Power battery cooling system and cooling method

Abstract

The invention belongs to the technical field of battery cooling control, and provides a power battery cooling system and method, a cooling branch is provided with an electromagnetic valve, and the opening degree of the electromagnetic valve is adjusted according to a signal of a control module so as to increase or reduce a cooling medium flowing through a power battery; all the cooling branches are connected to the cooling equipment in parallel to form a cooling loop; a flow direction switching mechanism is arranged in the cooling loop, and the flow direction switching mechanism is configured to change the direction of the cooling medium flowing through the power battery according to a signal of the control module. The system has the advantages that the battery pack temperature transmitted by the power battery is monitored in real time through the control module, so that the temperature condition of each branch battery is judged, and the consistency of the monomer temperature of the battery during cooling is effectively controlled through dual control of flow and flow direction.

Description

Technical Field

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

[0002] With the development of new energy vehicle technology, thermal management of power batteries is particularly important. Currently, liquid cooling solutions have replaced air cooling solutions and have become the mainstream technology, ensuring the stability and safety of power batteries in high-temperature working environments.

[0003] When the power battery is cooled by multiple branches at the same time, the temperature and flow of the battery cooling system are affected by the number of batteries in series in a single branch and the position of the batteries. In particular, in recent years, the battery configuration has increased in power and the number of branches has increased. If more batteries need to be connected in series in order to reduce the number of branches, then the temperature consistency of each branch battery cell must be controlled. When all battery cells are kept at a similar temperature, the working efficiency of the entire battery pack can be maximized. If some cells are overheated or overcooled, their charging and discharging efficiency will be reduced, which will affect the output power of the entire battery pack. Summary of the invention

[0004] The object of the present invention is to provide a power battery cooling system and a cooling method to solve the above-mentioned problems.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A power battery cooling system, wherein the power battery comprises at least two battery branches, each battery branch comprises at least one battery pack, each battery branch is provided with a corresponding cooling branch, and a cooling medium flows through the battery packs in sequence to cool the power battery; a solenoid valve is provided on the cooling branch, and the solenoid valve adjusts its valve opening by a signal from a control module to increase or decrease the cooling medium flowing through the power battery;

[0007] All cooling branches are connected in parallel to the cooling device to form a cooling circuit; a flow direction switching mechanism is provided in the cooling circuit, and the flow direction switching mechanism is configured to change the direction of the cooling medium flowing through the power battery according to the signal of the control module.

[0008] Furthermore, the control module is configured to detect the temperatures of multiple points in the cooling branch to obtain the highest temperature value and the lowest temperature value in the cooling branch and form a difference between the two; the difference is used to determine the direction in which the cooling medium flows through the power battery.

[0009] Furthermore, a first three-way valve is provided between the inlet of the cooling device and the cooling branch, a first port of the first three-way valve is connected to the inlet of the cooling device, and a second port and a third port of the first three-way valve are respectively connected to two ends of the cooling branch, so that the cooling branch forms a first loop through the first three-way valve;

[0010] A second three-way valve is arranged between the outlet of the cooling device and the cooling branch, the first port of the second three-way valve is connected to the outlet of the cooling device, the second port and the third port of the second three-way valve are respectively connected to the two ends of the cooling branch, so that the cooling branch forms a second loop through the second three-way valve.

[0011] Furthermore, the flow direction switching mechanism includes four control valves; one end of the first control valve is connected to the inlet of the cooling device, and the other end thereof is connected to one end of the cooling branch, one end of the second control valve is connected to the inlet of the cooling device, and the other end thereof is connected to the other end of the cooling branch; one end of the third control valve is connected to the outlet of the cooling device, and the other end thereof is connected to one end of the cooling branch, and one end of the fourth control valve is connected to the outlet of the cooling device, and the other end thereof is connected to the other end of the cooling branch.

[0012] Furthermore, the valve opening of the solenoid valve is determined by the temperature difference between the cooling branch where the solenoid valve is located and other cooling branches.

[0013] Furthermore, an average value of the temperatures of multiple points on the cooling branch is determined as the current temperature value of the cooling branch.

[0014] Furthermore, the control module is configured to adjust the valve opening of the solenoid valve so that the temperature difference of each cooling branch is always within a first preset range.

[0015] The present invention also provides a power battery cooling method, based on the above power battery cooling system, comprising the steps of:

[0016] Detect the temperature value of each point in each cooling branch to obtain the average temperature, maximum temperature and minimum temperature of each cooling branch;

[0017] Determine the valve opening of the solenoid valve in each cooling branch by comparing the average temperature value of each cooling branch;

[0018] The direction in which the cooling medium flows through the power battery is determined based on the difference between the highest temperature and the lowest temperature.

[0019] Furthermore, the valve opening of the solenoid valve is adjusted so that the temperature difference of each cooling branch is always within the first preset range.

[0020] Furthermore, the opening state of the solenoid valve when the previous cooling system ends is used as the opening state of the solenoid valve when the next cooling system starts.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects:

[0022] (1) According to the detected temperature information, the flow direction of the total circuit is adjusted, and the flow of the cooling branch is adjusted at the same time, which enhances the consistency of flow and temperature regulation between different branches;

[0023] (2) Each branch can be equipped with a solenoid valve. Through the cell temperature data uploaded by the battery, the opening of the branch with lower temperature can be adjusted to reduce the flow of the branch with lower temperature, thereby making the flow of each branch consistent, and thus making the temperature of each branch consistent;

[0024] (3) The function of changing the flow direction of the cooling medium in the equipment is achieved by controlling the flow direction switching mechanism, thereby adjusting the temperature difference between the nearest section and the farthest end of the branch, so that the temperature consistency of the battery cells can be effectively controlled, the power battery decays more slowly, and the service life is longer. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 is a schematic diagram of a cooling system in an embodiment of the present invention;

[0027] Figure 2 is a schematic diagram of a cooling system using a three-way valve in an embodiment provided by the present invention;

[0028] Figure 3 is a schematic diagram of a cooling system using a control valve in an embodiment provided by the present invention;

[0029] Figure 4 It is a flow chart of the steps of the power battery cooling method in the embodiment provided by the present invention. DETAILED DESCRIPTION

[0030] It should be noted that in the present invention, descriptions such as "first", "second", "one", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0031] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" 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 be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0033] The following are specific embodiments of the present invention, and the technical solutions of the present invention are further described in conjunction with the accompanying drawings, but the present invention is not limited to these embodiments.

[0034] like Figure 1 As shown, in one embodiment, three battery branches are configured in the power battery, each battery branch includes three battery packs (battery cells), each battery pack is configured with a corresponding cooling pipe, and the cooling pipes on the same battery branch are connected to form a cooling branch, and the two ends of the three cooling branches are connected in parallel to the cooling device, thereby forming a cooling circuit.

[0035] A solenoid valve is provided in each cooling branch. The solenoid valve adjusts its valve opening according to the signal of the control module to increase or decrease the cooling medium flowing through the power battery. When the cooling device is working, by reducing the opening of the solenoid valve, the flow resistance in the cooling branch will increase, thereby reducing the flow of the branch. The reduction in flow will slow down the temperature drop of the battery pack. By controlling the valve opening state of the solenoid valve in different cooling branches, the temperature consistency of each battery branch can be achieved, even if the battery temperature of each battery branch is kept within a certain value range.

[0036] Sensors are installed on the cooling branch pipes and the battery pack to collect the temperature at the current location. The control module takes the average value of the temperature data collected at multiple points in a branch to determine the current temperature value of the cooling branch, and compares this temperature value with the temperature values ​​of other branches to adjust the valve opening state of the solenoid valve.

[0037] When it is detected that the average temperature T1 of branch 1 is higher than the average temperature T2 of branch 2:

[0038] ①When T2+a(constant)>T1≥T2, the solenoid valve does not work and maintains the current opening state;

[0039] ② When T2+b (constant)>T1≥T2+a, close the valve opening k1 (constant) of the solenoid valve of branch 2, thereby increasing the flow resistance of branch 2 and reducing the flow of branch 2, thereby increasing the flow of branch 1 and reducing the temperature of branch 1;

[0040] ③ When T2+c (constant)>T1≥T2+b, close the valve opening k2 (constant) of the solenoid valve of branch 2, thereby increasing the flow resistance of branch 2 and reducing the flow of branch 2, thereby increasing the flow of branch 1 and reducing the temperature of branch 1;

[0041] ④T1≥T2+c, close the valve opening k3 (constant) of the solenoid valve of branch 2, thereby increasing the flow resistance of branch 2 and reducing the flow of branch 2, thereby increasing the flow of branch 1 and reducing the temperature of branch 1.

[0042] Therefore, by controlling the opening of the solenoid valve, the difference in the average temperatures of the three branches (T1, T2, T3) can be controlled within a°C, that is, |T1-T2|<a and |T2-T3|<a and |T1-T3|<a.

[0043] In addition, the solenoid valve opening state at the end of the previous cooling system will be used as the solenoid valve opening state when the cooling system is started next time.

[0044] However, while ensuring the temperature consistency of each branch, since the cooling medium flows through each battery pack in sequence according to the cooling pipeline, the cooling medium will absorb more heat when flowing through the first battery pack in the cooling branch, and will not be able to absorb the heat generated by the two battery packs that flow through later, thereby affecting the working efficiency of the latter two battery packs.

[0045] Therefore, it is proposed to provide a flow direction switching mechanism in the cooling circuit, which is configured to change the direction of the cooling medium flowing through the power battery according to the signal of the control module. By changing the direction of the flow through the battery pack, the battery packs in the same branch can also form temperature consistency.

[0046] like Figure 2 As shown, in one embodiment, the flow direction switching mechanism includes two three-way valves, wherein a first three-way valve is arranged between the inlet of the cooling device and the cooling branch, the first port of the first three-way valve is connected to the inlet of the cooling device, and the second port and the third port of the first three-way valve are respectively connected to the two ends of the cooling branch, so that the cooling branch forms a first loop through the first three-way valve;

[0047] A second three-way valve is arranged between the outlet of the cooling device and the cooling branch, the first port of the second three-way valve is connected to the outlet of the cooling device, the second port and the third port of the second three-way valve are respectively connected to the two ends of the cooling branch, so that the cooling branch forms a second loop through the second three-way valve.

[0048] When the cooling system starts working, the first port and the second port of the first three-way valve are connected, and the third port of the first three-way valve is closed. At the same time, the first port and the second port of the second three-way valve are connected, and the third port of the second three-way valve is closed. The cooling medium flows out from the outlet of the cooling device, flows from bottom to top through each battery branch, and then returns to the inlet of the cooling device.

[0049] When the temperature difference between different battery packs in the same battery branch is too large, it is necessary to change the flow direction of the cooling medium. At this time, the first port and the third port of the first three-way valve are connected, and the second port of the first three-way valve is closed. At the same time, the first port and the third port of the second three-way valve are connected, and the second port of the second three-way valve is closed. The cooling medium will flow through the battery pack from top to bottom along the pipeline to achieve temperature consistency of different battery packs in the same branch.

[0050] In another embodiment, if Figure 3 As shown, the flow direction switching mechanism includes four control valves, one end of the first control valve is connected to the inlet of the cooling device, and the other end thereof is connected to one end of the cooling branch, one end of the second control valve is connected to the inlet of the cooling device, and the other end thereof is connected to the other end of the cooling branch; one end of the third control valve is connected to the outlet of the cooling device, and the other end thereof is connected to one end of the cooling branch, and one end of the fourth control valve is connected to the outlet of the cooling device, and the other end thereof is connected to the other end of the cooling branch.

[0051] Similarly, when the cooling medium needs to flow through the battery pack from bottom to top, just open the first control valve and the fourth control valve and close the second control valve and the third control valve. When the second control valve and the third control valve are opened and the first control valve and the fourth control valve are closed, the cooling medium will flow through the battery pack from top to bottom.

[0052] In controlling the flow direction of the cooling medium, the control module can detect the temperatures of multiple points in the branch to obtain the highest temperature value Tmax and the lowest temperature value Tmin in the branch, and form the difference between the two; this difference is used to determine the direction in which the cooling medium flows through the power battery.

[0053] Preferably, when the cooling medium flows through the battery pack from bottom to top to cool it, the temperature values ​​of the nearest section A and the farthest end B in the branch are respectively used as the minimum temperature value Tmin and the maximum temperature value Tmax.

[0054] When Tmax-Tmin≥d, the flow direction of the cooling medium will be adjusted through the flow direction switching mechanism, thereby changing the direction of the cooling medium entering and exiting the battery pack, thereby reducing the temperature difference between different battery packs.

[0055] In an embodiment, a power battery cooling method is also provided, based on the above power battery cooling system, comprising the steps of:

[0056] Detect the temperature value of each point in each cooling branch to obtain the average temperature, maximum temperature and minimum temperature of each cooling branch;

[0057] Determine the valve opening of the solenoid valve in each cooling branch by comparing the average temperature value of each cooling branch;

[0058] The direction in which the cooling medium flows through the power battery is determined according to the difference between the highest temperature and the lowest temperature.

[0059] In this embodiment, the control module monitors the battery pack temperature transmitted by the power battery in real time, thereby determining the temperature conditions of each branch battery, and through dual control of flow rate and flow direction, the temperature consistency of the battery cells during cooling can be effectively controlled, so that the power battery decays more slowly and its service life becomes longer.

[0060] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A power battery cooling system, wherein the power battery comprises at least two battery branches, each battery branch comprises at least one battery pack, each battery branch is provided with a corresponding cooling branch, and a cooling medium flows through the battery pack in sequence to cool the power battery; a solenoid valve is provided on the cooling branch, and the solenoid valve adjusts its valve opening by a signal from a control module to increase or decrease the cooling medium flowing through the power battery; It is characterized in that All cooling branches are connected in parallel to the cooling device to form a cooling circuit; a flow direction switching mechanism is provided in the cooling circuit, and the flow direction switching mechanism is configured to change the direction of the cooling medium flowing through the power battery according to the signal of the control module.

2. A power battery cooling system according to claim 1, characterized in that: The control module is configured to detect the temperatures of multiple points in the cooling branch to obtain the highest temperature value and the lowest temperature value in the cooling branch and form a difference between the two; the difference is used to determine the direction in which the cooling medium flows through the power battery.

3. A power battery cooling system according to claim 1, characterized in that: A first three-way valve is provided between the inlet of the cooling device and the cooling branch, wherein a first port of the first three-way valve is connected to the inlet of the cooling device, and a second port and a third port of the first three-way valve are respectively connected to two ends of the cooling branch, so that the cooling branch forms a first loop through the first three-way valve; A second three-way valve is arranged between the outlet of the cooling device and the cooling branch, the first port of the second three-way valve is connected to the outlet of the cooling device, the second port and the third port of the second three-way valve are respectively connected to the two ends of the cooling branch, so that the cooling branch forms a second loop through the second three-way valve.

4. A power battery cooling system according to claim 1, characterized in that: The flow direction switching mechanism includes four control valves; one end of the first control valve is connected to the inlet of the cooling device, and the other end thereof is connected to one end of the cooling branch; one end of the second control valve is connected to the inlet of the cooling device, and the other end thereof is connected to the other end of the cooling branch; one end of the third control valve is connected to the outlet of the cooling device, and the other end thereof is connected to one end of the cooling branch; one end of the fourth control valve is connected to the outlet of the cooling device, and the other end thereof is connected to the other end of the cooling branch.

5. A power battery cooling system according to claim 1, characterized in that: The valve opening of the solenoid valve is determined by the temperature difference between the cooling branch where the solenoid valve is located and other cooling branches.

6. A power battery cooling system according to claim 5, characterized in that: An average value of the temperatures of multiple points on the cooling branch is determined as the current temperature value of the cooling branch.

7. A power battery cooling system according to claim 5, characterized in that: The control module is configured to adjust the valve opening of the solenoid valve so that the temperature difference of each cooling branch is always within a first preset range.

8. A power battery cooling method, based on the power battery cooling system according to claim 1, characterized in that: Includes steps: Detect the temperature value of each point in each cooling branch to obtain the average temperature, maximum temperature and minimum temperature of each cooling branch; Determine the valve opening of the solenoid valve in each cooling branch by comparing the average temperature value of each cooling branch; The direction in which the cooling medium flows through the power battery is determined according to the difference between the highest temperature and the lowest temperature.

9. A power battery cooling method according to claim 8, characterized in that: Based on the valve opening adjustment of the solenoid valve, the temperature difference of each cooling branch is always within the first preset range.

10. A power battery cooling method according to claim 8, characterized in that: The solenoid valve opening state at the end of the previous cooling system is used as the solenoid valve opening state when the next cooling system is started.

Images