Battery pack cooling circulation method and system

Abstract

The invention discloses a battery pack cooling circulation method and system which are applied to the technical field of battery pack cooling, and the method comprises the steps: obtaining the temperature of each region when a battery pack is cooled, and calculating the temperature difference value between any two regions through the maximum temperature value and the minimum temperature value of each region, whether the temperature difference values meet preset conditions or not is judged, if yes, corresponding cooling operation is executed, and the flow direction and flow of the cooling medium are adjusted, so that it is guaranteed that the temperature difference values of all the areas are consistent when the battery pack is cooled, and the cooling effect of the battery pack is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery pack cooling, and in particular to a battery pack cooling circulation method and system. Background Art

[0002] With the technological iteration of electric vehicles, fast charging is currently the mainstream energy replenishment technology direction. The current technical direction mostly uses high voltage and low current for rapid charging and discharging. The cooling system is arranged through the charging pile, and the cooling system of the battery pack is inserted into the cooling system to cool down the charging process. In this way, the battery can maintain the temperature of the cell during high-rate charging, thereby increasing the service life of the cell and reducing the risk of thermal runaway during charging.

[0003] The fast charging process will actually cause the battery cells to generate a lot of heat, which will affect the service life of the battery. When the heat accumulates to a certain level, dangerous events such as thermal runaway will occur. Therefore, how to keep the battery cells at a more comfortable temperature during the fast charging process is the main technical obstacle to fast charging. In the existing technology, the form of using supercharging arrangement to coordinate the control of the thermal management of the entire battery pack is currently in the charging pile, without considering the full working conditions of the entire electric vehicle. As the charging speed becomes faster and faster and the discharge power becomes larger and larger, the current cooling method cannot cover the heat generation difference of the battery cells under all working conditions, such as low heat generation of the battery cells at low speed and high heat generation at high speed. Moreover, the current technology is to achieve the flow rate and flow of the cooling system through signal control. At the same time, this method is one-way, the inlet and outlet are not interchangeable, and the temperature difference of the whole package cannot be adjusted. Summary of the Invention

[0004] In order to solve the above technical problems, an embodiment of the present invention provides a battery pack cooling cycle method and system to solve the technical problem in the prior art of poor cooling effect caused by inconsistent temperature differences in various areas of the battery pack during charging.

[0005] An embodiment of the present invention provides a battery pack cooling cycle method, the method comprising:

[0006] Obtain the temperature of each area of ​​the battery pack during cooling and the current cooling medium flow direction;

[0007] Based on the maximum and minimum temperature values ​​of each area, the temperature difference between any two areas is calculated to obtain multiple temperature difference values. According to the current flow direction of the cooling medium, each temperature difference value is divided according to the preset rules to obtain the corresponding temperature difference set;

[0008] Determine whether the temperature difference set meets the preset conditions. If so, adjust the current cooling medium flow direction and flow state.

[0009] In a possible implementation, each region includes a first region and a second region obtained by dividing according to the physical location distribution of each single battery cell inside the battery pack, and each of the first region and the second region includes a plurality of adjacently arranged sub-regions;

[0010] Each sub-region is determined according to the geometric position of each single battery in the battery pack in three-dimensional space.

[0011] In one possible implementation, the temperature difference values ​​are divided according to the current cooling medium flow direction and a preset rule to obtain a corresponding temperature difference set, including:

[0012] If the current cooling medium flow direction is the first direction, temperature differences obtained according to the maximum temperature value of each sub-region in the first region and the minimum temperature value of each sub-region in the second region are determined as a temperature difference set, and the temperature difference set is determined to be the first temperature difference set;

[0013] If the current cooling medium flow direction is the second direction, the temperature difference values ​​calculated based on the minimum temperature value of each sub-area in the first area and the maximum temperature value of each sub-area in the second area are determined as a temperature difference set, and the temperature difference set is determined to be the second temperature difference set.

[0014] In a possible implementation, the first direction is a direction starting from any sub-area in the second area and sequentially passing through each sub-area in the first area;

[0015] The second direction is a direction starting from any sub-region of the first region and sequentially passing through each sub-region of the second region.

[0016] In one possible implementation, determining whether the temperature difference set satisfies a corresponding preset condition, and if so, adjusting the current flow direction and flow state of the cooling medium, including:

[0017] If the temperature difference set is the first temperature difference set, determining whether the first temperature difference value set satisfies a first preset condition, a second preset condition, or a third preset condition; if the first preset condition is satisfied, causing the cooling medium to flow in the second direction and performing conventional cooling on the battery pack; if the second preset condition is satisfied, causing the cooling medium to flow in the second direction and performing rectangular pulse cooling on the battery pack; and if the third preset condition is satisfied, causing the cooling medium to flow in the second direction and performing zigzag pulse cooling on the battery pack;

[0018] If the temperature difference set is the second temperature difference set, determine whether the second temperature difference value set meets the first preset condition, the second preset condition or the third preset condition. If the first preset condition is met, the cooling medium is made to flow in the first direction and the battery pack is cooled. If the second preset condition is met, the cooling medium is made to flow in the first direction and the battery pack is cooled in a rectangular pulse. If the third preset condition is met, the cooling medium is made to flow in the first direction and the battery pack is cooled in a zigzag pulse.

[0019] In a possible implementation, the first preset condition is that each temperature difference value in the temperature difference set is greater than or equal to a first temperature threshold and less than a second temperature threshold;

[0020] The second preset condition is that a first preset number of temperature difference values ​​in the temperature difference set are greater than or equal to a second temperature threshold;

[0021] The third preset condition is that when there is a temperature difference value in the temperature difference set that is greater than or equal to the second temperature threshold, there are also a second preset number of temperature difference values ​​that are greater than or equal to the first temperature threshold and less than the second temperature threshold.

[0022] In a possible implementation, before obtaining the temperature of each area of ​​the battery pack during cooling, the method further includes:

[0023] Get the current temperature of the entire battery pack while it is charging;

[0024] Determine whether the current temperature is greater than an initial preset temperature threshold. If so, perform normal cooling on the battery pack and obtain temperature values ​​of the battery pack at multiple moments during cooling.

[0025] When the temperature value is greater than the initial preset temperature threshold, and the temperature value at the current moment is continuously greater than the temperature value at the previous moment within the preset time period, the battery pack is pulse cooled, wherein the pulse cooling is sawtooth pulse cooling or rectangular pulse cooling.

[0026] In one possible implementation, rectangular pulse cooling of the battery pack and sawtooth pulse cooling of the battery pack include:

[0027] The first transistor is closed so that the first power source drives the first load to cool the battery pack, and the second transistor is closed and opened according to the first preset switching frequency so that the second power source inputs pulse power according to the first preset duty cycle to drive the second load to cool the battery pack with rectangular pulses;

[0028] The first transistor is closed so that the first power supply drives the first load to cool the battery pack, and the second transistor is closed and opened according to the second preset switching frequency so that the second power supply inputs pulse power according to the second preset duty cycle to drive the second load to perform sawtooth pulse cooling on the battery pack.

[0029] In order to solve the same technical problem, a second aspect of an embodiment of the present invention provides a battery pack cooling circulation system, including an acquisition module, a temperature difference calculation module and a judgment module, wherein:

[0030] An acquisition module is used to obtain the temperature of each area of ​​the battery pack during cooling and the current flow direction of the cooling medium;

[0031] The temperature difference calculation module is used to calculate the temperature difference between any two areas based on the maximum and minimum temperature values ​​of each area, obtain multiple temperature difference values, and divide each temperature difference value according to the current cooling medium flow direction and preset rules to obtain a corresponding temperature difference set;

[0032] The judgment module is used to judge whether the temperature difference set meets the preset conditions. If so, the current flow direction and flow state of the cooling medium are adjusted.

[0033] In a possible implementation, each region includes a first region and a second region obtained by dividing according to the physical location distribution of each single battery cell inside the battery pack, and each of the first region and the second region includes a plurality of adjacently arranged sub-regions;

[0034] Each sub-region is determined according to the geometric position of each single battery in the battery pack in three-dimensional space.

[0035] The technical solution of the present invention has the following advantages:

[0036] The battery pack cooling cycle method provided in an embodiment of the present invention obtains the temperature of each area of ​​the battery pack when it is cooled, and uses the maximum temperature value and the minimum temperature value of each area to calculate the temperature difference between any two areas, and then determines whether each temperature difference value meets the preset conditions. If so, the corresponding cooling operation is performed, and the flow direction and flow rate of the cooling medium are adjusted to ensure that the temperature difference values ​​of each area of ​​the battery pack are consistent when the battery pack is cooled, thereby improving the cooling effect of the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0038] Figure 1 This is a flow chart of a battery pack cooling cycle method according to an embodiment of the present invention;

[0039] Figure 2A diagram illustrating the division of battery pack regions in a battery pack cooling cycle method according to an embodiment of the present invention;

[0040] Figure 3 This is a cooling system control flow chart of the battery pack cooling cycle method according to an embodiment of the present invention;

[0041] Figure 4 Schematic diagram of the first direction of flow of the cooling medium in the battery pack cooling circulation method according to an embodiment of the present invention;

[0042] Figure 5 Schematic diagram of the second flow direction of the cooling medium in the battery pack cooling circulation method according to an embodiment of the present invention;

[0043] Figure 6 This is a diagram of the cooling cycle system architecture of the battery pack cooling cycle method according to an embodiment of the present invention;

[0044] Figure 7 A circuit structure connection diagram of a cooling cycle system of a battery pack cooling cycle method according to an embodiment of the present invention;

[0045] Figure 8 Schematic diagram of rectangular pulse cooling power of the battery pack cooling cycle method according to an embodiment of the present invention;

[0046] Figure 9 Schematic diagram of sawtooth pulse cooling power of the battery pack cooling cycle method according to an embodiment of the present invention;

[0047] Figure 10 This is a system block diagram of a battery pack cooling circulation system according to an embodiment of the present invention;

[0048] The figures are marked as follows: 21, first power supply; 22, second power supply; 31, first resistor; 32, second resistor; 33, variable resistor; 41, first transistor; 42, second transistor; 51, first load; 52, second load; 80, control unit; 60, confluence module; 70, rotary valve; 701, vehicle-end cooling inlet; 702, vehicle-end cooling outlet; 703, pile-end cooling inlet; 704, pile-end cooling outlet. DETAILED DESCRIPTION

[0049] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0050] The battery pack cooling cycle method provided by the embodiment of the present invention is as follows: Figure 1 As shown, Figure 1This is a flow chart of the battery pack cooling cycle method, including steps S101 to S103. The details of each step are as follows:

[0051] S101. Obtain the temperature of each area of ​​the battery pack during cooling and the current flow direction of the cooling medium.

[0052] It is worth noting that the temperature of each area refers to the temperature collected in real time when the battery pack is cooled in a fast charging scenario.

[0053] It can be understood that when users use charging piles to fast charge the battery pack, the battery pack is prone to local overheating under fast charging. At this time, the cooling system on the vehicle and the cooling system of the charging pile cooperate with each other to cool the battery pack, obtain the temperature of different areas in the battery pack and the current flow direction of the cooling medium, so as to facilitate the subsequent calculation of the temperature difference between each area.

[0054] When obtaining the temperature of each area, the temperature of the battery pack is collected through the thermistor set in the battery pack, and the collected temperature is sent to the battery management system. It should be noted that the method of collecting the temperature of each area of ​​the battery pack can also be collected using devices such as thermocouples and non-contact sensors. The type of equipment to be used can be determined according to actual conditions.

[0055] In one embodiment, each region includes a first region and a second region obtained by dividing the region according to the physical location distribution of each single battery cell inside the battery pack, and each of the first region and the second region includes a plurality of adjacently arranged sub-regions;

[0056] Each sub-region is determined according to the geometric position of each single battery in the battery pack in three-dimensional space.

[0057] It's worth noting that the battery pack is divided into the first and second regions based on the physical location of the individual cells within the pack. For example, some cells are located relatively close to the coolant inlet area, while others are located relatively close to the coolant outlet area. Therefore, based on the actual division requirements and the overall layout of the battery pack, a location boundary is set to separate the battery pack into the aforementioned two regions. The first and second regions are then further divided into sub-regions based on the geometric location of each cell. Using this method, the entire battery pack can be divided into multiple regions.

[0058] For example, Figure 2 As shown, Figure 2The figure shows the battery pack area division. Among them, Ⅰ is the first sub-area, Ⅱ is the second sub-area, Ⅲ is the third sub-area, and Ⅳ is the fourth sub-area. It should be noted that the positions of the first sub-area, the second sub-area, the third sub-area, and the fourth sub-area are not based on the Figure 2 In actual application, it can be determined according to the actual situation.

[0059] In addition, when dividing the areas, the thermal field distribution of the battery pack, that is, factors such as temperature gradient, coolant flow direction and heat dissipation path, can also be considered to divide the areas of the battery pack.

[0060] In one embodiment, before obtaining the temperature of each area of ​​the battery pack during cooling, the method further includes:

[0061] Get the current temperature of the entire battery pack while it is charging;

[0062] Determine whether the current temperature is greater than an initial preset temperature threshold. If so, perform normal cooling on the battery pack and obtain temperature values ​​of the battery pack at multiple moments during cooling.

[0063] When the temperature value is greater than the initial preset temperature threshold, and the temperature value at the current moment is continuously greater than the temperature value at the previous moment within the preset time period, the battery pack is pulse cooled, wherein the pulse cooling is sawtooth pulse cooling or rectangular pulse cooling.

[0064] It is worth noting that the current temperature refers to the temperature collected before cooling the battery pack, which is used to determine whether the battery pack needs to be cooled.

[0065] In this embodiment, during the initial charging phase of the battery pack, the battery management system monitors the battery pack temperature in real time. When the battery pack temperature is below an initial preset temperature threshold, the battery management system does not issue a command, the control valve rotates to a closed state, and a signal is input to the charging pile, disabling cooling. If the battery pack temperature is above the initial preset temperature threshold, the battery management system issues a command to rotate the control valve to an open state, and a signal is input to the charging pile to initiate cooling, allowing the battery pack to cool normally.

[0066] Subsequently, the temperature and temperature rise rate of the battery pack are continuously monitored. Specifically, after the battery pack is cooled for a preset time, the temperature of the battery pack at each moment within the preset time period is recorded. If the temperature continues to rise within the preset time period, the battery pack is pulse cooled. For example, when the temperature of the battery pack is still greater than the initial preset temperature threshold, and the temperature values ​​at each moment within the preset time period satisfy β1<β2<……<β n , the battery pack is pulse cooled.

[0067] Among them, β nIndicates the temperature value at the nth moment, n>2, the preset time period can be set to 2s, and the initial preset temperature threshold can be set according to actual needs.

[0068] S102. Based on the maximum temperature value and the minimum temperature value of each area, the temperature difference between any two areas is calculated to obtain multiple temperature difference values. According to the current cooling medium flow direction, each temperature difference value is divided according to a preset rule to obtain a corresponding temperature difference set.

[0069] In this embodiment, the maximum temperature value and the minimum temperature value of each area are used to calculate the temperature difference between any two areas. Then, according to the current flow direction of the cooling medium, the obtained temperature difference values ​​are divided according to preset rules to obtain a corresponding temperature difference set, which is used for subsequent adjustment of the cooling medium direction and flow state according to the temperature difference set.

[0070] It can be understood that, Figure 3 As shown, Figure 3 This is a flow chart of the cooling system control. After the battery pack is pulse-cooled, the temperature of each area of ​​the battery pack during cooling is obtained, and according to the temperature difference in different areas, the state of the rotatable three-way valve 70 is controlled to achieve the flow of the cooling medium in different directions.

[0071] It should be noted that the battery pack cooling cycle control is divided into a pulse cooling module and a temperature zone detection module. The pulse cooling module is used to cool the battery pack after it reaches the cooling conditions. The temperature zone detection calculates the temperature difference between the temperatures of various areas of the battery pack during cooling, and then determines whether to adjust the flow direction and flow state of the cooling medium based on the temperature difference. When cooling the battery pack, pulse cooling and temperature zone detection are operated separately and in parallel. When cooling is turned off, pulse cooling and temperature zone detection are simultaneously turned off.

[0072] In one embodiment, the temperature difference values ​​are divided according to the current cooling medium flow direction and a preset rule to obtain a corresponding temperature difference set, including:

[0073] If the current cooling medium flow direction is the first direction, temperature differences obtained according to the maximum temperature value of each sub-region in the first region and the minimum temperature value of each sub-region in the second region are determined as a temperature difference set, and the temperature difference set is determined to be the first temperature difference set;

[0074] If the current cooling medium flow direction is the second direction, the temperature difference values ​​calculated based on the minimum temperature value of each sub-area in the first area and the maximum temperature value of each sub-area in the second area are determined as a temperature difference set, and the temperature difference set is determined to be the second temperature difference set.

[0075] In this embodiment, the temperature difference value is a quantitative indicator for determining whether the flow direction of the cooling medium needs to be adjusted. Therefore, it is necessary to compare the maximum temperature value and the minimum temperature value of different areas to obtain the temperature difference value, and take corresponding cooling medium flow adjustment measures for different temperature difference ranges to achieve precise temperature control.

[0076] If the current cooling medium flow direction is the first direction, the temperature difference values ​​obtained based on the maximum temperature values ​​of each sub-region in the first region and the minimum temperature values ​​of each sub-region in the second region are divided into a temperature difference set, namely the first temperature difference set. For example, the first temperature difference value, namely Imax-IVmin, is obtained by comparing the maximum temperature value of the first sub-region with the minimum temperature value of the fourth sub-region; the second temperature difference value, namely Imax-IIImin, is obtained by comparing the maximum temperature value of the first sub-region with the minimum temperature value of the third sub-region; the third temperature difference value, namely IImax-IVmin, is obtained by comparing the maximum temperature value of the second sub-region with the minimum temperature value of the fourth sub-region; and the fourth temperature difference value, namely IImax-IIImin, is obtained by comparing the maximum temperature value of the second sub-region with the minimum temperature value of the third sub-region.

[0077] If the current cooling medium flow direction is the second direction, the temperature difference values ​​obtained based on the minimum temperature value of each sub-region in the first region and the maximum temperature value of each sub-region in the second region are divided into a temperature difference set, namely the second temperature difference set. For example, the maximum temperature value of the fourth sub-region and the minimum temperature value of the first sub-region are compared to obtain a fifth temperature difference value, namely IVmax-Imin; the maximum temperature value of the third sub-region and the minimum temperature value of the first sub-region are compared to obtain a sixth temperature difference value, namely IIImax-Imin; the maximum temperature value of the fourth sub-region and the minimum temperature value of the second sub-region are compared to obtain a seventh temperature difference value, namely IVmax-Ⅱmin; and the maximum temperature value of the third sub-region and the minimum temperature value of the second sub-region are compared to obtain an eighth temperature difference value, namely IIImax-Ⅱmin.

[0078] It should be noted that the calculation of the temperature differences in the first or second temperature difference value sets does not rely on a fixed order. Instead, the battery management system independently selects the temperature difference value to be calculated based on the actual monitored temperature and the flow direction of the cooling medium. For example, if the temperature of the first or second sub-area is significantly increased, the battery management system may calculate the first, second, third, and fourth temperature difference values.

[0079] Furthermore, the frequency of temperature difference generation is synchronized with the temperature sampling period to ensure real-time control strategies. For example, the temperature difference value is updated every 5 seconds and the cooling medium flow direction is adjusted based on the latest result.

[0080] In one embodiment, the first direction is a direction starting from any sub-region in the second region and sequentially passing through each sub-region in the first region;

[0081] The second direction is a direction starting from any sub-region of the first region and sequentially passing through each sub-region of the second region.

[0082] In this embodiment, the first direction can be understood as a clockwise direction, which is a direction starting from any sub-region in the second region and passing through each sub-region in the first region in sequence. For example, the cooling medium flows from the fourth sub-region to the first sub-region, that is, in the order of IV→III→II→I. Figure 4 shown.

[0083] The second direction can be understood as a counterclockwise direction, which is the direction starting from any sub-region of the first region and passing through each sub-region of the second region in sequence. For example, the cooling medium flows from the first sub-region to the fourth sub-region, that is, in the order of I→II→III→IV. Figure 5 shown.

[0084] S103: Determine whether the temperature difference set meets the corresponding preset conditions. If so, adjust the current flow direction and flow state of the cooling medium.

[0085] In this embodiment, based on the determined temperature difference set, it is determined whether the temperature difference set meets the corresponding preset conditions. If so, corresponding adjustment measures are adopted to adjust the flow direction and flow state of the cooling medium.

[0086] In one embodiment, determining whether the temperature difference set satisfies a corresponding preset condition, and if so, adjusting the current flow direction and flow state of the cooling medium includes:

[0087] If the temperature difference set is the first temperature difference set, determining whether the first temperature difference value set satisfies a first preset condition, a second preset condition, or a third preset condition; if the first preset condition is satisfied, causing the cooling medium to flow in the second direction and performing conventional cooling on the battery pack; if the second preset condition is satisfied, causing the cooling medium to flow in the second direction and performing rectangular pulse cooling on the battery pack; and if the third preset condition is satisfied, causing the cooling medium to flow in the second direction and performing zigzag pulse cooling on the battery pack;

[0088] If the temperature difference set is the second temperature difference set, determine whether the second temperature difference value set meets the first preset condition, the second preset condition or the third preset condition. If the first preset condition is met, the cooling medium is made to flow in the first direction and the battery pack is cooled. If the second preset condition is met, the cooling medium is made to flow in the first direction and the battery pack is cooled in a rectangular pulse. If the third preset condition is met, the cooling medium is made to flow in the first direction and the battery pack is cooled in a zigzag pulse.

[0089] In this embodiment, after cooling the battery pack, the battery management system calculates the temperature difference between each area in real time, compares each temperature difference in the determined temperature difference set with a set temperature difference threshold, and then adjusts the current cooling medium flow direction and flow state. For example, when the temperature difference obtained by subtracting the minimum value of the first sub-area from the maximum value of the fourth sub-area is greater than the first temperature threshold, the rotatable three-way valve 70 is activated to switch the flow direction, and the cooling medium flow direction is changed to a clockwise flow direction of IV→III→II→I. If the temperature difference obtained by subtracting the minimum value of the first sub-area from the maximum value of the fourth sub-area is greater than the first temperature threshold but less than or equal to the first temperature threshold, cooling is performed in a counterclockwise flow state of I→II→III→IV.

[0090] The temperature of each sub-area is then continuously monitored, and the temperature difference between the sub-areas is calculated. Specifically, if the first temperature difference value set meets the first preset condition, the cooling medium is caused to flow in a counterclockwise direction, pulse cooling of the battery pack is stopped, and conventional cooling of the battery pack is started. If the first temperature difference value set meets the second preset condition, the cooling medium is caused to flow in a counterclockwise direction, and rectangular pulse cooling of the battery pack is performed. If the first temperature difference value set meets the third preset condition, the cooling medium is caused to flow in a counterclockwise direction, and zigzag pulse cooling of the battery pack is performed.

[0091] If the battery management system calculates a second temperature difference set, it then determines the second temperature difference set. Specifically, if the second temperature difference set meets the first preset condition, the cooling medium flows in a clockwise direction to cool the battery pack. If the second temperature difference set meets the second preset condition, the cooling medium flows in a clockwise direction to cool the battery pack using rectangular pulses. If the second temperature difference set meets the third preset condition, the cooling medium flows in a clockwise direction to cool the battery pack using sawtooth pulses.

[0092] In one embodiment, the first preset condition is that each temperature difference value in the temperature difference set is greater than or equal to a first temperature threshold and less than a second temperature threshold;

[0093] The second preset condition is that a first preset number of temperature difference values ​​in the temperature difference set are greater than or equal to a second temperature threshold;

[0094] The third preset condition is that when there is a temperature difference value in the temperature difference set that is greater than or equal to the second temperature threshold, there are also a second preset number of temperature difference values ​​that are greater than or equal to the first temperature threshold and less than the second temperature threshold.

[0095] In this embodiment, the first preset condition is that all temperature difference values ​​in the temperature difference set are greater than or equal to the first temperature threshold and less than the second temperature threshold. The second preset condition is that a first preset number of temperature difference values ​​in the temperature difference set are greater than or equal to the second temperature threshold. The third preset condition is that when one temperature difference value in the temperature difference set is greater than or equal to the second temperature threshold, a second preset number of temperature difference values ​​are also greater than or equal to the first temperature threshold and less than the second temperature threshold.

[0096] It should be noted that the first preset number is preferably 2, and the second preset number is preferably 1. The first temperature threshold can be set to 5°C, and the second temperature threshold can be set to 10°C. Considering the actual monitoring accuracy of thermistors, limiting the temperature difference of all battery cells in the battery pack to within 5°C can ensure the consistency of the battery cells during long-term use. In addition, the current design capability of battery packs is that a temperature difference of more than 10°C within the entire pack will seriously affect the service life, so the second temperature threshold is set to 10°C.

[0097] For example, if the temperature difference set is the first temperature difference set, the first preset condition is that the first temperature difference value, the second temperature difference value, the third temperature difference value, and the fourth temperature difference value are all greater than or equal to the first temperature threshold and less than the second temperature threshold.

[0098] If IImax-IVmin≥5°C and 10>IImax-IIImin≥5°C, the rotatable three-way valve 70 is activated to change the flow direction and the battery pack is cooled normally in a counterclockwise direction.

[0099] The second preset condition is that the first temperature difference and the second temperature difference are both greater than or equal to the second temperature threshold, or the first temperature difference and the fourth temperature difference are greater than or equal to the second temperature threshold. For example: if Imax-IVmin≥10℃ and Imax-Ⅲmin≥10℃ or Ⅱmax-Ⅲmin≥10℃, the rotatable three-way valve 70 is started to change the flow direction so that the cooling medium flows in a counterclockwise flow state, and a rectangular pulse cooling power is output to cause the cooling medium to produce a pulse flow state, thereby performing pulse cooling on the battery pack.

[0100] The third preset condition is that when the first temperature difference is greater than or equal to the second temperature threshold, the second temperature difference is greater than or equal to the first temperature threshold and less than the second temperature threshold, or when the third temperature difference is greater than or equal to the second temperature threshold, the second temperature difference is greater than or equal to the first temperature threshold and less than the second temperature threshold, or the fourth temperature difference is greater than or equal to the first temperature threshold and less than the second temperature threshold. For example, if IImax-IVmin≥10°C and Imax-IIImin≥10°C or IImax-IIImin≥10°C, the rotatable three-way valve 70 is activated to change the flow direction, causing the cooling medium to flow in a counterclockwise direction and output rectangular pulse cooling power, generating a pulsed flow state for pulse cooling of the battery pack.

[0101] If Imax-IVmin≥10℃ and 10>Imax-Ⅲmin≥5℃ or 10>Ⅱmax-Ⅲmin≥5℃, the rotatable three-way valve 70 is started to change the flow direction so that the cooling medium flows in a counterclockwise direction and outputs a sawtooth pulse cooling power. The cooling medium generates a pulse flow state and performs pulse cooling on the battery pack.

[0102] If Ⅱmax-IVmin≥10℃ and 10>Imax-Ⅲmin≥5℃ or 10>Ⅱmax-Ⅲmin≥5℃, the rotatable three-way valve 70 is started to change the flow direction so that the cooling medium flows in a counterclockwise direction and outputs a sawtooth pulse cooling power. The cooling medium generates a pulse flow state and performs pulse cooling on the battery pack.

[0103] If the temperature difference set is the second temperature difference set, the first preset condition is that the fifth temperature difference value, the sixth temperature difference value, the seventh temperature difference value, and the eighth temperature difference value are all greater than or equal to the first temperature threshold and less than the second temperature threshold. For example, if 10>IVmax-Imin≥5℃ and 10>IIImax-Imin≥5℃ and 10>IVmax-Ⅱmin≥5℃ and 10>

[0104] If IIImax-IImin≥5°C, the rotatable three-way valve 70 is activated to change the flow direction so that the cooling medium flows in a clockwise direction and the battery pack is cooled normally.

[0105] The second preset condition is that the fifth temperature difference and the sixth temperature difference are both greater than or equal to the second temperature threshold, or the seventh temperature difference and the sixth temperature difference are both greater than or equal to the second temperature threshold, or the fifth temperature difference and the eighth temperature difference are greater than or equal to the second temperature threshold. For example, if IVmax-Imin≥10℃ and IIImax-Imin≥10℃ or

[0106] If IIImax-IImin≥10°C, the rotatable three-way valve 70 is started to change the flow direction so that the cooling medium flows in a clockwise direction and outputs rectangular pulse cooling power so that the cooling medium produces a pulse flow state.

[0107] If IVmax-Ⅱmin≥10℃ and Ⅲmax-Imin≥10℃ or Ⅲmax-Ⅱmin≥10℃, the rotatable three-way valve 70 is started to change the flow direction, so that the cooling medium flows in a clockwise direction and outputs rectangular pulse cooling power, and the cooling medium produces a pulse flow state.

[0108] The third preset condition is that when the fifth temperature difference is greater than or equal to the second temperature threshold, the sixth temperature difference is greater than or equal to the first temperature threshold and less than the second temperature threshold, or when the seventh temperature difference is greater than or equal to the second temperature threshold, the sixth temperature difference is greater than or equal to the first temperature threshold and less than the second temperature threshold, or the eighth temperature difference is greater than or equal to the first temperature threshold and less than the second temperature threshold. For example, if IVmax-Imin≥10℃ and 10>

[0109] If IIImax-Imin≥5℃ or 10>IIImax-IImin≥5℃, the rotatable three-way valve 70 is activated to change the flow direction, so that the cooling medium flows in a clockwise direction and outputs a sawtooth pulse cooling power, and the cooling medium generates a pulse flow state;

[0110] If IVmax-Ⅱmin≥10℃ and 10>Ⅲmax-Imin≥5℃ or 10>Ⅲmax-Ⅱmin≥5℃, the rotatable three-way valve 70 is started to change the flow direction so that the cooling medium flows in a clockwise direction and outputs a sawtooth pulse cooling power, and the cooling medium produces a pulse flow state.

[0111] In one embodiment, rectangular pulse cooling of a battery pack and sawtooth pulse cooling of a battery pack include:

[0112] The first transistor is closed so that the first power source drives the first load to cool the battery pack, and the second transistor is closed and opened according to the first preset switching frequency so that the second power source inputs pulse power according to the first preset duty cycle to drive the second load to cool the battery pack with rectangular pulses;

[0113] The first transistor is closed so that the first power supply drives the first load to cool the battery pack, and the second transistor is closed and opened according to the second preset switching frequency so that the second power supply inputs pulse power according to the second preset duty cycle to drive the second load to perform sawtooth pulse cooling on the battery pack.

[0114] In this embodiment, if Figure 6 As shown, Figure 6This is a diagram of the cooling cycle system architecture. By connecting the vehicle's cooling system and the charging station's cooling system, a complete cooling cycle is formed. The charging station's cooling system and the vehicle's cooling system have co-located inlet and outlet ports, each equipped with a rotatable three-way valve 70. During charging, the charging unit connects to the vehicle's battery pack's high-voltage connector, and the charging station's control unit communicates with the battery management system and the vehicle controller. Signals from the battery management system are then received to control the charging speed of the charging unit and the cooling method of the cooling unit. The rotatable three-way valve 70 connects the upper and lower cold plates. The valve body rotates to control the flow rate and direction of the cooling system. The rotation angle is controlled by both the battery management system and the vehicle controller. Specifically, the battery management system detects the battery pack temperature and transmits it to the vehicle controller. The valve body determines the valve opening angle and method, and then simultaneously outputs the temperature to the charging station. The charging station controls the cooling unit based on the signals from the battery management system. The vehicle controller and battery management system control the speed and direction of the cooling medium. The control strategy during discharge at the vehicle end is similar, the difference being that the battery management system directly coordinates the signal with the vehicle controller to control the rotation angle of the valve body and thus control the cooling speed and flow direction within the vehicle.

[0115] It should be noted that the rotatable three-way valve 70 includes a vehicle-end cooling inlet 701 , a vehicle-end cooling outlet 702 , a pile-end cooling inlet 703 and a pile-end cooling outlet 704 .

[0116] Figure 7 This is the circuit structure connection diagram of the cooling circulation system, such as Figure 7 As shown, the cooling cycle system has a first power supply 21 and a second power supply 22, which respectively power two loads (cooling cycle compressors), namely the first load 51 and the second load 52. The fluid is then collected in the confluence module 60 to cool the battery pack. The first transistor 41 and the second transistor 42 are both controllable switches controlled by the control unit 80. A variable resistor 33 is connected in parallel in the second power supply 22 circuit, which can be used to control the current flowing into the second load in the circuit, thereby adjusting the peak value of the pulse. In addition, the circuit diagram also includes a first resistor 31 and a second resistor 32.

[0117] It should be noted that the first transistor 51 and the second transistor 52 function as transistors and can achieve a pulse effect by changing the voltage of the P wave output by the battery management system.

[0118] Conventional cooling of the battery pack refers to closing only the first transistor 41 and turning on the first power supply 21, so that the first power supply 21 outputs continuous and stable power to drive the first load 51. At this time, the flow rate of the cooling medium is stable, thereby cooling the battery pack.

[0119] Pulse cooling involves closing the first transistor 41, turning on the first power supply 21, and then, after the first power supply 21 generates continuous and stable power, closing and opening the second transistor 42 at a predetermined switching frequency. This provides intermittent power to the second power supply 22, generating rectangular pulse power or sawtooth pulse power, thereby cooling the battery pack. When rectangular pulse power is generated, the second transistor 42 is closed and opened at a first predetermined switching frequency. When sawtooth pulse power is generated, the second transistor 42 is closed and opened at a second predetermined switching frequency.

[0120] It should be noted that rectangular pulse cooling of the battery pack means that the flow rate of the cooling medium is affected by the rectangular pulse power to produce a pulse flow state, thereby cooling the battery pack. Figure 8 The sawtooth pulse cooling of the battery pack means that the flow rate of the cooling medium is affected by the sawtooth pulse power to produce a pulse flow state, thereby cooling the battery pack. The sawtooth pulse power is as follows: Figure 9 The first preset breaking frequency and the second preset breaking frequency can be set according to actual needs.

[0121] The battery pack cooling circulation system provided by the embodiment of the present invention is as follows: Figure 10 As shown, Figure 10 This is a system block diagram of a battery pack cooling circulation system 1000, including:

[0122] An acquisition module 1001 is used to obtain the temperature of each area of ​​the battery pack during cooling and the current flow direction of the cooling medium;

[0123] The temperature difference calculation module 1002 is used to calculate the temperature difference between any two areas based on the maximum temperature value and the minimum temperature value of each area, obtain multiple temperature difference values, and divide each temperature difference value according to the current cooling medium flow direction and preset rules to obtain a corresponding temperature difference set;

[0124] The judgment module 1003 is used to judge whether the temperature difference set meets the preset conditions. If so, the current flow direction and flow state of the cooling medium are adjusted.

[0125] In one embodiment, each region includes a first region and a second region obtained by dividing the region according to the physical location distribution of each single battery cell inside the battery pack, and each of the first region and the second region includes a plurality of adjacently arranged sub-regions;

[0126] Each sub-region is determined according to the geometric position of each single battery in the battery pack in three-dimensional space.

[0127] The specific implementation of the battery pack cooling circulation system is basically the same as the specific embodiment of the above-mentioned battery pack cooling circulation method, and will not be repeated here.

[0128] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0129] The specific embodiments described above further illustrate the objectives, technical solutions, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A battery pack cooling cycle method, characterized in that: include: Obtain the temperature of each area of ​​the battery pack during cooling and the current cooling medium flow direction; Based on the maximum temperature value and the minimum temperature value of each of the regions, the temperature difference between any two of the regions is calculated to obtain a plurality of temperature difference values, and each of the temperature difference values ​​is divided according to a preset rule based on the current flow direction of the cooling medium to obtain a corresponding temperature difference set; It is determined whether the temperature difference set meets a preset condition. If so, the current flow direction and flow state of the cooling medium are adjusted.

2. The battery pack cooling cycle method according to claim 1, wherein: The regions include a first region and a second region obtained by dividing the regions according to the physical location distribution of the individual cells inside the battery pack, wherein the first region and the second region each include a plurality of adjacently arranged sub-regions; Each of the sub-areas is determined according to the geometric position of each single battery in the battery pack in three-dimensional space.

3. The battery pack cooling cycle method according to claim 1 or 2, characterized in that: The temperature difference values ​​are divided according to a preset rule based on the current cooling medium flow direction to obtain a corresponding temperature difference set, including: If the current cooling medium flow direction is the first direction, determining temperature difference values ​​obtained according to the maximum temperature value of each sub-region in the first region and the minimum temperature value of each sub-region in the second region as a temperature difference set, and determining the temperature difference set as a first temperature difference set; If the current cooling medium flow direction is the second direction, the temperature difference values ​​calculated based on the minimum temperature value of each sub-area in the first area and the maximum temperature value of each sub-area in the second area are determined as a temperature difference set, and the temperature difference set is determined to be the second temperature difference set.

4. The battery pack cooling cycle method according to claim 3, wherein: The first direction is a direction starting from any one of the sub-areas in the second area and sequentially passing through each of the sub-areas in the first area; The second direction is a direction starting from any sub-region of the first region and sequentially passing through each sub-region of the second region.

5. The battery pack cooling cycle method according to claim 3, wherein: The determining whether the temperature difference set satisfies a corresponding preset condition, and if so, adjusting the current flow direction and flow state of the cooling medium, includes: If the temperature difference set is the first temperature difference set, determining whether the first temperature difference value set satisfies a first preset condition, a second preset condition, or a third preset condition; if the first preset condition is satisfied, causing the cooling medium to flow in the second direction and performing conventional cooling on the battery pack; if the second preset condition is satisfied, causing the cooling medium to flow in the second direction and performing rectangular pulse cooling on the battery pack; and if the third preset condition is satisfied, causing the cooling medium to flow in the second direction and performing zigzag pulse cooling on the battery pack; If the temperature difference set is the second temperature difference set, determine whether the second temperature difference value set meets the first preset condition, the second preset condition or the third preset condition. If the first preset condition is met, make the cooling medium flow in the first direction and cool the battery pack. If the second preset condition is met, make the cooling medium flow in the first direction and perform rectangular pulse cooling on the battery pack. If the third preset condition is met, make the cooling medium flow in the first direction and perform sawtooth pulse cooling on the battery pack.

6. The battery pack cooling cycle method according to claim 5, wherein: The first preset condition is that each temperature difference value in the temperature difference set is greater than or equal to a first temperature threshold and less than a second temperature threshold; The second preset condition is that a first preset number of the temperature difference values ​​in the temperature difference set are greater than or equal to a second temperature threshold; The third preset condition is that when one of the temperature difference values ​​in the temperature difference set is greater than or equal to the second temperature threshold, there are also a second preset number of the temperature difference values ​​greater than or equal to the first temperature threshold and less than the second temperature threshold.

7. The battery pack cooling cycle method according to claim 1, wherein: Before obtaining the temperature of each area of ​​the battery pack during cooling, the method further includes: Obtaining a current temperature of the entire battery pack while the battery pack is charging; Determining whether the current temperature is greater than an initial preset temperature threshold, and if so, performing conventional cooling on the battery pack, and obtaining temperature values ​​of the battery pack at multiple moments during cooling; When the temperature value is greater than the initial preset temperature threshold, and the temperature value at the current moment is continuously greater than the temperature value at the previous moment within the preset time period, the battery pack is pulse cooled, wherein the pulse cooling is sawtooth pulse cooling or rectangular pulse cooling.

8. The battery pack cooling cycle method according to claim 6, wherein: The rectangular pulse cooling of the battery pack and the sawtooth pulse cooling of the battery pack include: The first transistor is closed so that the first power source drives the first load to cool the battery pack, and the second transistor is closed and opened according to a first preset switching frequency so that the second power source inputs pulse power according to a first preset duty cycle to drive the second load to cool the battery pack using rectangular pulses; The first transistor is closed so that the first power supply drives the first load to cool the battery pack, and the second transistor is closed and opened according to a second preset switching frequency so that the second power supply inputs pulse power according to a second preset duty cycle to drive the second load to perform sawtooth pulse cooling on the battery pack.

9. A battery pack cooling circulation system, characterized in that: The acquisition module, temperature difference calculation module and judgment module, wherein, The acquisition module is used to obtain the temperature of each area of ​​the battery pack during cooling and the current flow direction of the cooling medium; The temperature difference calculation module is configured to calculate the temperature difference between any two of the regions based on the maximum temperature value and the minimum temperature value of each of the regions to obtain a plurality of temperature difference values, and to divide each of the temperature difference values ​​according to a preset rule based on the current flow direction of the cooling medium to obtain a corresponding temperature difference set; The judgment module is used to judge whether the temperature difference set meets a preset condition, and if so, adjust the current flow direction and flow state of the cooling medium.

10. The battery pack cooling circulation system according to claim 9, characterized in that: The regions include a first region and a second region obtained by dividing the regions according to the physical location distribution of the single cells inside the battery pack, wherein the first region and the second region respectively include a plurality of adjacently arranged sub-regions; Each sub-region is determined according to the geometric position of each single battery in the battery pack in three-dimensional space.

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