Engine starting control method and system for extended-range electric vehicle

Abstract

The invention relates to the technical field of extended-range electric vehicle control, and discloses an engine starting control method and system for an extended-range electric vehicle, and the method comprises the following steps: obtaining the operation information of the extended-range electric vehicle, the operation information comprises the actual temperature of an engine, the actual rotating speed of a range extender, the state of charge (SOC) of a power battery and the maximum dischargeable power; when the starting request mark position of the engine is set, the generator is controlled to enter a torque control mode, and the engine enters a starting mode; and based on the actual temperature of the engine and the actual rotating speed of the range extender, the pre-control torque of the generator is activated through the enabling flag bit. By accurately controlling the rotating speed and the torque of the generator, smooth starting of the engine is achieved, the requirement for starting the engine in various vehicle using scenes is met, meanwhile, the actual temperature of the engine, the SOC of a power battery and the like are considered, the target rotating speed of the started engine and the starting torque of the generator are flexibly controlled, and the starting efficiency is improved. The starting performance of the engine is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of extended-range electric vehicle control, and in particular to an engine starting control method and system for an extended-range electric vehicle. Background Art

[0002] Extended-range electric vehicles (EVs) utilize a range extender, consisting of an engine and generator, to effectively increase the vehicle's driving range. During operation, when engine starting conditions are met, the generator typically starts the engine. Once the engine starts, the engine drives the generator to generate electricity to meet the vehicle's power requirements.

[0003] In existing technologies, engine starting control typically only controls the generator speed. This involves using a speed mode to drag the engine to the target speed for fuel injection and ignition, and then entering idle mode when the engine speed exceeds this target speed. However, in practice, the drag torque during engine starting is affected by various factors (such as engine temperature and battery status). Relying solely on generator speed control can easily lead to poor engine starting smoothness, which in turn affects the vehicle user's driving experience. Furthermore, existing technologies fail to fully incorporate parameters such as the battery's state of charge (SOC) and maximum discharge power to dynamically adjust the starting process. This can lead to problems such as low starting reliability and high energy consumption in low-temperature environments or when the battery is low. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention provides an engine start control method and system for an extended-range electric vehicle, which solves the problems mentioned in the above background technology.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: A method for controlling engine start of an extended-range electric vehicle, comprising the following steps: Acquiring operating information of the range-extended electric vehicle, the operating information including actual engine temperature, actual range extender speed, power battery state of charge (SOC), and maximum dischargeable power; When the engine start request flag is set, the generator is controlled to enter the torque control mode and the engine enters the start mode; Based on the actual engine temperature and the actual speed of the range extender, the pre-control torque of the generator is activated by the enable flag; The deviation between the actual speed of the range extender and the starting target drag speed is low-pass filtered, and the filtered deviation is used as the input of the PID controller to perform closed-loop control of the generator torque, and the starting control torque is determined in combination with the pre-control torque; When the actual engine speed reaches the injection and ignition speed threshold, the EMS is controlled to inject fuel and ignite the engine; When the actual engine speed is greater than the starting target speed, the engine is controlled to enter the running mode and the starting is completed; During the starting process, the engine vibration signal is collected in real time, and the compensation amount of the generator torque is adjusted based on the vibration signal characteristics.

[0006] Preferably, the setting of the pre-control torque based on the actual engine temperature and the actual speed of the range extender includes: Obtaining a corresponding torque value by querying a pre-control torque calibration table, wherein the calibration table is pre-established based on the actual engine temperature and the actual speed of the range extender; The process of establishing the calibration table includes: In different actual engine temperature ranges, bench tests are conducted to obtain the minimum drag torque of the range extender at different actual speeds. Performing temperature compensation correction on the minimum drag torque to generate a corrected pre-control torque value; The temperature range, speed range and pre-control torque value are stored correspondingly to form a two-dimensional calibration table.

[0007] Preferably, the performing PID closed-loop control on the generator torque includes: The torque calculated by the Kp term and the Ki term of the PID controller is respectively limited to a maximum torque and a minimum torque, and the limit values ​​are calibrated by bench tests; The PID closed-loop torque is added to the offset of the pre-control torque to generate the starting control torque.

[0008] Preferably, the method for determining the starting target drag speed includes: When the power battery SOC is lower than a first threshold, reducing the starting target drag speed; When the maximum dischargeable power of the power battery is lower than the second threshold, the starting target drag speed is corrected by a piecewise interpolation method; The threshold setting basis is: First threshold: When the SOC is lower than 30%, the battery's internal resistance increases significantly, and the discharge capacity decreases. Lowering the target speed can reduce starting power consumption and avoid battery over-discharge. Second threshold: Based on the typical power requirements of the extended-range system, when the maximum discharge power of the battery is less than 50kW, it cannot meet the starting requirements at the basic target speed of 1500rpm and needs to be dynamically adjusted through interpolation.

[0009] Preferably, collecting the engine vibration signal and adjusting the torque compensation amount includes: Vibration signals are collected in real time through the acceleration sensor installed on the engine cylinder; Perform time-frequency domain analysis on the vibration signal to extract the combustion vibration frequency component and the mechanical vibration frequency component; When the amplitude of the combustion vibration frequency component exceeds a preset threshold, reducing the generator torque compensation amount; When the mechanical vibration frequency component is abnormal, the torque compensation amount is increased to suppress resonance.

[0010] Preferably, the time-frequency domain analysis of the vibration signal includes: Wavelet transform is used to perform multi-scale decomposition of vibration signals to obtain energy distribution in different frequency bands; The time-frequency spectrum of the vibration signal is generated by short-time Fourier transform to identify the abnormal vibration characteristic frequency.

[0011] Preferably, when the generator enters the torque control mode, the method further comprises: The generator speed increase gradient limit is calibrated based on the deviation between the starting target drag speed and the actual speed of the range extender, as well as the actual engine temperature; When the speed deviation is greater than the preset value, the speed gradient limit is increased linearly in stages.

[0012] Preferably, the setting of the fuel injection ignition speed threshold is also based on the power battery SOC, including: When the SOC is higher than the third threshold, the fuel injection ignition speed threshold is the first preset value; When the SOC is lower than the third threshold, the fuel injection ignition speed threshold is a second preset value, and the first preset value is greater than the second preset value; The third threshold is 40%, the first preset value is 800 rpm, and the second preset value is 600 rpm; The logic of the threshold setting is: When SOC>40%, the battery discharge capacity is sufficient, and a higher injection ignition speed of 800rpm is used to shorten the starting time and improve responsiveness; When SOC is ≤ 40%, the fuel injection and ignition speed is reduced to 600 rpm to reduce starting energy consumption. At the same time, combustion stability is improved by advancing fuel injection and ignition to compensate for the reduction in drag torque caused by insufficient battery power. The injection ignition speed threshold also needs to be corrected in combination with the actual engine temperature T. The correction formula is: When T<0℃, If SOC>40%, the injection ignition speed threshold is corrected to: ; If SOC≤40%, the injection ignition speed threshold is corrected to: ; When T≥0℃, the original threshold remains unchanged.

[0013] Preferably, the step of collecting the engine vibration signal in real time and adjusting the torque compensation amount further includes: Establish a vibration model database of historical starting data, which stores the corresponding relationship between vibration characteristics and torque compensation under different engine temperatures, power battery SOC and starting target speed conditions; The real-time vibration signal is analyzed in the time-frequency domain to extract features, which are then matched with the vibration features in the database to find the historical vibration model with the highest similarity. Generate a predicted value based on the torque compensation amount corresponding to the matched historical vibration model, and fuse it with the real-time calculated compensation amount through the Kalman filter algorithm to obtain the final compensation amount used to adjust the generator torque; Among them, vibration feature matching uses Euclidean distance to calculate similarity, and Kalman filtering realizes data fusion through recursive calculation of state prediction and observation update.

[0014] An engine starting control system for an extended-range electric vehicle, comprising: An operating information acquisition module is configured to obtain operating information of the range-extended electric vehicle, wherein the operating information includes actual engine temperature, actual speed of the range extender, state of charge (SOC) of the power battery, and maximum dischargeable power; A control mode switching module is configured to control the generator to enter a torque control mode and the engine to enter a starting mode when the engine start request flag is set; A pre-control torque generation module is configured to activate the pre-control torque of the generator based on the actual engine temperature and the actual speed of the range extender through an enable flag, and query the pre-control torque calibration table to obtain a corresponding torque value; A PID closed-loop control module is configured to perform low-pass filtering based on the deviation between the actual speed of the range extender and the starting target drag speed, use the filtered deviation as the input of the PID controller, perform closed-loop control of the generator torque, and determine the starting control torque in combination with the pre-control torque; The fuel injection and ignition control module is configured to control the EMS to inject fuel and ignite the engine when the actual engine speed reaches the fuel injection and ignition speed threshold; a mode conversion determination module configured to control the engine to enter a running mode and complete starting when the actual engine speed is greater than the starting target speed; The vibration signal processing module is configured to collect the engine vibration signal in real time during the starting process and adjust the compensation amount of the generator torque based on the vibration signal characteristics.

[0015] The present invention provides an engine start control method and system for an extended-range electric vehicle. The method and system have the following beneficial effects: By accurately controlling the generator speed and torque, smooth engine starts are achieved, meeting engine starting requirements in various vehicle usage scenarios. Furthermore, by taking into account the actual engine temperature, the power battery's state of charge (SOC), and the maximum dischargeable power, the target engine speed and generator starting torque are flexibly controlled to enhance engine starting performance. Specifically, the coordinated calibration of the actual engine temperature and pre-controlled torque, combined with dynamic correction of the target speed based on the power battery status, optimizes the starting strategy at low temperatures or when the battery is low. Furthermore, the coordinated control of vibration signal feedback and torque compensation further enhances the smoothness of the starting process, resulting in excellent starting reliability, economy, emissions performance, NVH performance, and adaptability to low-temperature environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The figure is a flow chart of an engine starting control method for an extended-range electric vehicle according to an embodiment of the present invention.

[0017] Figure 2 This is an architecture diagram of the engine starting control system of the extended-range electric vehicle in an embodiment of the present invention. DETAILED DESCRIPTION

[0018] The following will clearly and completely describe the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0019] Example: Please see the attached Figure 1 The embodiment of the present invention provides an engine start control method for an extended-range electric vehicle, comprising the following steps: Acquiring operating information of the range-extended electric vehicle, the operating information including actual engine temperature, actual range extender speed, power battery state of charge (SOC), and maximum dischargeable power; When the engine start request flag is set, the generator is controlled to enter the torque control mode and the engine enters the start mode; Based on the actual engine temperature and the actual speed of the range extender, the pre-control torque of the generator is activated by the enable flag; The deviation between the actual speed of the range extender and the starting target drag speed is low-pass filtered, and the filtered deviation is used as the input of the PID controller to perform closed-loop control of the generator torque, and the starting control torque is determined in combination with the pre-control torque; When the actual engine speed reaches the injection and ignition speed threshold, the EMS is controlled to inject fuel and ignite the engine; When the actual engine speed is greater than the starting target speed, the engine is controlled to enter the running mode and the starting is completed; During the starting process, the engine vibration signal is collected in real time, and the compensation amount of the generator torque is adjusted based on the vibration signal characteristics.

[0020] Specifically, operating information such as the actual engine temperature, range extender speed, power battery SOC and maximum dischargeable power are obtained through sensors. When a start request is triggered, the generator is switched to torque control mode and the engine enters start mode. The pre-control torque is activated based on the engine temperature and range extender speed. The deviation between the actual speed of the range extender and the target speed is low-pass filtered and used as the input of the PID controller. The starting control torque is generated in combination with the pre-control torque. When the engine speed reaches the injection ignition threshold, the EMS injection ignition is controlled. When the speed exceeds the target value, it switches to the running mode. At the same time, the engine vibration signal is collected in real time, and the torque compensation amount is adjusted according to the vibration characteristics.

[0021] It realizes closed-loop control with multi-parameter fusion, solves the problem of poor smoothness of traditional single-speed control, and improves the engine's starting reliability, economy, emission performance and NVH performance under different working conditions through precise control of speed and torque and vibration feedback compensation, and enhances its adaptability to low-temperature environments.

[0022] The pre-control torque is set based on the actual engine temperature and the actual speed of the range extender, including: Obtaining a corresponding torque value by querying a pre-control torque calibration table, wherein the calibration table is pre-established based on the actual engine temperature and the actual speed of the range extender; The process of establishing the calibration table includes: In different actual engine temperature ranges, bench tests are conducted to obtain the minimum drag torque of the range extender at different actual speeds. Performing temperature compensation correction on the minimum drag torque to generate a corrected pre-control torque value; The temperature range, speed range and pre-control torque value are stored correspondingly to form a two-dimensional calibration table.

[0023] Specifically, the actual temperature ranges of different engines are divided into the following ways: When T<-10℃, it is divided into low temperature range; when -10℃≤T<25℃, it is divided into normal temperature range; when T≥25℃, it is divided into high temperature range; The temperature compensation correction formula is:

[0024] in, is the corrected pre-control torque value, The minimum drag torque obtained for the bench test, is the temperature compensation coefficient, is the reference temperature; The bench test procedure for obtaining the minimum drag torque is as follows: with the engine in cold, warm, and hot states, the range extender is controlled to increase the total speed to the rated speed in 50 rpm steps. The minimum generator torque required for a successful engine start at each speed point is recorded. The criteria for a successful start are a start time of ≤2s and a speed overshoot of ≤10%. The storage method of the two-dimensional calibration table includes: discretizing the temperature range in steps of 10°C and the speed range in steps of 100 rpm; and calculating and filling the torque values ​​of non-measurement points after discretization using bilinear interpolation method.

[0025] The PID closed-loop control of the generator torque includes: The torque calculated by the Kp term and the Ki term of the PID controller is respectively limited to a maximum torque and a minimum torque, and the limit values ​​are calibrated by bench tests; The PID closed-loop torque is added to the offset of the pre-control torque to generate the starting control torque.

[0026] Specifically, the PID controller's Kp and Ki terms, calculated using torque calculations, were bench-tested and calibrated to their maximum and minimum limits. The starting control torque was then generated by adding the PID closed-loop torque to the pre-control torque offset. Torque limits ensure system safety, and the synergistic effect of the PID closed-loop and pre-control torque improves torque control accuracy and smoothness, reducing speed fluctuations.

[0027] The method for determining the starting target drag speed includes: When the power battery SOC is lower than a first threshold, reducing the starting target drag speed; When the maximum dischargeable power of the power battery is lower than the second threshold, the starting target drag speed is corrected by a piecewise interpolation method; The threshold setting basis is: First threshold: When the SOC is lower than 30%, the battery's internal resistance increases significantly, and the discharge capacity decreases. Lowering the target speed can reduce starting power consumption and avoid battery over-discharge. Second threshold: Based on the typical power requirements of the extended-range system, when the maximum discharge power of the battery is less than 50kW, it cannot meet the starting requirements at the basic target speed of 1500rpm and needs to be dynamically adjusted through interpolation.

[0028] Specifically, when the power battery SOC falls below 30%, the target starting speed is lowered to reduce energy consumption. When the maximum dischargeable power falls below 50kW, the target speed is adjusted using piecewise interpolation to adapt it to the battery's discharge capacity. This prevents overdischarge or overloading of the battery when it is at low charge or power, balances starting energy consumption with battery protection, and improves system starting reliability even when the battery is in poor condition.

[0029] The collecting of the engine vibration signal and adjusting the torque compensation amount includes: Vibration signals are collected in real time through the acceleration sensor installed on the engine cylinder; Perform time-frequency domain analysis on the vibration signal to extract the combustion vibration frequency component and the mechanical vibration frequency component; When the amplitude of the combustion vibration frequency component exceeds a preset threshold, reducing the generator torque compensation amount; When the mechanical vibration frequency component is abnormal, the torque compensation amount is increased to suppress resonance.

[0030] Specifically, the system collects vibration signals in real time using the engine cylinder accelerometer. Time-frequency analysis is then performed to extract combustion and mechanical vibration frequency components. The system then adjusts the torque compensation based on whether the combustion vibration amplitude exceeds a threshold or if mechanical vibration is abnormal. This real-time suppression of combustion vibration and mechanical resonance improves NVH performance during starting, enhances starting stability, and enhances driving comfort.

[0031] The time-frequency domain analysis of the vibration signal includes: Wavelet transform is used to perform multi-scale decomposition of vibration signals to obtain energy distribution in different frequency bands; The time-frequency spectrum of the vibration signal is generated by short-time Fourier transform to identify the abnormal vibration characteristic frequency.

[0032] Specifically, a wavelet transform is used to decompose the vibration signal at multiple scales to obtain the energy distribution of different frequency bands. A short-time Fourier transform is then used to generate a time-frequency spectrum to identify the characteristic frequencies of abnormal vibrations. This precise extraction of vibration signal characteristics provides a reliable basis for torque compensation, facilitates the timely detection of combustion anomalies or mechanical failures, and enhances the system's fault identification capabilities.

[0033] When the generator enters torque control mode, it also includes: The generator speed increase gradient limit is calibrated based on the deviation between the starting target drag speed and the actual speed of the range extender, as well as the actual engine temperature; When the speed deviation is greater than the preset value, the speed gradient limit is increased linearly in stages.

[0034] Specifically, the generator speed ramp limit is calibrated based on the deviation between the starting target speed and the range extender's actual speed, as well as the actual engine temperature. When the speed deviation exceeds the preset value, the ramp limit is linearly increased in stages. This avoids torque shock caused by sudden speed changes, while ensuring smooth starting and dynamically adjusting the response speed based on the operating conditions, optimizing starting efficiency.

[0035] The setting of the injection ignition speed threshold is also based on the power battery SOC, including: When the SOC is higher than the third threshold, the fuel injection ignition speed threshold is the first preset value; When the SOC is lower than the third threshold, the fuel injection ignition speed threshold is a second preset value, and the first preset value is greater than the second preset value; The third threshold is 40%, the first preset value is 800 rpm, and the second preset value is 600 rpm; The logic of the threshold setting is: When SOC>40%, the battery discharge capacity is sufficient, and a higher injection ignition speed of 800rpm is used to shorten the starting time and improve responsiveness; When SOC is ≤ 40%, the fuel injection and ignition speed is reduced to 600 rpm to reduce starting energy consumption. At the same time, combustion stability is improved by advancing fuel injection and ignition to compensate for the reduction in drag torque caused by insufficient battery power. The injection ignition speed threshold value also needs to be corrected in combination with the actual engine temperature T. The correction formula is: When T<0℃, If SOC>40%, the injection ignition speed threshold is corrected to: ; If SOC≤40%, the injection ignition speed threshold is corrected to: ; When T≥0℃, the original threshold remains unchanged.

[0036] Specifically, in the engine starting control of extended-range electric vehicles, adjusting the starting target drag speed based on the battery state and correcting the injection ignition threshold based on SOC and temperature form a synergistic mechanism to jointly optimize the energy consumption and reliability of the starting process. Both use the power battery SOC as the core input parameter, but the control dimensions and action stages are different: the former reduces the battery discharge demand by lowering the target speed, while the latter compensates for insufficient torque by pre-ignition threshold. For example, under low SOC conditions, the "speed reduction" and "pre-ignition" strategies are executed simultaneously to reduce the starting energy consumption demand and compensate for the torque drop by improving combustion stability. The connection between the two is that the target speed adjustment directly affects the generator drag power demand, while the ignition threshold correction determines the timing of combustion intervention. The two need to be dynamically matched to avoid ignition failure due to too low speed or incomplete combustion due to ignition too early.

[0037] The step of collecting the engine vibration signal in real time and adjusting the torque compensation amount further includes: Establish a vibration model database of historical starting data, which stores the corresponding relationship between vibration characteristics and torque compensation under different engine temperatures, power battery SOC and starting target speed conditions; The real-time vibration signal is analyzed in the time-frequency domain to extract features, which are then matched with the vibration features in the database to find the historical vibration model with the highest similarity. Generate a predicted value based on the torque compensation amount corresponding to the matched historical vibration model, and fuse it with the real-time calculated compensation amount through the Kalman filter algorithm to obtain the final compensation amount used to adjust the generator torque; Among them, vibration feature matching uses Euclidean distance to calculate similarity, and Kalman filtering realizes data fusion through recursive calculation of state prediction and observation update.

[0038] Specifically, a historical model database was established to store the correspondence between vibration characteristics and torque compensation under different operating conditions. Real-time vibration characteristics were matched with the database to generate predicted compensation values, which were then fused with the real-time calculated compensation values ​​through a Kalman filter. Leveraging historical data and intelligent algorithms, this approach improves the adaptability and accuracy of torque compensation under non-calibrated operating conditions, reduces the impact of sensor noise, makes torque compensation more stable, and expands the system's application range.

[0039] An engine starting control system for an extended-range electric vehicle, comprising: An operating information acquisition module is configured to obtain operating information of the range-extended electric vehicle, wherein the operating information includes actual engine temperature, actual speed of the range extender, state of charge (SOC) of the power battery, and maximum dischargeable power; A control mode switching module is configured to control the generator to enter a torque control mode and the engine to enter a starting mode when the engine start request flag is set; A pre-control torque generation module is configured to activate the pre-control torque of the generator based on the actual engine temperature and the actual speed of the range extender through an enable flag, and query the pre-control torque calibration table to obtain a corresponding torque value; A PID closed-loop control module is configured to perform low-pass filtering based on the deviation between the actual speed of the range extender and the starting target drag speed, use the filtered deviation as the input of the PID controller, perform closed-loop control of the generator torque, and determine the starting control torque in combination with the pre-control torque; The fuel injection and ignition control module is configured to control the EMS to inject fuel and ignite the engine when the actual engine speed reaches the fuel injection and ignition speed threshold; a mode conversion determination module configured to control the engine to enter a running mode and complete starting when the actual engine speed is greater than the starting target speed; The vibration signal processing module is configured to collect the engine vibration signal in real time during the starting process and adjust the compensation amount of the generator torque based on the vibration signal characteristics.

[0040] Specifically, the operating information acquisition module acquires data from multiple sources; the control mode switching module executes generator and engine mode switching; the pre-control torque generation module uses a built-in calibration table for lookup calculations; the PID closed-loop control module implements deviation processing and torque limiting; the injection and ignition control module executes ignition logic through the EMS; the mode transition determination module triggers state switching based on the speed signal; and the vibration signal processing module collects signals and performs analysis and compensation. These modules work together through a bus to meet the high real-time requirements of the starting process.

[0041] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for controlling engine start of an extended-range electric vehicle, characterized in that: The following steps are involved: Acquiring operating information of the range-extended electric vehicle, the operating information including actual engine temperature, actual range extender speed, power battery state of charge (SOC), and maximum dischargeable power; When the engine start request flag is set, the generator is controlled to enter the torque control mode and the engine enters the start mode; Based on the actual engine temperature and the actual speed of the range extender, the pre-control torque of the generator is activated by the enable flag; The deviation between the actual speed of the range extender and the starting target drag speed is low-pass filtered, and the filtered deviation is used as the input of the PID controller to perform closed-loop control of the generator torque, and the starting control torque is determined in combination with the pre-control torque; When the actual engine speed reaches the injection and ignition speed threshold, the EMS is controlled to inject fuel and ignite the engine; When the actual engine speed is greater than the starting target speed, the engine is controlled to enter the running mode and the starting is completed; During the starting process, the engine vibration signal is collected in real time, and the compensation amount of the generator torque is adjusted based on the vibration signal characteristics.

2. The engine start control method of an extended-range electric vehicle according to claim 1, characterized in that: The pre-control torque is set based on the actual engine temperature and the actual speed of the range extender, including: Obtaining a corresponding torque value by querying a pre-control torque calibration table, wherein the calibration table is pre-established based on the actual engine temperature and the actual speed of the range extender; The process of establishing the calibration table includes: In different actual engine temperature ranges, bench tests are conducted to obtain the minimum drag torque of the range extender at different actual speeds. Performing temperature compensation correction on the minimum drag torque to generate a corrected pre-control torque value; The temperature range, speed range and pre-control torque value are stored correspondingly to form a two-dimensional calibration table.

3. The engine start control method of an extended-range electric vehicle according to claim 1, characterized in that: The PID closed-loop control of the generator torque includes: The torque calculated by the Kp term and the Ki term of the PID controller is respectively limited to a maximum torque and a minimum torque, and the limit values ​​are calibrated by bench tests; The PID closed-loop torque is added to the offset of the pre-control torque to generate the starting control torque.

4. The engine start control method of an extended-range electric vehicle according to claim 1, characterized in that: The method for determining the starting target drag speed includes: When the power battery SOC is lower than a first threshold, reducing the starting target drag speed; When the maximum dischargeable power of the power battery is lower than the second threshold, the starting target drag speed is corrected by a piecewise interpolation method; The threshold setting basis is: First threshold: When the SOC is lower than 30%, the battery's internal resistance increases significantly, and the discharge capacity decreases. Lowering the target speed can reduce starting power consumption and avoid battery over-discharge. Second threshold: Based on the typical power requirements of the extended-range system, when the maximum discharge power of the battery is less than 50kW, it cannot meet the starting requirements at the basic target speed of 1500rpm and needs to be dynamically adjusted through interpolation.

5. The engine start control method of an extended-range electric vehicle according to claim 1, characterized in that: The collecting of the engine vibration signal and adjusting the torque compensation amount includes: Vibration signals are collected in real time through the acceleration sensor installed on the engine cylinder; Perform time-frequency domain analysis on the vibration signal to extract the combustion vibration frequency component and the mechanical vibration frequency component; When the amplitude of the combustion vibration frequency component exceeds a preset threshold, reducing the generator torque compensation amount; When the mechanical vibration frequency component is abnormal, the torque compensation amount is increased to suppress resonance.

6. The engine start control method of an extended-range electric vehicle according to claim 5, characterized in that: The time-frequency domain analysis of the vibration signal includes: Wavelet transform is used to perform multi-scale decomposition of vibration signals to obtain energy distribution in different frequency bands; The time-frequency spectrum of the vibration signal is generated by short-time Fourier transform to identify the abnormal vibration characteristic frequency.

7. The engine start control method of an extended-range electric vehicle according to claim 1, characterized in that: When the generator enters torque control mode, it also includes: The generator speed increase gradient limit is calibrated based on the deviation between the starting target drag speed and the actual speed of the range extender, as well as the actual engine temperature; When the speed deviation is greater than the preset value, the speed gradient limit is increased linearly in stages.

8. The engine start control method for an extended-range electric vehicle according to claim 1, characterized in that: The setting of the injection ignition speed threshold is also based on the power battery SOC, including: When the SOC is higher than the third threshold, the fuel injection ignition speed threshold is the first preset value; When the SOC is lower than the third threshold, the fuel injection ignition speed threshold is a second preset value, and the first preset value is greater than the second preset value; The third threshold is 40%, the first preset value is 800 rpm, and the second preset value is 600 rpm; The logic of the threshold setting is: When SOC>40%, the battery discharge capacity is sufficient, and a higher injection ignition speed of 800rpm is used to shorten the starting time and improve responsiveness; When SOC is ≤ 40%, the fuel injection and ignition speed is reduced to 600 rpm to reduce starting energy consumption. At the same time, combustion stability is improved by advancing fuel injection and ignition to compensate for the reduction in drag torque caused by insufficient battery power. The injection ignition speed threshold also needs to be corrected in combination with the actual engine temperature T. The correction formula is: When T<0℃, If SOC>40%, the injection ignition speed threshold is corrected to: ; If SOC≤40%, the injection ignition speed threshold is corrected to: ; When T≥0℃, the original threshold remains unchanged.

9. The engine start control method of an extended-range electric vehicle according to claim 1, characterized in that: The step of collecting the engine vibration signal in real time and adjusting the torque compensation amount further includes: Establish a vibration model database of historical starting data, which stores the corresponding relationship between vibration characteristics and torque compensation under different engine temperatures, power battery SOC and starting target speed conditions; The real-time vibration signal is analyzed in the time-frequency domain to extract features, which are then matched with the vibration features in the database to find the historical vibration model with the highest similarity. Generate a predicted value based on the torque compensation amount corresponding to the matched historical vibration model, and fuse it with the real-time calculated compensation amount through the Kalman filter algorithm to obtain the final compensation amount used to adjust the generator torque; Among them, vibration feature matching uses Euclidean distance to calculate similarity, and Kalman filtering realizes data fusion through recursive calculation of state prediction and observation update.

10. An engine starting control system for an extended-range electric vehicle, characterized in that: A method for controlling engine start of an extended-range electric vehicle according to any one of claims 1 to 9, comprising: An operating information acquisition module is configured to obtain operating information of the range-extended electric vehicle, wherein the operating information includes actual engine temperature, actual speed of the range extender, state of charge (SOC) of the power battery, and maximum dischargeable power; A control mode switching module is configured to control the generator to enter a torque control mode and the engine to enter a starting mode when the engine start request flag is set; A pre-control torque generation module is configured to activate the pre-control torque of the generator based on the actual engine temperature and the actual speed of the range extender through an enable flag, and query the pre-control torque calibration table to obtain a corresponding torque value; A PID closed-loop control module is configured to perform low-pass filtering based on the deviation between the actual speed of the range extender and the starting target drag speed, use the filtered deviation as the input of the PID controller, perform closed-loop control of the generator torque, and determine the starting control torque in combination with the pre-control torque; The fuel injection and ignition control module is configured to control the EMS to inject fuel and ignite the engine when the actual engine speed reaches the fuel injection and ignition speed threshold; a mode conversion determination module configured to control the engine to enter a running mode and complete starting when the actual engine speed is greater than the starting target speed; a vibration signal processing module configured to collect engine vibration signals in real time during the starting process and adjust the compensation amount of the generator torque based on the characteristics of the vibration signals; The pre-control torque calibration table, the starting target drag speed, the method for determining the injection ignition speed threshold, and the vibration signal processing method are all implemented according to the methods described in claims 1-9.

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