-Intensifying Fault-Tolerant Interior Permanent Magnet Motor for Sensorless Operation" (IEEE Transactions on Industrial Electronics, 2020) attempts to propose a magnetic field-enhanced permanent magnet motor to improve the motor's sensorless operation capability. However, the reverse saliency of this type of motor is not significant, and the secondary saliency problem has not been overcome. The accuracy of rotor position estimation in both dynamic and steady states still needs to be further improved. Therefore, to meet the requirements of the new generation of electric vehicles for excellent multi-condition sensorless operation, it is particularly important to improve the in-wheel motor's positionless operation capability, demagnetization resistance, and speed regulation range while maintaining its basic electromagnetic performance. Summary of the Invention

[0004] Purpose of the Invention: This invention addresses the challenges of the prior art by proposing a fault-tolerant permanent magnet in-wheel motor based on an active sensorless strategy, as well as its drive and design methods. This design incorporates positionless operation capability into the design phase, comprehensively considering the impact of motor parameters on sensorless operation to meet the diverse operating conditions of electric vehicles, including frequent starting and stopping, acceleration and deceleration, heavy-load climbing, high-speed cruising, and fault conditions. While maintaining strong fault tolerance and wide speed regulation, the motor exhibits superior positionless operation capabilities, further broadening the wide-area high-efficiency range of electric vehicle motor drive systems and improving safe and reliable operation.

[0005] Technical solution: To achieve the above-mentioned invention purpose, the present invention provides a permanent magnet fault-tolerant hub motor drive system based on an active position sensorless strategy. The system comprises: a five-phase permanent magnet fault-tolerant hub motor (1), a Park transformation module (2), a position sensorless control module (3), an MTPA control module (4), a PI controller (5), an inverse Park transformation module (6), an SVPWM module (7) and an inverter module (8). The system specifically comprises the following steps:

[0006] Step 1) Design a permanent magnet fault-tolerant hub motor based on an active position-free sensor strategy, and comprehensively consider the position-free operation performance in the design stage to obtain good position-free operation performance and fault-tolerant performance.

[0007] Step 2) In order to give full play to the superior position sensorless operating performance of the permanent magnet fault-tolerant hub motor in step 1), a secondary harmonic suppression and position error signal extraction algorithm based on frequency band adaptation is proposed to suppress the influence of secondary salient pole harmonics on position observation and improve the dynamic response performance of position sensorless control.

[0008] Step 3) Based on the permanent magnet fault-tolerant hub motor with the novel active position sensorless strategy in step 1) and the position sensorless control method in step 2), a five-phase permanent magnet fault-tolerant hub motor position sensorless drive control system is constructed.

[0009] Furthermore, in the step 1), a permanent magnet fault-tolerant hub motor based on an active position sensor-free strategy is characterized in that: from the inside to the outside, it includes a rotating shaft (11), a stator (9), and a rotor (10). The stator (9) is composed of a stator yoke (22), an armature tooth (14), a stator slot (21), and a fault-tolerant tooth (13); the armature teeth (14) and the fault-tolerant teeth (13) are evenly distributed along the outer circumference of the stator (9), and the armature teeth (14) are wound with an armature winding (12), and two adjacent armature winding (14) groups are isolated by the fault-tolerant teeth (13); the main permanent magnets (15) and the iron core poles (16) are evenly distributed along the inner circumference of the rotor (10), and the main permanent magnets (15) are surface-embedded arc-shaped permanent magnets, and the surface-embedded permanent magnet poles are connected to the adjacent The iron core pole (16) forms a pair of magnetic poles; a q-axis magnetic barrier (17) exists between the surface-embedded permanent magnetic pole and the iron core pole (16) near the air gap side, and the q-axis magnetic barrier (17) and the outer circle of the stator (9) form a non-uniform air gap; multiple layers of arc-shaped magnetic barriers (19) exist between the surface-embedded permanent magnetic pole and the iron core pole (16) near the outer circle side, and magnetic bridges (20) are formed between each layer of the arc-shaped magnetic barriers; a rectangular auxiliary permanent magnet (18) is provided between the q-axis magnetic barrier (17) and the arc-shaped magnetic barrier near the air gap, and the auxiliary permanent magnet (18) and the main permanent magnet (15) are connected in series.

[0010] The stator (9) and the rotor (10) are both made of magnetic conductive materials such as silicon steel sheets, with a lamination coefficient of 0.96; the armature winding (12) is made of enameled copper conductor material.

[0011] The armature winding (12) is a single-layer concentrated winding.

[0012] The number of stator teeth is a multiple of 2m, and the difference between the number of stator teeth and the number of rotor poles is 2, where m is the number of phases of the motor.

[0013] The sum of the number of the permanent magnetic poles and the iron core poles (16) is P s .

[0014] The number of rotor poles is P s The number of poles of the main permanent magnet (15) is P m The number of poles of the auxiliary permanent magnet (18) is P a The number of the core poles (16) is P f , the four satisfy the relationship: P m +P f =P s =P a .

[0015] The multi-layer arc-shaped magnetic barriers (19) are designed to be located between the magnetic poles of the main permanent magnet (15) and the iron core poles (16), and are evenly distributed along the circumferential direction of the rotor (10); the auxiliary permanent magnets (18) are located between the multi-layer arc-shaped magnetic barriers (19) and the q-axis magnetic barriers (17), and are evenly distributed along the outer circumferential direction of the rotor (10).

[0016] The center of the q-axis magnetic barrier (17) is O1, and the radius is R1. The center of the multi-layer arc-shaped magnetic barrier (19) is O2, and the radii of the arc-shaped magnetic barriers are R2 and R3 respectively. The thickness of the arc-shaped magnetic barrier is H0.

[0017] The main permanent magnet (15) and the auxiliary permanent magnet (18) are both made of neodymium iron boron permanent magnet steel. The magnetization direction of the main permanent magnet (15) is directed toward the center of the circle, and the magnetization direction of the auxiliary permanent magnet (18) is along the circumferential direction. The magnetization directions of two adjacent auxiliary permanent magnets (18) are opposite, so that the auxiliary magnetic field and the main magnetic field form a magnetic circuit in series.

[0018] The present invention provides a permanent magnet fault-tolerant hub motor based on an active position sensorless strategy, and its specific design method is as follows:

[0019] Step 1.1) Using the slot-pole matching design method of the traditional fault-tolerant motor, the number of stator (9) teeth and the number of rotor (10) pole pairs are preliminarily determined, and the slot vector distribution is determined based on the principle of maximum fundamental wave composite vector.

[0020] Step 1.2) Alternating surface-embedded main permanent magnet poles are set, and the magnetization direction of the main permanent magnet poles all points to the air gap, forming a closed magnetic circuit together with the iron core poles, which is conducive to improving the utilization rate of the permanent magnet.

[0021] Step 1.3) A q-axis magnetic barrier (17) and a multi-layer arc-shaped magnetic barrier (19) are set between the main permanent magnet pole and the iron core pole (16) to increase the cross-axis magnetic resistance, thereby realizing the anti-salient pole characteristic of the motor.

[0022] Step 1.4) A rectangular auxiliary permanent magnet (18) magnetized along the circumferential direction is arranged between the q-axis magnetic barrier (17) and the multi-layer arc-shaped magnetic barrier (19), so that it increases the quadrature-axis magnetic resistance while providing an auxiliary magnetic field, thereby reducing the quadrature-axis inductance and further increasing the anti-saliency effect of the motor.

[0023] In step 1.5), the parameters of the main permanent magnet (15), the auxiliary permanent magnet (18), the q-axis magnetic barrier (17), and the multi-layer arc magnetic barrier (19) are optimized to obtain good anti-salient pole characteristics. By considering the position sensorless operation performance in advance during the motor design stage, the design of an active position sensorless operation permanent magnet fault-tolerant hub motor is realized.

[0024] The design of an active sensorless permanent magnet fault-tolerant in-wheel motor effectively improves the motor's sensorless operation capability. However, the secondary saliency issue still exists, hindering the full utilization of the motor drive system's high-precision sensorless operation performance. To fully realize the superior sensorless performance of this permanent magnet fault-tolerant in-wheel motor, the present invention also provides a sensorless control algorithm based on frequency band adaptation for secondary harmonic suppression and signal extraction.

[0025] Furthermore, in step 2), the specific steps for implementing the position sensorless control algorithm based on frequency band adaptive subharmonic suppression and signal extraction are as follows:

[0026] 2.1) A secondary harmonic suppression algorithm based on frequency band adaptation is used to suppress the influence of secondary salient pole harmonics on position observation.

[0027] An adaptive linear neuron filter based on recursive least squares is used. The filter coefficients are self-tuned through an adaptive algorithm to suppress specific subharmonics in the position error signal. The desired filter output signal y(n) is obtained by processing the harmonic reference signal r(n) and the adjustable weight component x(k). The desired fundamental signal Y(n) is obtained by taking the difference between the input signal U(n) and the desired filter output signal y(n). The recursive least squares method yields the formula:

[0028]

[0029] Where y1(n) is the harmonic estimator; x 11 (n-1), x 21 (n-1) is the estimated amplitude of the harmonic component; is the harmonic reference signal, is the estimated rotor position; Y(n) is the filter output; U(n) is the filter input; the adjustable filter coefficient x 11 (n) and x 21 (n) is updated online based on the harmonic reference signal, and the expression is as follows:

[0030]

[0031] Among them, the gain coefficient k 11 (n) and k 21 (n) is expressed as:

[0032]

[0033] Where μ is the forgetting factor and 0<μ<1. The inverse of the autocorrelation matrix H1(n) is converted into two scales H 11 (n) and H 21(n), making the implementation of the recursive least squares algorithm simpler and faster, H 11 (n) and H 21 (n) can be expressed as:

[0034]

[0035] 2.2) Based on step 2.1), the dynamic response performance of the position sensorless control of the five-phase permanent magnet fault-tolerant hub motor is improved by combining a frequency band adaptive position error signal extraction algorithm.

[0036] By taking advantage of the characteristic that the all-pass network filter only changes the signal phase, linear operations are performed on the signals before and after filtering to construct adaptive bandpass filters and adaptive bandnotch filters. The transfer function of a typical second-order all-pass network filter is:

[0037]

[0038] Where, is the filter bandwidth correlation coefficient, ω m is the filter bandwidth with 3dB attenuation, T s is the digital sampling period; p=cos(ω n T s ), is the filter frequency correlation coefficient, ω n is the resonant frequency point; the resonant frequency in the adaptive band filter is set to:

[0039]

[0040] Where, ω c To inject high frequency signal frequency, To estimate the motor speed, the resonant frequency is automatically adjusted according to the motor speed to reduce the phase delay caused by the filter. The filter bandwidth is set to:

[0041]

[0042] Among them, ω b is the adjustable bandwidth, λ is the dynamic adjustment factor, ω * For a given speed, when the motor is running stably, the dynamic adjustment factor does not work, and the filter bandwidth depends on ω b When the motor is in variable speed operation, the dynamic adjustment factor takes effect again, and the filter bandwidth is adaptively adjusted according to the error between the actual speed and the given speed to improve the dynamic response performance of position-free control. The modulated current can be expressed as:

[0043]

[0044] Where, is the high frequency response current of q1 axis; ω h is the angular frequency of the injected high-frequency signal, is the amplitude of the 2nd high frequency injected harmonic; is the position error function, To estimate the angular position error; the modulated current contains 2 high-frequency injected harmonics, so the adaptive band notch filter ω c Set to 2ω h , to obtain the position error signal

[0045] Furthermore, in step 3), the five-phase permanent magnet fault-tolerant hub motor drive system based on the active position sensorless strategy is characterized by:

[0046] The five-phase permanent magnet fault-tolerant hub motor (1) serves as the drive motor module of the system and outputs electromagnetic torque T e and the five-phase current i abcde ;

[0047] Five-phase current i abcde The feedback quadrature and direct axis current signals i are obtained by the Park transformation module (2). d1q1d3q3 ;

[0048] The sensorless control module (3) based on frequency band adaptive subharmonic suppression and position error signal extraction algorithm, through the feedback current signal i q1 , estimate the rotor position and speed information;

[0049] The MTPA module (4) based on the formula method combines the given speed n with the estimated speed The difference is optimally distributed through the given torque output by the PI controller (5) to obtain the optimal AC and DC axis given current

[0050] The PI controller (5) is used to adjust the given current With the feedback current i d1q1d3q3 Deviation, get the given AC and DC axis voltage signal U d1q1d3q3 ;

[0051] The inverse Park transformation module (6) is used to inversely transform the given AC and DC axis voltage signal U d1q1d3q3 , obtain the voltage signal U in the stationary coordinate system α1β1α3β3 ;

[0052] The SVPWM module (7) is used to convert the voltage signal U α1β1α3β3 Modulate into ten PWM pulse signals required to drive the motor;

[0053] The inverter module (8) outputs five-phase voltage signals through ten PWM pulse signals, thereby providing power to the five-phase permanent magnet fault-tolerant hub motor (1).

[0054] Beneficial effects of the present invention:

[0055] (1) The present invention, for the first time, comprehensively considers the position sensorless operating performance of the motor drive system from the perspective of motor design and control, and proposes a permanent magnet fault-tolerant hub motor drive system based on an active position sensorless strategy. Taking the position-free operating performance into consideration in the motor design stage in advance, a permanent magnet fault-tolerant hub motor based on an active position sensorless strategy is proposed to improve the rotor estimation accuracy in the dynamic steady state when the motor is controlled without a position sensor, and to simplify the complexity of the motor control algorithm. At the same time, for this type of permanent magnet fault-tolerant hub motor, a corresponding position sensorless control algorithm is proposed to achieve high-precision detection of the rotor position to cope with complex and changeable operating conditions.

[0056] (2) The present invention increases the fault tolerance of the motor through phase redundancy and adopts fractional slot concentrated winding, so that different phases of the motor can achieve phase-to-phase magnetic isolation through fault-tolerant teeth, reducing the magnetic circuit coupling between different phases, and greatly improving the reliability of the motor. Unlike traditional motor designs, the present invention takes into account the need for high-precision rotor position detection in the position sensorless control layer. By cleverly setting "alternating poles", "multi-layer magnetic barriers" and "q-axis magnetic barriers" on the rotor, the motor has better anti-salient pole characteristics while reducing the amount of permanent magnets used. This creatively improves the position sensorless operation accuracy from the perspective of motor design.

[0057] (3) In order to further improve the torque output capacity and the reverse salient pole ratio, the motor of the present invention cleverly and reasonably adds auxiliary permanent magnets to the rotor. The auxiliary permanent magnets are located on the q-axis magnetic circuit. The magnetization direction of the auxiliary permanent magnets is along the circumferential direction. They are connected in series with the main permanent magnets on the magnetic circuit, which can improve the torque output capacity of the motor to a certain extent. In addition, since the magnetic permeability of the permanent magnets is quite different from that of the silicon steel sheets, the auxiliary permanent magnets located on the q-axis magnetic circuit can act as auxiliary magnetic sources on the one hand, and increase the q-axis magnetic resistance on the other hand. On the basis of improving the torque output capacity, the reverse salient pole ratio of the motor is further improved, thereby ensuring the high torque output of the motor while having excellent position sensorless operation capability.

[0058] (4) From the perspective of motor drive control, the present invention proposes an adaptive secondary harmonic suppression strategy to suppress the harmonics caused by secondary salient poles and improve the observation accuracy of the rotor position. In addition, to further improve the dynamic response performance of position sensorless control, the present invention proposes an adaptive frequency band filter based on a full-pass network to replace the fixed bandwidth filter for rotor position error signal extraction. The proposed control algorithm can fully utilize the good position sensorless operating performance of the proposed motor structure under multiple working conditions.

[0059] (5) From the perspective of motor design and control, the present invention comprehensively improves the position-free operation accuracy of the motor, provides new ideas for modern position-free control theory, is conducive to promoting the development of the position-free control theory of hub motors, and has significant engineering application value for the development of electric vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 This is a block diagram of the permanent magnet fault-tolerant hub motor drive system based on the active position sensorless strategy of the present invention;

[0061] Figure 2 This is a schematic diagram of the structure of a permanent magnet fault-tolerant hub motor that meets the active position sensorless strategy of the present invention;

[0062] Figure 3 for Figure 1 Schematic diagram of stator structure and armature winding distribution;

[0063] Figure 4 for Figure 1 An enlarged schematic diagram of the local structure and geometric dimensions of the middle rotor;

[0064] Figure 5 for Figure 1 Schematic diagram of magnetization of NdFeB permanent magnets on the middle rotor;

[0065] Figure 6 for Figure 1 Schematic diagram of the direct axis and quadrature axis of the middle rotor;

[0066] Figure 7 A structural block diagram of a design method for an active position sensorless permanent magnet fault-tolerant hub motor provided by the present invention;

[0067] Figure 8 The back EMF waveform of the motor of the present invention;

[0068] Figure 9 The inductance waveform of the motor of the present invention;

[0069] Figure 10 The d-axis and q-axis inductance waveforms of the motor of the present invention when loaded;

[0070] Figure 11This is a graph showing the relationship between the rotor position error angle of the motor according to the present invention and the q-axis current;

[0071] Figure 12 This is a simplified block diagram of the position sensorless control module of the present invention;

[0072] Figure 13 This is a principle block diagram of the adaptive linear neuron filter of the present invention;

[0073] Figure 14 This is a block diagram of the adaptive frequency band filtering principle of the present invention;

[0074] Figure: 1. Five-phase permanent magnet fault-tolerant in-wheel motor; 2. Park transform module; 3. Sensorless control module; 4. MTPA control module; 5. PI module; 6. Inverse Park transform module; 7. SVPWM module; 8. Inverter module. 9. Stator; 10. Rotor; 11. Rotating shaft; 12. Armature winding; 13. Fault-tolerant teeth; 14. Armature teeth; 15. Main permanent magnets; 16. Core poles; 17. Q-axis magnetic barrier; 18. Auxiliary permanent magnets; 19. Multi-layer arc magnetic barrier; 20. Magnetic bridge; 21. Stator slots; 22. Stator yoke. DETAILED DESCRIPTION

[0075] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0076] Figure 1 The figure shows the structural block diagram of the permanent magnet fault-tolerant hub motor drive system of the novel active position sensorless strategy at zero and low speed of the present invention. The five-phase permanent magnet fault-tolerant hub motor (1) is used as the driving motor of the system; the Park transformation module (2) and the inverse Park transformation module (6) are used to decouple the mathematical model in the natural coordinate system; the position sensorless control module (3) is used to estimate the rotor position. and speed Information; MTPA control module (4) based on the formula method, using and The calculation formula of the DC axis reference current is used to allocate the optimal DC axis current under a given torque. Where Ψ f 、i s , L d1 and L q1They are permanent magnet flux linkage, stator current amplitude, direct-axis inductance, and quadrature-axis inductance respectively; a PI controller (5) is used to adjust the deviation between the current given value and the feedback value to obtain a given voltage control signal; an SVPWM module (7) is used to modulate the voltage signal in a given two-phase stationary coordinate system into a required PWM signal; and an inverter module (8) is used to output a five-phase AC signal to provide power to the five-phase permanent magnet fault-tolerant hub motor (1).

[0077] like Figure 2 As shown, the present invention proposes an active position sensor-free permanent magnet fault-tolerant hub motor. The motor adopts a traditional fault-tolerant motor slot-pole combination scheme, and a 20-slot / 18-pole slot-pole combination scheme is selected for a five-phase motor. From the inside to the outside, it includes a rotating shaft (11), a stator (9), and a rotor (10). The stator (9) is composed of a stator yoke (22), an armature tooth (14), a stator slot (21), and a fault-tolerant tooth (13); the armature teeth (14) and the fault-tolerant teeth (13) are evenly distributed along the outer circumference of the stator (9), and the armature winding (12) is wound on the armature teeth (14). Two adjacent armature winding (14) groups are isolated by the fault-tolerant teeth (13); the main permanent magnets (15) and the iron core poles (16) are evenly distributed along the inner circumference of the rotor (10). The main permanent magnets (15) are surface-embedded arc-shaped permanent magnets, and the surface-embedded permanent magnet poles are connected to the adjacent The iron core pole (16) forms a pair of magnetic poles; a q-axis magnetic barrier (17) exists between the surface-embedded permanent magnetic pole and the iron core pole (16) near the air gap side, and the q-axis magnetic barrier (17) and the outer circle of the stator (9) form a non-uniform air gap; a multi-layer arc-shaped magnetic barrier (19) exists between the surface-embedded permanent magnetic pole and the iron core pole (16) near the outer circle side, and a magnetic bridge (20) is formed between each layer of the arc-shaped magnetic barrier; a rectangular auxiliary permanent magnet (18) is provided between the q-axis magnetic barrier (17) and the arc-shaped magnetic barrier near the air gap, and the auxiliary permanent magnet (18) and the main permanent magnet (15) form a series connection. The stator (9) and the rotor (10) are both made of magnetic conductive materials such as silicon steel sheets, and the lamination coefficient is 0.96; the armature winding (12) uses enameled copper conductor material.

[0078] Figure 3 The figure is a schematic diagram of the structure of the stator (9) and the distribution diagram of the armature winding (12). The number of slots in the stator (9) is 20, and the semi-closed flat bottom slots are used. The armature winding (12) is wound on the armature teeth (14) and adopts a single-layer concentrated winding. The armature winding (12) is arranged according to Figure 2 In the order marked in, "+" is the winding incoming direction, and "-" is the winding outgoing direction. The armature windings (12) are isolated by fault-tolerant teeth (13).

[0079] Figure 4 for Figure 1 The enlarged schematic diagram of the local structure and geometric dimensions of the middle rotor (10) is shown in FIG. The inner diameter and outer diameter of the rotor (10) are Ri and R o Surface-embedded arc-shaped main permanent magnets (15) are alternately distributed on the inner ring of the rotor (10), and the main permanent magnets (15) and the iron core poles (16) form a pair of magnetic poles. A q-axis magnetic barrier (17) with a center of O1 and a radius of R1 exists between the main permanent magnet (15) and the core pole (16) near the inner circle, forming the q-axis magnetic barrier (17); a multi-layer arc-shaped magnetic barrier (19) with a radius of O2 and radii of R2 and R3 respectively exists between the main permanent magnet (15) and the core pole (16) near the outer circle, and the thickness of the arc-shaped magnetic barrier is H0, which effectively increases the q-axis magnetic resistance; a magnetic bridge (20) exists between the multi-layer arc-shaped magnetic barriers (19), which reduces the influence on the d-axis magnetic flux; a rectangular auxiliary permanent magnet (18) exists between the arc-shaped magnetic barrier and the q-axis magnetic barrier (17) near the air gap side. Due to the low magnetic permeability of the permanent magnet, it provides an auxiliary magnetic field and acts as the q-axis magnetic barrier (17), which can increase the torque while increasing the anti-salient pole effect.

[0080] Figure 5 for Figure 3 A schematic diagram of the magnetization of the NdFeB permanent magnets on the rotor (10) shows that the magnetization directions of the alternating surface-embedded main permanent magnets (15) located on the inner ring of the rotor (10) are all directed toward the center of the circle, forming a pair of magnetic poles with the adjacent iron core poles (16); the auxiliary permanent magnets (18) located on both sides of the main permanent magnets (15) are magnetized in opposite directions along the circumferential direction, forming a magnetic circuit in series with the main permanent magnets (15).

[0081] Figure 6 for Figure 1 Schematic diagram of the direct axis and quadrature axis of the rotor (10). The centerline of the main permanent magnet (15) magnetic pole is the direct axis direction, and the centerline between the main permanent magnet (15) and the iron core pole (16) is the quadrature axis. The direct axis and the quadrature axis are 90 electrical degrees apart. The inductance corresponding to the quadrature axis of the motor is called the quadrature axis inductance, and the inductance corresponding to the direct axis of the motor is called the direct axis inductance.

[0082] Figure 7 The present invention provides a design method for an active position sensorless permanent magnet fault-tolerant hub motor, and the specific steps are as follows:

[0083] Step 1.1) Using the slot-pole matching design method of the traditional fault-tolerant motor, the number of stator (9) teeth and the number of rotor (10) pole pairs are preliminarily determined, and the slot vector distribution is determined based on the principle of maximum fundamental wave composite vector.

[0084] Step 1.2) Alternating surface-embedded main permanent magnet poles are set, and the magnetization direction of the main permanent magnet poles all points to the air gap, forming a closed magnetic circuit together with the iron core poles, which is conducive to improving the utilization rate of the permanent magnet.

[0085] Step 1.3) A q-axis magnetic barrier (17) and a multi-layer arc-shaped magnetic barrier (19) are set between the main permanent magnet pole and the iron core pole (16) to increase the cross-axis magnetic resistance, thereby realizing the anti-salient pole characteristic of the motor.

[0086] Step 1.4) A rectangular auxiliary permanent magnet (18) magnetized along the circumferential direction is arranged between the q-axis magnetic barrier (17) and the multi-layer arc-shaped magnetic barrier (19), so that it increases the quadrature-axis magnetic resistance while providing an auxiliary magnetic field, thereby reducing the quadrature-axis inductance and further increasing the anti-saliency effect of the motor.

[0087] In step 1.5), the parameters of the main permanent magnet (15), the auxiliary permanent magnet (18), the q-axis magnetic barrier (17), and the multi-layer arc magnetic barrier (19) are optimized to obtain good anti-salient pole characteristics. By considering the position sensorless operation performance in advance during the motor design stage, the design of an active position sensorless operation permanent magnet fault-tolerant hub motor is realized.

[0088] Figure 8 The back EMF waveform of the motor of the present invention has a maximum back EMF of about 78V and a harmonic distortion rate of 2.3%. The back EMF of the motor has a good sinusoidality, which is beneficial to the corresponding drive control and can reduce the cogging torque of the motor.

[0089] Figure 9 This motor's inductance waveform shows high self-inductance and low mutual inductance, accounting for 2.8% of the motor's self-inductance. This provides a certain level of short-circuit current suppression capability. The low magnetic coupling between phases allows for phase-to-phase magnetic isolation, improving the motor's fault tolerance.

[0090] Figure 10 The waveforms of the d-axis and q-axis inductances of the motor of the present invention when loaded are shown. The d-axis inductance of the motor is greater than the q-axis inductance, and the ratio of the d-axis inductance to the q-axis inductance is approximately 1.3. It has good anti-salient pole characteristics, which is beneficial to the zero-speed and low-speed positionless operation of the motor. At the same time, it reduces the risk of irreversible demagnetization of permanent magnets during high-speed weak magnetic field and improves reliability during high-speed cruising.

[0091] Figure 11 This is a relationship diagram of the motor rotor position error angle versus q-axis current of the present invention. When the motor q-axis current changes, the motor rotor position error angle changes slightly, has high stability, and can effectively improve the motor's position-free control accuracy.

[0092] Figure 12 The simplified block diagram of the position sensorless control module is provided. The subharmonic suppression and position error signal extraction algorithm based on frequency band adaptation includes an adaptive frequency band filter and an adaptive linear neuron filter.

[0093] Figure 13This is a block diagram of the principle of the adaptive linear neuron filter based on the recursive least squares method of the present invention. The filter coefficients are self-tuned through an adaptive algorithm to suppress specific subharmonics in the position error signal. The desired filter output signal y(n) is obtained by processing the harmonic reference signal r(n) and the adjustable weight component x(k). The desired fundamental signal Y(n) is obtained by subtracting the input signal U(n) from the desired filter output signal y(n). The recursive least squares method yields the formula:

[0094]

[0095] Where y1(n) is the harmonic estimator; x 11 (n-1), x 21 (n-1) is the estimated amplitude of the harmonic component; is the harmonic reference signal, is the estimated rotor position; Y(n) is the filter output; U(n) is the filter input; the adjustable filter coefficient x 11 (n) and x 21 (n) is updated online based on the harmonic reference signal, and the expression is as follows:

[0096]

[0097] Among them, the gain coefficient k 11 (n) and k 21 (n) is expressed as:

[0098]

[0099] Where μ is the forgetting factor and 0<μ<1. The inverse of the autocorrelation matrix H1(n) is converted into two scales H 11 (n) and H 21 (n), making the implementation of the recursive least squares algorithm simpler and faster, H 11 (n) and H 21 (n) can be expressed as:

[0100]

[0101] Figure 14 This is a block diagram of the adaptive bandpass filter principle of the present invention. By utilizing the characteristic of the all-pass network filter that only changes the signal phase, linear operations are performed on the signals before and after filtering to construct an adaptive bandpass filter and an adaptive bandnotch filter. The transfer function of a typical second-order all-pass network filter is:

[0102]

[0103] Where, is the filter bandwidth correlation coefficient, ωm is the filter bandwidth with 3dB attenuation, T s is the digital sampling period; p=cos(ω n T s ), is the filter frequency correlation coefficient, ω n is the resonant frequency point; the resonant frequency in the adaptive band filter is set to:

[0104]

[0105] Where, ω c To inject high frequency signal frequency, To estimate the motor speed, the resonant frequency is automatically adjusted according to the motor speed to reduce the phase delay caused by the filter. The filter bandwidth is set to:

[0106]

[0107] Among them, ω b is the adjustable bandwidth, λ is the dynamic adjustment factor, ω * For a given speed, when the motor is running stably, the dynamic adjustment factor does not work, and the filter bandwidth depends on ω b When the motor is in variable speed operation, the dynamic adjustment factor takes effect again, and the filter bandwidth is adaptively adjusted according to the error between the actual speed and the given speed to improve the dynamic response performance of position-free control. The modulated current can be expressed as:

[0108]

[0109] Where, is the high frequency response current of q1 axis; ω h is the angular frequency of the injected high-frequency signal, is the amplitude of the 2nd high frequency injected harmonic; is the position error function, To estimate the angular position error; the modulated current contains 2 high-frequency injected harmonics, so the adaptive band notch filter ω c Set to 2ω h , to obtain the position error signal

Claims

1. A permanent magnet fault-tolerant hub motor based on an active position sensorless strategy, characterized by: The invention comprises a rotating shaft (11), a stator (9), and a rotor (10) in sequence from the inside to the outside; the stator (9) is composed of a stator yoke (22), an armature tooth (14), a stator slot (21), and a fault-tolerant tooth (13); the armature teeth (14) and the fault-tolerant tooth (13) are evenly distributed along the outer circumference of the stator (9); the armature teeth (14) are wound with an armature winding (12); two adjacent armature tooth (14) groups are isolated by the fault-tolerant tooth (13); the main permanent magnets (15) and the iron core poles (16) are evenly distributed along the inner circumference of the rotor (10); the main permanent magnets (15) are surface-embedded arc-shaped permanent magnets. The invention relates to a stator body, wherein a surface-embedded main permanent magnetic pole and an adjacent iron core pole (16) form a pair of magnetic poles; a q-axis magnetic barrier (17) exists between the surface-embedded main permanent magnetic pole and the iron core pole (16) near the air gap side, and the q-axis magnetic barrier (17) and the outer circle of the stator (9) form a non-uniform air gap; a multi-layer arc-shaped magnetic barrier (19) exists between the surface-embedded main permanent magnetic pole and the iron core pole (16) near the outer circle side, and a magnetic bridge (20) is formed between each layer of the arc-shaped magnetic barrier; a rectangular auxiliary permanent magnet (18) is provided between the q-axis magnetic barrier (17) and the arc-shaped magnetic barrier near the air gap, and the auxiliary permanent magnet (18) and the main permanent magnet (15) are connected in series.

2. The permanent magnet fault-tolerant hub motor based on active position sensorless strategy according to claim 1, characterized in that: The stator (9) and the rotor (10) are both made of magnetic conductive materials such as silicon steel sheets, and the lamination coefficient is 0.96; the armature winding (12) is made of enameled copper conductor material, and the armature winding (12) is a single-layer concentrated winding.

3. The permanent magnet fault-tolerant hub motor based on active position sensorless strategy according to claim 1, characterized in that: The number of stator teeth is a multiple of 2m, and the difference between the number of stator teeth and the number of rotor (10) poles is 2, where m is the number of phases of the motor; the sum of the number of permanent magnet poles and iron core poles (16) is P s ; The number of poles of the rotor (10) is P s The number of poles of the main permanent magnet (15) is P m The number of poles of the auxiliary permanent magnet (18) is P a The number of the core poles (16) is P f , the four satisfy the relationship: P m +P f =P s =P a .

4. The permanent magnet fault-tolerant hub motor based on active position sensorless strategy according to claim 1, characterized in that: The multi-layer arc-shaped magnetic barrier (19) is designed to be located between the magnetic pole of the main permanent magnet (15) and the iron core pole (16), and is evenly distributed along the circumferential direction of the rotor (10); the auxiliary permanent magnet (18) is located between the arc-shaped magnetic barrier and the q-axis magnetic barrier (17) and is evenly distributed along the outer circumferential direction of the rotor (10); the center of the q-axis magnetic barrier (17) is O1 and the radius is R1, the center of the multi-layer arc-shaped magnetic barrier (19) is O2, the radii of the arc-shaped magnetic barrier are R2 and R3 respectively, and the thickness of the arc-shaped magnetic barrier is H0.

5. The permanent magnet fault-tolerant hub motor based on active position sensorless strategy according to claim 1, characterized in that: The main permanent magnet (15) and the auxiliary permanent magnet (18) are both made of neodymium iron boron permanent magnet steel. The magnetization direction of the main permanent magnet (15) is directed toward the center of the circle, and the magnetization direction of the auxiliary permanent magnet (18) is along the circumferential direction. The magnetization directions of two adjacent auxiliary permanent magnets (18) are opposite.

6. A design method for a permanent magnet fault-tolerant hub motor based on an active position sensorless strategy according to claim 1, characterized in that: The steps include: Step 1.1) Using the slot-pole coordination design method of the fault-tolerant motor, preliminarily determine the number of stator (9) teeth and the number of rotor (10) pole pairs, and determine the slot vector allocation based on the maximum fundamental wave composite vector principle; Step 1.2) Alternating surface-embedded main permanent magnet poles are set, with the magnetization direction of the main permanent magnet poles all pointing to the air gap, forming a closed magnetic circuit together with the core poles, which is conducive to improving the utilization rate of the permanent magnet; Step 1.3) arranging a q-axis magnetic barrier (17) and a multi-layer arc-shaped magnetic barrier (19) between the main permanent magnet pole and the iron core pole (16) to increase the cross-axis magnetic resistance, thereby realizing the anti-salient pole characteristic of the motor; Step 1.4) A rectangular auxiliary permanent magnet (18) magnetized along the circumferential direction is provided between the q-axis magnetic barrier (17) and the multi-layer arc-shaped magnetic barrier (19), so that it increases the quadrature-axis magnetic resistance while providing an auxiliary magnetic field, thereby reducing the quadrature-axis inductance and further increasing the anti-saliency effect of the motor; In step 1.5), the parameters of the main permanent magnet (15), the auxiliary permanent magnet (18), the q-axis magnetic barrier (17), and the multi-layer arc magnetic barrier (19) are optimized to obtain good anti-salient pole characteristics. By considering the position sensorless operation performance in advance during the motor design stage, the design of an active position sensorless operation permanent magnet fault-tolerant hub motor is realized.

7. A driving method of a permanent magnet fault-tolerant hub motor based on an active position sensorless strategy according to claim 1, characterized in that: The steps include: Step 1) designing a permanent magnet fault-tolerant hub motor based on an active position-free sensor strategy according to claim 1, and comprehensively considering the position-free operation performance in the design stage to obtain good position-free operation performance and fault-tolerant performance; Step 2) To fully utilize the superior sensorless operation performance of the permanent magnet fault-tolerant hub motor in step 1), a frequency band adaptive secondary harmonic suppression and position error signal extraction algorithm is proposed to suppress the influence of secondary salient pole harmonics on position observation and improve the dynamic response performance of sensorless control; Step 3) Based on the permanent magnet fault-tolerant hub motor with the novel active position sensorless strategy in step 1) and the position sensorless control method in step 2), a five-phase permanent magnet fault-tolerant hub motor position sensorless drive control system is constructed.

8. The driving method of a permanent magnet fault-tolerant hub motor based on an active position sensorless strategy according to claim 7, characterized in that: A frequency band adaptive secondary harmonic suppression and position error signal extraction algorithm is proposed to suppress the influence of secondary salient pole harmonics on position observation. The specific process is as follows: An adaptive linear neuron filter based on recursive least squares is used. The filter coefficients are self-tuned through an adaptive algorithm to suppress specific subharmonics in the position error signal. The harmonic reference signal r(n) and the adjustable weight component x(k) are processed to obtain the expected output signal y(n) of the filter. The expected fundamental signal Y(n) can be obtained by taking the difference between the input signal U(n) and the expected output signal y(n) of the filter. The formula obtained by the recursive least squares method is: Where y1(n) is the harmonic estimator; x 11 (n-1), x 21 (n-1) is the estimated amplitude of the harmonic component; is the harmonic reference signal, is the estimated rotor position; Y(n) is the filter output; U(n) is the filter input; Adjustable filter coefficient x 11 (n) and x 21 (n) is updated online based on the harmonic reference signal, and the expression is as follows: Among them, the gain coefficient k 11 (n) and k 21 (n) is expressed as: Where μ is the forgetting factor and 0<μ<1, where the inverse of the autocorrelation matrix H1(n) is converted into two scales H 11 (n) and H 21 (n), making the implementation of the recursive least squares algorithm simpler and faster, H 11 (n) and H 21 (n) can be expressed as: 。 9. The driving method of a permanent magnet fault-tolerant hub motor based on an active position sensorless strategy according to claim 8, characterized in that: It also includes the use of the characteristic of the all-pass network filter that only changes the signal phase, performing linear operations on the signals before and after filtering, and constructing adaptive bandpass filters and adaptive bandnotch filters. The transfer function of a typical second-order all-pass network filter is: Where, is the filter bandwidth correlation coefficient, ω m is the filter bandwidth with 3dB attenuation, T s is the digital sampling period; p=cos(ω n T s ), is the filter frequency correlation coefficient, ω n is the resonant frequency point; The resonant frequency in the adaptive band filter is set as: Where, ω c To inject high frequency signal frequency, To estimate the motor speed, the resonant frequency is automatically adjusted according to the motor speed to reduce the phase delay caused by the filter. The filter bandwidth is set to: Among them, ω b is the adjustable bandwidth, λ is the dynamic adjustment factor, ω * For a given speed, when the motor is running stably, the dynamic adjustment factor does not work, and the filter bandwidth depends on ω b When the motor is in variable speed operation, the dynamic adjustment factor takes effect again, and the filter bandwidth is adaptively adjusted according to the error between the actual speed and the given speed to improve the dynamic response performance of position-free control. The modulated current can be expressed as: Where, is the high frequency response current of q1 axis; ω h is the angular frequency of the injected high-frequency signal, is the amplitude of the 2nd high frequency injected harmonic; is the position error function, To estimate the angular position error; the modulated current contains 2 high-frequency injected harmonics, so the adaptive band notch filter ω c Set to 2ω h , to obtain the position error signal 10. The driving method of a permanent magnet fault-tolerant hub motor based on an active position sensorless strategy according to claim 7, characterized in that: The specific process of building a five-phase permanent magnet fault-tolerant hub motor position sensorless drive control system is as follows: The five-phase permanent magnet fault-tolerant hub motor (1) serves as the drive motor module of the system and outputs electromagnetic torque T e and the five-phase current i abcde ; Five-phase current i abcde The feedback quadrature and direct axis current signals i are obtained through Park transformation module (2) d1q1d3q3 ; The sensorless control module (3) based on frequency band adaptive subharmonic suppression and position error signal extraction algorithm, through the feedback current signal i q1 , estimate the rotor position and speed information; The MTPA control module (4) based on the formula method combines the given speed n with the estimated speed The difference is optimally distributed through the given torque output by the PI controller (5) to obtain the optimal given current of the AC and DC axes. The PI controller (5) is used to adjust the given current With the feedback current i d1q1d3q3 Deviation, get the given AC and DC axis voltage signal U d1q1d3q3 ; The inverse Park transformation module (6) is used to inversely transform the given AC and DC axis voltage signal U d1q1d3q3 , obtain the voltage signal U in the stationary coordinate system α1β1α3β3 ; The SVPWM module (7) is used to convert the voltage signal U α1β1α3β3 Modulate into ten PWM pulse signals required to drive the motor; The inverter module (8) outputs a five-phase voltage signal via ten PWM pulse signals, thereby providing power to the five-phase permanent magnet fault-tolerant hub motor (1).

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