Die-casting cooling water supply method and system based on variable-frequency constant-pressure control

Abstract

The invention relates to the technical field of industrial fluid control, and discloses a die-casting cooling water supply method and system based on variable-frequency constant-pressure control, and the method comprises the steps: collecting process time sequence data and die thermal state data of a die-casting machine in real time; based on the heat flow coupling model, predicting the total water demand of the system in a future time window; decoupling the predicted variable quantity of the water demand, and generating a feedforward control instruction aiming at the main water supply unit and a transient compensation instruction aiming at the active pressure compensation unit; and finally, driving the main water supply unit and the active pressure compensation unit to cooperatively act through a composite control framework combining feedforward control and real-time pressure feedback correction. Through feedforward prediction and dual-channel cooperative control, load disturbance can be actively dealt with, the system pressure stability and the water supply accuracy are remarkably improved, energy consumption is reduced, and the problem that the pressure of a water supply pipe network fluctuates severely due to frequent opening and closing of a cooling loop valve in die-casting production is solved.

Description

Technical Field

[0001] This invention relates to the field of industrial fluid control technology, specifically to a method and system for supplying cooling water to die casting based on variable frequency constant pressure control. Background Technology

[0002] In the die-casting process, precise cooling of the mold is necessary to ensure stable mold temperature and casting quality. This typically relies on a centralized cooling water supply system to provide cooling water at a stable pressure. Currently, such systems commonly employ variable frequency constant pressure control technology. This technology uses pressure sensors installed in the pipeline network to compare the actual pressure values ​​with target values. Once a deviation is identified, the frequency converter is used to adjust the water pump speed to maintain constant pipeline pressure.

[0003] However, the production characteristics of a die-casting workshop involve multiple die-casting machines operating in parallel, with their cooling circuits controlled by numerous solenoid valves. These valves are often opened and closed in a concentrated or instantaneous manner according to the process sequence. This causes a drastic step change in the total water demand of the system within a very short time, creating a strong load disturbance on the water supply system. Traditional variable frequency constant pressure control methods exhibit inherent lag in response to such sudden load changes. This is because the control system can only begin adjusting after detecting a pressure change, and the mechanical inertia of the pump units and the response speed of the frequency converter limit its adjustment capability, making it unable to instantaneously follow changes in water demand. Therefore, significant instantaneous drops or overshoots in the pipeline pressure are inevitable. These pressure fluctuations not only affect the stability of the flow rate in each cooling circuit, thus adversely affecting product quality, but may also trigger water hammer effects in the pipeline, damaging equipment safety. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method and system for supplying cooling water for die casting based on variable frequency constant pressure control. This solves the problem that the variable frequency constant pressure control method used in existing technologies can only perform lag adjustment based on pressure feedback, making it difficult to effectively cope with the severe water demand impact caused by the concentrated opening and closing of valves in the die casting process, which leads to significant fluctuations in pipeline pressure.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for supplying cooling water to die-casting based on variable frequency constant pressure control, comprising the following steps: S1. Perform system initialization and model building to obtain the baseline process parameters and control model parameters required for system operation; S2. Real-time sensing system for the entire operating status, collecting and synchronously processing process timing data, mold thermal status data and water supply network hydraulic status data from multiple die-casting machines; S3. Based on the heat-fluid coupling model, predict the water demand and calculate the total predicted water demand of the system within the future prediction time window by combining the process time sequence data and the mold thermal state data. S4. Decouple and generate dual-channel control commands. Based on the total predicted water demand of the system, decouple and generate feedforward control commands for the main water supply unit and transient compensation commands for the active pressure compensation unit, respectively. S5. Perform composite control and closed-loop correction, drive the main water supply unit and the active pressure compensation unit to perform coordinated actions according to the generated instructions, and perform closed-loop correction of the control instructions based on real-time pressure feedback.

[0006] Preferably, in step S3, based on the deviation between the measured temperature and the target process temperature in the mold thermal state data, the basic set flow rate of the cooling circuit is corrected, and the dynamic predicted flow rate is calculated; and the dynamic predicted flow rates of all cooling circuits predicted to be in the open state are summarized to obtain the total predicted water demand of the system.

[0007] Preferably, in the step of correcting the basic set flow rate of the cooling circuit, when the measured temperature is higher than the target process temperature, the dynamic predicted flow rate is greater than the basic set flow rate; when the measured temperature is lower than the target process temperature, the dynamic predicted flow rate is less than the basic set flow rate.

[0008] Preferably, in step S4, the transient compensation flow that needs to be compensated by the active pressure compensation unit is determined by comparing the predicted change in the system's water demand with the maximum flow change that the main water supply unit can respond to and adjust within the future prediction time window.

[0009] Preferably, in the step of determining the transient compensation flow rate, when the predicted change in the system water demand is greater than the maximum flow rate change of the main water supply unit, the difference between the predicted change in the system water demand and the maximum flow rate change of the main water supply unit is determined as the transient compensation flow rate.

[0010] Preferably, step S4 further includes: generating a feedforward control command for the main water supply unit based on the total predicted water demand of the system and the flow frequency characteristic function of the main water supply unit.

[0011] Preferably, in step S5, by including an execution timestamp corresponding to the time of occurrence of a future event in the transient compensation instruction, the transient compensation action of the active pressure compensation unit is triggered when the execution timestamp arrives.

[0012] Preferably, in step S5, the composite control and closed-loop correction includes: Calculate the deviation between the actual pressure value of the water supply network and the preset target pressure value, and generate a feedback correction command; The feedforward control command and the feedback correction command are superimposed to form the final control command; The main water supply unit is driven to make adjustments according to the final control command.

[0013] Preferably, in step S1, the reference process parameters include the basic set flow rate and target process temperature of each cooling circuit; the control model parameters include the thermal compensation sensitivity coefficient, the flow frequency characteristic function of the main water supply unit, and the response model of the active pressure compensation unit.

[0014] A die-casting cooling water supply system based on variable frequency constant pressure control includes: The data acquisition module is used to collect and process process timing data, mold thermal status data and water supply network hydraulic status data from multiple die-casting machines in real time. The water demand prediction and command decoupling module is connected to the data acquisition module and is used to: calculate the total predicted water demand of the system within the future prediction time window based on the process timing data and the mold thermal state data; and decouple and generate feedforward control commands for the main water supply unit and transient compensation commands for the active pressure compensation unit based on the total predicted water demand of the system. The composite control and correction module, connected to the water demand prediction and command decoupling module and the data acquisition module, is used to: generate feedback correction commands based on the hydraulic state data of the water supply network, superimpose the feedforward control commands and the feedback correction commands to form a final control command, and output the final control command to the main water supply unit and output the transient compensation command to the active pressure compensation unit.

[0015] This invention provides a method and system for supplying cooling water to die-casting plants based on variable frequency constant pressure control. It offers the following advantages: 1. This invention significantly improves the pressure stability of the die-casting cooling water supply system by establishing a heat-fluid coupling water demand prediction model and combining it with a method of decoupling and generating dual-channel control commands. This method predicts changes in system water demand in advance by collecting process sequence and mold thermal state data in real time, and decomposes them into slow and fast control components processed by the main water supply unit and the active pressure compensation unit, respectively. This feedforward collaborative compensation mechanism can actively respond to rather than passively respond to load disturbances caused by centralized valve switching, effectively suppressing the large pressure fluctuations and overshoot phenomena commonly found in traditional feedback control.

[0016] 2. The method of this invention incorporates the real-time thermal state of the mold into the water demand prediction model, enhancing the accuracy and process adaptability of the cooling water supply. By introducing a thermal compensation coefficient, the system can dynamically correct the basic set flow rate of each cooling circuit based on the deviation between the measured temperature of the mold and the target process temperature. This allows the water supply flow rate to not only respond to the opening and closing of the valves, but also to adapt to the actual thermal load changes of the mold, thus meeting the cooling requirements while avoiding local overcooling or overheating, which helps to improve the molding quality of die-cast parts and the consistency of the production process.

[0017] 3. This invention employs a composite control architecture combining feedforward prediction and feedback correction, which helps reduce energy consumption and equipment wear in the main water supply unit. Because feedforward control handles most predictable load fluctuations in the system, the supplementary feedback correction stage only needs to address small residual deviations. This allows the frequency converter of the main water supply unit to avoid frequent, wide-range speed adjustments, enabling it to operate under more stable and efficient conditions. Simultaneously, the absorption of instantaneous impacts by the active pressure compensation unit reduces the water hammer effect in the pipeline network, lessens mechanical impact on pipes, valves, and other components, and extends the service life of the equipment. Attached Figure Description

[0018] Figure 1 This is an overall flowchart of the control method of the present invention; Figure 2 This is a schematic diagram of the overall system architecture of the present invention. Detailed Implementation

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

[0020] Example: Please see the appendix Figure 1 This invention provides a method for supplying cooling water to die-casting based on variable frequency constant pressure control, comprising the following steps: S1. Perform system initialization and model building. This step is performed before the system runs to obtain the baseline process parameters and control model parameters required for system operation.

[0021] S2. Real-time perception of the overall system operation status. This step is executed continuously during system operation and is used to collect and synchronously process process timing data, mold thermal status data, and hydraulic status data of the water supply network from multiple die-casting machines.

[0022] S3. Water demand prediction based on the heat-fluid coupling model. This step uses the real-time status data collected in step S2 to run the prediction model and calculate the total water demand of the system within the future prediction time window.

[0023] S4. Decoupling and generating dual-channel control commands. Based on the water demand prediction results in step S3, this step decouples and generates feedforward control commands for the main water supply unit and transient compensation commands for the active pressure compensation unit.

[0024] S5. Perform composite control and closed-loop correction. This step drives the main water supply unit and the active pressure compensation unit to work together according to the instructions generated in step S4, and performs closed-loop correction of the control instructions based on real-time pressure feedback.

[0025] In step S1, system initialization and model building specifically include setting the system's physical parameters and process baselines, as well as initializing the predictive and control models. This process is executed by the central control unit, providing basic data, mathematical models, and initial conditions for subsequent online predictive and control.

[0026] This process may include the following steps: Establish digital profiles for die-casting equipment and cooling circuits. In the central control unit, assign a unique digital identifier to each die-casting machine in the die-casting workshop, and assign a unique subordinate digital identifier to each cooling circuit within each die-casting machine, controlled by an independent solenoid valve. Through this hierarchical identification, the system can precisely correlate and control data for individual cooling water circuits.

[0027] Configure the process baseline parameters for each cooling loop. For each established digital profile of a cooling loop, configure its core process parameters. These parameters should include at least: Basic setting flow This parameter is for the cooling circuit. Cooling water flow rate designed under standard die-casting process. For the digital identification of the die-casting machine, This is the digital identifier for the cooling circuit of the die-casting machine. This value serves as the calculation basis for subsequent dynamic flow correction.

[0028] Target process temperature This parameter is related to the cooling circuit. Key temperature measurement points of the mold related to heat exchange The system supports linking one or more temperature measurement points to a cooling loop. This allows for a comprehensive consideration of the status of multiple temperature measurement points based on process requirements, and also supports multiple cooling loops working together to achieve the target temperature at each measurement point. This parameter setting establishes a direct link between fluid control and the thermal state target.

[0029] Establish a mapping relationship between process timing signals and valve actions. To enable the central control unit to predict the opening and closing actions of valves in each cooling circuit, it is necessary to establish a mapping between the process timing signals output by the die-casting machine's programmable logic controller (PLC) and the physical actions of the valves. This will control specific cooling circuits. The PLC output position signal indicating the on / off state of the solenoid valve coil is bound to the open and closed states defined in the circuit file. Those skilled in the art can establish this mapping relationship using industrial bus protocol communication or I / O hardwired signal acquisition methods.

[0030] Set the compensation parameters for the thermal-fluid coupling model. To establish a quantitative relationship between the real-time thermal state of the mold and the cooling water flow rate requirement, the compensation parameters in the model need to be set. These parameters define the functional relationship between the deviation of the measured mold temperature from the target process temperature and the required adjustment range of the dynamic flow rate. This functional relationship can be set as linear, and its core parameter is the thermal compensation sensitivity coefficient. The physical meaning of this coefficient is related to the cooling circuit. Associated temperature measurement points For each unit of temperature deviation from the target value, the rate of change of the flow demand of this loop relative to its baseline set flow rate. This coefficient... It can be determined based on the thermodynamic simulation of the mold, statistical analysis of historical production data, or empirical calibration.

[0031] Establish the flow-frequency characteristic function of the main water supply unit. To achieve precise feedforward control of the main water supply unit's output flow, it is necessary to establish a mapping relationship between the inverter's operating frequency and the actual output flow. This relationship can be established through the characteristic function. To represent. Among them, Output traffic to the target. This refers to the target operating frequency of the frequency converter. This characteristic function can be obtained by performing offline calibration tests on the main water supply unit.

[0032] Configure the response model of the active pressure compensation unit. To achieve accurate compensation for instantaneous pressure fluctuations, it is necessary to establish a response model between the control commands and physical actions of the active pressure compensation unit. This model can be derived from the response function. To represent. Among them, This is the compensation flow required for APCU to handle instantaneous throughput; it can be a positive or negative value. This refers to the specific execution instructions sent to the APCU controller. The establishment of this response model ensures that the compensation flow requirements calculated by the upper-layer algorithm can be accurately translated into physical actions by the underlying hardware.

[0033] After initialization, the system enters the online operation phase. In step S2, the system monitors the overall operational status in real time. This process specifically includes the acquisition and synchronization of data on process timing, mold thermal status, and pipeline hydraulic status. This process provides real-time, accurate, and time-consistent input data for the subsequent water demand prediction model.

[0034] Acquire process timing data. Through die-casting machine interface modules deployed on each die-casting machine side, real-time acquisition of switching signals output by the die-casting machine PLC, directly corresponding to the actions of the solenoid valves in each cooling circuit. When a change in the state of the switching signal of any cooling circuit is detected, the interface module records the precise moment of occurrence of the event, forming time-stamped process timing data.

[0035] Collect mold thermal state data. Through the die-casting machine interface module, at a preset high sampling frequency, periodically collect signals output from temperature sensors installed at key locations on the mold and convert them into specific temperature values. The interface module appends a corresponding timestamp to each sampled data point, forming timestamped mold thermal state data. Sampling time, For die-casting machine markings, This is a temperature measurement point marker.

[0036] Event synchronization is performed. To ensure the consistency and strong correlation of the data used by subsequent prediction models, the collected data undergoes time synchronization. This time synchronization is achieved through a unified clock synchronization network, using either a network time protocol or a precise time protocol. This method ensures that all collected data is based on a unified time base, eliminating data misalignment issues caused by inconsistent clocks among different acquisition units.

[0037] Collect raw pressure signals from the main pipeline. Install pressure sensors at one or more locations along the main water supply pipeline that represent the overall pressure status of the pipeline network to continuously monitor the fluid pressure within the pipeline.

[0038] Pressure signal processing. The central control unit or dedicated data acquisition module performs digital filtering and moving average filtering on the acquired raw signals to suppress high-frequency noise, thereby generating a stable actual pressure value that reflects the true pressure of the pipeline network. ,in This refers to the current moment.

[0039] Attach a timestamp and transmit. This will provide the processed actual pressure value. A timestamp synchronized with the unified time base is attached and transmitted to the central control unit as real-time feedback for closed-loop correction in subsequent step S5.

[0040] In step S3, water demand is predicted based on a thermal-fluid coupling model. This process integrates deterministic timing information of the process with real-time dynamic information of the mold's thermal state to obtain an accurate predicted value that can characterize the total load of the entire die-casting cooling water system at future moments.

[0041] Predict the future state of the cooling circuit. The central control unit processes the collected process timing data and predicts the future state within a preset, extremely short future prediction time window. Within the system, all impending cooling circuit solenoid valve state transition events are identified. Based on the current moment... The status of each circuit and the upcoming transition events determine the cooling circuit. In the future The predicted state, i.e., on or off.

[0042] Calculate the thermal compensation coefficient. For each time predicted to occur in the future... Cooling circuit in the open state The central control unit is based on the collected temperature measurement points associated with the circuit. Real-time temperature data is used to calculate the thermal compensation coefficient for quantifying the flow rate adjustment range. This coefficient can be calculated using the following linear relationship: ; in: This is the thermal compensation sensitivity coefficient; Temperature measurement point At the present moment The measured temperature; Temperature measurement point The target process temperature.

[0043] Calculate the dynamically predicted flow rate. Based on the calculated thermal compensation coefficient, the central control unit adjusts the base set flow rate to a dynamically predicted flow rate that dynamically matches the real-time heat load. This correction is achieved through a predefined functional relationship that maps the base flow rate and thermal compensation coefficient to a dynamically predicted flow rate. This dynamically predicted flow rate can be calculated using the following formula: ; This calculation method ensures that when the measured temperature is higher than the target temperature, the dynamically predicted flow rate will be greater than the basic set flow rate to enhance the cooling effect; conversely, the flow rate will be reduced to avoid overcooling.

[0044] The system calculates the total predicted water demand. The central control unit combines the predicted status and dynamic predicted flow rates, and through summation, obtains the system's predicted water demand at future times. Total forecast water demand The calculation formula is as follows: ; in: This represents the total number of die-casting machines. For the first The total number of cooling circuits for the die-casting machine; For cooling circuit In the future The predicted state (1 for on, 0 for off).

[0045] In step S4, the dual-channel control commands are decoupled and generated. This process decomposes the predicted total water demand change into two control components executed by the main water supply unit and the active pressure compensation unit, respectively.

[0046] Generates the main pump frequency converter feedforward control command. This command is used to address macroscopic and low-frequency changes in system water demand, forming a slow control channel with a relatively slow response but a wide range of applications. The central control unit calculates the total predicted water demand. Substitute into the established flow frequency characteristic function In the process, the feedforward target operating frequency of the main water supply unit frequency converter is calculated. : ; The calculation system forecasts changes in water demand. The central control unit calculates the current time... The system's actual total water demand And the total projected water demand at future times. By comparing, we can obtain the prediction time window. Within, the total predicted change in system water demand .

[0047] Determine the transient compensation flow rate. This step aims to isolate high-frequency water demand fluctuations that the main water supply unit cannot keep up with in a timely manner due to its inherent response inertia, and allocate them to the fast-responding APCU for processing, forming a rapid control channel. The central control unit calculates the flow rate within the prediction time window based on the maximum frequency change rate preset by the main water supply unit's frequency converter. The maximum flow rate change that can be responded to and regulated internally. Total predicted change in system water demand With the maximum flow rate change Comparison: like This indicates that the main pump itself is sufficient to cope with the change, and the transient compensation flow rate is then... It is 0.

[0048] like This indicates that the change in water demand exceeds the instantaneous adjustment capacity of the main pump, and the difference is the transient compensation flow rate that needs to be quickly compensated by the active pressure compensation unit. ; in: This is a sign function; it outputs 1 when the input value is positive, -1 when it is negative, and 0 when it is zero.

[0049] Should It represents the high-frequency component in the change of water demand in the system.

[0050] Generate APCU execution instructions. The central control unit will calculate the transient compensation flow. As input, substitute it into the established APCU response model function. In the process, the specific execution instructions that need to be sent to the APCU to achieve this compensation traffic are calculated. : ; In step S5, composite control and closed-loop correction are performed.

[0051] Simultaneously distribute and execute dual-channel control commands. The central control unit will generate the feedforward target operating frequency. , and the generated APCU transient compensation execution instructions These instructions are simultaneously sent to their respective execution units. To achieve precise coordination, the execution instructions of the APCU can include information related to the timing of future events. The corresponding execution timestamps. Upon receiving the instruction, the main water supply unit begins gradual adjustment, while the APCU triggers a compensation action instantaneously when the local clock reaches the timestamp marked by the instruction. Through this mechanism, the APCU's rapid response precisely compensates for the main water supply unit's response delay at the moment of change in water demand, enabling the water supply system to smoothly and quickly follow changes in water demand.

[0052] Calculate real-time pressure deviation. The central control unit will collect real-time pipeline pressure values. , compared with the preset system target pressure value Compare and calculate the current time. pressure deviation .

[0053] Generate feedback correction commands. Adjust pressure deviation. As input, the signal is sent to the closed-loop feedback controller, which generates an adjustment to the operating frequency of the main water supply unit's frequency converter based on the magnitude, duration, and rate of change of the pressure deviation; this is known as a feedback correction command. .

[0054] The feedforward control command and the feedback correction command are combined to form the final control command, which is then sent to the main water supply unit frequency converter. The composite process is a linear superposition: ; By combining feedforward predictive control with real-time feedback correction, this invention forms a composite control architecture. The feedforward control channel handles most of the predictable load fluctuations in the system, while the feedback control channel, as a supplement, eliminates residual and unpredictable deviations, jointly ensuring the long-term stability and accuracy of the system pressure.

[0055] Please see the appendix Figure 2 A die-casting cooling water supply system based on variable frequency constant pressure control includes: The data acquisition module is used to collect and process process timing data, mold thermal status data and water supply network hydraulic status data from multiple die-casting machines in real time. The water demand forecasting and command decoupling module is connected to the data acquisition module and is used to: calculate the total predicted water demand of the system within the future prediction time window based on process timing data and mold thermal state data; and decouple and generate feedforward control commands for the main water supply unit and transient compensation commands for the active pressure compensation unit based on the total predicted water demand of the system. The composite control and correction module, connected to the water demand prediction and command decoupling module and the data acquisition module, is used to: generate feedback correction commands based on the hydraulic state data of the water supply network, superimpose feedforward control commands and feedback correction commands to form final control commands, and output the final control commands to the main water supply unit and output transient compensation commands to the active pressure compensation unit.

[0056] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for supplying cooling water to die-casting based on variable frequency constant pressure control, characterized in that, Includes the following steps: S1. Perform system initialization and model building to obtain the baseline process parameters and control model parameters required for system operation; S2. Real-time sensing system for the entire operating status, collecting and synchronously processing process timing data, mold thermal status data and water supply network hydraulic status data from multiple die-casting machines; S3. Based on the thermal-fluid coupling model, predict the water demand and calculate the total predicted water demand of the system within the future prediction time window by combining the process time sequence data and the mold thermal state data. S4. Decouple and generate dual-channel control commands. Based on the total predicted water demand of the system, decouple and generate feedforward control commands for the main water supply unit and transient compensation commands for the active pressure compensation unit, respectively. S5. Perform composite control and closed-loop correction, drive the main water supply unit and the active pressure compensation unit to perform coordinated actions according to the generated instructions, and perform closed-loop correction of the control instructions based on real-time pressure feedback.

2. The method for supplying cooling water for die casting based on variable frequency constant pressure control according to claim 1, characterized in that, In step S3, based on the deviation between the measured temperature and the target process temperature in the mold thermal state data, the basic set flow rate of the cooling circuit is corrected, and the dynamic predicted flow rate is calculated. The dynamic predicted flow rates of all cooling loops predicted to be in the open state are then aggregated to obtain the total predicted water demand of the system.

3. The method for supplying cooling water for die casting based on variable frequency constant pressure control according to claim 2, characterized in that, In the step of correcting the basic set flow rate of the cooling circuit, when the measured temperature is higher than the target process temperature, the dynamically predicted flow rate is greater than the basic set flow rate. When the measured temperature is lower than the target process temperature, the dynamically predicted flow rate is less than the basic set flow rate.

4. The method for supplying cooling water for die casting based on variable frequency constant pressure control according to claim 1, characterized in that, In step S4, by comparing the predicted change in the system's water demand with the maximum flow change that the main water supply unit can respond to and adjust within the future prediction time window, the transient compensation flow that needs to be compensated by the active pressure compensation unit is determined.

5. A method for supplying cooling water to die-casting based on variable frequency constant pressure control according to claim 4, characterized in that, In the step of determining the transient compensation flow rate, when the predicted change in the system water demand is greater than the maximum flow rate change of the main water supply unit, the difference between the predicted change in the system water demand and the maximum flow rate change of the main water supply unit is determined as the transient compensation flow rate.

6. The method for supplying cooling water for die casting based on variable frequency constant pressure control according to claim 4, characterized in that, Step S4 further includes: generating feedforward control commands for the main water supply unit based on the total predicted water demand of the system and the flow frequency characteristic function of the main water supply unit.

7. The method for supplying cooling water for die casting based on variable frequency constant pressure control according to claim 1, characterized in that, In step S5, by including an execution timestamp corresponding to the time of the future event in the transient compensation instruction, the transient compensation action of the active pressure compensation unit is triggered when the execution timestamp arrives.

8. The method for supplying cooling water for die casting based on variable frequency constant pressure control according to claim 1, characterized in that, In step S5, the composite control and closed-loop correction include: Calculate the deviation between the actual pressure value of the water supply network and the preset target pressure value, and generate a feedback correction command; The feedforward control command and the feedback correction command are superimposed to form the final control command; The main water supply unit is driven to make adjustments according to the final control command.

9. A method for supplying cooling water to die-casting based on variable frequency constant pressure control according to claim 1, characterized in that, In step S1, the reference process parameters include the basic set flow rate and target process temperature of each cooling circuit; the control model parameters include the thermal compensation sensitivity coefficient, the flow frequency characteristic function of the main water supply unit, and the response model of the active pressure compensation unit.

10. A die-casting cooling water supply system based on variable frequency constant pressure control, comprising a die-casting cooling water supply method based on variable frequency constant pressure control according to any one of claims 1-9, characterized in that, include: The data acquisition module is used to collect and process process timing data, mold thermal status data and water supply network hydraulic status data from multiple die-casting machines in real time. The water demand prediction and command decoupling module is connected to the data acquisition module and is used to: calculate the total predicted water demand of the system within the future prediction time window based on the process timing data and the mold thermal state data; and decouple and generate feedforward control commands for the main water supply unit and transient compensation commands for the active pressure compensation unit based on the total predicted water demand of the system. The composite control and correction module, connected to the water demand prediction and command decoupling module and the data acquisition module, is used to: generate feedback correction commands based on the hydraulic state data of the water supply network, superimpose the feedforward control commands and the feedback correction commands to form a final control command, and output the final control command to the main water supply unit and output the transient compensation command to the active pressure compensation unit.

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