Frequency converter hybrid heat dissipation control method and system

Abstract

The invention relates to the technical field of frequency converter hybrid heat dissipation technology, and provides a frequency converter hybrid heat dissipation control method and system, and the method comprises the steps: S1, signal collection and thermal load judgment, S2, advanced extension starting, S3, single-stage heat dissipation effect verification, S4, combined heat dissipation effect verification, and S5, dynamic energy-saving adjustment. Operation parameters and external working condition pre-change signals are acquired through the signal acquisition module, the thermal load change trend and the key temperature measurement point prediction temperature are pre-judged in combination with the thermal load prediction model, the heat dissipation equipment is started in advance before the temperature reaches the first starting threshold value, the problem that traditional passive heat dissipation response is lagged is solved, and the heat dissipation efficiency is improved. A forced air cooling and water cooling circulation graded heat dissipation mode is adopted, the heat dissipation mode is dynamically switched according to the heat load size and the heat dissipation effect, single-stage air cooling can meet the requirement during light load, water cooling is started in a combined mode to improve the heat dissipation efficiency during heavy load, meanwhile, part of heat dissipation equipment is closed when the temperature is lower than a target interval, and heat dissipation energy consumption is reduced to the maximum.

Description

Technical Field

[0001] This invention relates to the field of hybrid heat dissipation technology for frequency converters, and specifically to a hybrid heat dissipation control method and system for frequency converters. Background Technology

[0002] As a power electronic device, the inverter generates a lot of heat during operation through its internal power devices such as IGBTs and rectifier bridges. If the heat cannot be dissipated in time, the device temperature will rise, which will not only reduce the inverter's operating efficiency and shorten its service life, but may also trigger overheat protection in severe cases, causing equipment shutdown and affecting production continuity.

[0003] In existing technologies, inverter heat dissipation control mostly adopts a passive control mode of "starting after the temperature reaches the target," which lacks the ability to predict changes in heat load. Often, the heat dissipation equipment is only activated after the temperature of the power devices rises, resulting in a delayed heat dissipation response and a tendency to cause temporary overheating. At the same time, some hybrid heat dissipation solutions simply add air-cooling and water-cooling equipment without setting up a staged start-up or heat dissipation effect verification mechanism. Either the single-stage heat dissipation is insufficient, leading to overheating, or the blind activation of multiple stages of heat dissipation results in energy waste.

[0004] To address the aforementioned problems, we propose a hybrid heat dissipation control method and system for frequency converters. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a hybrid heat dissipation control method and system for frequency converters, overcoming the deficiencies of the prior art. By real-time acquisition of frequency converter operating parameters and receiving external pre-commands, it achieves advanced prediction of heat load changes. Based on the prediction results, hybrid heat dissipation equipment such as air cooling and water cooling is activated in stages before the temperature reaches the threshold. Combined with closed-loop feedback from temperature sensors, the effectiveness of single-stage and combined heat dissipation modes is dynamically verified and evaluated.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A hybrid heat dissipation control method and system for frequency converters includes the following steps:

[0008] Step S1. The operating status parameters of the frequency converter are acquired in real time through the signal acquisition module. The operating status parameters include at least the output current, output frequency, and ambient temperature inside the frequency converter cabinet. At the same time, the equipment condition pre-change signal from the external control system is received through the communication module. Based on the operating status parameters and the pre-change signal, the main control unit calls the built-in heat load prediction model to predict the heat load change trend of the frequency converter and calculate the predicted temperature of key temperature measurement points.

[0009] Step S2. When it is predicted that the heat load will increase and the predicted temperature reaches the first start-up threshold T0-ΔT, the first-stage heat dissipation device in the hybrid heat dissipation device is started in advance according to the preset start-up priority; where ΔT is the start-up temperature difference dynamically corrected according to the ambient temperature.

[0010] Step S3. After starting the first-level heat dissipation device, continuously monitor the actual temperature of the key temperature measurement point within the first preset evaluation time t1 and compare it with the first target temperature threshold T0. If the actual temperature continuously drops to the range defined by the temperature threshold T0 within t1 and stabilizes, it is determined that the heat dissipation requirements are met. If it does not drop to the range, it is determined that the requirements are not met, and the second-level heat dissipation device is immediately started and switched to the combined heat dissipation mode.

[0011] Step S4. After switching to the combined heat dissipation mode, the actual temperature is continuously monitored within the second preset evaluation time t2 and compared with the second target temperature threshold T1. If the actual temperature drops and stabilizes within the range defined by the temperature threshold T1 within t2, it is determined that the requirements are met. If it still cannot drop to the range, it is determined that the heat dissipation capacity is insufficient. At this time, the intelligent control unit generates a derating command to control the inverter to reduce the output power and generates a warning signal output.

[0012] Step S5. During operation of any heat dissipation mode, if the actual temperature continues to drop and falls below the lower limit of the target temperature range of the current mode, some heat dissipation devices are shut down in a preset order; if the temperature subsequently rises back to the first start-up threshold T0-ΔT, steps S2 to S4 are repeated.

[0013] Preferably, in step S1, the signal acquisition module includes a current detection module: sampling the DC bus current through a Hall sensor, wherein the Hall sensor is mounted on the DC bus conductor, and the sampled data is transmitted to the main control unit after signal conditioning;

[0014] Voltage detection module: used to detect DC bus voltage and output voltage. It is connected to the DC bus and output terminal through a voltage divider resistor network, and uses an isolation operational amplifier for signal conditioning. The conditioned voltage signal is then transmitted to the main control unit.

[0015] Frequency detection unit: used to detect the output voltage cycle of the frequency converter to obtain the output frequency, and the detection data is uploaded to the main control unit in real time;

[0016] Communication module: An industrial bus interface integrated in the main control unit of the frequency converter, which communicates bidirectionally with the programmable logic controller, which is the external control system, to receive pre-change signals containing load change magnitude and time nodes and transmit them to the main control unit.

[0017] Preferably, the operating status parameters include at least the output current collected by the current sensor, the DC bus voltage collected by the voltage detection module, the output frequency obtained by the frequency detection unit, and the ambient temperature collected by the temperature sensor independently installed in the inverter cabinet; the ambient temperature data is transmitted to the main control unit, which performs dynamic correction of the ΔT value; when the ambient temperature is higher than 35℃, ΔT is increased by 1-2℃; when the ambient temperature is lower than 10℃, ΔT is decreased by 1-2℃.

[0018] Preferably, the hybrid heat dissipation device includes a forced air cooling unit as a first-stage heat dissipation device and a water-cooled circulation unit as a second-stage heat dissipation device;

[0019] The forced air cooling unit includes a fan assembly. The main control unit is connected to the fan assembly through a speed control circuit and outputs speed control commands based on temperature data to control the fan assembly speed.

[0020] The water-cooled circulation unit includes a cooling water pump, a cooling channel arranged in close contact with the heat-generating components, and a liquid level sensor. The main control unit is connected to the cooling water pump via a relay to control the pump's start and stop. The cooling channel is tightly attached to the heat dissipation substrate of the inverter power module through a thermally conductive silicone grease filling layer. The liquid level sensor is installed inside the coolant expansion tank, and its signal output terminal is connected to the main control unit to upload liquid level data in real time, allowing the main control unit to determine the coolant status.

[0021] Preferably, the actual temperature of the key temperature measurement point mentioned in steps S3 and S4 is collected by multiple PT100 platinum resistance temperature sensors. Each sensor is set on the surface of the key heat-generating component inside the frequency converter and is connected to the multiple analog input channels of the main control unit through shielded cables. After the temperature signal collected by the temperature sensor is transmitted to the main control unit, the main control unit performs data processing.

[0022] Preferably, the heat dissipation effect comparison in steps S3 and S4 is performed by the main control unit, specifically including:

[0023] Data sampling: From the start of the heat dissipation equipment, the main control unit controls the temperature sensor to collect and store temperature data at a fixed period Δt;

[0024] Trend judgment: The main control unit analyzes the temperature data of the most recent consecutive cycles to determine whether it maintains a monotonically decreasing trend;

[0025] Rate vs. endpoint comparison: The main control unit calculates the average temperature drop rate and compares it with the preset rate threshold; at the end of the evaluation period, the current temperature is compared with the target temperature threshold.

[0026] Logical judgment: The main control unit executes the judgment logic. When the continuous temperature drop and the average temperature drop rate meet the standard at the same time, or when the end temperature meets the standard at the end of the evaluation period, the heat dissipation effect is judged to be qualified; otherwise, it is unqualified.

[0027] Command output: If the single-stage heat dissipation verification in step S3 is deemed unqualified, the main control unit shall immediately issue a command to activate the second-stage heat dissipation device.

[0028] If the joint heat dissipation verification in step S4 is deemed unqualified, the main control unit triggers the generation of a derating command and sends it to the inverter main controller to control the inverter to reduce the output power, and at the same time generates a warning signal output.

[0029] Preferably, the heat load prediction model is a thermodynamic calculation model based on inverter loss calculation, which is called and executed by the main control unit. The specific process includes:

[0030] First, the main control unit's control signal acquisition module collects the inverter's output current, output frequency, carrier frequency, and DC bus voltage in real time.

[0031] Next, the main control unit calculates the conduction loss and switching loss of the power device based on its power characteristic parameters, and sums them to obtain the total heat generation power.

[0032] Then, the main control unit converts the inverter's heat dissipation structure into an equivalent thermal resistance-thermal capacity network model with lumped parameters;

[0033] Finally, the main control unit uses the current temperature as the initial value and combines the total heat generation power and thermal resistance network model to iteratively calculate the predicted temperature of key points after a set time in the future, which is used to trigger advanced heat dissipation control.

[0034] The warning signal is generated by the main control unit and includes a switch signal that drives the local audible and visual alarm and a communication message containing a fault code sent to the host computer monitoring system.

[0035] A hybrid heat dissipation control system for a frequency converter, used to implement the aforementioned control method, includes:

[0036] Sensing and communication unit: includes current and voltage sensors for acquiring current and voltage parameters, a group of temperature sensors for acquiring temperature, and a bus communication interface for exchanging data with an external controller; each sensor and interface is connected to the intelligent control unit for signal transmission, and uploads acquired data and external commands in real time.

[0037] The heat dissipation unit includes a forced air cooling subunit as the first-stage heat dissipation device and a water cooling circulation subunit as the second-stage heat dissipation device.

[0038] The forced air cooling subunit includes a cooling fan controlled by its drive circuit, and the water cooling circulation subunit includes a cooling water pump controlled by its drive circuit; the control terminals of the drive circuits of the cooling fan and the cooling water pump are both connected to the corresponding control output terminals of the intelligent control unit.

[0039] Intelligent control unit: As the core processing and decision-making component, its input terminal is connected to the sensing and communication unit to receive operating parameters, temperature and external commands; its control output terminal is connected to the drive circuit corresponding to each subunit in the heat dissipation execution unit.

[0040] The intelligent control unit is configured to: perform heat load prediction and temperature calculation, generate and send start / stop and speed control commands for the heat dissipation equipment to the drive circuit, execute closed-loop verification logic for heat dissipation effect, and output inverter derating control command and system warning signal when verification fails.

[0041] This invention provides a hybrid heat dissipation control method and system for frequency converters. It has the following beneficial effects:

[0042] By acquiring operating parameters and external operating condition pre-change signals through a signal acquisition module, and combining this with a heat load prediction model to predict heat load change trends and key temperature measurement points, the heat dissipation equipment is activated in advance before the temperature reaches the first start-up threshold, thus solving the problem of delayed response in traditional passive heat dissipation.

[0043] It adopts a forced air cooling + water cooling circulation staged heat dissipation mode, and dynamically switches the heat dissipation mode according to the heat load and heat dissipation effect. Under light load, single-stage air cooling can meet the needs, while under heavy load, water cooling is activated to improve heat dissipation efficiency. At the same time, when the temperature is lower than the target range, some heat dissipation equipment is shut down to minimize heat dissipation energy consumption.

[0044] A two-level heat dissipation effect verification mechanism is set up. The main control unit monitors temperature changes in real time and calculates the temperature drop rate to accurately determine whether the heat dissipation meets the requirements. In case of insufficient heat dissipation capacity, derating control and early warning are triggered in time to avoid the inverter from shutting down due to overheating.

[0045] Based on the dynamic correction of the ambient temperature inside the inverter cabinet, the temperature difference ΔT is adjusted to start the heat dissipation equipment in advance in high temperature environment and ΔT is adjusted to reduce ineffective heat dissipation in low temperature environment. Attached Figure Description

[0046] Figure 1 This is a flowchart of the control method of the present invention;

[0047] Figure 2 This is a diagram illustrating the control system architecture and signal flow of the present invention. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] See attached document Figures 1-2 As shown, a hybrid heat dissipation control method and system for frequency converters includes the following steps:

[0050] Step S1. The operating status parameters of the frequency converter are acquired in real time through the signal acquisition module. The operating status parameters include at least the output current, output frequency, and ambient temperature inside the frequency converter cabinet. At the same time, the equipment condition pre-change signal from the external control system is received through the communication module. Based on the operating status parameters and the pre-change signal, the main control unit calls the built-in heat load prediction model to predict the heat load change trend of the frequency converter and calculate the predicted temperature of key temperature measurement points.

[0051] Step S2. When it is predicted that the heat load will increase and the predicted temperature reaches the first start-up threshold T0-ΔT, the first-stage heat dissipation device in the hybrid heat dissipation device is started in advance according to the preset start-up priority; where ΔT is the start-up temperature difference dynamically corrected according to the ambient temperature.

[0052] Step S3. After starting the first-level heat dissipation device, continuously monitor the actual temperature of the key temperature measurement point within the first preset evaluation time t1 and compare it with the first target temperature threshold T0. If the actual temperature continuously drops to the range defined by the temperature threshold T0 within t1 and stabilizes, it is determined that the heat dissipation requirements are met. If it does not drop to the range, it is determined that the requirements are not met, and the second-level heat dissipation device is immediately started and switched to the combined heat dissipation mode.

[0053] Step S4. After switching to the combined heat dissipation mode, the actual temperature is continuously monitored within the second preset evaluation time t2 and compared with the second target temperature threshold T1. If the actual temperature drops and stabilizes within the range defined by the temperature threshold T1 within t2, it is determined that the requirements are met. If it still cannot drop to the range, it is determined that the heat dissipation capacity is insufficient. At this time, the intelligent control unit generates a derating command to control the inverter to reduce the output power and generates a warning signal output.

[0054] Step S5. During operation of any heat dissipation mode, if the actual temperature continues to drop and falls below the lower limit of the target temperature range of the current mode, some heat dissipation devices are shut down in a preset order; if the temperature subsequently rises back to the first start-up threshold T0-ΔT, steps S2 to S4 are repeated.

[0055] In step S1, the signal acquisition module includes a current detection module: sampling the DC bus current through a Hall sensor, the Hall sensor being mounted on the DC bus conductor, and the sampled data being transmitted to the main control unit after signal conditioning;

[0056] Voltage detection module: used to detect DC bus voltage and output voltage. It is connected to the DC bus and output terminal through a voltage divider resistor network, and uses an isolation operational amplifier for signal conditioning. The conditioned voltage signal is then transmitted to the main control unit.

[0057] Frequency detection unit: used to detect the output voltage cycle of the frequency converter to obtain the output frequency, and the detection data is uploaded to the main control unit in real time;

[0058] Communication module: The industrial bus interface integrated in the main control unit of the frequency converter communicates bidirectionally with the programmable logic controller (PLC) that serves as the external control system. It receives pre-change signals containing load change magnitude and time nodes and transmits them to the main control unit to achieve data interaction and collaboration.

[0059] The operating status parameters include at least the output current collected by the current sensor, the DC bus voltage collected by the voltage detection module, the output frequency obtained by the frequency detection unit, and the ambient temperature collected by the temperature sensor independently installed in the inverter cabinet; the ambient temperature data is transmitted to the main control unit, which performs dynamic correction of the ΔT value; when the ambient temperature is higher than 35℃, ΔT is increased by 1-2℃; when the ambient temperature is lower than 10℃, ΔT is decreased by 1-2℃.

[0060] The hybrid heat dissipation device includes a forced air cooling unit as the first-stage heat dissipation device and a water cooling circulation unit as the second-stage heat dissipation device.

[0061] The forced air cooling unit includes a fan assembly. The main control unit is connected to the fan assembly through a speed control circuit and outputs speed control commands based on temperature data to control the fan assembly speed.

[0062] The water-cooled circulation unit includes a cooling water pump, cooling channels arranged in close contact with the heat-generating components, and a liquid level sensor. The main control unit is connected to the cooling water pump via a relay to control the pump's start and stop. The cooling channels are tightly attached to the heat dissipation substrate of the inverter power module through a thermally conductive silicone grease filling layer. The liquid level sensor is installed inside the coolant expansion tank, and its signal output terminal is connected to the main control unit to upload liquid level data in real time. The main control unit judges the coolant status to ensure the reliable operation of the water-cooling system.

[0063] The actual temperature of the key temperature measurement points mentioned in steps S3 and S4 is collected by multiple PT100 platinum resistance temperature sensors. Each sensor is set on the surface of the key heat-generating components inside the frequency converter and is connected to the multiple analog input channels of the main control unit through shielded cables. After the temperature signals collected by the temperature sensors are transmitted to the main control unit, the main control unit processes the data.

[0064] The heat dissipation effect comparison in steps S3 and S4 is performed by the main control unit, specifically including:

[0065] Data sampling: From the start of the heat dissipation equipment, the main control unit controls the temperature sensor to collect and store temperature data at a fixed period Δt (Δt=10s);

[0066] Trend judgment: The main control unit analyzes the temperature data of the most recent consecutive cycles to determine whether it maintains a monotonically decreasing trend;

[0067] Rate vs. endpoint comparison: The main control unit calculates the average temperature drop rate and compares it with the preset rate thresholds (v1≥0.5℃ / min, v2≥1℃ / min); at the end of the evaluation period (t1 or t2), the current temperature is compared with the target temperature threshold (T0 or T1).

[0068] Logical judgment: The main control unit executes the judgment logic. When the continuous temperature drop and the average temperature drop rate meet the standard at the same time, or when the end temperature meets the standard at the end of the evaluation period, the heat dissipation effect is judged to be qualified; otherwise, it is unqualified.

[0069] Command output: If the single-stage heat dissipation verification in step S3 is deemed unqualified, the main control unit shall immediately issue a command to activate the second-stage heat dissipation device.

[0070] If the joint heat dissipation verification in step S4 is deemed unqualified, the main control unit triggers the generation of a derating command and sends it to the inverter main controller to control the inverter to reduce the output power, and at the same time generates a warning signal output.

[0071] The heat load prediction model is a thermodynamic calculation model based on inverter loss calculation, which is called and executed by the main control unit. The specific process includes:

[0072] First, the main control unit's control signal acquisition module collects the inverter's output current, output frequency, carrier frequency, and DC bus voltage in real time.

[0073] Next, the main control unit calculates the conduction loss and switching loss of the power device (IGBT) based on its power characteristic parameters, and sums them to obtain the total heat generation power.

[0074] Then, the main control unit converts the inverter's heat dissipation structure into an equivalent thermal resistance-thermal capacity network model with lumped parameters;

[0075] Finally, the main control unit uses the current temperature as the initial value and combines the total heat generation power and thermal resistance network model to iteratively calculate the predicted temperature of key points after a set time in the future, which is used to trigger advanced heat dissipation control.

[0076] The warning signal is generated by the main control unit and includes a switch signal that drives the local audible and visual alarm and a communication message containing a fault code sent to the host computer monitoring system to ensure effective transmission of the warning information.

[0077] A hybrid heat dissipation control system for a frequency converter, used to implement the aforementioned control method, includes:

[0078] Sensing and communication unit: includes current and voltage sensors for acquiring current and voltage parameters, a group of temperature sensors for acquiring temperature, and a bus communication interface for exchanging data with an external controller; each sensor and interface is connected to the intelligent control unit for signal transmission, and uploads acquired data and external commands in real time.

[0079] The heat dissipation unit includes a forced air cooling subunit as the first-stage heat dissipation device and a water cooling circulation subunit as the second-stage heat dissipation device.

[0080] The forced air cooling subunit includes a cooling fan controlled by its drive circuit, and the water cooling circulation subunit includes a cooling water pump controlled by its drive circuit; the control terminals of the drive circuits of the cooling fan and the cooling water pump are both connected to the corresponding control output terminals of the intelligent control unit.

[0081] Intelligent control unit: As the core processing and decision-making component, its input terminal is connected to the sensing and communication unit to receive operating parameters, temperature and external commands; its control output terminal is connected to the drive circuit corresponding to each subunit in the heat dissipation execution unit.

[0082] The intelligent control unit is configured to: perform heat load prediction and temperature calculation, generate and send start / stop and speed control commands for the heat dissipation equipment to the drive circuit, execute closed-loop verification logic for heat dissipation effect, and output inverter derating control command and system warning signal when verification fails;

[0083] Example 1: Industrial heavy-duty scenario (frequency converter application in mining machinery)

[0084] First, the parameters are set as follows: the first target temperature threshold T0 = 55℃, the second target temperature threshold T1 = 50℃, and the initial value of the pre-start temperature difference ΔT is set to 5℃; the first preset evaluation time t1 = 10min, the second preset evaluation time t2 = 15min, and the temperature sampling period Δt = 10s; the temperature drop rate thresholds v1 = 0.8℃ / min and v2 = 1.2℃ / min.

[0085] The signal acquisition module uses a Hall current sensor (model CS3000) mounted on the DC bus; the voltage detection module uses a voltage divider resistor network + isolation operational amplifier AD8421; and the frequency detection unit is integrated into the inverter's main control unit. In the hybrid cooling system, the forced air cooling unit uses a fan group (model 4020) composed of four axial fans, connected to the main control unit via a PWM speed control circuit. The water cooling circulation unit uses a miniature gear pump (flow rate 10L / min), and the cooling channel uses a copper serpentine tube, which is attached to the heat sink of the IGBT power module. The liquid level sensor uses a float sensor (model FY-30) installed in the expansion tank. Three PT100 sensors are set at key temperature measurement points, respectively installed on the surface of the IGBT module, the surface of the rectifier bridge, and inside the inverter cabinet.

[0086] Operation process: The signal acquisition module collects the inverter's output current (0-200A), output frequency (0-50Hz), and ambient temperature inside the cabinet in real time. At the same time, it receives the hoist preload command sent by the PLC via RS485 bus (e.g., the load will be increased to 80% after 10 seconds). The main control unit calls the heat load prediction model, and combined with the current output current of 180A and frequency of 50Hz, calculates that the sum of the IGBT module's conduction loss and switching loss is 3.2kW. Iterative calculation shows that the predicted temperature at the key temperature measurement point after 10 seconds is 50℃ (reaching T0-ΔT=55-5=50℃).

[0087] The main control unit determines that the heat load is about to increase and predicts that the temperature will reach the first start-up threshold. It immediately starts the four fans of the forced air cooling unit and runs them at 80% of the rated speed according to the preset priority.

[0088] After the air-cooling unit is started, the temperature is continuously monitored for 10 minutes (t1). The temperature drops from 50℃ to 53℃ in the first 5 minutes, but the temperature remains between 53-54℃ in the following 5 minutes and does not drop to the T0=55℃ range (not meeting the stability requirements). The main control unit determines that the single-stage heat dissipation does not meet the requirements and immediately starts the gear pump of the water-cooling circulation unit to switch to the combined heat dissipation mode.

[0089] Within 15 minutes (t2) of operation in the combined heat dissipation mode, the temperature continuously decreased from 54℃ to 49℃ and stabilized within the range of T1=50℃. The average temperature drop rate was 1.3℃ / min ≥ v2=1.2℃ / min, indicating that the heat dissipation requirements were met, and the operation of the combined heat dissipation mode was maintained.

[0090] When the hoist completes the hoisting operation, the load drops to 30%, the output current drops to 60A, and the temperature inside the cabinet drops to 48℃ after 10 minutes, which is lower than the lower limit of the T1=50℃ range. The main control unit shuts down two fans according to priority, and the water cooling pump maintains low speed operation. If the hoist is loaded again and the temperature rises back to 50℃ (T0-ΔT), the above graded start-up and verification process is repeated.

[0091] If the cooling efficiency decreases due to dust clogging the fan filter, and the temperature remains at 52℃ (higher than T1=50℃) after 15 minutes of combined cooling operation, the main control unit determines that the cooling capacity is insufficient, immediately generates a derating command to reduce the inverter output power to 90kW, simultaneously activates the local audible and visual alarm, and uploads fault code E001 (insufficient cooling) to the PLC.

[0092] Example 2: Light-load energy-saving scenario (inverter application for fans and pumps)

[0093] Parameter settings: First target temperature threshold T0 = 60℃, second target temperature threshold T1 = 55℃, initial value of pre-start temperature difference ΔT is set to 4℃; first preset evaluation time t1 = 8min, second preset evaluation time t2 = 12min, temperature sampling period Δt = 10s; temperature drop rate thresholds v1 = 0.5℃ / min, v2 = 1.0℃ / min;

[0094] The signal acquisition module uses a small Hall current sensor (model ACS712), the voltage detection module is simplified to a voltage divider resistor + ordinary operational amplifier LM324, and the communication module uses a Modbus-RTU bus interface to communicate with the PLC. In the hybrid heat dissipation equipment, the forced air cooling unit uses two silent fans (model 3010), the water cooling circulation unit uses a miniature centrifugal pump (flow rate 5L / min), and the cooling channel uses an aluminum flat plate channel. Two PT100 sensors are set at key temperature measurement points, which are installed on the surface of the IGBT module and inside the cabinet, respectively.

[0095] Operation process: The signal acquisition module acquires the output current of 30A (rated current 70A) and the output frequency of 30Hz. The ambient temperature inside the cabinet is 25℃. The PLC sends a pre-change signal that "the frequency will rise to 35Hz in 20 seconds". The main control unit calls the heat load prediction model, calculates the total heat generation power of 0.8kW, and predicts that the temperature of the key temperature measurement point will be 56℃ in 20 seconds (reaching T0-ΔT=60-4=56℃).

[0096] The main control unit starts one fan of the forced air cooling unit (started according to priority) and sets the speed to 60% of the rated speed; within 8 minutes (t1), the temperature drops from 56℃ to 58℃ and stabilizes in the range of T0=60℃. The average temperature drop rate is 0.6℃ / min≥v1=0.5℃ / min. It is determined that the single-stage heat dissipation meets the requirements and the single fan is kept running.

[0097] After the water pump runs for 1 hour, the load drops to 25%, the output frequency is 25Hz, and the temperature drops to 52℃, which is below the lower limit of the T0=60℃ range. The main control unit turns off the fan and runs with low power consumption by relying only on natural heat dissipation and water cooling circulation unit. Compared with the traditional continuous air cooling mode, the energy consumption is reduced by 35%.

[0098] Example 3: High-Temperature Environment Scenarios (Application of Frequency Converters in Metallurgical Workshops)

[0099] Parameter settings: First target temperature threshold T0 = 58℃, second target temperature threshold T1 = 53℃, initial value of pre-start temperature difference ΔT is set to 5℃; when the ambient temperature is higher than 35℃, ΔT is increased by 2℃ to 7℃; first preset evaluation time t1 = 8min, second preset evaluation time t2 = 12min, temperature sampling period Δt = 10s; temperature drop rate thresholds v1 = 1.0℃ / min, v2 = 1.5℃ / min;

[0100] The signal acquisition module is the same as in Example 1, except that an additional PT100 sensor is added outside the inverter cabinet to collect ambient temperature data. In the hybrid heat dissipation equipment, the forced air cooling unit uses a high-temperature resistant fan (temperature resistance 120℃), the water cooling circulation unit uses a stainless steel cooling channel, and the coolant is an ethylene glycol aqueous solution (concentration 50%) to improve heat dissipation efficiency in high-temperature environments. The intelligent control unit uses an independent control board (model STM32F407) and communicates with the inverter main controller via a CAN bus.

[0101] Operation process: The ambient temperature in the workshop is detected as 40℃ (above 35℃). The main control unit increases ΔT from 5℃ to 7℃, and the first start-up threshold becomes 58-7=51℃.

[0102] The signal acquisition module acquires an output current of 120A (rated current 150A), an output frequency of 45Hz, and an ambient temperature of 40℃. The PLC sends a pre-change signal that the frequency will rise to 50Hz in 5 seconds. The main control unit calculates the total heat generation power of 2.5kW and predicts that the temperature at the key temperature measurement point will be 51℃ in 5 seconds, reaching the first start-up threshold.

[0103] The main control unit starts the two fans of the forced air cooling unit and runs them at 100% rated speed.

[0104] Within 8 minutes (t1), the temperature rose from 51°C to 56°C (due to the influence of high ambient temperature, it did not decrease), and the average temperature drop rate was negative. It was determined that the single-stage heat dissipation did not meet the requirements, and the water cooling circulation unit was immediately activated.

[0105] Within 12 minutes (t2) of combined heat dissipation operation, the temperature dropped from 56℃ to 52℃ and stabilized within the range of T1=53℃, with an average temperature drop rate of 0.33℃ / min (due to the high ambient temperature, the rate was lower than v2=1.5℃ / min, but the final temperature met the standard), indicating that the heat dissipation requirements were met; the main control unit maintained the fan speed at 100% and the water pump at full load according to the ambient temperature to ensure temperature stability.

[0106] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. 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. Such 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 variable frequency drive hybrid thermal control method, comprising: The method comprises the following steps: Step S1. Real-time acquisition of the operating state parameters of the frequency converter by a signal acquisition module, the operating state parameters at least including output current, output frequency and temperature of the environment in the frequency converter cabinet; at the same time, receiving the device working condition pre-change signal from the external control system by a communication module; based on the operating state parameters and the pre-change signal, the built-in thermal load prediction model is called to predict the thermal load change trend of the frequency converter to be generated, and the predicted temperature of the key temperature measuring point is calculated; Step S2. When it is predicted that the thermal load will increase and the predicted temperature reaches the first starting threshold T0-ΔT, the first level of the hybrid heat dissipation device is started in advance according to the preset starting priority; wherein ΔT is the advance starting temperature difference dynamically corrected according to the environmental temperature; Step S3. After starting the first level of the heat dissipation device, the actual temperature of the key temperature measuring point is continuously monitored within the first preset evaluation time t1, and compared with the first target temperature threshold T0; if the actual temperature continuously decreases to the interval defined by the temperature threshold T0 within t1 and stabilizes, it is determined that the heat dissipation requirement is met; if it does not decrease to the interval, it is determined that the requirement is not met, and the second level of the heat dissipation device is immediately started, and the combined heat dissipation mode is switched to; Step S4. After switching to the combined heat dissipation mode, the actual temperature is continuously monitored within the second preset evaluation time t2, and compared with the second target temperature threshold T1; if the actual temperature decreases and stabilizes in the interval defined by the temperature threshold T1 within t2, it is determined that the requirement is met; if it still cannot decrease to the interval, it is determined that the heat dissipation capacity is insufficient, at which time the intelligent control unit generates a derating instruction to control the frequency converter to reduce the output power, and generates a warning signal output; Step S5. During the operation of any heat dissipation mode, if the actual temperature continuously decreases and is lower than the lower limit of the target temperature interval of the current mode, part of the heat dissipation device is closed in the preset order; if the temperature subsequently rises to the first starting threshold T0-ΔT, steps S2 to S4 are repeated.

2. The heat radiation control method according to claim 1, wherein In step S1, the signal acquisition module includes a current detection module: a Hall sensor is used to sample the direct current bus current, the Hall sensor is sleeved on the direct current bus conductor, and the sampled data is transmitted to the main control unit after signal conditioning; A voltage detection module is used to detect the direct current bus voltage and output voltage, which is connected with the direct current bus and output end through a voltage dividing resistor network, and the voltage signal after conditioning is transmitted to the main control unit through an isolation operational amplifier; A frequency detection unit is used to detect the output voltage period of the frequency converter to obtain the output frequency, and the detection data is uploaded to the main control unit in real time; A communication module is integrated in the industrial bus interface of the frequency converter main control unit, which communicates with the programmable logic controller as the external control system, receives the pre-change signal containing the load change amplitude and time node and transmits it to the main control unit.

3. The heat radiation control method according to claim 1, wherein The operating state parameters at least include output current collected by a current sensor, DC bus voltage collected by a voltage detection module, output frequency obtained by a frequency detection unit, and ambient temperature collected by a temperature sensor independently arranged in the frequency converter cabinet; the ambient temperature data is transmitted to the main control unit, and dynamic correction of a ΔT value is performed by the main control unit; when the ambient temperature is higher than 35 DEG C, the ΔT is up-regulated by 1-2 DEG C; when the ambient temperature is lower than 10 DEG C, the ΔT is down-regulated by 1-2 DEG C.

4. The heat radiation control method according to claim 1, wherein The mixed heat dissipation device comprises a forced air cooling unit as a first-stage heat dissipation device and a water cooling circulation unit as a second-stage heat dissipation device; The forced air cooling unit comprises a fan group, and the main control unit is connected with the fan group through a speed regulation circuit, and a speed regulation instruction is output according to temperature data to control the rotating speed of the fan group; The water cooling circulation unit comprises a cooling water pump, a cooling flow channel arranged in close contact with the heating component, and a liquid level sensor, the main control unit is connected with the cooling water pump through a relay to control the start and stop of the water pump, the cooling flow channel is closely attached to the heat dissipation substrate of the frequency converter power module through a heat-conducting silicone grease filling layer, and the liquid level sensor is installed in a cooling liquid expansion tank, and a signal output end thereof is connected to the main control unit to upload liquid level data in real time, and the cooling liquid state is judged by the main control unit.

5. The heat radiation control method according to claim 1, wherein The actual temperatures of the key temperature measuring points in steps S3 and S4 are collected by a plurality of PT100 platinum thermal resistance temperature sensors, each sensor is arranged on the surface of a key heating component in the frequency converter, and is connected to a plurality of analog input channels of the main control unit through shielded cables respectively, and after the temperature signals collected by the temperature sensors are transmitted to the main control unit, data processing is performed by the main control unit.

6. The heat radiation control method according to claim 1, wherein The heat dissipation effect comparison in steps S3 and S4 is performed by the main control unit, and specifically comprises the following steps: Data sampling: since the heat dissipation device is started, the main control unit controls the temperature sensor to collect and store temperature data at a fixed period Δt; Trend judgment: the main control unit analyzes the temperature data of a plurality of continuous periods to judge whether it maintains a monotone decreasing trend; Rate and endpoint comparison: the main control unit calculates an average temperature drop rate and compares it with a preset rate threshold; at the end of the evaluation period, the current temperature is compared with a target temperature threshold; Logical judgment: the main control unit executes a judgment logic, when the temperature continuously decreases and the average temperature drop rate meets the standard at the same time, or the endpoint temperature meets the standard at the end of the evaluation period, the heat dissipation effect is determined to be qualified; otherwise, it is unqualified; Instruction output: if it is determined to be unqualified in the single-stage heat dissipation verification of step S3, the main control unit immediately issues an instruction to start the second-stage heat dissipation device; If it is determined to be unqualified in the joint heat dissipation verification of step S4, the main control unit triggers a generation of a derating instruction and sends it to the frequency converter main controller to control the frequency converter to reduce the output power, and a warning signal is generated and output at the same time.

7. The heat radiation control method according to claim 1, wherein The thermal load prediction model is a thermodynamic calculation model based on frequency converter loss calculation, which is called and executed by the main control unit, and the specific process comprises the following steps: Firstly, the main control unit controls a signal collection module to collect output current, output frequency, carrier frequency and DC bus voltage of the frequency converter in real time; Then, the main control unit calculates the conduction loss and switching loss of the power device based on the power characteristic parameters, and sums them to obtain the total heat generation power; Then, the main control unit equivalent the heat dissipation structure of the frequency converter to a lumped parameter thermal resistance-capacitance network model; Finally, the main control unit takes the current temperature as the initial value, combines the total heat generation power and the thermal resistance network model, and iteratively calculates the key point predicted temperature after the future set time to trigger the advanced heat dissipation control; The warning signal is generated by the main control unit, including the on-off signal for driving the local sound-light alarm and the communication message containing the fault code sent to the upper computer monitoring system.

8. A frequency converter hybrid heat sink control system for implementing the control method of any one of claims 1-7, characterized by, It includes: Sensing and communication unit: including current sensor and voltage sensor for collecting current and voltage parameters, temperature sensor group for collecting temperature, and bus communication interface for exchanging data with external controller; each sensor and interface is signal connected with the intelligent control unit, and real-time upload of collected data and external instructions; The heat dissipation execution unit includes a forced air cooling subunit as the first level of heat dissipation equipment and a water cooling circulation subunit as the second level of heat dissipation equipment; The forced air cooling subunit contains a cooling fan controlled by its drive circuit, and the water cooling circulation subunit contains a cooling water pump controlled by its drive circuit; the control end of the drive circuit of the cooling fan and the cooling water pump is connected with the corresponding control output end of the intelligent control unit; The intelligent control unit is the core processing and decision-making component, its input end is signal connected with the sensing and communication unit for receiving operating parameters, temperature and external instructions; its control output end is signal connected with the drive circuit of each subunit in the heat dissipation execution unit; The intelligent control unit is configured to perform heat load prediction and temperature calculation, generate and send start-stop and speed regulation instructions of heat dissipation equipment to the drive circuit, execute closed-loop verification logic of heat dissipation effect, and output frequency converter derating control instructions and system warning signal when verification fails.

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