Harmonic evaluation method and device, electronic equipment and storage medium

Abstract

The invention provides a harmonic evaluation method and device, electronic equipment and a storage medium, and the method comprises the steps: constructing a mathematical model of a fundamental component of a modulation signal in a process of generating a PWM signal through natural sampling triangular carrier modulation; based on the mathematical model of the fundamental component, obtaining a harmonic component of the PWM signal; extracting features in the harmonic component, wherein the features comprise an amplitude, an initial phase angle and an angular frequency in the harmonic component; and obtaining the average amplitude of the harmonic component at different initial phase angles, and obtaining the total harmonic distortion rate of the PWM signal based on the average amplitude. According to the method, more accurate performance evaluation can be carried out on the harmonic waves in the natural sampling triangular carrier wave modulation process under the condition of harmonic wave disturbance.

Description

Technical Field

[0001] The present invention relates to the technical field of PWM modulation, and in particular, to a harmonic evaluation method, device, electronic device, and storage medium. Background Art

[0002] With the energy revolution and technological progress, the power electronic distribution network has become a key trend in the development of the power system. The PWM generated by power electronic converters such as new energy grid-connected inverters and electric vehicle chargers has non-linear characteristics, resulting in a large amount of harmonics in the output current, which has become the main source of harmonic pollution in the distribution network. In addition, broadband harmonics such as background harmonics in the distribution network and switching sub-harmonics of power electronic devices enter the control system after voltage and current sampling, and are transmitted to the PWM module through the control link, generating secondary sideband harmonics related to the frequency of the disturbance harmonics, which exacerbates harmonic pollution.

[0003] THD (Total Harmonic Distortion) is used to measure the harmonic performance. Currently, the harmonic performance analysis under natural sampling triangular carrier modulation is mainly based on the WTHD (Weighted Total Harmonic Distortion) index. Among them, natural sampling compares a sine wave as the modulation signal (also called the reference signal) with a sawtooth wave as the carrier, and controls the on-off of the switch at the natural intersection moments of the two waveforms. The phase angles of each harmonic component are affected differently by the sideband coefficients, resulting in the total amplitude of the superimposed harmonic components being affected by the fundamental wave, harmonic disturbance, and the initial phase angle of the carrier signal. Therefore, the WTHD of the PWM modulation output waveform under different initial phase angles is not unique, and thus it is difficult to use it to compare the harmonic emission levels of different PWM modulation strategies. Summary of the Invention

[0004] In view of the above deficiencies of the prior art, the present invention provides a harmonic evaluation method, device, electronic device, and storage medium for more accurately evaluating the harmonic performance during natural sampling triangular carrier modulation under harmonic disturbance conditions.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a harmonic evaluation method, including:

[0007] Construct a mathematical model of the fundamental wave component of the modulation signal during the process of generating a PWM signal by natural sampling triangular carrier modulation;

[0008] Based on the mathematical model of the fundamental wave component, obtain the harmonic components of the PWM signal;

[0009] Extract the features in the harmonic components, where the features include the amplitude, initial phase angle, and angular frequency in the harmonic components;

[0010] Obtain the average amplitude of the harmonic components at different initial phase angles, and obtain the total harmonic distortion rate of the PWM signal based on the average amplitude.

[0011] Further, the expression of the mathematical model of the fundamental wave component is as follows:

[0012]

[0013] where f(t) represents the modulation signal of natural sampling, r(ω s t) represents the carrier signal, p(t) represents the PWM signal generated after comparing the modulation signal with the carrier signal, ω s represents the switching frequency, and T c represents the switching period;

[0014] The formula of the carrier signal r(ω s t) is:

[0015] Further, the obtaining of the harmonic components of the PWM signal includes:

[0016] When there is harmonic disturbance, set f(t) and r(w s t) as: r(ω s t) = f(t) = A0cos(ω0t + θ0) + A1cos(ω1t + θ1)

[0017] where A0, ω0, and θ0 respectively represent the amplitude, angular frequency, and initial phase angle of the fundamental wave component, A1, ω1, and θ1 respectively represent the amplitude, angular frequency, and initial phase angle of the disturbance harmonic component in the modulation signal, and the Fourier series expansion of the carrier signal r(ω s t) is:

[0018]

[0019] where n c represents the carrier frequency sideband coefficient, and ω c represents the carrier angular frequency;

[0020] According to the above formula, the Fourier series form of the PWM signal p(t) is obtained as:

[0021]

[0022] Substitute the set f(t) and r(ω s t) into the above formula and perform Jacobi-Anger expansion, and the expression of the harmonic components of the PWM signal p(t) is obtained as:

[0023]

[0024] Wherein:

[0025] ω x t = n0ω0 + n1ω1 + n c ω c

[0026] θ x = n0θ0 + n1θ1 + n c θ c

[0027] J n is the first kind of Bessel function, n0 is the fundamental frequency sideband coefficient, and n p is the harmonic component frequency sideband coefficient.

[0028] Furthermore, extracting the features in the harmonic components includes:

[0029] Decompose the expression of the harmonic components of the PWM signal p(t) to obtain the amplitude, initial phase angle, and angular frequency in the harmonic components.

[0030] Furthermore, obtaining the average amplitude at different initial phase angles of the harmonic components includes: Using the carrier signals at different initial phase angles as references, taking the initial phase angles of the fundamental component and harmonic components of the modulation signal as variables, calculating the harmonic component P n (θ0, θ1) of the nth PWM signal, and then calculating the average amplitude M n :

[0031]

[0032] where K is the step size of the initial phase angle θ0 of the fundamental component and the initial phase angle θ1 of the harmonic component, and the value range is 0 to 2π.

[0033] Furthermore, obtaining the total harmonic distortion rate of the PWM signal based on the average amplitude includes calculating the total harmonic distortion rate E NTHD :

[0034]

[0035] where M1 is the average amplitude at different initial phase angles of the fundamental component.

[0036] In a second aspect, the present invention provides a harmonic evaluation system, including:

[0037] A model construction module for constructing a mathematical model of the fundamental component of the modulation signal in the process of generating a PWM signal by natural sampling triangular carrier modulation;

[0038] A harmonic extraction module, configured to obtain harmonic components of the PWM signal based on a mathematical model of the fundamental wave component;

[0039] A feature extraction module, configured to extract features from the harmonic components, where the features include the amplitude, initial phase angle, and angular frequency in the harmonic components;

[0040] A harmonic evaluation module, configured to obtain an average amplitude of the harmonic components at different initial phase angles, and obtain a total harmonic distortion rate of the PWM signal based on the average amplitude.

[0041] Further, the expression of the mathematical model of the fundamental wave component is as follows:

[0042]

[0043] where f(t) represents a naturally sampled modulation signal, r(ω s t) represents a carrier signal, p(t) represents a PWM signal generated after comparing the modulation signal with the carrier signal, ω s represents a switching frequency, and T c represents a switching period;

[0044] The formula of the carrier signal r(ω s t) is:

[0045] In a third aspect, the present invention provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. Wherein, when the processor executes the computer program, the steps of the harmonic evaluation method as described above are implemented.

[0046] In a fourth aspect, the present invention provides a computer-readable storage medium, on which a computer program is stored. Wherein, when the computer program is executed by a processor, the steps of the harmonic evaluation as described above are implemented.

[0047] Due to the above technical solutions, the present invention has the following advantages and positive effects compared with the prior art:

[0048] By modeling the harmonics under natural sampling triangular carrier modulation and specifically analyzing the harmonic components therein, the present invention obtains characteristic values such as the amplitude, angular frequency, and initial phase angle of the disturbing harmonic components therein, and then calculates the average amplitude of the harmonic components at different initial phase angles, and evaluates the total harmonic distortion rate based on the average amplitude, overcoming the non-uniqueness brought by the strong randomness of the harmonic initial phase angle in the traditional evaluation criteria, and providing a more practical and valuable reference basis. Description of the Drawings

[0049] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those skilled in the art, without creative efforts, relevant information can also be obtained based on these drawings.

[0050] Figure 1 is a flowchart of a harmonic evaluation method of the present invention;

[0051] Figure 2 is a hardware simulation test diagram of the present invention;

[0052] Figure 3 is a hardware architecture diagram of an electronic device of the present invention. Specific Embodiments

[0053] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0054] The terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The singular forms "a", "the" and "said" used in the present disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0055] In an actual industrial scenario, for natural sampling triangular carrier modulation, a one-dimensional spectrum analysis method is usually used to extend it from single-frequency modulation based on the fundamental component to multi-frequency modulation with the fundamental component superimposed by harmonic perturbations, and a mathematical model for sideband harmonic analysis of the output PWM waveform of natural sampling triangular wave modulation applicable to classical two-level PWM under the action of arbitrary harmonic perturbations is established.

[0056] For natural sampling triangular carrier PWM modulation, its output pulse signal can be formed by combining the output signals of the leading-edge sawtooth carrier modulation and the trailing-edge sawtooth carrier modulation within the switching period.

[0057] In the one-dimensional spectrum analysis method, by using the mathematical tools of Fourier series expansion and Jacobi-Anger expansion, the specific expressions of the harmonic components of the output signal of natural sampling triangular carrier PWM modulation can be calculated. After obtaining the specific expressions, since the corresponding phase angles of the harmonic components at each frequency are affected differently by the sideband coefficients, the magnitude of the total amplitude of the superimposed harmonic components depends not only on each sideband coefficient, but also on the fundamental wave, harmonic disturbance, and the initial phase angle of the carrier signal. Therefore, the WTHD values of the PWM modulation output waveforms under different initial phase angle conditions are not unique, making it difficult to use for comparing the harmonic emission levels of different PWM modulation strategies.

[0058] In other words, when the power electronic converter operates, the initial phase angle of the carrier signal has strong randomness, and the existing WTHD index is difficult to comprehensively evaluate the harmonic distortion of the PWM modulation strategy under the influence of harmonic disturbance. To overcome this defect, the present invention provides a harmonic evaluation method, device, electronic device, and storage medium for providing an improved total harmonic distortion rate (NTHD) index to evaluate the total harmonic distortion rate during the natural sampling triangular carrier modulation under harmonic disturbance.

[0059] Embodiment 1

[0060] This embodiment provides a harmonic evaluation method for evaluating the harmonic performance of a power electronic converter. As Figure 1 shown, the method specifically includes the following steps:

[0061] S1, Model construction: Construct a mathematical model of the fundamental wave component of the modulation signal during the process of generating a PWM signal by natural sampling triangular carrier modulation.

[0062] Specifically, for the natural sampling triangular carrier modulation in the classical two-level PWM modulation, a mathematical model of the fundamental wave component in its reference signal (i.e., the adjusted modulation signal) is established under the condition of harmonic disturbance.

[0063] S2, Obtain harmonic components: Based on the mathematical model of the fundamental wave component, obtain the harmonic components of the PWM signal.

[0064] Specifically, in this embodiment, the harmonic components can be obtained by mathematical methods. The pulse signal is formed by combining the output signals of the front-edge sawtooth carrier modulation and the rear-edge sawtooth carrier modulation, and the harmonic components of the PWM can be obtained more accurately for harmonic analysis.

[0065] S3, Feature analysis: Extract the features in the harmonic components, where the features include the amplitude, initial phase angle, and angular frequency in the harmonic components.

[0066] S4, Harmonic evaluation: Obtain the average amplitude of the harmonic components at different initial phase angles, and obtain the total harmonic distortion rate of the PWM signal based on the average amplitude.

[0067] Specifically, since the total amplitude of the superimposed harmonic components is affected by the initial phase angle of the carrier signal, obtaining the total harmonic distortion rate of the PWM signal based on the average amplitude at different initial phase angles can avoid the non-uniqueness of WTHD caused by the initial phase angle problem and improve its comprehensive accuracy.

[0068] In step S1, the mathematical model expression of the fundamental wave component constructed is:

[0069]

[0070] where f(t) represents the naturally sampled modulation signal, r(ω s t) represents the carrier signal, p(t) represents the PWM pulse signal after comparing the modulation signal and the carrier signal, ω s represents the switching frequency, and T c represents the switching period.

[0071] where the specific formula of the carrier signal r(ω s t) is:

[0072]

[0073] In step S2, the harmonic components are specifically obtained through the following steps:

[0074] S21: When there is harmonic disturbance in the PWM reference signal, set f(t) and r(w s t) as:

[0075] r(ω s t) = f(t) = A0cos(ω0t + θ0) + A1cos(ω1t + θ1)

[0076] where A0, ω0, and θ0 are respectively the amplitude, angular frequency, and initial phase angle of the fundamental wave component, and A1, ω1, and θ1 are respectively the amplitude, angular frequency, and initial phase angle of the disturbance harmonic component in the modulation signal.

[0077] The Fourier series expansion of the sawtooth carrier signal r(ω s t) is:

[0078]

[0079] where n c represents the carrier frequency sideband coefficient; ω c represents the carrier angular frequency.

[0080] S22: Consider the carrier wave of the natural sampling triangular carrier wave modulation method as the combined output signal of the front-edge sawtooth carrier wave modulation and the back-edge sawtooth carrier wave modulation. Then, according to the above formula, the Fourier series form of p(t) can be obtained:

[0081]

[0082] S23: Substitute the set f(t) and r(ω s t) into the above formula. After performing the Jacobi-Anger expansion, obtain the expression of the harmonic components of the output PWM signal p(t):

[0083]

[0084] where J n is the Bessel function of the first kind; n0 is the fundamental frequency sideband coefficient; n p is the perturbation harmonic frequency sideband coefficient.

[0085] In step S3, when analyzing the characteristics of the harmonic components, decompose the above expression of the harmonic components of p(t) to obtain the amplitude, initial phase angle, and angular frequency in the harmonic components, where:

[0086] ω x t = n0ω0 + n1ω1 + n c ω c

[0087] θ x = n0θ0 + n1θ1 + n c θ c

[0088] In the process of obtaining the total harmonic distortion rate in step S4, first, take the carrier signals with different initial phase angles as references, use the initial phase angles of the fundamental component and the harmonic perturbation component of the modulation signal as variables, calculate the nth harmonic component P n (θ0, θ1) of the PWM signal, then calculate the average amplitude M n of the harmonic components of the PWM signal under different initial phase angle conditions, and based on this average amplitude M n calculate the total harmonic distortion rate E NTHD of the PWM signal, which can be called the improved total harmonic distortion rate, thereby compensating for the non-uniqueness of WTHD caused by the strong randomness of the initial phase angle. The specific calculation formula is as follows:

[0089]

[0090] Wherein, K is the step size of the fundamental initial phase angle θ0 and the harmonic disturbance initial phase angle θ1 of the modulation signal, and its value range is 0 to 2π; M1 is the average amplitude of the fundamental component of the PWM signal under different initial phase angles. In the formula, the average amplitude of the harmonics under different initial phase angles is used as the calculated amplitude, which makes up for the disadvantages brought by the non-uniqueness of the total harmonic distortion rate of the output waveform of PWM modulation under different initial phase angles.

[0091] In this embodiment, considering the strong random characteristics of the initial phase angles of the fundamental wave and harmonic disturbance frequency components in the modulation signal of the power electronic converter controller under the influence of harmonic disturbance, the proposed NTHD index performs an average process by comprehensively considering the sideband harmonic amplitudes under different initial phase angle conditions. Compared with the traditional WTHD index, it has more practical significance in comprehensively evaluating the sideband harmonic performance of different PWM methods.

[0092] The implementation process of the present invention covers the entire process from modeling, processing functions, data analysis to index optimization. Its innovative detection and data indicators can effectively cope with the complex and multi-line power electronic distribution network environment, realizing the rationality and effectiveness of harmonic analysis, and has broad industrial application prospects. The present invention has feasibility and superiority.

[0093] Embodiment 2

[0094] This embodiment provides a harmonic evaluation system, which includes: a model construction module for constructing a mathematical model of the fundamental component of the modulation signal in the process of generating a PWM signal by natural sampling triangular carrier modulation; a harmonic extraction module for obtaining the harmonic components of the PWM signal based on the mathematical model of the fundamental component; a feature extraction module for extracting features in the harmonic components, and the features include the amplitude, initial phase angle and angular frequency in the harmonic components; a harmonic evaluation module for obtaining the average amplitude of the harmonic components under different initial phase angles, and obtaining the total harmonic distortion rate of the PWM signal based on the average amplitude.

[0095] In an implementable manner, the expression of the mathematical model of the fundamental component is as follows:

[0096]

[0097] Wherein, f(t) represents the modulation signal of natural sampling, r(ω s t) represents the carrier signal, p(t) represents the PWM signal generated after comparing the modulation signal with the carrier signal, ω s represents the switching frequency, and T c represents the switching period;

[0098] The formula of the carrier signal r(ω s t) is:

[0099] In an implementable manner, obtaining the harmonic components of the PWM signal includes:

[0100] When there is harmonic disturbance, set f(t) and r(ω s t) as: r(ω s t) = f(t) = A0cos(ω0t + θ0) + A1cos(ω1t + θ1), where A0, ω0, and θ0 respectively represent the amplitude, angular frequency, and initial phase angle of the fundamental wave component, and A1, ω1, and θ1 respectively represent the amplitude, angular frequency, and initial phase angle of the disturbance harmonic component in the modulation signal, and the Fourier series expansion of the carrier signal r(ω s t) is:

[0101]

[0102] where n c represents the carrier frequency sideband coefficient, and ω c represents the carrier angular frequency;

[0103] According to the above formula, the Fourier series form of the PWM signal p(t) is obtained as:

[0104]

[0105] Substitute the set f(t) and r(ω s t) into the above formula and perform Jacobi-Anger expansion, and the expression of the harmonic components of the PWM signal p(t) is obtained as:

[0106]

[0107] where:

[0108] ω x t = n0ω0 + n1ω1 + n c ω c

[0109] θ x = n0θ0 + n1θ1 + n c θ c

[0110] J n is the Bessel function of the first kind, n0 is the fundamental wave frequency sideband coefficient, and n p is the harmonic component frequency sideband coefficient.

[0111] In an implementable manner, extracting the features in the harmonic components includes:

[0112] Decompose the expression of the harmonic components of the PWM signal p(t) to obtain the amplitude, initial phase angle, and angular frequency in the harmonic components.

[0113] In an implementable manner, obtaining the average amplitude at different initial phase angles of the harmonic components includes: using the carrier signals at different initial phase angles as references, taking the initial phase angles of the fundamental wave component and the harmonic components of the modulation signal as variables, calculating to obtain the nth harmonic component P of the PWM signal n (θ0, θ1), and then calculating the average amplitude M of this harmonic component at different initial phase angles n :

[0114]

[0115] where K is the step size of the initial phase angles θ0 of the fundamental wave component and θ1 of the harmonic components of the modulation signal, and the value range is 0 to 2π.

[0116] In an implementable manner, obtaining the total harmonic distortion rate of the PWM signal based on the average amplitude includes calculating the total harmonic distortion rate E according to the following formula NTHD :

[0117]

[0118] where M1 is the average amplitude of the fundamental wave component of the PWM signal at different initial phase angles.

[0119] In this embodiment, by performing harmonic modeling on natural sampling triangular carrier modulation and specifically analyzing the harmonic components therein, characteristic values such as the amplitude, angular frequency, and initial phase angle of the disturbance harmonic components are obtained. Then, the average amplitude of the harmonic components at different initial phase angles is calculated, and based on this average amplitude, the total harmonic distortion rate is evaluated, overcoming the non-uniqueness brought by the strong randomness of the harmonic initial phase angle in the traditional evaluation criteria, and providing a more practical and valuable reference basis.

[0120] Embodiment 3

[0121] This embodiment provides a controller for a power electronic converter. The controller includes a harmonic evaluation system provided in Embodiment 2 to be used for evaluating the voltage harmonics output by the power electronic converter and performing feedback control on the power electronic converter according to the evaluation results. In addition, Figure 2 it also provides an inverter system topology for detecting the above evaluation system, such as Figure 2 shown, this structure includes four switching tubes T1 to T4 and corresponding four freewheeling diodes. The voltage u output after inverter filtering AB is an AC voltage and can be used to evaluate voltage harmonics.

[0122] Embodiment 4

[0123] This embodiment provides an electronic device, which can be presented in the form of a computing device (for example, it can be a server device), including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the harmonic evaluation method provided in Embodiment 1 can be implemented.

[0124] Figure 3 The schematic diagram of the hardware structure of this embodiment is shown, as Figure 3 shown, the electronic device 30 specifically includes:

[0125] At least one processor 31, at least one memory 32, and a bus 33 for connecting different system components (including the processor 31 and the memory 32), where:

[0126] The bus 33 includes a data bus, an address bus, and a control bus.

[0127] The memory 32 includes volatile memory, such as random access memory (RAM) 321 and / or cache memory 322, and may further include read-only memory (ROM) 323.

[0128] The memory 32 further includes a program / utility 325 having a set (at least one) of program modules 324. Such program modules 324 include, but are not limited to: an operating system, one or more application programs, other program modules, and program data. Each or some combination of these examples may include the implementation of a network environment.

[0129] The processor 31 executes various functional applications and data processing by running the computer program stored in the memory 32, such as the steps of the harmonic evaluation method provided in Embodiment 1 of the present invention.

[0130] The electronic device 30 can further communicate with one or more external devices 34 (such as a keyboard, a pointing device, etc.). Such communication can be carried out through an input / output (I / O) interface 35. And, the electronic device 30 can also communicate with one or more networks (such as a local area network (LAN), a wide area network (WAN), and / or a public network, such as the Internet) through a network adapter 36. The network adapter 36 communicates with other modules of the electronic device 30 through the bus 33. It should be understood that, although not shown in the figure, other hardware and / or software modules can be used in combination with the electronic device 30, including but not limited to: microcode, device drivers, redundant processors, external disk drive arrays, RAID (disk array) systems, tape drives, and data backup storage systems, etc.

[0131] It should be noted that although several units / modules or sub-units / modules of the electronic device are mentioned in the above detailed description, this division is merely exemplary and not mandatory. In fact, according to the embodiments of the present application, the features and functions of two or more units / modules described above can be embodied in one unit / modules. Conversely, the features and functions of one unit / modules described above can be further divided and embodied by multiple units / modules.

[0132] Embodiment 5

[0133] This embodiment provides a computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the steps of the harmonic evaluation method provided in Embodiment 1 are implemented.

[0134] Among them, the more specific computer-readable storage medium that can be adopted may include but is not limited to: portable disks, hard disks, random access memories, read-only memories, erasable programmable read-only memories, optical storage devices, magnetic storage devices, or any suitable combination of the above.

[0135] In a possible implementation manner, the present invention can also be implemented in the form of a program product, which includes program code. When the program product runs on a terminal device, the program code is used to cause the terminal device to execute the steps of the harmonic evaluation method provided in Embodiment 1.

[0136] Among them, the program code for executing the present invention can be written in any combination of one or more programming languages, and the program code can be executed entirely on the user device, partially on the user device, executed as an independent software package, partially on the user device and partially on a remote device, or entirely on a remote device.

[0137] Although the specific implementation manners of the present invention are described above, those skilled in the art should understand that this is only an example, and the protection scope of the present invention is defined by the appended claims. Without departing from the principles and essence of the present invention, those skilled in the art can make various changes or modifications to these implementation manners, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A harmonic evaluation method, characterized in that, Including: Constructing a mathematical model of the fundamental component of the modulation signal during the process of generating a PWM signal by natural sampling triangular carrier modulation; Obtaining the harmonic components of the PWM signal based on the mathematical model of the fundamental component; Extracting the features in the harmonic components, where the features include the amplitude, initial phase angle, and angular frequency in the harmonic components; Obtaining the average amplitude of the harmonic components at different initial phase angles, and obtaining the total harmonic distortion rate of the PWM signal based on the average amplitude.

2. The harmonic evaluation method according to claim 1, wherein The expression of the mathematical model of the fundamental component is as follows: Among them, f(t) represents the modulated signal of natural sampling, r(ω s t) represents the carrier signal, p(t) represents the PWM signal generated after comparing the modulated signal with the carrier signal, ω s represents the switching frequency, T c represents the switching period; The carrier signal r(ω s t) is:

3. The harmonic evaluation method according to claim 2, wherein The obtaining of the harmonic components of the PWM signal includes: When there is a harmonic disturbance, set f(t) and r(w s t) as: r(ω s t) = f(t) = A0cos(ω0t + θ0) + A1cos(ω1t + θ1) wherein, A0, ω0, and θ0 respectively represent the amplitude, angular frequency, and initial phase angle of the fundamental wave component, and A1, ω1, and θ1 respectively represent the amplitude, angular frequency, and initial phase angle of the disturbance harmonic component in the modulation signal, and the Fourier series expansion of the carrier signal r(ω s t) is: Among them, n c represents the carrier frequency sideband coefficient, and ω c represents the carrier angular frequency; According to the above formula, the Fourier series form of the PWM signal p(t) is obtained as: Substitute the set f(t) and r(ω s t) into the above formula and perform Jacobi-Anger expansion, and the expression of the harmonic component of the PWM signal p(t) is obtained as follows: Where: ω x t = n0ω0 + n1ω1 + n c ω c θ x = n0θ0 + n1θ1 + n c θ c J n is the first kind of Bessel function, n0 is the fundamental frequency sideband coefficient, and n p is the harmonic component frequency sideband coefficient.

4. The harmonic evaluation method according to claim 3, characterized in that The extracting of the features in the harmonic components includes: decomposing the expression of the harmonic components of the PWM signal p(t) to obtain the amplitude, initial phase angle, and angular frequency in the harmonic components.

5. The harmonic evaluation method according to claim 4, wherein Obtaining the average amplitude at different initial phase angles of the harmonic component includes: using the carrier signals at different initial phase angles as references, taking the initial phase angles of the fundamental wave component and the harmonic component of the modulation signal as variables, and calculating the harmonic component P of the nth PWM signal n (θ0, θ1), and then calculating the average amplitude M at different initial phase angles of the harmonic component n : Where K is the step size of the initial phase angle θ0 of the fundamental component and the initial phase angle θ1 of the harmonic component, and the value range is 0 to 2π.

6. The harmonic evaluation method according to claim 5, wherein Obtaining the total harmonic distortion rate of the PWM signal based on the average amplitude includes calculating the total harmonic distortion rate E according to the following formula NTHD :[[]]END]] Where M1 is the average amplitude of the fundamental component at different initial phase angles.

7. A harmonic evaluation system, characterized in that, Including: A model construction module for constructing a mathematical model of the fundamental component of the modulation signal during the process of generating a PWM signal by natural sampling triangular carrier modulation; A harmonic extraction module for obtaining the harmonic components of the PWM signal based on the mathematical model of the fundamental component; A feature extraction module for extracting the features in the harmonic components, where the features include the amplitude, initial phase angle, and angular frequency in the harmonic components; A harmonic evaluation module for obtaining the average amplitude of the harmonic components at different initial phase angles, and obtaining the total harmonic distortion rate of the PWM signal based on the average amplitude.

8. The harmonic evaluation system according to claim 7, wherein The expression of the mathematical model of the fundamental component is as follows: Among them, f(t) represents the modulated signal of natural sampling, r(ω s t) represents the carrier signal, p(t) represents the PWM signal generated after comparing the modulated signal with the carrier signal, ω s represents the switching frequency, T c represents the switching period; The carrier signal r(ω s t) is:

9. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and capable of running on the processor, characterized in that When the processor executes the computer program, it implements the steps of the harmonic evaluation method according to any one of claims 1-5.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the harmonic evaluation method according to any one of claims 1 to 5.

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