A control method and system of an urban rail transit asynchronous motor based on a flux linkage observer

Abstract

The application relates to a kind of urban rail transit asynchronous motor control method and system based on flux observer, the method comprises the following steps: step S1, based on wheel set fixed shaft rotation equation, determine the load torque of urban rail train asynchronous motor;Step S2, in combination with different road conditions and carrying demand, determine train operation strategy, obtain preset speed and acceleration trajectory;Step S3, based on flux observer, build urban rail train asynchronous motor control model, according to preset speed and acceleration trajectory, control urban rail train asynchronous motor.Compared with prior art, the load calculation of urban rail train, traction mode and asynchronous motor control based on flux observer are separated in the application, the general practicability of asynchronous motor control mode is increased, more accurate flux observation can be realized by using rotor flux observer, and vector control is realized by decoupling of asynchronous motor model.

Description

Technical Field

[0001] This invention relates to the field of rail transit control technology, and in particular to a method and system for controlling asynchronous motors in urban rail transit based on a flux linkage observer. Background Technology

[0002] With the deepening of urbanization and urban construction, urban rail transit is gaining increasing popularity. Against the backdrop of rapid development in the transportation industry, continuous growth in overall transportation energy consumption, and a surge in electricity consumption, research on the efficient control of urban rail trains is of great significance.

[0003] The operation of urban rail transit systems is planned and organized; however, due to uneven spatial and temporal distribution of passenger flow and complex train operation conditions, train operation needs to be adjusted in a timely manner according to actual conditions to achieve "on-demand" start and stop, which places high demands on motor control. The most commonly used motor in urban rail vehicles is the asynchronous motor, which has advantages such as low cost and ease of installation, use, and maintenance.

[0004] When modeling an asynchronous motor, it is necessary to ignore harmonics, magnetic circuit saturation, and core losses present in space. In a three-phase stationary coordinate system, the mathematical model of an asynchronous motor is a high-order, nonlinear, strongly coupled, multivariable system.

[0005] Currently, the most widely used asynchronous motor control methods include vector control, direct torque control, adaptive control, and artificial intelligence-based control. Traditional variable frequency speed control systems control only the stator voltage amplitude and frequency, and cannot arbitrarily control the magnitude and position of the stator and rotor magnetic flux vectors, resulting in low precision, high energy consumption, and poor efficiency.

[0006] Vector or direct torque control technology allows asynchronous motors to be controlled like DC motors, greatly improving the performance and application range of AC motors.

[0007] Vector control of AC asynchronous motors includes three types: rotor field-oriented, air-gap field-oriented, and stator field-oriented. After simplifying the motor model through coordinate transformation, an equivalent DC motor model can be obtained in the synchronously rotating coordinate system oriented by rotor flux linkage. Similar to the control of electromagnetic torque and flux linkage in DC motors, the control quantities in the rotor flux linkage-oriented coordinate system can be inversely transformed to obtain the corresponding quantities in the three coordinate systems for control. In the traditional direct field-oriented control process, if the amplitude or phase of the flux linkage is inaccurate, the system performance will be significantly reduced. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a highly practical and more precise control method and system for asynchronous motor control in urban rail transit based on a flux linkage observer, so that the train can start and stop on demand according to actual needs, thereby further improving the traction and braking performance of the train.

[0009] The objective of this invention can be achieved through the following technical solutions:

[0010] This invention provides a control method for asynchronous motors in urban rail transit based on a flux linkage observer. The method includes the following steps:

[0011] Step S1: Determine the load torque of the asynchronous motor of the urban rail train based on the fixed-axis rotation equation of the wheelset;

[0012] Step S2: Determine the train operation strategy based on different road conditions and transportation needs;

[0013] Step S3: Based on the flux linkage observer, build a control model for the asynchronous motor of the urban rail train and control the asynchronous motor of the urban rail train.

[0014] Preferably, step S1 includes the following sub-steps:

[0015] Step S11: Calculate the traction force of the single-moving axle output wheel based on the wheelset fixed-axis rotation equation;

[0016] Step S12: Based on the traction force of the single-acting axle output wheel axle and the motion equation of the traction motor, calculate the actual load torque of the motor during the actual operation of the train.

[0017] Preferably, step S11 specifically includes:

[0018] 1) Equation of rotation of wheelset on fixed axis:

[0019] F mw r g2 -F t R = J w α w (1)

[0020] Among them, F mv The force exerted by the motor on the driven wheel through the driving wheel; r g2 Where F is the radius of the driven gear; t The output axle wheel traction force is the single-acting axle; R is the vehicle radius; J w It is the sum of the moments of inertia of the wheelset and the driven mechanism; α w The formula for calculating the angular acceleration of the wheelset is:

[0021]

[0022] Where, ω wWhere γ is the wheel-to-wheel angular velocity, γ is the creep rate, and V is the vehicle's linear speed.

[0023] 2) Considering the creep phenomenon between the wheel and rail, according to Newton's second law and the equation of rotation of the wheelset with a fixed axle, the expression for the output axle traction force of the single-moving axle is:

[0024]

[0025] Where m is the mass distributed across the single-moving shaft, f m The resistance is distributed to the single-moving shaft, and m is the mass distributed to the single-moving shaft.

[0026] Preferably, step S12 specifically includes:

[0027] 1) For the traction motor, the equation of motion is:

[0028]

[0029] Among them, T m T is the output torque of the traction motor. L ω represents the actual load torque of the traction motor. m The mechanical angular velocity of the traction motor;

[0030] 2) Gears have a transmission efficiency that satisfies:

[0031] T L =F wm r g1 =F mw r g1 / η Gear (5)

[0032] Where, η Gear For gear transmission efficiency. g1 The radius of the driving gear.

[0033] 3) The actual load torque of the motor is expressed as:

[0034]

[0035] In the formula, J w R is the sum of the rotational inertia of the wheelset and the driven mechanism; R is the radius of the driven wheel; η Gear For gear transmission efficiency; i g N is the gear ratio; m ω represents the number of traction motors; M represents the total mass of the vehicle formation; m ω is the angular mechanical speed of the traction motor; f is the total resistance of the vehicle formation.

[0036] Preferably, the train operation strategy in step S2 includes a time-saving traction strategy, an energy-saving traction strategy, and a comfort traction strategy.

[0037] Preferably, the urban rail train asynchronous motor control model in step S3 is an urban rail train asynchronous motor control model based on rotor field-oriented control, specifically:

[0038] Acquisition of current signal i from AC motor A i B i C Perform Clarke transform to obtain i α i β After performing the Park transformation to obtain the rotated orthogonal coordinate system i d i q ;

[0039] The current signal from the asynchronous motor is input to the flux linkage observer, which outputs the rotor flux linkage observation value. This observation value is then used to calculate the speed. The deviation between the given speed and the observed speed value is input to the speed regulator, which outputs the control current.

[0040] Output current With the collected current i q The deviation is input to the current regulator, which will set the given excitation current. With the collected current i d The deviation is input to the current regulator, and the outputs of the two current regulators are successively processed by IPark transformation and space vector pulse width modulation (SVPWM) before being applied to the inverter. The inverter then indirectly controls the asynchronous motor, forming a closed-loop control.

[0041] Preferably, the flux linkage observer is a rotor flux linkage observer based on the dq-axis coordinate system, where the d-axis coincides with the rotor flux linkage vector, and is called a synchronous rotating orthogonal coordinate system oriented according to the rotor flux linkage:

[0042] 1) The voltage equation in the dq coordinate system is:

[0043]

[0044] In the formula, u sd i sd ψ sd These represent the components of stator voltage, current, and flux linkage along the d-axis, respectively. sq i sq ψ sq These are the components of stator voltage, current, and flux linkage along the q-axis, respectively; u rd i rd ψ rd These represent the rotor voltage, current, and flux linkage components along the d-axis, respectively. rq i rq ψ rqThese represent the components of rotor voltage, current, and flux linkage along the q-axis, respectively; ω is the rotor speed, and ω1 is the angular velocity relative to the stator dq coordinate axis; R s R r These are the resistances of the two equivalent windings of the stator and the resistances of the two equivalent windings of the rotor, respectively.

[0045] 2) The flux linkage equation is:

[0046]

[0047] In the formula, L s For the self-inductance of the equivalent two windings of the stator, L r L is the self-inductance of the rotor's equivalent two windings. m The mutual inductance between the coaxial equivalent windings of the stator and rotor;

[0048] 3) Calculate the rotor flux linkage ψ based on the voltage equation and the flux linkage equation. r And synchronous angular velocity ω1:

[0049]

[0050]

[0051] Integrating the synchronous angular velocity ω1 yields the rotational transformation angle θ inside the motor.

[0052] Preferably, the space vector pulse width modulation (SVPWM) process specifically comprises:

[0053] 1) Transform the AC motor model into an equivalent DC motor model;

[0054] 2) Perform sector identification:

[0055] The space vector formed by the three-phase voltages output by the inverter is:

[0056]

[0057] Define reference variables and constraints to obtain the specific correspondence between sector value N and sector number S;

[0058] 3) Calculate the duration of action:

[0059] During a switching cycle T0, at a certain moment, the voltage vector u s If you rotate to a certain position in the first sector, then u s It can be obtained from different combinations of two adjacent non-zero vectors U1, U2 and the zero vector U0 in time in this region. Let the time of action of the three be t1, t2, t0 respectively. According to the principle of balance equivalence, we can obtain:

[0060] U sT0=U1t1+U2t2+U0t0 (12)

[0061] Where T0 = t1 + t2 + t0;

[0062] Define a reference variable:

[0063]

[0064] Obtain the values ​​of t1, t2, and t0 within each sector;

[0065] The sector vector switching point is calculated using a seven-step method to output the space vector pulse width modulation (SVPWM) signal.

[0066] Preferably, the definition of reference variables and constraints to obtain the specific correspondence between sector value N and sector number S is as follows:

[0067] Define the reference variable as:

[0068]

[0069] The constraints are satisfied:

[0070]

[0071] The specific correspondence between sector value N = A + 2B + 4C and sector number S is obtained.

[0072] According to a second aspect of the present invention, a control system for an asynchronous motor in urban rail transit based on a flux linkage observer is provided, the system comprising:

[0073] Acquisition of current signal i from AC motor A i B i C i is obtained after the Clarke transform module α i β After passing through the Park transformation module, i is obtained in the rotated orthogonal coordinate system. d i q ;

[0074] The current signal from the asynchronous motor is input to the flux linkage observer, which outputs the rotor flux linkage observation value. This value is then used by the speed calculation module to calculate the observed speed. The deviation between the given speed and the observed speed value is input to the speed regulator, which outputs the control current.

[0075] Output current With the collected current i q The deviation is input to the current regulator, which will set the given excitation current. With the collected current i dThe deviation is input to the current regulator. The outputs of the two current regulators are successively adjusted by the IPark conversion module and the space vector pulse width modulation (SVPWM) module and then applied to the inverter. The inverter indirectly controls the asynchronous motor to form a closed-loop control.

[0076] The magnetic flux observer implements the method described above.

[0077] Compared with the prior art, the present invention has the following advantages:

[0078] 1) Separating the load calculation and traction mode of urban rail trains from the asynchronous motor control based on the flux linkage observer increases the general applicability of the asynchronous motor control mode, which is applicable to the motor control of any train under any operating conditions;

[0079] 2) In the design of the flux linkage observer, the stator voltage, current and speed of the AC motor are easy-to-measure physical quantities. Accurate flux linkage observation can be achieved by using the rotor flux linkage observation model, and vector control can be achieved by decoupling the asynchronous motor model. Attached Figure Description

[0080] Figure 1 Schematic diagrams of different traction strategies;

[0081] Figure 2 Graph showing implementation of the magnetic flux observer;

[0082] Figure 3 This is an implementation of the SVPWM algorithm;

[0083] Figure 4 This is a global control model for an asynchronous motor based on a flux linkage observer.

[0084] Figure 5 Flowchart for implementing an asynchronous motor control method for urban rail trains based on a flux linkage observer;

[0085] Figure 6 The motor speed in the embodiment;

[0086] Figure 7 The torque is the motor torque in the embodiment;

[0087] Figure 8 The three-phase electronic current of the motor in the embodiment;

[0088] Figure 9 This represents the flux linkage value observed by the flux linkage observer. Detailed Implementation

[0089] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0090] Example

[0091] This embodiment presents a control method for asynchronous motors in urban rail transit based on a flux linkage observer. The method includes the following steps:

[0092] Step S1: Determine the load torque of the asynchronous motor of the urban rail train based on the fixed-axis rotation equation of the wheelset;

[0093] Step S2: Combine different road conditions and transportation needs to determine the train operation strategy and obtain the preset speed and acceleration trajectory;

[0094] Step S3: Based on the flux linkage observer, build a control model for the asynchronous motor of the urban rail train, and control the asynchronous motor of the urban rail train according to the preset speed and acceleration trajectory.

[0095] Next, the method of the present invention will be described in detail, such as... Figure 5 As shown.

[0096] 1. Determination of load torque

[0097] Step S11: Based on the wheelset fixed-axis rotation equation, calculate the output axle traction force of the single-moving axle, specifically as follows:

[0098] 1) Equation of rotation of wheelset on fixed axis:

[0099] F mw r g2 -F t R = J w α w (1)

[0100] Among them, F mv The force exerted by the motor on the driven wheel through the driving wheel; r g2 Where F is the radius of the driven gear; t The output axle wheel traction force is the single-acting axle; R is the vehicle radius; J w It is the sum of the moments of inertia of the wheelset and the driven mechanism; α w The formula for calculating the angular acceleration of the wheelset is:

[0101]

[0102] Where, ω wWhere γ is the wheel-to-wheel angular velocity, γ is the creep rate, and V is the vehicle's linear speed.

[0103] 2) Considering the creep phenomenon between the wheel and rail, according to Newton's second law and the equation of rotation of the wheelset with a fixed axle, the expression for the output axle traction force of the single-moving axle is:

[0104]

[0105] Where m is the mass distributed across the single-moving shaft, f m The resistance is distributed to the single-moving shaft, and m is the mass distributed to the single-moving shaft.

[0106] Step S12: Based on the traction force of the single-drive axle output wheel and the motion equation of the traction motor, calculate the actual load torque of the motor during the actual operation of the train, specifically as follows:

[0107] 1) For the traction motor, the equation of motion is:

[0108]

[0109] Among them, T m T is the output torque of the traction motor. L ω represents the actual load torque of the traction motor. m The mechanical angular velocity of the traction motor;

[0110] 2) Gears have a transmission efficiency that satisfies:

[0111] T L =F wm r g1 =F mw r g1 / η Gear (5)

[0112] Among them, F mw The force exerted by the motor on the driven wheel through the driving wheel, r g1 Let η be the radius of the driving gear. Gear For gear transmission efficiency;

[0113] 3) The actual load torque of the motor is expressed as:

[0114]

[0115] In the formula, J w η is the sum of the rotational inertia of the wheelset and the driven mechanism. Gear For gear transmission efficiency, i g Where M is the gear ratio, R is the total mass of the vehicle group, and N is the radius of the driven wheel. m ω is the number of traction motors, γ is the creep rate, and ω is the creep rate. m ω is the angular mechanical speed of the traction motor; f is the total resistance of the vehicle formation.

[0116] During actual train operation, creep only occurs when the wheels spin or slide, and therefore can be ignored under normal operating conditions. From the above equations, the actual load torque of the motor can be obtained as follows:

[0117]

[0118] In the formula, J w R is the sum of the rotational inertia of the wheelset and the driven mechanism; R is the radius of the driven wheel; η Gear γ is the gear transmission efficiency; γ is the creep rate; i g N is the gear ratio; m ω represents the number of traction motors (driving shafts); M represents the total mass of the vehicle formation; m denoted as angular mechanical speed of the traction motor; f is the total resistance of the train formation. Calculations show that a certain urban rail train using a fixed formation of 4 powered and 2 unpowered carriages has a load torque of approximately 2000 N·m when fully loaded and approximately -1200 N·m during braking.

[0119] 2. Determination of train operation strategy

[0120] Depending on the varying road conditions and transport demands between stations, trains undergo frequent starts and stops. By analyzing the forces acting on the train and its operational process, the train's overall performance throughout the journey can be clearly understood, allowing for the rational planning of operational strategies. Currently, the three most commonly used strategies in practical engineering research are time-saving traction strategies, energy-saving traction strategies, and comfort traction strategies. For example... Figure 1 As shown.

[0121] Time-saving traction strategy: This strategy requires the train to complete the designated section of road in the shortest possible time. The train starts with maximum traction force and reaches its maximum speed V. max Then, it travels at that constant speed for a period of time, and then decelerates with maximum braking force until it stops.

[0122] Energy-saving traction strategy: This requires the train to complete the specified distance with minimal energy loss. In practical engineering applications, it is difficult to achieve the relatively optimal control sequence of "maximum acceleration - constant speed driving - coasting - maximum braking" on every line; instead, the train must accelerate to V with maximum traction force. t Allocate time reasonably in S according to time requirements t1 To S t2 The ratio of constant speed and coasting conditions is determined, and then the maximum braking force is applied for braking.

[0123] Comfort-oriented traction strategy: This requires trains to prioritize passenger comfort. Related research indicates that the maximum acceleration / deceleration range suitable for 80% passenger comfort is 1.2-1.4 m / s². 2 .

[0124] In this embodiment, an energy-saving traction strategy is adopted during train operation, which requires the train to complete the specified section of road in the shortest possible time. The train starts with maximum traction force and reaches its maximum speed V. max Then, it will maintain this constant speed for a period of time, before decelerating to a stop with maximum braking force. The train's maximum speed is 80 km / h, and its acceleration is 1 m / s². 2 .

[0125] 3. Design of the magnetic flux observer

[0126] Vector control of AC asynchronous motors typically employs three methods: rotor field-oriented, air-gap field-oriented, and stator field-oriented. In traditional direct field-oriented control, inaccurate flux amplitude or phase significantly degrades system performance. Rotor field-oriented control allows for complete decoupling of excitation current and torque current, thus achieving complete decoupling of field control and torque control.

[0127] The design process of the magnetic flux observer is as follows Figure 2 As shown.

[0128] A rotor flux linkage observer based on the dq-axis coordinate system, where the d-axis coincides with the rotor flux linkage vector, is called a synchronously rotating orthogonal coordinate system oriented according to the rotor flux linkage. The voltage equation in the dq-axis coordinate system is:

[0129]

[0130] In the formula, u sd i sd ψ sd These represent the components of stator voltage, current, and flux linkage along the d-axis, respectively. sq i sq ψ sq These represent the components of stator voltage, current, and flux linkage along the q-axis, respectively. The components of rotor voltage, current, and flux linkage along the dq-axis are similar to those of the stator. ω is the rotor speed, and ω1 is the angular velocity relative to the stator's dq-axis.

[0131] The flux linkage equation in the dq coordinate system is:

[0132]

[0133] In the formula, L s For the self-inductance of the equivalent two windings of the stator, L r L is the self-inductance of the rotor's equivalent two windings. m It refers to the mutual inductance between the coaxial equivalent windings of the stator and rotor.

[0134] The torque equation in the dq coordinate system is:

[0135]

[0136] The rotational angular velocity ω1 of the dq rotating coordinate system is:

[0137]

[0138] The difference between the rotational angular velocity ω1 of the coordinate system and the rotor speed ω is defined as the slip ω. s :

[0139]

[0140] From the state equation

[0141]

[0142] The rotor flux linkage ψ can be derived. r for:

[0143]

[0144] Where p is the differential operator d / dt; T r Electromagnetic time constant: T r =L r / R r R r The resistance is the equivalent resistance of the two windings of the rotor.

[0145] The integral of ω1 yields the rotational transformation angle θ within the motor. The design of the flux linkage observer is as follows: Figures 1-5 As shown.

[0146] Rotor flux ψ r And synchronous angular velocity ω1:

[0147]

[0148]

[0149] The integral of ω1 yields the rotational transformation angle θ within the motor. Based on this, a flux linkage observer can be designed.

[0150] 4. Control method for asynchronous motors of urban rail trains based on flux linkage observer

[0151] The load torque of the asynchronous motor of the urban rail train is determined; the operation strategy of the urban rail train is classified, and the train operation strategy is determined in combination with different road conditions and transportation needs; based on the flux linkage observer, the control system of the asynchronous motor of the urban rail train is constructed. The specific steps are as follows:

[0152] 1) Implementation of the SVPWM algorithm, such as Figure 3 As shown, the specific steps include:

[0153] Step 1: Coordinate Transformation

[0154] The purpose of coordinate transformation is to convert an AC motor model into an equivalent DC motor model. This transformation greatly simplifies the analysis and control of the motor. Commonly used coordinate transformations include the Clarke transformation and the Park transformation.

[0155] The Clarke transformation is the transformation from a three-phase coordinate system ABC to a two-phase orthogonal coordinate system αβ. The transformation formula is:

[0156]

[0157] The Park transformation transforms a stationary two-phase orthogonal coordinate system αβ into a rotating orthogonal coordinate system dq. The transformation formula is:

[0158]

[0159] Step 2: Sector Determination

[0160] The space vector formed by the three-phase voltages output by the inverter is:

[0161]

[0162] Define the following reference variables:

[0163]

[0164] Redefining:

[0165] The specific correspondence between the sector value N = A + 2B + 4C and the sector number S is shown in Table 1:

[0166] Table 1

[0167] Sector value N 3 1 5 4 6 2

[0168] Step 3: Calculation of Action Time

[0169] During a switching cycle T0, at a certain moment, the voltage vector u s If you rotate to a certain position in the first sector, then u s It can be obtained from different combinations of two adjacent non-zero vectors U1, U2 and the zero vector U0 in time in this region. Let the time of action of the three be t1, t2, t0 respectively. According to the principle of balance equivalence, we can obtain:

[0170] U s T0=U1t1+U2t2+U0t0 (21)

[0171] Where T0 = t1 + t2 + t0.

[0172] Define the following reference variables:

[0173] The values ​​of t1, t2, and t0 within each sector can be obtained, as shown in Table 2:

[0174] Table 2

[0175] t1 Z Y -Z -X X -Y t2 Y -X X Z -Y -Z

[0176] The SVPWM signal can be output by calculating the sector vector switching point using the seven-step method.

[0177] 2) The Park transform is obtained by estimating the position in the flux linkage observer. And observe the flux linkage value;

[0178] 3) Build an overall model of the asynchronous motor control system.

[0179] Figure 4 This is an overall control model for an asynchronous motor based on a flux linkage observer.

[0180] Next, a system embodiment of the present invention is given. A control system for an asynchronous motor in urban rail transit based on a flux linkage observer is provided. This system includes modules such as an outer-loop speed regulator (ASR), an inner-loop current regulator (ACR), Park transform and its inverse transform, Clark transform, voltage vector modulation (SVPWM), and a flux linkage observer. It employs speed-current dual closed-loop feedback control, with PI regulators used in both the inner and outer loops. The outer-loop speed regulator (ASR) achieves zero steady-state error control when the speed is stable, while the inner-loop current regulator (ACR) controls the current to follow the output of the speed regulator. In the figure, n * For a given rotational speed, i d * Given the excitation current, i q * Given a torque current, i d i q For the current i after inverse transformation to the dq coordinate system aligned with the rotor flux direction (2s / 2r), α i β Let be the current in the stationary two-phase coordinate system αβ. The rotor flux linkage position angle is denoted as .

[0181] Specifically:

[0182] Acquisition of current signal i from AC motor A i B i C i is obtained after the Clarke transform module α i β After passing through the Park transformation module, i is obtained in the rotated orthogonal coordinate system. d i q ;

[0183] The current signal from the asynchronous motor is input to the flux linkage observer, which outputs the rotor flux linkage observation value. This value is then used by the speed calculation module to calculate the observed speed. The deviation between the given speed and the observed speed value is input to the speed regulator, which outputs the control current. Output current With the collected current i q The deviation is input to the current regulator, which will set the given excitation current. With the collected current i d The deviation is input to the current regulator, and the outputs of the two current regulators are successively regulated by the IPark conversion module and the space vector pulse width modulation (SVPWM) module before being applied to the inverter. The inverter indirectly controls the asynchronous motor, forming a closed-loop control. The implementation of the flux linkage observer is based on the above-mentioned flux linkage observer design method.

[0184] Figures 6-9 The figures shown are the motor speed, motor torque, motor three-phase electronic current, and flux linkage values ​​observed by the flux linkage observer in this embodiment.

[0185] The control method for asynchronous motors of urban rail trains based on flux linkage observers proposed in this invention enables trains to start and stop "on demand" according to actual needs, thereby further improving the traction and braking performance of trains.

[0186] The electronic device of this invention includes a central processing unit (CPU), which can perform various appropriate actions and processes according to computer program instructions stored in read-only memory (ROM) or loaded from a storage unit into random access memory (RAM). The RAM may also store various programs and data required for device operation. The CPU, ROM, and RAM are interconnected via a bus. Input / output (I / O) interfaces are also connected to the bus.

[0187] Multiple components in the device are connected to the I / O interface, including: input units such as keyboards and mice; output units such as various types of displays and speakers; storage units such as disks and optical discs; and communication units such as network interface cards (NICs), modems, and wireless transceivers. The communication unit allows the device to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0188] The processing unit executes the various methods and processes described above, such as methods S1 to S3. For example, in some embodiments, methods S1 to S3 may be implemented as computer software programs tangibly contained in a machine-readable medium, such as a storage unit. In some embodiments, part or all of the computer program may be loaded and / or installed on the device via ROM and / or a communication unit. When the computer program is loaded into RAM and executed by the CPU, one or more steps of methods S1 to S3 described above may be performed. Alternatively, in other embodiments, the CPU may be configured to execute methods S1 to S3 by any other suitable means (e.g., by means of firmware).

[0189] The functions described above in this document can be performed at least in part by one or more hardware logic components. For example, exemplary types of hardware logic components that can be used, without limitation, include: field programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), payload programmable logic devices (CPLDs), and so on.

[0190] The program code used to implement the methods of the present invention can be written in any combination of one or more programming languages. This program code can be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing device, such that when executed by the processor or controller, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code can be executed entirely on the machine, partially on the machine, as a standalone software package partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0191] In the context of this invention, a machine-readable medium can be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. Machine-readable media can include, but are not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0192] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A control method for asynchronous motors in urban rail transit based on a flux linkage observer, characterized in that, The method includes the following steps: Step S1: Based on the wheelset fixed-axis rotation equation, determine the load torque of the urban rail train's asynchronous motor, including the following sub-steps: Step S11: Calculate the traction force of the single-moving axle output wheel based on the wheelset fixed-axis rotation equation; Step S12: Based on the traction force of the single-acting axle output wheel axle and the motion equation of the traction motor, calculate the actual load torque of the motor during the actual operation of the train; The actual load torque of the motor is expressed as: （6） In the formula, It is the sum of the rotational inertia of the wheelset and the driven mechanism. For gear transmission efficiency, This is the gear ratio. This refers to the total mass of the vehicle formation. The radius of the driven wheel, The number of traction motors. For creep rate, The angular mechanical speed of the traction motor; The total resistance of the vehicle formation; Step S2: Combine different road conditions and transportation needs to determine the train operation strategy and obtain the preset speed and acceleration trajectory; The train operation strategy includes a time-saving traction strategy, an energy-saving traction strategy, and a comfort traction strategy. The comfort traction strategy is the highest acceleration / deceleration range that requires the train to prioritize passenger comfort. Step S3: Based on the flux linkage observer, build a control model for the asynchronous motor of the urban rail train, and control the asynchronous motor of the urban rail train according to the preset speed and acceleration trajectory; the control model for the asynchronous motor of the urban rail train is a control model for the asynchronous motor of the urban rail train based on rotor magnetic field orientation control.

2. The method for controlling an asynchronous motor in urban rail transit based on a flux linkage observer according to claim 1, characterized in that, Step S11 specifically involves: 1) Equation of rotation of wheelset on fixed axis: （1） in, The force exerted by the motor on the driven wheel through the driving wheel; The radius of the driven gear; For single-drive shaft output shaft wheel traction force; The radius of the vehicle; It is the sum of the rotational inertia of the wheelset and the driven mechanism; The formula for calculating the angular acceleration of the wheelset rotation is: （2） in, The angular velocity of the wheel. For creep rate, The straight-line speed of the vehicle; 2) Considering the creep phenomenon between the wheel and rail, according to Newton's second law and the equation of rotation of the wheelset with a fixed axle, the expression for the output wheel axle traction force of a single-moving axle is: （3） in, Distribute mass to the single-moving shaft. Distribute resistance to the single-moving shaft. Distribute mass to the single-moving shaft.

3. The method for controlling an asynchronous motor in urban rail transit based on a flux linkage observer according to claim 2, characterized in that, Step S12 includes: 1) For the traction motor, the equation of motion is: （4） in, For the output torque of the traction motor, This represents the actual load torque of the traction motor. The mechanical angular velocity of the traction motor; 2) Gears have a transmission efficiency that satisfies: （5） in, The force exerted by the motor on the driven wheel through the driving wheel. The radius of the driving gear, This refers to the gear transmission efficiency.

4. The method for controlling an asynchronous motor in urban rail transit based on a flux linkage observer according to claim 1, characterized in that, The asynchronous motor control model for urban rail trains in step S3 is a control model for asynchronous motors of urban rail trains based on rotor field-oriented control, specifically as follows: Acquiring current signals from AC motors conduct Transformation In the process Transformation to obtain the rotating orthogonal coordinate system ; The current signal from the asynchronous motor is input to the flux linkage observer, which outputs the rotor flux linkage observation value. This observation value is then used to calculate the speed. The deviation between the given speed and the observed speed value is input to the speed regulator, which outputs the control current. ; Output current With the collected current The deviation is input to the current regulator, which will set the given excitation current. With the collected current The deviation is input to the current regulator, and the outputs of the two current regulators are successively processed by IPark transformation and space vector pulse width modulation (SVPWM) before being applied to the inverter. The inverter then indirectly controls the asynchronous motor, forming a closed-loop control.

5. The method for controlling an asynchronous motor in urban rail transit based on a flux linkage observer according to claim 4, characterized in that, The magnetic flux observer is based on The rotor flux linkage observer in the axis coordinate system makes The shaft and rotor flux linkage vectors coincide, forming a synchronous rotating orthogonal coordinate system oriented according to the rotor flux linkage: 1) The voltage equation in the coordinate system is: （7） In the formula, These are stator voltage, current, and flux linkage, respectively. Components of the axis, These are stator voltage, current, and flux linkage, respectively. The components of the axis; These are rotor voltage, current, and flux linkage. Components of the axis, These are rotor voltage, current, and flux linkage. The components of the axis; The rotor speed, For relative to the stator Angular velocity of the coordinate axes; These are the resistances of the two equivalent windings of the stator and the resistances of the two equivalent windings of the rotor, respectively. 2) The flux linkage equation is: （8） In the formula, For the self-inductance of the two equivalent stator windings, The self-inductance of the rotor is equivalent to the two windings. The mutual inductance between the coaxial equivalent windings of the stator and rotor; 3) Calculate the rotor flux linkage based on the voltage equation and flux linkage equation. and synchronous angular velocity : （9） （10） Synchronous angular velocity The rotational transformation angle inside the asynchronous motor is obtained after integration. .

6. The method for controlling an asynchronous motor in urban rail transit based on a flux linkage observer according to claim 4, characterized in that, The Space Vector Pulse Width Modulation (SVPWM) process is specifically as follows: 1) Transform the AC motor model into an equivalent DC motor model; 2) Perform sector identification: The space vector formed by the three-phase voltages output by the inverter is: （11） Define reference variables and constraints to obtain sector values. With sector number Specific correspondences; 3) Calculate the duration of action: One switching cycle At a certain moment, the voltage vector If rotated to a certain position in the first sector, then It can be determined by two adjacent non-zero vectors in this region. and zero vector Different combinations of time are obtained, let the duration of action of the three be respectively. According to the principle of equilibrium equivalence, we can obtain: （12） in, ; Define a reference variable: （13） Get each sector The value; The sector vector switching point is calculated using a seven-step method to output the space vector pulse width modulation (SVPWM) signal.

7. The method for controlling an asynchronous motor in urban rail transit based on a flux linkage observer according to claim 6, characterized in that, The defined reference variables and constraints are used to obtain the sector values. With sector number The specific correspondence is as follows: Define the reference variable as: （14） The constraints are satisfied: （15） Get sector value With sector number The specific correspondence.

8. The method for controlling an asynchronous motor in urban rail transit based on a flux linkage observer according to claim 1, characterized in that, The train operation strategies in step S2 include time-saving traction strategy, energy-saving traction strategy, and comfort traction strategy.

9. A control system for asynchronous motors in urban rail transit based on a flux linkage observer, characterized in that, The system includes: Acquiring current signals from AC motors go through The transformation module obtains After The transformation module obtains the rotational orthogonal coordinate system. ; The current signal from the asynchronous motor is input to the flux linkage observer, which outputs the rotor flux linkage observation value. This value is then used by the speed calculation module to calculate the observed speed. The deviation between the given speed and the observed speed value is input to the speed regulator, which outputs the control current. ; Output current With the collected current The deviation is input to the current regulator, which will set the given excitation current. With the collected current The deviation is input to the current regulator. The outputs of the two current regulators are successively adjusted by the IPark conversion module and the space vector pulse width modulation (SVPWM) module and then applied to the inverter. The inverter indirectly controls the asynchronous motor to form a closed-loop control. The implementation of the magnetic flux observer is based on the method described in claim 6.

Images