A power battery liquid cooling control method and system

Abstract

The present invention discloses a method for controlling liquid cooling of a power battery, which sets corresponding control strategies for different vehicle states in advance. Each control strategy sets multiple cooling liquid gears according to the current maximum temperature of the single cell battery, and each cooling liquid gear is preset with a corresponding cooling liquid request power. When the system is working, it identifies the current vehicle state; executes the corresponding control strategy according to the current vehicle state; obtains the current maximum temperature of the single cell battery in real time, and executes the cooling liquid gear according to the current maximum temperature of the single cell battery. The present invention sets three fixed power gears according to the temperature of the temperature probe, and establishes real-time power gears according to the change of the water inlet temperature, maintains the coolant temperature at the target temperature, and sets signal stabilization at the same time to prevent the temperature acquisition jitter from causing rapid power jumps; sets the liquid cooling system state to facilitate troubleshooting.

Description

Technical Field

[0001] The present invention relates to the field of power batteries, and in particular to power battery cooling technology. Background Art

[0002] With the gradual deterioration of the global climate, the intensification of urban air pollution and the over-consumption of oil resources, the development of energy-saving and environmentally friendly vehicles has become an important direction for technological innovation in the world's automotive industry and an inevitable choice for the sustainable development of the automotive industry. As the heart of new energy vehicles, batteries have the same important position as traditional fuel engines, and also require the same cooling system to ensure their stable and efficient operation.

[0003] At present, there are many cooling methods for power batteries, and liquid cooling is the most common. For example, the publication number is CN117913424A, the publication date is April 19, 2024, and the patent name is "A liquid cooling control strategy for battery packs and PCS in energy storage systems". The disclosed energy storage system battery pack and PCS liquid cooling control strategy, the control steps are as follows: Step 1: First, according to whether the collected minimum battery temperature is lower than 10°C, when it is lower than 10°C, enter process 1, turn on the heating mode, and the outlet water temperature is 25°C. When the minimum battery temperature is not greater than 15°C, continue the heating mode and the outlet water temperature is 25°C. When the minimum battery temperature is higher than 15°C, the water cooling unit stops working; Step 2: When the battery temperature is greater than or equal to 10°C, enter process 2 or process 3, and the judgment condition is the PCS running state. When the PCS is running, enter process 2, and when the PCS is not in running state, enter process 3; Step 3: When the PCS is running, enter process 2 and turn on the self-circulation mode of the water cooling unit; Step 4: When the PCS stops running, enter process 3.

[0004] As users' requirements for vehicles increase, battery discharge power is also increasing. Traditional air cooling can no longer meet the heat dissipation needs of the battery system. Liquid cooling systems are gradually being used in battery cooling. However, in order to achieve efficient liquid cooling effects, while the hardware equipment meets the requirements, a set of efficient control strategies is also needed to achieve perfect control. Summary of the invention

[0005] The technical problem to be solved by the present invention is to realize a power battery liquid cooling control method and system, which can efficiently complete functions such as cooling request, power control, self-state monitoring and signal stabilization.

[0006] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a power battery liquid cooling control method, in which corresponding control strategies are pre-set for different vehicle states, each control strategy sets multiple cooling liquid gears according to the current maximum temperature of the single battery, and each cooling liquid gear is preset with a corresponding cooling liquid request power;

[0007] When the system is working, it identifies the current vehicle status;

[0008] Execute corresponding control strategy according to the current vehicle state;

[0009] The current maximum temperature of the single battery is obtained in real time, and the cold liquid gear is executed according to the current maximum temperature of the single battery.

[0010] The vehicle status includes: fast charging status, slow charging status and discharging status.

[0011] In the fast charging state, when the maximum temperature of the monomer is ≥T11, the first gear is entered, a liquid cooling request is sent, and power P1 is requested; when the maximum temperature of the monomer is ≥T12, the second gear is entered, a liquid cooling request is sent, and power P2 is requested; when the maximum temperature of the monomer is ≥T13, the third gear is entered, a liquid cooling request is sent, and power P3 is requested, wherein T11>T12>T13, P1>P2>P3.

[0012] In the slow charging state: when the maximum temperature of the monomer is ≥T111°C, the first gear is entered, a liquid cooling request is sent, and power P1 is requested; when the maximum temperature of the monomer is ≥T112, the second gear is entered, a liquid cooling request is sent, and power P2 is requested; when the maximum temperature of the monomer is ≥T113, the third gear is entered, a liquid cooling request is sent, and power P3 is requested, wherein T111>T112>T113, P1>P2>P3.

[0013] In the discharge state: when the maximum temperature of the monomer is ≥T111°C, the first gear is entered, a liquid cooling request is sent, and power P1 is requested; when the maximum temperature of the monomer is ≥T112, the second gear is entered, a liquid cooling request is sent, and power P2 is requested; when the maximum temperature of the monomer is ≥T113, the third gear is entered, a liquid cooling request is sent, and power P3 is requested, wherein T111>T112>T113, P1>P2>P3.

[0014] When the system is working, the current water inlet of the cooling liquid is obtained in real time. When the water inlet temperature is lower than T20, the system enters the real-time power calculation mode. The real-time power calculation mode is the highest priority mode. The cooling liquid request power is obtained by multiplying the difference between the current cooling liquid target temperature T21 and T20 by the preset coefficient.

[0015] In the real-time power calculation mode:

[0016] Coolant required power = (T20-T21)*3281*1.073*0.2Kw;

[0017] The calculated power is set to filter for 10 seconds, and the output power is switched after each change in the water inlet temperature lasts for 10 seconds.

[0018] When the system is working, the gear is only allowed to rise. When the maximum temperature of the single cell is less than T10 in the fast charging state, the liquid cooling state is exited. When the maximum temperature of the single cell is less than T110 in the slow charging state and the discharging state, the liquid cooling state is exited.

[0019] When the vehicle is in fast charging, slow charging or discharging state, and does not meet the liquid cooling mode, if the cell temperature difference is ≥ T3, the average temperature mode is turned on. The liquid cooling request power of the average temperature mode is 0, and only the water pump is turned on. When the cell temperature difference is less than the set value, the average temperature mode is exited.

[0020] A power battery liquid cooling control system, the system's BMS is connected to a vehicle network and obtains the temperature of a power battery cell, a temperature sensor is provided at a water inlet of the cooling liquid system, the temperature sensor is connected to and outputs a temperature signal to the BMS, the BMS is connected to and outputs a drive signal to a cooling system, and the system executes the power battery liquid cooling control method.

[0021] The present invention sets three fixed powers according to the temperature of the temperature probe, and establishes real-time power gears according to the change of the water inlet temperature, so as to maintain the coolant temperature at the target temperature. At the same time, signal stabilization is set to prevent rapid power jumps caused by temperature collection jitter; the liquid cooling system status is set to facilitate fault troubleshooting. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The following is a brief description of the contents expressed in each figure in the specification of the present invention:

[0023] Figure 1 This is the fast charging state control flow chart;

[0024] Figure 2 This is a flow chart of the control of slow charging driving state;

[0025] Figure 3 This is the flow chart of the uniform temperature mode. DETAILED DESCRIPTION

[0026] The following is a further detailed description of the specific implementation methods of the present invention, such as the shape, structure, relative position and connection relationship between the various components involved, the function and working principle of each part, the manufacturing process and operation method, etc., through the description of the embodiments with reference to the accompanying drawings, so as to help those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention.

[0027] The system is equipped with a BMS, and the BMS system status is divided into high-voltage driving, fast charging and slow charging status. In different statuses, the maximum temperature probe temperature is higher than different threshold conditions, and the system enters the first, second and third gears, sending cooling requests and corresponding power. The BMS is connected to the vehicle network and obtains the temperature of the power battery cells. It is necessary to obtain the temperature of each cell of the power battery, and use the values ​​of these problems for more precise control. The vehicle network is a CAN network. In addition, a temperature sensor is required at the water inlet of the cooling liquid system. The temperature sensor can obtain the water temperature at the water inlet of the cooling liquid system. The temperature sensor is connected and outputs a temperature signal to the BMS. The BMS is connected and outputs a drive signal to the cooling system. The system executes the power battery liquid cooling control method.

[0028] During control, when the water inlet temperature is lower than the set threshold, a cooling request is sent, and the cooling power is dynamically calculated according to a predetermined formula to maintain the water inlet temperature at the ideal temperature.

[0029] When the maximum temperature probe temperature does not meet any gear threshold and the water inlet temperature does not meet the threshold for entering the dynamic calculation of cooling power, if the temperature difference is greater than a certain threshold, a temperature equalization request is sent and the cooling power is zero.

[0030] When the maximum temperature probe temperature is lower than the exit temperature of each state, exit cooling.

[0031] The system divides the vehicle status into three, namely fast charging status, discharging status and slow charging status, and executes different control strategies in different status. First, the status judgment is made, and then the program is executed according to the pre-selected settings. The execution program directly selects the gear through a simple threshold comparison, and then executes according to the corresponding gear setting, which simplifies the entire judgment and execution work, reduces the system control's hardware requirements, and ensures the reliability and accuracy of the control program execution.

[0032] Specifically:

[0033] In the fast charging state, the liquid cooling gear is divided into three gears. When the maximum temperature of the single cell is ≥T11, it enters the first gear, sends a liquid cooling request, and requests power P1; when the maximum temperature of the single cell is ≥T12, it enters the second gear, sends a liquid cooling request, and requests power P2; when the maximum temperature of the single cell is ≥T13, it enters the third gear, sends a liquid cooling request, and requests power P3, among which T11>T12>T13, P1>P2>P3.

[0034] The control strategies for the discharge state and the slow charge state are the same. In the discharge and slow charge states, the liquid cooling gear is divided into three gears. When the maximum temperature of the monomer is ≥T111℃, the first gear is entered, a liquid cooling request is sent, and power P1 is requested; when the maximum temperature of the monomer is ≥T112, the second gear is entered, a liquid cooling request is sent, and power P2 is requested; when the maximum temperature of the monomer is ≥T113, the third gear is entered, a liquid cooling request is sent, and power P3 is requested; among them, T111>T112>T113, P1>P2>P3.

[0035] Regardless of whether it is in fast charging, discharging or slow charging state, when the water inlet temperature is lower than T20, it enters the real-time power calculation mode, which has the highest priority. If the coolant target temperature is set to T21, the power is: (T20-T21)*3281*1.073*0.2Kw. Among them, the calculation power is set to filter for 10 seconds, and the output power is switched after each change of the water inlet temperature for 10 seconds (the default for the first 10 seconds is the maximum power P3).

[0036] The gear can be raised but not lowered. When the maximum temperature of the single cell is less than T10 in the fast charging state, the liquid cooling state will be exited. When the maximum temperature of the single cell is less than T110 in the slow charging and discharging state, the liquid cooling state will be exited.

[0037] When the conditions do not meet the liquid cooling mode, but the temperature difference of the cells is ≥ T3, the temperature equalization mode is turned on. At this time, the requested power is 0 and only the water pump is turned on. When the temperature difference of the cells is less than (T3-1)℃, the temperature equalization mode is exited.

[0038] When the vehicle status changes (such as parking for charging becomes discharging for driving), the liquid cooling system synchronously switches the judgment threshold; the liquid cooling only works when the main negative relay is closed.

[0039] Disable the liquid cooling function in the smart charging state, that is, disable the liquid cooling function when a smart charging request is received.

[0040] The present invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A power battery liquid cooling control method, characterized in that: The corresponding control strategies are pre-set for different vehicle states. Each control strategy sets multiple cooling liquid gears according to the current maximum temperature of the single battery. Each cooling liquid gear is preset with a corresponding cooling liquid request power. When the system is working, it identifies the current vehicle status; Execute corresponding control strategy according to the current vehicle state; The current maximum temperature of the single battery is obtained in real time, and the cold liquid gear is executed according to the current maximum temperature of the single battery.

2. The power battery liquid cooling control method according to claim 1, characterized in that: The vehicle status includes: fast charging status, slow charging status and discharging status.

3. The power battery liquid cooling control method according to claim 2, characterized in that: In the fast charging state, when the maximum temperature of the monomer is ≥T11, the first gear is entered, a liquid cooling request is sent, and power P1 is requested; when the maximum temperature of the monomer is ≥T12, the second gear is entered, a liquid cooling request is sent, and power P2 is requested; when the maximum temperature of the monomer is ≥T13, the third gear is entered, a liquid cooling request is sent, and power P3 is requested, wherein T11>T12>T13, P1>P2>P3.

4. The power battery liquid cooling control method according to claim 2, characterized in that: In the slow charging state: when the maximum temperature of the monomer is ≥T111°C, the first gear is entered, a liquid cooling request is sent, and power P1 is requested; when the maximum temperature of the monomer is ≥T112, the second gear is entered, a liquid cooling request is sent, and power P2 is requested; when the maximum temperature of the monomer is ≥T113, the third gear is entered, a liquid cooling request is sent, and power P3 is requested, wherein T111>T112>T113, P1>P2>P3.

5. The power battery liquid cooling control method according to claim 2, characterized in that: In the discharge state: when the maximum temperature of the monomer is ≥T111°C, the first gear is entered, a liquid cooling request is sent, and power P1 is requested; when the maximum temperature of the monomer is ≥T112, the second gear is entered, a liquid cooling request is sent, and power P2 is requested; when the maximum temperature of the monomer is ≥T113, the third gear is entered, a liquid cooling request is sent, and power P3 is requested, wherein T111>T112>T113, P1>P2>P3.

6. The power battery liquid cooling control method according to any one of claims 2 to 5, characterized in that: When the system is working, the current water inlet of the cooling liquid is obtained in real time. When the water inlet temperature is lower than T20, the system enters the real-time power calculation mode. The real-time power calculation mode is the highest priority mode. The cooling liquid request power is obtained by multiplying the difference between the current cooling liquid target temperature T21 and T20 by the preset coefficient.

7. The power battery liquid cooling control method according to claim 6, characterized in that: In the real-time power calculation mode: Coolant required power = (T20-T21)*3281*1.073*0.2Kw; The calculated power is set to filter for 10 seconds, and the output power is switched after each change in the water inlet temperature lasts for 10 seconds.

8. The power battery liquid cooling control method according to claim 7, characterized in that: When the system is working, the gear is only allowed to rise. When the maximum temperature of the single cell is less than T10 in the fast charging state, the liquid cooling state is exited. When the maximum temperature of the single cell is less than T110 in the slow charging state and the discharging state, the liquid cooling state is exited.

9. The power battery liquid cooling control method according to claim 8, characterized in that: When the vehicle is in fast charging, slow charging or discharging state, and does not meet the liquid cooling mode, if the cell temperature difference is ≥ T3, the average temperature mode is turned on. The liquid cooling request power of the average temperature mode is 0, and only the water pump is turned on. When the cell temperature difference is less than the set value, the average temperature mode is exited.

10. A power battery liquid cooling control system, characterized in that: The BMS of the system is connected to the vehicle network and obtains the temperature of the power battery cells. The water inlet of the cooling liquid system is provided with a temperature sensor, the temperature sensor is connected to and outputs a temperature signal to the BMS, and the BMS is connected to and outputs a drive signal to the cooling system. The system executes the power battery liquid cooling control method as described in any one of claims 1-9.

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