A cooling cycle self-regulating temperature control system and method

Abstract

The application provides a cooling circulation self-adjusting temperature control system and method, and relates to the technical field of temperature control. The system comprises a cooling circulation loop, a multi-parameter acquisition module, a heat load estimation module, a feedforward compensation module, a feedback control module, a main adjustment execution module, a multi-branch parallel distribution module and a bypass adjustment module. The inlet and outlet temperatures, flow rates and liquid levels are acquired; the real-time heat load and change rate are calculated based on the acquired data; the feedforward control amount is generated in advance according to the heat load change rate; the feedback control amount is generated by a PID controller according to the inlet temperature deviation; the feedforward and feedback control amounts are further superimposed to adjust the rotating speed of the circulating pump through a frequency converter; in addition, the multi-branch parallel distribution module independently adjusts the branch electric valve opening degree according to the temperature difference of each region; and the bypass adjustment module rapidly shunts through the bypass valve when the heat load suddenly increases. Precise and rapid adaptive temperature control is realized, and the system is suitable for occasions with severe heat load fluctuation or strict multi-region temperature difference requirements.

Description

Technical Field

[0001] This invention belongs to the field of temperature control system technology, specifically relating to a cooling cycle self-regulating temperature control system and method. Background Technology

[0002] With the technological development in fields such as precision CNC machining, semiconductor manufacturing, and high-end data centers, the operating heat load of various precision equipment fluctuates greatly and the heat dissipation distribution is significantly uneven. This places extremely high demands on the temperature control accuracy, dynamic response speed, and adaptability of cooling systems under all operating conditions. Traditional cooling and temperature control technologies are gradually failing to meet the needs of high-end scenarios.

[0003] Current mainstream industrial cooling systems generally suffer from several technical defects: First, most adopt a single PID temperature feedback control architecture, adjusting operating parameters solely based on the measured temperature deviation of the cooling medium. This inherently results in control lag, leading to significant temperature overshoot when equipment heat load changes abruptly and drastically. The system also experiences long stabilization times and struggles to achieve high-precision temperature control at the ±0.2℃ level. Second, most systems operate in a constant flow mode, failing to dynamically match cooling flow based on real-time heat load. Circulating pumps maintain high loads for extended periods, resulting in high levels of wasted energy. Furthermore, frequent and significant adjustments to pumps and valves exacerbate component wear and shorten system lifespan. Third, for controlled objects requiring heat dissipation in multiple areas such as spindles and cabinets, a central control system is commonly used. The single-supply method cannot independently allocate flow according to the different heat dissipation needs of different areas, which is prone to local overheating and excessive temperature difference between areas, directly affecting the operating accuracy and stability of precision equipment. Fourth, the existing system has insufficient adaptability to operating conditions. It lacks a rapid buffer and control mechanism when the heat load suddenly increases, which can easily lead to short-term temperature runaway. Under low load conditions, the pump and valve adjustment enters the dead zone, which can easily lead to abnormal fluctuations in the temperature of the cooling medium that are continuously low. It cannot cover the stable operation of the entire scenario from extremely low load to full load impact. Fifth, the control parameters of most systems need to be manually debugged and calibrated on site. They cannot be adaptively corrected according to the actual operating conditions, resulting in high debugging and maintenance costs. The system has poor adaptability to equipment with different load characteristics and different pipeline resistances, and lacks versatility.

[0004] Against this backdrop, there is an urgent need for an intelligent cooling control system that features multimodal perception fusion, predictive feedforward compensation, zoned dynamic flow allocation, and full-condition adaptive optimization, in order to systematically address the shortcomings of existing technologies. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a cooling cycle self-regulating temperature control system and method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a cooling cycle self-regulating temperature control system, comprising: Cooling circulation loop: includes a circulation pump, a heat exchanger, a liquid storage tank, and connecting pipelines. The outlet of the circulation pump is connected to the inlet of the cooling channel of the controlled heat object via the heat exchanger, and the outlet of the cooling channel of the controlled heat object is connected to the inlet of the circulation pump via the liquid storage tank. Multi-parameter acquisition module: including a first temperature sensor installed at the inlet of the cooling channel of the controlled heat object, a second temperature sensor installed at the outlet of the cooling channel of the controlled heat object, a flow meter installed at the outlet of the circulating pump, and a liquid level sensor installed in the storage tank; Heat load estimation module: connected to the first temperature sensor, the second temperature sensor and the flow meter respectively, used to calculate the real-time heat load value and heat load change rate based on the temperature difference between the inlet and outlet of the cooling medium and the circulation flow rate; Feedforward compensation module: connected to the heat load estimation module, used to generate feedforward control quantity based on the heat load change rate; Feedback control module: includes a PID controller, which is connected to the signal of the first temperature sensor and is used to generate a feedback control quantity based on the deviation between the set temperature value and the measured value of the first temperature sensor; Main regulating execution module: includes a frequency converter, which is connected to the feedforward compensation module, the feedback control module and the circulating pump signal respectively, and is used to adjust the speed of the circulating pump according to the superposition value of the feedforward control quantity and the feedback control quantity; Multi-branch parallel distribution module: includes at least two cooling branches connected in parallel between the heat exchanger and the controlled heat object, each cooling branch is equipped with an electric regulating valve and a branch flow meter, the multi-branch parallel distribution module is used to adjust the opening degree of each electric regulating valve according to the temperature difference of different areas of the controlled heat object; Bypass regulation module: includes a bypass pipeline and a bypass regulating valve. One end of the bypass pipeline is connected to the outlet of the circulating pump, and the other end is connected to the inlet of the storage tank. The bypass regulating valve is installed on the bypass pipeline for rapid diversion when the system heat load suddenly increases.

[0007] The feedback control module also includes a parameter self-tuning unit, which is used to automatically adjust the proportional coefficient, integral time, and derivative time of the PID controller according to the system operating conditions.

[0008] The multi-branch parallel distribution module also includes a zone temperature sensor installed at the outlet of each cooling zone of the controlled heat object. The opening degree of each electric regulating valve is independently adjusted according to the deviation between the measured value of the corresponding zone temperature sensor and the zone set value.

[0009] The system also includes a refrigerant temperature sensor and a refrigerant flow regulating valve installed at the refrigerant inlet of the heat exchanger. The opening degree of the refrigerant flow regulating valve is adjusted according to the measured value of the second temperature sensor.

[0010] The bypass adjustment module also includes a one-way valve linked to the bypass adjustment valve, which is used to prevent the cooling medium from flowing backward from the storage tank to the outlet of the circulation pump.

[0011] The liquid storage tank is equipped with an electric heater, which is connected to the feedback control module for compensating for the temperature of the cooling medium under low system load conditions.

[0012] Secondly, the present invention provides a cooling cycle self-regulating temperature control method, comprising the following steps: The temperature of the cooling medium at the inlet of the cooling channel of the controlled heat object is collected by the first temperature sensor, the temperature of the cooling medium at the outlet of the cooling channel is collected by the second temperature sensor, the flow rate of the cooling medium in the circulation pipeline is collected by the flow meter, and the liquid level of the storage tank is monitored by the liquid level sensor. Based on the collected inlet and outlet cooling medium temperatures and cooling medium flow rates, the real-time heat load value is calculated, and the heat load change rate is obtained by performing time differentiation on the real-time heat load value. Based on the heat load change rate, a feedforward control quantity is generated. When the heat load change rate is positive and exceeds the first preset threshold, the circulation pump speed is increased in advance; when the heat load change rate is negative and the absolute value exceeds the second preset threshold, the circulation pump speed is decreased in advance. While performing the feedforward compensation, the PID controller in the feedback control module compares the preset inlet target temperature with the actual inlet temperature measured by the first temperature sensor in real time, and calculates the feedback control quantity to eliminate steady-state error based on the deviation between the two. The feedforward control quantity and the feedback control quantity are linearly superimposed to generate a composite speed regulation command and output to the frequency converter. The speed of the circulating pump is synchronously adjusted by the frequency converter. In the early stage of heat load fluctuation, the feedforward control quantity dominates the advance adjustment, and after the heat load stabilizes, the feedback control quantity dominates the fine correction. Based on the circulation pump speed regulation, the multi-branch parallel distribution module obtains the measured temperature of each cooling zone of the controlled heat object, compares it with the set temperature corresponding to each zone, and independently adjusts the opening of the electric regulating valve on each cooling branch according to the direction and magnitude of the temperature deviation of each zone. When the real-time heat load value exceeds the preset percentage of the system design load, it is determined that the current condition is an extreme thermal shock condition. The bypass adjustment module is then controlled to open the bypass adjustment valve, and part of the cooling medium at the outlet of the circulating pump is directly diverted to the liquid storage tank through the bypass pipeline to reduce the temperature rise rate of the cooling medium entering the controlled heat object per unit time.

[0013] Before generating the feedforward control quantity, a filtering sub-step is also included: performing a first-order inertial filter on the heat load change rate to eliminate false triggering caused by measurement noise.

[0014] Before performing deviation value calculation based on the PID controller, a parameter self-tuning initialization sub-step is also included, as follows: The hysteresis time and time constant of the controlled heat object are obtained from the system step response test, and the initial proportional coefficient, integral time and derivative time of the PID controller are calculated according to the Ziegler-Nichols method. During the operation of the cooling cycle self-regulating temperature control method, an online parameter correction sub-step is also performed: the initial proportional coefficient, integral time, and derivative time are corrected online based on the adjustment control quantity and stabilization time index of the actual system response.

[0015] The electric regulating valve adopts a split-range control strategy: when the temperature deviation of any region is within the preset temperature deviation range, the electric regulating valve corresponding to that region maintains its current opening; when the temperature deviation exceeds the preset temperature deviation range but is less than the upper limit, the opening adjustment of the corresponding electric regulating valve is linearly proportional to the temperature deviation; when the temperature deviation exceeds the upper limit of the preset temperature deviation range, the electric regulating valve adjusts to the limit position at the maximum rate.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The cooling cycle self-regulating temperature control system prepared by this invention forms a complete closed-loop temperature control logic through deep synergy and linkage of all functional modules, including all-domain perception, load prediction, composite regulation, zone adaptation, and condition fallback. The entire system uses a multi-parameter acquisition module as the sensing basis, synchronously collecting all-dimensional operating data. The collected temperature and flow data are simultaneously sent to the heat load estimation module to calculate the current heat load value and rate of change in real time. The heat load change rate is filtered and noise-reduced before being sent to the feedforward compensation module to generate the pump speed adjustment amount in advance. At the same time, the inlet temperature deviation is sent to the PID feedback module with parameter self-tuning to generate the fine adjustment amount. The two are superimposed and jointly drive the frequency converter to adjust the speed of the main circulation pump, forming a collaborative main control logic of prediction coarse adjustment to eliminate hysteresis and feedback fine adjustment to maintain accuracy. While the main loop adjusts the total flow, multiple branch modules independently adjust the opening of each branch valve to match the local heat dissipation difference. When the heat load suddenly increases, the bypass module quickly diverts and buffers the flow, and the refrigerant side regulating valve coordinates with bidirectional temperature control. Under low load conditions, the electric heater automatically starts to compensate for the temperature. All modules complement each other and cover the operating needs of all scenarios.

[0017] Furthermore, the cooling cycle self-regulating temperature control system of the present invention solves the core pain points of traditional cooling systems, such as control lag, temperature overshoot, slow response, large local temperature difference, and poor adaptability to operating conditions. It ensures both response speed under dynamic operating conditions and temperature control accuracy under steady-state operating conditions, and can stably achieve a temperature control accuracy of ±0.2℃. At the same time, compared with traditional constant flow cooling systems, it reduces mechanical wear caused by frequent pump and valve operations, and takes into account multiple technical benefits such as precise temperature control, adaptability to all operating conditions, stable operation, and energy saving. Attached Figure Description

[0018] Figure 1 This is a system diagram of the present invention. Detailed Implementation

[0019] To further understand the content of this invention, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments are merely illustrative and not limiting of the invention.

[0020] Example 1 A cooling cycle self-regulating temperature control system includes a cooling cycle loop, a multi-parameter acquisition module, a heat load estimation module, a feedforward compensation module, a feedback control module, a main regulation execution module, a multi-branch parallel distribution module, and a bypass regulation module.

[0021] The cooling circulation loop consists of a circulating pump, a heat exchanger, a storage tank, and connecting pipelines. The outlet of the circulating pump is connected via the heat exchanger to the inlet of the cooling channel of the controlled heat object (e.g., a laser, power module, reactor, etc.). The outlet of the cooling channel of the controlled heat object is connected via pipelines to the inlet of the storage tank, and the outlet of the storage tank is then connected to the inlet of the circulating pump, forming a closed loop. The cooling medium can be water, ethylene glycol solution, or other heat-conducting fluids.

[0022] The multi-parameter acquisition module contains multiple sensors: The first temperature sensor (T1) is installed at the inlet of the cooling channel of the controlled heat object to measure the temperature of the cooling medium entering the controlled heat object.

[0023] The second temperature sensor (T2) is installed at the outlet of the cooling channel of the controlled heat object to measure the temperature of the cooling medium flowing out of the controlled heat object.

[0024] A flow meter (F) is installed at the outlet of a circulating pump to measure the volumetric or mass flow rate of the cooling medium in the circulating pipeline.

[0025] The liquid level sensor (L) is installed inside the liquid storage tank to monitor the liquid level of the cooling medium inside the tank and prevent dry burning or insufficient liquid.

[0026] The heat load estimation module is connected to the first temperature sensor, the second temperature sensor, and the flow meter via wired or wireless signal transmission. Its core function is to calculate the current heat load value in real time based on the collected inlet and outlet temperature difference ΔT = T2 - T1 and the circulation flow rate m (or volumetric flow rate converted to mass flow rate), using the thermodynamic formula Q = c × m × ΔT, where c is the specific heat capacity of the cooling medium. Simultaneously, this module performs time differentiation on the real-time heat load value to obtain the heat load change rate, which is used to characterize the dynamic trend of heat load change.

[0027] Feedforward Compensation Module: The feedforward compensation module is signal-connected to the heat load estimation module. It receives the heat load change rate signal and generates a feedforward control quantity accordingly. In this embodiment, the feedforward compensation module includes a differential advance stage, which first performs a first-order inertial filter on the heat load change rate to filter out high-frequency measurement noise and avoid false triggering due to noise. The filtered signal is then proportionally amplified and output as the feedforward control quantity.

[0028] When the rate of change of heat load is positive and exceeds the first preset threshold, the feedforward control quantity is positive, indicating that the system needs to increase the cooling capacity in advance.

[0029] When the rate of change of heat load is negative and its absolute value exceeds the second preset threshold, the feedforward control quantity is negative, indicating that the system can reduce the cooling capacity in advance.

[0030] Feedback control module: This module includes a PID controller whose input is connected to the signal from a first temperature sensor. Its setpoint is the user-defined target inlet temperature. The PID controller generates feedback control input based on the deviation between the setpoint and the measured value from the first temperature sensor, using proportional, integral, and derivative operations. To adapt to different operating conditions, this embodiment's feedback control module also integrates a parameter self-tuning unit. When the system is initially put into operation or when operating conditions change significantly, this unit obtains the lag time τ and time constant T of the controlled object through a step response test, and then calculates the initial PID parameters according to the Ziegler-Nichols empirical formula. During normal operation, the parameter self-tuning unit continuously monitors the system's overshoot, settling time, and other performance indicators, and fine-tunes the PID parameters online to ensure control quality.

[0031] The main control and execution module includes a frequency converter. The control signal input terminals of the frequency converter are connected to the output terminals of the feedforward compensation module and the feedback control module, respectively. Internally, the frequency converter algebraically superimposes the feedforward control quantity and the feedback control quantity, converting the superposition result into a corresponding frequency command to regulate the speed of the circulating pump. When the heat load suddenly increases, the feedforward control quantity increases rapidly, and the superposition results in the frequency converter outputting a higher frequency, immediately increasing the circulating pump speed and accelerating the circulation of the cooling medium, thereby suppressing temperature rise. Simultaneously, the feedback control quantity gradually takes effect, eliminating steady-state errors.

[0032] Multi-branch parallel distribution module: This module addresses the issue of uneven heat dissipation across different areas of the controlled heat source. Two or more cooling branches are connected in parallel between the heat exchanger outlet and the controlled heat source. Each branch is connected in series with an electrically controlled regulating valve and a branch flow meter. Additionally, a zone temperature sensor is installed at the outlet of each cooling zone. The control logic of the multi-branch parallel distribution module is as follows: It reads the measured value from each zone temperature sensor and compares it with the set temperature for that zone. If the measured temperature of a zone is higher than the set value, the opening of the electrically controlled regulating valve for that branch is increased, increasing the flow rate of the cooling medium through that zone; conversely, if the measured temperature is lower than the set value, the valve opening is decreased.

[0033] The adjustment method adopts a split-range control strategy: when the temperature deviation of any region is within the preset temperature deviation range, the electric regulating valve corresponding to that region maintains its current opening; when the temperature deviation exceeds the preset temperature deviation range but is less than the upper limit, the opening adjustment of the corresponding electric regulating valve is linearly proportional to the temperature deviation; when the temperature deviation exceeds the upper limit of the preset temperature deviation range, the electric regulating valve adjusts to the limit position at the maximum rate.

[0034] Bypass Regulating Module: The bypass regulating module includes a bypass pipeline and a bypass regulating valve. One end of the bypass pipeline connects to the outlet of the circulating pump and the heat exchanger, and the other end connects to the inlet of the storage tank. The bypass regulating valve is installed on this pipeline. When the real-time heat load value calculated by the heat load estimation module exceeds the preset percentage of the system design load, it indicates that the system is close to full load operation. If the temperature continues to rise at this time, it may lead to insufficient cooling capacity. At this time, the bypass regulating module opens the bypass regulating valve, allowing a portion of the high-temperature cooling medium to bypass directly back to the storage tank, without passing through the heat exchanger and the controlled heat object. The purpose of this is to reduce the rate of temperature rise of the cooling medium entering the controlled heat object, giving the system more response time. To prevent backflow of the cooling medium when the pump stops, a one-way valve is also connected in series on the bypass pipeline. Its direction allows the medium to flow from the outlet of the circulating pump to the storage tank, and its direction cuts off the flow in the opposite direction.

[0035] Preferably, a refrigerant temperature sensor and a refrigerant flow regulating valve are installed at the refrigerant inlet of the heat exchanger. The opening of the regulating valve is controlled by a second temperature sensor (T2): when the measured value of T2 is higher than the set upper limit, the opening of the refrigerant flow regulating valve is increased to enhance heat exchange; when T2 is lower than the set lower limit, the opening is decreased to save energy.

[0036] Preferably, an electric heater is installed inside the storage tank. When the system is under low load and the temperature of the cooling medium remains below the set lower limit, the feedback control module sends a signal to start the electric heater to heat the cooling medium and raise its temperature to a suitable range, thus preventing condensation or freezing on the surface of the controlled object due to excessively cold medium.

[0037] Example 2 A self-regulating temperature control method for a cooling cycle includes the following steps: S1: The temperature of the cooling medium at the inlet of the cooling channel of the controlled heat object is collected by the first temperature sensor, the temperature of the cooling medium at the outlet of the cooling channel is collected by the second temperature sensor, the flow rate of the cooling medium in the circulation pipeline is collected by the flow meter, and the liquid level of the storage tank is monitored by the liquid level sensor.

[0038] S2: Based on the inlet and outlet temperature difference and circulation flow rate collected in S1, calculate the real-time heat load value according to the thermodynamic formula. At the same time, perform time differentiation on this real-time heat load value to obtain the heat load change rate, which is used to characterize the dynamic change trend of the heat load.

[0039] S3: Generate a feedforward control quantity based on the heat load change rate. When the heat load change rate is positive and exceeds the first preset threshold, generate a positive feedforward control quantity to increase the speed of the circulating pump in advance. When the heat load change rate is negative and its absolute value exceeds the second preset threshold, generate a negative feedforward control quantity to decrease the speed of the circulating pump in advance. In other cases, the feedforward control quantity is zero or maintains the current value.

[0040] S4: While performing the feedforward compensation, the PID controller in the feedback control module compares the preset inlet target temperature with the actual inlet temperature measured by the first temperature sensor in real time, and calculates the feedback control quantity to eliminate steady-state error based on the deviation between the two.

[0041] The initial parameters of the PID controller can be obtained through system step response testing combined with the Ziegler-Nichols method for engineering tuning. During system operation, the parameter self-tuning unit corrects the PID parameters online based on performance indicators such as overshoot and settling time. The feedforward control quantity and the feedback control quantity are algebraically superimposed to obtain the total control quantity, which is then output to the frequency converter. The frequency converter adjusts the speed of the circulating pump according to the total control quantity, thereby achieving dynamic regulation of the cooling medium flow rate.

[0042] S5: The feedforward control quantity and the feedback control quantity are linearly superimposed to generate a composite speed adjustment command and output to the frequency converter. The speed of the circulating pump is synchronously adjusted by the frequency converter so that the feedforward control quantity dominates the advance adjustment in the early stage of heat load fluctuation, and the feedback control quantity dominates the fine correction after the heat load stabilizes.

[0043] S6: Based on the speed adjustment of the circulating pump, the multi-branch parallel distribution module obtains the measured temperature of each cooling zone of the controlled heat object, compares it with the set temperature of each zone, and independently adjusts the opening of the electric regulating valve on each cooling branch according to the direction and magnitude of the temperature deviation of each zone.

[0044] S7: Real-time monitoring of the heat load value calculated by S2. When this heat load value exceeds a preset percentage of the system design load, the bypass control module opens the bypass control valve, directly returning a portion of the cooling medium to the storage tank via the bypass pipeline. This reduces the rate of temperature rise of the cooling medium entering the controlled heat object, providing more time for system response. The opening degree of the bypass control valve can be adjusted proportionally according to the overload level, and a maximum opening limit is provided to prevent the main circuit flow from becoming too low.

[0045] Example 3 The aforementioned self-regulating temperature control system for cooling circulation is applied to the precision cooling scenario of the spindle in a five-axis CNC machining center. The system is designed with a temperature control accuracy of ±0.2℃ and a maximum heat load of 12kW, as detailed below: Cooling circulation loop: A deionized water-ethylene glycol mixed solution (volume ratio 1:1) is used as the cooling medium. The loop consists of: Circulation pump: A vertical variable frequency centrifugal pump is selected, with a rated flow rate of 30L / min, a rated head of 25m, a power of 1.5kW, and a speed adjustment range of 0~3000rpm; Heat exchanger: Plate heat exchanger with a heat exchange area of ​​0.8㎡, refrigerant side connected to the factory's 7℃ chilled water main pipeline, designed heat exchange efficiency ≥92%; Storage tank: 50L capacity, 0.6MPa pressure, with insulation layer and built-in 2kW electric heater; Connecting pipes: 304 stainless steel seamless pipes, DN20 diameter, total pipe length 12m.

[0046] Loop connection relationship: including the circulating pump outlet, plate heat exchanger, multi-branch parallel distribution module, main shaft cooling channel inlet, main shaft cooling channel outlet, liquid storage tank, and circulating pump inlet connected in sequence, forming a closed loop.

[0047] Multi-parameter acquisition module: Sensor configuration and installation position: First temperature sensor: PT100 platinum resistance thermometer, accuracy ±0.1℃, installed at the main inlet of the spindle cooling channel, to acquire the inlet temperature T1; Second temperature sensor: PT100 of the same precision, installed at the main outlet of the spindle cooling channel, to collect the return liquid temperature T2; Flow meter: Electromagnetic flow meter, accuracy ±0.5% FS, range 0~40L / min, installed on the main outlet pipeline of the circulating pump; Liquid level sensor: Submersible liquid level gauge, measuring range 0~0.5m, installed at the bottom of the storage tank, monitors the liquid level and triggers a low liquid level alarm; Refrigerant temperature sensor: PT100, installed at the refrigerant inlet of the plate heat exchanger, to collect refrigerant temperature T_c; Zone temperature sensors: a total of 3 PT100, which are installed at the cooling zone outlets of the front bearing of the spindle, the middle stator, and the rear motor housing.

[0048] Heat load estimation module: Uses an STM32F407 microcontroller as the processing core. Input signals are T1, T2, and flow rate signal. It calculates the real-time heat load Q = c m ΔT.

[0049] Wherein: the specific heat capacity of the cooling medium is c = 3.8 KJ / (kg) ℃), mass flow rate m is converted from volumetric flow rate (mixture density 1.05kg / L), temperature difference ΔT=T2-T 1。

[0050] The heat load change rate dQ / dt is output using first-order differential calculation with a sampling interval of 50ms.

[0051] Feedforward compensation module: Features a built-in differential lead-in stage to perform first-order inertial filtering (time constant 0.2s) on the rate of change of heat load, eliminating measurement noise; Control threshold settings are also available. First preset threshold (heat load rise trigger value, +0.8): When triggered, the feedforward control quantity corresponds to a 150 rpm increase in the circulating pump speed; Second preset threshold (heat load decrease trigger value, -0.6): When triggered, the feedforward control quantity corresponds to a 120 rpm reduction in the circulating pump speed.

[0052] Feedback control module: Employs a digital PID controller with a parameter self-tuning unit. The initial PID parameters were obtained through step response testing: the controlled object's lag time τ = 1.2s, the time constant T = 8.5s, and the initial parameters were calculated using the Ziegler-Nichols method: proportional coefficient Kp = 2.8, integral time Ti = 5.2s, and derivative time Td = 1.1s.

[0053] Parameter self-tuning logic: During operation, the overshoot and settling time are collected in real time. When the overshoot is >5%, Kp decreases by 10% and Ti increases by 15%; when the settling time is >15s, Kp increases by 8% and Td increases by 10%. Parameter correction is completed every 30s.

[0054] Main regulating and executing module: adopts a 0.75kW vector frequency converter, the input is the superposition value of feedforward control quantity and feedback control quantity, and the output is a 0~50Hz frequency signal to regulate the speed of the circulating pump, with a speed regulation resolution of 1rpm.

[0055] Multi-branch parallel distribution module: Set up 3 parallel cooling branches, corresponding to 3 cooling zones of the spindle: Each branch is equipped with a DN15 electric regulating valve (regulation accuracy ±1%, response time <2s) and a branch micro flow meter.

[0056] A split-range control strategy is adopted: when the temperature deviation |ΔT| < 0.1℃ (dead zone), the valve opening is maintained; when 0.1℃ ≤ |ΔT| < 0.5℃ (linear zone), the opening is adjusted proportionally to the deviation; when |ΔT| ≥ 0.5℃, the valve is adjusted to fully open / fully closed at a rate of 5% / s. Each branch has an independent closed loop: the front bearing is set to 24.5℃, the middle stator to 25℃, and the rear motor housing to 25.5℃. The valve opening is adjusted independently according to the actual measured value of the temperature sensor in the corresponding area.

[0057] Bypass regulating module: Bypass pipeline diameter DN15, configuration: Bypass regulating valve: electric two-way valve, response time <1s; Check valve: opening pressure 0.02MPa, to prevent backflow of medium from the storage tank.

[0058] Triggering logic: When the real-time heat load Q>9.6kW (80% of the system design load), the bypass regulating valve opens by 30%, and the opening increases linearly with the increase of heat load, with a maximum opening of 80%.

[0059] Auxiliary regulating unit: Refrigerant flow regulating valve: installed at the refrigerant inlet of the plate heat exchanger, increases the refrigerant flow when T2>28℃, and decreases the refrigerant flow when T2<26℃; Electric heater control: When Q < 0.6kW (minimum effective regulating load) and T1 lasts for 5 minutes < 23℃, start the electric heater, adjust the heating power according to PID, and maintain T1 in the range of 24~25℃.

[0060] Example 4 Taking the machining center transitioning from standby to heavy-duty cutting as an example, the temperature control method implemented using Example 3 follows these steps: S1: After the system starts, each sensor collects data at a frequency of 100Hz. Initial steady-state values: T1=24.8℃, T2=25.7℃, main pipeline flow rate=12L / min, liquid level in storage tank=0.35m; temperatures in 3 zones: front end 24.6℃, middle end 24.9℃, and rear end 25.3℃.

[0061] S2: Calculate the initial heat load: mass flow rate m = 12 L / min 1.05 kg / L / 60 = 0.21 kg / S Temperature difference ΔT = 25.7 - 24.8 = 0.9℃; Real-time heat load Q=3.8 0.21 0.9 = 0.72 kW; The rate of change of heat load is calculated by continuous sampling. In standby mode, dQ / dt = 0 kW / s.

[0062] S3: Feedforward compensation control: When the machining center starts heavy-duty cutting (spindle power increases from 1kW to 8kW), at the 2nd second, it is detected that dQ / dt = 1.2kW / s, which exceeds the first preset threshold of 0.8kW / s. After applying a first-order inertial filter to the rate of change, a feedforward control variable is generated: the circulation pump speed is increased by 200 rpm (from the initial 1200 rpm to 1400 rpm), and the flow rate is increased in advance to cope with the sudden increase in heat load.

[0063] S4: Feedforward-Feedback Composite Control At 5 seconds, T1 rose to 25.3℃, deviating from the set value of 25℃ by +0.3℃. The PID controller calculates the feedback control quantity: the output speed is increased by 100 rpm. After superimposing the feedforward control quantity, the inverter output frequency corresponds to a speed of 1500 rpm, and the main pipeline flow rate increases to 18 L / min; After running for 10 seconds, the system overshoot was 3.2%, the settling time was 12 seconds, and the parameter self-tuning unit corrected Kp to 2.6 and Ti to 5.8 seconds.

[0064] S5: Multi-branch flow distribution adjustment During the cutting process, the temperature in the middle stator region of the spindle rose to 25.8℃, a deviation of +0.8℃, while the temperature at the front end was 24.7℃ (a deviation of -0.1℃). Mid-range branch: When the deviation exceeds the upper limit of the linear zone, the electric regulating valve opens from 40% to 80% at a rate of 5% / s; Front-end branch: If the deviation is within the dead zone, the valve opening remains constant at 35%; The temperature in the back-end area is 25.6℃, with a deviation of +0.1℃. The valve opening is linearly adjusted from 50% to 55%. After 3 seconds of adjustment, the temperature in each area returned to within ±0.2℃ of the set value.

[0065] S6: Bypass adjustment trigger At 15 seconds, the spindle enters full-load cutting, and the real-time thermal load rises to 10.2kW (exceeding 80% of the design load).

[0066] The bypass adjustment module opens the bypass adjustment valve with an initial opening of 35%, and 20% of the flow directly returns to the storage tank through the bypass pipeline; the temperature rise rate of the cooling medium entering the spindle decreases from 0.15℃ / s to 0.06℃ / s, effectively suppressing temperature overshoot.

[0067] Assisted adjustment execution: Refrigerant side adjustment: T2 rises to 28.2℃, the opening of the refrigerant flow regulating valve increases from 30% to 60%, and after 2 minutes T2 drops back to 26.5℃; Low load compensation: After machining is completed, the spindle is idle, Q drops to 0.4kW, T1 continues to drop to 22.8℃, the electric heater is started and runs at 30% power. After 8 minutes, T1 rises back to 24.5℃, maintaining the system temperature stability.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A cooling cycle self-regulating temperature control system, characterized in that, include: Cooling circulation loop: includes a circulation pump, a heat exchanger, a liquid storage tank, and connecting pipelines. The outlet of the circulation pump is connected to the inlet of the cooling channel of the controlled heat object via the heat exchanger, and the outlet of the cooling channel of the controlled heat object is connected to the inlet of the circulation pump via the liquid storage tank. Multi-parameter acquisition module: including a first temperature sensor installed at the inlet of the cooling channel of the controlled heat object, a second temperature sensor installed at the outlet of the cooling channel of the controlled heat object, a flow meter installed at the outlet of the circulating pump, and a liquid level sensor installed in the storage tank; Heat load estimation module: connected to the first temperature sensor, the second temperature sensor and the flow meter respectively, used to calculate the real-time heat load value and heat load change rate based on the temperature difference between the inlet and outlet of the cooling medium and the circulation flow rate; Feedforward compensation module: connected to the heat load estimation module, used to generate feedforward control quantity based on the heat load change rate; Feedback control module: includes a PID controller, which is connected to the signal of the first temperature sensor and is used to generate a feedback control quantity based on the deviation between the set temperature value and the measured value of the first temperature sensor; Main regulating execution module: includes a frequency converter, which is connected to the feedforward compensation module, the feedback control module and the circulating pump signal respectively, and is used to adjust the speed of the circulating pump according to the superposition value of the feedforward control quantity and the feedback control quantity; Multi-branch parallel distribution module: includes at least two cooling branches connected in parallel between the heat exchanger and the controlled heat object, each cooling branch is equipped with an electric regulating valve and a branch flow meter, the multi-branch parallel distribution module is used to adjust the opening degree of each electric regulating valve according to the temperature difference of different areas of the controlled heat object; Bypass regulation module: includes a bypass pipeline and a bypass regulating valve. One end of the bypass pipeline is connected to the outlet of the circulating pump, and the other end is connected to the inlet of the storage tank. The bypass regulating valve is installed on the bypass pipeline for rapid diversion when the system heat load suddenly increases.

2. The cooling cycle self-regulating temperature control system according to claim 1, characterized in that, The feedback control module also includes a parameter self-tuning unit, which is used to automatically adjust the proportional coefficient, integral time, and derivative time of the PID controller according to the system operating conditions.

3. The cooling cycle self-regulating temperature control system according to claim 1, characterized in that, The multi-branch parallel distribution module also includes a zone temperature sensor installed at the outlet of each cooling zone of the controlled heat object. The opening degree of each electric regulating valve is independently adjusted according to the deviation between the measured value of the corresponding zone temperature sensor and the zone set value.

4. The cooling cycle self-regulating temperature control system according to claim 1, characterized in that, The system also includes a refrigerant temperature sensor and a refrigerant flow regulating valve installed at the refrigerant inlet of the heat exchanger. The opening degree of the refrigerant flow regulating valve is adjusted according to the measured value of the second temperature sensor.

5. The cooling cycle self-regulating temperature control system according to claim 1, characterized in that, The bypass adjustment module also includes a one-way valve linked to the bypass adjustment valve, which is used to prevent the cooling medium from flowing backward from the storage tank to the outlet of the circulation pump.

6. The cooling cycle self-regulating temperature control system according to claim 1, characterized in that, The liquid storage tank is equipped with an electric heater, which is connected to the feedback control module for compensating for the temperature of the cooling medium under low system load conditions.

7. A cooling cycle self-regulating temperature control method, based on the cooling cycle self-regulating temperature control system according to any one of claims 1 to 6, characterized in that, Includes the following steps: The temperature of the cooling medium at the inlet of the cooling channel of the controlled heat object is collected by the first temperature sensor, the temperature of the cooling medium at the outlet of the cooling channel is collected by the second temperature sensor, the flow rate of the cooling medium in the circulation pipeline is collected by the flow meter, and the liquid level of the storage tank is monitored by the liquid level sensor. Based on the collected inlet and outlet cooling medium temperatures and cooling medium flow rates, the real-time heat load value is calculated, and the heat load change rate is obtained by performing time differentiation on the real-time heat load value. Based on the heat load change rate, a feedforward control quantity is generated. When the heat load change rate is positive and exceeds the first preset threshold, the circulation pump speed is increased in advance; when the heat load change rate is negative and the absolute value exceeds the second preset threshold, the circulation pump speed is decreased in advance. While performing the feedforward compensation, the PID controller in the feedback control module compares the preset inlet target temperature with the actual inlet temperature measured by the first temperature sensor in real time, and calculates the feedback control quantity to eliminate steady-state error based on the deviation between the two. The feedforward control quantity and the feedback control quantity are linearly superimposed to generate a composite speed regulation command and output to the frequency converter. The speed of the circulating pump is synchronously adjusted by the frequency converter. In the early stage of heat load fluctuation, the feedforward control quantity dominates the advance adjustment, and after the heat load stabilizes, the feedback control quantity dominates the fine correction. Based on the circulation pump speed regulation, the multi-branch parallel distribution module obtains the measured temperature of each cooling zone of the controlled heat object, compares it with the set temperature corresponding to each zone, and independently adjusts the opening of the electric regulating valve on each cooling branch according to the direction and magnitude of the temperature deviation of each zone. When the real-time heat load value exceeds the preset percentage of the system design load, it is determined that the current condition is an extreme thermal shock condition. The bypass adjustment module is then controlled to open the bypass adjustment valve, and part of the cooling medium at the outlet of the circulating pump is directly diverted to the liquid storage tank through the bypass pipeline to reduce the temperature rise rate of the cooling medium entering the controlled heat object per unit time.

8. The cooling cycle self-regulating temperature control method according to claim 7, characterized in that, Before generating the feedforward control quantity, a filtering sub-step is also included: performing a first-order inertial filter on the heat load change rate to eliminate false triggering caused by measurement noise.

9. The cooling cycle self-regulating temperature control method according to claim 7, characterized in that, Before performing deviation value calculation based on the PID controller, a parameter self-tuning initialization sub-step is also included, as follows: The hysteresis time and time constant of the controlled heat object are obtained from the system step response test, and the initial proportional coefficient, integral time and derivative time of the PID controller are calculated according to the Ziegler-Nichols method. During the operation of the cooling cycle self-regulating temperature control method, an online parameter correction sub-step is also performed: the initial proportional coefficient, integral time, and derivative time are corrected online based on the adjustment control quantity and stabilization time index of the actual system response.

10. The cooling cycle self-regulating temperature control method according to claim 7, characterized in that, The electric regulating valve adopts a split-range control strategy: when the temperature deviation of any region is within the preset temperature deviation range, the electric regulating valve corresponding to that region maintains its current opening degree. When the temperature deviation exceeds the preset temperature deviation range but is less than the upper limit, the opening adjustment of the corresponding electric regulating valve is linearly proportional to the temperature deviation; when the temperature deviation exceeds the upper limit of the preset temperature deviation range, the electric regulating valve adjusts to the limit position at the maximum rate.

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