A permanent magnet synchronous motor state measurement method based on speed loop

Abstract

The present invention relates to a permanent magnet synchronous motor state measurement method of a speed loop, belongs to the field of permanent magnet synchronous motor control technology, and solves the problems of large error, high delay and impossibility of general use when measuring low speed in the prior art. The method comprises the following steps: according to the controlled model of the speed loop, an internal state observation model of the permanent magnet synchronous motor is established; the state matrix corresponding to the above observation model is obtained to determine whether the above observation model is observable and controllable; if it is not observable or uncontrollable, the structure or parameters of the observation model are adjusted until it is observable and controllable; the servo system order corresponding to the observable and controllable observation model is determined, and the feedback gain matrix of the feedback link in the above observation model is determined in combination with the system step response performance index, so that the true value of the observable state variable of the closed-loop control is equal to the measured value; the measured value of the observable state variable within a sampling period is obtained, and the state matrix is ​​input into the observation model determined by the feedback gain matrix to determine the unobservable state variable.

Description

Technical Field

[0001] The invention relates to the technical field of permanent magnet synchronous motor control, and in particular to a permanent magnet synchronous motor state measurement method based on a speed loop. Background Art

[0002] Permanent magnet synchronous motors are widely used due to their high power density, high conversion efficiency, and easy control. At present, in the control of permanent magnet synchronous motors, proportional integral (PI) control is generally used for the speed loop control. However, there are also many occasions where different requirements are placed on overshoot, stability, dynamic followability and other performances. In addition to PI control, IP control, pseudo differential feedback control (PDFF), model tracking control, M / T method control (such as Figure 1 ) and other control methods.

[0003] The above control methods have their own advantages, but they generally have limitations such as large errors and high delays when measuring low speeds. In addition, they need to be suitable for different application scenarios according to the external systems they are applied to. However, in the development process of motor drivers, it is often unclear what kind of external system the controller will be used in.

[0004] At present, there is a lack of a unified control structure that can overcome the problems of large errors and high delays in existing technologies when measuring low speeds, and can implement different control structures by simply configuring parameters, and configure different control structures according to the performance requirements of different scenarios. Summary of the invention

[0005] In view of the above analysis, an embodiment of the present invention aims to provide a permanent magnet synchronous motor state measurement method based on a speed loop, so as to solve the problems of large error, high delay and non-universality when measuring low speed in the prior art.

[0006] On the one hand, an embodiment of the present invention provides a permanent magnet synchronous motor state measurement method based on a speed loop, comprising the following steps:

[0007] According to the controlled model of the speed loop, the observable state variables of the permanent magnet synchronous motor are closed-loop controlled to establish the internal state observation model of the permanent magnet synchronous motor;

[0008] Obtaining a state matrix corresponding to the observation model, and judging whether the observation model is observable and controllable according to the state matrix; if the observation model is not observable or controllable, adjusting the structure or parameters of the observation model until the observation model is observable and controllable;

[0009] Determine the servo system order corresponding to the above observable and controllable observation model, and determine the feedback gain matrix of the feedback link in the above observation model in combination with the system step response performance index corresponding to the order, so that the true value of the observable state variable of the closed-loop control is equal to the measured value;

[0010] The measured values ​​of the observable state variables of the above closed-loop control of the permanent magnet synchronous motor within a sampling period are obtained, input into the observation model determined by the feedback gain matrix, and the unobservable state variables inside the permanent magnet synchronous motor within the sampling period are determined and pushed to the user.

[0011] The beneficial effects of the above technical solution are as follows: a state observer is constructed starting from the speed loop, the motor speed is simulated directly through the speed loop state matrix, and the state observer is used to replace the M / T method that is inaccurate in speed measurement at low speed, thereby greatly increasing the speed feedback accuracy in the servo control process and optimizing the low-speed control effect of the motor. A full-dimensional state observer is constructed, and the error between the estimated value and the true value (including the measured value of the observable state variable) can be approached to zero by selecting a suitable feedback gain matrix. The parameter setting is simple and the calculation cost is reduced. Its application will bring convenience to the implementation of the servo system and enable permanent magnet synchronous motors to adapt to a wider range of application scenarios.

[0012] Based on a further improvement of the above method, the step of performing closed-loop control on the observable state variables of the permanent magnet synchronous motor according to the controlled model of the speed loop and establishing an internal state observation model of the speed loop in the permanent magnet synchronous motor further includes:

[0013] Determine the observable state variables of the permanent magnet synchronous motor and the unobservable state variables to be measured;

[0014] Select one of the above observable state variables as the output y, and use the column vector formed by all the above observable state variables and the unobservable state variables as the input x to establish the controlled mathematical model of the speed loop in the permanent magnet synchronous motor.

[0015]

[0016] Wherein, the elements of x are observable state variables and unobservable state variables of the permanent magnet synchronous motor, A, B, and C are state matrices related to the state variables, It means to perform differential operation on each element in x, and u is the unobservable state variable to be measured;

[0017] The above mathematical model is mirrored, and a feedback link is constructed according to the difference between the obtained mirror model and the above mathematical model to obtain the internal state observation model of the permanent magnet synchronous motor.

[0018] The beneficial effect of the above-mentioned further improvement scheme is: from a mathematical perspective, a controlled model of the speed loop in the permanent magnet synchronous motor is defined, and a state observer (i.e., observation model) is constructed based on the controlled mathematical model, which can more intuitively understand the input and output variables of the state observer, thereby accurately obtaining the specific values ​​of the internal non-objective state variables of the permanent magnet synchronous motor.

[0019] Furthermore, the step of judging whether the observation model is observable and controllable according to the state matrix further includes:

[0020] According to the state matrices A and C, it is determined whether the following equation is true. If true, it is determined that the observation model is observable. Otherwise, it is determined that the observation model is not observable.

[0021] rank[C T A T C T (A T ) 2 C T ]=n

[0022] In the formula, rank() represents the rank of the matrix, and n is the number of elements in x;

[0023] After determining that the observation model is observable, the following equation is determined based on the state matrices A and B. If it is true, the observation model is determined to be controllable. Otherwise, the observation model is determined to be uncontrollable.

[0024] rank[D CD C 2 D]=n

[0025] C=I+AT s

[0026]

[0027] Where I is the n-order unit matrix, T s is the sampling period.

[0028] The beneficial effect of the above further improvement scheme is to limit the judgment method of whether the constructed observation model is observable and controllable. Through a large number of experiments, the judgment formula of whether the above state observer is observable and controllable is summarized. Substituting A, B, and C in the controlled mathematical model of the speed loop into the above formula, the observability and controllability of the currently constructed observation model can be determined very quickly and accurately. If it is not appropriate, it can be adjusted in time.

[0029] Furthermore, if the observation model is not observable or controllable, the step of adjusting the structure or parameters of the observation model until the observation model is observable and controllable further includes:

[0030] If the observation model is not observable, reselect the observable output variable corresponding to the output y, rebuild the observation model, and judge again until the reconstructed observation model is observable;

[0031] If the above observable observation model is not controllable, change the parameters in the observation model, the parameters include sampling period and rotor moment of inertia, and judge again until the observation model is controllable, so as to obtain an observable and controllable observation model.

[0032] The beneficial effects of the above further improvement scheme are: adjusting the observable output variable corresponding to the output y makes the observation model observable, and adjusting the sampling period, moment of inertia and other parameters makes the observation model controllable. The above scheme provides a parameter adjustment method, combined with the judgment formula of whether the state observer can be observable and controllable, so that the constructed observation model can be both observable and controllable.

[0033] Further, the output y is the motor rotor mechanical angle θ;

[0034] The input x is

[0035]

[0036] A, B, and C are

[0037]

[0038] Where ω is the mechanical angular velocity of the motor rotor, T l is the load torque, J m is the rotor moment of inertia, T s is the sampling period, ω, T l As an unobservable state variable inside the permanent magnet synchronous motor.

[0039] The beneficial effect of the above further improvement scheme is: defining an observable and controllable observation model. The output y and the input x are defined, where θ in the input x is also used as an observable output variable, ω, T l The above formula helps users better understand the controlled model of the speed loop in the permanent magnet synchronous motor.

[0040] Furthermore, the internal state observation model of the speed loop in the permanent magnet synchronous motor is:

[0041]

[0042] in

[0043]

[0044] Where, L w is the feedback gain matrix of the feedback link, l1, l2, l3 are L welement, θ′ is the actual mechanical angle of the motor rotor.

[0045] The beneficial effects of the above further improvement scheme are: defining an internal state observation model of the speed loop in the permanent magnet synchronous motor, building a feedback link by mirroring the controlled model of the speed loop and combining the difference between the observed value θ′ and the true value θ of the observable output variable, and reasonably building L w is the feedback gain matrix L of the feedback link w , which can make the observed values ​​of all variables of the permanent magnet synchronous motor equal to the true values.

[0046] Further, the feedback gain matrix L of the feedback link in the observation model is determined by the following steps: w :

[0047] Determine the step response performance index of the servo system corresponding to the observation model, including the step response overshoot σ p , overshoot peak time t p 、System bandwidthω b 、System natural frequency ω n ;

[0048] Determine all the poles s1,…,s of the servo system that meet the above step response performance indicators N , N is the total number of poles;

[0049] Input the above poles into the following pole configuration model to obtain the feedback gain matrix L of the feedback link: w

[0050] L w =place(A,B,P)

[0051] in

[0052]

[0053] The beneficial effect of the above further improvement scheme is: a feedback gain matrix L is defined that can make the observed values ​​of all variables of the permanent magnet synchronous motor equal to the true values. w Determination method. Through the system step response performance index (step response overshoot σ p , overshoot peak time t p 、System bandwidthω b 、System natural frequency ω n ), the feedback gain matrix L can be constructed intuitively w The pole configuration scheme.

[0054] Furthermore, when the order of the servo system is 3, the influence of the far pole on the system is ignored, and the servo system corresponding to the observation model is approximated as a second-order system.

[0055] The beneficial effect of the above further improvement scheme is that the model of the servo system is equivalent to a second-order system, which can further determine a variable of the state observer.

[0056] Furthermore, the step response overshoot σ p , overshoot peak time t p 、System bandwidthω b 、System natural frequency ω n Determine by the following equations and inequalities

[0057]

[0058]

[0059]

[0060]

[0061]

[0062] Where n% is the upper limit of the step response overshoot, T is the upper limit of the overshoot peak time, Ψ is the upper limit of the system bandwidth, and φ is the damping coefficient;

[0063] Determine the value that satisfies the above σ according to the following formula p ,t p ,ω b ,ω n The pair of main poles of the servo system is

[0064]

[0065]

[0066] The P is

[0067]

[0068] The beneficial effect of the above further improvement scheme is that as a third-order system, the servo system substitutes its specific step response performance index into the above formula, that is, the pole configuration model of the feedback gain matrix, and a pair of main poles of the servo system can be accurately obtained.

[0069] Further, 0.707≤φ≤1.

[0070] The beneficial effect of the above further improvement scheme is: the damping coefficient range of the servo system is limited, from which the most suitable damping coefficient value can be quickly selected and substituted into the pole calculation formula to quickly determine a pair of main pole positions, which facilitates the calculation of the feedback gain matrix.

[0071] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0073] Figure 1 It is a control schematic diagram of the existing AC servo system;

[0074] Figure 2 This is a schematic diagram of the steps of a method for measuring the state of a permanent magnet synchronous motor based on a speed loop according to Embodiment 1 of the present invention;

[0075] Figure 3 The controlled mathematical model and mirroring process of the speed loop of Embodiment 2 of the present invention;

[0076] Figure 4 The internal state observation model of the permanent magnet synchronous motor of the speed loop of embodiment 2 of the present invention;

[0077] Figure 5 The permanent magnet synchronous motor simulation model with an observer according to embodiment 2 of the present invention;

[0078] Figure 6 The speed loop output of Example 2 of the present invention is compared with the speed loop output of the M / T method when the command speed is 600r / min and the observer bandwidth is 200rad / s;

[0079] Figure 7 The speed loop output of Example 2 of the present invention is compared with the speed loop output of the M / T method when the command speed is 600r / min and the observer bandwidth is 2000rad / s;

[0080] Figure 8 The speed loop output of Example 2 of the present invention is compared with the speed loop output of the M / T method when the command speed is 20 r / min and the observer bandwidth is 10 rad / s and 1000 rad / s respectively. DETAILED DESCRIPTION

[0081] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0082] In the AC servo system of permanent magnet synchronous motor, some state variables are used as system internal variables (such as load torque T l etc.) cannot be measured directly or the measurement cost is high. In this case, it is appropriate to use the method of building a state observer to reconstruct the original system.

[0083] To reconstruct the speed loop in the permanent magnet synchronous motor AC servo system, the variables that cannot be directly measured or the measurement cost is high need to be regarded as unobservable state variables. Table 1 below gives the physical meaning of each state variable of the permanent magnet synchronous motor.

[0084] Table 1

[0085]

[0086] Example 1

[0087] A specific embodiment of the present invention discloses a method for measuring the state of a permanent magnet synchronous motor based on a speed loop, such as Figure 2 As shown, the following steps are included:

[0088] S1. According to the controlled model of the speed loop, the observable state variables of the permanent magnet synchronous motor are closed-loop controlled to establish an internal state observation model of the permanent magnet synchronous motor;

[0089] Specifically, the control model can select a controlled mathematical model that includes the state variables to be measured that the user is interested in (including unobservable state variables) according to actual needs, and then use the state variables to be measured that the user is interested in as input and the observable state variables as output, mirror the controlled mathematical model, and construct a feedback link with the difference between the true value and the measured value of the observable state variable, and construct a closed-loop control loop for the observable state variable, so that the true value of the observable state variable is consistent with the measured value.

[0090] S2. Obtain the state matrix corresponding to the observation model, and determine whether the observation model is observable and controllable according to the state matrix; if not, adjust the structure or parameters of the observation model until the observation model is observable and controllable;

[0091] Specifically, step S2 is used to determine whether the observation model is observable and controllable, thereby ensuring that the final result is authentic.

[0092] S3. Determine the servo system order corresponding to the above observable and controllable observation model, and determine the feedback gain matrix of the feedback link in the above observation model in combination with the system step response performance index corresponding to the order, so that the theoretical value of the observable state variable of the closed-loop control is equivalent to the measured value;

[0093] Specifically, through feedback regulation, the errors between the state variables of the feedback link and the variables of the original control path gradually approach zero.

[0094] S4. Obtain the measured values ​​of the observable state variables of the above closed-loop control of the permanent magnet synchronous motor within a sampling period, input them into the observation model determined by the feedback gain matrix, determine the unobservable state variables inside the permanent magnet synchronous motor within the sampling period, and push them to the user.

[0095] During implementation, the difference between the reconstructed system (feedback link) and the original system output (controlled model) variables is feedback-adjusted through the feedback gain matrix to form a closed-loop system, so that the errors between the state variables of the reconstructed system and the variables of the original system gradually approach zero, and the observed values ​​of the unobservable state variables inside the permanent magnet synchronous motor that are very close to the true values ​​can be obtained.

[0096] Compared with the prior art, the method provided in this embodiment constructs a state observer starting from the speed loop, simulates the motor speed directly through the speed loop state matrix, and uses the state observer to replace the M / T method that is inaccurate in speed measurement at low speed, thereby greatly increasing the speed feedback accuracy in the servo control process, optimizing the low-speed control effect of the motor, and constructing a full-dimensional state observer. By selecting a suitable feedback gain matrix, the error between the estimated value and the true value (including the measured value of the observable state variable) can be approached to zero. The parameter setting is simple and the calculation cost is reduced. Its application will bring convenience to the implementation of the servo system and enable the permanent magnet synchronous motor to adapt to a wider range of application scenarios.

[0097] Example 2

[0098] Based on the improvement of the method in Example 1, step S1 is further refined as follows:

[0099] S11. Determine the observable state variables of the permanent magnet synchronous motor and the unobservable state variables to be measured; the user can select the required observable state variables and unobservable state variables according to actual needs;

[0100] S12. Select one of the above observable state variables as output y, and use the column vector formed by all the above observable state variables and the unobservable state variables as input x to establish a controlled mathematical model of the speed loop in the permanent magnet synchronous motor.

[0101]

[0102] In the formula, the elements of x are the observable state variables and unobservable state variables of the permanent magnet synchronous motor, A, B, and C are state matrices, represents a differential operation on each element in x; u is a local or global unobservable state variable of interest to the user.

[0103] S13. Mirroring the constructed mathematical model, constructing a feedback link based on the difference between the obtained mirror model and the above mathematical model, and obtaining an internal state observation model of the permanent magnet synchronous motor.

[0104] For example, the mirroring process is as follows Figure 3 As shown, the internal state observation model is as follows Figure 4 shown.

[0105] Preferably, step S2 is further refined as follows:

[0106] S21. Determine whether the following equation is true according to the state matrices A and C. If true, determine that the observation model is observable and execute step S23. Otherwise, determine that the observation model is not observable and execute step S22.

[0107] rank[C T A T C T (A T ) 2 C T ]=n (2)

[0108] In the formula, rank() represents the rank of the matrix, n is the number of elements of x, and T represents the transpose operation;

[0109] S22. Reselect the observable output variable corresponding to the output y, rebuild the observation model, and make another judgment until the reconstructed observation model is observable;

[0110] S23. After determining that the observation model is observable, determine whether the following equation is true based on the state matrices A and B. If true, determine that the observation model is controllable and execute step S3. Otherwise, determine that the observation model is uncontrollable and execute step S24.

[0111] rank[D CD C 2 D]=n (3)

[0112] C=I+AT s

[0113]

[0114] Where I is the n-order unit matrix, T s is the sampling period.

[0115] S24. Change the parameters in the observation model, which include the sampling period and the rotor moment of inertia, and make another judgment until the observation model is controllable, thereby obtaining an observable and controllable observation model.

[0116] Preferably, an observable and controllable observation model is given below. The output y is the mechanical angle θ of the motor rotor. The input x is

[0117]

[0118] therefore

[0119] u=[T e ],y=[θ]

[0120]

[0121] In the formula, u is the input variable set of the speed loop, y is the output variable set of the speed loop, and x is the state variable set related to the permanent magnet synchronous motor. is a set of differentials of each state variable in x, θ is the mechanical angle of the motor rotor, ω is the mechanical angular velocity of the motor rotor, T l is the load torque, J m is the rotor moment of inertia, T s is the sampling period, ω, T l As the unobservable state variables inside the permanent magnet synchronous motor, A, B, and C are parameter matrices.

[0122] The internal state observation model of the permanent magnet synchronous motor speed loop is:

[0123]

[0124] Right now

[0125]

[0126] in

[0127]

[0128]

[0129] In the formula, x′ is the set of state variables on the feedback link, is a set of differentials of each state variable in x′, θ′ is the measured mechanical angle of the motor rotor, ω′ is the mechanical angular velocity of the motor rotor on the feedback link, T′ l Load torque on the feedback link.

[0130] The order of the observed AC servo system is 3 (the three state variables are the q-axis transient electromotive force E q , rotor angular velocity ω, rotor position angle θ), so the expected number of poles N = 3. According to the comprehensive performance index requirements, one pair can be selected as the dominant poles s1 and s2, and the other can be the far pole s3 far away from the imaginary axis in the left half plane. If the far poles (q-axis transient electromotive force E q) on the system, it can be considered that the performance of the system is mainly determined by a pair of dominant poles, so it can be approximately regarded as a simplified second-order system for calculation.

[0131] Preferably, step S3 further determines the feedback gain matrix L of the feedback link in the observation model by the following steps: w :

[0132] S31. Determine the step response performance index of the servo system corresponding to the observation model through the following formula, including the step response overshoot σ p , overshoot peak time t p 、System bandwidthω b 、System natural frequency ω n

[0133]

[0134]

[0135]

[0136]

[0137]

[0138] Where n% is the upper limit of the step response overshoot, T is the upper limit of the overshoot peak time, Ψ is the upper limit of the system bandwidth, and φ is the damping coefficient.

[0139] S32. Determine all poles s1, ..., s1 of the servo system that meet the above step response performance indicators. N , N is the total number of poles, corresponding to the third-order system above, there are two main poles s1 and s2

[0140]

[0141]

[0142] S33. Input the above poles into the following pole configuration model to obtain the feedback gain matrix L of the feedback link w

[0143] L w =place(A,B,P) (11)

[0144] in

[0145]

[0146]

[0147] Bandwidth and ω of a Second-Order System nis proportional to, and when φ=0.707, ω n ≈ω b .

[0148] s3 is the far pole, and its distance from the origin should be much larger than the distance between the main pole and the origin. Usually |s3|>>5|s1| is selected, and |s3|=10|s1| is selected.

[0149] After selecting the poles, call the pole placement function in the Matlab function library to calculate the state observer gain matrix L w .

[0150] The speed loop observer simulation experiment was carried out on the MATLAB / Simulink platform, and a model using a full-dimensional state observer as the speed feedback link was built. Its specific structure is as follows Figure 5 As shown in the figure. The M / T feedback method of the speed loop of this model is to approximate the speed by the M / T method through the pulse number of the encoder. Since the resolution is too low at low speed, a state observer is introduced to estimate the instantaneous speed. The motor parameters in the simulation model are shown in Table 2.

[0151] Table 2 Permanent magnet synchronous motor simulation parameters

[0152]

[0153] After simulation comparison, it can be Figures 6 to 8 The observation effect of the state variable under different bandwidths of the state observer in this embodiment is compared with the speed measurement waveform of the M / T method.

[0154] Figure 6 The figure shows the speed loop output of the command speed of 600r / min and the observer bandwidth of 200rad / s compared with the speed loop output of the M / T method. It can be seen that at the set observer bandwidth, the amplitude-frequency characteristic is the maximum gain multiple, and the phase-frequency characteristic is maintained at a good level, ensuring that the waveform below 200rad / s can be completely retained and a very fast response state is guaranteed. Figure 7 The light grey curve in the figure is the output result of the M / T method speed measurement, and the dark grey curve is the speed observation waveform of the state observer with a bandwidth of 200 rad / s. Figure 8 The light gray and dark gray curves have the same meaning. Figure 7 , the dark grey curve is the speed observation waveform of the state observer with a bandwidth of 2000 rad / s. It can be seen that when the observer bandwidth is appropriate, the observer feedback control method of this embodiment can effectively reduce the high-frequency noise of the speed at both low and high speeds.

[0155] Compared with the prior art, the full-dimensional state observer provided in this embodiment can be used at low and high speeds of the servo drive speed loop, skipping the steps of reading and calculating the photoelectric encoder, saving manpower and price costs, and simplifying the control steps. When the observer bandwidth is appropriate, the feedback control of the AC servo system can effectively reduce the high-frequency noise of the speed.

[0156] Those skilled in the art will appreciate that all or part of the processes of the above-mentioned embodiments can be implemented by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, wherein the computer-readable storage medium is a disk, an optical disk, a read-only storage memory, or a random access memory, etc.

[0157] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for measuring the state of a permanent magnet synchronous motor based on a speed loop, characterized in that: The steps include: According to the controlled model of the speed loop, the observable state variables of the permanent magnet synchronous motor are closed-loop controlled to establish the internal state observation model of the permanent magnet synchronous motor; Obtain a state matrix corresponding to the observation model, and determine whether the observation model is observable and controllable according to the state matrix; if not, adjust the structure or parameters of the observation model until the observation model is observable and controllable; Determine the servo system order corresponding to the above observable and controllable observation model, and determine the feedback gain matrix of the feedback link in the above observation model in combination with the system step response performance index corresponding to the order, so that the true value of the observable state variable of the closed-loop control is equal to the measured value; The measured values ​​of the observable state variables of the above closed-loop control of the permanent magnet synchronous motor within a sampling period are obtained, input into the observation model determined by the feedback gain matrix, and the unobservable state variables inside the permanent magnet synchronous motor within the sampling period are determined and pushed to the user.

2. The method for measuring the state of a permanent magnet synchronous motor based on a speed loop according to claim 1, characterized in that: The step of performing closed-loop control on the observable state variables of the permanent magnet synchronous motor according to the controlled model of the speed loop and establishing an internal state observation model of the speed loop in the permanent magnet synchronous motor further comprises: Determine the observable state variables of the permanent magnet synchronous motor and the unobservable state variables to be measured; Select one of the above observable state variables as the output y, and use the column vector formed by all the above observable state variables and the unobservable state variables as the input x to establish the controlled mathematical model of the speed loop in the permanent magnet synchronous motor. Wherein, the elements of x are observable state variables and unobservable state variables of the permanent magnet synchronous motor, A, B, and C are state matrices related to the state variables, It means to perform differential operation on each element in x, and u is the unobservable state variable to be measured; The above mathematical model is mirrored, and a feedback link is constructed according to the difference between the obtained mirror model and the above mathematical model to obtain the internal state observation model of the permanent magnet synchronous motor.

3. According to the method for measuring the state of a permanent magnet synchronous motor based on a speed loop as claimed in claim 2, the step of judging whether the observation model is observable and controllable according to the state matrix further comprises: According to the state matrices A and C, it is determined whether the following equation is true. If true, it is determined that the observation model is observable. Otherwise, it is determined that the observation model is not observable. rank[C T A T C T (A T ) 2 C T ]=n In the formula, rank( ) represents the rank of the matrix, and n is the number of elements in x; After determining that the observation model is observable, the following equation is determined based on the state matrices A and B. If it is true, the observation model is determined to be controllable. Otherwise, the observation model is determined to be uncontrollable. rank[D CD C 2 D]=n C=I+AT s Where I is the n-order unit matrix, T s is the sampling period.

4. The method for measuring the state of a permanent magnet synchronous motor based on a speed loop according to claim 3 is characterized in that: If the observation model is not observable or controllable, the step of adjusting the structure or parameters of the observation model until the observation model is observable and controllable further includes: If the observation model is not observable, reselect the observable output variable corresponding to the output y, rebuild the observation model, and judge again until the reconstructed observation model is observable; If the above observable observation model is not controllable, change the parameters in the observation model, the parameters include sampling period and rotor moment of inertia, and judge again until the observation model is controllable, so as to obtain an observable and controllable observation model.

5. The method for measuring the state of a permanent magnet synchronous motor based on a speed loop according to any one of claims 2 to 4, characterized in that: The output y is the motor rotor mechanical angle θ; The input x is A, B, and C are C＝1 0 0 Where ω is the mechanical angular velocity of the motor rotor, T l is the load torque, J m is the rotor moment of inertia, T s is the sampling period, ω, T l As an unobservable state variable inside the permanent magnet synchronous motor.

6. The method for measuring the state of a permanent magnet synchronous motor based on a speed loop according to claim 5, characterized in that: The internal state observation model of the speed loop in the permanent magnet synchronous motor is: in Where, L w is the feedback gain matrix of the feedback link, l1, l2, l3 are L w element, θ′ is the actual mechanical angle of the motor rotor.

7. The method for measuring the state of a permanent magnet synchronous motor based on a speed loop according to any one of claims 2-4 and 6, characterized in that: The feedback gain matrix L of the feedback link in the observation model is determined by the following steps: w : Determine the step response performance index of the servo system corresponding to the observation model, including the step response overshoot σ p , overshoot peak time t p 、System bandwidthω b 、System natural frequency ω n ; Determine all the poles s1,…, of the servo system that meet the above step response performance indicators s N , N is the total number of poles; Input the above poles into the following pole configuration model to obtain the feedback gain matrix L of the feedback link: w L w =place(A,B,P) in 8. The method for measuring the state of a permanent magnet synchronous motor based on a speed loop according to claim 7, characterized in that: When the order of the servo system is 3, the influence of the far pole on the system is ignored, and the servo system corresponding to the observation model is approximated as a second-order system.

9. The method for measuring the state of a permanent magnet synchronous motor based on a speed loop according to claim 8, characterized in that: The step response overshoot σ p , overshoot peak time t p 、System bandwidthω b 、System natural frequency ω n Determine by the following equations and inequalities Where n% is the upper limit of the step response overshoot, T is the upper limit of the overshoot peak time, Ψ is the upper limit of the system bandwidth, and φ is the damping coefficient; Determine the value that satisfies the above σ according to the following formula p ,t p ,ω b ,ω n The pair of main poles of the servo system is The P is 10. The method for measuring the state of a permanent magnet synchronous motor based on a speed loop according to claim 9, characterized in that: 0.707≤φ≤1.

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