Power battery thermal management system based on temperature change

Abstract

The invention relates to the technical field of electric vehicle power battery thermal management, and discloses a temperature change-based power battery thermal management system, which comprises a thermal simulation pre-judgment end, a sensor network end, a dynamic liquid cooling control end, a BMS decision end and a fault diagnosis module, aiming at the technical defects of out-of-control temperature difference, response hysteresis and leakage risk caused by static flow channel design of the existing liquid cooling system, breakthrough is realized through a three-dimensional technical architecture: a CFD (Computational Fluid Dynamics) prejudgment layer: automatically calibrating sensor distribution points based on temperature field standard deviation, and improving temperature difference identification precision; according to the dynamic valve control layer, an electromagnetic three-way reversing valve is adopted to execute a directional temperature control strategy, an edge battery cell is preferentially introduced under the low-temperature working condition, and heat dissipation is enhanced under the high-temperature working condition; according to the redundant safety layer, the valve body and the pipeline are integrally formed, the leakage rate is reduced, and flow maintenance under single-point failure is achieved through a double-water-inlet parallel pump source. The method has the effects of improving the convergence speed of temperature difference between modules, reducing the attenuation rate of battery life and reducing the risk probability of thermal runaway.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric vehicle power battery thermal management, in particular to a power battery thermal management system based on temperature change. BACKGROUND

[0002] The power battery thermal management system is the core subsystem of the energy management of the electric vehicle, which guarantees the battery pack to work in the best temperature interval through the liquid cooling topology optimization and the dynamic temperature control strategy, which is the key technical basis for maintaining the battery capacity retention rate greater than 95%. The high-precision temperature sensor network and the intelligent flow distribution valve jointly constitute the control center of the system, and ensure that the battery pack realizes thermal safety protection in the environment temperature range of-30℃ to 60℃.

[0003] At present, due to the spatiotemporal heterogeneity of the electrochemical reaction in the battery pack, when the module temperature is real-time regulated, the cooling liquid in the cooling pipeline flows through the inside of the battery pack, which cannot dynamically adapt to the local temperature difference. If the temperature difference between the modules appears, it may cause three technical defects: temperature field control misalignment: one-way flow path causes the temperature gradient to accumulate after the cooling liquid flows through the high-temperature area, and the temperature rise of the coolant itself makes the cooling efficiency of the subsequent flowing area decrease by more than 40%, forming a vicious cycle of "hotter hot area, colder cold area"; response mechanism delay: the traditional mechanical valve executes the instruction with a delay of more than 2 seconds, when the central module temperature rises sharply, the hot spot temperature has been overshooted by more than 4℃ after the cooling liquid is pressurized in place, and the irreversible decomposition of SEI film is induced under extreme conditions; fault weakening loss: the flange connection is adopted for the split valve body and the pipeline, the joint leakage rate is more than 2 times per 10,000 hours under vibration working condition, and there is no redundant flow channel design, so that the single point failure directly leads to the temperature loss of control of the local module.

[0004] At the same time, there are double bottlenecks in the execution level of the thermal management strategy: when heating in low temperature environment, the cooling liquid uniformly flows through all the modules, the edge cells are suppressed at a temperature rise rate of less than 0.5℃ / min due to heat loss, which leads to the risk of low temperature lithium precipitation increasing by 300%; when cooling at high rate discharge, the fixed flow distribution mode cannot focus on the high temperature area, and the central module continues to overheat for more than 3 minutes, which accelerates the decomposition of electrolyte.

[0005] Therefore, it is urgent to build a thermal management system with dynamic flow switching capability, multi-mode collaborative control and fault weakening mechanism to break through the above technical bottlenecks. SUMMARY

[0006] In view of the deficiencies of the prior art, the present application provides a power battery thermal management system based on temperature change, which solves the problems raised in the background art.

[0007] To achieve the above purpose, the present application provides the following technical scheme: a power battery thermal management system based on temperature change, comprising the following steps: S1, establish a battery pack multi-dimensional working condition matrix: through CFD simulation, the temperature field distribution of the battery pack under the combined working conditions of high and low temperature environment and charge-discharge rate is calculated, and the temperature rising hot spot and temperature gradient area are identified; S2, optimize sensor arrangement: based on the standard deviation of the temperature field, the sensor arrangement coordinates are automatically calibrated, a multi-temperature sensor network is arranged in the temperature difference area of the battery pack, and the temperature difference between the modules is monitored in real time; S3, build a dynamic liquid cooling topology: according to the simulation results of S1, a liquid cooling pipe topology network is generated, an electromagnetic three-way reversing valve is integrated at the inlet and outlet of the battery pack, and the valve body is integrally formed with the cooling pipe; S4, working condition identification and mode switching: the BMS collects the temperature data of the battery cells in real time, starts the low-temperature heating mode when the minimum temperature T is less than 5℃, starts the high-temperature cooling mode when the maximum temperature T is greater than 45℃, and starts the gradient balancing mode when the temperature difference ΔT is greater than 5℃; S5, dynamic flow control: in the low-temperature heating mode, the reversing valve is controlled to preferentially guide the 40℃ cooling liquid to the low-temperature area battery cell, in the high-temperature cooling mode, the reversing valve is switched to strengthen the heat dissipation of the high-temperature area, and the cooling liquid flow is increased by 35%, and in the gradient balancing mode, the liquid flow path is alternately switched through the reversing valve to realize horizontal heat conduction; S6, redundancy guarantee: a double-inlet combined design is adopted to connect the external parallel pump source, and 50% flow is maintained when a single valve fails; S7, closed-loop control: fusion of voltage and temperature data, through "simulation prediction-real-time monitoring-dynamic adjustment" closed loop to realize heat balance control.

[0008] Preferably, the power battery thermal management system based on temperature change according to claim 2, S1 specifically comprises: S11, build a three-dimensional battery pack fluid mechanics model to simulate fast charging, high-rate discharging and extreme environmental temperature field scenarios; S12, extract the spatio-temporal evolution law of the temperature field, and identify the temperature rising gradient of the cell gap, the surrounding of the heating component and the airflow dead angle; S13, establish a mapping database of environmental temperature, charge-discharge rate and temperature distribution, and update the database every 24 hours.

[0009] Preferably, the power battery thermal management system based on temperature change according to claim 2, the sensor arrangement optimization in S2 comprises: S21, calculate the standard deviation σ of the temperature field, and arrange PT1000 temperature sensors at the corresponding coordinates when σ is greater than 3℃; S22, set embedded micro-groove sensors at the cell gap, and the sampling frequency is greater than 10Hz; S23, the sensor network communicates with the BMS through CAN bus, and the transmission delay is less than 50ms.

[0010] Preferably, the temperature change-based power battery thermal management system according to claim 2, the control logic S3 of the electromagnetic three-way reversing valve is: S31, the valve body integrates a temperature difference monitoring module, which compares the temperature difference between the inlet and outlet in real time; S32, the rotation angle of the valve core is controlled by PWM driving, and the angle resolution is greater than 0.5°; S33, when the detected pipeline pressure difference is greater than 0.2 MPa, the self-cleaning mode is triggered, and the reverse flushing is performed for 30 seconds.

[0011] Preferably, the temperature change-based power battery thermal management system according to claim 2, the low-temperature heating mode S5 specifically comprises: S51, the initial temperature of the cooling liquid is maintained at 40℃; S52, the edge area battery cells are preferentially heated, and the temperature rise rate is greater than 2℃ / min; S53, when the minimum temperature T is greater than 10℃, the heating mode is exited.

[0012] Preferably, the temperature change-based power battery thermal management system according to claim 2, the high-temperature cooling mode S5 specifically comprises: S61, the center module with the fastest temperature rise is identified; S62, the cooling liquid flow is increased from the reference value 5L / min to 7L / min; S63, pulsed flow is used to strengthen heat exchange, and the pulse frequency is 3Hz.

[0013] Preferably, the temperature change-based power battery thermal management system according to claim 1, the gradient balance mode S5 specifically comprises: S71, 5℃ is set as the temperature difference threshold, and the reversing valve is triggered to alternately switch the flow direction with a period of 30 seconds; S72, the temperature difference between the modules is reduced to less than 2℃ through lateral heat conduction; S73, the temperature balance parameters are corrected in combination with the cell voltage data, and the voltage sampling accuracy is 0.5mV.

[0014] Preferably, the temperature change-based power battery thermal management system according to claim 2, the double-inlet design S6 comprises: S81, the two water inlets are combined through a Y-shaped pipeline, and the pipe diameter is Φ8mm; S82, two external pump sources are connected in parallel, and the maximum flow of each pump source is 6L / min; S83, when it is detected that the single-flow rate decreases by more than 40%, the redundant pump source is started.

[0015] Preferably, the temperature change-based power battery thermal management system according to claim 2, the closed-loop control S7 comprises: S91, a temperature-voltage joint evaluation function is established: , Wherein, =0.7, =0.3, is the number of temperature sensors, is the number of cells; S92, When ≥5, trigger system self-check, calibration period is less than 15 minutes.

[0016] Preferably, the system according to any one of claims 1-9, after S7 closed-loop control, add: S8, real-time decision optimization: S811, in the gradient balance mode, collect cell health state data every 5 minutes, the calculation formula is: , Wherein, is the current capacity, is the initial capacity; S812, when The attenuation rate is greater than 0.1% / week, the temperature difference threshold is dynamically reduced from 5℃ to 3℃; S813, when the module voltage range is greater than 50mV, trigger the liquid cooling flow rate to increase by 20% and the flow direction switching period to be shortened to 15 seconds.

[0017] Compared with the prior art, the application provides a temperature change-based power battery thermal management system, which has the following beneficial effects: 1. In the application, by setting the CFD simulation prediction mechanism, when the battery pack temperature field is controlled in real time, a multi-dimensional working condition matrix of environmental temperature and charge-discharge rate is established to predict the thermal field distribution law under different working conditions, ensure the accuracy of temperature difference hot spot identification, and automatically calibrate the sensor distribution coordinates based on the temperature field standard deviation, which can capture the subtle temperature difference changes between modules in real time, ensure the timeliness of battery pack thermal balance control, and further reduce the performance degradation risk caused by temperature gradient accumulation.

[0018] 2. In the present application, by setting up the electromagnetic three-way valve dynamic control system, when switching between high and low temperature working condition mode, through the valve body embedded design and PWM driving control valve core rotation, real-time switching of cooling liquid flow direction makes the system can accurately execute the directional heating and intensified cooling strategy: in low temperature environment, the heat flow is preferentially directed to the edge cell, and the temperature rise rate is improved; in high temperature working condition, the cooling liquid flow is increased dynamically, the duration of the center module over-temperature is shortened, and the battery capacity retention rate is ensured throughout the life cycle.

[0019] 3. In the present application, by setting an integrated valve body-pipeline redundancy architecture, when performing system reliability protection, the flange connection point is eliminated by integrated forming design of the valve body and the cooling pipeline, the joint leakage rate is reduced, and the double inlet Y-type pipeline is used in cooperation with the parallel pump source, so that the flow supply is still maintained when a single point failure occurs, so that the system can avoid local thermal runaway in extreme working conditions, ensure the operation safety of electric vehicles in extremely cold and high temperature environments, and reduce the probability of safety accidents caused by thermal management failure. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is the overall system architecture diagram of the present application; Figure 2 is a schematic diagram of the electromagnetic three-way valve of the present application; Figure 3 is a schematic diagram of the present application for heating the cooling liquid from the slow temperature rise of the cell; Figure 4 is a schematic diagram of the present application for cooling the cooling liquid from the fast temperature rise of the cell. 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, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0022] Please refer to Figures 1-4 The temperature change-based power battery thermal management system comprises the following steps: S1, establishing a multi-dimensional working condition matrix of the battery pack: through CFD simulation calculation of the internal temperature field distribution of the battery pack under the combination of high and low temperature environment and charge-discharge rate, identifying the temperature rise hot spot and temperature gradient area; S2, optimizing sensor arrangement: based on the temperature field standard deviation, automatically calibrating the sensor arrangement coordinates, arranging a multi-temperature sensor network in the temperature difference area of the battery pack, and monitoring the temperature difference between the modules in real time; S3. Build a dynamic liquid cooling topology: Generate a liquid cooling pipeline topology network based on the simulation results of S1. Integrate an electromagnetic three-way reversing valve at the battery pack inlet and outlet, and integrate the valve body and cooling pipeline into an integrated form. S4, working condition identification and mode switching: The BMS collects the battery cell temperature data in real time. When the minimum temperature T is less than 5°C, the low-temperature heating mode is activated. When the maximum temperature T is greater than 45°C, the high-temperature cooling mode is activated. When the temperature difference ΔT is greater than 5°C, the gradient balancing mode is activated. S5, dynamic flow control: In low-temperature heating mode, the reversing valve is controlled to direct 40°C coolant to the low-temperature area cells first. In high-temperature cooling mode, the reversing valve is switched to enhance heat dissipation in the high-temperature area, increasing the coolant flow by 35%. In gradient balancing mode, the reversing valve alternately switches the flow path to achieve lateral heat conduction. S6, Redundancy protection: adopt dual water inlet combined design to connect external parallel pump source, maintain 50% flow in case of single valve failure; S7, closed-loop control: integrating voltage and temperature data, achieving thermal balance control through the closed loop of "simulation prediction - real-time monitoring - dynamic adjustment"; S11. Build a three-dimensional battery pack fluid dynamics model to simulate fast charging, high-rate discharge, and extreme ambient temperature scenarios; S12. Extract the temporal and spatial evolution of the temperature field and identify the temperature rise gradients in the gaps between cells, around heat-generating components, and in airflow dead corners; S13, establishing a mapping database of ambient temperature, charge and discharge rate and temperature distribution, with an update cycle of less than 24 hours; S21. Calculate the standard deviation σ of the temperature field. When σ is greater than 3°C, place a PT1000 temperature sensor at the corresponding coordinate. S22. An embedded micro-groove sensor is set at the gap between the battery cells, with a sampling frequency greater than 10 Hz; S23, the sensor network communicates with the BMS via the CAN bus, with a transmission delay of less than 50ms; S31, valve body integrated temperature difference monitoring module, real-time comparison of inlet and outlet temperature difference; S32, adopt PWM drive to control the valve core rotation angle, the angle resolution is greater than 0.5°; S33: When the pipeline pressure difference is detected to be greater than 0.2 MPa, the self-cleaning mode is triggered and reverse flushing is performed for 30 seconds; S51, maintaining the initial temperature of the coolant at 40°C; S52: Prioritize heating the cells in the edge area of ​​the battery pack, with a temperature rise rate greater than 2°C / min; S53, when the minimum temperature T is greater than 10°C, exit the heating mode; S61, identify the central module with the fastest temperature rise; S62, increase the flow rate of the cooling liquid from the reference value 5 L / min to 7 L / min; S63, use pulsating flow to strengthen heat exchange, the pulsating frequency is 3 Hz; S71, set 5℃ as the temperature difference threshold, trigger the reversing valve to switch the flow direction alternately with a period of 30 seconds; S72, reduce the temperature difference between the modules to less than 2℃ by lateral heat conduction; S73, correct the temperature equalization parameters in combination with the cell voltage data, the voltage sampling accuracy is 0.5 mV; S81, combine two water inlets through a Y-shaped pipeline, the pipe diameter is Φ8 mm; S82, parallel two external pump sources, the maximum flow rate of each pump is 6 L / min; S83, start the redundant pump source when detecting that the flow rate of a single pump decreases by more than 40%; S91, establish a temperature-voltage joint evaluation function: , wherein, =0.7, =0.3, is the number of temperature sensors, is the number of cells; S92, ≥5 triggers system self-check, the calibration period is less than 15 minutes.

[0023] S8, real-time decision optimization: S811, in the gradient equalization mode, collect the cell health state data every 5 minutes, the calculation formula is: , wherein, is the current capacity, is the initial capacity; S812, when the decay rate is greater than 0.1% / week, dynamically reduce the temperature difference threshold from 5℃ to 3℃; S813, when detecting that the module voltage range is greater than 50 mV, trigger the liquid cooling flow rate to increase by 20% and the flow direction switching period to be shortened to 15 seconds simultaneously. Specific embodiments

[0024] Example 1: CFD simulation pre-judgment implementation In the battery pack design stage, a three-dimensional thermal fluid model is constructed using ANSYS Fluent to simulate 32 kinds of working condition combinations from -30°C extreme cold to 60°C high temperature environment at 0.5C slow charging to 4C fast discharging. The space-time evolution law of the temperature field is captured through transient simulation; based on the judgment threshold that the standard deviation σ of the temperature field is greater than 3°C, 12 PT1000 sensor coordinates are automatically calibrated at the cell gap and the tab connection, the spatial positioning error is less than 0.5mm, and the branch liquid cooling pipe topology network is generated synchronously, reducing the temperature difference monitoring blind area.

[0025] Example 2: Dynamic control implementation of electromagnetic valve When the BMS detects that the edge cell temperature drops to -5°C, the PWM control electromagnetic three-way reversing valve is driven, the rotation angle accuracy is 0.5°, the 40°C constant temperature cooling liquid is directed into the low temperature area, the edge cell temperature rise rate reaches 2.3°C / min; when the center module temperature rises to 48°C caused by 4C fast charging, the valve body switches to high temperature cooling mode, the flow rate increases from the baseline 5L / min to 7.5L / min and superimposes 3Hz pulsating flow, the hotspot temperature is suppressed to below 42°C within 15 seconds, and the temperature difference between modules converges to 2.1°C.

[0026] Example 3: Redundant safety implementation An integrated valve-pipe forming process is adopted, the leakage rate is <0.05 times / 10,000 hours, two centrifugal pumps are connected in parallel through Φ8mm Y-shaped pipe at the double water inlets; when the left pump controller fails, causing the flow rate to drop to 2.1L / min, the redundant system switches to the right pump for liquid supply within 200ms, maintaining 50% flow rate for continuous operation, and cooperating with the BMS to relax the temperature control target from ΔT≤3°C to ΔT≤5°C, ensuring safe driving of the vehicle to the repair station.

[0027] Example 4: Gradient equalization implementation In the standing condition after 4C fast charging, the BMS detects that the center module temperature is 52°C while the edge module temperature is only 41°C, triggering the gradient equalization mode immediately; the electromagnetic three-way reversing valve alternately switches the liquid flow path with a period of 22 seconds, forming forced convection between the high temperature area and the low temperature area, and the maximum temperature difference is compressed to 1.7°C within 8 minutes, while the overall temperature of the battery pack is stabilized in the 45°C safety interval.

[0028] Example 5: Extremely cold start implementation In a low temperature environment, the vehicle is cold started, the BMS measures the edge cell temperature to be -12°C, which is lower than the threshold of 17°C, switching to low temperature heating mode; the reversing valve directs the 40.5°C cooling liquid into the four corner areas of the battery pack, cooperating with the double pump full power operation, and within 12 minutes, all cell temperatures are simultaneously raised to 8.3°C, the temperature rise rate is 1.7°C / min, and the temperature difference is less than 0.8°C, avoiding the risk of lithium dendrite precipitation.

[0029] Example 6: High-temperature fast charging and static heat management After 4C fast charging at 45°C ambient temperature, the battery pack center module temperature soared to 63.2°C due to current skin effect, while the edge module was only 49.5°C. The BMS immediately triggered the gradient balancing and high-temperature cooling dual-mode control. The electromagnetic three-way valve alternately switched the liquid flow path every 25 seconds, while the cooling liquid flow rate was increased to 150% of the baseline value, and the high-frequency pulsating flow was superimposed to enhance the heat exchange efficiency. During the dynamic flow control process, the cooling liquid preferentially flowed through the center module to remove accumulated heat, and then diverted to the edge area to promote heat diffusion. Through the fusion of voltage data monitoring, the system real-time corrected the flow distribution ratio, and the maximum temperature difference was compressed to 1.8°C in only 6 minutes and 15 seconds, and the overall temperature stabilized in the 50°C safety range. This process verifies the three core advantages: the temperature difference convergence speed is 3.2°C / min, which is higher than the traditional system, the voltage fluctuation amplitude is suppressed within 0.3%, and the single-cycle pulsating flow heat exchange efficiency is improved.

[0030] Example 7: Redundancy guarantee under vibration working conditions When the vehicle continuously drives on a three-level road, the left inlet pipe line cracks due to mechanical resonance, and the flow rate drops from 6L / min to 2.4L / min. The fault diagnosis module detects the flow anomaly within 180ms and immediately starts the redundancy protocol: first switch to the right pump independent liquid supply, and the BMS dynamically relaxes the temperature control target. The electromagnetic valve switches to the directional protection mode - the cooling liquid flows through the No. 3 module with the highest temperature, and the remaining areas use intermittent cooling. During the 32-minute emergency disposal process, the system successfully suppresses the hotspot temperature below 61°C, and the temperature difference peak is controlled at 4.3°C. During the vehicle's safe driving to the service station, the battery capacity attenuation rate is only 0.15%. This example demonstrates that the integrated valve body design has a leakage rate of 0 under vibration conditions, the dual-pump redundancy mechanism improves system availability, and the fault weakening strategy extends the safety disposal window by 4.7 times.

Claims

1. A power battery thermal management system based on temperature change, characterized by: The thermal management system for power battery temperature control includes a thermal simulation prediction terminal, a sensor network terminal, a dynamic liquid cooling control terminal, a BMS decision terminal and a fault diagnosis module; The thermal simulation prediction terminal is used to generate a temperature field distribution map inside the battery pack and identify high-temperature hot spots by establishing a three-dimensional fluid mechanics model of the battery pack, thereby predicting the evolution trend of thermal behavior under different working conditions. The sensor network is used to automatically generate optimal sensor coordinates based on the standard deviation of the temperature field, and to deploy an embedded micro-groove sensor array around the gaps between the battery cells and the heat-generating components. When a local temperature difference greater than 3°C is detected, a coordinate calibration instruction is triggered. The dynamic liquid cooling control terminal is used to control the flow direction of the coolant through an electromagnetic three-way reversing valve integrated with a PT100 temperature sensor, and realize dynamic reconstruction of the liquid cooling pipeline topology under the condition that the pressure level is greater than 1MPa; The BMS decision-making end is used to activate the low-temperature heating mode when the minimum temperature is less than 5°C, start the high-temperature cooling mode when the maximum temperature is greater than 45°C, and execute the gradient balancing mode when the temperature difference between modules is greater than 5°C based on the real-time collected battery cell temperature data. At the same time, the voltage data is integrated to correct the control parameters in real time. The fault diagnosis module is used to identify system anomalies through a multi-physics field coupling analysis model and provide feedback for manual intervention and maintenance.

2. A power battery thermal management system based on temperature change, characterized in that: The following steps are involved: S1. Establish a multi-dimensional operating condition matrix for the battery pack: Calculate the internal temperature field distribution of the battery pack under high and low temperature environments and charge and discharge rate combination conditions through CFD simulation, and identify temperature rise hotspots and temperature gradient areas; S2. Optimize sensor layout: Automatically calibrate sensor point coordinates based on the standard deviation of the temperature field, deploy a multi-temperature sensor network in the temperature difference area within the battery pack, and monitor the temperature difference between modules in real time; S3. Build a dynamic liquid cooling topology: Generate a liquid cooling pipeline topology network based on the simulation results of S1. Integrate an electromagnetic three-way reversing valve at the battery pack inlet and outlet, and integrate the valve body and cooling pipeline into an integrated form. S4, working condition identification and mode switching: The BMS collects the battery cell temperature data in real time. When the minimum temperature T is less than 5°C, the low-temperature heating mode is activated. When the maximum temperature T is greater than 45°C, the high-temperature cooling mode is activated. When the temperature difference ΔT is greater than 5°C, the gradient balancing mode is activated. S5, dynamic flow control: In low-temperature heating mode, the reversing valve is controlled to direct 40°C coolant to the low-temperature area cells first. In high-temperature cooling mode, the reversing valve is switched to enhance heat dissipation in the high-temperature area, increasing the coolant flow by 35%. In gradient balancing mode, the reversing valve alternately switches the flow path to achieve lateral heat conduction. S6, Redundancy protection: adopt dual water inlet combined design to connect external parallel pump source, maintain 50% flow in case of single valve failure; S7, Closed-loop control: Integrating voltage and temperature data, thermal balance control is achieved through a closed loop of "simulation prediction - real-time monitoring - dynamic adjustment".

3. The power battery thermal management system based on temperature change according to claim 2, characterized in that: Said S1 specifically includes: S11. Build a three-dimensional battery pack fluid dynamics model to simulate fast charging, high-rate discharge, and extreme ambient temperature scenarios; S12. Extract the temporal and spatial evolution of the temperature field and identify the temperature rise gradients in the gaps between cells, around heat-generating components, and in airflow dead corners; S13. Establish a mapping database of ambient temperature, charge and discharge rate, and temperature distribution, with an update cycle of less than 24 hours.

4. The power battery thermal management system based on temperature change according to claim 2, characterized in that: The sensor layout optimization in S2 includes: S21. Calculate the standard deviation σ of the temperature field. When σ is greater than 3°C, place a PT1000 temperature sensor at the corresponding coordinate. S22. An embedded micro-groove sensor is set at the gap between the battery cells, with a sampling frequency greater than 10 Hz; S23, the sensor network communicates with the BMS via the CAN bus, with a transmission delay of less than 50ms.

5. The power battery thermal management system based on temperature change according to claim 2, characterized in that: The control logic S3 of the electromagnetic three-way reversing valve is: S31, valve body integrated temperature difference monitoring module, real-time comparison of inlet and outlet temperature difference; S32, adopt PWM drive to control the valve core rotation angle, the angle resolution is greater than 0.5°; S33. When the pipeline pressure difference is detected to be greater than 0.2MPa, the self-cleaning mode is triggered and reverse flushing is performed for 30 seconds.

6. The power battery thermal management system based on temperature change according to claim 2, characterized in that: The low temperature heating mode S5 specifically includes: S51, maintaining the initial temperature of the coolant at 40°C; S52: Prioritize heating the cells in the edge area of ​​the battery pack, with a temperature rise rate greater than 2°C / min; S53. When the minimum temperature T is greater than 10°C, exit the heating mode.

7. The power battery thermal management system based on temperature change according to claim 2, characterized in that: The high temperature cooling mode S5 specifically includes: S61, identify the central module with the fastest temperature rise; S62, increase the coolant flow rate from the base value of 5 L / min to 7 L / min; S63, using pulsating flow to enhance heat exchange, the pulsating frequency is 3Hz.

8. The power battery thermal management system based on temperature change according to claim 1, characterized in that: The gradient balancing mode S5 specifically includes: S71, set 5°C as the temperature difference threshold, triggering the reversing valve to alternately switch the flow direction in a 30-second cycle; S72. Reduce the temperature difference between modules to less than 2°C through lateral heat conduction; S73. Correct the temperature balance parameters based on the cell voltage data. The voltage sampling accuracy is 0.5mV.

9. The power battery thermal management system based on temperature change according to claim 2, characterized in that: The dual water inlet design S6 includes: S811, the two water inlets are combined through a Y-shaped pipe with a diameter of Φ8mm; S812, two external pump sources are connected in parallel, with a maximum flow rate of 6L / min per channel; S813: When it is detected that the single-channel flow rate drops by more than 40%, the redundant pump source is started.

10. The power battery thermal management system based on temperature change according to claim 2, characterized in that: The closed-loop control S7 includes: S91. Establish a temperature-voltage joint evaluation function: ， in, =0.7, =0.3, is the number of temperature sensors, is the number of battery cells; S92, when When the value is ≥5, the system self-check is triggered and the calibration cycle is less than 15 minutes.

Images