Fan frequency conversion energy-saving system and method

Abstract

The invention relates to a frequency conversion and energy conservation system and method for a fan, and the operation frequency of the fan is adjusted according to a judgment result of the opening degree of a valve plate in a most disadvantageous branch by obtaining the opening degree of the valve plate in the most disadvantageous branch. According to the method, the fan frequency can be automatically adjusted only through simple method judgment, the corresponding relation related to complex pipeline system characteristic curves does not need to be calculated, a simpler method is provided for variable-frequency and energy-saving operation of the fan, the requirement that the fan operates at the most reasonable operation frequency is met all the time, and the operation efficiency is improved. The air volume value of each branch is guaranteed, energy is saved, consumption is reduced, operation noise is reduced, the method is simple and convenient to operate, labor management cost can be saved, management efficiency can be improved, and the current situation that field debugging is difficult is effectively reduced; and moreover, when the air volume of the system is insufficient, faults can be quickly eliminated by utilizing detected data, and stable operation of the system is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of ventilation and air conditioning systems, and particularly to a variable-frequency energy-saving system and method for a fan. Background Art

[0002] In a ventilation and air conditioning system, the air volume value in a room is adjusted by an end air valve. The air volume of the main supply fan is frequency-modulated according to the changes in the air volume of each branch to save energy. The main fan usually operates with variable frequency by the constant static pressure method. The principle of the constant static pressure method is to set a static pressure sensor at an appropriate position in the air supply system pipeline to measure the static pressure value at this point. The variable-frequency control of the supply fan takes this static pressure value as the target value, and by adjusting the operating frequency of the fan, the static pressure at the measured position in the pipeline is maintained constant. The constant static pressure method has good energy-saving effects, but the disadvantages are that in the case of a complex pipe network, it is difficult to determine the position and value of the static pressure sensor, and the constant static pressure method is not suitable for systems with filters installed at the end air outlets. In addition, when the system lacks air, it is difficult for the constant static pressure method to judge faults, and it requires a high technical level and expensive on-site measurement equipment to complete fault troubleshooting, and few enterprises can be competent for such debugging work. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the defects in the prior art, so as to provide a variable-frequency energy-saving system and method for a fan.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A variable-frequency energy-saving method for a fan, comprising the following steps:

[0006] Obtain the valve opening degree in the most unfavorable branch;

[0007] If it is determined that the valve opening degree in the most unfavorable branch is within the preset range, the operating frequency of the fan is maintained; if it is determined that the valve opening degree of the most unfavorable branch is the maximum value of the preset range, the fan is controlled to operate at an increased frequency until the valve opening degree of the most unfavorable branch is the minimum value of the preset range.

[0008] Further, it further comprises the following steps:

[0009] Judge the valve opening degree in the most unfavorable branch, control the fan to operate at a decreased frequency until the valve opening degree of the most unfavorable branch is the minimum value of the preset range, and then maintain the fan to operate at the current operating frequency.

[0010] Further, the minimum value is 80%-90%, the maximum value is 90%-100%, and the difference between the maximum value and the minimum value is 10%.

[0011] Further, it further comprises the following steps:

[0012] The fan frequency is increased to the highest frequency and the valve opening of the most unfavorable branch is the maximum value within the preset range, and an alarm is started.

[0013] Further, it also includes the preliminary debugging steps:

[0014] Obtain the maximum total air volume in the main pipeline of the ventilation and air-conditioning system. If it is determined that the maximum total air volume is not within the first set range, a warning message is sent.

[0015] Obtain the maximum total pressure value in the main pipeline of the ventilation and air-conditioning system. If it is determined that the maximum total pressure value is not within the second set range, a warning message is sent.

[0016] Further, when the air valves of each branch are air control units, the preliminary debugging steps also include: closing all air control units, detecting the total pressure value in the main pipeline and recording it as the maximum total pressure value; opening all air control units, and when the valve openings of all branches reach 100%, detecting the air volume value in the main pipeline and recording it as the maximum total air volume.

[0017] When the air valve of the most unfavorable branch is an air control unit and the air valves of other branches are constant air volume valves, the preliminary debugging steps also include: closing the main pipeline shut-off valve at the outlet of the fan in the ventilation and air-conditioning system, detecting the total pressure value in the main pipeline and recording it as the maximum total pressure value; opening the main pipeline shut-off valve at the outlet of the fan in the ventilation and air-conditioning system, and when the valve opening of the most unfavorable branch reaches 100%, detecting the air volume value in the main pipeline and recording it as the maximum total air volume.

[0018] When the air valve of the most unfavorable branch is an air control unit and the air valves of other branches are manual valves, the preliminary debugging steps also include: closing the air valves of all branches, detecting the total pressure value in the main pipeline and recording it as the maximum total pressure value; opening the air valves of all branches, and when the valve openings of all air valves reach 100%, detecting the air volume value in the main pipeline and recording it as the maximum total air volume.

[0019] Further, the preliminary debugging steps also include:

[0020] When the maximum total air volume is within the first set range and the maximum total pressure value is within the second set range, determine whether the air leakage volume is within the third set range;

[0021] If so, the debugging is qualified;

[0022] If not, start the alarm for troubleshooting.

[0023] To achieve the above object, the present invention also adopts the following technical solutions:

[0024] A variable-frequency energy-saving system for a fan, which is used in cooperation with a ventilation and air-conditioning system. The variable-frequency energy-saving system for a fan includes a wind control unit and a controller. The wind control unit is arranged at the end of the most unfavorable branch and is used for detecting the opening degree of the valve plate in the branch where it is located.

[0025] The controller is electrically connected to the wind control unit and is used for obtaining the opening degree of the valve plate in the most unfavorable branch. If it is judged that the opening degree of the valve plate in the most unfavorable branch is within a preset range, the operating frequency of the fan of the ventilation and air-conditioning system is maintained; if it is judged that the opening degree of the valve plate in the most unfavorable branch is the maximum value of the preset range, the fan of the ventilation and air-conditioning system is controlled to operate at an increased frequency until the opening degree of the valve plate in the most unfavorable branch is the minimum value of the preset range.

[0026] Furthermore, the system further includes a wind measurement module. The wind measurement module is communicatively connected to the controller and is used for measuring in real time the air volume value and the total pressure value in the main pipeline at the outlet of the fan in the ventilation and air-conditioning system and sending the air volume value and the total pressure value to the controller.

[0027] In summary, compared with the prior art, the present invention has at least the following beneficial effects:

[0028] The present invention relates to a variable-frequency energy-saving system and method for a fan. By obtaining the opening degree of the valve plate in the most unfavorable branch and adjusting the operating frequency of the fan according to the judgment result of the opening degree of the valve plate in the most unfavorable branch. Only through a simple method of judgment can the fan frequency be automatically adjusted, without calculating the corresponding relationship related to the complex characteristic curve of the pipeline system, providing a simpler method for the variable-frequency energy-saving operation of the fan, always meeting the fan to operate at the most reasonable operating frequency, ensuring the air volume value of each branch while saving energy and reducing consumption and reducing the operating noise. The method is simple and convenient to operate, can save the labor management cost, improve the management efficiency, and effectively reduce the current situation of difficult on-site debugging; and when the air volume of the system is insufficient, the detected data can be used to quickly troubleshoot faults and ensure the stable operation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required to be used in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to these drawings without creative efforts.

[0030] Figure 1 It is a schematic structural diagram of a variable-frequency energy-saving system for a fan provided in an embodiment of the present invention.

[0031] Figure 2 It is a schematic structural diagram of a variable-frequency energy-saving system for a fan provided in another embodiment of the present invention.

[0032] Figure 3 This is a schematic structural diagram of a variable-frequency energy-saving system for a fan provided in another embodiment of the present invention.

[0033] Figure 4 This is a frequency-resistance operation curve graph of a fan provided in an embodiment of the present invention.

[0034] Description of reference numerals:

[0035] 1. Fan; 11. Frequency converter;

[0036] 2. Wind measurement module;

[0037] 3. Wind control unit; 4. Controller; 5. Main pipeline; 6. Branch pipeline; 61. Most unfavorable branch pipeline; 7. Constant air volume valve; 8. Manual valve; 9. Control panel. Specific implementation manners

[0038] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of 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.

[0039] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0040] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0041] In the prior art, in order to achieve the goal of energy conservation in the ventilation and air conditioning system, one of the disclosed technologies is to test, mark and set calibration values for air valves, and based on the corresponding relationship between the calibration values and the initial air volume, form a relationship curve between the calibration values and the initial air volume, so that the set value of the air valve can be based on the corresponding relationship between the actual air supply volume and the calibration value, and by adjusting the opening degree of the valve plate, make the actual air supply volume match the set value. Although adjusting the opening degree of the valve plate through the control logic between air valves can solve the air volume error problem caused by the blind adjustment of the air volume device, realize the intelligent variable fresh air volume operation of the all-air central air conditioning, and meet the fresh air demand in the room while achieving the energy conservation requirement. However, for the terminal air volume measured by this method and the total air volume of the valve plate feedback and summation, corresponding control relationship curves need to be made with the actual operation curve of the fan. The establishment and debugging of this corresponding relationship require technicians to have a high technical level and practical experience, and the technical requirement threshold is too high. In most projects, the fan frequency conversion requirement is difficult to be successfully implemented in actual projects; or, another disclosed technology usually requires the fan to operate at a relatively high static pressure. As the air filter of the ventilation and air conditioning system gradually clogs, the regulating valves of each branch will automatically gradually increase their own valve plate opening degrees to reduce the resistance in order to maintain the resistance balance and air volume constancy of the ventilation and air conditioning system. In this case, although it avoids the air volume imbalance and the manual repeated adjustment and balancing process brought by using the regulating valve, the fan has been operating at a relatively high static pressure, which will waste more energy consumption, and the relatively large operating resistance will generate relatively large noise.

[0042] Based on the above problems, the present invention provides a fan frequency conversion energy conservation method, including the following steps:

[0043] Obtain the opening degree of the valve plate in the most unfavorable branch;

[0044] If it is determined that the opening degree of the valve plate in the most unfavorable branch is within the preset range, then maintain the fan operation frequency; if it is determined that the opening degree of the valve plate in the most unfavorable branch is the maximum value of the preset range, then control the fan to operate at an increased frequency until the opening degree of the valve plate in the most unfavorable branch is the minimum value of the preset range.

[0045] In a ventilation and air conditioning system, usually a main pipeline connects multiple branch pipelines to convey air volume. The fan is installed in the main pipeline and transfers the air volume to the main pipeline, and then is distributed to different areas or rooms through each branch pipeline. When the fan variable frequency energy-saving method is applied to the ventilation and air conditioning system, there are two definition methods for the most unfavorable branch pipeline. One is to detect the valve plate opening degrees of all branch pipelines through a wind control unit and select one or more branch pipelines with the largest valve plate opening degrees as the most unfavorable branch pipelines; the other is to find out one or more branch pipelines with the largest cumulative resistance loss and friction loss based on pre-analysis and detection and define them as the most unfavorable branch pipelines. Generally, the branch pipeline farthest from the fan is selected as the most unfavorable branch pipeline. In this application, it is necessary to obtain the valve plate opening degree of the most unfavorable branch pipeline because when the fan conveys air volume, the air flow in the pipeline will encounter energy losses caused by friction and local resistance, and the cumulative resistance loss of the most unfavorable branch pipeline is the largest. Therefore, when the valve plate opening degree of the most unfavorable branch pipeline can meet the requirements of the actual air output, the other branch pipelines will surely be able to meet the requirements of the actual air output as well.

[0046] Specifically, when the system is in the initial stage of use, the fan is maintained at the operating frequency that makes the valve plate opening degree of the most unfavorable branch pipeline the minimum value and operates at a fixed frequency. After the system has been used for a period of time, situations such as the filter gradually becoming clogged and its performance deteriorating may occur. At this time, the valve plate opening degree of the most unfavorable branch pipeline gradually tends to the maximum value to reduce the resistance brought by the valve plate, thereby stabilizing the air volume in the branch pipeline until the valve plate opening degree reaches the maximum value; when the valve plate has been opened to the maximum value, it indicates that only adjusting the valve plate opening degree can no longer meet the requirements of the branch pipeline air volume. At this time, by increasing the operating frequency of the fan, the air output of the fan is increased, and for energy conservation, the valve plate opening degree of the most unfavorable branch pipeline simultaneously tends to the minimum value until it reaches the minimum value, and the fan operates at a fixed frequency at the operating frequency when the valve plate opening degree of the most unfavorable branch pipeline reaches the minimum value, and the above steps are cycled. Based on the dynamic change of the valve plate opening degree of the most unfavorable branch pipeline and the dynamic adjustment of the operating frequency of the fan, the fan always operates at the most energy-saving operating frequency, improving the economy of the system, and effectively avoiding frequent adjustment of the operating frequency of the fan, reducing the start-stop times and operating pressure of the fan, thereby reducing the wear of the fan.

[0047] Therefore, this application automatically adjusts the variable frequency energy-saving operation of the fan according to the judgment of the valve plate opening degree of the most unfavorable branch pipeline, provides a simpler method for the variable frequency energy-saving operation of the fan, reduces the excessive requirements for technical personnel during the construction and commissioning process, is convenient for installation and commissioning, effectively reduces the current situation of difficult on-site commissioning, and the operation becomes digital, visual, and intelligent, always meeting the fan's operation at the most reasonable operating frequency, ensuring both the air volume values of each branch pipeline and energy conservation and consumption reduction, and a reasonable valve plate opening degree can reduce resistance and reduce operating noise.

[0048] It should be noted that there is a certain corresponding relationship between the valve opening and the actual air output. The larger the valve opening, the less the resistance of the air output flow through the valve, and the smaller the actual energy loss of the air output. However, it may cause unnecessary waste due to the actual air output exceeding the user's demand; while the smaller the valve opening, the greater the resistance of the air output flow through the valve, the greater the actual air volume loss, and the increase in the energy consumption of the fan. Therefore, a reasonable preset range needs to be set for the valve opening so that it can be adjusted within the reasonable preset range to meet both the user's usage requirements and achieve the purpose of energy saving. The preset range has end values, namely the minimum value and the maximum value. The minimum value is preferably higher than 50% to avoid the negative impact of excessive resistance on the system performance. The specific value of the preset range should be set according to the actual usage situation, considering the demand changes in different seasons and regions and the overall efficiency of the system, etc., and will not be limited here.

[0049] In some embodiments of the present invention, when the system is just started, in order for the fan to quickly reach the air supply demand, the operating frequency will be relatively high at this time. The valve opening in the most unfavorable branch is judged, and the fan is controlled to run at a reduced frequency until the valve opening in the most unfavorable branch is the minimum value of the preset range, and then the fan is maintained to run at the current operating frequency to avoid unnecessary energy consumption waste caused by the relatively high operating frequency of the fan.

[0050] In some embodiments of the present invention, the minimum value is 80%-90%, the maximum value is 90%-100%, and the difference between the maximum value and the minimum value is 10%. The smaller difference can enable the system to achieve more accurate air volume control, ensure that there will be no large fluctuations in the air volume in the branch when the valve opening changes, and improve the operating stability of the system.

[0051] Preferably, as shown in the appendix Figure 4 The minimum value of the preset range is 90% and the maximum value is 100%. That is, when the system is in the initial stage of use, the fan is maintained at the operating frequency when the valve of the most unfavorable branch is at an opening of 90% and operates at a fixed frequency. After the system has been used for a period of time, due to possible situations such as the gradual blockage and performance degradation of the filter, the valve opening of the most unfavorable branch gradually increases until it reaches 100%. The fan is controlled to run at an increased frequency, and at the same time, the valve opening of the most unfavorable branch gradually decreases until it reaches 90%, and the fan is controlled to run at a fixed frequency, and the above steps are cycled. It should be noted that the minimum value of 90% and the maximum value of 100% are the most preferred values of this application, but the minimum value and the maximum value can be set according to the actual application requirements and are not limited to the range listed in this application.

[0052] In some embodiments of the present invention, as shown in the appendix Figure 4As shown, after the system has been used for a period of time, there may be a situation where the fan frequency is increased to the highest frequency and the valve opening of the most unfavorable branch reaches the maximum value. This indicates that as the usage time of the ventilation and air conditioning system increases, impurities such as dust and particulate matter in the air will gradually accumulate on the filter, resulting in severe blockage. The blocked filter will cause at least a pressure loss of 200 - 300 Pa, increasing the resistance of the ventilation and air conditioning system and preventing the fan from providing sufficient air volume. Therefore, the following steps are also included: the fan frequency is increased to the highest frequency and the valve opening of the most unfavorable branch is at the maximum value within the preset range, and when the alarm point is reached, the alarm is activated; to prompt the maintenance personnel to replace or clean the filter in a timely manner.

[0053] In some embodiments of the present invention, before the ventilation and air conditioning system is handed over to the user, there is also a commissioning stage for the staff at the initial installation. Therefore, the following pre - commissioning steps are also included: obtain the maximum total air volume in the main pipeline of the ventilation and air conditioning system, and if it is determined that the maximum total air volume is not within the first set range, an early warning message is sent; obtain the maximum total pressure value in the main pipeline of the ventilation and air conditioning system, and if it is determined that the maximum total pressure value is not within the second set range, an early warning message is sent. By measuring the maximum total air volume value and the maximum total pressure value of the main pipeline, it is judged whether they are within the set range to ensure the rationality of the design of the ventilation and air conditioning system. When the maximum total air volume exceeds the first set range, it may mean that there is a potential overload risk in the system, which may lead to system damage. Or, when the maximum total pressure value exceeds the second set range, it may cause too high pressure in the system, which may affect the sealing performance of the system. Therefore, when any one is not within the set range, an early warning message needs to be sent to enable the staff to conduct fault troubleshooting. After troubleshooting and repair, commissioning is carried out again, and only after passing can it be put into use. It should be noted that the first set range and the second set range are set according to the actual usage situation, for example, considering the demand changes in different seasons and regions and the overall efficiency of the system, etc., and are not limited here.

[0054] It should be noted that the measurement process of the maximum total pressure value is to adjust the valve opening of all branches to 0%, so that no air volume flows out of the branches. Therefore, the fan does not need to overcome any local resistance in the branches. Therefore, the total pressure value measured at this time is the maximum total pressure value. Further, the measurement of the maximum total air volume can be carried out when the valve opening of all branches reaches 100% and the system is in the operating state of the maximum air volume demand under the preset conditions. This reflects the most extreme situation that may be encountered in actual use. Therefore, the total air volume measured at this time is the maximum total air volume. For example, when all branches require the maximum ventilation volume at the same time, testing the maximum total air volume can evaluate whether the selected fan can provide sufficient air volume under the maximum demand conditions. If the measured maximum total air volume exceeds the design requirements, the system should trigger an alarm to prompt the operator to conduct troubleshooting.

[0055] In some embodiments of the present invention, when the air valves of each branch are air control units, the preliminary debugging steps further include: closing all air control units, detecting the total pressure value in the main pipeline and recording it as the maximum total pressure value; opening all air control units, and when the valve plate openings of all branches reach 100%, detecting the air volume value in the main pipeline and recording it as the maximum total air volume;

[0056] When the air valve of the most unfavorable branch is an air control unit and the air valves of other branches are constant air volume valves, the working air volume is set for all constant air volume valves before leaving the factory, and the working air volume is set for the air control unit. The preliminary debugging steps further include: closing the main pipeline shut-off valve at the outlet of the fan in the ventilation and air conditioning system, detecting the total pressure value in the main pipeline and recording it as the maximum total pressure value; opening the main pipeline shut-off valve at the outlet of the fan in the ventilation and air conditioning system, and when the valve plate opening of the most unfavorable branch reaches 100%, detecting the air volume value in the main pipeline and recording it as the maximum total air volume;

[0057] When the air valve of the most unfavorable branch is an air control unit and the air valves of other branches are manual valves, the preliminary debugging steps further include: closing the air valves of all branches, detecting the total pressure value in the main pipeline and recording it as the maximum total pressure value; opening the air valves of all branches, and when the valve plate openings of all air valves reach 100%, detecting the air volume value in the main pipeline and recording it as the maximum total air volume.

[0058] In some embodiments of the present invention, the preliminary debugging steps further include: when the maximum total air volume is within the first set range and the maximum total pressure value is within the second set range, determining whether the air leakage volume is within the third set range; if so, the debugging is qualified; if not, start an alarm for troubleshooting.

[0059] It should be noted that when the air valves of each branch are air control units, the air leakage volume is calculated by the system intelligently at this time; when the air valve of the most unfavorable branch is an air control unit and the air valves of other branches are constant air volume valves, the total air volume of each branch pipe and the air leakage volume are calculated manually at this time; when the air valve of the most unfavorable branch is an air control unit and the air valves of other branches are manual valves, the total air volume of each branch pipe and the air leakage volume are calculated manually at this time.

[0060] Furthermore, the calculation of the air leakage volume is obtained by comparing the measured air volume value in the main pipeline with the total air volume value of all branches. The specific formula is as follows:

[0061]

[0062] Preferably, the third set range is less than or equal to 10%. When the detected air leakage exceeds 10%, it is considered that there is a relatively serious air leakage problem in the system, and an alarm needs to be activated and fault troubleshooting is required. More preferably, since even if the initial commissioning is qualified, over time, the air leakage volume of the system may change due to factors such as pipeline aging. Therefore, each time the ventilation and air-conditioning system operates, it is necessary to detect whether the air leakage volume is within the third set range to ensure that the ventilation and air-conditioning system always operates within the optimal performance range and further reduce energy consumption.

[0063] In addition to the above-mentioned fan variable-frequency energy-saving method, the present invention also provides a fan variable-frequency energy-saving system operating based on the above method. The system described below can be mutually corresponding and referred to the method described above.

[0064] As shown in the Figure 1 accompanying drawings, for cooperating with the ventilation and air-conditioning system, the fan variable-frequency energy-saving system includes an air control unit 3 and a controller 4.

[0065] The air control unit 3 is at least arranged at the end of the most unfavorable branch 61 for detecting the valve opening of the branch 6 where it is located.

[0066] The controller 4 is electrically connected to the air control unit 3 for obtaining the valve opening of the most unfavorable branch 61 and judging that if the valve opening of the most unfavorable branch 61 is within the preset range, the operating frequency of the fan of the ventilation and air-conditioning system is maintained; if the valve opening of the most unfavorable branch 61 is the maximum value within the preset range, the fan 1 of the ventilation and air-conditioning system is controlled to operate at an increased frequency until the valve opening of the most unfavorable branch 61 is the minimum value within the preset range.

[0067] Specifically, by arranging at least the air control unit 3 in the original ventilation and air-conditioning system in the most unfavorable branch 61 and cooperating with the controller 4, the fan 1 is connected with an inverter 11, and the inverter 11 is communicatively connected with the controller 4 to determine whether to adjust the operating frequency of the fan 1. There is no need to adjust the operating frequency of the fan 1 according to the corresponding relationship of the complex pipeline system characteristic curve, and it always meets the requirement that the fan 1 operates at the most reasonable operating frequency, which not only ensures the air volume value of each branch 6 but also saves energy and reduces consumption and operating noise. The method is simple and convenient to operate, can save labor management costs, improve management efficiency, and effectively reduce the current situation of difficult on-site commissioning. In addition, when the air volume of the system is insufficient, the detected data can be used to quickly troubleshoot faults and ensure the stable operation of the system.

[0068] Furthermore, the air control unit 3 can have the function of feeding back the air volume value and the valve opening, and can choose to implement one of the air volume value control or the valve opening control, or only have the function of feeding back the valve opening. Also, the variable air volume valve or other air valves on the market that can feed back the valve opening also belong to the air control unit 3 of the present application. Even further, in the present application, the main function of the air control unit 3 is to detect and feedback the valve opening of the branch 6 where it is located.

[0069] It should be noted that there are various implementation methods for the system. In addition to the above control method using the usage method, other implementation methods can also be used. For example, each air control unit 3 is connected to the controller 4 through a circuit, and the minimum electrical signal and the maximum electrical signal are set artificially. The minimum electrical signal corresponds to the electrical signal when the valve opening of the most unfavorable branch 61 is the minimum value within the preset range, and the maximum electrical signal corresponds to the electrical signal when the valve opening of the most unfavorable branch 61 is the maximum value within the preset range. When the circuit emits the minimum electrical signal, the controller 4 controls the operating frequency of the fan 1 based on the received minimum electrical signal and maximum electrical signal. For example, the minimum value of the preset range is 90% and the maximum value is 100%. When the minimum electrical signal is triggered, the system detects that the valve opening of the most unfavorable branch 61 is 90%, and when the maximum electrical signal is triggered, the system detects that the valve opening of the most unfavorable branch 61 is 100%. The controller 4 controls the operating frequency of the fan 1 based on the received minimum electrical signal and maximum electrical signal. Of course, it is not limited to the above circuit logic control, and it can be other circuit control logics, which are not defined here.

[0070] In some embodiments of the present invention, the system further includes a wind measurement module 2. The wind measurement module 2 is communicatively connected to the controller 4. The wind measurement module 2 is used to measure the air volume value and total pressure value in the main pipeline 5 at the outlet of the fan 1 in the ventilation and air-conditioning system in real time, and send the air volume value and total pressure value to the controller 4 to cooperate with the system for pre-commissioning work. Preferably, the specific structure of the wind measurement module 2 of the present application is the structure of the controller 4 for measuring dynamic pressure, total pressure and static pressure in the publication number CN220911626U. Of course, those skilled in the art can select and adjust according to the actual application situation and product requirements, etc. The wind measurement module 2 can also be replaced with any measurement device for measuring air volume and duct pressure, which is not defined here.

[0071] In some embodiments of the present invention, as shown in the attached Figure 1 figure, the ventilation and air-conditioning system is a variable air volume system, and air control units 3 are provided on all branches. The air control unit 3 can intelligently detect the valve opening of any branch, and the controller 4 determines and selects the branch 6 with the largest valve opening as the most unfavorable branch 61.

[0072] In some embodiments of the present invention, as shown in the attached Figure 2 figure, the ventilation and air-conditioning system is a constant air volume system, the air valves of each branch are constant air volume valves 7, and only the air valve of the most unfavorable branch 61 is the air control unit 3. Through preliminary calculation and analysis, a branch 6 farthest from the fan 1 is selected as the most unfavorable branch 61.

[0073] Furthermore, taking a common constant air volume ventilation and air-conditioning system as an example, the operating parameters of the system are: the system design required air volume is 10000m 3 / h, the system design resistance is 500 Pa, among which the pipeline system resistance is 180 Pa, the final resistance of the filter is 300 Pa, and the selected model of the air handling unit fan is 10000 m 3 / h, the total pressure of the fan is 550 Pa, and the initial resistance of the primary filter and the medium - efficiency filter together is 150 Pa. It is calculated that the fixed - frequency operation energy consumption of the system per hour is 2073 W. For the constant - volume air - conditioning system of general ventilation that cooperates with the fan variable - frequency energy - saving system in this application, the variable - frequency energy consumption per hour is 1500 W. The energy consumption of the constant - volume air - conditioning system of general ventilation that does not cooperate with the fan variable - frequency energy - saving system in this application increases by 35.8%. The annual energy - saving amount of the constant - volume air - conditioning system of general ventilation that cooperates with the fan variable - frequency energy - saving system in this application can reach 4639.68 KWh. Further, taking the constant - volume air - conditioning system of purification ventilation as an example, the operating parameters of the system are: the designed demand air volume of the system is 10000 m 3 / h, the system design resistance is 900 Pa, among which the pipeline system resistance is 180 Pa, the final resistance of the filter is 700 Pa, and the selected model of the air handling unit fan is 10000 m 3 / h, the total pressure of the fan is 960 Pa, the initial resistance of the primary filter and the medium - efficiency filter together is 150 Pa, and the initial resistance of the high - efficiency filter is 200 Pa. It is calculated that the fixed - frequency operation energy consumption of the system per hour is 3556 W. For the constant - volume air - conditioning system of clean air ventilation that cooperates with the fan variable - frequency energy - saving system in this application, the variable - frequency energy consumption per hour is 2611 W. The energy consumption of the constant - volume air - conditioning system of clean air ventilation that does not cooperate with the fan variable - frequency energy - saving system in this application increases by 36.2%. The annual energy - saving amount of the constant - volume air - conditioning system of clean air ventilation that cooperates with the fan variable - frequency energy - saving system in this application can reach 8164.8 KWh.

[0074] In some embodiments of the present invention, as shown in the attached Figure 3 figure, the air valves of each branch are manual valves 8, and only the air valve of the most unfavorable branch 61 is the air - control unit 3. Through preliminary calculation and analysis, one branch 6 farthest from the fan 1 is selected and defined as the most unfavorable branch 61.

[0075] It should be noted that the remaining branches 6 of the above - mentioned three systems can also be partially provided with the air - control unit 3, and the number of branches 6 provided with the air - control unit 3 can be set according to the actual use situation, which is not limited here.

[0076] In some embodiments of the present invention, the ventilation and air - conditioning system further includes a filter, and the filter is arranged at the air outlet of the fan 1. It should be noted that when the filter is severely blocked, it will cause at least a pressure loss of 200 - 300 Pa, increasing the resistance of the ventilation and air - conditioning system, so that the fan 1 needs to increase the operating frequency to maintain the required air volume, greatly increasing the energy consumption. Therefore, when the fan 1 has run to the highest frequency and the valve disc of the most unfavorable branch 61 has been opened to the maximum, the filter needs to be replaced at this time.

[0077] In some embodiments of the present invention, the air control unit 3 includes a measuring device, a control device and an actuating device. The measuring device is used to measure the air volume value and the valve plate opening degree of the branch line 6 in real time. The actuating device is used to control the valve plate opening degree of the air control unit. The control device is electrically connected to the measuring device and the actuating device; the controller 4 is electrically connected to the control device of the air control unit 3, and obtains the valve plate opening degree of the air control unit 3 in real time, and based on this, adjusts the fan 1 to operate at the most energy-saving operating frequency.

[0078] In some embodiments of the present invention, an alarm device is further included, which is used to receive the alarm instruction sent by the controller 4 and send out a signal for alarm. For example, when the maximum total air volume or the maximum total pressure value of the main pipeline 5 measured during the debugging stage does not meet the set value, the air leakage amount obtained based on the sum of the air volume values of each branch line 6 exceeds the set value, or the air volume data cannot be detected due to a fault in the air volume measuring module 2 or the air control unit 3, etc., the controller 4 issues an alarm instruction, and the alarm device gives an alarm, and the staff conducts fault troubleshooting.

[0079] In some embodiments of the present invention, a control panel 9 is further included. The controller 4 is electrically connected to the control panel 9, so that the air volume value and the total pressure value obtained by the air volume measuring module 2, the valve plate opening degree of the branch line where the air control unit 3 is located, the operating frequency of the fan 1, etc. are all displayed on the display screen of the control panel 9, so that the users and maintenance personnel can directly control and observe the data through the control panel 9, so as to quickly observe whether there is any abnormality in the system. Preferably, the display screen of the control panel 9 has a debugging key and an operation key, so that the users or maintenance personnel can quickly switch to different modes of the system.

[0080] The above embodiments are only the preferred embodiments of the present invention, and cannot be used to limit the scope of protection of the present invention. Any non-substantive changes and substitutions made by those skilled in the art based on the present invention belong to the scope of protection required by the present invention.

Claims

1. A frequency conversion energy-saving method for a fan, characterized in that, It includes the following steps: Obtain the valve opening degree in the most unfavorable branch; If it is judged that the valve opening degree in the most unfavorable branch is within the preset range, maintain the operating frequency of the fan; if it is judged that the valve opening degree of the most unfavorable branch is the maximum value of the preset range, control the fan to operate at an increased frequency until the valve opening degree of the most unfavorable branch is the minimum value of the preset range.

2. The variable-frequency energy-saving method of the fan according to claim 1, wherein It also includes the following steps: Judge the valve opening degree in the most unfavorable branch, control the fan to operate at a decreased frequency until the valve opening degree of the most unfavorable branch is the minimum value of the preset range, and then maintain the fan to operate at the current operating frequency.

3. The variable-frequency energy-saving method of a fan according to claim 1 or 2, characterized in that, The minimum value is 80%-90%, the maximum value is 90%-100%, and the difference between the maximum value and the minimum value is 10%.

4. The variable-frequency energy-saving method for a fan according to claim 1 or 2, characterized in that, It also includes the following steps: When the fan increases the frequency to the highest frequency and the valve opening degree of the most unfavorable branch is the maximum value of the preset range, start the alarm.

5. The variable-frequency energy-saving method of the fan according to claim 1, characterized in that, It also includes the pre-commissioning steps: Obtain the maximum total air volume in the main pipeline of the ventilation and air-conditioning system. If it is judged that the maximum total air volume is not within the first set range, send a warning message; Obtain the maximum total pressure value in the main pipeline of the ventilation and air-conditioning system. If it is judged that the maximum total pressure value is not within the second set range, send a warning message.

6. The fan variable-frequency energy-saving method according to claim 5, characterized in that When the air valves of each branch are air control units, the pre-commissioning steps further include: closing all air control units, detecting the total pressure value in the main pipeline and recording it as the maximum total pressure value; opening all air control units, and when the valve opening degrees of all branches reach 100%, detecting the air volume value in the main pipeline and recording it as the maximum total air volume; When the air valve of the most unfavorable branch is an air control unit and the air valves of other branches are constant air volume valves, the pre-commissioning steps further include: closing the main pipeline shut-off valve at the outlet of the fan in the ventilation and air-conditioning system, detecting the total pressure value in the main pipeline and recording it as the maximum total pressure value; opening the main pipeline shut-off valve at the outlet of the fan in the ventilation and air-conditioning system, and when the valve opening degree of the most unfavorable branch reaches 100%, detecting the air volume value in the main pipeline and recording it as the maximum total air volume; When the air valve of the most unfavorable branch is an air control unit and the air valves of other branches are manual valves, the pre-commissioning steps further include: closing the air valves of all branches, detecting the total pressure value in the main pipeline and recording it as the maximum total pressure value; opening the air valves of all branches, and when the valve opening degrees of all air valves reach 100%, detecting the air volume value in the main pipeline and recording it as the maximum total air volume.

7. The method for frequency conversion energy saving of a fan according to claim 5, characterized in that, The pre-commissioning steps further include: When the maximum total air volume is within the first set range and the maximum total pressure value is within the second set range, judge whether the air leakage volume is within the third set range; If so, the commissioning is qualified; If not, start the alarm for troubleshooting.

8. A variable-frequency energy-saving system for a fan, characterized in that, For cooperating with the ventilation and air-conditioning system, the fan variable-frequency energy-saving system includes an air control unit and a controller. The air control unit is arranged at the end of the most unfavorable branch and is used to detect the valve opening degree in the branch where it is located; The controller is electrically connected to the air control unit, and is used to obtain the valve opening degree in the most unfavorable branch, and if it is judged that the valve opening degree of the most unfavorable branch is within the preset range, the operating frequency of the fan of the ventilation and air-conditioning system is maintained; if it is judged that the valve opening degree of the most unfavorable branch is the maximum value of the preset range, the fan of the ventilation and air-conditioning system is controlled to operate with an increased frequency until the valve opening degree of the most unfavorable branch is the minimum value of the preset range.

9. The variable-frequency energy-saving system of a fan according to claim 8, wherein It further includes a wind measurement module, the wind measurement module is communicatively connected to the controller, and the wind measurement module is used to measure in real time the air volume value and the total pressure value in the main pipeline at the outlet of the fan in the ventilation and air-conditioning system, and send the air volume value and the total pressure value to the controller.

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