Permanent magnet synchronous motor dead-beat prediction control method based on superspiral sliding mode expansion observer

Abstract

The invention provides a permanent magnet synchronous motor dead-beat prediction control method based on a super-spiral sliding-mode expansion observer, which comprises the following steps: firstly, designing a sliding-mode observer based on a super-spiral theory to carry out primary estimation on unknown disturbances such as parameter perturbation and the like, and then designing an expansion state observer on the basis to carry out secondary estimation on the disturbances; and the estimated values of the two disturbances are used for compensating the predicted current and the output voltage in sequence, so that high-precision and robust current control is realized, and the dynamic and static performance of a control system is improved. Compared with traditional dead-beat predictive control, the method has the advantages of high robustness, low parameter sensitivity, good dynamic performance, no static error and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of deadbeat predictive current control of a surface-mounted permanent magnet synchronous motor, and in particular relates to a deadbeat predictive control method for a permanent magnet synchronous motor based on a super-helical sliding mode expansion observer. Background Art

[0002] Since the stator current of a permanent magnet synchronous motor is directly related to the motor torque, the dynamic and steady-state response of the stator current is of great importance in motor control. In order to improve the performance of the current loop, the existing technology mainly adopts strategies such as hysteresis current control, direct torque control, sliding mode control and current prediction control. Among many strategies, the deadbeat predictive control has the advantages of fast response speed and good followability. It is widely used at this stage, but its actual effect is greatly affected by the accuracy of motor parameters and factors such as torque, speed, temperature, etc. during motor operation, resulting in poor control accuracy. Therefore, the field urgently needs an improved deadbeat current control method that is insensitive to motor parameters and has high accuracy. Summary of the invention

[0003] In view of this, in order to solve the technical problems existing in the art, the present invention provides a deadbeat predictive control method for a permanent magnet synchronous motor based on a super-helical sliding mode expansion observer, which specifically includes the following steps:

[0004] Step 1: For the surface-mounted permanent magnet synchronous motor, ignoring the influence of spatial harmonics, hysteresis loss, eddy current loss, core loss, and temperature frequency factors on the motor parameters, establish the d and q axis voltage equations including the disturbance caused by parameter changes in the synchronous rotating coordinate system;

[0005] Step 2: Using the voltage equation established in step 1 and combining it with the superhelix theory, a superhelix sliding mode observer is established for one-beat-ahead prediction and a primary estimation of disturbances; the actual current is replaced by the observed current in the voltage equation, and the sliding surface, sliding mode control law and sliding mode control function of the superhelix sliding mode disturbance observer are designed; on this basis, the currents of the d and q axes are used as state variables, and the d and q axis control voltages are used as input quantities to obtain the current equation of the superhelix sliding mode observer; the current equation and the sliding mode control function are discretized by first-order forward difference respectively;

[0006] Step 3: Based on the super-helical sliding mode observer, an extended observer is introduced to form a dual observer, and the d-axis and q-axis currents and disturbances are estimated twice using the dual observer current equation after first-order forward difference discretization.

[0007] Step 4: Use the d-axis and q-axis currents obtained by the dual observer and the two estimated disturbance observation values, combined with the sliding mode control function, to implement one-beat delay feedforward compensation for the control voltage to obtain the final current loop output voltage.

[0008] Furthermore, in step 1, the d-axis and q-axis voltage equations of the following form are specifically established:

[0009]

[0010] Among them, u d 、u q 、i d 、i q are the voltage and stator current of the d and q axes respectively, R is the stator resistance, L is the stator inductance of the d and q axes, ω e is the electrical angular velocity, ψ f is the permanent magnet flux linkage, the superscript · is the differential of the corresponding parameter;

[0011] Considering the disturbances caused by temperature changes, magnetic saturation, cross-coupling, internal unmodeled and external unknown interference factors on the motor parameters, the voltage equation is expanded to obtain the following voltage equation containing disturbances:

[0012]

[0013] Among them, f d and f q are the disturbances of the d and q axes, respectively, and F d and F q are the disturbances f d and f q The rate of change.

[0014] Furthermore, in step 2, a super-helical sliding mode disturbance observer of the following form is specifically established:

[0015]

[0016] Among them, the superscript o represents the observed value of the corresponding parameter, U sd and U sq are the sliding mode control functions of the d and q axes, respectively, and g d and g q are the sliding mode control coefficients of the d and q axes respectively;

[0017] The d and q axis currents i d and i q As the control variable, design the linear sliding mode switching surface: s = i o -i;

[0018] The voltage equation containing disturbances and the super-helical sliding mode disturbance observer are combined to obtain the following permanent magnet synchronous motor system error equation:

[0019]

[0020] Among them, e 1 and e 2are the current observation errors of the d and q axes, and e 3 and e 4 are the disturbance observation errors of the d and q axes respectively, and the error terms are:

[0021]

[0022] On this basis, the sliding mode control laws of the d and q axes are designed as follows:

[0023]

[0024] To compensate for the disturbance observation error e of the d and q axes 1 and e 2 To make it converge to 0, the sliding mode control function is designed as:

[0025]

[0026] On this basis, the following current equation of the super spiral sliding mode observer is obtained:

[0027]

[0028] After the first-order forward difference, the following discretization form is obtained:

[0029]

[0030] in, are the observed values ​​of the d-axis and q-axis currents at the kth moment and k+1th moment, respectively. are the observed values ​​of the d-axis and q-axis disturbances at the kth moment and k+1th moment respectively;

[0031] The discretized sliding mode control function and current observation error are as follows:

[0032]

[0033] Furthermore, the specific form of the dual observer current equation established in step 3 is as follows:

[0034]

[0035] Where, the superscript ∧ indicates the quadratic estimate of the corresponding parameter;

[0036] After the first-order forward difference, the following discretization form is obtained:

[0037]

[0038] Among them, c 1 and c 2 are the parameters of the extended observer, respectively.

[0039] Furthermore, in step 4, the d-axis and q-axis currents and disturbance observation values ​​at the kth moment obtained by the dual observer are combined with the sliding mode control function to calculate the d-axis and q-axis voltages at the k+1th moment:

[0040]

[0041] The deadbeat predictive control method for permanent magnet synchronous motor based on superhelical sliding mode expansion observer provided by the present invention first designs a sliding mode observer based on superhelical theory to estimate unknown disturbances such as parameter perturbations, and then designs an expanded state observer on this basis to estimate the disturbances twice, and the estimated values ​​of the two disturbances are used to compensate the predicted current and output voltage successively, thereby realizing high-precision and robust current control, and improving the dynamic and static performance of the control system. Compared with the traditional deadbeat predictive control, the present invention has the advantages of high robustness, low parameter sensitivity, good dynamic performance, and no static error. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A flow chart of the method provided by the present invention;

[0043] Figure 2 It is a comparison chart of test results of traditional deadbeat predictive control DPCC modulation and the method provided by the present invention under conditions of no mismatch and mismatch of motor parameters. DETAILED DESCRIPTION

[0044] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] The present invention provides a permanent magnet synchronous motor deadbeat predictive control method based on a super spiral sliding mode expansion observer, such as Figure 1 As shown, the specific steps include:

[0046] Step 1: For the surface-mounted permanent magnet synchronous motor, ignoring the influence of spatial harmonics, hysteresis loss, eddy current loss, core loss, and temperature frequency factors on the motor parameters, establish the d and q axis voltage equations including the disturbance caused by parameter changes in the synchronous rotating coordinate system;

[0047] Step 2: Using the voltage equation established in step 1 and combining it with the superhelix theory, a superhelix sliding mode observer is established for one-beat-ahead prediction and a primary estimation of disturbances; the actual current is replaced by the observed current in the voltage equation, and the sliding surface, sliding mode control law and sliding mode control function of the superhelix sliding mode disturbance observer are designed; on this basis, the currents of the d and q axes are used as state variables, and the d and q axis control voltages are used as input quantities to obtain the current equation of the superhelix sliding mode observer; the current equation and the sliding mode control function are discretized by first-order forward difference respectively;

[0048] Step 3: Based on the super-helical sliding mode observer, an extended observer is introduced to form a dual observer, and the d-axis and q-axis currents and disturbances are estimated twice using the dual observer current equation after first-order forward difference discretization.

[0049] Step 4: Use the d-axis and q-axis currents obtained by the dual observer and the two estimated disturbance observation values, combined with the sliding mode control function, to implement one-beat delay feedforward compensation for the control voltage to obtain the final current loop output voltage.

[0050] In a preferred embodiment of the present invention, in step 1, the d-axis and q-axis voltage equations of the following form are specifically established:

[0051]

[0052] Among them, u d 、u q 、i d 、i q are the voltage and stator current of the d and q axes respectively, R is the stator resistance, L is the stator inductance of the d and q axes, ω e is the electrical angular velocity, ψ f is the permanent magnet flux linkage, the superscript · is the differential of the corresponding parameter;

[0053] Considering the disturbances caused by temperature changes, magnetic saturation, cross-coupling, internal unmodeled and external unknown interference factors on the motor parameters, the voltage equation is expanded to obtain the following voltage equation containing disturbances:

[0054]

[0055] Among them, f d and f q are the disturbances of the d and q axes, respectively, and F d and F q are the disturbances f d and f q The rate of change.

[0056] In a preferred embodiment of the present invention, in step 2, a super-helical sliding mode disturbance observer of the following form is specifically established:

[0057]

[0058] Among them, the superscript o represents the observed value of the corresponding parameter, U sd and U sq are the sliding mode control functions of the d and q axes, g d and g q are the sliding mode control coefficients of the d and q axes respectively;

[0059] The d and q axis currents i d and i q As the control variable, design the linear sliding mode switching surface: s = i o -i;

[0060] The voltage equation containing disturbances and the super-helical sliding mode disturbance observer are combined to obtain the following permanent magnet synchronous motor system error equation:

[0061]

[0062] Among them, e 1 and e 2 are the current observation errors of the d and q axes, and e 3 and e 4 are the disturbance observation errors of the d and q axes respectively, and the error terms are:

[0063]

[0064] The super-helical sliding mode observer can reduce the high-frequency oscillation of the output signal and suppress the chattering effect. Therefore, on this basis, the d-axis and q-axis sliding mode control laws are designed as follows:

[0065]

[0066] To compensate for the disturbance observation error e of the d and q axes 1 and e 2 To make it converge to 0, the sliding mode control function is designed as:

[0067]

[0068] On this basis, the following current equation of the super spiral sliding mode observer is obtained:

[0069]

[0070] After the first-order forward difference, the following discretization form is obtained:

[0071]

[0072] in, are the observed values ​​of the d-axis and q-axis currents at the kth moment and k+1th moment, respectively. are the observed values ​​of the d-axis and q-axis disturbances at the kth moment and k+1th moment respectively;

[0073] The discretized sliding mode control function and current observation error are as follows:

[0074]

[0075] In a preferred embodiment of the present invention, the specific form of the dual observer current equation established in step 3 is as follows:

[0076]

[0077] Where, the superscript ∧ indicates the quadratic estimate of the corresponding parameter;

[0078] After the first-order forward difference, the following discretization form is obtained:

[0079]

[0080] Among them, c 1 and c 2 are the parameters of the extended observer, respectively.

[0081] In a preferred embodiment of the present invention, in step 4, the d-axis current and the disturbance observation value at the kth moment obtained by the dual observer are combined with the sliding mode control function to calculate the d-axis voltage and the q-axis voltage at the k+1th moment:

[0082]

[0083] In a specific embodiment of the present invention, based on Figure 1 The control framework shown in the figure is used to carry out simulation experiments. Under the conditions of a speed reference of 1500rpm and a sudden load jump disturbance at 0.05 seconds, control simulations are carried out using the traditional deadbeat predictive current control method and the method provided by the present invention. The comparison results are as follows:

[0084] Please see Figure 2 (a) and Figure 2 (b) shows the d-axis and q-axis currents of the two control methods when there is a 1.5-fold mismatch between the motor parameters (including inductance, resistance, and flux) and the control parameters. It can be seen that the q-axis current of the traditional deadbeat predictive control method overshoots and has a steady-state error with the target current; the q-axis current of the deadbeat predictive control method based on the cascaded disturbance state observer has no overshoot, and there is no static error between the d-axis and q-axis currents and the target current; the q-axis current of the method of the present invention has better tracking performance for the target current, the control strategy is less sensitive to the motor model parameters, and has better robustness.

[0085] It should be understood that the size of the serial numbers of the steps in the embodiment of the present invention does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention.

[0086] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A deadbeat predictive control method for a permanent magnet synchronous motor based on a super-helical sliding mode expansion observer, characterized in that: Specifically include the following steps: Step 1: For the surface-mounted permanent magnet synchronous motor, ignoring the influence of spatial harmonics, hysteresis loss, eddy current loss, core loss, and temperature frequency factors on the motor parameters, establish the d and q axis voltage equations including the disturbance caused by parameter changes in the synchronous rotating coordinate system; Step 2: Using the voltage equation established in step 1 and combining it with the superhelix theory, a superhelix sliding mode observer is established for one-beat-ahead prediction and one-time estimation of disturbances; the actual current is replaced by the observed current in the voltage equation, and the sliding surface, sliding mode control law and sliding mode control function of the superhelix sliding mode disturbance observer are designed; on this basis, the current of the d and q axes are used as state variables, and the d and q axis control voltages are used as input quantities to obtain the current equation of the superhelix sliding mode observer; The current equation and the sliding mode control function are discretized by first-order forward difference respectively; Step 3: Based on the super-helical sliding mode observer, an extended observer is introduced to form a dual observer, and the d-axis and q-axis currents and disturbances are estimated twice using the dual observer current equation after first-order forward difference discretization. Step 4: Use the d-axis and q-axis currents obtained by the dual observer and the two estimated disturbance observation values, combined with the sliding mode control function, to implement one-beat delay feedforward compensation for the control voltage to obtain the final current loop output voltage.

2. The method according to claim 1, characterized in that: In step 1, the d and q axis voltage equations are specifically established in the following form: Among them, u d 、u q 、i d 、i q are the voltage and stator current of the d and q axes respectively, R is the stator resistance, L is the stator inductance of the d and q axes, ω e is the electrical angular velocity, ψ f is the permanent magnet flux linkage, the superscript · is the differential of the corresponding parameter; Considering the disturbances caused by temperature changes, magnetic saturation, cross-coupling, internal unmodeled and external unknown interference factors on the motor parameters, the voltage equation is expanded to obtain the following voltage equation containing disturbances: Among them, f d and f q are the disturbances of the d and q axes, respectively, and F d and F q are the disturbances f d and f q The rate of change.

3. The method according to claim 2, characterized in that: In step 2, the following super-helical sliding mode disturbance observer is established: Among them, the superscript o represents the observed value of the corresponding parameter, U sd and U sq are the sliding mode control functions of the d and q axes, respectively, and g d and g q are the sliding mode control coefficients of the d and q axes respectively; The d and q axis currents i d and i q As the control variable, design the linear sliding mode switching surface: s = i o -i; The voltage equation containing disturbances and the super-helical sliding mode disturbance observer are combined to obtain the following permanent magnet synchronous motor system error equation: Among them, e1 and e2 are the current observation errors of the d and q axes respectively, e3 and e4 are the disturbance observation errors of the d and q axes respectively, and the error terms are: On this basis, the sliding mode control laws of the d and q axes are designed as follows: In order to compensate the disturbance observation errors e1 and e2 of the d and q axes and make them converge to 0, the sliding mode control function is designed as follows: On this basis, the following current equation of the super spiral sliding mode observer is obtained: After the first-order forward difference, the following discretization form is obtained: in, are the observed values ​​of the d-axis and q-axis currents at the kth moment and k+1th moment, respectively. are the observed values ​​of the d-axis and q-axis disturbances at the kth moment and k+1th moment respectively; The discretized sliding mode control function and current observation error are as follows:

4. The method according to claim 3, characterized in that: The specific form of the dual observer current equation established in step 3 is as follows: Where, the superscript ∧ indicates the quadratic estimate of the corresponding parameter; After the first-order forward difference, the following discretization form is obtained: Among them, c1 and c2 are the parameters of the extended observer respectively.

5. The method according to claim 4, characterized in that: In step 4, the d-axis and q-axis currents and disturbance observation values ​​obtained by the dual observer at the kth moment are combined with the sliding mode control function to calculate the d-axis and q-axis voltages at the k+1th moment:

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