阅读说明：本技术 一种双悬浮力无轴承异步电机的矢量控制方法 (Vector control method of double-suspension-force bearingless asynchronous motor ) 是由 丁琪峰 杨泽斌 孙晓东 卢承领 王光鑫 于 2021-08-20 设计创作，主要内容包括：本发明公开了一种双悬浮力无轴承异步电机的矢量控制方法,首先建立了双悬浮力无轴承异步电机的数学模型,包括电机的磁链方程、电压方程、主控悬浮力方程以及辅助悬浮力方程；接着推导了双悬浮力无轴承异步电机的等效转子电阻并优化了主控悬浮力方程；最后采用基于气隙磁场定向的矢量控制方法实现双悬浮力无轴承异步电机的主控悬浮力、辅助悬浮力以及转矩的独立控制。(The invention discloses a vector control method of a double-suspension-force bearingless asynchronous motor, which comprises the steps of firstly establishing a mathematical model of the double-suspension-force bearingless asynchronous motor, wherein the mathematical model comprises a flux linkage equation, a voltage equation, a main control suspension force equation and an auxiliary suspension force equation of the motor; then, the equivalent rotor resistance of the double-suspension bearingless asynchronous motor is deduced, and a master control suspension force equation is optimized; and finally, independently controlling the main control suspension force, the auxiliary suspension force and the torque of the double-suspension-force bearingless asynchronous motor by adopting a vector control method based on air gap magnetic field orientation.)

1. A vector control method of a double-suspension-force bearingless asynchronous motor is characterized by comprising the following steps:

s1, establishing a mathematical model of the bearingless motor based on the double suspension force, wherein the mathematical model comprises a flux linkage equation, a voltage equation and a suspension force equation; the suspension force equation comprises a main control suspension force equation and an auxiliary suspension force equation;

s2, optimizing a main control suspension force equation;

s3, vector control of the double-suspension-force bearingless asynchronous motor;

s4, the decoupling method for rotor magnetic field orientation based on the rotor flux linkage equation, the optimized suspension force equation and the electromagnetic torque equation of the double-suspension bearingless asynchronous motor in S2 and S3 is as follows: will give an electromagnetic torque Te^*Rotor flux linkage psi_1r ^*The components F of the main control suspension force on the x and y axes_2x ^*、F_2y ^*Component F of auxiliary levitation force in x, y axes_3x ^*、F_3y ^*As input, i is calculated according to the equation of electromagnetic torque of the motor_1sqCalculating i according to the rotor flux linkage equation_1sdCalculating i according to the main control suspension force equation_2sdAnd i_2sqCalculating i according to the auxiliary suspension force formula_3sdAnd i_3sq。

2. The vector control method of the double-levitation-force bearingless asynchronous motor according to claim 1, characterized by constructing a two-phase flux linkage equation of the double-levitation-force bearingless asynchronous motor under an alpha coordinate system and a beta coordinate system:

and the rotor flux linkage, the torque winding current, the main control suspension force winding current and the auxiliary suspension force winding current are used as independent variables, and the components of the rotor current of the double-suspension force bearingless asynchronous motor on the alpha axis and the beta axis are reversely solved:

according to i_1rα、i_1rβFurther simplifying the stator flux linkage equation of the double-suspension-force bearingless asynchronous motor:

wherein psi_1sα、ψ_2sα、ψ_3sα、ψ_1rαThe components of the torque winding, the main control suspension force winding, the auxiliary suspension force winding and the rotor winding flux linkage on an alpha axis are respectively; psi_1sβ、ψ_2sβ、ψ_3sβ、ψ_1rβThe components of the torque winding, the main control suspension force winding, the auxiliary suspension force winding and the rotor winding flux linkage on a beta axis are respectively; l is_1s、L_2s、L_3s、L_1rSelf-inductance of a torque winding, a main control suspension force winding, an auxiliary suspension force winding and a rotor winding respectively; m_1s2s、M_1s3s、M_1s1r、M_2s3s、M_2s1r、M_3s1rMutual inductance between a torque winding and a main control suspension force winding, between the torque winding and an auxiliary suspension force winding, between the torque winding and a rotor winding, between the main control suspension force winding and the auxiliary suspension force winding, between the main control suspension force winding and the rotor winding, and between the auxiliary suspension force winding and the rotor winding; i.e. i_1sα、i_2sα、i_3sαAnd i_1rαThe components of the current of the torque winding, the main control suspension force winding, the auxiliary suspension force winding and the rotor winding on an alpha axis respectively; i.e. i_1sβ、i_2sβ、i_3sβAnd i_1rβThe components of the torque winding, the main control suspension force winding, the auxiliary suspension force winding and the rotor winding on the beta axis are respectively.

3. The vector control method of the double-levitation-force bearingless asynchronous motor according to claim 2, characterized by constructing a rotor voltage equation of the double-levitation-force bearingless asynchronous motor on an alpha axis and a beta axis:

wherein u is_rα、u_rβIs the component of the rotor voltage on the alpha and beta axes; r_1rIs the rotor resistance; omega_rIs the rotor angular frequency; t is a time variable; p is a differential operator; i.e. i_rα、i_rβThe components of the rotor current on the alpha and beta axes, respectively.

4. The vector control method of the double-levitation-force bearingless asynchronous motor according to claim 2, characterized by constructing a rotor voltage equation of the double-levitation-force bearingless asynchronous motor on d and q axes:

wherein u is_rd、u_rqThe components of the rotor voltage on d and q axes; psi_1rd、ψ_1rqThe components of the rotor flux linkage on the d and q axes; i.e. i_1sd、i_2sd、i_3sdThe current components of the torque winding, the main control suspension force winding and the auxiliary suspension force winding on d and q axes are shown; ω is the torque winding electrical angular frequency.

5. The vector control method of the double-levitation-force bearingless asynchronous motor according to claim 2, characterized by constructing a levitation force equation of the double-levitation-force bearingless asynchronous motor:

substitution of p₁＝2，p₂＝1，p₃Simplified as 3:

in the formula, F_2mAnd F_3mRespectively a main control suspension force equation and an auxiliary suspension force equation; psi₁Is a torque winding air gap flux linkage;andthe main control suspension force stator current and the auxiliary suspension force stator current are respectively; mu.s₀Is a vacuum magnetic conductivity; l is the effective iron core length of the motor rotor; r is the rotor radius; w₁And W₂The effective turns of each phase of the torque winding and the suspension force winding are respectively connected in series;

according to the dot multiplication and cross multiplication principle of the vector, the main control suspension force of the bearingless asynchronous motor is decomposed to d and q axes:

wherein, F_2x、F_2yThe components of the main control suspension force on the x axis and the y axis are shown; i.e. i_2sdAnd i_2sqThe components of the current of the main control suspension force winding on the x axis and the y axis are obtained; psi_1dAnd psi_1qThe components of the torque winding air gap flux linkage on the x and y axes; k₂Is a constant, expressed as

According to the dot multiplication and cross multiplication principle of the vector, decomposing the auxiliary suspension force of the bearingless asynchronous motor to d and q axes:

wherein, F_3x、F_3yTo assist the components of the levitation force in the x, y axes, K₃Is a constant, expressed as

6. The vector control method of the double-levitation-force bearingless asynchronous motor according to claim 5, wherein the optimization process of the main control levitation force equation is as follows:

s2.1, constructing a BIM voltage balance equation:

wherein the content of the first and second substances,andthe stator voltages of the torque winding and the master levitation force winding,andfor its stator current, Z_1sAnd Z_2sFor the purpose of its stator impedance,andinducing electromotive force, X, for its stator_mFor the purpose of mutual leakage resistance thereof,in order for the rotor to induce an electromotive force,as rotor current, Z_rIs the rotor equivalent impedance; the second term may be further:K_wthe turn ratio of the main control suspension force winding to the torque winding is adopted; j is an imaginary symbol; mu and lambda are initial phase angles of the magnetic fields of the torque winding and the master control suspension force winding respectively;

s2.2, further rewriting the second term in S2.1 as:

in the formula, K_wThe turn ratio of the main control suspension force winding to the torque winding is adopted;

s2.3, in order to enable mutual leakage inductance coefficients of the two sets of windings to be mutually inverse, the current of the suspension force winding is equivalent toThis gives:

wherein, X'_m＝X_m/K_w，Z'_s2＝Z_s2/K_2w；

S2.4, further, converting the rotor winding parameters to the stator winding to construct a rotor voltage balance equation:

wherein rotor induced potential is generated by the superposition of a torque winding and a master control suspension force winding, and rotor current is further simplified as follows:

wherein,And x_rRotor induced electromotive force and rotor leakage reactance s of torque winding and main control suspension force winding when rotor is static₁And s₂The slip ratio of the torque winding and the main control suspension force winding is obtained; r_rIs the rotor resistance;

s2.5, deducing the equivalent resistance R of the master control levitation force winding module according to the S2.4_re：

Get K_w1 and λ μ, further:

s2.6, according to S2.5, simultaneously carrying out torque winding and master control of levitation forceThe wire diameter, the number of turns and the material parameters of the winding are set to be consistent, and an excitation current equation of the main control suspension winding is further constructed

Wherein k is_mIs the excitation current coefficient and is expressed asx_sStator leakage reactance, R, for rotor windings and main control levitation force windings_sIs a stator resistor;

s2.7, optimizing a main control suspension force equation of the double-suspension-force bearingless asynchronous motor according to S2.6, and multiplying the main control suspension force equation by an excitation current coefficient after a traditional mathematical formula to obtain:

wherein psi₁Is stator flux linkage i_2sThe current of the main control suspension force winding; psi_1d、ψ_1qThe components of the stator flux linkage on the d and q axes.

7. The vector control method of the double-levitation-force bearingless asynchronous motor according to claim 6, characterized in that the vector control process of the double-levitation-force bearingless asynchronous motor is as follows:

s3.1, adopting a rotor magnetic field orientation vector control strategy to controlWherein psi_1rIs a rotor flux linkage, and has u due to short circuit inside rotor conducting bar_rd＝u_rqIt is substituted into the rotor voltage equation in S2.1.5 at 0:

s3.2, relation between the torque winding air gap flux linkage and the rotor flux linkage of the bearingless asynchronous motor:

wherein L is_1rσRotor leakage inductance for torque winding, i_1sdAnd i_1sqThe components of the stator current of the torque winding on the d and q axes;

and S3.3, bringing the torque winding air gap flux linkage and the rotor flux linkage in the S3.2 into the main control levitation force calculation formula of the optimized double-levitation-force bearingless asynchronous motor in the S2.7, and constructing a main control levitation force equation based on rotor magnetic field orientation:

s3.3, bringing the torque winding air gap flux linkage and the rotor flux linkage in the S3.2 into an auxiliary levitation force calculation formula of the double-levitation-force bearingless asynchronous motor in the S1.6, and constructing an auxiliary levitation force equation based on rotor magnetic field orientation:

s3.4, further, the process of constructing the electromagnetic torque equation of the bearingless asynchronous motor is as follows: will phi_1rd＝ψ_1r，ψ_1rq0 generation motor torque equation T_eIn (1), obtaining:ψ_1ris the rotor flux linkage.

8. The vector control method of a double-suspension-force bearingless asynchronous motor according to claim 1, wherein the structure of the double-suspension-force bearingless asynchronous motor comprises a rotor and a stator, the rotor comprises a rotating shaft and a rotor core, 28 rotor slots are uniformly arranged on the rotor core along the circumferential direction, and 7 pairs of closed rotor guide bars are embedded in the rotor slots; the stator consists of a stator core and stator windings, 36 stator slots are uniformly formed, 2 layers of windings are embedded in the stator slots, the inner side of each stator slot is provided with a suspension force winding, the outer side of each stator slot is provided with a torque winding, the suspension force winding comprises a main control suspension force winding with 1 pair of poles and an auxiliary suspension force winding with 3 pairs of poles, the main control suspension force winding and the auxiliary suspension force winding are alternately distributed and respectively occupy the inner sides of 18 stator slots.

9. The vector control method of a double-levitation-force bearingless asynchronous motor according to claim 8, wherein 4 rotor slots which are centrosymmetric and have 90 ° adjacent included angles are divided into one group, and are divided into 7 groups, 4 rotor bars are embedded in each group of rotor slots along the axial direction, each rotor bar comprises an axial section and a radial section, the axial section is embedded in the rotor slot and is arranged along the axial direction, and the radial section is used for connecting the tail ends of the axial section. Specifically, on one end face of the rotor core (30), 2 radial sections are utilized to connect the axial sections of the end, and the 2 radial sections are parallel to each other; and the other end surface of the rotor core (30) is connected with the axial section at the other end by utilizing the other 2 radial sections, and the 2 radial sections are parallel to each other, so that a closed loop is formed among the group of rotor conducting bars.

Technical Field

The invention belongs to the technical field of electric transmission control equipment, and particularly relates to a vector control method of a double-suspension-force bearingless asynchronous motor.

Background

With the development of modern industry, the application of the motor is wider and wider, and the requirement is higher and higher. The bearingless motor skillfully embeds a set of suspension force winding on a common motor by utilizing the similarity of the structures of the magnetic bearing and the stator of the motor, and can simultaneously realize stable suspension and frictionless rotation by respectively controlling the currents in the suspension force winding and the torque winding. Compared with a common motor, the bearingless motor has the advantages of no mechanical friction, no abrasion, no need of lubrication and the like, and has wide application prospect in the special electrical fields of aerospace, high-speed hard disks, flywheel energy storage, biomedicine and sterile pollution-free operation.

The bearingless asynchronous motor has the advantages of both the bearingless motor and the asynchronous motor, and the control theory and the control method of the bearingless asynchronous motor are continuously developed and perfected along with the deep research. Because the air gap of the bearingless asynchronous motor is small, the traditional mechanical bearing is abandoned, and any external interference can cause the motor to sweep the chamber, which can cause accidents in serious cases. Therefore, how to reduce the buffeting of the motor rotor and improve the suspension control precision is the most basic problem of the research and development of the bearingless asynchronous motor.

At present, various solution realization methods are proposed for independent control of the suspension force and the torque of the bearingless asynchronous motor. Chinese patent application No. CN201811125660.7, entitled: the independent inverse decoupling control system of the bearingless asynchronous motor can realize dynamic decoupling control of the bearingless asynchronous motor, simplify the complexity of a system model, avoid the dependence of an inverse model of a magnetic suspension system on a torque system magnetic field orientation mode, and is particularly suitable for high-speed motor driving application occasions with higher requirements on dynamic control performance. Chinese patent application No. CN201510104159.2, entitled: a stator flux linkage directional inverse decoupling control system of a bearingless asynchronous motor enables the system to be decoupled into four linear subsystems before a stator flux linkage directional original system: the system comprises a first-order rotating speed subsystem, a first-order stator flux linkage subsystem and two radial displacement second-order subsystems of alpha and beta, wherein the four linear subsystems are respectively and correspondingly connected with four regulators, and the four regulators are respectively connected with a stator flux linkage directional inverse system to form a closed-loop control system. The two decoupling methods both depend on the accurate mathematical model of the motor, and the parameters of the motor can change continuously in the actual operation, which directly influences the control accuracy of the methods. Meanwhile, the method is researched based on a single-suspension-force bearingless asynchronous motor, the current is decomposed to d and q axes, the magnitude and the direction of the suspension force of the motor are controlled only by changing the currents of the d and q axes, and the interference of external factors of the motor is easy to occur.

Disclosure of Invention

In order to solve the defects in the prior art, the invention aims at a vector control method of a double-suspension-force bearingless asynchronous motor.

The technical scheme adopted by the invention is as follows:

a vector control method of a double-suspension-force bearingless asynchronous motor comprises the following steps:

s1, establishing a mathematical model of the bearingless motor based on the double suspension force, wherein the mathematical model comprises a flux linkage equation, a voltage equation and a suspension force equation; the suspension force equation comprises a main control suspension force equation and an auxiliary suspension force equation;

s2, optimizing a main control suspension force equation;

s3, vector control of the double-suspension-force bearingless asynchronous motor;

s4, the decoupling method for rotor magnetic field orientation based on the rotor flux linkage equation, the optimized suspension force equation and the electromagnetic torque equation of the double-suspension bearingless asynchronous motor in S2 and S3 is as follows: will give an electromagnetic torque Te^*Rotor flux linkage psi_1r ^*The components F of the main control suspension force on the x and y axes_2x ^*、F_2y ^*Component F of auxiliary levitation force in x, y axes_3x ^*、F_3y ^*As input, i is calculated according to the equation of electromagnetic torque of the motor_1sqCalculating i according to the rotor flux linkage equation_1sdAccording to the master control suspension force equationCalculate i_2sdAnd i_2sqCalculating i according to the auxiliary suspension force formula_3sdAnd i_3sq。

Further, a two-phase flux linkage equation of the double-suspension-force bearingless asynchronous motor under an alpha coordinate system and a beta coordinate system is constructed:

and the rotor flux linkage, the torque winding current, the main control suspension force winding current and the auxiliary suspension force winding current are used as independent variables, and the components of the rotor current of the double-suspension force bearingless asynchronous motor on the alpha axis and the beta axis are reversely solved:

according to i_1rα、i_1rβFurther simplifying the stator flux linkage equation of the double-suspension-force bearingless asynchronous motor:

wherein psi_1sα、ψ_2sα、ψ_3sα、ψ_1rαThe components of the torque winding, the main control suspension force winding, the auxiliary suspension force winding and the rotor winding flux linkage on an alpha axis are respectively; psi_1sβ、ψ_2sβ、ψ_3sβ、ψ_1rβThe components of the torque winding, the main control suspension force winding, the auxiliary suspension force winding and the rotor winding flux linkage on a beta axis are respectively; l is_1s、L_2s、L_3s、L_1rSelf-inductance of a torque winding, a main control suspension force winding, an auxiliary suspension force winding and a rotor winding respectively; m_1s2s、M_1s3s、M_1s1r、M_2s3s、M_2s1r、M_3s1rThe mutual inductance between the torque winding and the main control suspension force winding, the torque winding and the auxiliary suspension force winding, the torque winding and the rotor winding, the main control suspension force winding and the auxiliary suspension force winding, the main control suspension force winding and the rotor winding, and the auxiliary suspension force winding and the rotor winding. i.e. i_1sα、i_2sα、i_3sαAnd i_1rαThe components of the current of the torque winding, the main control suspension force winding, the auxiliary suspension force winding and the rotor winding on an alpha axis respectively; i.e. i_1sβ、i_2sβ、i_3sβAnd i_1rβThe components of the torque winding, the main control suspension force winding, the auxiliary suspension force winding and the rotor winding on the beta axis are respectively.

Further, a rotor voltage equation of the double-suspension-force bearingless asynchronous motor on the alpha shaft and the beta shaft is constructed:

wherein u is_rα、u_rβIs the component of the rotor voltage on the alpha and beta axes; r_1rIs the rotor resistance; omega_rIs the rotor angular frequency; t is a time variable; p is a differential operator; i.e. i_rα、i_rβThe components of the rotor current on the α and β axes, respectively;

further, a rotor voltage equation of the double-suspension-force bearingless asynchronous motor on d and q axes is constructed:

wherein u is_rd、u_rqThe components of the rotor voltage on d and q axes; psi_1rd、ψ_1rqThe components of the rotor flux linkage on the d and q axes; i.e. i_1sd、i_2sd、i_3sdThe current components of the torque winding, the main control suspension force winding and the auxiliary suspension force winding on d and q axes are shown; ω is the torque winding electrical angular frequency.

Further, constructing a suspension force equation of the double-suspension-force bearingless asynchronous motor:

substitution of p₁＝2，p₂＝1，p₃Simplified as 3:

in the formula, F_2mAnd F_3mRespectively a main control suspension force equation and an auxiliary suspension force equation; psi₁Is a torque winding air gap flux linkage;andthe main control suspension force stator current and the auxiliary suspension force stator current are respectively; mu.s₀Is a vacuum magnetic conductivity; l is the effective iron core length of the motor rotor; r is the rotor radius; w₁And W₂The effective turns of each phase of the torque winding and the suspension force winding are respectively connected in series;

according to the dot multiplication and cross multiplication principle of the vector, the main control suspension force of the bearingless asynchronous motor is decomposed to d and q axes:

wherein, F_2x、F_2yThe components of the main control suspension force on the x axis and the y axis are shown; i.e. i_2sdAnd i_2sqThe components of the current of the main control suspension force winding on the x axis and the y axis are obtained; psi_1dAnd psi_1qThe components of the torque winding air gap flux linkage on the x and y axes; k₂Is a constant, expressed as

According to the dot multiplication and cross multiplication principle of the vector, decomposing the auxiliary suspension force of the bearingless asynchronous motor to d and q axes:

wherein, F_3x、F_3yTo assist the components of the levitation force in the x, y axes, K₃Is a constant, expressed as

Further, the optimization process of the main control suspension force equation is as follows:

s2.1, constructing a BIM voltage balance equation:

wherein the content of the first and second substances,andthe stator voltages of the torque winding and the master levitation force winding,andfor its stator current, Z_1sAnd Z_2sFor the purpose of its stator impedance,andinducing electromotive force, X, for its stator_mFor the purpose of mutual leakage resistance thereof,in order for the rotor to induce an electromotive force,as rotor current, Z_rIs the rotor equivalent impedance. The second term may be further:K_wthe turn ratio of the main control suspension force winding to the torque winding is adopted; j is an imaginary symbol; mu and lambda are initial phase angles of the magnetic fields of the torque winding and the main control levitation force winding respectively.

S2.2, further rewriting the second term in S2.1 as:

in the formula, K_wThe turn ratio of the main control suspension force winding and the torque winding is adopted.

S2.3, in order to enable mutual leakage inductance coefficients of the two sets of windings to be mutually inverse, the current of the suspension force winding is equivalent toThis gives:

wherein, X'_m＝X_m/K_w，Z'_s2＝Z_s2/K_2w。

S2.4, further, converting the rotor winding parameters to the stator winding to construct a rotor voltage balance equation:

wherein rotor induced potential is generated by the superposition of a torque winding and a master control suspension force winding, and rotor current is further simplified as follows:

wherein,And x_rRotor induced electromotive force and rotor leakage reactance s of torque winding and main control suspension force winding when rotor is static₁And s₂The slip ratios of the torque winding and the main control suspension force winding are shown. R_rIs the rotor resistance.

S2.5, deducing the equivalent resistance R of the master control levitation force winding module according to the S2.4_re：

Get K_w1 and λ μ, further:

s2.6, according to S2.5, the wire diameters, the number of turns and material parameters of the torque winding and the main control suspension force winding are set to be consistent, and an excitation current equation of the main control suspension winding is further constructed

Wherein k is_mIs the excitation current coefficient and is expressed asx_sStator leakage reactance, R, for rotor windings and main control levitation force windings_sIs the stator resistance.

S2.7, optimizing a main control suspension force equation of the double-suspension-force bearingless asynchronous motor according to S2.6, and multiplying the main control suspension force equation by an excitation current coefficient after a traditional mathematical formula to obtain:

wherein psi₁Is stator flux linkage i_2sThe current of the main control suspension force winding; psi_1d、ψ_1qThe components of the stator flux linkage on the d and q axes.

Further, the vector control process of the double-suspension-force bearingless asynchronous motor is as follows:

s3.1, adopting a rotor magnetic field orientation vector control strategy to controlWherein psi_1rIs a rotor flux linkage, and has u due to short circuit inside rotor conducting bar_rd＝u_rqIt is substituted into the rotor voltage equation in S2.1.5 at 0:

s3.2, relation between the torque winding air gap flux linkage and the rotor flux linkage of the bearingless asynchronous motor:

wherein L is_1rσRotor leakage inductance for torque winding, i_1sdAnd i_1sqThe components of the torque winding stator current on the d and q axes.

And S3.3, bringing the torque winding air gap flux linkage and the rotor flux linkage in the S3.2 into the main control levitation force calculation formula of the optimized double-levitation-force bearingless asynchronous motor in the S2.7, and constructing a main control levitation force equation based on rotor magnetic field orientation:

s3.3, bringing the torque winding air gap flux linkage and the rotor flux linkage in the S3.2 into an auxiliary levitation force calculation formula of the double-levitation-force bearingless asynchronous motor in the S1.6, and constructing an auxiliary levitation force equation based on rotor magnetic field orientation:

s3.4, further, the process of constructing the electromagnetic torque equation of the bearingless asynchronous motor is as follows: will phi_1rd＝ψ_1r，ψ_1rq0 generation motor torque equation T_eIn (1), obtaining:ψ_1ris the rotor flux linkage.

Furthermore, the structure of the double-suspension-force bearingless asynchronous motor comprises a rotor and a stator, wherein the rotor consists of a rotating shaft and a rotor iron core, 28 rotor slots are uniformly arranged on the rotor iron core along the circumferential direction, and 7 pairs of closed rotor guide bars are embedded in the rotor slots; the stator consists of a stator core and stator windings, 36 stator slots are uniformly formed, 2 layers of windings are embedded in the stator slots, the inner side of each stator slot is provided with a suspension force winding, the outer side of each stator slot is provided with a torque winding, the suspension force winding comprises a main control suspension force winding with 1 pair of poles and an auxiliary suspension force winding with 3 pairs of poles, the main control suspension force winding and the auxiliary suspension force winding are alternately distributed and respectively occupy the inner sides of 18 stator slots.

Further, divide into a set of 4 rotor grooves that central symmetry and adjacent contained angle are 90, divide into 7 groups altogether, and every rotor inslot of group imbeds 4 rotor conducting bars along the axial, and the rotor conducting bar includes axial section and radial section, the axial section imbeds rotor inslot portion and arranges along the axial, radial section is used for connecting the end of axial section. Specifically, on one end face of a rotor core, 2 radial sections are used for connecting axial sections of the end, and the 2 radial sections are parallel to each other; and the other end surface of the rotor core is connected with the axial section at the other end by using the other 2 radial sections, and the 2 radial sections are parallel to each other, so that a closed loop is formed among the group of rotor conducting bars.

Advantageous effects

The vector control method of the double-levitation-force bearingless asynchronous motor aims at the double-levitation-force bearingless asynchronous motor, and independent control of main levitation force, auxiliary levitation force and torque is achieved. The control method is simple, the decoupling variables are few, the operation is easy, and the suspension force control precision of the motor can be effectively improved.

Drawings

FIG. 1 is a decoupling algorithm of a double-suspension bearingless asynchronous motor based on rotor magnetic field orientation.

Fig. 2 is a schematic view of the structure of the motor of the present invention.

Fig. 3 shows the connection of the bars in the rotor slots 1, 4, 8, 11, 15, 18, 22, 25 according to the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

As shown in fig. 2 and 3, the double-suspension bearingless asynchronous motor comprises a motor rotating shaft 29, a rotor core 30 and a stator core 31 in sequence from inside to outside along the radial direction.

The rotor core 30 is sleeved on the motor rotating shaft 29 and rotates synchronously with the motor rotating shaft 29 during operation. The rotor core 30 is formed by laminating silicon steel sheets with the model number of DW465-50, 28 rotor slots are uniformly arranged along the circumferential direction, and the rotor slots are arranged along the axial direction of the rotor core 30; for convenience of description, the 28 rotor slots are respectively represented by 1 to 28.

Along clockwise, with central symmetry and adjacent contained angle be 4 rotor grooves of 90 and divide into a set, divide into 7 groups altogether, 4 rotor conducting bars of each group rotor inslot along axial embedding, the rotor conducting bar is made by the aluminum alloy. The rotor bar includes an axial section and a radial section, the axial section is embedded inside the rotor groove and arranged along the axial direction, and the radial section is used for connecting the tail end of the axial section. Specifically, at one end face of rotor core 30, 2 radial segments are used to connect the axial segments of the end, and the 2 radial segments are parallel to each other; on the other end face of the rotor core 30, the other 2 radial segments are used to connect the axial segment at the other end, and the 2 radial segments are parallel to each other, so that a closed loop is formed between the group of rotor conducting bars.

The stator core 31 is formed by laminating silicon steel sheets with the model number DW465-50, and 36 stator slots are uniformly arranged along the circumferential direction of the stator core 31. Dividing the stator slot into an inner layer and an outer layer along the radial direction, wherein the inner layer is close to the stator core 31; the inner layer is provided with a suspension force winding and the outer layer is provided with a torque winding 34.

The suspension force winding comprises 1 set of 1 antipodal main control suspension force winding 32 and 1 set of 3 antipodal auxiliary suspension force winding 33, and the main control suspension force winding 32 and the auxiliary suspension force winding 33 are sequentially and alternately embedded in the inner side of the stator slot at intervals and respectively occupy 18 stator slots.

The torque winding 34 is 1 set of 2 antipodal windings occupying 36 stator slots.

The main control suspension force winding 32, the auxiliary suspension force winding 33 and the torque winding 34 are distributed in a centralized mode, and the winding is formed by winding an electromagnetic coil with good electric conduction and then dipping paint and drying.

The rotation principle is as follows: rated current is supplied to the torque winding 34, and a 2-pair pole rotating magnetic field is generated outside the stator. The axial conducting bars in the rotor grooves relatively cut the rotating magnetic field, induced current is generated in the closed rotor conducting bars, the induced current of the rotor generates Lorentz force in the rotating magnetic field, and then electromagnetic torque acting on the rotor conducting bars is generated, and the motor rotor is driven to rotate.

The suspension principle is as follows: the current is introduced into the main control suspension force winding 32, the inner side of the stator generates a 1-pair pole rotating magnetic field, the difference between the 1-pair pole rotating magnetic field and the outer 2-pair pole magnetic field meets the relation that the difference between the pole pair number is 1, the two magnetic fields interact to generate Maxwell unbalanced magnetic pulling force, the current of the main control suspension force winding is decomposed to d and q axes according to the vector dot-product-cross multiplication principle, and the suspension of the motor is realized by changing the currents of the d and q axes. Current is introduced into the auxiliary suspension force winding 33, 3 pairs of pole rotating magnetic fields are generated on the inner side of the stator and meet the relation that the difference of the pole pair number is 1 with 2 pairs of pole magnetic fields on the outer side, the two magnetic fields interact to generate another Maxwell unbalanced magnetic pulling force, the current of the auxiliary suspension force winding 33 is decomposed to d and q axes, the suspension force of the motor is further controlled by controlling the currents of the d and q axes, and therefore the suspension control precision of the motor is improved. Because the main control suspension force winding and the auxiliary suspension force winding do not meet the relation that the difference of the pole pair number is 1, the Maxwell magnetic pull force cannot be generated under the action of the main control suspension force winding and the auxiliary suspension force winding. The three sets of winding magnetic fields are easy to decouple, 4 forces can be provided by synchronous control of the three sets of winding magnetic fields, and the suspension precision of the bearingless asynchronous motor is improved.

For the double-levitation-force bearingless asynchronous motor, as shown in fig. 1, the present application also provides a vector control strategy for the double-levitation-force bearingless asynchronous motor, which includes the following steps;

s1, establishing a mathematical model of the double-suspension-force bearingless motor based on the double-suspension-force bearingless motor, wherein the mathematical model comprises a flux linkage equation, a voltage equation and a suspension force equation, and the specific process is as follows:

s1.1, constructing a two-phase flux linkage equation of the double-suspension-force bearingless asynchronous motor under an alpha and beta coordinate system:

wherein psi_1sα、ψ_2sα、ψ_3sα、ψ_1rαThe components of the torque winding, the main control suspension force winding, the auxiliary suspension force winding and the rotor winding flux linkage on an alpha axis are respectively; psi_1sβ、ψ_2sβ、ψ_3sβ、ψ_1rβThe components of the torque winding, the main control suspension force winding, the auxiliary suspension force winding and the rotor winding flux linkage on a beta axis are respectively; l is_1s、L_2s、L_3s、L_1rSelf-inductance of a torque winding, a main control suspension force winding, an auxiliary suspension force winding and a rotor winding respectively; m_1s2s、M_1s3s、M_1s1r、M_2s3s、M_2s1r、M_3s1rThe mutual inductance between the torque winding and the main control suspension force winding, the torque winding and the auxiliary suspension force winding, the torque winding and the rotor winding, the main control suspension force winding and the auxiliary suspension force winding, the main control suspension force winding and the rotor winding, and the auxiliary suspension force winding and the rotor winding. i.e. i_1sα、i_2sα、i_3sαAnd i_1rαThe components of the current of the torque winding, the main control suspension force winding, the auxiliary suspension force winding and the rotor winding on an alpha axis respectively; i.e. i_1sβ、i_2sβ、i_3sβAnd i_1rβThe components of the torque winding, the main control suspension force winding, the auxiliary suspension force winding and the rotor winding on the beta axis are respectively.

S1.2, reversely solving the components of the rotor current of the double-suspension-force bearingless asynchronous motor on the alpha axis and the beta axis by taking the rotor flux linkage, the torque winding current, the main control suspension force winding current and the auxiliary suspension force winding current as independent variables according to the S1.1:

s1.3, further simplifying a stator flux linkage equation of the double-suspension-force bearingless asynchronous motor in the S1.1 according to the S1.2:

s1.4, constructing a rotor voltage equation of the double-suspension-force bearingless asynchronous motor on an alpha shaft and a beta shaft according to the S1.2:

wherein u is_rα、u_rβIs the component of the rotor voltage on the alpha and beta axes; r_1rIs the rotor resistance; omega_rIs the rotor angular frequency; t is a time variable; p is microDividing operators; i.e. i_rα、i_rβThe components of the rotor current on the alpha and beta axes, respectively.

S1.5, further constructing a rotor voltage equation of the double-suspension-force bearingless asynchronous motor on d and q axes according to the S1.4:

wherein u is_rd、u_rqThe components of the rotor voltage on d and q axes; psi_1rd、ψ_1rqThe components of the rotor flux linkage on the d and q axes; i.e. i_1sd、i_2sd、i_3sdThe current components of the torque winding, the main control suspension force winding and the auxiliary suspension force winding on d and q axes are shown; ω is the torque winding electrical angular frequency.

S1.6, constructing a suspension force equation of the double-suspension-force bearingless asynchronous motor:

substitution of p₁＝2，p₂＝1，p₃Simplified as 3:

in the formula, F_2mAnd F_3mRespectively a main control suspension force equation and an auxiliary suspension force equation; psi₁Is a torque winding air gap flux linkage;andthe main control suspension force stator current and the auxiliary suspension force stator current are respectively; mu.s₀Is a vacuum magnetic conductivity; l is the effective iron core length of the motor rotor; r is the rotor radius; w₁And W₂The effective turns of each phase of the torque winding and the suspension force winding are respectively connected in series.

S1.7, decomposing the main control suspension force of the bearingless asynchronous motor to d and q axes according to the dot multiplication and cross multiplication principle of the vector:

wherein, F_2x、F_2yThe components of the main control suspension force on the x axis and the y axis are shown; i.e. i_2sdAnd i_2sqThe components of the current of the main control suspension force winding on the x axis and the y axis are obtained; psi_1dAnd psi_1qThe components of the torque winding air gap flux linkage on the x and y axes; k₂Is a constant, expressed asConstant p₁＝2，p₂＝1。

S1.8, decomposing the auxiliary suspension force of the bearingless asynchronous motor to d and q axes according to the dot multiplication and cross multiplication principle of the vector:

wherein, F_3x、F_3yTo assist the components of the levitation force in the x, y axes, K₃Is a constant, expressed as

S2, the optimization process of the main control suspension force equation is as follows:

s2.1, constructing a BIM voltage balance equation:

wherein the content of the first and second substances,andthe stator voltages of the torque winding and the master levitation force winding,andfor its stator current, Z_1sAnd Z_2sFor the purpose of its stator impedance,andinducing electromotive force, X, for its stator_mFor the purpose of mutual leakage resistance thereof,in order for the rotor to induce an electromotive force,as rotor current, Z_rIs the rotor equivalent impedance. The second term may be further:K_wthe turn ratio of the main control suspension force winding to the torque winding is adopted; j is an imaginary symbol; mu and lambda are initial phase angles of the magnetic fields of the torque winding and the main control levitation force winding respectively.

S2.2, further rewriting the second term in S2.1 as:

in the formula, K_wThe turn ratio of the main control suspension force winding and the torque winding is adopted.

S2.3, in order to enable mutual leakage inductance coefficients of the two sets of windings to be mutually inverse, the current of the suspension force winding is equivalent toThis gives:

wherein, X'_m＝X_m/K_w，Z'_s2＝Z_s2/K_2w。

S2.4, further, converting the rotor winding parameters to the stator winding to construct a rotor voltage balance equation:

wherein rotor induced potential is generated by the superposition of a torque winding and a master control suspension force winding, and rotor current is further simplified as follows:

wherein,And x_rRotor induced electromotive force and rotor leakage reactance s of torque winding and main control suspension force winding when rotor is static₁And s₂The slip ratios of the torque winding and the main control suspension force winding are shown. R_rIs the rotor resistance.

S2.5, deducing the equivalent resistance R of the master control levitation force winding module according to the S2.4_re：

Get K_w1 and λ μ, further:

s2.6, according to S2.5, the wire diameters, the number of turns and material parameters of the torque winding and the main control suspension force winding are set to be consistent, and an excitation current equation of the main control suspension winding is further constructed

Wherein k is_mIs the excitation current coefficient and is expressed asx_sStator leakage reactance, R, for rotor windings and main control levitation force windings_sIs the stator resistance.

S2.7, optimizing a main control suspension force equation of the double-suspension-force bearingless asynchronous motor according to S2.6, and multiplying the main control suspension force equation by an excitation current coefficient after a traditional mathematical formula to obtain:

wherein psi₁Is stator flux linkage i_2sThe current of the main control suspension force winding; psi_1d、ψ_1qThe components of the stator flux linkage on the d and q axes.

S3, the vector control process of the double-suspension-force bearingless asynchronous motor is as follows:

s3.1, adopting a rotor magnetic field orientation vector control strategy to controlWherein psi_1rIs a rotor flux linkage, and has u due to short circuit inside rotor conducting bar_rd＝u_rqIt is substituted into the rotor voltage equation in S2.1.5 at 0:

s3.2, relation between the torque winding air gap flux linkage and the rotor flux linkage of the bearingless asynchronous motor:

wherein L is_1rσRotor leakage inductance for torque winding, i_1sdAnd i_1sqThe components of the torque winding stator current on the d and q axes.

And S3.3, bringing the torque winding air gap flux linkage and the rotor flux linkage in the S3.2 into the main control levitation force calculation formula of the optimized double-levitation-force bearingless asynchronous motor in the S2.7, and constructing a main control levitation force equation based on rotor magnetic field orientation:

s3.3, bringing the torque winding air gap flux linkage and the rotor flux linkage in the S3.2 into an auxiliary levitation force calculation formula of the double-levitation-force bearingless asynchronous motor in the S1.6, and constructing an auxiliary levitation force equation based on rotor magnetic field orientation:

s3.4, further, the process of constructing the electromagnetic torque equation of the bearingless asynchronous motor is as follows: will phi_1rd＝ψ_1r，ψ_1rq0 generation motor torque equation T_eIn (1), obtaining:ψ_1ris the rotor flux linkage.

S4, as shown in figure 1, the decoupling method for rotor magnetic field orientation based on the rotor flux linkage equation, the optimized suspension force equation and the electromagnetic torque equation of the double-suspension-force bearingless asynchronous motor in S2 and S3 is as follows: will give an electromagnetic torque Te^*Rotor flux linkage psi_1r ^*The components F of the main control suspension force on the x and y axes_2x ^*、F_2y ^*Component F of auxiliary levitation force in x, y axes_3x ^*、F_3y ^*As input, a motor based onMagnetic torque equation calculates i_1sqCalculating i according to the rotor flux linkage equation_1sdCalculating i according to the main control suspension force equation_2sdAnd i_2sqCalculating i according to the auxiliary suspension force formula_3sdAnd i_3sq。

The above embodiments are only used for illustrating the design idea and features of the present invention, and the purpose of the present invention is to enable those skilled in the art to understand the content of the present invention and implement the present invention accordingly, and the protection scope of the present invention is not limited to the above embodiments. Therefore, all equivalent changes and modifications made in accordance with the principles and concepts disclosed herein are intended to be included within the scope of the present invention.