Asynchronous motor control method and control system based on ESO rotor flux observation

Abstract

An asynchronous motor control method and control system based on ESO rotor flux observation, the method: by establishing the stator current and rotor flux state equations of the squirrel cage asynchronous motor in a stationary coordinate system; constructing the stator current estimation extended state equation; constructing the ESO rotor flux observer on the basis of the rotor flux state equation and the constructed stator current estimation extended state equation, after obtaining the rotor flux estimation component by using the obtained ESO rotor flux observer, obtaining the rotor flux phase information by inverse tangent transformation, and feeding it back to the system to form a closed-loop control, using the rotor flux voltage model as a reference model and the ESO rotor flux observer as an adjustable model to complete the construction of the speed estimator; the system includes a controller module, a pulse width modulation module, a rotor flux observer module, a voltage model module and a rotor speed estimator module. The present invention can simplify the design structure of the extended state observer and improve the control accuracy.

Description

Technical Field

[0001] The present invention relates to an asynchronous motor control method and control system based on ESO rotor flux observation, belonging to the technical field of motor control. Background Art

[0002] Asynchronous motors are widely used in electric vehicles and industrial production due to their simple structure, easy manufacturing, low price, reliable operation and convenient maintenance. With the development of control technology, vector control has become one of the most widely used control strategies in asynchronous motors today. However, high-performance vector control technology often requires high-precision rotor flux position and speed feedback information, which brings certain challenges to the control of asynchronous motors.

[0003] Traditional methods usually use encoders to obtain rotor position and speed feedback information. However, in special working environments such as hydroelectric power stations, the stability of the encoder is easily affected by uncertain factors such as air humidity, dust and temperature changes. At the same time, high-precision code disks are generally expensive, which adds a certain cost to the design of asynchronous motor structures. Therefore, encoderless control has become a hot spot in the development of asynchronous motor research today. At present, the common methods for obtaining rotor flux position and speed feedback are voltage model flux observer and extended state observer. Among them, the voltage model flux observer has the problem of integral drift caused by back electromotive force, while the extended state observer does not rely on the system model and can eliminate the influence of integral drift. Therefore, it has received widespread attention from researchers. However, the existence of traditional nonlinear fal functions not only increases the difficulty of system design, but also affects the estimation accuracy of stator current and rotor flux components. Summary of the invention

[0004] In view of the problems existing in the above-mentioned prior art, the present invention provides an asynchronous motor control method and control system based on ESO rotor flux observation. The method and system can not only simplify the design structure of the extended state observer and improve the control accuracy, but also reduce the manufacturing cost.

[0005] In order to achieve the above object, the present invention provides an asynchronous motor control method based on ESO rotor flux observation, comprising the following steps:

[0006] S1. Establish the stator current and rotor flux state equations of the squirrel cage asynchronous motor in the stationary coordinate system;

[0007] S2. Based on the stator current state equation, the state expansion variable is designed according to the error between the actual value and the estimated value of the stator current in the α and β axes, and the stator current estimation expansion state equation is constructed;

[0008] S3. Based on the rotor flux state equation and the stator current estimation extended state equation constructed in step S2, construct an ESO rotor flux observer;

[0009] S4. After obtaining the rotor flux estimation component using the ESO rotor flux observer obtained in step S3, the flux phase information is obtained by inverse tangent transformation and fed back to the system to form a closed-loop control;

[0010] S5. Using the rotor flux voltage model as the reference model and the ESO rotor flux observer as the adjustable model, the speed estimator is constructed.

[0011] Furthermore, the stator current and rotor flux state equations of the squirrel cage asynchronous motor in the stationary coordinate system are established in S1 as follows:

[0012]

[0013]

[0014] In the formula, i sα ,i sβ are the α and β axis components of the stator current, L m is the mutual inductance, ψ ra、 ψ rβ are the α and β axis components of the rotor flux, u sα ,u sβ are the α and β axis components of the stator voltage, L s is the stator self-inductance, L r is the rotor self-inductance, R s , R r They are stator resistance and rotor resistance respectively, σ=1-L m 2 / L s L r is the magnetic leakage coefficient, T r =L r / R r is the rotor electromagnetic time constant, ω r is the rotor speed.

[0015] Furthermore, the step of constructing the stator current estimation extended state equation in S2 is:

[0016] S2.1. Based on the stator current state equation, the state expansion variable is designed according to the error between the actual value and the estimated value of the stator current in the α and β axes. The expression is as follows:

[0017]

[0018] Where b1 and b2 are adjustment coefficients, and b1>0, b2>0; z11 is the error design variable of the stator current in the α axis, z 12 is the design variable for the stator current error in the β axis.

[0019] S2.2. Substitute the expanded variables designed in S2.1 into the stator current state equation to construct the stator current estimation expanded state equation, which is expressed as follows:

[0020]

[0021] From the above formula, it can be obtained that the designed expanded state variable replaces the nonlinear term of the fal function in the original expanded state, simplifying the design structure of the current system while retaining the nonlinear advantage.

[0022] Furthermore, the steps for constructing the ESO flux observer in S3 are:

[0023] S3.1. Based on the stator current estimation expanded state equation, the estimated stator current data is used to construct the expanded variable again, and its expression is as follows:

[0024]

[0025] In the formula, r is the adjustment coefficient, and r>0;

[0026] S3.2. Substitute the expanded variables constructed again in S3.1 into the rotor flux state equation, and the expression of the ESO rotor flux observer is obtained as follows:

[0027]

[0028] In the formula, is the estimated component of the α and β axes of the rotor flux; z 21 is the error design variable of the rotor flux in the α axis, z 22 is the design variable for the rotor flux error in the β axis.

[0029] It can be seen from the ESO rotor flux observer obtained above that it uses extended variables to replace the nonlinear term of the fal function in the original extended state observer, which simplifies the system structure; at the same time, the measured rotor flux component is only related to the stator current error, eliminating the influence of integral drift caused by the existence of rotor back electromotive force in the traditional voltage model, and improving the control accuracy of the system.

[0030] Furthermore, after the rotor flux estimation component is obtained by using the obtained ESO rotor flux observer in S4, the expression of the estimated rotor flux phase is obtained by inverse tangent transformation as follows:

[0031]

[0032] In the formula, To estimate the rotor flux phase, it is sent to the Park transformation to realize the transformation between the rotating coordinate system and the stationary coordinate system.

[0033] Furthermore, the steps of constructing the speed estimator in S5 are:

[0034] S5.1. The expression of the rotor flux voltage model is as follows:

[0035]

[0036] S5.2. Using the rotor flux voltage model in S5.1 as the reference model and the ESO rotor flux observer as the adjustable model, the expression of the speed estimator is obtained as follows:

[0037]

[0038] In the formula, is the estimated rotor speed; k1 is the proportional adjustment coefficient, k2 is the integral adjustment coefficient, and s is the integral.

[0039] The present invention also provides an asynchronous motor control system based on ESO rotor flux observation, comprising a controller module, a pulse width modulation module, a rotor flux observer module, a voltage model module and a rotor speed estimator module.

[0040] The controller module includes a speed controller and a current controller, the speed controller adopts a pi controller with output limiting, and the current controller adopts feedforward decoupling control;

[0041] The pulse width modulation module controls the switching on and off of the thyristors in the three-phase inverter to achieve inversion after receiving the SVPWM control signal;

[0042] The rotor flux observer module adopts the ESO algorithm, uses the error information between the α-axis and β-axis stator currents to design expansion variables, and substitutes the obtained error design variables into the flux model to complete the estimation of the required rotor flux components;

[0043] The voltage model module solves the actual components of the rotor flux in the α and β axes based on the voltage state equation;

[0044] The rotor speed estimator module, based on the voltage model module and the rotor flux observer module, forms an adaptive rate according to the information between the actual value and the estimated value of the rotor flux in the α and β axes, and realizes the estimation of the rotor speed through the adjustment of the controller.

[0045] The present invention establishes the stator current and rotor flux state equations of the squirrel cage asynchronous motor in a stationary coordinate system, designs state expansion variables based on the stator current state equation according to the error between the actual value and the estimated value of the stator current in the α and β axes, constructs the stator current estimation expansion state equation, constructs an ESO rotor flux observer on the basis of the rotor flux state equation and the constructed stator current estimation expansion state equation, obtains the rotor flux estimation component by using the obtained ESO rotor flux observer, obtains the flux phase information by inverse tangent transformation, and feeds it back to the system to form a closed-loop control, takes the rotor flux voltage model as a reference model, and the ESO rotor flux observer as an adjustable model, and finally completes the construction of the speed estimator, maintains the advantages of the nonlinear traditional expanded state observer, only needs to solve the information value of the current error, simplifies the complexity of the traditional nonlinear control rate, improves the control accuracy of the system, and eliminates the problem of integral drift of the traditional voltage model; at the same time, the scheme does not need to use sensors, which significantly reduces the manufacturing cost of the asynchronous motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 is a control system block diagram of the present invention;

[0047] Figure 2 It is a schematic diagram of the rotor flux module structure of the present invention;

[0048] Figure 3 1 is a simulation result diagram of the actual value and estimated value of the stator current α axis of an embodiment of the present invention;

[0049] Figure 4 1 is a simulation result diagram of the actual value and estimated value of the stator current β axis of an embodiment of the present invention;

[0050] Figure 5 : is a simulation result diagram of the actual value and estimated value of the rotor flux α axis according to an embodiment of the present invention;

[0051] Figure 6 : is a simulation result diagram of actual value and estimated value of rotor flux β axis according to an embodiment of the present invention;

[0052] Figure 7 : is a diagram showing the simulation result of the error between the actual value and the estimated value of the rotor flux α axis according to an embodiment of the present invention;

[0053] Figure 8 It is a diagram showing the simulation results of the error between the actual value and the estimated value of the rotor flux β axis in an embodiment of the present invention. DETAILED DESCRIPTION

[0054] The present invention will be further described below in conjunction with the accompanying drawings.

[0055] like Figure 1As shown, the control system based on the present invention includes a controller module, a pulse width modulation module, a rotor flux observer module, a voltage model module and a rotor speed estimator module.

[0056] The controller module includes a speed controller and a current controller, the speed controller adopts a pi controller with output limiting, and the current controller adopts feedforward decoupling control;

[0057] The pulse width modulation module controls the switching on and off of the thyristors in the three-phase inverter to achieve inversion after receiving the SVPWM control signal;

[0058] The rotor flux observer module adopts the ESO algorithm, uses the error information between the α-axis and β-axis stator currents to design expansion variables, and substitutes the obtained error design variables into the flux model to complete the estimation of the required rotor flux components;

[0059] The voltage model module solves the actual components of the rotor flux in the α and β axes based on the voltage state equation;

[0060] The rotor speed estimator module, based on the voltage model module and the rotor flux observer module, forms an adaptive rate according to the information between the actual value and the estimated value of the rotor flux in the α and β axes, and realizes the estimation of the rotor speed through the adjustment of the controller.

[0061] like Figure 2 As shown, it is a working flow chart of the control method of the present invention, an asynchronous motor control method based on ESO rotor flux observation, comprising the following steps:

[0062] S1. Establish the stator current and rotor flux state equations of the squirrel cage asynchronous motor in the stationary coordinate system;

[0063] S2. Based on the stator current state equation, the state expansion variable is designed according to the error between the actual value and the estimated value of the stator current in the α and β axes, and the stator current estimation expansion state equation is constructed;

[0064] S3. Based on the rotor flux state equation and the stator current estimation extended state equation constructed in step S2, construct an ESO rotor flux observer;

[0065] S4. After obtaining the rotor flux estimation component using the ESO rotor flux observer obtained in step S3, the flux phase information is obtained by inverse tangent transformation and fed back to the system to form a closed-loop control;

[0066] S5. Using the rotor flux voltage model as the reference model and the ESO rotor flux observer as the adjustable model, the speed estimator is constructed.

[0067] Furthermore, the stator current and rotor flux state equations of the squirrel cage asynchronous motor in the stationary coordinate system are established in S1 as follows:

[0068]

[0069]

[0070] In the formula, i sα ,i sβ are the α and β axis components of the stator current, L m is the mutual inductance, ψ ra , rβ are the α and β axis components of the rotor flux, u sα ,u sβ are the α and β axis components of the stator voltage, L s is the stator self-inductance, L r is the rotor self-inductance, R s , R r They are stator resistance and rotor resistance respectively, σ=1-L m 2 / L s L r is the magnetic leakage coefficient, T r =L r / R r is the rotor electromagnetic time constant, ω r is the rotor speed.

[0071] Furthermore, the step of constructing the stator current estimation extended state equation in S2 is:

[0072] S2.1. Based on the stator current state equation, the state expansion variable is designed according to the error between the actual value and the estimated value of the stator current in the α and β axes. The expression is as follows:

[0073]

[0074] Where b1 and b2 are adjustment coefficients, and b1>0, b2>0; z 11 is the error design variable of the stator current in the α axis, z 12 is the design variable for the stator current error in the β axis.

[0075] S2.2. Substitute the expanded variables designed in S2.1 into the stator current state equation to construct the stator current estimation expanded state equation, which is expressed as follows:

[0076]

[0077] From the above formula, it can be obtained that the designed expanded state variable replaces the nonlinear term of the fal function in the original expanded state, simplifying the design structure of the current system while retaining the nonlinear advantage.

[0078] Furthermore, the steps for constructing the ESO flux observer in S3 are:

[0079] S3.1. Based on the stator current estimation expanded state equation, the estimated stator current data is used to construct the expanded variable again, and its expression is as follows:

[0080]

[0081] In the formula, r is the adjustment coefficient, and r>0;

[0082] S3.2. Substitute the expanded variables constructed again in S3.1 into the rotor flux state equation, and the expression of the ESO rotor flux observer is obtained as follows:

[0083]

[0084] In the formula, Supplement for the estimated components of the α and β axes of the rotor flux: 21 is the error design variable of the rotor flux in the α axis, z 22 is the design variable for the rotor flux error in the β axis.

[0085] It can be seen from the ESO rotor flux observer obtained above that it uses extended variables to replace the nonlinear term of the fal function in the original extended state observer, which simplifies the system structure; at the same time, the measured rotor flux component is only related to the stator current error, eliminating the influence of integral drift caused by the existence of rotor back electromotive force in the traditional voltage model, and improving the control accuracy of the system.

[0086] Furthermore, after the rotor flux estimation component is obtained by using the obtained ESO rotor flux observer in S4, the expression of the estimated rotor flux phase is obtained by inverse tangent transformation as follows:

[0087]

[0088] In the formula, To estimate the rotor flux phase, it is sent to the Park transformation to realize the transformation between the rotating coordinate system and the stationary coordinate system.

[0089] Furthermore, the steps of constructing the speed estimator in S5 are:

[0090] S5.1. The expression of the rotor flux voltage model is as follows:

[0091]

[0092] S5.2. Using the rotor flux voltage model in S5.1 as the reference model and the ESO rotor flux observer as the adjustable model, the expression of the speed estimator is obtained as follows:

[0093]

[0094] In the formula, is the estimated rotor speed; k1 is the proportional adjustment coefficient, k2 is the integral adjustment coefficient, and s is the integral.

[0095] Embodiment: The parameters of the asynchronous motor used in this embodiment are shown in Table 1:

[0096] Table 1 Asynchronous motor parameters

[0097] Rated power / kW 380 Rated voltage / V 1.1 <![CDATA[Moment of inertia / kg·m 2 > 0.18 Stator resistance / Ω 0.435 Rotor resistance / Ω 0.816 Stator leakage inductance / H 0.0018 Rotor leakage inductance / H 0.0018 Mutual inductance / H 0.069

[0098] Build a simulation model of the asynchronous motor in the MATLAB / Simulink simulation platform and set the bandwidth parameter of the ESO to W. ob =20π, according to the bandwidth parameter b1=2W ob , b2=W ob 2 ;

[0099] Figure 3 and Figure 4 The simulation result diagram of the actual value and estimated value of the stator current in the α and β axes; Figure 5 and Figure 6 The simulation result diagrams of the actual and estimated values ​​of the rotor flux in the α and β axes respectively; Figure 7 and Figure 8 The simulation results of the actual value and estimated value error of the rotor flux in the α and β axes are shown in Figure 2. Figure 7 and Figure 8 It can be seen that the error between the true value and the error value of the rotor flux measured by the ESO rotor flux observer based on the present invention is within the range of 0.01Wb.

[0100] It can be seen from the above simulation results that the asynchronous motor is controlled based on the improved ESO flux observation of the present invention, the system control accuracy is improved, and the problem of integral drift of the traditional voltage model is eliminated. At the same time, this solution does not require the use of sensors, which significantly reduces the manufacturing cost of the asynchronous motor.

Claims

1. An asynchronous motor control method based on ESO rotor flux observation, characterized in that: The following steps are involved: S1. Establish the stator current and rotor flux state equations of the squirrel cage asynchronous motor in the stationary coordinate system; S2. Based on the stator current state equation, according to the stator current The error between the actual value and the estimated value of the shaft is used to design the state expansion variable, and the stator current estimation expansion state equation is constructed; the steps of constructing the stator current estimation expansion state equation are: S2.

1. Based on the stator current state equation, according to the stator current The error between the actual value and the estimated value of the axis is the design state expansion variable, which is expressed as follows: ； In the formula, is the adjustment coefficient and satisfies The stator current is The error design variables of the axis, The stator current is Error design variables of the axis; The stator current is Axis component; S2.

2. Substitute the expanded variables designed in S2.1 into the stator current state equation to construct the stator current estimation expanded state equation, which is expressed as follows: ； In the formula, For mutual induction, The rotor flux is Axis component, The stator voltage is Axis component, is the stator self-inductance, is the rotor self-inductance, are the stator resistance and rotor resistance respectively, is the magnetic flux leakage coefficient, is the rotor electromagnetic time constant, is the rotor speed; S3. Based on the rotor flux state equation and the stator current estimation extended state equation constructed in step S2, construct an ESO rotor flux observer; S4. After obtaining the rotor flux estimation component using the ESO rotor flux observer obtained in step S3, the flux phase information is obtained by inverse tangent transformation and fed back to the system to form a closed-loop control; S5. Using the rotor flux voltage model as the reference model and the ESO rotor flux observer as the adjustable model, the speed estimator is constructed. The construction steps of the speed estimator are as follows: S5.

1. The expression of the rotor flux voltage model is as follows: ； S5.

2. Using the rotor flux voltage model in S5.1 as the reference model and the ESO rotor flux observer as the adjustable model, the expression of the speed estimator is obtained as follows: ； In the formula, is the estimated rotor speed; is the proportional adjustment coefficient, is the integral adjustment coefficient, s is the integral.

2. The asynchronous motor control method based on ESO rotor flux observation according to claim 1 is characterized in that: The stator current and rotor flux state equations of the squirrel cage asynchronous motor in the stationary coordinate system are established in S1 as follows: ； ； In the formula, The stator current is Axis component, For mutual induction, The rotor flux is Axis component, The stator voltage is Axis component, is the stator self-inductance, is the rotor self-inductance, are the stator resistance and rotor resistance respectively, is the magnetic flux leakage coefficient, is the rotor electromagnetic time constant, is the rotor speed.

3. The asynchronous motor control method based on ESO rotor flux observation according to claim 1 is characterized in that: The steps for constructing the ESO flux observer in S3 are: S3.

1. Based on the stator current estimation expanded state equation, the estimated stator current data is used to construct the expanded variable again, and its expression is as follows: ； In the formula, is the adjustment coefficient, and ; S3.

2. Substitute the expanded variables constructed again in S3.1 into the rotor flux state equation, and the expression of the ESO rotor flux observer is obtained as follows: ； In the formula, The rotor flux axis estimation component; The rotor flux is The error design variables of the axis, The rotor flux is Error design variables of the axis.

4. The asynchronous motor control method based on ESO rotor flux observation according to claim 3 is characterized in that: After the rotor flux estimation component is obtained by using the obtained ESO rotor flux observer in S4, the expression of the estimated rotor flux phase is obtained by inverse tangent transformation: ； In the formula, To estimate the rotor flux phase, it is sent to the Park transformation to realize the transformation between the rotating coordinate system and the stationary coordinate system.

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