A permanent magnet synchronous motor speed control method and device

Abstract

The present invention relates to the technical field of permanent magnet synchronous motor speed control, and specifically to a permanent magnet synchronous motor speed control method and device, the method comprising: establishing a mathematical model of a permanent magnet synchronous motor taking into account periodic and non-periodic disturbances; designing a disturbance observer based on an iterative learning strategy to estimate the lumped disturbances including torque pulsation suffered by the permanent magnet synchronous motor; designing a fast integral terminal sliding mode speed controller based on the disturbance observer to achieve pulsation suppression of the permanent magnet synchronous motor. The present invention effectively suppresses the torque pulsation phenomenon by designing a novel fast integral terminal sliding mode and a disturbance observer based on iterative learning, thereby ensuring that the control system has good robustness and dynamic response performance, so as to achieve rapid tracking of the motor speed, and effectively improve the tracking accuracy for motor systems with a greater impact of periodic torque pulsation.

Description

Technical Field

[0001] The present invention relates to the technical field of permanent magnet synchronous motor speed control, and in particular to a permanent magnet synchronous motor speed control method and device. Background Art

[0002] Permanent magnet synchronous motors are widely used in different fields such as electric vehicles, CNC machine tools, optoelectronic turntables, and ship propulsion due to their high power density, high torque-to-inertia ratio, and high efficiency; however, parameter mismatch, nonlinearity of the controlled model, and permanent magnet synchronous motor torque pulsation caused by flux harmonics, cogging torque, inverter nonlinearity, and current detection errors reduce the tracking performance and stability of the system.

[0003] Integral terminal sliding mode is often used in motor speed control due to its advantages such as fast response speed, small overshoot and strong interference suppression ability. It can improve the anti-interference ability of permanent magnet synchronous motor servo control system. However, the traditional integral terminal sliding mode controller converges slowly when the tracking error is far away from the equilibrium point. Therefore, a new type of fast integral terminal sliding mode control is needed. This strategy can achieve faster convergence speed when the tracking error is large, thereby realizing rapid convergence of the tracking error. However, when the disturbance is unknown, the sliding mode control needs to select a larger switching gain to ensure the robustness of the system, which will cause severe jitter in the motor system.

[0004] Using a disturbance observer to estimate and compensate for disturbances is an effective method to weaken the jitter phenomenon of sliding mode control. However, due to the high bandwidth characteristics of torque pulsation, traditional disturbance observers are based on slowly varying disturbances and have limited observation capabilities for periodic disturbances. Therefore, a new type of disturbance observer based on iterative learning is needed to estimate and compensate for periodic disturbances, thereby achieving torque pulsation suppression and jitter reduction. Summary of the invention

[0005] The embodiments of the present invention provide a permanent magnet synchronous motor speed control method and device, which can realize rapid tracking of the motor speed and effectively improve the tracking accuracy for motor systems that are greatly affected by periodic torque pulsation.

[0006] According to an embodiment of the present invention, a permanent magnet synchronous motor speed control method is provided, comprising the following steps:

[0007] Establish a mathematical model of permanent magnet synchronous motor considering periodic and non-periodic disturbances;

[0008] Design a disturbance observer based on iterative learning strategy to estimate the total disturbance of permanent magnet synchronous motor including torque ripple.

[0009] A fast integrating terminal sliding mode speed controller based on disturbance observer is designed to achieve pulsation suppression for permanent magnet synchronous motor.

[0010] Furthermore, the mathematical model of the permanent magnet synchronous motor considering periodic and non-periodic disturbances is established as follows:

[0011] Assume that the output electromagnetic torque of the permanent magnet synchronous motor is:

[0012]

[0013] Among them, T e and T cog Correspondingly represents the motor electromagnetic torque and cogging torque; θ e , n p The corresponding expression is the electrical angle and pole pair number of the motor; ψ f , ψ 6i Correspondingly represents the permanent magnet flux of the permanent magnet synchronous motor and the 6ith order flux harmonic amplitude; i q , Δi inverter ,Δi offset ,Δi scaling They correspond to the q-axis current, the current error caused by inverter nonlinearity, current sensor offset and scaling, respectively;

[0014] Among them, Δi inverter ,Δi offset ,Δi scaling ,T cog It can be further expressed as:

[0015]

[0016] Among them, R s and L s They correspond to the stator inductance and resistance of the motor, A1, A2, θ5, θ7, V dead They are the harmonic amplitude, initial phase angle and voltage change caused by dead zone effect; Δi a , Δi b The corresponding expression is phase current i a ,i b The DC offset, θ1, depends on Δi a and i b The constant angle of i s Indicates the amplitude of phase current; k a , k b They correspond to the scaling factors of phase a and phase b currents respectively; T cogi represents the amplitude of the i-th cogging torque harmonic; N c Indicates the least common multiple between the number of motor teeth and the number of pole pairs;

[0017] From equations (1) and (2), the flux harmonics, the nonlinearity of the inverter and the cogging torque generate 6 times the harmonic components in the electromagnetic torque, the current sensor offset generates 1 times the harmonic components in the electromagnetic torque, and the current sensor scaling generates 2 times the harmonic components in the electromagnetic torque; therefore, the electromagnetic torque is mainly composed of a DC component and the 1st, 2nd, 6th and 12th harmonic components, which can be simplified as:

[0018]

[0019] Where k represents the harmonic order, T e0 , T ek ,φ k They are respectively expressed as the amplitude and phase angle of the DC component and the harmonic component;

[0020] The motion equation of the permanent magnet synchronous motor is expressed as:

[0021]

[0022] Where J represents the moment of inertia, ω m represents the mechanical angular velocity, B represents the viscous damping coefficient, T L Indicates load torque;

[0023] Taking into account the uncertainty of system parameters, unknown load torque and current loop tracking error, the speed loop mathematical model of the permanent magnet synchronous motor can be rewritten as:

[0024]

[0025] Among them, k t0 , J0, B0 correspond to the nominal values ​​of electromagnetic torque coefficient, moment of inertia and damping coefficient respectively; d represents the lumped disturbance term, and the expression is:

[0026]

[0027] Formula (5) and Formula (6) are mathematical models of permanent magnet synchronous motors that consider periodic and non-periodic disturbances. Compared with the traditional mathematical model of permanent magnet synchronous motors, they not only consider non-periodic disturbances such as system parameter uncertainty, unknown load torque, and current loop tracking error, but also introduce periodic torque pulsation. The control method proposed in the present invention further suppresses torque pulsation.

[0028] Furthermore, a disturbance observer based on iterative learning strategy is designed to estimate the total disturbance including torque ripple of the permanent magnet synchronous motor. Specifically:

[0029] The estimation capability of the traditional disturbance observer for periodic disturbance is improved by introducing an iterative learning control law into the disturbance observer equation. The estimation of the lumped disturbance of the permanent magnet synchronous motor is represented by the disturbance observer expression of the iterative learning strategy. The disturbance observer expression based on the iterative learning strategy is:

[0030]

[0031] In the formula, e j and e j-1 They correspond to the estimated errors of the rotation speed in the j-th and j-1-th iteration cycles respectively; ω mj , and They correspond to the speed, speed estimation, expected q-axis current and disturbance estimation of the j-th iteration period respectively; K represents the observer gain coefficient; the speed estimation error is updated by the P-type iterative learning law with a forgetting factor, γ represents the learning gain; ξ represents the forgetting factor, which should satisfy 0≤ξ<1 according to the necessary and sufficient conditions for the convergence of the iterative error.

[0032] Furthermore, a disturbance observer based on an iterative learning strategy takes the measured rotational speed value and the q-axis current given value as input signals and outputs an estimate of the lumped disturbance.

[0033] Furthermore, a fast integral terminal sliding mode controller of a speed loop of a permanent magnet synchronous motor takes an estimate of a lumped disturbance output by a disturbance observer, a given speed value and a measured speed value as input signals, and outputs a q-axis current given value.

[0034] Furthermore, the speed loop sampling frequency of the permanent magnet synchronous motor is 1-4kHz.

[0035] Furthermore, the speed observation error data storage interval of the permanent magnet synchronous motor is set to 1°.

[0036] A permanent magnet synchronous motor speed control device, comprising:

[0037] Model building module, used to build mathematical models of permanent magnet synchronous motors considering periodic and non-periodic disturbances;

[0038] The disturbance observer design module is used to design a disturbance observer based on an iterative learning strategy to estimate the total disturbance of the permanent magnet synchronous motor, including torque ripple.

[0039] The controller design module designs a fast integral terminal sliding mode speed controller based on disturbance observer to achieve pulsation suppression of permanent magnet synchronous motor.

[0040] A computer-readable storage medium stores one or more programs, and the one or more programs can be executed by one or more processors to implement the steps in any of the above-mentioned permanent magnet synchronous motor speed control methods.

[0041] A terminal device comprises: a processor, a memory and a communication bus; the memory stores a computer-readable program executable by the processor;

[0042] The communication bus realizes the connection and communication between the processor and the memory;

[0043] When the processor executes the computer-readable program, the steps in any one of the above-mentioned permanent magnet synchronous motor speed control methods are implemented.

[0044] The permanent magnet synchronous motor speed control method and device in the embodiment of the present invention include: establishing a mathematical model of the permanent magnet synchronous motor considering periodic and non-periodic disturbances; designing a disturbance observer based on an iterative learning strategy to estimate the lumped disturbance including torque pulsation suffered by the permanent magnet synchronous motor; designing a fast integral terminal sliding mode speed controller based on the disturbance observer to achieve pulsation suppression of the permanent magnet synchronous motor. The present invention effectively suppresses the torque pulsation phenomenon by designing a new type of fast integral terminal sliding mode and a disturbance observer based on iterative learning, thereby ensuring that the control system has good robustness and dynamic response performance, so as to achieve rapid tracking of the motor speed, and effectively improve the tracking accuracy for motor systems with greater influence of periodic torque pulsation. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0046] Figure 1 It is a flow chart of the permanent magnet synchronous motor speed control method of the present invention;

[0047] Figure 2 It is a block diagram of a disturbance observer based on an iterative learning strategy of the present invention;

[0048] Figure 3 It is a block diagram of the transfer function of the disturbance observer based on the iterative learning strategy of the present invention;

[0049] Figure 4 This is a block diagram of the fast integral terminal sliding mode speed controller of the present invention;

[0050] Figure 5 This is a structural block diagram of a permanent magnet synchronous motor speed control system based on fast integral terminal sliding mode and periodic disturbance compensation according to the present invention;

[0051] Figure 6 It is a speed test curve diagram of the present invention;

[0052] Figure 7 and Figure 8 The speed response curve of the motor of the present invention when the speed is 100r / min and 20r / min and the Fourier amplitude spectrum in steady state;

[0053] Fig. 9 The comparison of the percentages of the 1st, 2nd, 6th and 12th harmonics of the Fourier analysis of the steady state when the motor speed of the present invention is 100r / min and 20r / min;

[0054] Fig.10 The disturbance estimation result of the disturbance observer based on the iterative learning strategy when the torque pulsation is introduced in the present invention;

[0055] Fig.11 This is a diagram of the estimation result of the lumped disturbance of the present invention;

[0056] Fig.12 A comparison diagram of the velocity loop test results and Fourier analysis without and with the proposed disturbance observer of the present invention;

[0057] Fig.13 A permanent magnet synchronous motor speed control device according to the present invention;

[0058] Fig.14 The present invention is a schematic diagram of a terminal device. DETAILED DESCRIPTION

[0059] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. 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 should fall within the scope of protection of the present invention.

[0060] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0061] See also Figure 1 According to an embodiment of the present invention, a permanent magnet synchronous motor speed control method is provided, comprising the following steps:

[0062] S101: Establish a mathematical model of a permanent magnet synchronous motor considering periodic and non-periodic disturbances;

[0063] S102: Design a disturbance observer based on iterative learning strategy to estimate the disturbance and torque ripple of the permanent magnet synchronous motor;

[0064] S103: Design a fast integral terminal sliding mode speed controller based on disturbance observer to achieve pulsation suppression for permanent magnet synchronous motor.

[0065] The present invention effectively suppresses torque pulsation by designing a novel fast integral terminal sliding mode and a disturbance observer based on iterative learning, thereby ensuring that the control system has good robustness and dynamic response performance, so as to achieve rapid tracking of the motor speed and effectively improve the tracking accuracy for motor systems that are greatly affected by periodic torque pulsation.

[0066] In the embodiment, step S101 specifically includes:

[0067] Flux harmonics, cogging torque, inverter nonlinearity and current detection error are the main torque ripple factors. Considering the above factors, the output electromagnetic torque of the permanent magnet synchronous motor is:

[0068]

[0069] Among them, T e and T cog Correspondingly represents the motor electromagnetic torque and cogging torque; θ e , n p The corresponding expression is the electrical angle and pole pair number of the motor; ψ f , ψ 6i Correspondingly represents the permanent magnet flux of the permanent magnet synchronous motor and the 6ith order flux harmonic amplitude; iq , Δi inverter ,Δi offset ,Δi scaling They correspond to the q-axis current, the current error caused by inverter nonlinearity, current sensor offset and scaling, respectively;

[0070] Among them, Δi inverter ,Δi offset ,Δi scaling ,T cog It can be further expressed as:

[0071]

[0072] Among them, R s and L s They correspond to the stator inductance and resistance of the motor, A1, A2, θ5, θ7, V dead They are the harmonic amplitude, initial phase angle and voltage change caused by dead zone effect; Δi a ,i b The corresponding expression is phase current i a ,i b The DC offset, θ1, is dependent on Δi a and i b The constant angle of i s Indicates the amplitude of phase current; k a , k b They correspond to the scaling factors of phase a and phase b currents respectively; T cogi represents the amplitude of the i-th cogging torque harmonic; N c Indicates the least common multiple between the number of motor slots and the number of pole pairs.

[0073] From equations (1) and (2), the flux harmonics, the nonlinearity of the inverter and the cogging torque generate 6 times the harmonic components in the electromagnetic torque, the current sensor offset generates 1 times the harmonic components in the electromagnetic torque, and the current sensor scaling generates 2 times the harmonic components in the electromagnetic torque; therefore, the electromagnetic torque is mainly composed of a DC component and the 1st, 2nd, 6th and 12th harmonic components, which can be simplified as:

[0074]

[0075] Where k represents the harmonic order, T e0 , T ek ,φ k They are respectively expressed as the amplitude and phase angle of the DC component and the harmonic component;

[0076] The motion equation of the permanent magnet synchronous motor is expressed as:

[0077]

[0078] Where J represents the moment of inertia, ω m represents the mechanical angular velocity, B represents the viscous damping coefficient, T L Indicates load torque;

[0079] Further considering the uncertainty of system parameters, unknown load torque and current loop tracking error, the mathematical model of the permanent magnet synchronous motor speed loop can be rewritten as:

[0080]

[0081] Among them, k t0 , J0, B0 correspond to the nominal values ​​of electromagnetic torque coefficient, moment of inertia and damping coefficient respectively; d represents the lumped disturbance term, and the expression is:

[0082]

[0083] The last item of formula (6) is the torque ripple. Therefore, the lumped interference of the permanent magnet synchronous motor is composed of periodic interference and non-periodic interference.

[0084] Formula (5) and Formula (6) are mathematical models of permanent magnet synchronous motors that consider periodic and non-periodic disturbances. Compared with the traditional mathematical model of permanent magnet synchronous motors, they not only consider non-periodic disturbances such as system parameter uncertainty, unknown load torque, and current loop tracking error, but also introduce periodic torque pulsation. The control method proposed in the present invention further suppresses torque pulsation.

[0085] In the embodiment, step S102 specifically includes:

[0086] The estimation capability of the traditional disturbance observer for periodic disturbance is improved by introducing an iterative learning control law into the disturbance observer equation. The estimation of the lumped disturbance of the permanent magnet synchronous motor is represented by the disturbance observer expression of the iterative learning strategy. The disturbance observer expression based on the iterative learning strategy is:

[0087]

[0088] In the formula, e j and e j-1 They correspond to the estimated errors of the rotation speed in the j-th and j-1-th iteration cycles respectively; ω mj , and They correspond to the speed, speed estimation, expected q-axis current and disturbance estimation of the j-th iteration cycle respectively; K represents the observer gain coefficient; the speed estimation error is updated by the P-type iterative learning law with a forgetting factor, γ represents the learning gain; ξ represents the forgetting factor, which should satisfy 0≤ξ<1 according to the necessary and sufficient conditions for the iterative error to converge; according to formula (7), reference Figure 2 Block diagram of the observer.

[0089] exist Figure 2 In the s domain, the storage unit used to store the estimated error is represented by e -τs , so the transfer function diagram of the disturbance observer based on iterative learning strategy is as follows Figure 3 shown.

[0090] The transfer function from disturbance to disturbance estimate can be expressed as:

[0091]

[0092] In order to suppress torque harmonics, e j-1 and e j The time delay between the two, i.e. the iteration period τ, should satisfy where ω e is the fundamental frequency of the torque harmonic; the signal frequency of the disturbance is considered to be 6ω e Therefore, j = 6ω e but When ξ=0, the above formula is equal to 1, indicating that the torque harmonics can be fully estimated. Similarly, the 12th or higher order torque harmonics can be fully observed. At the same time, when the disturbance is concentrated at low frequency, 1-(1-ξ)e -τs < s <1, the system can be regarded as a low-pass filter with improved performance; in addition, it can be seen from the above formula that the smaller the value of ξ, the more significant the cumulative effect of the sudden load disturbance contained in the control signal, and it may even lead to the divergence of the iterative learning algorithm; therefore, the value of ξ cannot be too small; taking into account the conditions including the convergence of the iterative error, a value near 0.1 is usually selected; the selection of γ and K needs to take into account the observation error and noise.

[0093] In the embodiment, step S103 is specifically as follows:

[0094] The integral terminal sliding mode control has been widely used in the field of servo control because of its advantages: 1) improving the robustness of the system approaching stage; 2) the tracking error will tend to zero in a finite time; 3) no singularity problem will occur in the control law; 4) the choice of gain depends only on the upper bound of the unknown disturbance. However, when the tracking error of the traditional integral terminal sliding mode control is far away from the equilibrium point, the convergence speed decreases, which is lower than the traditional integral sliding surface; define the speed tracking error:

[0095]

[0096] in, Represents the motor target speed, and the expression of the traditional integral terminal sliding surface is as follows:

[0097] s(t)=e(t)+β∫0t |e(τ)| p / q sgn(e(τ))dτ (10)

[0098] Wherein, β>0; 0<p / q<1, and p and q are positive odd numbers, sgn(·) represents the sign function; when the sliding mode motion is in the sliding mode stage, that is, s=0, the following equation holds.

[0099] Since 0<p / q<1, when |e|>>1, that is, the velocity tracking error is far away from the equilibrium point, the convergence speed of the velocity tracking error decreases.

[0100] This application designs a fast integral terminal sliding mode speed controller based on a disturbance observer to achieve pulsation suppression for a permanent magnet synchronous motor. Compared with the traditional integral terminal sliding mode surface, it ensures that when the speed tracking error is far away from the equilibrium point, the convergence speed of the speed tracking error is improved. At the same time, the disturbance feedforward compensation estimated by the disturbance observer based on the iterative learning strategy is added to the sliding mode control law, which can reduce the switching gain of the sliding mode control item and thus weaken the chattering phenomenon. The fast integral terminal sliding mode surface expression is as follows:

[0101] s(t)=e(t)+∫0 t [αsgn(e(τ))+β|e(τ)| p / q sgn(e(τ))]dτ (11)

[0102] Where, s(t) represents the sliding surface, e(t) represents the deviation between the given speed value and the measured speed value, the term defines the speed tracking error, α, β are positive coefficients, 0<p / q<1, and p and q are positive odd numbers, sgn() represents the sign function; when s=0, When |e|>>1, due to the term αsgn(e) Increase, to ensure that when the speed tracking error is far away from the equilibrium point, the convergence speed of the speed tracking error is improved; let the initial value of the integral term be -e(0) and choose the convergence law satisfy Then the system will remain on the sliding surface s(t) = 0;

[0103] Then, by solving equation (11), we can calculate the time it takes for the motor speed tracking error to converge to zero: The property that the integral terminal sliding mode tracking error tends to zero in a finite time is not affected; in actual experiments, the inverse tangent function or saturation function can be used to replace the sign function to further weaken the "jittering".

[0104] Design sliding mode reaching law formula:

[0105]

[0106] Wherein, f is the terminal term coefficient, g is the exponential term coefficient, 0<m / n<1, and m and n are positive odd numbers.

[0107] By taking the derivative of equation (11) and combining equations (12), (7) and (5), we can obtain the sliding mode control law based on the fast integral terminal sliding mode and the disturbance observer based on the iterative learning strategy:

[0108]

[0109] refer to Figure 4 , is the block diagram of the sliding mode speed controller based on fast integral terminal.

[0110] The stability of the fast integral terminal sliding mode controller is proved below based on Lyapunov stability theory:

[0111] Construct a Lyapunov function of the following form:

[0112] Taking the derivative of the Lyapunov function, combining equations (11), (9), and (5), and substituting them into the control law equation (13), we can obtain:

[0113]

[0114] The above formula shows that in In this case, the speed error (9) of the system converges to zero under the control law (13).

[0115] refer to Figures 5 to 11 , the present invention is described in detail by performing simulation experiments below:

[0116] Figure 5 The present invention is a structural block diagram of a permanent magnet synchronous motor speed control system based on fast integral terminal sliding mode and periodic disturbance compensation. In this embodiment, the disturbance observer based on the iterative learning strategy takes the measured speed value and the q-axis current set value as input signals, and outputs an estimate of the lumped disturbance; the fast integral terminal sliding mode controller located in the speed loop takes the estimate of the lumped disturbance, the set speed value and the measured speed value as input signals, and outputs a q-axis current set value.

[0117] The speed observation error data storage can be realized through the memory of DSP and FPGA. Usually, the speed loop sampling frequency of permanent magnet synchronous motor is 1-4kHz. Due to the limited memory of the processor, the speed observation error data storage interval can be set to 1°; the cogging torque repeats with the motor electrical angle. When the motor electrical angle jumps from 360° to 0°, the number of iterations increases by 1; for any electrical angle, when the motor rotates, each speed loop sampling cycle stores the speed observation error of the electrical angle rounded up to the current electrical angle into the memory, and at the same time, the speed observation error corresponding to the current electrical angle of the previous iteration process is obtained by linear interpolation, that is:

[0118] e j-1 (θ e )=(e j-1 (θ e +1)-e j-1 (θ e ))·(θ e -θ e )+e j-1 (θ e ) (14)

[0119] Among them, θ e Indicates the electrical angle value is rounded down, e j-1 (θ e ) represents the electrical angle θ of the j-1th iteration e The speed observation error corresponding to the rounding down point.

[0120] In order to prove the effectiveness and advancement of the control method of the present invention, a simulation comparison experiment was carried out; first, without considering the torque pulsation and without introducing the disturbance observer, the speed regulation performance and anti-interference ability of the present invention and the traditional integral sliding mode and integral terminal sliding mode speed controller were compared through simulation. In order to highlight the fairness of the comparison, the current loop adopted a decoupled current controller with the same parameters.

[0121] Further considering the torque pulsation, in order to verify the disturbance estimation ability of the disturbance observer based on the iterative learning strategy, the method proposed in the present invention is compared with the extended state observer, the sliding mode disturbance observer and the generalized proportional integral observer; finally, the torque pulsation suppression ability of the control method of the present invention is evaluated.

[0122] Figure 6 The speed test curves are shown in Figure 1. The motor speed is 100r / min, the current loop is decoupled current control, and the speed loop is respectively the traditional integral sliding mode, integral terminal sliding mode and fast integral terminal sliding mode controller. The three control algorithms use the same reaching law and coefficients. It can be seen from the figure that the integral sliding mode, integral terminal sliding mode and fast integral terminal sliding mode algorithms take about 1.53, 0.96 and 0.56s to adjust the motor to the target speed respectively. The traditional integral terminal sliding mode approaches the target speed faster when the speed error is small, and the approach speed is less than the integral sliding mode when the speed error is large. The approach speed of the integral sliding mode decreases with the decrease of the tracking error and cannot reach the target speed in a limited time. The proposed algorithm has a faster response speed. At the same time, in order to verify the anti-interference ability of the proposed method, the simulation adds a load disturbance of 5N·m at t=2s and unloads the load disturbance at t=4s. It can be seen from the figure that the motor speed fluctuation amplitude and recovery time of the proposed method are smaller than those of the other two methods when facing load disturbances.

[0123] Figure 7 , Figure 8 and Fig. 9 They are the speed response curves of the motor with speeds of 100r / min and 20r / min, and the 1st, 2nd, 6th and 12th harmonic amplitude percentages of the Fourier analysis in steady state. It can be seen from the figure that there are obvious harmonics in the motor speed signal; at the same time, it can be seen that compared with the high-speed motor, the torque pulsation phenomenon is more serious under the condition of low-speed operation of the motor. This is because according to formula (2), when the motor runs at low speed, the influence of the inverter nonlinearity is more obvious, which also shows the accuracy of the model established in step one.

[0124] Fig.10 The disturbance estimation results of the disturbance observer based on iterative learning strategy when introducing torque ripple. It can be seen from the figure that after four iterations, the proposed method can completely estimate the lumped disturbance; Fig.11 The estimation results of the lumped disturbance by the linear extended state observer, the sliding mode-based disturbance observer, the generalized proportional-integral disturbance observer and the proposed observer are shown in the figure. Compared with the proposed method, the observation results of other methods are difficult to observe high-frequency harmonics, and the observations of low-frequency components have varying degrees of amplitude changes and phase lags. In local areas, the size of the observation error is even close to the peak value of the lumped interference term, which indicates that the torque pulsation phenomenon seriously affects the performance of the disturbance observer; while the method of the present invention can effectively observe the lumped disturbance composed of the torque pulsation term.

[0125] In order to further verify the ability of the proposed technology to suppress torque pulsation, the speed loop adopts a fast integral terminal sliding mode controller. Fig.12 A comparison of the speed loop test results and Fourier analysis without and with the proposed disturbance observer is given; it can be seen from the figure that when the disturbance observer is not introduced, the speed fluctuation is 0.46r / min, and the fundamental amplitude of the Fourier analysis is 4.986e-2. After the proposed disturbance observer is introduced, the torque pulsation is completely suppressed and the harmonic components in the speed can be ignored.

[0126] The above experimental results show that the permanent magnet synchronous motor speed control method based on fast integral terminal sliding mode and periodic disturbance compensation of the present invention not only has good rapid response capability, but also has robustness to parameter changes and the ability to suppress torque pulsation.

[0127] See also Fig.13 According to an embodiment of the present invention, a permanent magnet synchronous motor speed control device is provided, comprising:

[0128] A model building module 100 is used to build a mathematical model of a permanent magnet synchronous motor taking into account periodic and non-periodic disturbances;

[0129] A disturbance observer design module 200 is used to design a disturbance observer based on an iterative learning strategy to estimate the disturbance and torque ripple of the permanent magnet synchronous motor;

[0130] The controller design module 300 designs a fast integral terminal sliding mode speed controller based on a disturbance observer to achieve pulsation suppression of the permanent magnet synchronous motor.

[0131] The present invention effectively suppresses torque pulsation by designing a novel fast integral terminal sliding mode and a disturbance observer based on iterative learning, thereby ensuring that the control system has good robustness and dynamic response performance, so as to achieve rapid tracking of the motor speed and effectively improve the tracking accuracy for motor systems that are greatly affected by periodic torque pulsation.

[0132] Based on the above-mentioned permanent magnet synchronous motor speed control method, this embodiment provides a computer-readable storage medium, which stores one or more programs. The one or more programs can be executed by one or more processors to implement the steps in the permanent magnet synchronous motor speed control method as in the above-mentioned embodiment.

[0133] A terminal device comprises: a processor, a memory and a communication bus; the memory stores a computer-readable program that can be executed by the processor; the communication bus realizes the connection and communication between the processor and the memory; when the processor executes the computer-readable program, the steps in the above-mentioned permanent magnet synchronous motor speed control method are realized.

[0134] Based on the above permanent magnet synchronous motor speed control method, the present application provides a terminal device, such as Fig.14 As shown, it includes at least one processor (processor) 20; display screen 21; and memory (memory) 22, and may also include a communications interface (Communications Interface) 23 and a bus 24. Among them, the processor 20, the display screen 21, the memory 22 and the communication interface 23 can communicate with each other through the bus 24. The display screen 21 is configured to display a preset user guide interface in the initial setting mode. The communication interface 23 can transmit information. The processor 20 can call the logic instructions in the memory 22 to execute the method in the above embodiment.

[0135] In addition, the logic instructions in the memory 22 can be implemented in the form of software functional units and can be stored in a computer-readable storage medium when sold or used as an independent product.

[0136] The memory 22 is a computer-readable storage medium that can be configured to store software programs, computer executable programs, such as program instructions or modules corresponding to the methods in the embodiments of the present disclosure. The processor 20 executes functional applications and data processing by running the software programs, instructions or modules stored in the memory 22, that is, implementing the methods in the above embodiments.

[0137] The memory 22 may include a program storage area and a data storage area, wherein the program storage area may store an operating system and at least one application required for a function; the data storage area may store data created according to the use of the terminal device, etc. In addition, the memory 22 may include a high-speed random access memory and may also include a non-volatile memory. For example, a variety of media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a disk or an optical disk, may also be a transient storage medium.

[0138] In addition, the specific process of loading and executing the multiple instruction processors in the above-mentioned storage medium and the terminal device has been described in detail in the above-mentioned method, and will not be described one by one here.

[0139] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A permanent magnet synchronous motor speed control method, characterized in that: The following steps are involved: Establish a mathematical model of permanent magnet synchronous motor considering periodic and non-periodic disturbances; Designing a disturbance observer based on an iterative learning strategy to estimate the total disturbance including torque pulsation suffered by the permanent magnet synchronous motor; Designing a fast integral terminal sliding mode speed controller based on disturbance observer to achieve pulsation suppression of the permanent magnet synchronous motor; The mathematical model of the permanent magnet synchronous motor considering periodic and non-periodic disturbances is specifically established as follows: Assume that the output electromagnetic torque of the permanent magnet synchronous motor is: Among them, T e and T cog Correspondingly represents the motor electromagnetic torque and cogging torque; θ e , n p The corresponding expression is the electrical angle and pole pair number of the motor; ψ f , ψ 6i Correspondingly represents the permanent magnet flux of the permanent magnet synchronous motor and the 6ith order flux harmonic amplitude; i q , Δi inverter ,Δi offset ,Δi scaling They correspond to the q-axis current, the current error caused by inverter nonlinearity, current sensor offset and scaling, respectively; Among them, Δi inverter ,Δi offset ,Δi scaling ,T cog It can be further expressed as: Among them, R s and L s They correspond to the stator inductance and resistance of the motor, A1, A2, θ5, θ7, V dead They are the harmonic amplitude, initial phase angle and voltage change caused by dead zone effect; Δi a , Δi b The corresponding expression is phase current i a ,i b The DC offset, θ1, is dependent on Δi a and Δi b The constant angle of i s Indicates the amplitude of phase current; k a , k b They correspond to the scaling factors of phase a and phase b currents respectively; T cogi represents the amplitude of the i-th cogging torque harmonic; N c Indicates the least common multiple between the number of motor teeth and the number of pole pairs; From equations (1) and (2), the flux harmonics, the nonlinearity of the inverter and the cogging torque generate 6 times the harmonic components in the electromagnetic torque, the current sensor offset generates 1 times the harmonic components in the electromagnetic torque, and the current sensor scaling generates 2 times the harmonic components in the electromagnetic torque; therefore, the electromagnetic torque is mainly composed of a DC component and the 1st, 2nd, 6th and 12th harmonic components, which can be simplified as: Where k represents the harmonic order, T e0 , T ek ,φ k They are respectively expressed as the amplitude and phase angle of the DC component and the harmonic component; The motion equation of the permanent magnet synchronous motor is expressed as: Where J represents the moment of inertia, ω m represents the mechanical angular velocity, B represents the viscous damping coefficient, T L Indicates load torque; Taking into account the uncertainty of system parameters, unknown load torque and current loop tracking error, the speed loop mathematical model of the permanent magnet synchronous motor can be rewritten as: Among them, k t0 , J0, B0 correspond to the nominal values ​​of electromagnetic torque coefficient, moment of inertia and damping coefficient respectively; d represents the lumped disturbance term, and the expression is: The design of the disturbance observer based on the iterative learning strategy to estimate the total disturbance including torque ripple suffered by the permanent magnet synchronous motor is specifically as follows: The estimation capability of the traditional disturbance observer for periodic disturbance is improved by introducing an iterative learning control law into the disturbance observer equation. The estimation of the lumped disturbance of the permanent magnet synchronous motor is represented by the disturbance observer expression of the iterative learning strategy. The disturbance observer expression based on the iterative learning strategy is: In the formula, e j and e j-1 They correspond to the estimated errors of the rotation speed in the j-th and j-1-th iteration cycles respectively; ω mj , and They correspond to the speed, speed estimation, expected q-axis current and disturbance estimation of the j-th iteration period respectively; K represents the observer gain coefficient; the speed estimation error is updated by the P-type iterative learning law with a forgetting factor, γ represents the learning gain; ξ represents the forgetting factor, which should satisfy 0≤ξ<1 according to the necessary and sufficient conditions for the convergence of the iterative error.

2. The permanent magnet synchronous motor speed control method according to claim 1, characterized in that: The disturbance observer based on the iterative learning strategy takes the measured rotation speed value and the q-axis current given value as input signals, and outputs an estimate of the lumped disturbance.

3. The permanent magnet synchronous motor speed control method according to claim 2, characterized in that: The fast integral terminal sliding mode speed controller of the permanent magnet synchronous motor speed loop takes the estimation of the lumped disturbance output by the disturbance observer, the given speed value and the measured speed value as input signals, and outputs a q-axis current given value.

4. The permanent magnet synchronous motor speed control method according to claim 3, characterized in that: The speed loop sampling frequency of the permanent magnet synchronous motor is 1-4kHz.

5. The permanent magnet synchronous motor speed control method according to claim 3, characterized in that: The speed observation error data storage interval of the permanent magnet synchronous motor is set to 1°.

6. A permanent magnet synchronous motor speed control device, characterized in that: A permanent magnet synchronous motor speed control method as claimed in any one of claims 1 to 5 is adopted; the speed control device comprises: Model building module, used to build mathematical models of permanent magnet synchronous motors considering periodic and non-periodic disturbances; A disturbance observer design module is used to design a disturbance observer based on an iterative learning strategy to estimate the total disturbance including torque ripple suffered by the permanent magnet synchronous motor; A controller design module designs a fast integral terminal sliding mode speed controller based on a disturbance observer to achieve pulsation suppression of the permanent magnet synchronous motor.

7. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores one or more programs, and the one or more programs can be executed by one or more processors to implement the steps in the permanent magnet synchronous motor speed control method as described in any one of claims 1-5.

8. A terminal device, characterized in that: include: Processor, memory and communication bus; The memory stores a computer-readable program executable by the processor; The communication bus realizes the connection and communication between the processor and the memory; When the processor executes the computer-readable program, the steps in the permanent magnet synchronous motor speed control method as described in any one of claims 1 to 5 are implemented.

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