Vehicle state test simulation method for new energy vehicle

Abstract

The invention relates to the technical field of simulation testing, and discloses a vehicle state test simulation method for a new energy vehicle, and the method comprises the steps: building a hardware-in-the-loop test bench comprising a VCU HIL, a BMS HIL and an MCU motor controller, and connecting a system power supply, a frequency conversion cabinet, a motor, a dynamometer and a bidirectional power supply according to the real vehicle topology; the system is initialized to a vehicle flameout state, and an ICM ignition control module is set to be at an OFF gear; a hardware-in-the-loop test system is constructed to completely simulate a whole vehicle high-voltage power-on and power-off process, accurate reproduction of real vehicle operation conditions is achieved, it is guaranteed that the test process can comprehensively cover various working states of a high-voltage system, meanwhile, a multi-controller collaborative wake-up and self-inspection mechanism is adopted, the reliability of the system initialization state is guaranteed, and the test efficiency is improved. The test deviation caused by the abnormal initial state is avoided, and the accuracy and consistency of the test result are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of simulation testing, in particular to a vehicle state test simulation method for new energy vehicles. BACKGROUND

[0002] With the progress and development of science and technology, automobiles have become more and more common in people's daily life. With the improvement of people's environmental awareness, new energy vehicles have also developed rapidly. People's requirements for new energy vehicles in terms of safety, comfort, driving, energy consumption and entertainment will also be higher and higher, thus putting forward higher production standards for automobile manufacturers.

[0003] In the current hardware-in-the-loop test field of new energy vehicles, the high-voltage system of the vehicle involves the cooperative work of multiple controllers. When the whole vehicle high-voltage power-on and power-off state simulation test is carried out, the hardware-in-the-loop system is difficult to accurately reproduce the dynamic electrical characteristics of the real vehicle high-voltage loop. When the voltage rising slope in the pre-charging process or the voltage decay characteristics in the power-off process deviate from the actual working condition, it will cause the mismatch between the relay action timing and the electrical state, and may cause misjudgment of faults such as pre-charging timeout and contactor sticking.

[0004] Therefore, the present application provides a vehicle state test simulation method for new energy vehicles to solve the above problems. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a vehicle state test simulation method for new energy vehicles to solve the problems of voltage decay characteristics deviating from actual working conditions, mismatch between relay action timing and electrical state, pre-charging timeout, and misjudgment of faults such as contactor sticking.

[0006] To achieve the above purpose, the present application provides the following technical solutions: a vehicle state test simulation method for new energy vehicles, which uses a hardware-in-the-loop system to simulate the whole vehicle high-voltage power-on and power-off process, comprising the following steps: A hardware-in-the-loop test bench containing VCU HIL, BMS HIL and MCU motor controller is built, and the system power supply, frequency conversion cabinet, motor, dynamometer and bidirectional power supply are connected according to the real vehicle topology; Initialize the system to the vehicle off state, and set the ICM ignition control module to OFF gear; Switch the key knob from OFF gear to ON gear, trigger the wake-up and self-checking program of VCU, BMS, MCU, DCDC and EAC; Verify the preconditions for raising high-voltage electricity: simulate the vehicle stationary state, gear in P / N gear, brake pedal valid signal, no charging gun connection signal and no fault in high-voltage interlocking; Switch the key knob from ON to START, VCU sends high voltage power-on command to BMS; BMS closes the main negative relay, pre-charge relay in turn, and closes the main positive relay and disconnects the pre-charge relay when detecting that the motor bus voltage and battery pack voltage difference ≤5%; When the BMS feedbacks the high voltage power-on completion state, the system enters the Ready drivable state; Switch the key knob from ON to OFF, VCU controls the torque output to zero and turns off the high voltage accessories; BMS executes high voltage power-off sequence: disconnect main negative relay → disconnect main positive relay → feedback relay status; VCU sends active discharge command to MCU, and when detecting that the DC-link voltage drops to below 60V or lasts for 5 seconds, controls each controller to enter sleep mode.

[0007] Preferably, the built-up includes a hardware-in-the-loop test bench of VCU HIL, BMS HIL and MCU motor controller, specifically including: Establish CAN bus communication protocol between VCU HIL and BMS HIL, transmission rate is 500kbps; Configure the torque response delay of MCU motor controller and dynamometer ≤10ms; Parallel high-precision voltage sensors at the output end of the bidirectional power supply, sampling frequency ≥1kHz; Increase CAN FD protocol redundant channel, set double communication time window synchronization mechanism, when the main channel delay >2ms, automatically switch to standby channel; Deploy temperature compensation circuit between frequency conversion cabinet and motor to eliminate signal drift error ±0.5% under large current working condition.

[0008] Preferably, the wake-up and self-checking procedure includes: VCU performs internal control strategy self-checking after waking up, completion time is 200±50ms; BMS self-checking includes battery cell voltage uniformity detection, tolerance range ±20mV; MCU self-checking includes IGBT gate drive circuit diagnosis, fault code feedback delay ≤5ms; DCDC self-checking increases soft start current climbing rate detection, slope threshold is set to 20A / ms; EAC self-checking verifies the sealing property of refrigerant circulation pipeline through pulse pressure sensor, leakage rate threshold ≤0.5kPa / s.

[0009] Preferably, the closing of the main positive relay and the disconnection of the pre-charge relay includes: The main negative relay is closed to start the pre-charge timer, and the timeout threshold is set to 500 ms; The voltage rise slope is calculated in real time during the pre-charge process: ; wherein, Kv is the voltage rise slope, ΔV is the voltage change, Δt is the time change, ≥ 5 V / ms needs to be maintained; The main positive relay is closed when the bus voltage reaches 95% of the battery pack voltage; An abnormal slope processing mechanism is established: if Kv is < 3 V / ms for 3 consecutive sampling periods, it is determined that the pre-charge resistor is invalid and the power-up process is interrupted; The contactor arc detection is started after the main positive relay is closed, and the opening and closing integrity is confirmed through high-frequency current ripple analysis.

[0010] Preferably, the high-voltage power-down sequence comprises: The voltage drop monitoring window is started after the main negative relay is opened; The voltage decay characteristics are verified by a second-order RC circuit model: ; wherein, V(t) is the voltage at time t, V0 is the initial voltage, t is the time, τ is the time constant, and the time constant ≤ 0.5 s needs to be maintained; The contactor state is fed back to the VCU when the voltage drops to the safety threshold; The contactor breaking action feedback loop is increased: a Hall current sensor is used to verify the actual opening timing of the relay contact, and a fault code is triggered when the deviation from the command is > 5 ms; A residual charge discharge circuit is set at the high-voltage bus end, and the discharge resistance is optimized to 50 Ω ± 5%.

[0011] Preferably, the active discharge comprises: The voltage-time double-judgment condition is set: DC-link voltage ≤ 60 V or discharge duration of 5 seconds; The discharge power control function is constructed:

[0012] wherein, P is the real-time discharge power, K is the heat dissipation coefficient, V is the DC-link voltage, Vsafe is the safety threshold voltage, which is fixed at 60 V; De-rate mode is activated when the MCU temperature exceeds 105℃; Increase temperature-power coupling adjustment: dynamically correct k value according to IGBT junction temperature, k value decreases by 15% for every 10℃ increase in junction temperature; Deploy multi-stage discharge path: automatically switch to backup discharge resistor circuit when the main discharge circuit fails, with a switching delay of ≤10ms.

[0013] Preferably, it also includes a fault injection test step: Inject a pre-charge resistor open-circuit fault during the pre-charge phase to verify that the BMS can cut off the relay within 20ms; Simulate high-voltage interlock disconnection event, detect VCU power-down command response delay ≤100ms; Inject IGBT short-circuit fault during active discharge process to verify that the fuse operates within 1ms; Add multi-node fault interlocking test: trigger pre-charge timeout + voltage slope anomaly + contactor sticking composite fault simultaneously to verify the response priority of the system's layered protection mechanism; Build a fault tree database: store feature parameters and expected response time matrix for ≥50 fault modes.

[0014] Preferably, it also includes a safety protection mechanism: Set a spark gap device between the positive and negative poles of the DC-link, with a breakdown voltage of 800V; Activate the backup discharge circuit when a relay sticking fault is detected; Ensure electrical isolation between BMS HIL and power hardware through an opto-isolating module; Increase electromagnetic compatibility design: install a common-mode choke on the CAN bus to suppress radiation interference in the ≥100MHz frequency band; Deploy a real-time watchdog circuit: if the heartbeat signal is lost for 3 consecutive communication cycles, forcibly cut off the power stage power supply.

[0015] Preferably, the hardware-in-the-loop system needs to meet the following collaborative indicators: High-voltage power-up completion time from key START signal to Ready light turning on ≤800ms; Voltage synchronization accuracy requires that the bus voltage and battery pack voltage deviation be sustained at ≤3%; Contactor breaking timing error ≤10ms during power-off process; Fault injection coverage: achieve the random hardware fault target coverage defined by ISO 26262 ASIL-D level, including single-point fault and latent fault automatic injection verification; Timing synchronization accuracy: clock deviation between controllers ≤100μs, using IEEE 1588v2 precision time protocol synchronization.

[0016] Preferably, it also includes a cloud verification mechanism: Upload test data to the cloud platform through the OPC UA protocol; Establish a time series data correlation analysis model: Among them, is the system health score, is the dynamic optimization coefficient, is the power-on time, is the dynamic optimization coefficient, is the voltage fluctuation integral value, is the dynamic optimization coefficient, is the fault injection pass rate; When the health score is lower than the threshold, automatically trigger the retest sequence; Add a blockchain storage module: use the SHA-256 algorithm to encrypt the key test node data and chain it, with a storage interval ≤200ms; Deploy a digital twin comparison engine: automatically mark working conditions with a deviation of >15% between measured data and ideal model as an optimization candidate set.

[0017] (Three) beneficial effects Compared with the prior art, the present application provides a vehicle state test simulation method for new energy vehicles, which has the following beneficial effects: 1. In the present application, when simulating the vehicle state test of a new energy vehicle, a hardware-in-the-loop test system is constructed to completely simulate the high-voltage power-on and power-off process of the whole vehicle, accurately reproducing the real vehicle operating conditions, ensuring that the test process can cover all types of working states of the high-voltage system, and at the same time using a multi-controller cooperative wake-up and self-checking mechanism to ensure the reliability of the system initialization state, avoiding test deviations caused by abnormal initial state, and improving the accuracy and consistency of the test results.

[0018] 2. In the present application, when simulating the vehicle state test of a new energy vehicle, a dynamic timing control model of the high-voltage power-on and power-off process is established to monitor the voltage change slope and decay characteristics in real time, ensuring that the relay action timing and electrical state are strictly matched, so that the system can accurately identify fault states such as pre-charge abnormalities and contactor sticking, and immediately trigger a correction mechanism when a timing deviation is detected, ensuring the accuracy and safety of the high-voltage loop control process.

[0019] ​3. In the present application, when performing new energy vehicle state test simulation, multi-modal fault injection and safety protection mechanism are introduced to support single fault and composite fault automatic test, verify the effectiveness of system fault response and protection strategy, enable the system to evaluate the processing capacity of the controller in real time when injecting faults, enhance the detection coverage of high-voltage system safety risks, and provide sufficient basis for vehicle safety and reliability evaluation. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 A flowchart of a vehicle state test simulation method for a new energy vehicle. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0022] Specific embodiment: a vehicle state test simulation method for a new energy vehicle, which uses a hardware-in-the-loop system to simulate the whole vehicle high-voltage power-on and power-off process, including the following steps: A hardware-in-the-loop test bench containing VCU HIL, BMS HIL and MCU motor controller is built, and the system power supply, frequency conversion cabinet, motor, dynamometer and bidirectional power supply are connected according to the real vehicle topology; Initialize the system to the vehicle off state, and set the ICM ignition control module to the OFF gear; Switch the key knob from the OFF gear to the ON gear to trigger the wake-up and self-checking procedures of VCU, BMS, MCU, DCDC and EAC; Verify the preconditions for high-voltage power-on: simulate the vehicle stationary state, gear in P / N gear, brake pedal valid signal, no charging gun connection signal and no fault in high-voltage interlocking; Switch the key knob from the ON gear to the START gear, and the VCU sends a high-voltage power-on command to the BMS; The BMS closes the main negative relay, the pre-charging relay in turn, and closes the main positive relay and disconnects the pre-charging relay when detecting that the difference between the motor bus voltage and the battery pack voltage is ≤5%; After the BMS feedbacks the high-voltage power-on completion state, the system enters the Ready drivable state; Switch the key knob from the ON gear to the OFF gear, and the VCU controls the torque output to zero and turns off the high-voltage accessories; The BMS executes the high-voltage power-off sequence: disconnect the main negative relay → disconnect the main positive relay → feedback the relay state; VCU sends active discharge instruction to MCU, when detecting that the DC-link voltage drops below 60V or lasts for 5 seconds, the control of each controller enters sleep mode.

[0023] A hardware-in-the-loop test bench including VCU HIL, BMS HIL and MCU motor controller is built, specifically including: A CAN bus communication protocol is established between VCU HIL and BMS HIL, and the transmission rate is 500kbps; The torque response delay of the MCU motor controller and the dynamometer is configured to be ≤10ms; A high-precision voltage sensor is connected in parallel at the output end of the bidirectional power supply, and the sampling frequency is ≥1kHz; A CAN FD protocol redundant channel is added, and a double-channel communication time window synchronization mechanism is set, which automatically switches to the standby channel when the main channel delay is >2ms; A temperature compensation circuit is deployed between the frequency conversion cabinet and the motor to eliminate signal drift error ±0.5% under large current working conditions.

[0024] The system is initialized to the vehicle off state, and the ICM ignition control module is set to OFF gear, including: Send a global reset command through the control software of the test bench to set all controllers to sleep or standby mode, simulate the static working condition when the vehicle key is not inserted, which involves clearing all historical fault codes and temporary data to ensure that the system memory is zero; The virtual gear of the ICM is forcibly set to OFF position, which is realized through the configuration interface of the HIL test bench; During the initialization process, all high-power devices are turned off synchronously, and the bidirectional power supply output is set to zero voltage state to ensure no residual current interference at the test starting point; The wake-up and self-checking program includes: After the VCU wakes up, it performs internal control strategy self-checking, and the completion time is 200±50ms; BMS self-checking includes battery monomer voltage uniformity detection, tolerance range ±20mV; MCU self-checking includes IGBT gate drive circuit diagnosis, and fault code feedback delay ≤5ms; The DCDC self-checking adds soft start current ramp rate detection, and the slope threshold is set to 20A / ms; During EAC self-checking, the pulse pressure sensor is used to verify the sealing performance of the refrigerant circulation pipeline, and the leakage rate threshold is ≤0.5kPa / s.

[0025] Verification of high-voltage prepositioning includes: Simulate the vehicle static state, send the vehicle speed signal to the VCU through the HIL bench, and verify that the vehicle dynamic model is in static mode.

[0026] Gear state confirmation, set virtual gear lever to P or N position, MCU controller feedback gear signal to CAN bus.

[0027] Brake pedal effectiveness check, activate brake pedal simulator, generate effective signal ≥ 50% stroke, ensure VCU receives and confirms the input.

[0028] Charging gun connection detection, simulate no external charging gun insertion event, BMS continuously monitors the charging interface state, outputs "no connection" flag.

[0029] High voltage interlock troubleshooting: run interlock loop self-diagnosis program, check all high voltage connectors for open or short circuit faults.

[0030] Switch the key knob from ON to START, VCU sends high voltage power-on command to BMS, including: Key state switching, rotate the ICM ignition module from ON to START, generate a start pulse signal.

[0031] VCU instruction sending, VCU analyzes the START signal and sends a high voltage power-on command to BMS through the CAN bus.

[0032] BMS reception and response, BMS confirms the validity of the command, starts the relay control sequence, including main negative relay closure.

[0033] Pre-charge process monitoring, under BMS control, pre-charge relays are closed in sequence, and bus voltage changes are monitored in real time High voltage power-on sequence includes: After the main negative relay is closed, start the pre-charge timer, the timeout threshold is set to 500ms; Real-time calculation of voltage rise slope during pre-charge process: ; Where, Kv is the voltage rise slope, ΔV is the voltage change, Δt is the time change, ≥ 5V / ms needs to be maintained; When the bus voltage reaches 95% of the battery pack voltage, trigger the main positive relay closure; Establish a slope anomaly handling mechanism: if Kv is < 3V / ms for 3 consecutive sampling periods, determine that the pre-charge resistor is invalid and interrupt the power-on process; After the main positive relay is closed, start the contactor arc detection, confirm the complete opening and closing integrity through high-frequency current ripple analysis.

[0034] When the BMS feedbacks the high-voltage power-on completion state, the system enters the Ready drivable state, including: BMS state feedback: After the relay action sequence is completed, the BMS sends a "high-voltage power-on completion" state signal to the VCU.

[0035] System mode switching: The VCU analyzes the state signal and controls the vehicle to enter the Ready mode, including the instrument panel Ready light turning on.

[0036] Running state verification: Monitor key parameters.

[0037] Output zeroing and closing of high-voltage accessories, including: Key state switching: Rotate the ICM ignition module from the ON gear to the OFF gear to generate a power-down request signal.

[0038] VCU control instruction: After the VCU receives the OFF signal, immediately send a torque zeroing instruction to the MCU and close all high-voltage accessories.

[0039] Accessory state confirmation: Verify the accessory closed state, such as setting the air conditioner compressor drive request to "OFF".

[0040] Power-down sequence preparation: VCU sends a high-voltage power-down preparation instruction to the BMS to start the subsequent relay disconnection process.

[0041] High-voltage power-down sequence includes: Start voltage drop monitoring window after the main negative relay is disconnected; Verify voltage decay characteristics through a second-order RC circuit model: ; Where, is the voltage at time t, is the initial voltage, is the time, is the time constant, and the time constant should be ≤0.5s; When the voltage drops to the safety threshold, feedback the contactor state to the VCU; Add contactor disconnection action feedback closed loop: Use a Hall current sensor to verify the actual relay contact opening time sequence, and trigger a fault code when the deviation from the instruction is >5ms; Set a residual charge discharge circuit at the high-voltage bus end, and optimize the discharge resistance value to 50Ω±5%.

[0042] Active discharge control includes: Set voltage-time double judgment conditions: DC-link voltage ≤60V or discharge for 5 seconds; Build a discharge power control function:

[0043] wherein, P is the real-time discharge power, K is the heat dissipation coefficient, V is the DC-link voltage, V is the safety threshold voltage, fixed at 60V; Start the derating mode when the MCU temperature exceeds 105℃; Increase the temperature-power coupling adjustment: dynamically modify the k value according to the IGBT junction temperature, and the k value decreases by 15% for every 10℃ increase in junction temperature; Deploy multiple discharge paths: automatically switch to the backup braking resistor circuit when the main discharge circuit fails, with a switching delay of ≤10ms.

[0044] Also includes fault injection test steps: Inject a pre-charge resistor open circuit fault during the pre-charge phase to verify that the BMS can cut off the relay within 20ms; Simulate a high-voltage interlock disconnection event to detect the response delay of the VCU power-off command ≤100ms; Inject an IGBT short circuit fault during active discharge to verify that the fuse operates within 1ms; Add multi-node fault interlocking test: trigger pre-charge timeout + voltage slope anomaly + contactor sticking composite fault simultaneously to verify the response priority of the system's layered protection mechanism; Build a fault tree database: store the characteristic parameters and expected response time matrix of ≥50 fault modes.

[0045] Also includes safety protection mechanisms: Set a spark gap device between the positive and negative poles of the DC-link, with a breakdown voltage of 800V; Activate the backup discharge circuit when a relay sticking fault is detected; Ensure electrical isolation between the BMS HIL and power hardware through an opto-isolating module; Increase electromagnetic compatibility design: install a common-mode choke on the CAN bus to suppress radiation interference in the ≥100MHz frequency band; Deploy a real-time watchdog circuit: if the heartbeat signal is lost for 3 consecutive communication cycles, forcibly cut off the power stage power supply.

[0046] The hardware-in-the-loop system must meet the following collaborative indicators: High-voltage power-up completion time from key START signal to Ready light turning on ≤800ms; Voltage synchronization accuracy requires that the bus voltage and battery pack voltage deviation be sustained ≤3%; Contactor breaking timing error ≤10ms in the power-off process; Fault injection coverage index: achieve the random hardware fault target coverage defined by ISO 26262 ASIL-D level, including single point fault and automatic injection verification of latent fault; Timing synchronization accuracy: clock deviation between controllers ≤100μs, using IEEE 1588v2 precision time protocol synchronization.

[0047] Also includes cloud verification mechanism: Upload test data to the cloud platform through the OPC UA protocol; Establish a time series data correlation analysis model: ; Among them, is the system health score, is the dynamic optimization coefficient, is the power-on time, is the dynamic optimization coefficient, is the voltage fluctuation integral value, is the dynamic optimization coefficient, is the fault injection pass rate; When the health score is lower than the threshold, automatically trigger the retest sequence; Add a blockchain storage module: use the SHA-256 algorithm to encrypt the key test node data and chain it, and the hash value generation formula is: ; Among them, is the hash value, is the time series data, is a random number, is a cryptographic hash function; The storage interval is ≤200ms, and the public verification interface is provided through the blockchain browser; Deploy a digital twin comparison engine: calculate the deviation between the measured data and the ideal model: ; Among them, is the deviation index, is the measured value, is the theoretical value, is the reference dimension, is the number of parameters.

[0048] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting; it is not intended to exclude myriad other embodiments of the present application that other inventors can develop based on the same general inventive concepts embodied by the described embodiments. That is, although the present application is described in terms of particular embodiments and implementations, it is to be understood that the terminology used is for the purpose of descriptive clarity and that it is intended to be limited only by the words recited in the appended claims. The scope of the present application shall be limited only by the claims.

[0049] While the embodiments of the application have been shown and described herein, it is to be understood that the application is not limited to these embodiments. Rather, numerous modifications are possible without departing from the spirit and scope of the present application as delineated by the claims and their equivalents.

Claims

1. A vehicle condition testing simulation method for new energy vehicles, characterized in that: The method utilizes a hardware-in-the-loop system to simulate the high-voltage power-on and power-off process of the entire vehicle, including the following steps: A hardware-in-the-loop test bench was built, including VCU HIL, BMS HIL and MCU motor controller, and the system power supply, frequency converter cabinet, motor, dynamometer and bidirectional power supply were connected according to the actual vehicle topology. Initialize the system to the vehicle's off state and set the ICM ignition control module to the OFF position; Switching the key knob from the OFF position to the ON position triggers the wake-up and self-test procedures of the VCU, BMS, MCU, DCDC, and EAC. Verify the high-voltage preconditions: simulate a stationary vehicle, gear in P / N, valid brake pedal signal, no charging gun connection signal, and no high-voltage interlock fault. When the key knob is switched from the ON position to the START position, the VCU sends a high-voltage power-on command to the BMS. The BMS sequentially closes the main negative relay and the pre-charge relay, and when it detects that the difference between the motor bus voltage and the battery pack voltage is ≤5%, it closes the main positive relay and opens the pre-charge relay. Once the BMS reports that the high-voltage power-on is complete, the system enters the Ready and drivable state. Switch the key knob from the ON position to the OFF position. The VCU controls the torque output to zero and shuts off the high-voltage accessories. The BMS executes the high-voltage power-down sequence: disconnect the main negative relay, then disconnect the main positive relay, and finally feedback the relay status; The VCU sends an active discharge command to the MCU. When it detects that the DC-link voltage has dropped below 60V or lasts for 5 seconds, it controls each controller to enter sleep mode.

2. The vehicle condition testing simulation method for new energy vehicles according to claim 1, characterized in that: The construction of the hardware-in-the-loop test bench, which includes VCU HIL, BMS HIL, and MCU motor controller, specifically includes: A CAN bus communication protocol is established between VCU HIL and BMS HIL, with a transmission rate of 500kbps. Configure the torque response delay of the MCU motor controller and dynamometer to ≤10ms; A high-precision voltage sensor with a sampling frequency ≥1kHz is connected in parallel at the bidirectional power supply output. Add redundant channels for the CAN FD protocol and set up a dual-channel communication time window synchronization mechanism to automatically switch to the backup channel when the main channel delay is greater than 2ms. A temperature compensation circuit is deployed between the frequency converter cabinet and the motor to eliminate signal drift error of ±0.5% under high current conditions.

3. The vehicle state testing simulation method for new energy vehicles according to claim 1, characterized in that: The wake-up and self-test procedure includes: After the VCU is woken up, it performs an internal control policy self-test, which takes 200±50ms to complete. BMS self-test includes battery cell voltage balance detection, with a tolerance range of ±20mV; The MCU self-test includes IGBT gate drive circuit diagnosis, and the fault code feedback delay is ≤5ms. The DCDC self-test adds soft-start current creep rate detection, with the slope threshold set to 20A / ms; During EAC self-test, the refrigerant circulation pipeline sealing is verified using a pulse pressure sensor, with a leakage rate threshold of ≤0.5kPa / s.

4. The vehicle state testing simulation method for a new energy vehicle according to claim 1, characterized in that: The closing of the main positive relay and the opening of the precharge relay includes: After the main negative relay is closed, the precharge timer is started, and the timeout threshold is set to 500ms; Real-time calculation of voltage rise slope during pre-charging: ； in, The slope of the voltage rise. This is the change in voltage. For the time change, ≥5V / ms must be maintained; The main positive relay is triggered to close when the bus voltage reaches 95% of the battery pack voltage. Establish an abnormal slope handling mechanism: if Kv is less than 3V / ms for 3 consecutive sampling periods, the pre-charge resistor is determined to be faulty and the power-on process is interrupted. After the main positive relay closes, the contactor arc detection is activated, and the integrity of opening and closing is confirmed through high-frequency current ripple analysis.

5. The vehicle state testing simulation method for a new energy vehicle according to claim 1, characterized in that: The high-voltage power-down sequence includes: The voltage drop monitoring window is activated after the main negative relay is disconnected. Verify the voltage attenuation characteristics using a second-order RC circuit model: ； in, Let be the voltage at time t. The initial voltage, For time, The time constant. Requires ≤0.5s; When the voltage drops to the safety threshold, the contactor status is fed back to the VCU; Add a closed-loop feedback mechanism for contactor disconnection: Use a Hall current sensor to verify the actual disconnection timing of the relay contacts, and trigger a fault code when the deviation from the command is greater than 5ms; A residual charge discharge circuit is installed at the high-voltage bus end, and the discharge resistor value is optimized to 50Ω±5%.

6. The vehicle state testing simulation method for a new energy vehicle according to claim 1, characterized in that: The active discharge includes: Set dual voltage-time judgment conditions: DC-link voltage ≤ 60V or discharge duration 5 seconds; Construct the discharge power control function: in, For real-time discharge power, For heat dissipation coefficient, DC-link voltage, The safety threshold voltage is fixed at 60V. Derating mode is activated when the MCU temperature exceeds 105°C. Increased temperature-power coupling regulation: The k-value is dynamically adjusted based on the IGBT junction temperature, decreasing by 15% for every 10°C increase in junction temperature; Deploy multi-stage discharge paths: When the main discharge circuit fails, it automatically switches to the backup circuit of the braking resistor with a switching delay of ≤10ms.

7. The vehicle state testing simulation method for a new energy vehicle according to claim 1, characterized in that: It also includes fault injection testing steps: An open-circuit fault in the pre-charge resistor was injected during the pre-charge phase to verify that the BMS could cut off the relay within 20ms. Simulate a high-voltage interlock disconnection event and detect a VCU power-down command response delay of ≤100ms; Injecting an IGBT short-circuit fault during active discharge verifies that the fuse action time is ≤1ms. Added multi-node fault interlocking test: synchronously triggering precharge timeout + abnormal voltage slope + contactor adhesion composite fault to verify the response priority of the system's hierarchical protection mechanism; Construct a fault tree database: store the feature parameters and expected response time matrix of ≥50 fault modes.

8. The vehicle state testing simulation method for a new energy vehicle according to claim 1, characterized in that: It also includes security protection mechanisms: A spark gap device is installed between the positive and negative terminals of the DC-link, and the breakdown voltage is set to 800V; When a relay sticking fault is detected, the backup discharge circuit is activated. Electrical isolation between the BMS HIL and power hardware is ensured through opto-isolation modules; Enhanced electromagnetic compatibility design: A common-mode choke is installed at the CAN bus end to suppress radiated interference in the ≥100MHz frequency band; Deploy a real-time watchdog circuit: if the heartbeat signal is lost for three consecutive communication cycles, the power stage power supply will be forcibly cut off.

9. The vehicle state testing simulation method for a new energy vehicle according to claim 1, characterized in that: The hardware-in-the-loop system must meet the following coordination indicators: The high-voltage power-on completion time from the START signal on the key to the Ready indicator lighting up is ≤800ms; Voltage synchronization accuracy requires that the deviation between the bus voltage and the battery pack voltage be ≤3%; The contactor disconnection timing error during the power-down process is ≤10ms. Fault injection coverage metric: Achieve the target coverage of random hardware faults as defined by ISO 26262 ASIL-D level, including automated injection verification of single-point faults and latent faults; Timing synchronization accuracy: Clock deviation between controllers ≤100μs, synchronized using IEEE 1588v2 precision time protocol.

10. The vehicle state testing simulation method for a new energy vehicle according to claim 1, characterized in that: It also includes a cloud-based verification mechanism: Upload test data to the cloud platform via the OPC UA protocol; Establish a time-series data correlation analysis model: ； in, Score the system's health. For dynamic optimization coefficients, Power-on time, For dynamic optimization coefficients, This is the integral value of the voltage fluctuation. For dynamic optimization coefficients, Injecting a pass rate for faults; When the health score falls below a threshold, a retest sequence is automatically triggered. Add a blockchain evidence storage module: use the SHA-256 algorithm to encrypt and upload key test node data to the blockchain, with an evidence storage interval of ≤200ms; Deploy a digital twin comparison engine: automatically mark working conditions where the deviation between measured data and ideal model is >15% as optimization candidates.

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