Novel electric vehicle superheat degree control early warning system and method

Abstract

The invention belongs to the technical field of new energy automobile heat management, and discloses a novel electric automobile superheat degree control early warning system and method.The system comprises a compressor, a chiller valve, a PT sensor and a vehicle control unit, the vehicle control unit is used for collecting the water inlet temperature, the water outlet temperature and the target temperature of a power battery, a correction value is obtained through combination of a calibration table, and the correction value is calculated; in the valve distribution process, a whole vehicle controller takes the proportion of the required rotating speed of the battery end and the required rotating speed of the passenger compartment end as input, looks up a table to obtain the opening degree of a chiller valve, and outputs the opening degree of the chiller valve to a compressor driving unit. And synchronously updating with the rotating speed of the compressor in the same control period. In the superheat degree monitoring process, the PT sensor outputs refrigerant pressure and temperature signals, and the vehicle control unit calculates the superheat degree and compares the superheat degree with a preset threshold value.

Description

Technical Field

[0001] This invention belongs to the field of thermal management technology for new energy vehicles, specifically a novel overheat control and early warning system and method for electric vehicles. Background Technology

[0002] With the popularization of new energy vehicles, power battery thermal management has become a key link in vehicle safety and performance improvement. In the existing technology, most electric vehicles use a single compressor refrigeration circuit, which simultaneously undertakes the tasks of battery cooling and passenger cabin air conditioning. The compressor speed control is mostly based on a single parameter, such as the battery inlet water temperature or the cabin set temperature. There is a lack of a comprehensive correction method for the battery inlet and outlet water temperatures and the target temperature. This single-dimensional adjustment often leads to insufficient control accuracy, and the battery is prone to deviation from the target temperature under conditions such as high-speed discharge and fast charging.

[0003] Existing technologies propose methods to adjust valves through pressure difference or fixed ratio, but these methods are usually independent of compressor control and do not form a dynamic linkage. As a result, when the compressor speed is adjusted, the valve opening is not matched synchronously, causing an imbalance in the distribution of refrigerant in the battery cooling branch and the passenger cabin cooling branch. Especially when the battery load suddenly increases or the cabin demand changes suddenly, the problem of insufficient or excessive refrigerant supply is likely to occur, which affects both battery temperature control and passenger cabin comfort.

[0004] In terms of safety protection, existing technical literature mainly focuses on alarm prompts for overheat monitoring, lacking a hierarchical linkage protection mechanism. The common practice is that when the PT sensor detects an abnormal overheat, it only triggers an alarm or a single power limiting measure, without combining compressor speed regulation with valve allocation for sequential processing. This means that the risk of liquid slugging or exhaust overheating cannot be suppressed in a timely and effective manner. Summary of the Invention

[0005] The purpose of this invention is to provide a novel overheat control and early warning system and method for electric vehicles to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a novel electric vehicle overheat control and early warning system, the system comprising a compressor, a chiller valve, a PT sensor and a vehicle controller; in: The PT sensor is located at the outlet of the power battery cooler and is used to collect coolant pressure and temperature and calculate superheat. The vehicle controller is configured as follows: The compressor set speed is determined based on the power battery temperature parameters and passenger cabin requirements; The opening degree of the chiller valve is determined based on the ratio of the compressor speed requirements at the battery end and the passenger cabin end, so that the compressor speed regulation is consistent with the refrigerant distribution. When the overheating level is lower than the preset lower threshold or higher than the preset upper threshold, an early warning signal is triggered, and a graded protection action with battery cooling as the priority is executed.

[0007] Preferably, the compressor is used for: The compressor is installed in the refrigeration circuit of the electric vehicle. Its suction end is connected to the outlet pipe of the power battery cooler, and its discharge end is connected to the inlet pipe of the condenser, forming a continuous refrigerant flow path. The compressor adopts an electric drive structure and has a scroll or piston compression mechanism inside. It can compress low-temperature and low-pressure superheated steam under the action of control signal and output high-temperature and high-pressure gas to drive the refrigerant to circulate in the circuit. The compressor is connected to the vehicle controller via a cable. The set speed signal output by the controller directly acts on the compressor drive unit, enabling the compressor to operate at the target speed based on the superposition of the power battery correction value and the passenger compartment requirements. To avoid ambiguity, the compressor's operating range is defined within a calibrated range, such as 2000–8000 rpm. Through the continuously adjustable characteristics of this range, the refrigerant can maintain a stable pressure and temperature state before entering the condenser, providing a stable input for the subsequent heat exchange process.

[0008] Preferably, the chiiller valve is used for: The chiller valve is installed at the branch position of the refrigerant pipeline. Its two ends are connected to the power battery cooling branch and the passenger compartment cooling branch respectively, forming a one-to-two pipeline topology. The chiller valve is an electrically controlled valve, and its valve core is controlled by an electrically driven actuator, which can continuously adjust the position between fully closed and fully open. The chiller valve opening is set by the vehicle controller, which first determines the required speed at the battery end. Speed ​​required by passenger cabin Then calculate the percentage:

[0009] In the formula: Outlet water temperature With target temperature The required compressor speed (in rpm) at the battery end is obtained after interpolation and table correction. Its value directly reflects the cooling demand of the battery cooling branch. The vehicle controller determines the temperature based on the driver's settings. With ambient temperature The required speed (in rpm) of the compressor at the passenger cabin end is obtained by looking up the table, and its value corresponds to the cooling requirements of the passenger cabin. The percentage of battery cooling demand in total demand, ranging from 0 to 1, is used as the lookup input. The controller will As the lookup input, the corresponding valve opening is obtained. :

[0010] In the formula: : Indicates the opening degree of the chiiller valve, in percentage (%). The valve opening function established during the calibration phase ensures that the valve allocation remains synchronized with the total required speed of the compressor. Here It is not an abstract parameter, but the ratio of the required rotational speed at the battery end to that at the cabin end. It is directly derived from the temperature measured by the sensor and the driver's input. Its physical meaning is the proportion of battery cooling demand in the total demand.

[0011] Preferably, the PT sensor is used for: The PT sensor is fixed on the refrigerant line at the outlet of the power battery cooler. The sensor body is composed of a pressure sensing element and a temperature sensing element. It can output pressure and temperature signals simultaneously when the refrigerant flows through it. The sensor is electrically connected to the vehicle controller, and the signal is transmitted to the controller in the form of voltage or digital quantity. The vehicle controller calculates the refrigerant superheat based on the output of the PT sensor. The superheat is defined as:

[0012] In the formula: Superheat (unit: K) indicates the value by which the refrigerant temperature is higher than the saturation temperature at the corresponding pressure; The actual refrigerant temperature (in °C) is directly measured by the PT sensor temperature element in the battery cooler outlet pipe. The refrigerant pressure (in MPa) collected by the PT sensor pressure element at the same location; : for the measured pressure The saturation temperature (unit: °C) is obtained from the refrigerant saturation property table; when (e.g., 5K) indicates that the refrigerant is close to saturated liquid, posing a risk of liquid slugging; when If the temperature reaches 15K, it indicates that the refrigerant is severely overheated, posing a risk of compressor exhaust overheating.

[0013] Preferably, the vehicle controller is used for: The vehicle controller establishes an electrical connection with the compressor, chiiller valve and PT sensor. It includes a processing unit and a storage unit. The processing unit is used to perform logical operations, and the storage unit stores interpolation lookup logic and control calibration data. (1) Calculation of the required rotational speed at the battery end: The controller first collects the water inlet temperature of the power battery. Power battery outlet water temperature and battery target temperature Calculate the temperature difference separately:

[0014] In the formula: : Coolant temperature (°C) collected by the inlet temperature sensor of the power battery cooler; : Coolant temperature (°C) collected by the outlet temperature sensor of the power battery cooler; : The target temperature (°C) set by the battery thermal management system; , This represents the difference between the actual battery temperature and the target temperature, and is the input for calculating the correction value. Look up the table using interpolation:

[0015] In the formula: : A lookup function stored in the vehicle controller maps temperature difference to compressor corrected speed (rpm); , Correction values ​​for inlet and outlet water temperatures; Obtain the correction value , Recalculate:

[0016] In the formula: The compressor speed required at the battery end (rpm) is a comprehensive indicator of the battery branch's demand. (2) Calculation of required rotational speed at the cabin end: The controller collects the temperature set by the pilot. With ambient temperature The required speed at the cabin end is obtained through the cabin end calibration table. ; (3) Set the rotation speed:

[0017] In the formula: The compressor speed is set as the input to the compressor drive unit; (4) Chiller valve control: By percentage Find the opening degree by looking up the table. and with Synchronized updates; (5) Overheat protection: When the PT sensor calculates Not here When the interval is within the specified range, the controller outputs a warning signal and executes the following actions in sequence: ① Maintain the flow rate of the battery cooling branch; ② Reduce the flow rate of the passenger compartment cooling branch; ③ Reduce the compressor speed.

[0018] This invention also provides a novel method for overheat control and early warning of electric vehicles, based on the above-mentioned system, and the specific steps of the method are as follows: Compressor speed setting: Collect the inlet water temperature, outlet water temperature and target temperature of the power battery, obtain the correction value by interpolation and lookup table respectively, and add them together to form the compressor speed required by the battery side; at the same time, collect the driver's set temperature and ambient temperature to obtain the compressor speed required by the passenger compartment side, and add it to the compressor speed required by the battery side to form the compressor set speed. Valve distribution linkage: The ratio of the required speed of the compressor at the battery end to the required speed of the compressor at the passenger cabin end is used as the lookup table input to determine the opening degree of the chiiller valve. The opening degree of the chiiller valve is adjusted synchronously while the compressor setting speed is adjusted, so that the compressor speed regulation and refrigerant distribution are linked. Overheat monitoring and sequential protection: The coolant overheat is calculated by a PT sensor and compared with a preset threshold. When the overheat is below the lower threshold, a risk of liquid slugging is identified. When the overheat is above the upper threshold, a risk of exhaust overheating is identified. When the above risks occur, an early warning signal is triggered and protective actions are executed in sequence: first, keep the battery cool; second, reduce passenger compartment cooling; and third, reduce compressor speed.

[0019] Preferably, the specific steps for setting the compressor speed are as follows: In this step, the vehicle controller acquires and processes multiple input signals sequentially: First, read the water inlet temperature of the power battery. With target temperature Calculate the inlet water temperature difference:

[0020] Then the water outlet temperature of the power battery was read. The outlet water temperature difference is obtained as follows:

[0021] The controller uses a lookup table function to interpolate the two temperature difference inputs. The influent correction value is obtained. With water correction value The sum of these two factors determines the required rotational speed at the battery end:

[0022] Based on this, the controller receives the temperature set by the driver. With ambient temperature Through the cabin end calibration table Calculate the required rotational speed at the cabin end:

[0023] Ultimately, the controller adds the two demands together within the same control cycle:

[0024] And The output is sent to the compressor drive unit as its operating command.

[0025] Preferably, the specific steps for valve distribution and linkage are as follows: When the compressor is set to speed Once determined, the vehicle controller enters the valve allocation phase, where it calculates the ratio of demand between the battery side and the compartment side:

[0026] This percentage parameter Input into the valve calibration table This determines the valve opening:

[0027] in, This indicates the opening degree of the chiiller valve, ranging from 0-100%. Subsequently, the controller updates the compressor set speed simultaneously within the same cycle. and valve opening This ensures that the valve action is synchronized with the compressor speed adjustment time. The valve is adjusted to the target position via an electric drive actuator, so that the refrigerant flow ratio in the battery branch and the compartment branch is consistent with the demand ratio.

[0028] Preferably, the specific steps of the overheat monitoring and sequential protection are as follows: While the compressor and the valve are operating normally, the PT sensor provides the refrigerant temperature Tact and the pressure P in real time. The vehicle controller calculates according to the formula:

[0029] Calculate the refrigerant superheat SH, where Tsat(P) is the saturation temperature obtained from the refrigerant property table at the pressure P; The controller compares the superheat with the threshold range [SHmin, SHmax]: When SH < SHmin (such as 5K), judge the risk of liquid slugging; When SH > SHmax (such as 15K), judge the risk of exhaust overheating; When any risk condition is triggered, the controller outputs a warning signal and performs a sequential protection action: Keep the cooling capacity of the battery cooling branch unchanged; Adjust the valve to reduce the distribution of the cabin end branch; Reduce the set speed n of the compressor set .

[0030] The beneficial effects of the present invention are as follows: 1. By introducing the double correction calculation of the inlet water temperature and the outlet water temperature relative to the target temperature in the vehicle controller, and superimposing the two to form the required speed at the battery end, and then adding it to the required speed at the passenger cabin end to form the set speed of the compressor, the present invention overcomes the limitation of the prior art that only relies on single temperature difference control. This method can simultaneously reflect the temperature deviation of the battery coolant at the inlet and outlet, more comprehensively characterize the actual heat dissipation demand of the battery, avoid the deviation of the target temperature caused by the lag of single parameter, and under complex working conditions such as fast charging and high-power discharging, the compressor speed can dynamically adapt to the composite demands of the battery end and the cabin end, making the system respond more timely and accurately to the change of heat load.

[0031] 2. In the valve distribution link, by using the proportion of the required speeds of the compressors at the battery end and the cabin end as the look-up table input to obtain the valve opening value, and synchronously updating the compressor speed and the valve opening in each control cycle to form an integrated linkage of compressor adjustment and valve distribution. This proportion-driven control method is different from the fixed ratio or the separate adjustment based on the pressure difference in the prior art. It can automatically maintain the dynamic balance of the refrigerant between the two branches when the battery load suddenly increases or the demand at the cabin end changes rapidly. Through the synchronous update of the compressor output and the valve opening, the distribution of the refrigerant flow is no longer independently lagging, but is consistent with the operating state of the compressor, improving the coordination of the battery cooling safety and the cabin end comfort.

[0032] 3. This invention uses a PT sensor installed at the battery cooler outlet to collect refrigerant pressure and temperature in real time and calculate superheat. When the superheat is below the lower limit, a risk of liquid slugging is identified; when it is above the upper limit, a risk of exhaust overheating is identified, and a warning signal is output. Based on this, the vehicle controller executes sequential protection based on the principle of prioritizing battery cooling: first, ensuring cooling of the battery branch; second, reducing the demand at the compartment; and finally, reducing the compressor speed. This hierarchical protection mechanism differs from the existing technology's approach of only triggering alarms or single power limiting. It can ensure battery thermal safety while avoiding excessive sacrifice of compartment performance. Through the combination of superheat calculation and sequential control, the system can achieve progressive intervention when risks occur, ensuring a balance between safety and operational stability. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the overall structure of the electric vehicle overheat control and early warning system of the present invention; Figure 2 This is a block diagram illustrating the compressor speed setting and control principle of the present invention. Figure 3 This is a schematic diagram illustrating the linkage between valve allocation and compressor speed in this invention; Figure 4 This is a flowchart of the overheat monitoring and graded protection process of the present invention. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, this embodiment of the invention provides a novel electric vehicle overheat control and early warning system, which includes a compressor, a chiller valve, a PT sensor, and a vehicle controller. in: The PT sensor is located at the outlet of the power battery cooler to collect coolant pressure and temperature and calculate superheat. The vehicle controller is configured as follows: The compressor set speed is determined based on the power battery temperature parameters and passenger cabin requirements; The opening degree of the chiller valve is determined based on the ratio of the compressor speed requirements at the battery end and the passenger cabin end, so that the compressor speed regulation is consistent with the refrigerant distribution. When the overheating level is below the preset lower threshold or above the preset upper threshold, an early warning signal is triggered, and graded protection actions are performed with battery cooling as the priority.

[0036] Example: The present invention provides a novel electric vehicle overheat control and early warning system, which mainly consists of a compressor, a chiller valve, a PT sensor and a vehicle controller. The four components are connected to electrical signals through refrigerant pipelines to form a complete closed-loop control structure. The compressor is installed in the refrigeration circuit, with its suction end connected to the outlet of the power battery cooler and its discharge end connected to the inlet of the condenser. It uses an electrically driven compression mechanism that can continuously adjust the speed within a set range. The chiller valve is located at the refrigerant distribution point, with its two ends connected to the battery cooling branch and the passenger compartment cooling branch, respectively. The valve core is controlled by an electrically driven actuator. The PT sensor is fixed on the battery cooler outlet pipe and is used to simultaneously collect the pressure and temperature of the refrigerant. The vehicle controller is electrically connected to the above components and is used to perform data acquisition, calculation, and control logic.

[0037] During the compressor speed setting process, the vehicle controller collects the inlet water temperature, outlet water temperature, and target temperature of the power battery, and generates a correction result by combining the calibration data to form the required speed at the battery end. At the same time, it collects the driver's set temperature and the ambient temperature to obtain the required speed at the passenger compartment end. The two parts of the demand are added together to form the compressor set speed, and this value is used as the operating command of the compressor drive unit, so that the compressor can quickly respond to the comprehensive needs of the battery and the compartment end under complex operating conditions.

[0038] In the valve distribution linkage process, the vehicle controller obtains the target opening degree of the chiller valve by looking up a table based on the ratio of demand at the battery end and the compartment end, and updates it synchronously with the compressor speed within the same control cycle. The valve core adjusts its position under the action of the electric drive actuator, thereby realizing the dynamic distribution of refrigerant between the battery cooling branch and the compartment cooling branch, so that the refrigerant distribution is consistent with the compressor output, avoiding flow imbalance caused by lag.

[0039] In the overheat monitoring and sequential protection phase, the PT sensor outputs the refrigerant temperature and pressure in real time. The vehicle controller calculates the refrigerant overheat based on this and compares it with the upper and lower limit thresholds. When the overheat is below the lower limit, it determines the risk of liquid slugging; when it is above the upper limit, it determines the risk of exhaust overheating. If a risk is detected, the controller outputs a warning signal and executes three protection steps in sequence: first, keep the battery cool; second, reduce the cooling distribution at the compartment end; and finally, reduce the compressor speed, thereby ensuring battery thermal safety.

[0040] In specific application scenarios, such as fast charging in high summer temperatures, the demand for battery cooling increases significantly. The system can quickly increase the compressor speed through dual correction and ensure battery cooling priority through valve allocation. When cabin-side demand exists simultaneously, the system automatically allocates resources according to their proportions. If the PT sensor detects abnormal overheating, the system immediately executes sequential protection to ensure that the battery is in a safe temperature range while also taking into account passenger cabin comfort and system stability.

[0041] The compressor is used for: The compressor is installed in the refrigeration circuit of the electric vehicle. Its suction end is connected to the outlet pipe of the power battery cooler, and its discharge end is connected to the inlet pipe of the condenser, forming a continuous refrigerant flow path. The compressor adopts an electric drive structure and has a scroll or piston compression mechanism inside. Under the action of a control signal, it can compress low-temperature, low-pressure superheated vapor and output high-temperature, high-pressure gas to drive the refrigerant to circulate in the circuit. The compressor is connected to the vehicle controller via a cable. The set speed signal output by the controller directly acts on the compressor drive unit, enabling the compressor to operate at the target speed based on the superposition of the power battery correction value and the passenger compartment requirements. To avoid ambiguity, the compressor's operating range is defined within a calibrated range, such as 2000–8000 rpm. Through the continuously adjustable characteristics of this range, the refrigerant can maintain a stable pressure and temperature state before entering the condenser, providing a stable input for the subsequent heat exchange process.

[0042] Among them, the chiiller valve is used for: The chiller valve is installed at the branch point of the refrigerant pipeline. Its two ends are connected to the power battery cooling branch and the passenger compartment cooling branch respectively, forming a one-to-two pipeline topology. The chiller valve is an electrically controlled valve, and its valve core is controlled by an electrically driven actuator, which can continuously adjust the position between fully closed and fully open. The chiller valve opening is set by the vehicle controller, which first determines the required speed at the battery end. Speed ​​required by passenger cabin Then calculate the percentage:

[0043] In the formula: Outlet water temperature With target temperature The required compressor speed (in rpm) at the battery end is obtained after interpolation and table correction. Its value directly reflects the cooling demand of the battery cooling branch. The vehicle controller determines the temperature based on the driver's settings. With ambient temperature The required speed (in rpm) of the compressor at the passenger cabin end is obtained by looking up the table, and its value corresponds to the cooling requirements of the passenger cabin. The percentage of battery cooling demand in total demand, ranging from 0 to 1, is used as the lookup input. The controller will As the lookup input, the corresponding valve opening is obtained. :

[0044] In the formula: : Indicates the opening degree of the chiiller valve, in percentage (%). The valve opening function established during the calibration phase ensures that the valve allocation remains synchronized with the total required speed of the compressor. Here It is not an abstract parameter, but the ratio of the required rotational speed at the battery end to that at the cabin end. It is directly derived from the temperature measured by the sensor and the driver's input. Its physical meaning is the proportion of battery cooling demand in the total demand.

[0045] Among them, the PT sensor is used for: The PT sensor is fixed on the refrigerant line at the outlet of the power battery cooler. The sensor body is composed of a pressure sensing element and a temperature sensing element. It can output pressure and temperature signals simultaneously when the refrigerant flows through it. The sensor is electrically connected to the vehicle controller, and the signal is transmitted to the controller in the form of voltage or digital quantity. The vehicle controller calculates the refrigerant superheat based on the output of the PT sensor. The superheat is defined as:

[0046] In the formula: Superheat (unit: K) indicates the value by which the refrigerant temperature is higher than the saturation temperature at the corresponding pressure; The actual refrigerant temperature (in °C) is directly measured by the PT sensor temperature element in the battery cooler outlet pipe. The refrigerant pressure (in MPa) collected by the PT sensor pressure element at the same location; : for the measured pressure The saturation temperature (unit: °C) is obtained from the refrigerant saturation property table; when (e.g., 5K) indicates that the refrigerant is close to saturated liquid, posing a risk of liquid slugging; when If the temperature reaches 15K, it indicates that the refrigerant is severely overheated, posing a risk of compressor exhaust overheating.

[0047] The vehicle controller is used for: The vehicle controller establishes an electrical connection with the compressor, chiiller valve and PT sensor. It includes a processing unit and a storage unit. The processing unit is used to perform logical operations, and the storage unit stores interpolation lookup logic and control calibration data. (1) Calculation of the required rotational speed at the battery end: The controller first collects the water inlet temperature of the power battery. Power battery outlet water temperature and battery target temperature Calculate the temperature difference separately:

[0048] In the formula: : Coolant temperature (°C) collected by the inlet temperature sensor of the power battery cooler; : Coolant temperature (°C) collected by the outlet temperature sensor of the power battery cooler; : The target temperature (°C) set by the battery thermal management system; , This represents the difference between the actual battery temperature and the target temperature, and is the input for calculating the correction value. Look up the table using interpolation:

[0049] In the formula: : A lookup function stored in the vehicle controller maps temperature difference to compressor corrected speed (rpm); , Correction values ​​for inlet and outlet water temperatures; Obtain the correction value , Recalculate:

[0050] In the formula: The compressor speed required at the battery end (rpm) is a comprehensive indicator of the battery branch's demand. (2) Calculation of required rotational speed at the cabin end: The controller collects the temperature set by the pilot. With ambient temperature The required speed at the cabin end is obtained through the cabin end calibration table. ; (3) Set the rotation speed:

[0051] In the formula: The compressor speed is set as the input to the compressor drive unit; (4) Chiller valve control: By percentage Find the opening degree by looking up the table. and with Synchronized updates; (5) Overheat protection: When the PT sensor calculates Not here When the interval is within the specified range, the controller outputs a warning signal and executes the following actions in sequence: ① Maintain the flow rate of the battery cooling branch; ② Reduce the flow rate of the passenger compartment cooling branch; ③ Reduce the compressor speed.

[0052] This invention also provides a novel method for overheat control and early warning of electric vehicles, based on the above-mentioned system, and the specific steps of the method are as follows: Compressor speed setting: Collect the inlet water temperature, outlet water temperature and target temperature of the power battery, obtain the correction value by interpolation and lookup table respectively, and add them together to form the compressor speed required by the battery side; at the same time, collect the driver's set temperature and ambient temperature to obtain the compressor speed required by the passenger compartment side, and add it to the compressor speed required by the battery side to form the compressor set speed. Valve distribution linkage: The ratio of the required speed of the compressor at the battery end to the required speed of the compressor at the passenger cabin end is used as the lookup table input to determine the opening degree of the chiiller valve. The opening degree of the chiiller valve is adjusted synchronously while the compressor setting speed is adjusted, so that the compressor speed regulation and refrigerant distribution are linked. Overheat monitoring and sequential protection: The coolant overheat is calculated by a PT sensor and compared with a preset threshold. When the overheat is below the lower threshold, a risk of liquid slugging is identified. When the overheat is above the upper threshold, a risk of exhaust overheating is identified. When the above risks occur, an early warning signal is triggered and protective actions are executed in sequence: first, keep the battery cool; second, reduce passenger compartment cooling; and third, reduce compressor speed.

[0053] The specific steps for setting the compressor speed are as follows: In this step, the vehicle controller acquires and processes multiple input signals sequentially: First, read the water inlet temperature of the power battery. With target temperature Calculate the inlet water temperature difference:

[0054] Then the water outlet temperature of the power battery was read. The outlet water temperature difference is obtained as follows:

[0055] The controller uses a lookup table function to interpolate the two temperature difference inputs. The influent correction value is obtained. With water correction value The sum of these two factors determines the required rotational speed at the battery end:

[0056] Based on this, the controller receives the temperature set by the driver. With ambient temperature Through the cabin end calibration table Calculate the required rotational speed at the cabin end:

[0057] Ultimately, the controller adds the two demands together within the same control cycle:

[0058] And The output is sent to the compressor drive unit as its operating command.

[0059] The specific steps for valve distribution and linkage are as follows: When the compressor is set to speed Once determined, the vehicle controller enters the valve allocation phase, where it calculates the ratio of demand between the battery side and the compartment side:

[0060] This percentage parameter Input into the valve calibration table This determines the valve opening:

[0061] in, This indicates the opening degree of the chiiller valve, ranging from 0-100%. Subsequently, the controller updates the compressor set speed simultaneously within the same cycle. and valve opening This ensures that the valve action is synchronized with the compressor speed adjustment time. The valve is adjusted to the target position via an electric drive actuator, so that the refrigerant flow ratio in the battery branch and the compartment branch is consistent with the demand ratio.

[0062] The specific steps for superheat monitoring and sequential protection are as follows: While the compressor and the valve are operating normally, the PT sensor provides the refrigerant temperature Tact and pressure P in real time. The vehicle controller calculates the refrigerant superheat SH according to the formula:

[0063] where Tsat(P) is the saturation temperature obtained from the refrigerant property table at pressure P; The controller compares the superheat with the threshold range [SHmin, SHmax]: When SH < SHmin (e.g., 5K), a liquid slugging risk is determined; When SH > SHmax (e.g., 15K), an exhaust overheat risk is determined; When any risk condition is triggered, the controller outputs a warning signal and performs a sequential protection action: Keep the cooling capacity of the battery cooling branch unchanged; Adjust the valve to reduce the distribution of the cabin end branch; Reduce the compressor set speed n set .

[0064] It should be noted that in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device.

[0065] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A novel overheat control and early warning system for electric vehicles, characterized in that: The system includes a compressor, a chiiller valve, a PT sensor, and a vehicle controller; in: The PT sensor is located at the outlet of the power battery cooler and is used to collect coolant pressure and temperature and calculate superheat. The vehicle controller is configured as follows: The compressor set speed is determined based on the power battery temperature parameters and passenger cabin requirements; The opening degree of the chiller valve is determined based on the ratio of the compressor speed requirements at the battery end and the passenger cabin end, so that the compressor speed regulation is consistent with the refrigerant distribution. When the overheating level is lower than the preset lower threshold or higher than the preset upper threshold, an early warning signal is triggered, and a graded protection action with battery cooling as the priority is executed.

2. The novel electric vehicle overheat control and early warning system according to claim 1, characterized in that: The compressor is used for: The compressor is installed in the vehicle's refrigeration circuit. Its suction end is connected to the battery cooler outlet, and its discharge end is connected to the condenser inlet. The compressor is electrically driven and its function is to compress the incoming low-temperature, low-pressure vapor under the speed command output by the vehicle controller to form a high-temperature, high-pressure gas, thereby maintaining the circulation of the refrigerant. The compressor is electrically connected to the vehicle controller and can operate at a set speed based on the battery-side correction calculation results and the passenger compartment requirements. The compressor housing is equipped with a scroll or piston compression assembly, and the speed range can be continuously adjusted within a predetermined calibration range to ensure that the refrigerant enters the condenser and subsequent heat exchange unit in the required state.

3. The novel electric vehicle overheat control and early warning system according to claim 2, characterized in that: The chiiller valve is used for: The chiller valve is located at the branch point of the refrigerant pipeline, with its two ends connected to the battery cooling branch and the passenger compartment cooling branch, respectively. The valve body is an electronically controlled valve structure, which can change its opening degree under the drive signal of the vehicle controller, and is used to distribute the refrigerant flow between the two cooling branches. The opening degree of the chiller valve is not fixed, but is obtained by the vehicle controller by looking up a table based on the ratio of the required speed of the compressor at the battery end to the required speed of the compressor at the passenger compartment end. The valve core is continuously adjusted by the actuator in the range of fully closed to fully open, so that the flow ratio of refrigerant in the two branches is kept synchronized with the set speed of the compressor.

4. The novel electric vehicle overheat control and early warning system according to claim 3, characterized in that: The PT sensor is used for: The PT sensor is fixed on the refrigerant pipeline at the outlet of the battery cooler. Its sensing end is in direct contact with the flowing refrigerant. The sensor is composed of a pressure-sensitive element and a temperature-sensitive element and is used to simultaneously collect the pressure and temperature values ​​of the refrigerant. The output of the PT sensor is electrically connected to the input of the vehicle controller, which can convert real-time pressure and temperature signals into standard electrical signals and transmit them to the controller. The vehicle controller uses the signals to calculate the refrigerant superheat and compares it with a preset threshold as the basis for the judgment of the warning and protection logic.

5. A novel electric vehicle overheat control and early warning system according to claim 4, characterized in that: The vehicle controller is used for: The vehicle controller establishes an electrical connection with the compressor, chiiller valve, and PT sensor to receive pressure and temperature signals from the PT sensor. It also calls the pre-stored interpolation lookup table logic to calculate the correction values ​​corresponding to the difference between the battery inlet water temperature and the target temperature, and the difference between the outlet water temperature and the target temperature, and adds them together to form the required speed of the compressor at the battery end. The vehicle controller further calculates the required compressor speed at the passenger compartment end based on the driver's set temperature and the ambient temperature, and adds it to the required speed at the battery end to form the compressor set speed. The controller uses the ratio of the required speeds at both ends as a lookup input to determine the opening degree of the chiller valve, and outputs a warning signal when the overheat exceeds the upper and lower limit thresholds, while performing graded protection actions to prioritize battery cooling.

6. A novel method for overheat control and early warning of electric vehicles, characterized in that: This novel electric vehicle overheat control and early warning method is based on the system described in claim 5, and the specific steps of the method are as follows: Compressor speed setting: Collect the inlet water temperature, outlet water temperature and target temperature of the power battery, obtain the correction value by interpolation and lookup table respectively, and add them together to form the compressor speed required by the battery side; at the same time, collect the driver's set temperature and ambient temperature to obtain the compressor speed required by the passenger compartment side, and add it to the compressor speed required by the battery side to form the compressor set speed. Valve distribution linkage: The ratio of the required speed of the compressor at the battery end to the required speed of the compressor at the passenger cabin end is used as the lookup table input to determine the opening degree of the chiiller valve. The opening degree of the chiiller valve is adjusted synchronously while the compressor setting speed is adjusted, so that the compressor speed regulation and refrigerant distribution are linked. Overheat monitoring and sequential protection: The coolant overheat is calculated by a PT sensor and compared with a preset threshold. When the overheat is below the lower threshold, a risk of liquid slugging is identified. When the overheat is above the upper threshold, a risk of exhaust overheating is identified. When the above risks occur, an early warning signal is triggered and protective actions are executed in sequence: first, keep the battery cool; second, reduce passenger compartment cooling; and third, reduce compressor speed.

7. A novel method for controlling and warning overheating in electric vehicles according to claim 6, characterized in that: The specific steps for setting the compressor speed are as follows: The vehicle controller receives the difference between the inlet water temperature of the power battery and the target battery temperature, and obtains a first correction value through interpolation and table lookup; at the same time, it receives the difference between the outlet water temperature of the power battery and the target battery temperature, and obtains a second correction value through interpolation and table lookup; the first correction value and the second correction value are added together to form the required speed of the compressor at the battery end; The vehicle controller further receives the driver's set temperature and the ambient temperature, and calculates the required speed of the compressor in the passenger compartment. The required speed of the compressor in the passenger compartment is added to the required speed of the compressor in the battery compartment to form the set speed of the compressor, and the set speed is used as the control input of the compressor drive unit.

8. A novel method for controlling and warning overheating in electric vehicles according to claim 7, characterized in that: The specific steps for valve distribution and linkage are as follows: The vehicle controller uses the ratio of the compressor speed required by the battery side to the compressor speed required by the passenger compartment side as input parameters. It obtains the opening value of the chiiller valve by looking up a table. The valve core of the chiiller valve is adjusted to the corresponding opening position by an electric actuator to control the flow ratio of refrigerant between the two branches. The vehicle controller updates the compressor set speed and the chiller valve opening simultaneously in each control cycle, ensuring that valve adjustment and compressor speed adjustment are synchronized in time, so that the distribution of refrigerant between the battery cooling branch and the passenger compartment cooling branch matches the compressor operating status.

9. A novel method for controlling and warning overheating in electric vehicles according to claim 8, characterized in that: The specific steps for superheat monitoring and sequential protection are as follows: The PT sensor is installed on the refrigerant pipeline at the battery cooler outlet to output refrigerant pressure and temperature signals; the vehicle controller calculates the real-time superheat based on the difference between the saturation temperature corresponding to the collected temperature and pressure; and compares the superheat with a preset lower threshold and an upper threshold to determine the refrigerant operating status. When the overheating level is lower than the preset lower threshold, the vehicle controller determines that there is a risk of liquid slugging; when the overheating level is higher than the preset upper threshold, the vehicle controller determines that there is a risk of exhaust overheating; when any risk occurs, the vehicle controller outputs a warning signal and performs three protective actions in sequence: maintaining the cooling of the battery cooling branch, reducing the cooling of the passenger compartment cooling branch, and reducing the compressor set speed.

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