Pulse flow enhanced heat exchange battery thermal management system

Abstract

The invention discloses a pulse flow enhanced heat exchange battery thermal management system which comprises a cold plate, a circulating pump and a pulse control module, the cold plate is used for being in contact with a battery; the cold plate is provided with a flow channel, the flow channel is communicated with the circulating pump through a circulating pipeline, and the circulating pump is used for pumping cooling liquid into the cold plate; and the pulse control module is used for periodically controlling the circulating pump, so that the flow velocity of the cooling liquid is periodically changed in the flow channel. An unsteady flow field is generated through periodic flow velocity change, a thermal boundary layer is effectively destroyed, and the fluid heat exchange capacity is remarkably improved. The pulse flow induces the vortex structure to enhance fluid mixing and reduce the battery temperature difference, and under the condition of the same average flow, the pulse flow can obtain a better cooling effect and reduce the pump power consumption.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power battery thermal management, and particularly relates to a pulse flow enhanced heat exchange battery thermal management system. BACKGROUND

[0002] With the rapid development of new energy vehicles and energy storage systems, the energy density of lithium ion batteries is continuously improved, and the temperature rise rate and thermal runaway risk are significantly increased. A reasonable and effective thermal management system is the key to ensuring the performance and service life of the battery.

[0003] The existing battery liquid cooling thermal management system generally adopts continuous stable flow (steady flow) mode, and the heat exchange enhancement capacity is limited. Some studies introduce a single parameter pulse flow (such as fixed duty cycle and fixed period), but its dynamic response is single, and it is difficult to adapt to the thermal load changes of the battery under different working conditions. For example, the heat generation is low at the initial stage of discharging, but the heat generation increases significantly in the middle and late stages. The single pulse strategy cannot meet the needs of energy saving at the early stage and heat dissipation enhancement at the late stage. In addition, the existing control strategy is generally "fixed strategy", which cannot be segmented and controlled according to the running stage, limiting the potential efficiency of pulse flow in complex and tortuous flow channels or heat exchange enhancement structures.

[0004] Therefore, there is an urgent need for a control method that can dynamically switch pulse parameters at different time periods to achieve higher heat exchange efficiency, lower pump power consumption, and better temperature uniformity. SUMMARY

[0005] The present application aims to overcome the shortcomings of the prior art and provide a combined pulse flow control system based on a phase change material coupled cold plate to solve the problems of single flow and uneven heat exchange in the existing liquid cooling system, and to achieve efficient temperature uniformity and energy consumption optimization of the thermal management.

[0006] To achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0007] A pulse flow enhanced heat exchange battery thermal management system, comprising a cold plate, a circulating pump, and a pulse control module.

[0008] The cold plate is used to contact the battery. The cold plate is provided with a flow channel, and the flow channel is connected to the circulating pump through a circulating pipeline. The circulating pump is used to pump the coolant into the cold plate. The pulse control module is used to periodically control the circulating pump to form a periodically changing flow rate of the coolant in the flow channel.

[0009] Optionally, the pulse control module is provided with a single pulse control strategy. The pulse period is any value in the range of 1-300s, and the duty cycle is any value in the range of 0-1. When the duty cycle is 0, the motor of the circulating pump stops rotating. When the duty cycle is 1, the motor of the circulating pump reaches the maximum speed under the input voltage.

[0010] Optionally, the pulse flow enhanced heat exchange battery thermal management system further comprises a temperature sensor for collecting the temperature of the battery and the surface of the cold plate and feeding back to the pulse control module, when the temperature monitored by the temperature sensor exceeds the set target temperature or the maximum temperature difference exceeds the target maximum temperature difference, the pulse control module adjusts the pulse period and duty cycle so that the temperature of the battery and the surface of the cold plate or the maximum temperature difference is lower than the set target temperature or target maximum temperature difference.

[0011] Optionally, the pulse control module is further provided with a segmented combined pulse control strategy, comprising the following steps:

[0012] Divide a running period of the battery into at least two stages with a set temperature node or a time node; set the pulse period and duty cycle for each stage respectively;

[0013] Control the circulating pump to output flow pulses according to the pulse period and duty cycle, so that the liquid cooling fluid is periodically started and stopped or periodically flow-modulated in pulses in the stage;

[0014] Switch the corresponding pulse control parameters in sequence according to the stage order in the running period.

[0015] Optionally, the number of stages and the division of stages are set according to the real-time temperature change during the battery operation or according to the battery operation time, and the pulse period and duty cycle are dynamically adjusted according to the battery temperature feedback.

[0016] Optionally, the cold plate is further provided with a phase change material, and the phase change material cavity is filled with a phase change material.

[0017] Optionally, the battery is composed of a plurality of lithium batteries, and the thickness direction of all the lithium batteries is perpendicular to the horizontal plane; the cold plate contacts the left and right surfaces of the lithium battery, and the front and rear surfaces of the lithium battery are mutually adhered.

[0018] Optionally, the pulse flow enhanced heat exchange battery thermal management system further comprises an incubator, and the cold plate and the battery are placed in the incubator.

[0019] Optionally, a constant temperature water tank is arranged in the circulating pipeline.

[0020] Optionally, the cold plate is provided with not less than two independent flow channels, and the flow directions in different flow channels are opposite or switched to opposite directions according to the valve.

[0021] Compared with the prior art, the present application has the following advantages:

[0022] 1. Enhanced heat transfer performance: Non-steady flow field is generated by periodic flow rate variation, effectively destroying thermal boundary layer and significantly improving fluid heat transfer capacity.

[0023] 2. Improved temperature uniformity: Pulsed flow induces vortex structure to enhance fluid mixing and reduce battery pack temperature difference.

[0024] 3. Reduced energy consumption: Under the same average flow conditions, pulsed flow can achieve better cooling effect and reduce pump power consumption.

[0025] 4. High control flexibility: Different frequencies, duty cycles and flow rate amplitudes can be adjusted through programmable pulse control module to adapt to various operating conditions.

[0026] 5. Strong compatibility: The system can be directly applied to existing phase change material composite liquid cooling plate structure without complex modification, with strong engineering practicability.

[0027] 6. Low cost: The system can be directly applied to the external control end of the conventional liquid cooling system pump, with very low hardware cost. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The pulse flow enhanced heat transfer battery thermal management system provided by the embodiment of the present application is shown in the composition schematic diagram.

[0029] Figure 2 It is a cross-sectional view of the cold plate.

[0030] Figure 3 It is a combined pulse segmented control strategy based on temperature base node schematic diagram.

[0031] Figure 4 It is a combined pulse segmented control strategy based on s time base node schematic diagram.

[0032] In the figure: 1, phase change material liquid cooling plate; 11, phase change material cavity; 12, liquid cooling channel; 2, charge and discharge box; 3, pulse control module; 31, computer; 32, data acquisition instrument; 33, single-chip microcomputer; 4, circulating pump; 5, constant temperature cooling liquid tank; 6, constant temperature oven. DETAILED DESCRIPTION

[0033] Embodiment:

[0034] The technical solutions of the present application will be further described below in combination with the drawings and embodiments.

[0035] Referring to Figure 1 the embodiment provided by the present application, the pulse flow enhanced heat transfer battery thermal management system mainly includes a cold plate, a circulating pump and a pulse control module.

[0036] The cold plate is used in contact with the battery to form a cold plate and battery module. When charging, the battery is connected to the charge-discharge box 2 to charge the battery. The cold plate is provided with a flow channel connected to a circulating pump through a circulating pipeline. The circulating pump is used to pump the coolant into the cold plate. The pulse control module is used to periodically control the circulating pump to form a periodically changing flow rate of the coolant in the flow channel.

[0037] In this way, the non-steady flow field is generated by the periodic flow rate change, effectively breaking the thermal boundary layer and significantly improving the fluid heat exchange capacity. The pulse flow induces vortex structure to enhance fluid mixing and reduce battery temperature difference. Under the same average flow condition, pulse flow can obtain better cooling effect and reduce pump power consumption.

[0038] In a specific embodiment, the circulating pump is a variable speed pump supporting PWM or analog voltage input, that is, the coolant flow rate is realized by PWM (Pulse Width Modulation, PWM). PWM is a technology for controlling analog circuits by changing the width of pulses. The motor speed can be adjusted by adjusting the duty cycle of high and low level signals. The pulse control module is programmed and burned by corresponding software and hardware to customize the pulse flow control strategy. For example, the pulse control module can set a single pulse control strategy with a pulse period of 1-300s and a duty cycle of 0-1. When the duty cycle is 0, the motor of the circulating pump stops rotating. When the duty cycle is 1, the circulating pump motor reaches the maximum speed under the input voltage.

[0039] In a preferred embodiment, the pulse flow enhanced heat transfer battery thermal management system further comprises a temperature sensor for collecting the temperature of the battery and the surface of the cold plate and feeding back to the pulse control module. When the temperature monitored by the temperature sensor exceeds the set target temperature, or the maximum temperature difference exceeds the target maximum temperature difference, the pulse control module adjusts the pulse period and duty cycle to make the battery and cold plate surface temperature or maximum temperature difference lower than the set target temperature or target maximum temperature difference, thereby ensuring the safety of the battery. Therefore, the pulse control module is also provided with a segmented combined pulse control strategy, including the following steps:

[0040] (1) Divide a battery operating cycle into at least two stages based on a set temperature node or a time node. Set the pulse period and duty cycle for each stage respectively. The number of stages and the division of stages are set according to the real-time temperature change during battery operation or according to the battery operation time. The pulse period and duty cycle are dynamically adjusted according to the battery temperature feedback.

[0041] (2) Control the circulating pump to output flow pulses according to the pulse period and duty cycle, so that the liquid cooling fluid is periodically started and stopped or periodically flow modulated pulse flow within the stage;

[0042] (3) During the operation cycle, the corresponding pulse control parameters are switched sequentially according to the stage sequence.

[0043] In one specific embodiment, such as Figure 2 As shown, in addition to the flow channel 12, the cold plate also has a phase change material cavity 11, which is filled with phase change material to provide heat buffering. Since coolant flows in the flow channel 12, it can exchange heat with the battery and restore the latent heat of the phase change material. Thus, by setting up the cold plate, under the combined action of the phase change material and the flow channel, heat is absorbed when the battery is charged and discharged, preventing local overheating and greatly improving the safety and cycle life of the battery. In addition, a constant temperature coolant tank is also set in the circulation pipeline connected to the flow channel and the circulation pump. In this way, the coolant will enter the constant temperature coolant tank after exiting the cold plate and then enter the cold plate again through the circulation pump, thereby realizing the circulation of coolant.

[0044] In one specific embodiment, the flow channel 12 has at least two independent flow channels, with the liquid flow direction in different channels or switched to opposite directions according to a valve, thereby further enhancing the cooling effect of the cold plate on the battery. The flow channel 12 is serpentine to further ensure the cooling effect of the cold plate on the battery. The coolant is water to reduce usage costs.

[0045] In one specific embodiment, the battery is composed of several lithium batteries, all of which are perpendicular to the horizontal plane in the thickness direction, i.e., the batteries are arranged in a horizontally stacked manner; the cold plate is in contact with the left and right sides of the lithium batteries, and the front and back of the lithium batteries are in close contact with each other, which is beneficial to improving the space utilization of the thermal management system.

[0046] In a preferred embodiment, the battery thermal management device based on phase change material coupled liquid cooling further includes a constant temperature chamber 6, in which the cold plate and the battery are placed to ensure that the battery is within a safe temperature range. Furthermore, a temperature sensor is installed within the constant temperature chamber 6 to monitor the temperature of the cold plate and the battery.

[0047] In one specific embodiment, the pulse control module 3 includes a computer 31, a data acquisition device 32, and a microcontroller 33. The data acquisition device 31 is connected to a temperature sensor to collect the monitoring results of the temperature sensor and transmit the collected monitoring results to the computer 31. The computer 31 then sends pulse control commands to the microcontroller 33, which controls the operation of the circulating pump motor.

[0048] The combined pulse flow control system provided in this embodiment will be further verified and explained below with application scenario examples:

[0049] Take the STM32F03C8T6 single-chip as an example, and the K-type thermocouple (i.e. temperature acquisition unit) as an example for temperature data acquisition, both of which are connected to the computer. When the temperature monitored by the temperature sensor does not compare with the set threshold temperature, the system only outputs a single pulse parameter pulse flow, i.e. the pulse duty cycle and period remain unchanged during operation, which is the most basic control method. When the temperature monitored by the temperature sensor compares with the set threshold temperature, there are several control strategies as follows:

[0050] Combined pulse segmentation control strategy based on temperature node:

[0051] As shown in Figure 3 , in this embodiment, the pulse control module presets the highest temperature T lim allowed for battery operation as 40℃, the maximum temperature difference ΔT lim as 5℃, and sets two temperature threshold values T1 and T2 (T1 = 34℃, T2 = 37℃) for stage switching. During system operation, the pulse control module acquires the highest temperature T max of the battery and the maximum temperature difference ΔT in real time, and adjusts the pulse period and duty cycle accordingly to form a segmented combined pulse strategy.

[0052] In the initial stage of battery operation, if T max is detected to be lower than T1 and ΔT is within the allowed range, the system enters the energy-saving pulse stage in the low-temperature zone. In this stage, the circulating pump operates with a longer period T p = 80–200 s and a lower duty cycle D = 0.1–0.3, utilizes lower flow frequency to maintain basic heat exchange capacity, and relies on the heat storage characteristics of the phase change material to maintain the battery temperature stable, to achieve the saving of pump power.

[0053] When T max reaches T1 and ΔT is within the allowed range, the system automatically switches to the transition enhancement stage in the medium-temperature zone. In this stage, the pulse control module adjusts the pulse period to a medium range T p = 20–80 s, and increases the duty cycle to D = 0.3–0.7. The fluid can produce stronger periodic velocity changes under this parameter, promoting the recovery of latent heat of the phase change material and the temperature uniformization of the battery module, adapting to the cooling demand under medium heat load conditions.

[0054] When T max further rises above T2, or ΔT exceeds ΔT lim , the system enters the enhanced pulse stage in the high-temperature zone. In this stage, the pulse period will be shortened to T p= 5–20 s, duty cycle increases to D = 0.7–1 to form a high-frequency, high-flow-rate amplitude pulsed flow. The strong disturbance of this stage can significantly destroy the thermal boundary layer inside the cold plate, inducing the continuous formation of secondary flow structures, thereby rapidly reducing the battery temperature and suppressing the temperature difference from expanding. When T max or ΔT drops to a low one-level interval, the system automatically returns to the corresponding energy-saving or transition stage, achieving a dynamic balance between cooling capacity and energy consumption.

[0055] Combined pulse segmentation control strategy based on s time base node:

[0056] As shown in Figure 4 , the pulse parameters are segmented and set based on the time process of the battery discharge cycle to adapt to the gradually increasing thermal load characteristics presented by the battery at different time stages. Under this strategy, the pulse control module divides a complete running cycle of the battery into several time periods in advance, and sets the pulse period and duty cycle for each time period, thereby achieving dynamic matching between cooling capacity and energy consumption.

[0057] Taking a 20 min 3C discharge cycle as an example, the system divides the running process into an initial stage, a middle stage, and a late stage in turn. In the initial stage of 0–8 min, since the battery heat generation is low, the circulating pump uses a longer pulse period T p = 80–200 s and a lower duty cycle D = 0.1–0.3 to maintain basic cooling capacity while reducing pump power consumption, and uses the heat storage capacity of the phase change material to stabilize the battery temperature. When running to 8–14 min, the battery thermal load increases, entering the discharge middle stage, the pulse period is adjusted to T p = 20–80 s, and the duty cycle is increased to D = 0.3–0.7 to enhance the flow field disturbance and the recovery speed of the latent heat of the phase change material, so that the heat exchange capacity adapts to the medium-intensity heat accumulation. In the 14–20 min late stage of charging and discharging, the battery is in a high heat flux interval, and the system switches to intensive cooling, with the pulse period further shortened to T p = 5–20 s, and the duty cycle is increased to D = 0.7–1; the high-frequency, high-duty cycle pulsed flow can significantly enhance the velocity gradient and secondary flow structure inside the cold plate, thereby quickly removing high-intensity heat and suppressing the temperature from continuing to rise.

[0058] Through the above temperature-based node or time-based node trigger control strategy, the system can adaptively adjust the pulse period and duty cycle according to the real-time thermal load, achieving continuous coverage from low thermal load to high heat flux working conditions; while ensuring T maxThe control method can significantly reduce the pump energy consumption while the ΔT does not exceed the set upper limit. The control method does not need to change the cold plate structure, can be directly applied to the existing phase change material composite liquid cooling system, and has high engineering feasibility and practical value.

[0059] The above examples are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and to implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the essence of the present application should be covered within the protection scope of the present application.

Claims

1. A pulse flow enhanced heat exchange battery thermal management system, characterized in that, Includes cold plate, circulating pump, and pulse control module; The cold plate is used to contact the battery; the cold plate is provided with a flow channel, which is connected to the circulation pump through a circulation pipeline, and the circulation pump is used to pump coolant into the cold plate; the pulse control module is used to periodically control the circulation pump so that the coolant forms a periodically changing flow rate in the flow channel.

2. The pulse flow enhanced heat exchange battery thermal management system as described in claim 1, characterized in that, The pulse control module is set to a single pulse control strategy. The pulse period is any value within the range of 1–300s, and the duty cycle is any value within the range of 0–1. When the duty cycle is 0, the motor of the circulating pump stops rotating. When the duty cycle is 1, the motor of the circulating pump reaches the maximum speed under the input voltage.

3. The pulse flow enhanced heat exchange battery thermal management system as described in claim 2, characterized in that, It also includes a temperature sensor, which is used to collect the surface temperature of the battery and the cold plate and feed it back to the pulse control module. When the temperature monitored by the temperature sensor exceeds the set target temperature, or the maximum temperature difference exceeds the target maximum temperature difference, the pulse control module adjusts the pulse period and duty cycle so that the surface temperature of the battery and the cold plate or the maximum temperature difference is lower than the set target temperature or the target maximum temperature difference.

4. The pulse flow enhanced heat exchange battery thermal management system as described in any one of claims 1-3, characterized in that, The pulse control module is also equipped with a segmented combined pulse control strategy, including the following steps: By setting a temperature base node or a time base node, a battery operating cycle is divided into at least two stages; each stage has a set pulse period and duty cycle. The circulating pump is controlled to output flow pulses according to the pulse period and duty cycle, so that the liquid cooling fluid exhibits periodic start-stop or periodic flow modulation pulse flow within the stage. During the operating cycle, the corresponding pulse control parameters are switched sequentially according to the stage sequence.

5. The pulse flow enhanced heat exchange battery thermal management system as described in claim 4, characterized in that, The number of stages and the basis for dividing the stages are set according to the real-time temperature changes during battery operation or according to the battery operation time, and the pulse period and duty cycle are dynamically adjusted according to the battery temperature feedback.

6. The pulse flow enhanced heat exchange battery thermal management system as described in claim 1, characterized in that, The cold plate is also provided with a phase change material, and the cavity of the phase change material is filled with the phase change material.

7. The pulse flow enhanced heat exchange battery thermal management system as described in claim 1 or 6, characterized in that, The battery is composed of several lithium batteries, all of which have their thickness direction perpendicular to the horizontal plane; the cold plate is in contact with the left and right sides of the lithium batteries, and the front and back sides of the lithium batteries are attached to each other.

8. The pulse flow enhanced heat exchange battery thermal management system as described in claim 1, characterized in that, It also includes a constant temperature chamber, in which the cold plate and the battery are placed.

9. The pulse flow enhanced heat exchange battery thermal management system as described in claim 1, characterized in that, A constant temperature water tank is installed in the circulation pipeline.

10. The pulse flow enhanced heat exchange battery thermal management system as described in claim 1, characterized in that, The cold plate is provided with no less than two independent flow channels, and the liquid flow direction in different flow channels can be switched to the opposite direction according to the valve.

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