Modeling method of variable frequency motor system, electronic equipment and medium

Abstract

The invention provides a modeling method of a variable frequency motor system, electronic equipment and a medium, high-frequency line element characteristic parameters of a cable are calculated and identified through a finite element method, high-frequency characteristic parameters of a variable frequency motor are obtained through extraction of a common-mode impedance characteristic curve and a differential-mode impedance characteristic curve, and a variable frequency motor system model is constructed. Factors such as electrical parameter changes of the variable frequency motor system can be captured, the problems that high-frequency characteristic parameters of an existing variable frequency motor system cannot be measured in real time, modeling of a single device is inaccurate and the like are solved, and the modeling accuracy of the variable frequency motor system is improved.

Description

Technical Field

[0001] The present invention belongs to the field of motor systems, and in particular relates to a modeling method, electronic equipment and medium for a variable frequency motor system. Background Art

[0002] The inverter-driven variable-frequency motor faces the problem of voltage surge at the machine end during operation, which seriously threatens the insulation performance of the motor, may cause equipment failure, and affect the stability and reliability of the system. In order to effectively solve the voltage surge problem faced by the inverter-driven variable-frequency motor during operation, a modeling method for variable-frequency motors and motor cables is needed to accurately and comprehensively describe the various influencing factors in the system. Traditional cables are usually ignored or modeled as a simple concentrated parameter combination model of resistance, inductance and capacitance during modeling. The simplified model cannot fully consider the nonlinearity and high-frequency behavior of the cable, and it is difficult to accurately predict the distortion and attenuation of the signal during cable propagation. For complex cable systems, the parameterization and verification of the model requires a large amount of experimental data, but these data are difficult to obtain, which greatly reduces the accuracy of the cable model. Traditional variable-frequency motors usually use stator-rotor loop equivalent circuit models to describe their electrical characteristics, but they cannot accurately capture the high-frequency characteristics of variable-frequency motors. Especially for high-performance applications, more complex models are required to consider effects such as magnetic saturation and core loss, which increases the complexity of modeling. In existing research, high-frequency modeling of cables and motors is mostly separate, and does not take into account the switching characteristics of power devices, changes in electrical parameters of cable motor systems, and dynamic changes in motor load characteristics. This is insufficient to provide reliable technical support for variable frequency motor system design, maintenance, and insulation protection strategies. Summary of the invention

[0003] The purpose of the present invention is to address the deficiencies in the prior art and provide a modeling method, electronic equipment and medium based on a variable frequency motor system, which can be used for modeling a variable frequency motor system and improve the accuracy of modeling a variable frequency motor system.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] A modeling method for a variable frequency motor system includes the following steps:

[0006] Build a high-frequency pulse module;

[0007] According to the length, cross-sectional area and material parameters of the cable, the finite element method is used to calculate the cable high-frequency line element characteristic parameters, wherein the cable high-frequency line element characteristic parameters include the cable unit length capacitance, the cable unit length inductance and the cable unit length resistance; according to the cable high-frequency line element characteristic parameters, an equivalent circuit model of the cable characteristic parameters is constructed;

[0008] The common-mode impedance is calculated according to the common-mode voltage and common-mode current of the variable-frequency motor measured in real time to obtain a common-mode impedance characteristic curve; the differential-mode impedance is calculated according to the differential-mode voltage and differential-mode current of the variable-frequency motor measured in real time to obtain a differential-mode impedance characteristic curve; a plurality of characteristic values ​​are extracted from the common-mode impedance characteristic curve and the differential-mode impedance characteristic curve, and characteristic parameters of the variable-frequency motor are obtained by calculating the characteristic values, wherein the characteristic parameters of the variable-frequency motor include the surface resistance R of the motor winding. s , motor winding turn-to-turn inductance L w , motor winding interturn capacitance C w , stator winding leakage inductance L s , stator high frequency iron loss R e , parasitic resistance R between stator winding and motor frame sf , parasitic capacitance C between stator winding and motor frame sf , parasitic resistance R between the stator neutral point and the motor frame g , parasitic capacitance C between the stator neutral point and the motor frame g , machine-side slew capacitor C comp ; According to the variable frequency motor characteristic parameters, an equivalent circuit model of the variable frequency motor characteristic parameters is constructed;

[0009] The characteristic value includes the impedance amplitude Z at the first minimum value Z1 of the common mode impedance characteristic curve z1 and the resonant frequency f z1 , the capacitance value C corresponding to C1 in the low-frequency band on the left side of the first minimum value Z1 of the common-mode impedance characteristic curve a , the capacitance value C corresponding to C2 in the high frequency band on the right side of the first minimum value Z1 of the common mode impedance characteristic curve HF ; Impedance amplitude Z at the first maximum value P of the differential mode impedance characteristic curve P , the impedance amplitude Z at the first minimum Z2 of the differential mode impedance characteristic curve Z2 , impedance angle θ z2 and the resonant frequency f z2 , the impedance amplitude Z at the second minimum Z3 of the differential mode impedance characteristic curve Z3 , the first maximum value P of the differential mode impedance characteristic curve and the inductance value L at the midpoint L1 of the starting frequency DM and the resonant frequency f L1 ;

[0010] The expression for calculating the characteristic parameters of the variable frequency motor through the characteristic value is as follows:

[0011]

[0012] R e =3|Z P |

[0013] Rsf =3|Z Z3 |

[0014]

[0015]

[0016] R s =|Z Z2 |cos(θ z2 )

[0017] The high-frequency pulse module, the cable characteristic parameter equivalent circuit model, and the variable frequency motor characteristic parameter equivalent circuit model are connected to construct a variable frequency motor system model; the output end of the high-frequency pulse module is connected to the first end of the cable characteristic parameter equivalent circuit model, and the second end of the cable characteristic parameter equivalent circuit model is connected to the input end of the variable frequency motor characteristic parameter equivalent circuit model.

[0018] The present invention calculates and identifies the characteristic parameters of the high-frequency line elements of the cable, obtains the high-frequency characteristic parameters of the variable-frequency motor through common-mode impedance characteristic curves and differential-mode impedance characteristic curves, and constructs a variable-frequency motor system model. It can capture factors such as changes in electrical parameters of the variable-frequency motor system, solves the problems of the inability to measure the high-frequency characteristic parameters of the existing variable-frequency motor system in real time and inaccurate modeling of individual devices, and improves the accuracy of variable-frequency motor system modeling.

[0019] Furthermore, the cable characteristic parameter equivalent circuit is: the cable unit length inductance and the cable unit length resistance are connected in series and then connected in parallel with the cable unit length capacitance.

[0020] Furthermore, the expression for calculating the characteristic parameters of the cable high-frequency line element by the finite element method is as follows:

[0021]

[0022] Where es.C0 is the cable capacitance per unit length, es.W e is the total electric energy, es.V0 is the cable terminal voltage, l is the preset cable length, mf.L0 is the cable inductance per unit length, mf.PhiCoil is the cascade magnetic flux of the coil added for cable simulation, mf.ICoil is the coil current added for cable simulation, mf.R0 is the cable resistance per unit length, and mf.RCoil is the coil resistance added for cable simulation.

[0023] Furthermore, the characteristic value is extracted from the following frequency range of the common-mode impedance characteristic curve and the differential-mode impedance characteristic curve: the starting frequency is the left side of the first intersection of the common-mode impedance characteristic curve and the differential-mode impedance characteristic curve, and the lower frequency value between the maximum value of the common-mode impedance characteristic curve and the minimum value of the differential-mode impedance characteristic curve; the ending frequency is the right side of the second intersection of the common-mode impedance characteristic curve and the differential-mode impedance characteristic curve, and the higher frequency value between the minimum value of the common-mode impedance characteristic curve and the minimum value of the differential-mode impedance characteristic curve.

[0024] Further, the variable frequency motor characteristic parameter equivalent circuit is: the first end of the surface resistance of the motor winding is respectively connected to the first end of the machine-end slew capacitor, the first end of the stator winding leakage inductance, the first end of the stator high-frequency iron loss, and the first end of the parasitic resistance between the stator winding and the motor frame; the second end of the surface resistance of the motor winding is connected to the first end of the motor winding interturn inductance, the second end of the motor winding interturn inductance is connected to the first end of the motor winding interturn capacitance, the second end of the parasitic resistance between the stator winding and the motor frame is connected to the parasitic resistance between the stator winding and the motor frame. The first end of the stator winding interturn capacitor is connected, the second end of the motor winding interturn capacitor is respectively connected to the second end of the stator winding leakage inductance, the second end of the stator high-frequency iron loss, and the first end of the parasitic resistance between the stator neutral point and the motor frame, the second end of the parasitic resistance between the stator neutral point and the motor frame is connected to the first end of the parasitic capacitor between the stator neutral point and the motor frame, and the second end of the machine-end slew capacitor is respectively connected to the second end of the motor winding interturn capacitor, the second end of the parasitic capacitor between the stator neutral point and the motor frame, and the second end of the parasitic capacitor between the stator winding and the motor frame.

[0025] Based on the same inventive concept, the present invention also provides an electronic device, including:

[0026] one or more processors;

[0027] A memory having one or more programs stored therein, which, when executed by the one or more processors, enables the one or more processors to implement the steps of the modeling method of the variable frequency motor system.

[0028] Based on the same inventive concept, the present invention further provides a computer-readable storage medium storing a computer program, which implements the steps of the modeling method of the variable frequency motor system when the computer program is executed by a processor.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention calculates and identifies the characteristic parameters of the high-frequency line elements of the cable through the finite element method, obtains the high-frequency characteristic parameters of the variable-frequency motor through the extraction of the common-mode impedance characteristic curve and the differential-mode impedance characteristic curve, and constructs a variable-frequency motor system model. It can capture factors such as the changes in electrical parameters of the variable-frequency motor system, solves the problems of the inability to measure the high-frequency characteristic parameters of the existing variable-frequency motor system in real time and the inaccurate modeling of individual devices, and improves the accuracy of variable-frequency motor system modeling. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of a flow chart of a variable frequency motor system modeling method of the present invention;

[0032] Figure 2 It is a schematic diagram of the finite element calculation of high-frequency line element characteristic parameters of the frequency conversion cable of the present invention;

[0033] Figure 3 The common mode and differential mode impedance characteristic curves of the variable frequency motor of the present invention;

[0034] Figure 4 It is a topological diagram of the variable frequency motor system model of the present invention.

[0035] In the figure, 1- three-level inverter, 2- long cable, 3- variable frequency motor, 4- high frequency voltage sensor, 5- high frequency current Hall element, 6- high voltage differential probe, 7- oscilloscope. DETAILED DESCRIPTION

[0036] The present invention will be described in detail below in conjunction with the embodiments. It should be noted that the embodiments and features of the embodiments of the present invention can be combined with each other without conflict. For the convenience of description, if the words "upper", "lower", "left" and "right" appear in the following, they only indicate that the upper, lower, left and right directions are consistent with the drawings themselves, and do not limit the structure.

[0037] Example

[0038] (1) Construction of variable frequency motor system test platform

[0039] refer to Figure 1-Figure 4 This embodiment is a test platform built with a three-level inverter 1, a long cable 2, a variable frequency motor 3, a high-frequency voltage sensor 4, a high-frequency current Hall element 5, a high-voltage differential probe 6, and an oscilloscope 7 to simulate the high-frequency operating conditions of the variable frequency motor system driven by the inverter.

[0040] Among them, the three-level inverter 1 is used to generate a driving voltage excitation, and the voltage pulse excitation is finally input to the three-phase terminal of the variable frequency motor 3 through the transmission of the long-line cable 2 to drive the variable frequency motor 3 to operate. The three-level inverter 1 is installed inside the converter cabinet; the long-line cable 2 is independently routed and installed in a separate slot frame to reduce the electromagnetic interference generated by the transient output voltage of the inverter; the variable frequency motor 3 is installed on the bogie and connected to the wheel set through gears; the high-frequency voltage sensor 4 is installed at the three terminals of the variable frequency motor 3 to measure the common mode voltage and phase voltage; the high-frequency current Hall element is installed at the connection between the long-line cable 2 and the variable frequency motor 3 to measure the common mode current and phase current; the ground wire of the high-voltage differential probe 6 is connected to the housing of the oscilloscope input terminal, and the probe hook at the signal line end is connected to the end of the point to be measured; the signal is proportionally differentially transmitted to the oscilloscope 7 through the high-voltage differential probe 6 to observe the measured common mode signal, differential mode signal and phase voltage and current signal; the oscilloscope 7 is placed on the workbench.

[0041] In the embodiment, the test platform constructed by the three-level inverter 1, the long-line cable 2, the variable frequency motor 3, the high-frequency voltage sensor 4, the high-frequency current Hall element 5, the high-voltage differential probe 6, and the oscilloscope 7 is in the rated operating condition. The output voltage pulse of the three-level inverter 1 is connected to the long-line cable 2, and the output signal is connected to the variable frequency motor 3. The high-frequency voltage sensor 4 and the high-frequency current Hall element 5 are connected to the connection between the long-line cable 2 and the variable frequency motor 3, wherein the high-frequency current Hall element 5 should ensure that the measured line is in its center position. The high-frequency voltage sensor 4 and the high-frequency current Hall element 5 are used to collect the common-mode voltage, common-mode current, phase voltage, and phase current signals of the three terminals of the motor. The obtained signals are proportionally differentiated by the high-voltage differential probe 6, and are input into the oscilloscope 7 to observe the captured common-mode signals and phase voltage and current signal results as the actual measurement basis for obtaining the key data of simulation modeling.

[0042] (2) Construction of variable frequency motor system simulation platform

[0043] The three-level inverter 1 is modeled using Figure 4 The high-frequency pulse module shown has its output connected to the cable input terminal.

[0044] The long-line cable 2 is modeled in three dimensions in the finite element software, and the cross-sectional dimension parameters, material parameters of each layer, length parameters, etc. of the long-line cable are extracted for finite element calculation to obtain the resistance characteristic parameters, capacitance characteristic parameters, and inductance characteristic parameters of the unit line element cable. The calculation formula is as follows:

[0045]

[0046] Where es.C0 is the cable capacitance per unit length, es.W eis the total electric energy, es.V0 is the voltage at the cable terminals, l is the preset cable length, mf.L0 is the cable inductance per unit length, mf.PhiCoil is the cascade magnetic flux of the coil added for cable simulation, mf.ICoil is the coil current added for cable simulation, mf.R0 is the cable resistance per unit length, and mf.RCoil is the coil resistance added for cable simulation. The material parameters of each layer of the cable include relative magnetic permeability, electrical conductivity, and relative dielectric constant.

[0047] Input the resistance characteristic parameters, capacitance characteristic parameters and inductance characteristic parameters of the unit line element cable Figure 4 The equivalent circuit topology of the long-line cable 2 shown simulates the transmission effect of the long-line cable 2 on the high-frequency pulse voltage.

[0048] The cable unit length inductance and the cable unit length resistance are connected in series and then connected in parallel with the cable unit length capacitance.

[0049] The impedance characteristic parameters of the variable frequency motor 3 are equivalent to the common mode and differential mode impedance characteristic curves of the variable frequency motor 7 according to the common mode voltage and current signals and the differential mode voltage and current signals captured by the oscilloscope 7. The calculation formula is as follows:

[0050]

[0051] Among them, Z cmf and Z dmf are the common mode and differential mode impedance frequency domain values, U cmf and U dmf are the frequency domain values ​​of common mode voltage and differential mode voltage respectively, I cmf and I dmf are the frequency domain values ​​of common mode current and differential mode current respectively. The common mode and differential mode impedance spectrum diagrams obtained are as follows: Figure 3 As shown, the corresponding characteristic values ​​are extracted from the common-mode and differential-mode impedance characteristic curves.

[0052] Frequency domain selection: find the intersection of the common-mode and differential-mode impedance curves. The starting frequency is selected from the first intersection point and extends to the left to the smaller frequency of the maximum value of the common-mode curve and the minimum value of the differential-mode curve; the ending frequency is selected from the second intersection point and extends to the right to the larger frequency of the minimum value of the common-mode curve and the minimum value of the differential-mode curve; the following feature points are selected in the above frequency domain;

[0053] Find the characteristic point from the common mode impedance spectrum: the first minimum point Z1, extract the characteristic value: the impedance amplitude Z corresponding to Z1 Z1 and resonant frequency f Z1 ; Calculate the average slope of the low-frequency segment C1 (left side of Z1) and C2 (right side of Z1), that is, the capacitance value C corresponding to the C1 segment and the C2 segment a and C HF ;

[0054] Find the characteristic points from the differential impedance spectrum: the first maximum point P, the first minimum point Z2 and the second minimum point Z3. Extract characteristic values: impedance amplitude Z at point P P , impedance amplitude Z at point Z2 Z2 , impedance angle θ z2 and resonant frequency f z2 , impedance amplitude Z at point Z3 Z3 , L1 segment (the intersection of the midpoint frequency between P and the frequency starting point and the differential mode curve) inductance value L DM and the resonant frequency f L1 .

[0055] Extract the relevant information of common mode and differential mode characteristic parameters, and the calculation formula is as follows:

[0056]

[0057] R e =3|Z P |

[0058] R sf =3|Z Z3 |

[0059]

[0060] R s =|Z Z2 |cos(θ z2 )

[0061]

[0062] Among them, R s Indicates the surface resistance of the motor winding; L w Indicates the inter-turn inductance of the motor winding; C w Indicates the inter-turn capacitance of the motor winding; L s Represents the stator winding leakage inductance; R e Represents the high-frequency iron loss of the stator; R sf Represents the parasitic resistance between the stator winding and the motor frame; C sf Represents the parasitic capacitance between the stator winding and the motor frame; R g Represents the parasitic resistance between the stator neutral point and the motor frame; C g Represents the parasitic capacitance between the stator neutral point and the motor frame; C comp Represents the motor-end slew capacitor, which suppresses the motor-end slew rate.

[0063] Surface resistance R of motor winding s The first end is connected to the machine-side slew capacitor C comp First end, stator winding leakage inductance L s First end, stator high frequency iron loss Re The parasitic resistance R between the first end, the stator winding and the motor frame sf The first end is connected to the surface resistance R of the motor winding s The second end and the motor winding turn-to-turn inductance L w The first end is connected to the motor winding turn-to-turn inductance L w The second end and the motor winding interturn capacitance C w The first end is connected to the parasitic resistance R between the stator winding and the motor frame sf The parasitic capacitance C between the second end and the stator winding and the motor frame sf The first end is connected to the motor winding interturn capacitance C w The second end is connected to the stator winding leakage inductance L s Second end, stator high frequency iron loss R e The parasitic resistance R between the second terminal, the stator neutral point and the motor frame g The first end is connected to the parasitic resistance R between the stator neutral point and the motor frame g The parasitic capacitance C between the second end and the stator neutral point and the motor frame g The first end is connected to the machine-side slew capacitor C comp The second end is connected to the motor winding inter-turn capacitance C w The parasitic capacitance C between the second end, the stator neutral point and the motor frame g The parasitic capacitance C between the second end, stator winding and motor frame sf The second end is connected to construct an equivalent circuit model of the variable frequency motor characteristic parameters.

[0064] According to the high-frequency pulse module, the parameters of the high-frequency line element of the long-line cable, and the characteristic parameters of the high-frequency motor, the circuits of each module are connected to perform comprehensive high-frequency modeling of the variable frequency motor system. Among them, the high-frequency pulse module generates a driving voltage excitation, and its right end is connected to the high-frequency model of the long-line cable. The right end of the high-frequency model of the long-line cable is connected to the input terminal of the equivalent circuit model of the characteristic parameters of the high-frequency motor. A voltage and current differential probe is added between the high-frequency model of the long-line cable and the equivalent circuit model of the characteristic parameters of the high-frequency motor, and the output of each differential probe is connected to the oscilloscope module to read the data.

[0065] (3) Evaluate and calibrate simulation parameters based on actual measurements

[0066] Substitute the extracted feature parameters into Figure 4 In the high-frequency equivalent circuit of the variable frequency motor 3 shown in the figure. In summary, a comprehensive high-frequency equivalent model of the variable frequency motor system can be obtained. By changing the length and cross-section of the variable frequency cable 2, the phase voltage and phase current data obtained by the oscilloscope 7 are compared with the phase voltage and phase current data obtained by simulating the comprehensive high-frequency equivalent model of the variable frequency motor system, so as to correct and optimize the model parameters. The model accuracy is shown in the following formula:

[0067]

[0068] Among them, η is the comprehensive high-frequency equivalent model simulation accuracy of the variable frequency motor system, r i It is the residual between the simulated and measured data of phase voltage or phase current.

[0069] If the simulation accuracy of the comprehensive high-frequency equivalent model does not reach the target accuracy, a closed-loop parameter adjustment method is used. According to the influence of each parameter of the model circuit on the simulated phase voltage and current, the simulation accuracy η of the comprehensive high-frequency equivalent model of the variable-frequency motor system is used as the feedback index to feedback and adjust the high-frequency line element parameters of the long-line cable and the high-frequency characteristic impedance parameters of the equivalent circuit model of the variable-frequency motor characteristic parameters, and the cycle continues until the simulation accuracy reaches the target accuracy.

[0070] This embodiment provides an electronic device, including:

[0071] one or more processors;

[0072] The memory stores one or more programs, and when the one or more programs are executed by one or more processors, the one or more processors implement the steps of the modeling method of the variable frequency motor system.

[0073] In some implementations, the memory may be a high-speed random access memory (RAM), and may also include a non-volatile memory, such as at least one disk memory.

[0074] In some other implementations, the processor may be a central processing unit (CPU), a digital signal processor (DSP), or other general-purpose processors of various types, which are not limited herein.

[0075] This embodiment provides a computer-readable storage medium storing a computer program, which implements the steps of the modeling method of the variable frequency motor system when the computer program is executed by a processor.

[0076] The comprehensive modeling method of a variable frequency motor system proposed in this embodiment can simulate the entire variable frequency motor system and optimize the accuracy of the proposed model parameters, thereby providing technical support for the design and maintenance of the variable frequency motor.

[0077] This embodiment achieves a breakthrough in identifying the high-frequency characteristic parameters of the system without relying on an impedance meter by comprehensively modeling the variable-frequency motor system in real-time operation, including distributed parameter modeling of the cable and parameter identification through the finite element method, high-frequency parameter modeling of the variable-frequency motor and obtaining the motor impedance characteristic parameters through spectrum feature extraction, etc., which greatly simplifies the parameter identification process and improves the efficiency of debugging and maintenance of the variable-frequency motor system. By changing the switching state of the inverter, using the finite element method to calculate the high-frequency parameters of the cable and measuring the impedance spectrum of the variable-frequency motor under different working conditions, this embodiment can accurately capture the dynamic characteristics of the system under high-frequency working conditions, including the switching behavior of power devices, changes in electrical parameters of the cable motor system, and dynamic changes in motor load characteristics, so as to improve the system's ability to resist high-frequency interference, thereby improving the stability and reliability of the entire variable-frequency motor.

[0078] In view of the shortcomings of the traditional motor cable modeling method, which is time-consuming and labor-intensive and cannot capture the high-frequency behavior of the cable, the modeling method proposed in this embodiment does not require a large amount of repeated test data, and only uses the material parameters and cross-sectional size parameters of the motor cable itself to achieve high-frequency distributed parameter modeling of the cable. This method is easy to operate and more in line with actual traction conditions. The proposed motor cable model can accurately extract the distributed parameters of the cable under high frequency and simulate its high-frequency behavior. On the other hand, in view of the shortcomings of the traditional motor modeling that cannot capture high-frequency characteristics and the high complexity of the model, this embodiment can capture the dynamic behavior of the motor under high-frequency conditions based on simple experiments. There is no need to consider the specific structural characteristics inside the motor, and this method is simpler and easier to implement. The modeling method based on measured data can more accurately reflect the actual behavior of the motor, has the advantages of full-screen coverage, wide practicability, and high reliability, and can provide strong technical support for exploring the generation mechanism of voltage surges in motor drive systems.

[0079] The comprehensive high-frequency modeling method of this embodiment provides a simpler and more efficient way to identify the high-frequency characteristic parameters of the variable-frequency motor system, further optimizes the performance of the system, and provides strong support for the reliable operation of the motor system.

[0080] The contents explained in the above embodiments should be understood as these embodiments are only used to more clearly illustrate the present invention, and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

Claims

1. A modeling method for a variable frequency motor system, characterized in that: The process includes: Build a high-frequency pulse module; According to the length, cross-sectional area and material parameters of the cable, the finite element method is used to calculate the cable high-frequency line element characteristic parameters, wherein the cable high-frequency line element characteristic parameters include the cable unit length capacitance, the cable unit length inductance and the cable unit length resistance; According to the cable high-frequency line element characteristic parameters, an equivalent circuit model of the cable characteristic parameters is constructed; The common-mode impedance is calculated according to the common-mode voltage and common-mode current of the variable-frequency motor measured in real time to obtain a common-mode impedance characteristic curve; the differential-mode impedance is calculated according to the differential-mode voltage and differential-mode current of the variable-frequency motor measured in real time to obtain a differential-mode impedance characteristic curve; a plurality of characteristic values ​​are extracted from the common-mode impedance characteristic curve and the differential-mode impedance characteristic curve, and characteristic parameters of the variable-frequency motor are obtained by calculating the characteristic values, wherein the characteristic parameters of the variable-frequency motor include the surface resistance R of the motor winding. s , motor winding turn-to-turn inductance L w , motor winding interturn capacitance C w , stator winding leakage inductance L s , stator high frequency iron loss R e , parasitic resistance R between stator winding and motor frame sf , parasitic capacitance C between stator winding and motor frame sf , parasitic resistance R between the stator neutral point and the motor frame g , parasitic capacitance C between the stator neutral point and the motor frame g , machine-side slew capacitor C comp ; According to the variable frequency motor characteristic parameters, an equivalent circuit model of the variable frequency motor characteristic parameters is constructed; The characteristic value includes the impedance amplitude Z at the first minimum value Z1 of the common mode impedance characteristic curve Z1 and the resonant frequency f Z1 , the capacitance value C corresponding to C1 in the low-frequency band on the left side of the first minimum value Z1 of the common-mode impedance characteristic curve a , the capacitance value C corresponding to C2 in the high frequency band on the right side of the first minimum value Z1 of the common mode impedance characteristic curve HF ; Impedance amplitude Z at the first maximum value P of the differential mode impedance characteristic curve P , the impedance amplitude Z at the first minimum Z2 of the differential mode impedance characteristic curve Z2 , impedance angle θ z2 and the resonant frequency f z2 , the impedance amplitude Z at the second minimum Z3 of the differential mode impedance characteristic curve Z3 , the first maximum value P of the differential mode impedance characteristic curve and the inductance value L at the midpoint L1 of the starting frequency DM and the resonant frequency f L1 ; The expression for calculating the characteristic parameters of the variable frequency motor through the characteristic value is as follows: R e =3|Z P | R sf =3|Z Z3 | R s =|Z Z2 |cos(θ z2 ) The high-frequency pulse module, the cable characteristic parameter equivalent circuit model, and the variable frequency motor characteristic parameter equivalent circuit model are connected to construct a variable frequency motor system model; the output end of the high-frequency pulse module is connected to the first end of the cable characteristic parameter equivalent circuit model, and the second end of the cable characteristic parameter equivalent circuit model is connected to the input end of the variable frequency motor characteristic parameter equivalent circuit model.

2. The modeling method of the variable frequency motor system according to claim 1, characterized in that: The cable characteristic parameter equivalent circuit is: the cable unit length inductance and the cable unit length resistance are connected in series and then connected in parallel with the cable unit length capacitance.

3. The modeling method of the variable frequency motor system according to claim 1, characterized in that: The expression for calculating the characteristic parameters of the cable high-frequency line element by the finite element method is as follows: Where es.C0 is the cable capacitance per unit length, es.W e is the total electric energy, es.V0 is the cable terminal voltage, l is the preset cable length, mf.L0 is the cable inductance per unit length, mf.PhiCoil is the cascade magnetic flux of the coil added for cable simulation, mf.ICoil is the coil current added for cable simulation, mf.R0 is the cable resistance per unit length, and mf.RCoil is the coil resistance added for cable simulation.

4. The modeling method of the variable frequency motor system according to claim 1, characterized in that: The characteristic value is extracted from the following frequency range of the common-mode impedance characteristic curve and the differential-mode impedance characteristic curve: the starting frequency is the left side of the first intersection point of the common-mode impedance characteristic curve and the differential-mode impedance characteristic curve, and the frequency is the lower value between the maximum value of the common-mode impedance characteristic curve and the minimum value of the differential-mode impedance characteristic curve; the ending frequency is the right side of the second intersection point of the common-mode impedance characteristic curve and the differential-mode impedance characteristic curve, and the frequency is the higher value between the minimum value of the common-mode impedance characteristic curve and the minimum value of the differential-mode impedance characteristic curve.

5. The modeling method of the variable frequency motor system according to claim 1, characterized in that: The variable frequency motor characteristic parameter equivalent circuit is as follows: the first end of the surface resistance of the motor winding is respectively connected to the first end of the machine-end slew capacitor, the first end of the stator winding leakage inductance, the first end of the stator high-frequency iron loss, and the first end of the parasitic resistance between the stator winding and the motor frame; the second end of the surface resistance of the motor winding is connected to the first end of the inter-turn inductance of the motor winding; the second end of the inter-turn inductance of the motor winding is connected to the first end of the inter-turn capacitance of the motor winding; the second end of the parasitic resistance between the stator winding and the motor frame is connected to the parasitic capacitance between the stator winding and the motor frame. The first end of the motor winding interturn capacitor is connected, the second end of the motor winding interturn capacitor is respectively connected to the second end of the stator winding leakage inductance, the second end of the stator high-frequency iron loss, and the first end of the parasitic resistance between the stator neutral point and the motor frame, the second end of the parasitic resistance between the stator neutral point and the motor frame is connected to the first end of the parasitic capacitor between the stator neutral point and the motor frame, and the second end of the machine-end slew capacitor is respectively connected to the second end of the motor winding interturn capacitor, the second end of the parasitic capacitor between the stator neutral point and the motor frame, and the second end of the parasitic capacitor between the stator winding and the motor frame.

6. An electronic device, characterized in that: include: one or more processors; A memory having one or more programs stored thereon, which, when the one or more programs are executed by the one or more processors, enables the one or more processors to implement the steps of the method according to any one of claims 1 to 5.

7. A computer-readable storage medium, characterized in that: The computer program is stored therein, and when the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

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