Coolant flow rate calculation method and device

Abstract

The application discloses a cooling liquid flow calculation method and device. The calculation method is applied to calculating the cooling liquid flow in the heating process of a heater. The calculation method comprises the following steps: starting timing when the heater starts, acquiring a target power integral value, a real-time heating power, a real-time inlet temperature and a real-time outlet temperature of the heater, and determining a real-time inlet-outlet temperature difference; performing time integral calculation on the real-time heating power, determining a power change amount within a preset time length and average power within a corresponding integral time period; determining a time point of starting integral calculation according to the average power and the power change amount; starting synchronous time integral calculation on the real-time heating power and the real-time inlet-outlet temperature difference after the time point, determining integral power and integral temperature difference at a time point of reaching the target power integral value, and calculating the cooling liquid flow. The embodiment of the application can effectively improve the measurement accuracy of the cooling liquid flow.

Description

Technical Field

[0001] This invention relates to the field of fluid measurement and thermal management control technology, and in particular to a method and apparatus for calculating coolant flow rate. Background Technology

[0002] In the fields of new energy vehicles or industrial production, high-precision liquid flow monitoring is required in scenarios such as vehicle battery cooling and industrial equipment liquid cooling to ensure the long-term normal operation of vehicle batteries or industrial equipment.

[0003] In thermal management systems, accurate coolant flow measurement is crucial for assessing heat dissipation efficiency. However, traditional coolant flow measurement methods may suffer from limitations such as the influence of heater heat during equipment startup and fluctuations in heating power, leading to insufficient accuracy in the measured coolant flow. Summary of the Invention

[0004] This invention provides a method and apparatus for calculating coolant flow rate, in order to solve the problem of low accuracy in coolant flow rate measurement.

[0005] According to one aspect of the present invention, a method for calculating coolant flow rate is provided, which is applied to calculating coolant flow rate during the heating process of a heater; The method for calculating coolant flow rate includes: The timing starts when the heater is started, and the target power integral value, real-time heating power, real-time inlet temperature and real-time outlet temperature of the heater are obtained, and the real-time inlet and outlet temperature difference is determined. The real-time heating power is integrated over time to determine the power change within a preset time period and the average power within the corresponding integration time period. The time point for initiating integral calculation is determined based on the average power and the power change. Synchronous time integration calculation is initiated for the real-time heating power and the real-time inlet and outlet temperature difference after the specified time point. The integrated power and integrated temperature difference are determined at the time point when the target power integral value is reached, and the coolant flow rate is calculated.

[0006] Optionally, the step of performing time integration calculation on the real-time heating power to determine the power change within a preset time period and the average power within the corresponding integration time period includes: The real-time heating power is integrated over time to determine the average power within the time period during which the integration reaches the target power value. Based on the preset duration and its corresponding heating power sequence, the power change within the preset duration is determined; wherein, the heating power sequence includes the real-time heating power corresponding to at least two time points included in the preset duration; the preset duration is included within the time period in which the integral reaches the target power integral value.

[0007] Optionally, the step of performing time integration calculation on the real-time heating power to determine the average power within the time period during which the integration reaches the target power integral value includes: The integral time period for reaching the target power integral value is dynamically determined based on the target power integral value and the real-time heating power. The average power of all real-time heating power within the integration time period is determined by averaging all the power within the integration time period.

[0008] Optionally, determining the power change within the preset time period based on the preset time period and its corresponding heating power sequence includes: Multiple real-time heating powers are acquired within the preset duration at a preset data acquisition cycle, and the heating power sequence is determined. In the heating power sequence, the difference between the real-time heating power corresponding to each two adjacent preset data acquisition cycles is compared, and the difference with the largest value is determined as the power change.

[0009] Optionally, the target power integral value ranges from 80,000 to 100,000 J.

[0010] Optionally, determining the time point for initiating integral calculation based on the average power and the power change includes: Based on the average power, a first time threshold is determined by formula (1); wherein, the first time threshold represents the time point at which the real-time inlet and outlet temperature difference stabilizes, and formula (1) is expressed as follows: (1) in, This represents the first time threshold. Indicates the safety factor. Indicates the mass of the heater's metal carrier. Indicates the specific heat capacity of a metal. This represents the average power; Starting from the first time threshold, the power change is compared with the change threshold until the power change is less than or equal to the change threshold. The time starting point corresponding to the preset duration is then determined as the second time threshold, and the second time threshold is determined as the time point for starting integral calculation. The second time threshold represents the time point when the heating power stabilizes.

[0011] Optionally, the safety factor may range from 1.2 to 1.5.

[0012] Optionally, determining the integral power and integral temperature difference at the time point when the target integral power value is reached, and calculating the coolant flow rate, includes: The time point at which the target power integral value is reached is determined based on the time point at which the integral calculation is initiated and the integral time period at which the target power integral value is reached. The integrated power is determined by integrating the real-time heating power to reach the target power integral value at the time point, and the integrated temperature difference is determined by integrating the real-time inlet and outlet temperature difference to reach the target power integral value at the time point. The coolant flow rate is calculated using formula (2) based on the integral power and the integral temperature difference; formula (2) is expressed as follows: (2) in, This indicates the coolant flow rate. Indicates the density of the coolant. This indicates the specific heat capacity of the coolant. The time integral of the real-time heating power. This represents the time integral of the real-time temperature difference between inlet and outlet.

[0013] Optionally, determining the time point for reaching the target power integral value based on the time point calculated from the start-up integral and the integration time period for reaching the target power integral value further includes: The length of the integration time period is compared with the duration threshold. If the length of the integration time period exceeds the duration threshold, the current integration calculation process is terminated and the next integration calculation process is restarted.

[0014] According to another aspect of the present invention, a coolant flow rate calculation device is provided, comprising: The signal acquisition and processing module is used to start timing when the heater is started, acquire the target power integral value of the heater, real-time heating power, real-time inlet temperature and real-time outlet temperature, and determine the real-time inlet and outlet temperature difference; The stability analysis module is used to perform time integration calculation on the real-time heating power to determine the power change within a preset time period and the average power within the corresponding integration time period. The start-up time determination module is used to determine the time point for start-up integral calculation based on the average power and the power change. The flow calculation module is used to initiate synchronous time integration calculation for the real-time heating power and the real-time inlet and outlet temperature difference after the time point, determine the integrated power and integrated temperature difference at the time point when the target power integral value is reached, and calculate the coolant flow rate.

[0015] The coolant flow rate calculation method provided in this invention involves starting the heater and timing the process. It acquires the heater's real-time heating power, real-time inlet temperature, real-time outlet temperature, and a set target power integral value, and calculates the real-time inlet and outlet temperature difference. The real-time heating power is integrated over time to determine the average power within the integration period when the heater reaches the target power integral value, as well as the power change over a preset duration within that period. This allows for the determination of the heater's power stability period and the time point where its own temperature has minimal impact on the coolant flow rate measurement accuracy. Based on the average power and power change, the starting point for the integration calculation is determined to ensure the accuracy of subsequent integration calculation results. Synchronous time integration calculations are performed on the real-time heating power and real-time inlet and outlet temperature difference after the time point. When the energy integral reaches the target power integral value, the integrated power and integrated temperature difference determined at that time point are used to calculate the coolant flow rate. This constraint on the integration calculation time point reduces the influence of the heater's own temperature on the real-time inlet and outlet temperature difference and the interference of power fluctuations, thereby effectively improving the measurement accuracy of the coolant flow rate.

[0016] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart illustrating a method for calculating coolant flow rate according to an embodiment of the present invention; Figure 2This is a schematic diagram of the specific process of step S120 in a coolant flow rate calculation method provided by an embodiment of the present invention; Figure 3 This is a schematic diagram of the specific process of step S121 in a coolant flow rate calculation method provided by an embodiment of the present invention; Figure 4 This is a schematic diagram of the specific process of step S122 in a coolant flow measurement method according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the specific process of step S130 in a coolant flow rate calculation method provided by an embodiment of the present invention; Figure 6 This is a schematic diagram of the specific process of step S140 in a coolant flow rate calculation method provided by an embodiment of the present invention; Figure 7 This is a schematic diagram of a coolant flow calculation device provided according to an embodiment of the present invention. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0020] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0021] As described in the background section, accurate coolant flow measurement is crucial for assessing heat dissipation efficiency in thermal management systems for vehicle batteries or industrial equipment. Traditional coolant flow measurement methods often use the following formula to calculate the coolant flow rate, which can be expressed as: in, Indicates coolant flow rate. Indicates the density of the coolant. This indicates the specific heat capacity of the coolant. This indicates the heating power of the heater. This indicates the temperature difference between the inlet and outlet of the heater.

[0022] However, traditional methods for measuring coolant flow rate have the following key drawbacks. First, during the initial startup of a vehicle or industrial equipment, the temperature of the heater's metal carrier is still low, and it absorbs heat, leading to an underestimation of the inlet and outlet coolant temperature difference. This results in an inflated calculated coolant flow rate, with errors exceeding 30%. Second, when the heater's heating power is unstable, the instantaneous heating power and the inlet and outlet coolant temperature difference have a non-linear relationship, causing significant deviations in direct calculations. Third, during continuous heater operation, prolonged integration calculations accumulate environmental heat loss and sensor noise, leading to... The integral value is distorted. All of these defects lead to poor accuracy in the measured and calculated coolant flow rate.

[0023] Based on the above-mentioned technical problems, the embodiments of the present invention propose the following technical solutions: This invention provides a method for calculating coolant flow rate. Figure 1 This is a flowchart illustrating a method for calculating coolant flow rate according to an embodiment of the present invention. This embodiment is applicable to calculating the coolant flow rate of a high-temperature liquid heater during the heating process. The method can be executed by a coolant flow rate calculation device, which can be implemented in hardware and / or software and can be configured in a computer or server. Figure 1 As shown, the method for calculating coolant flow rate specifically includes the following steps: S110. Start timing when the heater is started, obtain the target power integral value of the heater, real-time heating power, real-time inlet temperature and real-time outlet temperature, and determine the real-time inlet and outlet temperature difference.

[0024] Specifically, the heater is started and timing begins immediately to integrate the corresponding physical quantities over time. The real-time heating power, inlet temperature, and outlet temperature of the heater are collected at regular data acquisition cycles, where the real-time heating power is variable. The real-time inlet and outlet temperature difference at that time point is obtained by subtracting the real-time outlet temperature from the real-time inlet temperature at the same time point. Furthermore, the target power integral value of the heater represents the target value achieved by the heater at the time point corresponding to the calculation of the coolant flow rate. That is, when the energy reaches the target power integral value after the heater has worked for a period of time, the coolant flow rate is calculated once at that time point. For example, the target power integral value ranges from 80,000 to 100,000 J. The target power integral value can be set according to actual testing needs and is not limited here. In this embodiment of the invention, setting the target power integral value to 80,000 J ensures that the time required for energy integration to reach the target power integral value is appropriate, which is beneficial for improving the accuracy of coolant flow rate measurement.

[0025] S120. Perform time integration calculation on the real-time heating power to determine the power change within a preset time period and the average power within the corresponding integration time period.

[0026] Specifically, during the heater's operation, the real-time heating power is continuously integrated over time. Based on the total time it takes for the heater to reach the target power integral value (i.e., the integration time period), and the real-time heating power at each integration time point within that period, the average power is calculated. This reduces the impact of the heater's own heat absorption on the accuracy of coolant flow rate measurement during the initial startup phase. Furthermore, during the process of the heater reaching the target power integral value, the power change within a preset time period is determined based on this preset time and the corresponding real-time heating power, thus identifying the power stability period of the heater during its operation.

[0027] S130. Determine the time point for starting the integral calculation based on the average power and the power change.

[0028] Specifically, based on the average power within the determined integration time period and the power change within the preset duration, the time point when the heater's heating power is stable and its own temperature has minimal impact can be determined, thus ensuring the accuracy of the subsequent integration calculation results.

[0029] S140. Start synchronous time integration calculation for the real-time heating power and real-time inlet and outlet temperature difference after the time point. Determine the integral power and integral temperature difference at the time point when the target power integral value is reached, and calculate the coolant flow rate.

[0030] Specifically, starting from the determined time point for initiating the integral calculation, the time integration calculations for real-time heating power and real-time inlet / outlet temperature difference are simultaneously initiated, obtaining the integrated power and integrated temperature difference at each time point. The coolant flow rate is calculated using the integrated power and integrated temperature difference corresponding to when the energy integration reaches the target power integrated value. Thus, by dynamically integrating the real-time heating power and real-time inlet / outlet temperature difference with the calibrated target power integrated value over time, and by constraining the time points of the integration calculation based on relevant changes in the heating power required for the calculation, accurate integrated power and integrated temperature difference can be calculated and used for coolant flow rate calculation, thereby effectively improving the measurement accuracy of coolant flow rate.

[0031] The coolant flow rate calculation method provided in this invention involves starting the heater and timing the process. It acquires the heater's real-time heating power, real-time inlet temperature, real-time outlet temperature, and a set target power integral value, and calculates the real-time inlet and outlet temperature difference. The real-time heating power is integrated over time to determine the average power within the integration period when the heater reaches the target power integral value, as well as the power change over a preset duration within that period. This allows for the determination of the heater's power stability period and the time point where its own temperature has minimal impact on the coolant flow rate measurement accuracy. Based on the average power and power change, the starting point for the integration calculation is determined to ensure the accuracy of subsequent integration calculation results. Synchronous time integration calculations are performed on the real-time heating power and real-time inlet and outlet temperature difference after the time point. When the energy integral reaches the target power integral value, the integrated power and integrated temperature difference determined at that time point are used to calculate the coolant flow rate. This constraint on the integration calculation time point reduces the influence of the heater's own temperature on the real-time inlet and outlet temperature difference and the interference of power fluctuations, thereby effectively improving the measurement accuracy of the coolant flow rate.

[0032] Based on the above embodiments, Figure 2 This is a schematic flowchart illustrating step S120 in a coolant flow rate calculation method provided in an embodiment of the present invention. (See also...) Figure 2 Optionally, step S120, which involves performing time integration calculation on the real-time heating power to determine the power change within a preset time period and the average power within the corresponding integration time period, specifically includes the following steps: S121. Perform time integral calculation on the real-time heating power to determine the average power within the time period during which the integral reaches the target power integral value.

[0033] Specifically, since the real-time heating power of the heater changes during operation rather than remaining constant, in order to facilitate subsequent evaluation of the impact on the heater's shell temperature, it is necessary to calculate and determine the average power during the time period from when the heater's operating energy integral reaches the target power integral value.

[0034] S122. Determine the power change within the preset time period based on the preset time period and its corresponding heating power sequence; wherein, the heating power sequence includes the real-time heating power corresponding to at least two time points included in the preset time period; the preset time period is included within the time period during which the integral reaches the target power integral value.

[0035] Specifically, the preset duration is generally shorter than the length of the integration time from energy integration to reaching the target power integral value. The real-time heating power corresponding to each time point within a certain preset duration within the integration time is collected, that is, the heating power sequence corresponding to the preset duration, and the power change of the heater's real-time heating power within that preset duration is calculated.

[0036] Based on the above embodiments, Figure 3 This is a schematic flowchart illustrating step S121 of a coolant flow rate calculation method provided in an embodiment of the present invention. (See also...) Figure 3 Optionally, step S121, which involves performing time integration calculation on the real-time heating power to determine the average power within the time period during which the integration reaches the target power value, specifically includes the following steps: S1211. Based on the target power integral value and the real-time heating power, dynamically determine the integral time period for reaching the target power integral value.

[0037] Specifically, since the real-time heating power of the heater varies during operation, while the target power integral value is fixed after being set, the integration time varies under different real-time heating powers to achieve the target power integral value. Therefore, energy integration for the heater is a dynamic process. Based on the real-time heating power, the integration time required to reach the target power integral value can be dynamically determined, thus defining the integration time period.

[0038] S1212. Average all real-time heating power within the integration time period to determine the average power within the integration time period.

[0039] Specifically, the average power within the integration time period can be determined by averaging the real-time heating power at each time point within the integration time period.

[0040] Based on the above embodiments, Figure 4 This is a schematic flowchart illustrating step S122 of a coolant flow measurement method provided in an embodiment of the present invention. (See also...) Figure 4 Optionally, step S122, which determines the power change within the preset time based on the preset time and its corresponding heating power sequence, specifically includes the following steps: S1221. Acquire multiple real-time heating powers within a preset time period using a preset data acquisition cycle, and determine the heating power sequence.

[0041] For example, the preset data acquisition period can be set according to actual measurement needs and is not limited here. For example, in this embodiment of the invention, the preset data acquisition period can be 0.05 seconds and the preset duration can be 2 seconds, so multiple preset data acquisition periods can be included within a certain preset duration. Real-time heating power at multiple time points is collected according to the preset data acquisition period within a certain preset duration, and the multiple real-time heating powers are sorted in chronological order to obtain a heating power sequence.

[0042] S1222. In the heating power sequence, compare the difference between the real-time heating power corresponding to each two adjacent preset data acquisition cycles, and determine the largest difference as the power change.

[0043] Specifically, the real-time heating power collected at each adjacent time point in the heating power sequence is compared by subtraction, and the largest difference among the heating power values ​​is taken as the power change within the preset time period. For the operation process where the heating power of the heater gradually increases over time, the power change can be calculated using only the real-time heating power corresponding to the start time point and the real-time heating power corresponding to the end time point within the preset time period.

[0044] For example, in Example 1, taking a preset duration of 2 seconds and a preset data acquisition period of 0.5 seconds as an example, assuming the real-time heating power at the 1st second is 4000W, the real-time heating power at the 1.5th second is 4500W, the real-time heating power at the 2nd second is 4200W, the real-time heating power at the 2.5th second is 4500W, and the real-time heating power at the 3rd second is 5000W, then the absolute values ​​of the differences between the two adjacent data are 500W, 300W, 300W, and 500W respectively; therefore, the power change within the preset duration is 500W. Example 2, still using a preset duration of 2 seconds and a preset data acquisition cycle of 0.5 seconds as an example, assume the real-time heating power is 4000W in the first second, 4500W in the first 1.5 seconds, 5000W in the second second, 5500W in the second 2.5 seconds, and 6000W in the third second. Since the heater's heating power gradually increases within this preset duration, the difference between the 6000W at the third second and the 4000W at the first second can be calculated and divided by the preset duration of 2 seconds to obtain the power change within this preset duration as 1000W. Using the method shown in Example 1, the power change of the heater after it reaches stable operation can be calculated to monitor the stability of the real-time heating power. Using the method shown in Example 2, the power change during the initial startup phase of the heater can be calculated, allowing subsequent coolant flow rate measurements to avoid the unstable startup period of the heater, thus improving the accuracy of the coolant flow rate.

[0045] It should be noted that the preset duration is the length of the sliding window of time. That is, during the time integration process, the power change needs to be calculated for each consecutive preset duration in order to determine the stability of the heating power during the operation of the heater.

[0046] Based on the above embodiments, Figure 5 This is a schematic flowchart illustrating step S130 in a coolant flow rate calculation method provided in an embodiment of the present invention. (See also...) Figure 5 Optionally, determining the time point for initiating the integral calculation based on the average power and the power change in step S130 includes: S131. Based on the average power, the first time threshold is determined by formula (1); where the first time threshold represents the time point at which the real-time inlet and outlet temperature difference stabilizes, and formula (1) is expressed as follows: (1) in, Indicates the first time threshold. Indicates the safety factor. Indicates the mass of the heater's metal carrier. Indicates the specific heat capacity of a metal. This represents the average power.

[0047] Specifically, when the heater type is determined, the heater metal carrier mass and metal specific heat capacity in formula (1) are fixed constants. The value of the safety factor can be determined according to actual needs and is not limited here. For example, the range of the safety factor includes 1.2 to 1.5. Preferably, in this embodiment of the invention, the safety factor is 1.3. By substituting the calculated average power into formula (1), the first time threshold can be calculated. The first time threshold is the time point when the real-time inlet and outlet temperature difference is stable. That is, before the integration time reaches the first time threshold, the real-time inlet and outlet temperature difference is in an unstable state, and the real-time inlet and outlet temperature difference during this period is distorted; while the real-time inlet and outlet temperature difference data after reaching the first time threshold is in a stable state. Therefore, the real-time inlet and outlet temperature difference data that has not reached the first time threshold cannot be used to calculate the coolant flow rate and must be discarded. For example, during the integral calculation process, the start time flag bit of each time point that has not reached the first time threshold can be recorded as 1, and the integrator needs to be reset for re-integration; while the start time flag bit of each time point after the first time threshold is recorded as 0, indicating that the integral data at that time point can be used to calculate the coolant flow rate.

[0048] S132. Starting from the first time threshold, the power change is compared with the change threshold until the power change is less than or equal to the change threshold. The time starting point corresponding to the preset duration is determined as the second time threshold, and the second time threshold is determined as the time point for starting integral calculation; wherein, the second time threshold represents the time point when the heating power is stable.

[0049] Specifically, the change threshold can be set according to actual needs and is not restricted here. The power change within a preset time period calculated after the first time threshold is compared with the change threshold. If the power change is greater than the change threshold, it indicates that the real-time heating power within the time period corresponding to the preset time period fluctuates, and the real-time heating power within that preset time period is unstable. If the power change is less than or equal to the change threshold, it indicates that the real-time heating power within the time period corresponding to the preset time period is in a stable state. Therefore, the starting point of the preset time period can be used as the second time threshold. The second time threshold is the time point when the heating power stabilizes. That is, before the integration time reaches the second time threshold, the real-time heating power is in an unstable state, while the real-time heating power data after reaching the second time threshold is in a stable state. Therefore, real-time heating power data that has not reached the second time threshold cannot be used to calculate coolant flow rate and must be discarded. The second time threshold is set as the time point for starting the integral calculation. That is, each time point after reaching the second time threshold simultaneously satisfies the condition that the real-time inlet and outlet temperature difference is less affected by the heater's own temperature and that the real-time heating power does not fluctuate, which is beneficial to improving the accuracy of coolant flow measurement.

[0050] For example, during the integral calculation process, the stable time flag bit of each time point that has not reached the second time threshold can be recorded as 0, and the integrator needs to be reset for re-integration; while the stable time flag bit of each time point from the second time threshold onwards can be recorded as 1, indicating that the integral data of that time point can be used to calculate the coolant flow rate.

[0051] Based on the above embodiments, Figure 6 This is a schematic flowchart illustrating step S140 in a coolant flow rate calculation method provided in an embodiment of the present invention. See also... Figure 6 Optionally, step S140, which involves determining the integral power and integral temperature difference at the time point when the target integral power value is reached, and calculating the coolant flow rate, specifically includes the following steps: S141. Determine the time point for reaching the target power integral value based on the time point of the start-up integral calculation and the integral time period for reaching the target power integral value.

[0052] Specifically, in the process of calculating the time integration of energy, the time point for reaching the target power integral value can be determined by adding the determined start time of the integration calculation and the dynamically determined integration time period for reaching the target power integral value.

[0053] S142. Integrate the real-time heating power to the point in time when the target power integral value is reached, determine the integral power, and integrate the real-time inlet and outlet temperature difference to the point in time when the target power integral value is reached, determine the integral temperature difference.

[0054] Specifically, by integrating the real-time heating power over a defined integration period, the integral power at which the energy reaches the target integral power value can be calculated. Similarly, by integrating the real-time inlet and outlet temperature difference over a defined integration period, the integral temperature difference at which the energy reaches the target integral power value can be calculated. Since the inlet and outlet temperature difference is less affected by the heater's own temperature and the heating power remains stable within the defined integration period, the accuracy of the calculated integral power and integral temperature difference data for this integration period is relatively high.

[0055] S143. Calculate the coolant flow rate using formula (2) based on the integral power and integral temperature difference; formula (2) is expressed as: (2) in, Indicates coolant flow rate. Indicates the density of the coolant. This indicates the specific heat capacity of the coolant. The time integral of the real-time heating power. This represents the time integral of the real-time temperature difference between inlet and outlet.

[0056] Specifically, when the type of coolant used in the heater is determined, the coolant density and specific heat capacity are fixed constants. By substituting the calculated integral power and integral temperature difference into formula (2), the coolant flow rate with high accuracy can be calculated.

[0057] Based on the above embodiments, optionally, the step S141 of determining the time point for reaching the target power integral value based on the time point of the start-up integral calculation and the integral time period for reaching the target power integral value further includes the following steps: The length of the integration time period is compared with the duration threshold. If the length of the integration time period exceeds the duration threshold, the current integration calculation process is terminated and the next integration calculation process is restarted.

[0058] Specifically, the duration threshold is the limit of the continuous integration time, which can be set according to actual needs and is not limited here. For example, the duration threshold can be 300 seconds. The length of the determined integration time period is compared with the duration threshold. If the length of the integration time period exceeds the duration threshold, problems may arise such as excessive heat loss through the heater to the environment due to prolonged integration calculations, and decreased data monitoring accuracy due to prolonged sensor operation. This can lead to a distortion in the ratio of integrated power to integrated temperature difference, resulting in lower accuracy in coolant flow rate measurement. In this case, the current integration calculation process must be stopped, all previous integration data cleared, and a new integration calculation process restarted to ensure the accuracy of the calculated coolant flow rate. It should be noted that to ensure the stability of the integration data, the length of the integration time period should not be too short. For example, the minimum length of the integration time period should be greater than or equal to 15 seconds. That is, the calculation of coolant flow rate should be triggered when the energy integration reaches the target power integration value, provided that the integration calculation starts after the time point and the length of the integration time period does not exceed the duration threshold. This calculation method enables high-precision monitoring of coolant flow rate with an error within ±10%, effectively improving the accuracy of coolant flow rate measurement.

[0059] One feasible embodiment, taking the calculation of coolant flow rate in a new energy vehicle heater as an example, uses the Zhongying SH4225 as the main control chip for the heater. The sensors used for power acquisition include a CC6922SG-5FB040 current sensor (±0.5%) and an ADX111Q analog signal acquisition voltage sensor. The heater is made of aluminum alloy, so the mass of the heater's metal carrier is M = 2.7 kg, and the specific heat capacity of the metal is c = 900 J / (kg·K). A 50% ethylene glycol solution is used as the coolant, with a density of ρ = 1080 kg / m³. 3 The specific heat capacity is Cv = 3480 J / (kg·K). The safety factor is 1.35, and the calibrated target power integral value is 80000 J.

[0060] The measurement process is as follows: The vehicle is powered on and started, the heater begins operation, and timing begins at t=0. Assuming an average power P_avg=4kW, based on the above data, the first time threshold can be calculated as t_threshold=1.35×(2.7×900) / 4000=42 seconds. Therefore, all data collected within 0-42 seconds can be discarded. Starting from t=43 seconds, data is collected at a preset data acquisition cycle of 0.05 seconds. The power change within a preset duration sliding window of 2 seconds is calculated, and the power change within each preset duration is compared with the change threshold. The time point corresponding to the power change being less than the change threshold is determined as the second time threshold. In this embodiment, the second time threshold can be assumed to be the 43rd second. Using the target power integral value and the average power, the length of the integration time period can be calculated as 80000J / 4000W=20s, indicating that the energy reaches the target power integral value of 80000J when integrating from 43 seconds to 63 seconds. The integral power at the 63rd second can be calculated as ∫P=80.0kJ, and the integral temperature difference is ∫ΔT=128K·s.

[0061] Therefore, the flow rate of ethylene glycol coolant can be calculated using the formula Q. l =(1 / (1080×3480))×(80000 / 128)=0.0001663m 3 / s=9.98L / min.

[0062] This invention also provides a coolant flow rate calculation device. Figure 7 This is a schematic diagram of a coolant flow calculation device provided in an embodiment of the present invention. See also... Figure 7 The coolant flow calculation device 000 includes: The signal acquisition and processing module 100 is used to start timing when the heater is started, acquire the target power integral value of the heater, real-time heating power, real-time inlet temperature and real-time outlet temperature, and determine the real-time inlet and outlet temperature difference. The stability analysis module 200 is used to perform time integration calculation on the real-time heating power to determine the power change within a preset time period and the average power within the corresponding integration time period. The start-up time determination module 300 is used to determine the time point for start-up integral calculation based on the average power and the power change. The flow calculation module 400 is used to start synchronous time integration calculation of real-time heating power and real-time inlet and outlet temperature difference after a time point. It determines the integral power and integral temperature difference at the time point when the target power integral value is reached, and calculates the coolant flow rate.

[0063] The coolant flow calculation device provided in the embodiments of the present invention can execute the coolant flow calculation method provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the method, which will not be elaborated here.

[0064] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for calculating coolant flow rate, characterized in that, It is used to calculate the coolant flow rate during the heating process of a heater; The method for calculating coolant flow rate includes: The timing starts when the heater is started, and the target power integral value, real-time heating power, real-time inlet temperature and real-time outlet temperature of the heater are obtained, and the real-time inlet and outlet temperature difference is determined. The real-time heating power is integrated over time to determine the power change within a preset time period and the average power within the corresponding integration time period. The time point for initiating integral calculation is determined based on the average power and the power change. Synchronous time integration calculation is initiated for the real-time heating power and the real-time inlet and outlet temperature difference after the specified time point. The integrated power and integrated temperature difference are determined at the time point when the target power integral value is reached, and the coolant flow rate is calculated.

2. The method for calculating coolant flow rate according to claim 1, characterized in that, The step of performing time integration calculation on the real-time heating power to determine the power change within a preset time period and the average power within the corresponding integration time period includes: The real-time heating power is integrated over time to determine the average power within the time period during which the integration reaches the target power value. Based on the preset duration and its corresponding heating power sequence, the power change within the preset duration is determined; wherein, the heating power sequence includes the real-time heating power corresponding to at least two time points included in the preset duration; the preset duration is included within the time period in which the integral reaches the target power integral value.

3. The method for calculating coolant flow rate according to claim 2, characterized in that, The step of performing time integration calculation on the real-time heating power to determine the average power within the time period during which the integration reaches the target power integral value includes: The integral time period for reaching the target power integral value is dynamically determined based on the target power integral value and the real-time heating power. The average power of all the real-time heating power within the integration time period is calculated to determine the average power within the integration time period.

4. The method for calculating coolant flow rate according to claim 2, characterized in that, The step of determining the power change within the preset time period based on the preset time period and its corresponding heating power sequence includes: Multiple real-time heating powers are acquired within the preset duration at a preset data acquisition cycle, and the heating power sequence is determined. In the heating power sequence, the difference between the real-time heating power corresponding to each two adjacent preset data acquisition cycles is compared, and the difference with the largest value is determined as the power change.

5. The method for calculating coolant flow rate according to claim 1, characterized in that, The target power integral value ranges from 80,000 to 100,000 J.

6. The method for calculating coolant flow rate according to claim 1, characterized in that, Determining the time point for initiating integral calculation based on the average power and the power change includes: Based on the average power, a first time threshold is determined by formula (1); wherein, the first time threshold represents the time point at which the real-time inlet and outlet temperature difference stabilizes, and formula (1) is expressed as follows: （1） in, This represents the first time threshold. Indicates the safety factor. Indicates the mass of the heater's metal carrier. Indicates the specific heat capacity of a metal. This represents the average power; Starting from the first time threshold, the power change is compared with the change threshold until the power change is less than or equal to the change threshold. The time starting point corresponding to the preset duration is then determined as the second time threshold, and the second time threshold is determined as the time point for starting integral calculation. The second time threshold represents the time point when the heating power stabilizes.

7. The method for calculating coolant flow rate according to claim 6, characterized in that, The safety factor ranges from 1.2 to 1.

5.

8. The method for calculating coolant flow rate according to claim 1, characterized in that, The step of determining the integral power and integral temperature difference at the time point when the target integral power value is reached, and calculating the coolant flow rate, includes: The time point at which the target power integral value is reached is determined based on the time point at which the integral calculation is initiated and the integral time period at which the target power integral value is reached. The integrated power is determined by integrating the real-time heating power to reach the target power integral value at the time point, and the integrated temperature difference is determined by integrating the real-time inlet and outlet temperature difference to reach the target power integral value at the time point. The coolant flow rate is calculated using formula (2) based on the integral power and the integral temperature difference; formula (2) is expressed as follows: （2） in, This indicates the coolant flow rate. Indicates the density of the coolant. Indicates the specific heat capacity of the coolant. The time integral of the real-time heating power. This represents the time integral of the real-time temperature difference between inlet and outlet.

9. The method for calculating coolant flow rate according to claim 8, characterized in that, The step of determining the time point for reaching the target power integral value based on the time point calculated from the start-up integral and the integral time period for reaching the target power integral value further includes: The length of the integration time period is compared with the duration threshold. If the length of the integration time period exceeds the duration threshold, the current integration calculation process is terminated and the next integration calculation process is restarted.

10. A coolant flow rate calculation device, characterized in that, include: The signal acquisition and processing module is used to start timing when the heater is started, acquire the target power integral value of the heater, real-time heating power, real-time inlet temperature and real-time outlet temperature, and determine the real-time inlet and outlet temperature difference; The stability analysis module is used to perform time integration calculation on the real-time heating power to determine the power change within a preset time period and the average power within the corresponding integration time period. The start-up time determination module is used to determine the time point for start-up integral calculation based on the average power and the power change. The flow calculation module is used to initiate synchronous time integration calculation for the real-time heating power and the real-time inlet and outlet temperature difference after the time point, determine the integrated power and integrated temperature difference at the time point when the target power integral value is reached, and calculate the coolant flow rate.

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