Multi-battery pack system temperature control strategy

Abstract

The invention discloses a multi-battery pack system temperature control strategy, which belongs to the technical field of battery management, and comprises the following steps: step 1, carrying out thermal unbalance monitoring on each battery pack in a battery module, carrying out aging state temperature uniformity monitoring on the battery module, and judging whether the battery module is charged or not; 2, judging whether the battery module is in a flight operation state or not, performing thermal unbalance monitoring on each battery pack in the battery module, and performing aging state temperature uniformity monitoring on the battery module; 3, the temperature T3 of the battery module is collected, and whether the collected temperature T3 is smaller than or equal to 30 DEG C or not is judged; 4, judging whether the acquisition temperature T3 is greater than or equal to 34 DEG C; the method has the following technical effects that different heating and refrigerating control strategies are designed according to different movement working conditions, efficient battery module temperature control is achieved, and the electric quantity consumed by temperature control is reduced.

Description

Technical Field

[0001] The present invention relates to the field of battery management technology, and in particular to a temperature control strategy for a multi-battery pack system. Background Art

[0002] EVTOL aircraft (electric vertical take-off and landing aircraft) are powered by battery packs in new energy battery modules. During the charging and discharging process, the battery packs in the battery module will release a lot of heat, resulting in battery energy loss. Most of the current EVTOL aircraft (electric vertical take-off and landing aircraft) have battery packs in multiple battery modules. Under certain operating conditions, such as take-off, changing the direction of navigation, etc., some battery packs in some battery modules will operate, while some battery packs in other battery modules will not operate. In special cases, when a pack has thermal runaway, the battery packs in the battery module need to be specially treated. In summary, it is very necessary to design a set of thermal management tests to achieve temperature balance and control of the battery packs in multiple battery modules.

[0003] Currently, EVTOL aircraft cools and heats the battery system according to a set of thresholds, which greatly increases the power loss caused by battery module temperature control. The power used for battery module temperature control is also provided by the battery system. The increase in auxiliary power consumption will cause the power used for EVTOL aircraft flight to decrease, thereby reducing the flight distance and reducing the EVTOL aircraft user experience.

[0004] In view of the above situation, if the liquid flow rate allocated to the battery packs in each battery module is designed to be consistent, the battery packs in the battery module running at high power will be higher, and the battery packs in the battery module running at low power will be lower. This will further widen the temperature difference of the entire system, and the final result will be that the pressure difference of the battery packs in a certain battery module is too large, causing the battery packs in the battery module to need to be frequently replenished or even retired early. In addition, the existing multi-pack control strategy of EVTOL aircraft is that when the maximum temperature of the battery pack in the battery module is high, a command is sent to start the EVTOL aircraft for refrigeration; when the minimum temperature of the battery pack in the battery module is low, the BMS sends a command requiring the EVTOL aircraft to start heating. For the battery pack system in multiple battery modules, if the operating power of the battery packs in multiple battery modules is the same, there is no problem with this operation. However, under different flight conditions, the EVTOL aircraft will have 1. The battery pack in a battery module has a large operating power, and the battery pack in another battery module has a small operating power; 2. The battery pack in a battery module has thermal runaway.

[0005] In view of the above situation, extreme refrigeration will be used to reduce the temperature of the liquid in the system, and by reducing the temperature of the liquid, the battery pack in the thermal runaway battery module can be suppressed. However, the refrigeration equipment on the EVTOL aircraft equipment is limited, especially the general EVTOL aircraft uses natural cooling to dissipate heat instead of cooling by compressor refrigeration. The cooling rate of the coolant is limited, and the specific heat of the coolant is also large, which results in the battery pack in the thermal runaway battery module cannot be effectively suppressed, increasing the flight safety factor.

[0006] Based on this, the present invention designs a temperature control strategy for a multi-battery pack system to solve the above problems. Summary of the invention

[0007] In view of the above-mentioned shortcomings of the prior art, the present invention provides a temperature control strategy for a multi-battery pack system.

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions: A temperature control strategy for a multi-battery pack system: The following steps are involved: Step 1: Monitor the thermal imbalance of each battery pack in the battery module, monitor the aging status and temperature uniformity of the battery module, and determine whether the battery module is charged. If the judgment is no, execute step 2; if the judgment is yes, execute step 5; Step 2: Determine whether the battery module is in flight operation state. If it is not, the battery module is not temperature controlled. If it is yes, execute step 3 and simultaneously monitor thermal imbalance of each battery pack in the battery module and monitor the uniform temperature of the battery module under aging state; Step 3: Collect the battery module temperature T3, and determine whether the collected temperature T3 is ≤30°C. If it is determined to be yes, the battery module is not temperature-controlled. If it is determined to be no, execute step 4. At the same time, collect the discharge power of the battery packs in the battery module one by one, and determine whether the discharge power of battery pack A is ≤ the discharge power of any battery pack in other battery modules. If it is determined to be yes, the opening of the electric ball valve at battery pack A is 85%, and the opening of other electric ball valves is 100%. If it is determined to be no, the opening of the electric ball valve at battery pack A is 100%, and the opening of other electric ball valves is 90%. Step 4: Determine whether the collected temperature T3 is ≥ 34°C. If so, cool the battery module. If not, do not control the temperature of the battery module. Step 5: During charging, determine whether the battery module is in a fast charging state. If so, collect the battery module temperature T1 and execute step 6. If not, collect the battery module temperature T2 and execute step 7. At the same time, perform thermal imbalance monitoring on each battery pack in the battery module and perform temperature uniformity monitoring on the battery module in terms of aging state. Step 6: Determine the temperature T1, and heat, uncontrol the temperature, or cool the battery module according to the determination result; Step 7: Determine the temperature T2, and heat, uncontrollably treat, or cool the battery module based on the determination result.

[0009] Furthermore, the specific operations for thermal imbalance monitoring of the battery pack in the battery module are as follows: Step a: The BMS (battery management system) obtains the battery pack status in the battery module and determines whether there is a thermal runaway state. If the determination is no, the battery pack in the battery module is not temperature controlled. If the determination is yes, step b is executed. Step b: Set the opening of the electric ball valve corresponding to the battery pack in the battery module in thermal runaway state to 100%, the opening of the electric ball valve corresponding to the battery pack in the remaining battery modules that are not in thermal runaway state to 60%, the speed of the circulating water pump is 100%, and the fan is running.

[0010] Furthermore, the specific operations of aging state temperature uniformity monitoring are as follows: Step A: Collect the minimum temperature Tmin and the maximum temperature Tmax of the battery module, and determine whether Tmax-Tmin is ≤3°C. If it is not, execute step B. If it is yes, turn off the cooling circulation water pump and the fan. Step B: Determine whether Tmax-Tmin is ≥5℃. If so, the circulating water pump is turned on, the circulating water pump speed is 100%, and the fan is turned on. If not, the cooling circulating water pump is turned off and the fan is turned off.

[0011] Furthermore, the specific operations of step 6 are as follows: Step 611: determine whether the temperature T1 is less than 2°C, if so, execute step 612, if not, execute step 613; Step 612: determine whether the temperature T1 is ≤ 0°C, if so, perform heating treatment, if not, perform non-temperature control treatment on the battery module; Step 613: determine whether the temperature T1 is ≤ 34°C. If so, perform non-temperature control on the battery module. If not, execute step 614. Step 614: Determine whether the temperature T1 is ≤38°C. If so, perform non-temperature control on the battery module. If not, perform cooling.

[0012] Furthermore, the specific operations of step 7 are as follows: Step 711: determine whether the temperature T2 is less than 0°C, if so, execute step 714, if not, execute step 712; Step 712: determine whether the temperature T2 is ≤ 38°C. If so, perform non-temperature control on the battery module. If not, execute step 713. Step 713: Determine whether the temperature T2 is less than 42°C. If so, perform non-temperature control on the battery module. If not, perform cooling. Step 714: Determine whether the temperature T2 is ≤ -4°C. If so, heat the battery module. If not, perform non-temperature control on the battery module.

[0013] Furthermore, the specific operation of heating is: the PTC heater is turned on and the speed of the circulating water pump is 100%.

[0014] Furthermore, the specific operation of refrigeration is: the fan is turned on and the speed of the circulating water pump is 100%.

[0015] Furthermore, the specific operation of non-temperature control treatment is: the PTC heater is turned off, the circulating water pump speed runs at 0, and the fan is turned off.

[0016] The present invention has the following technical effects: the present invention designs different heating and cooling control strategies according to different motion conditions, realizes efficient battery module temperature control, reduces the power consumed by temperature control, and at the same time, effectively reduces the temperature difference of the battery module, prolongs the life of the battery system, and prolongs the flight distance of the aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 A block diagram of a temperature control strategy for a multi-battery pack system of the present invention; Figure 2 This is a block diagram of the temperature uniformity monitoring of the aging state of the present invention; Figure 3 A control system diagram of a temperature control strategy for a multi-battery pack system according to the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] The present invention will be further described below in conjunction with the embodiments.

[0021] Example 1: Please refer to Figure 1-Figure 2 , a temperature control strategy for a multi-battery pack system: The following steps are involved: Step 1: Monitor the thermal imbalance of each battery pack in the battery module, monitor the aging status and temperature uniformity of the battery module, and determine whether the battery module is charged. If the judgment is no, execute step 2; if the judgment is yes, execute step 5; The specific operations for thermal imbalance monitoring of the battery pack in the battery module are as follows: Step a: The BMS (battery management system) obtains the battery pack status in the battery module and determines whether there is a thermal runaway state. If the determination is no, the battery pack in the battery module is not temperature controlled. If the determination is yes, step b is executed. Step b: Set the opening of the electric ball valve corresponding to the battery pack in the battery module in thermal runaway state to 100%, the opening of the electric ball valve corresponding to the battery pack in the remaining battery modules that are not in thermal runaway state to 60%, the speed of the circulating water pump is 100%, and the fan is running.

[0022] The specific operations of aging state temperature uniformity monitoring are as follows: Step A: Collect the minimum temperature Tmin and the maximum temperature Tmax of the battery module, and determine whether Tmax-Tmin is ≤3°C. If it is not, execute step B. If it is yes, turn off the cooling circulation water pump and the fan. Step B: Determine whether Tmax-Tmin is ≥5°C. If so, the circulating water pump is turned on, the circulating water pump speed is 100%, and the fan is turned on. If not, the cooling circulating water pump is turned off, and the fan is turned off. Step 2: Determine whether the battery module is in flight operation state. If it is not, the battery module is not temperature controlled. If it is yes, execute step 3 and simultaneously monitor thermal imbalance of each battery pack in the battery module and monitor the uniform temperature of the battery module under aging state; Step 3: Collect the battery module temperature T3, and determine whether the collected temperature T3 is ≤30°C. If it is determined to be yes, the battery module is not temperature-controlled. If it is determined to be no, execute step 4. At the same time, collect the discharge power of the battery packs in the battery module one by one, and determine whether the discharge power of battery pack A is ≤ the discharge power of any battery pack in other battery modules. If it is determined to be yes, the opening of the electric ball valve at battery pack A is 85%, and the opening of other electric ball valves is 100%. If it is determined to be no, the opening of the electric ball valve at battery pack A is 100%, and the opening of other electric ball valves is 90%. Step 4: Determine whether the collected temperature T3 is ≥ 34°C. If so, cool the battery module. If not, do not control the temperature of the battery module. Step 5: During charging, determine whether the battery module is in a fast charging state. If so, collect the battery module temperature T1 and execute step 6. If not, collect the battery module temperature T2 and execute step 7. At the same time, perform thermal imbalance monitoring on each battery pack in the battery module and perform temperature uniformity monitoring on the battery module in terms of aging state. Step 6: Determine the temperature T1, and heat, uncontrol the temperature, or cool the battery module according to the determination result; Step 6: Step 611: determine whether the temperature T1 is less than 2°C, if so, execute step 612, if not, execute step 613; Step 612: determine whether the temperature T1 is ≤ 0°C, if so, perform heating treatment, if not, perform non-temperature control treatment on the battery module; Step 613: determine whether the temperature T1 is ≤ 34°C. If so, perform non-temperature control on the battery module. If not, execute step 614. Step 614: determine whether the temperature T1 is ≤ 38°C. If so, perform non-temperature control on the battery module. If not, perform cooling. Step 7: Determine the temperature T2, and heat, uncontrollably treat, or cool the battery module based on the determination result.

[0023] Step 7: Step 711: determine whether the temperature T2 is less than 0°C, if so, execute step 714, if not, execute step 712; Step 712: determine whether the temperature T2 is ≤ 38°C. If so, perform non-temperature control on the battery module. If not, execute step 713. Step 713: Determine whether the temperature T2 is less than 42°C. If so, perform non-temperature control on the battery module. If not, perform cooling. Step 714: Determine whether the temperature T2 is ≤ -4°C. If so, heat the battery module. If not, perform non-temperature control on the battery module.

[0024] The specific heating operation is: the PTC heater is turned on and the circulating water pump speed is 100%.

[0025] The specific operation of refrigeration is: the fan is turned on and the speed of the circulating water pump is 100%.

[0026] The specific operation of non-temperature control treatment is: the PTC heater is turned off, the circulating water pump speed runs at 0, and the fan is turned off.

[0027] To sum up, the specific control strategies are divided into: Battery heating control strategies in fast charging and slow charging states. Different start and shut-down thresholds are designed according to different heating strategies. Battery cooling control strategies for flight, fast charging, and slow charging states, as well as thermal runaway control strategies. Different startup and shutdown thresholds are designed based on different cooling strategies. Aging state temperature balance function control strategy, battery pack variable power state control strategy in the battery module; different temperature control strategies, design different start and shutdown thresholds; The present invention designs different heating and cooling control strategies according to different motion conditions to achieve efficient battery module temperature control and reduce the power consumed by temperature control. At the same time, it also effectively reduces the temperature difference of the battery module, prolongs the life of the battery system, and prolongs the flight distance of the aircraft.

[0028] Example 2: Please refer to Figure 3 A control system for a temperature control strategy of a multi-battery pack system, utilizing the temperature control strategy of the multi-battery pack system, including a PTC heater, a radiator, a fan, a circulating water pump, a plurality of electric ball valves, a plurality of cooling plates and a plurality of BMSs, wherein the plurality of BMSs are installed one-to-one with the battery packs in the battery module, the plurality of cooling plates are installed one-to-one with the battery packs in the battery module, the input end of the cooling plate is connected to the electric ball valve, the electric ball valves are connected to the output end of the circulating water pump through pipelines, the input end of the circulating water pump is connected to the output end of the radiator, the input end of the radiator is connected to the output end of the PTC heater, the input end of the PTC heater is connected to all the cooling plates through pipelines, and the fan is located on one side of the radiator.

[0029] A controllable electric ball valve is introduced. By adjusting the electric ball valve, the flow of the battery pack in the battery module can be controlled accordingly, thereby suppressing the out-of-control state of the battery pack in the thermal runaway battery module.

[0030] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A temperature control strategy for a multi-battery pack system, characterized in that: The following steps are involved: Step 1: Monitor the thermal imbalance of each battery pack in the battery module, monitor the aging status and temperature uniformity of the battery module, and determine whether the battery module is charged. If the judgment is no, execute step 2; if the judgment is yes, execute step 5; Step 2: Determine whether the battery module is in flight operation state. If it is not, the battery module is not temperature controlled. If it is yes, execute step 3 and simultaneously monitor thermal imbalance of each battery pack in the battery module and monitor the uniform temperature of the battery module under aging state; Step 3: Collect the battery module temperature T3, and determine whether the collected temperature T3 is ≤30°C. If it is determined to be yes, the battery module is not temperature-controlled. If it is determined to be no, execute step 4. At the same time, collect the discharge power of the battery packs in the battery module one by one, and determine whether the discharge power of battery pack A is ≤ the discharge power of any battery pack in other battery modules. If it is determined to be yes, the opening of the electric ball valve at battery pack A is 85%, and the opening of other electric ball valves is 100%. If it is determined to be no, the opening of the electric ball valve at battery pack A is 100%, and the opening of other electric ball valves is 90%. Step 4: Determine whether the collected temperature T3 is ≥ 34°C. If so, cool the battery module. If not, do not control the temperature of the battery module. Step 5: During charging, determine whether the battery module is in a fast charging state. If so, collect the battery module temperature T1 and execute step 6. If not, collect the battery module temperature T2 and execute step 7. At the same time, perform thermal imbalance monitoring on each battery pack in the battery module and perform temperature uniformity monitoring on the battery module in terms of aging state. Step 6: Determine the temperature T1, and heat, uncontrol the temperature, or cool the battery module according to the determination result; Step 7: Determine the temperature T2, and heat, uncontrollably treat, or cool the battery module based on the determination result.

2. The temperature control strategy of a multi-battery pack system according to claim 1, characterized in that: The specific operations for thermal imbalance monitoring of the battery pack in the battery module are as follows: Step a: The BMS obtains the status of the battery pack in the battery module and determines whether there is a thermal runaway state. If the judgment is no, the battery pack in the battery module is not temperature-controlled. If the judgment is yes, step b is executed; Step b: Set the opening of the electric ball valve corresponding to the battery pack in the battery module in thermal runaway state to 100%, the opening of the electric ball valve corresponding to the battery pack in the remaining battery modules that are not in thermal runaway state to 60%, the speed of the circulating water pump is 100%, and the fan is running.

3. The temperature control strategy of a multi-battery pack system according to claim 2, characterized in that: The specific operations of aging state temperature uniformity monitoring are as follows: Step A: Collect the minimum temperature Tmin and the maximum temperature Tmax of the battery module, and determine whether Tmax-Tmin is ≤3°C. If it is not, execute step B. If it is yes, turn off the cooling circulation water pump and the fan. Step B: Determine whether Tmax-Tmin is ≥5℃. If so, the circulating water pump is turned on, the circulating water pump speed is 100%, and the fan is turned on. If not, the cooling circulating water pump is turned off and the fan is turned off.

4. The temperature control strategy for a multi-battery pack system according to claim 3, characterized in that: Step 6: Step 611: determine whether the temperature T1 is less than 2°C, if so, execute step 612, if not, execute step 613; Step 612: determine whether the temperature T1 is ≤ 0°C, if so, perform heating treatment, if not, perform non-temperature control treatment on the battery module; Step 613: determine whether the temperature T1 is ≤ 34°C. If so, perform non-temperature control on the battery module. If not, execute step 614. Step 614: Determine whether the temperature T1 is ≤38°C. If so, perform non-temperature control on the battery module. If not, perform cooling.

5. The temperature control strategy for a multi-battery pack system according to claim 3, characterized in that: Step 7: Step 711: determine whether the temperature T2 is less than 0°C, if so, execute step 714, if not, execute step 712; Step 712: determine whether the temperature T2 is ≤ 38°C. If so, perform non-temperature control on the battery module. If not, execute step 713. Step 713: Determine whether the temperature T2 is less than 42°C. If so, perform non-temperature control on the battery module. If not, perform cooling. Step 714: Determine whether the temperature T2 is ≤ -4°C. If so, heat the battery module. If not, perform non-temperature control on the battery module.

6. The temperature control strategy for a multi-battery pack system according to any one of claims 4-5, characterized in that: The specific heating operation is: the PTC heater is turned on and the circulating water pump speed is 100%.

7. The temperature control strategy for a multi-battery pack system according to claim 6, characterized in that: The specific operation of refrigeration is: the fan is turned on and the speed of the circulating water pump is 100%.

8. The temperature control strategy for a multi-battery pack system according to claim 7, characterized in that: The specific operation of non-temperature control treatment is: the PTC heater is turned off, the circulating water pump speed runs at 0, and the fan is turned off.

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