A simulation method for power switching of a power battery

Abstract

The application relates to the technical field of power batteries, in particular to a simulation method for power switching of a power battery, which adopts a one-dimensional simulation electro-thermal coupling model battery circuit model to receive the maximum temperature and the minimum temperature of a three-dimensional thermal simulation model battery, and to calculate the SOC change value and the battery heat production of the power battery at each moment in the charging and discharging process, and output the SOC value to a power map switching strategy model and output the heat production to the battery cell of the three-dimensional thermal simulation model; the control strategy model calculates the allowable power of the battery at each moment according to the table lookup method and the calculation formula according to the received parameters such as the maximum and minimum temperatures of the three-dimensional thermal simulation model battery and the SOC value of the one-dimensional simulation electro-thermal coupling model battery; the method can make the power switching test close to the real use scene, avoid the problems of overvoltage or undervoltage, fully exert the battery performance, and improve the simulation precision.

Description

Technical Field

[0001] This invention relates to the field of power battery technology, and specifically to a simulation method for power battery power switching. Background Technology

[0002] Overcharging or over-discharging a power battery can cause lithium plating, which affects the battery's lifespan and safety. Therefore, power batteries need to be kept within a certain voltage range during use.

[0003] When a power battery is used within its cutoff voltage range, it can exhibit different charging and discharging performance at different charging and discharging times. With shorter charging and discharging times, the power battery can provide or release greater power, thereby improving the vehicle's power performance. Therefore, the use of a power battery must ensure that it is used within its cutoff voltage range while also considering maximizing its charging and discharging performance.

[0004] Power batteries typically have charging and discharging power maps of 2s, 5s, 10s, and 30s based on time (assuming constant battery temperature and SOC, the battery can charge and discharge at a constant power for 2s, with the battery voltage always within the cutoff voltage range during discharge). Since pure electric vehicle batteries have a larger total energy and mass, and shorter charging and discharging times, the SOC and temperature of the battery can be considered constant in power battery switching tests. However, HEV batteries have a smaller total energy and mass, and their SOC and temperature fluctuate significantly during charging and discharging. Battery charging and discharging power map switching tests should consider changes in battery SOC and temperature and adjust the charging and discharging power in real time; otherwise, overvoltage or undervoltage issues may occur in the HEV battery during the test, ultimately leading to test failure. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a simulation method that can consider the impact of battery temperature and SOC on charge and discharge performance, making the HEV power battery power switching test closer to the real-world battery usage scenario, thereby improving the test's authenticity and protecting the battery within a safe voltage operating range for power battery charge and discharge power switching.

[0006] To solve the above-mentioned technical problems, the technical solution provided by the present invention is: the simulation method for power battery power switching, comprising the following steps:

[0007] (1) Establish a three-dimensional thermal simulation model for simulating the heat exchange process between different battery structures;

[0008] (2) Simulate the heat transfer path based on the three-dimensional thermal simulation model established in step (1), and calculate the highest and lowest temperatures of the power battery;

[0009] (3) Establish a one-dimensional simulation electrothermal coupling model, which includes a battery circuit model and a control strategy model;

[0010] (4) The charging and discharging power requirements of the vehicle to the power battery are simulated by the battery circuit model. The SOC value and heat generation of the power battery are calculated by the calculated power requirements. The calculated battery SOC value and heat generation are output to the control strategy model and the three-dimensional thermal simulation model.

[0011] (5) The control strategy model selects the highest or lowest temperature of the battery as the battery's operating temperature based on the ambient temperature of the battery, and calculates the temperature selection and required power of the power battery.

[0012] This solution utilizes a combined one-dimensional and three-dimensional simulation. The one-dimensional circuit model accurately calculates the battery's heat generation and feeds it back to the three-dimensional thermal model, effectively improving the simulation accuracy of the three-dimensional thermal model. Based on simulation methods, this solution achieves real-time calculation of battery temperature and SOC changes during power switching. It uses a three-dimensional simulation model to calculate the battery temperature, and uses a one-dimensional circuit model and strategy model to calculate the heat generation, SOC, and maximum allowable charge / discharge power at each moment, which are then input into the test equipment. This effectively avoids battery overvoltage or undervoltage faults during testing, thus realistically simulating the power switching state during actual vehicle operation.

[0013] Furthermore, in step (1), the three-dimensional thermal simulation model includes the top cover, the air inside the battery pack, electrical connectors, battery cells, thermally conductive adhesive, water-cooled plate, end plate, housing, bottom protective plate, and coolant. The heat generated by the battery cells during charging and discharging is transferred to the air inside the battery pack, coolant, top cover, electrical connectors, thermally conductive adhesive, water-cooled plate, end plate, housing, and bottom protective plate through convection and heat conduction.

[0014] Further, in step (3), the battery circuit model includes a battery simulation element, a SOC cutoff condition control element, a SOC element, a load simulation element, a load consumption simulation element, a voltage monitoring element, a battery heat generation element, and a final temperature element. The load simulation element is connected to the load consumption simulation element. The power value of the load consumption simulation element is calculated by the control strategy model and then input to the battery simulation element. In this process, a one-dimensional simulation electrothermal coupling model is used to simulate the charging and discharging process of the battery. The load simulation element is connected to the load consumption simulation element and is used to simulate the charging and discharging power demand of the vehicle on the power battery. The battery simulation element can simulate the electrochemical reaction process of the battery and calculate the SOC value and heat generation of the power battery in real time.

[0015] Furthermore, the SOC element and the battery heat generation element are respectively connected to the battery simulation element. In this process, the battery SOC and heat generation signals calculated by the battery simulation element are output to the control strategy model and the three-dimensional thermal simulation model.

[0016] Furthermore, the SOC cutoff condition control element is connected to the battery simulation element to define the SOC range of the power battery. When the battery simulation element reaches a certain SOC value during charging and discharging, the model stops running and starts running the next operating condition. The voltage monitoring element is connected in parallel in the circuit model to monitor the real-time voltage of the power battery. The control strategy model selects the highest and lowest temperatures of the battery as the battery's operating temperature based on the ambient temperature of the battery, and inputs the final temperature element to the battery simulation element.

[0017] Furthermore, the control strategy models include a battery temperature strategy model, a cutoff voltage protection strategy model, and a power switching strategy model.

[0018] Furthermore, the battery temperature strategy model includes a battery heat generation element, a battery maximum temperature element, a battery minimum temperature element, an ambient temperature element, a selection element, a final temperature element, and a three-dimensional interface element. Among them, the battery heat generation element is connected to the three-dimensional interface element and inputs the battery heat generation calculated by the battery simulation element into the three-dimensional thermal simulation model to calculate the temperature rise of the power battery. The three-dimensional interface element is connected to the battery maximum temperature element and the battery minimum temperature element and inputs the battery maximum and minimum temperatures calculated by the three-dimensional thermal simulation model into the one-dimensional simulation electrothermal coupling model.

[0019] The ambient temperature element is connected to the selection element, and the battery maximum temperature element and battery minimum temperature element are connected to the selection element to jointly realize the output of the battery maximum temperature through the final temperature element when the ambient temperature is higher than the preset temperature T0, and the output of the battery minimum temperature when it is lower than T0.

[0020] Furthermore, the cutoff voltage protection strategy model includes three sub-models, which consist of a voltage monitoring element, a voltage judgment element, an ambient temperature element, a temperature judgment element, a voltage protection trigger element, and a voltage trigger cutoff element.

[0021] The ambient temperature is divided into three gradients: Tb≥T, Ta≥T>Tb, and T>Ta, where ambient temperature : T, temperature 1 : Ta, and temperature 2 : Tb. The ambient temperature element inputs the ambient temperature to the temperature judgment element. Multiple sub-models are distinguished according to different ambient temperatures and voltage cutoff ranges. When Tb≥T, sub-model 1 runs, and the voltage monitoring element inputs the battery voltage to the voltage judgment element. The voltage judgment element determines whether the battery voltage is within the cutoff range V1-V2. If the voltage is outside the cutoff range, the voltage protection strategy is triggered, and signal 1 is output to the voltage protection trigger element. The voltage protection trigger element inputs the cutoff signal to the voltage trigger cutoff element, and the protection strategy is triggered. The simulation process stops when any sub-model cutoff condition is triggered.

[0022] Furthermore, the power switching strategy model includes a final temperature element, a SOC element, a 30s charge / discharge power map, a 2s charge / discharge power map, a 10s charge / discharge power map, a minimum operating power, a power selection element, a numerical comparison element, a map selection element, an ambient temperature element, a time recording element, an allowable power result element, and a state transition element.

[0023] The current allowable battery power is obtained by combining the final temperature element, SOC element, 30s charge / discharge power map, 2s charge / discharge power map and 10s charge / discharge power map. The minimum operating power, power selection element and the power output after looking up the table of 10s charge / discharge power map are compared. If the power value output by the 10s charge / discharge power map is less than the minimum operating power, the minimum operating power is output.

[0024] The numerical comparison element compares the output values ​​of the 10s charge / discharge power map and the 2s charge / discharge power map. If the 2s charge / discharge power map is greater than the 10s charge / discharge power map, the 2s charge / discharge power map is output; otherwise, the 10s charge / discharge power map is output.

[0025] The 30s charge / discharge power map lookup values, 10s charge / discharge power map lookup values, and 2s charge / discharge power map lookup values ​​are respectively input to the state transition element. The state transition element selects the 2s charge / discharge power map, 10s charge / discharge power map, and 30s charge / discharge power map according to the start time of charge / discharge. The transition time from 2s to 10s charge / discharge power map is time01.

[0026] Furthermore, the power calculation method during the 2s-10s charge / discharge power map transition period is as follows:

[0027] p = charge2 + (clock - time01) * (charge10 - charge2) / time01, where p is the allowable power, charge2 is the table lookup value of the charging and discharging power in 2 seconds, clock is the time, and charge10 is the table lookup value of the charging and discharging power in 10 seconds.

[0028] The power calculation method during the 10s-30s charge / discharge power transition period is as follows:

[0029] p = charge10 + (clock - 10) * (charge30 - charge10) / time01, where charge30 is the table lookup value of the charging and discharging power over 30 seconds;

[0030] Use the time-segment map lookup value during non-transition periods:

[0031] When the charging / discharging time clock ≤ 2s, jump to State001 and output the allowable power value;

[0032] When the charging / discharging time 2 < clock ≤ 2 + time01s, jump to State002 and output the allowable power value;

[0033] When the charging / discharging time 2 + time01s < clock ≤ 10s, jump to State003 and output the allowable power value;

[0034] When the charging / discharging time is 10 < clock ≤ 10 + time01s, jump to State004 and output the allowable power value;

[0035] When the charging / discharging time is 10 + time01s < clock ≤ 30s, jump to State005 and output the allowable power value.

[0036] Compared with the prior art, in this invention, a one-dimensional simulated electrothermal coupling model of the battery circuit is used to receive the highest and lowest battery temperatures from the three-dimensional thermal simulation model. The SOC change and heat generation of the battery at each moment during the charging and discharging process are calculated, and the SOC value is output to the power map switching strategy model. The heat generation is output to the cell of the three-dimensional thermal simulation model. The control strategy model calculates the allowable power of the battery at each moment according to the parameters such as the highest and lowest battery temperatures from the three-dimensional thermal simulation model and the battery SOC value from the one-dimensional simulated electrothermal coupling model, using a lookup table method and the above calculation formula. Attached Figure Description

[0037] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0038] Figure 1 This is a schematic diagram of the three-dimensional thermal simulation model in this embodiment.

[0039] Figure 2 This is a schematic diagram of the internal planar structure of the three-dimensional thermal simulation model in this embodiment;

[0040] Figure 3 This is a schematic diagram of the three-dimensional simulation battery temperature results in this embodiment;

[0041] Figure 4 This is a schematic diagram of the battery circuit model in this embodiment;

[0042] Figure 5 This is a diagram illustrating the working process of the battery circuit model in this embodiment;

[0043] Figure 6 This is a schematic diagram of the power battery heat generation and SOC simulation results in this embodiment;

[0044] Figure 7 This is a schematic diagram of the battery temperature strategy model in this embodiment;

[0045] Figure 8 This is a diagram illustrating the working process of the battery temperature strategy model in this embodiment;

[0046] Figure 9 This is a schematic diagram of the cutoff voltage protection strategy model in this embodiment;

[0047] Figure 10 This is a diagram illustrating the working process of the cutoff voltage protection strategy model in this embodiment;

[0048] Figure 11 This is a comparison diagram of the protection policy being triggered and not triggered in this embodiment;

[0049] Figure 12 This is a schematic diagram of the power switching strategy model in this embodiment;

[0050] Figure 13 This is a schematic diagram of the power map in this embodiment;

[0051] Figure 14 This is a schematic diagram of the allowable power output in this embodiment;

[0052] Figure 15 This is a schematic diagram showing the maximum allowable power value of the battery in this embodiment;

[0053] Figure 16 This is a schematic diagram of the overall simulation principle of this embodiment.

[0054] In the diagram: 1-Top cover, 2-Air inside the battery pack, 3-Electrical connector, 4-Battery cell, 5-Thermal conductive adhesive, 6-Water cooling plate, 7-End plate, 8-Casing, 9-Bottom plate, 10-Coolant, 11-Battery simulation element, 12-SOC cutoff condition control element, 13-SOC element, 14-Load simulation element, 15-Load consumption simulation element, 16-Voltage monitoring element, 20-Battery heat generation element, 26-Final temperature element, 21-Battery maximum temperature element, 22-Battery minimum temperature element, 2 3-Ambient temperature element, 25-Selection element, 27-3D interface element, 29-Temperature judgment element, 30-Voltage protection trigger element, 31-Voltage trigger cutoff element, 32-30s charge / discharge power map, 33-2s charge / discharge power map, 34-10s charge / discharge power map, 35-Minimum operating power, 36-Power selection element, 37-Numerical comparison element, 38-Map selection element, 40-Time recording element, 43-Allowable power result element, 44-State jump element. Detailed Implementation

[0055] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0056] The simulation method for power battery power switching described in this invention includes the following steps:

[0057] (1) Establish a three-dimensional thermal simulation model for simulating the heat exchange process between different battery structures;

[0058] In this step, such as Figure 1 and 2 As shown, the three-dimensional thermal simulation model includes the top cover 1, the air inside the battery pack 2, the electrical connectors 3, the battery cells 4, the thermally conductive adhesive 5, the water-cooling plate 6, the end plate 7, the housing 8, the bottom protective plate 9, and the coolant 10.

[0059] In this process, a three-dimensional thermal simulation model is used to simulate the heat exchange between different battery structures. During the charging and discharging process, the cell 4 will generate heat. Part of the heat will cause the cell 4 to generate a temperature rise, while the other part of the heat will be transferred to the air 2, coolant 10, top cover 1, electrical connector 3, thermally conductive adhesive 5, water cooling plate 6, end plate 7, housing 8, and bottom protection plate 9 inside the battery pack through convection heat transfer and heat conduction.

[0060] (2) Use a three-dimensional thermal simulation model to simulate the heat transfer path and calculate the highest and lowest temperatures of the power battery;

[0061] In this embodiment, the three-dimensional simulated battery temperature is as follows: Figure 3 As shown;

[0062] (3) Establish a one-dimensional simulation electrothermal coupling model, which includes a battery circuit model and a control strategy model;

[0063] Among them, such as Figure 4 As shown, the battery circuit model includes battery simulation element 11, SOC cutoff condition control element 12, SOC element 13, load simulation element 14, load consumption simulation element 15, voltage monitoring element 16, battery heat generation element 20, and final temperature element 26.

[0064] In this process, a one-dimensional simulation electrothermal coupling model is used to simulate the charging and discharging process of the battery. The load simulation element 14 is connected to the load consumption simulation element 15 to simulate the charging and discharging power demand of the vehicle on the power battery. The specific power value of the load consumption simulation element 15 is calculated by the control strategy model and input to the element. The power demand is then input to the battery simulation element 11. The battery simulation element 11 simulates the electrochemical reaction process of the battery and calculates the SOC value and heat generation of the power battery in real time.

[0065] SOC element 13 and battery heat generation element 20 are respectively connected to battery simulation element 11. During this process, the battery SOC and heat generation signals calculated by battery simulation element 11 are output to the control strategy model and the three-dimensional thermal simulation model. SOC cutoff condition control element 12 is connected to battery simulation element 11 and is used to define the operating SOC range of the power battery. When battery simulation element 11 reaches a certain SOC value during charging and discharging, the model stops running and starts running the next operating condition.

[0066] Voltage monitoring element 16 is connected in parallel in the analog circuit model to monitor the real-time voltage of the power battery. The control strategy model selects the highest and lowest temperatures of the battery as its operating temperature based on the ambient temperature of the battery. This temperature is then input to the battery simulation element 11 via the final temperature element 26. Its operation process is as follows: Figure 5 As shown.

[0067] (4) The charging and discharging power requirements of the vehicle to the power battery are simulated using a battery circuit model. The SOC value and heat generation of the power battery are calculated based on the calculated power requirements. The calculated battery SOC value and heat generation are then output to the control strategy model and the three-dimensional thermal simulation model. The simulation results of power battery heat generation and SOC are as follows: Figure 6 As shown;

[0068] (5) The control strategy model selects the highest or lowest temperature of the battery as the battery's operating temperature based on the ambient temperature of the battery, and calculates the temperature selection and required power of the power battery.

[0069] The control strategy model is used to calculate the power battery temperature selection and required power, and to implement the voltage protection strategy. This model mainly consists of three parts: a battery temperature strategy model, a cutoff voltage protection strategy model, and a power switching strategy model.

[0070] like Figure 7 As shown, the battery temperature strategy model includes a battery heat generation element 20, a battery maximum temperature element 21, a battery minimum temperature element 22, an ambient temperature element 23, a selection element 25, a final temperature element 26, and a three-dimensional interface element 27. Its working principle is as follows: the battery heat generation element 20 is connected to the three-dimensional interface element 27, inputting the battery heat generation calculated by the battery simulation element 1 into the three-dimensional thermal simulation model to calculate the temperature rise of the power battery. The three-dimensional interface element 27 is connected to the battery maximum temperature element 21 and the battery minimum temperature element 22, and can input the battery maximum and minimum temperatures calculated by the three-dimensional thermal simulation model into the one-dimensional simulation model. The ambient temperature element 23 is connected to the selection element 25. The battery maximum temperature element 21 and the battery minimum temperature element 22 are connected to the selection element 25 to jointly achieve the following: when the ambient temperature is higher than a certain temperature T0, the battery maximum temperature is output; when it is lower than T0, the battery minimum temperature is output. This temperature value is output through the final temperature element 26. Its working process is as follows: Figure 8 As shown.

[0071] like Figure 9 As shown, the cutoff voltage protection strategy model includes three sub-models, which mainly consist of voltage monitoring element 16, voltage judgment element 27, ambient temperature element 23, temperature judgment element 29, voltage protection trigger element 30, and voltage trigger cutoff element 31.

[0072] The working principle of this model is as follows: due to different ambient temperatures, the thresholds for triggering overvoltage or undervoltage of the power battery vary. In this scheme, the ambient temperature is divided into three gradients: Tb≥T, Ta≥T>Tb, and T>Ta, where ambient temperature = T, temperature 1 = Ta, and temperature 2 = Tb. Simultaneously, the corresponding power battery voltage usage ranges are V1-V2, V3-V4, and V5-V6 (V1, V2, V3, V4, V5, and V6 are different voltage values, defined according to the actual battery conditions). The ambient temperature element 23 inputs the ambient temperature to the temperature judgment element 29. When Tb≥T, the sub-model 1 is triggered to run. The voltage monitoring element 16 inputs the battery voltage to the voltage judgment element 27, which determines whether the battery voltage is within the cutoff range V1-V2. If the voltage is outside the cutoff range, the cutoff voltage protection strategy is triggered, outputting signal 1 to the voltage protection trigger element 30. The voltage protection trigger element 30 inputs this cutoff signal to the voltage trigger cutoff element 31. Once the protection strategy is triggered, the simulation stops, thus protecting the battery. The triggering principle of sub-models 2 and 3 is the same as that of sub-model 1, the difference being the different ambient temperature and voltage cutoff ranges. The simulation immediately stops when any of the three sub-models triggers a cutoff condition. Their working process is as follows: Figure 10 As shown. Figure 11 The protection strategy is compared between triggered and non-triggered states (the model stops running after the strategy is triggered to avoid battery overvoltage or undervoltage).

[0073] like Figure 12 As shown, the power switching strategy model includes the final temperature element 26, SOC element 13, 30s charge / discharge power map 32, 2s charge / discharge power map 33, 10s charge / discharge power map 34, minimum operating power 35, power selection element 36, numerical comparison element 37, map selection element 38, ambient temperature element 23, time recording element 40, allowable power result element 43, and state transition element 44.

[0074] The combination of the final temperature element 26, SOC element 13, 30s charge / discharge power map 32, 2s charge / discharge power map 33, and 10s charge / discharge power map 34 allows the battery to obtain its current allowable power based on different battery temperatures and SOC values. The power map is shown below. Figure 13 As shown (different charge / discharge times, temperatures, and SOCs of the battery correspond to different allowable power).

[0075] The minimum operating power 35, the power selection element 36, and the power output from the 10s charge / discharge power map 34 (after looking up the table) are compared. If the power value output from the 10s charge / discharge power map 34 is less than the minimum operating power 35, then the minimum operating power 35 is output to ensure that there is a minimum operating power for this charge / discharge process. The numerical comparison element 37 compares the output values ​​of the 10s charge / discharge power map 34 and the 2s charge / discharge power map 33. If the 2s charge / discharge power map 33 is greater than the 10s charge / discharge power map 34, then the 2s charge / discharge power map is output; otherwise, the 10s charge / discharge power map 33 is output. The comparison is to ensure that the charge / discharge power map can output the largest possible value. The calculation results of the 30s charge / discharge power map lookup value, 10s charge / discharge power map lookup value, and 2s charge / discharge power map lookup value are input to the state transition element 44 respectively. The state transition element 44 selects the 2s charge / discharge power map, 10s charge / discharge power map, and 30s charge / discharge power map respectively according to the start time of charge / discharge. The transition time from 2s to 10s charge / discharge power map is time01 (2 to 2+time01; 10 to 10+time01 is the power transition period).

[0076] The power calculation method during the 2s-10s charge / discharge power transition period is as follows:

[0077] p = charge2 + (clock - time01) * (charge10 - charge2) / time01, where p is the allowable power, charge2 is the table lookup value of the charging and discharging power in 2 seconds, clock is the time, and charge10 is the table lookup value of the charging and discharging power in 10 seconds.

[0078] The power calculation method during the 10s-30s charge / discharge power transition period is as follows:

[0079] p = charge10 + (clock - 10) * (charge30 - charge10) / time01, where charge30 is the table lookup value of the charging and discharging power over 30 seconds;

[0080] like Figure 14 As shown, during non-transition periods, the time-slot map is used to look up table values:

[0081] When the charging / discharging time clock ≤ 2s, jump to State001 and output the allowable power value;

[0082] When the charging / discharging time 2 < clock ≤ 2 + time01s, jump to State002 and output the allowable power value;

[0083] When the charging / discharging time 2 + time01s < clock ≤ 10s, jump to State003 and output the allowable power value;

[0084] When the charging / discharging time is 10 < clock ≤ 10 + time01s, jump to State004 and output the allowable power value;

[0085] When the charging / discharging time is 10 + time01s < clock ≤ 30s, jump to State005 and output the allowable power value.

[0086] In this embodiment, the calculated maximum allowable power for battery charging and discharging is as follows (the battery's required power also changes with SOC and temperature, thus ensuring that the battery is used within the target voltage range). The maximum allowable power value for the battery, obtained by looking up the table and calculation, is as follows: Figure 15 As shown.

[0087] Compared with existing technologies, this invention uses a one-dimensional simulated electrothermal coupling model of the battery circuit to receive the highest and lowest battery temperatures from a three-dimensional thermal simulation model. It then calculates the SOC change and heat generation of the battery at each moment during charging and discharging. The SOC value is output to the power map switching strategy model, and the heat generation is output to cell 4 in the three-dimensional thermal simulation model. The control strategy model, based on the received highest and lowest battery temperatures from the three-dimensional thermal simulation model and the battery SOC value from the one-dimensional simulated electrothermal coupling model, calculates the allowable power of the battery at each moment using a lookup table method and the aforementioned calculation formula. The overall simulation principle of this invention is as follows: Figure 16 As shown.

[0088] Overall, this solution utilizes a combined one-dimensional and three-dimensional simulation. The one-dimensional circuit model accurately calculates the battery's heat generation and feeds it back to the three-dimensional thermal model, effectively improving the simulation accuracy of the three-dimensional thermal model. Based on simulation methods, this solution achieves real-time calculation of battery temperature and SOC changes during power switching. The three-dimensional simulation model calculates the battery temperature, while the one-dimensional circuit model and strategy model calculate the heat generation, SOC, and maximum allowable charge / discharge power at each moment, which are then input into the test equipment. This effectively avoids battery overvoltage or undervoltage faults during testing, thus realistically simulating the power switching state during actual vehicle operation.

[0089] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A simulation method for power battery power switching, characterized in that, Includes the following steps: (1) Establish a three-dimensional thermal simulation model for simulating the heat exchange process between different battery structures; (2) Simulate the heat transfer path based on the three-dimensional thermal simulation model established in step (1), and calculate the highest and lowest temperatures of the power battery; (3) Establish a one-dimensional simulation electrothermal coupling model, which includes a battery circuit model and a control strategy model; (4) The charging and discharging power requirements of the vehicle to the power battery are simulated by the battery circuit model. The SOC value and heat generation of the power battery are calculated by the calculated power requirements. The calculated battery SOC value and heat generation are output to the control strategy model and the three-dimensional thermal simulation model. (5) The control strategy model selects the highest or lowest temperature of the battery as the battery's operating temperature based on the ambient temperature of the battery, and calculates the temperature selection and required power of the power battery.

2. The simulation method for power battery power switching according to claim 1, characterized in that, In step (1), the three-dimensional thermal simulation model includes a top cover, air inside the battery pack, electrical connectors, battery cells, thermally conductive adhesive, water-cooled plate, end plate, housing, bottom protective plate, and coolant. The heat generated by the battery cells during charging and discharging is transferred to the air inside the battery pack, coolant, top cover, electrical connectors, thermally conductive adhesive, water-cooled plate, end plate, housing, and bottom protective plate through convection and heat conduction.

3. The simulation method for power battery power switching according to claim 1, characterized in that, In step (3), the battery circuit model includes a battery simulation element, a SOC cutoff condition control element, a SOC element, a load simulation element, a load consumption simulation element, a voltage monitoring element, a battery heat generation element, and a final temperature element. The load simulation element is connected to the load consumption simulation element. The power value of the load consumption simulation element is calculated by the control strategy model and then input to the battery simulation element.

4. The simulation method for power battery power switching according to claim 3, characterized in that, The SOC element and the battery heat generation element are respectively connected to the battery simulation element. The battery SOC and heat generation signals calculated by the battery simulation element are output to the control strategy model and the three-dimensional thermal simulation model.

5. The simulation method for power battery power switching according to claim 4, characterized in that, The SOC cutoff condition control element is connected to the battery simulation element. When the battery simulation element reaches the preset SOC value during charging and discharging, the model stops running and starts running the next operating condition. The voltage monitoring element is connected in parallel in the circuit model. The control strategy model selects the highest and lowest temperatures of the battery as the battery's operating temperature based on the ambient temperature of the battery, and inputs the final temperature element to the battery simulation element.

6. The simulation method for power battery power switching according to claim 1, characterized in that, The control strategy model includes a battery temperature strategy model, a cutoff voltage protection strategy model, and a power switching strategy model.

7. The simulation method for power battery power switching according to claim 6, characterized in that, The battery temperature strategy model includes a battery heat generation element, a battery maximum temperature element, a battery minimum temperature element, an ambient temperature element, a selection element, a final temperature element, and a three-dimensional interface element. The battery heat generation element is connected to the three-dimensional interface element, and the battery heat generation calculated by the battery simulation element is input into the three-dimensional thermal simulation model; the three-dimensional interface element is connected to the battery maximum temperature element and the battery minimum temperature element, and the battery maximum and minimum temperatures calculated by the three-dimensional thermal simulation model are input into the one-dimensional simulation electrothermal coupling model; The ambient temperature element is connected to the selection element. The battery maximum temperature element and the battery minimum temperature element are connected to the selection element to jointly realize that when the ambient temperature is higher than the preset temperature T0, the battery maximum temperature is output through the final temperature element, and when it is lower than T0, the battery minimum temperature is output.

8. The simulation method for power battery power switching according to claim 6, characterized in that, The cutoff voltage protection strategy model includes a voltage monitoring element, a voltage judgment element, an ambient temperature element, a temperature judgment element, a voltage protection trigger element, and a voltage trigger cutoff element; The ambient temperature is divided into three gradients: Tb≥T, Ta≥T>Tb, and T>Ta, where ambient temperature : T, temperature 1 : Ta, and temperature 2 : Tb. The ambient temperature element inputs the ambient temperature to the temperature judgment element. Multiple sub-models are distinguished according to different ambient temperatures and voltage cutoff ranges. When Tb≥T, sub-model 1 runs. The voltage monitoring element inputs the battery voltage to the voltage judgment element. The voltage judgment element determines whether the battery voltage is within the cutoff range V1-V2. If the voltage is outside the cutoff range, the voltage protection strategy is triggered, and signal 1 is output to the voltage protection trigger element. The voltage protection trigger element inputs a cutoff signal to the voltage trigger cutoff element, and the protection strategy is triggered. The simulation process stops if any sub-model is triggered to close.

9. The simulation method for power battery power switching according to claim 6, characterized in that, The power switching strategy model includes a final temperature element, a SOC element, a 30s charge / discharge power map, a 2s charge / discharge power map, a 10s charge / discharge power map, a minimum operating power, a power selection element, a numerical comparison element, a map selection element, an ambient temperature element, a time recording element, a permissible power result element, and a state transition element. The current allowable battery power is obtained by combining the final temperature element, SOC element, 30s charge / discharge power map, 2s charge / discharge power map and 10s charge / discharge power map. The minimum operating power and the power output after looking up the table of the power selection element are compared with the power output after looking up the table of the 10s charge / discharge power map. If the power value output by the 10s charge / discharge power map is less than the minimum operating power, the minimum operating power is output. The numerical comparison element compares the output values ​​of the 10s charge-discharge power map and the 2s charge-discharge power map. If the 2s charge-discharge power map is greater than the 10s charge-discharge power map, the 2s charge-discharge power map is output; otherwise, the 10s charge-discharge power map is output. The 30s charge / discharge power map lookup values, 10s charge / discharge power map lookup values, and 2s charge / discharge power map lookup values ​​are respectively input to the state transition element. The state transition element selects the 2s charge / discharge power map, 10s charge / discharge power map, and 30s charge / discharge power map according to the start time of charge / discharge. The transition time from 2s to 10s charge / discharge power map is time01.

10. The simulation method for power battery power switching according to claim 9, characterized in that, The power calculation method during the 2s-10s charge / discharge power transition period is as follows: p = charge2 + (clock - time01) * (charge10 - charge2) / time01, where p is the allowable power, charge2 is the table lookup value of the charging and discharging power in 2 seconds, clock is the time, and charge10 is the table lookup value of the charging and discharging power in 10 seconds. The power calculation method during the 10s-30s charge / discharge power transition period is as follows: P = charge10 + (clock - 10) * (charge30 - charge10) / time01, where charge30 is the table lookup value of the charging and discharging power over 30 seconds; Use the time-segment map lookup value during non-transition periods: When the charging / discharging time clock ≤ 2s, jump to State001 and output the allowable power value; When the charging / discharging time 2 < clock ≤ 2 + time01s, jump to State002 and output the allowable power value; When the charging / discharging time 2 + time01s < clock ≤ 10s, jump to State003 and output the allowable power value; When the charging / discharging time is 10 < clock ≤ 10 + time01s, jump to State004 and output the allowable power value; When the charging / discharging time is 10 + time01s < clock ≤ 30s, jump to State005 and output the allowable power value.

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