Measurement noise suppression method of permanent magnet synchronous motor speed regulation system

Abstract

The invention relates to a measurement noise suppression method of a permanent magnet synchronous motor speed regulation system, and belongs to the field of synchronous motor speed regulation system control. A nonlinear extended state observer is designed by utilizing a dynamic equation of a permanent magnet synchronous motor speed regulation system, so that the motor rotating speed and external disturbance can be estimated in real time; a continuous terminal sliding mode controller is designed according to a motor rotating speed observation value and an interference observation value, a rotating speed containing measurement noise is replaced by the rotating speed observation value, and feedforward compensation disturbance is performed in real time, so that the influence of the disturbance on system output is effectively counteracted; meanwhile, the high-frequency switching function is hidden in the high-order derivative of the sliding mode variable, and the chattering phenomenon of traditional sliding mode control is avoided; compared with traditional active disturbance rejection control, the method provided by the invention has higher control precision, smaller rotating speed fluctuation and better measurement noise suppression performance; and after load disturbance, the adjustment time is shorter, the anti-interference capability is stronger, the current pulsation is smaller, and long-time stable operation of the motor is facilitated.

Description

Technical Field

[0001] The invention belongs to the field of synchronous motor speed regulation system control and relates to a measurement noise suppression method for a permanent magnet synchronous motor speed regulation system. Background Art

[0002] Permanent magnet synchronous motors are widely used in industrial fields such as automotive electronics, daily appliances, industrial production lines, and computer numerical control machine tools due to their light weight, high operating efficiency, superior speed regulation performance, and high reliability. In the permanent magnet synchronous motor speed regulation system, a position sensor is usually used to measure the position signal of the motor rotor, and the motor speed is obtained by differential operation. However, since the position sensor inevitably introduces quantization error, the actual calculated motor speed usually contains measurement noise. In recent years, the application of the auto-disturbance rejection control method combining the extended state observer with the feedback controller in the permanent magnet synchronous motor speed regulation system has become increasingly widespread. Compared with the traditional proportional-integral-derivative (PID) controller, the auto-disturbance rejection control method effectively solves the contradiction between "rapidity" and "overshoot" and has better robustness. Generally, increasing the bandwidth of the extended state observer can improve the anti-interference performance of the system, but this approach often weakens the system's measurement noise suppression ability. At present, the most common measurement noise suppression method is to introduce a low-pass filter in the feedback loop and filter out high-frequency measurement noise by adjusting the cutoff frequency of the filter. However, the introduction of a low-pass filter will cause phase lag in the system, thus affecting the dynamic performance and anti-interference ability of the speed control system. Therefore, a measurement noise suppression method for a permanent magnet synchronous motor speed control system is designed to enable the system to have better anti-interference performance while effectively suppressing measurement noise and reducing speed fluctuations. Summary of the invention

[0003] In view of this, the problem to be solved by the present invention is: how to solve the problem that the measurement noise suppression method affects the control performance of the permanent magnet synchronous motor speed control system, and how to make the speed control system take into account both the measurement noise suppression performance and the anti-interference performance.

[0004] In order to achieve the above object, the present invention proposes the following technical solutions:

[0005] A method for suppressing measurement noise of a permanent magnet synchronous motor speed control system comprises the following steps:

[0006] The nonlinear extended state observer is designed using the dynamic equations of the permanent magnet synchronous motor speed control system.

[0007] Collect the three-phase currents abc and convert them into the α-axis current i through Clarke transformation α and the β-axis current i β ; Use Park transformation to transform i αand i β Converted to q-axis current i q and the d-axis current i d ;

[0008] The position sensor collects the motor position signal and calculates the motor speed Ω with measurement noise n and the interval where the rotor is located;

[0009] The speed and disturbance of the permanent magnet synchronous motor are estimated by the nonlinear extended state observer to obtain the motor speed observation value. and interference observations

[0010] According to the motor speed observation value And the interference observation Design continuous terminal sliding mode controller;

[0011] The d-axis voltage u is calculated by the continuous terminal sliding mode controller and the current controller. d and q-axis voltage u q And, with the help of inverse Park transformation, we can get the α-axis voltage u α and β axis voltage u β ;

[0012] The α and β axis voltages are input into the space vector pulse width modulation module, and the switching signals of the six power tubes of the three-phase inverter are calculated to generate the abc three-phase voltages to drive the permanent magnet synchronous motor to rotate.

[0013] Furthermore, the dynamic equation of the permanent magnet synchronous motor speed control system is expressed as:

[0014]

[0015] Where, Ω represents the motor speed, represents the derivative of the motor speed, B represents the viscosity coefficient, J represents the moment of inertia, i q represents the q-axis current, T L Indicates the motor load, K t represents the motor torque constant, expressed as:

[0016]

[0017] Among them, n p1 represents the number of motor pole pairs, ψ f1 represents the permanent magnet flux, so the dynamic equation is expressed as:

[0018]

[0019] Among them, d t represents the total disturbance to the system, Indicates the reference current.

[0020] The nonlinear extended state observer is expressed as:

[0021]

[0022] in, represents the observed value of motor speed, represents the interference observation value, represents the derivative of the motor speed observation, represents the derivative of the disturbance observation, λ1, λ2 represent the observer coefficients related to the observer bandwidth, Ω n represents the motor speed with measurement noise, and b represents the internal parameters of the motor, which can be expressed as:

[0023]

[0024] Among them, n p1 represents the number of motor pole pairs, ψ f1 represents the permanent magnet flux, J represents the moment of inertia, represents the reference current;

[0025] Nonlinear functions and It can be expressed as:

[0026]

[0027] Among them, γ1, γ2 represent the coefficients of the nonlinear function, γ1 = 1 + ε, γ2 = 1 - ε, and the constant ε ∈ (-0.5, 0), indicates |·| i sgn(i), sgn(i) is:

[0028]

[0029] Further, the steps of designing a continuous terminal sliding mode controller are:

[0030] The sliding surface σ is expressed as:

[0031]

[0032] in, Ω ref represents the reference speed, e represents the error between the reference speed and the speed observation value, is the derivative of e, c is the controller parameter;

[0033] The continuous terminal sliding mode control law is:

[0034]

[0035] in, represents the controller output, represents the derivative of the reference speed, k is the controller parameter, i eq represents the equivalent control term, i v Represents a toggle control.

[0036] Furthermore, the observer coefficients λ1 and λ2 are expressed as:

[0037]

[0038] Where p0 is the observer bandwidth.

[0039] Further, the motor speed Ω with measurement noise n , expressed as:

[0040] Ω n =Ω+δ n

[0041] Among them, Ω represents the motor speed, δ n represents the measurement noise.

[0042] Furthermore, the continuous terminal sliding mode controller uses the motor speed observation value Instead of the motor speed Ω with measurement noise n , and the total disturbance d t Perform real-time feed-forward compensation.

[0043] The beneficial effects of the present invention are:

[0044] The designed method has a simple structure and can be implemented using a processor of general performance, and can enable the speed control system to have better dynamic performance and steady-state performance; the continuous terminal sliding mode controller overcomes the jitter phenomenon of the traditional sliding mode, and at the same time, performs feedforward compensation for the disturbance to improve the system's anti-interference performance; the nonlinear extended state observer introduces a nonlinear term compared to the conventional extended state observation, which enables the system to operate at a smaller observer bandwidth, thereby more effectively suppressing measurement noise.

[0045] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0047] Figure 1 A schematic diagram of a control system according to an embodiment of the present invention;

[0048] Figure 2 A flow chart of a control system according to an embodiment of the present invention;

[0049] Figure 3 A flow chart of a nonlinear extended state observer according to an embodiment of the present invention;

[0050] Figure 4 This is a flow chart of a continuous terminal sliding mode controller according to an embodiment of the present invention;

[0051] Figure 5 1 is a system speed curve under two control modes according to an embodiment of the present invention;

[0052] Figure 6 is a system current curve under a conventional active disturbance rejection control method according to an embodiment of the present invention;

[0053] Figure 7 is a system current curve under a control method of an embodiment of the present invention;

[0054] Figure 8 is a speed output curve of the observer under the control mode of one embodiment of the present invention;

[0055] Fig. 9 FIG. 4 is a disturbance output curve of the observer under the control mode of an embodiment of the present invention. DETAILED DESCRIPTION

[0056] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0057] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0058] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0059] The dynamic equation of the permanent magnet synchronous motor speed control system of the present invention can be expressed as:

[0060]

[0061] Where, Ω represents the motor speed, represents the derivative of the motor speed, B represents the viscosity coefficient, J represents the moment of inertia, i q represents the q-axis current, T L Indicates the motor load, K t represents the motor torque constant, which can be expressed as:

[0062]

[0063] Among them, n p1 represents the number of motor pole pairs, ψ f1 Represents the flux linkage of a permanent magnet.

[0064] In order to facilitate the design, the dynamic equation is further rewritten and can be expressed as:

[0065]

[0066]

[0067]

[0068] Among them, d t represents the total disturbance to the system, Indicates the reference current.

[0069] In the actual permanent magnet synchronous motor speed control system, the motor speed is usually not directly obtained, but the rotor position is measured by an incremental encoder and then differentiated. However, due to the quantization error of the position sensor, the motor speed calculated by differentiation will contain measurement noise. Therefore, the motor speed measurement value Ω containing measurement noise is defined. n , which can be expressed as:

[0070] Ωn =Ω+δ n

[0071] Among them, δ n represents the measurement noise.

[0072] See also Figure 1 , which is a schematic diagram of a control system of an embodiment of the present invention, mainly includes a continuous terminal sliding mode controller, a generalized permanent magnet synchronous motor and a nonlinear extended state observer, wherein the generalized permanent magnet synchronous motor includes a loadable permanent magnet synchronous motor, a vector control framework, two current controllers, a three-phase inverter, a vector pulse width modulation module, a position sensor and a speed calculation module.

[0073] See also Figure 2 , is a flow chart of a control system according to an embodiment of the present invention, which mainly includes the following steps:

[0074] 1. Collect the three-phase currents abc and convert them into the α-axis current i through Clarke transformation. α and the β-axis current i β ; Use Park transformation to transform i α and i β Converted to q-axis current i q and the d-axis current i d ;

[0075] 2. The position sensor collects the motor position signal and calculates the speed Ω n and the interval where the rotor is located;

[0076] 3. Estimate the speed and disturbance of the permanent magnet synchronous motor through nonlinear extended state observation to obtain the motor speed observation value and interference observations

[0077] 4. Calculate the d-axis voltage u through the continuous terminal sliding mode controller and the current controller d and q-axis voltage u q And, with the help of inverse Park transformation, we can get the α-axis voltage u α and β axis voltage u β ;

[0078] 5. Input the α and β axis voltages into the space vector pulse width modulation module, calculate the switching signals of the six power tubes of the three-phase inverter, and generate the abc three-phase voltage to drive the permanent magnet synchronous motor to rotate.

[0079] See also Figure 3 , is a flow chart of a nonlinear extended state observer according to an embodiment of the present invention. The nonlinear extended state observer can be expressed as:

[0080]

[0081] in, represents the observed value of motor speed, represents the interference observation value, represents the derivative of the motor speed observation, represents the derivative of the disturbed observation, Ω n represents the motor speed with measurement noise, and b represents the internal parameters of the motor, which can be expressed as:

[0082]

[0083] Among them, n p1 represents the number of motor pole pairs, ψ f1 represents the permanent magnet flux, J represents the moment of inertia, represents the reference current;

[0084] Nonlinear functions and It can be expressed as:

[0085]

[0086] Among them, γ1, γ2 are the coefficients of the nonlinear function, γ1 = 1 + ε, γ2 = 1 - ε, and the constant ε∈(-0.5, 0), indicates |·| i sgn(i), sgn(i) is:

[0087]

[0088] The observer coefficients λ1 and λ2 related to the observer bandwidth can be expressed as:

[0089]

[0090] Where p0 is the observer bandwidth.

[0091] Compared with the conventional extended state observer, this method introduces nonlinear terms to enable the observation error to converge quickly, thereby ensuring good anti-interference performance and effectively suppressing measurement noise when using a smaller observer bandwidth.

[0092] See also Figure 4 , is a flow chart of a continuous terminal sliding mode controller according to an embodiment of the present invention, and the sliding mode surface σ is:

[0093]

[0094] in, Ω ref represents the reference speed, e represents the error between the reference speed and the speed observation value, is the derivative of e, and c is the controller parameter.

[0095] The continuous terminal sliding mode control law is:

[0096]

[0097] in, represents the controller output, represents the derivative of the reference speed, k is the controller parameter, i eq represents the equivalent control term, i v Represents a toggle control.

[0098] Compared with conventional feedback controllers, the continuous terminal sliding mode controller designed by this method replaces the speed containing measurement noise with the speed observation value, and performs real-time feedforward compensation for the disturbance to offset the impact of the disturbance on the system output; at the same time, this method hides the high-frequency switching function in the high-order derivative of the sliding mode variable, avoiding the jitter phenomenon caused by the switching function in traditional sliding mode control.

[0099] See also Figure 5 , are the system speed curves under two control modes of an embodiment of the present invention. The two control modes are the method proposed by the present invention and the traditional anti-disturbance control method (proportional feedback controller combined with extended state observer). By comparing the system speed curve, it can be found that the control method of the present invention can quickly reach the steady-state value after no-load start, with almost no overshoot, and the rise time is significantly shorter than that of the traditional anti-disturbance control method. When a load disturbance is applied to the speed regulation system at 2 seconds, the method of the present invention shows better anti-disturbance performance, shorter adjustment time, and smaller maximum speed drop, which is significantly better than the conventional anti-disturbance control method. On this basis, the standard deviation calculation of the system speed shows that the control method of the present invention has a smaller speed standard deviation than the traditional anti-disturbance control method, indicating that it has higher control accuracy, smaller speed fluctuation, and better measurement noise suppression performance.

[0100] See also Figure 6 , is a system current curve under a conventional active disturbance rejection control method according to an embodiment of the present invention; please refer to Figure 7 , is the system current curve under the control mode of an embodiment of the present invention. By comparing the two figures, it can be found that the method designed by the present invention has a shorter adjustment time and stronger anti-disturbance ability after the system is disturbed by the load; and the current pulsation of the method designed by the present invention is smaller, which is conducive to the long-term stable operation of the motor.

[0101] See also Figure 8, is the speed output curve of the observer under the control mode of an embodiment of the present invention. The curves in the figure respectively represent the actual value and the observed value of the motor speed. It can be seen that the change trend of the speed observed by the observer is consistent with the actual measured value, indicating that the observer can observe the motor speed in real time and accurately.

[0102] See also Fig. 9 , which is the disturbance output curve of the observer under the control mode of an embodiment of the present invention. It can be seen that the observer accurately estimates the load disturbance at 2 seconds, indicating that the observer can estimate the disturbance in real time.

[0103] The method designed in the present invention has a simple structure and can be implemented using a processor of general performance, and can enable the speed control system to have better dynamic performance and steady-state performance; the continuous terminal sliding mode controller overcomes the chattering phenomenon of the traditional sliding mode, and at the same time, performs feedforward compensation for the disturbance to improve the anti-interference performance of the system; the nonlinear extended state observer introduces a nonlinear term compared to the conventional extended state observation, so that the system can operate at a smaller observer bandwidth, thereby more effectively suppressing measurement noise.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A method for suppressing measurement noise of a permanent magnet synchronous motor speed control system, characterized in that: The following steps are involved: The nonlinear extended state observer is designed using the dynamic equations of the permanent magnet synchronous motor speed control system. Collect the three-phase currents abc and convert them into the α-axis current i through Clarke transformation α and the β-axis current i β ; Use Park transformation to transform i α and i β Converted to q-axis current i q and the d-axis current i d ; The position sensor collects the motor position signal and calculates the motor speed Ω with measurement noise n and the interval where the rotor is located; The speed and disturbance of the permanent magnet synchronous motor are estimated by the nonlinear extended state observer to obtain the motor speed observation value. and interference observations According to the motor speed observation value And the interference observation Design continuous terminal sliding mode controller; The d-axis voltage u is calculated by the continuous terminal sliding mode controller and the current controller. d and q-axis voltage u q And, with the help of inverse Park transformation, we can get the α-axis voltage u α and β axis voltage u β ; The α and β axis voltages are input into the space vector pulse width modulation module, and the switching signals of the six power tubes of the three-phase inverter are calculated to generate the abc three-phase voltages to drive the permanent magnet synchronous motor to rotate.

2. The method for suppressing measurement noise of a permanent magnet synchronous motor speed control system according to claim 1, characterized in that: The dynamic equation of the permanent magnet synchronous motor speed control system is expressed as: Where, Ω represents the motor speed, represents the derivative of the motor speed, B represents the viscosity coefficient, J represents the moment of inertia, i q represents the q-axis current, T L Indicates the motor load, K t represents the motor torque constant, expressed as: Among them, n p1 represents the number of motor pole pairs, ψ f1 represents the permanent magnet flux, so the dynamic equation is expressed as: Among them, d t represents the total disturbance to the system, Indicates the reference current.

3. The method for suppressing measurement noise of a permanent magnet synchronous motor speed control system according to claim 1, characterized in that: The nonlinear extended state observer is expressed as: in, represents the observed value of motor speed, represents the interference observation value, represents the derivative of the motor speed observation, represents the derivative of the disturbance observation, λ1, λ2 represent the observer coefficients related to the observer bandwidth, Ω n represents the motor speed with measurement noise, and b represents the internal parameters of the motor, which can be expressed as: Among them, n p1 represents the number of motor pole pairs, ψ f1 represents the permanent magnet flux, J represents the moment of inertia, represents the reference current; Nonlinear functions and It can be expressed as: Among them, γ1, γ2 represent the coefficients of the nonlinear function, γ1=1+ε, γ2=1-ε, and the constant ε∈(-0.5,0), "·" i indicates |·| i sgn(i), sgn(i) is:

4. The method for suppressing measurement noise of a permanent magnet synchronous motor speed control system according to claim 1, characterized in that: The steps of designing a continuous terminal sliding mode controller are: The sliding surface σ is expressed as: in, Ω ref represents the reference speed, e represents the error between the reference speed and the speed observation value, is the derivative of e, c is the controller parameter; The continuous terminal sliding mode control law is: in, represents the controller output, represents the derivative of the reference speed, k is the controller parameter, i eq represents the equivalent control term, i v Represents a toggle control.

5. The method for suppressing measurement noise of a permanent magnet synchronous motor speed control system according to claim 3, characterized in that: The observer coefficients λ1 and λ2 are expressed as: Where p0 is the observer bandwidth.

6. The method for suppressing measurement noise of a permanent magnet synchronous motor speed control system according to claim 3, characterized in that: The motor speed Ω with measurement noise n , expressed as: Oh n =Ω+δ n Among them, Ω represents the motor speed, δ n represents the measurement noise.

7. A method for suppressing measurement noise of a permanent magnet synchronous motor speed control system according to any one of claims 2 to 6, characterized in that: The continuous terminal sliding mode controller uses the motor speed observation value Instead of the motor speed Ω with measurement noise n , and the total disturbance d t Perform real-time feed-forward compensation.

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