With the increasingly urgent situation of environmental protection and the instability of the world situation, fossil energy, mainly oil and natural gas, is increasingly exhausted, as many regions and countries have introduced environmental protection policies to reduce their dependence on fossil energy. New energy, also known as unconventional energy, is generally the renewable energy developed and utilised based on new technologies [1–4]. With the gradual implementation of the dual carbon policy, countries around the world are increasing the scale of new energy use to reduce carbon emissions. One of the important policies is to promote the marketisation of new energy vehicles, as well as the implementation of transformation programmes such as replacing oil with electricity, which is of great significance in reducing carbon emissions and achieving a carbon peak.

New energy vehicle technology as an emerging technology, after nearly 20 years of development, has integrated vehicle power control and helps to drive the advanced technology. The formation of advanced technology principles, with the new technology, has emerged as the new structure of the car. New energy vehicles include four types of HEV, and BEV, including solar vehicles, FCEV, and other new energy vehicles [5–7]. No matter which technology direction is adopted, the driving mode of new energy vehicles is essentially different from that of traditional oil vehicles. Traditional oil vehicles use gasoline combustion in an internal combustion engine to generate power, while new energy vehicles need to use current through the motor to generate force to achieve drive, belonging to the integrated high-power electronic and electrical device system. The drive system mainly includes high-power DC/DC converter or DC/AC inverter, power battery, drive motor and high-voltage cables connected between them [8, 9]. Due to the weight of new energy vehicles and the power demand in driving, the motor will produce a complex electromagnetic environment and send out strong electromagnetic interference (EMI) during operation. In the operation process of vehicle startup and flash-off, acceleration and deceleration are mainly realised by controlling the current size and direction of the motor. However, in the actual driving process, it is inevitable to conduct frequent acceleration and deceleration operations, which will also aggravate the complexity of the electromagnetic environment generated by the motor [10–13]. On the one hand, under the frequent on-off operation of the switch, the voltage and current jump in a short time, thus forming a strong electromagnetic radiation and interference; on the other hand, the high-voltage cable driving the components may produce a large current of hundreds of amperes during operation, which also generates strong electromagnetic radiation. Thus, new energy vehicles are in the process of running the complexity of EMI of motor drive system; Regarding motor drive system for new energy vehicle core parts, its safe operation is related to life and property safety and other major problems [14–16], and therefore very necessary for new energy vehicles’ EMI generated by the driving system which is the system theory and experimental research.

In view of the EMI phenomenon, many scholars put forward methods to predict it. As shown in Figure 1, the literature on EMI prediction reports generally shows an increasing trend. Xiang et al. [17] constructed precise mathematical models of common mode and differential mode interference sources, and systematically studied interference sources of a 10 kVA three-phase bridge converter. Zhou, [18] took the widely used switching power supply as an example and proposed a new EMI conduction modelling method. The impedance analysis method was used to model high-frequency parasitic parameters, and a model for accurately predicting the conducted EMI of switching power supply was established. Duan and Wen, [19] modelled detailed circuit parameters such as fast switching transients and parasitic parameters of power modules of SiC devices. Compared with traditional methods, this method improves the prediction accuracy of conducting EMI in the high-frequency range of the SiC motor drive system. Zhang et al., [20] proposed an EMI prediction method for UAV dynamic data link based on Gaussian Process regression (GPR). The injection test was conducted on the training subjects. Wu et al., [21] analysed and modelled the DM and CM EMI noises from the AC-DC power supply in LED TV. Jin et al., [22] proposed a new method based on the deep neural network (DNN) model, which can accurately and quickly predict the maximum radiation electric field at 3 m of the weld-wire ball grid array (WB-BGA) package. The radiation predicted by the DNN model is in good agreement with that by full-wave simulation.

Regarding the hot new energy electric vehicles in recent years, this paper analyses the mechanism of EMI, find the EMI sources and transmission ways, interference components modelling analysis of motor, and EMI test and motor drive system. To accurately predict the EMI of the motor drive system of new energy vehicles, we had better avoid the impact of EMI.

To predict the EMI of the motor drive system, it needs to clarify the mechanism of the EMI, among which, the first thing is to find out all the EMI sources. The general electric vehicle motor drive system is mainly composed of the main power loop, cable, chassis, radiator, control circuit and other parts. The main components involved in EMI include an inverter, battery, drive motor and AC cable. While inverter at work is mainly responsible for voltage transformation, the storage battery is sent out at work with a lot of energy, a current passing through the cable can produce magnetic current, the drive motor itself contains powerful magnets, becomes magnetic when we worked in the drive system, these all result in a change to the complex electromagnetic system, and the main source of EMI is the motor driven system.

There are EMI sources not only inside the system but also outside the driving system. Among them, charging and discharging the system, load mutation of power supply, high-frequency operation of the switching device and some other surrounding strong electric components can all produce EMI outside the system, especially transient EMI when a rapid large pulse current is generated [23–27]. Especially in the motor drive system, although some high-power, high-current equipment such as drive motor, power supply equipment, high-power circuit itself has a strong ability to resist EMI, under the action of switching inductance mechanism, they can produce strong EMI to the whole system. In the high-power loop module, IPM and IGBT are the main sources of power consumption and EMI. In the switching process of these high-power devices, it is easy to cause the generation of a large pulse current and voltage, which indirectly causes the generation of radiation and noise. Basically speaking, the EMI generated in the motor drive system is mainly caused by the voltage and current mutation caused by the motor start, the rapid rectification of electronic and electric devices, and the conduction of higher field intensity and radiation disturbance caused by high voltage radiation.

According to another division method, the EMI source of the motor drive system can be divided into the common mode interference source generated by the main power loop, and the radiation interference source. Common-mode interference propagates mainly through the parasitic capacitive coupling of the system to the ground. As shown in Figure 2, when the switching device is turned on or off, it generates a high charge and discharge of parasitic capacitance [28]. In the drive system, common-mode interference is mainly caused by charging and discharging behaviours of parasitic capacitors by grounded devices, leads and shells, thus generating conducted common-mode EMI. In the actual working process, the generation of common mode EMI mainly depends on the parasitic capacitance between the tripod of the switching device and the heat dissipation device.

Differential mode interference refers to the interference between phase lines directly through the loop formed by phase lines and power supply, which is the noise of equal amplitude and opposite phase generated on two signal lines [29]. In the switching on and off process of IGBT and other high-power devices, there will be a rapid change of current. Although this part of the current does not flow through the motor, to realise the continuity of current in the motor, other channel currents also change rapidly. In the presence of a higher stray inductance, a differential mode voltage change occurs, followed by a differential mode interference current. Although differential mode interference increases the degree of EMI in the system, it is unavoidable. The idea of eliminating differential mode current is not feasible in practice, but we can reduce the influence of differential mode interference on sensitive devices by changing the path of differential mode current.

Other EMI comes from the existing radiation interference sources, such as the radiation interference generated by the motor, power cable, etc., and the radiator will more or less produce some electromagnetic oscillation interference. Motor start, stop and load change will change the working current and generate pulse current, and this disturbance is manifested as irregular pulse flow of about 10 kHz ∼ 1 GHz spectrum. Power cables will lead to crosstalk between cables through radiation, resulting in EMI to other components in the car and signal cables, affecting their normal operation. Electromagnetic leakage may also occur in the chassis with poor shielding, which also causes EMI [30, 31, 32].

Common mode interference has the characteristics of high frequency and large amplitude, which can cause large interference. On the contrary, differential mode interference has a small amplitude, which causes small interference. As shown in Figure 4, in the actual measurement, the common-mode current flows from the radiator to the reference point, back to the DC side through the impedance stabilisation network (LISN) used for the measurement or through the core capacitance, and then to the inverter through the DC input line.

We can know from Figure 5 that there are two propagation paths of differential mode interference. Path 1 is the extra interference caused by the switch, which is removed by adding dead zones in this paper. Path 2 is the additional interference generated by useful current during operation, which is suppressed by shielding, wiring and other methods.

In the motor drive system, when the switching components switch, the EMI is caused by

Where:

Where

Similarly, it can be obtained through Eq. (3):

Where:

For _{YmYn}_{YmXn}_{p}

In the equation, _{p}_{p}

The inductance of the DC connection cable connecting the inverter will affect the high-frequency EMI spectrum and should be modelled. The inductance, named _{cable}

Where

The total DM EMI source should be a combination of

The total CM EMI source VCM should be a combination of VcmV and VcmI, which can also be written as:

It can be seen that in Eqs (8) and (9), to analytically calculate

The EMI test of the motor system mainly includes two aspects: one is to test the conducted radiation; second, PCB board near field radiation is tested. The conducted radiation includes the voltage method and the test of instantaneous pulses in the main loop route, usually using CISPR15 and GB18655-2011.

The schematic diagram of the voltage method test is shown in Figure 6. According to the international standard manual, the positive and negative power cables of the test equipment should be connected to two manual networks respectively. The length of the power cables should exceed 250 mm.

Figure 7 shows the schematic diagram of the testing structure of the instantaneous pulse of the main loop route. This method has a more accurate testing effect than the voltage method. In this circuit, the connecting wire should be arranged in an insulation material of 70 mm or so. The oscilloscope and voltage wave are added to the circuit, and the waveform diagram of repeated changes can be obtained by controlling the circuit through switches. To keep the accuracy of the results, it waveform data needs to be collected10 times and the best quality is selected. A schematic diagram of the circuit structure is shown in Figure 7.

Taking the motor drive system as the research object, the EMI results are tested. In this paper, the model XC2287 three-phase AC permanent magnet synchronous motor is taken as the research object, and the main parameters are as follows: The voltage of the DC power supply is 26 V, the frequency of the PWM wave is 900 kHz, the rated power is 3600 W, the rated current is 7500 mA, the maximum instantaneous current is 1370 mA, the line-phase electromotive force is 5.4 V, the speed is fixed at 3200 RPM, and the maximum is 4000 RPM. The internal resistance of the coil is 0.264

The test is mainly analysed through a waveform diagram, and the detection method mainly follows the following principles:

Emission performance should be considered if EUT includes mathematical logic circuits such as clock, crystal oscillator, micro processing equipment, and RC; However, if EUT is a commutable current circuit, switching control circuit or ignition system, the broadband transmission performance should be considered.

The narrow test of EUT should strictly refer to CISPR 16-1-1. The mean detection method has the advantages of suppressing pulse signals and ensuring signal integrity in measuring narrow broadband signals than the peak detection method. So in this paper, the mean detection method is used to analyse the narrowband emission performance.

In broadband transmission test, peak detection mode or quasi-peak detection mode can be selected according to the actual work requirements. The principle of the two is different. The peak detection is designed to simulate the sound signal received by the human ear, which has a less anti-interference ability. The quasi-detection mode is designed to simulate the reception of satellite signal, which is not prone to distortion. Table 1 lists the test equipment models and corresponding manufacturers.

Selection of test equipment

Test system equipment | Specifications | Manufacturer |
---|---|---|

EMI test receiver | ECSE32 | R & S |

Antenna | HFH3-Z8 | R & S |

Double cone antenna | HK 120 | R & S |

Log-periodic antenna | HL 225 | R & S |

Double ridged waveguide horn antenna | EMCO 3210 | ETC-lindgram |

Artificial network | NNBM 8133 | SCHW ARZBARK |

EMI, electromagnetic interference

Figure 9 shows that during the working process of the motor drive system, the amplitude difference of vibration of the test curve is not particularly large under different conduction frequencies, and the maximum difference is 2 dB µV.

From the test results, the motor system is working, and as the frequency increases, the changing trend of test results is almost suppressed. The test results show that the difference between peak and minimum is nearly 20 dBµV, and the difference in each has the same frequency, which can work when the transmission frequency motor system is relatively stable, along with the signal frequency.

To further increase the working current of the motor, to analyse the transmission frequency, it is found that the relationship between test results and frequency is not large, and under different frequency, the test results of the maximum and the minimum are almost the same. However, when the current is bigger, the test voltage changes fast, and the test curve looks more intensive, which can be learnt from Maxwell’s electromagnetic theory. The changing current will produce a magnetic field, and the greater the intensity, the more obvious the electromagnetic interaction.

Test equipment for radiation emission interference results mainly includes the following:

MD 03052 digital oscilloscope, bandwidth range 0–500 MHz, the adoption rate is set to 2.5 Gs/s, with filtering analysis function;

The length of the rf coaxial cable is 30 cm. The coil is made of aluminium material with an insulating layer of 5 turns. Both ends are respectively connected with the idle centre and obstacle layer of the RF coaxial blue line.

EUT is an electronic component with a testing function. It connects the BNC interface of the rf coaxial line with the digital channel of the oscilloscope to form a near-field bottom testing system.

The near-field test is to use the built test system in the experiment. It is to test and analyse the radiation emission in a specific frequency band, but the specific value cannot be calculated. In this way, the requirement for experimental equipment is not so high, and the experimental cost can be saved to some extent. Set up EUT test environment to ensure normal current and grounding of the system. To better experiment, the coil in the testing process in turn along the parallel and vertical direction of the chassis shell, scanning the entire process after the agency failed to EMI Kalman filter processing, can lead to the error of the relatively large test results, so the experiment was made in the process of debugging, to clearly observe the phenomenon, after testing the electrical flow in circuit 7.After Kalman filtering, relatively regular test curves are obtained, as shown in Figure 11.

Considering the practical industrial application, the results of EMI with small currents were mainly predicted, and the relationship between electromagnetic radiation field intensity and frequency under different current sizes were tested, and the test results were obtained as shown in Figure 12. The peak intensity of magnetic field radiation decreases with the decrease of current. When the current is 1A, the radiation intensity is mainly concentrated in the 0–20 Ghz frequency band, and the waveform is relatively dense. At this time, the interference effect of the magnetic field is still obvious.

When it is further increased to 2 current, the magnetic field radiation wave diagram is as shown in Figure 13(a). When the wave numerical further increases, the field strength changes with frequency., When there is a change in the frequency range of 0–10 GHz, and 30–40 GHz, the radiation intensity appears to be strong with shocks, the interference effect is strengthened, and under a certain frequency, the magnetic field and electric current produce a resonance. The presence of a magnetic field will produce a larger effect. When the current increases to 5A, there are obvious oscillations at low frequency, medium frequency and high frequency, and the peak value of the curve increases slightly. At this time, the effect of the magnetic field has no certain rule, but at 5–10 Ghz, 12–20 Ghz and 30–40 Ghz, the interference of the magnetic field is relatively weak, and the radiation intensity is stable within this range. In general, with the increase of current intensity, the peak value of magnetic field radiation intensity increases, and the obvious interference range changes from low-frequency current to high-frequency current. At a high current, the magnetic field radiation interference is concentrated in the low frequency, medium frequency and high-frequency regions.

In view of the complex and changeable EMI in the motor drive system of new energy vehicles, this paper analysed the generation mechanism of EMI, found the EMI source, and modelled and analszed the motor interference components. The conclusions are as follows:

In view of the EMI in the new energy motor drive system, the EMI source and propagation path are analysed. The results show that Electromagnetic interference sources are mainly from the main power circuit within the system, cable, chassis, radiator, outside of the control circuit and system of charging and discharging system, power supply high-frequency operation load mutation, switching devices and some other surrounding high voltage components. And different transmission forms in frequency and amplitude have a great difference.

Through the main return route pulse testing method to test the conduction radiation intensity, it is found that when the current motor system voltage variation ratio is relatively stable, the maximum and the minimum voltage difference is 20 dBµV, the difference in the frequency not big; but when the current is bigger, the frequency of the circuit voltage changes quickly, with more intense voltage curve. The difference between the maximum and minimum voltage is further increased, so we can conclude that the frequency does not influence circuit voltage, but only the circuit size, which is in line with Maxwell’s electromagnetic theory model.

Through the near-field radiation test, it can be seen that the influence of the magnetic field is related to the magnitude and frequency of the current. When the working current is 1A, the field intensity curve oscillates violently, concentrated in the 0–20 Ghz frequency band. When the current increases to 2A and 5A, the gap between the peak value and the minimum value of the field intensity further widens. At 2A current, the field intensity distribution is relatively uniform with frequency, and obvious changes appear at higher frequencies, which is caused by resonance. However, when the current is 5A, the strong interference effect of the magnetic field appears at low frequency, intermediate frequency and high frequency, and is relatively fixed at other frequencies. In general, with the increase of current intensity, the obvious interference range has a trend of changing from low-frequency to high-frequency current.

#### Selection of test equipment

Test system equipment | Specifications | Manufacturer |
---|---|---|

EMI test receiver | ECSE32 | R & S |

Antenna | HFH3-Z8 | R & S |

Double cone antenna | HK 120 | R & S |

Log-periodic antenna | HL 225 | R & S |

Double ridged waveguide horn antenna | EMCO 3210 | ETC-lindgram |

Artificial network | NNBM 8133 | SCHW ARZBARK |

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Index Evaluation Based on Logistic Distribution Fitting Transition Probability Function Children's Educational Curriculum Evaluation Management System in Mathematical Equation Model Query Translation Optimization and Mathematical Modeling for English-Chinese Cross-Language Information Retrieval The Effect of Children’s Innovative Education Courses Based on Fractional Differential Equations Fractional Differential Equations in the Standard Construction Model of the Educational Application of the Internet of Things Optimization research on prefabricated concrete frame buildings based on the dynamic equation of eccentric structure and horizontal-torsional coupling Optimization in Mathematics Modeling and Processing of New Type Silicate Glass Ceramics Green building considering image processing technology combined with CFD numerical simulation Research on identifying psychological health problems of college students by logistic regression model based on data mining Abnormal Behavior of Fractional Differential Equations in Processing Computer Big Data Mathematical Modeling Thoughts and Methods Based on Fractional Differential Equations in Teaching Research on evaluation system of cross-border E-commerce platform based on the combined model A mathematical model of PCNN for image fusion with non-sampled contourlet transform Nonlinear Differential Equations in Computer-Aided Modeling of Big Data Technology The Uniqueness of Solutions of Fractional Differential Equations in University Mathematics Teaching Based on the Principle of Compression Mapping Financial customer classification by combined model Influence of displacement ventilation on the distribution of pollutant concentrations in livestock housing Recognition of Electrical Control System of Flexible Manipulator Based on Transfer Function Estimation Method Automatic Knowledge Integration Method of English Translation Corpus Based on Kmeans Algorithm Real Estate Economic Development Based on Logarithmic Growth Function Model Design of Tennis Mobile Teaching Assistant System Based on Ordinary Differential Equations Financial Crisis Early Warning Model of Listed Companies Based on Fisher Linear Discriminant Analysis High Simulation Reconstruction of Crowd Animation Based on Optical Flow Constraint Equation Construction of Intelligent Search Engine for Big Data Multimedia Resource Subjects Based on Partial Least Squares Structural Equation 3D Animation Simulation of Computer Fractal and Fractal Technology Combined with Diamond-Square Algorithm Analysis of the Teaching Quality of Physical Education Class by Using the Method of Gradient Difference The Summation of Series Based on the Laplace Transformation Method in Mathematics Teaching Optimal Solution of the Fractional Differential Equation to Solve the Bending Performance Test of Corroded Reinforced Concrete Beams under Prestressed Fatigue Load Animation VR scene mosaic modeling based on generalized Laplacian equation Radial Basis Function Neural Network in Vibration Control of Civil Engineering Structure Optimal Model Combination of Cross-border E-commerce Platform Operation Based on Fractional Differential Equations The influence of accounting computer information processing technology on enterprise internal control under panel data simultaneous equation Research on Stability of Time-delay Force Feedback Teleoperation System Based on Scattering Matrix BIM Building HVAC Energy Saving Technology Based on Fractional Differential Equation Construction of comprehensive evaluation index system of water-saving irrigation project integrating penman Montei the quation Human Resource Management Model of Large Companies Based on Mathematical Statistics Equations Data Forecasting of Air-Conditioning Load in Large Shopping Malls Based on Multiple Nonlinear Regression Analysis of technical statistical indexes of college tennis players under the win-lose regression function equation Automatic extraction and discrimination of vocal main melody based on quadratic wave equation Analysis of wireless English multimedia communication based on spatial state model equation Optimization of Linear Algebra Core Function Framework on Multicore Processors Application of hybrid kernel function in economic benefit analysis and evaluation of enterprises Research on classification of e-commerce customers based on BP neural network The Control Relationship Between the Enterprise's Electrical Equipment and Mechanical Equipment Based on Graph Theory Mathematical Modeling and Forecasting of Economic Variables Based on Linear Regression Statistics Nonlinear Differential Equations in Cross-border E-commerce Controlling Return Rate 3D Mathematical Modeling Technology in Visualized Aerobics Dance Rehearsal System Fractional Differential Equations in Electronic Information Models BIM Engineering Management Oriented to Curve Equation Model Leakage control of urban water supply network and mathematical analysis and location of leakage points based on machine learning Analysis of higher education management strategy based on entropy and dissipative structure theory Prediction of corporate financial distress based on digital signal processing and multiple regression analysis Mathematical Method to Construct the Linear Programming of Football Training Multimedia sensor image detection based on constrained underdetermined equation The Size of Children's Strollers of Different Ages Based on Ergonomic Mathematics Design Application of Numerical Computation of Partial Differential Equations in Interactive Design of Virtual Reality Media Stiffness Calculation of Gear Hydraulic System Based on the Modeling of Nonlinear Dynamics Differential Equations in the Progressive Method Knowledge Analysis of Charged Particle Motion in Uniform Electromagnetic Field Based on Maxwell Equation Relationship Between Enterprise Talent Management and Performance Based on the Structural Equation Model Method Term structure of economic management rate based on parameter analysis of estimation model of ordinary differential equation Influence analysis of piano music immersion virtual reality cooperation based on mapping equation Chinese painting and calligraphy image recognition technology based on pseudo linear directional diffusion equation Label big data compression in Internet of things based on piecewise linear regression Animation character recognition and character intelligence analysis based on semantic ontology and Poisson equation Design of language assisted learning model and online learning system under the background of artificial intelligence Study on the influence of adolescent smoking on physical training vital capacity in eastern coastal areas Application of machine learning in stock selection Comparative analysis of CR of ideological and political education in different regions based on improved fuzzy clustering Action of Aut( G ) on the set of maximal subgroups ofp -groupsResearch on loyalty prediction of e-commerce customer based on data mining Algebraic Equations in Educational Model of College Physical Education Course Education Professional English Translation Corpus Under the Binomial Theorem Coefficient Geometric Tolerance Control Method for Precision Machinery Based on Image Modeling and Novel Saturation Function Retrieval and Characteristic Analysis of Multimedia Tester Based on Bragg Equation Semiparametric Spatial Econometric Analysis of Household Consumption Based on Ordinary Linear Regression Model Video adaptive watermark embedding and detection algorithm based on phase function equation English Learning Motivation of College Students Based on probability Distribution Scientific Model of Vocational Education Teaching Method in Differential Nonlinearity Research on mobile Awareness service and data privacy Protection based on Linear Equations computing protocol Vocal Music Teaching Model Based on Finite Element Differential Mathematical Equations Studying a matching method combining distance proximity and buffer constraints The trend and influence of media information Propagation based on nonlinear Differential equation Research on the construction of early warning model of customer churn on e-commerce platform Evaluation and prediction of regional human capital based on optimised BP neural network Study on inefficient land use determination method for cities and towns from a city examination perspective A study of local smoothness-informed convolutional neural network models for image inpainting Mathematical Calculus Modeling in Improving the Teaching Performance of Shot Put Application of Nonlinear Differential Equation in Electric Automation Control System Higher Mathematics Teaching Curriculum Model Based on Lagrangian Mathematical Model Computational Algorithm to Solve Two–Body Problem Using Power Series in Geocentric System Decisions of competing supply chain with altruistic retailer under risk aversion Optimization of Color Matching Technology in Cultural Industry by Fractional Differential Equations The Marketing of Cross-border E-commerce Enterprises in Foreign Trade Based on the Statistics of Mathematical Probability Theory Application of Linear Partial Differential Equation Theory in Guiding Football Scientific Training Nonlinear Channel Estimation for Internet of Vehicles Some Necessary Conditions for Feedback Functions of de Bruijn Sequences The Evolution Model of Regional Tourism Economic Development Difference Based on Spatial Variation Function System Model of Shipping Enterprise Safety Culture Based on Dynamic Calculation Matrix Model An empirical research on economic growth from industrial structure optimisation in the Three Gorges Reservoir area The Inner Relationship between Students' Psychological Factors and Physical Exercise Based on Structural Equation Model (SEM) Analysis and Research on Influencing Factors of Ideological and Political Education Teaching Effectiveness Based on Linear Equation Study of agricultural finance policy information extraction based on ELECTRA-BiLSTM-CRF Fractional Differential Equations in Sports Training in Universities Examination and Countermeasures of Network Education in Colleges and Universities Based on Ordinary Differential Equation Model Innovative research of vertical video creation under the background of mobile communication Higher Education Agglomeration Promoting Innovation and Entrepreneurship Based on Spatial Dubin Model Chinese-English Contrastive Translation System Based on Lagrangian Search Mathematical Algorithm Model Genetic algorithm-based congestion control optimisation for mobile data network