Frequency adjusting system and method based on roots pump-backing pump
By designing a frequency adjustment system in the vacuum systems of Roots pumps and fore pumps, and using frequency converters and motors to achieve adaptive frequency adjustment, the problem of Roots pump overload in the existing system when the frequency is not adapted is solved, the application range is expanded and energy-saving effects are achieved.
Patent Information
- Application Number
- CN202510392784.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-31
- Publication Date
- 2025-06-20
AI Technical Summary
The existing vacuum system of Roots pump plus fore pump is prone to overload the Roots pump when the frequency is not adapted, especially when the load changes greatly, it is difficult to effectively deal with the application needs of large and light loads.
A frequency adjustment system based on Roots pump-fore pump is designed. By configuring the rear motor, rear inverter, front motor and front inverter in Roots pump and fore pump, and using a pressure sensor and controller to achieve frequency adaptive adjustment, we ensure that the frequency of the Roots pump and the fore pump are adapted to each other.
It realizes adaptive adjustment of the frequency of Roots pump and fore pump, and can expand the application range of vacuum pumps at the frequency required by customers, adapt to the needs of large and light loads, and achieve energy-saving results while meeting customer usage needs.
Smart Images
Figure CN120175640A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of vacuum pumps, and particularly relates to a frequency regulation system and method based on a Roots pump - fore pump. Background Art
[0002] In the existing vacuum system with a Roots pump plus a fore pump, generally, the Roots pump uses frequency conversion to adjust the rotational speed, and the fore pump operates at a fixed frequency or two - stage speed. It is relatively easy to have the problem of overload of the Roots pump caused by frequency inadaptability. For example, when the operating frequency of the Roots pump is relatively high while the operating frequency of the fore pump is relatively low, and the compression ratio of the unit is relatively large, the Roots pump will experience overload (over - current) under large loads, because the Roots pump has only a certain pressure difference (load) tolerance ability. Summary of the Invention
[0003] The purpose of the present invention is to provide a frequency regulation system and method based on a Roots pump - fore pump, in which the frequencies of the Roots pump and the fore pump are adaptively adjusted, so that the unit can operate at the frequency required by the customer, and the application range of the vacuum pump is expanded. The technical solutions adopted are as follows: A frequency regulation system based on a Roots pump - fore pump, comprising: At least one Roots pump, each Roots pump is configured with a rear motor and a rear frequency converter; the Roots pump is connected to the output shaft of the rear motor, and the rear motor is electrically connected to the output end of the rear frequency converter; the suction end of the previous Roots pump is connected to the discharge end of the next Roots pump; the intake end of the last Roots pump is connected to an intake pipe, and a pressure sensor is arranged on the intake pipe; A fore pump, configured with a front motor and a front frequency converter, whose suction end is connected to the discharge end of the foremost Roots pump, the fore pump is connected to the output shaft of the front motor, and the front motor is electrically connected to the output end of the front frequency converter; The rear frequency converter and the front frequency converter are both in bidirectional communication with the controller; the output end of the pressure sensor is connected to the controller, the front frequency converter and the rear frequency converter; The last rear frequency converter receives the pressure analog signal P, outputs an analog signal to the corresponding rear motor to change the rotational speed of the rear motor; The remaining rear frequency converters receive the pressure analog signal P or the analog signal output by the next rear frequency converter to the corresponding rear motor, and output an analog signal to the corresponding rear motor to change the rotational speed of the rear motor; The front frequency converter receives the pressure analog signal P or the analog signal output by the foremost rear frequency converter to the corresponding rear motor, and outputs an analog signal to the front motor to change the rotational speed of the front motor.
[0004] Preferably, the pressure analog signal is output by the controller or the pressure sensor.
[0005] Preferably, a target intake pressure is set in the controller, which receives the intake port pressure P1, compares it with the target intake pressure, and outputs a pneumatic analog signal P.
[0006] Preferably, the controller reads the currents of the front motor and the rear motor, and outputs a control signal to the corresponding frequency converter to achieve frequency adjustment.
[0007] Preferably, the controller is connected to a CT current transformer, which is installed on the main power line at the motor outgoing end of the corresponding motor.
[0008] Preferably, the controller obtains the currents of the front frequency converter and the rear frequency converter, and outputs a control signal to the corresponding frequency converter to achieve frequency adjustment.
[0009] A frequency adaptive adjustment method based on a Roots pump - fore pump, based on a frequency adjustment system of a Roots pump - fore pump, includes the following steps: The last rear frequency converter receives the pneumatic analog signal P, outputs an analog signal to the corresponding rear motor to change the rotation speed of the rear motor; The remaining rear frequency converters receive the pneumatic analog signal P or the analog signal output from the previous rear frequency converter to the corresponding rear motor, and output an analog signal to the corresponding rear motor to change the rotation speed of the rear motor; The front frequency converter receives the pneumatic analog signal P or the analog signal output from the foremost rear frequency converter to the corresponding rear motor, and outputs an analog signal to the front motor to change the rotation speed of the front motor.
[0010] Compared with the prior art, the advantages of the present invention are: 1. The frequency of the Roots pump and the fore pump is adaptively adjusted.
[0011] Specifically, the front frequency converter or the rear frequency converter both receive the pneumatic pressure value at the intake end of the last Roots pump and use the pneumatic pressure value as feedback data, and output an analog quantity to the corresponding motor to change the rotation speed of the motor.
[0012] Or the last rear frequency converter receives the pneumatic analog signal P; The remaining frequency converters respectively receive the analog signal output from the previous rear frequency converter to the corresponding rear motor; The front frequency converter receives the analog signal output from the foremost rear frequency converter to the corresponding rear motor.
[0013] 2. When the load of the customer process changes greatly, this invention can adjust the frequencies of the upper and lower pumps to achieve different compression ratios to meet the application requirements of large loads and light loads. When there is a large load, generally a larger fore pump is required and the compression ratio of the unit is smaller, while for a light load, a larger compression ratio can be used.
[0014] This invention can also reduce the frequency to achieve energy-saving effects on the premise of meeting the usage requirements of customers. Description of the Drawings
[0015] Figure 1 It is a structural diagram of the frequency regulation system based on a Roots pump - fore pump in Embodiment 1; Figure 2 It is a structural diagram of the frequency regulation system based on a Roots pump - fore pump in Embodiment 2; Figures 3 - 4 It is a structural diagram of the frequency regulation system based on a Roots pump - fore pump in Embodiment 3. Detailed Embodiments
[0016] The following will describe in more detail the frequency regulation system and method based on a Roots pump - fore pump of the present invention with reference to the schematic diagrams, in which the preferred embodiments of the present invention are shown. It should be understood that those skilled in the art can modify the present invention described herein while still achieving the advantageous effects of the present invention. Therefore, the following description should be understood as broad guidance for those skilled in the art and not as a limitation to the present invention.
[0017] Embodiment 1 As Figure 1 shown, the frequency regulation system based on a Roots pump - fore pump includes: A Roots pump, configured with a rear motor and a rear frequency converter; the Roots pump is connected to the output shaft of the rear motor, and the rear motor is electrically connected to the output end of the rear frequency converter; the air inlet end of the Roots pump is connected to an air inlet pipe, and a pressure sensor is provided on the air inlet pipe or at the air inlet of the Roots pump; A fore pump, configured with a front motor and a front frequency converter, whose suction end is connected to the air outlet end of the Roots pump through a pipeline, the fore pump is connected to the output shaft of the front motor, and the front motor is electrically connected to the output end of the front frequency converter; Both the rear frequency converter and the front frequency converter communicate bidirectionally with the controller; the output end of the pressure sensor is connected to the controller, the front frequency converter, and the rear frequency converter.
[0018] The rear frequency converter receives the air pressure analog signal P and outputs an analog signal to the corresponding rear motor to change the rotation speed of the rear motor; The front frequency converter receives the air pressure analog signal P or the analog signal output by the rear frequency converter to the corresponding rear motor, and outputs an analog signal to the front motor to change the rotation speed of the front motor.
[0019] Specifically, the air pressure analog signal is output by the controller or the pressure sensor.
[0020] The target intake pressure is set in the controller, which receives the intake port pressure P1, compares it with the target intake pressure, and outputs the air pressure analog signal P.
[0021] The controller reads the current and power consumption of the front motor and the rear motor, and outputs a control signal to the corresponding frequency converter to achieve frequency adjustment. Specifically, the controller is connected to a CT current transformer, and the CT current transformer is installed on the main power line at the motor outgoing terminal of the corresponding motor.
[0022] In addition, the controller obtains the current and power consumption of the front frequency converter and the rear frequency converter, and outputs a control signal to the corresponding frequency converter to achieve frequency adjustment. That is, when the main board communicates with the frequency converter at this time, there is no need to use an additional CT current transformer.
[0023] The current is used as a protection set value to limit the upper frequency limit and is an input signal, and the frequency is an output signal.
[0024] As Figure 1 shown, "Frequency Converter 1" refers to the rear frequency converter, and "Frequency Converter 3" refers to the front frequency converter.
[0025] In this embodiment, the customer cavity pressure P1 can also be used as the feedback data for the front frequency converter.
[0026] Frequency Converter 1 outputs an analog signal M1 to Motor 1. After the controller judges based on the current C1 of Motor 1, it outputs the frequency of Frequency Converter 1. The frequency of Frequency Converter 1 judged and output by the controller corresponds to the inlet pressure, so finally it forms within the frequency range [f1min~f1max] of Frequency Converter 1.
[0027] The pump body itself has upper and lower limits of frequency according to the mechanism design (the upper and lower limit frequencies of the frequency converter will be input as the upper and lower limit frequencies). The controller inputs the inlet pressure analog signal into the frequency converter. The frequency converter uses the PID regulation function to output the corresponding frequency (within the upper and lower limit frequencies set by the frequency converter), so that the pressure approaches the set pressure value (at this time, the frequency can fluctuate within a small range). When the inlet pressure changes, the frequency fluctuates greatly.
[0028] The analog signal M1 output from Frequency Converter 1 to Motor 1 is used as the input signal of Frequency Converter 3 of the front-stage pump. The frequency range f1min~f1max of Frequency Converter 1 corresponds to the frequency range f3min~f3max of Frequency Converter 3.
[0029] After the controller judges based on the current C3 of Motor 3, it outputs the frequency of Frequency Converter 3. The frequency of Frequency Converter 3 judged and output by the controller forms the frequency range [f3min~f3max].
[0030] Set the target pressure on the controller, adopt the PID regulation function of the frequency converter, use the analog signal of the target pressure as the input signal of the frequency converter, and the frequency converter outputs the corresponding frequency to make the pressure approach the target pressure.
[0031] The current has a limiting function. When the operating current does not exceed the set protection value (for example, 90% of the rated current), it operates at the current frequency; when the operating current exceeds the set protection value, the frequency is reduced until the current does not exceed the set protection value.
[0032] Embodiment 2 On the basis of Embodiment 1, a Roots pump is additionally provided.
[0033] As Figure 2 shown, the control system includes: 2 Roots pumps, each Roots pump is equipped with a rear motor and a rear frequency converter; the Roots pump is connected to the output shaft of the rear motor, and the rear motor is electrically connected to the output end of the rear frequency converter; the suction end of the previous Roots pump is connected to the air outlet end of the next Roots pump through a pipeline; the air inlet end of the last Roots pump is connected to an air inlet pipe, and a pressure sensor is arranged on the air inlet pipe; The front-stage pump is equipped with a front motor and a front frequency converter. Its suction end is connected to the air outlet end of the foremost Roots pump through a pipeline. The front-stage pump is connected to the output shaft of the front motor, and the front motor is electrically connected to the output end of the front frequency converter; The last rear frequency converter receives the pressure analog signal P and outputs an analog signal to the corresponding rear motor to change the rotation speed of the rear motor; The remaining rear frequency converters receive the pressure analog signal P or the analog signal output by the previous rear frequency converter to the corresponding rear motor, and output an analog signal to the corresponding rear motor to change the rotation speed of the rear motor; The front frequency converter receives the pressure analog signal P or the analog signal output by the foremost rear frequency converter to the corresponding rear motor, and outputs an analog signal to the front motor to change the rotation speed of the front motor.
[0034] As Figure 2 shown, "Frequency Converter 1" refers to the last rear frequency converter, "Frequency Converter 2" refers to the remaining rear frequency converters; "Frequency Converter 3" refers to the front frequency converter.
[0035] The inlet pressure or the customer cavity pressure P1 is used as the input signal of Frequency Converter 1 of Roots Pump 1. Frequency Converter 1 outputs an analog signal M1, and the controller outputs the frequency of Frequency Converter 1 according to the current C1 of Motor 1. The frequency of Frequency Converter 1 output by the controller forms a frequency range [f1min~f1max].
[0036] The analog signal M1 output from Inverter 1 to Motor 1 serves as the input signal for Inverter 2 of the Roots pump 2. The frequency range f1min~f1max of Inverter 1 corresponds to the frequency range f2min~f2max of Inverter 2. The controller determines the frequency of Inverter 2 based on the current C2 of Motor 2 and outputs it. The frequency of Inverter 2 output by the controller forms the frequency range [f2min~f2max].
[0037] The analog signal M2 output from Inverter 2 to Motor 2 serves as the input signal for Inverter 3 of the pre-stage pump. The frequency range f2min~f2max of Inverter 2 corresponds to the frequency range f3min~f3max of Inverter 3. The controller determines the frequency of Inverter 3 based on the current C3 of Motor 3 and outputs it. The frequency of Inverter 3 output by the controller forms the frequency range [f3min~f3max].
[0038] In other embodiments, Inverter 2 and Inverter 3 can directly take the inlet pressure or the customer chamber pressure P1 as the input.
[0039] Embodiment 3 As Figure 3 shown, on the basis of Embodiment 1, the scheme for obtaining the output frequency of the inverter is further refined.
[0040] As Figure 4 shown, on the basis of Embodiment 2, the scheme for obtaining the output frequency of the inverter is further refined.
[0041] In this embodiment, the controller comprehensively calculates the output frequency of the inverter based on the motor current of the inverter, the Roots pump housing temperature, the Roots pump inlet pressure, the Roots pump outlet pressure, and the inverter power consumption.
[0042] Specifically, test the boundary performance of the vacuum pump and obtain the output frequency under different input working conditions according to the algorithm.
[0043] Obtain the historical data set as shown in Table 1.
[0044] Train the neural network model based on the historical data set; After that, collect and input the current motor current, Roots pump housing temperature, Roots pump inlet pressure, Roots pump outlet pressure, and inverter power consumption into the trained model to obtain the output frequency of the inverter.
[0045] Table 1 Historical Data Set When different x1, x2, x3, x4, x5 are input, Y outputs corresponding values to make the inlet pressure close to the target value.
[0046] When the power consumption of the frequency converter exceeds the set upper limit value, the frequency Y should be reduced.
[0047] When the motor current exceeds the set upper limit value, the frequency Y should be reduced.
[0048] When the housing temperature X3 exceeds the set upper limit value, the frequency Y should be reduced.
[0049] X2 - X1 is the pressure difference between the inlet and outlet of the vacuum pump, which affects the power consumption X5 of the frequency converter. When X2 - X1 increases, X5 also increases.
[0050] As Figure 3 shown, the inlet pressure or the customer chamber pressure P1 is used as the input signal of the frequency converter 1 for the roots pump 1. The frequency converter 1 feeds back the frequency output analog quantity. The controller outputs the frequency of the frequency converter 1 after comprehensive judgment based on the current C1 of the motor 1, the housing temperature T1 of the roots pump 1, the inlet pressure P1 of the roots pump 1, and the exhaust pressure P3 of the roots pump 1.
[0051] The controller outputs the frequency of the frequency converter 3 after comprehensive judgment based on the current C3 of the motor 3, the housing temperature T3 of the fore pump, the inlet pressure P3 of the fore pump, and the exhaust pressure P4 of the fore pump.
[0052] As Figure 4 shown, the inlet pressure or the customer chamber pressure P1 is used as the input signal of the frequency converter 1 for the roots pump 1. The frequency converter 1 feeds back the frequency output analog quantity. The controller outputs the frequency of the frequency converter 1 after comprehensive judgment based on the current C1 of the motor 1, the housing temperature T1 of the roots pump 1, the inlet pressure P1 of the roots pump 1, and the exhaust pressure P2 of the roots pump 1.
[0053] The controller outputs the frequency of the frequency converter 2 after comprehensive judgment based on the current C2 of the motor 2, the housing temperature T2 of the roots pump 2, the inlet pressure P2 of the roots pump 2, and the exhaust pressure P3 of the roots pump 2.
[0054] The controller outputs the frequency of the frequency converter 3 after comprehensive judgment based on the current C3 of the motor 3, the housing temperature T3 of the fore pump, the inlet pressure P3 of the fore pump, and the exhaust pressure P4 of the fore pump.
[0055] Energy-saving mode (applicable to all embodiments) Considering the process intermittent cycle, the pump group sets the energy-saving mode.
[0056] In the energy-saving mode, the frequency converter 1 outputs f1min, and the frequency converter 2 outputs f2min; The frequency converter 3 outputs the frequency f3 with the lowest power consumption (f3 should be between f3min and f3max).
[0057] The above are only the preferred embodiments of the present invention and do not impose any restrictive effect on the present invention. Any person skilled in the art, within the scope of the technical solution of the present invention, makes any form of equivalent replacement or modification and other changes to the technical solution and technical content disclosed by the present invention, which are all within the content of the technical solution of the present invention and still fall within the protection scope of the present invention.
Claims
1. A frequency regulation system based on Roots pump-fore pump, characterized in that: include: At least one Roots pump, each of which is equipped with a rear motor and a rear frequency converter; The Roots pump is connected to the output shaft of the rear motor, and the rear motor is electrically connected to the output end of the rear frequency converter; the air intake end of the previous Roots pump is connected to the air outlet end of the next Roots pump; the air intake end of the last Roots pump is connected to the air intake pipe, and the air pressure sensor is arranged on the air intake pipe; A front pump is provided with a front motor and a front frequency converter, wherein the air suction end is connected to the air outlet end of the front Roots pump, the front pump is connected to the output shaft of the front motor, and the front motor is electrically connected to the output end of the front frequency converter; The rear frequency converter and the front frequency converter both communicate with the controller in a two-way manner; the output end of the air pressure sensor is connected to the controller, the front frequency converter and the rear frequency converter; The last rear frequency converter receives the air pressure analog signal P and outputs the analog signal to the corresponding rear motor to change the rotation speed of the rear motor; The remaining rear frequency converters receive the air pressure analog signal P or the analog signal output by the rear frequency converter to the corresponding rear motor, and output the analog signal to the corresponding rear motor to change the rotation speed of the rear motor; The front inverter receives the air pressure analog signal P or the analog signal output by the first rear inverter to the corresponding rear motor, and outputs the analog signal to the front motor to change the rotation speed of the front motor.
2. The frequency regulation system based on Roots pump-fore pump according to claim 1 is characterized in that: The air pressure analog signal is output by a controller or an air pressure sensor.
3. The frequency regulation system based on Roots pump-fore pump according to claim 2 is characterized in that: The controller sets the target intake pressure, receives the intake pressure P1, compares it with the target intake pressure, and outputs the pressure analog signal P.
4. The frequency regulation system based on Roots pump-fore pump according to claim 1 is characterized in that: The controller reads the current of the front motor and the rear motor, and outputs control signals to the corresponding inverters to achieve frequency regulation.
5. The frequency regulation system based on Roots pump-fore pump according to claim 4 is characterized in that: The controller is connected to a CT current transformer, and the CT current transformer is installed on a main power line of a motor outlet terminal of a corresponding motor.
6. The frequency regulation system based on Roots pump-fore pump according to claim 1 is characterized in that: The controller obtains the current of the front inverter and the rear inverter, and outputs control signals to the corresponding inverters to achieve frequency regulation.
7. A frequency adaptive regulation method based on a Roots pump-backing pump, based on the frequency regulation system based on a Roots pump-backing pump according to any one of claims 1 to 6, characterized in that: The following steps are involved: The last rear frequency converter receives the air pressure analog signal P and outputs the analog signal to the corresponding rear motor to change the rotation speed of the rear motor; The remaining rear frequency converters receive the air pressure analog signal P or the analog signal output by the rear frequency converter to the corresponding rear motor, and output the analog signal to the corresponding rear motor to change the rotation speed of the rear motor; The front inverter receives the air pressure analog signal P or the analog signal output by the first rear inverter to the corresponding rear motor, and outputs the analog signal to the front motor to change the rotation speed of the front motor.