Temperature and humidity control method of frequency converter cabinet

Abstract

The invention discloses a temperature and humidity control method for a frequency converter cabinet, and the method specifically comprises the steps: setting the target module temperature of a frequency converter in the frequency converter cabinet, monitoring the current module temperature of the frequency converter, and obtaining the temperature difference et between the target module temperature and the current module temperature; according to the temperature difference et, the target opening degree ut of an expansion valve in a heat dissipation module of the frequency converter cabinet is calculated through a PID algorithm, and the expansion valve is adjusted and continuously controlled according to the opening degree ut, so that the module temperature of the frequency converter cabinet converges towards the target module temperature; the current module humidity in the frequency converter cabinet is monitored, and the dew point temperature is calculated according to the current module temperature and the current module humidity; obtaining a preset environment temperature and a preset environment humidity according to the dew point temperature; and the temperature in the frequency converter cabinet is adjusted according to the preset environment temperature and the preset environment humidity. Through the arrangement, the temperature and humidity control response in the frequency converter cabinet is more timely, the accuracy is higher, and the problems of condensation in the cabinet or overheating of the module and the like are effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of frequency converters, and particularly to a method for controlling the temperature and humidity of a frequency converter cabinet. Background Art

[0002] In the existing industrial automation systems, as a key power electronic device, the frequency converter is widely used in motor control and energy efficiency optimization. With the improvement of the integration level of the frequency converter and its increasing application in complex environments, the problem of temperature and humidity control of its internal modules has become increasingly prominent.

[0003] In the prior art, the temperature control of the modules in the frequency converter cabinet mainly relies on traditional fans or air conditioning systems for forced convection heat dissipation, lacking a precise adjustment mechanism based on real-time feedback of temperature difference. The existing systems often cannot flexibly adjust the opening degree of the heat dissipation module (such as the expansion valve) according to the real-time environment and the operating conditions of the equipment, resulting in the module temperature being prone to deviate from the set target value, affecting the stability and service life of the equipment operation. Summary of the Invention

[0004] In order to solve the deficiencies of the prior art, the purpose of the present invention is to provide a method for controlling the temperature and humidity of a frequency converter cabinet. This control method can accurately and dynamically control the temperature and humidity inside the frequency converter cabinet.

[0005] Based on the above purpose, the present invention adopts the following technical solutions:

[0006] A method for controlling the temperature and humidity of a frequency converter cabinet, comprising the steps of:

[0007] S1. Set the target module temperature of the frequency converter in the frequency converter cabinet, monitor the current module temperature of the frequency converter, and obtain the temperature difference e between the target module temperature and the current module temperature t ;

[0008] S2. According to the temperature difference e t , calculate the target opening degree u of the expansion valve in the heat dissipation module of the frequency converter cabinet through the PID algorithm t , and adjust and continuously control the expansion valve according to the opening degree u t so that the module temperature of the frequency converter cabinet converges to the target module temperature;

[0009] S3. Monitor the current module humidity inside the frequency converter cabinet, and calculate the dew point temperature according to the current module temperature and the current module humidity;

[0010] S4. Obtain the preset ambient temperature and preset ambient humidity based on the dew point temperature; when the temperature inside the cabinet is greater than the preset ambient temperature, start the fan of the surface cooler inside the frequency converter cabinet for circulating cooling inside the cabinet until the temperature inside the cabinet is less than the preset ambient temperature; when the humidity inside the cabinet is greater than the preset ambient humidity, dehumidify by condensation inside the surface cooler until the humidity inside the cabinet is less than the preset ambient humidity.

[0011] Further, step S2 specifically includes: According to the target opening u t , control the driver of the expansion valve to output the corresponding opening current, and the refrigerant flow rate in the heat dissipation module of the frequency converter cabinet changes accordingly, so that the module temperature of the frequency converter cabinet converges to the target module temperature.

[0012] Further, the PID algorithm formula in step S2 is:

[0013]

[0014] where, u t is the target opening; k p is the proportional coefficient; e t is the temperature difference; is the accumulation of errors; dt is the sampling period; det is the slope of the error change; T i is the integral time constant; T d is the differential time constant.

[0015] Further, step S2 also includes: According to the temperature difference e t , divide the temperature regulation into a large temperature difference area, an approaching area, and a fine-tuning area; when the temperature difference e t is in the large temperature difference area, control by increasing the proportional coefficient and the integral time constant; when the temperature difference e t is in the approaching area, control by reducing the proportional coefficient and the integral time constant and increasing the differential time coefficient at the same time; when the temperature difference e t is in the fine-tuning area, control by using the default proportional coefficient and integral time constant.

[0016] Further, when |e t |≥5°C, it is in the large temperature difference area, and at this time:

[0017]

[0018] k p1 =P K1 *k p ,

[0019] T i1 =P i1 *T i ,

[0020] Among them, k p1 is the proportionality coefficient of the large temperature difference region; P K1 is the proportionality amplification coefficient of the large temperature difference region, usually taking 1.5 - 2.5; T i1 is the integral time constant of the large temperature difference region; P i1 is the integral time amplification coefficient of the large temperature difference region, usually taking 1.5 - 2.5;

[0021] When 5°C > |e t | ≥ 2°C, it is in the approaching region, and at this time:

[0022]

[0023] k p2 = P K2 * k p ,

[0024] T i2 = P i2 * T i ,

[0025] T d2 = P d2 * T d ,

[0026] Among them, k p2 is the proportionality coefficient of the approaching region; P K2 is the proportionality amplification coefficient of the approaching region, usually taking 1 - 1.5; T i2 is the integral time constant of the approaching region; P i2 is the integral time amplification coefficient of the approaching region, usually taking 0.8 - 1.2; T d2 is the differential time constant of the approaching region; P d2 is the differential time amplification coefficient of the approaching region, usually taking 2 - 2.5;

[0027] When |e t | < 2°C, it is in the fine-tuning region, and at this time, the default k p , T i , T d parameters are adopted; at the same time, to prevent integral saturation, there is:

[0028] When entering the fine-tuning region, e t > 0, and for the first time e t < 0, the error integral accumulation is halved;

[0029] When entering the fine-tuning region, e t < 0, and for the first time e t > 0, the error integral accumulation is halved.

[0030] Furthermore, a return temperature difference of ±0.5°C is set at a critical point between the large temperature difference zone and the approach zone; and a return temperature difference of ±0.5°C is set at a critical point between the approach zone and the fine-tuning zone.

[0031] Furthermore, in step S3, the calculation formula of the dew point temperature is:

[0032]

[0033] Among them, T s is the dew point temperature; T is the current air temperature; RH is the relative humidity.

[0034] Furthermore, in step S4, an electronic dehumidifier and a circulating fan in the cabinet can be used to control the temperature and humidity, specifically including: the electronic dehumidifier sets the target temperature and humidity by reading the target module temperature and current temperature and humidity information of the inverter cabinet, and at the same time links the circulating fan in the cabinet to dehumidify and cool down, so that the current module temperature and current module humidity of the inverter cabinet converge to the target temperature and humidity.

[0035] Furthermore, step S2 further includes:

[0036] Assume the inlet temperature of the refrigerant in the heat dissipation module is T in , the target module temperature of the inverter is T a ; Then: When T a -T in >3℃ and T in When the temperature is lower than 40℃, the heat dissipation module is in cooling mode; when T a -T in ≤3℃ or T in When the temperature is ≥40℃, the heat dissipation module is in heating condition;

[0037] When the heat dissipation module is in cooling condition, the expansion valve at the inlet of the heat dissipation module is fully opened, and only the expansion valve at the outlet is controlled;

[0038] When the heat dissipation module is in heating condition, the expansion valve at the outlet of the heat dissipation module is fully opened, and the expansion valve at the inlet is controlled by the PID algorithm.

[0039] The present invention provides a method for controlling temperature and humidity of a frequency converter cabinet. The method dynamically adjusts the opening of the expansion valve in the heat dissipation module through the PID algorithm, realizes accurate control of the module temperature in the frequency converter cabinet, and combines dew point temperature calculation and multiple temperature and humidity control measures to ensure the stability and safety of the cabinet environment, solving the problems of untimely response, inaccurate control, easy condensation or module overheating in the prior art of the frequency converter cabinet temperature and humidity control. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a schematic diagram of the internal structure of the first accommodating chamber of the frequency converter cabinet provided by the present invention;

[0041] Figure 2 It is a schematic diagram of the internal structure of the second accommodation cavity of the frequency converter cabinet provided according to the present invention;

[0042] Figure 3 It is a schematic diagram of the connection of internal devices of the frequency converter cabinet provided according to the present invention;

[0043] Figure 4 It is a step diagram of the temperature and humidity control method of the frequency converter cabinet provided according to the present invention. Detailed implementation manners

[0044] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0045] At the same time, in order to clearly illustrate the technical solutions of the present application, the upper side, lower side, left side, right side, front side and rear side as shown in Figure 1 are also defined.

[0046] The present application provides a temperature and humidity control method for a frequency converter cabinet, which is used to accurately and dynamically control the temperature and humidity inside the frequency converter cabinet. As shown in Figures 1 to 3 , the frequency converter cabinet specifically includes a cabinet body 1, a frequency converter 2, a surface cooler 3 and a liquid cooling component 4.

[0047] Specifically, the cabinet body 1 includes a first accommodation cavity 11 and a second accommodation cavity 12 along the front-rear direction, and the first accommodation cavity 11 and the second accommodation cavity 12 communicate with each other. The frequency converter 2 and the surface cooler 3 are respectively arranged in the first accommodation cavity 11, and the liquid cooling component 4 is arranged in the second accommodation cavity 12. The liquid cooling component 4 includes an inlet pipe 41 and an outlet pipe 42. One end of the inlet pipe 41 is connected to an external main condenser, and the other end is divided into a first branch 411 and a second branch 412. The first branch 411 is connected to the surface cooler 3, and the second branch 412 is connected to the frequency converter 2. More specifically, the second branch 412 is connected to the rectifier radiator and the inverter radiator inside the frequency converter 2. One end of the outlet pipe 42 is connected to the frequency converter 2, and the other end is connected to an external main evaporator.

[0048] Through the above settings, the frequency converter 2 dissipates heat directly through liquid cooling, improving the heat dissipation efficiency. After the refrigerant absorbs heat inside the frequency converter 2, it flows to the external main evaporator through the outlet pipe 42, thereby realizing the efficient cooling of the frequency converter 2. The surface cooler 3 is used to cool the air inside the cabinet body 1 and reduce the humidity, thereby preventing the frequency converter 2 from being damaged due to condensation.

[0049] As shown in Figure 2As shown, the first branch 411 uses a capillary tube, and a solenoid valve 43 for controlling the working state of the surface cooler 3 is provided on the first branch 411. By combining the capillary tube with the solenoid valve 43 to control the flow of the refrigerant into the surface cooler 3, the precise control ability of the refrigerant flow rate is improved, and the cooling performance and dew condensation control effect of the surface cooler 3 are optimized.

[0050] A dew condensation plate is provided inside the surface cooler 3, and a drain port for discharging condensed water is provided at the bottom. When the frequency converter 2 is in the on state, the solenoid valve 43 remains open. After the refrigerant enters the surface cooler 3, it cools and condenses on the dew condensation plate, improving the reliability and safety of the frequency converter cabinet in a high-humidity environment, reducing the maintenance cost and failure probability caused by dew condensation, and ensuring the long-term stable operation of the equipment.

[0051] As Figure 1 shown, a reactor 5 is provided at the bottom of the first accommodation cavity 11, and the frequency converter 2 is electrically connected to the reactor 5. Among them, the reactor 5 is arranged close to the surface cooler 3, so that the cooling air flow can efficiently take away the heat during its operation, reduce the temperature rise, and improve the service life and operation reliability of the reactor 5.

[0052] Furthermore, a fan 31 is provided at the top of the surface cooler 3, and air blows upward from inside the surface cooler 3 to blow cold air into the cabinet 1. After the air circulates, it returns from the bottom of the surface cooler 3, taking away the heat on the reactor 5 at the same time, further improving the heat dissipation efficiency of the system, being convenient for operation and maintenance, and being able to meet the requirements of long-term stable operation.

[0053] As Figure 3 shown, a first expansion valve 44 for controlling the refrigerant flow rate is provided on the second branch 412; a temperature detection module is provided inside the frequency converter 2, and the temperature detection module is used to detect the current module temperature of the frequency converter 2. The opening degree of the first expansion valve 44 is obtained through an opening degree algorithm formula according to the current module temperature and the preset temperature of the frequency converter 2. Through the above settings, the dynamic adjustment of the refrigerant flow rate can be realized, so that the module temperature of the frequency converter 2 is always kept within a preset reasonable range, effectively preventing the performance attenuation or failure of components caused by too high temperature. At the same time, the system has a fast response speed and high control accuracy, can adapt to the cooling requirements under different load conditions, and improves the stability and service life of the frequency converter 2.

[0054] Specifically, the opening degree algorithm formula of the first expansion valve 44 is:

[0055]

[0056] where u t is the target opening degree; k p is the proportional coefficient; e t is the difference between the target temperature and the current module temperature; is the accumulation of errors; dt is the sampling period; det is the slope of the error change; T i is the integral time constant; T d is the differential time constant.

[0057] As Figure 3 shown, a second expansion valve 45 for controlling the liquid discharge flow rate is provided on the liquid outlet pipe 42. When the system is in the refrigeration condition, the first expansion valve 44 is fully open, and only the opening degree of the second expansion valve 45 is controlled. When the system is in the heating condition, the refrigerant outflow temperature is relatively high, and the liquid extraction temperature of the corresponding condenser is relatively high. At this time, the second expansion valve 45 needs to be fully open, and the opening degree of the first expansion valve 44 is controlled by using the PID algorithm, which can effectively reduce the refrigerant temperature and take away heat faster, making it easier for the frequency converter 2 to reach the target temperature.

[0058] As Figure 2 and Figure 3 shown, stop valves 6 are respectively provided on the liquid inlet pipe 41 and the liquid outlet pipe 42 outside the second accommodation chamber 12, so as to realize the quick isolation and precise control of each module of the liquid cooling assembly 4, and improve the flexibility and safety of the system operation and maintenance. As Figure 4 shown, the temperature and humidity control method of the frequency converter cabinet specifically includes the steps:

[0059] S1. Set the target module temperature of the frequency converter in the frequency converter cabinet, monitor the current module temperature of the frequency converter, and obtain the temperature difference e t between the target module temperature and the current module temperature;

[0060] S2. According to the temperature difference e t , calculate the target opening degree u t of the expansion valve in the heat dissipation module of the frequency converter cabinet through the PID algorithm, and adjust and continuously control the expansion valve according to the opening degree u t so that the module temperature of the frequency converter cabinet converges to the target module temperature;

[0061] S3. Monitor the current module humidity in the frequency converter cabinet, and calculate the dew point temperature according to the current module temperature and the current module humidity;

[0062] S4. Obtain the preset ambient temperature and the preset ambient humidity according to the dew point temperature; when the temperature in the cabinet is greater than the preset ambient temperature, start the fan of the surface cooler in the frequency converter cabinet to perform circulating cooling in the cabinet until the temperature in the cabinet is less than the preset ambient temperature; when the humidity in the cabinet is greater than the preset ambient humidity, dehumidify the condensate inside the surface cooler until the humidity in the cabinet is less than the preset ambient humidity.

[0063] Through the above settings, it is possible to achieve efficient and precise control of the temperature of the internal modules of the frequency converter cabinet, ensure that the modules are within the optimal operating temperature range, and improve the operating stability and efficiency of the equipment. At the same time, by introducing dew point temperature calculation and presetting environmental temperature and humidity thresholds, combined with the coordinated regulation of the surface cooler and the electronic dehumidifier, it is possible to effectively control the humidity inside the cabinet, prevent the risk of condensation of electrical components caused by excessive humidity, and ensure system safety.

[0064] Among them, step S2 specifically includes: according to the target opening u t , control the driver of the expansion valve to output the corresponding opening current, and the refrigerant flow rate in the heat dissipation module of the frequency converter cabinet changes accordingly, so that the module temperature of the frequency converter cabinet converges to the target module temperature. By precisely controlling the opening current of the expansion valve, the adjustment accuracy of the refrigerant flow rate and the system response speed are significantly improved, thereby achieving rapid and effective control of the module temperature of the frequency converter cabinet.

[0065] The PID algorithm formula in step S2 is:

[0066]

[0067] Among them, u t is the target opening; k p is the proportional coefficient; e t is the temperature difference; is the accumulation of errors; dt is the sampling period; det is the slope of the error change; T i is the integral time constant; T d is the differential time constant.

[0068] Furthermore, step S2 also includes: according to the temperature difference e t , divide the temperature regulation into a large temperature difference area, an approaching area, and a fine-tuning area; when the temperature difference e t is in the large temperature difference area, use the method of increasing the proportional coefficient and the integral time constant for control; when the temperature difference e t is in the approaching area, use the method of reducing the proportional coefficient and the integral time constant, and at the same time increasing the differential time coefficient for control; when the temperature difference e t is in the fine-tuning area, use the default proportional coefficient and integral time constant for control.

[0069] Even further, when |e t |≥5℃, it is in the large temperature difference area, and at this time:

[0070]

[0071] k p1 =P K1 *k p ,

[0072] T i1 = P i1 * T i ,

[0073] where k p1 is the proportionality coefficient of the large temperature difference region; P K1 is the proportional amplification coefficient of the large temperature difference region, usually taking 1.5 - 2.5; T i1 is the integral time constant of the large temperature difference region; P i1 is the integral time amplification coefficient of the large temperature difference region, usually taking 1.5 - 2.5;

[0074] When 5°C > |e t | ≥ 2°C, it is in the approaching region, and at this time:

[0075]

[0076] k p2 = P K2 * k p ,

[0077] T i2 = P i2 * T i ,

[0078] T d2 = P d2 * T d ,

[0079] where k p2 is the proportionality coefficient of the approaching region; P K2 is the proportional amplification coefficient of the approaching region, usually taking 1 - 1.5; T i2 is the integral time constant of the approaching region; P i2 is the integral time amplification coefficient of the approaching region, usually taking 0.8 - 1.2; T d2 is the differential time constant of the approaching region; P d2 is the differential time amplification coefficient of the approaching region, usually taking 2 - 2.5;

[0080] When |e t | < 2°C, it is in the fine-tuning region. At this time, the default k p , T i , T d parameters are adopted; meanwhile, to prevent integral saturation, there is:

[0081] When entering the fine-tuning region, e t > 0, and for the first time e t < 0, the error integral accumulation is halved;

[0082] When entering the fine-tuning region, e t < 0, and for the first time e tWhen >0, the error integral is halved.

[0083] By using the temperature difference t The partitioned PID control strategy enables the system to dynamically adjust the control parameters according to the actual working conditions, achieve rapid response in the large temperature difference area, achieve smooth transition in the approaching area, and achieve high-precision control in the fine-tuning area. This control method significantly improves the adjustment efficiency and accuracy of the temperature control system, reduces the overshoot rate and steady-state error during the system adjustment process, and ensures the dynamic stability of the inverter module temperature and the high reliability of the system operation.

[0084] The critical point between the large temperature difference zone and the approach zone is set with a return temperature difference of ±0.5℃; the critical point between the approach zone and the fine-tuning zone is set with a return temperature difference of ±0.5℃. The introduction of the return temperature difference mechanism makes the control algorithm more robust, enhances the system's adaptability to complex working conditions such as environmental changes and temperature disturbances, extends the service life of the expansion valve driver, and ensures the long-term stable operation of the inverter cabinet.

[0085] In step S3, the calculation formula of the dew point temperature is:

[0086]

[0087] Among them, T s is the dew point temperature; T is the current air temperature; RH is the relative humidity.

[0088] In step S4, an electronic dehumidifier and a circulating fan in the cabinet can be used to control the temperature and humidity, specifically including: the electronic dehumidifier reads the target module temperature and current temperature and humidity information of the inverter cabinet, sets the target temperature and humidity, and simultaneously links the circulating fan in the cabinet to dehumidify and cool down, so that the current module temperature and current module humidity of the inverter cabinet converge to the target temperature and humidity.

[0089] Step S2 also includes:

[0090] Assume the inlet temperature of the refrigerant in the heat dissipation module is T in , the target module temperature of the inverter is T a ; Then: When T a -T in >3℃ and T in When the temperature is lower than 40℃, the heat dissipation module is in cooling mode; when T a -T in ≤3℃ or T in When the temperature is ≥40℃, the heat dissipation module is in heating condition;

[0091] When the heat dissipation module is in cooling condition, the expansion valve at the inlet of the heat dissipation module is fully opened, and only the expansion valve at the outlet is controlled;

[0092] When the heat dissipation module is in the heating condition, the expansion valve at the outlet of the heat dissipation module is fully open, and the expansion valve at the inlet is controlled by the PID algorithm. When the heat dissipation module is in the heating condition, the refrigerant inlet temperature is high. If the expansion valve at the outlet is used for throttling at this time, due to the high refrigerant temperature, the temperature of the frequency converter cannot be reduced to the target temperature, and the heat dissipation effect is poor. By fully opening the expansion valve at the outlet and adjusting the expansion valve at the inlet, heat can be taken away faster, enabling the frequency converter to reach the target temperature.

[0093] The above is the description of the embodiments of the present invention. Through the above description of the disclosed embodiments, those skilled in the art can implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel points disclosed herein.

Claims

1. A temperature and humidity control method for a frequency converter cabinet, characterized in that, Includes steps: S1. Set the target module temperature of the frequency converter in the frequency converter cabinet, monitor the current module temperature of the frequency converter, and obtain the temperature difference e between the target module temperature and the current module temperature t ; S2. According to the temperature difference e t , calculate the target opening degree u of the expansion valve in the heat dissipation module of the frequency converter cabinet through the PID algorithm t , and according to the opening degree u t adjust and continuously control the expansion valve so that the module temperature of the frequency converter cabinet converges to the target module temperature; S3, monitoring the current module humidity in the inverter cabinet, and calculating the dew point temperature according to the current module temperature and the current module humidity; S4. Determine the preset ambient temperature and preset ambient humidity based on the dew point temperature; when the temperature inside the cabinet is greater than the preset ambient temperature, start the fan of the surface cooler in the inverter cabinet to circulate and cool the cabinet until the temperature inside the cabinet is less than the preset ambient temperature; when the humidity inside the cabinet is greater than the preset ambient humidity, condense and dehumidify inside the surface cooler until the humidity inside the cabinet is less than the preset ambient humidity.

2. The temperature and humidity control method of the frequency converter cabinet according to claim 1, characterized in that The specific steps of step S2 include: according to the target opening u t , controlling the driver of the expansion valve to output the corresponding opening current, and the refrigerant flow rate in the heat dissipation module of the frequency converter cabinet changes accordingly, so that the module temperature of the frequency converter cabinet converges to the target module temperature.

3. The temperature and humidity control method of the frequency converter cabinet according to claim 1, characterized in that, The PID algorithm formula in step S2 is: Among them, u t is the target opening; k p is the proportionality coefficient; e t is the temperature difference; is the accumulation of errors; dt is the sampling period; det is the slope of the error change; T i is the integral time constant; T d is the derivative time constant.

4. The temperature and humidity control method of the frequency converter cabinet according to claim 3, characterized in that, The step S2 further includes: according to the temperature difference e t , the temperature regulation is divided into a large temperature difference region, an approaching region, and a fine-tuning region; when the temperature difference e t is in the large temperature difference region, a method of increasing the proportionality coefficient and the integral time constant is adopted for control; when the temperature difference e t is in the approaching region, a method of reducing the proportionality coefficient and the integral time constant and simultaneously increasing the differential time coefficient is adopted for control; when the temperature difference e t is in the fine-tuning region, the default proportionality coefficient and integral time constant are adopted for control.

5. The temperature and humidity control method of the frequency converter cabinet as claimed in claim 4, characterized in that: When |e t | ≥ 5°C, it is in the large temperature difference region, and at this time: k p1 = P K1 * k p , T i1 = P i1 * T i , where k p1 is the proportionality coefficient of the large temperature difference region; P K1 is the proportional amplification coefficient of the large temperature difference region, usually taking 1.5 - 2.5; T i1 is the integral time constant of the large temperature difference region; P i1 is the integral time amplification coefficient of the large temperature difference region, usually taking 1.5 - 2.5; When 5°C > |e t | ≥ 2°C, it is in the approaching zone, and at this time: k p2 = P K2 * k p , T i2 = P i2 * T i , T d2 = P d2 * T d , Among them, k p2 is the proportional coefficient of the approaching area; P k2 is the proportional amplification coefficient of the approaching area, usually taking 1 to 1.5; T i2 is the integral time constant of the approaching area; P i2 is the integral time amplification coefficient of the approaching area, usually taking 0.8 to 1.2; T d2 is the differential time constant of the approaching area; P d2 is the differential time amplification coefficient of the approaching area, usually taking 2 to 2.5; When |e t | < 2 °C, it is in the fine-tuning region, and the default k p , T i , T d parameters are adopted; at the same time, to prevent integral saturation, there is: When entering the fine-tuning area, e t > 0, and for the first time e t < 0, the error integral accumulation is halved; When entering the fine-tuning area, e t <0, and for the first time e t > 0, the cumulative error integral is halved.

6. The temperature and humidity control method of the frequency converter cabinet according to claim 4, characterized in that, A return temperature difference of ±0.5°C is set between the critical point of the large temperature difference zone and the approach zone; a return temperature difference of ±0.5°C is set between the critical point of the approach zone and the fine adjustment zone.

7. The temperature and humidity control method of the frequency converter cabinet according to claim 1, wherein In step S3, the calculation formula of the dew point temperature is: where T s is the dew point temperature; T is the current air temperature; and RH is the relative humidity.

8. The temperature and humidity control method of the frequency converter cabinet according to claim 1, characterized in that, In step S4, an electronic dehumidifier and a circulating fan in the cabinet can be used to control the temperature and humidity, which specifically includes: the electronic dehumidifier sets the target temperature and humidity by reading the target module temperature and current temperature and humidity information of the inverter cabinet, and at the same time links the circulating fan in the cabinet to dehumidify and cool down, so that the current module temperature and current module humidity of the inverter cabinet converge to the target temperature and humidity.

9. The temperature and humidity control method of the frequency converter cabinet according to claim 1, characterized in that, The step S2 further comprises: Let the inlet liquid temperature of the refrigerant in the heat dissipation module be T in , and the target module temperature of the frequency converter be T a ; then: when T a - T in > 3°C and T in < 40°C, the heat dissipation module is in the refrigeration mode; when T a - T in ≤ 3°C or T in ≥ 40°C, the heat dissipation module is in the heating mode; When the heat dissipation module is in a refrigeration condition, the expansion valve at the inlet of the heat dissipation module is fully opened, and only the expansion valve at the outlet is controlled; When the heat dissipation module is in a heating condition, the expansion valve at the outlet of the heat dissipation module is fully opened, and the expansion valve at the inlet is controlled by a PID algorithm.

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