A method for suppressing current harmonics of permanent magnet synchronous motor

Abstract

The present invention discloses a method for suppressing harmonics of permanent magnet synchronous motor current, which comprises: establishing a mathematical model of permanent magnet synchronous motor in synchronous rotating coordinate system d-q; setting a reduced-order vector resonance controller, and connecting the reduced-order vector resonance controller in parallel to a current loop; setting a controller based on reduced-order vector resonance and generalized anti-disturbance control, wherein the reduced-order vector resonance and generalized anti-disturbance control are connected in parallel and serve as a current loop controller. The method for suppressing harmonics of permanent magnet synchronous motor current disclosed by the present invention reduces the harmonic components and can well suppress the harmonics of permanent magnet synchronous motor current.

Description

Technical Field

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

[0002] Permanent magnet synchronous motors are widely used in servo systems because of their high efficiency, high power density, large torque-to-inertia ratio, low noise, and easy maintenance, especially in areas that require high motor performance and control accuracy, such as optoelectronic stabilization platforms, precision CNC machine tools, new energy electric vehicles and other equipment industries. At present, the harmonic impact is mainly reduced by improving the motor structure and adopting advanced control strategies, but the first method increases the manufacturing cost of the motor. Therefore, many scholars have proposed some algorithms such as repetitive control to suppress current harmonics. However, these algorithms all have obvious shortcomings, such as repetitive control contains delay links, slow adjustment speed and other shortcomings. Therefore, it is necessary to study and design a new current harmonic suppression method to improve the control accuracy of motor current. Summary of the invention

[0003] The present invention aims to overcome the defects of the prior art, and the present invention adopts the following technical solutions:

[0004] The invention provides a method for suppressing current harmonics of a permanent magnet synchronous motor.

[0005] A method for suppressing current harmonics of a permanent magnet synchronous motor, wherein the permanent magnet synchronous motor comprises a current loop, and the method for suppressing current harmonics of the permanent magnet synchronous motor comprises:

[0006] Establish the mathematical model of permanent magnet synchronous motor in synchronous rotating coordinate system dq;

[0007] Setting a reduced-order vector resonant controller, connecting the reduced-order vector resonant controller in parallel to the current loop, wherein the reduced-order vector resonant controller tracks a sinusoidal signal of a specified resonant frequency and suppresses current harmonics by compensation;

[0008] A controller based on reduced-order vector resonance and generalized auto-disturbance rejection is set up, wherein the reduced-order vector resonance and generalized auto-disturbance rejection controller are connected in parallel and serve as a current loop controller, and the reduced-order vector resonance and generalized auto-disturbance rejection controller are used to eliminate AC periodic disturbances and DC non-periodic disturbances.

[0009] In some embodiments, the stator voltage equation of the permanent magnet synchronous motor can be expressed as follows:

[0010]

[0011] In the formula, ψ d =ψ f +L d i dc and ψq =L q i qc Represent the d-axis and q-axis components of the stator flux respectively;

[0012] i dc and u dv Represent the d-axis stator current and voltage respectively, i qc and u qv Represent the q-axis stator current and voltage respectively, L d and L q Respectively represent the d-axis and q-axis inductance of the stator winding, R1 represents the stator one-phase resistance, n p is the number of motor pole pairs, ω m is the mechanical angular velocity of the motor, ψ f is the permanent magnet flux.

[0013] In some embodiments, the permanent magnet synchronous motor is a surface mounted permanent magnet synchronous motor.

[0014] In some embodiments, the L d =L q =L s .

[0015] In some embodiments, the reduced-order vector resonance controller is expressed as follows:

[0016]

[0017] Among them, k pr and k ir are the proportional and resonant coefficients, j is the imaginary unit, s represents the Laplace operator, ω h represents the resonant frequency, ω c Indicates the cutoff frequency.

[0018] In some embodiments, the reduced-order vector resonance controller is used to suppress the 5th and 7th harmonics in the three-phase current of the permanent magnet synchronous motor.

[0019] In some embodiments, the DC non-periodic disturbance includes a parameter perturbation.

[0020] In some embodiments, the reduced-order vector resonance and generalized active disturbance rejection controller are based on connecting the reduced-order resonance controller and the generalized active disturbance rejection controller in parallel.

[0021] In some embodiments, the disturbance compensation of the generalized control law based on reduced-order vector resonance and generalized active disturbance rejection controller includes: compensation for known coupled disturbances, compensation for reference current change disturbances based mainly on step disturbance compensation, compensation for DC disturbances, and compensation for AC harmonic disturbances.

[0022] In some embodiments, the permanent magnet synchronous motor further includes a speed loop, and the speed loop adopts proportional integral control.

[0023] Technical effect of the present invention: The permanent magnet synchronous motor current harmonic suppression method disclosed by the present invention establishes a mathematical model of the permanent magnet synchronous motor in a synchronous rotating coordinate system dq; sets a reduced-order vector resonance controller, and connects the reduced-order vector resonance controller in parallel to the current loop to compensate and suppress current harmonics; sets a reduced-order vector resonance and generalized anti-disturbance controller, and the reduced-order vector resonance and generalized anti-disturbance controller are connected in parallel and used as current loop controllers to eliminate AC periodic disturbances and DC non-periodic disturbances. The permanent magnet synchronous motor current harmonic suppression method reduces the harmonic components, can well suppress the harmonics of the permanent magnet synchronous motor current, and ensures the control accuracy and quality of the current. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 A control block diagram of a permanent magnet synchronous motor based on reduced-order vector resonance and generalized active disturbance rejection control according to an embodiment of the present invention;

[0026] Figure 2 A block diagram of a current closed-loop control principle based on reduced-order vector resonance according to an embodiment of the present invention;

[0027] Figure 3 A block diagram of a reduced-order vector resonance structure according to an embodiment of the present invention;

[0028] Figure 4 is a Bode diagram of a reduced-order vector resonant controller according to an embodiment of the present invention; wherein ω in FIG. (a) c Fixed, k r Changes, where k in Figure (b) r Fixed, ω c change;

[0029] Figure 5 is a Bode diagram of the current loop closed-loop transfer function under the action of only the reduced-order vector resonant controller according to an embodiment of the present invention; wherein ω in FIG. (a) c Fixed, k r Change, k in Figure (b) r Fixed, ω c change;

[0030] Figure 6 is a three-dimensional graph of the steady-state maximum disturbance estimation error of the generalized active disturbance rejection controller according to one embodiment of the present invention;

[0031] Figure 7 Bode diagrams of disturbance estimation and disturbance estimation error transfer functions under different orders of expansion of a generalized active disturbance rejection controller according to an embodiment of the present invention;

[0032] Figure 8 A method for suppressing current harmonics of a permanent magnet synchronous motor according to an embodiment of the present invention is based on a reduced-order vector resonance and generalized active disturbance rejection control structure diagram;

[0033] Fig. 9 The three-phase current waveforms and fast Fourier transform results of different algorithms under the conditions of a rotation speed of 100 rpm and a load of 5 N·m according to an embodiment of the present invention;

[0034] Fig.10 q-axis current waveforms and fast Fourier transform results of different algorithms under the conditions of a rotation speed of 100 rpm and a load of 5 N·m according to an embodiment of the present invention;

[0035] Fig.11 Schematic diagram of a method for suppressing current harmonics in a permanent magnet synchronous motor according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0037] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0038] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.

[0039] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0040] As used in the specification and appended claims of this application, the term "if" can be interpreted as "when" or "uponce" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "uponce it is determined" or "in response to determining" or "uponce [described condition or event] is detected" or "in response to detecting [described condition or event]", depending on the context.

[0041] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0042] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0043] The present invention will be described in detail below in conjunction with the various embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional changes made by a person skilled in the art based on these embodiments are all within the scope of protection of the present invention.

[0044] At present, permanent magnet synchronous motors mainly reduce the influence of harmonics by improving the motor structure and adopting advanced control strategies, but the first method increases the manufacturing cost of the motor, so many scholars have proposed to use methods such as repetitive control, resonant control, iterative learning control, etc. to suppress current harmonics. However, these algorithms all have obvious shortcomings, such as repetitive control including delay links, slow adjustment speed, poor iterative learning robustness, slow convergence speed and other shortcomings. The inventors of the embodiments of the present invention found that: in the framework of space vector control, whether it is a three-loop control including a position loop or a double-loop control including a speed loop, the current loop is the innermost loop of the permanent magnet synchronous motor, so the current loop is the key to achieving high-performance and high-precision control of the permanent magnet synchronous motor. However, there are various disturbances in the current loop, including internal parameter perturbations, external interferences mainly based on reference current step changes, and current harmonics caused by inverter nonlinearity and motor cogging effects, among which low-order harmonics are the main ones in the three-phase current. Therefore, it is necessary to study and design a current harmonic suppression strategy to improve the control accuracy of the motor current by overcoming the influence of internal and external disturbances, especially current harmonics, on the current.

[0045] The embodiment of the present invention provides a method for suppressing current harmonics of a permanent magnet synchronous motor. Fig.11 shown.

[0046] refer to Fig.11 As shown, an embodiment of the present invention provides a method for suppressing current harmonics of a permanent magnet synchronous motor, wherein the permanent magnet synchronous motor includes a current loop, and the method for suppressing current harmonics of the permanent magnet synchronous motor includes:

[0047] S1, establish a mathematical model of the permanent magnet synchronous motor in the synchronous rotating coordinate system dq;

[0048] S2, setting a reduced-order vector resonant controller, connecting the reduced-order vector resonant controller in parallel to the current loop, wherein the reduced-order vector resonant controller tracks a sinusoidal signal of a specified resonant frequency and suppresses current harmonics by compensation;

[0049] S3, setting a controller based on reduced-order vector resonance and generalized auto-disturbance rejection, connecting the reduced-order vector resonance and generalized auto-disturbance rejection controller in parallel and using them as a current loop controller, wherein the controller based on reduced-order vector resonance and generalized auto-disturbance rejection controller is used to eliminate AC periodic disturbances and DC non-periodic disturbances.

[0050] In the framework of space vector control, whether it is a three-loop control including a position loop or a dual-loop control including a speed loop, the current loop is the innermost loop. Therefore, in some embodiments, the permanent magnet synchronous motor includes a dual-loop control of a current loop and a speed loop, and in some embodiments, the permanent magnet synchronous motor includes a three-loop control of a current loop, a speed loop and a position loop.

[0051] In some embodiments, the stator voltage equation of the permanent magnet synchronous motor can be expressed as follows:

[0052]

[0053] In the formula, ψ d =ψ f +L d i dc and ψ q =L q i qc Represent the d-axis and q-axis components of the stator flux respectively;

[0054] i dc and u dv Represent the d-axis stator current and voltage respectively, i qc and u qv Represent the q-axis stator current and voltage respectively, L d and L q Respectively represent the d-axis and q-axis inductance of the stator winding, R1 represents the stator one-phase resistance, n p is the number of motor pole pairs, ω m is the mechanical angular velocity of the motor, ψ f is the permanent magnet flux.

[0055] In some embodiments, the permanent magnet synchronous motor is a surface mounted permanent magnet synchronous motor.

[0056] In some embodiments, for a surface-mounted permanent magnet synchronous motor, the AC and DC axis magnetic circuits are substantially symmetrical, so the L d =L q =L s .

[0057] In some embodiments, the reduced-order vector resonance controller is expressed as follows:

[0058]

[0059] Among them, k pr and k ir are the proportional and resonant coefficients, j is the imaginary unit, s represents the Laplace operator, ω h represents the resonant frequency, ω c Indicates the cutoff frequency.

[0060] In some embodiments, the reduced-order vector resonant controller is used to suppress the 5th and 7th harmonics in the three-phase current of the permanent magnet synchronous motor. In order to suppress the 5th and 7th low-order harmonics in the three-phase current of the permanent magnet synchronous motor, a resonant control control strategy is usually adopted. There are various disturbances in the current loop, including internal parameter perturbations, external interferences mainly based on reference current step changes, and current harmonics caused by inverter nonlinearity and motor cogging effects, among which the three-phase current is dominated by low-order harmonics, especially the 5th and 7th harmonics.

[0061] In some embodiments, the DC non-periodic disturbance includes a parameter perturbation.

[0062] In some embodiments, the reduced-order vector resonance and generalized active disturbance rejection controller are based on connecting the reduced-order resonance controller and the generalized active disturbance rejection controller in parallel.

[0063] In some embodiments, the disturbance compensation of the generalized control law based on reduced-order vector resonance and generalized active disturbance rejection controller includes: compensation for known coupled disturbances, compensation for reference current change disturbances based mainly on step disturbance compensation, compensation for DC disturbances, and compensation for AC harmonic disturbances.

[0064] In some embodiments, the permanent magnet synchronous motor further includes a speed loop, and the speed loop adopts proportional integral control.

[0065] The method for suppressing the harmonics of the permanent magnet synchronous motor current disclosed in the embodiment of the present invention establishes a mathematical model of the permanent magnet synchronous motor in a synchronous rotating coordinate system dq; sets a reduced-order vector resonance controller, and connects the reduced-order vector resonance controller in parallel to the current loop to compensate and suppress the current harmonics; and sets a controller based on reduced-order vector resonance and generalized anti-disturbance control, which are connected in parallel and serve as current loop controllers to eliminate AC periodic disturbances and DC non-periodic disturbances. The method for suppressing the harmonics of the permanent magnet synchronous motor current reduces the harmonic components, can well suppress the harmonics of the permanent magnet synchronous motor current, and ensure the control accuracy and quality of the current. Compared with the current harmonic suppression method of the prior art: (1) by simultaneously connecting reduced-order vector resonance controllers with different resonant frequencies in parallel, unity gain and zero phase shift can be achieved to suppress the current harmonics of different resonant frequencies. (2) Under the conditions of the same observation bandwidth and control gain, the advantage of generalized anti-disturbance control is that it can estimate the disturbance faster and reduce the steady-state disturbance estimation error. Therefore, based on the reduced-order vector resonance and generalized auto-disturbance rejection controller, the harmonic interference can be suppressed, and the suppression capability of DC non-periodic disturbance and AC periodic disturbance is improved.

[0066] The following is further described in detail through specific examples.

[0067] refer to Figure 1 As shown, Figure 1 This is a block diagram of the dual closed-loop servo system of a permanent magnet synchronous motor under space vector control. The permanent magnet synchronous motor includes a current loop and a speed loop, a PI controller, a space vector SVPWM, a three-phase inverter, a permanent magnet synchronous motor, a Clark transformation, and a Park transformation; a reduced-order vector resonant controller is connected in parallel to the current loop, and the reduced-order vector resonant controller tracks the sinusoidal signal of the specified resonant frequency and suppresses the current harmonics by compensation; the reduced-order vector resonance and the generalized anti-disturbance control controller are connected in parallel and serve as the current loop controller.

[0068] In this embodiment, the speed loop adopts the traditional proportional integral control, and the proposed reduced-order vector resonance and generalized anti-disturbance control act on the current loop. The proposed controller can not only compensate for non-periodic DC interference, but also suppress non-periodic AC harmonics.

[0069] The present invention is specifically implemented through the following technical solutions:

[0070] First, the mathematical model of the permanent magnet synchronous motor in the synchronous rotating coordinate system dq is established. Ignoring the motor core saturation, eddy current and hysteresis loss, its stator voltage equation can be expressed as follows:

[0071]

[0072] In the formula, ψ d =ψ f +L d i dc and ψ q =L q i qc Represent the d-axis and q-axis components of the stator flux respectively. dc and u dv Represent the d-axis stator current and voltage respectively, i qc and u pv Represent the q-axis stator current and voltage respectively, L d and L q Respectively represent the d-axis and q-axis inductance of the stator winding, R1 represents the stator one-phase resistance, n p is the number of motor pole pairs, ω m is the mechanical angular velocity of the motor, ψ f is the permanent magnet flux. For surface-mounted permanent magnet synchronous motors, the AC and DC axis magnetic circuits are basically symmetrical, so L d =L q =L s .

[0073] Considering the internal parameter perturbation of the motor and external interference such as current harmonics, in order to facilitate the design of subsequent steps, equation (1) can be rewritten as follows:

[0074]

[0075] Where b0 = 1 / L s0 ,f dk and f qk Respectively represent the known coupling interference, f d and f q represent the unknown total disturbances of the d-axis and q-axis, including the internal disturbance f caused by parameter perturbation di 、f qi and external disturbances mainly composed of harmonics and current step changes de 、f qe , that is, f d =f di +f de , f q =f qi +f qe Therefore, f dk 、f qk and f di 、f qi The expressions are as follows:

[0076]

[0077]

[0078] In the formula, ΔL s =L s -L s0 , ΔR1=R1-R 10 , Δψ f =ψ f -ψ f0 , L s0 , R 10 and ψ f0 is the corresponding nominal value.

[0079] Secondly, a reduced-order vector resonant controller is set. In order to suppress the 5th and 7th low-order harmonics in the three-phase current of the permanent magnet synchronous motor, a resonant control strategy is usually adopted. Therefore, the present invention proposes a reduced-order vector resonant controller, which is expressed as follows:

[0080]

[0081] Among them, k pr and k ir are the proportional and resonant coefficients, j is the imaginary unit, s represents the Laplace operator, ω h represents the resonant frequency, ω c In order to achieve the pole cancellation of the equivalent model of the zero-point permanent magnet synchronous motor of the reduced-order vector resonant controller, let k pr =k r ωc L s0 , k ir =k r ω c R 10 , where k r is the resonant gain, such as Figure 2 As shown, it is a block diagram of d-axis and q-axis current closed-loop control under reduced-order vector resonance.

[0082] In order to realize the imaginary number j in the digital controller, the present invention makes full use of the orthogonality of the d-axis and the q-axis, that is, u dv =ju qv ,u qv =-ju dr Therefore, according to the transformation of formula (5), the d-axis and q-axis outputs u of the reduced-order vector resonance controller are obtained: dr 、u qr With the current deviation input e dc 、e qc The relationship between them is as follows:

[0083]

[0084] Figure 3 This is the control block diagram of the reduced-order vector controller proposed by the present invention drawn according to formula (6).

[0085] To further illustrate the influence of various parameters in the controller on the reduced-order vector controller, according to the actual motor parameters, L s0 =0.0085H, R 10 =0.675Ω. Therefore, the Bode plot of the reduced-order vector resonant controller is as follows: Figure 4 As shown. Figure 4 As can be seen in (a), when w c When k is fixed, r The larger the k is, the greater the resonant gain of the reduced-order vector resonant controller is, while the resonant bandwidth remains basically unchanged. r It affects the resonant gain but not the resonant bandwidth. Figure 4 As shown in (b), when k r When w is fixed, c The larger the w is, the larger the resonant bandwidth of the reduced-order vector resonant controller is, and the better the robustness to the change of the motor resonant frequency is, while the resonant gain remains basically unchanged. c It affects the resonant bandwidth but not the resonant gain.

[0086] In an ideal situation, L s =L s0 , R1=R 10 .according to Figure 2 , find the actual output id(q)c Ratio reference input The closed-loop transfer function is as follows:

[0087]

[0088] According to formula (7), the Bode plot of the current closed-loop transfer function under the action of the reduced-order vector resonant controller is drawn as follows: Figure 5 As shown, it can be seen that when the parameter k r and w c When the resonant frequency changes, the amplitude and phase at the specified resonant frequency will not change, achieving unity gain and zero phase shift. In other words, the reduced-order vector resonant controller can make i d(q)c Real-time tracking There is basically no static error. Therefore, the proposed reduced-order vector resonant controller can track the sinusoidal signal of the specified resonant frequency and achieve the purpose of suppressing current harmonics through compensation.

[0089] Third, a controller based on reduced-order vector resonance and generalized auto-disturbance rejection is set. In order to eliminate non-periodic disturbances of DC such as parameter perturbation and further suppress periodic disturbances of current harmonics, the present invention designs a generalized auto-disturbance rejection controller. Because the design methods of the d-axis and q-axis are similar, only the design method of the q-axis is given here. According to formula (2), adding n additional states to the original model equation can obtain the following equation:

[0090]

[0091] Among them, the state matrix Input Matrix Unknown interference matrix Known Interference Matrix In addition, the system matrix is ​​expressed as f q The n-1 derivative of .

[0092] Therefore, the generalized extended state observer is obtained as follows:

[0093]

[0094] In the formula, the matrix represents the estimate of the matrix x, e q1 =z1-x1,

[0095] Then the error equation of the observer can be expressed as:

[0096]

[0097] In the above formula, eq =zx, C represents the output matrix, C = [1 0 0 … 0] n+1 According to the general observer bandwidth tuning strategy, the selection is as follows:

[0098]

[0099] Where ω0 represents the bandwidth of the generalized extended state observer, and m = 1, 2, ..., n + 1. Therefore, the eigenvalues ​​of the matrix (A-LC) are all negative real numbers and are all assigned to -ω0. Therefore, the matrix (A-LC) is a Hurwitz matrix. At this time, if Then the observation error e q is asymptotically stable; if And is bounded, then the observation error e q is bounded input and bounded output stable. Therefore, if f q is a constant disturbance, whose first-order derivative is 0, then the second-order extended state observer can track the constant disturbance without static error in the steady state. Similarly, if f q is a ramp disturbance, whose second-order derivative is 0, then the observation error of the third-order extended state observer is That is, the ramp signal can be tracked without static error. However, for harmonic disturbance, assuming f q =H sin(ω h t), its n-th order derivative is not zero and is bounded, so no matter how many orders the observer is expanded to, the observation error e q All of them are bounded input and bounded output stable. According to the McLaughlin formula, the Taylor expansion of harmonic interference is as follows:

[0100]

[0101] It can be seen from the above formula that the more the order of expansion of the expanded state observer is, the better it can track the Taylor expansion term, and the lower the maximum limit of the observation error.

[0102] To further illustrate the performance of the generalized extended state observer, the following analysis will be conducted from the frequency domain perspective. From (8) and (9), it can be obtained that the transfer function z2 / f of the disturbance estimation of the second-order, third-order, and fourth-order extended state observers is q as follows:

[0103]

[0104] At the same time, the interference estimation error transfer function can also be obtained:

[0105]

[0106] In f q =H sin(ω ht), the general form of the steady-state maximum disturbance estimation error under different expansion orders can be obtained according to formula (14) as follows:

[0107]

[0108] Among them, e q2 =z2-x2, n is the order of the extended state observer and n≥2, g=ω h / ω0 represents the ratio of the harmonic interference frequency to the observer bandwidth, and g<1 is generally selected. Therefore, the harmonic amplitude H=1 is taken, and the three-dimensional graph of the steady-state maximum interference estimation error is drawn according to formula (15) as shown in Figure 6 As shown in the figure, it can be seen that |e q2 | max It decreases as the order n increases and decreases as g decreases. In other words, |e q2 | max Inversely proportional to the order n and the harmonic frequency ω h is proportional to and inversely proportional to the observer bandwidth ω0. Therefore, if at the harmonic frequency ω h In the case of fixed q2 | max To reduce, it needs to be done by increasing the order and the observer bandwidth, but considering the influence of measurement noise, n and ω0 cannot be too large. According to equations (13) and (14), under the condition of fixed observer bandwidth, the interference estimation and interference estimation error transfer functions of the extended state observer at different orders are as follows: Figure 7 As shown, it can be seen that with the increase of the expansion order, its anti-interference ability is enhanced and the noise suppression ability is weakened. Therefore, it is not advisable to expand too high an order. Here, a three-order generalized extended state observer is selected. According to formula (9), its expression is

[0109]

[0110] In the formula, z1, z2, z3 are the current i qc , unknown total disturbance f q and the first-order derivative of the unknown total disturbance By estimating the value of , the reduced-order resonant controller is connected in parallel with the generalized ADRC controller, and the generalized control law is obtained as

[0111]

[0112] In the formula, represents the reference current of the q axis, k pq represents the control gain of the q-axis. Similarly, the d-axis related expression can be obtained according to equations (16) and (17). According to equation (17), the disturbance compensation of the generalized control law includes four parts. First, fqk For compensation of known coupled disturbances, and secondly It is used for reference current change disturbance compensation mainly based on step disturbance compensation. The third part z2 is the disturbance observed by the generalized extended state observer, which can mainly realize the compensation of DC interference. The fourth part b0u qr To achieve compensation for AC harmonic disturbance. z2 and b0u qr represents the external disturbance of the system, i.e. Substituting equation (17) back into equation (2), the q-axis system can be simplified to a single integrator system, that is:

[0113]

[0114] From the above, a controller based on reduced-order vector resonance and generalized active disturbance rejection is obtained through equations (6), (16) and (17), and its structure is shown in the figure: Figure 8 As shown, ω f Represents the fundamental frequency, N + represents a positive natural number. Figure 8 It can be seen that based on the reduced-order vector resonance and generalized ADRC, the estimation term of the disturbance derivative, i.e. z3, is added to the traditional ADRC, and a new type of reduced-order vector resonance controller is connected in parallel.

[0115] Compared with the traditional current harmonic suppression method, (1) by connecting reduced-order vector resonant controllers with different resonant frequencies in parallel, unity gain and zero phase shift can be achieved to suppress current harmonics with different resonant frequencies. (2) Under the conditions of the same observation bandwidth and control gain, the advantage of generalized auto-disturbance rejection control is that it can estimate the disturbance faster and reduce the steady-state disturbance estimation error. Therefore, based on reduced-order vector resonance and generalized auto-disturbance rejection controller, harmonic interference can be suppressed, and the suppression ability of DC non-periodic disturbance and AC periodic disturbance can be improved.

[0116] In order to verify the effectiveness of the current harmonic suppression method proposed in the present invention, the traditional PI algorithm and the algorithm proposed in the present invention are used to simulate under the same load and harmonic injection conditions. qc Compare and analyze the three-phase current, perform fast Fourier transform and calculate the total harmonic distortion. The simulation structure is as follows Fig. 9 and Fig.10 As shown, it can be seen that the method based on reduced-order vector resonance and generalized auto-disturbance rejection can relatively reduce the harmonic components, can well suppress the harmonics of the permanent magnet synchronous motor current, and ensure the control accuracy and quality of the current.

[0117] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be implemented using hardware, a software module executed by a processor, or a combination of the two. The software module may be placed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0118] In the description of the present invention, it should be understood that the symbols such as parameters, variables and program names mentioned in the embodiments of the present invention can be replaced by any other codes that will not cause confusion.

[0119] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0120] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features.

[0121] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0122] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0123] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0124] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

[0125] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for suppressing current harmonics of a permanent magnet synchronous motor, wherein the permanent magnet synchronous motor comprises a current loop, It is characterized in that The permanent magnet synchronous motor current harmonic suppression method comprises: Establish the mathematical model of permanent magnet synchronous motor in synchronous rotating coordinate system dq; Setting a reduced-order vector resonant controller, connecting reduced-order vector resonant controllers with different resonant frequencies in parallel on the current loop, wherein the reduced-order vector resonant controller tracks a sinusoidal signal of a specified resonant frequency and suppresses current harmonics by compensation; The setting is based on reduced-order vector resonance and generalized active disturbance rejection controller, where the generalized active disturbance rejection controller includes the stator winding The generalized extended state observer corresponding to the axis and the stator winding The generalized extended state observer corresponding to the axis, The generalized extended state observer corresponding to the axis is expressed as: In the formula, Respectively, the current , unknown total disturbance and the first-order derivative of the unknown total disturbance The estimate, yes q Shaft current estimation error, yes q Shaft stator current, , is the inductance of the permanent magnet synchronous motor, represent Shaft voltage, express The axis has known coupled interference, , , represents the observer gain coefficient; The generalized extended state observer corresponding to the axis is expressed as: In the formula, Respectively, the current , unknown total disturbance and the first-order derivative of the unknown total disturbance The estimate, yes d Shaft current estimation error, yes d Shaft stator current, , is the inductance of the permanent magnet synchronous motor, represent Shaft voltage, express The axis has known coupled interference, , , represents the observer gain coefficient; The reduced-order vector resonance and the generalized auto-disturbance rejection controller are connected in parallel and serve as a current loop controller, wherein the generalized control law is obtained by connecting the reduced-order vector resonance and the generalized auto-disturbance rejection controller in parallel. The generalized control law corresponding to the axis is expressed as: In the formula represent q Axis generalized control law, , represent The reference current of the axis, represent The control gain of the axis, Represents the reduced-order vector resonant controller Shaft output; The generalized control law corresponding to the axis is expressed as: In the formula represent d Axis generalized control law, , represent The reference current of the axis, represent The control gain of the axis, Represents the reduced-order vector resonant controller Shaft output; The reduced-order vector resonance and generalized auto-disturbance rejection controller are used to eliminate AC periodic disturbances and DC non-periodic disturbances; The reduced-order vector resonant controller expression is as follows: in, and are the proportional and resonant coefficients, respectively, is an imaginary unit, represents the Laplace operator, represents the resonant frequency, Indicates the cutoff frequency.

2. The method for suppressing current harmonics of a permanent magnet synchronous motor according to claim 1, characterized in that: The stator voltage equation of the permanent magnet synchronous motor is expressed as follows: In the formula, and Represents the stator flux Axis and Axis component; and Respectively represent Shaft stator current and voltage, and Respectively represent Shaft stator current and voltage, and Represents the stator winding Axis and Shaft inductance, represents the stator one-phase resistance, is the number of motor pole pairs, is the mechanical angular velocity of the motor, is the permanent magnet flux.

3. The method for suppressing current harmonics of a permanent magnet synchronous motor according to claim 2, characterized in that: The permanent magnet synchronous motor is a surface mounted permanent magnet synchronous motor.

4. The method for suppressing current harmonics of a permanent magnet synchronous motor according to claim 3, characterized in that: Said ,in, Refers to the stator inductance of a permanent magnet synchronous motor.

5. The method for suppressing current harmonics of a permanent magnet synchronous motor according to claim 1, characterized in that: The reduced-order vector resonance controller is used to suppress the fifth and seventh harmonics in the three-phase current of the permanent magnet synchronous motor.

6. The method for suppressing current harmonics of a permanent magnet synchronous motor according to claim 1, characterized in that: DC non-periodic disturbances include parameter perturbations.

7. The method for suppressing current harmonics of a permanent magnet synchronous motor according to claim 1, characterized in that: The disturbance compensation of the generalized control law based on reduced-order vector resonance and generalized active disturbance rejection controller includes: Compensation for known coupled disturbances, compensation for reference current change disturbances based on step disturbance compensation, compensation for DC disturbances, and compensation for AC harmonic disturbances.

8. The method for suppressing current harmonics of a permanent magnet synchronous motor according to claim 1, characterized in that: The permanent magnet synchronous motor also includes a speed loop, and the speed loop adopts proportional integral control.

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