Anti-surge and anti-backflow control method for magnetic suspension blower

Abstract

The invention provides an anti-surge and anti-backflow control method for a magnetic suspension air blower, and belongs to the technical field of air blowers. The anti-surge and anti-backflow control method for the magnetic suspension air blower comprises the steps that an electric check valve is arranged in an air supply pipeline outside fan equipment, and the electric check valve is electrically connected with a system corresponding to the magnetic suspension air blower; a plurality of rotating speed gears are divided in a low-speed operation interval of the fan, different rotating speed gears correspond to different opening degrees of the electric check valve, and the larger the rotating speed is, the larger the opening degree of the corresponding electric check valve is; the fan enters a low-speed operation interval after being started, the rotating speed gear of the motor is adjusted step by step from small to large, and the system correspondingly adjusts the opening degree of the electric check valve according to the rotating speed gear where the motor is located; and after the fan enters the high-speed operation interval, the electric check valve is fully opened, and the speed is directly increased to the target set rotating speed. According to the anti-surge and anti-backflow control method for the magnetic suspension air blower, the surge inducement of sudden pressure rise caused by closing of the electric check valve is avoided.

Description

Technical Field

[0001] This invention belongs to the field of blower technology, specifically relating to a method for preventing surge and backflow control in a magnetic levitation blower. Background Technology

[0002] Magnetic levitation blowers have a check valve installed in the air supply duct near the blower equipment. This check valve is typically mechanical and prevents gas from flowing back into the blower equipment when the blower is not running. Additionally, since the gas supplied by the magnetic levitation blower is generally air, an air vent valve is also installed at the blower's outlet.

[0003] Before the blower starts, the mechanical check valve is closed. After the blower starts but before reaching its set speed, the system corresponding to the magnetic levitation blower controls the vent valve to open, allowing air to be discharged outside the equipment through the vent valve. This prevents blower surge when the check valve is closed; at this time, the check valve remains closed, and no air is being supplied to the pipeline. Once the blower reaches its set speed, the system controls the vent valve to close rapidly. At this point, the pressure in the blower outlet pipeline rises sharply. When the pressure exceeds the spring pressure in the mechanical check valve, the check valve opens instantaneously, and gas begins to be continuously supplied to the pipeline.

[0004] In specific operating applications of explosion-proof magnetic levitation blowers, the gas being transported is no longer air, but a flammable gas, so venting through the vent valve is not permitted. However, after removing the vent valve, because the mechanical check valve is closed before the blower starts, the air pressure in the pipeline cannot open the check valve before the blower reaches the predetermined speed after starting, which may cause the blower to falsely trigger surge protection during speed-up. Summary of the Invention

[0005] This invention provides a method for controlling surge and backflow prevention in a magnetic levitation blower, aiming to solve the technical problem that existing mechanical check valves cannot open in time during the operation of a blower conveying combustible gas in order to prevent gas from flowing back into the blower side, thus accidentally triggering surge protection during the speed-up process.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: to provide a method for controlling surge and backflow prevention in a magnetic levitation blower, comprising: An electric check valve is installed in the air supply duct outside the blower equipment, and the electric check valve is electrically connected to the corresponding system of the magnetic levitation blower. Before the fan is started, the electric check valve is in the closed position; The low-speed operating range of the fan is divided into multiple speed levels. The opening degree of the electric check valve is different for different speed levels, and the higher the speed, the larger the opening degree of the electric check valve. After the fan starts, it enters the low-speed operating range. The motor speed is adjusted step by step from small to large. The system adjusts the opening of the electric check valve according to the motor speed. Once the fan enters the high-speed operating range, the electric check valve opens fully and the speed increases directly to the target set speed.

[0007] In one possible implementation, multiple speed ranges are N1, N2, ..., Nn, and the opening degree of the electric check valve corresponding to each speed range is D1, D2, ..., Dn. When the system adjusts the opening of the electric check valve, different openings correspond to different safety margins d1, d2, ..., dn; That is, when the speed setting is Nx, the actual opening degree of the corresponding electric check valve is Dx+dx; Where 1≤x≤n.

[0008] In one possible implementation, the safety margins d1, d2, ..., dn take different values, and d1 < d2 < ... < dn.

[0009] In one possible implementation, the low-speed operating range is divided into four speed levels, and the safety margins corresponding to different opening degrees of the electric check valve are d1, d2, d3, and d4, where d1 is 2%, d2 is 3%, d3 is 5%, and d4 is 8%.

[0010] In one possible implementation, the low-speed operating range is 0 to 2000 rpm, and the high-speed operating range is 2000 rpm to the target set speed.

[0011] In one possible implementation, the low-speed operating range is divided into four speed gears: N1, N2, N3, and N4. The speed gear N1 corresponds to a speed of 0–500 rpm, the speed gear N2 corresponds to a speed of 500–1000 rpm, the speed gear N3 corresponds to a speed of 1000–1500 rpm, and the speed gear N4 corresponds to a speed of 1500–2000 rpm.

[0012] One possible implementation also includes: The system monitors the outlet pressure of the fan at different speed levels and compares the outlet pressure with the surge pressure value; When the outlet pressure is higher than the surge pressure value, increase the opening degree of the current electric check valve.

[0013] One possible implementation also includes: Continuously monitor the relationship between outlet pressure and surge pressure values; If the outlet pressure remains higher than the surge pressure within the preset time, continue to increase the opening of the electric check valve until the outlet pressure is lower than the surge pressure.

[0014] In one possible implementation, when the outlet pressure is greater than the surge pressure, the increment of the electric check valve opening is equal each time.

[0015] In one possible implementation, the opening degree of the electric check valve is adjusted by 2% each time.

[0016] The solution shown in the embodiments of this application, compared with the prior art: (1) The electric check valve is in a forced-closed state before the fan starts. Compared with the traditional mechanical check valve that relies on spring pressure for sealing, the sealing reliability is higher. It will not cause backflow risk due to spring fatigue, effectively preventing combustible gas in the pipeline from flowing back to the fan side and avoiding damage to internal components.

[0017] (2) In this embodiment, the exhaust valve at the air outlet duct is eliminated, and the speed is adjusted step by step within the low-speed operating range. This allows the air supply pressure on the air outlet side to be smoothly released into the air supply duct as the opening of the electric check valve gradually increases during the fan speed-up process. This avoids the surge caused by the sudden pressure rise due to the closure of the electric check valve, and ensures the stability of the pressure during the fan speed-up process.

[0018] (3) The vent valve has been eliminated, avoiding the technical problem of not being able to adapt to explosion-proof conditions due to reliance on the vent valve, and expanding the application scenarios of the magnetic levitation blower.

[0019] (4) The electric check valve is electrically linked to the system, so that the opening adjustment of the electric check valve is automatically completed by the system according to the speed parameters without manual intervention. Compared with the manual control of the traditional mechanical check valve, the degree of automation is higher and it is suitable for the intelligent control needs of modern industry. Detailed Implementation

[0020] To make the technical problems, solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0021] The anti-surge and anti-backflow control method for magnetic levitation blowers provided by this invention will now be described.

[0022] The method for preventing surge and backflow in the magnetic levitation blower includes: An electric check valve is installed in the air supply duct outside the blower equipment, and the electric check valve is electrically connected to the corresponding system of the magnetic levitation blower. Before the fan is started, the electric check valve is in the closed position; The low-speed operating range of the fan is divided into multiple speed levels. The opening degree of the electric check valve is different for different speed levels, and the higher the speed, the larger the opening degree of the electric check valve. After the fan starts, it enters the low-speed operating range. The motor speed is adjusted step by step from small to large. The system adjusts the opening of the electric check valve according to the motor speed. Once the fan enters the high-speed operating range, the electric check valve opens fully and the speed increases directly to the target set speed.

[0023] It should be noted that, in actual use, the magnetic levitation blower corresponding to the embodiments of this application does not have an exhaust valve installed in its air outlet duct.

[0024] The system adjusts the opening of the electric check valve as follows: The system pre-stores the opening parameters corresponding to different fan speeds. During fan operation, the system collects operating parameters such as fan speed and outlet pressure to determine the current operating range and speed setting. When it detects that the opening of the electric check valve needs adjustment, it sends an electrical signal command to the electric check valve. After receiving the command, the actuator of the electric check valve rotates the valve plate to the target opening, making its opening correspond to the speed.

[0025] After the fan stops, the system sends a full-close command, and the electric check valve returns to the closed state. Before the fan restarts, the system continuously maintains the electric check valve fully closed electrical signal control to prevent backflow from the source.

[0026] The surge and backflow prevention control method for magnetic levitation blowers provided in this embodiment, compared with the prior art: (1) The electric check valve is in a forced-closed state before the fan starts. Compared with the traditional mechanical check valve that relies on spring pressure for sealing, the sealing reliability is higher. It will not cause backflow risk due to spring fatigue, effectively preventing combustible gas in the pipeline from flowing back to the fan side and avoiding damage to internal components.

[0027] (2) In this embodiment, the exhaust valve at the air outlet duct is eliminated, and the speed is adjusted step by step within the low-speed operating range. This allows the air supply pressure on the air outlet side to be smoothly released into the air supply duct as the opening of the electric check valve gradually increases during the fan speed-up process. This avoids the surge caused by the sudden pressure rise due to the closure of the electric check valve, and ensures the stability of the pressure during the fan speed-up process.

[0028] (3) The vent valve has been eliminated, avoiding the technical problem of not being able to adapt to explosion-proof conditions due to reliance on the vent valve, and expanding the application scenarios of the magnetic levitation blower.

[0029] (4) The electric check valve is electrically linked to the system, so that the opening adjustment of the electric check valve is automatically completed by the system according to the speed parameters without manual intervention. Compared with the manual control of the traditional mechanical check valve, the degree of automation is higher and it is suitable for the intelligent control needs of modern industry.

[0030] In some embodiments, the multiple speed ranges are N1, N2, ..., Nn, and the opening degree of the electric check valve corresponding to each speed range is D1, D2, ..., Dn. When the system adjusts the opening of the electric check valve, different openings correspond to different safety margins d1, d2, ..., dn; That is, when the speed setting is Nx, the actual opening degree of the corresponding electric check valve is Dx+dx; Where 1≤x≤n.

[0031] In this embodiment, the safety margin is an additional compensation value for the opening degree of the electric check valve. That is, when the system adjusts the opening degree of the electric check valve, it does not directly adjust it to the basic opening degree Dx, but adds the corresponding safety margin on the basis of the basic opening degree, i.e., Dx+dx.

[0032] The system pre-stores the opening degree of the electric check valve corresponding to different speed settings, as well as the safety margin corresponding to different electric check valve opening degrees. When the fan reaches the corresponding speed setting, the system automatically retrieves the Dx and dx corresponding to that speed setting, calculates them, and sends an electrical signal command of the actual target opening degree (Dx+dx) to the electric check valve. The electric actuator of the electric check valve executes precisely, and the entire process is synchronized with the speed setting switch.

[0033] In this embodiment, each speed setting corresponds to a speed range. When the motor speed falls within this range, the opening degree of the corresponding electric check valve is the same. By establishing a one-to-one correspondence between speed settings and the opening degree of the electric check valve, the opening adjustment of the electric check valve is specifically divided into multiple fixed opening degrees. This avoids excessively large, small, or delayed opening adjustments during speed setting switching. The system can automatically initiate opening adjustment commands based on the speed setting, and the electric actuator of the electric check valve executes the commands accordingly, reducing opening adjustment errors and ensuring the stability of the fan's air pressure and flow rate at each speed setting, thus reducing the probability of surge triggering.

[0034] It should be noted that the base opening Dx corresponding to each speed setting is the critical opening calibrated by the system that just keeps the fan outlet pressure below the surge threshold. At this point, the fan is in a critical surge state. If there are slight disturbances such as minor resistance fluctuations or flow changes in the pipeline, the outlet pressure can easily exceed the surge pressure value instantaneously, directly triggering the surge protection. In this embodiment, the electric check valve opening corresponding to each speed setting has a corresponding safety margin. The sum of the base opening Dx and the safety margin dx further reduces the fan outlet pressure, allowing the fan to operate in a manner that avoids the critical surge state and reducing the probability of false surge triggering.

[0035] In some embodiments, the safety margins d1, d2, ..., dn have different values, and d1 < d2 < ... < dn.

[0036] The lower the fan speed, the smaller the airflow, and the slower the pipeline pressure builds up. Although the surge critical range is narrow, the impact of operating disturbances is smaller, thus requiring a smaller anti-surge margin. Conversely, the higher the fan speed, the higher the airflow and outlet pressure, the greater the amplitude and probability of pipeline pressure fluctuations. The surge critical risk increases stepwise, requiring a larger safety margin to offset the surge hazard caused by the high risk.

[0037] Therefore, the safety margin corresponding to the opening degree of each electric check valve is not a uniform fixed value, but rather increases accordingly as the opening degree increases. The increase of the safety margin dx and the increase of the basic opening degree Dx form a synergistic relationship, providing better opening redundancy for the speed range corresponding to higher speeds, ensuring normal air supply pressure release at each speed range, allowing the fan to stay away from the surge threshold even in high-risk stages, improving the efficiency of pre-surge protection, and avoiding insufficient or excessive protection.

[0038] In some embodiments, the low-speed operating range is divided into four speed levels, and the safety margins corresponding to different opening degrees of the electric check valve are d1, d2, d3, and d4, where d1 is 2%, d2 is 3%, d3 is 5%, and d4 is 8%.

[0039] It should be noted that the safety margin of 2% is based on the electric check valve being fully open to a value of 1, and the safety margin is 2% * 1.

[0040] In this embodiment, the four speed settings in the low-speed operating range are N1, N2, N3, and N4. Specifically, N1 corresponds to a speed of 0–500 rpm, N2 to 500–1000 rpm, N3 to 1000–1500 rpm, and N4 to 1500–2000 rpm.

[0041] This embodiment illustrates a specific division of the aforementioned speed ranges and safety margins. The low-speed operating range is precisely divided into four speed ranges: After the fan starts, it enters the first range (N1), which represents the initial stage of fan startup. At this range, the speed is the lowest, the airflow is minimal, and the outlet pressure is almost nonexistent, with only a slight risk of critical surge due to minor disturbances. Entering the second range (N2), the fan speed increases slightly, and the pressure begins to build up slowly, with a slight increase in surge risk. Entering the third range (N3), the fan enters the mid-to-high range of low speed, with flow and pressure increasing simultaneously. The amplitude and probability of pipeline pressure fluctuations increase, significantly raising the surge risk. Entering the fourth range, the fan approaches the upper limit of the low-speed operating range, and the flow and pressure are close to the preset values ​​for the high-speed operating range. This is the range with the highest surge risk in the low-speed operating range and is also the stage most susceptible to pressure build-up triggering surge protection.

[0042] It should be noted that when the fan speed gradually increases across multiple speed levels, it is necessary to ensure that the fan runs smoothly at the current speed level before switching to the next speed level.

[0043] In this embodiment, by clearly defining the fan speed corresponding to each speed gear and the safety margin corresponding to each speed gear, the system can pre-set the opening degree of the corresponding electric check valve when the fan is detected to be in different speed gears.

[0044] Alternatively, the above-mentioned speed and safety margin values ​​can be input into the system. The system will use speed as the x-axis and safety margin as the y-axis to automatically analyze the relationship curve between the speed range division and the safety margin. When the fan speed range division is not four but five, the system will automatically determine the safety margin in the corresponding relationship curve based on the range of the five speed ranges, and then adjust the opening of the electric check valve.

[0045] For example, if there are 5 RPM speed settings: N1 = 0–400 rpm, N2 = 400–800 rpm, N3 = 800–1200 rpm, N4 = 1200–1600 rpm, and N5 = 1600–2000 rpm, then the corresponding safety margins are d1 = 2%, d2 = 3%, d3 = 4%, d4 = 6%, and d5 = 8%.

[0046] Furthermore, when the fan speed is at the critical point between two speed settings, the opening of the electric check valve corresponding to the lower speed setting should be used as the standard. For example, when N1 = 0~500rpm and N2 = 500~1000rpm, and the fan speed is 500rpm, then the opening of the electric check valve currently being adjusted should be D1+2%.

[0047] In some embodiments, the low-speed operating range is 0 to 2000 rpm, and the high-speed operating range is 2000 rpm to the target set speed.

[0048] This embodiment is for cases where the target set speed is greater than 2000 rpm. In the low-speed operating range, the fan speed is gradually increased; when entering the high-speed operating range, the fan outlet pressure is sufficient to overcome the backflow pressure in the pipeline, at which point the speed can be directly increased to the target set speed, and the electric check valve is fully opened.

[0049] By dividing the motor's operating state into two ranges: a low-speed range and a high-speed range, and defining the corresponding speeds for each range, the fan gradually increases speed in the low-speed range and directly accelerates to the target set speed in the high-speed range. This ensures that the fan does not trigger surge protection due to rapid acceleration at lower speeds, while also improving regulation efficiency by directly accelerating to the target set speed in the high-speed range. This achieves both safety and reliability in fan regulation, meeting the requirements for backflow prevention and surge prevention in combustible gas transportation.

[0050] In some embodiments, it also includes: The system monitors the outlet pressure of the fan at different speed levels and compares the outlet pressure with the surge pressure value; When the outlet pressure is higher than the surge pressure value, increase the opening degree of the current electric check valve.

[0051] Specifically, a pressure sensor can be installed at the outlet of the fan. The reading of the pressure sensor can be transmitted to the system, and the system compares the current outlet pressure with the corresponding surge pressure value.

[0052] The outlet pressure is detected only in the low-speed operating range and compared with the surge pressure value. When the outlet pressure is higher than the surge pressure value, surge protection is easily triggered. At this time, the opening of the electric check valve can be increased to quickly release the back pressure at the fan outlet by increasing the flow area, thereby reducing the actual outlet pressure and bringing the outlet pressure back to a state lower than the surge pressure value, thus avoiding the critical surge protection.

[0053] Considering the various unstable factors in actual working conditions, this embodiment can avoid many disturbance factors. By monitoring the outlet pressure in real time and adjusting the electric check valve immediately, it can quickly respond to various unforeseen abnormal disturbances. All of these can be quickly depressurized by increasing the opening of the electric check valve, making the anti-surge control process more in line with the complex working conditions on site.

[0054] By pre-matching the opening degree and safety margin, the blower is kept away from the surge threshold. Furthermore, combined with monitoring the outlet pressure, flexible adjustments can be made for abnormal operating conditions. This combination forms a dual anti-surge system, reducing the risk of surge and significantly improving the reliability of anti-surge protection. Even in the harsh explosion-proof conditions of combustible gas transportation, it ensures that the blower will not frequently trigger surge protection and will continue to operate stably.

[0055] When the outlet pressure is greater than the surge pressure value, simply increase the opening of the electric check valve without changing the fan speed. The output of the air supply flow is stable. The excess pressure is released by increasing the flow area, which quickly eliminates the risk of surge and avoids fluctuations in the air supply system caused by sudden changes in speed.

[0056] Based on the preset control logic, an additional instruction is set to adjust the output pressure by monitoring. Even if the preset parameters deviate slightly due to changes in operating conditions, they can be corrected in time through feedback adjustment. This ensures that pipelines without vent valves will not accidentally trigger surge, thus avoiding safety accidents such as flammable gas leaks caused by drastic fluctuations in pipeline pressure due to surge, and further enhancing operational safety.

[0057] In some embodiments, it also includes: Continuously monitor the relationship between outlet pressure and surge pressure values; If the outlet pressure remains higher than the surge pressure within the preset time, continue to increase the opening of the electric check valve until the outlet pressure is lower than the surge pressure.

[0058] The system collects the outlet pressure through a pressure sensor, compares it with the surge pressure value, and issues an adjustment command based on the deviation. After adjusting the opening of the electric check valve, the pressure is collected again until the deviation is eliminated. This closed-loop control process improves the system's automation and intelligent adjustment capabilities. It can achieve automatic adjustment throughout the entire process without manual intervention, adapting to the intelligent control needs of modern industry. It can accurately control the outlet pressure within a safe range below the surge pressure value, avoiding over-adjustment or under-adjustment.

[0059] When the outlet pressure exceeds the surge pressure, surge protection is easily triggered. A single adjustment may not guarantee that the outlet pressure will fall below the surge pressure. Therefore, by observing the outlet pressure value over a preset time period, it can be determined whether the pressure relief capacity is insufficient. If the outlet pressure remains above the surge pressure, the opening of the electric check valve should be further adjusted. This adjustment process can eliminate the risk of surge and prevent surge protection from being triggered due to incomplete pressure relief.

[0060] Optionally, the preset duration can be 5 seconds. This preset duration allows for a reasonable response time to pressure changes, preventing excessive or frequent system adjustments. There is a certain lag between changes in the fan outlet pressure and the adjustment of the electric check valve opening. After the electric check valve opening is adjusted, the pressure in the pipeline needs a certain amount of time to be released by increasing the flow area, rather than decreasing rapidly. The preset duration is matched with the pipeline's hysteresis response characteristics and the fan's pressure output characteristics, providing sufficient response time for pressure relief. Only if the pressure does not recover within the preset duration is it considered invalid compensation, making the pressure feedback adjustment process more precise.

[0061] In some embodiments, when the outlet pressure is greater than the surge pressure value, the increment of the electric check valve opening is equal each time.

[0062] Specifically, the opening degree of the electric check valve is adjusted by 2% each time.

[0063] If the pressure is significantly exceeded and the opening of the electric check valve is increased all at once, it can easily lead to a sudden drop in outlet pressure, causing fluctuations in flow and pressure within the pipeline. In this embodiment, each opening adjustment is a small adjustment, and the total pressure relief requirement is met through multiple incremental adjustments, allowing the outlet pressure of the blower to stabilize and gradually decrease to a safe range.

[0064] This embodiment ensures that each adjustment of the electric check valve opening is small, while still achieving the effect of reducing outlet pressure, by limiting the adjustment amount each time. It avoids a sudden pressure drop due to excessive adjustment. By setting the outlet pressure to be greater than the surge pressure value in the system, the opening degree is increased by 2% each time, eliminating the need for system analysis and allowing direct execution of the corresponding instructions. This reduces the complexity of program design and lowers the probability of program errors.

[0065] The actuator of the electric check valve can be adapted to a fixed increment of 2%, which improves the accuracy of the opening adjustment, ensures that the actual adjustment opening matches the system command, avoids errors where the command does not match the actual adjustment, and ensures the effectiveness of pressure relief regulation.

[0066] As one specific implementation method of this application, the following steps are referenced: (1) No vent valve is installed in the air outlet duct of the fan body; (2) An explosion-proof electric check valve is installed in the air supply duct outside the fan equipment, with stepless adjustable opening degree; (3) When the fan is stopped, the system controls the electric check valve to be closed to prevent gas from flowing back into the fan side.

[0067] (4) The low-speed operating range of the fan (0-2000rpm) is set with four operating speed ranges, namely 0~500rpm, 500~1000rpm, 1000~1500rpm and 1500~2000rpm; (5) At each operating speed, determine the surge pressure value for each speed, that is, the minimum outlet pressure value when the fan just experiences surge vibration, from low to high, namely P1, P2, P3 and P4, and the corresponding check valve openings are D1%, D2%, D3% and D4 respectively; (the test record is made separately on-site by adjusting the check valve opening). (6) Each time the fan is started, the speed is gradually increased. That is, during the speed increase process after the fan is started, in the low speed range (0-2000rpm), it is necessary to pass through four gears from low to high: 0-500rpm, 500-1000rpm, 1000-1500rpm and 1500-2000rpm respectively. Only after the operation at each gear is stable can the speed be increased to the next gear until the target set speed is reached. (7) When the fan operating speed is 0 < R ≤ 500 rpm, the system controls the check valve opening to be D1 + d1; when the fan operating speed is 500 rpm < R ≤ 1000 rpm, the system controls the check valve opening to be D2 + d2; when the fan operating speed is 1000 rpm < R ≤ 1500 rpm, the system controls the check valve opening to be D3 + d3; when the fan operating speed is 1500 rpm < R ≤ 2000 rpm, the system controls the check valve opening to be D4 + d4. The addition of d opening in this scheme is to consider safety margin and avoid critical surge protection. Since the opening and outlet pressure are exponentially proportional, the smaller the opening, the greater the change in outlet pressure corresponding to each change in opening, so d1, d2, d3 and d4 have different values. The default values ​​are 2% for d1, 3% for d2, 5% for d3 and 8% for d4, which can be modified through the human-machine interface.

[0068] (8) Under the conditions of (7) above, monitor the relationship between the outlet pressure value and the surge pressure value in real time under the four operating gears. If the outlet pressure is higher than the surge pressure, the opening should be increased by 2% based on the original opening, and the relationship should be judged again after 5 seconds; if the outlet pressure is still higher than the surge pressure, the opening should be increased by 2% based on the original opening, and so on, until the outlet pressure is lower than the surge pressure. (9) When the fan speed is R > 2000 rpm, the fan outlet pressure is sufficient to overcome the backflow pressure in the pipeline. At this time, the speed is directly increased to the target set speed, and the check valve is fully opened at the same time.

[0069] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for controlling surge and backflow prevention in a magnetic levitation blower, characterized in that, include: An electric check valve is installed in the air supply duct outside the blower equipment, and the electric check valve is electrically connected to the corresponding system of the magnetic levitation blower. Before the fan is started, the electric check valve is in the closed position; The low-speed operating range of the fan is divided into multiple speed levels. The opening degree of the electric check valve is different for different speed levels, and the higher the speed, the larger the opening degree of the electric check valve. After the fan starts, it enters the low-speed operating range. The motor speed is adjusted step by step from small to large. The system adjusts the opening of the electric check valve according to the motor speed. Once the fan enters the high-speed operating range, the electric check valve opens fully and the speed increases directly to the target set speed.

2. The anti-surge and anti-backflow control method for a magnetic levitation blower as described in claim 1, characterized in that, The multiple speed settings are N1, N2, ..., Nn, and the opening degree of the electric check valve corresponding to each speed setting is D1, D2, ..., Dn. When the system adjusts the opening of the electric check valve, different openings correspond to different safety margins d1, d2, ..., dn; That is, when the speed setting is Nx, the actual opening degree of the corresponding electric check valve is Dx+dx; Where 1≤x≤n.

3. The anti-surge and anti-backflow control method for magnetic levitation blowers as described in claim 2, characterized in that, The safety margins d1, d2, ..., dn have different values, and d1 < d2 < ... < dn.

4. The anti-surge and anti-backflow control method for a magnetic levitation blower as described in claim 3, characterized in that, The low-speed operating range is divided into four speed levels. The safety margins corresponding to different opening degrees of the electric check valve are d1, d2, d3, and d4, where d1 is 2%, d2 is 3%, d3 is 5%, and d4 is 8%.

5. The anti-surge and anti-backflow control method for a magnetic levitation blower as described in claim 1, characterized in that, The low-speed operating range is 0 to 2000 rpm, and the high-speed operating range is 2000 rpm to the target set speed.

6. The anti-surge and anti-backflow control method for a magnetic levitation blower as described in claim 5, characterized in that, The low-speed operating range is divided into four speed settings: N1, N2, N3, and N4. The speed setting N1 corresponds to 0–500 rpm, the speed setting N2 corresponds to 500–1000 rpm, the speed setting N3 corresponds to 1000–1500 rpm, and the speed setting N4 corresponds to 1500–2000 rpm.

7. The anti-surge and anti-backflow control method for a magnetic levitation blower as described in claim 1, characterized in that, Also includes: The system monitors the outlet pressure of the fan at different speed levels and compares the outlet pressure with the surge pressure value; When the outlet pressure is higher than the surge pressure value, increase the opening degree of the current electric check valve.

8. The anti-surge and anti-backflow control method for a magnetic levitation blower as described in claim 7, characterized in that, Also includes: Continuously monitor the relationship between outlet pressure and surge pressure values; If the outlet pressure remains higher than the surge pressure within the preset time, continue to increase the opening of the electric check valve until the outlet pressure is lower than the surge pressure.

9. The anti-surge and anti-backflow control method for a magnetic levitation blower as described in claim 8, characterized in that, When the outlet pressure is greater than the surge pressure, the increment of the electric check valve opening is equal each time.

10. The anti-surge and anti-backflow control method for a magnetic levitation blower as described in claim 9, characterized in that, Each adjustment of the electric check valve opening is 2%.