Cable cooling liquid distribution equalization control method for decentralized liquid-cooled charging piles

Abstract

The application discloses a cable cooling liquid distribution equalization control method for a distributed liquid-cooled charging pile and relates to the technical field of charging pile thermal management. The method comprises the following steps: acquiring the real-time charging power, inlet liquid temperature and outlet liquid temperature of each charging gun, and calculating the real-time heat generation rate; predicting the cumulative heat load, performing phase compensation based on the heat capacity lag time, and generating the expected heat dissipation demand; distributing the total pump flow based on the expected heat dissipation demand as the weight, correcting the minimum maintenance flow to obtain the feasible distribution flow; collecting the cable skin temperature to calculate the temperature difference attenuation rate, correcting the heat capacity lag time to obtain the dynamic lag compensation factor; re-equalizing and correcting the feasible distribution flow, outputting the final distribution flow, generating the electromagnetic valve duty cycle signal and synchronously adjusting the total cooling pump rotating speed. The application realizes on-demand, dynamic and equalized distribution of the cooling liquid, reduces the pumping energy consumption under the premise of ensuring the safety of high-load guns.

Description

Technical Field

[0001] This invention relates to the field of thermal management technology for charging piles, and more specifically to a method for balanced control of cable coolant distribution for distributed liquid-cooled charging piles. Background Technology

[0002] In distributed liquid-cooled charging piles, the power of each charging gun varies dynamically and significantly, requiring precise allocation of coolant flow to each gun cable to achieve balanced control.

[0003] In traditional methods, the cooling pump operates at a fixed speed, supplying the same coolant flow rate regardless of the actual power of each nozzle, relying solely on a simple temperature threshold switch to start and stop the cooling system. This method has significant drawbacks: low-load nozzles are over-cooled, resulting in severe waste of pumping energy; high-load nozzles are under-cooled, posing a safety risk of cable overheating and burnout. Furthermore, the "on-off" threshold control exhibits significant temperature fluctuation lag, leading to frequent start-ups and shutdowns of the cooling system, further exacerbating equipment wear. Therefore, there is an urgent need for a balanced control method that can dynamically distribute coolant based on the real-time power differences of each nozzle, while also considering system energy consumption and charging safety. Summary of the Invention

[0004] This invention addresses the technical problems in existing technologies, such as the inability of coolant distribution to adapt to the real-time power differences of each charging gun, excessive cooling of low-load guns resulting in energy waste, insufficient cooling of high-load guns leading to overheating risks, and the lag and frequent start-stop of on / off temperature control. It provides a cable coolant distribution equalization control method for distributed liquid-cooled charging piles.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: This invention provides a method for equalizing the distribution of cable coolant in distributed liquid-cooled charging piles, comprising: The real-time charging power of each charging gun in the distributed liquid-cooled charging pile is obtained, and the real-time heat generation rate of each charging gun is calculated by combining the inlet liquid temperature and outlet liquid temperature of the corresponding cable. Based on the real-time heat generation rate, the cumulative heat load of each charging gun in the current charging cycle is predicted, and phase compensation is performed on each of the cumulative heat loads based on the thermal capacity lag time to generate the expected heat dissipation demand of each charging gun. Using the expected heat dissipation demand as the allocation weight and combined with the upper limit of the available flow rate of the total pump, the initial allocation flow rate of each charging gun is calculated, and the initial allocation flow rate is corrected based on the minimum maintenance flow rate required for cooling the charging gun to obtain the feasible allocation flow rate. Collect the cable sheath temperature corresponding to each charging gun, calculate the temperature difference attenuation rate between the cable sheath temperature and the corresponding rated operating temperature, and correct the thermal capacity hysteresis time based on the temperature difference attenuation rate to obtain the dynamic hysteresis compensation factor. The feasible distribution flow is rebalanced and corrected using the dynamic hysteresis compensation factor, the final distribution flow is output, and the duty cycle control signal of the solenoid valve of each charging gun circuit is generated to synchronously adjust the speed of the main cooling pump and perform coolant distribution balancing control.

[0006] The beneficial effects of this invention are: Compared to existing technologies, this invention first calculates the heat generation rate of each nozzle by real-time charging power and the temperature difference between the inlet and outlet of the coolant, achieving accurate online sensing of the cable's thermal load. Secondly, it predicts the cumulative heat load based on the heat generation rate and uses thermal capacity lag time for phase compensation, synchronizing the cooling demand prediction with the actual temperature rise of the cable and eliminating control lag caused by heat transfer delay. Thirdly, it allocates the total flow rate with the expected heat dissipation demand as a weight, and after minimum maintenance flow rate correction, it uses a dynamic lag compensation factor based on cable sheath temperature feedback to rebalance the flow rate, ensuring sufficient cooling for high-load nozzles and energy-efficient operation for low-load nozzles. Finally, it generates a solenoid valve duty cycle signal and synchronously adjusts the total cooling pump speed, achieving a fully closed-loop control from flow rate calculation to execution. This invention solves the problems of cooling supply-demand mismatch, energy waste, and overheating risk inherent in traditional methods. Attached Figure Description

[0007] Figure 1 A schematic flowchart of the cable coolant distribution equalization control method for distributed liquid-cooled charging piles provided by the present invention. Figure 2 This is a schematic diagram of the calculation process for a feasible allocation of traffic provided by the present invention. Detailed Implementation

[0008] Examples, such as Figure 1 As shown, this embodiment of the invention provides a cable coolant distribution equalization control method for distributed liquid-cooled charging piles, including: S10: Obtain the real-time charging power of each charging gun in the distributed liquid-cooled charging pile, and calculate the real-time heat generation rate of each charging gun by combining the inlet liquid temperature and outlet liquid temperature of the corresponding cable. Distributed liquid-cooled charging stations are equipped with multiple charging guns, each independently providing charging services for its corresponding electric vehicle. The charging guns integrate coolant channels; coolant flows in from the inlet, passes through the cable, and exits from the outlet, carrying away the Joule heat generated by the energized cable through convective heat transfer. The real-time charging power of different charging guns varies significantly, and the corresponding cable heat generation rates also differ. To achieve on-demand coolant distribution, it is essential to first quantitatively assess the heat generated by each charging gun per unit time under current operating conditions, i.e., the real-time heat generation rate.

[0009] Specifically, the calculation of the real-time heat generation rate needs to comprehensively consider the Joule heating effect of the charging gun and the actual heat-carrying capacity of the coolant. The Joule heat power can be calculated from the charging power and the equivalent resistance of the cable, representing the heat generation power of the cable when energized. The heat power carried away by the coolant from the cable can be calculated from the coolant's flow rate, specific heat capacity, and the temperature difference between the inlet and outlet. Furthermore, the cable itself has a certain heat capacity; some heat is absorbed by the cable itself, causing a temperature increase, rather than all being carried away by the coolant. Therefore, the real-time heat generation rate equals the Joule heat power minus the net heat power carried away by the coolant, while also considering the cable's own heat storage capacity and correction terms caused by the deviation between the inlet liquid temperature and the cable sheath temperature. This step provides accurate heat generation data for subsequent cumulative heat load prediction and flow distribution.

[0010] Specifically, the real-time charging power of each charging gun in the distributed liquid-cooled charging pile is obtained, and the real-time heat generation rate of each charging gun is calculated by combining the inlet and outlet liquid temperatures of the corresponding cables, including: Collect the real-time charging power of each charging gun, and simultaneously record the inlet liquid temperature and outlet liquid temperature of the corresponding cable. Calculate the average reference flow rate based on the maximum available flow rate of the total pump and the total number of charging guns currently in active status; Using the average reference flow rate, coolant specific heat capacity, and the temperature difference between the inlet and outlet liquid temperatures, the heat power carried away by the coolant from the cable is calculated. Based on the real-time charging power and the equivalent resistance of the cable, the Joule heat power is calculated, and the rate of change of the cable sheath temperature is extracted. Combined with the cable heat capacity, the cable's own heat storage power is calculated. The real-time heat generation rate is obtained by adding the heat power carried away by the coolant from the cable to the heat storage power and incorporating a redundancy correction term for the Joule heat power, wherein the redundancy correction term is proportional to the deviation between the inlet liquid temperature and the cable sheath temperature.

[0011] First, the real-time charging power of each charging gun is collected, and the inlet and outlet liquid temperatures of the corresponding cables are recorded. The real-time charging power is directly read from the charging pile's power metering module, representing the instantaneous electrical power output by the charging gun to the electric vehicle at the current moment, measured in kilowatts. This is a core input parameter determining the cable's Joule thermal power. The inlet and outlet liquid temperatures are collected in real-time by temperature sensors installed at the inlet and outlet of the cable's coolant flow channel, respectively. The inlet temperature is the initial temperature of the coolant before it enters the cable flow channel, representing the reference cold source temperature of the coolant; the outlet temperature is the outlet temperature of the coolant after it has absorbed heat through the cable, representing the temperature rise of the coolant after heat exchange. The temperature difference between the inlet and outlet liquid temperatures directly reflects the amount of heat carried away by the coolant from the cable, and is a key basis for calculating the coolant's thermal power.

[0012] Next, the average reference flow rate is calculated based on the maximum available flow rate of the main pump and the total number of charging guns currently active. The maximum available flow rate of the main pump can be obtained directly from the rated flow rate value on the main cooling pump nameplate. This parameter ensures that the sum of the flow rates allocated to each charging gun does not exceed the pump's inherent liquid supply capacity. For example, a main pump with a rated flow rate of 40 liters per minute will reach its maximum when supplying liquid to two charging guns each requiring 20 liters per minute. The average reference flow rate is equal to the maximum available flow rate of the main pump divided by the total number of charging guns currently active. When the number of active guns is zero, the average reference flow rate is set to zero.

[0013] Furthermore, using the average reference flow rate, coolant specific heat capacity, and the temperature difference between the inlet and outlet liquid temperatures, the heat power carried away by the coolant from the cable is calculated. The coolant specific heat capacity is directly obtained from the property parameter table corresponding to the selected coolant model. It characterizes the heat absorbed by a unit mass of coolant when its temperature rises by 1 degree Celsius, expressed in joules per kilogram of degree Celsius. This parameter is a core property constant for calculating the coolant's heat exchange capacity.

[0014] Specifically, the formula for calculating the heat power carried away by the coolant is: Heat power carried away by the coolant = (Average reference flow rate × Coolant density × Coolant specific heat capacity × (Outlet liquid temperature - Inlet liquid temperature)) / 60. After unit conversion, the heat power value is obtained in watts. This heat power carried away by the coolant represents the rate at which the coolant carries away heat from the cable after flowing through it under the average reference flow rate conditions. It is used to evaluate the cooling effect of the current coolant circulation on the cable and serves as a balance term in subsequent real-time heat generation rate calculations and a basis for flow allocation decisions.

[0015] Furthermore, based on the real-time charging power and the cable's equivalent resistance, the Joule thermal power is calculated, and the rate of change of the cable's surface temperature is extracted. Combined with the cable's heat capacity, the cable's own heat storage power is then calculated. Joule thermal power = (Real-time charging power / Charging voltage) 2 × Equivalent resistance of the cable, where the charging voltage is the nominal voltage of the DC bus of the charging pile, which is a constant, such as 800 volts. The rate of change of cable sheath temperature is the change in temperature per unit time, which can be obtained by dividing the temperature difference between adjacent sampling times by the sampling time interval. The cable's own heat storage capacity is equal to the cable's heat capacity multiplied by the above-mentioned rate of temperature change.

[0016] Specifically, the cable's own heat storage power is the rate at which the cable absorbs or releases heat due to its own thermal capacity effect, representing the rate of change of energy storage within the cable. When the cable sheath temperature rises, the heat storage power is positive, indicating that some Joule heat is absorbed by the cable body and not transferred to the coolant in time; when the cable sheath temperature falls, the heat storage power is negative, indicating that the cable body releases the stored heat to assist in heating the coolant. By introducing heat storage power, the calculation of the real-time heat generation rate can more accurately reflect the actual heating state of the cable, avoiding errors in heat generation estimation caused by heat transfer delays.

[0017] Finally, the heat power carried away by the coolant from the cable is added to the heat storage power, and then combined with the redundancy correction term for the Joule heat power to obtain the real-time heat generation rate. The redundancy correction term is proportional to the deviation between the inlet liquid temperature and the cable sheath temperature. When the inlet liquid temperature is lower than the cable sheath temperature, the redundancy correction term is positive, indicating additional temperature difference-driven heat transfer; when the inlet liquid temperature is higher than the cable sheath temperature, the redundancy correction term is negative, indicating that the coolant is actually heating the cable. The formula for calculating the real-time heat generation rate is: Joule heat power minus the sum of the carried-away heat power and the heat storage power, then minus the redundancy correction term, finally yielding the net heat generation rate of the cable per unit time.

[0018] The final real-time heat generation rate reflects the actual amount of heat that the cable needs to have removed by the coolant under the current operating conditions, providing accurate input for subsequent cumulative heat load prediction.

[0019] S20: Based on the real-time heat generation rate, predict the cumulative heat load of each charging gun in the current charging cycle, and perform phase compensation on each of the cumulative heat loads based on the thermal capacity lag time to generate the expected heat dissipation demand of each charging gun. Secondly, after obtaining the real-time heat generation rate of each charging gun, it is necessary to predict the total cumulative heat generation over a future period, i.e., the cumulative heat load, based on the remaining time of the current charging cycle. Since charging power varies over time, the heat generation rate is not constant, and relying solely on the current heat generation rate for flow allocation cannot adapt to dynamic power fluctuations. Therefore, this step analyzes the historical trends in heat generation rate changes, extrapolates the predicted heat generation rate for the remaining charging time, and combines this with the already generated heat load to estimate the total cumulative heat load of the cable at the end of the current charging cycle.

[0020] However, heat transfer in cables exhibits a significant hysteresis effect. After the coolant flows through the cable, it takes a certain amount of time for heat to be transferred from the heat source to the temperature sensor measurement point; this delay is called the thermal hysteresis time. If the current cumulative heat load is directly used as the heat dissipation demand for coolant allocation, the actual heating state of the cable will have changed by the time it takes effect, causing the control action to lag behind the heat load change. This results in untimely cooling response of the high-load gun and overcooling of the low-load gun. Therefore, this step introduces the thermal hysteresis time to perform phase compensation on the cumulative heat load, shifting the currently calculated heat load backward by one hysteresis time to generate the expected heat dissipation demand synchronized with the actual temperature change trend of the cable. Through this phase compensation, the coolant allocation decision can be aligned with the cable's heat load change in time, eliminating the control delay caused by heat transfer hysteresis. The expected heat dissipation demand reflects the heat that the cable will generate after a future hysteresis time interval and is the core weight basis for subsequent flow allocation.

[0021] Specifically, based on the real-time heat generation rate, the cumulative heat load of each charging gun in the current charging cycle is predicted, and phase compensation is performed on each of the cumulative heat loads based on the thermal capacity lag time to generate the expected heat dissipation demand of each charging gun, including: Starting from the current moment, the real-time heat generation rate sequence of each charging gun within the previous continuous time window is extracted in reverse. Linear regression is performed on the real-time heat generation rate sequence to obtain the slope of the change in heat generation rate, and the predicted value of the heat generation rate within the remaining charging time is extrapolated based on the slope of the change. The equivalent heat production rate is obtained by weighting the heat production rate at the end of the real-time heat production rate sequence with the predicted value. The accumulated heat load is determined based on the equivalent heat generation rate and the remaining charging time, combined with the accumulated heat load. Obtain the expected heat dissipation demand output from the previous control cycle, and record it as the historical heat dissipation demand; The thermal hysteresis time is determined based on the temperature difference between the cable sheath temperature and the rated operating temperature, wherein the thermal hysteresis time decreases as the temperature difference increases. The smoothing coefficient is determined based on the sampling period and the thermal hysteresis time. The expected heat demand for the current period is generated by weighting and fusing the equivalent heat generation rate and the historical heat discharge demand using the smoothing coefficient.

[0022] First, starting from the current moment, the real-time heat generation rate sequence of each charging gun within a continuous historical time window is extracted in reverse. Specifically, starting from the current moment as the end point, the system traces backward at fixed sampling intervals, sequentially collecting the real-time heat generation rate value corresponding to each historical sampling point. The collected values ​​are then arranged in chronological order from oldest to newest, forming a real-time heat generation rate sequence within a continuous time window. For example, if the window length is set to 30 seconds and the sampling interval to 1 second, then 30 seconds before the current moment, 30 real-time heat generation rate values ​​are successively acquired to form a sequence.

[0023] Secondly, a linear regression is performed on the real-time heat generation rate sequence to obtain the slope of the heat generation rate change, and the predicted heat generation rate for the remaining charging time is extrapolated based on the slope. Linear regression assumes that the heat generation rate changes linearly with time, and the linear regression line of the sequence can be fitted using the least squares method. The slope of this line is the slope of the heat generation rate change.

[0024] Specifically, a positive slope indicates an increasing heat production rate, while a negative slope indicates a decreasing heat production rate. Adding the slope to the heat production rate at the end of the real-time heat production rate sequence and multiplying it by the remaining charging time yields the predicted heat production rate at the end of the remaining charging time. Linear interpolation between the final heat production rate and the predicted value allows for the calculation of the predicted heat production rate at any point within the remaining charging time.

[0025] Specifically, a linear regression is performed on the real-time heat generation rate sequence to obtain the slope of the heat generation rate change, and the predicted heat generation rate for the remaining charging time is extrapolated based on the slope of the change, including: Each rate value in the real-time heat generation rate sequence is assigned a sequential index number, which is used as a time coordinate. Calculate the rate average of the real-time heat generation rate sequence and the index average of the sequence index number; The slope of change is calculated based on the sum of the products of the average rate, the average index, and the deviations between each rate value and its corresponding index number in the real-time heat production rate sequence. The predicted value of the heat generation rate is calculated based on the change slope, the rate value at the end of the real-time heat generation rate sequence, and the remaining charging time.

[0026] First, each rate value in the real-time heat production rate sequence is assigned a sequential index number, which serves as the time coordinate. The rate values ​​in the real-time heat production rate sequence are arranged in chronological order from oldest to newest, and each rate value is assigned an increasing sequential index number; for example, the first rate value is indexed as 1, the second as 2, and so on up to the nth. The sequential index number represents the relative position of each rate value in the time series and serves as the independent variable for linear regression.

[0027] Next, calculate the rate average and the index average of the sequence indexes for the real-time heat production rate sequence. The rate average is equal to the sum of all rate values ​​in the real-time heat production rate sequence divided by the sequence length n. The index average is equal to the sum of all sequence indexes divided by n.

[0028] Furthermore, the slope of change is calculated based on the sum of the products of the average rate, the average index, and the deviations between each rate value and its corresponding index number in the real-time heat production rate sequence. Specifically, the formula for calculating the slope of change is: Where n is the length of the real-time heat production rate sequence, index number i is the sequential index number corresponding to the i-th rate value, the average index number is the arithmetic mean of the sequential index numbers, rate value i is the i-th real-time heat production rate, and the average rate number is the arithmetic mean of the real-time heat production rate sequence.

[0029] The slope of the change is calculated using two parts: the numerator and the denominator. The numerator is the sum of the products of the difference between each index number and its average value, multiplied by the sum of the differences between the corresponding rate values ​​and their average values. The denominator is the sum of the squares of the differences between each index number and its average value. The slope of the optimal straight line that best describes the linear change in rate with the index number is obtained by fitting the line using the least squares method. This slope represents the trend of heat production rate over time. A positive slope indicates an increasing heat production rate, while a negative slope indicates a decreasing heat production rate.

[0030] Next, based on the slope of change, the rate value at the end of the real-time heat generation rate sequence, and the remaining charging time, a predicted heat generation rate is calculated. The predicted heat generation rate equals the rate value at the end of the time sequence plus the slope of change multiplied by the remaining charging time. This formula assumes that the heat generation rate maintains its current linear trend over the remaining charging time, thus allowing for an estimation of the heat generation rate at the end of charging. This predicted heat generation rate represents an estimate of the instantaneous heat generation rate of the cable at the end of charging under the current trend of heat generation rate change, used to determine whether cable heating intensifies or slows down in the later stages of charging.

[0031] For example, if the heat generation rate at the end of the charging process is 200 watts, the slope of change is 5 watts per second, and the remaining charging time is 30 seconds, then the predicted heat generation rate is 200 plus 5 multiplied by 30, which equals 350 watts. This indicates that the heat generation rate is increasing and will reach 350 watts at the end of the charging process. If the slope of change is -3 watts per second, then the predicted heat generation rate is 200 plus -3 multiplied by 30, which equals 110 watts. This indicates that the heat generation rate is decreasing and will drop to 110 watts at the end of the charging process.

[0032] Furthermore, by linearly interpolating the rate value at the end of the charging period with the predicted value, an estimated heat generation rate can be obtained at any point within the remaining charging time. Specifically, taking the end of the charging period as the starting point and the end of the charging period as the ending point, the heat generation rate changes linearly with time within the remaining charging time interval. For any point in time within the remaining charging time, the estimated heat generation rate is equal to the rate value at the end of the charging period plus the slope of change multiplied by the time interval between that point and the end of the charging period.

[0033] For example, if the remaining charging time is 30 seconds, and the heat generation rate needs to be estimated after 15 seconds, then the heat generation rate after 15 seconds is equal to 200 plus 5 multiplied by 15, which is 275 watts. Through linear regression extrapolation, the future trend of the heat generation rate can be reasonably predicted without relying on future charging power information, providing a basis for calculating cumulative heat load. The advantage of this method is that it does not require real-time acquisition of future charging power plans; it can achieve short-term predictions based solely on historical trends in heat generation rates, making the calculation simple and the response fast.

[0034] Furthermore, the equivalent heat production rate is obtained by weighted averaging the heat production rate at the end of the real-time heat production rate sequence with the predicted value. The equivalent heat production rate represents the average heat production rate level from the current moment to the end of charging. The weights of the weighted average can be set according to the confidence level of the recent heat production trend. For example, the heat production rate at the end of the sequence can be assigned a weight of 0.7, and the predicted value can be assigned a weight of 0.3. When the heat production rate sequence shows a strong trend, the weight of the predicted value can be appropriately increased to enhance the response to trend changes; when the sequence fluctuates greatly and the trend is unclear, the weight of the rate at the end of the sequence can be increased to maintain stability. Through weighted averaging, the equivalent heat production rate integrates the current actual heat production level and the future trend prediction, making the calculation of subsequent cumulative heat load more reasonable.

[0035] Furthermore, based on the equivalent heat generation rate and the remaining charging time, combined with the accumulated heat load, the accumulated heat load is determined. The accumulated heat load is the integral value of the real-time heat generation rate from the start of charging to the current time, which can be obtained by successively accumulating the product of the heat generation rate and the sampling interval within each sampling interval. The accumulated heat load equals the accumulated heat load plus the equivalent heat generation rate multiplied by the remaining charging time. This accumulated heat load is used to reflect the total heat generated by the cable at the end of the current charging cycle.

[0036] Furthermore, the expected heat dissipation demand output from the previous control cycle is obtained and recorded as the historical heat dissipation demand. This historical heat dissipation demand is the heat dissipation demand value output after phase compensation at the end of the previous control cycle, representing the cooling demand predicted in the previous cycle and synchronized with the trend of cable heat load changes. Since the control cycle is executed continuously, the thermal state of the cable between adjacent cycles has continuity and inertia. Therefore, the heat dissipation demand of the previous cycle can be used as a reference for the prediction of the current cycle, forming a smooth transition in time and avoiding drastic jumps in the predicted value caused by sampling noise or instantaneous fluctuations.

[0037] Secondly, the thermal lag time is determined based on the temperature difference between the cable sheath temperature and the rated operating temperature. The thermal lag time decreases as the temperature difference increases. Specifically, the thermal lag time = reference time constant × rated temperature difference / current temperature difference. Here, the reference time constant is the thermal lag time of the cable under rated operating conditions, the rated temperature difference is the difference between the rated operating temperature and the normal cable sheath temperature, and the current temperature difference is the rated operating temperature minus the current cable sheath temperature. When the current temperature difference approaches zero, the thermal lag time is limited to a very small positive value to avoid the denominator being zero and resulting in infinity.

[0038] Thermal hysteresis time represents the time delay of heat transfer from the heat source to the temperature sensor's measuring point within the cable. It quantifies the degree of response delay from heat generation to detection within the cable. A larger thermal hysteresis time indicates a more severe heat transfer delay, requiring a correspondingly larger phase compensation amplitude; a smaller thermal hysteresis time indicates faster heat transfer, allowing for a correspondingly smaller phase compensation amplitude. By dynamically adjusting the thermal hysteresis time based on temperature difference, the phase compensation intensity can be adapted to the cable's thermal response characteristics at different operating temperatures. When the cable temperature approaches the rated operating temperature, the thermal hysteresis time decreases, the compensation intensity increases, and overheating caused by lag in cooling response is avoided.

[0039] Furthermore, a smoothing coefficient is determined based on the sampling period and the thermal capacity lag time. The smoothing coefficient equals the sampling period divided by the sum of the sampling period and the thermal capacity lag time. When the thermal capacity lag time is large, the smoothing coefficient is small, historical heat rejection demand has a larger weight in the current period prediction, and the phase compensation is weak; when the thermal capacity lag time is small, the smoothing coefficient is large, the equivalent heat production rate has a larger weight in the current period prediction, and the phase compensation is strong.

[0040] Finally, a smoothing coefficient is used to weight and fuse the equivalent heat generation rate and historical heat dissipation demand to generate the expected heat dissipation demand for the current cycle. Specifically, the calculation formula is: Expected heat dissipation demand for the current cycle = (Smoothing coefficient × Equivalent heat generation rate) + ((1 - Smoothing coefficient) × Historical heat dissipation demand). Through this weighted fusion, the expected heat dissipation demand reflects both the current heat generation trend and inherits prior information from historical predictions. Furthermore, phase compensation for heat transfer delays is achieved through the heat capacity lag time, ensuring that the predicted cooling demand is synchronized with the actual temperature rise of the cable.

[0041] S30: Using the expected heat dissipation demand as the allocation weight, combined with the upper limit of the available flow rate of the total pump, calculate the initial allocation flow rate of each charging gun, and make a minimum correction to the initial allocation flow rate based on the minimum maintenance flow rate required for cooling the charging gun to obtain the feasible allocation flow rate. Furthermore, after obtaining the expected heat dissipation demand of each charging gun, it needs to be converted into specific coolant flow distribution instructions. A charging gun with a higher expected heat dissipation demand indicates that more heat needs to be removed from the cable during the current charging cycle, and therefore should be allocated a larger coolant flow rate. Therefore, using the expected heat dissipation demand of each charging gun as a weight, the upper limit of the total pump's available flow rate is proportionally distributed among the charging guns to obtain the initial allocated flow rate. High-load guns receive more coolant flow rate, while low-load guns receive less, thus achieving on-demand allocation of cooling resources.

[0042] However, the initial allocated flow rate obtained by weighting the flow rates may be too low, even approaching zero. The coolant flow channel of the charging gun cable has a minimum sustaining flow rate requirement. Below this flow rate, the coolant cannot form forced convection heat transfer within the channel, and the heat generated by the cable cannot be carried away in time, leading to temperature runaway. Therefore, a minimum sustaining flow rate correction is needed for the initial allocated flow rate. Specifically, first, the minimum sustaining flow rate corresponding to each charging gun is obtained. This parameter is determined by the cable channel size and coolant properties. If the sum of the minimum sustaining flow rates of all charging guns exceeds the upper limit of the total pump's available flow rate, the allocation is reduced proportionally to the minimum sustaining flow rate of each gun, so that the reduced sum equals the upper limit of the total pump's available flow rate. Conversely, if the minimum sustaining flow rate is not exceeded, each gun is first ensured to receive at least the minimum sustaining flow rate, and then the remaining flow rate is redistributed proportionally to the excess of the initial allocated flow rate to obtain a feasible allocated flow rate.

[0043] By employing a minimum flow guarantee, each charging gun can be ensured to receive a minimum coolant flow rate sufficient to sustain forced convection heat transfer, thus avoiding the risk of overheating due to insufficient flow. This feasible flow allocation method, while meeting minimum sustaining constraints, still maintains a positive correlation with the expected heat dissipation demand, achieving on-demand allocation under safety constraints.

[0044] Specifically, such as Figure 2As shown, using the expected heat dissipation demand as the allocation weight and combining it with the upper limit of the total pump's available flow rate, the initial allocated flow rate for each charging gun is calculated. Then, based on the minimum sustaining flow rate required for cooling the charging gun, a minimum guaranteed adjustment is made to the initial allocated flow rate to obtain a feasible allocated flow rate, including: Iterate through all the active charging guns, sum up the expected heat dissipation requirements of each charging gun, and get the total demand. The normalized weight of each charging gun is obtained by dividing the expected heat dissipation requirement of each charging gun by the total requirement. The initial allocated flow rate for each charging gun is determined based on the normalized weight of each charging gun and the upper limit of the total pump available flow rate. The minimum sustaining flow rate for each charging gun is obtained by reading the rated technical parameters of each charging gun. Calculate the sum of the minimum sustaining flow rates of all charging guns. If the sum of the minimum sustaining flow rates is greater than the upper limit of the total pump available flow rate, reduce the allocated flow rate of each charging gun according to the ratio of the minimum sustaining flow rate, so that the reduced sum is equal to the upper limit of the total pump available flow rate, and use the reduced result as the feasible allocated flow rate. If the sum of the minimum maintenance flow rates is not greater than the upper limit of the total pump available flow rate, then for each charging gun, the difference between the initial allocated flow rate and the minimum maintenance flow rate is calculated, and those with negative differences are set to zero. The remaining flow rate is obtained by subtracting the sum of the minimum maintenance flow rates from the upper limit of the total pump's available flow rate. The remaining flow rate is then allocated proportionally according to the difference between each charging gun. Finally, the minimum maintenance flow rate of each charging gun is added to the allocated remaining flow rate to obtain the feasible allocation flow rate.

[0045] First, iterate through all active charging guns and sum the expected heat dissipation requirements of each charging gun to obtain the total demand. The total demand reflects the total cooling requirement of all currently active charging guns.

[0046] Secondly, the expected heat dissipation demand of each charging gun is divided by the total demand to obtain the normalized weight of each charging gun. The normalized weight ranges from 0 to 1, and the sum of the normalized weights of all charging guns is equal to 1, representing the proportion of each charging gun's cooling demand to the total demand.

[0047] Then, based on the normalized weight of each charging gun and the upper limit of the total pump's available flow rate, the initial allocated flow rate for each charging gun is determined. Specifically, the initial allocated flow rate is equal to the normalized weight multiplied by the upper limit of the total pump's available flow rate. Charging guns with greater expected heat dissipation demand receive a larger initial allocated flow rate.

[0048] Furthermore, by reading the rated technical parameters of each charging gun, the minimum sustaining flow rate corresponding to each charging gun is obtained. The minimum sustaining flow rate is the minimum flow rate required to ensure that the coolant inside the cable forms forced convection heat transfer; below this minimum sustaining flow rate, heat dissipation will fail.

[0049] Next, calculate the sum of the minimum sustaining flow rates of all charging nozzles. If the sum of the minimum sustaining flow rates is greater than the maximum available flow rate of the main pump, it indicates that meeting the minimum sustaining requirements of each nozzle exceeds the liquid supply capacity of the main pump, and in this case, it must be reduced proportionally. Multiply the minimum sustaining flow rate of each charging nozzle by the same reduction factor. Specifically, this reduction factor is equal to the maximum available flow rate of the main pump divided by the sum of the minimum sustaining flow rates of all charging nozzles, so that the sum of the reduced distribution flow rates of each nozzle is exactly equal to the maximum available flow rate of the main pump, and the reduced result is taken as the feasible distribution flow rate.

[0050] Furthermore, if the sum of the minimum sustaining flow rates is not greater than the maximum available flow rate of the total pump, then for each charging gun, the difference between the initial allocated flow rate and the minimum sustaining flow rate is calculated, and negative differences are set to zero. A positive difference indicates that the gun has additional allocation requirements after meeting the minimum sustaining flow rate, while a negative or zero difference indicates that the initial allocated flow rate of the gun is lower than or equal to the minimum sustaining flow rate, and its additional requirements are considered zero.

[0051] Then, the sum of the minimum sustaining flow rates is subtracted from the upper limit of the total available flow rate of the pump to obtain the remaining flow rate. The remaining flow rate is the flow rate that can be redistributed after ensuring that each charging gun obtains the minimum sustaining flow rate. Subsequently, the remaining flow rate is allocated proportionally according to the difference between the charging guns. Specifically, the positive differences of all charging guns are first summed to obtain the total difference, then each charging gun's own positive difference is divided by the total difference to obtain the allocation ratio for that charging gun. Finally, this ratio is multiplied by the remaining flow rate to obtain the additional allocated flow rate for that charging gun. The minimum sustaining flow rate of each charging gun is added to the allocated additional allocated flow rate to obtain the feasible allocation flow rate.

[0052] Through the above-mentioned minimum guarantee adjustment, the feasible flow allocation ensures that each charging gun can obtain the minimum flow rate sufficient to maintain forced convection heat transfer, while also achieving differentiated allocation according to cooling needs within the capacity of the total pump.

[0053] S40: Collect the cable sheath temperature corresponding to each charging gun, calculate the temperature difference attenuation rate between the cable sheath temperature and the corresponding rated operating temperature, and correct the thermal capacity hysteresis time based on the temperature difference attenuation rate to obtain the dynamic hysteresis compensation factor. Furthermore, after obtaining the feasible flow rate allocation, it is necessary to further adjust the flow rate using real-time feedback from the cable sheath temperature. The feasible flow rate allocation is calculated based on the expected heat dissipation demand and the minimum sustaining flow rate, but its effectiveness depends on the accuracy of the thermal lag time. However, as the charging process progresses, the cable temperature gradually increases, and the temperature difference from the rated operating temperature continuously decreases. The original thermal lag time can no longer accurately reflect the current heat transfer delay characteristics. Therefore, this step introduces cable sheath temperature feedback to calculate the temperature difference decay rate to correct the thermal lag time in real time.

[0054] Specifically, the temperature difference decay rate reflects how close the current cable sheath temperature is to the rated operating temperature. A higher value indicates that the cable temperature is closer to the rated operating temperature and the heat transfer response is faster. Based on the temperature difference decay rate, the thermal capacity lag time determined in the previous steps is corrected to obtain the dynamic lag compensation factor. The dynamic lag compensation factor decreases as the temperature difference decay rate increases. That is, when the cable temperature is close to the rated operating temperature, the compensation factor decreases, the phase compensation strength increases, and the coolant intervenes earlier; when the cable temperature is low, the compensation factor is larger, the phase compensation strength decreases, and overcooling is avoided.

[0055] This step allows for adaptive and dynamic adjustment of the thermal hysteresis time based on the actual cable temperature. The dynamic hysteresis compensation factor embeds real-time temperature difference information into the subsequent flow rebalancing correction, enabling the cooling control to respond more sensitively and accurately to changes in cable temperature, preventing overheating risks caused by cooling hysteresis when the temperature rises rapidly under high load.

[0056] Specifically, the cable sheath temperature corresponding to each charging gun is collected, the temperature difference attenuation rate between the cable sheath temperature and the corresponding rated operating temperature is calculated, and the thermal hysteresis time is corrected based on the temperature difference attenuation rate to obtain a dynamic hysteresis compensation factor, including: Collect the cable sheath temperature corresponding to each charging gun and obtain the rated operating temperature corresponding to each charging gun. Calculate the difference between the rated operating temperature and the cable sheath temperature, and divide it by the difference between the rated operating temperature and the room temperature to obtain the temperature difference attenuation rate. The thermal capacity lag time of the current control cycle is obtained, and a dynamic lag compensation factor is determined based on the thermal capacity lag time and the temperature difference decay rate, wherein the dynamic lag compensation factor decreases as the temperature difference decay rate increases. When the temperature difference decay rate is lower than the lower limit of the decay rate, the dynamic hysteresis compensation factor is fixed as the product of the heat capacity hysteresis time and the reciprocal of the lower limit of the decay rate, wherein the lower limit of the decay rate is the weighted average of the temperature difference decay rate of the previous control cycle and the current temperature difference decay rate.

[0057] First, the cable sheath temperature corresponding to each charging gun is collected, and the rated operating temperature of each charging gun is obtained. Optionally, the cable sheath temperature can be collected in real time by a temperature sensor attached to the outer surface of the cable. This represents the actual temperature of the outer surface of the insulation layer under the current operating condition and is the core feedback parameter for determining whether the cable is overheating and calculating the temperature difference attenuation rate. The rated operating temperature is the highest temperature allowed for the long-term safe operation of the cable insulation material. It can be obtained directly by referring to the technical specifications of each charging gun and the corresponding cable manufacturer, for example, it can be set to 90 degrees Celsius. When the cable sheath temperature is lower than the rated operating temperature, the cable is in a safe operating state; when it approaches or exceeds the rated operating temperature, there is a risk of accelerated insulation aging or thermal breakdown, requiring timely and enhanced cooling.

[0058] Secondly, calculate the difference between the rated operating temperature and the cable sheath temperature, and divide it by the difference between the rated operating temperature and room temperature to obtain the temperature difference decay rate. Room temperature can be taken as ambient temperature, such as 25 degrees Celsius. The temperature difference decay rate reflects how close the current cable sheath temperature is to the rated operating temperature. When the cable sheath temperature is close to the rated operating temperature, the numerator approaches zero, and the temperature difference decay rate approaches zero; when the cable sheath temperature is equal to room temperature, the numerator equals the rated operating temperature minus room temperature, and the temperature difference decay rate equals 1. The smaller the temperature difference decay rate, the higher the cable temperature, the closer it is to the rated operating temperature, and the more urgent the cooling requirement.

[0059] Furthermore, the thermal lag time of the current control cycle is obtained, and the dynamic lag compensation factor is determined based on the thermal lag time and the temperature difference decay rate. Specifically, the dynamic lag compensation factor = thermal lag time / temperature difference decay rate. The dynamic lag compensation factor decreases as the temperature difference decay rate increases and increases as the temperature difference decay rate decreases. When the cable temperature is high and the temperature difference decay rate is low, the dynamic lag compensation factor is large, indicating that a stronger phase compensation force is needed to allow the coolant to intervene earlier; when the cable temperature is low and the temperature difference decay rate is large, the dynamic lag compensation factor is small, and the phase compensation force is weakened.

[0060] Furthermore, when the temperature difference decay rate is below the lower limit of the decay rate, the dynamic lag compensation factor is fixed as the product of the thermal capacity lag time and the reciprocal of the lower limit of the decay rate. The lower limit of the decay rate is taken as the weighted average of the temperature difference decay rate of the previous control cycle and the current temperature difference decay rate. The weighting coefficient is set according to the balance requirements between the dependence on historical decay rates and the system response speed; for example, the weight of the previous cycle is set to 0.7, and the weight of the current cycle is set to 0.3, so that the lower limit of the decay rate has a large inertia with historical values, avoiding drastic fluctuations caused by single measurement noise. The lower limit of the decay rate represents the minimum allowable value of the temperature difference decay rate after smoothing, used to prevent the dynamic lag compensation factor from being excessively amplified when the temperature difference decay rate approaches zero, leading to control instability.

[0061] This smoothing process prevents excessive amplification of the dynamic hysteresis compensation factor, which could lead to control instability, when the temperature difference attenuation rate is too low. When the cable temperature is very close to the rated operating temperature, the dynamic hysteresis compensation factor is limited to a reasonable range, ensuring stable operation of the control system.

[0062] In summary, through the above dynamic correction process, the thermal hysteresis time can be adjusted in real time according to the actual temperature of the cable, so that the phase compensation strength always matches the current thermal state.

[0063] S50: The feasible distribution flow is rebalanced and corrected using the dynamic hysteresis compensation factor, the final distribution flow is output, and the duty cycle control signal of the solenoid valve of each charging gun circuit is generated to synchronously adjust the speed of the main cooling pump and perform coolant distribution balancing control.

[0064] Finally, after obtaining the feasible distribution flow rate and dynamic hysteresis compensation factor, the feasible distribution flow rate needs to be rebalanced and corrected to output the final distribution flow rate and generate the corresponding control signal to execute the coolant distribution control.

[0065] The feasible allocation flow rate is calculated based on the expected heat dissipation demand and corrected for by a minimum sustaining flow rate, but it does not consider real-time feedback of cable sheath temperature. The dynamic hysteresis compensation factor reflects the impact of the proximity of the current cable temperature to the rated operating temperature on heat transfer delay and can be used to differentiate the flow rate of high-load guns. Specifically, firstly, the average heat dissipation demand is calculated based on the expected heat dissipation demand of each charging gun, and charging guns with expected heat dissipation demand greater than the average are marked as high-load guns. For each high-load gun, a rebalancing coefficient is calculated based on its temperature difference decay rate and the dynamic hysteresis compensation factor. The rebalancing coefficient decreases as the temperature difference decay rate increases and increases as the dynamic hysteresis compensation factor increases. The feasible allocation flow rate of the high-load gun is multiplied by the rebalancing coefficient, so that the high-load gun in a high-temperature state receives additional cooling flow rate, forming a "high-temperature priority" compensation mechanism. For non-high-load guns, the feasible allocation flow rate remains unchanged.

[0066] After rebalancing is completed, the flow rates of all charging guns are summed to obtain the total rebalancing flow rate. The ratio of the upper limit of the available flow rate of the main pump to the total rebalancing flow rate is calculated as a scaling factor. The flow rates of each charging gun are scaled proportionally so that the scaled sum is equal to the upper limit of the available flow rate of the main pump. Then, a second check and correction of the minimum maintenance flow rate is performed to obtain the final allocated flow rate.

[0067] Once the final allocated flow rate is determined, it is converted into a corresponding duty cycle control signal according to the flow rate-duty cycle calibration relationship of the solenoid valves in each charging gun circuit. The flow rate-duty cycle calibration relationship is pre-generated during the charging pile commissioning phase. An inverse mapping function from flow rate to duty cycle is established by measuring the actual flow rate of the branches under different duty cycles. Simultaneously, the final allocated flow rates of all charging guns are summed to obtain the total required flow rate. The current actual output flow rate of the main cooling pump is collected, the deviation value is calculated, and the speed control signal of the main cooling pump is adjusted based on the deviation value to make the actual output flow rate approach the total required flow rate. The duty cycle control signal is output to the solenoid valves of the corresponding charging gun circuits, and the speed control signal is output to the drive unit of the main cooling pump to perform coolant distribution equalization control.

[0068] Through the above-mentioned flow distribution and closed-loop execution, the coolant can be distributed on demand, dynamically and evenly among each charging gun, reducing the pumping energy consumption of the cooling system while ensuring the safety of the high-load gun cable.

[0069] Specifically, the feasible allocation flow is rebalanced and corrected using the dynamic hysteresis compensation factor to output the final allocation flow, including: Based on the expected heat dissipation requirements of each charging gun, calculate the average heat dissipation requirements of all active charging guns, and mark the charging guns whose expected heat dissipation requirements are greater than the average heat dissipation requirements as high-load guns. For each high-load gun, obtain the corresponding temperature difference attenuation rate and the dynamic hysteresis compensation factor, and calculate the rebalancing coefficient, wherein the rebalancing coefficient decreases as the temperature difference attenuation rate increases and increases as the dynamic hysteresis compensation factor increases. Multiply the feasible distribution flow of the high-load gun by the rebalancing coefficient to obtain the rebalanced distribution flow; For non-high load guns, the feasible allocation flow is kept unchanged as the rebalanced allocation flow. Based on the relative magnitude of the upper limit of the available flow rate of the total pump and the sum of the distributed flow rates after rebalancing of each charging gun, the distributed flow rates of each charging gun after rebalancing are scaled proportionally so that the scaled sum is equal to the upper limit of the available flow rate of the total pump, and the scaled result is used as the final distributed flow rate of each charging gun.

[0070] First, based on the expected heat dissipation requirements of each charging gun, the average heat dissipation requirement of all active charging guns is calculated. Specifically, the expected heat dissipation requirements of all active charging guns are summed to obtain a total requirement. Then, the total requirement is divided by the total number of active charging guns, and the quotient is the average heat dissipation requirement. This average heat dissipation requirement represents the average intensity of the cooling demand of all charging guns at present, serving as a baseline for judging high-load charging guns.

[0071] Secondly, charging guns with expected heat dissipation demand greater than average heat dissipation demand are marked as high-load guns. High-load guns have a higher heat generation rate than average and require more coolant flow to maintain a safe temperature; charging guns with expected heat dissipation demand less than or equal to average heat dissipation demand are marked as low-load guns, with relatively lower cooling requirements.

[0072] Specifically, for each high-load gun, the corresponding temperature difference attenuation rate and dynamic hysteresis compensation factor are obtained, and the rebalancing coefficient is calculated. Rebalancing coefficient = Dynamic hysteresis compensation factor / (Temperature difference attenuation rate) 2 The rebalancing coefficient decreases with increasing temperature difference decay rate and increases with increasing dynamic hysteresis compensation factor. A larger temperature difference decay rate indicates a lower cable temperature, a smaller rebalancing coefficient, and less additional flow allocation; a smaller temperature difference decay rate indicates a cable temperature closer to the rated operating temperature, a larger rebalancing coefficient, and more additional flow allocation. The dynamic hysteresis compensation factor reflects the degree of correction for heat transfer delay; a larger value indicates a stronger need for phase compensation, and the rebalancing coefficient increases accordingly.

[0073] Then, the feasible allocation flow rate of the high-load gun is multiplied by a rebalancing coefficient to obtain the rebalanced allocation flow rate. After multiplying by the rebalancing coefficient, the flow rate of the high-load gun is amplified differentially according to its current temperature state. The higher the temperature of the high-load gun, the more additional flow rate it receives, forming a "high-temperature priority" compensation mechanism. For non-high-load guns, the feasible allocation flow rate remains unchanged as the rebalanced allocation flow rate, and no additional flow rate compensation is performed.

[0074] Finally, based on the relative magnitude of the maximum available flow rate of the main pump and the sum of the rebalanced distribution flow rates of each charging gun, the rebalanced distribution flow rates of each charging gun are scaled proportionally so that the scaled sum equals the maximum available flow rate of the main pump. This scaled result is then used as the final distribution flow rate for each charging gun. This proportional scaling ensures that the sum of the final distribution flow rates does not exceed the maximum liquid supply capacity of the main pump.

[0075] Specifically, based on the relative magnitude of the upper limit of the available flow rate of the total pump and the sum of the rebalanced distribution flow rates of each charging gun, the rebalanced distribution flow rates of each charging gun are scaled proportionally so that the scaled sum equals the upper limit of the available flow rate of the total pump, and the scaled result is used as the final distribution flow rate of each charging gun, including: The total rebalancing flow is obtained by summing the distributed flow after rebalancing of all charging guns. Calculate the ratio of the upper limit of the total available flow rate of the pump to the sum of the rebalancing flow rates, and denot it as the scaling factor; The distribution flow of each charging gun after rebalancing is adjusted according to the scaling factor to obtain the preliminary final flow, wherein the preliminary final flow increases as the scaling factor increases; Iterate through the initial final flow rate of each charging gun. If there is a charging gun with a flow rate lower than the minimum sustaining flow rate, then force the initial final flow rate of the charging gun with a flow rate lower than the minimum sustaining flow rate to be set to the minimum sustaining flow rate. Calculate the sum of the minimum sustaining flow rates of all charging guns. If the sum of the minimum sustaining flow rates is greater than the upper limit of the total pump available flow rate, reduce the allocated flow rate of each charging gun according to the proportion of the minimum sustaining flow rate, so that the reduced sum is equal to the upper limit of the total pump available flow rate, and use the reduced result as the final allocated flow rate of each charging gun. If the sum of the minimum sustaining flow rates is not greater than the upper limit of the total available flow rate of the pump, then the upper limit of the total available flow rate of the pump is subtracted from the sum of the minimum sustaining flow rates to obtain the remaining flow rate; For charging guns where the initial final flow rate is not lower than the minimum maintenance flow rate, the remaining flow rate is allocated proportionally based on the difference between the initial final flow rate and the minimum maintenance flow rate, and the allocated flow rate is added to the minimum maintenance flow rate to obtain the final allocated flow rate for each charging gun. For a charging gun that is forced to be set to the minimum sustaining flow rate, the corresponding final allocated flow rate is the minimum sustaining flow rate.

[0076] First, the rebalanced flow rates of all charging guns are summed to obtain the total rebalanced flow rate. The rebalanced flow rate is the result of differential compensation for high-load guns based on the feasible flow rate, and its sum may be greater than, equal to or less than the upper limit of the total pump's available flow rate.

[0077] Next, calculate the ratio of the maximum available flow rate of the main pump to the total rebalancing flow rate, and denot it as the scaling factor. If the scaling factor is less than 1, it indicates that the total flow rate after rebalancing exceeds the liquid supply capacity of the main pump and needs to be compressed proportionally; if the scaling factor is greater than 1, it indicates that the main pump has spare capacity and can be scaled up proportionally.

[0078] Then, the rebalanced flow rate of each charging gun is adjusted according to the scaling factor to obtain the preliminary final flow rate. The preliminary final flow rate is equal to the rebalanced flow rate multiplied by the scaling factor, that is, it increases as the scaling factor increases and decreases as the scaling factor decreases. Through proportional scaling, the sum of the preliminary and final flow rates equals the upper limit of the total pump's available flow rate, but the flow rate of each gun may be lower than its minimum maintenance flow rate, requiring a secondary baseline correction.

[0079] Specifically, the initial and final flow rates of each charging gun are iterated. If any charging gun has a flow rate lower than the minimum sustaining flow rate, its initial and final flow rates are forcibly set to the minimum sustaining flow rate. This step ensures that each charging gun receives at least a minimum flow rate sufficient to sustain forced convection heat transfer, preventing heat dissipation failure due to excessively low flow rates.

[0080] Next, calculate the sum of the minimum sustaining flow rates of all charging nozzles. If the sum of the minimum sustaining flow rates exceeds the maximum available flow rate of the main pump, it indicates that meeting the minimum sustaining requirements of each nozzle exceeds the liquid supply capacity of the main pump. In this case, the flow rate must be reduced proportionally. That is, the allocated flow rate is reduced according to the ratio of the minimum sustaining flow rate of each nozzle, so that the sum after reduction equals the maximum available flow rate of the main pump. The reduced result is used as the final allocated flow rate of each charging nozzle. The reduction factor is calculated as follows: the reduction factor equals the maximum available flow rate of the main pump divided by the sum of the minimum sustaining flow rates, and the final allocated flow rate of each nozzle equals its minimum sustaining flow rate multiplied by the reduction factor.

[0081] Furthermore, if the sum of the minimum sustaining flow rates does not exceed the maximum available flow rate of the main pump, it means that the main pump's liquid supply capacity is sufficient to meet the minimum cooling requirements of all charging guns. In this case, there is available surplus flow rate for further differentiated allocation. The surplus flow rate is obtained by subtracting the sum of the minimum sustaining flow rates from the maximum available flow rate of the main pump. The surplus flow rate is the additional flow rate that can be redistributed after ensuring that each gun receives the minimum sustaining flow rate, in order to compensate for the cooling gap of high-load charging guns.

[0082] Specifically, for charging guns whose initial final flow rate is not lower than the minimum sustaining flow rate, the remaining flow rate is allocated proportionally based on the difference between the initial final flow rate and the minimum sustaining flow rate. The larger the difference, the greater the additional flow rate requirement of the charging gun after meeting the minimum sustaining flow rate, and the higher its share should be allocated in the remaining flow rate distribution. First, the differences of all charging guns with flow rates not lower than the minimum sustaining flow rate are summed to obtain the total difference. Then, each gun's own difference is divided by the total difference to obtain its allocation ratio. Finally, this ratio is multiplied by the remaining flow rate to obtain the additional flow rate allocated to that gun.

[0083] Ultimately, the final allocated flow rate of the charging gun equals the minimum sustaining flow rate plus the additional allocated flow rate. For charging guns forced to the minimum sustaining flow rate, their initial final flow rate, which was originally lower than the minimum sustaining flow rate, has been forcibly increased to the minimum sustaining flow rate. Therefore, the difference is zero, and they no longer participate in the redistribution of remaining flow rate; their final allocated flow rate is the minimum sustaining flow rate. Through the above-mentioned secondary baseline correction, the final allocated flow rate satisfies the minimum sustaining flow rate requirements of all charging guns while achieving on-demand flow rate allocation within the total pump capacity. High-load guns can obtain more additional flow rate, while low-load guns remain at a lower base flow rate level.

[0084] Furthermore, the duty cycle control signals for the solenoid valves of each charging gun circuit are generated to synchronously adjust the speed of the main cooling pump and perform coolant distribution equalization control, including: Obtain the final allocated flow rate of each charging gun, and convert each final allocated flow rate into a corresponding duty cycle control signal according to the flow rate-duty cycle calibration relationship of the solenoid valve of each charging gun circuit; The calibration process for the flow-duty cycle calibration relationship includes: During the commissioning phase of the charging pile, the solenoid valve is placed at multiple different duty cycle test points, and the actual flow rate of the coolant in the branch corresponding to each test point is measured. Multiple sets of corresponding points of duty cycle and flow rate are connected by piecewise linear interpolation to form an inverse mapping function from flow rate to duty cycle. The inverse mapping function is stored in the controller as the flow rate-duty cycle calibration relationship. The total required flow rate is obtained by summing the final allocated flow rates of all charging guns. Collect the current actual output flow rate of the main cooling pump and calculate the deviation between the total required flow rate and the actual output flow rate; Adjust the speed control signal of the main cooling pump according to the deviation value so that the actual output flow rate is close to the total demand flow rate; The duty cycle control signal is output to the solenoid valve of the corresponding charging gun circuit, and the speed control signal is output to the drive device of the main cooling pump to perform coolant distribution equalization control.

[0085] First, the final allocated flow rate of each charging gun is obtained, and then converted into a corresponding duty cycle control signal according to the flow rate-duty cycle calibration relationship of the solenoid valves in each charging gun's circuit. The solenoid valves control the opening and closing time ratio of the valves by adjusting the duty cycle, thereby adjusting the coolant flow rate through the branch. The flow rate-duty cycle calibration relationship maps the final allocated flow rate to a duty cycle percentage signal that the solenoid valve controller can recognize; for example, 0% corresponds to the valve being fully closed, and 100% corresponds to the valve being fully open.

[0086] The calibration process for the flow rate-duty cycle calibration relationship is as follows: During the charging pile commissioning phase, the solenoid valve is placed at multiple different duty cycle test points, for example, setting the duty cycle to 20%, 40%, 60%, 80%, and 100% respectively. A flow meter is used to measure the actual flow rate of the coolant in the corresponding branch at each test point. Multiple sets of corresponding points of duty cycle and flow rate are plotted as a scatter plot, and piecewise linear interpolation is used to connect adjacent test points to form a continuous mapping curve.

[0087] Piecewise linear interpolation is a method that approximates the mapping relationship between two adjacent known test points by connecting them with straight line segments. Specifically, it is implemented through the following steps: First, the duty cycle test points are sorted from smallest to largest, for example, 20%, 40%, 60%, 80%, 100%. Then, two adjacent test points and their corresponding flow rates are defined as the two endpoints of a line segment. For any target flow rate value between the two endpoints, the corresponding duty cycle is calculated using a linear interpolation formula. Specifically, the ratio of the difference between the target flow rate and the flow rate at the left endpoint to the difference between the flow rates at the right endpoint and the flow rate at the left endpoint is calculated. This ratio is then multiplied by the difference in duty cycles between the left and right endpoints and added to the duty cycle at the left endpoint. Since the flow-duty cycle characteristics of a solenoid valve typically have a non-linear region, piecewise linear interpolation has higher fitting accuracy than single linear fitting and can more accurately reflect the true flow response characteristics of the solenoid valve in each opening range.

[0088] Specifically, the flow-duty cycle calibration relationship represents the deterministic mapping law between the coolant flow rates of the branches corresponding to different duty cycle openings of the solenoid valve. It serves as the basis for converting the theoretically calculated final distribution flow rate into an actual executable solenoid valve control signal. When used for real-time control, it allows for the rapid and accurate determination of the required duty cycle control signal for each solenoid valve based on the target flow rate value, ensuring that the actual flow rate of each branch is as close as possible to the final distribution flow rate.

[0089] Furthermore, the final allocated flow rates of all charging guns are summed to obtain the total required flow rate. The total required flow rate reflects the sum of coolant flow rates needed to activate all charging guns within the current control cycle and serves as the basis for adjusting the main cooling pump speed. Next, the current actual output flow rate of the main cooling pump is collected, and the deviation between the total required flow rate and the actual output flow rate is calculated. The deviation value equals the total required flow rate minus the actual output flow rate. When the deviation value is positive, it indicates that the actual output flow rate is insufficient, and the pump speed needs to be increased; when the deviation value is negative, it indicates that the actual output flow rate is excessive, and the pump speed needs to be decreased.

[0090] Furthermore, the speed control signal of the main cooling pump is adjusted based on the deviation value to make the actual output flow rate approach the total demand flow rate, including: Based on a preset proportion of the total demand flow, obtain the allowable threshold for flow error; Compare the absolute value of the deviation with the allowable threshold for flow error. If the absolute value is not greater than the allowable threshold for flow error, then keep the current speed control signal unchanged. If the deviation value is positive, the speed control signal is increased, and the increase is proportional to the magnitude of the deviation value. If the deviation value is negative, the speed control signal is reduced, and the reduction is proportional to the absolute value of the deviation value. The adjusted speed control signal is output to the drive unit of the main cooling pump; Repeat the process of comparison, increase or decrease, and output until the absolute value of the deviation is not greater than the allowable threshold for flow error.

[0091] First, based on a preset percentage of the total demand flow rate, a flow rate error tolerance threshold is obtained. This preset percentage is typically determined during the charging pile commissioning phase based on the system's control accuracy requirements; for example, it can be set to 5%. The flow rate error tolerance threshold equals the total demand flow rate multiplied by this preset percentage, representing the allowable deviation range between the actual output flow rate of the cooling pump and the target flow rate. For example, if the total demand flow rate is 40 liters per minute and the preset percentage is 5%, then the flow rate error tolerance threshold is 2 liters per minute. When the deviation between the actual flow rate and the target flow rate is within 2 liters per minute, the cooling pump's output is considered to meet the requirements and no adjustment is needed.

[0092] Secondly, compare the absolute value of the deviation with the allowable threshold for flow error. The absolute value of the deviation is the absolute value of the difference between the actual output flow and the total required flow, regardless of the sign. If the absolute value is not greater than the allowable threshold for flow error, it indicates that the deviation between the current actual output flow and the target flow is within the allowable range and meets the requirements. Therefore, the current speed control signal should be kept unchanged, and no adjustment is needed.

[0093] Furthermore, if the deviation value is positive, meaning the total demand flow is greater than the actual output flow, it indicates that the actual output flow is insufficient, requiring increased cooling capacity. In this case, the speed control signal should be increased, with the increase proportional to the magnitude of the deviation value. The larger the deviation value, the greater the flow shortfall, and the more significantly the pump speed needs to be increased.

[0094] Optionally, the proportional coefficient between the amplitude of the speed control signal and the deviation value can be calibrated during the commissioning phase. For example, the proportional coefficient can be set to increase the rated speed by 2% per liter per minute of deviation. Let the deviation between the total demand flow and the actual output flow be ΔQ, in liters per minute, and the pump's rated speed be N. max The increase in speed is equal to ΔQ multiplied by the proportional coefficient, then divided by the rated speed to convert it to a percentage of speed. The final speed control signal is equal to the current speed plus this increase. For example, if the deviation is 3 liters per minute, the proportional coefficient is 2% of the rated speed per liter per minute, and the rated speed is 3000 rpm, then the speed increase is 3 multiplied by 2%, which equals 6%, corresponding to an increase of 180 rpm. The new speed control signal is the current speed plus 180 rpm. To prevent speed over-limit, the final speed must be limited between the pump's minimum speed and rated speed.

[0095] If the deviation value is negative, meaning the total demand flow is less than the actual output flow, it indicates that the actual output flow is excessive, resulting in wasted pumping energy. In this case, the speed control signal should be reduced, and the reduction should be proportional to the absolute value of the deviation. The larger the absolute value of the deviation, the more severe the excess flow, and the more significantly the pump speed needs to be reduced to save energy.

[0096] Optionally, let the absolute value of the deviation, |ΔQ|, equal the actual output flow rate minus the total demand flow rate. The proportionality coefficient is also set to 2% of the rated speed reduction per liter per minute corresponding to the deviation. Then, the speed reduction is equal to |ΔQ| multiplied by the proportionality coefficient, divided by the rated speed to convert it to a speed percentage. The final speed control signal is equal to the current speed minus this reduction. For example, if the actual output flow rate is 30 liters per minute, the total demand flow rate is 25 liters per minute, the deviation is -5 liters per minute, the absolute value is 5 liters per minute, the proportionality coefficient is 2% of the rated speed per liter per minute, and the rated speed is 3000 rpm. Then, the speed reduction is 5 multiplied by 2%, equal to 10%, corresponding to a speed reduction of 300 rpm. The new speed control signal is the current speed minus 300 rpm. Through this quantitative adjustment mechanism, the cooling pump speed can adaptively adjust according to the flow deviation, allowing the actual output flow rate to quickly and stably approach the total demand flow rate, while avoiding unnecessary pumping energy waste.

[0097] Finally, the adjusted speed control signal is output to the drive unit of the main cooling pump. The drive unit changes the pump motor speed according to the received signal, thereby adjusting the actual output flow.

[0098] Simultaneously, the process of comparing, increasing or decreasing, and outputting is repeated until the absolute value of the deviation is no greater than the allowable threshold for flow error. This cooling pump speed regulation is a continuous control process. After each adjustment, the actual output flow is re-acquired, a new deviation value is calculated, and the comparison and adjustment are repeated. This iterative process continues until the deviation between the actual output flow and the total demand flow is reduced to within the allowable threshold. At this point, the current speed control signal remains unchanged.

[0099] Through the closed-loop regulation mechanism based on the error allowable threshold, the main cooling pump can automatically adjust its speed according to the change in total demand flow, thereby minimizing the pump's energy consumption while meeting the flow requirements of each branch.

[0100] Furthermore, the duty cycle control signal is output to the solenoid valves of the corresponding charging gun circuits, while the speed control signal is output to the drive unit of the main cooling pump to perform coolant distribution equalization control. The solenoid valves control the opening and closing time ratio of their valve cores according to the received duty cycle signal, ensuring that the actual flow rate in each branch approaches the final distributed flow rate; the main cooling pump adjusts its motor speed according to the speed control signal, ensuring that the pump's actual output flow rate approaches the total demand flow rate. Working together, these two mechanisms ultimately achieve precise, dynamic, and balanced coolant distribution among the charging guns.

[0101] In summary, through the above closed-loop control, coolant can be delivered to the high-load charging gun as needed while taking into account the main pump's liquid supply capacity, and over-cooling of the low-load gun can be avoided.

[0102] In summary, the embodiments of this application have at least the following technical effects: This invention first calculates the real-time heat generation rate based on the real-time charging power, inlet liquid temperature, and outlet liquid temperature of each charging gun, achieving real-time quantitative perception of cable heat generation and providing a data foundation for differentiated coolant allocation. Second, it predicts the cumulative heat load based on the real-time heat generation rate and introduces heat capacity lag time for phase compensation, generating the expected heat dissipation demand. This overcomes the control response delay problem caused by heat transfer lag, ensuring that flow allocation is synchronized with the actual heat load change trend of the cable. Third, it allocates flow based on the expected heat dissipation demand, combined with a minimum maintenance flow rate for baseline correction. Simultaneously, it uses a dynamic lag compensation factor based on cable sheath temperature feedback to rebalance the flow, ensuring that high-load guns receive sufficient cooling and low-load guns avoid over-cooling, achieving adaptive matching between coolant allocation and charging power. Finally, it generates duty cycle control signals for the solenoid valves of each gun's circuit and synchronously adjusts the total cooling pump speed, precisely executing the flow allocation command and significantly reducing the pumping energy consumption of the cooling system while ensuring the safety of the high-load charging gun cable.

[0103] This invention solves the technical problems of cooling supply and demand mismatch, energy waste and overheating risk in the prior art.

Claims

1. A method for balanced control of cable coolant distribution in distributed liquid-cooled charging piles, characterized in that, The method includes: The real-time charging power of each charging gun in the distributed liquid-cooled charging pile is obtained, and the real-time heat generation rate of each charging gun is calculated by combining the inlet liquid temperature and outlet liquid temperature of the corresponding cable. Based on the real-time heat generation rate, the cumulative heat load of each charging gun in the current charging cycle is predicted, and phase compensation is performed on each of the cumulative heat loads based on the thermal capacity lag time to generate the expected heat dissipation demand of each charging gun. Using the expected heat dissipation demand as the allocation weight and combined with the upper limit of the available flow rate of the total pump, the initial allocation flow rate of each charging gun is calculated, and the initial allocation flow rate is corrected based on the minimum maintenance flow rate required for cooling the charging gun to obtain the feasible allocation flow rate. Collect the cable sheath temperature corresponding to each charging gun, calculate the temperature difference attenuation rate between the cable sheath temperature and the corresponding rated operating temperature, and correct the thermal capacity hysteresis time based on the temperature difference attenuation rate to obtain the dynamic hysteresis compensation factor. The feasible distribution flow is rebalanced and corrected using the dynamic hysteresis compensation factor, the final distribution flow is output, and the duty cycle control signal of the solenoid valve of each charging gun circuit is generated to synchronously adjust the speed of the main cooling pump and perform coolant distribution balancing control.

2. The cable coolant distribution equalization control method for distributed liquid-cooled charging piles according to claim 1, characterized in that, Obtain the real-time charging power of each charging gun in the distributed liquid-cooled charging pile, and calculate the real-time heat generation rate of each charging gun by combining the inlet and outlet liquid temperatures of the corresponding cables, including: Collect the real-time charging power of each charging gun, and simultaneously record the inlet liquid temperature and outlet liquid temperature of the corresponding cable. Calculate the average reference flow rate based on the maximum available flow rate of the total pump and the total number of charging guns currently in active status; Using the average reference flow rate, coolant specific heat capacity, and the temperature difference between the inlet and outlet liquid temperatures, the heat power carried away by the coolant from the cable is calculated. Based on the real-time charging power and the equivalent resistance of the cable, the Joule heat power is calculated, and the rate of change of the cable sheath temperature is extracted. Combined with the cable heat capacity, the cable's own heat storage power is calculated. The real-time heat generation rate is obtained by adding the heat power carried away by the coolant from the cable to the heat storage power and incorporating a redundancy correction term for the Joule heat power, wherein the redundancy correction term is proportional to the deviation between the inlet liquid temperature and the cable sheath temperature.

3. The cable coolant distribution equalization control method for distributed liquid-cooled charging piles according to claim 1, characterized in that, Based on the real-time heat generation rate, the cumulative heat load of each charging gun in the current charging cycle is predicted, and phase compensation is performed on each of the cumulative heat loads based on the thermal capacity lag time to generate the expected heat dissipation demand of each charging gun, including: Starting from the current moment, the real-time heat generation rate sequence of each charging gun within the previous continuous time window is extracted in reverse. Linear regression is performed on the real-time heat generation rate sequence to obtain the slope of the change in heat generation rate, and the predicted value of the heat generation rate within the remaining charging time is extrapolated based on the slope of the change. The equivalent heat production rate is obtained by weighting the heat production rate at the end of the real-time heat production rate sequence with the predicted value. The accumulated heat load is determined based on the equivalent heat generation rate and the remaining charging time, combined with the accumulated heat load. Obtain the expected heat dissipation demand output from the previous control cycle, and record it as the historical heat dissipation demand; The thermal hysteresis time is determined based on the temperature difference between the cable sheath temperature and the rated operating temperature, wherein the thermal hysteresis time decreases as the temperature difference increases. The smoothing coefficient is determined based on the sampling period and the thermal hysteresis time. The expected heat demand for the current period is generated by weighting and fusing the equivalent heat generation rate and the historical heat discharge demand using the smoothing coefficient.

4. The cable coolant distribution equalization control method for distributed liquid-cooled charging piles according to claim 3, characterized in that, Perform linear regression on the real-time heat generation rate sequence to obtain the slope of the heat generation rate change, and extrapolate the predicted heat generation rate value for the remaining charging time based on the slope of the change, including: Each rate value in the real-time heat generation rate sequence is assigned a sequential index number, which is used as a time coordinate. Calculate the rate average of the real-time heat generation rate sequence and the index average of the sequence index number; The slope of change is calculated based on the sum of the products of the average rate, the average index, and the deviations between each rate value and its corresponding index number in the real-time heat production rate sequence. The predicted value of the heat generation rate is calculated based on the change slope, the rate value at the end of the real-time heat generation rate sequence, and the remaining charging time.

5. The cable coolant distribution equalization control method for distributed liquid-cooled charging piles according to claim 1, characterized in that, Using the expected heat dissipation demand as the allocation weight and combining it with the upper limit of the total pump's available flow rate, the initial allocation flow rate for each charging gun is calculated. Then, a minimum maintenance flow rate is applied to the initial allocation flow rate based on the minimum sustaining flow rate required for cooling the charging gun to obtain a feasible allocation flow rate, including: Iterate through all the active charging guns, sum up the expected heat dissipation requirements of each charging gun, and get the total demand. The normalized weight of each charging gun is obtained by dividing the expected heat dissipation requirement of each charging gun by the total requirement. The initial allocated flow rate for each charging gun is determined based on the normalized weight of each charging gun and the upper limit of the total pump available flow rate. The minimum sustaining flow rate for each charging gun is obtained by reading the rated technical parameters of each charging gun. Calculate the sum of the minimum sustaining flow rates of all charging guns. If the sum of the minimum sustaining flow rates is greater than the upper limit of the total pump available flow rate, reduce the allocated flow rate of each charging gun according to the ratio of the minimum sustaining flow rate, so that the reduced sum is equal to the upper limit of the total pump available flow rate, and use the reduced result as the feasible allocated flow rate. If the sum of the minimum maintenance flow rates is not greater than the upper limit of the total pump available flow rate, then for each charging gun, the difference between the initial allocated flow rate and the minimum maintenance flow rate is calculated, and those with negative differences are set to zero. The remaining flow rate is obtained by subtracting the sum of the minimum maintenance flow rates from the upper limit of the total pump's available flow rate. The remaining flow rate is then allocated proportionally according to the difference between each charging gun. Finally, the minimum maintenance flow rate of each charging gun is added to the allocated remaining flow rate to obtain the feasible allocation flow rate.

6. The cable coolant distribution equalization control method for distributed liquid-cooled charging piles according to claim 1, characterized in that, Collect the cable sheath temperature corresponding to each charging gun, calculate the temperature difference attenuation rate between the cable sheath temperature and the corresponding rated operating temperature, and correct the thermal hysteresis time based on the temperature difference attenuation rate to obtain the dynamic hysteresis compensation factor, including: Collect the cable sheath temperature corresponding to each charging gun and obtain the rated operating temperature corresponding to each charging gun. Calculate the difference between the rated operating temperature and the cable sheath temperature, and divide it by the difference between the rated operating temperature and the room temperature to obtain the temperature difference attenuation rate. The thermal capacity lag time of the current control cycle is obtained, and a dynamic lag compensation factor is determined based on the thermal capacity lag time and the temperature difference decay rate, wherein the dynamic lag compensation factor decreases as the temperature difference decay rate increases. When the temperature difference decay rate is lower than the lower limit of the decay rate, the dynamic hysteresis compensation factor is fixed as the product of the heat capacity hysteresis time and the reciprocal of the lower limit of the decay rate, wherein the lower limit of the decay rate is the weighted average of the temperature difference decay rate of the previous control cycle and the current temperature difference decay rate.

7. The cable coolant distribution equalization control method for distributed liquid-cooled charging piles according to claim 1, characterized in that, The feasible allocation flow is rebalanced and corrected using the dynamic lag compensation factor to output the final allocation flow, including: Based on the expected heat dissipation requirements of each charging gun, calculate the average heat dissipation requirements of all active charging guns, and mark the charging guns whose expected heat dissipation requirements are greater than the average heat dissipation requirements as high-load guns. For each high-load gun, obtain the corresponding temperature difference attenuation rate and the dynamic hysteresis compensation factor, and calculate the rebalancing coefficient, wherein the rebalancing coefficient decreases as the temperature difference attenuation rate increases and increases as the dynamic hysteresis compensation factor increases. Multiply the feasible distribution flow of the high-load gun by the rebalancing coefficient to obtain the rebalanced distribution flow; For non-high load guns, the feasible allocation flow is kept unchanged as the rebalanced allocation flow. Based on the relative magnitude of the upper limit of the available flow rate of the total pump and the sum of the distributed flow rates after rebalancing of each charging gun, the distributed flow rates of each charging gun after rebalancing are scaled proportionally so that the scaled sum is equal to the upper limit of the available flow rate of the total pump, and the scaled result is used as the final distributed flow rate of each charging gun.

8. The cable coolant distribution equalization control method for distributed liquid-cooled charging piles according to claim 7, characterized in that, Based on the relative magnitude of the upper limit of the total pump's available flow rate and the sum of the rebalanced distribution flow rates of each charging gun, the rebalanced distribution flow rates of each charging gun are scaled proportionally so that the scaled sum equals the upper limit of the total pump's available flow rate. The scaled result is then used as the final distribution flow rate of each charging gun, including: The total rebalancing flow is obtained by summing the distributed flow after rebalancing of all charging guns. Calculate the ratio of the upper limit of the total available flow rate of the pump to the sum of the rebalancing flow rates, and denot it as the scaling factor; The distribution flow of each charging gun after rebalancing is adjusted according to the scaling factor to obtain the preliminary final flow, wherein the preliminary final flow increases as the scaling factor increases; Iterate through the initial final flow rate of each charging gun. If there is a charging gun with a flow rate lower than the minimum sustaining flow rate, then force the initial final flow rate of the charging gun with a flow rate lower than the minimum sustaining flow rate to be set to the minimum sustaining flow rate. Calculate the sum of the minimum sustaining flow rates of all charging guns. If the sum of the minimum sustaining flow rates is greater than the upper limit of the total pump available flow rate, reduce the allocated flow rate of each charging gun according to the proportion of the minimum sustaining flow rate, so that the reduced sum is equal to the upper limit of the total pump available flow rate, and use the reduced result as the final allocated flow rate of each charging gun. If the sum of the minimum sustaining flow rates is not greater than the upper limit of the total available flow rate of the pump, then the upper limit of the total available flow rate of the pump is subtracted from the sum of the minimum sustaining flow rates to obtain the remaining flow rate; For charging guns where the initial final flow rate is not lower than the minimum maintenance flow rate, the remaining flow rate is allocated proportionally based on the difference between the initial final flow rate and the minimum maintenance flow rate, and the allocated flow rate is added to the minimum maintenance flow rate to obtain the final allocated flow rate for each charging gun. For a charging gun that is forced to be set to the minimum sustaining flow rate, the corresponding final allocated flow rate is the minimum sustaining flow rate.

9. The cable coolant distribution equalization control method for distributed liquid-cooled charging piles according to claim 1, characterized in that, Generate duty cycle control signals for the solenoid valves of each charging gun circuit, synchronously adjust the speed of the main cooling pump, and perform coolant distribution equalization control, including: Obtain the final allocated flow rate of each charging gun, and convert each final allocated flow rate into a corresponding duty cycle control signal according to the flow rate-duty cycle calibration relationship of the solenoid valve of each charging gun circuit; The calibration process for the flow-duty cycle calibration relationship includes: During the commissioning phase of the charging pile, the solenoid valve is placed at multiple different duty cycle test points, and the actual flow rate of the coolant in the branch corresponding to each test point is measured. Multiple sets of corresponding points of duty cycle and flow rate are connected by piecewise linear interpolation to form an inverse mapping function from flow rate to duty cycle. The inverse mapping function is stored in the controller as the flow rate-duty cycle calibration relationship. The total required flow rate is obtained by summing the final allocated flow rates of all charging guns. Collect the current actual output flow rate of the main cooling pump and calculate the deviation between the total required flow rate and the actual output flow rate; Adjust the speed control signal of the main cooling pump according to the deviation value so that the actual output flow rate is close to the total demand flow rate; The duty cycle control signal is output to the solenoid valve of the corresponding charging gun circuit, and the speed control signal is output to the drive device of the main cooling pump to perform coolant distribution equalization control.

10. The cable coolant distribution equalization control method for distributed liquid-cooled charging piles according to claim 9, characterized in that, Adjusting the main cooling pump speed control signal according to the deviation value to make the actual output flow rate approach the total demand flow rate includes: Based on a preset proportion of the total demand flow, obtain the allowable threshold for flow error; Compare the absolute value of the deviation with the allowable threshold for flow error. If the absolute value is not greater than the allowable threshold for flow error, then keep the current speed control signal unchanged. If the deviation value is positive, the speed control signal is increased, and the increase is proportional to the magnitude of the deviation value. If the deviation value is negative, the speed control signal is reduced, and the reduction is proportional to the absolute value of the deviation value. The adjusted speed control signal is output to the drive unit of the main cooling pump; Repeat the process of comparison, increase or decrease, and output until the absolute value of the deviation is not greater than the allowable threshold for flow error.

Images