A control method for an energy flow system based on transcritical CO2 thermal management

Abstract

The application belongs to the technical field of new energy vehicles, and discloses a control method of an energy flow system based on transcritical CO2 thermal management, wherein the energy flow system comprises a lithium ion battery, a motor, a CO2 compressor, an outdoor heat exchanger, a front-end water radiator, an indoor heat exchanger, a battery cooler, a four-way reversing valve, a regenerator, a first electronic expansion valve, a second electronic expansion valve, a first electronic water pump, a second electronic water pump, an indoor fan, an outdoor fan and a gas-liquid separator; in the control method, the controlled components comprise the CO2 compressor, the first electronic expansion valve, the second electronic expansion valve, the first electronic water pump, the second electronic water pump, the indoor fan and the outdoor fan. In the technical scheme, different requirements of the battery, the motor and the passenger cabin are comprehensively considered, and comprehensive control is performed in combination with the characteristics of transcritical CO2 circulation, so that the overall performance of the new energy vehicle can be comprehensively improved.

Description

Technical Field

[0001] This invention belongs to the field of new energy vehicle technology, and specifically relates to a control method for an energy flow system based on transcritical CO2 thermal management. Background Technology

[0002] With the evolution of refrigerants, CO2 has been widely used as a natural working fluid; however, the industry currently lacks comprehensive control methods and strategies that reflect the characteristics of the CO2 cycle and are centered on the energy flow.

[0003] Currently, the industry consensus is that heat pump air conditioning technology using transcritical CO2 circulation exhibits excellent heating performance in winter, effectively increasing battery temperature and single-charge capacity. It can also play a greater role in optimizing energy flow, comprehensively improving the vehicle's range, power, and comfort. However, existing control methods for new energy vehicle energy flow systems rarely comprehensively consider the three major characteristics of the vehicle—range, power, and comfort—for unified optimization. Furthermore, the control logic of individual components is often incomplete and imprecise. The vehicle control logic for batteries and motors typically uses the simplest start-stop control method: setting conditions, activating control strategies to restore the controlled variable to the set range when the conditions are met, and then stopping control execution. This method is crude, inefficient, and detrimental to overall vehicle performance. Additionally, when the battery, motor, and passenger compartment—the three major energy-consuming modules—simultaneously require energy allocation, there is no corresponding control algorithm to comprehensively evaluate energy flow and achieve all-round performance improvement. Summary of the Invention

[0004] The purpose of this invention is to provide a control method for an energy flow system based on transcritical CO2 thermal management, in order to solve one or more of the aforementioned technical problems. The technical solution provided by this invention comprehensively considers the different needs of the battery, motor, and passenger compartment, and integrates the characteristics of the transcritical CO2 cycle for comprehensive control, thereby comprehensively improving the overall performance of new energy vehicles.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention provides a control method for an energy flow system based on transcritical CO2 thermal management.

[0007] The energy flow system based on transcritical CO2 thermal management includes: a lithium-ion battery, a motor, a CO2 compressor, an outdoor heat exchanger, a front-end water radiator, an indoor heat exchanger, a battery cooler, a four-way reversing valve, a regenerator, a first electronic expansion valve, a second electronic expansion valve, a first electronic water pump, a second electronic water pump, an indoor fan, an outdoor fan, and a gas-liquid separator; wherein,

[0008] The coolant outlet of the lithium-ion battery is connected to the coolant inlet of the lithium-ion battery via the second heat exchange channel of the battery cooler and the first electronic water pump; the coolant outlet of the motor is connected to the coolant inlet of the motor via the second heat exchange channel of the front-end water radiator and the second electronic water pump; the indoor fan is used to ventilate the passenger compartment through the second heat exchange channel of the indoor heat exchanger; the second heat exchange channel of the outdoor heat exchanger is connected to the first heat exchange channel of the front-end water radiator, and the outdoor fan is used to ventilate the first heat exchange channel of the front-end water radiator through the second heat exchange channel of the outdoor heat exchanger; the CO2 compression... The outlet of the machine is connected to port a of the four-way reversing valve; port b of the four-way reversing valve is divided into two paths, one path is connected to the inlet of the first electronic expansion valve through the first heat exchange channel of the indoor heat exchanger, and the other path is connected to the inlet of the second electronic expansion valve through the first heat exchange channel of the battery cooler; the outlets of the first and second electronic expansion valves merge and are then connected to port c of the four-way reversing valve through the first heat exchange channel of the regenerator and the first heat exchange channel of the outdoor heat exchanger; port d of the four-way reversing valve is connected to the inlet of the CO2 compressor through the gas-liquid separator and the second heat exchange channel of the regenerator.

[0009] In the energy flow system based on transcritical CO2 thermal management, in heating mode, port a of the four-way reversing valve is connected to port b, and port c of the four-way reversing valve is connected to port d; in cooling mode, port a of the four-way reversing valve is connected to port c, and port b of the four-way reversing valve is connected to port d.

[0010] The control method proposes battery energy flow management evaluation index, passenger cabin energy flow management evaluation index, and motor energy flow management evaluation index. The functional relationship between the three indexes and the power consumption, component information and environmental information of each actuator is obtained through mathematical fitting. The maximum gradient optimization method is used to dynamically optimize the system to achieve path optimization.

[0011] In the control method, the proposed evaluation index is used as the judgment standard, so that the exhaust pressure with the optimal evaluation index is the optimal execution exhaust pressure.

[0012] A further improvement of the control method of the present invention is that, in the control method,

[0013] The total cooling and heating demand is controlled by the rotational speed of the CO2 compressor; wherein, as the rotational speed of the CO2 compressor increases, the sum of the heat exchange of the indoor heat exchanger and the battery cooler increases; as the rotational speed of the CO2 compressor increases, the heat exchange of the outdoor fan increases; the rotational speed of the outdoor fan decreases as the vehicle speed increases and increases as the vehicle speed decreases.

[0014] The indoor air supply temperature is controlled by the indoor fan; wherein, as the difference between the required air supply temperature and the ambient temperature decreases, the air supply volume of the indoor fan increases.

[0015] The heat exchange capacity of the indoor heat exchanger is controlled by the first electronic expansion valve; wherein, as the heat exchange demand of the passenger compartment increases, the opening degree of the first electronic expansion valve increases; as the heat exchange demand of the passenger compartment decreases, the opening degree of the first electronic expansion valve decreases.

[0016] The heat exchange of the battery cooler is controlled by the second electronic expansion valve; wherein, as the demand for battery heat exchange increases, the opening of the second electronic expansion valve increases; as the demand for battery heat exchange decreases, the opening of the second electronic expansion valve decreases.

[0017] The first electronic water pump controls the flow rate of battery cooling water, and the second electronic water pump controls the flow rate of motor cooling water.

[0018] A further improvement to the control method of the present invention lies in that the optimized control objectives of the control method include: lithium-ion battery discharge rate, lithium-ion battery temperature, motor temperature, motor torque, passenger compartment comfort, and the COP energy efficiency ratio of the vehicle thermal management system; wherein,

[0019] The heat exchange in the battery cooler is regulated by a CO2 compressor, a second electronic expansion valve, and a first electronic water pump. This energy serves as the main source of cooling or heating for the battery. At the same time, the self-generated heat from different battery rates and the heat from natural convection between the battery and the environment are also taken into account. The heat exchange in the battery cooler is used to regulate the battery temperature and improve the battery's single discharge capacity. By balancing the power consumption of the compressor and the improvement effect of the battery's single discharge capacity, the battery's thermal management efficiency is improved.

[0020] The heat exchange capacity of the indoor heat exchanger is regulated by a CO2 compressor, a first electronic expansion valve, and an indoor fan. This energy serves as the main source of cooling or heating energy for the passenger cabin, used to regulate the temperature and temperature field of the passenger cabin and maintain the thermal comfort of passengers in the passenger cabin.

[0021] The second electronic water pump and outdoor fan are used to regulate the heat exchange in the front-end water radiator. This energy serves as the main source of cooling for the motor and electronic control system, regulating the motor temperature and ensuring the motor's power limit.

[0022] A further improvement to the control method of this invention lies in the following: the use of a CO2 compressor, a second electronic expansion valve, and a first electronic water pump to regulate the heat exchange in the battery cooler serves as the primary source of cooling or heating energy for the battery. Simultaneously, it considers the self-generated heat from different battery rates and the heat from natural convection heat exchange between the battery and the environment. The heat exchange in the battery cooler is used to regulate the battery temperature, thereby increasing the battery's single-discharge capacity. This step, by balancing the compressor's power consumption and the improvement in the battery's single-discharge capacity, improves the battery's thermal management efficiency.

[0023] Define the effective thermal management rate M of the battery bat , is represented as ,

[0024] M bat =(Q dis，e -Q dis，r ) / Q chiller ;

[0025] In the formula, Q dis，r Q is the battery's rated discharge capacity for a single charge at the current ambient temperature; dis,e This is the rated discharge capacity of the battery under the specified temperature after implementing thermal management strategies. The capacity value is greater than the rated discharge capacity under ambient temperature without thermal management. Q chiller This refers to the amount of heat or cold supplied to the battery by the battery cooler in the system.

[0026] Using the functional relationship of battery effective thermal management efficiency, we perform objective optimization of a system of multiple linear equations under the current operating state, with COP as the optimization object. bat The feasible region is the power and temperature operating range of each component, yielding results only with respect to the discharge rate C. dis The single discharge capacity is a function of the single discharge capacity, and the optimal single discharge capacity is obtained by solving the extreme points of advanced mathematics.

[0027] in,

[0028] Define the single-cycle discharge capacity Q and battery temperature T of a lithium-ion battery. ba Discharge rate C dis The relationship between them; among them,

[0029] The definitions of discharge rate and battery temperature are as follows:

[0030] C dis =f(I e I r )=f(I r ,I e,eng ,I e,comp ,I e,otr ,I e,pump1 ,I e,pump2 ,Iblower ,I fan )

[0031] =f(I r ,P eng ,P comp ,P otr ,P pump1 ,P pump2 ,P blower ,P fan )

[0032] =((P) eng +P comp +P otr,high ) / U high +(P pump1 +P pump2 +P blower +P fan ) / U low ) / I r ;

[0033] T bat =f(C dis Q chiller ,T ambient )=k1*C dis -k2*Q chiller -k3*T ambient ;

[0034] In the formula, I e This refers to the actual output current of the battery; I r The battery's rated 1C discharge current; I e，eng I represents the actual current of the motor. e，comp I represents the actual current of the compressor. e，otr For the current of other components; I e，pump1 I represents the actual current of the first electronic water pump. e，pump2 I represents the actual current of the second electronic water pump. blower I represents the actual current of the indoor fan. fan P represents the outdoor fan current. eng P represents the actual power of the motor. comp P represents the actual power of the compressor. pump1 P represents the actual power of the first electronic water pump. pump2 P represents the actual power of the second electronic water pump. blower P represents the actual power of the indoor fan. fan P represents the outdoor fan power. otr Power for other components; U high For high-voltage electrical systems; U low For low-voltage electrical systems; T ambien The actual ambient temperature; k1, k2, and k3 are specific proportionality coefficients, with k1 being the ratio of temperature to ambient temperature.dis The relevant parameters for battery internal resistance are: k2 is the energy loss in the battery water circuit, and k3 is the parameter related to the convective heat transfer coefficient between the battery and the air.

[0035] The relationship between single discharge capacity and battery temperature and discharge rate is as follows:

[0036] Q dis，e =f(C dis T bat Q dis，r )=Q dis，r *(1-k4 / e^T bat –k5*(e^(C dis -1));

[0037] In the formula, k4 and k5 represent the battery temperature T, respectively. bat The effect of discharge rate on the single discharge capacity Q of C-cell batteries dis，e The extent of the impact.

[0038] A further improvement of the control method of the present invention lies in the step of using a CO2 compressor, a first electronic expansion valve, and an indoor fan to regulate the heat exchange of the indoor heat exchanger. This portion of energy serves as the main cooling or heating energy source for the passenger compartment, used to regulate the temperature and temperature field of the passenger compartment and maintain the thermal comfort of passengers in the passenger compartment.

[0039] The motor's dynamic cooling effect (M) is defined by the inlet water temperature, outlet water temperature, water flow rate, and motor temperature in the motor's water circuit. eng The supply air temperature, return air temperature, and air volume of the HVAC system define the comfort evaluation index M for the passenger cabin. cabin , respectively represented as,

[0040] M eng =l1(T w,out -T w,in )*q w / T eng ;

[0041] M cabin =l2(T a,back -T a,in )*q HVAC / T ambient ;

[0042] In the formula, l1 and l2 are correction coefficients; T w,in T represents the inlet water temperature of the motor's water circuit. w,out q represents the return water temperature of the motor's water circuit. w T represents the water flow rate in the motor's water circuit. eng T represents the motor temperature. a,in T is the supply air temperature for HVAC systems.a,back q represents the return air temperature of an HVAC (Heating, Ventilation, and Air Conditioning) system. HVAC For the air volume of HVAC (Heating, Ventilation, and Air Conditioning), T ambien This refers to the actual ambient temperature.

[0043] Specifically, as the motor torque demand increases, the value of l1 decreases; as solar radiation intensifies, the value of l2 decreases; and when comfort demands increase, the value of M increases. cabin Value; when the demand for motor power performance increases, increase M. eng Value; by increasing the inlet and outlet water temperature difference and water flow rate in the motor water circuit, the M value, which is used as an evaluation indicator for motor thermal management, is improved. eng Value; by increasing the supply and return air temperature difference and air volume of HVAC systems, the M value, which is an evaluation indicator for the passenger cabin, can be improved. cabin Values; wherein, the water flow rate is controlled by adjusting the second electronic water pump, the air volume is controlled by adjusting the indoor fan, the inlet water temperature is controlled by adjusting the speed of the outdoor fan, and the air supply temperature is controlled by adjusting the speed of the CO2 compressor and the opening of the first electronic expansion valve.

[0044] A further improvement to the control method of the present invention lies in that,

[0045] Define the global evaluation index M global , is represented as ,

[0046] M global =m1*M bat +m2*M eng +m3*M cabin ;

[0047] In the formula, m1, m2, and m3 are the battery weight, motor weight, and cabin weight, respectively, m1 + m3 + m2 = 100%, and m1, m2, and m3 < 100%.

[0048] M global State description value M global,state and mechanical description value M global,machine , respectively represented as,

[0049] M global,state =f(C dis Q chiller ,T ambient ,T w,out ,T w,in ,q w ,T eng ,T a,back ,T a,in ,q HVAC ,T ambient );

[0050] M global,machine =f(Pcomp ,P pump1 ,P pump2 ,P fan ,P blower D vavle1 D vavle2 ).

[0051] A further improvement to the control method of the present invention lies in that the global evaluation index M... global middle,

[0052] When the ambient temperature is within the preset temperature range that meets the harsh working conditions, m1>m3>m2;

[0053] When the solar radiation intensity is greater than the preset radiation intensity threshold, m3>m1>m2;

[0054] When the motor torque is greater than the preset torque threshold, m2>m3>m1;

[0055] When the vehicle speed is greater than the preset speed threshold, m3>m1>m2.

[0056] A further improvement of the control method of the present invention lies in that, during the control process, each state value is a feedback quantity, each mechanical value is a control quantity, and each mechanical structure is an actuator; M is calculated based on the mechanical description values. globa The gradient is calculated, and the system's independent variables are increased along the gradient direction until the system gradient is 0, thus finding M. global The optimal control result is obtained by finding the maximum value within the defined domain.

[0057] A further improvement of the control method of the present invention is that, during the control process of the control method, the exhaust pressure of the system is jointly regulated by adjusting the opening degree of the first electronic expansion valve and the second electronic expansion valve;

[0058] Where, when M global When optimal, the best exhaust pressure P is obtained. dis，bestopel , is represented as ,

[0059] P dis,bestopel =f(T) ambient C dis M global )*P dis,optimal =(n1*T ambient +n2*C dis +n3*M global )*P dis,optimal ;

[0060] In the formula, n1, n2, and n3 are fitting correction coefficients; P dis,optimal This is the optimal exhaust pressure.

[0061] Compared with the prior art, the present invention has the following beneficial effects:

[0062] In the technical solution provided by this invention, the following heat exchange process is involved in both cooling and heating modes: the battery cooler exchanges heat with the coolant through a first electronic water pump, and then the coolant exchanges heat with the lithium-ion battery through the first electronic water pump, achieving battery thermal management; the indoor heat exchanger exchanges heat with the air through an indoor fan, and then sends the heated air into the passenger compartment, achieving passenger compartment thermal management; the refrigerant CO2 in the outdoor heat exchanger exchanges heat with the outdoor air through an outdoor fan, and the coolant in the front-end water radiator exchanges heat with the outdoor air through an outdoor fan, and then the coolant exchanges heat with the motor through a second electronic water pump, thereby achieving motor thermal management. The technical solution provided by this invention comprehensively considers the different needs of the battery, motor, and passenger compartment, and combines the characteristics of the transcritical CO2 cycle for integrated control, which can comprehensively improve the overall performance of new energy vehicles.

[0063] The technical solution disclosed in this invention optimizes the energy flow of the entire vehicle based on transcritical CO2 thermal management technology, taking into account the different needs of the battery, motor, and passenger compartment, and combining the characteristics of the transcritical CO2 cycle for comprehensive control. Given that the overall performance of new energy vehicles is constrained by multiple complex factors, this invention proposes an optimized energy flow control method based on a transcritical CO2 thermal management system. It accurately defines and evaluates the energy flow allocation needs of the battery, motor, and passenger compartment, proposes a comprehensive evaluation algorithm to assess the energy needs of the three modules, and further combines the transcritical CO2 thermal management system to provide a control scheme for its exhaust pressure, comprehensively improving the overall vehicle performance.

[0064] This invention proposes a more refined battery thermal management strategy. Specifically, existing methods do not consider the contradiction between thermal management requirements and the consumption required to achieve the corresponding thermal management goals. This invention proposes the maximum marginal benefit point of battery thermal management, which can exchange the minimum battery capacity consumption for the maximum improvement of battery single discharge efficiency, thereby improving the overall vehicle range.

[0065] This invention proposes a comprehensive evaluation index to coordinate the energy flow allocation of battery capacity characteristics, motor power characteristics, and passenger cabin thermal comfort. It uses a gradient optimization method to optimize the vehicle thermal management evaluation index, thereby comprehensively improving the driving range and passenger comfort of new energy vehicles.

[0066] This invention proposes an optimal exhaust pressure, which is an exhaust pressure optimized based on the vehicle energy flow evaluation index, enabling the system to move from steady-state optimality to dynamic global optimality.

[0067] In summary, this invention comprehensively considers multiple indicators, proposes vehicle energy flow evaluation indicators with different weights, and classifies and controls them according to different operating conditions. While maintaining the aforementioned control logic, the vehicle evaluation indicators are optimized, and the optimal control path for vehicle evaluation is found through a gradient descent method, achieving optimized vehicle control via the fastest path. During the optimization process, the concept of optimal exhaust pressure is proposed, prioritizing the vehicle energy flow evaluation indicators as the highest-priority parameter. This breaks through the limitations of the optimal exhaust pressure in traditional transcritical CO2 thermal management systems, ensuring dynamic global optimization rather than the lowest steady-state energy consumption. Furthermore, the relationship between the optimal exhaust pressure and the optimal execution exhaust pressure of the transcritical carbon dioxide thermal management system is fitted, and the optimal exhaust pressure is obtained through empirical correlation, thus yielding the optimal execution exhaust pressure. Attached Figure Description

[0068] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art are briefly introduced below; obviously, the drawings described below are some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0069] Figure 1 This is a schematic diagram of the heating mode of an energy flow system based on transcritical CO2 thermal management in an embodiment of the present invention;

[0070] Figure 2 This is a schematic diagram of the cooling mode of an energy flow system based on transcritical CO2 thermal management in an embodiment of the present invention;

[0071] Figure 3 This is a schematic diagram of the vehicle evaluation index optimization logic of an energy flow system based on transcritical CO2 thermal management in an embodiment of the present invention;

[0072] Explanation of the reference numerals in the figure:

[0073] 1. Lithium-ion battery; 2. Motor; 3. Passenger compartment; 4. CO2 compressor; 5. Outdoor heat exchanger; 6. Front-end water radiator; 7. Indoor heat exchanger; 8. Battery cooler; 9. Four-way reversing valve; 10. Regenerator; 11. First electronic expansion valve; 12. Second electronic expansion valve; 13. First electronic water pump; 14. Second electronic water pump; 15. Indoor fan; 16. Outdoor fan; 17. Gas-liquid separator. Detailed Implementation

[0074] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. 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 should fall within the scope of protection of the present invention.

[0075] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0076] Please see Figure 1 and Figure 2 This invention provides an electric vehicle energy flow system based on transcritical CO2 thermal management, comprising: a lithium-ion battery 1, a motor 2, a CO2 compressor 4, an outdoor heat exchanger 5, a front-end water radiator 6, an indoor heat exchanger 7, a battery cooler 8, a four-way reversing valve 9, a regenerator 10, a first electronic expansion valve 11, a second electronic expansion valve 12, a first electronic water pump 13, a second electronic water pump 14, an indoor fan 15, an outdoor fan 16, and a gas-liquid separator 17; wherein,

[0077] The coolant outlet of the lithium-ion battery 1 is connected to the coolant inlet of the lithium-ion battery 1 via the second heat exchange channel of the battery cooler 8 and the first electronic water pump 13; wherein, a first water tank may be installed in the circulation pipeline.

[0078] The indoor fan 15 is used to ventilate the passenger compartment 3 through the second heat exchange channel of the indoor heat exchanger 7;

[0079] The second heat exchange channel of the outdoor heat exchanger 5 is connected to the first heat exchange channel of the front water radiator 6, and the outdoor fan 16 is used to ventilate the first heat exchange channel of the front water radiator 6 through the second heat exchange channel of the outdoor heat exchanger 5.

[0080] The coolant outlet of the motor 2 is connected to the coolant inlet of the motor 2 via the second heat exchange channel of the front-end water radiator 6 and the second electronic water pump 14; wherein a second water tank may be installed in the circulation pipeline;

[0081] like Figure 1 As shown, in heating mode, the outlet of the CO2 compressor 4 is connected to port a of the four-way reversing valve 9, and port a of the four-way reversing valve 9 is connected to port b of the four-way reversing valve 9. Port b of the four-way reversing valve 9 is divided into two paths: one path is connected to the inlet of the first electronic expansion valve 11 through the first heat exchange channel of the indoor heat exchanger 7, and the other path is connected to the inlet of the second electronic expansion valve 12 through the first heat exchange channel of the battery cooler 8. The outlets of the first electronic expansion valve 11 and the second electronic expansion valve 12 merge and are then connected to port c of the four-way reversing valve 9 through the first heat exchange channel of the regenerator 10 and the first heat exchange channel of the outdoor heat exchanger 5. Port c of the four-way reversing valve 9 is connected to port d of the four-way reversing valve 9. Port d of the four-way reversing valve 9 is connected to the inlet of the CO2 compressor 4 through the gas-liquid separator 17 and the second heat exchange channel of the regenerator 10, forming a cycle.

[0082] like Figure 2 As shown, in the cooling mode, the outlet of CO2 compressor 4 is connected to port a of four-way reversing valve 9, and port a of four-way reversing valve 9 is connected to port c of four-way reversing valve 9. Port c of four-way reversing valve 9 is divided into two paths after passing through the first heat exchange channel of outdoor heat exchanger 5 and the first heat exchange channel of regenerator 10. One path is connected to port b of four-way reversing valve 9 through the first electronic expansion valve 11 and the first heat exchange channel of indoor heat exchanger 7. The other path is connected to port b of four-way reversing valve 9 through the second electronic expansion valve 12 and the first heat exchange channel of battery cooler 8. Port b of four-way reversing valve 9 is connected to port d of four-way reversing valve 9. Port d of four-way reversing valve 9 is connected to the inlet of CO2 compressor 4 through gas-liquid separator 17 and the second heat exchange channel of regenerator 10, forming a cycle.

[0083] In the technical solution provided by the embodiments of the present invention, the following heat exchange process is carried out in both cooling and heating modes: the battery cooler exchanges heat with the coolant through the first electronic water pump, and then the coolant and lithium-ion battery exchange heat through the first electronic water pump to achieve battery thermal management; the indoor heat exchanger exchanges heat with the air through the indoor fan, and sends the heat-exchanged air into the passenger compartment to achieve passenger compartment thermal management; the refrigerant CO2 in the outdoor heat exchanger exchanges heat with the outdoor air through the outdoor fan, the coolant in the front water radiator exchanges heat with the outdoor air through the outdoor fan, and the coolant and motor exchange heat through the second electronic water pump to achieve motor thermal management.

[0084] The optimized control method provided in this embodiment of the invention involves controlled components including: a CO2 compressor, a first electronic expansion valve, a second electronic expansion valve, a first electronic water pump, a second electronic water pump, an indoor fan, and an outdoor fan; wherein the formed control logic includes:

[0085] (1) The total cooling and heating demand is controlled by the speed of the CO2 compressor; the main difference is reflected in the change of heat exchange in the indoor heat exchanger and the battery cooler. The higher the compressor speed, the greater the sum of heat exchange in the indoor heat exchanger and the battery cooler.

[0086] (2) The outdoor fan works in conjunction with the CO2 compressor. When the compressor speed increases, the heat exchange of the outdoor fan also increases accordingly. At the same time, the outdoor fan speed is related to the vehicle speed. When the vehicle speed is high, the outdoor fan speed will be appropriately reduced; when the vehicle speed is low, the outdoor fan needs more power to increase the speed.

[0087] (3) The heat exchange capacity of the indoor heat exchanger is controlled by the first electronic expansion valve; wherein, when the heat exchange demand of the indoor passenger compartment is large, the first electronic expansion valve is opened wide, and when the heat exchange demand of the indoor passenger compartment is small, the first electronic expansion valve is closed.

[0088] (4) The indoor air supply temperature is controlled by the indoor fan; when the required air supply temperature is significantly different from the ambient temperature, the indoor fan is turned down; when the required air supply temperature is not significantly different from the ambient temperature, the indoor fan is turned up.

[0089] (5) The heat exchange of the battery cooler is controlled by the second electronic expansion valve; when the demand for battery heat exchange is large, the second electronic expansion valve is opened wide, and when the demand for battery heat exchange is small, the second electronic expansion valve is closed.

[0090] (6) The temperature and flow rate of the battery cooling water are controlled by the first electronic water pump; wherein, when the battery cooling requires a larger water flow rate, the first electronic water pump is turned up, and when the battery cooling requires a lower cooling temperature, the first electronic water pump is turned down.

[0091] (7) The flow rate of cooling water for the motor is controlled by the second electronic water pump; wherein, when the motor requires a large amount of cooling, the second electronic water pump is turned up, and when the motor requires less cooling, the first electronic water pump is turned down.

[0092] In the technical solution provided by this invention, the optimization control objectives of the optimized control method include: lithium-ion battery discharge rate, lithium-ion battery temperature, motor temperature, motor torque, passenger compartment comfort, and the COP (Coefficiency of Performance) energy efficiency ratio of the vehicle thermal management system; among which, the following optimized control methods are provided for the energy flow of new energy vehicles:

[0093] The heat exchange in the battery cooler is regulated by a CO2 compressor, a second electronic expansion valve, and a first electronic water pump. This energy serves as the main source of cooling or heating energy for the battery. At the same time, the self-generated heat from different battery rates and the heat from natural convection between the battery and the environment are also taken into account. The heat exchange in the battery cooler is used to regulate the battery temperature and increase the battery's single discharge capacity. By balancing the power consumption of the compressor and the effect of increasing the battery's single discharge capacity, the battery thermal management efficiency is further improved.

[0094] The heat exchange capacity of the indoor heat exchanger is regulated by a CO2 compressor, a first electronic expansion valve, and an indoor fan. This energy serves as the main source of cooling or heating energy for the passenger compartment. The temperature and temperature field of the passenger compartment are regulated by the CO2 compressor, the first electronic expansion valve, and the indoor fan to maintain the thermal comfort of passengers in the passenger compartment.

[0095] The heat exchange in the front-end water radiator is regulated by a second electronic water pump and an outdoor fan. This energy serves as the main source of cooling for the motor and electronic control system. The motor temperature is regulated by the second electronic water pump and the outdoor fan to ensure the motor's power limit.

[0096] Taking into account the above multiple indicators, a vehicle energy flow evaluation index is proposed according to different weights. This index is then classified and controlled under different operating conditions. While maintaining the control logic, the vehicle evaluation index is optimized. The optimal control path for vehicle evaluation is found using a gradient descent method, achieving optimized vehicle control via the fastest path. During the optimization process, the concept of optimal exhaust pressure is proposed, prioritizing the vehicle energy flow evaluation index as the highest-priority parameter. This breaks through the limitations of the optimal exhaust pressure in traditional transcritical CO2 thermal management systems, ensuring dynamic global optimization rather than the lowest steady-state energy consumption. Furthermore, the relationship between the optimal exhaust pressure and the optimal execution exhaust pressure of the transcritical CO2 thermal management system is fitted. The optimal exhaust pressure is obtained through empirical correlation, leading to the optimal execution exhaust pressure.

[0097] In this embodiment of the invention, the effective thermal management rate M of the battery is defined. bat , is represented as ,

[0098] M bat =(Q dis，e -Q dis，r ) / Q chiller ;

[0099] In the formula, Q dis,r Q is the battery's rated discharge capacity for a single charge at the current ambient temperature. dis,e This is the rated discharge capacity of the battery under the specified temperature after implementing thermal management strategies. This capacity value is greater than the rated discharge capacity under ambient temperature without thermal management. Q chiller This refers to the amount of heat / cooling supplied to the battery by the battery cooler in the thermal management system.

[0100] Explanatoryly, using the above relationships, we perform objective optimization of the system's multivariate linear equations under its current operating state, with the optimization object being COP. bat The feasible region is the power and temperature operating range of each component, where T is the power and temperature range of each component. bat By replacing the corresponding correlation, we can obtain the result that is only related to the discharge rate C. dis The single discharge capacity is a function of the single discharge capacity, and the optimal single discharge capacity is obtained by solving the extreme points of advanced mathematics.

[0101] In this embodiment of the invention, the single discharge capacity Q and the battery temperature T of the lithium-ion battery are defined. ba Discharge rate C dis The relationship between them; among them,

[0102] First, we need to further define the discharge rate and battery temperature.

[0103] C dis =f(I e I r )=f(I r ,I e,eng ,I e,comp ,I e,otr ,I e,pump1 ,I e,pump2 ,I blower ,I fan )

[0104] =f(I r ,P eng ,P comp ,P otr ,P pump1 ,P pump2 ,P blower ,P fan )

[0105] =((P) eng +P comp +P otr,high ) / U high +(P pump1 +P pump2 +P blower +P fan ) / U low ) / I r ;

[0106] T bat =f(C dis Q chiller ,T ambient )=k1*C dis -k2*Q chiller -k3*Tambient ;

[0107] In the formula, I e This refers to the actual output current of the battery; I r The battery's rated 1C discharge current; I e，eng I represents the actual current of the motor. e，comp I represents the actual current of the compressor. e，otr For the current of other components; I e，pump1 I represents the actual current of the first electronic water pump. e，pump2 I represents the actual current of the second electronic water pump. blower I represents the actual current of the indoor fan. fan P represents the outdoor fan current. eng P represents the actual power of the motor. comp P represents the actual power of the compressor. pump1 P represents the actual power of the first electronic water pump. pump2 P represents the actual power of the second electronic water pump. blower P represents the actual power of the indoor fan. fan P represents the outdoor fan power. otr Power for other components; U high For high-voltage electrical systems; U low For low-voltage electrical systems; Q chiller The value of heat or cold energy provided to the battery by the battery cooler; T ambien The actual ambient temperature; k1, k2, and k3 are specific proportionality coefficients, which can be derived from the corresponding physical relationships. k1 is related to C. dis The relevant parameters for battery internal resistance are as follows: k2 is the energy loss in the battery water circuit, and k3 is the parameter related to the convective heat transfer coefficient between the battery and air.

[0108] The relationship between single discharge capacity and battery temperature and discharge rate is as follows:

[0109] Q dis，e =f(C dis T bat Q dis，r )=Q dis，r *(1-k4 / e^T bat –k5*(e^(C dis -1));

[0110] Among them, k4 and k5 represent the battery temperature T, respectively. bat The effect of discharge rate on the single discharge capacity Q of C-cell batteries dis，e The extent of the impact.

[0111] Explaining this, for lithium-ion batteries, both temperature changes and discharge rate affect the single-cycle discharge capacity. Capacity decay becomes less noticeable at high battery temperatures, but becomes highly sensitive to temperature variations at lower temperatures. At higher discharge rates, the single-cycle discharge capacity decreases significantly, while at lower rates, there is almost no effect on the discharge capacity.

[0112] In this embodiment of the invention, an effective thermal management rate for vehicle-mounted lithium-ion batteries is proposed. This is achieved by comprehensively analyzing battery temperature, total battery discharge current, and the heat or cooling provided by the thermal management system to obtain the current temperature of the lithium-ion battery and its usable discharge capacity at that temperature. Furthermore, by comparing the energy required by the thermal management system to achieve the current discharge capacity, the benefits and costs are compared to obtain the effective thermal management rate. This effective thermal management rate can assess the impact of thermal management on the improvement or reduction of the vehicle's driving range. Through optimized control, adjusting the CO2 compressor speed, the opening of the first electronic expansion valve and the second electronic expansion valve in the battery branch, and the speed of the first electronic water pump, the energy allocated to battery thermal management is controlled, ultimately maximizing the marginal benefit of battery thermal management. This is considered the optimal effective thermal management rate.

[0113] In this embodiment of the invention, the control scheme for passenger cabin comfort and motor thermal management uses intuitive parameters from the thermal management system, namely the inlet water temperature, return water temperature, water flow rate, and motor temperature, to define the motor's power cooling effect M. eng The supply air temperature, return air temperature, and air volume of the HVAC (Heating, Ventilation, and Air Conditioning) module are used to define the comfort evaluation index M of the passenger cabin. cabin , is represented as ,

[0114] M eng =l1(T w,out -T w,in )*q w / T eng ;

[0115] M cabin =l2(T a,back -T a,in )*q HVAC / T ambient ;

[0116] In the formula, l1 and l2 are correction coefficients fitted based on experience, which will change with road conditions, number of passengers, weather conditions and so on. The worse the road conditions, the greater the torque required, the more power the motor needs to output, and the higher the thermal management requirements, so l1 will be smaller, and vice versa. When the number of passengers in the passenger compartment is greater in summer and the solar radiation is stronger, the value of l2 will be smaller. When the number of passengers in the passenger compartment is less in winter and the solar radiation is weaker, the value of l2 will also be smaller; and vice versa.

[0117] Explanatory, M eng and M cabin The higher the value, the better the thermal management effect is considered to be, and the better it meets the requirements of motor power characteristics and passenger cabin comfort characteristics. When passengers have high comfort requirements, the value can be increased. cabin The value of M can be increased when passengers have high requirements for the motor's power performance. eng The value of the value is as follows. For the optimized control logic of the thermal management evaluation index of the passenger compartment and the motor, the thermal management evaluation index of the motor is improved by increasing the inlet and outlet water and water flow rate, and the evaluation index of the passenger compartment is improved by increasing the temperature difference between the supply and return air and increasing the air volume; the water flow rate is controlled by adjusting the second electronic water pump, and the air volume is controlled by adjusting the indoor fan; the inlet water temperature of the motor is controlled by adjusting the speed of the outdoor fan, and the supply air temperature is controlled by adjusting the speed of the compressor and the opening degree of the first electronic expansion valve in the transcritical CO2 heat pump air conditioning system.

[0118] This invention proposes evaluation indicators for passenger compartment thermal management and motor thermal management. Specifically, the magnitude of thermal management demand is determined by the motor temperature and ambient temperature under different operating conditions. The energy flow provided to the passenger compartment by the thermal management system is regulated by the CO2 compressor speed, the opening of the first electronic expansion valve, and the indoor fan speed. The energy flow provided to the motor by the thermal management system is regulated by the outdoor fan speed and the second electronic water pump speed. By comparing the supply and demand sides, evaluation indicators for passenger compartment and motor thermal management are calculated, providing a basis for judging whether the energy flow provided by the thermal management system meets the needs of the passenger compartment and motor under current demand.

[0119] In a further preferred embodiment of the present invention, a global evaluation index M for the energy flow system is defined. global , is represented as ,

[0120] M global =m1*M bat +m2*M eng +m3*M cabin ;

[0121] In the formula, m1, m2, and m3 are the battery weight, motor weight, and vehicle compartment weight, respectively. All three weights are less than 100%, and the sum of the three weight values ​​is 100% (m1 + m3 + m2 = 100%, m1, m2, m3 < 100%). The vehicle energy flow system will assign values ​​to m1, m2, and m3 according to the vehicle's driving conditions, using ambient temperature, solar radiation, road slope, and vehicle speed as important indicators for weight assignment.

[0122] The specific embodiments of the present invention are exemplary.

[0123] (1) The basic weight of the battery is 35%, the weight of the motor is 20%, and the basic weight of the cabin is 45%. The weight assignment is based on this and varies under different working conditions.

[0124] (2) When the ambient temperature deviates from the suitable temperature (20℃~25℃) n1℃, the battery weight m1 increases by 2%, the cabin weight m3 increases by 1%, and the motor weight m2 decreases by 3%.

[0125] (3) For every n² W / m² increase in solar radiation 2 At that time, the weight of the vehicle cabin increases by 2%, the weight of the battery increases by 1%, and the weight of the motor decreases by 3%.

[0126] (4) For every n3 Nm increase in motor torque, the weight of the motor increases by 1.5%, the weight of the battery increases by 0.5%, and the weight of the vehicle compartment decreases by 2%.

[0127] (5) For every n4 km / h increase in vehicle speed, the battery weight increases by 0.5%, the motor weight increases by 0.5%, and the cabin weight decreases by 1%.

[0128] Among them, n1, n2, n3, and n4 are specific values ​​that can be obtained through a limited number of experiments or set based on engineering experience;

[0129] As a further example, for the above evaluation method, the assignment situations can be classified as follows:

[0130] (1) Working conditions with extremely harsh ambient temperatures: m1>m3>m2;

[0131] (2) Under conditions of strong solar radiation: m3>m1>m2;

[0132] (3) Operating conditions with very high motor torque: m2>m3>m1;

[0133] (4) Operating conditions with very high vehicle speeds: m3>m1>m2;

[0134] Based on this classification and specific assignment method, M under different working conditions global Further control optimization and synthesis can yield M. globalThe state description value and mechanical description value are represented as follows:

[0135] M global,state =f(C dis Q chiller ,T ambient ,T w,out ,T w,in ,q w ,T eng ,T a,back ,T a,in ,q HVAC ,T ambient );

[0136] M global,machine =f(P comp ,P pump1 ,P pump2 ,P fan ,P blower D vavle1 D vavle2 );

[0137] Please see Figure 3 During the control process, various state values ​​are feedback quantities, various mechanical values ​​are control quantities, and various mechanical structures are actuators. M is calculated based on the mechanical description values. globa The gradient is calculated, and the system's independent variables are increased along the gradient direction until the system gradient is 0, thus finding M. global The maximum value within the defined domain is the optimal control result. The specific steps of this solution process are as follows:

[0138] (1) Given initial values ​​for compressor speed, first electronic water pump speed, second electronic water pump speed, outdoor fan speed, indoor fan speed, first electronic expansion valve opening, and second electronic expansion valve opening; for example, these initial values ​​can be defined as N respectively. 1,0 N 2,0 N 3,0 N 4,0 N 5,0 N 6,0 N 7,0 These values ​​operate within a given range (N). 1,min N 1,max ),(N 2,min N 2,max ),(N 3,min N 3,max (N) 4,min N 4,max ),(N 5,min N 5,max ),(N 6,min N 6,max ),(N 7,min N7,max );

[0139] (2) Calculate M global Given the gradient G0 at the initial value, increase the initial value along the gradient direction. Taking the compressor as a reference, increase the compressor's maximum speed by 10%, and increase the other parameters proportionally to the maximum value according to the gradient value, thus obtaining N. 1,1 N 2,1 N 3,1 N 4,1 N 5,1 N 6,1 N 7,1 ;

[0140] (3) Repeat step (2) until the gradient value G is reached. i When the value is less than 1 for the first time, the reference value is changed, and the compressor speed change step size is changed to 1% of the maximum speed to obtain a new N value, which gradually approaches M. global The global optimum;

[0141] (4) Repeat step (3) until the gradient value G is reached. i When the value is less than 0.1 for the first time, the reference value is changed, and the compressor speed change step size is changed to 0.1% of the maximum speed to obtain a new N value, which gradually approaches M. global The global optimum;

[0142] (5) Repeat the steps in (4) until the gradient value G i If the value is less than 0.01, then M is considered to have been obtained. global The global optimal value is obtained, and each executing mechanism takes the current value of N as the final value.

[0143] In this embodiment of the invention, a comprehensive global evaluation index integrating battery, passenger compartment, and motor thermal management is proposed. By assigning different weight values ​​under different operating conditions using specific weight coefficients, the importance of the three thermal management objects is adjusted to obtain the most suitable thermal management target for the current operating condition. Furthermore, after obtaining the global evaluation index, a gradient calculation method can be used to solve for the maximum gradient of all actuators in the energy flow system: compressor, electronic expansion valve, water pump, fan, and blower. By continuously obtaining the maximum gradient and changing the input of the actuators, the optimal value for the system's global evaluation index is found, achieving optimized control.

[0144] In the optimization process of this invention embodiment, the exhaust pressure of the transcritical CO2 thermal management system can be jointly controlled by adjusting the opening degrees of the first electronic expansion valve and the second electronic expansion valve; wherein, when M globalIn the optimal state, the system exhaust pressure at this point is defined as the optimal exhaust pressure. This concept is different from the optimal exhaust pressure of the traditional transcritical CO2 thermal management system. The traditional optimal exhaust pressure only considers the COP of the thermal management system and ignores the optimization of the energy flow distribution of the whole vehicle. Therefore, the optimal exhaust pressure is more instructive for the optimization control of the energy flow of new energy vehicles.

[0145] The optimal execution pressure P proposed in this invention dis,bestopel This is related to the optimal exhaust pressure of the transcritical CO2 thermal management system, and the optimal operating pressure can be defined as follows:

[0146] P dis,bestopel =f(T) ambient C dis M global )*P dis,optimal =(n1*T ambient +n2*C dis +n3*M global )*P dis,optimal ;

[0147] In the formula, n1, n2, and n3 are fitting correction coefficients; P dis,optimal This is the optimal exhaust method.

[0148] This invention proposes the concept of optimal execution exhaust pressure, which is based on a global evaluation index and represents the exhaust pressure that optimizes the global evaluation index. Unlike the traditional optimal exhaust pressure for transcritical carbon dioxide, which only focuses on system performance, the optimal execution exhaust pressure comprehensively considers the optimization of the entire energy flow system, ensuring that the entire system is in an optimal state under this evaluation index. Furthermore, this invention proposes a relationship between the optimal execution exhaust pressure and the traditional optimal exhaust pressure. The optimal execution exhaust pressure can be calculated from the system's optimal exhaust pressure, achieving a unification of system optimization and global optimization. Consequently, some empirical formulas used in the traditional optimal exhaust pressure can also be indirectly applied to the calculation of the optimal execution exhaust pressure, effectively improving the application efficiency of the optimal exhaust pressure.

[0149] In summary, this invention provides an energy flow optimization control method for new energy vehicles. Using a transcritical CO2 thermal management system as the hub, it optimizes and controls the energy flow characteristics of the main energy flow components of new energy vehicles: lithium-ion batteries, motors, compressors, indoor fans, outdoor fans, and other energy flow components: high-voltage electrical equipment and low-voltage electrical equipment.

[0150] (1) Taking into account the low temperature characteristics and rate characteristics of lithium-ion batteries, the most efficient thermal management logic is provided for lithium-ion batteries by coordinating the entire energy flow equipment of new energy vehicles.

[0151] (2) The effective thermal management rate of the battery is proposed to describe the ratio of the energy release capacity increased by the battery when it operates at a suitable temperature due to thermal management to the energy consumed by thermal management, so as to guide the comprehensive thermal management strategy.

[0152] (3) Starting from the transcritical CO2 thermal management system, based on its inlet and outlet water temperature, supply and return air temperature, water flow rate and air volume, a comprehensive evaluation index for motor power characteristics and passenger cabin comfort characteristics is proposed.

[0153] (4) Based on three indicators—motor power performance, passenger cabin comfort, and battery effective thermal management rate—a performance evaluation function for vehicle energy flow management is proposed with different weights. By solving the maximum gradient value of the function, the optimal power consumption and energy distribution scheme of the motor, compressor, fan, and water pump are obtained.

[0154] (5) Based on the characteristics of the transcritical CO2 thermal management system, under the premise that the energy demand layer is met, the optimal execution pressure suitable for the system to work is found. Under this exhaust pressure, the performance evaluation index of the entire new energy vehicle mentioned in (4) is the highest.

[0155] (6) By mathematically relating the exhaust pressure to the optimal exhaust pressure of the transcritical CO2 heat pump air conditioning system itself, the optimal exhaust pressure of the entire new energy vehicle energy flow system can be indirectly obtained by solving the optimal exhaust pressure of the transcritical CO2 heat pump air conditioning system alone, thereby achieving the optimization of the entire system.

[0156] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0157] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0158] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0159] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0160] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A control method for an energy flow system based on transcritical CO2 thermal management, characterized in that, The energy flow system based on transcritical CO2 thermal management includes: a lithium-ion battery (1), a motor (2), a CO2 compressor (4), an outdoor heat exchanger (5), a front-end water radiator (6), an indoor heat exchanger (7), a battery cooler (8), a four-way reversing valve (9), a regenerator (10), a first electronic expansion valve (11), a second electronic expansion valve (12), a first electronic water pump (13), a second electronic water pump (14), an indoor fan (15), an outdoor fan (16), and a gas-liquid separator (17); wherein, The coolant outlet of the lithium-ion battery (1) is connected to the coolant inlet of the lithium-ion battery (1) via the second heat exchange channel of the battery cooler (8) and the first electronic water pump (13); the coolant outlet of the motor (2) is connected to the coolant inlet of the motor (2) via the second heat exchange channel of the front water radiator (6) and the second electronic water pump (14); the indoor fan (15) is used to ventilate the passenger compartment through the second heat exchange channel of the indoor heat exchanger (7); the second heat exchange channel of the outdoor heat exchanger (5) is connected to the first heat exchange channel of the front water radiator (6), and the outdoor fan (16) is used to ventilate the first heat exchange channel of the front water radiator (6) through the second heat exchange channel of the outdoor heat exchanger (5); the CO2 compressor (4) The outlet of the four-way reversing valve (9) is connected to port a of the four-way reversing valve (9); port b of the four-way reversing valve (9) is divided into two paths, one path is connected to the inlet of the first electronic expansion valve (11) through the first heat exchange channel of the indoor heat exchanger (7), and the other path is connected to the inlet of the second electronic expansion valve (12) through the first heat exchange channel of the battery cooler (8); the outlet of the first electronic expansion valve (11) and the outlet of the second electronic expansion valve (12) merge and are connected to port c of the four-way reversing valve (9) through the first heat exchange channel of the regenerator (10) and the first heat exchange channel of the outdoor heat exchanger (5); port d of the four-way reversing valve (9) is connected to the inlet of the CO2 compressor (4) through the gas-liquid separator (17) and the second heat exchange channel of the regenerator (10); In the energy flow system based on transcritical CO2 thermal management, in heating mode, port a of the four-way reversing valve (9) is connected to port b, and port c of the four-way reversing valve (9) is connected to port d; in cooling mode, port a of the four-way reversing valve (9) is connected to port c, and port b of the four-way reversing valve (9) is connected to port d. The control method proposes battery energy flow management evaluation index, passenger cabin energy flow management evaluation index, and motor energy flow management evaluation index. The functional relationship between the three indexes and the power consumption, component information and environmental information of each actuator is obtained through mathematical fitting. The maximum gradient optimization method is used to dynamically optimize the system to achieve path optimization. In the control method, the proposed evaluation index is used as the judgment standard, so that the exhaust pressure with the optimal evaluation index is the optimal execution exhaust pressure.

2. The control method according to claim 1, characterized in that, In the control method described above The total cooling and heating demand is controlled by the rotational speed of the CO2 compressor; wherein, as the rotational speed of the CO2 compressor increases, the sum of the heat exchange of the indoor heat exchanger and the battery cooler increases; as the rotational speed of the CO2 compressor increases, the heat exchange of the outdoor fan increases; the rotational speed of the outdoor fan decreases as the vehicle speed increases and increases as the vehicle speed decreases. The indoor air supply temperature is controlled by the indoor fan; wherein, as the difference between the required air supply temperature and the ambient temperature decreases, the air supply volume of the indoor fan increases. The heat exchange capacity of the indoor heat exchanger is controlled by the first electronic expansion valve; wherein, as the heat exchange demand of the passenger compartment increases, the opening degree of the first electronic expansion valve increases; as the heat exchange demand of the passenger compartment decreases, the opening degree of the first electronic expansion valve decreases. The heat exchange of the battery cooler is controlled by the second electronic expansion valve; wherein, as the demand for battery heat exchange increases, the opening of the second electronic expansion valve increases; as the demand for battery heat exchange decreases, the opening of the second electronic expansion valve decreases. The first electronic water pump controls the flow rate of battery cooling water, and the second electronic water pump controls the flow rate of motor cooling water.

3. The control method according to claim 2, characterized in that, The optimization control objectives of the control method include: lithium-ion battery discharge rate, lithium-ion battery temperature, motor temperature, motor torque, passenger compartment comfort, and the COP energy efficiency ratio of the vehicle thermal management system; among which... The heat exchange in the battery cooler is regulated by a CO2 compressor, a second electronic expansion valve, and a first electronic water pump. This energy serves as the main source of cooling or heating for the battery. At the same time, the self-generated heat from different battery rates and the heat from natural convection between the battery and the environment are also taken into account. The heat exchange in the battery cooler is used to regulate the battery temperature and improve the battery's single discharge capacity. By balancing the power consumption of the compressor and the improvement effect of the battery's single discharge capacity, the battery's thermal management efficiency is improved. The heat exchange capacity of the indoor heat exchanger is regulated by a CO2 compressor, a first electronic expansion valve, and an indoor fan. This energy serves as the main source of cooling or heating energy for the passenger cabin, used to regulate the temperature and temperature field of the passenger cabin and maintain the thermal comfort of passengers in the passenger cabin. The second electronic water pump and outdoor fan are used to regulate the heat exchange in the front-end water radiator. This energy serves as the main source of cooling for the motor and electronic control system, regulating the motor temperature and ensuring the motor's power limit.

4. The control method according to claim 3, characterized in that, The process involves using a CO2 compressor, a second electronic expansion valve, and a first electronic water pump to regulate the heat exchange in the battery cooler. This energy serves as the primary source of cooling or heating for the battery. Simultaneously, it considers the self-generated heat from different battery rates and the heat transferred through natural convection between the battery and the environment. The heat exchange in the battery cooler is used to regulate the battery temperature, thereby increasing the battery's single-cycle discharge capacity. This step improves battery thermal management efficiency by balancing compressor power consumption and the increase in single-cycle discharge capacity. Define the effective thermal management rate M of the battery bat , is represented as , M bat =(Q dis，e -Q dis，r ) / Q chiller ; In the formula, Q dis,r Q is the battery's rated discharge capacity for a single charge at the current ambient temperature; dis,e This is the rated discharge capacity of the battery under the specified temperature after implementing thermal management strategies. The capacity value is greater than the rated discharge capacity under ambient temperature without thermal management. Q chiller This refers to the amount of heat or cold supplied to the battery by the battery cooler in the system. Using the functional relationship of battery effective thermal management efficiency, we perform objective optimization of a system of multiple linear equations under the current operating state, with COP as the optimization object. bat The feasible region is the power and temperature operating range of each component, yielding results only with respect to the discharge rate C. dis The single discharge capacity is a function of the single discharge capacity, and the optimal single discharge capacity is obtained by solving the extreme points of advanced mathematics. in, Define the single-cycle discharge capacity Q and battery temperature T of a lithium-ion battery. ba Discharge rate C dis The relationship between them; among them, The definitions of discharge rate and battery temperature are as follows: C dis =f(I e ,I r )=f(I r ,I e,eng ,I e,comp ,I e,otr ,I e,pump1 ,I e,pump2 ,I blower ,I fan ) =f(I r ,P eng ,P comp ,P otr ,P pump1 ,P pump2 ,P blower ,P fan ) =((P eng +P comp +P otr,high ) / U high +(P pump1 +P pump2 +P blower +P fan ) / U low ) / I r ; T bat =f(C dis ,Q chiller ,T ambient )=k1*C dis -k2*Q chiller -k3*T ambient ; In the formula, I e This refers to the actual output current of the battery; I r The battery's rated 1C discharge current; I e，eng I represents the actual current of the motor. e，comp I represents the actual current of the compressor. e，otr For the current of other components; I e，pump1 I represents the actual current of the first electronic water pump. e，pump2 I represents the actual current of the second electronic water pump. blower I represents the actual current of the indoor fan. fan P represents the outdoor fan current. eng P represents the actual power of the motor. comp P represents the actual power of the compressor. pump1 P represents the actual power of the first electronic water pump. pump2 P represents the actual power of the second electronic water pump. blower P represents the actual power of the indoor fan. fan P represents the outdoor fan power. otr Power for other components; U high For high-voltage electrical systems; U low For low-voltage electrical systems; T ambien The actual ambient temperature; k1, k2, and k3 are specific proportionality coefficients, with k1 being the ratio of temperature to ambient temperature. dis The relevant parameters for battery internal resistance are: k2 is the energy loss in the battery water circuit, and k3 is the parameter related to the convective heat transfer coefficient between the battery and the air. The relationship between single discharge capacity and battery temperature and discharge rate is as follows: Q dis，e =f(C dis ,T bat ,Q dis，r )=Q dis，r *(1-k4 / e^T bat –k5*(e^(C dis -1)); In the formula, k4 and k5 represent the battery temperature T, respectively. bat The effect of discharge rate on the single discharge capacity Q of C-cell batteries dis，e The extent of the impact.

5. The control method according to claim 4, characterized in that, The step of using a CO2 compressor, a first electronic expansion valve, and an indoor fan to regulate the heat exchange of the indoor heat exchanger, with this energy serving as the main cooling or heating energy source for the passenger compartment, is used to regulate the temperature and temperature field of the passenger compartment and maintain the thermal comfort of the passengers. The motor's dynamic cooling effect (M) is defined by the inlet water temperature, outlet water temperature, water flow rate, and motor temperature in the motor's water circuit. eng The supply air temperature, return air temperature, and air volume of the HVAC system define the comfort evaluation index M for the passenger cabin. cabin , respectively represented as, M eng =l1(T w,out -T w,in )*q w / T eng ; M cabin =l2(T a,back -T a,in )*q HVAC / T ambient ; In the formula, l1 and l2 are correction coefficients; T w,in T represents the inlet water temperature of the motor's water circuit. w,out q represents the return water temperature of the motor's water circuit. w T represents the water flow rate in the motor's water circuit. eng T represents the motor temperature. a,in T is the supply air temperature for HVAC systems. a,back q represents the return air temperature of an HVAC (Heating, Ventilation, and Air Conditioning) system. HVAC For the air volume of HVAC (Heating, Ventilation, and Air Conditioning), T ambien This refers to the actual ambient temperature. Specifically, as the motor torque demand increases, the value of l1 decreases; as solar radiation intensifies, the value of l2 decreases; and when comfort demands increase, the value of M increases. cabin Value; when the demand for motor power performance increases, increase M. eng Value; by increasing the inlet and outlet water temperature difference and water flow rate in the motor water circuit, the M value, which is used as an evaluation indicator for motor thermal management, is improved. eng Value; by increasing the supply and return air temperature difference and air volume of HVAC systems, the M value, which is an evaluation indicator for the passenger cabin, can be improved. cabin Values; wherein, the water flow rate is controlled by adjusting the second electronic water pump, the air volume is controlled by adjusting the indoor fan, the inlet water temperature is controlled by adjusting the speed of the outdoor fan, and the air supply temperature is controlled by adjusting the speed of the CO2 compressor and the opening of the first electronic expansion valve.

6. The control method according to claim 5, characterized in that, Define the global evaluation index M global , is represented as , M global =m1*M bat +m2*M eng +m3*M cabin ; In the formula, m1, m2, and m3 are the battery weight, motor weight, and cabin weight, respectively, m1 + m3 + m2 = 100%, and m1, m2, and m3 < 100%. M global State description value M global,state and mechanical description value M global,machine , respectively represented as, M global,state =f(C dis ,Q chiller ,T ambient ,T w,out ,T w,in ,q w ,T eng ,T a,back ,T a,in ,q HVAC ,T ambient ); M global,machine =f(P comp ,P pump1 ,P pump2 ,P fan ,P blower ,D vavle1 ,D vavle2 )。 7. The control method according to claim 6, characterized in that, The global evaluation index M global middle, When the ambient temperature is within the preset temperature range that meets the harsh working conditions, m1>m3>m2; When the solar radiation intensity is greater than the preset radiation intensity threshold, m3>m1>m2; When the motor torque is greater than the preset torque threshold, m2>m3>m1; When the vehicle speed is greater than the preset speed threshold, m3>m1>m2.

8. The control method according to claim 6, characterized in that, In the control process of the described control method, each state value is a feedback quantity, each mechanical value is a control quantity, and each mechanical structure is an actuator; M is calculated based on the mechanical description values. global The gradient is calculated, and the system's independent variables are increased along the gradient direction until the system gradient is 0, thus finding M. global The optimal control result is obtained by finding the maximum value within the defined domain.

9. The control method according to claim 8, characterized in that, During the control process of the aforementioned control method, the exhaust pressure of the system is jointly regulated by adjusting the opening degrees of the first electronic expansion valve and the second electronic expansion valve. Where, when M global When optimal, the best exhaust pressure P is obtained. dis,bestopel , is represented as , P dis,bestopel =f(T ambient ,C dis ,M global )*P dis,optimal =(n1*T ambient +n2*C dis +n3*M global )*P dis,optimal ; In the formula, n1, n2, and n3 are fitting correction coefficients; P dis,optimal This is the optimal exhaust pressure.

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