Closed cooling system of mining frequency converter and cooling method thereof

Abstract

The invention relates to the technical field of equipment cooling, and provides a closed cooling system of a mining frequency converter and a cooling method thereof, a heat dissipation device is arranged in a closed circulation loop and is used for cooling a cooling liquid flowing through the closed circulation loop; the booster pump assembly is arranged in the closed circulation loop and comprises a main booster pump and a standby booster pump which are arranged in parallel; the temperature sensor is used for monitoring the temperature of cooling liquid in the closed circulation loop; the pressure sensor is used for monitoring fluid pressure in the closed circulation loop; the control unit is electrically connected with the temperature sensor, the pressure sensor, the main booster pump and the standby booster pump, and the control unit is configured to adjust the operation frequency of the main booster pump in real time according to the temperature monitored by the temperature sensor so as to change the flow of the cooling liquid in the closed circulation loop; and when the pressure sensor monitors that the pressure in the closed circulation loop is lower than a preset fault threshold value, the main booster pump is stopped, and the standby booster pump is started.

Description

Closed-loop cooling system and cooling method for mining frequency converters Technical Field

[0001] This invention relates to the field of equipment cooling technology, and in particular to a closed-loop cooling system and cooling method for a mining frequency converter. Background Technology

[0002] High-power frequency converters are core drive components for heavy equipment such as hoisting and transportation in mines. During operation, the internal power semiconductor devices, such as IGBTs, generate a large amount of heat. If this heat cannot be dissipated in a timely and effective manner, it will directly lead to excessively high operating temperatures of the frequency converter, resulting in derating operation or even shutdown failure, seriously affecting the safety and continuity of mine production and causing huge economic losses. Summary of the Invention

[0003] This invention provides a closed-loop cooling system and cooling method for mining frequency converters, addressing the aforementioned technical deficiencies in existing technologies. It not only achieves energy savings but also helps extend the service life of the internal power devices of the frequency converter. Furthermore, the operation, adjustment, and fault handling of the entire closed-loop cooling system are fully automated by the control unit, requiring no manual intervention and reducing maintenance costs.

[0004] A first aspect of the present invention provides a closed-loop cooling system for a mining frequency converter, comprising: a closed-loop circulation loop, consisting of multiple heat dissipation components of the frequency converter body connected in parallel via pipes; a heat dissipation device disposed in the closed-loop circulation loop for cooling the coolant flowing through the closed-loop circulation loop; a booster pump assembly disposed in the closed-loop circulation loop for driving the coolant to circulate; the booster pump assembly includes a main booster pump and a standby booster pump connected in parallel; a temperature sensor for monitoring the temperature of the coolant in the closed-loop circulation loop; a pressure sensor for monitoring the fluid pressure in the closed-loop circulation loop; and a control unit electrically connected to the temperature sensor, the pressure sensor, the main booster pump, and the standby booster pump, respectively, wherein the control unit is configured to: adjust the operating frequency of the main booster pump in real time according to the temperature monitored by the temperature sensor to change the flow rate of the coolant in the closed-loop circulation loop; and stop the main booster pump and start the standby booster pump when the pressure in the closed-loop circulation loop is detected by the pressure sensor as being lower than a preset fault threshold.

[0005] According to the closed-loop cooling system of the mining frequency converter provided by the present invention, a first control valve is provided on both the upstream and downstream pipelines of the main booster pump, and the first control valve is electrically connected to the control unit; a second control valve is provided on both the upstream and downstream pipelines of the standby booster pump, and the second control valve is electrically connected to the control unit.

[0006] In the closed-loop cooling system of the mining frequency converter provided by the present invention, the main booster pump is a frequency converter booster pump.

[0007] According to the closed-loop cooling system of the mining frequency converter provided by the present invention, each heat dissipation component of the frequency converter body is provided with a filter and a one-way valve on its parallel branch.

[0008] According to the closed-loop cooling system for a mining frequency converter provided by the present invention, the heat dissipation device includes: a radiator body connected between the frequency converter body located at the end and the booster pump assembly; and a fan disposed on one side of the radiator body, the fan being driven by an explosion-proof motor.

[0009] The closed-loop cooling system for a mining frequency converter provided by the present invention further includes: a liquid collection tank, which is located between the downstream of the heat dissipation device and the upstream of the booster pump assembly, for storing antifreeze coolant.

[0010] The closed-loop cooling system for a mining frequency converter provided by the present invention further includes: a wireless transmission module, which is electrically connected to the control unit and is used to wirelessly transmit an alarm signal to the central control room when a system failure occurs.

[0011] A second aspect of the present invention provides a cooling method for a closed-loop cooling system based on any one of the above-described mining frequency converters, comprising the following steps: real-time monitoring of temperature parameters of the heat load of the frequency converter body and real-time monitoring of pressure parameters of the closed-loop circulation loop; real-time adjustment of the operating frequency of the main booster pump based on the temperature monitored by the temperature sensor to change the flow rate of coolant in the closed-loop circulation loop; and when the pressure in the closed-loop circulation loop is detected by the pressure sensor to be lower than a preset fault threshold, controlling the main booster pump to stop working and starting the standby booster pump to take over the circulation operation from the main booster pump.

[0012] According to the cooling method of the closed-loop cooling system of the mining frequency converter provided by the present invention, the step of adjusting the operating frequency of the main booster pump in real time based on the temperature monitored by the temperature sensor includes: comparing the real-time coolant temperature monitored by the temperature sensor with a preset target temperature to obtain a temperature deviation value; calculating a proportional adjustment component based on the temperature deviation value; calculating an integral adjustment component based on the historical accumulation of the temperature deviation value to eliminate steady-state error; calculating a derivative adjustment component based on the rate of change of the temperature deviation value to suppress temperature fluctuations and overshoot; and superimposing the proportional adjustment component, integral adjustment component, and derivative adjustment component to generate a final control signal to adjust the operating frequency of the main booster pump in real time.

[0013] According to the cooling method of the closed-loop cooling system for a mining frequency converter provided by the present invention, the cooling method further includes: when the temperature parameter is detected to exceed a preset start-up temperature threshold, starting the main booster pump to begin cyclic operation; when the temperature parameter is detected to be lower than the start-up temperature threshold, controlling the main booster pump to be in standby or stop state; and simultaneously starting the standby booster pump, generating a fault alarm signal and sending the alarm signal to the remote control room via a wireless transmission module.

[0014] The closed-loop cooling system for mining frequency converters provided by this invention controls a main booster pump and a standby booster pump connected in parallel through a control unit. The control unit adjusts the operating frequency of the main booster pump in real time based on the temperature monitored by the temperature sensor, thereby changing the flow rate of coolant in the closed-loop circulation loop. When the pressure in the closed-loop circulation loop is detected by the pressure sensor to be lower than a preset fault threshold, the main booster pump is stopped and the standby booster pump is started. This solves the risk of a single point of failure causing the entire system to fail and ensures the continuity of mine production.

[0015] Furthermore, by employing variable frequency control for the main booster pump, the cooling output of the closed-loop cooling system can be matched in real time with changes in the heat load of the inverter itself. This not only achieves energy savings but also helps extend the lifespan of the power components inside the inverter. Simultaneously, the operation, adjustment, and fault handling of the entire closed-loop cooling system are fully automated by the control unit, requiring no manual intervention, reducing maintenance costs, and enabling remote monitoring and unattended operation, aligning with the modern trend of intelligent mining.

[0016] The cooling method for a closed-loop cooling system of a mining frequency converter provided by this invention elevates a traditional fluid transport process into a closed-loop cooling system capable of monitoring, regulating, and repairing, and simultaneously issuing alarm information. This can synergistically resolve the conflicting demands for energy saving, high efficiency, and high reliability. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 is a system diagram of the closed cooling system of the mining frequency converter provided by the present invention.

[0019] Figure 2 is a schematic flowchart of the cooling method of the closed cooling system for the mining frequency converter provided by the present invention.

[0020] Figure 3 is a circuit diagram of the closed cooling system of the mining frequency converter provided by the present invention.

[0021] Reference numerals: 10, inverter body; 20, heat dissipation device; 30, booster pump assembly; 31, main booster pump; 32, standby booster pump; 33, first control valve; 34, second control valve; 40, check valve; 50, liquid collection tank. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0023] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0024] In the embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0025] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0026] Referring to Figure 1, this embodiment of the invention provides a closed-loop cooling system for a mining frequency converter, which constructs a closed-loop circulation system. The main body of this closed-loop circulation system consists of multiple frequency converter bodies 10 connected in parallel, each with its own heat dissipation components (e.g., liquid cooling plates or heat dissipation modules). This ensures that each frequency converter body 10 receives an independent coolant supply. The closed-loop circulation system is filled with coolant, typically antifreeze coolant, to adapt to the complex temperature environment of a mine. For example, using a -35°C coolant can solve the problem of freezing damage to water-cooled equipment under low-temperature conditions.

[0027] A heat dissipation device 20 is installed in the closed-loop circulation system. The heat dissipation device 20 is usually located after all the heat dissipation components of the inverter body and is used to cool the coolant that has absorbed heat from the inverter body in the closed-loop circulation system. The heat dissipation device 20 can be an air-cooled radiator (driven by an explosion-proof fan) or a water-cooled heat exchanger.

[0028] A booster pump assembly 30 is provided in the closed-loop circulation system to drive the coolant circulation. The booster pump assembly 30 includes a main booster pump 31 and a standby booster pump 32 connected in parallel. Each booster pump has a valve controlled by a control unit on its inlet and outlet pipes.

[0029] Temperature sensors are installed at key locations in the closed-loop circulation system (e.g., the main outlet pipe or the main return pipe) to monitor the temperature of the coolant in real time, which directly reflects the overall thermal load status of the frequency converter.

[0030] Similarly, pressure sensors are installed at key locations in the closed-loop circulation system (e.g., the outlet manifold of the main booster pump 31) to monitor the fluid pressure in the closed-loop circulation system in real time. This pressure is a key indicator for determining whether the main booster pump 31 is operating normally and whether there is any leakage in the pipeline.

[0031] The control unit (e.g., PLC, microcontroller, or dedicated controller) is electrically connected to the temperature sensor, pressure sensor, main booster pump 31, and standby booster pump 32, respectively. The control unit is configured to: adjust the operating frequency of the main booster pump 31 in real time according to the temperature monitored by the temperature sensor to change the flow rate of coolant in the closed loop; and stop the main booster pump 31 and start the standby booster pump 32 when the pressure in the closed loop is detected by the pressure sensor as being lower than a preset fault threshold.

[0032] Based on the above structural description, the working process of this invention can be divided into two core modes, corresponding to normal operation and fault response respectively: Mode 1: Frequency conversion energy saving and precise temperature control process under normal operation After the closed cooling system of the mining frequency converter is started, the control unit starts the main booster pump 31. At this time, the standby booster pump 32 is in standby mode.

[0033] When the inverter starts working, it generates heat. The coolant in the closed-loop circulation circuit flows through the heat dissipation components of the inverter body, absorbs heat, and its temperature rises.

[0034] When the temperature sensor detects the coolant temperature, it sends the real-time temperature signal to the control unit. The control unit internally runs a control algorithm (such as a PID control algorithm). It compares the real-time temperature with a preset target temperature (e.g., the upper limit of the optimal operating temperature for the IGBT module).

[0035] If the real-time temperature is higher than the target temperature, it indicates insufficient heat dissipation. The control unit will increase the operating frequency of the main booster pump 31, thereby increasing the speed of the main booster pump 31 and increasing the coolant flow rate, which will remove more heat and lower the temperature.

[0036] If the real-time temperature is lower than the target temperature, it indicates excessive heat dissipation or low load. The control unit will reduce the operating frequency of the main booster pump 31, slowing down the speed of the main booster pump 31 and reducing the flow rate, thereby saving the power consumption of the water pump and allowing the temperature to rise back to the target range.

[0037] Through this closed-loop negative feedback regulation, the closed cooling system of the mining frequency converter can dynamically maintain the operating temperature of the frequency converter within a stable range, while achieving on-demand cooling and maximizing energy savings.

[0038] Mode 2: Automatic Redundancy Switching Process in Fault Conditions During the operation of the closed-loop cooling system of the mining frequency converter, the control unit continuously monitors the fluid pressure of the closed-loop circulation loop through a pressure sensor.

[0039] When the main booster pump 31 suddenly fails (such as the motor burns out or the pump body jams) or a serious leak occurs in the closed-loop circulation circuit, the pressure in the closed-loop circulation circuit will drop rapidly.

[0040] When the pressure value detected by the pressure sensor falls below a preset fault threshold (this threshold is far below the lower limit of normal operating pressure, used to distinguish between normal fluctuations and actual faults), the control unit immediately determines that a serious system fault has occurred. The control unit will immediately execute the automatic emergency plan: Step 1: Immediately cut off the power supply to the main booster pump 31, causing the main booster pump 31 to stop working. Step 2: At the same time, immediately send a start command to the standby booster pump 32, causing the standby booster pump 32 to start and take over the work of the main booster pump 31.

[0041] Because the main booster pump 31 and the standby booster pump 32 are connected in parallel, the standby booster pump 32 can quickly restore the pressure and flow of the closed-loop circulation after starting, ensuring uninterrupted coolant circulation. The entire switching process is fully automatic with an extremely short response time (usually on the order of seconds), ensuring that the inverter body continues to receive stable cooling in emergency situations and avoiding shutdowns due to cooling interruptions.

[0042] While performing the switchover, the control unit will also issue an alarm signal (for example, via audible and visual alarm or wireless transmission to the central control room) to notify maintenance personnel that the main booster pump 31 has malfunctioned and needs to be repaired in a timely manner.

[0043] The closed-loop cooling system for mining frequency converters provided in this invention organically combines frequency conversion speed regulation technology with redundant backup design under an intelligent control unit, thereby synergistically solving two core problems in the field of industrial cooling: operational economy and extreme reliability.

[0044] It is understood that the closed-loop cooling system of the mining frequency converter provided by the present invention controls the main booster pump 31 and the standby booster pump 32, which are set up in parallel, through the control unit. The control unit adjusts the operating frequency of the main booster pump 31 in real time according to the temperature monitored by the temperature sensor, so as to change the flow rate of coolant in the closed loop. When the pressure in the closed loop is detected by the pressure sensor to be lower than the preset fault threshold, the main booster pump 31 is stopped and the standby booster pump 32 is started, thereby solving the risk of the entire system being paralyzed due to a single point of failure and ensuring the continuity of mine production.

[0045] Furthermore, by adopting a variable frequency booster pump for the main booster pump 31, the cooling output of the closed-loop cooling system can match the heat load changes of the inverter body in real time. This not only achieves energy saving but also helps extend the service life of the power devices inside the inverter. Simultaneously, the operation, adjustment, and fault handling of the entire closed-loop cooling system are fully automated by the control unit, requiring no manual intervention, reducing maintenance costs, and enabling remote monitoring and unattended operation, aligning with the development trend of modern intelligent mining.

[0046] Referring to Figure 1, the upstream and downstream pipelines of the main booster pump 31 are equipped with a first control valve 33, which is electrically connected to the control unit; the upstream and downstream pipelines of the standby booster pump 32 are equipped with a second control valve 34, which is electrically connected to the control unit.

[0047] Essentially, independent control valve assemblies are installed on the pipelines of the main booster pump 31 and the standby booster pump 32, which are connected in parallel. Specifically, a first control valve 33 is installed on both the inlet (upstream) and outlet (downstream) pipelines of the main booster pump 31. This means that the main booster pump 31 can be independently isolated from the closed-loop circulation by its two upstream and downstream control valves. Similarly, a second control valve 34 is installed on both the inlet (upstream) and outlet (downstream) pipelines of the standby booster pump 32. The standby booster pump 32 thus has the ability to be completely isolated.

[0048] In this context, the first control valve 33 and the second control valve 34 are generally understood to be valves that can be remotely switched via electrical signals, such as solenoid valves, electric ball valves, or electric butterfly valves. The actuators of both the first control valve 33 and the second control valve 34 are electrically connected to a control unit (such as a PLC). This allows the control unit to automatically control the opening and closing states of each control valve according to preset program logic, thereby achieving programmed management of the entire fluid path.

[0049] The working process of this invention embodiment is as follows: Normal operation mode: When the system is initialized or running normally, the control unit issues an instruction to open the two first control valves 33 (main booster pump 31) and at the same time ensure that the two second control valves 34 (standby booster pump 32) are in the closed state.

[0050] After confirming the valve status, the control unit starts the main booster pump 31. At this time, the flow path of the coolant is clear: it flows through the opened first control valve 33 into the main booster pump 31, and is pumped out from the main booster pump 31 through the other opened first control valve 33 into the closed circulation loop.

[0051] Since both second control valves 34 of the standby booster pump 32 are closed, the standby booster pump 32 is completely bypassed and isolated, and coolant will not flow through the standby booster pump 32.

[0052] Automatic fault switching mode: When the pressure sensor detects that the pressure is below the fault threshold, the control unit determines that the main booster pump 31 is faulty. The control unit immediately stops the main booster pump 31, closes both first control valves 33, and completely isolates the faulty main booster pump 31 from the closed circulation loop. The control unit opens both second control valves 34 to establish a circulation path for the standby booster pump 32. After confirming that the second control valves 34 are open, the standby booster pump 32 is started. The coolant begins to circulate through the standby booster pump 32, and the system returns to normal operation. The entire process is completed automatically without manual intervention.

[0053] When the main booster pump 31 fails and is taken over by the standby booster pump 32, maintenance personnel can perform online maintenance. Since the faulty main booster pump 31 is doubly isolated by the two closed first control valves 33 before and after it, maintenance personnel can safely disassemble and repair the main booster pump 31 without affecting the operating cooling system or posing a risk of coolant leakage.

[0054] Furthermore, to achieve dynamic adjustment of coolant flow rate, the main booster pump 31 is designated as the main booster pump. The main booster pump integrates or is equipped with an external frequency converter. The control unit outputs a frequency control signal (such as a 4-20mA analog signal or via bus communication) instead of a simple switching signal. By changing the power supply frequency to the water pump motor, the control unit steplessly adjusts the motor speed, thereby precisely controlling the pump's output flow rate and head.

[0055] Compared to methods like valve throttling, variable frequency drive (VFD) can control flow more precisely and respond more quickly, resulting in higher accuracy and stability of closed-loop temperature control. According to fluid dynamics principles, the shaft power of a water pump is proportional to the cube of its rotational speed. When the inverter load decreases and the required cooling capacity is reduced, the system reduces the flow rate by decreasing the pump speed, resulting in a cubic decrease in energy consumption. Compared to fixed-speed pumps combined with valve throttling, this significantly improves energy efficiency.

[0056] Referring again to Figure 1, in some embodiments of the present invention, each inverter body 10 has a filter and a one-way valve 40 provided on the parallel branch of the heat dissipation component.

[0057] The filter is installed on the pipe before the coolant enters each inverter's heat dissipation component. It contains a filter screen to intercept any impurities in the coolant, such as metal shavings, scale, and fragments of sealing material. A one-way valve 40 is installed on the branch pipe, allowing coolant to flow only towards the inverter's heat dissipation components and preventing backflow in any direction.

[0058] Because the internal flow channels of the liquid-cooled heat dissipation components (liquid cooling plates) of the inverter body are usually quite narrow, they are easily clogged by tiny impurities, leading to localized hot spots, which can burn out the power module in severe cases. By installing filters to prevent the risk of clogging, the long-term stability of the heat dissipation efficiency of each inverter body is ensured. The one-way valve 40 prevents liquid backflow during pump start-up and shutdown or pressure fluctuations in different branches.

[0059] Referring again to Figure 1, in some embodiments of the present invention, the heat dissipation device 20 includes a heat sink body and a fan. The heat sink body is connected between the inverter body 10 located at the end and the booster pump assembly 30. The fan is located on one side of the heat sink body and is driven by an explosion-proof motor.

[0060] High-temperature coolant flows inside the radiator body (usually a coil with multiple layers of heat dissipation fins), transferring heat to the fins. The fan rotates at high speed, generating a strong airflow that forces the airflow across the radiator fins, carrying the heat away into the surrounding environment through convection heat transfer, thereby cooling the coolant.

[0061] Because the underground environment of coal mines often contains explosive mixtures such as methane and coal dust, all electrical equipment must meet strict explosion-proof standards. The motor driving the fan is an explosion-proof motor, with an explosion-proof enclosure installed on its exterior. This ensures that any electrical sparks, arcs, or dangerously high temperatures generated inside the motor during operation will not ignite the external explosive gas environment, thus avoiding the risk of an explosion caused by the operation of the fan motor in the closed cooling system and improving system safety.

[0062] Referring again to Figure 1, in some embodiments of the present invention, the closed cooling system further includes a liquid collection tank 50, which is located between the downstream of the heat dissipation device 20 and the upstream of the booster pump assembly 30, for storing antifreeze coolant.

[0063] The collection tank 50 can be a container equipped with a level gauge, a replenishment port, and a vent valve. As a coolant storage tank for the system, the collection tank 50 facilitates daily inspection and replenishment of coolant lost due to minor leaks. Simultaneously, the collection tank 50 provides a buffer volume to absorb pressure and flow fluctuations in the system piping network.

[0064] Because air inevitably mixes into or is released from the coolant during circulation, the presence of gas reduces heat exchange efficiency and may lead to pump cavitation. The low flow velocity within the sump 50 makes it an ideal location for gas-liquid separation; gas accumulates here and can be discharged through the top vent valve. Placing the sump 50 upstream of the booster pump assembly 30 ensures that the suction inlet of the booster pump assembly 30 is always submerged in liquid, maintaining a stable positive pressure. This effectively prevents cavitation damage to the booster pump assembly 30 due to suction problems, ensuring stable operation of the power core.

[0065] In some embodiments of the present invention, the closed cooling system further includes a wireless transmission module, which is electrically connected to the control unit and is used to wirelessly transmit an alarm signal to the central control room when a system failure occurs.

[0066] The wireless transmission module (such as LoRa, ZigBee, 4G / 5G DTU, etc.) serves as a data interface, receiving commands and data from the control unit. When the control unit determines that a system fault has occurred (e.g., the main booster pump 31 has failed and switched to the backup pump, the coolant temperature is too high, the pressure is abnormal, etc.), the wireless transmission module will encode the preset alarm signal and send it wirelessly through the module.

[0067] Through wireless transmission, system status and alarm information can be sent in real time to the central control room on the surface or underground. Maintenance personnel can monitor the cooling system's operating status without being physically present on-site, improving maintenance efficiency and response speed. In the event of a fault, the control room can accurately issue alarm information and immediately dispatch maintenance personnel with the correct tools and spare parts to handle the situation, shortening fault response and repair time and further ensuring production continuity.

[0068] Referring to Figures 2 and 3, a second aspect of the present invention provides a cooling method based on a closed-loop cooling system for any of the aforementioned mining frequency converters. This method is a cooling method compatible with any of the aforementioned closed-loop cooling systems for mining frequency converters. The method aims to automatically achieve efficient cooling, energy-saving operation, and reliable response to fault conditions of the frequency converter through preset control logic steps. The method includes the following steps: Step S100: Real-time monitoring of the temperature parameters of the frequency converter body's heat load and real-time monitoring of the pressure parameters of the closed-loop circulation circuit.

[0069] Understandably, this step involves continuous monitoring and judgment. The control unit continuously monitors the coolant temperature in the closed-loop circulation loop through a temperature sensor, and monitors the pressure parameters of the closed-loop circulation loop in real time through a pressure sensor.

[0070] Step S200: Based on the temperature monitored by the temperature sensor, adjust the operating frequency of the main booster pump 31 in real time to change the flow rate of coolant in the closed loop; and when the pressure in the closed loop is detected by the pressure sensor to be lower than the preset fault threshold, control the main booster pump 31 to stop working and start the standby booster pump 32 to take over the circulation operation of the main booster pump 31.

[0071] Understandably, this step involves startup conditions, startup execution, and standby / stop conditions.

[0072] Start-up conditions: When the inverter starts working or the load increases, causing the coolant temperature to rise and exceed a preset start-up temperature threshold (e.g., 40°C), the control unit determines that the system needs to enter active cooling mode.

[0073] Start-up execution: The control unit sends a start command to the main booster pump 31 to start driving the coolant to circulate in a closed loop.

[0074] Standby / Stop Conditions: When the inverter body stops working or is under extremely low load, the coolant temperature drops naturally after heat dissipation and falls below the start-up temperature threshold (or another slightly lower stop threshold to prevent frequent start-stop). The control unit determines that active cooling is no longer needed and then controls the main booster pump 31 to stop running or enter standby mode.

[0075] This step enables basic energy management of the closed-loop cooling system, avoiding the ineffective operation of the booster pump when the inverter is under low load or shut down, directly reducing the system's standby power consumption and achieving the first level of energy saving.

[0076] Further, in step S200: based on the temperature monitored by the temperature sensor, the operating frequency of the main booster pump 31 is adjusted in real time, specifically including the following steps: Step S210: compare the real-time coolant temperature monitored by the temperature sensor with the preset target temperature to obtain the temperature deviation value.

[0077] Understandably, this embodiment illustrates that once the system is started, the control objective shifts to precise temperature regulation. First, a target is set and the deviation is acquired: the control unit presets a target temperature, for example, 55°C, which is most beneficial to the performance and lifespan of the Insulated Gate Bipolar Transistor (IGBT). The control unit compares the coolant temperature detected in real-time by the temperature sensor with this target temperature and calculates the temperature deviation value (Error): Temperature Deviation Value = Real-time Temperature - Target Temperature.

[0078] Step S220: Calculate the proportional (P) control component based on the temperature deviation value; calculate the integral (I) control component based on the historical accumulation of the temperature deviation value to eliminate steady-state error; calculate the derivative (D) control component based on the rate of change of the temperature deviation value to suppress temperature fluctuations and overshoot.

[0079] Understandably, in this step, the control unit executes a complex PID control algorithm based on the temperature deviation value, calculating three adjustment components in parallel: proportional (P) control: this component is proportional to the current temperature deviation value. Its function is to provide a rapid adjustment response. The larger the deviation, the greater the adjustment force (i.e., the pump frequency increment).

[0080] Integral (I) regulation: This component is the accumulation of all past temperature deviations over time. Its core function is to eliminate steady-state errors. Even if the temperature still has a slight difference from the target value after P regulation, this accumulation term will continue to exert its effect until the difference is completely eliminated, ensuring the temperature control accuracy during long-term operation.

[0081] Differential (D) regulation: This component is proportional to the rate of change of the temperature deviation. Its function is to predict and suppress; if the temperature rises too quickly, it will intervene in advance to slow down the regulation, thereby effectively suppressing temperature overshoot and oscillations, making the temperature curve smoother and the system more stable.

[0082] Step S230: The proportional control component, integral control component and derivative control component are superimposed to generate the final control signal to adjust the operating frequency of the main booster pump in real time.

[0083] Understandably, this step generates and executes a control signal. The control unit superimposes the three adjustment components (P, I, and D) to generate a final control signal. This signal is sent to the frequency converter of the main booster pump 31, adjusting the operating frequency of the main booster pump 31 in real time. Thus, the coolant flow rate is dynamically and smoothly changed, ultimately achieving precise and stable control of the coolant temperature.

[0084] Compared to simple on / off or proportional control, PID control offers higher temperature control accuracy, faster response speed, and stronger system stability. It ensures that the core components of the frequency converter always operate within their optimal temperature range, extending equipment lifespan and guaranteeing maximum output performance.

[0085] In some embodiments of the present invention, the cooling method of the closed cooling system of the mining frequency converter further includes: when the temperature parameter is detected to exceed the preset start-up temperature threshold, the main booster pump 31 is started to perform a cyclic operation; for example, when the temperature of the frequency converter is detected to exceed 33°C, the main booster pump 31 is started to run.

[0086] When the temperature parameter is detected to be lower than the start-up temperature threshold, the main booster pump 31 is controlled to be in standby or stopped state.

[0087] While starting the backup booster pump 32, a fault alarm signal is generated and sent to the remote control room via a wireless transmission module.

[0088] Understandably, this is a safety assurance process that operates in parallel with the aforementioned temperature control.

[0089] First, continuous pressure monitoring: the control unit constantly monitors the fluid pressure in the closed-loop circuit through pressure sensors.

[0090] During normal operation, the pressure remains within a stable range. The control unit has a preset fault pressure threshold, which is lower than the normal operating pressure. When the main booster pump 31 malfunctions (e.g., jammed or damaged) or a large-scale leak occurs in the pipeline, the circuit pressure will drop sharply. Once the detected pressure falls below this fault threshold, the control unit immediately determines that a serious fault has occurred.

[0091] The control unit immediately and automatically executes the following series of linked operations: Action 1: Immediately stop the operation of the main booster pump 31.

[0092] Action 2: Almost simultaneously, the backup booster pump 32 is activated to take over the operation of the main booster pump 31, quickly restoring the pressure and flow rate of the circuit.

[0093] While the backup booster pump 32 is started, the control unit generates a fault alarm signal and transmits the signal to the remote central control room in the form of radio waves via the wireless transmission module.

[0094] It is understood that the embodiments of the present invention can automatically switch between the main booster pump 31 and the standby booster pump 32, ensuring uninterrupted cooling function, thereby guaranteeing the continuous operation of the frequency converter and downstream production equipment and avoiding downtime accidents. Fault information is transmitted to the monitoring center in a timely and accurate manner, enabling maintenance personnel to know the occurrence and type of fault immediately. This can shorten fault response time, avoid the need for blind inspections by personnel in dangerous and complex underground environments, and improve personnel safety and maintenance efficiency.

[0095] The cooling method of the closed-loop cooling system for mining frequency converters provided by this invention deeply integrates process control theory (PID), redundancy backup theory, and remote communication technology under computer control and applies them to the field of mining equipment cooling. It elevates a traditional fluid transport process into a closed-loop cooling system capable of monitoring, regulating, and repairing, and simultaneously issuing alarm information. This approach can synergistically resolve the conflicting demands for energy saving, high efficiency, and high reliability.

[0096] Based on the above description, the following embodiment of the invention uses the cooling system of the main inclined shaft frequency converter under extremely cold conditions (Ruifeng Coal Mine) as an example for illustration: The Ruifeng Coal Mine main inclined shaft frequency converter adopts a closed cooling system with static pressure water introduced from a high-level water tank. Four frequency converters are connected in parallel through Ф40 galvanized steel pipes. A filter and a one-way valve 40 are added to achieve a resistance increase effect, so that the cooling flow is distributed as needed. A liquid collection tank 50 and a fan driven by an explosion-proof motor are added to the closed circulation loop to remove the heat generated by the frequency converter. The use of the explosion-proof motor and cooling water tank of the original obsolete underground worm gear air compressor cooling system reduces procurement costs, effectively explores the reuse value of obsolete equipment, and achieves cost reduction and efficiency improvement.

[0097] During the circulation process, the coolant passes through the following components in sequence: the heat dissipation components of the inverter body, the return galvanized pipe, the heat dissipation device 20, the collection tank 50, the main booster pump, the inlet pipe, the distributor valve, and the heat dissipation components of the inverter body, thus achieving a closed-loop circulation for heat transfer.

[0098] The main booster pump automatically adjusts the system flow rate based on system monitoring information, ensuring the frequency converter operates within its optimal temperature range and pressure tolerance range of 0.1MPa to 0.3MPa. This reduces water waste in arid regions, minimizes equipment downtime caused by substandard water quality, and ultimately lowers the equipment failure rate after the upgrade.

[0099] As shown in Figure 3, the bidirectional wireless transmission module transmits signals to the long-distance relay, enabling industrial remote control. This allows for on-site alarm transmission to the central control room of the transportation team in case of a fault. The control unit module implements self-locking and interlocking functions. After a fault occurs and the pressure sensor detects a pressure change, it uploads the fault information to the control center, stopping the closed-loop operation and automatically switching to the backup booster pump 32, triggering the alarm function.

[0100] Usage results show that the frequency converter can operate normally in ambient temperatures ranging from -35℃ to 40℃, avoiding the impact of freezing damage to water-cooled equipment in low-temperature environments. With a daily raw coal production of approximately 18,000 tons, no frequency converter overheating failures or shutdowns occurred, and no main inclined shaft shutdowns were caused by water quality issues, resulting in a significant reduction in the failure rate. This enables all-weather operation of the main inclined shaft, preventing the impact of electromechanical accidents and improving the safe operation capability of the main transportation system.

[0101] The modified closed-loop cooling system can save 7680 m³ of water per month in arid regions. 3 This effectively improves resource utilization and reduces the treatment pressure on sewage treatment plants. (Based on a cost of 10 yuan / m³) 3 It is estimated that this will save 76,000 yuan / month in production costs and 912,000 yuan / year in production water costs. It will also save 2,000 yuan / month in inverter maintenance costs and 1,000 yuan / month in strong acid hazardous waste treatment costs. Using coolant will reduce inorganic acid corrosion of the cooling water channels, effectively extending equipment lifespan. The high-temperature problem of the main shaft inverter has not recurred after the modification. The economic target of monthly savings is 79,000 yuan / month. Simultaneously, setting a starting temperature of 33℃ and maintaining the booster pump in standby mode will achieve energy savings.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A closed-loop cooling system for a mining frequency converter, characterized in that, include: A closed-loop circulation system is composed of multiple inverter body heat dissipation components connected in parallel through pipes; a heat dissipation device is located in the closed-loop circulation system to cool the coolant flowing through it; a booster pump assembly is located in the closed-loop circulation system to drive the coolant circulation; the booster pump assembly includes a main booster pump and a standby booster pump connected in parallel; a temperature sensor is used to monitor the temperature of the coolant in the closed-loop circulation system; a pressure sensor is used to monitor the fluid pressure in the closed-loop circulation system; and a control unit is electrically connected to the temperature sensor, the pressure sensor, the main booster pump, and the standby booster pump, respectively. The control unit is configured to: adjust the operating frequency of the main booster pump in real time according to the temperature monitored by the temperature sensor to change the flow rate of the coolant in the closed-loop circulation system. And when the pressure in the closed-loop circuit is detected by the pressure sensor to be lower than a preset fault threshold, the main booster pump is stopped and the standby booster pump is started.

2. The closed-loop cooling system for the mining frequency converter according to claim 1, characterized in that, The main booster pump is equipped with a first control valve on both its upstream and downstream pipelines, and the first control valve is electrically connected to the control unit; the standby booster pump is equipped with a second control valve on both its upstream and downstream pipelines, and the second control valve is electrically connected to the control unit.

3. The closed-loop cooling system for the mining frequency converter according to claim 2, characterized in that, The main booster pump is a variable frequency booster pump.

4. The closed-loop cooling system for the mining frequency converter according to claim 1, characterized in that, Each of the heat dissipation components of the inverter body is equipped with a filter and a one-way valve on its parallel branch.

5. The closed-loop cooling system for a mining frequency converter according to any one of claims 1 to 4, characterized in that, The heat dissipation device includes: a radiator body connected between the inverter body located at the end and the booster pump assembly; and a fan located on one side of the radiator body, the fan being driven by an explosion-proof motor.

6. The closed-loop cooling system for the mining frequency converter according to claim 5, characterized in that, Also includes: A liquid collection tank is located downstream of the heat dissipation device and upstream of the booster pump assembly, and is used to store antifreeze coolant.

7. The closed-loop cooling system for a mining frequency converter according to any one of claims 1 to 4, characterized in that, Also includes: A wireless transmission module, which is electrically connected to the control unit, is used to wirelessly transmit alarm signals to the central control room when a system failure occurs.

8. A cooling method for a closed-loop cooling system based on the mining frequency converter according to any one of claims 1 to 7, characterized in that, The process includes the following steps: real-time monitoring of the temperature parameters of the inverter body's heat load and real-time monitoring of the pressure parameters of the closed-loop circulation loop; and real-time adjustment of the operating frequency of the main booster pump based on the temperature monitored by the temperature sensor to change the flow rate of the coolant in the closed-loop circulation loop. And when the pressure in the closed-loop circuit is detected by the pressure sensor to be lower than a preset fault threshold, the main booster pump is controlled to stop working, and the standby booster pump is started to take over the main booster pump to perform the cyclic operation.

9. The cooling method of the closed-loop cooling system for a mining frequency converter according to claim 8, characterized in that, The real-time adjustment of the operating frequency of the main booster pump based on the temperature monitored by the temperature sensor includes: comparing the real-time coolant temperature monitored by the temperature sensor with a preset target temperature to obtain a temperature deviation value; calculating a proportional adjustment component based on the temperature deviation value; calculating an integral adjustment component based on the historical accumulation of the temperature deviation value to eliminate steady-state error; calculating a derivative adjustment component based on the rate of change of the temperature deviation value to suppress temperature fluctuations and overshoot; and superimposing the proportional adjustment component, integral adjustment component, and derivative adjustment component to generate a final control signal to adjust the operating frequency of the main booster pump in real time.

10. The cooling method of the closed-loop cooling system for a mining frequency converter according to claim 8, characterized in that, The cooling method further includes: when the temperature parameter is detected to exceed the preset start-up temperature threshold, starting the main booster pump to begin cyclic operation; when the temperature parameter is detected to be lower than the start-up temperature threshold, controlling the main booster pump to be in standby or stop state; while starting the backup booster pump, generating a fault alarm signal, and sending the alarm signal to the remote control room through a wireless transmission module.

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