Iterative phase-locked limit loop flux observer, control method, device and system

Abstract

The invention discloses an iterative phase-locked limit loop flux observer, a control method, a device and a system. The control method comprises the following steps: collecting motor αβ Shaft voltage and current signals, construction α β The IPMSM mathematical model under the shaft system is used to calculate the motor back electromotive force vector; the motor back electromotive force vector is used as input to obtain the motor rotor flux information through the iterative phase-locked limit loop flux observer, and the motor speed and position signal are estimated based on the motor rotor flux information; the motor speed and position signal are input into the motor closed-loop control system to achieve position sensorless closed-loop control of the permanent magnet synchronous motor. The method provided by the present invention can avoid the problems of integral drift or phase lag in traditional flux observers, effectively suppress the influence of DC bias on the accuracy of flux and position observation, and significantly improve the dynamic response capability of position sensorless control, suppressing the position estimation error generated by the dynamic process.

Description

Technical Field

[0001] The present invention belongs to the field of permanent magnet synchronous motor control, and in particular relates to an iterative phase-locked limit loop flux observer, a control method and device, and a system. Background Art

[0002] The permanent magnet synchronous motor position sensorless drive system can achieve high-efficiency, low-maintenance frequency and high-power density electromechanical energy conversion at low cost, and is widely used in the fields of fans, compressors and rail transportation. According to different principles, it can be divided into high-frequency signal injection method and baseband model method. The high-frequency signal injection method requires the injection of auxiliary signals into the motor stator, which will increase system losses and reduce voltage utilization. It is usually used for zero-speed and low-speed operation of the permanent magnet synchronous motor position sensorless drive system.

[0003] The fundamental frequency model method does not require additional auxiliary signal injection. It can obtain accurate speed and position information by designing an advanced observer based on the motor fundamental frequency model to estimate the back EMF or flux information. Many scholars have used methods such as model reference adaptation, extended Kalman filter and sliding mode observer to design back EMF observers, but the back EMF amplitude is proportional to the motor speed. When the motor is running at low speed, non-ideal factors such as inverter nonlinear factors, DC bias and harmonic components will significantly reduce the signal-to-noise ratio of the back EMF component, thereby reducing the control accuracy of the back EMF fundamental frequency model method.

[0004] The fundamental frequency model method based on rotor flux obtains the rotor flux information of the motor by integrating or equivalently integrating the motor back electromotive force to extract the motor speed and position. When pure integration is used as the rotor flux observer, the integral drift and initial value error will cause the estimated flux information to produce a slope bias, resulting in a decrease in calculation accuracy or even divergence. In order to suppress DC bias, a high-pass filter is usually cascaded after pure integration to solve the integral drift problem of pure integration, which is equivalent to using a low-pass filter as a flux observer, but the low-pass filter will cause the estimated flux information to have phase lag and amplitude attenuation. The resonant frequency of the second-order generalized integral (with unity gain and zero phase lag) can deviate from 0Hz. The second-order generalized integral is used as a flux observer to avoid the amplitude attenuation and phase lag introduced by the low-pass filter, but it uses a linear oscillator as an orthogonal signal generator, and the observation performance depends on the initial value of the integral. Further use of a nonlinear oscillator can improve the robustness of the observer.

[0005] After obtaining the rotor flux signal, a phase-locked loop is usually used to extract the motor speed and position information. However, the traditional phase-locked loop uses a PI controller as a loop filter. Its linear characteristics and fixed parameters cannot meet the frequently changing working conditions of the motor, such as the inability to accurately track the input when the frequency ramp signal is used, thereby limiting the use of the traditional phase-locked loop in applications where the motor frequency changes rapidly. A new type of iterative phase-locked loop has been proposed in the prior art, which uses the principle of iterative operation to solve equations to search for the motor rotor position to improve the dynamic response capability of the phase-locked loop, and does not require the adjustment of control parameters. However, this method requires 64 iterations to optimize in order to obtain a theoretical observation accuracy of 0.003rad, which will undoubtedly significantly increase the burden on the digital controller.

[0006] In summary, how to achieve high-precision and low-computational burden position sensorless control of permanent magnet synchronous motors has important research significance. Summary of the invention

[0007] The object of the present invention is to provide an iterative phase-locked limit cycle flux observer, a control method and device, and a system for solving the above-mentioned problems.

[0008] The present invention provides the following technical solutions:

[0009] In a first aspect, the present invention provides a limit cycle flux observer, wherein the limit cycle flux observer designs a rotor flux observer based on a limit cycle oscillator, and the limit cycle flux observer comprises:

[0010] The convergence radius setting module is used to set the convergence radius to meet: Where A is the convergence radius of the limit cycle system, e sα With e sβ is the back electromotive force signal of the αβ axis motor;

[0011] An observer construction module is used to construct a limit cycle flux observer by introducing a tracking error term of back electromotive force to obtain rotor flux information;

[0012] The limit cycle flux observer is:

[0013]

[0014] Where the superscript “^” represents the estimated quantity, k and γ (k, γ>0) are the adjustable gains of the limit cycle flux observer, and ε e＝ [ε eα ε eβ ] T is the back-EMF tracking error vector, is the rotor flux vector obtained by the limit cycle flux observer, is the estimated back-EMF DC vector, is the estimated back EMF vector, for Orthogonal vector of ;

[0015] Estimated back EMF vector The actual back electromotive force vector e s The transfer function between is expressed as:

[0016]

[0017] The rotor flux vector estimated by the limit cycle flux observer The actual back electromotive force vector e s The transfer function between is expressed as:

[0018]

[0019] Where Q(s) is and The transfer function between .

[0020] In a second aspect, the present invention provides an iterative phase-locked loop, wherein the iterative phase-locked loop is based on Newton iteration, and the iterative phase-locked loop comprises:

[0021] The normalization module is used to normalize the rotor flux information and calculate the normalized rotor flux in the γδ axis coordinate system;

[0022] The compensation angle setting module is used to divide the entire calculation domain into four regions I-IV according to the sign of the rotor flux in the γδ coordinate system, and set the iterative initial value compensation angle according to the partitions;

[0023] The iterative initial value compensation angle θ is set according to the partition c for:

[0024]

[0025] An iterative initial value module is used to compensate regions I and IV to regions II and III according to an initial value compensation angle, and determine an iterative initial value;

[0026] The initial value of the iteration θ e(0) It is expressed as:

[0027]

[0028] The cost function module is used to obtain the equivalent position error based on the normalized rotor flux in the γδ axis coordinate system and construct a cost function to extract the rotor position;

[0029] The calculation accuracy module is used to calculate the calculation accuracy under different iteration times, so as to determine whether the iteration times are reasonable;

[0030] The differential module is used to obtain the motor speed by differentiating the rotor position after obtaining the rotor position.

[0031] In one implementation, the equivalent position error is:

[0032]

[0033] Among them, E err is the equivalent position error, is the normalized αβ-axis rotor flux information, is the normalized γδ-axis rotor flux information, is the estimated rotor position error, θ e is the actual value of the rotor position, is the observed value of the rotor position;

[0034] The rotor position is obtained by constructing a cost function through the equivalent position error;

[0035] The cost function J new for:

[0036]

[0037] The acquisition of the rotor position can be equivalent to solving:

[0038]

[0039] To solve the above equation, define the Newton iteration formula related to the estimated rotor position:

[0040]

[0041] In one implementation, the difference between the initial iteration value and the motor rotor position is limited to within the interval [-π / 2, π / 2] rad, thereby increasing the convergence speed of the Newton iteration method and reducing the calculation domain of the Newton iteration method.

[0042] In one embodiment, the calculation accuracy at different iteration numbers is calculated by the following formula:

[0043]

[0044] Among them, θ err(j-1) With θ err(j) is the calculation error between the j-1th and jth iterations, and is the rotor position information calculated at the j-1th and jth iterations.

[0045] In the third aspect, the present invention provides an iterative phase-locked limit cycle flux observer, which is used to obtain the motor rotor flux information and extract the motor speed and position signals; the extracted motor speed and position signals are used to input into the motor closed-loop control system to realize position sensorless closed-loop control of the permanent magnet synchronous motor; the iterative phase-locked limit cycle flux observer includes the above-mentioned iterative phase-locked loop and the above-mentioned limit cycle flux observer; the limit cycle flux observer is used to obtain the motor rotor flux information; the iterative phase-locked loop is used to extract the motor speed and position information according to the rotor flux information of the limit cycle flux observer, and feed the speed back to the limit cycle flux observer.

[0046] In a fourth aspect, the present invention provides a permanent magnet synchronous motor control method based on an iterative phase-locked limit cycle flux observer, the method comprising:

[0047] Collect the voltage and current signals of the motor's αβ axis, build the IPMSM mathematical model under the αβ axis system, and calculate the motor's back electromotive force vector;

[0048] The motor back electromotive force vector is used as input, and the motor rotor flux information is obtained through the above-mentioned iterative phase-locked limit cycle flux observer, and the motor speed and position signals are estimated according to the motor rotor flux information;

[0049] The motor speed and position signals are input into the motor closed-loop control system to realize position sensorless closed-loop control of the permanent magnet synchronous motor.

[0050] In a possible implementation, after obtaining the motor speed, the method further includes: using a low-pass filter to smooth the estimated speed to suppress high-frequency noise introduced by differentiation.

[0051] In a fifth aspect, the present invention provides a permanent magnet synchronous motor control device based on an iterative phase-locked limit cycle flux observer, the device comprising:

[0052] IPMSM mathematical model module, used to collect the voltage and current signals of the motor αβ axis, build the IPMSM mathematical model under the αβ axis system, and calculate the motor back electromotive force vector;

[0053] The above-mentioned iterative phase-locked limit loop flux observer is used to take the motor back electromotive force vector as input, obtain the motor rotor flux information, and estimate the motor speed and position signal according to the motor rotor flux information;

[0054] The motor speed and position signal transmission module is used to input the motor speed and position signals extracted by the iterative phase-locked limit loop flux observer into the motor closed-loop control system to realize position sensorless closed-loop control of the permanent magnet synchronous motor.

[0055] In a sixth aspect, the present invention provides a permanent magnet synchronous motor control system, the system comprising: the above-mentioned permanent magnet synchronous motor control device based on iterative phase-locked limit cycle flux observer.

[0056] Beneficial effects of the present invention:

[0057] (1) The present invention designs a rotor flux observer based on a nonlinear limit cycle oscillator. By designing a unique closed trajectory of the back-electromotive force limit cycle system, accurate observation of the motor rotor flux information is achieved, thereby solving the problems of integral drift or phase lag in traditional flux observers and suppressing the influence of DC bias on the accuracy of flux and position observation. The present invention can be used for asynchronous motor position sensorless control technology and synchronous reluctance motor position sensorless control technology.

[0058] (2) The present invention designs a new iterative phase-locked loop, which sets the iterative initial value compensation angle by partitioning the rotor flux signal, and realizes high-precision rotor position observation through three iterative operations based on Newton iteration operation. It can avoid the setting of phase-locked loop parameters and improve the dynamic response capability of position sensorless control. It can be used for grid-connected synchronization technology, asynchronous motor position sensorless control technology and synchronous reluctance motor position sensorless control technology.

[0059] (3) The present invention combines a limit cycle flux observer with an iterative phase-locked loop to form an iterative phase-locked limit cycle flux observer, which is used to improve the dynamic response capability of the permanent magnet synchronous motor position sensorless control and realize the permanent magnet synchronous motor position sensorless control with high precision and low computational burden. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The accompanying drawings are part of the present invention and are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but do not constitute an improper limitation of the present invention. Obviously, the accompanying drawings described below are only some embodiments. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0061] Figure 1 The partitioning of the entire calculation domain and the setting of the compensation angle provided in one embodiment of the present invention;

[0062] Figure 2 A control block diagram of an iterative phase-locked limit loop flux observer provided in one embodiment of the present invention;

[0063] Figure 3 A flow chart of a permanent magnet synchronous motor control method provided in one embodiment of the present invention;

[0064] Figure 4 Bode diagram of a pure integrator, a low-pass filter and a limit cycle flux observer provided in one embodiment of the present invention;

[0065] Figure 5 It is a Bode diagram of a limit cycle flux observer under parameter conditions provided in one embodiment of the present invention; Figure 5 (a) Bode diagram of limit loop flux observer under different k conditions; Figure 5 (b) Bode diagram of limit loop flux observer under different γ conditions;

[0066] Figure 6 is E under different position error conditions provided in an embodiment of the present invention err With J new ;

[0067] Figure 7 A schematic diagram of the structure of a permanent magnet synchronous motor control system provided in one embodiment of the present invention;

[0068] Figure 8 The steady-state experimental comparison results of the pure integral, low-pass filter and limit cycle flux observer provided in one embodiment of the present invention are shown in FIG. Figure 8 (a) is the steady-state experimental result of pure integration, Figure 8 (b) is the steady-state experimental result of the low-pass filter. Figure 8 (c) is the steady-state experimental result of the limit cycle flux observer;

[0069] Fig. 9 The results of the rotor flux experiment comparison under the α-axis back electromotive force 10V DC disturbance provided in one embodiment of the present invention are as follows; wherein, Fig. 9 (a) is the rotor flux experimental result of the low-pass filter. Fig. 9 (b) is the steady-state experimental result of the limit cycle flux observer;

[0070] Fig.10 An embodiment of the present invention provides experimental comparison results of rapid acceleration and deceleration between a conventional phase-locked loop and an iterative phase-locked loop; wherein, Fig.10 (a) is the experimental result of the traditional phase-locked loop. Fig.10 (b) is the experimental result of iterative phase-locked loop;

[0071] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but are intended to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0072] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0073] The present invention aims to solve the problems of integral drift or phase lag of the traditional flux observer in the existing permanent magnet synchronous motor position sensorless control technology and the problem that the traditional phase-locked loop cannot meet the frequent changes in motor working conditions, so that the permanent magnet synchronous motor position sensorless drive system can operate efficiently and stably.

[0074] Example 1

[0075] The disclosed embodiment of the present invention provides a limit cycle flux observer, which is based on a limit cycle oscillator to design a rotor flux observer, and the limit cycle flux observer includes:

[0076] The convergence radius setting module is used to set the convergence radius to meet: Where A is the convergence radius of the limit cycle system, e sα With e sβ is the back electromotive force of the αβ shaft motor;

[0077] An observer construction module is used to construct a limit cycle flux observer by introducing a tracking error term of back electromotive force to obtain rotor flux information;

[0078]

[0079] Where the superscript “^” represents the estimated quantity, k and γ (k, γ>0) are the adjustable gains of the limit cycle flux observer, and ε e＝ [ε eα ε eβ ] T is the back-EMF tracking error vector, is the rotor flux vector obtained by the limit cycle flux observer, is the estimated back-EMF DC vector, is the estimated back EMF vector, for Orthogonal vector of .

[0080] When the system is in steady state, the system trajectory converges to a closed orbit, which is the nonlinear part of the limit cycle flux observer. Then for the Laplace operator and The transfer function between is expressed as:

[0081]

[0082] From this formula, we can see that when the system is in a steady state, Q(s) can be used as an integrator, and the numerator It can ensure the normalization of the observed magnetic flux signal.

[0083] Furthermore, the limit cycle flux observer is converted to the s domain, and we have:

[0084]

[0085] use Delocalize the above formula:

[0086]

[0087] Furthermore, the estimated back EMF vector The actual back electromotive force vector e s The transfer function between is expressed as:

[0088]

[0089] Furthermore, the rotor flux vector estimated by the limit cycle flux observer The actual back electromotive force vector e s The transfer function between is expressed as:

[0090]

[0091]

[0092] Where Q(s) is and The transfer function between .

[0093] The DC bias E 0 / s is used as the input of the limit cycle flux observer, and Laplace’s final value theorem gives:

[0094]

[0095] Example 2

[0096] Newton's iteration method is an iterative method for solving nonlinear equations with an extremely fast convergence speed. The convergence speed is related to the selection of the initial value of the iteration. The closer the initial value of the iteration is to the optimal result, the faster the convergence speed.

[0097] Based on Newton iteration, an iterative phase-locked loop is provided in the disclosed embodiment of the present invention, and the iterative phase-locked loop includes:

[0098] The normalization module is used to normalize the rotor flux information and calculate the normalized rotor flux in the γδ axis coordinate system;

[0099] The compensation angle setting module is used to divide the entire calculation domain into four regions I-IV according to the sign of the rotor flux in the γδ coordinate system, and set the iterative initial value compensation angle according to the partitions;

[0100] An iterative initial value module is used to compensate regions I and IV to regions II and III according to an initial value compensation angle, and determine an iterative initial value;

[0101] The cost function module is used to obtain the equivalent position error based on the normalized rotor flux in the γδ axis coordinate system and construct a cost function to extract the rotor position;

[0102] The calculation accuracy module is used to calculate the calculation accuracy under different iteration times, so as to determine whether the iteration times are reasonable;

[0103] The differential module is used to obtain the motor speed by differentiating the rotor position after obtaining the rotor position.

[0104] In order to facilitate the design of iterative phase-locked loop, the rotor flux signal obtained by the limit cycle flux observer is normalized:

[0105]

[0106] in, is the normalized rotor flux vector. In order to select the initial value of the iteration close to the optimal result, the normalized rotor flux of the γδ axis (i.e., the estimated dq axis) coordinate system is calculated:

[0107]

[0108] in, and is the normalized γδ-axis rotor flux, is the estimated rotor position error.

[0109] Generally, the position observation value of the previous cycle is used As the initial value of the iteration, in order to facilitate the initial value of the iteration to approach the optimal result, the partition of the entire calculation domain is as follows Figure 1 As shown in the figure, the entire computational domain is divided into four regions (I-IV) according to the sign of the rotor flux in the γδ coordinate system, and the iterative initial value compensation angle θ is set according to the partitions. c :

[0110]

[0111] The initial compensation angle can compensate areas I and IV to areas II and III, so the final iteration initial value θ e(0) It is expressed as:

[0112]

[0113] Iteration initial value θ e(0) The difference between the motor rotor position and errIt can be limited to the interval (-π / 2,π / 2) rad, thereby improving the convergence speed of the Newton iteration method and reducing the calculation domain of the Newton iteration method.

[0114] Furthermore, the equivalent position error of the rotor flux design in the normalized γδ axis coordinate system is obtained:

[0115]

[0116] Among them, E err is the equivalent position error, is the normalized αβ-axis rotor flux information, is the normalized γδ-axis rotor flux information, is the estimated rotor position error, θ e is the actual value of the rotor position, is the observed value of the rotor position;

[0117] The rotor position is obtained by constructing a cost function through the equivalent position error;

[0118] The cost function J new for:

[0119]

[0120] The acquisition of the rotor position can be equivalent to solving:

[0121]

[0122] To solve the above equation, define the Newton iteration formula related to the estimated rotor position:

[0123]

[0124] Furthermore, for the iterative phase-locked loop, the number of iterations is proportional to the amount of calculation of the digital controller. To design a reasonable number of iterations, it is necessary to determine the calculation accuracy of the Newton iteration method under different numbers of iterations. The calculation accuracy under different numbers of iterations can be calculated by the following formula:

[0125]

[0126] Among them, θ err(j-1) With θ err(j) is the calculation error between the j-1th and jth iterations, and is the rotor position information calculated at the j-1th and jth iterations.

[0127] After obtaining the rotor position, the motor speed can be obtained by differentiating the rotor position.

[0128] Example 3

[0129] The present invention discloses an iterative phase-locked limit cycle flux observer, which is used to extract motor speed and position signals by acquiring motor rotor flux information; the extracted motor speed and position signals are used to input into the motor closed-loop control system to realize position sensorless closed-loop control of the permanent magnet synchronous motor; the iterative phase-locked limit cycle flux observer includes the above-mentioned iterative phase-locked loop and the above-mentioned limit cycle flux observer; the limit cycle flux observer is used to acquire motor rotor flux information; the iterative phase-locked loop is used to extract motor speed and position information according to the rotor flux information of the limit cycle flux observer, and feed the speed back to the limit cycle flux observer.

[0130] Control block diagram of iterative phase-locked limit cycle flux observer, refer to Figure 2 For the description of the limit cycle flux observer and the iterative phase-locked loop, please refer to the description of the same or similar parts above, which will not be repeated here.

[0131] Example 4

[0132] Reference Figure 3 As shown, the present disclosure provides a permanent magnet synchronous motor control method based on an iterative phase-locked limit cycle flux observer, and the method specifically includes the following steps:

[0133] Step S100: collecting the voltage and current signals of the motor αβ axis, constructing the IPMSM mathematical model under the αβ axis system, and calculating the motor back electromotive force vector.

[0134] Furthermore, the mathematical model of IPMSM under the αβ axis system can be expressed as:

[0135]

[0136] where u α 、u β is the stator voltage αβ axis component, i α 、i β is the stator current αβ axis component, R s With L q is the stator resistance and q-axis inductance, p is the differential operator, θ e is the motor rotor position, ψ af is the effective flux, ψ af It can be expressed as:

[0137] ψ af =ψ f +(L d -L q )i d

[0138] Where Ld is the d-axis inductance. The vector form of the IPMSM mathematical model under the αβ axis system is:

[0139] u s =R s i s +pψ s

[0140] Among them, u s =[u α u β ] T ,i s =[i α i β ] T , ψ s is the stator flux vector, ψ s It can be expressed as:

[0141] ψ s =L q i s +ψ af [cosθ e sinθ e )] T

[0142] Furthermore, according to the IPMSM mathematical model under the αβ axis system, the motor rotor flux vector is obtained.

[0143] According to the above formula, the rotor flux vector can be obtained:

[0144] ψ r =∫(u s -R s i s -pL q i s )dt=∫e s dt

[0145] Among them, ψ r =[ψ rα ψ rβ ] T =[ψ af cosθ e ψ af sinθ e ] T is the rotor flux vector, e s =[e sα e sβ ] T is the back electromotive force vector.

[0146] Step S200: taking the motor back electromotive force vector as input, obtaining the motor rotor flux information through an iterative phase-locked limit cycle flux observer, and estimating the motor speed and position signal according to the motor rotor flux information.

[0147] For the description of the iterative phase-locked limit cycle flux observer, please refer to the description of the same or similar parts above, which will not be repeated here.

[0148] For a general linear sinusoidal oscillator (such as a second-order generalized integral), the system has a series of closed orbits, and external disturbances or parameter mismatches may cause the system orbit to shift. For a nonlinear limit cycle oscillator, the system has only a unique closed trajectory. This feature makes the limit cycle oscillator robust to external interference near the convergence radius A, thereby ensuring the stability of the system. In addition, the limit cycle oscillator does not depend on the initial conditions of the system. Benefiting from the above advantages, the present invention designs a rotor flux observer based on a limit cycle oscillator to solve the problem of integral drift or phase lag in traditional flux observation schemes, and suppress the influence of DC bias on the accuracy of flux and position observation.

[0149] To verify the ability of the limit cycle flux observer to suppress DC bias and high-order harmonics, the Bode plots of pure integrator, low-pass filter and limit cycle flux observer are shown in Figure 2. Figure 4 As shown, the motor operating frequency is 100Hz, the cutoff frequency of LPF is 100rad / s, and the limit cycle flux observer parameters are k=1.414 and γ=85. The pure integrator will produce a time-varying ramp bias, causing the estimated flux to be saturated; the low-pass filter can suppress the DC component and high-order harmonics, and its amplitude attenuation rate is -20dB / decade, but it will cause significant amplitude attenuation and phase shift; the limit cycle flux observer has the ability to suppress DC components and high-order harmonics, and the amplitude attenuation rates below and above the center frequency are -20dB / decade and -40dB / decade respectively.

[0150] Figure 5 The Bode diagram of the limit cycle flux observer under different k and γ conditions is shown. Figure 5 As shown in (a), increasing the parameter k is conducive to improving the observer bandwidth, thereby improving the dynamic response capability of the system, but it will reduce the frequency selectivity of the observer. Therefore, the selection of parameter k needs to balance the dynamic response capability and frequency selectivity of the observer. Figure 5 As shown in (b), increasing the parameter γ is beneficial to improving the DC bias suppression capability of the observer, but an excessively large parameter γ will cause orthogonal signal oscillations outside the resonant frequency.

[0151] After obtaining the motor rotor flux information, an iterative phase-locked loop based on Newton iteration is used to extract the motor speed and position information.

[0152] According to the calculation accuracy formula, the estimation error of the Newton iteration method after different iteration times under different initial value conditions is shown in Table 1. It can be seen from the table that even if there is an error of ±π / 2rad in the initial value of the iteration, the estimation error can be limited to 4.73×10 -6 rad, which can meet the accuracy requirements of most fixed-point or floating-point operations.

[0153] Table 1 Estimation error of Newton iteration method after different iteration times under different initial value conditions

[0154]

[0155] Figure 6 The E under different position error conditions is given. err With J new .Depend on Figure 6 It can be seen that the cost function J new The entire computational domain contains only one convergence point, that is, only by minimizing the cost function J new , the position estimation error can converge to only 0rad.

[0156] Step S300: Input the motor speed and position signals into the motor closed-loop control system to implement position sensorless closed-loop control of the permanent magnet synchronous motor.

[0157] In a possible implementation, after obtaining the motor speed, the method further includes: using a low-pass filter to smooth the estimated speed to suppress high-frequency noise introduced by differentiation.

[0158]

[0159] Where k represents the sampling time, T s is the sampling period.

[0160] The following is an embodiment of the permanent magnet synchronous motor control device based on the iterative phase-locked limit cycle flux observer of the present invention, which can be used to execute the embodiment of the permanent magnet synchronous motor control method based on the iterative phase-locked limit cycle flux observer of the present invention. For details not disclosed in the embodiment of the permanent magnet synchronous motor control device based on the iterative phase-locked limit cycle flux observer of the present invention, please refer to the embodiment of the permanent magnet synchronous motor control method based on the iterative phase-locked limit cycle flux observer of the present invention.

[0161] Example 5

[0162] An exemplary embodiment of the present invention provides a permanent magnet synchronous motor control device based on an iterative phase-locked limit cycle flux observer, referring to Figure 7Schematic diagram of the structure of a permanent magnet synchronous motor control system. The permanent magnet synchronous motor control device can be implemented as all or part of a terminal through software, hardware, or a combination of both. The permanent magnet synchronous motor control device based on an iterative phase-locked limit cycle flux observer includes:

[0163] IPMSM mathematical model module, used to collect the voltage and current signals of the motor αβ axis, build the IPMSM mathematical model under the αβ axis system, and calculate the motor back electromotive force vector;

[0164] The above-mentioned iterative phase-locked limit loop flux observer is used to take the motor back electromotive force vector as input, obtain the motor rotor flux information, and extract the motor speed and position signal according to the motor rotor flux information;

[0165] The motor speed and position signal transmission module is used to input the motor speed and position signals extracted by the iterative phase-locked limit loop flux observer into the motor closed-loop control system to realize position sensorless closed-loop control of the permanent magnet synchronous motor.

[0166] Optionally, the permanent magnet synchronous motor control device based on the iterative phase-locked limit cycle flux observer also includes a filter module for smoothing the estimated rotation speed using a low-pass filter to suppress high-frequency noise introduced by differentiation.

[0167] It should be noted that the permanent magnet synchronous motor control device based on the iterative phase-locked limit cycle flux observer provided in the above embodiment only uses the division of the above functional modules as an example when executing the permanent magnet synchronous motor control method based on the iterative phase-locked limit cycle flux observer. In practical applications, the above functional distribution can be completed by different functional modules as needed, that is, the internal structure of the device is divided into different functional modules to complete all or part of the functions described above. In addition, the permanent magnet synchronous motor control device based on the iterative phase-locked limit cycle flux observer provided in the above embodiment and the permanent magnet synchronous motor control method embodiment based on the iterative phase-locked limit cycle flux observer belong to the same concept. The implementation process thereof is detailed in the permanent magnet synchronous motor control method embodiment based on the iterative phase-locked limit cycle flux observer, which will not be repeated here.

[0168] Continue to refer to Figure 7 As shown, in one embodiment, a permanent magnet synchronous motor control system is proposed, which includes the above-mentioned permanent magnet synchronous motor control device based on iterative phase-locked limit cycle flux observer.

[0169] The specific working process of the system is as follows: subtract the estimated rotor electrical angular velocity from the given rotor electrical angular velocity to obtain the speed difference; input the speed difference into the maximum torque current ratio (MTPA) controller to obtain the dq axis given current; obtain the three-phase current of the permanent magnet synchronous motor through A / D sampling, and sequentially transform the three-phase current through Clark transformation and Park transformation to obtain the current feedback value; subtract the dq axis given current from the current feedback value to obtain the current difference; input the current difference into the PI controller to obtain the dq axis reference voltage; transform the dq axis reference voltage through coordinates to obtain the αβ axis voltage; input the αβ axis voltage into the SVPWM modulation module to output the duty cycle signal; input the duty cycle signal into the inverter to control the inverter on and off and the above-mentioned permanent magnet synchronous motor control device. Based on the description of the control device, refer to the description of the same or similar parts above, which will not be repeated here.

[0170] The beneficial effects of the present invention are verified by a 750W permanent magnet synchronous motor experimental platform. The parameters of the 750W permanent magnet synchronous motor are: rated frequency 250Hz, rated speed 3000rpm, pole pair number 5, d-axis inductance 4.7mH, q-axis inductance 6.7mH, stator resistance 0.9Ω, permanent magnet flux linkage 0.054Wb, and rated current 4.2A. A hysteresis brake is used as the motor load, a two-level three-phase inverter is used to drive the permanent magnet synchronous motor, and a DSP TMS320F28335 is used to implement the control algorithm, and the sampling frequency and switching frequency are both 10kHz.

[0171] Figure 8 The steady-state experimental comparison results of pure integration, low-pass filter and iterative phase-locked limit loop flux observer are shown in Figure 2. The motor speed is 300 rpm. Figure 8 (a) is the steady-state experimental result of pure integration, Figure 8 (b) is the steady-state experimental result of the low-pass filter. Figure 8 (c) is the steady-state experimental result of iterative phase-locked limit loop flux observer. Figure 8 As shown in (a), due to the existence of DC disturbance in the back EMF, the stator flux signal estimated by pure integration seriously deviates from the ideal flux trajectory, resulting in the inability to track the motor rotor position signal; Figure 8 As shown in (b), since the low-pass filter is equivalent to the cascade of pure integration and high-pass filters, the rotor flux signal estimated by the low-pass filter has significant phase advance and amplitude attenuation; Figure 8 As shown in (c), the motor rotor flux signal estimated by the iterative phase-locked limit loop flux observer is close to the ideal flux trajectory and can accurately track the motor rotor position signal.

[0172] Fig. 9 The comparison results of the rotor flux experiment under the α-axis back electromotive force 10V DC disturbance, where the motor speed is 300rpm, Fig. 9(a) is the rotor flux experimental result of the low-pass filter. Fig. 9 (b) is the steady-state experimental result of iterative phase-locked limit loop flux observer. Fig. 9 As shown in (a), after applying a 10V DC disturbance to the α-axis back EMF, the α-axis rotor flux signal estimated by the low-pass filter will produce a DC bias, which will lead to a rotor position fundamental frequency disturbance in the estimated rotor position; Fig. 9 As shown in (b), after a 10V DC disturbance is applied to the α-axis back EMF, the iterative phase-locked limit loop flux observer can effectively compensate for the α-axis flux DC bias and converge to a steady state after two electrical cycles. During the entire operation, the rotor position error is within ±10.0 degrees, indicating that the iterative phase-locked limit loop flux observer has good anti-disturbance performance and observation accuracy.

[0173] Fig.10 The experimental comparison results of the traditional phase-locked loop and the iterative phase-locked loop in rapid acceleration and deceleration are shown in Figure 1. The speed change trend is 500~1725~3000~2000~1000, and the acceleration in acceleration and deceleration is 1500rpm / s and 800rpm / s respectively. Fig.10 (a), the maximum position estimation error of the traditional phase-locked loop can reach 27.0 degrees during the entire dynamic process. Fig.10 (b) After adopting the iterative phase-locked loop, the maximum position estimation error in the entire dynamic process can be limited to 8.4 degrees, indicating that the iterative phase-locked limit loop flux observer can significantly improve the dynamic response capability of position sensorless control and suppress the position estimation error generated by the dynamic process.

[0174] The above experimental effect diagrams show that the permanent magnet synchronous motor control method of the present invention can avoid the problems of integral drift or phase lag in traditional flux observers, effectively suppress the influence of DC bias on the accuracy of flux and position observation, and significantly improve the dynamic response capability of position sensorless control, thereby suppressing the position estimation error caused by the dynamic process.

[0175] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0176] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An iterative phase-locked loop, characterized in that: The iterative phase-locked loop is based on Newton iteration, and the iterative phase-locked loop includes: The normalization module is used to normalize the rotor flux information and calculate the normalized rotor flux in the γδ axis coordinate system; The compensation angle setting module is used to divide the entire calculation domain into four regions I-IV according to the sign of the rotor flux in the γδ coordinate system, and set the iterative initial value compensation angle according to the partitions; The iterative initial value compensation angle is set according to the partition as follows: Among them, θ c To set the initial value compensation angle of iteration according to the partition, and is the rotor flux of γδ axis; An iterative initial value module is used to compensate the rotor position estimation error from regions I and IV to regions II and III according to the initial value compensation angle, and determine an iterative initial value; The initial value of the iteration is expressed as: Among them, θ e(0) is the initial value of the iteration, is the position observation value of the previous period; The cost function module is used to obtain the equivalent position error based on the normalized rotor flux in the γδ axis coordinate system and construct a cost function to extract the rotor position; The calculation accuracy module is used to calculate the calculation accuracy under different iteration times, so as to determine whether the iteration times are reasonable; The differential module is used to obtain the motor speed by differentiating the rotor position after obtaining the rotor position.

2. The iterative phase-locked loop according to claim 1, characterized in that: The equivalent position error is: Among them, E err is the equivalent position error, is the normalized αβ-axis rotor flux information, is the normalized γδ-axis rotor flux information, is the estimated rotor position error, θ e is the actual value of the rotor position, is the observed value of the rotor position; The rotor position is obtained by constructing a cost function through the equivalent position error; The cost function J new for: The acquisition of the rotor position can be equivalent to solving: To solve the above equation, define the Newton iteration formula related to the estimated rotor position:

3. The iterative phase-locked loop according to claim 1, characterized in that: The difference between the initial iteration value and the motor rotor position is limited to the interval [-π / 2,π / 2] rad, thereby improving the convergence speed of the Newton iteration method and reducing the calculation domain of the Newton iteration method.

4. The iterative phase-locked loop according to claim 1, characterized in that: The calculation accuracy under different iteration numbers is calculated by the following formula: Among them, θ err(j-1) With θ err(j) is the calculation error between the j-1th and jth iterations, and is the rotor position information calculated at the j-1th and jth iterations, θ e is the actual value of the rotor position, is the normalized αβ-axis rotor flux information.

5. An iterative phase-locked limit cycle flux observer, characterized in that: The iterative phase-locked limit cycle flux observer is used to obtain the motor rotor flux information and extract the motor speed and position signals; the extracted motor speed and position signals are used to input into the motor closed-loop control system to realize the position sensorless closed-loop control of the permanent magnet synchronous motor; the iterative phase-locked limit cycle flux observer comprises a limit cycle flux observer and an iterative phase-locked loop according to any one of claims 1 to 4; the limit cycle flux observer is used to obtain the motor rotor flux information; the iterative phase-locked loop is used to extract the motor speed and position information according to the rotor flux information of the limit cycle flux observer, and feed the speed back to the limit cycle flux observer; The limit cycle flux observer comprises: The convergence radius setting module is used to set the convergence radius to meet: Where A is the convergence radius of the limit cycle system, e sα With e sβ is the back electromotive force signal of the αβ axis motor; An observer construction module is used to construct a limit cycle flux observer by introducing a tracking error term of back electromotive force to obtain rotor flux information; The limit cycle flux observer is: Where the superscript "^" represents the estimated quantity, k and γ are the adjustable gains of the limit cycle flux observer, k,γ>0, ε e＝ [ε eα ε eβ ] T is the back-EMF tracking error vector, is the rotor flux vector obtained by the limit cycle flux observer, is the estimated back-EMF DC vector, is the estimated back EMF vector, for The orthogonal vector of , p is the differential operator; Estimated back EMF vector The actual back electromotive force vector e s The transfer function between is expressed as: The rotor flux vector estimated by the limit cycle flux observer The actual back electromotive force vector e s The transfer function between is expressed as: Where Q(s) is and The transfer function between .

6. A permanent magnet synchronous motor control method based on iterative phase-locked limit cycle flux observer, characterized in that: The method comprises: Collect the voltage and current signals of the motor's αβ axis, build the IPMSM mathematical model under the αβ axis system, and calculate the motor's back electromotive force vector; Taking the motor back electromotive force vector as input, obtaining the motor rotor flux information through the iterative phase-locked limit cycle flux observer described in claim 5, and estimating the motor speed and position signal according to the motor rotor flux information; The motor speed and position signals are input into the motor closed-loop control system to realize position sensorless closed-loop control of the permanent magnet synchronous motor.

7. The permanent magnet synchronous motor control method based on iterative phase-locked limit cycle flux observer according to claim 6 is characterized in that: After obtaining the motor speed, the following steps are also included: using a low-pass filter to smooth the estimated speed to suppress the high-frequency noise introduced by the differential.

8. A permanent magnet synchronous motor control device based on iterative phase-locked limit cycle flux observer, characterized in that: The device comprises: IPMSM mathematical model module, used to collect the voltage and current signals of the motor αβ axis, build the IPMSM mathematical model under the αβ axis system, and calculate the motor back electromotive force vector; The iterative phase-locked limit cycle flux observer described in claim 5 is used to take the motor back electromotive force vector as input, obtain the motor rotor flux information, and estimate the motor speed and position signal based on the motor rotor flux information; The motor speed and position signal transmission module is used to input the motor speed and position signals extracted by the iterative phase-locked limit loop flux observer into the motor closed-loop control system to realize position sensorless closed-loop control of the permanent magnet synchronous motor.

9. A permanent magnet synchronous motor control system, characterized in that: The system includes: the permanent magnet synchronous motor control device based on iterative phase-locked limit cycle flux observer as described in claim 8.

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