阅读说明：本技术 不等长分段供电直线感应电机控制方法及系统 (Method and system for controlling linear induction motor with unequal length segmented power supply ) 是由 徐飞 李耀华 史黎明 李子欣 于 2021-07-27 设计创作，主要内容包括：本发明属于电机控制技术领域,具体涉及了一种不等长分段供电直线感应电机控制方法及系统,旨在解决现有技术无法实现不等长分段供电直线感应电机参数变化特征分析和控制的问题。本发明包括：构建定子和动子数学模型的等效电路,并建立子数学模型和动子数学模型；由动子位置计算各定子段覆盖动子的占比、定子段和动子长度系数；构建电机在稳态工况下的电压和磁链状态方程,并获取不等长直线感应电机定子段控制的前馈电压,采用PI控制器实现电流的反馈闭环控制,将前馈电压和反馈输出相加,并经ipark变换得到三相坐标系的参考电压,完成不等长分段供电直线感应电机的推力闭环控制。本发明实现了不等长分段供电直线感应电机的精确、平稳控制。(The invention belongs to the technical field of motor control, particularly relates to a method and a system for controlling a linear induction motor with unequal length sectional power supply, and aims to solve the problem that parameter change characteristic analysis and control of the linear induction motor with unequal length sectional power supply cannot be realized in the prior art. The invention comprises the following steps: constructing an equivalent circuit of a stator mathematical model and a rotor mathematical model, and establishing a rotor mathematical model and a rotor mathematical model; calculating the ratio of each stator segment covering the rotor, the stator segment and the rotor length coefficient according to the rotor position; the method comprises the steps of constructing a voltage and flux linkage state equation of a motor under a steady-state working condition, obtaining feedforward voltage controlled by stator segments of the unequal length linear induction motor, realizing feedback closed-loop control of current by adopting a PI (proportional integral) controller, adding the feedforward voltage and feedback output, obtaining reference voltage of a three-phase coordinate system through ipark transformation, and completing thrust closed-loop control of the unequal length segmented power supply linear induction motor. The invention realizes the accurate and stable control of the unequal length sectional power supply linear induction motor.)

1. A control method for a linear induction motor with unequal length and segmented power supply is characterized by comprising the following steps:

step S10, constructing an equivalent circuit of a stator mathematical model and an equivalent circuit of a rotor mathematical model according to the actual structure of the unequal length sectional power supply linear induction motor;

step S20, constructing a stator mathematical model of the unequal length segmented power supply linear induction motor based on the equivalent circuit of the stator mathematical model; constructing a rotor mathematical model of the unequal length segmented power supply linear induction motor based on the equivalent circuit of the rotor mathematical model;

step S30, calculating the ratio a of each stator segment covering the rotor according to the rotor position of the unequal length segment power supply linear induction motor_sStator segment length coefficient b_sAnd a mover length coefficient c_s；

Step S40, based on the mathematical models of the stator and the mover of the unequal length linear induction motor and the ratio a of each stator segment covering the mover_sStator segment length coefficient b_sAnd a mover length coefficient c_sAcquiring voltage and flux linkage state equations of the unequal length segmented power supply linear induction motor under a steady state working condition;

step S50, based on the voltage and flux linkage state equation, obtaining feedforward voltage controlled by the unequal length linear induction motor stator segment, and realizing feedback closed-loop control of current through a PI controller;

step S60, adding the output reference voltage of feedback closed-loop control and the feed-forward voltage, and obtaining the reference voltage u of a three-phase coordinate system through ipark transformation_abcAnd the thrust closed-loop control of the unequal-length sectional power supply linear induction motor is completed.

2. The method for controlling a linear induction motor with unequal length segments according to claim 1, wherein step S30 comprises:

step S31, calculating the stator covering ratio a of the rotor when the rotor of the unequal length segmented power supply linear induction motor enters the stator segment and the rotor leaves the stator segment respectively_s；

Step S32, calculating the stator segment length coefficient b based on the length relation between the current stator segment and the shortest stator segment_s；

Step S33, calculating a rotor segment length coefficient c based on the length of the rotor segment and the length relation of the shortest stator segment_s。

3. The method of claim 2, wherein the ratio a of stator coverage of the mover when the mover enters the stator segment and when the mover leaves the stator segment is larger than a_sRespectively as follows:

wherein the content of the first and second substances,the coverage of the rotor to the stator when the rotor enters the stator section is represented,representing the ratio of stator covered by the rotor when the rotor leaves the stator section, s represents the distance from the tail of the current rotor to the starting point, s_moverThe length of the mover is represented,represents the absolute position of the stator tail of the x-th segment,represents the absolute position of the x-th segment stator head from the starting point,represents the length of the x-th stator segment, and n is the number of the stator segments.

4. The method for controlling a linear induction motor with unequal length and segmented power supply according to claim 2, wherein the length coefficient b of the stator segment is equal to the length coefficient of the stator segment_sComprises the following steps:

wherein the content of the first and second substances,represents the length of the x-th stator segment, s_minRepresenting the length of the shortest stator segment and n is the number of stator segments.

5. The method of claim 2, wherein the sub-segment length coefficient c is equal to the sub-segment length coefficient c_sComprises the following steps:

wherein s is_moverRepresenting the length of the mover, s_minRepresenting the length of the shortest stator segment.

6. The method for controlling the linear induction motor with unequal length and segmented power supply according to claim 1, wherein the voltage and flux linkage state equation of the linear induction motor with unequal length and segmented power supply under the steady-state working condition is as follows:

u_sαand u_sβRespectively representing the stator voltage, Ψ_sα、Ψ_sβ、Ψ_rαAnd Ψ_rβRespectively representing stator and mover flux linkages, i_sα、i_sβ、i_rαAnd i_rβRepresenting stator and mover currents, respectively, R_sRepresents the stator resistance, R_rRepresents a mover resistance, L_lsRepresenting stator leakage inductance, L_lrRepresenting a leakage inductance of the mover, L_mRepresenting mutual inductance.

7. The method for controlling linear induction motors with unequal length and segmented power supply according to claim 1, wherein the feedforward voltage controlled by the stator segments of the unequal length linear induction motors is as follows:

wherein the content of the first and second substances,representing feed forward voltage, R, controlled by unequal length linear induction electronic stator segments_sRepresents the stator resistance, L_lsRepresenting stator leakage inductance, L_mWhich represents the mutual inductance,reference current, ω, representing the dq axis of the stator segment_sRepresenting the magnetic field orientation angular velocity.

8. The method as claimed in claim 7, wherein the magnetic field orientation angular velocity ω is controlled by the linear induction motor_sComprises the following steps:

wherein the content of the first and second substances,represents the electrical angular velocity when the rotor velocity is v, tau represents the polar distance of the unequal length sectional linear induction motor,representing control slip.

9. The method as claimed in claim 8,the unequal length segmented power supply linear induction motor is characterized in that the control strategy of the unequal length segmented power supply linear induction motor adopts the control slipAnd current amplitudeThe control slipAnd current amplitudeThe calculation method comprises the following steps:

wherein R is_rRepresents a mover resistance, L_lrRepresenting a leakage inductance of the mover, L_mRepresenting mutual inductance.

10. A control system for a linear induction motor with unequal length and segmented power supply is characterized by comprising the following modules:

the equivalent circuit building module is configured to build an equivalent circuit of a stator mathematical model and an equivalent circuit of a rotor mathematical model according to the actual structure of the unequal-length segmented power supply linear induction motor;

the mathematical model building module is configured to build a stator mathematical model of the unequal length segmented power supply linear induction motor based on an equivalent circuit of the stator mathematical model; constructing a rotor mathematical model of the unequal length segmented power supply linear induction motor based on the equivalent circuit of the rotor mathematical model;

a parameter calculation module configured to calculate the ratio a of each stator segment covering the mover according to the positions of the movers of the unequal length segmented power supply linear induction motor_sStator segment length coefficient b_sAnd a mover length coefficient c_s；

The voltage and flux linkage state equation building module is configured to be based on a stator mathematical model and a rotor mathematical model of the unequal length linear induction motor and the ratio a of each stator segment covering the rotor_sStator segment length coefficient b_sAnd a mover length coefficient c_sAcquiring voltage and flux linkage state equations of the unequal length segmented power supply linear induction motor under a steady state working condition;

the feedforward and feedback control module is configured to obtain feedforward voltage controlled by the stator segments of the linear induction motor with different lengths based on the voltage and the flux linkage state equation and realize feedback closed-loop control of current through a PI (proportional-integral) controller;

a thrust closed-loop control module configured to add the output reference voltage of the feedback closed-loop control and the feed-forward voltage and obtain a reference voltage u of a three-phase coordinate system through ipark transformation_abcAnd the thrust closed-loop control of the unequal-length sectional power supply linear induction motor is completed.

Technical Field

The invention belongs to the technical field of motor control, and particularly relates to a method and a system for controlling a linear induction motor with unequal length and sectional power supply.

Background

The long stator linear induction motor has the characteristics of high power, simple rotor structure and the like, is suitable for short-time, high-thrust and high-speed electromagnetic propulsion systems, and can be applied to the fields of industry, traffic and national defense. In order to reduce the capacity of a single power supply of a long stator linear induction motor and the withstand voltage grade of stator segments, the long stator is divided into a plurality of short stator segments, and each stator segment is supplied with power in a segmented mode through an alternating current change-over switch. In order to reduce the number of the alternating current switches and the switching times, the linear induction motor can be segmented in unequal lengths. At the initial position of the linear motor track, the operation speed of the rotor is low, the voltage required by each pair of poles of the stator is low, and a plurality of stator segments can be connected in series, so that the stator segments in the region can be arranged longer. In a high-speed region where the mover operates, a voltage required for each pair of poles of the stator is high, and thus the stator length can be set to be relatively short in this region.

The unequal-length subsection power supply can reduce the quantity and switching times of alternating-current transfer switches of the linear motor track, reduce the cost of an electromagnetic driving system, reduce the thrust fluctuation of the subsection and improve the reliability of the system. However, the unequal lengths of the stator segments can cause the parameters of the power supply stator segment linear motor to change constantly, and particularly, the problems of current impact and thrust fluctuation can be caused when the two stator segments with different lengths are switched. Therefore, it is necessary to solve the related problems caused by the unequal-length stator segments by researching an optimization control method on the basis of not changing the hardware architecture of the existing electromagnetic driving system. Some documents disclose a sectional power supply system [1] for an induction linear motor, which can reduce the number of power supplies, reduce the cost, solve the problem of thrust fluctuation caused by asynchronous operation of a frequency converter in dual power supply and reduce the influence of a switch on the power supply system, but the invention cannot solve the control problem caused by parameter change of the sectional power supply linear motor with unequal length. Other systems disclose a sectional power supply control system and method [2] for a long primary linear motor, however, the method mainly describes a control system of a linear synchronous motor with equal-length sectional power supply, and the method is not suitable for analyzing parameter variation characteristics and a control method of a linear induction motor with unequal-length sectional power supply.

The following documents are background information related to the present invention:

[1] zhang Yongkang, Li Yu Man, Wang Ji, Chua Shi Wei, Dong Wen Bo, Li Xiang, Zhang Jianquan, a sectionalized power supply system for induction linear motors, 2019-11-29, and CN110912493A.

[2] The segmented power supply control system and the segmented power supply control method for the long-primary linear motor are characterized by comprising the following steps of Asahi, Maocai, Zhanyanqing, Zhanshihua and Waekang, 2018-05-16 and CN110504893A.

Disclosure of Invention

In order to solve the above problems in the prior art, that is, the prior art cannot realize parameter change characteristic analysis and control of an unequal length segmented power supply linear induction motor, the invention provides a control method of an unequal length segmented power supply linear induction motor, the control method comprising:

step S10, constructing an equivalent circuit of a stator mathematical model and an equivalent circuit of a rotor mathematical model according to the actual structure of the unequal length sectional power supply linear induction motor;

step S20, constructing a stator mathematical model of the unequal length segmented power supply linear induction motor based on the equivalent circuit of the stator mathematical model; constructing a rotor mathematical model of the unequal length segmented power supply linear induction motor based on the equivalent circuit of the rotor mathematical model;

step S30, calculating the ratio a of each stator segment covering the rotor according to the rotor position of the unequal length segment power supply linear induction motor_sStator segment length coefficient b_sAnd a mover length coefficient c_s；

Step S40, based on the mathematical models of the stator and the mover of the unequal length linear induction motor and the ratio a of each stator segment covering the mover_sStator segment length coefficient b_sAnd a mover length coefficient c_sObtaining unequal length scoresA voltage and flux linkage state equation of the section power supply linear induction motor under a steady state working condition;

step S50, based on the voltage and flux linkage state equation, obtaining feedforward voltage controlled by the stator segments of the linear induction motor with unequal lengths, and realizing feedback closed-loop control of current through a PI (Proportional Integral Controller);

step S60, adding the output reference voltage of feedback closed-loop control and the feed-forward voltage, and obtaining the reference voltage u of a three-phase coordinate system through ipark transformation_abcAnd the thrust closed-loop control of the unequal-length sectional power supply linear induction motor is completed.

The ipark transform is an inverse transform of the park transform, which is a constant coefficient differential equation in which each electromagnetic quantity (such as current, voltage, flux linkage, etc.) of the abc transformation quantity system is converted into a dq0 axis variable system having the vertical axis d, the horizontal axis q, and the stationary axis 0 of the rotor as coordinate axes, and a variable coefficient differential equation having a time-varying inductance established by phase coordinates is converted into an inductance represented by axis coordinates as a constant coefficient.

Mathematically, the park transform has nothing but a coordinate transform, transforming the abc coordinates to the dq0 coordinates, and transforming u to the dq0 coordinates_a,u_b,u_b,i_a,i_b,i_cThe quantities flux a, flux b and flux c are transformed into dq0 coordinates and back if necessary.

In physical sense, park transform is to transform i_a,i_b,i_cThe projection of the current on the alpha axis and the beta axis is equivalent to the d axis and the q axis, and the current on the stator is equivalent to the direct axis and the quadrature axis. For steady state, after equivalence, i_q,i_dIs a constant.

In some preferred embodiments, step S30 includes:

step S31, calculating the stator covering ratio a of the rotor when the rotor of the unequal length segmented power supply linear induction motor enters the stator segment and the rotor leaves the stator segment respectively_s；

Step S32, calculating the stator segment length coefficient b based on the length relation between the current stator segment and the shortest stator segment_s；

Step S33, calculating a rotor segment length coefficient c based on the length of the rotor segment and the length relation of the shortest stator segment_s。

In some preferred embodiments, the mover covers the stator fraction a when the mover enters a stator segment and when the mover leaves a stator segment_sRespectively as follows:

wherein the content of the first and second substances,the coverage of the rotor to the stator when the rotor enters the stator section is represented,representing the ratio of stator covered by the rotor when the rotor leaves the stator section, s represents the distance from the tail of the current rotor to the starting point, s_moverThe length of the mover is represented,represents the absolute position of the stator tail of the x-th segment,represents the absolute position of the x-th segment stator head from the starting point,represents the length of the x-th stator segment, and n is the number of the stator segments.

In some preferred embodiments, the stator segment length coefficient b_sComprises the following steps:

wherein the content of the first and second substances,represents the length of the x-th stator segment, s_minRepresenting the length of the shortest stator segment and n is the number of stator segments.

In some preferred embodiments, the sub section length coefficient c_sComprises the following steps:

wherein s is_moverRepresenting the length of the mover, s_minRepresenting the length of the shortest stator segment.

In some preferred embodiments, the voltage and flux linkage state equation of the unequal length segmented power supply linear induction motor under the steady state working condition is as follows:

wherein u is_sαAnd u_sβRespectively representing the stator voltage, Ψ_sα、Ψ_sβ、Ψ_rαAnd Ψ_rβRespectively representing stator and mover flux linkages, i_sα、i_sβ、i_rαAnd i_rβRepresenting stator and mover currents, respectively, R_sRepresents the stator resistance, R_rRepresents a mover resistance, L_lsRepresenting stator leakage inductance, L_lrRepresenting a leakage inductance of the mover, L_mRepresenting mutual inductance.

In some preferred embodiments, the feed forward voltage controlled by the stator segments of the linear induction motor with different lengths is:

wherein the content of the first and second substances,representing feed forward voltage, R, controlled by unequal length linear induction electronic stator segments_sRepresents the stator resistance, L_lsRepresenting stator leakage inductance, L_mWhich represents the mutual inductance,reference current, ω, representing the dq axis of the stator segment_sRepresenting the magnetic field orientation angular velocity.

In some preferred embodiments, the magnetic field orients an angular velocity ω_sComprises the following steps:

wherein the content of the first and second substances,represents the electrical angular velocity when the rotor velocity is v, tau represents the polar distance of the unequal length sectional linear induction motor,representing control slip.

In some preferred embodiments, the control strategy of the unequal length segmented power supply linear induction motor adopts the control slipAnd current amplitudeThe control slipAnd current amplitudeThe calculation method comprises the following steps:

wherein R is_rRepresents a mover resistance, L_lrRepresenting a leakage inductance of the mover, L_mRepresenting mutual inductance.

In another aspect of the present invention, a control system for a linear induction motor with unequal length and segmented power supply is provided, the control system comprising the following modules:

the equivalent circuit building module is configured to build an equivalent circuit of a stator mathematical model and an equivalent circuit of a rotor mathematical model according to the actual structure of the unequal-length segmented power supply linear induction motor;

the mathematical model building module is configured to build a stator mathematical model of the unequal length segmented power supply linear induction motor based on an equivalent circuit of the stator mathematical model; constructing a rotor mathematical model of the unequal length segmented power supply linear induction motor based on the equivalent circuit of the rotor mathematical model;

a parameter calculation module configured to calculate the ratio a of each stator segment covering the mover according to the positions of the movers of the unequal length segmented power supply linear induction motor_sStator segment length coefficient b_sAnd a mover length coefficient c_s；

The voltage and flux linkage state equation building module is configured to be based on a stator mathematical model and a rotor mathematical model of the unequal length linear induction motor and the ratio a of each stator segment covering the rotor_sStator segment length coefficient b_sAnd a mover length coefficient c_sAcquiring voltage and flux linkage state equations of the unequal length segmented power supply linear induction motor under a steady state working condition;

the feedforward and feedback control module is configured to obtain feedforward voltage controlled by the stator segments of the linear induction motor with different lengths based on the voltage and the flux linkage state equation and realize feedback closed-loop control of current through a PI (proportional-integral) controller;

a thrust closed-loop control module configured to add the output reference voltage of the feedback closed-loop control and the feed-forward voltage and obtain a reference voltage u of a three-phase coordinate system through ipark transformation_abcAnd the thrust closed-loop control of the unequal-length sectional power supply linear induction motor is completed.

The invention has the beneficial effects that:

(1) the invention relates to a control method of an unequal length sectionalized power supply linear induction motor, which realizes decoupling modeling of a stator and a rotor of the unequal length sectionalized power supply linear induction motor by establishing a stator mathematical model of the linear induction motor by using a solid rotor and establishing a rotor mathematical model of the linear induction motor by using a virtual rotor.

(2) The invention relates to a control method of a linear induction motor with unequal length sectional power supply, which solves the problem of motor modeling under the condition that parameters of a stator section jump along with the movement of a rotor, ensures that thrust can still be stably output when the length of the stator section jumps, and can be used for offline or real-time electromagnetic transient simulation of the linear induction motor with unequal length sectional power supply.

(3) The method for controlling the unequal-length sectionalized power supply linear induction motor ensures that the thrust is still stably output when the length of the stator section jumps on the premise of decoupling modeling and offline or real-time electromagnetic transient simulation of modeling of the stator and the rotor of the unequal-length sectionalized power supply linear induction motor, thereby realizing accurate and stable control of the unequal-length sectionalized power supply linear induction motor.

Drawings

Other features, objects and advantages of the present application will become more apparent upon reading of the following detailed description of non-limiting embodiments thereof, made with reference to the accompanying drawings in which:

FIG. 1 is a schematic flow chart of a method for controlling a linear induction motor with unequal length and sectional power supply according to the invention;

FIG. 2 is a structural diagram of a driving system of an embodiment of a method for controlling a linear induction motor with unequal length and segmented power supply according to the invention;

FIG. 3 is an equivalent circuit of a stator mathematical model and an equivalent circuit of a mover mathematical model of an embodiment of the unequal length segmented power supply linear induction motor control method of the invention;

FIG. 4 is a mathematical model of one embodiment of the method for controlling a variable length segmented power supply linear induction motor according to the present invention;

FIG. 5 is a stator ratio and length coefficient graph of an embodiment of the method for controlling a linear induction motor with unequal length and segmented power supply of the present invention;

FIG. 6 shows the motor reference current, electrical angular velocity, feed forward voltage and PI controller output voltage of an embodiment of the method for controlling linear induction motors with unequal length segmented power supplies of the present invention;

FIG. 7 shows the voltage, current and thrust of the stator segment according to one embodiment of the method for controlling the linear induction motor with unequal length and segmented power supply.

Detailed Description

The present application will be described in further detail with reference to the following drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the relevant invention and not restrictive of the invention. It should be noted that, for convenience of description, only the portions related to the related invention are shown in the drawings.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.

The invention discloses a control method of a linear induction motor with unequal length and sectional power supply, which comprises the following steps:

step S10, constructing an equivalent circuit of a stator mathematical model and an equivalent circuit of a rotor mathematical model according to the actual structure of the unequal length sectional power supply linear induction motor;

step S20, constructing a stator mathematical model of the unequal length segmented power supply linear induction motor based on the equivalent circuit of the stator mathematical model; constructing a rotor mathematical model of the unequal length segmented power supply linear induction motor based on the equivalent circuit of the rotor mathematical model;

step S30, calculating the ratio a of each stator segment covering the rotor according to the rotor position of the unequal length segment power supply linear induction motor_sStator segment length coefficient b_sAnd a mover length coefficient c_s；

Step S40, based on the mathematical models of the stator and the mover of the unequal length linear induction motor and the ratio a of each stator segment covering the mover_sStator segment length coefficient b_sAnd moverLength coefficient c_sAcquiring voltage and flux linkage state equations of the unequal length segmented power supply linear induction motor under a steady state working condition;

step S50, based on the voltage and flux linkage state equation, obtaining feedforward voltage controlled by the unequal length linear induction motor stator segment, and realizing feedback closed-loop control of current through a PI controller;

step S60, adding the output reference voltage of feedback closed-loop control and the feed-forward voltage, and obtaining the reference voltage u of a three-phase coordinate system through ipark transformation_abcAnd the thrust closed-loop control of the unequal-length sectional power supply linear induction motor is completed.

In order to more clearly describe the method for controlling the linear induction motor with unequal length and segmented power supply according to the present invention, the following will describe each step in the embodiment of the present invention in detail with reference to fig. 1.

The method for controlling the unequal-length segmented power supply linear induction motor in the first embodiment of the invention comprises the following steps of S10-S60, wherein the following steps are described in detail:

as shown in FIG. 2, a power source u is a driving system structure diagram of an embodiment of the method for controlling a linear induction motor with unequal length and segmented power supply according to the invention₁And a power supply u₂And outputting a power supply voltage source for 2 converters. Power supply u₁Is a stator segment S_{1_1}、S_{2_1}……S_{n_1}Supplying power by controlling an AC switch k_{1_1}、k_{2_1}……k_{n_1}The on-off of which realizes the segmented power supply of the stator segment, b_{1_1}、b_{2_1}……b_{n_1}Represents a stator segment S_{1_1}、S_{2_1}……S_{n_1}The length factor of (c). Power supply u₂Is a stator segment S_{1_2}、S_{2_2}……S_{n_2}Supplying power by controlling an AC switch k_{1_2}、k_{2_2}……k_{n_2}The on-off of which realizes the segmented power supply of the stator segment, b_{1_2}、b_{2_2}……b_{n_2}Represents a stator segment S_{1_2}、S_{2_2}……S_{n_2}The length factor of (c). In the figure b_{1_1}And b_{1_2}Is a stator section at the initial part of the track, and the speed of a motor rotor passing through the stator section is lowerThe number of switches is reduced, and the length of the stator section is longer than that of other stator sections. Mover positions 1 and 2 represent mover positions at different times, a₁Covering linear induction motor stator section S for rotor_{1_1}、S_{2_1}……S_{n_1}A ratio of₁The value range is 0-1; a is₂Covering linear induction motor stator section S for rotor_{1_2}、S_{2_2}……S_{n_2}A ratio of₂The value range is 0-1. c. C_sA length coefficient of the mover, c is a length coefficient of the mover, since the length of the mover is not changed_sIs a constant value.

And step S10, constructing an equivalent circuit of a stator mathematical model and an equivalent circuit of a rotor mathematical model according to the actual structure of the unequal length sectional power supply linear induction motor.

In an embodiment of the present invention, as shown in fig. 3, the equivalent circuit of the stator mathematical model includes a stator-side equivalent circuit of the stator mathematical model and a solid mover-side equivalent circuit:

the stator side equivalent circuit of the stator mathematical model comprises a stator resistor R connected in series_sStator leakage inductance b_sL_lsAnd stator excitation inductance b_sL_mAnd applying a stator voltage u to both ends of the stator equivalent circuit of the mathematical stator model_sThen the stator side current of the stator mathematical model is i_s；

The equivalent circuit at the side of the solid rotor comprises an excitation inductor A which is connected in series and closed and covers the current stator section by the solid rotor_sb_sL_mSolid mover resistor R_r1And solid mover leakage inductance L_lr1The current on the active cell side of the solid is i_r1；

Stator side equivalent circuit of stator mathematical model, entity rotor side equivalent circuit and excitation inductance b_sL_mAnd the excitation inductor A of the entity rotor covering the current stator segment_sb_sL_mAre coupled.

In an embodiment of the present invention, as shown in fig. 3, the equivalent circuit of the mover mathematical model includes a stator-side equivalent circuit and a virtual mover-side equivalent circuit of the mover mathematical model:

the equivalent circuit on the stator side of the rotor mathematical model is the same as the equivalent circuit on the stator side of the stator mathematical model;

the virtual rotor side equivalent circuit comprises excitation inductors L which are connected in series and closed and are arranged on the virtual rotor side_mVirtual mover resistor R_r2And virtual mover leakage inductance L_lr2Virtual mover side current is i_r2；

Rotor mathematical model stator side equivalent circuit, virtual rotor side equivalent circuit and excitation inductance B_sL_mAnd excitation inductance L on the virtual mover side_mAre coupled.

Step S20, constructing a stator mathematical model of the unequal length segmented power supply linear induction motor based on the equivalent circuit of the stator mathematical model; and constructing a rotor mathematical model of the unequal length segmented power supply linear induction motor based on the equivalent circuit of the rotor mathematical model.

In one embodiment of the invention, the stator mathematical model comprises n stator segment mathematical models, the rotor mathematical model comprises a virtual rotor mathematical model and a solid rotor mathematical model, the virtual rotor mathematical model fully covers all stator end mathematical models, the solid rotor mathematical model is a mathematical model of a rotor which actually moves linearly, and n is the number of the stator segments.

The stator mathematical model is shown as formula (1):

wherein u is_sRepresenting the stator voltage, i_sRepresenting stator current, Ψ_sRepresenting stator flux linkage vector, i_rRepresenting the mover current, b_sRepresenting stator segment length coefficients, p representing a differential operator, R_sRepresents the stator resistance, b_sL_mRepresents the excitation inductance, A_sRepresenting the coupling coefficient.

Assuming that a segmented power supply can realize accurate current closed-loop control of each stator segment, the stator current amplitude phase of the rotor passing through each stator segment is equal and continuous, the angle of the rotor can enable the stator to be equivalent to infinite length, and therefore a rotor mathematical model is deduced, as shown in formula (2):

therein, Ψ_rRepresenting a mover flux linkage vector, ω_eRepresenting the electrical angular velocity of the mover, j representing a complex factor, i_rIs a mover current, L_rAnd excitation inductors on the virtual rotor side.

Referring to fig. 4, a mathematical model of an embodiment of the method for controlling a linear induction motor with unequal length segment power supply according to the present invention is illustrated by taking the position 2 of the mover in fig. 2 as an example, where the mover covers the stator segment S_{1_2}And stator segment S_{2_1}The stator lengths of the two stator segments are unequal, respectively b_{1_2}And b_{2_1}. For stator segment S_{1_2}Mutual inductance with mover is a₂b_{1_2}L_m. For stator segment S_{2_1}Mutual inductance with mover is a₁b_{2_1}L_m. For the mover, it has mutual inductance with both stators, and the value is a₂b_{1_2}L_m+a₁b_{2_1}L_mAnd a is₂b_{1_2}+a₁b_{2_1}＝c_s。

Step S30, calculating the ratio a of each stator segment covering the rotor according to the rotor position of the unequal length segment power supply linear induction motor_sStator segment length coefficient b_sAnd a mover length coefficient c_s：

Step S31, calculating the stator covering ratio a of the rotor when the rotor of the unequal length segmented power supply linear induction motor enters the stator segment and the rotor leaves the stator segment respectively_sAs shown in formula (3) and formula (4), respectively:

wherein the content of the first and second substances,the coverage of the rotor to the stator when the rotor enters the stator section is represented,representing the ratio of stator covered by the rotor when the rotor leaves the stator section, s represents the distance from the tail of the current rotor to the starting point, s_moverThe length of the mover is represented,represents the absolute position of the stator tail of the x-th segment,represents the absolute position of the x-th segment stator head from the starting point,represents the length of the x-th stator segment, and n is the number of the stator segments.

Step S32, calculating the stator segment length coefficient b based on the length relation between the current stator segment and the shortest stator segment_sAs shown in formula (5):

wherein the content of the first and second substances,represents the length of the x-th stator segment, s_minRepresenting the length of the shortest stator segment and n is the number of stator segments.

Step S33, calculating a rotor segment length coefficient c based on the length of the rotor segment and the length relation of the shortest stator segment_sAs shown in formula (6):

wherein s is_moverRepresenting the length of the mover, s_minRepresenting the length of the shortest stator segment.

As shown in fig. 5, in the graph of the stator ratio and the length coefficient for the method for controlling the linear induction motor with unequal length and segmented power supply according to the embodiment of the present invention, the abscissa represents time (unit: s), the ordinate on the graph of fig. 5 represents the position of the mover (unit: m), the ordinate on the graph of fig. 5 represents the stator ratio, and the ordinate on the graph of fig. 5 represents the length coefficient of the stator.

Step S40, based on the mathematical models of the stator and the mover of the unequal length linear induction motor and the ratio a of each stator segment covering the mover_sStator segment length coefficient b_sAnd a mover length coefficient c_sAcquiring a voltage and flux linkage state equation of the unequal length segmented power supply linear induction motor under a steady state working condition, as shown in formula (7):

u_sαand u_sβRespectively representing the stator voltage, Ψ_sα、Ψ_sβ、Ψ_rαAnd Ψ_rβRespectively representing stator and mover flux linkages, i_sα、i_sβ、i_rαAnd i_rβRepresenting stator and mover currents, respectively, R_sRepresents the stator resistance, R_rRepresents a mover resistance, L_lsRepresenting stator leakage inductance, L_lrRepresenting a leakage inductance of the mover, L_mRepresenting mutual inductance.

And step S50, acquiring feedforward voltage controlled by the stator segments of the linear induction motor with different lengths based on the voltage and flux linkage state equation, and realizing feedback closed-loop control of current through a PI controller.

The feedforward voltage controlled by the stator segments of the linear induction motor with different lengths is shown as the formula (8):

wherein the content of the first and second substances,representing feed forward voltage, R, controlled by unequal length linear induction electronic stator segments_sRepresents the stator resistance, L_lsRepresenting stator leakage inductance, L_mWhich represents the mutual inductance,reference current, ω, representing the dq axis of the stator segment_sRepresenting the magnetic field orientation angular velocity.

Magnetic field orientation angular velocity omega_sThe calculation method is shown as formula (9):

wherein the content of the first and second substances,represents the electrical angular velocity when the rotor velocity is v, tau represents the polar distance of the unequal length sectional linear induction motor,representing control slip.

The unequal length segmented power supply linear induction motor adopts the control slipAnd current amplitudeBy indirect magnetic field orientation, controlling slipAnd current amplitudeThe calculation method of (2) is shown in formula (10):

wherein R is_rRepresents a mover resistance, L_lrRepresenting a leakage inductance of the mover, L_mRepresenting mutual inductance.

Step S60, adding the output reference voltage of feedback closed-loop control and the feed-forward voltage, and obtaining the reference voltage u of a three-phase coordinate system through ipark transformation_abcAnd the thrust closed-loop control of the unequal-length sectional power supply linear induction motor is completed.

Collecting three-phase current of a motor, obtaining a feedback value of the motor current of a rotating coordinate system through park conversion, realizing feedback closed-loop control of the current by adopting a PI (proportional-integral) controller, outputting a reference voltage, adding the output reference voltage and a feed-forward voltage, and obtaining a reference voltage u of the three-phase coordinate system through ipark conversion_abcAnd the thrust closed-loop control of the sectionally-powered linear induction motor is completed.

The control method is subjected to simulation verification by adopting an example, a verification platform of the control method of the linear induction motor with unequal-length segmented power supply is built in Matlab simulink, 0.5 microsecond fixed step size simulation is adopted, and the control period is 100 microseconds. FIG. 5 is a graph of the ratio of the stators and the length coefficient of the unequal length linear induction motor, where the ratio a of the stator covered by the mover and powered by the current power supply can be calculated from the position of the mover_sAnd length coefficient b of stator_s. Fig. 6 shows the motor reference current, electrical angular velocity, feed forward voltage and PI controller output voltage. Fig. 7 shows stator segment voltage, current and thrust. According to the simulation results, the control method of the unequal-length segmented power supply linear motor can realize stable control of the thrust of the unequal-length segmented linear motor.

Although the foregoing embodiments describe the steps in the above sequential order, those skilled in the art will understand that, in order to achieve the effect of the present embodiments, the steps may not be executed in such an order, and may be executed simultaneously (in parallel) or in an inverse order, and these simple variations are within the scope of the present invention.

The invention discloses a control system of a linear induction motor with unequal length and segmented power supply, which comprises the following modules:

the equivalent circuit building module is configured to build an equivalent circuit of a stator mathematical model and an equivalent circuit of a rotor mathematical model according to the actual structure of the unequal-length segmented power supply linear induction motor;

the mathematical model building module is configured to build a stator mathematical model of the unequal length segmented power supply linear induction motor based on an equivalent circuit of the stator mathematical model; constructing a rotor mathematical model of the unequal length segmented power supply linear induction motor based on the equivalent circuit of the rotor mathematical model;

a parameter calculation module configured to calculate the ratio a of each stator segment covering the mover according to the positions of the movers of the unequal length segmented power supply linear induction motor_sStator segment length coefficient b_sAnd a mover length coefficient c_s；

The voltage and flux linkage state equation building module is configured to be based on a stator mathematical model and a rotor mathematical model of the unequal length linear induction motor and the ratio a of each stator segment covering the rotor_sStator segment length coefficient b_sAnd a mover length coefficient c_sAcquiring voltage and flux linkage state equations of the unequal length segmented power supply linear induction motor under a steady state working condition;

the feedforward and feedback control module is configured to obtain feedforward voltage controlled by the stator segments of the linear induction motor with different lengths based on the voltage and the flux linkage state equation and realize feedback closed-loop control of current through a PI (proportional-integral) controller;

a thrust closed-loop control module configured to add the output reference voltage of the feedback closed-loop control and the feed-forward voltage and obtain a reference voltage u of a three-phase coordinate system through ipark transformation_abcAnd the thrust closed-loop control of the unequal-length sectional power supply linear induction motor is completed.

It can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working process and related description of the system described above may refer to the corresponding process in the foregoing method embodiments, and will not be described herein again.

It should be noted that the unequal-length segmented power supply linear induction motor control system provided in the foregoing embodiment is only illustrated by dividing the functional modules, and in practical applications, the functions may be distributed by different functional modules according to needs, that is, the modules or steps in the embodiment of the present invention are further decomposed or combined, for example, the modules in the foregoing embodiment may be combined into one module, or may be further split into a plurality of sub-modules, so as to complete all or part of the functions described above. The names of the modules and steps involved in the embodiments of the present invention are only for distinguishing the modules or steps, and are not to be construed as unduly limiting the present invention.

An electronic apparatus according to a third embodiment of the present invention includes:

at least one processor; and

a memory communicatively coupled to at least one of the processors; wherein the content of the first and second substances,

the memory stores instructions executable by the processor for execution by the processor to implement the method for controlling an unequal length piecewise-powered linear induction motor described above.

A computer-readable storage medium of a fourth embodiment of the present invention stores computer instructions for being executed by the computer to implement the method for controlling an unequal-length piecewise-powered linear induction motor.

It can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working processes and related descriptions of the storage device and the processing device described above may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

Those of skill in the art would appreciate that the various illustrative modules, method steps, and modules described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that programs corresponding to the software modules, method steps may be located in Random Access Memory (RAM), memory, Read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. To clearly illustrate this interchangeability of electronic hardware and software, various illustrative components and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as electronic hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

The terms "first," "second," and the like are used for distinguishing between similar elements and not necessarily for describing or implying a particular order or sequence.

The terms "comprises," "comprising," or any other similar term are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

So far, the technical solutions of the present invention have been described in connection with the preferred embodiments shown in the drawings, but it is easily understood by those skilled in the art that the scope of the present invention is obviously not limited to these specific embodiments. Equivalent changes or substitutions of related technical features can be made by those skilled in the art without departing from the principle of the invention, and the technical scheme after the changes or substitutions can fall into the protection scope of the invention.