Converter IGBT evaporative cooling system and control method

Abstract

According to the variable-flow IGBT evaporative cooling system and the control method provided by the invention, dryness online calculation and closed-loop control based on pressure and density signals are introduced into the IGBT evaporative cooling system, so that accurate sensing and active regulation and control of a phase change state of a cooling medium are realized; therefore, it is ensured that the IGBT module is always in a gas-liquid mixing environment with the optimal heat exchange efficiency, the efficient heat dissipation capacity of phase change latent heat is fully utilized, local overheating or temperature fluctuation caused by excessive evaporation or insufficient liquid phase is avoided, the heat dissipation uniformity, stability and energy efficiency are fundamentally improved, and the heat dissipation efficiency is improved. The self-adaptive capacity of the system to different load working conditions is enhanced, and the guarantee is provided for long-term reliable operation and service life prolonging of the IGBT module through direct control over the key state quantity of dryness.

Description

Technical Field

[0001] This invention belongs to the field of liquid cooling control technology, specifically relating to a variable current IGBT evaporative cooling system and control method. Background Technology

[0002] With the development of power electronics technology, Insulated Gate Bipolar Transistor (IGBT) converters are increasingly widely used in high-frequency power conversion, new energy power generation, and industrial drives. IGBT modules generate a large amount of heat during operation. If this heat cannot be dissipated effectively and in a timely manner, it will lead to increased junction temperature, performance degradation, and even device failure, seriously affecting the reliability and lifespan of the system. Therefore, an efficient cooling system is crucial for ensuring the stable operation of IGBT converters. Currently, commonly used heat dissipation methods for IGBT modules include immersion evaporative cooling technology. This technology directly immerses the IGBT module in insulating coolant, utilizing the phase change of the liquid to absorb heat and achieve efficient heat dissipation. However, existing evaporative cooling systems lack coordinated control of various parameters within the cabinet (such as liquid level, pressure, and flow rate), preventing the IGBT module from operating in a safe and uniform temperature environment, thus affecting the heat dissipation effect. Summary of the Invention

[0003] This invention provides a variable current IGBT evaporative cooling system and control method, which aims to solve the problem in the prior art that the cooling system cannot coordinate and control various internal parameters, thus affecting the cooling effect.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is: to provide a converter IGBT evaporative cooling system, comprising: An immersion tank is used to install IGBT modules and contain coolant. The immersion tank is equipped with a liquid level sensor, a pressure sensor for monitoring the internal pressure of the immersion tank, a temperature sensor for monitoring the temperature of the coolant inside the immersion tank, and a density sensor for monitoring the density of the coolant inside the immersion tank. A pressure relief valve, installed on top of the immersion tank, is used to regulate the internal pressure of the immersion tank; A flow regulating valve is installed at the liquid inlet of the immersion tank to regulate the flow rate of the coolant inside the immersion tank. The cooling unit has its inlet end connected to the outlet end of the immersion tank, its outlet end connected to the inlet end of the immersion tank, and a circulation pump connected to the outlet end of the cooling unit.

[0005] In one possible implementation, the cooling unit includes: The condenser has its inlet end connected to the outlet end of the immersion tank, and its outlet end connected to a circulation pump. The outlet end of the circulation pump is equipped with a flow meter and a pressure sensor.

[0006] In one possible implementation, a regulating main valve is installed at the outlet end of the circulating pump, and an expansion tank is provided at the inlet end of the circulating pump.

[0007] Compared with the prior art, the solution shown in this application uses an immersion tank as the core to install IGBT modules. The tank is equipped with level, pressure, temperature, and density sensors to monitor the cooling conditions in real time. The pressure relief valve at the top of the immersion tank and the flow regulating valve at the liquid inlet are driven by the control system to adjust the internal pressure and coolant flow rate, respectively. During operation, the IGBTs generate heat, causing the immersed insulating coolant to evaporate and absorb heat. The vapor enters the cooling unit from the top of the immersion tank and condenses. The condensate, after cooling, is driven back by a circulating pump, forming a closed loop. This system achieves dynamic coordination of key parameters such as pressure and flow rate through multi-sensor collaborative feedback and linkage control of the pressure relief valve and flow regulating valve. By actively adjusting the internal pressure of the immersion tank, the saturation temperature of the coolant can be directly affected, thereby changing its phase change driving force at the operating temperature. Simultaneously, the flow regulating valve controls the circulating coolant flow rate, adjusting the liquid phase replenishment rate and the fluid flow state within the tank. The coordinated action of these two factors enables the system to comprehensively optimize the evaporation rate and condensation reflux balance of the coolant, thereby achieving indirect and effective regulation of the coolant dryness within the cabinet. This control capability ensures that the cooling medium around the IGBT module is always in an optimal gas-liquid two-phase mixing state, maximizing the utilization of latent heat of phase change and significantly improving the stability and controllability of heat dissipation efficiency.

[0008] In conjunction with the first aspect, this application also provides a control method for a converter IGBT evaporative cooling system, comprising the following steps: S1. The liquid level inside the immersion tank is monitored by the liquid level sensor to adjust the opening of the flow regulating valve, so as to ensure that the IGBT module inside the immersion tank is effectively immersed in the coolant. S2. The dryness of the coolant inside the immersion tank is calculated by monitoring the internal pressure and coolant density. The dryness of the coolant inside the immersion tank is adjusted by regulating the opening of the flow control valve and the internal pressure of the immersion tank.

[0009] In one possible implementation, during the coolant dryness adjustment process in step 2, the opening of the flow control valve is adjusted first to ensure that the IGBT module is always immersed in the coolant. Then, the coolant dryness value is adjusted by regulating the pressure inside the immersion tank through the opening of the pressure relief valve.

[0010] In one possible implementation, during the pressure regulation process inside the immersion tank, the internal pressure is first regulated by adjusting the opening of the pressure relief valve. When the pressure relief valve is fully open or fully closed, the circulation on the cooling unit side is regulated by adjusting the frequency of the circulating pump to achieve the pressure regulation effect.

[0011] In one possible implementation, when the pressure relief valve is fully open or fully closed, when the coolant dryness value exceeds the standard threshold, and when the pressure relief valve is fully open, the flow rate of the coolant inside the immersion tank is adjusted by increasing the opening of the flow regulating valve to adjust the dryness value of the coolant inside the immersion tank before adjusting the circulation pump frequency.

[0012] In one possible implementation, when the coolant dryness value is higher than the standard threshold, the opening of the flow regulating valve is increased to increase the coolant flow rate inside the immersion tank. After the level sensor alarm is cleared, the coolant dryness is re-monitored. If several values ​​still exceed the preset threshold, the opening of the pressure relief valve is then adjusted.

[0013] In one possible implementation, when the coolant dryness value is lower than the standard threshold, the opening of the pressure relief valve is reduced first. If the pressure relief valve is closed, the frequency of the circulation pump is reduced, and the opening of the flow regulating valve is adjusted according to the monitoring information of the liquid level sensor.

[0014] In one possible implementation, there are multiple immersion tanks. After the dryness of the coolant inside the multiple immersion tanks is within the acceptable range, the average dryness of the coolant inside the multiple immersion tanks is calculated. If the dryness of the coolant inside a single immersion tank exceeds the average value by a certain amount, the flow valve corresponding to this immersion tank is adjusted to make the dryness values ​​of the multiple immersion tanks tend to be consistent.

[0015] Compared with the prior art, the solution shown in this application, during the operation of the cooling system, firstly, monitors the liquid level in the immersion tank in real time using a liquid level sensor, and dynamically adjusts the opening of the flow regulating valve in the liquid inlet pipe based on the feedback signal to ensure that the coolant level always covers the IGBT module, providing it with a stable liquid phase cooling environment. At the same time, the system collects the pressure value inside the tank measured by the pressure sensor and the density value of the coolant measured by the density sensor in parallel. Based on the cooling hydraulic enthalpy diagram theory, and through a preset calculation model, such as based on the pressure-density relationship or the thermodynamic equation of state, the system calculates and obtains the current coolant dryness in real time. Subsequently, with the goal of maintaining the target dryness range, the system actively controls the coolant evaporation process and the gas-liquid balance state by coordinating the flow regulating valve to change the liquid phase flow rate and circulation intensity, and by adjusting the pressure relief valve on the top of the tank to change the system pressure and saturation temperature.

[0016] The core benefit of this method lies in the introduction of online dryness calculation and closed-loop control based on pressure and density signals into the IGBT evaporative cooling system. This enables precise sensing and active regulation of the phase change state of the cooling medium, ensuring that the IGBT module is always in a gas-liquid mixture environment with optimal heat exchange efficiency. This fully utilizes the efficient heat dissipation capacity of the latent heat of phase change while avoiding local overheating or temperature fluctuations caused by excessive evaporation or insufficient liquid phase. It fundamentally improves the uniformity, stability, and energy efficiency of heat dissipation, enhances the system's adaptability to different load conditions, and provides a guarantee for the long-term reliable operation and extended lifespan of the IGBT module through direct control of the key state quantity of dryness. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the variable current IGBT evaporative cooling system provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the internal structure of the immersion tank provided in an embodiment of the present invention; Figure 3 A flowchart of a control method for a variable current IGBT evaporative cooling system provided in an embodiment of the present invention.

[0018] Explanation of reference numerals in the attached figures: 1. Immersion tank; 11. Liquid level sensor; 12. Pressure sensor; 13. Temperature sensor; 14. Density sensor; 2. Cooling unit; 21. Condenser; 22. Circulating pump; 23. Flow meter; 24. Pressure sensor; 25. Main regulating valve; 26. Expansion tank; 3. IGBT module; 4. Pressure relief valve; 5. Flow regulating valve. Detailed Implementation

[0019] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0020] Please refer to the following: Figures 1 to 3The present invention will now describe the variable current IGBT evaporative cooling system. The variable current IGBT evaporative cooling system includes an immersion tank 1, a pressure relief valve 4, and a cooling unit 2. The immersion tank 1 is used to install IGBT modules 3. The immersion tank 1 is equipped with a liquid level sensor 11, a pressure sensor 12 for monitoring the internal pressure of the immersion tank 1, a temperature sensor 13 for monitoring the temperature of the coolant inside the immersion tank 1, and a density sensor 14 for monitoring the density of the coolant inside the immersion tank 1. The pressure relief valve 4 is installed on the top of the immersion tank 1 to regulate the internal pressure. A flow regulating valve 5 is installed at the liquid inlet of the immersion tank 1 to regulate the flow rate of the coolant inside the immersion tank 1. The liquid inlet of the cooling unit 2 is connected to the air outlet of the immersion tank 1, and the liquid outlet is connected to the liquid inlet of the immersion tank 1. A circulating pump 22 is connected to the liquid outlet of the cooling unit 2.

[0021] Compared with the prior art, the converter IGBT evaporative cooling system provided in this embodiment uses an immersion tank 1 as the core to install IGBT modules 3. The tank is equipped with level, pressure, temperature, and density sensors 14 to monitor the cooling conditions in real time. The pressure relief valve 4 at the top of the immersion tank 1 and the flow regulating valve 5 at the liquid inlet of the immersion tank 1 are driven by the control system to adjust the internal pressure and coolant flow rate, respectively. During operation, the IGBT heats up, causing the immersed insulating coolant to evaporate and absorb heat. The vapor enters the cooling unit 2 from the top of the immersion tank 1 and condenses. After cooling, the condensate is driven back by the circulation pump 22, forming a closed loop.

[0022] This system utilizes multi-sensor collaborative feedback to dynamically coordinate key parameters such as pressure and flow rate through the linkage control of pressure relief valve 4 and flow regulating valve 5. By actively adjusting the internal pressure of the immersion tank 1, the system directly affects the saturation temperature of the coolant, thereby altering its phase change driving force at the operating temperature. Simultaneously, the flow regulating valve 5 controls the flow rate of the circulating coolant, adjusting the liquid phase replenishment rate and the fluid flow state within the tank. This coordinated action allows the system to comprehensively optimize the coolant evaporation rate and condensation reflux balance, effectively achieving indirect and effective regulation of the coolant dryness within the tank. This control capability ensures that the cooling medium surrounding the IGBT module 3 is always in an optimal gas-liquid two-phase mixing state, maximizing the utilization of latent heat of phase change and significantly improving the stability and controllability of heat dissipation efficiency.

[0023] Specifically, in this embodiment, there are multiple sets of immersion cabinets 1, which are arranged in parallel. The air outlet of each set of immersion cabinets 1 is connected to the liquid inlet of the cooling unit 2, and the liquid inlet of each set of immersion cabinets 1 is connected to the liquid outlet of the cooling unit 2.

[0024] Specifically, in this embodiment, a temperature sensor 13 for monitoring the coolant temperature is installed inside the immersion tank 1. Under saturation conditions, the measured coolant temperature should be basically consistent with the saturation temperature under the current pressure. If the reading of the temperature sensor 13 deviates significantly from the saturation temperature calculated from the pressure, it may mean that the system has not reached saturation, such as being too cold or too hot; or that the pressure sensor 12 and the temperature sensor 13 have drift faults, thus reminding the system to correct and verify the dryness calculation model or measurement data.

[0025] Meanwhile, temperature is the most direct indicator for estimating the junction temperature of the IGBT module and for system thermal safety. Setting the target dryness range inherently requires considering the IGBT's heating frequency and the desired heat dissipation intensity, both of which are closely related to the stable operating temperature the system needs to maintain. The ultimate goal of controlling dryness is to control temperature. Therefore, the temperature signal will serve as an independent, higher-priority protection threshold. For example, when the junction temperature exceeds the safety limit, the system will disregard the current dryness control target and directly implement emergency enhanced cooling measures.

[0026] In some embodiments, the cooling unit 2 described above may employ, for example... Figure 1 The structure shown. See also Figure 1 The cooling unit 2 includes a condenser 21 and a circulating pump 22, a flow meter 23, and a pressure sensor 24 located at the liquid outlet of the condenser 21. The liquid inlet of the condenser 21 is connected to the air outlet of the immersion tank 1, and the liquid outlet is connected to the circulating pump 22. The liquid outlet of the circulating pump 22 is equipped with a flow meter 23 and a pressure sensor 24. During system operation, the multi-parameter sensor network inside the immersion tank 1, namely the liquid level, pressure, temperature, and density sensors 14, together with the flow meter 23 and pressure sensor 24 at the outlet of the cooling unit 2, forms a complete closed-loop monitoring system.

[0027] Specifically, in this embodiment, the IGBT module 3 generates heat, causing the coolant to evaporate. The steam enters the condenser 21 through the top pipe and is liquefied. The liquefied coolant is then driven back by the circulation pump 22, forming a cycle. Flow meters 23 and pressure sensors 24 installed on the loop monitor the flow rate and pressure of the returning coolant in real time, and these signals, along with the pressure, temperature, and density signals within the immersion tank 1, are synchronously uploaded to the control system. The core advantage of this solution is that the system uses a single condenser 21 to uniformly process the steam generated by multiple immersion tanks 1, achieving a high degree of integration and intensive design of the cooling system. While maintaining independent monitoring by their respective internal sensors, multiple immersion tanks 1 share the flow and pressure monitoring of the cooling unit 2 loop, enabling the system to centrally manage the coolant circulation and status of each tank in a unified and coordinated manner.

[0028] Based on a structural design with multiple immersion tanks 1 connected in parallel and linked to condenser 21, the system achieves significant benefits through multi-level collaborative control by integrating independent sensor data from each immersion tank 1 with pressure and flow monitoring on the main cooling loop. Specifically, the pressure and flow signals on the main loop reflect the overall operating status and delivery capacity of the cooling loop, while the pressure, temperature, liquid level, and dryness data within each immersion tank 1 accurately characterize their respective local heat dissipation requirements and phase change states. The control system can use the main loop parameters as system-level constraints and benchmarks, and perform integrated analysis with the independent feedback from each tank, thereby enabling differentiated and precise adjustment of the flow regulating valve 5 at the inlet of each immersion tank 1. This coordinated control mechanism ensures sufficient coolant flow to high-load tanks while avoiding over-flow to low-load tanks, achieving intelligent on-demand distribution of the cooling medium in multiple parallel branches.

[0029] Specifically, in this embodiment, the outlet of the pressure relief valve 4 is connected to the inlet of the condenser 21, and the pressure relief valve 4 is located above the coolant level.

[0030] In some embodiments, the cooling unit 2 described above may employ, for example... Figure 1 The structure shown. See also Figure 1 A regulating valve 25 is installed at the outlet of the circulating pump 22, and an expansion tank 26 is installed at the inlet of the circulating pump 22. In this embodiment, the pressure regulation of the system is achieved through the coordinated operation of the circulating pump 22, the expansion tank 26, and the regulating valve 25: the expansion tank 26 is connected in series at the inlet of the circulating pump 22 and then connected to the regulating valve 25, and the top of each immersion tank 1 is connected to the condenser 21 in a gas phase to form a unified pressure environment. Therefore, the internal pressure of the immersion tank 1 can be assisted by changing the frequency of the circulating pump 22. During the adjustment, the suction capacity of the circulating pump 22 is directly affected by changing its frequency. That is, reducing the frequency of the circulating pump causes the liquid phase in the condenser 21 to be retained and compresses the gas phase space, thereby increasing the system pressure. Increasing the pump frequency expands the gas phase space and reduces the pressure. The expansion tank 26 at the pump inlet absorbs pressure pulsations through internal air cushion buffer, providing a stable pressure boundary for the inlet of the circulating pump 22. On the basis of this stable pressure, the main valve 25 is adjusted to maintain the total flow of the system, and the flow regulating valves 5 of each branch independently and finely distribute the flow according to parameters such as liquid level, temperature and dryness in each immersion tank 1, so as to achieve coordinated control of global pressure regulation and local flow distribution.

[0031] Based on the same inventive concept, this application also provides a control method for a converter IGBT evaporative cooling system, see [link to relevant documentation]. Figure 3 This includes the following steps: S1. The liquid level inside the immersion tank 1 is monitored by the liquid level sensor 11, and the opening of the flow regulating valve 5 is adjusted to ensure that the IGBT module 3 inside the immersion tank 1 is effectively immersed in the coolant. S2. The dryness of the coolant inside the immersion tank 1 is calculated by monitoring the internal pressure and coolant density. The dryness of the coolant inside the immersion tank 1 is adjusted by adjusting the opening of the flow regulating valve 5 and the internal pressure of the immersion tank 1.

[0032] Compared with the prior art, the solution shown in this application embodiment first monitors the liquid level in the immersion tank 1 in real time through the liquid level sensor 11 during the operation of the cooling system. Based on this feedback signal, the opening of the flow regulating valve 5 in the liquid inlet pipeline is dynamically adjusted to ensure that the liquid level of the coolant always covers the IGBT module 3, providing it with a stable liquid phase cooling environment. At the same time, the system collects the pressure value inside the tank measured by the pressure sensor 12 and the density value of the coolant measured by the density sensor 14 in parallel. Based on the cooling hydraulic enthalpy diagram theory, the system calculates and obtains the current dryness of the coolant in real time through a preset calculation model, such as based on the relationship between pressure and density. Subsequently, with the goal of maintaining the target dryness range, the system adjusts the flow regulating valve 5 in a coordinated manner to change the liquid phase flow rate and circulation intensity, and the pressure relief valve 4 on the top of the tank to change the system pressure and saturation temperature, thereby realizing active control of the coolant evaporation process and the gas-liquid balance state.

[0033] The core benefit of this method lies in the introduction of online dryness calculation and closed-loop control based on pressure and density signals into the IGBT evaporative cooling system. This enables precise sensing and active regulation of the phase change state of the cooling medium, ensuring that the IGBT module 3 is always in a gas-liquid mixing environment with optimal heat transfer efficiency. This fully utilizes the efficient heat dissipation capacity of the latent heat of phase change while avoiding local overheating or temperature fluctuations caused by excessive evaporation or insufficient liquid phase. It fundamentally improves the uniformity, stability, and energy efficiency of heat dissipation, enhances the system's adaptability to different load conditions, and provides a guarantee for the long-term reliable operation and extended lifespan of the IGBT module 3 through direct control of the key state quantity of dryness.

[0034] Preferably, in this embodiment, the optimal operating target range for coolant dryness is defined as between 0.1 and 0.25. For control purposes, a low dryness adjustment threshold of 0.1 is set, and adjustment is initiated when the dryness value is below this value; a high dryness adjustment threshold of 0.25 is set, and adjustment is initiated when the dryness value is above this value; and a danger alarm threshold of 0.3 is set, and emergency protection is activated when the dryness value exceeds this value.

[0035] Based on the above control method, in step 2, during the coolant dryness adjustment process, the opening of the flow regulating valve 5 is adjusted first to ensure that the IGBT module 3 is always immersed in the coolant. Then, the pressure inside the immersion tank 1 is adjusted by regulating the opening of the pressure relief valve 4, thereby adjusting the coolant dryness value. During operation, the control system first adjusts the opening of the flow regulating valve 5 of each immersion tank 1 according to the signal from the liquid level sensor 11, ensuring that the IGBT module 3 is always completely immersed in the coolant. At this time, the change in the opening of the regulating valve maintains the stability of the liquid level, and the process of adjusting the coolant flow rate has an active influence on the flow state of the working fluid and the local heat exchange conditions inside the tank, constituting the first-level basic adjustment of the coolant dryness. After the liquid level stabilizes, the system then actively adjusts the pressure of the gas phase space inside the tank by adjusting the opening of the pressure relief valve 4 at the top of the immersion tank 1 based on the real-time calculated dryness value. The pressure change directly changes the saturation temperature and evaporation equilibrium point of the coolant, thereby achieving the second-level precise adjustment of the dryness. The two-stage adjustment process is executed step by step in terms of timing, but works synergistically in terms of control logic.

[0036] The beneficial effects of this control method are as follows: by establishing a hierarchical control strategy that prioritizes liquid level, assists in dryness control with flow rate, and precisely regulates pressure, the decoupling and optimization of multiple control objectives are achieved. The primary function of the flow regulating valve 5 is clearly defined as ensuring the basic premise of IGBT immersion safety, while also assigning it a basic role in dryness regulation. The pressure relief valve 4 is dedicated to fine-tuning dryness control based on pressure changes, resulting in a clear division of labor and complementary functions between the two actuators. This step-by-step, collaborative control logic not only fundamentally ensures the heat dissipation safety boundary of the IGBT module 3, but also achieves more stable, precise, and efficient control of the core state parameter of coolant dryness through the orderly adjustment of the two key physical quantities, flow rate and pressure. This significantly improves the overall reliability, response speed, and controllability of the evaporative cooling process.

[0037] Specifically, in this embodiment, during the pressure regulation process inside the immersion tank 1, the system first directly regulates the internal pressure of the immersion tank 1 by adjusting the opening of the pressure relief valve 4. When the adjustment capacity of the pressure relief valve 4 reaches its limit, the second-stage regulation mechanism is activated, which changes the system circulation state by adjusting the frequency of the circulating pump 22. The adjustment of the frequency of the circulating pump 22 affects the gas-liquid balance inside the condenser 21 by changing the flow rate on the pump suction side, thereby adjusting the pressure in the gas phase space of the immersion tank 1 connected to it. On the other hand, the change in pump outlet pressure will be buffered by the expansion tank 26 connected in series in the pipeline, and then work in conjunction with the regulating main valve 25 to assist in pressure regulation by adjusting the pressure difference between the liquid inlet and liquid outlet of the immersion tank 1.

[0038] Throughout the adjustment process, the system monitors the total flow rate in real time through the flow meter 23 on the main pipeline and processes the liquid level signal of each immersion tank 1 simultaneously to ensure that the frequency adjustment of the circulating pump 22 is always based on ensuring the minimum circulating flow rate required by each tank, thereby maintaining the IGBT module 3 in a safe state of complete immersion.

[0039] Specifically, adjusting the frequency of the circulating pump 22 not only changes the pump's outlet pressure, but more importantly, it affects the gas-liquid balance inside the condenser 21 by adjusting its suction side operating conditions, which in turn transmits to the gas phase space of the immersion tank 1 connected to it, thus achieving auxiliary fine adjustment of the pressure. During the entire pressure adjustment process, the system monitors the total flow rate in real time through the flow meter 23 and processes the liquid level signals of each immersion tank 1 simultaneously, ensuring that the frequency adjustment of the circulating pump 22 always takes into account the minimum coolant circulation flow required by each tank, and maintains the fully immersed state of the IGBT module 3.

[0040] Specifically, the beneficial effects of this control method lie in the construction of a multi-level, multi-path intelligent pressure regulation system: the direct regulation of the pressure relief valve 4 and the system-level regulation of the circulating pump 22 complement each other, significantly expanding the system's pressure regulation range and enhancing its ability to cope with extreme working conditions; through the gas-liquid balance regulation of the condenser 21 on the suction side of the circulating pump 22 and the coordinated control of the pipeline pressure difference by the circulating pump 22 and the regulating main valve 25, a dual action path for the pressure of the immersion tank 1 is formed, improving the pressure regulation range and dynamic response speed; setting the liquid level maintenance as a hard constraint condition for pump frequency regulation ensures that the system does not sacrifice basic heat dissipation safety at any regulation stage; the buffering effect of the expansion tank 26 ensures the stability of the pressure regulation process and avoids impact on the evaporative cooling process.

[0041] Specifically, when the coolant dryness value is higher than the standard threshold and the pressure relief valve 4 is fully open, before adjusting the frequency of the circulating pump 22, the flow rate of the coolant inside the immersion tank 1 is adjusted by increasing the opening of the flow regulating valve 5, thereby adjusting the dryness value of the coolant inside the immersion tank 1. However, the adjustment of the opening of the flow regulating valve 5 needs to ensure that the IGBT module 3 is always immersed in the coolant. If the dryness is within the acceptable range after adjusting the opening of the flow regulating valve 5, the frequency of the circulating pump 22 will not be adjusted. The specific implementation process is as follows: When the system is running, firstly, based on the internal pressure sensor 12 of the immersion tank 1 and the dryness calculation model, the opening of the pressure relief valve 4 is adjusted first to control the gas phase pressure, thereby achieving the initial adjustment of the coolant dryness; when the opening of the pressure relief valve 4 reaches the fully open limit position and the dryness value still does not reach the acceptable range, the system will enter the second-level adjustment stage, by increasing the opening of the flow regulating valve 5 of each immersion tank 1 inlet branch, changing the flow rate and flow distribution of the coolant entering each tank. The adjustment process requires real-time monitoring of the liquid level sensor 11 signal to ensure that any adjustment of the opening of the flow regulating valve 5 is based on the absolute premise that the IGBT module 3 is always completely submerged. If the real-time dryness value calculated by the system has entered the preset qualified range through the adjustment of the opening of the flow regulating valve 5, the control process will terminate and the frequency of the circulation pump 22 will remain at the current setting without adjustment. Only when the dryness is still unqualified after the adjustment of the flow regulating valve 5, and the liquid level of each cabinet is within the safe threshold, will the system start the third-level adjustment to assist in optimizing the system circulation state by fine-tuning the frequency of the circulation pump 22.

[0042] This control method achieves multiple optimization effects by establishing a hierarchical regulation strategy that prioritizes pressure, followed by flow rate, and then uses pump frequency as a backup. First, the method fully respects the regulation characteristics and energy efficiency differences of different actuators, prioritizing the use of the fastest-responding pressure relief valve 4 for primary dryness regulation. When the regulation capacity is insufficient, the flow regulating valve 5 is used for supplementary regulation, while the frequency regulation of the high-energy-consuming circulating pump 22 is used as a last resort. This sequence effectively improves the overall energy efficiency of the system. Second, by using liquid level safety as a hard constraint for the action of the flow regulating valve 5 and immediately terminating the regulation process after the dryness is qualified, unnecessary pump frequency adjustments and energy consumption are avoided, reflecting the energy-saving optimization concept of stopping when the requirement is met.

[0043] Furthermore, this hierarchical discrimination logic significantly simplifies the complexity of multivariate coordinated control, enhances the decision-making clarity and operational reliability of the system under different operating conditions, and extends the service life of key moving equipment by reducing the frequent adjustment of the circulating pump 22. Finally, this method achieves the best balance between control accuracy, response speed, system energy efficiency and equipment life while ensuring heat dissipation performance and operational safety.

[0044] Specifically, excessively high coolant dryness indicates an excessively high vapor-phase ratio, which may affect the effective wetting of the module surface by the liquid coolant. In this case, increasing the coolant circulation flow rate can enhance liquid scouring and replenishment of the module surface, disrupting any potential localized vapor films and improving heat transfer conditions, thus adjusting the dryness to a reasonable range. Conversely, excessively low coolant dryness indicates that the system is not fully utilizing the latent heat of phase change. In this situation, while ensuring a safe liquid level, other parameters can be adjusted, such as reducing system pressure, to promote boiling, while simultaneously optimizing the flow rate to establish an efficient and stable gas-liquid two-phase heat transfer state, thereby removing more heat.

[0045] Specifically, in this embodiment, in step 2, when the coolant dryness value is higher than the standard threshold, the opening of the flow regulating valve 5 is increased to increase the coolant flow rate inside the immersion tank 1. After the alarm of the level sensor 11 is cleared, the coolant dryness is re-monitored. If several values ​​still exceed the preset threshold, the opening of the pressure relief valve 4 is adjusted. The system calculates the coolant dryness value in real time. When the dryness is detected to exceed the preset safety upper limit, the opening of the corresponding flow regulating valve 5 in the inlet pipe of the immersion tank 1 is immediately increased to quickly increase the coolant flow rate. During this process, the liquid level inside the tank is continuously monitored. After the liquid level returns to the safe range and the alarm is cleared, the system recalculates the dryness value and makes a judgment: if several values ​​have returned to normal, the adjustment ends; if it still exceeds the standard, the second step of adjustment is initiated, increasing the opening of the pressure relief valve 4 at the top of the immersion tank 1 to reduce the internal pressure of the system. The pressure reduction lowers the saturation temperature of the coolant, thereby suppressing excessive boiling, promoting gas-liquid balance, and achieving the correction of dryness.

[0046] Specifically, when the coolant dryness value is lower than the standard threshold, the opening of the pressure relief valve 4 is reduced first; if the pressure relief valve 4 is completely closed, the frequency of the circulating pump 22 is reduced, and the opening of the flow regulating valve 5 is adjusted according to the monitoring information of the liquid level sensor 11. The system calculates the coolant dryness in real time. When the dryness value is determined to be lower than the preset lower limit, the opening of the pressure relief valve 4 at the top of the immersion tank 1 is gradually reduced to increase the internal pressure of the system, thereby adjusting the thermodynamic equilibrium point of the system by raising the boiling point; if the pressure relief valve 4 has been adjusted to a completely closed state and the dryness still fails to rise to the qualified range, the control system starts the second-stage adjustment, reducing the operating frequency of the circulating pump 22 to reduce the total circulating flow of the system, thereby slowing down the coolant flow rate, increasing its overall temperature and superheat, and creating conditions for promoting stable boiling; under the above pressure Throughout the entire process of force and total flow regulation, the system monitors the signals of the liquid level sensors 11 in each immersion tank 1 in parallel and independently, and uses these signals as the highest priority constraint to dynamically and adaptively adjust the opening of the corresponding branch flow regulating valve 5: when the liquid level in a tank approaches the lower safety limit due to the decrease in total flow, the opening of the flow valve in that tank is increased to prioritize immersion safety; for tanks with sufficient liquid level, the opening is maintained or finely adjusted to optimize the local flow field, and finally, through the synergistic effect of pressure, system flow and branch distribution, the dryness is smoothly restored to the efficient working range.

[0047] Preferably, this control method achieves multiple significant benefits by constructing a three-level collaborative control architecture with pressure regulation as the priority, system flow regulation as the follow-up, and liquid level safety adaptive protection: First, by orderly regulating the pressure relief valve 4 and the circulating pump 22, the problems of excessively low dryness and insufficient boiling are systematically solved from both thermodynamic conditions and heat transfer driving force perspectives, promoting the formation of an efficient and stable two-phase flow state; Second, the signal from the liquid level sensor 11 is used as an independent and highest-priority real-time constraint, and the flow of each branch is adaptively adjusted accordingly, ensuring that the immersion safety of the IGBT module 3 is absolutely guaranteed at any adjustment stage, fundamentally eliminating the risk of secondary dry burning caused by the optimization process; In addition, this strategy clearly defines the control boundaries and response sequences of different actuators, avoiding regulation conflicts, making the system response faster and the control more stable, while achieving energy saving by reducing the pump operating frequency.

[0048] Preferably, in this embodiment, there are multiple immersion tanks 1. After the coolant dryness inside multiple immersion tanks 1 is within the acceptable range, the average value of the coolant dryness inside multiple immersion tanks 1 is calculated. If the coolant dryness inside a single immersion tank 1 exceeds the average value by a certain amount, the flow valve corresponding to this immersion tank 1 is adjusted to make the dryness values ​​of multiple immersion tanks 1 tend to be consistent. The system monitors the operating status of all parallel immersion tanks 1 in parallel. When the coolant dryness value calculated independently by each tank is within the preset acceptable range, the control system calculates the arithmetic mean of the dryness values ​​of all immersion tanks 1 in real time as the system reference dryness. The system continuously compares the deviation of the real-time dryness of each tank with the reference dryness. When the dryness value of any immersion tank 1 is detected to deviate from the system reference dryness by more than a preset tolerance threshold, such as ±10%, it is determined that the tank is in a state of dryness imbalance. At this point, the system does not change the total frequency of the circulating pump 22 or the total system pressure setting. Instead, it fine-tunes the opening of the flow regulating valve 5 on the inlet branch of the specific immersion tank 1: if the dryness is significantly higher than the average, the opening of the flow regulating valve for that tank is appropriately increased to reduce its local dryness by increasing the liquid supply and flushing intensity; if the dryness is significantly lower than the average, the opening of the flow regulating valve for that tank is appropriately decreased to increase its dryness by slowing down the flow rate and enhancing local heat storage. This adjustment process is a closed-loop iteration based on the premise that the liquid level of each tank is always within the safe range, until the dryness values ​​of all immersion tanks 1 are stable within the reference dryness tolerance zone, thereby achieving a high degree of balance in the dryness distribution of multiple tanks.

[0049] This control method achieves high-precision thermal balance control of a multi-parallel immersion cabinet system by introducing a distributed collaborative fine-tuning mechanism based on the average dryness value. Specific benefits include: First, based on the overall stable operation of the system, it enables refined management of the heat dissipation status of each independent power unit. By specifically adjusting local flow rates, it effectively eliminates differences in thermal state between cabinets caused by differences in pipe resistance, uneven local heat loads, or manufacturing tolerances, ensuring that all IGBT modules operate in a highly consistent optimized thermal environment, greatly improving the overall temperature uniformity and reliability of the system. Second, this method adopts a precise control principle of solving local problems locally, eliminating the need for frequent changes in the frequency of the circulating pump 22 or the system pressure setting, avoiding repeated disturbances to the entire system's operating conditions, and significantly improving the overall operational stability and energy efficiency. Third, this equalization control can automatically adapt to the dynamic changes in the load of each cabinet, achieving intelligent on-demand allocation of heat dissipation resources. This prevents the risk of local overheating and avoids the waste of cooling resources, thereby extending the overall system's service life while ensuring equipment safety.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A converter IGBT evaporative cooling system, characterized in that, include: Immersion cabinet (1) for installing IGBT module (3), the immersion cabinet (1) is equipped with a liquid level sensor (11), a pressure sensor (12) for monitoring the internal pressure of the immersion cabinet (1), a temperature sensor (13) for monitoring the internal temperature of the coolant in the immersion cabinet (1), and a density sensor (14) for monitoring the internal density of the coolant in the immersion cabinet (1). A pressure relief valve (4) is installed on the top of the immersion tank (1) to regulate the internal pressure of the immersion tank (1); A flow regulating valve (5) is installed at the liquid inlet of the immersion tank (1) to regulate the flow rate of the coolant inside the immersion tank (1); The cooling unit (2) has its inlet end connected to the outlet end of the immersion tank (1), its outlet end connected to the inlet end of the immersion tank (1), and a circulation pump (22) connected to the outlet end of the cooling unit (2).

2. The converter IGBT evaporative cooling system as described in claim 1, characterized in that, The cooling unit (2) includes: The condenser (21) has its inlet end connected to the outlet end of the immersion tank (1), and its outlet end is connected to a circulation pump (22). The outlet end of the circulation pump (22) is equipped with a flow meter (23) and a pressure sensor (24).

3. The converter IGBT evaporative cooling system as described in claim 2, characterized in that, A regulating valve (25) is installed at the outlet end of the circulating pump (22), and an expansion tank (26) is provided at the inlet end of the circulating pump (22).

4. A control method for a converter IGBT evaporative cooling system, employing the converter IGBT evaporative cooling system as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. The liquid level inside the immersion tank (1) is monitored by the liquid level sensor (11) to adjust the opening of the flow regulating valve (5) to ensure that the IGBT module (3) inside the immersion tank (1) is effectively immersed in the coolant. S2. The dryness of the coolant inside the immersion tank (1) is calculated by monitoring the internal pressure and coolant density of the immersion tank (1), and the dryness of the coolant inside the immersion tank (1) is adjusted by adjusting the opening of the flow regulating valve (5) and the internal pressure of the immersion tank (1).

5. The control method for the converter IGBT evaporative cooling system as described in claim 4, characterized in that, In step 2, during the coolant dryness adjustment process, the opening of the flow regulating valve (5) is adjusted first so that the IGBT module (3) is always immersed in the coolant. Then, the coolant dryness value is adjusted by adjusting the opening of the pressure relief valve (4) and adjusting the pressure inside the immersion tank (1).

6. The control method for the converter IGBT evaporative cooling system as described in claim 5, characterized in that, During the internal pressure regulation process of the immersion tank (1), the internal pressure is first regulated by adjusting the opening of the pressure relief valve (4). When the pressure relief valve (4) is fully open or fully closed, the circulation on the cooling unit (2) side is regulated by adjusting the frequency of the circulation pump (22) to achieve the pressure regulation effect.

7. The control method for the converter IGBT evaporative cooling system as described in claim 6, characterized in that, When the coolant dryness value exceeds the standard threshold and the pressure relief valve (4) is fully open, before adjusting the frequency of the circulating pump (22), the flow rate of the coolant inside the immersion tank (1) is adjusted by increasing the opening of the flow regulating valve (5) to adjust the dryness value of the coolant inside the immersion tank (1).

8. The control method for the converter IGBT evaporative cooling system as described in claim 5, characterized in that, When the coolant dryness value is higher than the standard threshold, the opening of the flow regulating valve (5) is increased to increase the coolant flow rate inside the immersion tank (1). After the alarm of the liquid level sensor (11) is cleared, the coolant dryness is re-monitored. If the value still exceeds the preset threshold, the opening of the pressure relief valve (4) is then adjusted.

9. The control method for the converter IGBT evaporative cooling system as described in claim 6, characterized in that, When the coolant dryness value is lower than the standard threshold, the opening of the pressure relief valve (4) is reduced first. If the pressure relief valve (4) is closed, the frequency of the circulation pump (22) is reduced. At the same time, the opening of the flow regulating valve (5) is adjusted according to the monitoring information of the liquid level sensor (11).

10. The control method for the converter IGBT evaporative cooling system as described in claim 4, characterized in that, The number of immersion tanks (1) is multiple. After the dryness of the coolant inside the multiple immersion tanks (1) is within the qualified range, the average dryness of the coolant inside the multiple immersion tanks (1) is calculated. If the dryness of the coolant inside a single immersion tank (1) exceeds the average value by a certain amount, the flow valve corresponding to this immersion tank (1) is adjusted to make the dryness values ​​of the multiple immersion tanks (1) tend to be consistent.

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