Robust sliding mode current control method and system for permanent magnet motor long-line driving system

Abstract

The invention discloses a robust sliding mode current control method and system for a permanent magnet motor long-line driving system, and belongs to the field of power electronics and power transmission. Firstly, a state variable of a system is sampled, and a filter inductance current benchmark reference is calculated by using steady-state characteristics of a filter capacitor voltage dynamic model; then, a high-pass filter is used for extracting a resonance current component, and a filtering inductive current resonance suppression reference is calculated; establishing a filter inductive current discrete state equation by using a second-order Taylor expansion method; designing a discrete sliding mode switching function matrix based on the filter inductive current resonance suppression reference tracking error; obtaining a robust sliding mode control instruction based on the discrete sliding mode switching function matrix; and the robust sliding mode control instruction is converted into an alpha-beta coordinate system through Park inverse transformation, and the alpha-beta coordinate system is sent to a space vector modulation module to generate a pulse signal to be applied to an inverter. According to the method, the resonance phenomenon of the permanent magnet motor long-line driving system can be effectively suppressed, and the robustness of the system to mismatch disturbance of the stator inductance parameters is improved.

Description

Technical Field

[0001] The invention relates to a robust sliding mode current control method and system for a permanent magnet motor long-line drive system, and belongs to the field of power electronics and electric transmission. Background Art

[0002] Permanent magnet synchronous motors are widely used in industrial manufacturing, energy mining, aerospace and other fields due to their simple structure, compact size and high power factor. In oil field drilling, coal transportation and other fields, the inverter is connected to the permanent magnet motor through an LC filter and a long-distance cable for power supply, forming a permanent magnet motor long-line drive system to prevent the permanent magnet motor from being damaged by overvoltage. However, the LC filter and the motor stator inductance form an LCL third-order filter system, which will cause resonance instability problems.

[0003] The traditional control method for the long-distance drive system of a permanent magnet motor is to use proportional-integral control plus resonant damping control. Under complex working conditions, the stator inductance parameters of the permanent magnet motor itself will change, resulting in parameter mismatch. Since the proportional-integral control method in the prior art is not equipped with any control items to resist parameter mismatch, the optimal operating point is offset, thereby greatly reducing the robustness to parameter mismatch; in contrast, sliding mode control, as a commonly used nonlinear control strategy, has a natural robustness to system parameter changes and external disturbances. Despite this, the existing sliding mode control methods are all designed for conventional permanent magnet motor drive systems without LC filters. Because their current inner loop is designed based on the stator current vector control framework, it is easily affected by stator inductance parameter mismatch and resonant instability. In addition, there are essential differences in the structure between conventional permanent magnet motor drive systems and permanent magnet motor long-distance drive systems, which makes the existing sliding mode control methods unsuitable for permanent magnet motor long-distance drive systems.

[0004] The prior art with publication number CN115118190A discloses a permanent magnet motor intelligent control drive system, including an input module, a human-machine intelligent interaction platform, a voice recognition module, a fault diagnosis module, a fault warning module, a control algorithm module, a motor test bench module and an energy conversion module, and each module is connected by a flexible combination topology structure; at the same time, a permanent magnet motor loss control method based on an improved whale optimization algorithm is provided, including building a FOC control system and inputting motor parameters, collecting motor operation signals, deriving loss expressions, optimizing the improved whale optimization algorithm, coordinate transformation and motor minimum loss control. Its structure is complex, and it needs to use an artificial intelligence interaction platform, which has high requirements for computing power and energy, and slow control response speed. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a robust sliding mode current control method and system for a permanent magnet motor long-line drive system. By designing a discrete sliding mode switching function matrix based on filter current resonance suppression reference tracking to obtain a reference sliding mode control instruction, the resonance instability phenomenon can be effectively suppressed. The robust sliding mode control instruction is calculated in combination with the switching control instruction with a variable gain coefficient, which solves the problem that when the stator inductance parameters of the traditional proportional-integral control are mismatched, the operating point is offset, thereby reducing the robustness and stability.

[0006] To achieve the above technical objectives, the present invention provides a robust sliding mode current control method for a permanent magnet motor long-line drive system, the steps of which are as follows:

[0007] Use sensors to collect system information of the permanent magnet motor long-line drive system at time k;

[0008] The filter capacitor voltage dynamics model of the permanent magnet motor long-line drive system in the dq axis rotating coordinate system is established using the system information, and the filter inductor current reference is calculated using the filter capacitor voltage dynamics model;

[0009] Extracting the resonant current component in the filter capacitor voltage, and subtracting the resonant current component from the filter inductor current reference, to obtain a filter inductor current resonance suppression reference without the resonant current component;

[0010] The discrete sliding mode switching function matrix at time k and time k+1 is calculated;

[0011] Since the discrete sliding mode switching function matrix remains unchanged in the neighborhood near the sliding surface, the discrete sliding mode switching function matrix at time k is equal to that at time k+1, and the reference sliding mode control command is calculated;

[0012] Based on the discrete sliding mode switching function matrix at time k, a switching control instruction based on a variable gain coefficient is designed, and the switching control instruction is superimposed on the reference sliding mode control instruction to calculate a robust sliding mode control instruction;

[0013] The robust sliding mode control instructions are transformed by Park inverse transformation to obtain the robust sliding mode control instructions of αβ axis, which are converted into pulses to act on the inverter switch tube using the principle of space vector pulse width modulation to realize the robust sliding mode current control of the permanent magnet motor long-line drive system.

[0014] Further, the permanent magnet motor long-line drive system includes a DC bus voltage V connected in series dc , three-phase voltage source inverter, three-phase LC filter, long-distance cable and permanent magnet synchronous motor, three-phase LC filter including filter inductor L f And filter capacitor C f ; System information includes the filter inductance L collected at time k using voltage and current sensors fThe three-phase current i fa 、i fb and i fc , filter capacitor C f The three-phase voltage u sa 、u sb and u sc , the three-phase stator current i of the permanent magnet synchronous motor sa 、i sb 、i sc State variables, and the use of photoelectric encoders to collect the rotor electrical angle θ e The outer speed loop is regulated according to the traditional proportional integral, while the inner current loop adopts the robust sliding mode current control method.

[0015] Furthermore, the filter capacitor voltage dynamics model in the dq axis rotating coordinate system of the permanent magnet motor long-line drive system is as follows:

[0016] ;

[0017] In the formula, C f Represents the filter capacitor, u sd 、u sq Represents the dq axis filter capacitor voltage, and Indicates the rate of change of the dq-axis filter capacitor voltage, i fd 、i fq represents the dq axis filter inductor current, i sd 、i sq Represents the stator current of the dq-axis motor; ω e Represents the electrical angular velocity of the motor, which is determined by the rotor electrical angle θ e Taking the derivative with respect to time, we get;

[0018] Based on the property that the filter capacitor voltage has a zero rate of change when in steady state, that is: and Both are 0, and the filter inductor current reference is calculated through the filter capacitor voltage dynamics model:

[0019] ;

[0020] In the formula, and It is the reference of dq axis filter inductor current; and To realize the dq axis stator current reference of the vector control of the permanent magnet synchronous motor, Set to 0, is the output of the speed loop; k represents the k sampling time of the sensor.

[0021] Furthermore, according to the principle that the high-pass filter only allows high-frequency signals to pass, the resonant current component in the filter capacitor voltage is expressed as follows:

[0022] ;

[0023] In the formula, k and k-1 represent the k sampling time and k-1 sampling time respectively. and is the dq axis resonant current component, u sd 、u sq is the dq axis filter capacitor voltage, T s is the sampling period of each sensor, f c is the cutoff frequency of the high-pass filter;

[0024] By using the principle that the high-pass filter only allows high-frequency signals to pass, the resonant current component in the filter capacitor voltage is extracted, and the resonant current component is subtracted from the filter inductor current reference to obtain the filter inductor current resonance suppression reference without the resonant current component:

[0025] ;

[0026] In the formula, and is the dq axis filter inductor current resonance suppression reference, is the damping coefficient used to adjust the resonance suppression strength, which is taken as 0.707; and is the dq-axis resonant current component at the k sampling moment.

[0027] Furthermore, the filter inductor current resonance suppression reference and the dq-axis filter inductor current at time k are subtracted to obtain the discrete sliding mode switching function matrix at time k, which is expressed as follows:

[0028] ;

[0029] In the formula, is the discrete sliding mode switching function matrix at time k, and is the dq-axis component of the discrete sliding mode switching function matrix at time k; and is the dq axis filter inductor current resonance suppression reference, and is the filter inductor current collected at time k;

[0030] Recursively push s(k) at time k forward one step to obtain the discrete sliding mode switching function matrix at time k+1, which is expressed as follows:

[0031] ;

[0032] Among them, i fd (k+1) and i fq (k+1) is the dq-axis filter inductor current at time k+1 obtained by discretization based on the second-order Taylor series expansion. The specific expression is as follows:

[0033] ;

[0034] In the formula, the coefficient matrices A, B, F, and G are respectively:

[0035] ; where k and k+1 represent the k time and k+1 sampling time respectively, and is the filter inductor current, and is the dq axis inverter output voltage, u sd 、u sq is the dq axis filter capacitor voltage, i sd 、i sq is the stator current of the dq-axis motor, T s is the sampling period, L f Represents the filter inductance, C f Represents the filter capacitor, ω e Indicates the electrical angular velocity of the motor.

[0036] Further, according to the principle that the discrete sliding mode switching function matrix will remain unchanged in the neighborhood near the sliding surface, that is, the discrete sliding mode switching function matrix s(k) at time k is equal to the discrete sliding mode switching function matrix s(k+1) at time k+1, and the reference sliding mode control instruction is calculated as follows:

[0037] ;

[0038] In the formula, is the reference sliding mode control command at time k, I is the second-order unit matrix, A, B -1 , F, G are coefficient matrices.

[0039] Furthermore, the switching control instruction based on the variable gain coefficient is designed based on the discrete sliding mode switching function matrix at time k as follows:

[0040] ;

[0041] In the formula, is the switching control instruction at time k; and is the dq-axis component of the discrete sliding mode switching function matrix at time k; and is the gain coefficient that adaptively decays with the sliding mode switching function at time k, ε is greater than 0, according to The upper bound of the maximum parameter mismatch perturbation of each matrix coefficient in is set; e is the base of the natural logarithm, represents a symbolic function;

[0042] Switch control command With the reference sliding mode control instruction The correct robust control instructions can be obtained by superimposing them. The robust sliding mode control instructions are as follows:

[0043] ;

[0044] In the formula, is the robust sliding mode control command at time k.

[0045] Furthermore, the robust sliding mode control instructions are obtained according to the Park inverse transform, and the αβ axis robust sliding mode control instructions are as follows:

[0046] ;

[0047] In the formula, is the robust sliding mode control command of the αβ axis at time k, and are the α and β axis components of the robust sliding mode control command, is the Park inverse transformation matrix, θ e is the rotor electrical angle.

[0048] Furthermore, the robust sliding mode current control method for a permanent magnet motor long-line drive system is stored in a memory of a computer device, and the computer device also includes a processor for executing the robust sliding mode current control method for a permanent magnet motor long-line drive system.

[0049] A robust sliding mode current control system for a permanent magnet motor long-line drive system, comprising a sensor detection unit, a Park conversion unit and a robust sliding mode current control unit, wherein the robust sliding mode current control unit comprises a filter inductor current reference calculation unit, a filter inductor current resonance suppression reference unit, a discrete sliding mode switching function matrix, a robust sliding mode control instruction calculation unit, a Park inverse conversion unit and a space vector modulation unit connected in sequence;

[0050] The sensor detection unit is used to obtain the filter inductance L at the time k collected by the voltage and current sensors in the permanent magnet motor long-line drive system. f The three-phase current, filter capacitor C f The three-phase voltage of the permanent magnet synchronous motor, the three-phase stator current state variables, and the use of a photoelectric encoder to collect the rotor electrical angle θ e ;

[0051] Park transformation unit, used to transform the data in the abc three-phase coordinate system into the dq axis rotating coordinate system;

[0052] A filter inductor current reference calculation unit calculates a filter inductor current reference through a filter capacitor voltage dynamics model steady-state characteristic;

[0053] A filter inductor current resonance suppression reference unit, which uses a high-pass filter to extract the resonance current component and calculate the filter inductor current resonance suppression reference;

[0054] A discrete sliding mode switching function matrix is ​​used to design a discrete sliding mode switching function matrix based on the filter inductor current resonance suppression reference tracking error;

[0055] A robust sliding mode control command calculation unit calculates a robust sliding mode control command for controlling a permanent magnet motor long-line drive system using a discrete sliding mode switching function matrix;

[0056] Park inverse transformation unit, used to transform the robust sliding mode control command into αβ coordinate system through Park inverse transformation;

[0057] The space vector modulation unit is used to generate a pulse signal for controlling the inverter in the long-line drive system of the magnetic motor.

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] The present invention obtains a reference sliding mode control instruction based on a discrete sliding mode switching function matrix of filter current resonance suppression reference tracking, which can effectively suppress resonance in a permanent magnet motor long-line drive system; the method and system have simple use steps and are easy to use, can quickly obtain a reference sliding mode control instruction of the control system and combine it with a switching control instruction of a variable gain coefficient, thereby ensuring the robustness and stability of the permanent magnet motor long-line drive system when a stator inductance parameter mismatch occurs. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 It is a schematic block diagram of a robust sliding mode current control method for a permanent magnet motor long-line drive system of the present invention;

[0061] Figure 2 is the stator inductance parameter L of the permanent magnet motor in the traditional proportional integral control method s Schematic diagram of the motor speed, electromagnetic torque, d-axis stator current, q-axis stator current, and three-phase stator current dynamic and steady-state performance when 50% mismatch occurs;

[0062] Figure 3 is the stator inductance parameter L of the permanent magnet motor in the embodiment of the present invention sSchematic diagram of the motor speed, electromagnetic torque, d-axis stator current, q-axis stator current, and three-phase stator current dynamic and steady-state performance when 50% mismatch occurs. DETAILED DESCRIPTION

[0063] To make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0064] The present invention discloses a robust sliding mode current control method for a permanent magnet motor long-line drive system, and the permanent magnet motor long-line drive system used is as follows: Figure 1 As shown, the DC bus voltage V dc The three-phase voltage source inverter converts it into AC voltage, and then connects it to the permanent magnet motor through a three-phase LC filter. f Connected in series with the inverter output side, each phase filter capacitor C f One end and filter inductor L f The output sides are connected together, and the other ends are connected together to form a star connection. The three-phase filter inductor current i at time k is collected in sequence fa 、i fb and i fc , three-phase filter capacitor voltage u sa 、u sb and u sc , the three-phase stator current i of the permanent magnet synchronous motor sa 、i sb 、i sc State variables and rotor electrical angle θ e The rotor electrical angle θ e It is used for Park transformation and Park inverse transformation. The speed loop still uses the traditional proportional integral method for regulation, and the current inner loop uses the robust sliding mode current control method provided by the present invention.

[0065] Figure 1 In, V dc Indicates DC bus voltage; L f Represents the filter inductance, C f represents the filter capacitor, θ e is the electrical angle of the motor rotor; d / dt represents the derivative link, which is used to calculate the electrical angular velocity ω of the rotor e ;ω e * is the motor rotor electrical angular velocity reference; i sd * 、i sq * Indicates the dq axis stator current reference; u d (k) and u q (k), i fd(k) and i fq (k),u sd (k) and u sq (k), i sd (k) and i sq (k) respectively represent the dq axis inverter output voltage, filter inductor current, filter capacitor voltage and stator current obtained after Park transformation; i fd * 、i fq * Represents the dq axis filter inductor current reference; i fdh * 、i fqh * represents the dq axis filter inductor current resonance suppression reference; s(k) and s(k+1) represent the discrete sliding mode switching function matrix at time k and k+1 respectively; u dq ref (k) represents the robust sliding mode control command of dq axis; u αβ ref (k) represents u dq ref (k) Robust sliding mode control instructions of the αβ axes obtained after Park inverse transform.

[0066] A robust sliding mode current control method for a permanent magnet motor long-line drive system comprises the following steps:

[0067] S1. Use sensors to collect system information of the permanent magnet motor long-line drive system at time k; the system information includes the filter inductance L collected at time k by using voltage and current sensors f The three-phase current i fa 、i fb and i fc , filter capacitor C f The three-phase voltage u sa 、u sb and u sc , the three-phase stator current i of the permanent magnet synchronous motor sa 、i sb 、i sc State variables, and the use of photoelectric encoders to collect the rotor electrical angle θ e The outer speed loop is regulated according to the traditional proportional integral, while the inner current loop adopts the robust sliding mode current control method.

[0068] S2. Use system information to establish a filter capacitor voltage dynamics model in the dq axis rotating coordinate system of the permanent magnet motor long-line drive system, and use the filter capacitor voltage dynamics model to calculate the filter inductor current reference; the filter capacitor voltage dynamics model in the dq axis rotating coordinate system of the permanent magnet motor long-line drive system is as follows:

[0069] ;

[0070] In the formula, C f Represents the filter capacitor, u sd 、u sq Represents the dq axis filter capacitor voltage, and Indicates the rate of change of the dq-axis filter capacitor voltage, i fd 、i fq represents the dq axis filter inductor current, i sd 、i sq Represents the stator current of the dq-axis motor; ω e Represents the electrical angular velocity of the motor, which is determined by the rotor electrical angle θ e Taking the derivative with respect to time, we get;

[0071] Based on the property that the filter capacitor voltage has a zero rate of change when in steady state, that is: and Both are 0, and the filter inductor current reference is calculated through the filter capacitor voltage dynamics model:

[0072] ;

[0073] In the formula, and It is the reference of dq axis filter inductor current; and To realize the dq axis stator current reference of the vector control of the permanent magnet synchronous motor, Set to 0, is the output of the speed loop; k represents the k sampling time of the sensor.

[0074] S3, extract the resonant current component in the filter capacitor voltage, and subtract the resonant current component from the filter inductor current reference, to obtain a filter inductor current resonance suppression reference without the resonant current component; according to the principle that the high-pass filter only allows high-frequency signals to pass, the resonant current component in the filter capacitor voltage is expressed as follows:

[0075] ;

[0076] In the formula, k and k-1 represent the k-time and k-1-time sampling respectively. and is the dq axis resonant current component, u sd 、u sq is the dq axis filter capacitor voltage, T s is the sampling period of each sensor, f c is the cutoff frequency of the high-pass filter;

[0077] By using the principle that the high-pass filter only allows high-frequency signals to pass, the resonant current component in the filter capacitor voltage is extracted, and the resonant current component is subtracted from the filter inductor current reference to obtain the filter inductor current resonance suppression reference without the resonant current component:

[0078] ;

[0079] In the formula, and is the dq axis filter inductor current resonance suppression reference, is the damping coefficient used to adjust the resonance suppression strength, which is taken as 0.707; and is the dq-axis resonant current component at the k sampling moment.

[0080] S4, calculate and obtain the discrete sliding mode switching function matrix at time k and time k+1;

[0081] The filter inductor current resonance suppression reference and the dq-axis filter inductor current at time k are subtracted to obtain the discrete sliding mode switching function matrix at time k, which is expressed as follows:

[0082] ;

[0083] In the formula, is the discrete sliding mode switching function matrix at time k, and is the dq-axis component of the discrete sliding mode switching function matrix at time k; and is the dq axis filter inductor current resonance suppression reference, and is the filter inductor current collected at time k;

[0084] Recursively push s(k) at time k forward one step to obtain the discrete sliding mode switching function matrix at time k+1, which is expressed as follows:

[0085] ;

[0086] Among them, i fd (k+1) and i fq (k+1) is the dq-axis filter inductor current at time k+1 obtained by discretization based on the second-order Taylor series expansion. The specific expression is as follows:

[0087] ;

[0088] In the formula, the coefficient matrices A, B, F, and G are respectively:

[0089] ; where k and k+1 represent the k time and k+1 sampling time respectively, and is the filter inductor current, and is the dq axis inverter output voltage, u sd 、u sq is the dq axis filter capacitor voltage, i sd 、i sq is the stator current of the dq-axis motor, T s is the sampling period, L f Represents the filter inductance, C f Represents the filter capacitor, ω e Indicates the electrical angular velocity of the motor.

[0090] S5. Since the discrete sliding mode switching function matrix remains unchanged in the neighborhood near the sliding surface, the discrete sliding mode switching function matrix at time k is equal to that at time k+1, and the reference sliding mode control instruction is calculated;

[0091] According to the principle that the discrete sliding mode switching function matrix will remain unchanged in the neighborhood near the sliding surface, that is, the discrete sliding mode switching function matrix s(k) at time k is equal to the discrete sliding mode switching function matrix s(k+1) at time k+1, the reference sliding mode control instruction is calculated as follows:

[0092] ;

[0093] In the formula, is the reference sliding mode control command at time k, I is the second-order unit matrix, A, B -1 , F, G are coefficient matrices.

[0094] S6. Based on the discrete sliding mode switching function matrix at time k, design a switching control instruction based on a variable gain coefficient, and superimpose the switching control instruction with the reference sliding mode control instruction to calculate a robust sliding mode control instruction;

[0095] According to the principle that the discrete sliding mode switching function matrix will remain unchanged in the neighborhood near the sliding surface, the switching control instruction based on the variable gain coefficient is designed based on the discrete sliding mode switching function matrix at time k as follows:

[0096] ;

[0097] In the formula, is the switching control instruction at time k; and is the dq-axis component of the discrete sliding mode switching function matrix at time k; and is the gain coefficient that adaptively decays with the sliding mode switching function at time k, ε is greater than 0, according to The upper bound of the maximum parameter mismatch perturbation of each matrix coefficient in is set; e is the base of the natural logarithm, represents a symbolic function;

[0098] Switch control command With the reference sliding mode control instruction The correct robust control instructions can be obtained by superimposing them. The robust sliding mode control instructions are as follows:

[0099] ;

[0100] In the formula, is the robust sliding mode control command at time k.

[0101] S7, performing Park inverse transformation on the robust sliding mode control instruction to obtain the αβ axis robust sliding mode control instruction, converting it into a pulse to act on the inverter switch tube using the space vector pulse width modulation principle, and realizing the robust sliding mode current control of the permanent magnet motor long-line drive system;

[0102] The robust sliding mode control instructions are obtained according to the Park inverse transform. The αβ axis robust sliding mode control instructions are as follows:

[0103] ;

[0104] In the formula, is the robust sliding mode control command of the αβ axis at time k, and are the α and β axis components of the robust sliding mode control command, is the Park inverse transformation matrix, θ e is the rotor electrical angle.

[0105] A computer device comprises a processor and a memory, wherein the processor is electrically connected to the memory, the memory is used to store instructions and data, and the processor is used to execute a robust sliding mode current control method for a permanent magnet motor long-line drive system.

[0106] A computer-readable storage medium, characterized in that a computer program is stored in the computer-readable storage medium, and the computer program is suitable for being loaded and executed by a processor for a robust sliding mode current control method for a permanent magnet motor long-line drive system.

[0107] A robust sliding mode current control system for a permanent magnet motor long-line drive system, comprising a sensor detection unit, a Park conversion unit and a robust sliding mode current control unit, wherein the robust sliding mode current control unit comprises a filter inductor current reference calculation unit, a filter inductor current resonance suppression reference unit, a discrete sliding mode switching function matrix, a robust sliding mode control instruction calculation unit, a Park inverse conversion unit and a space vector modulation unit connected in sequence; Sensor detection unit, used to obtain voltage and current sensor data in permanent magnet motor long-line drive system k Filter inductance at the moment L f The three-phase current, filter capacitor C f The three-phase voltage of the permanent magnet synchronous motor, the three-phase stator current state variables, and the use of photoelectric encoders to collect the rotor electrical angle θ e ; Park transformation unit, used to transform the data in the abc three-phase coordinate system into the dq axis rotating coordinate system; A filter inductor current reference calculation unit calculates a filter inductor current reference through a filter capacitor voltage dynamics model steady-state characteristic; A filter inductor current resonance suppression reference unit, which uses a high-pass filter to extract the resonance current component and calculate the filter inductor current resonance suppression reference; A discrete sliding mode switching function matrix is ​​used to design a discrete sliding mode switching function matrix based on the filter inductor current resonance suppression reference tracking error; A robust sliding mode control command calculation unit calculates a robust sliding mode control command for controlling a permanent magnet motor long-line drive system using a discrete sliding mode switching function matrix; Park inverse transformation unit, used to transform the robust sliding mode control command into αβ coordinate system through Park inverse transformation; The space vector modulation unit is used to generate a pulse signal for controlling the inverter in the long-line drive system of the magnetic motor.

[0108] In order to verify the robust sliding mode current control method of the permanent magnet motor long-line drive system provided by the present invention, the method is applied to an embodiment of the permanent magnet motor long-line drive system. The parameters in the embodiment are shown in Table 1:

[0109] Table 1

[0110] ;

[0111] Figure 2 and Figure 3 The reference speed is 1000 rpm, the load torque is 4.5Nm, and the stator inductance L of the permanent magnet motor is sThe performance comparison waveforms from startup to steady state of the traditional proportional-integral control and the method proposed in the present invention when 50% parameter mismatch occurs, from top to bottom are the motor speed, electromagnetic torque, d-axis stator current, q-axis stator current and three-phase stator current.

[0112] from Figure 2 and Figure 3 It can be seen that although the system speed can reach 1000rpm under traditional control, at this time due to L s The parameter mismatch caused obvious resonance oscillation. The ripple of the dq axis stator current was very large and it was impossible to accurately track its reference value. The torque T e In contrast, the control method of the present invention does not involve any stator inductance and has a variable gain switching control item specifically used to resist parameter mismatch, so it can be used in L s In the event of 50% parameter mismatch, the dq axis stator current can always maintain excellent tracking performance. s Parameter mismatch shows strong robustness and no resonance phenomenon occurs. It can be seen that this method can ensure the strong robustness and stability of the permanent magnet motor long-line drive system.

Claims

1. A robust sliding mode current control method for a permanent magnet motor long-line drive system, characterized in that: Here are the steps: Use sensors to collect system information of the permanent magnet motor long-line drive system at time k; The filter capacitor voltage dynamics model of the permanent magnet motor long-line drive system in the dq axis rotating coordinate system is established using the system information, and the filter inductor current reference is calculated using the filter capacitor voltage dynamics model; Extracting the resonant current component in the filter capacitor voltage, and subtracting the resonant current component from the filter inductor current reference, to obtain a filter inductor current resonance suppression reference without the resonant current component; The discrete sliding mode switching function matrix at time k and time k+1 is calculated; Since the discrete sliding mode switching function matrix remains unchanged in the neighborhood near the sliding surface, the discrete sliding mode switching function matrix at time k is equal to that at time k+1, and the reference sliding mode control command is calculated; Based on the discrete sliding mode switching function matrix at time k, a switching control instruction based on a variable gain coefficient is designed, and the switching control instruction is superimposed on the reference sliding mode control instruction to calculate a robust sliding mode control instruction; The robust sliding mode control instructions are transformed by Park inverse transformation to obtain the robust sliding mode control instructions of αβ axis, which are converted into pulses to act on the inverter switch tube using the principle of space vector pulse width modulation to realize the robust sliding mode current control of the permanent magnet motor long-line drive system.

2. The robust sliding mode current control method for a permanent magnet motor long-line drive system according to claim 1, characterized in that: The permanent magnet motor long-line drive system includes a DC bus voltage V dc , three-phase voltage source inverter, three-phase LC filter, long-distance cable and permanent magnet synchronous motor, three-phase LC filter including filter inductor L f And filter capacitor C f ; System information includes the filter inductance L collected at time k using voltage and current sensors f The three-phase current i fa 、i fb and i fc , filter capacitor C f The three-phase voltage u sa 、u sb and u sc , the three-phase stator current i of the permanent magnet synchronous motor sa 、i sb 、i sc State variables, and the use of photoelectric encoders to collect the rotor electrical angle θ e The outer speed loop is regulated according to the traditional proportional integral, while the inner current loop adopts the robust sliding mode current control method.

3. The robust sliding mode current control method for a permanent magnet motor long-line drive system according to claim 2 is characterized in that: The filter capacitor voltage dynamics model in the dq axis rotating coordinate system of the permanent magnet motor long-line drive system is as follows: ； In the formula, C f Represents the filter capacitor, u sd 、u sq Represents the dq axis filter capacitor voltage, and Indicates the rate of change of the dq-axis filter capacitor voltage, i fd 、i fq represents the dq axis filter inductor current, i sd 、i sq Represents the stator current of the dq-axis motor; ω e Represents the electrical angular velocity of the motor, which is determined by the rotor electrical angle θ e Taking the derivative with respect to time, we get; Based on the property that the filter capacitor voltage has a zero rate of change when in steady state, that is: and Both are 0, and the filter inductor current reference is calculated through the filter capacitor voltage dynamics model: ； In the formula, and It is the reference of dq axis filter inductor current; and To realize the dq axis stator current reference of the vector control of the permanent magnet synchronous motor, Set to 0, is the output of the speed loop; k represents the k sampling time of the sensor.

4. The robust sliding mode current control method for a permanent magnet motor long-line drive system according to claim 3 is characterized in that: According to the principle that the high-pass filter only allows high-frequency signals to pass, the resonant current component in the filter capacitor voltage is expressed as follows: ； In the formula, k and k-1 represent the k sampling time and k-1 sampling time respectively. and is the dq axis resonant current component, u sd 、u sq is the dq axis filter capacitor voltage, T s is the sampling period of each sensor, f c is the cutoff frequency of the high-pass filter; By using the principle that the high-pass filter only allows high-frequency signals to pass, the resonant current component in the filter capacitor voltage is extracted, and the resonant current component is subtracted from the filter inductor current reference to obtain the filter inductor current resonance suppression reference without the resonant current component: ； In the formula, and is the dq axis filter inductor current resonance suppression reference, is the damping coefficient used to adjust the resonance suppression strength, which is taken as 0.707; and is the dq-axis resonant current component at the k sampling moment.

5. The robust sliding mode current control method for a permanent magnet motor long-line drive system according to claim 4 is characterized in that: The filter inductor current resonance suppression reference and the dq-axis filter inductor current at time k are subtracted to obtain the discrete sliding mode switching function matrix at time k, which is expressed as follows: ； In the formula, is the discrete sliding mode switching function matrix at time k, and is the dq-axis component of the discrete sliding mode switching function matrix at time k; and is the dq axis filter inductor current resonance suppression reference, and is the filter inductor current collected at time k; Recursively push s(k) at time k forward one step to obtain the discrete sliding mode switching function matrix at time k+1, which is expressed as follows: ； Among them, i fd (k+1) and i fq (k+1) is the dq-axis filter inductor current at time k+1 obtained by discretization based on the second-order Taylor series expansion. The specific expression is as follows: ； In the formula, the coefficient matrices A, B, F, and G are respectively: ; where k and k+1 represent the k time and k+1 sampling time respectively, and is the filter inductor current, and is the dq axis inverter output voltage, u sd 、u sq is the dq axis filter capacitor voltage, i sd 、i sq is the stator current of the dq-axis motor, T s is the sampling period, L f Represents the filter inductance, C f Represents the filter capacitor, ω e Indicates the electrical angular velocity of the motor.

6. The method for robust sliding mode current control of a permanent magnet motor long-line drive system according to claim 5, characterized in that: According to the principle that the discrete sliding mode switching function matrix will remain unchanged in the neighborhood near the sliding surface, that is, the discrete sliding mode switching function matrix s(k) at time k is equal to the discrete sliding mode switching function matrix s(k+1) at time k+1, the reference sliding mode control instruction is calculated as follows: ； In the formula, is the reference sliding mode control command at time k, I is the second-order unit matrix, A, B -1 , F, G are coefficient matrices.

7. The method for robust sliding mode current control of a permanent magnet motor long-line drive system according to claim 6, characterized in that: The switching control instruction based on the variable gain coefficient is expressed as follows: ； In the formula, is the switching control instruction at time k; and is the dq-axis component of the discrete sliding mode switching function matrix at time k; and is the gain coefficient that adaptively decays with the sliding mode switching function at time k, ε is greater than 0, according to The upper bound of the maximum parameter mismatch perturbation of each matrix coefficient in is set; e is the base of the natural logarithm, represents a symbolic function; Switch control command With the reference sliding mode control instruction The correct robust control instructions can be obtained by superimposing them. The robust sliding mode control instructions are as follows: ； In the formula, is the robust sliding mode control command at time k.

8. The method for robust sliding mode current control of a permanent magnet motor long-line drive system according to claim 7, characterized in that: The robust sliding mode control instructions are obtained according to the Park inverse transform. The αβ axis robust sliding mode control instructions are as follows: ； In the formula, is the robust sliding mode control command of the αβ axis at time k, and are the α and β axis components of the robust sliding mode control command, is the Park inverse transformation matrix, θ e is the rotor electrical angle.

9. The robust sliding mode current control method for a permanent magnet motor long-line drive system according to claim 8, characterized in that: The robust sliding mode current control method for a permanent magnet motor long-line drive system is stored in a memory of a computer device, and the computer device also includes a processor for executing the robust sliding mode current control method for a permanent magnet motor long-line drive system.

10. A robust sliding mode current control system for a permanent magnet motor long-line drive system, characterized in that: It includes a sensor detection unit, a Park conversion unit and a robust sliding mode current control unit, wherein the robust sliding mode current control unit includes a filter inductor current reference calculation unit, a filter inductor current resonance suppression reference unit, a discrete sliding mode switching function matrix, a robust sliding mode control instruction calculation unit, a dq / αβ conversion unit and a space vector modulation unit connected in sequence; The sensor detection unit is used to obtain the filter inductance L at the time k collected by the voltage and current sensors in the permanent magnet motor long-line drive system. f The three-phase current, filter capacitor C f The three-phase voltage of the permanent magnet synchronous motor, the three-phase stator current state variables, and the use of a photoelectric encoder to collect the rotor electrical angle θ e ; Park transformation unit, used to transform the data in the abc three-phase coordinate system into the dq axis rotating coordinate system; A filter inductor current reference calculation unit calculates a filter inductor current reference through a filter capacitor voltage dynamics model steady-state characteristic; A filter inductor current resonance suppression reference unit, which uses a high-pass filter to extract the resonance current component and calculate the filter inductor current resonance suppression reference; A discrete sliding mode switching function matrix is ​​used to design a discrete sliding mode switching function matrix based on the filter inductor current resonance suppression reference tracking error; A robust sliding mode control command calculation unit calculates a robust sliding mode control command for controlling a permanent magnet motor long-line drive system using a discrete sliding mode switching function matrix; A dq / αβ conversion unit, used to transform the robust sliding mode control command into the αβ coordinate system through the Park inverse transformation; The space vector modulation unit is used to generate a pulse signal for controlling the inverter in the long-line drive system of the magnetic motor.

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