Permanent magnet synchronous motor high-frequency mode identification method based on common-mode voltage injection

Abstract

The invention discloses a permanent magnet synchronous motor high-frequency mode identification method based on common-mode voltage injection, and the method comprises the steps: calculating a sideband common-mode voltage injection range and a sideband harmonic voltage frequency component under the injection according to a sideband harmonic voltage model; a sideband harmonic current frequency component with the maximum amplitude after injection is calculated within the common-mode voltage injection range, and an electromagnetic force wave generated by the sideband harmonic current under the condition serves as a vibration excitation source; increasing the switching frequency according to a specific step length, and carrying out a frequency sweeping experiment; and analyzing the collected data, and correcting a frequency response curve according to a high-frequency electromagnetic force calculation function to obtain modal parameters of the motor. According to the method, the common-mode voltage which has no influence on the fundamental frequency current is injected into the closed-winding permanent magnet synchronous motor, and the sideband harmonic current component with the maximum amplitude after injection is selected as the vibration excitation source for frequency sweeping, so that the identification of the high-frequency mode of the motor is effectively realized. The method can be widely applied to the field of motor mode identification.

Description

Technical Field

[0001] This invention relates to the field of motor mode identification, and in particular to a high-frequency mode identification method for permanent magnet synchronous motors based on common-mode voltage injection. Background Technology

[0002] In the steady-state operation of permanent magnet synchronous motors, accurate analysis of high-frequency modes is an important prerequisite for calculating and suppressing high-frequency vibrations of the motor. Currently, the acquisition of motor modal parameters mainly relies on the hammer impact modal test method. During the experiment using an excitation hammer, the low- and mid-frequency modes of the motor can be identified relatively well. However, due to the limitations of the hammer material and the bandwidth of the hammer force sensor, the energy in the high-frequency domain will decay rapidly, making it difficult to excite and identify high-frequency modes. It is necessary to reduce the error by repeating the experiment many times, which increases the cumbersomeness of the experimental process. Therefore, this type of method is not suitable for the identification of high-frequency modes.

[0003] Modal testing using electromagnetic excitation of motor vibration has attracted attention due to its ability to be actively controlled. By controlling the excitation source with an electromagnetic field, specific frequencies and amplitudes of excitation force can be precisely applied, thus better covering the wide-frequency modal characteristics of the motor. However, adding an external electromagnetic excitation source significantly increases system cost and complexity. Using electromagnetic force waves generated by the motor's own sideband current harmonics as an endogenous electromagnetic excitation source for motor vibration can effectively acquire motor modes under certain operating conditions. However, the current amplitude of these endogenous current harmonics varies with operating conditions, and some low-order modes (such as the first-order stator bending mode) or local modes (such as the end cap mode) are sensitive to excitation energy, while high-order modes or weakly coupled modes require sufficient excitation energy to be effectively excited. Using these endogenous current harmonics as excitation sources may lead to problems such as low signal-to-noise ratio and lack of high-order modes, failing to meet the requirements for modal excitation.

[0004] Therefore, researching a high-frequency mode identification method using an amplitude-adjustable endogenous electromagnetic excitation source is of great significance for the comprehensiveness and accuracy of motor mode identification. Summary of the Invention

[0005] In view of this, in order to solve the technical problem of low mode identification accuracy in existing permanent magnet synchronous motor mode identification methods, which use electromagnetic force waves generated by the sideband current harmonics excited by the motor itself as the endogenous electromagnetic excitation source of motor vibration, this invention proposes a high-frequency mode identification method for permanent magnet synchronous motors based on common-mode voltage injection. This method includes the following steps: Based on the sideband harmonic voltage model, the sideband common-mode voltage injection range and the frequency components of the sideband harmonic voltage under injection are calculated. Calculate the frequency component of the sideband harmonic current with the largest amplitude after injection within the common-mode voltage injection range, select the common-mode injection case, and use the electromagnetic force wave generated by the sideband harmonic current under this case as the vibration excitation source. The switching frequency is increased from low to high in a specific step size. For the frequency range that causes resonance, the step size can be appropriately reduced to perform fine frequency sweeping. The collected data is analyzed, and the frequency response curve is corrected according to the high-frequency electromagnetic force calculation function to obtain the motor's modal parameters.

[0006] Based on the above scheme, this invention provides a high-frequency mode identification method for permanent magnet synchronous motors based on common-mode voltage injection. This method relies on a PWM output harmonic model to accurately analyze the high-frequency vibration characteristics of the motor after common-mode voltage injection. By injecting specific DC bias and third harmonic common-mode components into the modulation wave, the inverter output spectrum is reconstructed, specific frequency peaks are enhanced, and frequency sweeping is completed, thereby accurately identifying the motor modes. With precise control of the common-mode voltage injection, this invention can efficiently achieve accurate identification of permanent magnet synchronous motor modes over a wide frequency range, providing key technical support for motor performance optimization. Attached Figure Description

[0007] Figure 1 This is a flowchart of the steps of a high-frequency mode identification method for permanent magnet synchronous motors based on common-mode voltage injection according to the present invention; Figure 2 This is a schematic diagram illustrating the principle of the motor modulation method using common-mode voltage injection according to a specific embodiment of the present invention; Figure 3 In a specific embodiment of the present invention, under the operating condition of 360 rpm, f s A schematic diagram of the amplitude of the sideband harmonic current at frequency ±f1; Figure 4 In a specific embodiment of the present invention, under the operating condition of 360 rpm, f s A schematic diagram of the amplitude of the sideband harmonic current at frequency ±2f1; Figure 5 This is a specific embodiment of the invention under the 720rpm operating condition, f s A schematic diagram of the amplitude of the sideband harmonic current at frequency ±f1; Figure 6 This is a specific embodiment of the invention under the 720rpm operating condition, f s A schematic diagram of the amplitude of the sideband harmonic current at a frequency of ±2f1. Detailed Implementation

[0008] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0009] It should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings. Unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0010] It should be understood that the terms "system," "apparatus," "unit," and / or "module" used in this application are a method of distinguishing different components, elements, parts, sections, or assemblies at different levels. However, if other terms can achieve the same purpose, they may be replaced by other expressions.

[0011] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," "a," and / or "the" are not specifically singular and may include the plural. Generally, the terms "comprising" and "including" only indicate the inclusion of expressly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements. An element defined by the phrase "comprising an..." does not exclude the presence of other identical elements in the process, method, product, or apparatus that includes the element.

[0012] In the description of the embodiments of this application, "a plurality of" refers to two or more. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0013] Furthermore, flowcharts are used in this application to illustrate the operations performed by the system according to embodiments of this application. It should be understood that the preceding or following operations are not necessarily performed precisely in sequence. Instead, the steps can be processed in reverse order or simultaneously. Additionally, other operations can be added to these processes, or one or more steps can be removed from them.

[0014] Reference Figure 1 This is a flowchart illustrating an optional example of the high-frequency mode identification method for permanent magnet synchronous motors based on common-mode voltage injection proposed in this invention. This method can be applied to computer equipment. The mode identification method proposed in this embodiment may include, but is not limited to, the following steps: Step S1: Calculate the sideband common-mode voltage injection range based on the sideband harmonic voltage model; The content of the sideband harmonic voltage model is shown in equations (5), (6), and (7). Based on the accurate acquisition of the harmonic components of the PWM strategy modulation wave f(t), equations (6) and (7) can be obtained through double Fourier analysis of equation (5). In addition, Table 2 gives the corresponding calculated values ​​for different modulation methods.

[0015] Step S2: Within the sideband common-mode voltage injection range of S1, calculate the frequency component of the sideband harmonic current with the largest amplitude after injection, and use the electromagnetic force generated by the sideband harmonic current under this common-mode injection condition as the vibration excitation source. Step S3: Set the operating conditions and sideband harmonic frequencies, and conduct a frequency sweep experiment in conjunction with the vibration excitation source in S2; Step S4: Analyze the data from the frequency sweep experiment in S3 and construct the original frequency response curve; Step S5: Correct the original frequency response curve of S4 according to the high-frequency electromagnetic force calculation function, and output the motor modal parameters.

[0016] In this embodiment, the correction process in step S5 is specifically a normalization process.

[0017] In some feasible embodiments, step S1 specifically includes: Injecting DC bias on top of SVPWM and the 3rd common-mode harmonic The principle of this common-mode voltage injection motor modulation method is referred to Figure 2 Reference value of injected common-mode voltage during switching cycle It can be written as: (1) In the formula, DC bias, The third common-mode modulation ratio, ω is the fundamental angular frequency.

[0018] The value range is determined by the adjustable range of the allocation ratio of SV0 and SV7 in SVPWM. Let the sum of the duty cycles of the SV0 and SV7 vectors be D. 07 It can be calculated as: (2) but The restricted range of values ​​is written as: (3) Analysis of six-sector D 07As can be seen from the expression, the effective vector duty cycle increases with the modulation ratio M, and the injected common-mode voltage increases. The smaller the value range, the better. SV0 and SV7 specifically refer to two zero vectors in SVPWM. Their core function is to adjust the output voltage amplitude and optimize the switching characteristics. They are key vectors for achieving continuously adjustable output voltage of a three-phase inverter.

[0019] For the six sectors of SVPWM, D1, D2, D3, D4, D5, D6, D7, D8, D9, D1, D9 ... h Relationship, D in the table sv1 -D sv6 This indicates the duty cycle of the effective vectors SV1-SV6 in SVPWM.

[0020] Table 1. Relationship between three-phase reference voltage and effective vector duty cycle in 6 sectors Define the maximum limit value as M lim As shown in equation (4): (4) Modulated wave expression after injection for: (5) In the formula, M is the modulation ratio.

[0021] By performing a double Fourier analysis on equation (5), the common-mode voltage injection condition is obtained. harmonic amplitude of frequency for: (6) (7) In the formula, m is the sideband coefficient, n is the baseband coefficient, and V dc q is the median value of the DC bus voltage. mn =m+n / N, where N is the carrier ratio, J k Let be the coefficients of the k-th order Bessel function, and , , The coefficients that vary with the sampling method are shown in Table 1: Table 2. Values ​​of α(ω), β(ω), and γ(ω) as a function of digital sampling method In some feasible embodiments, step S2 specifically includes: Establish a frequency domain model of the sideband electromagnetic force: (8) (9) In equation (8), L represents the inductance matrix.

[0022] Convert the three-phase voltage phasors and three-phase current phasors into rotating space vectors: (10) In the formula It is a voltage rotation space vector. It is the space vector of the rotating current.

[0023] Angular frequency in equation (8) Phase is The current amplitude is The sideband harmonic frequency component with the largest amplitude is selected by calculating using equations (8), (9), and (10). In this embodiment, as shown... Figures 3-6 As shown, the amplitudes of sideband harmonic currents at different frequencies after common-mode voltage injection under different operating conditions are presented. The gray area in the figure represents the value range of common-mode voltage injection M0 and M3, the red dots represent the current amplitude without common-mode voltage injection, and the highlighted point represents the maximum current amplitude after common-mode voltage injection. The electromagnetic force generated by this maximum current amplitude is taken as the electromagnetic force for frequency sweeping. It can be seen that under operating conditions of 360 rpm and 720 rpm, f... s The amplitude of the sideband harmonic current at frequency ±f1 is increased, thereby generating a larger electromagnetic force for frequency sweeping and mode identification. Therefore, in this embodiment, f is selected. s ±f1 serves as the intrinsic current excitation source, and its amplitude is adjusted to the maximum by adjusting the injection of M0 and M3, thereby achieving a better frequency sweep effect when the switching frequency changes.

[0024] The radial component F of the armature magnetomotive force of the sideband harmonic current it generates r and tangential component F t It can be represented as: (11) (12) In the formula, v is the spatial order of the armature magnetomotive force in the unit motor, and N t The number of unit motors is equal to the greatest common divisor of the number of pole pairs p and the number of slots z, θ is the mechanical rotation angle of the motor, and s n,v The direction of rotation of the armature magnetomotive force. This is the radial magnetomotive force amplitude coefficient. This is the amplitude coefficient of the tangential magnetomotive force.

[0025] For a permanent magnet, its magnetomotive force can be expressed as: (13) in, φ0 = π / 2 + δ is the amplitude of the u-th order spatial harmonic magnetomotive force of the permanent magnet, u = 1, 3, 5, ..., φ0 = π / 2 + δ is the initial phase of the fundamental magnetomotive force of the permanent magnet, and δ is the torque angle of the motor.

[0026] Assuming the air gap permeability is Λ0, the radial component σ of the sideband electromagnetic force density is obtained using Maxwell's stress tensor method. r With tangential component σ t They are respectively: (14) (15) By equating the electromagnetic force density to the concentrated electromagnetic force on the stator tooth surface, the radial concentrated electromagnetic force F can be obtained. r Tangential concentrated electromagnetic force F t Ignoring the equivalent resultant torque M z : (16) (17) In the formula, The effective length of the motor. Stator inner diameter The width angle of the stator tooth surface. For the first The position of the center line of each stator tooth.

[0027] The tangential concentrated electromagnetic force in the stator teeth also induces radial vibration in the stator yoke, which can be equivalent to the radial concentrated electromagnetic force in the stator yoke. It can be represented as: (18) In the formula The slot spacing is... For stator tooth height, The width of the stator yoke.

[0028] The tangential concentrated electromagnetic force is first equivalent to a tangential force acting on the center point of the yoke along the tooth centerline, and then equivalent to a pair of radial concentrated electromagnetic couples of equal magnitude and opposite direction acting on the stator yoke. .

[0029] According to the principle of mechanical equivalence, the tangential force can be completely equivalent to the radial force for calculation, i.e., equations (18) and (19).

[0030] Total radial concentrated electromagnetic force It can be represented as and sum: (19) The main high-frequency electromagnetic force components of the permanent magnet synchronous motor under the common-mode voltage injection condition can be obtained by equation (19), and this electromagnetic force can be used as the excitation source.

[0031] In this embodiment, the introduction of DC bias M0 results in odd-order sideband harmonics near odd-order subcarriers and even-order sideband harmonics near even-order subcarriers. Based on the sideband voltage harmonic amplitude calculation results, it can be considered that after injecting the common-mode component, the sideband harmonics are mainly concentrated in f. s ±4f1 and 2f s Within the range of ±4f1. Where f s This refers to the switching frequency.

[0032] With DC bias and the injection of the third common-mode harmonic, f s and 2f s The amplitudes of the major sideband harmonics in the vicinity change accordingly, and the variation patterns of the sideband harmonic amplitudes under M0 and M3 injections are inconsistent. Among them, DC bias injection affects f s ±f1、2f s The ±f1 frequency output voltage harmonics have a significant impact, while the injection of the 3rd common-mode harmonic has a greater impact on f. s ±2f1、2f s ±2f1 and 2f s The harmonic effects of the ±5f1 frequency output voltage are quite significant.

[0033] In some feasible embodiments, step S3 specifically includes: The switching frequency is increased from low to high in a specific step size. For the frequency range that may cause resonance, the step size can be appropriately reduced to perform a fine frequency sweep.

[0034] To facilitate the calculation of the vibration excitation source frequency and electromagnetic force, the rotational speed is fixed during the frequency sweep process. The selected fixed rotational speed should ensure that the amplitude of the sideband harmonic current near the vibration excitation source frequency is significant, so that the selected vibration excitation source can effectively excite high-frequency vibration.

[0035] Specifically, in this embodiment, a switching frequency f is selected. s and its multiplier 2f s Nearby frequencies.

[0036] During the frequency sweep experiment, it is necessary to record the experimental conditions to calculate the sideband harmonic current and high-frequency electromagnetic force; it is also necessary to record the corresponding data of the vibration excitation source frequency and the acceleration sensor at different switching frequencies so as to calculate the sideband harmonic current and high-frequency electromagnetic force offline later.

[0037] For a given switching frequency, frequency sweep from low to high frequency was achieved through common-mode voltage injection. Based on the acceleration data recorded in the previous experiment, a frequency-acceleration scatter plot can be plotted, and then the lines can be connected to form an acceleration-frequency response curve.

[0038] During the switching frequency change, the electromagnetic force is strengthened by common-mode voltage injection, which allows modes that might not have been excited to be expressed under a greater electromagnetic force.

[0039] In some feasible embodiments, step S4 specifically includes: After the frequency sweep experiment was completed, the collected data was first analyzed in depth using a vibration testing system.

[0040] Specifically, the acceleration frequency response curve corresponding to the vibration excitation source is accurately extracted, and the mode shape of the motor when resonance is induced by the vibration excitation source is accurately located. Since the deformation shape at the location where resonance is caused by the vibration excitation source is mainly dominated by a single resonant mode shape, the order information of the mode shape can be accurately obtained by using LMS working deformation mode analysis technology.

[0041] The overall process applied to the above method includes a high-frequency mode identification system for permanent magnet synchronous motors based on common-mode voltage injection, comprising: A vibration excitation determination unit is used to execute steps S1 and S2; The frequency sweep test unit is used to perform step S3; Vibration analysis unit, used to perform step S4; The identification unit is used to execute step S5.

[0042] The content of the above method embodiments is applicable to this system embodiment. The specific functions implemented in this system embodiment are the same as those in the above method embodiments, and the beneficial effects achieved are also the same as those achieved in the above method embodiments.

[0043] A high-frequency mode identification device for permanent magnet synchronous motors based on common-mode voltage injection: At least one processor; At least one memory for storing at least one program; When the at least one program is executed by the at least one processor, the at least one processor implements the high-frequency mode identification method for permanent magnet synchronous motors based on common-mode voltage injection as described above.

[0044] The content of the above method embodiments is applicable to the device embodiments. The specific functions implemented by the device embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0045] A storage medium storing processor-executable instructions, which, when executed by a processor, are used to implement the high-frequency mode identification method for permanent magnet synchronous motors based on common-mode voltage injection as described above.

[0046] The content of the above method embodiments is applicable to this storage medium embodiment. The specific functions implemented in this storage medium embodiment are the same as those in the above method embodiments, and the beneficial effects achieved are also the same as those achieved in the above method embodiments.

[0047] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A method for high-frequency mode identification of a permanent magnet synchronous motor based on common-mode voltage injection, characterized in that, Includes the following steps: Calculate the sideband common-mode voltage injection range based on the sideband harmonic voltage model; Within the range of the sideband common-mode voltage injection, the frequency component of the sideband harmonic current with the largest amplitude after injection is calculated, and the electromagnetic force generated by the sideband harmonic current under this common-mode injection condition is used as the vibration excitation source. Set the operating conditions and sideband harmonic frequencies, and conduct a frequency sweep experiment in conjunction with the vibration excitation source; The original frequency response curve was obtained by analyzing the data from the frequency sweep experiment. The original frequency response curve is corrected based on the high-frequency electromagnetic force calculation function, and the modal parameters of the motor are output.

2. The high-frequency mode identification method for permanent magnet synchronous motors based on common-mode voltage injection according to claim 1, characterized in that, The expression for the sideband common-mode voltage injection range is as follows: in, This represents the sum of the duty cycles of vectors SV0 and SV7. This represents the reference value of the injected common-mode voltage during the switching cycle. This indicates the effective vector duty cycle of the two-phase operation. Indicates the effective vector duty cycle of a single-phase operation. DC bias, The third common-mode modulation ratio, ω is the fundamental angular frequency.

3. The high-frequency mode identification method for permanent magnet synchronous motors based on common-mode voltage injection according to claim 2, characterized in that, The frequency component of the sideband harmonic current with the largest amplitude after injection is calculated according to the following formula: in, This indicates the amplitude of the injected sideband harmonic current. Represents the imaginary unit. Represents angular frequency. Represents the inductance matrix. Represents the phasor matrix of sideband harmonic currents. Indicates a time step. These represent the voltage phasors of phases A, B, and C, respectively. These represent the current phasors of phases A, B, and C, respectively. Indicates the transpose symbol. Represents the voltage rotation space vector. This represents the space vector of the rotating current.

4. The high-frequency mode identification method for permanent magnet synchronous motors based on common-mode voltage injection according to claim 2, characterized in that, The formula for calculating the electromagnetic force is as follows: in, This represents the total radial concentrated electromagnetic force. Indicates radially concentrated electromagnetic force. Indicates a radially concentrated electromagnetic couple. The slot spacing is... For stator tooth height, For the stator yoke width, The effective length of the motor. Stator inner diameter The width angle of the stator tooth surface. For the first The position of the center line of each stator tooth Represents the radial component of the sideband electromagnetic force density. This represents the tangential component of the sideband electromagnetic force density.

5. The high-frequency mode identification method for permanent magnet synchronous motors based on common-mode voltage injection according to claim 4, characterized in that, The step of setting the operating conditions and sideband harmonic frequencies, and conducting a frequency sweep experiment in conjunction with the vibration excitation source, specifically includes: With a fixed rotation speed, the switching frequency is increased from low to high in specific steps, and the sideband harmonic frequency is set according to the switching frequency. Combined with the vibration excitation source, a frequency sweep experiment is performed. Record the operating conditions and data of the frequency sweep experiment.

6. The high-frequency mode identification method for permanent magnet synchronous motors based on common-mode voltage injection according to claim 5, characterized in that, The step of analyzing the data from the frequency sweep experiment to obtain the original frequency response curve specifically includes: Extract the acceleration frequency response curve corresponding to the vibration excitation source; The mode shape of a positioning motor when it resonates under the action of a vibration excitation source.

7. The high-frequency mode identification method for permanent magnet synchronous motors based on common-mode voltage injection according to claim 6, characterized in that, The step of correcting the original frequency response curve based on the high-frequency electromagnetic force calculation function and outputting the motor's modal parameters specifically includes: The calculated results of the high-frequency electromagnetic force are fitted with the original frequency response curve of the corresponding vibration excitation source to obtain the corrected frequency response curve. Based on the corrected frequency response curve, the modal parameters of the motor are generated.

8. A high-frequency mode identification system for permanent magnet synchronous motors based on common-mode voltage injection, characterized in that, include: The vibration excitation determination unit is used to calculate the sideband common-mode voltage injection range based on the sideband harmonic voltage model. Within the range of the sideband common-mode voltage injection, the frequency component of the sideband harmonic current with the largest amplitude after injection is calculated, and the electromagnetic force generated by the sideband harmonic current under this common-mode injection condition is used as the vibration excitation source. The frequency sweep test unit sets the operating conditions and sideband harmonic frequencies, and performs a frequency sweep test in conjunction with the vibration excitation source. The vibration analysis unit is used to analyze the data from the frequency sweep experiment to obtain the original frequency response curve; The identification unit is used to correct the original frequency response curve according to the high-frequency electromagnetic force calculation function and output the motor's modal parameters.

9. A high-frequency mode identification device for permanent magnet synchronous motors based on common-mode voltage injection, characterized in that, include: At least one processor; At least one memory for storing at least one program; When the at least one program is executed by the at least one processor, the at least one processor implements the high-frequency mode identification method for permanent magnet synchronous motors based on common-mode voltage injection as described in any one of claims 1-7.

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