Battery thermal management circuit and method

Abstract

The invention discloses a battery thermal management circuit and method, which are applied to the technical field of battery charging, the battery thermal management circuit comprises an external power supply distribution unit, a second relay, a Hall sensor, a third relay and a pre-charging resistor which are arranged in the power supply distribution unit, the power supply distribution unit is connected with the positive electrode of a battery pack, and the negative electrode of each battery pack is connected with a relay; when the temperature of one battery pack is too high, the battery pack is charged after power failure and temperature reduction, so that the problem that the temperatures of different battery packs in the whole vehicle are inconsistent in the charging process is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery thermal management, and in particular to a battery thermal management circuit and method. Background Art

[0002] With the expansion of electric vehicle applications, commercial vehicle development is accelerating. However, due to cost and high capacity constraints, battery packs in powertrains are often integrated using two or more battery packs connected in parallel. Furthermore, the voltage of the vehicle's power supply system has been slower to increase compared to that of passenger cars. Consequently, significant heat generation occurs during charging, especially during fast charging. Therefore, current designs often incorporate liquid cooling systems for active cooling during charging. However, since battery packs consist of multiple packs, it's difficult to uniformly control the temperature within each pack. If a pack overheats, all power must be removed for cooling, and charging can resume only after the temperature drops. This reduces charging speed. This is to address the issue of inconsistent temperatures among different battery packs in a vehicle during charging. Summary of the Invention

[0003] In order to solve the above technical problems, an embodiment of the present invention provides a battery thermal management circuit and method to solve the technical problem in the prior art that different battery packs in a vehicle cannot have inconsistent temperatures during charging.

[0004] A first aspect of an embodiment of the present invention provides a battery thermal management circuit, comprising a battery unit, a power distribution unit, and a battery management system, wherein:

[0005] A battery unit, comprising a plurality of battery packs, wherein the negative electrode of each battery pack is connected to a first relay;

[0006] The power distribution unit includes a second relay, a Hall sensor, a third relay and a pre-charging resistor, wherein the first end of the second relay and the first end of the pre-charging resistor are used to connect to the positive pole of the charging interface, the second end of the second relay is connected to the positive pole of each battery pack, the first end of the third relay is connected to the second end of the pre-charging resistor, the second end of the third relay is connected to the positive pole of each battery pack, the negative pole of each battery pack is used to connect to the negative pole of the charging interface, and the Hall sensor is connected to the battery management system.

[0007] In a possible implementation of the first aspect, the negative electrode of each battery pack is connected to a first relay, including:

[0008] A first end of the first relay is connected to the negative electrode of the battery pack, and a second end of the first relay is connected to the negative electrode of the battery pack.

[0009] In a possible implementation of the first aspect, the method further includes:

[0010] The first relay is communicatively connected to the battery management system.

[0011] In a possible implementation of the first aspect, the system further includes a first cooling control unit, a second cooling control unit, and a controller, wherein:

[0012] The first cooling control unit includes: a first power supply, a first transistor, a first capacitor, a first resistor, a second resistor and a first load, wherein:

[0013] A first end of the first resistor is connected to the positive electrode of the first power supply, a second end of the first resistor is connected to the emitter of the first transistor, a first end of the first capacitor, a first end of the second resistor, and a first end of the first load are respectively connected to the collector of the first transistor, a second end of the first load, a second end of the first capacitor, and a second end of the second resistor are respectively connected to the negative electrode of the first power supply, and a controller is connected to the base of the first transistor;

[0014] The second cooling control unit includes: a second power supply, a second transistor, a third resistor and a second load, wherein the positive electrode of the second power supply is connected to the first end of the third resistor, the second end of the third resistor is connected to the emitter of the second transistor, the collector of the second transistor is connected to the first end of the second load, the second end of the second load is connected to the negative electrode of the second power supply, and the base of the second transistor is connected to the controller.

[0015] In a possible implementation of the first aspect, a three-way valve (93) and a confluence module (90) are further included, wherein:

[0016] The first load and the second load are connected to the first end of the confluence module through a confluence pipe, the second end of the confluence module is connected to the first end of the three-way valve through a liquid cooling pipe, and the second end of the three-way valve is connected to the cooling plate of the battery pack through the liquid cooling pipe.

[0017] In a possible implementation manner of the first aspect, the controller is communicatively connected to the battery management system.

[0018] A second aspect of the embodiments of the present invention provides a battery thermal management method, which is implemented by the battery thermal management circuit of the first aspect of the embodiments of the present invention, including:

[0019] Obtaining the temperature of each battery pack during cooling to obtain multiple temperatures after cooling;

[0020] Determining whether the temperatures after cooling are greater than a first preset threshold. If any of the temperatures after cooling are greater than the first preset threshold, calculating the temperature rise rate of the corresponding battery pack and determining whether the temperature rise rate is greater than 0. If so, disconnecting the first relay corresponding to the battery pack to stop charging the battery pack and continue cooling the battery pack.

[0021] The temperature of the battery pack after the first relay is disconnected is collected to obtain an updated temperature. If the updated temperature is less than a third preset threshold, the first relay is closed to enable the charging pile to charge the battery pack.

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

[0023] Get the current temperature of each battery pack under charging conditions;

[0024] Determining whether each current temperature is greater than a first preset threshold and less than a second preset threshold; if any current temperature is greater than the first preset threshold and less than the second preset threshold, calculating the temperature rise rate of the corresponding battery pack and determining whether the temperature rise rate is greater than 0; if so, cooling the battery pack according to the first cooling method; and if less than 0, cooling the battery pack according to the second cooling method;

[0025] If the current temperature is greater than or equal to a second preset threshold, the battery pack is cooled according to a first cooling method, wherein the second preset threshold is greater than the first preset threshold, and the first preset threshold is greater than the third preset threshold.

[0026] In a possible implementation of the second aspect, calculating the temperature rise rate of the corresponding battery pack includes:

[0027] Obtain the temperature of the corresponding battery pack at multiple moments when it is being cooled or not being cooled;

[0028] The temperature rise rate of the corresponding battery pack is calculated based on the temperatures at multiple moments.

[0029] In a possible implementation of the second aspect, the first cooling method is:

[0030] The second transistor is closed so that the second power supply drives the second load to cool the battery pack according to the output power of the first frequency pulse signal, and the first transistor is closed and opened according to the preset switching frequency so that the first power supply drives the first load to cool the battery pack according to the output power of the second frequency pulse signal;

[0031] The second cooling method is:

[0032] The second transistor is closed, so that the second power supply outputs power according to the first frequency pulse signal to drive the second load to cool the battery pack.

[0033] The technical solution of the present invention has the following advantages:

[0034] The battery thermal management circuit provided in an embodiment of the present invention consists of an external power distribution unit, which is equipped with a second relay, a Hall sensor, a third relay and a pre-charging resistor. The power distribution unit is connected to the positive electrode of the battery pack, and a relay is connected to the negative electrode of each battery pack. When the temperature of a battery pack is too high, the battery pack is powered off and cooled, and charging is resumed after the temperature drops, thereby solving the problem of inconsistent temperatures of different battery packs in the entire vehicle during the charging process.

[0035] The battery thermal management method provided by the embodiment of the present invention obtains the temperature of each battery pack during cooling to obtain multiple temperatures after cooling, and determines whether each temperature after cooling is greater than a first preset threshold value. If any temperature after cooling is greater than the first preset threshold value, the temperature rise rate of the corresponding battery pack is calculated to determine whether the temperature rise rate is greater than 0. If it is, the first relay corresponding to the battery pack is disconnected to stop the charging pile from charging the battery pack and continue to cool the battery pack; the temperature of the battery pack after the first relay is disconnected is collected to obtain an updated temperature. If the updated temperature is less than a third preset threshold value, the first relay is closed to enable the charging pile to charge the battery pack, thereby solving the problem of inconsistent temperatures of different battery packs in the entire vehicle during the charging process. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] 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.

[0037] Figure 1 1 is a circuit structure diagram of a battery thermal management circuit according to an embodiment of the present invention;

[0038] Figure 2 This is a structural diagram of a cooling cycle system of a battery thermal management circuit according to an embodiment of the present invention;

[0039] Figure 3 This is an overall structural diagram of a battery thermal management circuit according to an embodiment of the present invention;

[0040] Figure 4 This is a flow chart of a battery thermal management method according to an embodiment of the present invention;

[0041] Figure 5 This is a control flow chart of a battery thermal management method according to an embodiment of the present invention;

[0042] Among them, the figure numbers are as follows: 100, battery cell; 200, power distribution unit; 300, battery management system; 110, first cooling control unit; 120, second cooling control unit; 10, battery pack; 21, first relay; 22, second relay; 41, Hall sensor; 23, third relay; 31, pre-charge resistor; 32, first resistor; 33, second resistor; 34, third resistor; 61, controller; 51, first power supply; 52, second power supply; 81, first transistor; 82, second transistor; 91, first load; 92, second load; 90, convergence module; 93, three-way valve; 71, first capacitor. DETAILED DESCRIPTION

[0043] 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.

[0044] In the description of the present invention, it should be noted that the terms “first”, “second” and “third” are only used for descriptive purposes and should not be understood as indicating or implying relative importance.

[0045] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the term "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can also be internal communication between two components; it can be a wireless connection or a wired connection. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0046] The battery thermal management circuit provided by the embodiment of the present invention is as follows: Figure 1 As shown, it includes a battery unit 100, a power distribution unit 200 and a battery management system 300, wherein:

[0047] The battery unit 100 includes a plurality of battery packs 10, wherein the negative electrode of each battery pack is connected to a first relay 21;

[0048] The power distribution unit 200 includes a second relay 22, a Hall sensor 41, a third relay 23 and a pre-charging resistor 31, wherein the first end of the second relay 22 and the first end of the pre-charging resistor 31 are used to connect to the positive pole of the charging interface, the second end of the second relay 22 is connected to the positive pole of each battery pack 10, the first end of the third relay 23 is connected to the second end of the pre-charging resistor 31, the second end of the third relay 23 is connected to the positive pole of each battery pack 10, the negative pole of each battery pack 10 is used to be connected to the negative pole of the charging interface, and the Hall sensor 41 is connected to the battery management system 300.

[0049] In this embodiment, due to the high heat generated during charging in a commercial vehicle with multiple battery packs in parallel, and the inconsistent state of charge of each pack, the charging power of each pack is inconsistent even when the power supply outputs the same voltage, further leading to inconsistent temperature rise rates for each pack. Therefore, a battery thermal management circuit is proposed. When the temperature rise rate of a battery pack 10 cannot be reduced to zero after cooling, the battery management system 300 can power off the battery pack 10 with a temperature rise rate greater than zero. Meanwhile, the cooling system continues to cool the battery pack 10 after powering off. When the temperature drops to a safe temperature that allows charging to resume, the battery management system 300 controls the relay in the power-off pack to close, allowing charging to resume.

[0050] The entire charging system includes a charging pile end and a vehicle end, wherein the battery thermal management circuit is installed on the vehicle end, specifically including a battery unit 100, a power distribution unit 200 and a battery management system 300. The battery unit 100 includes multiple battery packs 10, wherein the negative pole of each battery pack is connected to a first relay 21. Among them, a battery pack refers to a battery module composed of multiple battery groups connected in series and parallel, which is used to provide continuous power for the vehicle. The number of battery packs can be set according to actual needs, and the battery pack includes multiple single cells (battery cells).

[0051] The power distribution unit is equipped with a second relay 22, a Hall sensor 40, a third relay 23 and a pre-charge resistor 31, which are connected to the positive electrode of each battery pack in the battery unit. Figure 1 As shown, the power distribution unit 200 includes a second relay 22, a Hall sensor 41, a third relay 23 and a pre-charging resistor 31, wherein the first end of the second relay 22 and the first end of the pre-charging resistor 31 are used to connect to the positive pole of the charging interface, the second end of the second relay 22 is connected to the positive pole of each battery pack 10, the first end of the third relay 23 is connected to the second end of the pre-charging resistor 31, the second end of the third relay 23 is connected to the positive pole of each battery pack 10, and the negative pole of each battery pack 10 is used to be connected to the negative pole of the charging interface.

[0052] It should be noted that the second relay 22 is a main positive relay, and the third relay 23 is a pre-charge relay.

[0053] The battery thermal management circuit also includes a battery management system 300, which monitors the entire battery cell. A Hall effect sensor 41 is connected to the battery management system 300, which collects real-time data on each battery pack, including voltage, total current, and temperature. The Hall effect sensor 41 measures the real-time current in the circuit through changes in the magnetic field. If the current is abnormal (such as excessive current due to a failed pre-charge resistor), charging is immediately interrupted.

[0054] In one embodiment, the negative electrode of each battery pack is connected to a first relay 21, including:

[0055] A first end of the first relay 21 is connected to the negative electrode of the battery pack in the battery pack 10 , and a second end of the first relay ( 21 ) is connected to the negative electrode of the battery pack 10 .

[0056] In this embodiment, each battery pack is equipped with a relay, namely a first relay 21, at the negative electrode. The first relay 21 is connected as follows: the first end of the first relay 21 is connected to the negative electrode of the battery pack, and the second end of the first relay 21 is connected to the negative electrode of the battery pack. This means that the first end of the first relay 21 is connected to the negative electrode bus bar within the battery pack, and the second end of the first relay 21 is connected to the total negative electrode of the battery pack, ensuring complete power-off of the battery pack.

[0057] The entire battery cell is monitored by a single battery management system 300. When the temperature rise of one or more battery packs in the battery system exceeds zero under pulse cooling, the battery management system 300 identifies the battery pack location. The battery cell consists of multiple battery packs connected in parallel, each with independent temperature detection. Temperature is collected by thermistors (Negative Temperature Coefficient Thermistors) within each pack.

[0058] In one embodiment, the first relay 21 is in communication with the battery management system 300 .

[0059] In this embodiment, the first relay 21 is in communication with the battery management system 300. After the thermistors in each battery pack detect the battery pack temperature, they transmit the acquired temperature information to the battery management system 300. The battery management system 300 identifies the temperature information of each battery pack, determines the temperature rise of each battery pack based on the temperature, and issues a command to open the first relay 21. Simultaneously, both the powered and unpowered battery packs are cooled using a pulse cooling method. When the powered battery pack cools down to a temperature range suitable for charging, the battery management system 300 issues a command to close the relay, and the battery resumes charging.

[0060] In one embodiment, the first cooling control unit 110, the second cooling control unit 120 and the controller 61 are further included, wherein:

[0061] The first cooling control unit 110 includes: a first power supply 51, a first transistor 81, a first capacitor 71, a first resistor 32, a second resistor 33 and a first load 91, wherein:

[0062] A first end of the first resistor 32 is connected to the positive electrode of the first power supply 51, a second end of the first resistor 32 is connected to the emitter of the first transistor 81, a first end of the first capacitor 71, a first end of the second resistor 33, and a first end of the first load 91 are respectively connected to the collector of the first transistor 81, a second end of the first load 91, a second end of the first capacitor 71, and a second end of the second resistor 33 are respectively connected to the negative electrode of the first power supply 51, and the controller 61 is connected to the base of the first transistor 81;

[0063] The second cooling control unit 120 includes: a second power supply 52, a second transistor 82, a third resistor 34 and a second load 92, wherein the positive electrode of the second power supply 52 is connected to the first end of the third resistor 34, the second end of the third resistor 34 is connected to the emitter of the second transistor 82, the collector of the second transistor 82 is connected to the first end of the second load 92, the second end of the second load 92 is connected to the negative electrode of the second power supply 52, and the base of the second transistor 82 is connected to the controller 61.

[0064] In this embodiment, the battery thermal management circuit is further connected to the first cooling control unit 110, the second cooling control unit 120 and the controller 61. Figure 3As shown, the first cooling control unit 110 is composed of a first power supply 51, a first transistor 81, a first capacitor 71, a first resistor 32, a second resistor 33 and a first load 91. The first end of the first resistor 32 is connected to the positive electrode of the first power supply 51, the second end of the first resistor 32 is connected to the emitter of the first transistor 81, the first end of the first capacitor 71, the first end of the second resistor 33 and the first end of the first load 91 are respectively connected to the collector of the first transistor 81, the second end of the first load 91, the second end of the first capacitor 71 and the second end of the second resistor 33 are respectively connected to the negative electrode of the first power supply 51, and the controller 61 is connected to the base of the first transistor 81.

[0065] The second cooling control unit 120 includes a second power supply 52, a second transistor 82, a third resistor 34, and a second load 92. The positive electrode of the second power supply 52 is connected to the first end of the third resistor 34, the second end of the third resistor 34 is connected to the emitter of the second transistor 82, the collector of the second transistor 82 is connected to the first end of the second load 92, the second end of the second load 92 is connected to the negative electrode of the second power supply 52, and the base of the second transistor 82 is connected to the controller 61. Both the second transistor 82 and the first transistor 81 are controllable switches, controlled by the control unit to achieve a certain switching frequency. Both the second transistor 82 and the first transistor 81 function as transistors, and can achieve a pulse effect by varying the voltage of the P wave output by the battery management system 300. A variable resistor is connected in parallel with the first power supply 51 circuit to control the current flowing into the first load 91, thereby adjusting the peak value of the rectangular pulse.

[0066] Specifically, the above-mentioned first cooling control unit 110 and second cooling control unit 120 together constitute a cooling circulation system. The corresponding loads (first load 91 and second load 92) are respectively powered by their respective power supplies (first power supply 51 and second power supply 52), so that the cooling medium is gathered in the convergence module, thereby realizing a cooling cycle and cooling the battery pack. The cooling circulation system can be installed at the charging pile end or the vehicle end. If it is installed at the charging pile end, the cooling system at the charging pile end can be used for the cooling cycle in the cooling circulation system. If it is installed at the vehicle end, the vehicle cooling system can be used for the cooling cycle of the cooling circulation system. In actual application, under charging conditions, the battery management system 300 outputs control instructions to the controller 61 at the charging pile end or the vehicle end according to the collected battery pack temperature, so that the controller 61 controls the cooling circulation system and cools the battery pack 10.

[0067] In one embodiment, a three-way valve 93 and a confluence module 90 are further included, wherein:

[0068] The first load 91 and the second load 92 are connected to the first end of the confluence module 90 through a confluence pipe, the second end of the confluence module 90 is connected to the first end of the three-way valve 93 through a liquid cooling pipe, and the second end of the three-way valve 92 is connected to the cooling plate of the battery pack through the liquid cooling pipe.

[0069] In this embodiment, after the first load 91 and the second load 92 are connected to the first end of the convergence module 90 through the convergence pipe, when connected to the battery pack, the second end of the convergence module 90 is connected to the first end of the three-way valve 93 through the liquid cooling pipe, and the second end of the three-way valve 93 is connected to the cooling plate of the battery pack through the liquid cooling pipe, thereby circulating cooling the battery pack.

[0070] In one embodiment, the controller 61 is in communication with the battery management system 300 .

[0071] In this embodiment, if Figure 3 As shown, the controller 61 is in communication with the battery management system 300 and is used to receive control instructions sent by the battery management system 300. As an example, the battery management system 300 collects battery temperature through a thermistor, converts the collected voltage analog signal into a digital signal through the analog front end (AEF), and then transmits it to the battery management system 300 for logical operation to obtain a control instruction, and then sends the control instruction obtained after the operation to the controller 61. The controller turns on the cooling unit according to the received control instruction. It should be noted that the control instruction can be understood as an instruction on whether cooling needs to be turned on and what kind of cooling method to turn on.

[0072] The battery thermal management method provided by the embodiment of the present invention is as follows: Figure 4 FIG. 4 is a flow chart of a battery thermal management method according to an embodiment of the present invention, including steps S401 to S403. The details of each step are as follows:

[0073] S401 : Acquire the temperature of each battery pack during cooling to obtain a plurality of temperatures after cooling.

[0074] In this embodiment, the battery management system 800 collects the temperature of each battery pack 10 in the battery unit 100 through a thermistor. When the temperature of the battery unit 100 under charging conditions reaches a point where cooling is required, the controller 61 controls the first cooling control unit 110 and the second cooling control unit 120 to cool the battery pack. After cooling for a period of time, the battery management system 300 continues to monitor the temperature of each battery pack to obtain the temperature of each battery pack after cooling.

[0075] It should be noted that the temperature after cooling refers to the temperature collected when the battery pack is cooling.

[0076] In one embodiment, before obtaining the temperature of each battery pack during cooling, the process includes:

[0077] Get the current temperature of all battery packs under charging conditions;

[0078] Determining whether each current temperature is greater than a first preset threshold and less than a second preset threshold; if any current temperature is greater than the first preset threshold and less than the second preset threshold, calculating the temperature rise rate of the corresponding battery pack and determining whether the temperature rise rate is greater than 0; if so, cooling the battery pack according to the first cooling method; and if less than 0, cooling the battery pack according to the second cooling method;

[0079] If the current temperature is greater than or equal to a second preset threshold, the battery pack is cooled according to a first cooling method, wherein the second preset threshold is greater than the first preset threshold, and the first preset threshold is greater than the third preset threshold.

[0080] In this embodiment, the temperature of all battery packs 10 in the initial stage of charging is obtained to obtain the current temperature. When all battery packs 10 are charging and the current temperature is low, such as lower than the first preset threshold, the battery management system 300 inputs a signal to the charging pile end and does not start cooling.

[0081] like Figure 5 As shown, when the current temperature of each battery pack 10 is greater than or equal to the second preset threshold and less than the first preset threshold, the temperature rise rate is further judged. If the temperature rise rate is greater than 0, the battery management system 300 starts cooling, and the battery management system 300 outputs to the charging pile end through CAN to close the second transistor 82, so that the second power supply 52 supplies power to the second load, and closes the first transistor 81, so that the first transistor 81 drives the first power supply 51 to supply power to the first load 91 according to the switching frequency duty cycle (duty cycle is less than 70%), thereby realizing pulse cooling.

[0082] If the temperature rise rate is less than 0, the battery management system 300 outputs a signal to the charging station via CAN to close the second transistor 82, powering the second load 92 via the second power supply 52, for conventional supercharge cooling. If the current temperature is greater than or equal to the second preset threshold, pulse cooling is directly initiated.

[0083] It should be noted that the second preset threshold is greater than the first preset threshold, and the first preset threshold and the second preset threshold can be determined according to actual conditions.

[0084] In one embodiment, the first cooling method is:

[0085] The second transistor is closed so that the second power supply drives the second load to cool the battery pack according to the output power of the first frequency pulse signal, and the first transistor is closed and opened according to the preset switching frequency so that the first power supply drives the first load to cool the battery pack according to the output power of the second frequency pulse signal;

[0086] The second cooling method is:

[0087] The second transistor is closed, so that the second power supply outputs power according to the first frequency pulse signal to drive the second load to cool the battery pack.

[0088] In this embodiment, the first cooling method refers to cooling the battery using pulse cooling. Specifically, when pulse cooling is used to cool the battery, the second transistor is closed, the second power supply is activated, and continuous and stable power is generated to drive the second load to cool the battery pack. This indicates that the flow rate of the cooling medium is also stable. At the same time, the first transistor is closed and opened at a preset switching frequency, so that the first power supply generates intermittent power through the opening and closing of the first transistor, and the power output is driven by the second frequency pulse signal to cool the battery pack. The first and second power supplies work together to generate rectangular pulse power, which causes the flow rate of the cooling medium to be affected by the power, resulting in a pulse flow state, thereby achieving pulse cooling.

[0089] The second cooling method refers to using conventional supercharge cooling to cool the battery. Specifically, when using the conventional supercharge cooling method to cool the battery, only the second transistor is closed to make the second power supply work, generating continuous and stable power to drive the second load to cool the battery pack.

[0090] In one embodiment, calculating the temperature rise rate of the corresponding battery pack includes:

[0091] Obtain the temperature of the corresponding battery pack at multiple moments when it is being cooled or not being cooled;

[0092] The temperature rise rate of the corresponding battery pack is calculated based on the temperatures at multiple moments.

[0093] In this embodiment, the temperature of the battery pack to be calculated is collected at preset time intervals when it is cooled or not cooled, and the temperature rise rate is obtained by the temperature at the current moment and the temperature at the previous moment. As an example, the temperature sensor records multiple moments (t1, t2, t3, t4...t n ) corresponding temperature values ​​(T1, T2, T3, T4...T n ), calculate the temperature difference and time difference of adjacent time points, and then calculate the ratio of the temperature difference and time difference of adjacent time points to obtain the temperature rise rate.

[0094] S402. Determine whether the temperature after cooling is greater than a first preset threshold. If any of the temperatures after cooling is greater than the first preset threshold, calculate the temperature rise rate of the corresponding battery pack and determine whether the temperature rise rate is greater than 0. If it is, disconnect the first relay corresponding to the battery pack to stop charging the battery pack and continue cooling the battery pack.

[0095] In this embodiment, battery cooling typically involves pulse cooling. The battery management system monitors the temperature within each battery pack. If the cooled temperature of one or more battery packs exceeds a first preset threshold and the temperature rise rate exceeds zero, the battery management system 300 disconnects the first relay 21 for the battery pack with a temperature rise rate exceeding zero. After disconnection, charging continues for the remaining battery packs, while the cooling unit activates pulse cooling for the battery packs currently charging and those that have been powered off.

[0096] It should be noted that the first preset threshold is greater than the third preset threshold, and the third preset threshold can be determined according to actual needs.

[0097] As an example, the cooling is turned on in combination with the temperature determination of the battery pack. At this time, the battery management system 300 sends a signal to the controller of the charging pile end or the vehicle end via CAN, closes the second transistor 82, and supplies power to the cooling circulation system for cooling. When the temperature after cooling is ≥ the second preset threshold, the battery management system 300 sends a signal to the vehicle end or the charging pile end, closes the second transistor 82, and the second power supply 52 supplies power to the cooling circulation system. The first transistor 81 is closed and disconnected at a certain switching frequency, and the auxiliary power output of the first power supply 51 is controlled according to the duty cycle, thereby generating a pulsed power output, realizing a pulsed change in flow rate, and enhancing the heat exchange rate of the pipe wall of the liquid cooling system, thereby realizing pulsed cooling. Among them, the cooling circulation system has a dual channel, which brings together two parts of fluid with different flow rates through a confluence module, and then cools the battery pack.

[0098] Because pulse cooling is used in each battery pack, the charge state of each battery pack is inconsistent, resulting in inconsistent heat generation. However, the cooling effect is affected by a single cooling system, so the cooling effect is also inconsistent. When it is determined that the use of pulse cooling still cannot reduce the temperature rise of one or more packs to below 0, the battery management system disconnects the first relay at the negative electrode of the battery pack with a temperature rise rate greater than 0, and stops charging the battery pack with a temperature rise rate greater than zero. However, at this time, the cooling system still uses pulse cooling to cool the power-off and charging battery packs.

[0099] S403: collecting the temperature of the battery pack after the first relay is disconnected to obtain an updated temperature. If the updated temperature is less than a third preset threshold, closing the first relay to enable the charging pile to charge the battery pack.

[0100] In this embodiment, the battery management system detects whether the temperature of the disconnected battery pack has dropped below a third preset threshold. This temperature determines whether the relay should close. When the temperature drops below the third preset threshold, the first relay is reclosed, and the disconnected battery packs continue to charge. If the temperature within the battery pack remains above the third preset threshold, one or more high-temperature battery packs are disconnected from charging. If the battery pack detects that the updated temperature is below the first preset threshold, the battery management system outputs a command to stop cooling the charging station.

[0101] 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.

[0102] 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 thermal management circuit, characterized in that: The invention comprises a battery unit (100), a power distribution unit (200) and a battery management system (300), wherein: The battery unit (100) includes a plurality of battery packs (10), wherein the negative electrode of each battery pack is connected to a first relay (21); The power distribution unit (200) comprises a second relay (22), a Hall sensor (41), a third relay (23) and a pre-charging resistor (31), wherein the first end of the second relay (22) and the first end of the pre-charging resistor (31) are used to be connected to the positive pole of the charging interface, the second end of the second relay (22) is connected to the positive pole of each battery pack (10), the first end of the third relay (23) is connected to the second end of the pre-charging resistor (31), the second end of the third relay (23) is connected to the positive pole of each battery pack (10), the negative pole of each battery pack (10) is used to be connected to the negative pole of the charging interface, and the Hall sensor (41) is connected to the battery management system (300).

2. The battery thermal management circuit according to claim 1, wherein: The negative electrode of each battery pack is connected to a first relay (21), comprising: A first end of the first relay (21) is connected to the negative electrode of the battery pack in the battery pack (10), and a second end of the first relay (21) is connected to the negative electrode of the battery pack (10).

3. The battery thermal management circuit according to claim 1, wherein: Also includes: The first relay (21) is in communication connection with the battery management system (300).

4. The battery thermal management circuit according to claim 1, wherein: It also includes a first cooling control unit (110), a second cooling control unit (120) and a controller (61), wherein: The first cooling control unit (110) comprises: a first power supply (51), a first transistor (81), a first capacitor (71), a first resistor (32), a second resistor (33) and a first load (91), wherein: The first end of the first resistor (32) is connected to the positive electrode of the first power supply (51), the second end of the first resistor (32) is connected to the emitter of the first transistor (81), the first end of the first capacitor (71), the first end of the second resistor (33), and the first end of the first load (91) are respectively connected to the collector of the first transistor (81), the second end of the first load (91), the second end of the first capacitor (71), and the second end of the second resistor (33) are respectively connected to the negative electrode of the first power supply (51), and the controller (61) is connected to the base of the first transistor (81); The second cooling control unit (120) comprises: a second power supply (52), a second transistor (82), a third resistor (34) and a second load (92), wherein the positive electrode of the second power supply (52) is connected to the first end of the third resistor (34), the second end of the third resistor (34) is connected to the emitter of the second transistor (82), the collector of the second transistor (82) is connected to the first end of the second load (92), the second end of the second load (92) is connected to the negative electrode of the second power supply (52), and the base of the second transistor (82) is connected to the controller (61).

5. The battery thermal management circuit according to claim 1 or 4, characterized in that: It also includes a three-way valve (93) and a confluence module (90), wherein: The first load (91) and the second load (92) are connected to a first end of a confluence module (90) via a confluence pipe, a second end of the confluence module (90) is connected to a first end of the three-way valve (93) via a liquid cooling pipe, and a second end of the three-way valve (93) is connected to a cooling plate of the battery pack (10) via a liquid cooling pipe.

6. The battery thermal management circuit according to claim 1 or 4, characterized in that: The controller (61) is in communication connection with the battery management system (300).

7. A battery thermal management method, characterized in that: The method is implemented by the battery thermal management circuit according to any one of claims 1 to 6, comprising: Acquiring the temperature of each battery pack during cooling to obtain a plurality of post-cooling temperatures; determining whether each of the cooled temperatures is greater than a first preset threshold; if any of the cooled temperatures is greater than the first preset threshold, calculating a temperature rise rate of the corresponding battery pack, determining whether the temperature rise rate is greater than 0; if so, disconnecting the first relay corresponding to the battery pack to cause the charging pile to stop charging the battery pack and continue cooling the battery pack; The temperature of the battery pack after the first relay is disconnected is collected to obtain an updated temperature. If the updated temperature is less than a third preset threshold, the first relay is closed to enable the charging pile to charge the battery pack.

8. The battery thermal management method according to claim 5, wherein: Before obtaining the temperature of each battery pack during cooling, the method includes: Obtaining the current temperature of each battery pack under charging conditions; determining whether each of the current temperatures is greater than a first preset threshold and less than a second preset threshold; if any of the current temperatures is greater than the first preset threshold and less than the second preset threshold, calculating a temperature rise rate of the corresponding battery pack, and determining whether the temperature rise rate is greater than 0; if so, cooling the battery pack according to a first cooling method; and if so, cooling the battery pack according to a second cooling method; If the current temperature is greater than or equal to the second preset threshold, the battery pack is cooled according to a first cooling method, wherein the second preset threshold is greater than the first preset threshold, and the first preset threshold is greater than the third preset threshold.

9. The battery thermal management method according to claim 7, wherein: The calculating the corresponding temperature rise rate of the battery pack includes: Obtaining the temperature of the corresponding battery pack at multiple moments when cooling or not cooling; The temperature rise rate of the corresponding battery pack is calculated based on the temperatures at the multiple moments.

10. The battery thermal management method according to claim 8, wherein: The first cooling method is: The second transistor is closed so that the second power supply outputs power according to the first frequency pulse signal to drive the second load to cool the battery pack, and the first transistor is closed and opened according to a preset switching frequency so that the first power supply outputs power according to the second frequency pulse signal to drive the first load to cool the battery pack; The second cooling method is: The second transistor is closed, so that the second power supply outputs power according to the first frequency pulse signal to drive the second load to cool the battery pack.

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