A control method for three-phase squirrel cage asynchronous motor based on anti-disturbance observer

Abstract

A three-phase squirrel cage asynchronous motor control method based on an anti-disturbance observer first constructs a dynamic mathematical model and state space equation of the asynchronous motor in a synchronous rotating orthogonal coordinate system oriented by the rotor flux; based on the state equation of the asynchronous motor, a speed loop disturbance observer, a flux loop disturbance observer, a d-axis current loop disturbance observer, and a q-axis current loop anti-disturbance observer are designed; then a nonlinear controller of the asynchronous motor is designed based on the backstepping control theory; finally, the disturbance observer and the controller are combined to design a speed control strategy based on flux estimation to achieve speed control of the three-phase squirrel cage asynchronous motor. The present invention improves the torque response of the system by integrating the disturbance observer and the nonlinear controller, enhances the operating level of the system under load changes and motor parameter perturbations, improves the robustness of the system, and at the same time improves the complexity of the traditional parameter adjustment method and improves the practicality.

Description

Technical Field

[0001] The present invention relates to the technical field of asynchronous motor control, and in particular to a three-phase squirrel cage asynchronous motor control method based on an anti-disturbance observer. Background Art

[0002] Three-phase squirrel cage asynchronous motors are widely used in many industrial fields due to their durability, simple structure, and reliable operation. In asynchronous motor control technology, with the continuous practical application of vector control theory, asynchronous motor vector control technology is widely favored by decoupling the speed and flux of asynchronous motors in mathematical models.

[0003] The vector control method of asynchronous motor includes two parts: flux loop and speed loop. However, in practical applications, the traditional PI vector control system has problems such as parameter perturbation, poor anti-interference, and cumbersome parameter adjustment. It is easily affected by load changes, motor parameter changes and operating conditions. Therefore, it is difficult to achieve the desired effect under complex operating control requirements.

[0004] Modern control strategies such as sliding mode variable structure control, adaptive control, predictive control and internal model control have received extensive attention in the field of AC motor variable frequency control research. However, the "jittering" phenomenon of sliding mode variable structure control will cause large torque pulsation at low speed for vector control systems; the adaptive algorithm is complex and has a limited operating range, which requires high processor performance; the predictive control algorithm has problems such as low model prediction accuracy, few rolling optimization strategies, and monotonous feedback correction methods; the fixed time constant of the internal model controller has a contradiction between robustness and rapidity. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a three-phase squirrel cage asynchronous motor control method based on an anti-disturbance observer, which solves the problems of parameter perturbation, poor anti-disturbance and complex control existing in traditional control and general advanced control.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0007] A three-phase squirrel cage asynchronous motor control method based on an anti-disturbance observer comprises the following steps:

[0008] Step 1: According to the speed, flux and rotor DC axis current of the three-phase squirrel cage asynchronous motor, a dynamic mathematical model of the three-phase squirrel cage asynchronous motor in a synchronous rotating orthogonal coordinate system oriented by the rotor flux is constructed:

[0009]

[0010] Among them, ω r is the electrical angular velocity of the asynchronous motor rotor, n pis the number of asynchronous motor pole pairs, J is the moment of inertia of the asynchronous motor, L m is the mutual inductance between the stator and rotor of the asynchronous motor, L r is the asynchronous motor rotor self-inductance, is the rotor flux, i sd 、i sq is the d and q axis current on the stator side, T L is the load, R s is the stator resistance, R r is the rotor resistance, L s is the stator self-inductance of the asynchronous motor, σ=1-L m 2 / (L s L r ) is the motor leakage coefficient, ω dq is the rotor flux angular velocity, T r =L r / R r is the rotor time constant, u sd 、u sq is the stator d and q axis voltage;

[0011] Step 2: Let x1 = ω r , x3=i sq ,x4=i sd , we can get the state space equation of the asynchronous motor as follows:

[0012]

[0013] in, J0 is the known moment of inertia of the asynchronous motor, L m0 For the asynchronous motor, the mutual inductance between the stator and rotor is known, L r0 For an asynchronous motor with known rotor self-inductance,

[0014] T r0 is the known rotor time constant of the asynchronous motor, L r0 is the known rotor self-inductance of the asynchronous motor, R r0 is a known rotor resistance, R s0 is the known stator resistance, L s0 For an asynchronous motor with known stator self-inductance, σ0=1-L m0 2 / (L s0 L r0 ) is the known leakage magnetic coefficient of the motor, c2=-ω dq ,

[0015]

[0016]

[0017]

[0018] Step 3, according to the state space equation of the asynchronous motor, the speed loop disturbance observer, the flux loop disturbance observer, the d-axis current loop disturbance observer, and the q-axis current loop anti-disturbance observer are obtained as follows:

[0019]

[0020] Among them, λ1, λ2, λ3, and λ4 are observation coefficients, their values ​​are positive, and the observation intensity is positively correlated with the observation coefficient.

[0021] Step 4: Based on the backstepping control theory, the nonlinear controller of the asynchronous motor is designed as follows:

[0022]

[0023] in, is the expected value of the asynchronous motor torque, is the expected value of the asynchronous motor rotor flux, is the expected value of the q-axis current on the stator side of the asynchronous motor, is the expected value of the d-axis current on the stator side of the asynchronous motor, k1, k2, k3, k4 are control coefficients, their values ​​are positive, and the control strength is positively correlated with the control coefficient.

[0024] Step 5, finally, the disturbance observer and the controller are combined to realize the speed control of the three-phase squirrel cage asynchronous motor based on the speed control strategy of flux estimation; the output torque voltage u is obtained sd and excitation voltage u sq , and then obtain the reference torque voltage and reference excitation voltage to realize the control of the asynchronous motor.

[0025] The present invention provides a three-phase squirrel cage asynchronous motor control method based on an anti-disturbance observer. The method has the following beneficial effects: by integrating the anti-disturbance observer, the backstepping controller and the linear controller, the robustness of the asynchronous motor under load changes and parameter perturbations is improved, and the parameter adjustment method is simplified. The disturbances of the rotation speed, flux linkage, rotor d-axis current and rotor q-axis current are all observed by the disturbance detector, thereby improving the response and robustness, so that the motor angular velocity can be adjusted more quickly and accurately. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the present invention or the technical solutions in the prior art, the drawings required for describing the prior art are briefly introduced below.

[0027] Figure 1It is a structural schematic diagram of the control system of the present invention;

[0028] Figure 2 It is the speed closed loop tracking response curve;

[0029] Figure 3 It is the rotor electrical angle closed-loop tracking response curve;

[0030] Figure 4 It is the flux closed-loop tracking response curve;

[0031] Figure 5 is the rotor q-axis current closed-loop tracking response curve;

[0032] Figure 6 is the rotor d-axis current closed-loop tracking response curve;

[0033] Figure 7 It is the rotor electrical angle loop interference and observation curve;

[0034] Figure 8 is the magnetic link interference and observation curve;

[0035] Fig. 9 is the rotor q-axis current loop interference and observation curve;

[0036] Fig.10 is the rotor d-axis current interference and observation curve;

[0037] Fig.11 is the d-axis and q-axis control voltage variation curve;

[0038] Fig.12 is the load variation curve; DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention.

[0040] The present invention provides a three-phase squirrel cage asynchronous motor control method based on an anti-disturbance observer, comprising the following steps:

[0041] Step 1: According to the speed, flux and rotor DC axis current of the three-phase squirrel cage asynchronous motor, a dynamic mathematical model of the three-phase squirrel cage asynchronous motor in a synchronous rotating orthogonal coordinate system oriented by the rotor flux is constructed:

[0042]

[0043] Among them, ω r is the electrical angular velocity of the asynchronous motor rotor, n p is the number of asynchronous motor pole pairs, J is the moment of inertia of the asynchronous motor, L mis the mutual inductance between the stator and rotor of the asynchronous motor, L r is the asynchronous motor rotor self-inductance, is the rotor flux, i sd 、i sq is the d and q axis current on the stator side, T L is the load, R s is the stator resistance, R r is the rotor resistance, L s is the stator self-inductance of the asynchronous motor, σ=1-L m 2 / (L s L r ) is the motor leakage coefficient, ω dq is the rotor flux angular velocity, T r =L r / R r is the rotor time constant, u sd 、u sq is the stator d and q axis voltage;

[0044] Step 2: Let x1 = ω r , x3=i sq ,x4=i sd , we can get the state space equation of the asynchronous motor as follows:

[0045]

[0046] in, J0 is the known moment of inertia of the asynchronous motor, L m0 For the asynchronous motor, the mutual inductance between the stator and rotor is known, L r0 For an asynchronous motor with known rotor self-inductance, T r0 is the known rotor time constant of the asynchronous motor, L r0 is the known rotor self-inductance of the asynchronous motor, R r0 is a known rotor resistance, R s0 is the known stator resistance, L s0 For an asynchronous motor with known stator self-inductance, σ0=1-L m0 2 / (L s0 L r0 ) is the known leakage magnetic coefficient of the motor, c2=-ω dq ,

[0047]

[0048]

[0049]

[0050] Step 3, according to the state space equation of the asynchronous motor, the rotor electrical angle loop disturbance observer, the flux loop disturbance observer, the d-axis current loop disturbance observer, and the q-axis current loop anti-disturbance observer are obtained as follows:

[0051]

[0052] Among them, λ1, λ2, λ3, and λ4 are observation coefficients, their values ​​are positive, and the observation intensity is positively correlated with the observation coefficient.

[0053] Step 4: Based on the backstepping control theory, the nonlinear controller of the asynchronous motor is designed as follows:

[0054]

[0055] in, is the expected value of the asynchronous motor torque, is the expected value of the asynchronous motor rotor flux, is the expected value of the q-axis current on the stator side of the asynchronous motor, is the expected value of the d-axis current on the stator side of the asynchronous motor, k1, k2, k3, k4 are control coefficients, their values ​​are positive, and the control strength is positively correlated with the control coefficient.

[0056] Step 5, finally, the disturbance observer and the controller are combined to realize the speed control of the three-phase squirrel cage asynchronous motor based on the speed control strategy of flux estimation; the output torque voltage u is obtained sd and excitation voltage u sq , and then obtain the reference torque voltage and reference excitation voltage to realize the control of the asynchronous motor.

[0057] The present invention uses the above method to effectively estimate the uncertainty disturbance caused by model mismatch, parameter perturbation, etc. General advanced control algorithms are often more complicated, while the present invention proposes a flux controller and a current controller based on backstepping control technology, which can complete the adjustment with only one parameter per loop while completing the nonlinear decoupling of the system. At the same time, the disturbance observer and the nonlinear controller in the present invention are fused in a linear manner, and the tracking performance and anti-disturbance performance of the system are relatively independent of each other, and their adjustment effects can be adjusted separately, thereby solving the adjustment complexity of the proportional and integral controllers, reducing the adjustment complexity of the control system, and can meet a wide range of complex working conditions. Therefore, on the basis of backstepping control technology, disturbance observation technology and linear fusion, the present invention realizes the control of asynchronous motors and improves the practicality of advanced control.

[0058] Figure 1This is the control block diagram of the proposed control method. The method obtains a nonlinear controller based on the speed control strategy framework of flux estimation and backstepping control theory, and integrates the rotor electrical angle loop disturbance observer, flux loop disturbance observer, d-axis current loop disturbance observer and q-axis current loop anti-disturbance observer to obtain the d and q-axis voltages required by SVPWM and realize the speed control of the three-phase squirrel cage asynchronous motor.

[0059] Example

[0060] The parameters of a three-phase squirrel cage asynchronous motor are as follows: rated power 18.5kW, rated voltage 380V, rated frequency 51.5Hz, rated torque 118Nm, rated current 35.8A, rated speed 1500rpm, two pairs of poles, rotor inertia J is 0.1117kg.m 2 , R s 0.219Ω, R r 0.166Ω, L s 55.8mH, L r 55.8mH, L m 47.3mH, T r =L r / R r =0.3361,σ=1-L m 2 / (L s L r )=0.2811,n p is 2.

[0061] Step 1: Design and build the system and equations

[0062] According to the speed, flux and rotor AC and DC axis current of the three-phase squirrel cage asynchronous motor, a dynamic mathematical model of the three-phase squirrel cage asynchronous motor in a synchronous rotating orthogonal coordinate system oriented by the rotor flux is constructed:

[0063]

[0064] Among them, ω r is the electrical angular velocity of the asynchronous motor rotor, is the rotor flux, i sd 、i sq is the d and q axis current on the stator side, R s is the stator resistance, R r is the rotor resistance, L s is the stator self-inductance of the asynchronous motor, ω dq

[0065] is the rotor flux angular velocity, u sd 、u sq is the stator d and q axis voltage, T L For load.

[0066] Step 2, J0 is known to be 0.1061 kg.m 2 , R s0 0.208Ω, R r0 0.1577Ω, L s0 53mH, L r0 53mH, L m0 44.9mH, T r0 =L r0 / R r0 =0.3193,σ0=1-L m0 2 / (L s0 L r0 )=0.267. The state space equation is constructed as follows:

[0067] Let x1 = ω r , x3=i sq ,x4=i sd , we can get:

[0068]

[0069] Among them, δ1=17.9051(2.5437-0.1419x2x3-T L ), δ2=0.1566x2+0.7071x4, δ3=1.1357x3+5.8421x1x2-6.8901u sq , δ4=1.1357x4-26.7689x2-6.8901u sd .

[0070] Step 3, based on the asynchronous motor state equation, the rotor electrical angle loop disturbance observer, the flux loop disturbance observer, the d-axis current loop disturbance observer, and the q-axis current loop anti-disturbance observer are designed as follows:

[0071]

[0072] Step 4: Set the desired speed to 1500 rpm.

[0073] but Set the expected flux linkage to 0.8Wb, then Based on the backstepping control theory, the nonlinear controller of the asynchronous motor can be designed as follows:

[0074]

[0075] Step 5, finally, the disturbance observer and the controller are combined to design a speed control strategy based on flux estimation to achieve speed control of the three-phase squirrel cage asynchronous motor; the output torque voltage u is obtained. sd and excitation voltage u sq , and then obtain the reference torque voltage and reference excitation voltage to realize the control of the asynchronous motor.

[0076]

[0077]

[0078] Figure 2 The speed closed-loop tracking response is given, and the torque tracking effect under this control method is given by Figure 2 It can be found that when a load mutation occurs, it can respond quickly and maintain a good stable state, where the dotted line is the expected value and the solid line is the actual value. Figures 3 to 6 They are the rotor electrical angle closed-loop tracking response, flux linkage closed-loop tracking response, rotor q-axis current closed-loop tracking response and rotor d-axis current closed-loop tracking response, respectively. They describe the tracking characteristics of the rotor electrical angle closed-loop, flux linkage closed-loop, rotor q-axis current closed-loop and rotor d-axis current closed-loop. Figures 3 to 6 It can be seen that when the load changes, good transient and steady-state characteristics can be maintained, where the dotted line is the expected value and the solid line is the actual value. Figures 7 to 10 They are speed loop interference and observation, flux loop interference and observation, rotor q-axis current loop interference and observation, and rotor d-axis current interference and observation, which describe the observation effect of the observer on parameter perturbations and unknown load changes in each closed-loop system, where the dotted lines are observed values ​​and the solid lines are actual values. Fig.11 is the d-axis and q-axis control voltage, Fig.12 The load variation curve.

[0079] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A three-phase squirrel cage asynchronous motor control method based on an anti-disturbance observer, characterized in that: The following steps are involved: Step 1: According to the speed, flux and rotor DC axis current of the three-phase squirrel cage asynchronous motor, a dynamic mathematical model of the three-phase squirrel cage asynchronous motor in a synchronous rotating orthogonal coordinate system oriented by the rotor flux is constructed: Among them, ω r is the electrical angular velocity of the asynchronous motor rotor, n p is the number of asynchronous motor pole pairs, J is the moment of inertia of the asynchronous motor, L m is the mutual inductance between the stator and rotor of the asynchronous motor, L r is the asynchronous motor rotor self-inductance, is the rotor flux, i sd 、i sq is the d and q axis current on the stator side, T L is the load, R s is the stator resistance, R r is the rotor resistance, L s is the stator self-inductance of the asynchronous motor, σ=1-L m 2 / (L s L r ) is the motor leakage coefficient, ω dq is the rotor flux angular velocity, T r =L r / R r is the rotor time constant, u sd 、u sq is the stator d and q axis voltage; Step 2: Let x1 = ω r , x3=i sq ,x4=i sd , we can get the state space equation of the asynchronous motor as follows: in, J0 is the known moment of inertia of the asynchronous motor, L m0 For the asynchronous motor, the mutual inductance between the stator and rotor is known, L r0 For an asynchronous motor with known rotor self-inductance, T r0 is the known rotor time constant of the asynchronous motor, L r0 is the known rotor self-inductance of the asynchronous motor, R r0 is a known rotor resistance, R s0 is the known stator resistance, L s0 For an asynchronous motor with known stator self-inductance, σ0=1-L m0 2 / (L s0 L r0 ) is the known leakage magnetic coefficient of the motor, c2=-ω dq , Step 3, according to the state space equation of the asynchronous motor, the speed loop disturbance observer, the flux loop disturbance observer, the d-axis current loop disturbance observer, and the q-axis current loop anti-disturbance observer are obtained as follows: Among them, λ1, λ2, λ3, λ4 are observation coefficients, their values ​​are positive, and the observation intensity is positively correlated with the observation coefficient; Step 4: Based on the backstepping control theory, the nonlinear controller of the asynchronous motor is designed as follows: in, is the expected value of the asynchronous motor torque, is the expected value of the asynchronous motor rotor flux, is the expected value of the q-axis current on the stator side of the asynchronous motor, is the expected value of the d-axis current on the stator side of the asynchronous motor, k1, k2, k3, k4 are control coefficients, their values ​​are positive, and the control strength is positively correlated with the control coefficient; Step 5, finally, the disturbance observer and the controller are combined to realize the speed control of the three-phase squirrel cage asynchronous motor based on the speed control strategy of flux estimation; the output torque voltage u is obtained sd and excitation voltage u sq , and then obtain the reference torque voltage and reference excitation voltage to realize the control of the asynchronous motor.

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