Vernier permanent magnet fault-tolerant motor with asymmetric stator teeth

Abstract

The invention discloses a vernier permanent magnet fault-tolerant motor with asymmetric stator teeth, which belongs to the field of fault-tolerant motors and is characterized in that stator slots of the vernier permanent magnet fault-tolerant motor comprise open slots and closed slots; the open slots and the closed slots are equal in number and are arranged in a staggered manner; the tooth widths of the two stator teeth adjacent to the same closed slot are unequal, and the difference between the magnetic conductance amplitudes corresponding to the two stator teeth adjacent to the same closed slot is increased under the working condition of a short-circuit fault, so that the magnetic line of force which originally passes through a long magnetic circuit to be closed but must flow through the narrow teeth is changed to pass through the wide teeth due to the increase of the magnetic resistance; the capability of guiding magnetic lines to form a ring tooth magnetic circuit by the closed slot is enhanced, so that the leakage inductance of the ring tooth magnetic circuit slot under a short-circuit fault is increased, and the short-circuit resistance of the motor is enhanced; meanwhile, the span of the coil winding is closer to one polar distance, the utilization rate of the winding to a rotor excitation magnetic field and the groove area are improved, and then high torque output of the motor under the normal working condition can be guaranteed by increasing the current flowing through the grooves.

Description

Technical Field

[0001] The invention belongs to the field of fault-tolerant motors, and more specifically, relates to a vernier permanent magnet fault-tolerant motor with asymmetric stator teeth. Background Art

[0002] With the continuous acceleration of the global electrification wave, permanent magnet motors are widely used in aerospace, marine equipment, electric vehicles and other transportation electrification fields due to their simple structure, high power density, high operating efficiency and flexible control. These fields have high requirements for system reliability and safety due to the harsh working environment. In the actual operation of the motor, affected by unstable factors such as temperature, humidity, pressure and vibration, various open circuit or short circuit faults will inevitably occur. Among them, the probability of turn-to-turn short circuit faults is relatively high, and a huge demagnetization current will be generated in the faulty coil, which can usually reach more than ten times or even dozens of times the rated current value. If not intervened in time, it will cause the local temperature rise of the motor to be too high, burn the winding insulation, and cause irreversible demagnetization faults of the permanent magnet, etc. In severe cases, it will cause equipment shutdown and safety accidents. Therefore, the motor and its drive system must not only meet the requirements of torque density and efficiency, but also have a certain fault tolerance and short circuit resistance to cope with emergencies. The research on high-reliability motor drive system is of great significance.

[0003] In recent years, in order to meet the "three highs" characteristic index requirements of high power density, high operating efficiency and high dynamic characteristics of high-quality motor systems, various new principles and new structures of motors have emerged. Among them, a type of vernier permanent magnet motor based on the "magnetic field modulation principle" has obvious advantages of high torque density due to its multi-working magnetic field harmonic characteristics. It achieves low-speed and high-torque operation without changing the power supply frequency or increasing the number of motor poles and slots, and has become a research hotspot for scholars at home and abroad.

[0004] At present, the anti-short-circuit design of motors is mainly based on the design of winding arrangement, fault-tolerant teeth and stator slots. The winding impedance is increased by adopting fractional slot concentrated windings, reducing the number of parallel windings and setting magnetic slot wedges at the slots. However, fault tolerance and power density are usually two contradictory characteristics. The change of slot size will also affect parameters such as slot fill rate and slot coefficient, and the short-circuit current cannot be suppressed to the greatest extent. For example, patent document CN113708522A discloses a high-reliability permanent magnet fault-tolerant steering motor, such as Figure 1As shown, the winding method in this invention adopts the form of tooth-interval winding of fractional slot single-layer concentrated winding, the fault-tolerant teeth have no winding, and the stator adopts the distribution of large and small teeth, so that the mutual inductance between the motor phases and the mutual inductance of the high and low voltage windings are almost 0, which improves the fault tolerance of the motor and reduces the probability of phase-to-phase short-circuit failure. However, the winding connection method of single-layer tooth-interval winding and the fault-tolerant tooth structure cannot isolate the winding coils in the same stator slot, and do not have the ability to autonomously change the magnetic flux of the winding cross-link under fault conditions to further reduce the degree of common magnetic circuit coupling between windings. This method of physically isolating the windings of each phase has limited ability to suppress short-circuit current. Summary of the invention

[0005] In view of the above defects or improvement needs of the prior art, the present invention provides a vernier permanent magnet fault-tolerant motor with asymmetric stator teeth, so as to solve the technical problem that the vernier permanent magnet motor in the prior art has poor short-circuit resistance.

[0006] In order to achieve the above-mentioned object, the present invention provides a vernier permanent magnet fault-tolerant motor with asymmetric stator teeth, wherein the stator and the rotor are coaxially mounted, and an air gap is provided between the rotor and the stator;

[0007] The stator comprises: a stator core and an armature winding; the stator core is provided with stator teeth arranged along the circumferential direction; a stator slot is arranged between two adjacent stator teeth; the armature winding is wound in the stator slot;

[0008] The stator slots include two types: open slots and closed slots; the number of open slots and closed slots is equal and they are staggered; the tooth widths of two stator teeth adjacent to the same closed slot are unequal, which enhances the ability of the closed slot to guide the magnetic lines of force through the ring tooth magnetic circuit under short-circuit fault conditions, increases the slot leakage inductance, and thus significantly improves the short-circuit resistance of the vernier permanent magnet fault-tolerant motor.

[0009] Further preferably, the stator teeth are parallel teeth; the slot opening angle of the closed slot is The slot opening angle of the opening slot is Among them, Z s is the number of stator slots; k so1 is the slot opening coefficient of the closed slot, and its value is 0.633; k so2 is the slot opening coefficient of the open slot, and its corresponding value range is 0.7~0.833.

[0010] Further preferably, in order to better reduce the short-circuit current amplitude while taking into account the high torque output of the vernier permanent magnet motor, in the two stator teeth adjacent to the same closed slot, the tooth width ratio of the stator tooth with a wider tooth width to the stator tooth with a narrower tooth width is in the range of 11:9 to 11:5.

[0011] Further preferably, the slot areas of all stator slots are equal.

[0012] Further preferably, an arc-shaped iron core is provided at the slot opening of each closed slot, and an auxiliary groove is provided on the air gap surface of the closed slot;

[0013] Among them, a closed slot and two stator teeth adjacent to the closed slot constitute a functional multiplexing unit; the functional multiplexing unit is used to conduct magnetism to amplify the torque under normal working conditions; under short-circuit fault conditions, the direction of the magnetic lines of force and the magnetic flux interlinked with the winding are changed to form a ring tooth magnetic circuit to reduce the short-circuit current.

[0014] Further preferably, the position distribution of each auxiliary groove is determined by the following method:

[0015] Determine whether each harmonic of the motor's armature winding contributes to the motor's back electromotive force and whether the contribution is positive or negative through a motor simulation model, and use the armature winding harmonic that contributes to the back electromotive force as a working harmonic; wherein the motor simulation model is a simulation model of the above-mentioned vernier permanent magnet fault-tolerant motor without auxiliary grooves;

[0016] Based on the magnetic field modulation principle, the pole pairs and phases of the permeance harmonics corresponding to each operating harmonic are calculated respectively, and the phase of the permeance harmonic corresponding to the armature winding harmonic with a negative contribution to the back electromotive force is reversed by 180° as the phase of the permeance harmonic;

[0017] Based on the pole pairs and phases of the permeance harmonics corresponding to each operating harmonic, a spatial permeance waveform having a mapping relationship with the stator tooth structure is constructed;

[0018] Based on the positive and negative information of the spatial magnetic permeability waveform and the stator tooth distribution of the motor simulation model, the starting position and arc of each auxiliary groove along the circumferential direction are determined as the final position distribution design result.

[0019] Further preferably, the spatial magnetic permeability waveform is formed by superimposing the waveforms of each spatial magnetic permeability element; the expression of the waveform of the i-th spatial magnetic permeability element is:

[0020]

[0021] Among them, k wPr and k wv P r The coefficient of the subharmonic winding and the v subharmonic winding coefficient; P r is the number of rotor permanent magnet pole pairs; v is the order of the harmonic of the working armature winding, v = |P r ±P mj |; j is the harmonic order of magnetic permeability; θ mj is the phase value of the jth permeance harmonic, P mj is the number of pole pairs of the jth permeance harmonic, θ si is the position of the i-th spatial magnetic permeance element.

[0022] Further preferably, the groove depth of each auxiliary groove is determined by:

[0023] In the motor simulation model, each auxiliary groove is set on the near-air-gap surface of each closed slot according to the above-mentioned final position distribution design result;

[0024] The slot depth of each auxiliary groove in the motor simulation model is adjusted, and the slot depth of each auxiliary groove when the amplitude of the magnetic permeance harmonic corresponding to each working harmonic of the motor is maximized is taken as the final slot depth size design result.

[0025] Further preferably, the armature winding is a three-phase AC winding, including a double-layer winding coil; the two winding coils in the same closed slot belong to different phases, and the polarities of the currents flowing therethrough are opposite.

[0026] Further preferably, the coil span of the armature winding is 2.

[0027] Further preferably, the rotor is arranged inside the stator, and the stator teeth are arranged inside the stator core to form an outer stator structure; or, the rotor is arranged outside the stator, and the stator teeth are arranged outside the stator core to form an inner stator structure.

[0028] Further preferably, the number of stator slots Z s , rotor permanent magnet pole pair number P r and armature winding pole pair number P a The following relations are satisfied:

[0029]

[0030] Among them, P a =min{iZ s ±P r |, i∈ positive integer set}, GCD(Z s ,P a ) is Z s and P a The greatest common divisor of .

[0031] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0032] 1. The present invention provides a vernier permanent magnet fault-tolerant motor with asymmetric stator teeth, wherein the stator slots include two types: open slots and closed slots; the number of open slots and closed slots is equal and they are staggered; in order to cooperate with the characteristic that the number of stator teeth of the vernier permanent magnet motor is close to the number of rotor poles, the tooth widths of two stator teeth adjacent to the same closed slot are adjusted to be unequal, at which time the difference between the magnetic permeability amplitudes corresponding to the two stator teeth adjacent to the same closed slot increases, resulting in the magnetic lines of force that originally took the long magnetic circuit to close but must flow through the narrow teeth will change to the wide teeth due to the increase in magnetic resistance, and the ability of the closed slot to guide the magnetic lines of force to form a ring tooth magnetic circuit is enhanced, thereby increasing the leakage inductance of the ring tooth magnetic circuit slot under a short-circuit fault, improving the suppression effect of the short-circuit current, and the vernier permanent magnet fault-tolerant motor has a strong short-circuit resistance.

[0033] 2. The vernier permanent magnet fault-tolerant motor with asymmetric stator teeth provided by the present invention has unequal tooth widths of two stator teeth adjacent to the same closed slot. By adjusting the width difference of the two stator teeth, the coil winding span is closer to one pole pitch, thereby improving the utilization rate of the winding for the rotor excitation magnetic field. At the same time, the design of unequal tooth widths of adjacent stator teeth can also increase the slot area, and the output torque can be increased by increasing the current flowing through the slots, thereby ensuring the high torque density advantage of the vernier permanent magnet fault-tolerant motor under normal working conditions.

[0034] 3. Furthermore, in the vernier permanent magnet fault-tolerant motor with asymmetric stator teeth provided by the present invention, the slot areas of all stator slots are equal, so as to facilitate winding and ensure that the slot fill rates of all stator slots are the same.

[0035] 4. Furthermore, the vernier permanent magnet fault-tolerant motor with asymmetric stator teeth provided by the present invention has auxiliary grooves on the near-air-gap surface of the closed slot; each closed slot and two adjacent stator teeth together constitute a basic functional reuse unit. Under short-circuit fault conditions, since the slot opening of the closed slot is an arc-shaped iron core structure rather than air, the magnetic permeability of the arc-shaped iron core is several thousand times that of air. Compared with the long magnetic circuit closure of the magnetic lines of force, the functional reuse unit is more likely to guide them to take the ring tooth magnetic circuit with relatively lower magnetic resistance, thereby changing the direction of the magnetic lines of force and the magnetic flux interlinked with the winding, forming a ring tooth magnetic circuit, increasing the slot leakage inductance to increase the winding inductance, and being able to more effectively suppress the short-circuit current, further improving the fault-tolerant performance of the motor. Under normal working conditions, the function multiplexing unit plays the role of magnetic conduction and modulation harmonic pole number. The composition of magnetic conduction harmonics determines its conversion effect on the number of magnetic field harmonic poles, that is, it will not produce a large number of harmonics with high pole numbers, short wavelengths, and easy to form short magnetic circuits, which will hinder the magnetic lines of force from running through the ring gear magnetic circuit to a certain extent, ensuring the high torque output advantage of the vernier permanent magnet fault-tolerant motor under normal working conditions. Based on this, the present invention can coordinate the strong fault tolerance and high torque density of the vernier permanent magnet fault-tolerant motor.

[0036] 5. Furthermore, the setting of the function reuse unit of the vernier permanent magnet fault-tolerant motor provided by the present invention will cause the number of modulation teeth to be halved, and part of the working permeance harmonics will be converted into non-working permeance harmonics, resulting in the weakening of the magnetic field modulation capability and the decrease in the amplitude of the modulated working magnetic field harmonics. For the vernier permanent magnet motor, the working harmonic content directly determines the torque quality of the motor. Therefore, from the harmonic perspective, the optimal position arrangement of the auxiliary grooves is derived by directional editing of the pole pairs and phase composition of the permeance harmonics. The optimal function reuse unit structure after directional design improves the amplitude of the effective working magnetic field harmonics that contribute to the positive and reverse electromotive force, compensates for the weakened magnetic field modulation effect due to the setting of half of the closed slots, solves the contradiction between the motor's short-circuit resistance and the weakened permeance modulation effect due to the use of closed slots, and better guarantees the high torque output of the motor under normal working conditions.

[0037] 6. Furthermore, the vernier permanent magnet fault-tolerant motor provided by the present invention will use the slot depth dimensions of each auxiliary groove when the amplitude of the magnetic permeance harmonic corresponding to each working armature winding harmonic of the motor is maximized as the final slot depth dimension design result, further improving the magnetic field modulation capability of the vernier permanent magnet motor, thereby further ensuring its high torque density advantage under normal working conditions.

[0038] 7. Furthermore, the vernier permanent magnet fault-tolerant motor provided by the present invention has an armature winding which is a three-phase AC winding, including a double-layer winding coil; the two winding coils in the same closed slot belong to different phases, and the polarities of the currents passed through them are opposite. Under normal operating conditions, magnetic motive forces of the same magnitude and direction but different phases will be generated. The mutual antagonism of the magnetic lines of force in the same direction prevents most of the magnetic lines of force from taking the circular magnetic circuit, and the difference in phases prevents the magnetic motive forces from being completely offset, thereby reducing the torque density, further ensuring the torque performance of the motor under normal operating conditions.

[0039] 8. Furthermore, the vernier permanent magnet fault-tolerant motor provided by the present invention adopts a double-layer winding across two teeth with a coil span of 2. Compared with the conventional fractional slot concentrated winding, the working harmonic winding coefficient remains unchanged. At the same time, the results show that the winding connection method across two teeth combined with the function multiplexing unit can further reduce the short-circuit current. The difference between the two is that at this time, part of the magnetic lines of force flowing through the stator teeth on both sides of the function multiplexing unit also come from the magnetomotive force generated by the same coil across the two teeth, and the motor's short-circuit resistance and dynamic performance are further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic diagram of the structure of the high-reliability permanent magnet fault-tolerant steering motor provided in CN113708522A;

[0041] Figure 2 It is a structural schematic diagram of a traditional vernier permanent magnet motor;

[0042] Figure 3 A schematic structural diagram of a vernier permanent magnet fault-tolerant motor with asymmetric stator teeth provided in Example 1 of the present invention;

[0043] Figure 4 A schematic diagram of the direction of magnetic lines of force of the asymmetric stator tooth type vernier permanent magnet fault-tolerant motor provided in Example 1 of the present invention only when the stator armature winding is excited under a short circuit fault;

[0044] Figure 5 A schematic diagram of the structure of an asymmetric stator tooth type vernier permanent magnet fault-tolerant motor for realizing equal slots with stator teeth having larger inclined tooth widths provided in Example 2 of the present invention;

[0045] Figure 6 A schematic diagram of the structure of an asymmetric stator tooth type vernier permanent magnet fault-tolerant motor for realizing equal slots with stator teeth having a smaller inclined tooth width provided in Embodiment 3 of the present invention;

[0046] Figure 7 A schematic diagram of the structure of a function multiplexing unit provided in Embodiment 4 of the present invention;

[0047] Figure 8 A schematic structural diagram of an asymmetric stator tooth-type vernier permanent magnet fault-tolerant motor provided in Embodiment 4 of the present invention, in which the stator auxiliary slots are arc-shaped auxiliary slots;

[0048] Fig. 9 A schematic structural diagram of a stator auxiliary slot in an asymmetric stator tooth type vernier permanent magnet fault-tolerant motor provided in Example 4 of the present invention, in which the stator auxiliary slot is a triangular auxiliary slot;

[0049] Fig.10 A schematic structural diagram of a stator auxiliary slot in an asymmetric stator tooth-type vernier permanent magnet fault-tolerant motor provided in Embodiment 4 of the present invention, in which the stator auxiliary slot is a trapezoidal auxiliary slot;

[0050] Fig.11 A comparison diagram of the short-circuit current between winding turns of the conventional vernier permanent magnet motor, the asymmetric stator tooth type vernier permanent magnet fault-tolerant motor provided in Embodiment 1, Embodiment 2 and Embodiment 3 under a short-circuit fault provided by the present invention.

[0051] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0052] I-1 is the high-voltage side winding, I-2 is the low-voltage side winding, I-3 is the fault-tolerant tooth, I-4 is the armature tooth, I-5 is the rotor core, I-6 is the rotor, I-7 is the permanent magnet, I-8 is the stator, I-9 is the stator core, and I-10 is the stator slot depth;

[0053] 1 is the stator core, 2 is the armature winding, 3 is the permanent magnet, 4 is the rotor core, 5 is the function multiplexing unit, 6 is the auxiliary groove, 7 is the asymmetric tooth, 8 is the oblique large tooth, and 9 is the oblique small tooth. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is 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. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0055] In order to achieve the above-mentioned object, the present invention provides a vernier permanent magnet fault-tolerant motor with asymmetric stator teeth, wherein the stator and the rotor are coaxially mounted, and an air gap is provided between the rotor and the stator;

[0056] The stator comprises: a stator core and an armature winding; the stator core is provided with stator teeth arranged along the circumferential direction; a stator slot is arranged between two adjacent stator teeth; the armature winding is wound in the stator slot;

[0057] The stator slots include two types: open slots and closed slots; the number of open slots and closed slots is equal and they are staggered; the widths of the two stator teeth adjacent to the same closed slot are different, which is used to enhance the closed slot's ability to guide the magnetic lines of force through the ring tooth magnetic circuit under short-circuit fault conditions, increase the slot leakage inductance, and thus significantly improve the short-circuit resistance of the vernier permanent magnet motor. At the same time, it also makes the coil winding span closer to a pole pitch, which improves the utilization rate of the winding to the rotor excitation magnetic field and the slot area under normal conditions. The output torque can be increased by increasing the current flowing through the slots, ensuring the high torque density advantage of the vernier permanent magnet fault-tolerant motor under normal conditions.

[0058] It should be noted that the stator teeth may be parallel teeth, helical teeth, split teeth, large and small teeth, etc. Preferably, in an optional implementation, the stator teeth are parallel teeth.

[0059] In an optional embodiment, the slot opening angle of the closed slot is The slot opening angle of the opening slot is Among them, Z s is the number of stator slots; k so1 is the slot opening coefficient of the closed slot, and its value is 0.633; k so2 is the slot opening coefficient of the open slot, and its corresponding value range is 0.7~0.833.

[0060] Preferably, in two stator teeth adjacent to the same closed slot, the tooth width ratio of the stator tooth with a wider tooth width to the stator tooth with a narrower tooth width is in the range of 11:9 to 11:5.

[0061] It should be noted that the slot areas of the stator slots may be equal or unequal; preferably, in an optional implementation, the slot areas of all stator slots are equal. Specifically, when the stator teeth are parallel teeth, this can be achieved by tilting wide teeth or narrow teeth.

[0062] In an optional implementation, an arc-shaped core is provided at the slot of each closed slot, and an auxiliary groove is provided near the air gap surface. A closed slot and two stator teeth adjacent to the closed slot constitute a functional multiplexing unit; the functional multiplexing unit is used to conduct magnetism to amplify torque under normal working conditions; under short-circuit fault conditions, the direction of magnetic lines of force and the magnetic flux linked with the winding are changed to form a ring tooth magnetic circuit to reduce short-circuit current.

[0063] In an optional embodiment, the position distribution and groove depth of each auxiliary groove are determined by:

[0064] Determine whether each harmonic of the motor's armature winding contributes to the motor's back electromotive force and whether the contribution is positive or negative through a motor simulation model, and use the armature winding harmonic that contributes to the back electromotive force as the working winding harmonic; wherein the motor simulation model is a simulation model of the above-mentioned vernier permanent magnet fault-tolerant motor without auxiliary grooves;

[0065] Based on the magnetic field modulation principle, the pole pairs and phases of the permeance harmonics corresponding to each operating harmonic are calculated respectively, and the phase of the permeance harmonic corresponding to the armature winding harmonic with a negative contribution to the back electromotive force is reversed by 180° as the phase of the permeance harmonic;

[0066] Based on the pole pair number and phase information of the permeance harmonic corresponding to each working harmonic, a spatial permeance waveform with a mapping relationship with the stator tooth structure is constructed; wherein the spatial permeance waveform is formed by superimposing the waveforms of each spatial permeance element; the waveform K of the i-th spatial permeance element i The expression is:

[0067]

[0068] Among them, k wPr and k wv P r The coefficient of the subharmonic winding and the v subharmonic winding coefficient; P r is the number of rotor permanent magnet pole pairs; v is the order of the harmonic of the working armature winding, v = |P r ±P mj |; j is the harmonic order of magnetic permeability; θ mj is the phase value of the jth permeance harmonic, P mj is the number of pole pairs of the jth permeance harmonic, θ si is the position of the i-th spatial magnetic permeance element.

[0069] Based on the positive and negative information of the spatial magnetic permeability waveform and the stator tooth distribution of the motor simulation model, the starting position and arc of each auxiliary groove along the circumferential direction are determined as the final position distribution design result.

[0070] In an optional embodiment, the groove depth of each auxiliary groove is determined by:

[0071] In the motor simulation model, each auxiliary groove is set on the near-air-gap surface of each closed slot according to the above-mentioned final position distribution design result;

[0072] The slot depth of each auxiliary groove in the motor simulation model is adjusted, and the slot depth of each auxiliary groove when the amplitude of the magnetic permeance harmonic corresponding to each working harmonic of the motor is maximized is taken as the final slot depth size design result.

[0073] In an optional embodiment, the armature winding is a three-phase AC winding, including a double-layer winding coil; the two winding coils in the same closed slot belong to different phases, and the polarities of the currents passing through them are opposite. The coil span of the armature winding can be 1, 2, 3, etc., preferably 2. The armature winding connection mode can be centralized or distributed, which is not limited here.

[0074] It should be noted that the rotor can be arranged inside the stator or outside the stator, which is not limited here. In an optional embodiment, the rotor is arranged inside the stator, and the stator teeth are arranged on the inner side of the stator core to form an outer stator structure. In another optional embodiment, the rotor is arranged outside the stator, and the stator teeth are arranged on the outer side of the stator core to form an inner stator structure.

[0075] In order to further illustrate the vernier permanent magnet fault-tolerant motor provided by the present invention, a vernier permanent magnet fault-tolerant motor in which the stator and the rotor are coaxially mounted from the outside to the inside is taken as an example for detailed description:

[0076] Figure 2 The schematic diagram of the structure of a traditional vernier permanent magnet motor includes a stator and a rotor. The stator and the rotor are coaxially mounted from the outside to the inside, and an air gap is provided between the rotor and the stator. When the motor is working, the rotor rotates around the rotating axis relative to the stator. The stator includes: a stator core 1 and an armature winding 2. The stator core 1 is provided with stator teeth evenly distributed along the circumferential direction. The rotor includes: a permanent magnet 3 and a rotor core 4.

[0077] The stator teeth are parallel tooth type; the inner wall of the stator is evenly distributed with multiple stator slots along the circumferential direction, all of which are open slots; the armature winding 2 is wound in the stator slots; the rotor includes a permanent magnet array 3 and a rotor core 4; the permanent magnet array 3 is fixed around the rotor near the air gap surface, and the shape, thickness and pole arc coefficient of each permanent magnet are equal, and they are magnetized along the radial direction. Adjacent permanent magnets have opposite polarities and are fixed around the rotor core 4 in the order of NS-NS. The material is hard magnetic materials such as neodymium iron boron, samarium cobalt or ferrite.

[0078] Different from the structure of the traditional vernier permanent magnet motor, the present invention provides a vernier permanent magnet fault-tolerant motor with asymmetric stator teeth, wherein the stator and the rotor are coaxially mounted, and an air gap is provided between the rotor and the stator;

[0079] The stator comprises: a stator core and an armature winding; the stator core is provided with stator teeth arranged along the circumferential direction; a stator slot is arranged between two adjacent stator teeth; the armature winding is wound in the stator slot;

[0080] The stator slots include two types: open slots and closed slots; the number of open slots and closed slots is equal and they are staggered; the tooth widths of two stator teeth adjacent to the same closed slot are not equal.

[0081] The following are some specific embodiments of the vernier permanent magnet fault-tolerant motor with asymmetric stator teeth provided by the present invention:

[0082] Example 1

[0083] like Figure 3 The structure diagram of a vernier permanent magnet fault-tolerant motor with asymmetric stator teeth provided in this embodiment 1 is shown, which includes a stator and a rotor; the stator and the rotor are coaxially mounted from the outside to the inside, an air gap is provided between the rotor and the stator, and the rotor rotates around the rotating axis relative to the stator. The stator includes: a stator core 1, an armature winding 2; the stator core 1 is provided with stator teeth evenly distributed along the circumferential direction. The rotor includes: a permanent magnet 3 and a rotor core 4.

[0084] Stator slots are arranged between two adjacent stator teeth. Each stator slot is evenly distributed along the circumference of the inner wall of the stator core 1. There are two types of stator slots: open slots and closed slots. The number of open slots and closed slots is equal and they are placed alternately. Among them, open and closed indicate whether the side facing the rotor is open or closed. Auxiliary slots 6 are arranged near the air gap surface of the closed slot. Each closed slot and its two adjacent stator teeth together constitute a basic functional multiplexing unit 5. The optimal position arrangement of the auxiliary slots 6 is derived by directional editing of the pole pairs and phase composition of the magnetic permeance harmonics. The optimal functional multiplexing unit structure after directional design improves the amplitude of the effective working magnetic field harmonics that contribute to the positive and negative electromotive force, and compensates for the magnetic field modulation effect weakened by the setting of half of the closed slots.

[0085] The armature winding 2 in this embodiment adopts a double-layer winding form across two teeth with a coil span of 2. In order to ensure the high torque density of the vernier permanent magnet fault-tolerant motor under normal working conditions, the polarities of the currents passed through the winding coils belonging to different phases in the same closed slot remain opposite. Under the slot-pole coordination of this embodiment, whether the conventional fractional slot concentrated winding form or the winding form across two teeth is adopted, the working harmonic winding coefficient is 0.866. In contrast, the winding form across two teeth in combination with the function multiplexing unit 5 can better ensure the high torque density of the vernier permanent magnet fault-tolerant motor under normal working conditions, and further improve the motor's anti-short circuit capability. The difference between the two is that when the conventional fractional slot concentrated winding form is adopted, most of the magnetic lines of force of the function multiplexing unit 5 flowing through the stator teeth on both sides are derived from the magnetomotive force generated by the two winding coils belonging to different phases in the same closed slot, and their magnitude and direction are the same, but the phase is different; while when the winding form across two teeth is adopted, the magnetic lines of force of the function multiplexing unit 5 flowing through the stator teeth on both sides are not only derived from the two coil windings belonging to different phases in the same closed slot, but also some of the magnetic lines of force are derived from the magnetomotive force generated by the same coil across the two teeth, and their magnitude is , direction and phase are the same; the latter part of the magnetic force lines is more likely to not go through the ring tooth magnetic circuit under healthy conditions due to the mutual cancellation of the completely identical magnetic motive forces; under fault conditions, the magnitude of the magnetic motive forces that were originally different in phase also becomes unbalanced, and the weakening of the counteraction between the magnetic force lines in the same direction is more inclined to guide the magnetic force lines to go through the ring tooth magnetic circuit, further increasing the slot leakage inductance and the phase winding self-inductance, playing a role in suppressing the short-circuit current under short-circuit faults (including single-phase short circuits and turn-to-turn short circuits), and further improving the short-circuit resistance and dynamic performance of the motor. Both the stator core 1 and the rotor core 4 can be laminated with soft magnetic materials such as silicon steel sheets.

[0086] In this embodiment, the stator teeth are parallel teeth; the tooth widths of two stator teeth adjacent to the same closed slot are not equal, and the design of asymmetric teeth 7 is adopted, and the tooth width ratio of the stator teeth with wider tooth width to the stator teeth with narrower tooth width ranges from 11:9 to 11:5. In this embodiment, the tooth width ratio of the stator teeth with wider tooth width to the stator teeth with narrower tooth width is 11:5 by increasing the slot opening width of the open slot. At this time, the slot areas of adjacent stator slots are not equal, and the slot area S1 corresponding to each open slot is greater than the slot area S2 corresponding to the adjacent closed slot. It should be noted that increasing the slot opening width of the closed slot can also achieve a tooth width ratio of the stator teeth with wider tooth width to the stator teeth with narrower tooth width of 11:5. At this time, the slot areas of adjacent stator slots are also unequal, and the slot area S2 corresponding to each closed slot is greater than the slot area S1 corresponding to the adjacent open slot. The asymmetric tooth 7 design adjusts the width difference between the two stator teeth adjacent to the same closed slot, making the coil winding span closer to a pole pitch, thereby improving the utilization rate of the winding for the rotor excitation magnetic field, and at the same time increasing the slot area, and can increase the torque density by increasing the current flowing through the slots. Compared with the symmetrical tooth structure, due to the reduction of the magnetic permeability of the magnetic circuit on one side of the functional multiplexing unit 5, the magnetic lines of force that originally closed the long magnetic circuit but must flow through the narrow teeth will change to wide teeth due to the increase in magnetic resistance. The ability of the functional multiplexing unit 5 to guide the magnetic lines of force to form the ring tooth magnetic circuit is enhanced, further reducing the degree of common magnetic circuit coupling between the faulty phase winding and other phase windings, thereby increasing the leakage inductance of the ring tooth magnetic circuit slot under a short-circuit fault, and improving the suppression effect of the short-circuit current. Although the same influence also exists on the distribution of magnetic lines of force of the motor under normal working conditions, the short-circuit current is significantly reduced (the short-circuit current is reduced by 82.97%) while ensuring the high torque output of the vernier permanent magnet motor (the average torque is reduced by 14.53%, but still higher than the traditional single-working harmonic permanent magnet motor under the same stator, rotor inner and outer diameters and shaft length conditions). At this time, the short-circuit current peak is only more than 3 times the rated current, and the motor's ability to autonomously suppress short-circuit current is significantly improved.

[0087] In the simulation model of the vernier permanent magnet fault-tolerant motor with asymmetric stator teeth provided in this embodiment, the permanent magnet 3 is set to air, and the armature winding 2 is passed with rated current. In the case of a short circuit fault, the distribution of the magnetic lines of force of the motor in this embodiment is as follows: Figure 4 After the function multiplexing unit 5 is adopted, the magnetic flux generated by the armature winding 2 mainly forms a closed annular magnetic circuit in the two adjacent stator teeth corresponding to the function multiplexing unit 5, and only a small amount of magnetic lines of force take the long magnetic circuit to intersect with other phase windings, which reduces the coupling degree between the faulty phase winding and other phase windings, which is reflected in the low phase-to-phase mutual inductance. At the same time, the annular tooth magnetic flux increases the slot leakage inductance, improves the self-inductance of the phase winding under fault conditions, and improves the magnetic isolation capability and fault tolerance performance of the motor.

[0088] Example 2

[0089] The structure of the vernier permanent magnet fault-tolerant motor in this embodiment is the same as that of the vernier permanent magnet fault-tolerant motor in Example 1. The difference is that in this embodiment, the slot areas of all stator slots are equal. Specifically, the stator adopts an asymmetric tooth 7 design, in which the ratio of the large tooth width to the small tooth width is 11:5. In order to achieve equal slot fill rates of each stator slot to facilitate winding, the stator adopts an inclined large tooth 8 method (a method of tilting stator teeth with larger tooth widths) as shown in FIG. Figure 5 As shown, the magnetic permeance distribution near the air gap side remains unchanged to ensure that the magnetic field modulation effect remains unchanged. At this time, the inclination angle of the large tooth is 23.6° to ensure that the slot area S1 corresponding to each open slot is equal to the slot area S2 corresponding to the adjacent closed slot. The results show that compared with Example 1, the design of the oblique large tooth 8 in conjunction with the function multiplexing unit 5 can further reduce the short-circuit current (the short-circuit current is reduced by 85.6%). At this time, the short-circuit current peak can reach less than 3 times the rated current, and the motor has a stronger short-circuit resistance.

[0090] Example 3

[0091] The structure of the vernier permanent magnet fault-tolerant motor in this embodiment is the same as that of the vernier permanent magnet fault-tolerant motor in Example 1. The difference is that in this embodiment, the slot areas of all stator slots are equal. Specifically, the stator adopts an asymmetric tooth 7 design, in which the ratio of the large tooth width to the small tooth width is 11:5. In order to achieve equal slot fill rates of each stator slot for easy winding, the stator adopts an oblique small tooth 9 method (a method of tilting stator teeth with smaller tooth widths) as shown in FIG. Figure 6 As shown, the magnetic permeance distribution near the air gap side remains unchanged to ensure that the magnetic field modulation effect remains unchanged. At this time, the inclination angle of the small tooth is 31.7° to ensure that the slot area S1 corresponding to each open slot is equal to the slot area S2 corresponding to the adjacent closed slot. The results show that compared with Examples 1 and 2, the ability of the oblique small tooth 9 to suppress the short-circuit current in conjunction with the functional multiplexing unit 5 is relatively poor. At this time, the short-circuit current peak reaches about 5.5 times the rated current (the short-circuit current is reduced by 71.02%), but compared with the traditional vernier permanent magnet motor and the symmetrical tooth structure, its fault tolerance still has obvious advantages.

[0092] Example 4

[0093] This embodiment provides a method for designing a magnetic permeance orientation, and derives the optimal position arrangement of the auxiliary grooves by directional editing of the pole pairs and phase composition of the magnetic permeance harmonics. Specifically, in this embodiment, the position distribution of each auxiliary groove is designed in the following manner:

[0094] S1. Determine whether each harmonic of the motor's armature winding contributes to the motor's back electromotive force and whether the contribution is positive or negative through a motor simulation model, and use the armature winding harmonic that contributes to the back electromotive force as a working harmonic; wherein the motor simulation model is a simulation model of the above-mentioned vernier permanent magnet fault-tolerant motor without auxiliary grooves;

[0095] S2. Based on the magnetic field modulation principle, the pole pairs and phases of the permeance harmonics corresponding to each working harmonic are calculated respectively, and the phase of the permeance harmonic corresponding to the armature winding harmonic with a negative contribution to the back electromotive force is reversed by 180° as the phase of the permeance harmonic;

[0096] For the armature winding harmonics that contribute positive and negative electromotive force, the pole pairs and phase of the corresponding permeance harmonics are calculated based on the magnetic field modulation principle and the pole pairs and initial phase information of the armature winding harmonics; for the armature winding harmonics that contribute negative back electromotive force, the pole pairs of the corresponding permeance harmonics are also calculated, but the required phase is reversed by 180° as the phase of the permeance harmonic. The center axis of the A-phase winding is the initial position 0°, and the relevant parameters of each harmonic of the double-layer winding across two teeth include: harmonic winding coefficient k wv , notch coefficient k sv 、Harmonic phase θ sν , rotation direction, etc.

[0097] In this embodiment, the pole pair numbers of the effective working magnetic field harmonics are determined to be 4, 8, 16, 28, and 32, and the pole pair numbers and phase information of all target permeability harmonics are further derived.

[0098] S3, based on the pole pairs and phases of the permeance harmonics corresponding to each working harmonic, construct a spatial permeance waveform having a mapping relationship with the stator tooth structure;

[0099] S4. Based on the positive and negative information of the spatial magnetic permeability waveform and the stator tooth distribution of the motor simulation model, the optimal position distribution of each auxiliary groove is determined as the final position distribution design result.

[0100] There is a certain mapping relationship between the spatial permeability waveform and the modulation tooth structure, that is, the positive value of the permeability corresponds to the teeth of the modulation unit (that is, the tooth slot distribution structure corresponding to the harmonic modulation effect), and the negative value of the permeability corresponds to the slot of the modulation unit, thereby obtaining the position distribution of each auxiliary groove; wherein, the position distribution includes parameters such as the starting position of each auxiliary groove, the angle range (the arc of the auxiliary groove along the circumferential direction), etc.

[0101] After obtaining the position distribution of the auxiliary grooves, the depth of each auxiliary groove is further optimized, specifically including:

[0102] In the motor simulation model, each auxiliary groove is arranged on the near-air-gap surface of each closed slot according to the obtained position distribution;

[0103] The slot depth of each auxiliary groove in the motor simulation model is adjusted, and the slot depth of each auxiliary groove when the amplitude of the magnetic permeance harmonic corresponding to each working harmonic of the motor is maximized is taken as the final slot depth design result, and finally the following is obtained: Figure 7The structure of the function multiplexing unit 5 is shown. In this embodiment, the curvature and depth of each auxiliary groove are the same.

[0104] It should be noted that the auxiliary groove 6 can have various shapes in the radial cross section, and is not limited to the rectangular shape in the above embodiment, and can also be an arc, a triangle, a trapezoid, etc., which is not limited here. Figure 8 , Fig. 9 and Fig.10 The auxiliary slots 6 are shown as being arc-shaped, triangular or trapezoidal in shape, and their starting position and curvature along the circumferential direction still meet the result of the above-mentioned magnetic permeance orientation design, so as to play a role in improving the harmonic amplitude of the working magnetic field. The present invention includes but is not limited to the auxiliary slot forms of arc-shaped, triangular or trapezoidal shapes, and other auxiliary slot forms that can cooperate with the functional multiplexing unit to optimize the arrangement of the magnetic permeability unit, increase the harmonic content of the working magnetic permeability to improve the motor magnetic field modulation capability are all included in the protection scope of the present invention.

[0105] In this embodiment, there are 16 permanent magnets 3, 12 stator slots, and 6 function multiplexing units 5, and the number of function multiplexing units 5 is half of the number of stator slots. s , permanent magnet pole pair number P r and the number of stator armature winding pole pairs P a There are multiple possibilities that satisfy the following relationship:

[0106]

[0107] Among them, P a =min{iZ s ±P r |, i∈ positive integer set}, min represents the minimum value among all possible values; GCD(Z s ,P a ) is Z s and P a The greatest common divisor of .

[0108] Fig.11 : is a comparison diagram of the short-circuit current between the winding turns of the conventional vernier permanent magnet motor, the motors in Embodiment 1, Embodiment 2 and Embodiment 3 under a short-circuit fault. Fig.11It can be seen that the short-circuit current peak value of the conventional vernier permanent magnet motor is 153.12A, the short-circuit current peak value of the motor in Example 1 is 26.08A, the short-circuit current peak value of the motor in Example 2 is 22.05A, and the short-circuit current peak value of the motor in Example 3 is 44.37A. The short-circuit current peak values ​​of the vernier permanent magnet fault-tolerant motors in Examples 1, 2, or 3 are much smaller than those of the conventional vernier permanent magnet motors, and the motor in Example 2 has the strongest ability to suppress short-circuit current, with the short-circuit current reduced by about 85.60%. It can be seen that the vernier permanent magnet fault-tolerant motor provided in this embodiment has strong fault-tolerant capability.

[0109] It is easy for those skilled in the art to understand that the above is only a preferred embodiment of the present invention. The number of slot-pole combinations in the embodiment of the present invention is not limited to twelve stator slots and sixteen rotor poles. Without departing from the spirit and scope of the present invention, the present invention is not limited to the above embodiment. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A vernier permanent magnet fault-tolerant motor with asymmetric stator teeth, characterized in that: The stator and the rotor are coaxially mounted, and an air gap is provided between the rotor and the stator; The stator comprises: a stator core and an armature winding; the stator core is provided with stator teeth arranged along the circumferential direction; a stator slot is arranged between two adjacent stator teeth; the armature winding is wound in the stator slot; The stator slots include two types: open slots and closed slots; the number of the open slots and the closed slots is equal and they are staggered; the tooth widths of two stator teeth adjacent to the same closed slot are unequal, which are used to guide the magnetic lines of force to follow the ring tooth magnetic circuit under a short-circuit fault condition to increase the slot leakage inductance.

2. The vernier permanent magnet fault-tolerant motor according to claim 1, characterized in that: The stator teeth are parallel teeth; the slot opening angle of the closed slot is The slot opening angle of the opening slot is Among them, Z s is the number of stator slots; k so1 is the slot opening coefficient of the closed slot, and its value is 0.633; k so2 is the slot opening coefficient of the open slot, and its corresponding value range is 0.7~0.

833.

3. The vernier permanent magnet fault-tolerant motor according to claim 2, characterized in that: In two stator teeth adjacent to the same closed slot, a tooth width ratio of the stator tooth with a wider tooth width to the stator tooth with a narrower tooth width ranges from 11:9 to 11:

5.

4. The vernier permanent magnet fault-tolerant motor according to claim 1, characterized in that: The slot area of ​​all stator slots is equal.

5. The vernier permanent magnet fault-tolerant motor according to any one of claims 1 to 4, characterized in that: An arc-shaped iron core is arranged at the slot opening of each closed slot, and an auxiliary groove is arranged on the air gap surface of the closed slot.

6. The vernier permanent magnet fault-tolerant motor according to claim 5, characterized in that: The position distribution of each auxiliary groove is determined by the following method: Determine whether each harmonic of the motor's armature winding contributes to the motor's back electromotive force and whether the contribution is positive or negative through a motor simulation model, and use the armature winding harmonic that contributes to the back electromotive force as a working harmonic; wherein the motor simulation model is a simulation model of the vernier permanent magnet fault-tolerant motor without auxiliary grooves; Based on the magnetic field modulation principle, the pole pairs and phases of the permeance harmonics corresponding to each operating harmonic are calculated respectively, and the phase of the permeance harmonic corresponding to the armature winding harmonic with a negative contribution to the back electromotive force is reversed by 180° as the phase of the permeance harmonic; Based on the pole pairs and phases of the permeance harmonics corresponding to each operating harmonic, a spatial permeance waveform having a mapping relationship with the stator tooth structure is constructed; Based on the positive and negative information of the spatial permeance waveform and the stator tooth distribution of the motor simulation model, the starting position and arc of each auxiliary groove along the circumferential direction are determined as the final position distribution design result.

7. The vernier permanent magnet fault-tolerant motor according to claim 6, characterized in that: The spatial permeability waveform is formed by superimposing the waveforms of each spatial permeability element; the expression of the waveform of the i-th spatial permeability element is: Among them, k wPr and k wv P r The coefficient of the subharmonic winding and the v subharmonic winding coefficient; P r is the number of rotor permanent magnet pole pairs; v is the order of the harmonic of the working armature winding, v = |P r ±P mj |; j is the harmonic order of magnetic permeability; θ mj is the phase value of the jth permeance harmonic, P mj is the number of pole pairs of the jth permeance harmonic, θ si is the position of the i-th spatial magnetic permeance element.

8. The vernier permanent magnet fault-tolerant motor according to claim 6, characterized in that: The depth of each auxiliary groove is determined by: In the motor simulation model, each auxiliary groove is arranged on the near-air-gap surface of each closed slot according to the final position distribution design result; The slot depth dimensions of each auxiliary groove in the motor simulation model are adjusted, and the slot depth dimensions of each auxiliary groove when the amplitude of the magnetic permeance harmonic corresponding to each working harmonic of the motor is maximized are taken as the final slot depth dimension design result.

9. The vernier permanent magnet fault-tolerant motor according to claim 5, characterized in that: The armature winding is a three-phase AC winding, including a double-layer winding coil; the two winding coils in the same closed slot belong to different phases; and the current polarities flowing through them are opposite.

10. The vernier permanent magnet fault-tolerant motor according to claim 9, characterized in that: The coil span of the armature winding is 2.

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