A thermal management scheme and control strategy for electric aircraft batteries

Abstract

This invention relates to the field of battery thermal management technology and discloses a control strategy for an electric aircraft battery thermal management system. The thermal management system includes a control unit communicating with the battery pack BMS, a water chiller, a water pump, a four-way reversing valve 1, a motor heat exchanger, and a battery pack heat exchange module. It also includes a four-way reversing valve 2 and a ground-based PTC heating module. The control strategy is based on dual-parameter triggering of control actions using cell temperature and temperature rise rate, and simultaneously achieves integrated and coordinated control of battery cooling, motor heat dissipation, and low-temperature heating in conjunction with the operating conditions of the electric aircraft. It possesses advantages such as precise and proactive regulation of battery pack cell temperature, solving the problems of excessively rapid cell temperature rise and insufficient motor heat dissipation under high-power operating conditions.

Description

Technical Field

[0001] This invention relates to the field of battery thermal management technology, specifically to a thermal management scheme and control strategy for electric aircraft batteries. Background Technology

[0002] Electric aircraft, with their advantages of being environmentally friendly and low-noise, have become the development direction of the aviation field. Among them, multi-rotor VTOL electric aircraft are widely used in low-altitude operations and short-haul flights. However, the thermal management of their power systems has become a key factor restricting their performance and safety. As the core power source, the battery pack generates heat rapidly under high-rate discharge, fast charging, and high-power conditions such as VTOL, hovering, and landing. Traditional thermal management systems use only a single temperature threshold as the cooling trigger condition, which has the defect of delayed cooling response. This can easily lead to excessively rapid temperature rise of the battery cells and exceed the temperature limit, resulting in not only a decrease in battery discharge power and a shortened cycle life, but also serious flight safety hazards.

[0003] Meanwhile, during high-power flight of electric aircraft, air cooling alone is insufficient to meet the heat dissipation requirements of the motors, easily leading to overheating faults and affecting motor operational stability. In low-temperature environments, the discharge power of the battery cells drops significantly, failing to meet the power requirements of core operating conditions such as takeoff and flight. Traditional low-temperature heating methods often directly consume aircraft battery power, significantly shortening the effective flight time of electric aircraft. Furthermore, existing thermal management systems do not achieve synergistic thermal utilization of the battery and motor, employing simplistic cooling, heating, and heat dissipation strategies, resulting in low overall system energy efficiency and an inability to adapt to the diverse operating conditions of electric aircraft, whether on the ground / in the air or at high / conventional power levels.

[0004] Therefore, we propose a thermal management scheme and control strategy for electric aircraft batteries to solve the above problems. Summary of the Invention

[0005] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a thermal management scheme and control strategy for electric aircraft batteries, which has the advantages of precise and active temperature control of battery pack cells, and solves the problems of excessively rapid temperature rise of cells and insufficient heat dissipation of motors under high-power conditions.

[0006] (II) Technical Solution To achieve the aforementioned goal of precise and proactive temperature control of the battery pack cells, this invention provides the following technical solution: a control strategy for an electric aircraft battery thermal management system, wherein the thermal management system includes a control unit communicating with the battery pack BMS, a water chiller, a water pump, a four-way reversing valve 1, a motor heat exchanger, and a battery pack heat exchange module, and also includes a four-way reversing valve 2 and a ground PTC heating module; the control strategy is based on dual-parameter triggering control actions of cell temperature and temperature rise rate, and simultaneously combines the operating conditions of the electric aircraft to achieve integrated and coordinated control of battery cooling, motor heat dissipation, and low-temperature heating, specifically including: Active cooling control of the battery pack: When the average cell temperature is ≥25℃ and the temperature rise rate is ≥1℃ / min, or the average cell temperature is ≥30℃, the control unit controls the water chiller to start cooling; when the temperature rise rate is ≥1℃ / min and the cell temperature continues to rise, the water chiller lowers the battery pack coolant inlet temperature and the water pump increases the coolant flow rate; when the temperature rise rate is ≤0.5℃ / min or there is no temperature rise, the water chiller reduces the cooling capacity or stops cooling. Motor water cooling heat dissipation control: When the motor temperature is ≥100℃ and continues to rise, the control unit adjusts the four-way reversing valve 1 interface. If the water chiller has cooled the battery cells, the coolant after cooling the battery cells is delivered to the motor heat exchanger to dissipate heat from the motor. If the water chiller has not cooled the battery cells, the coolant circulates between the motor heat exchanger and the battery pack heat exchange module to dissipate heat from the motor. Ground low temperature heating control: When the battery cell temperature is lower than the first heating temperature in the ground state of the electric aircraft, the control unit adjusts the four-way reversing valve 2 interface to connect the ground PTC heating circuit, shuts down the water chiller, and the ground PTC heating module heats the coolant to heat the battery cell until the battery cell temperature is not lower than the first threshold temperature and then stops heating. Low-temperature heating control in the air: When the battery cell temperature is lower than the second heating temperature while the electric aircraft is in the air, the control unit adjusts the four-way reversing valve 1 interface to shut down the water chiller. The coolant circulates between the motor heat exchanger and the battery pack heat exchange module to absorb the motor waste heat to heat the battery cell. Heating stops when the battery cell temperature is not lower than the second threshold temperature.

[0007] Preferably, the battery pack heat exchange module is closely fitted with the battery cells of the No. 1 and No. 2 battery packs of the electric aircraft to achieve efficient heat exchange between the coolant and the battery cells.

[0008] Preferably, the water chiller is the core component of the system's refrigeration system, supports refrigeration power adjustment, and can be started / stopped and have its inlet coolant temperature adjusted according to the control unit's instructions.

[0009] Preferably, the water pump is a coolant circulation power component that supports flow regulation and can match the coolant flow requirements for cooling, heat dissipation, and heating conditions according to the control unit's instructions.

[0010] Preferably, the control unit communicates bidirectionally with the battery pack BMS in real time. The BMS collects the temperature data of individual battery cells, and the control unit calculates the average temperature and temperature rise rate of the battery cells based on the data.

[0011] Preferably, the motor cooling is based on air cooling, and water cooling is used as an auxiliary cooling method when air cooling is insufficient.

[0012] Preferably, the ground PTC heating module is an external heat source and does not consume the power of the electric aircraft battery pack during operation.

[0013] Preferably, the thermal management system uses a special aviation coolant with high thermal conductivity and low freezing point as the heat transfer medium.

[0014] Preferably, the electric aircraft is a multi-rotor electric aircraft, and more preferably a vertical take-off and landing multi-rotor electric aircraft.

[0015] An electric aircraft battery thermal management system includes a monitoring unit, a control unit, an execution unit, and a heat exchange unit. The monitoring unit includes a battery pack BMS and a temperature sensor. The execution unit includes a water chiller, a water pump, a four-way reversing valve 1, a four-way reversing valve 2, and a ground PTC heating module. The heat exchange unit includes a battery pack heat exchange module and a motor heat exchanger. The units work together to achieve coordinated thermal management of the battery and the motor.

[0016] (III) Beneficial Effects Compared with the prior art, the present invention provides a thermal management scheme and control strategy for electric aircraft batteries, which has the following beneficial effects: 1. This invention adopts an active cooling strategy triggered by two parameters: cell temperature and temperature rise rate. It identifies the cell temperature rise trend in advance and starts cooling before the cell temperature reaches the limit value. This completely solves the problem of cooling lag in traditional systems and effectively avoids the cell temperature from rising too quickly or too high under high power conditions, thus greatly improving the safety of battery use. 2. This invention dynamically adjusts the cooling capacity according to the cell temperature rise rate, achieving a precise match between the cooling capacity and the heat generated by the cell. When the temperature rise rate drops, the cooling is reduced or stopped, which significantly reduces the consumption of battery power by the thermal management system and effectively increases the effective flight time of the electric aircraft. 3. This invention adopts a hybrid cooling mode of water cooling + air cooling for the motor, and uses the battery thermal management system to achieve auxiliary liquid cooling of the motor, which solves the problem of insufficient air cooling heat dissipation of the motor during high-power flight, improves the motor's operational stability, and avoids motor high-temperature failure. 4. This invention designs a ground / air-based differentiated low-temperature heating strategy. On the ground, an external PTC heat source is used to preheat the battery cells without consuming the aircraft battery power. In the air, waste heat from the motor is used to heat the battery cells, achieving heat recycling without the need for an additional heat source. This ensures that the battery cells reach their rated discharge power at low temperatures, meeting the power requirements under all operating conditions, and also conforms to the energy-saving concept of electric aviation. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the heat exchange thermal management system for the battery pack water-cooled machine on an electric aircraft according to the present invention. Figure 2 This is a schematic diagram of the heat exchange management system for the battery pack and motor on an electric aircraft according to the present invention. Figure 3 This is a schematic diagram of the ground heating thermal management system for the battery pack on the electric aircraft of the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] The electric aircraft battery thermal management system of the present invention is a fully automatic intelligent control system. The overall workflow follows the logic of data acquisition, parameter calculation, threshold judgment, action execution, operating condition feedback, and mode switching, without human intervention. The specific implementation methods for each operating condition are described in detail below with reference to the accompanying drawings: Example 1: Active cooling mode of battery pack (with appendix) Figure 1 ) When the electric aircraft is in high-power conditions such as fast charging, vertical takeoff, and hovering, the battery pack BMS of the monitoring unit collects the cell temperature and discharge power data of battery #1 and battery #2 in real time and transmits the data to the control unit. Based on the collected data, the control unit calculates that when the average cell temperature is ≥25℃ and the temperature rise rate is ≥1℃ / min, or when the average cell temperature is ≥30℃, it immediately issues a control command: the four-way reversing valve 1 and the four-way reversing valve 2 maintain their initial interface state, the water chiller is turned on, and the water pump operates at normal or high flow rate according to the cell temperature rise rate.

[0020] Specialized aviation coolant, after being cooled by a water chiller, is pumped to the heat exchange modules of the battery packs for batteries #1 and #2, where it exchanges heat efficiently with the cells to achieve cell cooling. The cooled coolant then flows back to the water chiller for recooling, forming a closed-loop refrigeration circuit. When the control unit detects a cell temperature rise rate ≤0.5℃ / min or no temperature rise, it immediately instructs the water chiller to reduce its cooling power or stop cooling, while simultaneously adjusting the water pump flow rate to normal levels to reduce battery power consumption. In this embodiment, dual-parameter triggering and dynamic adjustment of cooling capacity ensure that the cell temperature does not exceed the safety limit of 55℃.

[0021] Example 2: Motor-assisted heat dissipation operation (with appendix) Figure 2 ) When the electric aircraft is flying at high power, the temperature sensor of the motor winding collects the motor temperature in real time and transmits the data to the control unit. When the control unit detects that the motor temperature is ≥100℃ and the temperature continues to rise, it determines that the air cooling is insufficient and immediately issues a control command: adjust the four-way reversing valve 1 to the battery pack-motor heat exchanger connection interface, and keep the four-way reversing valve 2 in its initial state.

[0022] If the water chiller is already operating to cool the battery pack, the low-temperature coolant after cooling batteries #1 and #2 is delivered to the motor heat exchanger via the four-way reversing valve 1, where it exchanges heat with the high-temperature motor to achieve liquid cooling. The cooled coolant then flows back to the water chiller for recooling. If the water chiller is not operating, a water pump drives the coolant to circulate between the motor heat exchanger and the heat exchange modules of batteries #1 and #2, utilizing the heat capacity of the battery pack to disperse the heat generated by the motor, achieving energy-free heat dissipation. In this embodiment, water cooling quickly reduces the motor temperature to a safe range, improving the motor's operational stability.

[0023] Example 3: Ground Low-Temperature Heating Condition (with appendix) Figure 3 ) When the electric aircraft is in standby mode on the ground, if the battery pack BMS detects that the average temperature of the cells of battery #1 and battery #2 is less than 10°C, the control unit determines that the cell discharge power cannot meet the takeoff requirements and immediately issues a control command: adjust the four-way reversing valve 2 to the ground PTC heating circuit connection interface, keep the four-way reversing valve 1 in its initial state, start the ground PTC, and at the same time shut down the water chiller to prevent the cooling function from offsetting the heating effect.

[0024] The ground-based PTC heats the dedicated aviation coolant within the system. A water pump then delivers the heated, high-temperature coolant to the heat exchange modules of batteries #1 and #2, where it exchanges heat with the low-temperature cells, preheating them. When the battery pack BMS detects an average cell temperature ≥10°C, the control unit immediately shuts off the ground-based PTC, the four-way reversing valve 2 resets to its initial state, disconnecting the ground heating circuit, and the system enters pre-flight thermal management standby mode. In this embodiment, the ground-based PTC serves as an external heat source and does not consume any power from the electric aircraft battery pack, ensuring sufficient battery power before takeoff.

[0025] Example 4: Low-Temperature Heating in Air (with appendix) Figure 2 ) When the electric aircraft is in flight, if the battery pack BMS detects that the average temperature of the cells of battery #1 and battery #2 is less than 15°C, the control unit determines that there is a risk of insufficient cell discharge power and immediately issues a control command: adjust the four-way reversing valve 1 to the battery pack-motor heat exchanger connection interface, shut down the water chiller, and keep the four-way reversing valve 2 in its initial state.

[0026] A water pump drives specialized aviation coolant to circulate between the motor heat exchanger and the heat exchange modules of batteries #1 and #2. At the motor heat exchanger, the coolant absorbs waste heat generated by the motor's operation, forming a high-temperature coolant. This high-temperature coolant then enters the battery pack heat exchange module, exchanging heat with the low-temperature battery cells to raise their temperature. When the battery pack BMS detects an average cell temperature ≥15°C, the control unit immediately instructs the four-way reversing valve 1 to reset to its initial state, restoring the coolant to its normal circulation path and stopping the collection and utilization of motor waste heat. In this embodiment, the motor waste heat is used to heat the battery cells, achieving heat recycling without requiring additional electrical energy consumption, thus improving the overall energy efficiency of the system.

[0027] Example 5: Implementation of Multi-condition Switching Throughout the entire process of an electric aircraft taking off from the ground and flying in the air, the thermal management system of this invention can achieve seamless switching between multiple operating conditions: On the ground, if the cell temperature is <10℃ (first heating temperature), the system automatically activates the ground low-temperature heating condition of Example 3, stopping heating and entering standby mode once the cell temperature reaches ≥10℃ (first threshold temperature); during takeoff (vertical takeoff), the cell generates heat through high-rate discharge, and the system immediately activates the battery pack active cooling condition of Example 1 to suppress cell temperature rise; during high-power flight, if the motor temperature reaches ≥100℃ and continues to rise, the system simultaneously activates the motor-assisted heat dissipation condition of Example 2; if the cell temperature drops to <15℃ (second heating temperature) during flight, the system automatically switches to the low-temperature heating condition of Example 4, switching back to normal operating conditions once the cell temperature recovers. Throughout the entire process, the control unit monitors data in real time and automatically adjusts the control strategy according to changes in operating conditions to ensure that the battery and motor are always within the optimal operating temperature range.

[0028] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A control strategy for a thermal management system for an electric aircraft battery, characterized in that, The thermal management system includes a control unit communicating with the battery pack BMS, a water chiller, a water pump, a four-way reversing valve 1, a motor heat exchanger, and a battery pack heat exchange module. It also includes a four-way reversing valve 2 and a ground-based PTC heating module. The control strategy is based on dual-parameter triggering of cell temperature and temperature rise rate, and simultaneously integrates battery cooling, motor heat dissipation, and low-temperature heating under the operating conditions of the electric aircraft to achieve unified and coordinated control. Specifically, it includes: Active cooling control of the battery pack: When the average cell temperature is ≥25℃ and the temperature rise rate is ≥1℃ / min, or the average cell temperature is ≥30℃, the control unit controls the water chiller to start cooling; when the temperature rise rate is ≥1℃ / min and the cell temperature continues to rise, the water chiller lowers the battery pack coolant inlet temperature and the water pump increases the coolant flow rate; when the temperature rise rate is ≤0.5℃ / min or there is no temperature rise, the water chiller reduces the cooling capacity or stops cooling. Motor water cooling heat dissipation control: When the motor temperature is ≥100℃ and continues to rise, the control unit adjusts the four-way reversing valve 1 interface. If the water chiller has cooled the battery cells, the coolant after cooling the battery cells is delivered to the motor heat exchanger to dissipate heat from the motor. If the water chiller has not cooled the battery cells, the coolant circulates between the motor heat exchanger and the battery pack heat exchange module to dissipate heat from the motor. Ground low temperature heating control: When the battery cell temperature is lower than the first heating temperature in the ground state of the electric aircraft, the control unit adjusts the four-way reversing valve 2 interface to connect the ground PTC heating circuit, shuts down the water chiller, and the ground PTC heating module heats the coolant to heat the battery cell until the battery cell temperature is not lower than the first threshold temperature and then stops heating. Low-temperature heating control in the air: When the battery cell temperature is lower than the second heating temperature while the electric aircraft is in the air, the control unit adjusts the four-way reversing valve 1 interface to shut down the water chiller. The coolant circulates between the motor heat exchanger and the battery pack heat exchange module to absorb the motor waste heat to heat the battery cell. Heating stops when the battery cell temperature is not lower than the second threshold temperature.

2. The control strategy according to claim 1, characterized in that, The battery pack heat exchange module is closely fitted with the battery cells of the No. 1 and No. 2 battery packs of the electric aircraft, realizing efficient heat exchange between the coolant and the battery cells.

3. The control strategy according to claim 1, characterized in that, The water chiller is the core component of the system's refrigeration system. It supports refrigeration power adjustment and can be started, stopped, and have its inlet coolant temperature adjusted according to the control unit's instructions.

4. The control strategy according to claim 1, characterized in that, The water pump is a coolant circulation power component that supports flow regulation and can match the coolant flow requirements for cooling, heat dissipation, and heating conditions according to the control unit's instructions.

5. The control strategy according to claim 1, characterized in that, The control unit communicates bidirectionally with the battery pack BMS in real time. The BMS collects the temperature data of individual battery cells, and the control unit calculates the average temperature and temperature rise rate of the cells based on the data.

6. The control strategy according to claim 1, characterized in that, The motor cooling is based on air cooling, with water cooling as an auxiliary cooling method when air cooling is insufficient.

7. The control strategy according to claim 1, characterized in that, The ground-based PTC heating module is an external heat source and does not consume the power of the electric aircraft's battery pack during operation.

8. The control strategy according to claim 1, characterized in that, The thermal management system uses a special aviation coolant with high thermal conductivity and low freezing point as the heat transfer medium.

9. The control strategy according to any one of claims 1-8, characterized in that, The electric aircraft is a multi-rotor electric aircraft, and preferably a vertical take-off and landing multi-rotor electric aircraft.

10. A thermal management system for an electric aircraft battery, characterized in that, The control strategy described in any one of claims 1-9 includes a monitoring unit, a control unit, an execution unit, and a heat exchange unit. The monitoring unit includes a battery pack BMS and a temperature sensor. The execution unit includes a water chiller, a water pump, a four-way reversing valve 1, a four-way reversing valve 2, and a ground PTC heating module. The heat exchange unit includes a battery pack heat exchange module and a motor heat exchanger. The units work together to achieve coordinated thermal management of the battery and the motor.

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