Converter valve junction temperature abnormity protection method and system based on water cooling flow rate adjustment

Abstract

A converter valve junction temperature anomaly protection method and system according to water cooling flow velocity adjustment comprises the steps of using a temperature sensor to measure the junction temperature of each through-flow element of a converter valve in real time, and calculating the comprehensive junction temperature anomaly index of each through-flow element according to the junction temperature and the junction temperature change rate; if the comprehensive junction temperature abnormal index of the through-flow element is larger than or equal to the set index threshold value of the corresponding through-flow element, the maximum flow speed of the water cooling system is calculated according to the rated power of the water cooling system by combining on-way resistance and local resistance of the water cooling system; establishing a loss function combining heating related loss of the corresponding through-flow element, thermal resistance from a radiator of the water cooling system to a cooling medium and inlet and outlet water temperature; and with the maximum flow velocity as a constraint condition, the flow velocity is adjusted until the loss function is minimum. According to the invention, the water cooling flow rate can be dynamically adjusted to control cooling when the junction temperature of the converter is abnormal, and the operation safety is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of converter valve safety protection, and more specifically, relates to a method and system for protecting a converter valve from abnormal junction temperature based on water cooling flow rate regulation. Background Art

[0002] The losses in the flow-passing elements in the converter valve, such as the thyristors and IGBT elements in the controllable phase-changing converter valve, during operation will cause the junction temperature of the elements to rise. In some applications, changes in the working load, ambient temperature, current load, and switching frequency of the converter valve will also cause the junction temperature of the converter valve elements to fluctuate. In particular, when the elements are aged and damaged, the gate control is unstable, and there is external electromagnetic interference, the junction temperature of the elements may suddenly change or rise sharply, causing the elements and equipment to be in a high temperature state. For the sake of safety protection design, in order to ensure that the junction temperature of the thyristors and IGBT elements is within the allowable range during steady-state operation, a water cooling system is required to dissipate heat.

[0003] CN116973720A proposes a method and system for estimating the junction temperature of an electric vehicle IGBT module, which belongs to the field of estimating the junction temperature of an electric vehicle IGBT. The method includes performing current deviation, voltage deviation and temperature deviation on the electric vehicle IGBT module under actual working conditions according to the principle of double pulse testing, and obtaining the IGBT device turn-on loss, IGBT device turn-off loss and diode reverse recovery loss; obtaining the working parameters of the electric vehicle IGBT module, and obtaining the loss result according to the working parameters, IGBT device turn-on loss, IGBT device turn-off loss and diode reverse recovery loss using the IGBT module loss calculation method; obtaining the IGBT thermal impedance considering the coolant water temperature and flow rate according to the step response method; obtaining the junction temperature of the electric vehicle IGBT module according to the loss result and the IGBT thermal impedance considering the coolant water temperature and coolant flow rate. However, this patent only detects abnormal junction temperature and does not reduce the temperature to prevent overheating; CN119051642A proposes a MOS field effect tube gate driving method, device, equipment and storage medium, the method includes: sampling the original driving signal of the MOS field effect tube to obtain a first driving signal; establishing a dynamic characteristic data table; calculating the nonlinear ideal gate voltage change curve and obtaining a second driving signal; amplifying, connecting with the MOS field effect tube gate through a dynamic impedance matching network, obtaining a power matching signal; inputting the current detection result into a digital signal processor to obtain an adaptive driving signal; analyzing the change rate of the drain-source voltage and estimating the junction temperature, and adjusting the slope and amplitude of the adaptive driving signal when an abnormality is detected. This patent reduces the junction temperature by adjusting the slope and amplitude of the adaptive driving signal when the junction temperature is abnormal, but it will change the driving condition of the converter, and does not take into account the situation of component damage, etc., and the junction temperature cannot be reduced by adjusting the driving signal, resulting in safety hazards.

[0004] CN118517777A proposes an environmental adaptability intelligent adjustment system for a water-cooling machine, including an environmental perception module, a data processing module, a cooling demand prediction module, an intelligent adjustment module, an actuator module, and a fault prediction and self-healing module. The environmental perception module monitors the ambient temperature in real time, the data processing module analyzes and processes the environmental data, the cooling demand prediction module predicts the optimal cooling strategy, the intelligent adjustment module calculates the optimal operating instructions, the actuator module adjusts the operating parameters of the water-cooling machine, and the fault prediction and self-healing module performs early warning and processing before the fault occurs. When the fault occurs, the self-healing mechanism is activated. However, this patent only adjusts the water cooling system according to the temperature data of the water-cooling machine itself and the temperature that needs to be adjusted, and is not combined with the actual equipment that needs to be cooled, and does not consider the power loss problem of the water cooling system. Summary of the invention

[0005] In order to solve the deficiencies in the prior art, the present invention provides a method and system for protecting a converter valve from abnormal junction temperature according to water cooling flow rate regulation.

[0006] The present invention adopts the following technical solution.

[0007] The first aspect of the present invention provides a method for protecting a converter valve from abnormal junction temperature according to water cooling flow rate regulation, comprising the following contents: Using a temperature sensor to measure the junction temperature of each flow element of the converter valve in real time, the flow element includes a thyristor and an IGBT, and measuring the inlet and outlet water temperatures of the water cooling system, and calculating the comprehensive junction temperature abnormality index of each flow element according to the junction temperature and the junction temperature change rate; If the comprehensive junction temperature abnormality index of the flow element is greater than or equal to the set index threshold of the corresponding flow element, the thermal resistance curve between the flow rate and the thermal resistance from the radiator to the cooling medium of the water cooling system is obtained through simulation; the maximum flow rate of the water cooling system is calculated according to the rated power of the water cooling system in combination with the along-the-line resistance and local resistance of the water cooling system; Establish a loss function combining the heat-related losses of the corresponding flow-through elements, the thermal resistance from the radiator to the cooling medium of the water cooling system, and the inlet and outlet water temperatures; Taking the maximum flow rate as the constraint, the flow rate is continuously adjusted. After each adjustment, the thermal resistance from the radiator to the cooling medium of the water cooling system corresponding to the adjusted flow rate is obtained by querying the thermal resistance curve. The heat-related losses of the corresponding flow-through elements are calculated after each adjustment, thereby calculating the loss function after each adjustment, and adjusting the flow rate until the loss function reaches the minimum.

[0008] Preferably, the temperature sensor is a resistance temperature detector (RTD) or a thermocouple; when the flow element is a thyristor, the anode and cathode of the thyristor are both connected to the radiator of the water cooling system; the thyristor junction temperature is the average temperature measured at the anode and cathode of the thyristor; when the flow element is an IGBT, the collector and emitter of the IGBT are both connected to the radiator of the water cooling system; the IGBT junction temperature is the average temperature measured at the collector and emitter of the IGBT.

[0009] Preferably, the comprehensive junction temperature abnormality index The calculation formula is:

[0010] In the formula, is a coefficient with a value of 0-1. is the junction temperature change rate, , are the junction temperatures of the flow element measured at the last moment and this moment respectively, , They are the time of the previous moment and the time of this moment respectively.

[0011] Preferably, the value range of the index threshold of the corresponding flow element is:

[0012] In the formula, is the maximum junction temperature of the corresponding flow element.

[0013] Preferably, the maximum flow rate of the water cooling system is calculated according to the rated power of the water cooling system in combination with the along-the-line resistance and the local resistance of the water cooling system, specifically: The formula for calculating the sum of the maximum along-the-line resistance and the maximum local resistance based on the maximum flow rate and rated power of the water cooling system is:

[0014] In the formula, is the maximum resistance along the path, is the maximum local resistance, d is the inner diameter of the pipe, is the set maximum power factor, is the flow coefficient, is the density of the coolant in the water cooling system, is the acceleration due to gravity, is the rated power of the water cooling system, is the maximum flow rate; The formula for calculating the maximum along-the-way resistance and the maximum local resistance based on the maximum flow velocity is:

[0015]

[0016] In the formula, C h is the Haicheng William coefficient; is the local resistance coefficient; The two formulas for calculating the maximum along-the-path resistance and the maximum local resistance according to the maximum flow velocity are substituted into the sum of the maximum along-the-path resistance and the maximum local resistance calculated according to the maximum flow velocity and rated power of the water cooling system, and the maximum flow velocity of the water cooling system is obtained by iterative solution.

[0017] Preferably, the flow coefficient By simulating the water cooling system, the flow rate corresponding to the flow velocity is obtained, and the flow rate corresponding to the flow velocity is calculated using the flow coefficient, the relationship between the flow velocity and the flow rate, or it is set according to the pipeline design of the water cooling system and the additional components of the water cooling system, the pipeline design includes the selection of pipe diameters and the series and parallel connection of water channels; the additional components include pipeline elbows, valves, and joints; The relationship formula between flow coefficient, flow velocity and flow rate:

[0018] In the formula, For flow, is the flow rate.

[0019] Preferably, the establishment combines the heat-related losses of the flow element corresponding to the moment, the thermal resistance from the radiator to the cooling medium of the water cooling system, and the loss function of the inlet and outlet water temperatures, takes the maximum flow rate as a constraint, and dynamically adjusts the flow rate with the minimum loss function as the goal, specifically: Loss Function for:

[0020] In the formula, The corresponding heat loss of the flow element at this moment is: is the junction-to-case thermal resistance from die to case, is the thermal contact resistance from the tube shell to the radiator of the water cooling system, The thermal resistance from the radiator to the cooling medium of the water cooling system corresponding to the flow rate at this moment is: is the proportional coefficient of heat dissipation from the tube shell directly to the external environment, , are the inlet water temperature and outlet water temperature, is the rated junction temperature of the corresponding flow element.

[0021] The heat-related losses of the flow-through element are specifically: If the flow element is a thyristor, the loss of the flow element is the sum of the conduction loss, turn-on loss and turn-off loss of the thyristor. If the flow element is an IGBT, the loss of the flow element is the conduction loss of the IGBT.

[0022] Preferably, the conduction loss of the IGBT The calculation formula is:

[0023] In the formula, is the on-state voltage of the IGBT, is the current through the IGBT, is the IGBT switching frequency; Conduction loss of thyristor , Turn-on loss and turn-off losses The calculation formulas are:

[0024]

[0025]

[0026] In the formula, is the conduction voltage drop of the thyristor, is the conduction current of the thyristor, is the duty cycle of the thyristor conduction; is the voltage of the thyristor during the turn-on process, is the current of the thyristor during the turn-on process, is the operating frequency of the thyristor, is the turn-on time of the thyristor, is the turn-off time of the thyristor.

[0027] The second aspect of the present invention provides a system for protecting a converter valve from abnormal junction temperature by adjusting the water cooling flow rate using the method described in the first aspect of the present invention, comprising a measurement module, a comprehensive junction temperature abnormality index calculation module, a maximum flow rate calculation module, a loss function establishment module, and a flow rate adjustment module, characterized in that: Measuring module: used to measure the junction temperature of each flow element of the controllable phase-changing valve in real time using a temperature sensor, the flow element including a thyristor and an IGBT, and measure the inlet and outlet water temperatures of the water cooling system; Comprehensive junction temperature abnormality index calculation module: used to calculate the comprehensive junction temperature abnormality index of each flow element according to the junction temperature and the junction temperature change rate; if there is a flow element whose comprehensive junction temperature abnormality index is greater than or equal to the set corresponding flow element index threshold, then obtain the thermal resistance curve between the flow rate and the thermal resistance from the radiator to the cooling medium of the water cooling system through simulation; Maximum flow rate calculation module: Combines the resistance along the water cooling system and the local resistance, and calculates the maximum flow rate of the water cooling system according to the rated power of the water cooling system; Loss function establishment module: establishes a loss function combining the heat-related losses of the corresponding flow-through elements, the thermal resistance from the radiator to the cooling medium of the water cooling system, and the inlet and outlet water temperatures; Flow rate regulation module: With the maximum flow rate as the constraint, the flow rate is continuously adjusted. After each adjustment, the thermal resistance from the radiator to the cooling medium of the water cooling system corresponding to the adjusted flow rate is obtained by querying the thermal resistance curve. After each adjustment, the heat-related losses of the corresponding flow-through elements are calculated, thereby calculating the loss function after each adjustment and adjusting the flow rate until the loss function reaches the minimum.

[0028] The beneficial effects of the present invention are that, compared with the prior art, the present invention measures the junction temperature of the flow element of the converter valve, calculates the comprehensive junction temperature abnormality index of each flow element according to the junction temperature and the junction temperature change rate, judges whether it is abnormal through the comprehensive junction temperature abnormality index, and adjusts the water cooling, taking into account the sudden change situation; the present invention combines the along-the-line resistance and local resistance of the water cooling system, calculates the maximum flow rate of the water cooling system according to the rated power of the water cooling system, and controls the power of the water cooling system within a certain range while adjusting the flow rate, so that the water cooling adjustment is more reasonable; the present invention establishes a loss function combining the heat-related losses of the corresponding flow element, the thermal resistance from the radiator to the cooling medium of the water cooling system, and the inlet and outlet water temperatures; the water cooling flow rate is dynamically adjusted by the loss function, which can effectively prevent the damage of the component caused by excessive junction temperature without increasing the loss of the water cooling system too much, so that the temperature of the flow element is kept within a safe range. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a flow chart of the present invention; Figure 2 It is the equivalent thermal circuit diagram of the flow element. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only embodiments of a part of the present invention, rather than all embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0031] like Figure 1 As shown, Embodiment 1 of the present invention proposes a method for protecting a converter valve from abnormal junction temperature according to water cooling flow rate regulation, including the following contents: Using a temperature sensor to measure the junction temperature of each flow element of the converter valve in real time, the flow element includes a thyristor and an IGBT, and measuring the inlet and outlet water temperatures of the water cooling system, and calculating the comprehensive junction temperature abnormality index of each flow element according to the junction temperature and the junction temperature change rate; It should be noted that the converter valve used in this embodiment is a controllable phase-changing converter valve.

[0032] If the comprehensive junction temperature abnormality index of the flow element is greater than or equal to the set index threshold of the corresponding flow element, the thermal resistance curve between the flow rate and the thermal resistance from the radiator to the cooling medium of the water cooling system is obtained through simulation; the maximum flow rate of the water cooling system is calculated according to the rated power of the water cooling system in combination with the along-the-line resistance and local resistance of the water cooling system; It should be noted that if the subsequently calculated adjusted flow rate is too large, it may cause the operating power of the water cooling system to be difficult to match it. Therefore, the maximum flow rate is calculated by combining the along-the-line resistance and local resistance of the water cooling system, and the flow rate is adjusted within this range; if the flow rate is too low and the ambient temperature is also too low, resulting in low inlet and outlet water temperatures, an electric heater is added near the water cooling system to force compensation for the cooling water temperature to prevent condensation caused by too low temperature.

[0033] Establish a loss function combining the heat-related losses of the corresponding flow-through elements, the thermal resistance from the radiator to the cooling medium of the water cooling system, and the inlet and outlet water temperatures; Taking the maximum flow rate as the constraint, the flow rate is continuously adjusted. After each adjustment, the thermal resistance from the radiator to the cooling medium of the water cooling system corresponding to the adjusted flow rate is obtained by querying the thermal resistance curve. The heat-related losses of the corresponding flow-through elements are calculated after each adjustment, thereby calculating the loss function after each adjustment, and adjusting the flow rate until the loss function reaches the minimum.

[0034] It should be noted that if the final adjusted flow rate is the maximum flow rate, an alarm will be issued to remind the staff to check to prevent a sharp increase in junction temperature due to aging or damage of the flow-through element, external electromagnetic interference and other faults.

[0035] Preferably, the temperature sensor is a resistance temperature detector (RTD) or a thermocouple; when the flow element is a thyristor, the anode and cathode of the thyristor are both connected to the radiator of the water cooling system; the thyristor junction temperature is the average temperature measured at the anode and cathode of the thyristor; when the flow element is an IGBT, the collector and emitter of the IGBT are both connected to the radiator of the water cooling system; the IGBT junction temperature is the average temperature measured at the collector and emitter of the IGBT.

[0036] Preferably, the comprehensive junction temperature abnormality index The calculation formula is:

[0037] In the formula, is a coefficient with a value of 0-1. is the junction temperature change rate, , are the junction temperatures of the flow element measured at the last moment and this moment respectively, , They are the time of the previous moment and the time of this moment respectively.

[0038] Preferably, the value range of the index threshold of the corresponding flow element is:

[0039] In the formula, is the maximum junction temperature of the corresponding flow element.

[0040] Preferably, the maximum flow rate of the water cooling system is calculated according to the rated power of the water cooling system in combination with the along-the-line resistance and the local resistance of the water cooling system, specifically: The formula for calculating the sum of the maximum along-the-line resistance and the maximum local resistance based on the maximum flow rate and rated power of the water cooling system is:

[0041] In the formula, is the maximum resistance along the path, is the maximum local resistance, d is the inner diameter of the pipe, is the set maximum power factor, is the flow coefficient, is the density of the coolant in the water cooling system, is the acceleration due to gravity, is the rated power of the water cooling system, is the maximum flow rate; Specifically, the maximum power factor of this embodiment is 30%.

[0042] The formula for calculating the maximum along-the-way resistance and the maximum local resistance based on the maximum flow velocity is:

[0043]

[0044] In the formula, C h is the Haicheng William coefficient; is the local resistance coefficient; The two formulas for calculating the maximum along-the-path resistance and the maximum local resistance according to the maximum flow velocity are substituted into the sum of the maximum along-the-path resistance and the maximum local resistance calculated according to the maximum flow velocity and rated power of the water cooling system, and the maximum flow velocity of the water cooling system is obtained by iterative solution.

[0045] Preferably, the flow coefficient By simulating the water cooling system, the flow rate corresponding to the flow velocity is obtained, and the flow rate corresponding to the flow velocity is calculated using the flow coefficient, the relationship between the flow velocity and the flow rate, or it is set according to the pipeline design of the water cooling system and the additional components of the water cooling system, the pipeline design includes the selection of pipe diameters and the series and parallel connection of water channels; the additional components include pipeline elbows, valves, and joints; The relationship formula between flow coefficient, flow velocity and flow rate:

[0046] In the formula, For flow, is the flow rate.

[0047] Specifically, the flow coefficient obtained by simulating the water cooling system using three-dimensional software is is 1.881. Preferably, the establishment combines the heat-related losses of the flow element corresponding to the moment, the thermal resistance from the radiator to the cooling medium of the water cooling system, and the loss function of the inlet and outlet water temperatures, takes the maximum flow rate as a constraint, and dynamically adjusts the flow rate with the minimum loss function as the goal, specifically: Loss Function for:

[0048] In the formula, The corresponding heat loss of the flow element at this moment is: is the thermal resistance of the corresponding flow element, , are the inlet water temperature and outlet water temperature, is the rated junction temperature of the corresponding flow element.

[0049] It should be noted that during the heat exchange process, the heat of the thyristor and IGBT components is transferred from the junction to the tube shell, then from the tube shell to the radiator, and finally from the radiator surface to the cooling medium. At the same time, part of the heat is directly dissipated to the external environment through the tube shell. When the flow element is a thyristor, the anode and cathode of the thyristor are connected to the radiator of the water cooling system; when the flow element is an IGBT, the collector and emitter of the IGBT are connected to the radiator of the water cooling system; the equivalent thermal circuit diagrams of thyristors and IGBTs are shown in Figure 2 As shown, the thermal resistance of the flow element The calculation formula is:

[0050]

[0051] In the formula, is the equivalent thermal resistance from the anode of the thyristor or the collector of the IGBT to the heat sink connected to it, is the equivalent thermal resistance from the cathode of the thyristor or the emitter of the IGBT to the heat sink connected to it; When it is A, it means that the corresponding thermal resistance is the thermal resistance of the thermal path from the anode of the thyristor or the collector of the IGBT to the heat sink connected to it. When it is B, it means that the corresponding thermal resistance is the thermal resistance of the thermal path from the cathode of the thyristor or the emitter of the IGBT to the heat sink connected to it. for Corresponding to the proportional coefficient of heat dissipation from the shell and tube on the heat path directly to the external environment, for Corresponding to the junction-to-case thermal resistance from the die to the case on the thermal path, for The contact thermal resistance from the shell to the radiator of the water cooling system on the corresponding heat path, for The thermal resistance from the radiator to the cooling medium of the water cooling system corresponding to the current flow rate on the heat path; Since the radiator, pipes and other structural materials of the water cooling system used in this embodiment are always the same, , thermal resistance of the flow element The calculation formula is:

[0052] In the formula, is the proportional coefficient of heat dissipation from the tube shell directly to the external environment, is the junction-to-case thermal resistance from die to case, is the thermal contact resistance from the tube shell to the radiator of the water cooling system, The thermal resistance from the radiator to the cooling medium of the water cooling system corresponding to the flow rate at this moment; Specifically, The material of the pipe of the water cooling system is related to the is 0.01. The final loss function for:

[0053] Preferably, the heat-related losses of the flow-through element are specifically: If the flow element is a thyristor, the loss of the flow element is the sum of the conduction loss, turn-on loss and turn-off loss of the thyristor. If the flow element is an IGBT, the loss of the flow element is the conduction loss of the IGBT.

[0054] Preferably, the conduction loss of the IGBT The calculation formula is:

[0055] In the formula, is the on-state voltage of the IGBT, is the current through the IGBT, is the IGBT switching frequency; Conduction loss of thyristor , Turn-on loss and turn-off losses The calculation formulas are:

[0056]

[0057]

[0058] In the formula, is the conduction voltage drop of the thyristor, is the conduction current of the thyristor, is the duty cycle of the thyristor conduction; is the voltage of the thyristor during the turn-on process, is the current of the thyristor during the turn-on process, is the operating frequency of the thyristor, is the turn-on time of the thyristor, is the turn-off time of the thyristor.

[0059] Embodiment 2 of the present invention proposes a system for protecting a converter valve from abnormal junction temperature by adjusting the water cooling flow rate using the method described in Embodiment 1 of the present invention, comprising a measurement module, a comprehensive junction temperature abnormality index calculation module, a maximum flow rate calculation module, a loss function establishment module, and a flow rate adjustment module, and is characterized in that: Measuring module: used to measure the junction temperature of each flow element of the controllable phase-changing valve in real time using a temperature sensor, the flow element including a thyristor and an IGBT, and measure the inlet and outlet water temperatures of the water cooling system; Comprehensive junction temperature abnormality index calculation module: used to calculate the comprehensive junction temperature abnormality index of each flow element according to the junction temperature and the junction temperature change rate; if there is a flow element whose comprehensive junction temperature abnormality index is greater than or equal to the set corresponding flow element index threshold, then obtain the thermal resistance curve between the flow rate and the thermal resistance from the radiator to the cooling medium of the water cooling system through simulation; Maximum flow rate calculation module: Combines the resistance along the water cooling system and the local resistance, and calculates the maximum flow rate of the water cooling system according to the rated power of the water cooling system; Loss function establishment module: establishes a loss function combining the heat-related losses of the corresponding flow-through elements, the thermal resistance from the radiator to the cooling medium of the water cooling system, and the inlet and outlet water temperatures; Flow rate regulation module: With the maximum flow rate as the constraint, the flow rate is continuously adjusted. After each adjustment, the thermal resistance from the radiator to the cooling medium of the water cooling system corresponding to the adjusted flow rate is obtained by querying the thermal resistance curve. After each adjustment, the heat-related losses of the corresponding flow-through elements are calculated, thereby calculating the loss function after each adjustment and adjusting the flow rate until the loss function reaches the minimum.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements 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 method for protecting a converter valve from abnormal junction temperature by adjusting the water cooling flow rate, characterized in that: Includes the following: Real-time measurement of the junction temperature of each flow element of the converter valve and the inlet and outlet water temperatures of the water cooling system, wherein the flow elements include thyristors and IGBTs, and the comprehensive junction temperature abnormality index of each flow element is calculated according to the junction temperature and the junction temperature change rate; if the comprehensive junction temperature abnormality index of a flow element exceeds the set index threshold of the corresponding flow element, the thermal resistance curve between the flow rate and the thermal resistance from the radiator to the cooling medium of the water cooling system is obtained through simulation; the maximum flow rate is calculated according to the rated power of the water cooling system in combination with the along-the-line resistance and local resistance of the water cooling system; A loss function is established that combines the heat-related losses of the corresponding flow elements, the thermal resistance from the radiator to the cooling medium of the water-cooling system, and the inlet and outlet water temperatures; with the maximum flow rate as the constraint, the flow rate is continuously adjusted, and after each adjustment, the thermal resistance from the radiator to the cooling medium of the water-cooling system corresponding to the adjusted flow rate is obtained by querying the thermal resistance curve, and the heat-related losses of the corresponding flow elements after each adjustment are calculated, thereby calculating the loss function after each adjustment, and adjusting the flow rate until the loss function is minimized.

2. The method for protecting a converter valve from abnormal junction temperature by adjusting the water cooling flow rate according to claim 1, characterized in that: A temperature sensor is used to measure the junction temperature of each flow-passing element of the converter valve. The temperature sensor is a resistance temperature detector (RTD) or a thermocouple. When the flow-passing element is a thyristor, both the anode and cathode of the thyristor are connected to the radiator of the water cooling system. The thyristor junction temperature is the average temperature measured at both ends of the anode and cathode of the thyristor. When the flow-passing element is an IGBT, both the collector and emitter of the IGBT are connected to the radiator of the water cooling system. The IGBT junction temperature is the average temperature measured at both ends of the collector and emitter of the IGBT.

3. The method for protecting a converter valve against abnormal junction temperature by adjusting the water cooling flow rate according to claim 1, characterized in that: The comprehensive junction temperature abnormality index The calculation formula is: In the formula, is a coefficient with a value between 0 and 1. is the junction temperature change rate, , are the junction temperatures of the flow element measured at the last moment and this moment respectively, , They are the time of the previous moment and the current moment respectively.

4. The method for protecting a converter valve against abnormal junction temperature according to water cooling flow rate regulation according to claim 3, characterized in that: The value range of the index threshold of the corresponding flow element is: In the formula, is the maximum junction temperature of the corresponding flow element.

5. The method for protecting a converter valve against abnormal junction temperature according to water cooling flow rate regulation according to claim 1, characterized in that: The maximum flow rate is calculated based on the rated power of the water cooling system in combination with the water cooling system's along-the-line resistance and local resistance, specifically: The formula for calculating the sum of the maximum along-the-line resistance and the maximum local resistance based on the maximum flow rate and rated power of the water cooling system is: In the formula, is the maximum resistance along the path, is the maximum local resistance, d is the inner diameter of the pipe, is the set maximum power factor, is the flow coefficient, is the density of the coolant in the water cooling system, is the acceleration due to gravity, is the rated power of the water cooling system, is the maximum flow rate; The formula for calculating the maximum along-the-way resistance and the maximum local resistance based on the maximum flow velocity is: In the formula, C h is the Haicheng William coefficient; is the local resistance coefficient; The two formulas for calculating the maximum along-the-path resistance and the maximum local resistance according to the maximum flow velocity are substituted into the sum of the maximum along-the-path resistance and the maximum local resistance calculated according to the maximum flow velocity and rated power of the water cooling system, and the maximum flow velocity of the water cooling system is obtained by iterative solution.

6. The method for protecting a converter valve from abnormal junction temperature by adjusting the water cooling flow rate according to claim 5, characterized in that: Flow coefficient By simulating the water cooling system, the flow rate corresponding to the flow velocity is obtained, and the flow rate corresponding to the flow velocity is calculated using the flow coefficient, the relationship between the flow velocity and the flow rate, or it is set according to the pipeline design of the water cooling system and the additional components of the water cooling system, the pipeline design includes the selection of pipe diameters and the series and parallel connection of water channels; the additional components include pipeline elbows, valves, and joints; The relationship formula between flow coefficient, flow velocity and flow rate: In the formula, For flow, is the flow rate.

7. The method for protecting a converter valve against abnormal junction temperature by adjusting the water cooling flow rate according to claim 6, characterized in that: The establishment combines the heat-related losses of the flow element corresponding to the moment, the thermal resistance from the radiator to the cooling medium of the water cooling system, and the inlet and outlet water temperatures, takes the maximum flow rate as a constraint, and dynamically adjusts the flow rate with the minimum loss function as the goal, specifically: Loss Function for: In the formula, The corresponding heat loss of the flow element at this moment is: is the junction-to-case thermal resistance from die to case, is the thermal contact resistance from the tube shell to the radiator of the water cooling system, The thermal resistance from the radiator to the cooling medium of the water cooling system corresponding to the flow rate at this moment is: is the proportional coefficient of heat dissipation from the tube shell directly to the external environment, , are the inlet water temperature and outlet water temperature, is the rated junction temperature of the corresponding flow element.

8. The method for protecting a converter valve against abnormal junction temperature according to water cooling flow rate regulation according to claim 7, characterized in that: The heat-related losses of the flow-through element are specifically: If the flow element is a thyristor, the loss of the flow element is the sum of the conduction loss, turn-on loss and turn-off loss of the thyristor. If the flow element is an IGBT, the loss of the flow element is the conduction loss of the IGBT.

9. The method for protecting a converter valve against abnormal junction temperature by adjusting the water cooling flow rate according to claim 8, characterized in that: IGBT conduction loss The calculation formula is: In the formula, is the on-state voltage of the IGBT, is the current through the IGBT, is the IGBT switching frequency; Conduction loss of thyristor , Turn-on loss and turn-off losses The calculation formulas are: In the formula, is the conduction voltage drop of the thyristor, is the conduction current of the thyristor, is the duty cycle of the thyristor conduction; is the voltage of the thyristor during the turn-on process, is the current of the thyristor during the turn-on process, is the operating frequency of the thyristor, is the turn-on time of the thyristor, is the turn-off time of the thyristor.

10. A system for protecting a converter valve against abnormal junction temperature by adjusting the water cooling flow rate using the method according to any one of claims 1 to 9, comprising a measurement module, a comprehensive junction temperature abnormality index calculation module, a maximum flow rate calculation module, a loss function establishment module, and a flow rate adjustment module, characterized in that: Measuring module: used to measure the junction temperature of each flow element of the controllable phase-changing valve in real time using a temperature sensor, the flow element including a thyristor and an IGBT, and measure the inlet and outlet water temperatures of the water cooling system; Comprehensive junction temperature abnormality index calculation module: used to calculate the comprehensive junction temperature abnormality index of each flow element according to the junction temperature and the junction temperature change rate; if there is a flow element whose comprehensive junction temperature abnormality index is greater than or equal to the set corresponding flow element index threshold, then obtain the thermal resistance curve between the flow rate and the thermal resistance from the radiator to the cooling medium of the water cooling system through simulation; Maximum flow rate calculation module: Combines the resistance along the water cooling system and the local resistance, and calculates the maximum flow rate of the water cooling system according to the rated power of the water cooling system; Loss function establishment module: establishes a loss function combining the heat-related losses of the corresponding flow-through elements, the thermal resistance from the radiator to the cooling medium of the water cooling system, and the inlet and outlet water temperatures; Flow rate regulation module: With the maximum flow rate as the constraint, the flow rate is continuously adjusted. After each adjustment, the thermal resistance from the radiator to the cooling medium of the water cooling system corresponding to the adjusted flow rate is obtained by querying the thermal resistance curve. After each adjustment, the heat-related losses of the corresponding flow-through elements are calculated, thereby calculating the loss function after each adjustment and adjusting the flow rate until the loss function reaches the minimum.

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