A permanent magnet synchronous motor current control method and system

Abstract

The present application discloses a permanent magnet synchronous motor current control method and system, which are applied to the field of permanent magnet synchronous motor control technology. The method comprises: establishing a permanent magnet synchronous motor current equation; establishing an extended state observer according to the permanent magnet synchronous motor current equation; outputting an error feedback control rate according to the extended state observer; the present application can estimate and compensate for non-periodic disturbances more quickly, and can also estimate and compensate for periodic disturbances efficiently, thereby further improving the robustness of permanent magnet synchronous motor current control.

Description

Technical Field

[0001] The present application relates to the technical field of control of permanent magnet synchronous motors, and in particular to a current control method and system for permanent magnet synchronous motors. Background Art

[0002] Permanent magnet synchronous motors are widely used in electric vehicles, CNC machine tools, robot servo control and other fields due to their advantages such as high power density, low power loss and high precision. However, there are various disturbances in the actual permanent magnet synchronous motor system. Non-periodic disturbances such as cross-coupling disturbances, parameter perturbations and external disturbances in the current loop reduce the stability of the system, and periodic disturbances such as flux harmonics and voltage harmonics reduce the control accuracy of the system. At present, the widely used control strategies for non-periodic disturbances in permanent magnet synchronous motors include active disturbance rejection control, intelligent control, robust control and sliding mode control. Among them, the core extended state observer of active disturbance rejection control is an effective method to suppress non-periodic disturbances.

[0003] However, traditional linear and nonlinear extended state observers can only converge on infinite or finite boundaries. For periodic disturbances in permanent magnet synchronous motors, resonant controllers, repetitive controllers and iterative learning controllers are effective methods to suppress periodic disturbances; quasi-resonant controllers are widely used in practical systems due to their superior performance. Therefore, in order to further improve the convergence speed of the observer and effectively suppress periodic disturbances, the present application innovatively proposes a permanent magnet synchronous motor current control method and system based on fixed-time stability theory and quasi-resonant control theory. Among them, the quasi-resonant fixed-time extended state observer can converge within a fixed time independent of the initial state of the observer, and can estimate and compensate for periodic disturbances, effectively improving the dynamic performance and steady-state performance of the permanent magnet synchronous motor system. Summary of the invention

[0004] The purpose of this application is to provide a permanent magnet synchronous motor current control method and system to solve the above-mentioned problems.

[0005] To achieve the above objectives, this application provides the following technical solutions:

[0006] The present application provides a permanent magnet synchronous motor current control method, comprising:

[0007] Establish the current equation of permanent magnet synchronous motor;

[0008] Establishing an extended state observer according to the permanent magnet synchronous motor current equation;

[0009] An error feedback control rate is output according to the extended state observer.

[0010] Furthermore, in the step of establishing the permanent magnet synchronous motor current equation, the dq axis current equation of the permanent magnet synchronous motor in the synchronous rotating coordinate system is:

[0011]

[0012] Among them, i d and i q are the stator currents of the d-axis and q-axis respectively, u d and u q are the stator voltages of the d-axis and q-axis, R s is the stator resistance, L d and L q are the stator inductances of the d-axis and q-axis, ω e is the electrical angular velocity, ψ f is the rotor flux;

[0013] According to the non-periodic disturbance, the dq axis current equation of the permanent magnet synchronous motor can be rewritten as:

[0014]

[0015]

[0016]

[0017] Among them, d dap and d qap are the non-periodic perturbations of the d-axis and q-axis respectively, d dco and d qco are the cross-coupling disturbances of the d-axis and q-axis, d dpa and d qpa are the disturbances caused by parameter perturbations on the d-axis and q-axis, respectively. dex and d qex are the external uncertain disturbances on the d-axis and q-axis respectively, L d0 =L q0 =L s0 is the nominal value of the d-axis and q-axis stator inductance, R s0 is the nominal value of the stator resistance, ψ f0 is the nominal value of the rotor flux, where ΔL d(q) =L d(q) -L d(q)0 , ΔR s =R s -R s0 , Δψ f =ψ f -ψ f0 .

[0018] Furthermore, the periodic disturbance of the permanent magnet synchronous motor current includes flux harmonics and inverter nonlinearity;

[0019] The flux harmonics of the dq axis of the permanent magnet synchronous motor are expressed as:

[0020]

[0021] Among them, ψ dh and ψ qh are the magnetic flux harmonics of the d-axis and q-axis, ψ d6n and ψ q6n are the amplitudes of the 6nth harmonic of the d-axis and q-axis respectively;

[0022] The voltage harmonics of the dq axis of the permanent magnet synchronous motor are expressed as

[0023]

[0024] Among them, u dh and u qh are the voltage harmonics of the d-axis and q-axis, τ dead and τ s They are dead time and sampling time, U dc is the DC bus voltage;

[0025] According to the flux harmonics and the voltage harmonics, the periodic disturbance of the dq axis of the permanent magnet synchronous motor is expressed as:

[0026]

[0027] Among them, d dp and d qp are the periodic perturbations of the d-axis and q-axis respectively;

[0028] According to equations (2) and (7), the permanent magnet synchronous motor current equation is rewritten as:

[0029]

[0030] Among them, d d =d dap +d dp and d q =d qap +d qp are the total disturbances of the d-axis and q-axis respectively, To control the gain.

[0031] Furthermore, the step of establishing an extended state observer according to the permanent magnet synchronous motor current equation specifically includes the following steps:

[0032] An extended state model of the permanent magnet synchronous motor d(q) axis current equation is established according to the permanent magnet synchronous motor current equation;

[0033] Based on the fixed-time control theory and quasi-resonant control theory, a quasi-resonant fixed-time dilation state observer is designed.

[0034] The fixed-time convergence characteristics are analyzed by the quasi-resonant fixed-time dilated state observer.

[0035] Furthermore, in the step of establishing an extended state model of the permanent magnet synchronous motor d (q) axis current equation according to the permanent magnet synchronous motor current equation, the following steps are specifically included:

[0036] According to the permanent magnet synchronous motor current equation, take x 1 =i d(q) , x 2 =d d(q) , u=u d(q) ,

[0037] Then the extended state observation model of the permanent magnet synchronous motor dq axis current equation is expressed as:

[0038]

[0039] in,

[0040] Furthermore, based on the fixed time control theory and the quasi-resonant control theory, the step of designing a quasi-resonant fixed time dilation state observer specifically includes the following steps:

[0041] The design of the quasi-resonant fixed-time dilation state observer is as follows:

[0042]

[0043]

[0044] in, is the estimated value of the state vector x, γ i =iγ-(i-1)(i=1,2), γ∈(1,+∞); is the estimated periodic disturbance, ω c , k r and ω h are the cutoff frequency, resonant gain and resonant frequency of the quasi-resonant controller, ω 0 ≥1 is a coefficient related to the observer bandwidth, where the observer gain vector K = [k 1 k 2 ] T =[2 1] T , sgn * (·)=|·| *sign(·), sign(·) is the sign function.

[0045] Furthermore, in the step of analyzing the fixed-time convergence characteristic by the quasi-resonant fixed-time dilation state observer, the following steps are specifically included:

[0046] The estimated error differential equation of the observer obtained according to the extended state observer and the quasi-resonant fixed-time extended state observer is:

[0047]

[0048] in, is the state estimation error, Reason The vector field formed is E = [1 0] T ;

[0049] The double limit homogeneous correction term is constructed by the quasi-resonant fixed-time dilated state observer Therefore, when the periodic disturbance h of the q-axis is 0, the estimated error differential equation (12) is related to the following system in the limits of 0 and ∞:

[0050]

[0051] in, Reason The vector field formed, α i =iα-(i-1)(i=1,2), α∈(1-1 / 2,+∞);

[0052] System (13) satisfies the weight vector r(α)=[r 1 r 2 ] T , r i =(i-1)α-(i-2)(i=1,2) The homogeneity is α-1;

[0053] Therefore, there exists ε>0, and for all α∈(1-ε,1+ε), the system (13) is asymptotically stable.

[0054] Furthermore, the system (13) has a homogeneous Lyapunov function that satisfies the homogeneity of the weight vector r(α) being 2, and its first order is a quadratic Lyapunov function in the linear case The first level set It is expressed as:

[0055]

[0056] Where S is the Riccati equation S+A T S+SA-CT The solution of C = 0, At the same time, the derivative of the Lyapunov function according to the solution of system (13) satisfies the following inequality:

[0057]

[0058] in,

[0059] When the estimated error differential equation ω 0 =1, The approximations at 0 and ∞ are and Using equation (14) to define the homogeneous Lyapunov function structure, two homogeneous Lyapunov functions are constructed, which are defined at 0 and ∞ as and W γ ,γ>1, and define the following two error sets:

[0060]

[0061]

[0062] Define the homogeneous Lyapunov function as:

[0063]

[0064] In the observer estimation error differential equation (12), take Then the estimated error differential equation (12) can be rewritten as:

[0065]

[0066] The Lyapunov function of the differential equation (18) is constructed in the form of the homogeneous Lyapunov function (17). Specifically:

[0067] Existence 1 ∈(0,ε) makes the following inequality hold:

[0068]

[0069] in, γ∈(1,1+ε 1 ).

[0070] Furthermore, the step of outputting an error feedback control rate according to the extended state observer specifically includes the following steps:

[0071] The d(q) axis reference current of the permanent magnet synchronous motor is defined as Then the d(q) axis current tracking error is The error expression using error feedback control is:

[0072]

[0073] Among them, k d(q)p is the proportionality coefficient;

[0074] According to the quasi-resonant fixed-time dilated state observer (10), the total disturbance d on the d(q) axis is d(q) It is estimated by the observer as:

[0075]

[0076] Substitute equation (21) into equation (20); the control law is obtained as follows:

[0077]

[0078] The present application also provides a permanent magnet synchronous motor current control system, comprising:

[0079] Establish module: establish permanent magnet synchronous motor current equation;

[0080] Calculation module: establishing an extended state observer according to the permanent magnet synchronous motor current equation;

[0081] Output module: outputs error feedback control rate according to the extended state observer.

[0082] The present application provides a permanent magnet synchronous motor current control method and system, which has the following features:

[0083] Beneficial effects:

[0084] This application establishes a permanent magnet synchronous motor current equation and an extended state observer, analyzes the extended state observer, and finally designs an error feedback control rate based on the extended state observer, thereby improving the convergence speed of the observer and effectively suppressing periodic disturbances; the extended state observer utilizes quasi-resonant control theory and introduces quasi-resonant correction terms to effectively estimate and compensate for periodic disturbances such as flux harmonics and voltage harmonics present in the current loop, and converges within a fixed time independent of the initial state of the observer, thereby effectively improving the dynamic performance and steady-state performance of the permanent magnet synchronous motor system. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] Figure 1 A schematic flow chart of a permanent magnet synchronous motor current control method according to Embodiment 1 of the present application;

[0086] Figure 2 This is a structural diagram of an active disturbance rejection control method based on a quasi-resonant fixed-time dilated state observer according to Example 1 of the present application;

[0087] Figure 3 This is a structural diagram of a simulation model of a permanent magnet synchronous motor servo control system according to Example 1 of the present application;

[0088] Figure 4 This is a diagram showing the estimation results of the linear extended state observer and the quasi-resonant fixed-time extended state observer for step disturbances according to Example 1 of the present application;

[0089] Figure 5 This is a diagram showing the comparison of simulation results of the d-axis current curve of Example 1 of the present application;

[0090] Figure 6 This is a diagram showing the q-axis current curve and Fourier analysis comparison simulation results of Example 1 of the present application;

[0091] Figure 7 This is a comparison simulation result diagram of the A phase current curve of Example 1 of the present application;

[0092] Figure 8 This is a structural schematic diagram of a permanent magnet synchronous motor current control system according to Example 2 of the present application. DETAILED DESCRIPTION

[0093] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0094] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0095] Example 1

[0096] See also Figure 1 , is a flow chart of a permanent magnet synchronous motor current control method according to Embodiment 1 of the present application; specifically comprising the following steps:

[0097] S1: Establish the current equation of permanent magnet synchronous motor.

[0098] In this embodiment, the dq-axis current equation of the permanent magnet synchronous motor in the synchronous rotating coordinate system is:

[0099]

[0100] Among them, i d and i q are the stator currents of the d-axis and q-axis respectively, u d and uq are the stator voltages of the d-axis and q-axis, R s is the stator resistance, L d and L q are the stator inductances of the d-axis and q-axis, ω e is the electrical angular velocity, ψ f is the rotor flux;

[0101] According to the non-periodic disturbance, the dq axis current equation of the permanent magnet synchronous motor can be rewritten as:

[0102]

[0103]

[0104]

[0105] Among them, d dap and d qap are the non-periodic perturbations of the d-axis and q-axis respectively, d dco and d qco are the cross-coupling disturbances of the d-axis and q-axis, d dpa and d qpa are the disturbances caused by parameter perturbations on the d-axis and q-axis, respectively. dex and d qex are the external uncertain disturbances on the d-axis and q-axis respectively, L d0 =L q0 =L s0 is the nominal value of the d-axis and q-axis stator inductance, R s0 is the nominal value of the stator resistance, ψ f0 is the nominal value of the rotor flux, where ΔL d(q) =L d(q) -L d(q)0 , ΔR s =R s -R s0 , Δψ f =ψ f -ψ f0 ;

[0106] The periodic disturbance of the permanent magnet synchronous motor current includes flux harmonics and inverter nonlinearity;

[0107] The flux harmonics of the dq axis of the permanent magnet synchronous motor are expressed as:

[0108]

[0109] Among them, ψ dh and ψ qh are the magnetic flux harmonics of the d-axis and q-axis, ψ d6n and ψ q6nare the amplitudes of the 6nth harmonic of the d-axis and q-axis respectively;

[0110] The voltage harmonics of the dq axis of the permanent magnet synchronous motor are expressed as

[0111]

[0112] Among them, u dh and u qh are the voltage harmonics of the d-axis and q-axis, τ dead and τ s They are dead time and sampling time, U dc is the DC bus voltage;

[0113] According to the flux harmonics and the voltage harmonics, the periodic disturbance of the dq axis of the permanent magnet synchronous motor is expressed as:

[0114]

[0115] Among them, d dp and d qp are the periodic perturbations of the d-axis and q-axis respectively;

[0116] According to equations (2) and (7), the permanent magnet synchronous motor current equation is rewritten as:

[0117]

[0118] Among them, d d =d dap +d dp and d q =d qap +d qp are the total disturbances of the d-axis and q-axis respectively, To control the gain.

[0119] S2: Establishing an extended state observer according to the permanent magnet synchronous motor current equation.

[0120] In this embodiment, the step of establishing an extended state observer according to the permanent magnet synchronous motor current equation specifically includes the following steps S21 to S23, and the implementation method of each step is described in detail below.

[0121] S21: Establishing an extended state model of the permanent magnet synchronous motor d(q) axis current equation according to the permanent magnet synchronous motor current equation.

[0122] Specifically, the following steps are included: according to the permanent magnet synchronous motor current equation, take x 1 =i d(q) , x 2 =d d(q) , u=u d(q) ,

[0123] Then the extended state observation model of the permanent magnet synchronous motor dq axis current equation is expressed as:

[0124]

[0125] in,

[0126] S22: Based on fixed-time control theory and quasi-resonant control theory, a quasi-resonant fixed-time dilation state observer is designed.

[0127] Specifically, the following steps are included: The design of the quasi-resonant fixed time expansion state observer is as follows:

[0128]

[0129]

[0130] in, is the estimated value of the state vector x, γ i =iγ-(i-1)(i=1,2), γ∈(1,+∞); is the estimated periodic disturbance, ω c , k r and ω h are the cutoff frequency, resonant gain and resonant frequency of the quasi-resonant controller, ω 0 ≥1 is a coefficient related to the observer bandwidth, where the observer gain vector K = [k 1 k 2 ] T =[2 1] T , sgn * (·)=|·| * sign(·), sign(·) is the sign function.

[0131] S23: Analyze fixed-time convergence characteristics through the quasi-resonant fixed-time dilation state observer.

[0132] Specifically, the following steps are included: according to the extended state observer and the quasi-resonant fixed-time extended state observer, the estimated error differential equation of the observer is obtained:

[0133]

[0134] in, is the state estimation error, Reason The vector field formed is E = [1 0] T ;

[0135] The double limit homogeneous correction term is constructed by the quasi-resonant fixed-time dilated state observer Therefore, when the periodic disturbance h of the q-axis is 0, the estimated error differential equation (12) is related to the following system in the limits of 0 and ∞:

[0136]

[0137] in, Reason The vector field formed, α i =iα-(i-1)(i=1,2), α∈(1-1 / 2,+∞);

[0138] System (13) satisfies the weight vector r(α)=[r 1 r 2 ] T , r i =(i-1)α-(i-2)(i=1,2) The homogeneity is α-1;

[0139] Therefore, there exists ε>0, and for all α∈(1-ε,1+ε), the system (13) is asymptotically stable.

[0140] In system (13), there exists a homogeneous Lyapunov function that satisfies the homogeneity of the weight vector r(α) to 2, and its first order is a quadratic Lyapunov function in the linear case The first level set It is expressed as:

[0141]

[0142] Where S is the Riccati equation S+A T S+SA-C T The solution of C = 0, At the same time, the derivative of the Lyapunov function according to the solution of system (13) satisfies the following inequality:

[0143]

[0144] in,

[0145] When the estimated error differential equation ω 0 =1, The approximations at 0 and ∞ are and Using equation (14) to define the homogeneous Lyapunov function structure, two homogeneous Lyapunov functions are constructed, which are defined at 0 and ∞ as and Wγ ,γ>1, and define the following two error sets:

[0146]

[0147]

[0148] Define the homogeneous Lyapunov function as:

[0149]

[0150] In the observer estimation error differential equation (12), take Then the estimated error differential equation (12) can be rewritten as:

[0151]

[0152] The Lyapunov function of the differential equation (18) is constructed in the form of the homogeneous Lyapunov function (17). Specifically:

[0153] Existence 1 ∈(0,ε) makes the following inequality hold:

[0154]

[0155] in, γ∈(1,1+ε 1 ).

[0156] Explain inequality (19), which is equivalent to the following two inequalities:

[0157]

[0158] and The two situations are basically the same, so here we only focus on According to formula (15), for You can get:

[0159]

[0160] definition Then according to formula (14), we can get

[0161] Where ξ=[ξ 1 ξ 2 ] T , when When , on any compact set, the function Converges uniformly to Existence 1 ∈(0,ε), for λ∈(0,1], such that:

[0162]

[0163] Finally, we get and have:

[0164]

[0165] Secondly, there is M 1 >0 makes the following inequality hold:

[0166]

[0167] in, γ∈(1,1+ε 1 ).

[0168] Explaining inequality (25), equation (25) can be equivalent to the following two inequalities:

[0169]

[0170] and The two situations are basically the same, so here we only focus on Discussion of the situation; definition According to formula (14), we can get:

[0171]

[0172] Using Schwartz inequality, we can get:

[0173]

[0174] Among them, h max is the maximum value of h, S i,j Represents the element in the i-th row and j-th column of the matrix S.

[0175] Combining equations (27) and (28), we can obtain:

[0176]

[0177] in,

[0178] Existence M 2 >0 makes the following inequality hold:

[0179]

[0180] in, γ∈(1,1+ε 1 );

[0181] Explaining inequality (30), equation (30) can be equivalent to the following two inequalities:

[0182]

[0183] and The two situations are basically the same, so here we only focus on Discussion of the situation; definition According to formula (14), we can get

[0184]

[0185] Using Schwartz inequality, we can get:

[0186]

[0187] in, for The maximum value of

[0188] Combining equation (32) and equation (33), we get:

[0189]

[0190] in,

[0191] Finally, based on the above Lyapunov function for differential equation (18) The derivative analysis shows that there exists ε 1 >0, for all γ∈(1,1+ε 1 ),ω 0 ≥1, then:

[0192]

[0193] When h = 0, inequality (35) is rewritten as:

[0194]

[0195] According to inequality (36), we can get: hour, Can be in fixed time τ 1 =4 / ω 0 (γ-1) converges to At a fixed time converges to the equilibrium point. Therefore, It is possible to calculate the initial estimation error in a fixed time τ 1 +τ 2 Converges to the equilibrium point.

[0196] When h≠0, there exist ζ, τ 3 , Γ and It does not matter, for all t ≥ τ 3 have:

[0197]

[0198] therefore, It is possible to calculate the initial estimation error in a fixed time τ 3 Converges to a small neighborhood of the equilibrium point.

[0199] In summary, Can follow Converges to an equilibrium point or a small neighborhood of an equilibrium point in a fixed time independent of the initial estimate error, given by Can follow Converges to an equilibrium point or a small neighborhood of an equilibrium point in fixed time independent of the initial estimate error.

[0200] S3: Outputting an error feedback control rate according to the extended state observer.

[0201] See also Figure 2 , is a structural diagram of an auto-disturbance rejection control method based on a quasi-resonant fixed-time dilated state observer according to Example 1 of the present application;

[0202] Specifically, the following steps are included: define the d(q) axis reference current of the permanent magnet synchronous motor as Then the d(q) axis current tracking error is The error expression using error feedback control is:

[0203]

[0204] Among them, k d(q)p is the proportionality coefficient;

[0205] According to the quasi-resonant fixed-time dilated state observer (10), the total disturbance d on the d(q) axis is d(q) It is estimated by the observer as:

[0206]

[0207] Substitute equation (21) into equation (20); the control law is obtained as follows:

[0208]

[0209] See also Figure 3 , which is a simulation model structure diagram of the permanent magnet synchronous motor servo control system of Example 1 of the present application; a detailed description is given below.

[0210] In order to verify the effectiveness of the permanent magnet synchronous motor current control strategy proposed in this application, the performance of the active disturbance rejection control method based on the quasi-resonant fixed time dilation state observer is analyzed in combination with the simulation results; Figure 3 In the simulation model shown, the speed loop adopts PI control, and the current loop adopts the auto-disturbance rejection control method based on the quasi-resonant fixed time dilation state observer proposed in this application.

[0211] First, the mechanical angular velocity reference input of the permanent magnet synchronous motor is given as Use the encoder to obtain the electrical angle θ of the motor e and angular velocity ω m , electrical angle θ e For coordinate transformation, angular velocity ω m Used for speed closed-loop control to obtain q-axis reference current Used for current loop control; then use the current sensor to obtain the motor's phase a, phase b and phase c current i a 、i b and i c , the actual current i of the motor d(q) axis is obtained through coordinate transformation d(q) Used for current control to obtain the current loop control input u d(q) ; Further, the switching signal state vector S of the inverter is obtained by coordinate transformation and SVPWM pulse modulation method abc ; Finally, the inverter is based on the DC bus voltage u DC And the switch signal output three-phase current drives the permanent magnet synchronous motor to run. Figure 3 The simulation model of the permanent magnet synchronous motor servo control system is given, and the comparative simulation results of the traditional linear active disturbance rejection control method and the active disturbance rejection control method based on quasi-resonant fixed time dilated state observer proposed in this application are given.

[0212] See also Figure 4 , which is a diagram showing the estimation results of the linear extended state observer and the quasi-resonant fixed-time extended state observer for step disturbances in Example 1 of the present application; when the current reference is Under the condition of a sudden 2N·m step disturbance at 5 seconds, Figure 4It can be seen that the adjustment time of the quasi-resonant fixed-time expanded state observer to estimate the step disturbance is 0.021 seconds, which is much shorter than the adjustment time of the linear expanded state observer to estimate the step disturbance of 0.037 seconds. This verifies that the quasi-resonant fixed-time expanded state observer proposed in this application has a faster non-periodic disturbance estimation and compensation capability than the traditional linear expanded state observer.

[0213] See also Figure 5 , which is a comparison simulation result diagram of the d-axis current curve of Example 1 of the present application; when the speed reference is When a 2N·m step disturbance is suddenly added at 5 seconds, Figure 5 The d-axis current curves of the traditional linear active disturbance rejection control method and the active disturbance rejection control method based on the quasi-resonant fixed time dilated state observer.

[0214] See also Figure 6 , is a diagram showing the q-axis current curve and Fourier analysis comparison simulation results of Example 1 of the present application; Figure 6 The q-axis current curves and their Fourier analysis results using the traditional linear active disturbance rejection control method and the active disturbance rejection control method based on quasi-resonant fixed time dilation state observer respectively.

[0215] Combination Figure 5 and Figure 6 It can be obtained that the d-axis current fluctuation and q-axis current fluctuation of the auto-disturbance rejection control method based on the quasi-resonant fixed-time extended state observer are 0.58A and 0.24A respectively, which are much smaller than the d-axis current fluctuation and q-axis current fluctuation of 0.88A and 0.33A of the traditional linear auto-disturbance rejection control method; it is verified that the auto-disturbance rejection control method based on the quasi-resonant fixed-time extended state observer can realize high-precision current control of the permanent magnet synchronous motor. In addition, compared Figure 6 The Fourier analysis results of the q-axis current use an anti-disturbance control method based on a quasi-resonant fixed-time dilation state observer to reduce the total harmonic disturbance (THD) of the q-axis current by 1.84%, verifying that the quasi-resonant fixed-time dilation state observer can effectively estimate and compensate for periodic disturbances.

[0216] See also Figure 7 , is a comparison simulation result diagram of the A phase current curve of Example 1 of the present application; Figure 7 The a-phase current curves of the traditional linear auto-disturbance rejection control method and the auto-disturbance rejection control method based on the quasi-resonant fixed time dilated state observer are respectively obtained; it is further obtained that the auto-disturbance rejection control method based on the quasi-resonant fixed time dilated state observer reduces the total harmonic disturbance (THD) of the a-phase current by 7.28%, thereby improving the stability of the permanent magnet synchronous motor system.

[0217] In summary, the present application establishes the permanent magnet synchronous motor current equation and the extended state observer through Example 1, analyzes the extended state observer, and finally designs the error feedback control rate according to the extended state observer, thereby improving the convergence speed of the observer and effectively suppressing the periodic disturbance; the extended state observer utilizes the quasi-resonant control theory, and by introducing the quasi-resonant correction term, it can effectively estimate and compensate for the periodic disturbances such as the flux harmonics and voltage harmonics existing in the current loop, and converges within a fixed time independent of the initial state of the observer, thereby effectively improving the dynamic performance and steady-state performance of the permanent magnet synchronous motor system.

[0218] Example 2

[0219] See also Figure 8 , is a structural diagram of a permanent magnet synchronous motor current control system according to Embodiment 2 of the present application; specifically comprising:

[0220] Establish module: establish permanent magnet synchronous motor current equation;

[0221] Calculation module: establishing an extended state observer according to the permanent magnet synchronous motor current equation;

[0222] Output module: outputs error feedback control rate according to the extended state observer.

[0223] In summary, the present application obtains the permanent magnet synchronous motor current equation and the extended state observer respectively through the establishment module and the calculation module of Example 2, and designs the error feedback control rate according to the extended state observer, which can effectively estimate and compensate for periodic disturbances such as flux harmonics and voltage harmonics existing in the current loop; at the same time, the extended state observer uses the fixed time stability theory, and can estimate and compensate for non-periodic disturbances such as cross-coupling disturbances, parameter perturbations and external disturbances existing in the current loop within a fixed time independent of the initial state of the observer; a permanent magnet synchronous motor current control system proposed in the present application can estimate and compensate for non-periodic disturbances more quickly, and can also estimate and compensate for periodic disturbances efficiently, further improving the robustness of permanent magnet synchronous motor current control.

[0224] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, device, article or method including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, device, article or method. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the presence of other identical elements in the process, device, article or method including the element.

[0225] The above description is only a preferred embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

[0226] Although the embodiments of the present application have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the appended claims and their equivalents.

[0227] Of course, the present application may have many other implementations. Based on the present implementation, other implementations obtained by ordinary technicians in this field without any creative work are all within the scope of protection of the present application.

Claims

1. A permanent magnet synchronous motor current control method, characterized in that: include: Establish the current equation of permanent magnet synchronous motor; Establishing an extended state observer according to the permanent magnet synchronous motor current equation; Specifically, it includes: based on the fixed time control theory and the quasi-resonant control theory, a quasi-resonant fixed time dilation state observer is designed, and the design of the quasi-resonant fixed time dilation state observer is as follows: in, is the control gain, L s0 is the nominal value of the dq axis stator inductance; x1 = i d(q) is the stator current of dq axis, is the state estimate of x1, is the state estimate of x2, x2=d d(q) is the total disturbance of the dq axis; is the estimated value of the state vector x, θ i =iθ-(i-1)(i=1,2), θ∈(1 / 2,1),γ i =iγ-(i-1)(i=1,2), γ∈(1,+∞); is the estimated periodic disturbance, ω c , k r and ω h are the cutoff frequency, resonant gain and resonant frequency of the quasi-resonant controller respectively, ω0≥1 is a coefficient related to the observer bandwidth, where the observer gain vector K=[k1 k2] T =[2 1] T , sgn * (·)=|·| * sign(·), sign(·) is the sign function; According to the output error feedback control rate of the extended state observer, specifically including: The dq axis reference current of the permanent magnet synchronous motor is defined as Then the dq axis current tracking error is where i d(q) is the stator current of the dq axis. Using error feedback control, the dq axis current tracking error is expressed as: Among them, k d(q)p is the proportionality coefficient, is the control gain, L s0 is the nominal value of the dq-axis stator inductance; According to the quasi-resonant fixed-time dilated state observer (10), the total disturbance d of the dq axis is d(q) It is estimated by the observer as: Substitute equation (21) into equation (20); the control law is obtained as follows:

2. A permanent magnet synchronous motor current control method according to claim 1, characterized in that: In the step of establishing the permanent magnet synchronous motor current equation, the dq axis current equation of the permanent magnet synchronous motor in the synchronous rotating coordinate system is: Among them, i d and i q are the stator currents of the d-axis and q-axis respectively, u d and u q are the stator voltages of the d-axis and q-axis, R s is the stator resistance, L d and L q are the stator inductances of the d-axis and q-axis, ω e is the electrical angular velocity, ψ f is the rotor flux; According to the non-periodic disturbance, the dq axis current equation of the permanent magnet synchronous motor can be rewritten as: Among them, d dap and d qap are the non-periodic perturbations of the d-axis and q-axis respectively, d dco and d qco are the cross-coupled perturbations of the d-axis and q-axis, d dpa and d qpa are the disturbances caused by parameter perturbations on the d-axis and q-axis, respectively. dex and d qex are the external uncertain disturbances on the d-axis and q-axis respectively, L d0 =L q0 =L s0 is the nominal value of the d-axis and q-axis stator inductance, R s0 is the nominal value of the stator resistance, ψ f0 is the nominal value of the rotor flux, where ΔL d(q) =L d(q) -L d(q)0 , ΔR s =R s -R s0 , Δψ f =ψ f -ψ f0 .

3. A permanent magnet synchronous motor current control method according to claim 2, characterized in that: The periodic disturbance of the permanent magnet synchronous motor current includes flux harmonics and inverter nonlinearity; The flux harmonics of the dq axis of the permanent magnet synchronous motor are expressed as: Among them, ψ dh and ψ qh are the magnetic flux harmonics of the d-axis and q-axis, ψ d6n and ψ q6n are the amplitudes of the 6nth harmonic of the d-axis and q-axis respectively; The voltage harmonics of the dq axis of the permanent magnet synchronous motor are expressed as Among them, u dh and u qh are the voltage harmonics of the d-axis and q-axis, τ dead and τ s They are dead time and sampling time, U dc is the DC bus voltage; According to the flux harmonics and the voltage harmonics, the periodic disturbance of the dq axis of the permanent magnet synchronous motor is expressed as: Among them, d dp and d qp are the periodic perturbations of the d-axis and q-axis respectively; According to equations (2) and (7), the permanent magnet synchronous motor current equation is rewritten as: Among them, d d =d dap +d dp and d q =d qap +d qp are the total disturbances of the d-axis and q-axis respectively, To control the gain.

4. A permanent magnet synchronous motor current control method according to claim 1, characterized in that: The step of establishing an extended state observer according to the permanent magnet synchronous motor current equation specifically includes the following steps: Establishing an extended state model of the permanent magnet synchronous motor dq axis current equation according to the permanent magnet synchronous motor current equation; Based on the fixed-time control theory and quasi-resonant control theory, a quasi-resonant fixed-time dilation state observer is designed. The fixed-time convergence characteristics are analyzed by the quasi-resonant fixed-time dilated state observer.

5. A permanent magnet synchronous motor current control method according to claim 4, characterized in that: The step of establishing an extended state model of the permanent magnet synchronous motor dq axis current equation according to the permanent magnet synchronous motor current equation specifically includes the following steps: According to the permanent magnet synchronous motor current equation, take x1=i d(q) , x2=d d(q) , u=u d(q) , where i d(q) is the stator current of dq axis, d d(q) is the total disturbance of the dq axis, u d(q) is the stator voltage of the dq axis; then the extended state observation model of the dq axis current equation of the permanent magnet synchronous motor is expressed as: in, x2=d d(q) is the total disturbance of the dq axis, is the control gain, L s0 is the nominal value of the dq-axis stator inductance.

6. A permanent magnet synchronous motor current control method according to claim 4, characterized in that: The step of analyzing the fixed-time convergence characteristic by the quasi-resonant fixed-time dilation state observer specifically includes the following steps: The estimated error differential equation of the observer obtained according to the extended state observer and the quasi-resonant fixed-time extended state observer is: in, is the state estimation error, x i (i=1, 2) represents x1 and x2, x1=i d(q) is the stator current of the dq axis, x2=d d(q) is the total disturbance of the dq axis, represent and is the state estimate of x1, is the state estimate of x2; Reason The vector field is composed of ω0≥1, which is the coefficient related to the observer bandwidth, k i (i=1, 2) represents k1 and k2, k1 and k2 are positive constants, θ i (i=1, 2) represents θ1 and θ2, θ i =iθ-(i-1), θ∈(1 / 2,1) is a constant, γ i (i=1, 2) represents γ1 and γ2, γ i =iγ-(i-1), γ∈(1,+∞) is a constant; is the estimated periodic disturbance, K = [k1 k2] T =[2 1] T , E = [1 0] T ; The double limit homogeneous correction term is constructed by the quasi-resonant fixed-time dilated state observer Therefore, when the periodic disturbance h of the q-axis is 0, the estimated error differential equation (12) is related to the following formula in the 0 and ∞ limits: in, Reason The vector field, α i =iα-(i-1)(i=1,2), α∈(1-1 / 2,+∞); Formula (13) satisfies the weight vector r(α) = [r1 r2] T , r i =(i-1)α-(i-2)(i=1,2) The homogeneity is α-1; Therefore, there exists ε>0, and for all α∈(1-ε,1+ε), the system (13) is asymptotically stable.

7. A permanent magnet synchronous motor current control method according to claim 6, characterized in that: The system (13) has a homogeneous Lyapunov function that satisfies the homogeneity of the weight vector r(α) being 2, and its first order is a quadratic Lyapunov function in the linear case The first level set It is expressed as: Where S is the Riccati equation S+A T S+SA-C T The solution of C = 0, λ>0, At the same time, the derivative of the Lyapunov function according to formula (13) satisfies the following inequality: in, When ω0=1 in the estimation error differential equation, The approximations at 0 and ∞ are and where K = [k1 k2] T =[2 1] T ; Using equation (14) to define the homogeneous Lyapunov function structure, two homogeneous Lyapunov functions are constructed, which are defined as W at 0 and ∞ respectively. θ , θ<1 and W γ , γ>1, and define the following two error sets: Define the homogeneous Lyapunov function as: In the observer estimation error differential equation (12), take Then the estimated error differential equation (12) can be rewritten as: The Lyapunov function of the differential equation (18) is constructed in the form of the homogeneous Lyapunov function (17). Specifically: There exists ε1∈(0,ε) such that the following inequality holds: in, θ∈(1-ε1,1), γ∈(1,1+ε1).

8. A control system for a permanent magnet synchronous motor current control method according to any one of claims 1 to 7, characterized in that: include: Establish module: establish permanent magnet synchronous motor current equation; Calculation module: establishing an extended state observer according to the permanent magnet synchronous motor current equation; Output module: outputs error feedback control rate according to the extended state observer.

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