阅读说明：本技术 一种磁场调制式双凸极电机及其凸极齿分布设计方法 (Magnetic field modulation type doubly salient motor and salient pole tooth distribution design method thereof ) 是由 赵文祥 蒋婷婷 徐亮 吉敬华 于 2020-11-30 设计创作，主要内容包括：本发明公开一种磁场调制式双凸极电机及其凸极齿分布设计方法,包括定子和动子,定子包括定子铁心、两套绕组和两套永磁体。每个定子齿分裂成两个励磁齿,每个励磁齿分裂成两个凸极齿。两套绕组分别为电枢绕组和励磁绕组,电枢绕组绕制于定子齿,励磁绕组绕制在由不同定子齿分裂而成的相邻励磁齿。两套沿切向充磁的永磁体分别放置在励磁槽槽口和槽底,放置于同一个槽以及相邻槽相同位置的永磁体极性相反。本发明双凸极的结构设计,使得磁场能够在气隙中调制出丰富的工作谐波,提升电机推力；永磁体磁路仅在定子齿中形成回路,解决了电机易饱和的问题。本发明的凸极齿分布设计方法,通过改变凸极齿分布调整谐波贡献幅值,从而提升电机推力。(The invention discloses a magnetic field modulation type doubly salient motor and a salient pole tooth distribution design method thereof. Each stator tooth is split into two field teeth, and each field tooth is split into two salient pole teeth. The two sets of windings are respectively an armature winding and an excitation winding, the armature winding is wound on the stator teeth, and the excitation winding is wound on the adjacent excitation teeth formed by splitting different stator teeth. Two sets of permanent magnets magnetized in the tangential direction are respectively placed at the notch and the bottom of the excitation slot, and the polarities of the permanent magnets placed in the same slot and the same position of the adjacent slots are opposite. Due to the structural design of the double salient poles, rich working harmonic waves can be modulated in an air gap by a magnetic field, and the thrust of the motor is improved; the permanent magnet magnetic circuit only forms a loop in the stator teeth, and the problem that the motor is easy to saturate is solved. According to the salient pole tooth distribution design method, the harmonic contribution amplitude is adjusted by changing the salient pole tooth distribution, so that the motor thrust is improved.)

1. A magnetic field modulation type doubly salient motor is characterized in that: the stator comprises a stator (1) and a rotor (2), wherein the stator comprises a stator iron core, stator teeth (3), an armature winding (6), an excitation winding (5), permanent magnets (1), (81) and permanent magnets (2), (82); each stator tooth (3) is split into two excitation teeth (4), each excitation tooth (4) is split into two salient pole teeth 1(71) and 2 (72);

the armature winding (6) is wound on the stator teeth (3), and in order to ensure that the central lines of the excitation winding and the armature winding have a half stator tooth pitch difference, the excitation winding (5) is wound on two adjacent excitation teeth (4) formed by splitting different stator teeth;

the permanent magnets 1(81) and 2(82) are tangentially magnetized and are placed in the excitation slot, the permanent magnets 1(81) are placed in the excitation slot, and the permanent magnets 2(82) are embedded in the bottom of the excitation slot; the polarities of the permanent magnets arranged at the same position of the two adjacent grooves are opposite, and the polarities of the permanent magnets in the same groove are also opposite; when the single permanent magnet is excited, the two permanent magnets in the same slot form a closed magnetic circuit in the stator teeth;

the rotor is formed by arranging a plurality of rotor salient poles (9), and the air gap magnetic field contains abundant working waves through bilateral modulation.

2. The field modulated doubly salient machine according to claim 1, wherein the tooth widths of salient pole teeth 1(71) and salient pole teeth 2(72) formed by splitting the same field tooth (4) are independent from each other; the distribution of the salient pole teeth of the stator is optimized, and the amplitude of the working wave at each time is adjusted to improve the thrust of the motor.

3. The magnetic field modulated doubly salient machine of claim 1, wherein: the number of the stator teeth (3) is N_sThe widths of the salient pole teeth 1(71) and 2(72) are respectively beta₁And beta₂The widths of the notches of the armature winding (6) and the excitation winding (5) are respectively beta₃And beta₅The width of an excitation groove formed after the single excitation tooth (4) is split is beta₄The number of the rotor salient poles (9) is N_rEach tooth pitch is tau_pThe relationship of the parameters can be expressed as:

β₁+β₂+β₃+β₄+β₅＝N_rτ_p/N_s。

4. the salient pole tooth distribution design method of the magnetic field modulated doubly salient motor according to claim 3, characterized in that: the total number of salient pole teeth of the stator is 4N_sWherein, the salient pole teeth 1(71) and the salient pole teeth 2(72) are both 2N_sDistribution of salient pole teeth and beta₁、β₂、β₃、β₄And beta₅The design method of salient pole tooth distribution mainly comprises the following steps: summarizing the distribution rule of the salient pole teeth; deducing the order and amplitude of the flux density of the no-load air gap in each case; solving the counter electromotive force through magnetic density, and obtaining the optimal mode of salient pole tooth distribution by comparing the magnitude of the counter electromotive force; the method comprises the following specific steps:

step 1, by beta₁、β₂、β₃、β₄And beta₅For the entry point, the distribution of salient pole teeth is designed, and the distribution of the salient pole teeth can be summarized into the following three Model models by taking a single stator tooth as a reference:

model I, when beta₁、β₂、β₃、β₄And beta₅When the five variables are mutually unequal, each stator tooth has a minimum unit;

model II, when the widths of the excitation winding notch and the armature winding notch are equal and the widths of the salient pole teeth 1(71) and the salient pole teeth 2(72) are equal, namely beta₁≠β₄≠β₃,β₁＝β₂,β₃＝β₅Each stator tooth then has two minimum units;

model III, when the widths of the excitation winding notch, the armature winding notch and the excitation groove are equal and the widths of the salient pole teeth 1(71) and the salient pole teeth 2(72) are equal, namely beta₁≠β₃,β₁＝β₂＝β₄,β₃＝β₅Each stator tooth then has four minimum units;

step 2, the permanent magnets 1(81) and 2(82) only form a closed magnetic circuit in the stator core, and the air gap flux density is generated by the excitation winding, so that the excitation winding only needs to be analyzed, and the air gap magnetomotive force of the excitation winding is as follows:

wherein, F_fwIs the magnetomotive force of the exciting winding, i is positive odd number, theta is the mechanical angle of the rotor, and N_fAnd i_fRespectively the number of turns and exciting current in series connection of each phase;

the rotor flux-guide is:

wherein j is a positive integer, theta is a mechanical angle rotated by the rotor, and theta₀Is the rotor initial position angle, omega is the mechanical angular velocity, Lambda_r0And Λ_rjAre respectively 0 and jN_rThe order permeability coefficient;

since the above formula can only be qualitatively analyzed and cannot be quantitatively solved, in order to quantitatively analyze the rotor magnetismGuide, rotor magnetic conductance Lambda according to motor size parameter_r(θ, t) can be expressed as:

wherein u is₀Delta is the length of the air gap, delta, relative to the air permeability_r(θ, t) is the rotor side air gap length;

wherein m is a positive integer, beta_rIs the width of the rotor slot, R_apIs the air gap radius, t is the corresponding time;

step 3, the distribution of the salient pole teeth influences the tooth form of the stator, so that the magnetic conductance of the stator is changed, and the variable S is used_pMinimum number of elements representing different conditions, stator permeance Λ_s(θ) can be expressed as:

wherein k is a positive integer, and Λ_s0And Λ_skAre respectively 0 and kS_pThe order permeability coefficient;

the same principle as the rotor magnetic conductance, the above formula can be qualitatively analyzed but cannot be quantitatively solved, and for quantitatively analyzing the stator magnetic conductance, according to the size parameter of the motor, the stator magnetic conductance can be expressed as:

wherein n is a positive integer, δ_s(theta) is the rotor-side air gap length, coefficient b_nExpressed as:

from the quantitative expression form of the stator permeance, the harmonic order and the amplitude of the stator permeance are equal to S_pIs related to the value of;

step 4, the motor magnetic conductance is the stator magnetic conductance and the rotor magnetic conductance, namely the synthetic magnetic conductance Λ (theta, t):

the field winding magnetic density B (θ, t) is expressed as:

wherein, Λ₀、Λ_k、Λ_j、Λ_kjRespectively 0-order, k-order, j-order and kj-order permeability coefficients of the stator, F_iIs a coefficient;

the magnetic flux density is composed of five parts, the first two parts are static, the rest parts are rotary, and the orders of the 4 and 5 parts are equal to kS_pIn relation to, and thus, different from S_pThe harmonic composition of the motor magnetic density and the corresponding amplitude are changed;

step 5, the winding function N (θ) is:

wherein v is a positive integer, N_iThe armature windings are connected in series with the turns;

magnetic linkage psi of each phase_p(t) is:

wherein l_aIs the effective axial length of the motor;

the counter potential is:

through the derivation of the formula, the stator magnetic conductance, the flux density, the flux linkage and the back electromotive force under three models can be obtained, and the influence of different distribution of salient pole teeth on the stator magnetic conductance harmonic waves is analyzed from the magnetic conductance model; then, obtaining the difference of the magnetic density order and the amplitude under different conditions according to the obtained magnetic density; then, comparing the sizes of the magnetic chains under different distributions; and finally, obtaining an optimal distribution structure through the obtained counter-electromotive force.

Technical Field

The invention relates to a magnetic field modulation type double salient pole motor and a salient pole tooth distribution design method thereof, and belongs to the field of motors. The motor has the performance advantages of high thrust and wide speed regulation range by adopting the design of a variable magnetic flux hybrid excitation double salient pole structure; the two sets of windings and the two sets of permanent magnets are both arranged on the stator, and the permanent magnet stator can be applied to the fields of aerospace, transportation, wind power generation and the like. .

Background

With the continuous development of the switched reluctance motor, the american academician Lipo professor and the like introduce permanent magnets into the switched reluctance motor and propose a permanent magnet doubly salient motor. Because of the higher price of the permanent magnet material, in order to save the manufacturing cost of the motor, the electro-magnetic doubly salient motor is developed on the basis. The windings of the electric excitation doubly salient motor are all placed on the stator side, and the rotor side is of a simple salient pole structure, so that the temperature management and high-speed operation capacity are good. Compared with a permanent magnet doubly salient motor, the excitation magnetic field of the electrically excited doubly salient motor can be controlled by changing the magnitude of the excitation current, the control is simple, the reliability is high, and the electrically excited doubly salient motor has wide application prospects in the fields of aerospace aviation, traffic transportation, wind power generation and the like.

The Chinese invention patent application number CN201910270245.9 discloses a double-stator electro-magnetic double-salient motor with loss of magnetism and fault tolerance and a method thereof, wherein a set of inner stator winding is added through the structure of double stators, and the motor space is fully utilized; the rotor is provided with a magnetic isolation bridge, main magnetic passes through the outer stator, the rotor and the inner stator to be closed, so that the motor can provide enough reluctance torque when in loss of field fault, and the fault-tolerant operation of the motor is realized. Although the motor has fault-tolerant capability, the permanent magnet is introduced into the electrically excited motor in order to further improve the thrust of the motor due to the electrically excited motor, so that the motor has high thrust density and wide speed range of the permanent magnet motor.

Chinese patent No. CN201010592364.5 discloses two axial excitation doubly salient motors, both of which include at least two doubly salient monomer structures arranged in the axial direction. The first structure forms an axial magnetic circuit through an axial magnetic conduction back iron; the second stator iron core, the stator axial magnetic conduction back iron and the permanent magnet are all arc-shaped structures. The invention has high space utilization rate, no additional air gap and high excitation efficiency. Although the invention effectively saves space and the introduction of the permanent magnet also improves the thrust density and the excitation efficiency of the motor, the complicated structural design also brings difficulty to production and manufacturing.

The Chinese patent application No. CN202010097798.1 discloses a double salient permanent magnet motor with adjustable effective permanent magnet pole number, which changes the magnetization direction of a low coercive force permanent magnet by applying pulse current in an excitation winding and adjusts the pole number of the permanent magnet of the double salient permanent magnet motor, so that the motor has wide magnetic adjustment range and wide area and high efficiency. Although the motor has a wide magnetic field adjusting range and high thrust density, the design difficulty of a control circuit is increased by applying pulse current to an excitation winding, and in addition, the risk of irreversible demagnetization of a permanent magnet caused by overlarge pulse current is also a problem to be faced.

From the current research, for the research of the performance of the doubly salient motor, a complex structural design is generally adopted to improve the fault-tolerant characteristic or the thrust capability of the motor, or the introduced permanent magnet shape and the current of an excitation winding are researched, but the research on the salient pole tooth characteristic of the doubly salient motor is not carried out.

Disclosure of Invention

The invention aims to provide a magnetic field modulation type doubly salient motor and a salient pole tooth distribution design method thereof aiming at the vacancy of the salient pole tooth distribution research of the existing doubly salient motor, and discloses a salient pole tooth distribution design method according to the principle of magnetic field modulation: the distribution mechanism of salient pole teeth is explored, so that the amplitude of working waves is optimized, and the thrust and the magnetic regulation capacity of the motor are improved. In addition, in order to further improve the thrust capability of the motor, the anti-saturation capability of the motor is enhanced through the design of the permanent magnet.

Specifically, the motor of the present invention is realized by adopting the following technical scheme: a magnetic field modulation type doubly salient motor comprises a stator (1) and a rotor (2), wherein the stator comprises a stator iron core, stator teeth (3), an armature winding (6), an excitation winding (5), a permanent magnet 1(81), and a permanent magnet 2 (82); each stator tooth (3) is split into two excitation teeth (4), each excitation tooth (4) is split into two salient pole teeth 1(71) and 2 (72); the armature winding (6) is wound on the stator teeth (3), and in order to ensure that the central lines of the excitation winding and the armature winding have a half stator tooth pitch difference, the excitation winding (5) is wound on two adjacent excitation teeth (4) formed by splitting different stator teeth; the permanent magnets 1(81) and 2(82) are tangentially magnetized and are placed in the excitation slot, the permanent magnets 1(81) are placed in the excitation slot, and the permanent magnets 2(82) are embedded in the bottom of the excitation slot; the polarities of the permanent magnets arranged at the same position of the two adjacent grooves are opposite, and the polarities of the permanent magnets in the same groove are also opposite; when the single permanent magnet is excited, the two permanent magnets in the same slot form a closed magnetic circuit in the stator teeth; the rotor is formed by arranging a plurality of rotor salient poles (9), and the air gap magnetic field contains abundant working waves through bilateral modulation.

Furthermore, the tooth widths of the salient pole teeth 1(71) and the salient pole teeth 2(72) formed by splitting the same excitation tooth (4) are independent and do not influence each other; the distribution of the salient pole teeth of the stator is optimized, and the amplitude of the working wave at each time is adjusted to improve the thrust of the motor.

Further, the number of the stator teeth (3) is N_sThe widths of the salient pole teeth 1(71) and 2(72) are respectively beta₁And beta₂The widths of the notches of the armature winding (6) and the excitation winding (5) are respectively beta₃And beta₅The width of an excitation groove formed after the single excitation tooth (4) is split is beta₄The number of the rotor salient poles (9) is N_rEach tooth pitch is tau_pThe relationship of the parameters can be expressed as:

β₁+β₂+β₃+β₄+β₅＝N_rτ_p/N_s。

the technical scheme of the design method comprises that the total number of salient pole teeth of the stator is 4N_sWherein, the salient pole teeth 1(71) and the salient pole teeth 2(72) are both 2N_sDistribution of salient pole teeth and beta₁、β₂、β₃、β₄And beta₅The design method of salient pole tooth distribution mainly comprises the following steps: summarizing the distribution rule of the salient pole teeth; derivation of the order of the flux density of the no-load air gap in each caseA secondary sum amplitude; solving the counter electromotive force through magnetic density, and obtaining the optimal mode of salient pole tooth distribution by comparing the magnitude of the counter electromotive force; the method comprises the following specific steps:

step 1, by beta₁、β₂、β₃、β₄And beta₅For the entry point, the distribution of salient pole teeth is designed, and the distribution of the salient pole teeth can be summarized into the following three Model models by taking a single stator tooth as a reference:

model I, when beta₁、β₂、β₃、β₄And beta₅When the five variables are mutually unequal, each stator tooth has a minimum unit;

model II, when the widths of the excitation winding notch and the armature winding notch are equal and the widths of the salient pole teeth 1(71) and the salient pole teeth 2(72) are equal, namely beta₁≠β₄≠β₃,β₁＝β₂,β₃＝β₅Each stator tooth then has two minimum units;

model III, when the widths of the excitation winding notch, the armature winding notch and the excitation groove are equal and the widths of the salient pole teeth 1(71) and the salient pole teeth 2(72) are equal, namely beta₁≠β₃,β₁＝β₂＝β₄,β₃＝β₅Each stator tooth then has four minimum units;

step 2, the permanent magnets 1(81) and 2(82) only form a closed magnetic circuit in the stator core, and the air gap flux density is generated by the excitation winding, so that the excitation winding only needs to be analyzed, and the air gap magnetomotive force of the excitation winding is as follows:

wherein, F_fwIs the magnetomotive force of the exciting winding, i is positive odd number, theta is the mechanical angle of the rotor, and N_fAnd i_fRespectively the number of turns and exciting current in series connection of each phase;

the rotor flux-guide is:

wherein j is a positive integer, theta is a mechanical angle rotated by the rotor, and theta₀Is the rotor initial position angle, omega is the mechanical angular velocity, Lambda_r0And Λ_rjAre respectively 0 and jN_rThe order permeability coefficient;

because the formula can only be qualitatively analyzed but cannot be quantitatively solved, in order to quantitatively analyze the rotor magnetic conductance, the rotor magnetic conductance lambada is determined according to the size parameter of the motor_r(θ, t) can be expressed as:

wherein u is₀Delta is the length of the air gap, delta, relative to the air permeability_r(θ, t) is the rotor side air gap length;

wherein m is a positive integer, beta_rIs the width of the rotor slot, R_apIs the air gap radius, t is the corresponding time;

step 3, the distribution of the salient pole teeth influences the tooth form of the stator, so that the magnetic conductance of the stator is changed, and the variable S is used_pMinimum number of elements representing different conditions, stator permeance Λ_s(θ) can be expressed as:

wherein k is a positive integer, and Λ_s0And Λ_skAre respectively 0 and kS_pThe order permeability coefficient;

the same principle as the rotor magnetic conductance, the above formula can be qualitatively analyzed but cannot be quantitatively solved, and for quantitatively analyzing the stator magnetic conductance, according to the size parameter of the motor, the stator magnetic conductance can be expressed as:

wherein n is a positive integer, δ_s(theta) is the rotor-side air gap length, coefficient b_nExpressed as:

from the quantitative expression form of the stator permeance, the harmonic order and the amplitude of the stator permeance are equal to S_pIs related to the value of;

step 4, the motor magnetic conductance is the stator magnetic conductance and the rotor magnetic conductance, namely the synthetic magnetic conductance Λ (theta, t):

the field winding magnetic density B (θ, t) is expressed as:

wherein, Λ₀、Λ_k、Λ_j、Λ_kjRespectively 0-order, k-order, j-order and kj-order permeability coefficients of the stator, F_iIs a coefficient;

the magnetic flux density is composed of five parts, the first two parts are static, the rest parts are rotary, and the orders of the 4 and 5 parts are equal to kS_pIn relation to, and thus, different from S_pThe harmonic composition of the motor magnetic density and the corresponding amplitude are changed;

step 5, the winding function N (θ) is:

wherein v is a positive integer, N_iThe armature windings are connected in series with the turns;

magnetic linkage psi of each phase_p(t) is:

wherein l_aIs the effective axial length of the motor;

the counter potential is:

through the derivation of the formula, the stator magnetic conductance, the flux density, the flux linkage and the back electromotive force under three models can be obtained, and the influence of different distribution of salient pole teeth on the stator magnetic conductance harmonic waves is analyzed from the magnetic conductance model; then, obtaining the difference of the magnetic density order and the amplitude under different conditions according to the obtained magnetic density; then, comparing the sizes of the magnetic chains under different distributions; and finally, obtaining an optimal distribution structure through the obtained counter-electromotive force.

Has the advantages that:

after the design scheme is adopted, the invention has the following beneficial effects:

1. according to the invention, the distribution of the salient pole teeth of the double-sided multi-tooth motor is designed, the distribution rule of the salient pole teeth is summarized, the harmonic amplitude and the size of the air gap flux density are deduced, and the influence of the distribution of the salient pole teeth on the working wave is obtained; and calculating the motor thrust when different salient pole teeth are distributed. Through research on a distribution design method of the salient pole teeth, the amplitude of working harmonic waves is optimized, and the thrust of the motor is improved.

2. The rotor is only of a simple salient pole structure, and for a double-salient pole motor, the simple salient pole structure of the rotor can greatly reduce the manufacturing cost and reduce the processing difficulty;

3. the two sets of windings are placed in different slots of the stator, a double-layer centralized type winding mode is adopted, the length of the end part can be effectively reduced, the copper consumption of the motor is reduced, the windings are placed in different slots, the winding complexity is effectively reduced, the processing manufacturability is improved, the two sets of windings are physically independent, and the fault-tolerant capability of the motor is improved;

4. two sets of windings and two permanent magnets are arranged on the stator, the armature winding is connected with three-phase alternating current, the exciting winding is connected with direct current, and the motor is free of electric brushes and slip rings, so that the running reliability of the motor is effectively improved, and the difficulty of regular maintenance of personnel is reduced;

5. the doubly salient hybrid excitation motor which takes excitation of the excitation winding as the main permanent magnet as the auxiliary permanent magnet has the advantage of wide speed regulation, can be applied to the field of urban rail transit, and is also suitable for linear reciprocating motion occasions such as a numerical control machining lathe and the like;

6. based on the magnetic field modulation principle, the invention designs the doubly salient motor which takes the excitation winding as the main part and the permanent magnet as the auxiliary part, fully exerts the excitation capability and simultaneously reduces the using amount of the permanent magnet as much as possible so as to achieve the optimal cost performance; the number of pole pairs of the armature winding, the number of pole pairs of the exciting winding and the number of salient poles of the rotor are reasonably designed, so that the armature winding can fully absorb harmonic waves of an exciting magnetic field, the motor has multiple working waves, and the thrust of the motor and the magnetic regulation capacity of the exciting winding are improved;

drawings

Fig. 1 is a schematic structural diagram of a magnetic field modulated double salient pole machine according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of the connection of armature windings according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of the connection of the field winding of an embodiment of the present invention;

FIG. 4 is a schematic view of the magnetic field distribution of an embodiment of the present invention in which only permanent magnets act alone;

FIG. 5 shows an embodiment of the present invention based on β₁、β₂、β₃、β₄And beta₅The distribution of salient pole teeth, wherein the minimum unit S is shown in the figure (a)_pWhen the number is 1, the distribution of salient pole teeth is shown schematically; graph (b) is the minimum unit S_pWhen the number is 2, the distribution of salient pole teeth is shown schematically; graph (c) is the minimum unit S_pWhen 4, the distribution of salient pole teeth is schematically shown；

Fig. 6 shows stator flux guide waveforms and harmonic distributions under different salient pole tooth distributions under the action of only the excitation winding alone, where fig. (a) shows the stator flux guide waveforms and fig. (b) shows the harmonic distributions;

FIG. 7 shows the air gap flux density waveform and the harmonic distribution under different salient pole tooth distributions under the action of only the excitation winding alone, where (a) is the air gap harmonic waveform and (b) is the harmonic distribution;

fig. 8 shows flux linkage waveforms and harmonic distributions under different salient pole tooth distributions under the action of only the excitation winding alone, where (a) shows the flux linkage waveforms and (b) shows the flux linkage harmonic distributions;

fig. 9 shows back electromotive force waveforms and harmonic distributions under different salient pole tooth distributions under the action of only the excitation winding alone, where fig. (a) shows the back electromotive force waveforms and fig. (b) shows the back electromotive force harmonic distributions;

FIG. 10 is a graph showing the variation of the thrust of the motor with current when the field winding and the armature winding are operated without permanent magnets according to the embodiment of the present invention;

fig. 11 is a curve showing that permanent magnets are placed in the field winding, the field winding and the armature winding are both active, and the thrust of the motor changes with the current according to the embodiment of the invention.

In the figure: 1. stator, 2, runner, 3, stator tooth, 4, excitation tooth, 5, excitation winding, 6, armature winding, 71, salient pole tooth 1, 72, salient pole tooth 2, 81, permanent magnet 1, 82, permanent magnet 2, 9, runner salient pole.

Detailed Description

In order to make the objects, technical solutions and effects of the present invention more clearly understood, the structural features and advantages of the motor of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

As shown in figure 1, the invention discloses a magnetic field modulation type doubly salient motor and a salient pole tooth distribution design method thereof, and the magnetic field modulation type doubly salient motor comprises a stator (1) and a rotor (2), wherein the stator comprises a stator core, an armature winding (6), an excitation winding (5), a permanent magnet (1) (81) and a permanent magnet (2) (82). Each stator tooth (3) is split into two exciter teeth (4), and each exciter tooth (4) is split into two salient pole teeth (71 and 72). The armature winding (6) is wound on the stator teeth (3), the excitation winding (5) is wound on two adjacent excitation teeth (4) formed by splitting different stator teeth (3), and the connection relationship of the armature winding and the excitation winding is shown in figures 2-3.

The armature winding (6) is wound on the stator teeth (3), and in order to ensure that the central lines of the excitation winding and the armature winding have a half stator tooth pitch difference, the excitation winding (5) is wound on two adjacent excitation teeth (4) formed by splitting different stator teeth.

The permanent magnet excitation device is characterized in that two sets of permanent magnets (81 and 82) are magnetized tangentially, the permanent magnets (81 and 82) are placed in an excitation groove, the permanent magnets 1(81) are placed in an excitation groove opening, and the permanent magnets 2(82) are embedded in the bottom of the excitation groove. The polarities of the permanent magnets placed in the same position of the two adjacent grooves are opposite, and the polarities of the permanent magnets in the same groove are also opposite. When the single permanent magnet is excited, the two permanent magnets in the same slot form a closed magnetic circuit in the stator teeth. Under the condition of high electric load, the permanent magnet can effectively inhibit the motor from being saturated and improve the thrust capacity of the motor.

The motor stator is characterized in that the motor stator is provided with a plurality of salient pole teeth, and two salient pole teeth formed by splitting the same excitation tooth are independent in size; the rotor is only a simple salient pole, and the air-gap magnetic field contains abundant working waves through bilateral modulation. The distribution of the salient pole teeth of the stator is optimized, and the amplitude of the working wave at each time is adjusted, so that the thrust of the motor is improved.

The method is characterized in that: number of stator teeth N_sThe widths of the salient pole teeth 1(71) and 2(72) are respectively beta₁And beta₂The widths of the armature winding and the excitation winding are respectively beta₃And beta₅The width of the excitation groove formed after the splitting of a single excitation tooth is beta₄The number of salient poles of the rotor is N_rEach tooth pitch is tau_p. The relationship of the parameters can be expressed as:

β₁+β₂+β₃+β₄+β₅＝N_rτ_p/N_s

the method is characterized in that: the total number of salient pole teeth is 4N_sWherein the salient pole teeth 1(71) and salient polesTeeth 2 and 72 are all 2N_s. Distribution of salient pole teeth and beta₁、β₂、β₃、β₄And beta₅It is related. The main thought of the design method for the distribution of the salient pole teeth is as follows: summarizing the distribution rule of the salient pole teeth; deducing the order and amplitude of the flux density of the no-load air gap in each case; and solving the counter electromotive force through magnetic density, and obtaining the optimal mode of salient pole tooth distribution by comparing the magnitude of the counter electromotive force. The distribution design method of the salient pole teeth comprises the following specific steps:

step 1, by beta₁、β₂、β₃、β₄And beta₅For the entry point, the distribution of salient pole teeth is designed, and based on a single stator tooth, the distribution of the salient pole teeth can be summarized into the following three conditions:

case 1. when the five variables are mutually unequal, each stator tooth has a minimum unit;

case 2. when the widths of the field winding slots and the armature winding slots are equal and the widths of the salient pole teeth 1 and the salient pole teeth 2 are equal, that is, (β)₁≠β₄≠β₃,β₁＝β₂,β₃＝β₅) Each stator tooth then has two minimum units;

case 3. when the widths of the field winding notches, the armature winding notches and the field grooves are equal and the widths of the salient pole teeth 1 and the salient pole teeth 2 are equal, that is, (β)₁≠β₃,β₁＝β₂＝β₄,β₃＝β₅) Each stator tooth then has four smallest units.

And 2, the permanent magnets 1 and 2 only form a closed magnetic circuit in the stator core, and the air gap flux density is generated by the excitation winding. Only the excitation winding needs to be analyzed. The excitation winding air gap magnetomotive force is as follows:

wherein, F_fwIs the magnetomotive force of the exciting winding, i is positive odd number, theta is the mechanical angle of the rotor, and N_fAnd i_fRespectively, each phase is connected in series with a number of turns andthe excitation current.

The rotor flux-guide is:

wherein j is a positive integer, theta is a mechanical angle rotated by the rotor, and theta₀Is the rotor initial position angle, omega is the mechanical angular velocity, Lambda_r0And Λ_rjAre respectively 0 and jN_rThe order permeance coefficient.

Because the above formula can only be qualitatively analyzed but cannot be quantitatively solved, in order to quantitatively analyze the rotor permeance, the rotor permeance can be expressed as:

wherein, mu₀Is relative air permeance, m is positive integer, beta_rIs the width of the rotor slot, R_apIs the air gap radius.

Step 3, the distribution of the salient pole teeth influences the tooth form of the stator, so that the magnetic conductance of the stator is changed, and the variable S is used_pRepresenting the minimum number of cells for different situations, the stator permeance can be expressed as:

wherein k is a positive integer, and Λ_s0And Λ_skAre respectively 0 and kS_pThe order permeance coefficient.

The above formula, like the rotor permeance, can only be qualitatively analyzed and cannot be quantitatively solved. For quantitative analysis of the stator permeance, the stator permeance can be expressed as:

wherein n is a positive integer,

from the quantitative expression form of the stator permeance, the harmonic order and the amplitude of the stator permeance are equal to S_pIs related to the value of (A).

Step 4, the motor magnetic conductance is synthesized into the magnetic conductance by the stator magnetic conductance and the rotor magnetic conductance:

the flux density of the field winding is expressed as:

wherein, Λ₀、Λ_k、Λ_j、Λ_kjRespectively, the magnetic permeability coefficients are 0 order, k order, j order and kj order of the stator.

The magnetic flux density is composed of five parts, the first two parts are static, the rest parts are rotary, and the orders of the 4 and 5 parts are equal to kS_pIt is related. Thus, different S_pSo that the harmonic composition of the magnetic density of the motor and the corresponding amplitude are changed.

Step 5, the winding function is:

wherein v is a positive integer, N_iThe armature windings are connected in series with a number of turns.

Each phase of magnetic linkage is as follows:

wherein l_aIs the effective axial length of the motor.

The counter potential is:

through the derivation of the formula, the stator magnetic conductance, the flux density, the flux linkage and the back electromotive force under three models can be obtained. Firstly, analyzing the influence of different distribution of salient pole teeth on stator magnetic conductance harmonic waves from a magnetic conductance model; then, obtaining the difference of the magnetic density order and the amplitude under different conditions according to the obtained magnetic density; then, comparing the sizes of the magnetic chains under different distributions; and finally, obtaining an optimal distribution structure through the obtained counter-electromotive force.

Examples of the invention

Fig. 1 is a schematic structural diagram of a doubly salient linear motor according to an embodiment of the present invention. As shown in fig. 1, the motor is a three-phase motor, and includes a stator (1) and a rotor (2), and the stator includes a stator core, an armature winding (6), a field winding (5), a permanent magnet 1(81), and a permanent magnet 2 (82). Each stator tooth (3) is split into two exciter teeth (4), and each exciter tooth (4) is split into two salient pole teeth (71 and 72). The armature winding (6) is wound on the stator teeth (3), and the excitation winding (5) is wound on two adjacent excitation teeth (4) formed by splitting different stator teeth (3). The permanent magnet 1 and the permanent magnet 2 are both placed in the excitation winding groove, the permanent magnet 1 is placed at the notch of the excitation groove, and the permanent magnet 2 is placed at the bottom of the excitation groove. The two permanent magnets are magnetized tangentially, the magnetizing polarities of the permanent magnets 1 and 2 in the same groove are opposite, and a loop is formed in a single stator tooth. The polarities of the permanent magnets arranged at the same positions of the adjacent excitation grooves are opposite, and the permanent magnets in different grooves are mutually independent. Stator teeth N of motor in embodiment_sThe number of the salient pole teeth is 6, 12 salient pole teeth 1 are provided, 12 salient pole teeth 2 are provided, and the number of the salient pole teeth is 24.

Fig. 2 shows the connection relationship of the armature windings, and three-phase alternating current is introduced into the armature windings, and the phase difference between the phases is 120 degrees in electrical angle.

Fig. 3 is a connection relationship of the excitation windings, the excitation windings are connected with direct current, and the positive and negative of the current influence the direction of thrust.

Fig. 4 shows the magnetic field distribution when the permanent magnets are individually energized, and it can be seen that the two permanent magnets in each field winding slot form a closed magnetic circuit within the stator teeth.

FIG. 5 is a graph according to beta₁、β₂、β₃、β₄And beta₅In the relation of (a), the distribution of salient pole teeth, and fig. 5(a) shows that when five variables are not equal to each other (β)₁≠β₂≠β₃≠β₄≠β₅) Each stator tooth has a minimum unit; FIG. 5(b) is a view showing when the widths of the field winding slots and the armature winding slots are equal and the widths of the salient pole teeth 1 and the salient pole teeth 2 are equal, i.e., (. beta.) (B)₁≠β₄≠β₅,β₁＝β₂,β₃＝β₅) Each stator tooth then has two minimum units; FIG. 5(c) shows the case where the widths of the field winding notches, the armature winding notches and the field grooves are equal to each other, and the widths of the salient pole teeth 1 and the salient pole teeth 2 are equal to each other, that is, (β)₁≠β₅,β₁＝β₂＝β₄,β₃＝β₅) Each stator tooth then has four smallest units.

Fig. 6 shows stator permeance waveform and harmonic distribution under three distribution conditions of salient pole teeth. Wherein model I indicates that five variables are mutually different, each stator tooth only has 1 salient pole tooth distribution with minimum units, and the minimum unit number S_pIs 1; model II indicates that the widths of the excitation winding slots and the armature winding slots are equal, the widths of the salient pole teeth 1 and the salient pole teeth 2 are equal, each stator tooth has 2 salient pole tooth distributions with minimum units, and the minimum unit number S_pIs 2; model III indicates that the widths of the excitation winding notch, the armature winding notch and the excitation groove are equal, the widths of the salient pole teeth 1 and the salient pole teeth 2 are equal, each stator tooth is provided with 4 minimum units, and the minimum unit number S_pIs 4. It can be seen from the figure that within 24 th harmonic. Of model IThe harmonics are: 6, 12, 18 and 24 times; the harmonics of model II are: 12 times and 24 times; the harmonics of model III are: 24 times; the harmonic orders of the three models can be expressed as: s_pN_s。

FIG. 7 shows the air gap flux density waveform and harmonic distribution in the case of three types of salient pole teeth. It can be seen from the figure that the harmonic orders of the three models are the same, but there is a difference in magnitude. Wherein, 2, 4, 8, 10, 14, 16 and 22 times are working waves; for convenience of analysis, the working waves with higher harmonic orders and less contribution are ignored. The highest amplitude for the 2 nd harmonic is model I; the 4 th harmonic with the highest amplitude is model II; the 8 th harmonic with the highest amplitude is model III. From the results, the distribution of salient pole teeth has a large influence on the amplitude of the harmonic.

Fig. 8 shows flux linkage waveforms and harmonic distributions in the case of three distributions of salient pole teeth. As can be seen, the fundamental amplitude of model I is at most 0.037Wb, model II is at most 0.036Wb, and the fundamental amplitude of model III is at least 0.028 Wb. model I and model II differed slightly, while model III was 26% lower than model I.

Fig. 9 shows back electromotive force waveforms and harmonic wave distributions in the case of three distributions of salient pole teeth. As can be seen from the figure, the back electromotive force is the same as the flux linkage, and the fundamental wave amplitude of model I is 13.0V at the highest, 12.7V second from model II, and the fundamental wave amplitude of model III is 9.9V at the lowest. Comparison shows that the salient pole teeth distribution mode of model I has the best effect.

Fig. 10 is a curve of thrust of the motor with current when the field winding and the armature winding are operated without the permanent magnet. When the armature winding current is 5A, the excitation winding current is increased from 5A to 20A, and the thrust is increased from 102N to 320N; when the armature winding current is 10A, the excitation winding current is increased from 5A to 20A, and the thrust is from 172N to 553N; when the armature winding current is 15A, the thrust is from 194N to 694N when the field winding current is increased from 5A to 20A; when the armature winding current is 20A, and the field winding current is increased from 5A to 20A, the thrust is from 191N to 736N. From the results, when the armature winding current is 20A and the field current is 5A, the motor is already saturated.

Fig. 11 is a curve of thrust of the motor with the change of current when the permanent magnet is placed in the field winding, the field winding and the armature winding are both active. When the armature winding current is 5A, the thrust is from 106N to 360N when the excitation winding current is increased from 5A to 20A; when the armature winding current is 10A, the thrust is from 180N to 661N when the field winding current is increased from 5A to 20A; when the armature winding current is 15A, the thrust is from 210N to 866N when the field winding current is increased from 5A to 20A; when the armature winding current is 20A, the thrust is from 220N to 952N as the field winding current increases from 5A to 20A. Comparing fig. 10 and 11, it can be seen that the permanent magnet design continues the saturation of the motor, which has a higher thrust capacity.

In summary, the invention discloses a magnetic field modulation type doubly salient motor and a salient pole tooth distribution design method thereof, wherein the motor comprises a stator and a rotor, and the stator comprises a stator core, two sets of windings and two sets of permanent magnets. Each stator tooth is split into two field teeth, and each field tooth is split into two salient pole teeth. The two sets of windings are respectively an armature winding and an excitation winding, the armature winding is wound on the stator teeth, and the excitation winding is wound on the adjacent excitation teeth formed by splitting different stator teeth. Two sets of permanent magnets magnetized in the tangential direction are respectively placed at the notch and the bottom of the excitation slot, and the polarities of the permanent magnets placed in the same slot and the same position of the adjacent slots are opposite. Due to the structural design of the double salient poles, rich working harmonic waves can be modulated in an air gap by a magnetic field, and the thrust of the motor is improved; the permanent magnet magnetic circuit only forms a loop in the stator teeth, and the problem that the motor is easy to saturate is solved. According to the salient pole tooth distribution design method, the salient pole tooth distribution mode is summarized according to the size relation, the magnetic conductance, the flux density, the flux linkage, the back electromotive force and the like of the stator and the rotor are deduced and solved by using a formula in combination with a magnetic field modulation theory, and the harmonic contribution amplitude is adjusted by changing the salient pole tooth distribution, so that the motor thrust is improved. The motor disclosed by the invention is suitable for a linear structure, the design idea is also suitable for a rotary structure, and all excitations of the motor are placed on the stator, so that the motor has a larger application prospect in rail transit needing long stroke and large thrust.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.