R454c-based dual-loop battery thermal management unit, method, and system

Abstract

The application relates to an R454C-based double-loop battery thermal management unit, method and system. In view of the temperature field imbalance problem caused by the coupling of the temperature glide characteristics of the R454C non-azeotropic working medium and the asymmetric heat generation of the battery, the application captures the unit operation parameters in real time through a detection unit, analyzes the component deviation of the non-azeotropic working medium and maps it into a dynamic unit heat exchange equivalent. At the same time, a demand acquisition module acquires the power battery temperature rise slope and hot spot spatial bias to generate an asymmetric load weight. A control module adjusts the shunt ratio of the proportional distribution valve in real time according to the asymmetric load weight, realizes the asymmetric and accurate injection of cold energy in the spatial dimension, and the system is supplemented with a balancing module. The balancing module artificially creates a pressure difference by actively adjusting the compressor frequency difference to drive the directional migration of the gaseous working medium components between the parallel loops. The application compensates for the glide effect from the working medium performance level and the physical flow double dimension, ensures the high uniformity of the global temperature field of the battery, and significantly improves the overall energy efficiency ratio of the heat pump system.

Description

Technical Field

[0001] This invention relates to the field of battery thermal management technology, specifically to a dual-loop battery thermal management unit, method, and system based on R454C. Background Technology

[0002] With increasingly stringent global environmental protection requirements, the field of power battery thermal management is undergoing a transformation from traditional refrigerants with high global warming potential to low-carbon and environmentally friendly media. R454C, a fourth-generation non-azeotropic mixture composed of R32 and R1234yf, has gradually become the mainstream choice to replace R134a in power battery heat pump systems due to its environmental friendliness and excellent thermodynamic cycle performance. In practical applications, R454C is mainly used in passenger vehicle air conditioning and refrigeration systems, indirectly providing cooling and heating power to the power battery pack through a secondary refrigerant circuit.

[0003] However, the significant temperature glide characteristics of R454C pose a serious challenge to the control of the battery temperature field. Due to the large difference in saturation temperatures between the components R32 and R1234yf in R454C, during phase change flow at constant pressure, the lower-boiling-point component preferentially vaporizes, causing the remaining liquid phase component to shift towards the higher-boiling-point direction. This results in the refrigerant's equilibrium temperature continuously rising along the flow path. This physical glide directly leads to spatial inconsistencies in the initial temperature potential (i.e., temperature energy level) of the refrigerant output from the external heat exchanger before it enters the battery pack.

[0004] Power battery packs exhibit inherent thermal imbalance characteristics during operation. This is primarily due to variations in heat dissipation conditions caused by the geometrical location of the cells, and localized heat generation deviations resulting from differences in contact resistance of structures such as the tabs and busbars. When this asymmetry in endogenous heating is superimposed on temperature slippage on the refrigerant side, the non-uniformity of the temperature field is further exacerbated. The initial temperature deviation coupled with the uneven heating of the battery itself can easily lead to temperature differences exceeding safe limits across the battery pack, severely impacting cell lifespan and system safety.

[0005] Therefore, when a power battery uses R454C as the working medium, due to the operating characteristics of R454C, the component ratio of R454C may fluctuate due to system circulation, minor leaks, or differences in solubility, leading to a shift in slip characteristics. Combined with the operating characteristics of the power battery, this results in a large temperature fluctuation range, and existing adjustment methods are insufficient to provide adequate regulation. This leads to insufficient local heat exchange driving force in the power battery, resulting in severe uneven cooling and significantly shortening the cell cycle life. Therefore, it is necessary to research a dual-loop battery thermal management unit, method, and system based on R454C. Summary of the Invention

[0006] Therefore, the purpose of this invention is to provide a dual-loop battery thermal management unit, method, and system based on R454C, which effectively solves the problem of temperature field imbalance caused by the temperature slip characteristics of the 454C non-azeotropic working fluid in phase change cycle and the asymmetric internal heating of the power battery in existing battery management methods.

[0007] To achieve the above objectives, the technical solution adopted by this invention is as follows: a dual-loop battery thermal management unit based on R454C, comprising a power battery, a first cooling circuit, a second cooling circuit, a first unit, and a second unit. A uniformly distributed temperature acquisition array is installed within the power battery. The first and second flow channels are arranged in counter-current configuration within the power battery. Pressure sensors and temperature sensors for monitoring the working fluid state are installed on the first and second units. The evaporators of the first and second units are coupled and exchange heat with the first and second cooling circuits, respectively. The inlets of the first and second flow channels are connected to the outlets of the first and second cooling circuits, respectively. The outlets of the first and second flow channels are connected together to the inlet of a flow equalization chamber. A proportional distribution valve is installed at the rear of the flow equalization chamber, with its two outlets connected to the inlets of the first and second cooling circuits, respectively, for returning the mixed refrigerant to the corresponding unit evaporator according to a preset ratio.

[0008] Furthermore, a dual-loop battery thermal management method based on R454C includes the following steps:

[0009] S1. Global Data Acquisition:

[0010] The pressure and temperature signals in the circuits of the first and second generator units are collected in real time and synchronously; the temperature distribution matrix of the entire power battery is obtained through a temperature sampling array distributed inside the power battery.

[0011] S2. Feature Data Processing:

[0012] Based on the pressure and temperature signals of the first and second units, and combined with the mapping relationship of the non-azeotropic working fluid properties, the ratio of the first component and the ratio of the second component are calculated respectively, and converted into the current unit heat exchange equivalent of each unit.

[0013] Based on the global temperature distribution matrix of the power battery, the overall average temperature, temperature rise slope characteristics and hot spot spatial bias are extracted. The first and second demands, which characterize the real-time heat load at both ends of the power battery, are generated by weighted mapping.

[0014] S3. Flow distribution control:

[0015] Using primary and secondary demand as cooling capacity allocation targets and unit heat exchange equivalent as a weighting factor, the flow distribution ratio of the proportional distribution valve is calculated.

[0016] S4. Execution:

[0017] The proportional distribution valve receives the diversion ratio and diverts the homogenized refrigerant to the first cooling circuit and the second cooling circuit.

[0018] A dual-loop battery thermal management system based on R454C includes,

[0019] Parallel units include a first unit and a second unit connected in parallel in the refrigeration circuit, wherein the first unit and the second unit use non-azeotropic R454C as the circulating working fluid;

[0020] The detection unit is located between the intake side pipelines of the first unit and the second unit, and is used to detect the first component ratio and the second component ratio of the first unit and the second unit, respectively.

[0021] The refrigerant heat exchange module includes a first cooling circuit and a second cooling circuit coupled to the heat exchangers of the first unit and the second unit, respectively; the inlets of the first cooling circuit and the second cooling circuit are respectively connected to the two ends of the power battery, and the power battery is cooled and heat exchanged in a countercurrent manner.

[0022] The demand acquisition module is used to collect temperature signals and temperature rise rates at different locations of the power battery in real time, and convert them into first and second demands corresponding to the two ends of the power battery.

[0023] The control module obtains the diversion ratio based on the first component ratio, the second component ratio, the first demand, and the second demand;

[0024] The flow distribution module is located at the outlet of the first cooling circuit and the second cooling circuit, and is used to mix the refrigerant and then allow it to enter the heat exchanger according to the flow ratio.

[0025] Furthermore, pressure and temperature sensors are installed on the high-pressure subcooled liquid pipeline between the condenser outlet and the electronic expansion valve of each unit; based on the obtained liquid phase pressure and liquid phase temperature, the mass percentage of the low-boiling-point component R32 in the working fluid is obtained and used as the working fluid component ratio.

[0026] Furthermore, the requirement acquisition module includes:

[0027] Acquisition Unit: Used to acquire temperature distribution information of the power battery, and extract overall average temperature and temperature rise slope features based on the temperature distribution information;

[0028] Analysis Unit: Based on the overall average temperature, calculate the basic circulating cooling capacity required by the system; based on the temperature distribution information, determine the spatial offset of the hot spot center relative to the geometric center of the battery; amplify the spatial offset using the temperature rise slope characteristics to generate an asymmetric load weight; couple the basic circulating cooling capacity with the asymmetric load weight to calculate the first demand and the second demand respectively, which are used to guide the flow distribution module's flow allocation ratio.

[0029] Furthermore, using the real-time obtained first component ratio and second component ratio, the unit heat exchange equivalent of the first unit and the second unit under the current working fluid concentration is calculated; the first demand and the second demand are used as the objective function for cooling capacity allocation, and the unit heat exchange equivalent is used as the weighting factor to calculate and generate the initial flow split ratio.

[0030] Furthermore, it also includes a balancing module disposed between the intake side pipelines of the first unit and the second unit. The balancing module includes a balancing branch and a pulse valve. The balancing branch is connected between the intake side pipelines of the first unit and the second unit, and the pulse valve is disposed on the balancing branch.

[0031] Furthermore, a first check valve and a second check valve are provided on the balance branch, and a switching valve is connected in parallel to the first check valve and the second check valve.

[0032] Furthermore, based on the deviation between the first and second requirements, the operating frequencies of the compressors of the first and second units are adjusted to generate a pressure difference across the balance branch. Driven by the pressure difference, the controlled pulse valve performs gaseous interaction of the working fluid components.

[0033] Furthermore, when the flow distribution module reaches the preset adjustment limit and the spatial heat load deviation represented by the first demand and the second demand exceeds the preset first-level deviation threshold, the drive pulse valve is opened to construct a cooling energy level difference through component offset; when the component concentration on either side of the real-time monitored first component ratio and second component ratio deviates from the preset range, while the component concentration on the other side is within its preset range, the drive pulse valve is opened to perform component mutual replenishment or concentration reconstruction.

[0034] The beneficial effects of the above technical solution are as follows: By deeply exploring the physicochemical properties of the non-azeotropic working fluid R454C, this invention constructs a dynamic equilibrium system capable of adaptively adjusting the energy level distribution. This breaks away from the traditional thermal management system's reliance on a single dimension of adjusting the flow carrier, instead introducing the mass dimension of working fluid component concentration, deeply coupling the slip characteristics of the working fluid side with the asymmetric heat generation characteristics of the battery side. By analyzing the working fluid components in real time and mapping them to quantifiable unit heat transfer equivalents, the system can reconstruct the cooling capacity distribution based on the spatial bias and temperature rise slope of the battery's internal heat load, eliminating the thermal imbalance problem caused by the inherent temperature slip of the environmentally friendly working fluid during phase change cycling and the uneven internal heat generation of the battery.

[0035] In its practical operation, this invention captures the pressure and temperature at the outlets of the condensers of the first and second units, and uses the bubble point line mapping relationship to analyze the real-time concentration of the R32 component, thus establishing the initial heat transfer potential of each loop. Simultaneously, a global temperature field matrix of the battery is constructed using a temperature acquisition array, and the overall average temperature is extracted as the cooling capacity baseline. The temperature rise slope characteristic is obtained through first-order difference calculation. This slope characteristic is used to dynamically amplify the spatial offset of the hotspot's centroid from the geometric center, generating asymmetric load weights, thereby calculating the differentiated first and second demands at both ends of the battery. Based on this, the control module calculates the action command of the proportional distribution valve, enabling the homogenized refrigerant to flow as needed to the evaporator with the matching energy level.

[0036] The technological advancements of this invention significantly improve the uniformity of the battery's overall temperature field and system safety. By introducing the temperature rise slope as a feedforward judgment indicator, it can predict transient conditions such as high-rate discharge or fast charging. Trend hedging effectively compensates for the physical inertia of R454C working fluid regulation and heat pump circulation, preventing overheating caused by battery thermal inertia. Furthermore, the combination of the proportional distribution valve and the flow equalization chamber ensures that the cooling medium entering the reverse flow channel inside the battery has a highly deterministic initial temperature. Even under extreme conditions where flow regulation reaches physical limits, the balancing module can still induce the directional migration of gaseous working fluid rich in high-energy components between units through the pressure difference driven by the compressor frequency difference, achieving secondary energy level reconstruction and component self-healing.

[0037] In summary, this invention solves the inherent temperature potential deviation defect of R454C in application. It utilizes a detection unit to analyze the component shift of the non-azeotropic working fluid in real time and map it to unit heat transfer equivalent. Combined with the feedforward deconstruction of the power battery temperature rise slope and hot spot spatial bias by the demand acquisition module, it generates asymmetric load weights to accurately guide the flow distribution ratio of the proportional distribution valve. Furthermore, the balancing module uses the compressor pressure difference to drive the directional migration of working fluid components to achieve secondary energy potential reconstruction. This effectively offsets the temperature field imbalance caused by the asymmetric coupling between the working fluid temperature slip characteristics and the battery's internal heating, significantly improving the uniformity of the power battery's overall temperature field and the system's energy efficiency ratio. Attached Figure Description

[0038] Figure 1 This is a logic block diagram of the present invention;

[0039] Figure 2 This is a circuit connection diagram of the present invention;

[0040] Figure 3 This is a schematic diagram of the implementation structure of the balancing module;

[0041] Figure 4 This is a comprehensive implementation logic block diagram of the present invention.

[0042] Reference numerals in the attached drawings: 1. First unit; 2. Second unit; 3. First cooling circuit; 4. Second cooling circuit; 5. Proportional distribution valve; 6. First check valve; 7. Second check valve; 8. Switching valve; 9. Pulse valve. Detailed Implementation

[0043] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0044] Example 1: This example aims to provide a dual-loop battery thermal management unit based on R454C and a thermal management method based on the unit. Addressing the temperature slip effect of the non-azeotropic R454C working fluid in the heat pump cycle, and the imbalance of local heat transfer driving force (temperature potential difference) caused by the asymmetric coupling of this effect with the heat generation in the power battery space, a unit architecture with component sensing and dynamic refrigerant flow reconfiguration functions is provided. By configuring a dual-loop system, two independent cooling channels are set within the battery, each driven by an independent heat pump unit, forming an independent cycle. The two units independently adjust the flow rate, velocity, and inlet temperature according to the real-time heat load at both ends of the battery, achieving differentiated supply of cooling capacity at both ends.

[0045] like Figure 1-2As shown, a dual-loop battery thermal management unit based on R454C includes a power battery, a first cooling loop 3, a second cooling loop 4, a first unit 1, and a second unit 2. For a battery cooling system using R454C as the working fluid, this embodiment dynamically adjusts the flow ratio of the refrigerant entering the first unit 1 and the second unit 2 after mixing, based on the battery heat load distribution fed back by a temperature acquisition array and the working fluid component energy levels calculated by pressure / temperature sensors, using a proportional distribution valve 5. The combination of the flow equalization chamber and the proportional distribution valve 5 solves the problem of inconsistent heat exchanger outlet temperature levels caused by R454C temperature slippage, ensuring that the cooling medium entering the battery has a controllable initial energy level.

[0046] In this specific implementation, a uniformly distributed temperature acquisition array is installed inside the power battery. The power battery has a first flow channel and a second flow channel arranged in counter-current flow. The control object of both units is the power battery. To obtain the performance data of the power battery, a temperature acquisition array is integrated inside it. The temperature acquisition array includes multiple high-precision temperature sensors evenly distributed in a matrix to capture transient temperature field data across the entire battery pack. In the internal cooling layer of the power battery, the first and second flow channels are arranged in a stacked and staggered manner, employing a counter-current heat exchange method to counteract the temperature gradient generated by the refrigerant's temperature rise along the flow path.

[0047] Pressure and temperature sensors are installed on the first unit 1 and the second unit 2 to monitor the working fluid state. The evaporators of the first unit 1 and the second unit 2 are coupled to the first cooling circuit 3 and the second cooling circuit 4 for heat exchange, respectively. In this embodiment, the first unit 1 and the second unit 2 are configured in parallel, both using non-azeotropic R454C as the circulating working fluid. Pressure and temperature sensors are installed on the high-pressure subcooled liquid pipeline between the condenser outlet and the electronic expansion valve of each unit to monitor the real-time physical properties of the working fluid. Through the parameters obtained by these two types of sensors, the controller can calculate the current component ratio of the circulating working fluid (i.e., the mass concentration of R32) in real time.

[0048] The inlets of the first and second flow channels are connected to the outlets of the first cooling circuit 3 and the second cooling circuit 4, respectively; the unit achieves heat transfer through the first cooling circuit 3 and the second cooling circuit 4. The evaporators of the first unit 1 and the second unit 2 serve as cold sources, coupled with the corresponding first and second cooling circuits 4 for heat exchange. The inlets of the first and second flow channels are connected to the outlets of the first and second cooling circuits 4, respectively, ensuring that refrigerant with a specific energy level enters the battery.

[0049] The outlets of the first and second flow channels are connected to the inlet of the heat exchanger homogenization chamber. This chamber has built-in static mixing fins designed to forcibly mix the two refrigerants carrying battery heat back to eliminate temperature differences and achieve homogenization of refrigerant properties. A proportional distribution valve 5 is provided at the rear of the heat exchanger homogenization chamber. The two outlets of the proportional distribution valve 5 are respectively connected to the inlets of the first cooling circuit 3 and the second cooling circuit 4, used to return the mixed refrigerant to the corresponding unit evaporator according to a preset ratio.

[0050] This embodiment targets a battery cooling system using R454C non-azeotropic refrigerant. It acquires the real-time heat load distribution across the entire battery area through a temperature acquisition array and combines this with the energy potential of the refrigerant components calculated by pressure and temperature sensors. A proportional distribution valve 5 dynamically adjusts the flow ratio of the refrigerant entering the first unit 1 and the second unit 2 after mixing. Simultaneously, this embodiment achieves physical homogenization of the refrigerant return heat through the flow homogenization chamber and the proportional distribution valve 5, providing the same refrigerant to both units. This provides a basis for proportional distribution and ensures that the cooling medium injected into the power battery channel has a highly deterministic initial temperature potential distribution.

[0051] In terms of control strategy, this embodiment performs precise energy level offset allocation based on working fluid property compensation and spatial heat demand: by comprehensively evaluating the heat demand characteristics at both ends of the power battery and the actual heat exchange equivalent of each unit circuit, the opening of the proportional distribution valve 5 is dynamically adjusted, which effectively solves the problem of insufficient local heat exchange driving force caused by the asymmetric coupling of working fluid property drift and battery heat generation. While broadening the system adjustment bandwidth, it significantly improves the uniformity of the temperature field across the entire power battery.

[0052] Example 2

[0053] like Figure 1-2 As shown, this embodiment provides a dual-loop battery thermal management method based on R454C, specifically including the following steps:

[0054] S1. Global Data Acquisition:

[0055] The pressure and temperature signals in the circuits of the first unit 1 and the second unit 2 are collected in real time and synchronously; the temperature distribution matrix of the entire power battery is obtained through the temperature sampling array distributed inside the power battery.

[0056] S2. Feature Data Processing:

[0057] Based on the pressure and temperature signals of Unit 1 and Unit 2, and combined with the non-azeotropic refrigerant property mapping relationship, the first component ratio and the second component ratio are calculated respectively, and converted into the current unit heat transfer equivalent of each unit. Based on the saturated property mapping relationship of R454C, the current real-time component ratio of Unit 1 and Unit 2 is calculated using the collected pressure and temperature signals. Since the latent heat of vaporization of R32 and R1234yf is significantly different, the current unit heat transfer equivalent of each loop (i.e., the heat limit that can be transported by a unit mass flow rate of refrigerant) is further calculated based on the real-time component ratio.

[0058] Based on the global temperature distribution matrix of the power battery, the overall average temperature, temperature rise slope characteristics, and hotspot spatial bias are extracted. A weighted mapping is used to generate the first and second demands characterizing the real-time heat load at both ends of the power battery. During implementation, the basic cooling energy level requirement of the system is determined by extracting the overall average temperature from the temperature distribution matrix. Time-difference processing is performed on the temperature signal to extract the temperature rise slope characteristics, which are used to characterize the transient changes in heat generation power. The spatial position of the highest temperature point relative to the geometric center of the battery pack is located, generating the hotspot spatial bias. The spatial bias is weighted and amplified using the temperature rise slope to calculate the first and second demands characterizing the urgency of cooling at both ends of the battery.

[0059] S3. Flow distribution control:

[0060] Using the primary and secondary demands as the targets for cooling capacity allocation, and the unit heat exchange equivalent as the weighting factor, the flow distribution ratio of the proportional distribution valve 5 is calculated.

[0061] S4. Execute

[0062] The proportional distribution valve 5 receives the diversion ratio and diverts the homogenized refrigerant to the first cooling circuit 3 and the second cooling circuit 4, thereby ensuring that the homogenized refrigerant with a uniform initial temperature is precisely guided to the first and second cooling circuits 4. The refrigerant then passes through an evaporator with a corresponding energy level for cooling and finally enters the countercurrent flow channel inside the battery, completing the balanced circulation of the entire temperature field.

[0063] This embodiment transforms the uncertain component slip during R454C operation into a definite weighting factor, ensuring that the temperature control system remains highly robust when refrigerant performance fluctuates. It also identifies heat accumulation trends in advance by using the temperature rise slope, avoiding instantaneous overheating of the battery due to thermal inertia. This significantly reduces the energy waste caused by blindly increasing the water pump flow rate to compensate for the temperature rise at the slip end in traditional systems.

[0064] Example 3

[0065] This embodiment describes a system for a dual-loop battery thermal management unit based on R454C, including parallel units, a detection unit, a refrigerant heat exchange module, a flow distribution module, and a demand acquisition module. The detection unit captures the working fluid state of the first and second units 2 in real time. Since there is a definite physical property mapping relationship between the pressure and temperature of R454C (R32 / R1234yf mixture) in the liquid phase, the system calculates the real-time mass percentage of the low-boiling-point component R32 by acquiring the liquid phase pressure and temperature at the condenser outlet of each unit.

[0066] The parallel unit includes a first unit 1 and a second unit 2 connected in parallel in the refrigeration circuit. Both units use non-azeotropic R454C as the working fluid. Each unit includes a compressor, evaporator, condenser, electronic expansion valve, temperature sensor, and pressure sensor. The compressor is a variable frequency compressor, serving as the core power source of the unit. It dynamically adjusts the mass flow rate of the R454C working fluid by receiving frequency commands from the control module. In the non-azeotropic system, the compressor speed affects not only the cooling capacity but also the slip temperature rise rate on the evaporator side. All components work together to complete the compression, condensation, throttling, and evaporation cycles of the working fluid, achieving the generation and transfer of cooling capacity.

[0067] The detection unit is set between the suction side pipelines of the first unit 1 and the second unit 2, and is used to detect the first component ratio and the second component ratio of the first unit 1 and the second unit 2, respectively; the pressure sensor and temperature sensor on the high-pressure subcooled liquid pipeline between the condenser outlet of each unit and the electronic expansion valve; based on the obtained liquid phase pressure and liquid phase temperature, the mass percentage of the low-boiling-point component R32 in the working fluid is obtained and used as the working fluid component ratio.

[0068] Using the real-time obtained first component ratio and second component ratio, the unit heat exchange equivalent of the first unit 1 and the second unit 2 at the current working fluid concentration is calculated; in this embodiment, the detection unit calculates the R454C component ratio by monitoring the liquid pressure and temperature at the condenser outlet of the first and second units 2: the bubble point temperature of the non-azeotropic working fluid R454C changes with the component ratio.

[0069] Under constant pressure, the bubble point temperature of a non-azeotropic working fluid decreases with increasing concentration of the low-boiling-point component. By measuring the difference between the actual liquid temperature and the bubble point temperature of the standard component at that pressure, the component offset can be reversely analyzed. Therefore, it can be seen that under a known pressure, there is a one-to-one mapping relationship between the temperature of the supercooled liquid and the mass percentage of the component. This mapping relationship is based on a polynomial fitting function of the R454C bubble point line or a property lookup table. Based on this mapping relationship, the mass percentage of the low-boiling-point component R32 is determined. By calculating the average latent heat of phase change at the current working fluid concentration, the unit heat transfer equivalent is obtained. The specific calculation formula is as follows:

[0070]

[0071] In the formula, and These are the standard phase transition enthalpy differences between pure components R32 and R1234yf at the current evaporation pressure, respectively. This represents the theoretical refrigeration potential per unit mass flow rate of the working fluid under the current composition. This represents the real-time mass percentage of the low-boiling-point component R32.

[0072] The refrigerant heat exchange module includes a first cooling circuit 3 and a second cooling circuit 4, which are respectively coupled to the heat exchangers of the first unit 1 and the second unit 2. The inlets of the first cooling circuit 3 and the second cooling circuit 4 are respectively connected to the two ends of the power battery and perform cooling and heat exchange on the power battery in a countercurrent manner.

[0073] The demand acquisition module is used to collect temperature signals and temperature rise rates at different locations of the power battery in real time, and convert them into a first demand and a second demand corresponding to the two ends of the power battery. The demand acquisition module is used to collect temperature signals and temperature rise rates at different locations of the power battery in real time, and convert them into a first demand (cooling demand at the end near the cooling circuit of the first unit 1) and a second demand (cooling demand at the end near the cooling circuit of the second unit 2) corresponding to the two ends of the power battery, so as to provide a target basis for cooling distribution and avoid local overheating caused by thermal imbalance of the power battery.

[0074] In implementation, the demand acquisition module includes a data acquisition unit and an analysis unit. The data acquisition unit acquires the temperature distribution information of the power battery and extracts the overall average temperature and temperature rise slope characteristics based on the temperature distribution information. The overall average temperature reflects the current thermal state of the power battery pack and is used to determine the system's basic cycle cooling requirements. Due to the large volume and numerous cells in the power battery pack, a single-point temperature cannot represent the overall energy level. This embodiment uses a spatially weighted arithmetic average method to obtain the overall average temperature. For example, the data acquisition unit obtains the instantaneous temperature set through temperature sensors distributed at n characteristic locations within the battery pack (such as cell surfaces, tabs, and module center), and then performs an arithmetic average.

[0075] The temperature rise slope characteristic represents the trend of battery heat generation power. Because the component slip regulation of R454C has a certain physical inertia, relying solely on absolute temperature values ​​(hysteresis signals) for regulation can lead to overheating. By calculating the temperature rise slope, the system can identify whether the battery is under high-heat-generating conditions such as high-rate discharge or fast charging. The calculation method involves performing a first-order difference operation on the sampled data; that is, for each sampling point, the rate of temperature change between the current and previous sampling times is calculated, and the fastest temperature rise rate across the entire range is extracted as the feature value.

[0076] When a step increase in the temperature rise slope is detected in a specific area, it is determined that the area is in a state of intense heat generation. At this time, the analysis unit converts this slope characteristic into a dynamic amplification factor, which is applied to the weighted calculation of the spatial bias. By triggering the proportional distribution valve 5 in advance, the system can pre-allocate a higher level of cooling flux to the high heat generation area before the absolute temperature value reaches the threshold. This utilizes trend offsetting to compensate for the physical inertia of the R454C working fluid regulation, ensuring that the battery temperature field always remains within a safe steady-state range.

[0077] Analysis Unit: Based on the overall average temperature, calculate the basic cooling capacity required for the system's basic cycle. In this embodiment, the total basic cooling capacity required to maintain the system's steady state is calculated by combining the global average temperature with the battery pack's thermal capacity characteristics.

[0078] Based on the temperature distribution information, the spatial offset of the hotspot center relative to the battery's geometric center is determined. By comparing the temperature scalar values ​​at each sampling point, the thermal centroid of the current temperature field is located. The spatial displacement of this centroid relative to the battery pack's geometric center is calculated to identify the degree of thermal asymmetry.

[0079] Using the primary and secondary demands as the objective function for cooling capacity allocation, and with the unit heat exchange equivalent as the weighting factor, the initial flow distribution ratio is calculated. The specific calculation formula is as follows:

[0080]

[0081] In the formula, It is a dimensionless asymmetric weighting factor used to describe the degree to which the heat load is tilted towards one end; This represents the spatial offset distance between the current hotspot center and the battery's geometric center. This is half the length of the battery pack, used for normalization processing; This is a dynamic amplification factor, used to pre-adjust based on the degree of temperature rise; The slope of the temperature rise is a characteristic that represents the local heat generation power.

[0082] The spatial offset is amplified using the temperature rise slope characteristic to generate an asymmetric load weight. The base cycle cooling capacity is coupled with the asymmetric load weight to calculate the first and second demands, which guide the flow distribution module's allocation ratio. The specific formula is as follows.

[0083]

[0084]

[0085] and These represent the real-time cooling demand mapped from both ends of the power battery. This is the baseline value of the total system demand calculated based on the global average temperature; through The total cooling demand is redistributed spatially to achieve precise coverage of localized high heat load areas.

[0086] On the supply side, the pressure and temperature sensors of the first and second units 2 are used to analyze the compositional shift of R454C in real time and convert it into unit heat exchange equivalent, i.e. and This represents the maximum heat (energy level) that a unit flow rate of refrigerant can carry under the current component ratio.

[0087] Finally, the control module and Let be the objective function, with and To adjust the weights and generate the final splitting instructions, the specific formula is as follows:

[0088]

[0089] In the formula, The proportional distribution valve 5 is directed to the flow distribution ratio of the first cooling circuit 3. and These are the unit heat exchange equivalents calculated in real time for Unit 1 and Unit 2, respectively.

[0090] If the first requirement The first unit (Unit 1) has a larger energy level due to its higher proportion of R32. The above logic can achieve a balance The value should be adjusted to avoid wasting pump power by blindly increasing the flow rate. If the first side has high demand but low energy level... If the slippage is lower (negative impact of slippage), the formula will be significantly increased. The energy level deficiency is compensated by the flow flux.

[0091] The control module obtains the shunting ratio based on the first component ratio, the second component ratio, the first demand, and the second demand. By evaluating the current energy level difference between the two circuits and the load deviation at both ends of the battery, the control module calculates an optimal shunting ratio. This ensures that the heat transfer potential carried by the two refrigerants before entering the battery flow channel is precisely matched with the local heat generation power of the battery, eliminating the thermal imbalance caused by the superposition of R454C slip characteristics and uneven battery heating.

[0092] The flow distribution module, located at the outlets of the first cooling circuit 3 and the second cooling circuit 4, is used to mix the refrigerant and distribute it into the heat exchanger according to the specified flow ratio. The flow distribution module is positioned at the outlet of the refrigerant circuit and directly executes the distribution commands generated by the control module. First, the two refrigerant streams from the battery channel outlet converge in the equalization chamber. The mixing structure inside the chamber eliminates the return water temperature difference, resetting the refrigerant state to a uniform temperature reference, thus solving the problem of inconsistent initial temperatures before entering the unit. Subsequently, the equalized refrigerant is re-cut and sent to the first and second cooling circuits 4 according to a preset ratio via the proportional distribution valve 5. The proportional distribution valve 5, by adjusting the physical flow rate and coordinating with the spatial layout of the counter-flow channel, ensures that the high-energy refrigerant flows precisely to the high-load cell area, ultimately achieving dynamic balance of the battery's overall temperature field.

[0093] This embodiment provides a thermal management system that deeply couples the non-azeotropic characteristics of R454C working fluid with the asymmetric heat generation of the power battery. A detection unit analyzes the working fluid composition shift in real time and maps it to unit heat transfer equivalent. Simultaneously, a demand acquisition module performs feedforward energy level reconstruction of the battery heat load using temperature rise slope and spatial offset. The control module calculates a precise flow distribution ratio based on the differentiated demands at both ends of the battery and the real-time energy potential of the working fluid as a correction weight. The flow distribution module performs asymmetric flux adjustment after flow equalization, and, in conjunction with the counter-current layout of the flow channels, compensates for the temperature slip effect of R454C from both physical performance level and physical flow rate dimensions. Ultimately, this achieves dynamic equilibrium of the entire temperature field of the power battery and matches the system's energy efficiency.

[0094] Example 4

[0095] This embodiment aims to address the problem of extremely uneven component distribution (e.g., insufficient refrigeration capacity due to excessively low R32 concentration on one side) or spatial heat load deviation exceeding the flow regulation limit between two parallel units under long-term operation or extreme conditions using R454C non-azeotropic refrigerant. This embodiment introduces an active balancing module, specifically installed between the suction-side piping of the first unit 1 and the second unit 2. This breaks the completely independent closed state of the two units, utilizing the artificial pressure difference generated by the compressor speed difference to drive the gaseous refrigerant to migrate directionally between the two units, thereby achieving a secondary reconstruction of the refrigeration energy potential at the molecular level.

[0096] like Figure 3-4 As shown, in terms of specific structure, the balancing module includes a balancing branch and a pulse valve 9. The balancing branch is connected between the intake side pipelines of the first unit 1 and the second unit 2. The pulse valve 9 is installed on the balancing branch and acts as an actuator to precisely control the interactive flux of the gaseous working fluid through high-frequency switching.

[0097] In a further implementation, a first check valve 6 and a second check valve 7 are installed on the balancing branch, and a switching valve 8 is connected in parallel to the first check valve 6 and the second check valve 7. The first check valve 6 and the second check valve 7 on the branch are used to limit the flow direction of the working fluid, while the parallel switching valve 8 provides flexibility for changing the flow direction, ensuring that the working fluid can flow from the first unit 1 to the second unit 2, or it can flow in the opposite direction.

[0098] In specific control, the operating frequency of the compressors of the first unit 1 and the second unit 2 is adjusted according to the deviation between the first demand and the second demand to generate a pressure difference at both ends of the balance branch. According to the principle of fluid mechanics, the suction pressure on the side with higher speed will be relatively lower, thereby artificially creating a pressure difference at both ends of the balance branch. Driven by the pressure difference, the controlled pulse valve 9 performs gaseous interaction of the working fluid components.

[0099] Scenario 1: The load deviation exceeds the flow regulation limit, requiring an increase in the cooling capacity of the high-load unit.

[0100] When the flow distribution module's diversion ratio reaches a preset adjustment limit, and the spatial heat load deviation represented by the first demand and the second demand exceeds a preset first-level deviation threshold, the drive pulse valve 9 opens to construct a cooling energy potential difference through component offset; when the flow distribution ratio reaches the limit (e.g. (If the battery temperature difference still cannot be balanced even after being adjusted to the set range), the drive pulse valve 9 will open. The pressure difference will induce the gaseous working fluid rich in R32 (high-energy component) to the high-load unit, achieving a sudden increase in cooling energy level.

[0101] During operation, the control module activates the balancing module, first adjusting the operating frequencies of the compressors in Unit 1 and Unit 2, so that the compressor speed on the high-load side (e.g., Unit 1) is higher than that on the low-load side (Unit 2). According to fluid mechanics principles, the suction pressure on the side with higher speed will be relatively lower, thus artificially creating a pressure difference across the balancing branch (the pressure on the low-load side is higher than that on the high-load side). Subsequently, the control module drives the pulse valve 9 to open at a preset frequency. Driven by the pressure difference, the gaseous working fluid (rich in high-energy R32 components) on the suction side of the low-load unit will migrate directionally to the high-load unit through the balancing branch. During the migration process, the detection unit monitors the component ratio changes of the two units in real time. When the R32 concentration in the high-load unit rises to the preset range and the battery temperature difference drops to a safe range, the control module controls the pulse valve 9 to close, the balancing module stops working, and the system returns to the normal flow regulation mode.

[0102] Scenario 2: The distribution of unit components is extremely uneven, requiring component mutual replenishment or concentration reconfiguration.

[0103] When the detection unit detects in real time that the concentration of a component on either side of the first component ratio and the second component ratio deviates from the preset range (e.g., the concentration of 2R32 in the second unit is too low, resulting in insufficient cooling capacity), while the concentration of the component on the other side is within the preset range (e.g., the concentration of 1R32 in the first unit is normal), the drive pulse valve 9 is opened to perform component mutual replenishment or concentration reconstruction.

[0104] In actual operation, the control module activates the balancing module, first adjusting the operating frequency of the compressors of the two units so that the compressor speed on the normal component side (unit 1) is higher than that on the abnormal component side (unit 2), creating a pressure difference at both ends of the balancing branch (the suction pressure on the normal component side is lower than that on the abnormal side). Then, the control module drives the pulse valve 9 to open, and simultaneously controls the opening and closing state of the switching valve 8 according to the migration direction requirements, so that the gaseous working fluid rich in R32 on the normal component side migrates directionally to the abnormal component side. The component ratio changes are monitored in real time. When the R32 concentration of the abnormal side unit returns to the preset range and the component distribution of the two units tends to be balanced, the control module closes the pulse valve 9 and the switching valve 8, and the balancing module stops working, ensuring that the heat exchange capacity of the two units is restored to balance.

[0105] This embodiment aims to solve the problem of extremely uneven component distribution or spatial heat load deviation exceeding the flow regulation limit between two parallel units when using R454C non-azeotropic refrigerant under long-term operation or extreme conditions. It achieves directional migration of refrigerant components and secondary reconstruction of refrigeration capacity through active control, ensuring stable operation of the system under all conditions. It breaks the completely independent closed state of the two units and uses the artificial pressure difference generated by the difference in compressor speed to drive the directional migration of gaseous refrigerant between the two units, optimize component distribution, and improve the refrigeration capacity of the high-load unit.

Claims

1. A dual-loop battery thermal management unit based on R454C, characterized in that: The system includes a power battery, a first cooling circuit, a second cooling circuit, a first unit, and a second unit. A uniformly distributed temperature acquisition array is installed within the power battery. The first and second flow channels are arranged in counter-current configurations within the power battery. Pressure and temperature sensors for monitoring the working fluid state are installed on the first and second units. The evaporators of the first and second units are coupled to the first and second cooling circuits for heat exchange, respectively. The inlets of the first and second flow channels are connected to the outlets of the first and second cooling circuits, respectively. The outlets of the first and second flow channels are connected to the inlet of a flow equalization chamber. A proportional distribution valve is installed at the rear of the flow equalization chamber, with its two outlets connected to the inlets of the first and second cooling circuits, respectively, for returning the mixed refrigerant to the corresponding unit evaporator according to a preset ratio.

2. A dual-loop battery thermal management method based on R454C, characterized in that: Includes the following steps, S1. Global Data Acquisition: The pressure and temperature signals in the circuits of the first and second generator units are collected in real time and synchronously; the temperature distribution matrix of the entire power battery is obtained through a temperature sampling array distributed inside the power battery. S2. Feature Data Processing: Based on the pressure and temperature signals of the first and second units, and combined with the mapping relationship of the non-azeotropic working fluid properties, the ratio of the first component and the ratio of the second component are calculated respectively, and converted into the current unit heat exchange equivalent of each unit. Based on the global temperature distribution matrix of the power battery, the overall average temperature, temperature rise slope characteristics and hot spot spatial bias are extracted. The first and second demands, which characterize the real-time heat load at both ends of the power battery, are generated by weighted mapping. S3. Flow distribution control: Using primary and secondary demand as cooling capacity allocation targets and unit heat exchange equivalent as a weighting factor, the flow distribution ratio of the proportional distribution valve is calculated. S4. Execution: The proportional distribution valve receives the diversion ratio and diverts the homogenized refrigerant to the first cooling circuit and the second cooling circuit.

3. A system for a dual-loop battery thermal management unit based on R454C, characterized in that: include, Parallel units include a first unit and a second unit connected in parallel in the refrigeration circuit, wherein the first unit and the second unit use non-azeotropic R454C as the circulating working fluid; The detection unit is located between the intake side pipelines of the first unit and the second unit, and is used to detect the first component ratio and the second component ratio of the first unit and the second unit, respectively. The refrigerant heat exchange module includes a first cooling circuit and a second cooling circuit coupled to the heat exchangers of the first unit and the second unit, respectively; the inlets of the first cooling circuit and the second cooling circuit are respectively connected to the two ends of the power battery, and the power battery is cooled and heat exchanged in a countercurrent manner. The demand acquisition module is used to collect temperature signals and temperature rise rates at different locations of the power battery in real time, and convert them into first and second demands corresponding to the two ends of the power battery. The control module obtains the diversion ratio based on the first component ratio, the second component ratio, the first demand, and the second demand; The flow distribution module is located at the outlet of the first cooling circuit and the second cooling circuit, and is used to mix the refrigerant and then allow it to enter the heat exchanger according to the flow ratio.

4. The dual-loop battery thermal management system based on R454C according to claim 3, characterized in that: Pressure and temperature sensors are installed on the high-pressure subcooled liquid pipeline between the condenser outlet and the electronic expansion valve of each unit. Based on the obtained liquid phase pressure and liquid phase temperature, the mass percentage of the low-boiling-point component R32 in the working fluid is obtained and used as the working fluid component ratio.

5. The dual-loop battery thermal management system based on R454C according to claim 3, characterized in that: The requirement acquisition module includes: Acquisition Unit: Used to acquire temperature distribution information of the power battery, and extract overall average temperature and temperature rise slope features based on the temperature distribution information; Analysis Unit: Based on the overall average temperature, calculate the basic circulating cooling capacity required by the system; based on the temperature distribution information, determine the spatial offset of the hot spot center relative to the geometric center of the battery; amplify the spatial offset using the temperature rise slope characteristics to generate an asymmetric load weight; couple the basic circulating cooling capacity with the asymmetric load weight to calculate the first demand and the second demand respectively, which are used to guide the flow distribution module's flow allocation ratio.

6. The dual-loop battery thermal management system based on R454C according to claim 3, characterized in that: Using the real-time obtained first and second component ratios, the unit heat exchange equivalent of the first and second units under the current working fluid concentration is calculated; the first and second demands are used as the objective function for cooling capacity allocation, and the unit heat exchange equivalent is used as the weighting factor to calculate and generate the initial flow split ratio.

7. The dual-loop battery thermal management system based on R454C according to claim 3, characterized in that: It also includes a balancing module disposed between the intake side pipelines of the first unit and the second unit. The balancing module includes a balancing branch and a pulse valve. The balancing branch is connected between the intake side pipelines of the first unit and the second unit, and the pulse valve is disposed on the balancing branch.

8. The dual-loop battery thermal management system based on R454C according to claim 7, characterized in that: The balancing branch is equipped with a first check valve and a second check valve, and a switching valve is connected in parallel to the first check valve and the second check valve.

9. The dual-loop battery thermal management system based on R454C according to claim 7, characterized in that: Based on the deviation between the first and second requirements, the operating frequencies of the compressors of the first and second units are adjusted to generate a pressure difference across the balance branch. Driven by the pressure difference, the controlled pulse valve performs gaseous interaction of the working fluid components.

10. The dual-loop battery thermal management system based on R454C according to claim 7, characterized in that: When the flow distribution module reaches the preset adjustment limit and the spatial heat load deviation represented by the first demand and the second demand exceeds the preset first-level deviation threshold, the drive pulse valve is opened to construct a cooling energy potential difference through component offset. When the concentration of a component on either side of the real-time monitored first component ratio and second component ratio deviates from the preset range, while the concentration of the component on the other side remains within its preset range, the drive pulse valve opens to perform component mutual replenishment or concentration reconstruction.

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