Electronic expansion valve control method and device, battery cooling system and new energy vehicle

Abstract

The application relates to the field of new energy vehicles, and provides an electronic expansion valve control method and device, a battery cooling system and a new energy vehicle. The method comprises the following steps: predicting an optimal electronic expansion valve opening degree control sequence of a battery cooling system at a future moment based on a current battery average temperature, a current refrigerant evaporation temperature and a current electronic expansion valve opening degree of the battery cooling system at a current moment, wherein 0≤ i ≤ N -1, N represents a total number of prediction steps; correcting the optimal electronic expansion valve opening degree control sequence based on an electronic expansion valve opening degree feedforward control sequence and an electronic expansion valve opening degree feedback control sequence to obtain an electronic expansion valve opening degree output control sequence; and controlling an electronic expansion valve driver to regulate a current electronic expansion valve opening degree of an electronic expansion valve in the battery cooling system based on the electronic expansion valve opening degree output control sequence. The application can significantly improve the system response speed, can adapt to different vehicle driving conditions and environmental temperatures, and has higher control precision.

Description

Technical Field

[0001] This application relates to the field of new energy vehicles, and in particular to an electronic expansion valve control method, device, battery cooling system, and new energy vehicle. Background Technology

[0002] As the requirements for driving range and safety of new energy vehicles continue to increase, the importance of battery thermal management systems is becoming increasingly prominent. Traditional liquid cooling systems suffer from problems such as low heat exchange efficiency, system complexity, and heavy weight. Direct battery cooling technology, by directly introducing the refrigerant into the battery cooling plate, achieves efficient heat exchange and has become a research hotspot for next-generation thermal management solutions.

[0003] In direct-cooling battery systems, the electronic expansion valve (EEV) is a key actuator, and its control accuracy directly affects the stability of battery temperature and system energy efficiency. However, existing EEV control methods are usually based on superheat or fixed opening strategies, which are difficult to adapt to dynamic changes in battery thermal load and suffer from problems such as response lag and large temperature fluctuations.

[0004] Therefore, there is an urgent need to provide an EEV control method that is highly adaptable, has a fast response, and high control accuracy. Summary of the Invention

[0005] In view of this, embodiments of this application provide an electronic expansion valve control method, device, battery cooling system, and new energy vehicle to solve the problems of existing EEV control methods being unable to adapt to changes in dynamic battery thermal load, and having issues such as response lag and low control accuracy.

[0006] A first aspect of this application provides an electronic expansion valve control method, comprising:

[0007] Based on the current battery cooling system Based on the current average battery temperature, current refrigerant evaporation temperature, and current electronic expansion valve opening, predict the future battery cooling system performance. The optimal control sequence for the electronic expansion valve opening at time t, where 0 ≤ i≤N -1, N Indicates the total number of prediction steps;

[0008] Based on the current predicted battery heat load of the battery cooling system, the feedforward control sequence of the electronic expansion valve opening of the battery cooling system is determined, and based on the current average battery temperature and the target battery temperature, the feedback control sequence of the electronic expansion valve opening of the battery cooling system is determined.

[0009] The optimal control sequence for the opening of the electronic expansion valve is modified based on the feedforward control sequence and the feedback control sequence for the opening of the electronic expansion valve to obtain the output control sequence for the opening of the electronic expansion valve.

[0010] The electronic expansion valve driver in the battery cooling system is controlled by an electronic expansion valve opening output control sequence to regulate the current opening of the electronic expansion valve.

[0011] A second aspect of this application provides an electronic expansion valve control device, comprising:

[0012] The prediction module is configured to predict based on the current battery cooling system. Based on the current average battery temperature, current refrigerant evaporation temperature, and current electronic expansion valve opening, predict the future battery cooling system performance. The optimal control sequence for the electronic expansion valve opening at time t, where 0 ≤ i ≤ N -1, N Indicates the total number of prediction steps;

[0013] The first determining module is configured to determine the electronic expansion valve opening feedforward control sequence of the battery cooling system based on the current predicted value of the battery heat load of the battery cooling system, and to determine the electronic expansion valve opening feedback control sequence of the battery cooling system based on the current average battery temperature and the target battery temperature.

[0014] The correction module is configured to correct the optimal control sequence for the electronic expansion valve opening based on the feedforward control sequence and the feedback control sequence for the electronic expansion valve opening, so as to obtain the output control sequence for the electronic expansion valve opening.

[0015] The first control module is configured to control the electronic expansion valve driver to regulate the current electronic expansion valve opening in the battery cooling system based on the electronic expansion valve opening output control sequence.

[0016] A third aspect of this application provides a battery cooling system, comprising:

[0017] The controller includes an electronic expansion valve control device (a second aspect); an electronic expansion valve driver communicatively connected to the controller; an electronic expansion valve electrically connected to the electronic expansion valve driver; a first reservoir including a refrigerant outlet; a battery cooling assembly including a refrigerant inlet; an electronic expansion valve located between the refrigerant outlet and the refrigerant inlet; and the battery cooling assembly for cooling the power battery.

[0018] A fourth aspect of the embodiments of this application provides a new energy vehicle, which includes the battery cooling system of the third aspect.

[0019] Compared with the prior art, the beneficial effects of the embodiments in this application include at least the following: based on the current battery cooling system... Based on the current average battery temperature, current refrigerant evaporation temperature, and current electronic expansion valve opening, predict the future battery cooling system performance. The optimal control sequence for the electronic expansion valve opening at any given time is obtained. Then, based on the electronic expansion valve opening feedforward control sequence and the electronic expansion valve opening feedback control sequence, the optimal control sequence for the electronic expansion valve opening is corrected to obtain the electronic expansion valve opening output control sequence. Finally, based on the electronic expansion valve opening output control sequence, the electronic expansion valve driver is controlled to adjust the current electronic expansion valve opening of the electronic expansion valve in the battery cooling system. The response speed is improved by more than 30%, the temperature fluctuation range of the power battery can be controlled within ±1℃, the system COP (energy efficiency ratio) is improved by 5%~8%, and it has adaptive capability, which can be applied to different vehicle driving conditions and ambient temperatures, and the control accuracy is higher. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a system structure block diagram of a battery cooling system provided in one embodiment of this application;

[0022] Figure 2 This is a schematic diagram of the structure of a power battery provided in one embodiment of this application;

[0023] Figure 3 This is a schematic diagram of a temperature sensor being arranged on the surface of a battery module according to an embodiment of this application;

[0024] Figure 4 This is a schematic flowchart of an electronic expansion valve control method provided in an embodiment of this application;

[0025] Figure 5 This is a system structure block diagram of a battery cooling system provided in another embodiment of this application;

[0026] Figure 6 This is a schematic diagram of an electronic expansion valve control device provided in an embodiment of this application;

[0027] Figure 7 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0028] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0029] The following will describe in detail, with reference to the accompanying drawings, an electronic expansion valve control method, a device, a battery cooling system, and a new energy vehicle according to embodiments of this application.

[0030] Figure 1 This is a system structure block diagram of a battery cooling system provided in one embodiment of this application. Please refer to... Figure 1 The battery cooling system includes a controller 101, an electronic expansion valve actuator 102, an electronic expansion valve 103, a first liquid receiver 104, a condenser 105, a compressor 106, a battery cooling assembly 107, a power battery 108, and a gas-liquid separator 109. The controller 101 and the electronic expansion valve actuator 102 are communicatively connected (e.g., via a CAN (Controller Area Network) bus). The electronic expansion valve actuator 102 and the electronic expansion valve 103 are electrically connected. The compressor 106 → condenser 105 → first liquid receiver 104 → electronic expansion valve 103 → battery cooling assembly 107 → power battery 108 → gas-liquid separator 109 → compressor 106 are sequentially connected to form a refrigerant circulation cooling loop.

[0031] The first liquid reservoir 104 includes a refrigerant outlet (not shown in the figure); the battery cooling assembly 107 includes a refrigerant inlet (not shown in the figure); and the electronic expansion valve 103 is located between the refrigerant outlet and the refrigerant inlet.

[0032] The battery cooling assembly 107 also includes delivery pipes, battery cooling plates, etc.

[0033] One side of the power battery 108 is in contact with the battery cooling plate, and multiple temperature sensors (not shown in the figure) are evenly distributed on the other side.

[0034] Figure 2 This is a schematic diagram of the structure of a power battery provided in one embodiment of this application. Figure 3 This is a schematic diagram of a temperature sensor being arranged on the surface of a battery module according to an embodiment of this application.

[0035] As an example, please refer to Figure 2The power battery 108 includes multiple battery modules (e.g., battery modules 1081-1084), and each battery module includes multiple individual cells connected in series. Each individual cell can be a lithium-ion battery. Figure 3 As shown, a temperature sensor 301 can be installed at each of the four diagonal points and the center point on the side of each module away from the battery cooling plate.

[0036] Figure 4 This is a schematic flowchart of an electronic expansion valve control method provided in an embodiment of this application. Figure 4 The electronic expansion valve control method can be derived from... Figure 1 The controller 101 shown is used to execute this. The controller 101 can be either the vehicle control unit (VCU) of a new energy vehicle or the thermal management system (TMS) of a new energy vehicle.

[0037] Please see Figure 4 The electronic expansion valve control method includes the following steps:

[0038] Step S401, based on the current battery cooling system Based on the current average battery temperature, current refrigerant evaporation temperature, and current electronic expansion valve opening, predict the future battery cooling system performance. The optimal control sequence for the electronic expansion valve opening at time t, where 0 ≤ i ≤ N -1, N This indicates the total number of prediction steps.

[0039] As an example, please refer to Figures 2-3 In the current sampling period (current k (At any given moment), the current temperature can be collected by various temperature sensors deployed on the surface of each battery module of the power battery 108. The system measures the current battery temperature at each temperature detection point (one temperature detection point corresponds to one temperature sensor) at any given time, and then calculates the average value of the current battery temperature collected by all temperature sensors to obtain the battery cooling system's performance at the current time. The current average battery temperature at any given time.

[0040] For example, suppose the power battery 108 has a total of m A temperature sensor, through this m A temperature sensor collects current data. k Current battery temperature at any given moment Then, according to formula (1), the current power battery 108 is calculated. The current average battery temperature at that time.

[0041] (1);

[0042] In equation (1), Indicates the first j The current battery temperature is collected by a temperature sensor. j The value range is 1, 2, 3, ... m ; m This indicates the total number of temperature sensors installed on the surface of the power battery. This indicates that power batteries are currently... The current average battery temperature at that time.

[0043] The current refrigerant evaporation temperature refers to the current temperature at which the refrigerant evaporates. k The temperature at which the refrigerant (such as a coolant) undergoes phase change evaporation as it flows through the battery cooling components.

[0044] The current refrigerant evaporation temperature can be obtained by a temperature sensor installed in the evaporator, or by measuring the refrigerant evaporation pressure (which can be obtained by a pressure sensor installed at the evaporator's return port) and combining it with the refrigerant's saturation pressure-temperature characteristic curve (which can be obtained from the refrigerant manufacturer's manual or refrigeration engineering database) to calculate the corresponding evaporation temperature.

[0045] The current electronic expansion valve opening degree refers to the current... k The opening degree of the electronic expansion valve in the battery cooling system at all times.

[0046] The current opening degree of the electronic expansion valve can be obtained by the real-time output of the opening degree signal from the position feedback element of the electronic expansion valve itself.

[0047] As an example, the array form of the optimal control sequence for the opening of the electronic expansion valve is as follows: ,in, This indicates the opening degree of the electronic expansion valve corresponding to the first step within the total prediction time. This indicates the electronic expansion valve opening corresponding to step 2 within the total prediction time. This indicates the electronic expansion valve opening at step 3 within the total prediction time. Indicates the first [number]th ... N The corresponding electronic expansion valve opening degree.

[0048] Predict total steps N It is the number of steps (dimensionless) that extrapolate the future based on the current state of the battery cooling system.

[0049] Sampling period This refers to the time interval between two adjacent control loops, which can generally be set to 100 ms to 500 ms.

[0050] Predicted total duration This refers to predicting the system's state over a future timeframe, where... .

[0051] Furthermore, ,in, This indicates the reserved timeframe, used to anticipate the long-term effects of control actions and ensure control quality. Indicates the physical duration in the control time domain. M represents the number of control time-domain steps, the number of steps that can independently optimize the control quantity (dimensionless), which determines the "flexibility of the control action" and needs to satisfy 1 ≤ M≤N Generally, the number of time-domain steps is controlled. M It can be set to 5 to 10 steps.

[0052] For example, suppose N =6, M =5 steps =100 ms, then =100×6=600 ms, which means predicting the system state in the next 600 ms. =100×5=500 ms, meaning that only 5 control steps within the next 500 ms are optimized.

[0053] In practical applications, the sampling period can be determined first based on the system characteristics of the battery cooling system, and then the total number of prediction steps can be determined based on the control lag time. N To ensure the total forecast duration The system can cover control lag time, and finally determine the number of control time-domain steps based on the system's computing power. M This ensures the flexibility, accuracy, and real-time nature of the control actions.

[0054] Step S402: Based on the current predicted battery heat load of the battery cooling system, determine the feedforward control sequence of the electronic expansion valve opening of the battery cooling system; based on the current average battery temperature and the target battery temperature, determine the feedback control sequence of the electronic expansion valve opening of the battery cooling system.

[0055] As an example, the array form of the electronic expansion valve opening feedforward control sequence is as follows: ,in, This represents the feedforward compensation value for the electronic expansion valve opening corresponding to the first step within the total prediction duration; This represents the feedforward compensation value for the electronic expansion valve opening corresponding to step 2 within the total prediction duration; This represents the feedforward compensation value for the electronic expansion valve opening at step 3 within the total prediction duration. Indicates the first [number]th ... N The corresponding electronic expansion valve opening feedforward compensation value.

[0056] The array form of the electronic expansion valve opening feedback control sequence is as follows: ,in, This represents the electronic expansion valve opening feedback compensation value corresponding to the first step within the total prediction time. This represents the electronic expansion valve opening feedback compensation value corresponding to step 2 within the total prediction time. This represents the electronic expansion valve opening feedback compensation value corresponding to step 3 within the total prediction time. Indicates the first [number]th ... N The corresponding electronic expansion valve opening feedback compensation value.

[0057] Step S403: Based on the electronic expansion valve opening feedforward control sequence and the electronic expansion valve opening feedback control sequence, the optimal control sequence for the electronic expansion valve opening is modified to obtain the electronic expansion valve opening output control sequence.

[0058] As an example, the electronic expansion valve opening feedforward control sequence, electronic expansion valve opening feedback control sequence, and electronic expansion valve opening optimal control sequence are superimposed to obtain the electronic expansion valve opening output control sequence. The array form of the electronic expansion valve opening output control sequence is as follows: ,in, This indicates the output electronic expansion valve opening corresponding to the first step within the total prediction time. ; This indicates the output electronic expansion valve opening corresponding to step 2 within the total prediction time. ; This indicates the output electronic expansion valve opening corresponding to step 3 within the total prediction time. ; This indicates the output electronic expansion valve opening at the Nth step within the total prediction time. .

[0059] Step S404: Based on the electronic expansion valve opening output control sequence, the electronic expansion valve driver is controlled to regulate the opening of the electronic expansion valve in the battery cooling system.

[0060] For ease of understanding, continuing with the above example, the controller 101 in the battery cooling system sends an opening control command to the electronic expansion valve driver. This opening control command includes the output electronic expansion valve opening corresponding to the first step in the electronic expansion valve opening output control sequence obtained in the above example, i.e. Upon receiving the opening control command, the electronic expansion valve driver adjusts the current opening of the electronic expansion valve in the battery cooling system to... .

[0061] In the next sampling period ( (At each time point), repeat the above steps, iterate continuously (re-optimize every cycle), and make up for the accuracy loss caused by "fixed control amount of subsequent steps".

[0062] Compared with traditional electronic expansion valve control methods, the technical solution provided in this application embodiment is based on the current battery cooling system. Based on the current average battery temperature, current refrigerant evaporation temperature, and current electronic expansion valve opening, predict the future battery cooling system performance. The optimal control sequence for the electronic expansion valve opening at any given time is obtained. Then, based on the electronic expansion valve opening feedforward control sequence and the electronic expansion valve opening feedback control sequence, the optimal control sequence for the electronic expansion valve opening is corrected to obtain the electronic expansion valve opening output control sequence. Finally, based on the electronic expansion valve opening output control sequence, the electronic expansion valve driver is controlled to adjust the current electronic expansion valve opening of the electronic expansion valve in the battery cooling system. The response speed is improved by more than 30%, the temperature fluctuation range of the power battery can be controlled within ±1℃, the system COP (energy efficiency ratio) is improved by 5%~8%, and it has adaptive capability, which can be applied to different vehicle driving conditions and ambient temperatures, and the control accuracy is higher.

[0063] In some embodiments, based on the current battery cooling system Based on the current average battery temperature, current refrigerant evaporation temperature, and current electronic expansion valve opening, predict future... Before the optimal control sequence for the electronic expansion valve opening at time 1, the following also applies:

[0064] Determine the target battery temperature and calculate the temperature deviation between the current average battery temperature and the target battery temperature;

[0065] If the temperature deviation is less than the preset temperature difference threshold, the battery cooling system will be controlled to enter the single-branch circulation cooling mode.

[0066] If the temperature deviation is greater than or equal to the preset temperature difference threshold, the battery cooling system will be controlled to enter the dual-branch circulating cooling mode.

[0067] As an example, the temperature deviation between the current average battery temperature and the target battery temperature can be calculated according to formula (2).

[0068] (2);

[0069] In equation (2), This indicates the temperature deviation between the current average battery temperature and the target battery temperature. Indicates the target battery temperature; This indicates the current average battery temperature.

[0070] The preset temperature difference threshold can be flexibly set according to different operating conditions. For example, under steady-state conditions (such as constant speed driving), it can be set to ±2~3℃; under dynamic conditions (such as fast charging, rapid acceleration, mountain road climbing), it can be set to ±4~5℃; under extreme environments (such as low temperatures below -10℃ and high temperatures above 35℃), it can be set to ±5~8℃.

[0071] Figure 5 This is a system structure block diagram of a battery cooling system provided in another embodiment of this application. Figure 5 The battery cooling system shown is Figure 1 Compared to the battery cooling system shown, the system also includes a second reservoir 110 and a water pump 111. The second reservoir 110 is used to store coolant, such as water. The second reservoir 110 → water pump 111 → battery cooling assembly 107 → power battery 108 → second reservoir 110 are connected in sequence to form a coolant circulation cooling loop.

[0072] As an example, if the temperature deviation value If the temperature difference is less than the preset temperature threshold, the controller 101 controls the battery cooling system to enter the single-branch circulation cooling mode, that is, only the refrigerant circulation cooling circuit or the coolant circulation cooling circuit is turned on to cool the power battery, which helps to save energy.

[0073] As another example, if the temperature deviation value If the temperature difference is greater than or equal to the preset temperature difference threshold, the controller 101 controls the battery cooling system to enter the dual-branch circulation cooling mode, that is, simultaneously opening the refrigerant circulation cooling circuit and the coolant circulation cooling circuit to cool down the power battery, so as to quickly reduce the temperature of the power battery, ensure the charging and discharging efficiency of the power battery, and extend the service life of the power battery.

[0074] In some embodiments, determining the target battery temperature includes:

[0075] Obtain the battery cooling system in the current k The battery operating status information at any time includes the battery state of charge, battery charge / discharge rate, and ambient temperature.

[0076] The target battery temperature is determined based on the battery's operating status information.

[0077] The State of Charge (SOC) of a battery is the percentage of its rated capacity (or the usable capacity in its current healthy state) that the battery can currently output. The value usually ranges from 0% to 100%, and it directly reflects the "remaining capacity" of the battery.

[0078] The battery charge / discharge rate is the ratio of the charge / discharge current to the battery's rated capacity. It is used to quantify the speed at which a battery charges and discharges, and directly reflects the battery's charging and discharging capabilities. For example, if the battery's rated capacity is 100Ah and the discharge current is 50A, then the discharge rate = 50A ÷ 100Ah = 0.5C (meaning the battery can be fully discharged in 2 hours).

[0079] Ambient temperature refers to the average air temperature of the environment surrounding the battery or vehicle, excluding the influence of local heat sources such as heat generated by the battery itself or direct sunlight.

[0080] In some implementations, the target battery temperature can be determined based on a preset mapping table of "target battery temperature - battery state of charge - battery charge / discharge rate - ambient temperature".

[0081] For example, when the battery charge / discharge rate is 1C, the target battery temperature can be determined according to Table 1. When the battery charge / discharge rate is 5C, the target battery temperature can be determined according to Table 2.

[0082] As an example, the mapping relationship table of target battery temperature, ambient temperature and SOC at 1C rate can be obtained by the following steps: (1) First, under ambient temperature of -20℃, fully charge the battery and place it for 1 hour to allow the battery to reach thermal and electrochemical equilibrium, and record the target battery temperature when SOC=100%; (2) Then, discharge at 1C rate with constant current to reduce SOC (battery state of charge) to 90%, and then let it stand for 1 hour again, and record the target battery temperature when SOC=90%; (3) Repeat the above discharge and stand steps, and record the target battery temperatures corresponding to SOC of 80%, 70%, 60%, 50%, 40%, 30%, 20%, and 10%; (4) Next, adjust the ambient temperature to -10℃, 0℃, 10℃, 20℃, 30℃, and 40℃, and repeat the above steps (1) to (3) to obtain the full range data collection of SOC from 100% to 10% and the corresponding target battery temperature. (5) Based on the data collected in steps (3) and (4) above, establish a mapping relationship table of target battery temperature, ambient temperature and SOC at 1C rate (i.e., Table 1).

[0083] Similarly, the mapping relationship table of target battery temperature, ambient temperature and SOC at 5C rate can be established by referring to the above method (i.e., Table 2), which will not be elaborated here.

[0084] Table 1. Mapping relationship between target battery temperature, ambient temperature, and SOC at 1C rate.

[0085]

[0086] Table 2. Mapping relationship between target battery temperature, ambient temperature, and SOC at 5C rate.

[0087]

[0088] As an example, assuming the battery charge / discharge rate is 1C, the ambient temperature is 30℃, and the battery state of charge is 50%, then by referring to Table 1 above, we can see that the target battery temperature is 20℃.

[0089] In some embodiments, based on the current battery cooling system Based on the current average battery temperature, current refrigerant evaporation temperature, and current electronic expansion valve opening, predict future... The optimal control sequence for the electronic expansion valve opening at each time step includes:

[0090] Based on the current battery cooling system Based on the current average battery temperature, current refrigerant evaporation temperature, and current electronic expansion valve opening, predict the future battery cooling system performance. Predicted average battery temperature and predicted refrigerant evaporation temperature at any given time;

[0091] Based on the target battery temperature, the battery cooling system will be in the future. The objective optimization function is constructed based on the predicted average battery temperature and predicted refrigerant evaporation temperature at various times, as well as the preset electronic expansion valve opening penalty coefficient.

[0092] Based on the objective function and preset constraints, the future battery cooling system is predicted. The optimal control sequence for the opening degree of the electronic expansion valve at any given time.

[0093] In some embodiments, based on the current battery cooling system Based on the current average battery temperature, current refrigerant evaporation temperature, and current electronic expansion valve opening, predict the future battery cooling system performance. The predicted average battery temperature and predicted refrigerant evaporation temperature at any given time include:

[0094] Obtain battery status parameters and refrigerant status parameters;

[0095] Based on the current average battery temperature, current refrigerant evaporation temperature, and battery state parameters, predict the future battery cooling system... Predicted average battery temperature at any given time;

[0096] Based on the current average battery temperature, current refrigerant evaporation temperature, refrigerant state parameters, and current electronic expansion valve opening, predict the future battery cooling system... Predict the refrigerant evaporation temperature at any given time.

[0097] Battery status parameters mainly include the mass (weight) of the power battery, specific heat capacity, heat generation power, heat transfer coefficient and heat transfer area of ​​forced convection heat transfer between the power battery and the evaporator.

[0098] Refrigerant state parameters mainly include refrigerant flow rate and latent heat of vaporization of refrigerant.

[0099] As an example, the temperature change of a power battery mainly depends on the heat generated by the battery and the heat dissipated by the refrigerant. Therefore, based on the current average battery temperature, the current refrigerant evaporation temperature, and battery state parameters, the future temperature change of the battery cooling system can be predicted. The predicted average battery temperature at time t is expressed mathematically as shown in equation (3).

[0100] (3);

[0101] In equation (3), Indicates the future Predicted average battery temperature at any given time; Indicates the current k The current average battery temperature at any given moment; Indicates the sampling period; Indicates the mass (weight) of the power battery. This indicates the specific heat capacity of the power battery; This indicates the heat generation capacity of the power battery; This represents the heat transfer coefficient for forced convection heat transfer between the power battery and the evaporator. Indicates the heat exchange area; Indicates the current k The current refrigerant evaporation temperature at any given moment.

[0102] After absorbing heat from the power battery, the refrigerant undergoes a phase change, and its evaporation temperature dynamically balances with the heat absorption flow rate. Therefore, based on the current average battery temperature, the current refrigerant evaporation temperature, and the refrigerant state parameters, the future battery cooling system performance can be predicted. The predicted refrigerant evaporation temperature at a given time is expressed mathematically as shown in equation (4).

[0103] (4);

[0104] In equation (4), Indicates the future Predict the refrigerant evaporation temperature at any given time; Indicates refrigerant flow rate; Indicates the latent heat of vaporization of the refrigerant; This indicates the heat loss from the evaporator.

[0105] The relationship between refrigerant flow rate and electronic expansion valve opening is shown in equation (5):

[0106] (6);

[0107] In equation (6), Indicates the flow coefficient; Indicates the current k The current opening degree of the electronic expansion valve at any given moment; This indicates the outlet pressure of the condenser, which is usually a fixed value, such as 10 bar. Indicates the current k The current evaporation pressure at any given time can be obtained through... Obtained by looking up the table.

[0108] Next, with the goal of minimizing the sum of squares of the average battery temperature deviation over the next N steps, and with the addition of a preset electronic expansion valve opening penalty coefficient (to avoid frequent fluctuations in the electronic expansion valve opening), the objective optimization function is constructed, and its mathematical expression is shown in equation (7).

[0109] (7);

[0110] In equation (7), Indicates the target battery temperature; This represents the penalty coefficient for the opening of the electronic expansion valve, which can generally be set to 0.1 to balance the stability of battery temperature control and the opening of the electronic expansion valve. Indicates the future Predicting the opening degree of the electronic expansion valve at any given time; Indicates the future Predicting the opening degree of the electronic expansion valve at any given time.

[0111] To ensure the safe operation of the vehicle's battery cooling system, the following preset constraints need to be met during the optimization of the objective function, as shown in equations (8) to (11):

[0112] (8);

[0113] (9);

[0114] (10);

[0115] (11);

[0116] In equations (8) to (11), Indicates the lowest battery temperature; Indicates the highest battery temperature; Indicates the lowest refrigerant evaporation temperature; Indicates the highest refrigerant evaporation temperature; Indicates the minimum opening degree of the electronic expansion valve; Indicates the maximum opening degree of the electronic expansion valve; This indicates the rate of change of the maximum electronic expansion valve opening.

[0117] Combining equations (7) to (11) above, the future battery cooling system can be solved. The optimal control sequence for the opening degree of the electronic expansion valve at any given time.

[0118] As an example, equations (7) to (11) above can be transformed into quadratic programming problems, and solved using solvers such as quadprog in Matlab and cvxpy in Python to obtain the future battery cooling system. The optimal control sequence for the opening degree of the electronic expansion valve at any given time.

[0119] In some embodiments, determining the electronic expansion valve opening feedforward control sequence and the electronic expansion valve opening feedback control sequence of the battery cooling system includes:

[0120] Based on the current predicted battery heat load of the battery cooling system, determine the feedforward control sequence for the opening of the electronic expansion valve of the battery cooling system.

[0121] Based on the current average battery temperature and the target battery temperature, determine the electronic expansion valve opening feedback control sequence of the battery cooling system.

[0122] Current battery heat load forecast, including the power battery at the current... k The current current value, current voltage value, and current SOC value at any given moment.

[0123] Based on the current current and voltage values ​​of the power battery, its current battery power value is calculated. Then, based on this current battery power value and the current battery SOC value, Table 3 is consulted to obtain the current electronic expansion valve opening feedforward compensation value of the battery cooling system (i.e., ).

[0124] As an example, under a set ambient temperature, the battery is fully charged and left to stand for 1 hour to allow it to reach thermal and electrochemical equilibrium. Then, the battery is discharged at a set power (e.g., 10 kW), and the opening feedforward compensation values ​​are recorded when the SOC drops to 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, and 10%. The above charge-discharge process is repeated, adjusting the battery power to 30 kW, 50 kW, 70 kW, and 100 kW, and the opening feedforward compensation values ​​are recorded when the SOC drops to 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, and 10%. Based on the collected data, a mapping table of "battery power - battery SOC - opening feedforward compensation value" is established (i.e., Table 3).

[0125] Table 3. Mapping Relationship between Battery Power, Battery SOC, and Opening Degree Feedforward Compensation Value

[0126]

[0127] As an example, the current average temperature of the power battery... and target battery temperature In the input PI control model, the output power battery's current electronic expansion valve opening feedback compensation value (i.e. ).

[0128] To reduce the amount of computation and computational complexity, we can ~ All are assigned the value 0. ~ All values ​​are assigned to 0, thus the electronic expansion valve opening feedforward control sequence can be obtained as follows: The electronic expansion valve opening feedback control sequence is as follows: Next, , And the optimal control sequence for the opening of the electronic expansion valve By superimposing the results, the electronic expansion valve opening output control sequence is obtained. .

[0129] In some embodiments, the method further includes:

[0130] Based on the current refrigerant evaporation temperature, determine the current refrigerant superheat and the current refrigerant evaporation pressure;

[0131] If the battery cooling system meets the preset electronic expansion valve forced closure conditions, the electronic expansion valve driver is controlled to forcibly close the electronic expansion valve in the battery cooling system. The preset electronic expansion valve forced closure conditions include at least one of the following: the current average battery temperature is less than a preset temperature threshold, the current refrigerant evaporation pressure is less than a preset pressure threshold, or the current refrigerant superheat is less than a preset superheat threshold.

[0132] The current refrigerant superheat refers to the difference between the actual temperature of the refrigerant after evaporation and the evaporation temperature, and is used to reflect whether the refrigerant flow is sufficient.

[0133] The preset temperature threshold can be flexibly set according to the actual situation, and is generally set to 5℃.

[0134] The preset pressure threshold can be flexibly set according to the actual situation, and is generally set to 1.5~2 bar.

[0135] The preset overheat threshold can be flexibly set according to the actual situation, and is generally set to 2K.

[0136] As an example, the current refrigerant superheat can be calculated according to equation (12).

[0137] (12);

[0138] In equation (12), Indicates the current k The current refrigerant superheat at any given moment; Indicates the current k The current refrigerant temperature at the evaporator outlet at any given moment; Indicates the preceding k The current refrigerant evaporation temperature at any given moment.

[0139] As an example, you can directly look up the "refrigerant evaporation temperature - evaporation pressure" mapping table provided by the refrigerant supplier based on the refrigerant type and the current refrigerant evaporation temperature to obtain the current refrigerant evaporation pressure.

[0140] If at least one of the following conditions for the electronic expansion valve to be forcibly closed is met: the current average battery temperature is less than a preset temperature threshold, the current refrigerant evaporation pressure is less than a preset pressure threshold, or the current refrigerant superheat is less than a preset superheat threshold, the electronic expansion valve driver is controlled to forcibly close the electronic expansion valve in the battery cooling system.

[0141] For example, if the current average battery temperature is less than a preset temperature threshold, the electronic expansion valve actuator is controlled to adjust the opening of the electronic expansion valve to the minimum value. If the current refrigerant evaporation pressure is less than a preset pressure threshold or the current refrigerant superheat is less than a preset superheat threshold, the electronic expansion valve actuator is controlled to forcibly and completely close the electronic expansion valve.

[0142] By simultaneously setting up triple safety protections of low temperature, low evaporation pressure, and low superheat, overcooling or refrigerant liquid slugging can be prevented, which helps to ensure the operational safety of the battery cooling system.

[0143] All of the above-mentioned optional technical solutions can be combined in any way to form the optional embodiments of this application, and will not be described in detail here.

[0144] The following performance tests further illustrate the technical effects of the technical solutions provided in the embodiments of this application.

[0145] Test 1

[0146] The electronic expansion valve control method provided in this application, the traditional PID control method, and the traditional MPC control method were used to conduct real-vehicle tests on a pure electric SUV (Sports Utility Vehicle). The SUV's power battery pack has a capacity of 80kWh, uses R1234yf refrigerant, employs an Infineon TC387 chip as the controller, has a sampling period of 200ms, and operates under NEDC cycle conditions at an ambient temperature of 35℃.

[0147] Test results show that the electronic expansion valve control method provided in this application can control the maximum battery temperature of the power battery below 38℃, with an overshoot of less than 0.5℃, a steady-state error of ±0.3℃, and a system COP of 3.2. Using the traditional PID control method, the overshoot is 2.1℃, the steady-state error is ±1.4℃, and the system COP is 2.9. Using the traditional MPC control method, the overshoot is 1.5℃, the steady-state error is ±1℃, and the system COP is 3.0.

[0148] Test 2

[0149] In low-temperature environments (-10℃), the electronic expansion valve control method provided in this application embodiment can avoid excessive closure of the electronic expansion valve, which could lead to excessively low evaporation pressure. Simulation experiments have verified that the temperature rise rate of the power battery can be increased by 20%, with no risk of frost formation.

[0150] The following are embodiments of the apparatus described in this application, which can be used to execute the embodiments of the method described in this application. For details not disclosed in the apparatus embodiments of this application, please refer to the embodiments of the method described in this application.

[0151] Figure 6 This is a schematic diagram of an electronic expansion valve control device provided in an embodiment of this application. Figure 6 As shown, the electronic expansion valve control device 600 includes:

[0152] Prediction module 601 is configured to predict based on the current battery cooling system. Based on the current average battery temperature, current refrigerant evaporation temperature, and current electronic expansion valve opening, predict the future battery cooling system performance. The optimal control sequence for the electronic expansion valve opening at time t, where 0 ≤ i ≤ N -1, N Indicates the total number of prediction steps;

[0153] The first determining module 602 is configured to determine the electronic expansion valve opening feedforward control sequence of the battery cooling system based on the current predicted value of the battery heat load of the battery cooling system, and to determine the electronic expansion valve opening feedback control sequence of the battery cooling system based on the current average battery temperature and the target battery temperature.

[0154] The correction module 603 is configured to correct the optimal control sequence of the electronic expansion valve opening based on the feedforward control sequence and the feedback control sequence of the electronic expansion valve opening, so as to obtain the output control sequence of the electronic expansion valve opening.

[0155] The first control module 604 is configured to control the electronic expansion valve driver to regulate the current electronic expansion valve opening of the electronic expansion valve in the battery cooling system based on the electronic expansion valve opening output control sequence.

[0156] In some embodiments, the electronic expansion valve control device further includes:

[0157] The temperature difference determination module is configured to determine the target battery temperature and calculate the temperature deviation between the current average battery temperature and the target battery temperature.

[0158] The second control module is configured to control the battery cooling system to enter a single-branch circulating cooling mode if the temperature deviation value is less than a preset temperature difference threshold.

[0159] The third control module is configured to control the battery cooling system to enter a dual-branch circulating cooling mode if the temperature deviation value is greater than or equal to a preset temperature difference threshold.

[0160] In some embodiments, the temperature difference determination module described above includes:

[0161] The information acquisition unit is configured to acquire information about the battery cooling system at the current time. k The battery operating status information at any time includes the battery state of charge, battery charge / discharge rate, and ambient temperature.

[0162] The temperature determination unit is configured to determine the target battery temperature based on battery operating status information.

[0163] In some embodiments, the prediction module 601 described above includes:

[0164] The first prediction unit is configured to predict based on the current battery cooling system. Based on the current average battery temperature, current refrigerant evaporation temperature, and current electronic expansion valve opening, predict the future battery cooling system performance. Predicted average battery temperature and predicted refrigerant evaporation temperature at any given time;

[0165] The building blocks are configured to be based on the target battery temperature and the future battery cooling system. The objective optimization function is constructed based on the predicted average battery temperature and predicted refrigerant evaporation temperature at various times, as well as the preset electronic expansion valve opening penalty coefficient.

[0166] The second prediction unit is configured to predict the future performance of the battery cooling system based on the objective optimization function and preset constraints. The optimal control sequence for the opening degree of the electronic expansion valve at any given time.

[0167] In some embodiments, the first prediction unit described above may be specifically configured as follows:

[0168] Obtain battery status parameters and refrigerant status parameters;

[0169] Based on the current average battery temperature, current refrigerant evaporation temperature, and battery state parameters, predict the future battery cooling system... Predicted average battery temperature at any given time;

[0170] Based on the current average battery temperature, current refrigerant evaporation temperature, refrigerant state parameters, and current electronic expansion valve opening, predict the future battery cooling system... Predict the refrigerant evaporation temperature at any given time.

[0171] In some embodiments, the above-described apparatus further includes:

[0172] The second determining module is configured to determine the current refrigerant superheat and the current refrigerant evaporation pressure based on the current refrigerant evaporation temperature.

[0173] The fourth control module is configured to control the electronic expansion valve driver to forcibly close the electronic expansion valve in the battery cooling system if the battery cooling system meets the preset electronic expansion valve forced closure conditions. The preset electronic expansion valve forced closure conditions include at least one of the following: the current average battery temperature is less than a preset temperature threshold, the current refrigerant evaporation pressure is less than a preset pressure threshold, or the current refrigerant superheat is less than a preset superheat threshold.

[0174] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0175] This application embodiment also provides a new energy vehicle, which includes, as follows: Figure 1 or Figure 5 The battery cooling system shown.

[0176] Figure 7 This is a schematic diagram of the electronic device 700 provided in an embodiment of this application. For example... Figure 7 As shown, the electronic device 700 of this embodiment includes a processor 701, a memory 702, and a computer program 703 stored in the memory 702 and executable on the processor 701. When the processor 701 executes the computer program 703, it implements the steps in the various method embodiments described above. Alternatively, when the processor 701 executes the computer program 703, it implements the functions of each module / unit in the various device embodiments described above.

[0177] Electronic device 700 can be a desktop computer, laptop, handheld computer, cloud server, or other electronic device. Electronic device 700 may include, but is not limited to, a processor 701 and a memory 702. Those skilled in the art will understand that... Figure 7 This is merely an example of electronic device 700 and does not constitute a limitation on electronic device 700. It may include more or fewer parts than shown, or different parts.

[0178] The processor 701 can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0179] The memory 702 can be an internal storage unit of the electronic device 700, such as a hard disk or RAM of the electronic device 700. The memory 702 can also be an external storage device of the electronic device 700, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card equipped on the electronic device 700. The memory 702 can also include both internal and external storage units of the electronic device 700. The memory 702 is used to store computer programs and other programs and data required by the electronic device.

[0180] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0181] If an integrated module / unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can also be implemented by a computer program instructing related hardware. The computer program can be stored in a readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program may include computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. A computer-readable medium may include: any entity or device capable of carrying computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in a computer-readable medium can be appropriately added to or subtracted according to the requirements of legislation and patent practice in a jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, a computer-readable medium does not include electrical carrier signals and electrical signals.

[0182] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for controlling an electronic expansion valve, characterized in that, include: Based on the current battery cooling system Based on the current average battery temperature, current refrigerant evaporation temperature, and current electronic expansion valve opening, the battery cooling system is predicted to perform well in the future. The optimal control sequence for the electronic expansion valve opening at time t, where 0 ≤ i≤N -1, N Indicates the total number of prediction steps; Based on the current predicted battery heat load of the battery cooling system, the feedforward control sequence of the electronic expansion valve opening of the battery cooling system is determined, and based on the current average battery temperature and the target battery temperature, the feedback control sequence of the electronic expansion valve opening of the battery cooling system is determined. The optimal control sequence for the electronic expansion valve opening is modified based on the feedforward control sequence and the feedback control sequence for the electronic expansion valve opening to obtain the output control sequence for the electronic expansion valve opening. The electronic expansion valve driver is controlled by the electronic expansion valve opening output control sequence to regulate the current electronic expansion valve opening in the battery cooling system.

2. The method according to claim 1, characterized in that, Based on the current battery cooling system Based on the current average battery temperature, current refrigerant evaporation temperature, and current electronic expansion valve opening, predict future... Before the optimal control sequence for the electronic expansion valve opening at time 1, the following also applies: Determine the target battery temperature and calculate the temperature deviation between the current average battery temperature and the target battery temperature; If the temperature deviation value is less than the preset temperature difference threshold, the battery cooling system is controlled to enter the single-branch circulation cooling mode. If the temperature deviation value is greater than or equal to the preset temperature difference threshold, the battery cooling system is controlled to enter the dual-branch circulating cooling mode.

3. The method according to claim 2, characterized in that, Determining the target battery temperature includes: Obtain the battery cooling system in the current k The battery operating status information at any time includes the battery state of charge, battery charge / discharge rate, and ambient temperature. Based on the battery operating status information, the target battery temperature is determined.

4. The method according to claim 1, characterized in that, Based on the current battery cooling system Based on the current average battery temperature, current refrigerant evaporation temperature, and current electronic expansion valve opening, predict future... The optimal control sequence for the electronic expansion valve opening at each time step includes: Based on the battery cooling system in the current Based on the current average battery temperature, current refrigerant evaporation temperature, and current electronic expansion valve opening, the battery cooling system is predicted to perform well in the future. Predicted average battery temperature and predicted refrigerant evaporation temperature at any given time; Based on the target battery temperature, the battery cooling system in the future... The objective optimization function is constructed based on the predicted average battery temperature and predicted refrigerant evaporation temperature at various times, as well as the preset electronic expansion valve opening penalty coefficient. Based on the objective optimization function and preset constraints, the future battery cooling system is predicted. The optimal control sequence for the opening degree of the electronic expansion valve at any given time.

5. The method according to claim 4, characterized in that, Based on the battery cooling system in the current Based on the current average battery temperature, current refrigerant evaporation temperature, and current electronic expansion valve opening, the battery cooling system is predicted to perform well in the future. The predicted average battery temperature and predicted refrigerant evaporation temperature at any given time include: Obtain battery status parameters and refrigerant status parameters; Based on the current average battery temperature, current refrigerant evaporation temperature, and battery state parameters, the battery cooling system is predicted to perform well in the future. Predicted average battery temperature at any given time; Based on the current average battery temperature, current refrigerant evaporation temperature, refrigerant state parameters, and current electronic expansion valve opening, the battery cooling system is predicted to... Predict the refrigerant evaporation temperature at any given time.

6. The method according to claim 1, characterized in that, The method further includes: Based on the current refrigerant evaporation temperature, determine the current refrigerant superheat and the current refrigerant evaporation pressure; If the battery cooling system meets the preset electronic expansion valve forced closure conditions, the electronic expansion valve driver is controlled to forcibly close the electronic expansion valve in the battery cooling system. The preset electronic expansion valve forced closure conditions include at least one of the following: the current average battery temperature is less than a preset temperature threshold, the current refrigerant evaporation pressure is less than a preset pressure threshold, or the current refrigerant superheat is less than a preset superheat threshold.

7. An electronic expansion valve control device, characterized in that, include: The prediction module is configured to predict based on the current battery cooling system. Based on the current average battery temperature, current refrigerant evaporation temperature, and current electronic expansion valve opening, the battery cooling system is predicted to perform well in the future. The optimal control sequence for the electronic expansion valve opening at time t, where 0 ≤ i ≤ N -1, N Indicates the total number of prediction steps; The first determining module is configured to determine the electronic expansion valve opening feedforward control sequence of the battery cooling system based on the current predicted value of the battery heat load of the battery cooling system, and to determine the electronic expansion valve opening feedback control sequence of the battery cooling system based on the current average battery temperature and the target battery temperature. The correction module is configured to correct the optimal control sequence for the electronic expansion valve opening based on the feedforward control sequence and the feedback control sequence for the electronic expansion valve opening, so as to obtain the output control sequence for the electronic expansion valve opening. The first control module is configured to control the electronic expansion valve driver to regulate the current electronic expansion valve opening of the electronic expansion valve in the battery cooling system based on the electronic expansion valve opening output control sequence.

8. A battery cooling system, characterized in that, include: The controller includes the electronic expansion valve control device as described in claim 7; An electronic expansion valve actuator, which is communicatively connected to the controller; An electronic expansion valve, wherein the electronic expansion valve is electrically connected to the electronic expansion valve driver; A first liquid receiver, the first liquid receiver including a refrigerant outlet; A battery cooling assembly, the battery cooling assembly including a refrigerant inlet; The electronic expansion valve is located between the refrigerant outlet and the refrigerant inlet; The battery cooling assembly is used to cool and reduce the temperature of the power battery.

9. A new energy vehicle, characterized in that, The new energy vehicle includes the battery cooling system as described in claim 8.

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