Magnetic suspension pump rotor displacement detection method
By setting at least three pairs of Hall sensors in the magnetic levitation pump to calculate the impeller offset, the problem of unstable accuracy of the eddy current sensor is solved, and the precise detection of the impeller position and angle is achieved to ensure the stable operation of the magnetic levitation pump.
Patent Information
- Application Number
- CN202510556392.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-29
- Publication Date
- 2025-07-18
AI Technical Summary
In existing magnetic levitation pumps, the coil consistency of the eddy current sensor cannot be guaranteed, resulting in changes in detection accuracy, which may lead to eccentric operation of the impeller, causing power consumption to increase and scratch the impeller with the pump head, causing particles to fall off and contaminate.
At least three pairs of Hall sensors are uniformly distributed. By detecting the voltage amplitude and symbol of the Hall sensor, the offset of the impeller is calculated to avoid misjudgment, and accurate displacement detection is achieved, and the temperature drift problem of traditional eddy current sensors are avoided.
Accurate monitoring of the position and angle of the impeller is achieved, misjudgment and temperature drifting are avoided, stable operation of the magnetic levitation pump is ensured, and faults caused by impeller eccentricity are prevented.
Smart Images
Figure CN120333279A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of magnetic levitation pumps, and particularly to a method for detecting the displacement of a magnetic levitation pump rotor. Background Art
[0002] Magnetic levitation pumps are a newly developed ultra-clean liquid pumping technology in recent years. Through non-contact electromagnetic bearing technology, the impeller is suspended in the pump chamber and rotates at high speed to pump liquid, having advantages such as extremely low outlet pulsation, no mechanical friction, and almost no particle shedding. At the same time, it uses an ultra-pure fluororesin pump head, resulting in extremely low release of metal and ionic contaminants, showing great advantages in the applications of various high-end semiconductor equipment in 12-inch advanced processes, and has become a core component commonly used in semiconductor machines such as single-wafer cleaning, electroplating / chemical plating, and chemical mechanical polishing (SDS system).
[0003] In a magnetic levitation pump, controlling the rotor at the central position is a necessary condition for the long-term high-speed and stable rotation of the rotor. In practice, the position of the rotor is usually detected by an eddy current displacement sensor. However, there is currently no mature industry detection standard for eddy current coils, and they are all wound by manufacturers themselves, unable to ensure the coil consistency. Therefore, when the use environment changes, the performance of the eddy current sensor will fluctuate, and the detection accuracy will change, and this performance fluctuation is unpredictable, which may cause the impeller to work eccentrically, resulting in an increase in the overall power consumption; in severe cases, it will cause high-speed rubbing between the impeller and the pump head, resulting in a large amount of particle shedding, polluting the semiconductor process production line and equipment. Therefore, it is necessary to find a displacement detection scheme with stable performance and less affected by environmental factors such as temperature to ensure the continuous and stable operation of the impeller.
[0004] In the prior art, since the industry detection standard for Hall sensors is relatively mature and less affected by environmental factors such as temperature, Hall sensors can be used for displacement detection. As Figure 1 shown, by evenly arranging four Hall sensors along the circumference of the impeller, and the distance between each Hall sensor and the impeller is equal. In the figure, 1_1, 1_2, 1_3, and 1_4 are respectively 4 Hall sensors, C1 represents the virtual circle formed by the Hall sensors, 2_1 represents the impeller, and M1 and M2 represent the intersection points of the N and S pole dividing lines of the impeller and the virtual circle C1. At this time, M1 coincides with the center of the Hall sensor 1_4, and the signal detected by the Hall sensor 1_4 is less than the signal detected by the Hall sensor 1_2.
[0005] According to the voltage amplitudes of two symmetrically arranged Hall sensors, the offset of the impeller can be calculated, and then the displacement of the impeller can be obtained. However, there are still obvious defects in the above-mentioned existing technical solutions. When the N-S pole dividing line of the impeller passes through the center of the Hall sensor, the measurement result will deviate. According to the determination method of the above-mentioned existing technology, the position of the impeller will be misjudged to the right of the y_1 axis, which does not conform to the actual situation. In this case, the system will mistakenly continue to adjust the impeller in the eccentric direction, resulting in the impeller rubbing against the wall. Summary of the Invention
[0006] To solve the defects existing in the prior art, the present invention proposes a method for detecting the displacement of the rotor of a magnetic levitation pump. By evenly arranging at least three pairs of Hall sensors circumferentially on the impeller, the technical problems existing in only arranging two pairs of Hall sensors originally can be avoided, ensuring the accuracy of displacement detection and avoiding damage to the motor and pollution of the production line caused by impeller eccentricity.
[0007] The present invention evenly distributes at least three pairs of oppositely arranged Hall sensors centered on the physical center of the volute; The specific detection method is as follows: First, collect the detection data of n (n≥3) pairs of Hall sensors; Then, screen the collected data to determine whether the impeller is at the physical center; When the center point of the Hall sensor coincides with the N-S pole dividing line of the impeller, the impeller is at the physical center. The distances between the two oppositely arranged Hall sensors and the impeller are the same, and the detected magnetic field intensities are also the same, but with opposite signs. Assuming that the amplitudes detected by the nth pair of Hall sensors are Vn1 and Vn2 respectively, at this time . There is no need to calculate the displacement of the impeller center.
[0008] When the impeller is not at the physical center, the distances between the same pair of Hall sensors and the impeller are different, and the detected magnetic field intensities are also different, but the signs are still opposite. If , it means that the impeller is close to the Hall sensor outputting Vn1. If , it means that the impeller is close to the Hall sensor outputting Vn2. It is necessary to calculate the displacement of the impeller center.
[0009] Furthermore, the specific determination method is as follows: Compare the output value of the Hall sensor with the set value ( is a very small value close to zero). If the absolute value of the output value of the Hall sensor is less than , it means that the center point of the Hall sensor corresponding to the value coincides with the N-S pole dividing line of the impeller; if the absolute value of the output value of the Hall sensor is greater than or equal to , it indicates that the center point of the Hall sensor corresponding to the numerical value does not coincide with the N and S pole demarcation line of the impeller.
[0010] Finally, based on the output data of the remaining Hall sensors and combined with the preset calibration coefficients, the specific position of the impeller in the xy plane coordinate system can be calculated.
[0011] Furthermore, the calculation process is as follows: When the absolute values of the output numerical values of all Hall sensors are greater than or equal to , use the output data of each pair of Hall sensors for calculation. Define the displacement detected by the nth pair of Hall sensors as , where k1 is the calibration coefficient, representing the correspondence with , which needs to be calibrated according to the actual situation; Vn1 and Vn2 are the output numerical values of a pair of Hall sensors. Arbitrarily select two displacement data and , and according to the coordinate transformation, obtain the specific position of the impeller in the xy plane coordinate system.
[0012] When the absolute value of the output numerical value of only one Hall sensor is less than the set value , discard the data of this sensor and the sensor with its relative position. The displacement detected by the remaining Hall sensors is still defined as . Arbitrarily select two displacement data and , and according to the coordinate transformation, obtain the specific position of the impeller in the xy plane coordinate system.
[0013] When the absolute values of the numerical values Vp_1 and Vq_1 detected by two Hall sensors are both less than the set value , discard the data detected by these two sensors. The displacement detected by the sensors paired with these two sensors is defined as , where k2 is also the calibration coefficient, representing the correspondence with , which also needs to be calibrated according to the actual situation. The displacement detected by the remaining Hall sensors is still defined as . Arbitrarily select two displacement data and or arbitrarily select one displacement data and , and according to the coordinate transformation, obtain the specific position of the impeller in the xy plane coordinate system.
[0014] The present invention realizes the displacement detection of the impeller by setting at least three pairs of Hall sensors and applying corresponding detection algorithms, avoiding the misjudgment problem that occurs in the prior art when the N / S pole boundary line of the impeller passes through the center of the sensor. At the same time, this solution can realize more accurate and comprehensive monitoring of two core information, namely the position and angle of the impeller, by setting multiple pairs of evenly distributed Hall sensors. In addition, compared with eddy current sensors, Hall sensors are less affected by temperature, avoiding the temperature drift problem of traditional eddy current sensors, and are very suitable for application scenarios such as magnetic levitation pumps that require non-contact and have extremely high requirements for sensor installation space, sensor measurement accuracy, and sensor response speed. Brief Description of the Drawings
[0015] Figure 1 It is a schematic diagram of the prior art when the center point of the Hall sensor coincides with the N / S pole boundary line of the impeller; Figure 2 It is a schematic diagram of an embodiment of the present invention when the center point of the Hall sensor does not coincide with the N / S pole boundary line of the impeller; Figure 3 It is a schematic diagram of an embodiment of the present invention when the center point of one Hall sensor coincides with the N / S pole boundary line of the impeller; Figure 4 It is a schematic diagram of an embodiment of the present invention when the center points of two Hall sensors coincide with the N / S pole boundary line of the impeller. Detailed Description of the Invention
[0016] The present invention will be further described below with reference to the accompanying drawings.
[0017] In this embodiment, three pairs of oppositely arranged Hall sensors are taken as an example, and the adjacent two Hall sensors are evenly distributed at an interval of 60°.
[0018] As Figure 2 shown, three pairs of Hall sensors (centered on the physical center 2 of the volute, evenly distributed to form a virtual circle 1; the first Hall sensor 5_1 and the second Hall sensor 5_2 are oppositely arranged, the third Hall sensor 5_3 and the fourth Hall sensor 5_4 are oppositely arranged, and the fifth Hall sensor 5_5 and the sixth Hall sensor 5_6 are oppositely arranged. The center connection lines of the two oppositely arranged Hall sensors all pass through the physical center 2 of the volute.
[0019] When the impeller center 4 is at the physical center 2 of the volute, the distances from the centers of the two oppositely arranged Hall sensors to the impeller center 4 are the same, and the detected magnetic field intensities are also the same, but with opposite signs. Assuming that the amplitudes detected by the nth pair of two Hall sensors are Vn1 and Vn2 respectively, at this time .
[0020] When the center 4 of the impeller is not at the physical center 2 of the volute, the distances between the centers of the two relatively arranged Hall sensors and the center 4 of the impeller are different, and the detected magnetic field intensities are also different, but the signs are still opposite. If then it indicates that the impeller 3 is close to the Hall sensor with output Vn1. If then it indicates that the impeller 3 is close to the Hall sensor with output Vn2.
[0021] The specific detection method is as follows: First, collect the output values of three pairs of Hall sensors.
[0022] Then, compare each output value with the set value ( is a very small value close to zero). If the absolute value of the output voltage of the Hall sensor is greater than or equal to it means that the center point of this Hall sensor does not coincide with the N and S pole dividing line of the impeller; this can avoid measurement errors when the N and S pole dividing line of the impeller passes through the center of the Hall sensor.
[0023] Finally, based on the output data of the remaining Hall sensors and combined with the preset calibration coefficient, the specific position of the impeller in the xy plane coordinate system can be calculated. Specifically: As Figure 2 shown, when the intersection points M1 and M2 of the N and S pole dividing line of the impeller and the virtual circle 1 formed by the Hall sensors do not coincide with the center point of any Hall sensor, calculate using the output voltage of each pair of Hall sensors; calculate the corresponding displacement for the first Hall sensor 5_1 and the second Hall sensor 5_2 according to where k1 is the calibration coefficient, which needs to be calibrated manually according to the actual situation, and V5_1 and V5_2 are the output voltages of the first Hall sensor 5_1 and the second Hall sensor 5_2; calculate the corresponding displacement for the third Hall sensor 5_3 and the fourth Hall sensor 5_4 according to ; calculate the corresponding displacement for the fifth Hall sensor 5_5 and the sixth Hall sensor 5_6 according to . Arbitrarily select 2 displacement data from , , , and obtain the specific position of the impeller in the xy plane coordinate system according to coordinate transformation.
[0024] For example, if , are selected, the data and in the 120° coordinate system can be converted into the displacement data Px and Py in the 90° coordinate system through the following formula: Px = + *cos120°; Py = *sin120°.
[0025] As Figure 3 shown, when the center point of a Hall sensor (the fifth Hall sensor 5_5 in this embodiment) coincides with the intersection point M1 of the virtual circle 1 formed by the N and S pole dividing line of the impeller and the Hall sensor, at this time, only the absolute value of the output voltage of one Hall sensor (the fifth Hall sensor 5_5 in this embodiment) is less than the set value , |V5_5| < , discard the output voltage values of the fifth Hall sensor 5_5 and the sixth Hall sensor 5_6, and calculate from the output voltages V5_1 and V5_2 of the first Hall sensor 5_1 and the second Hall sensor 5_2 to obtain , calculate from the output voltages V5_3 and V5_4 of the third Hall sensor 5_3 and the fourth Hall sensor 5_4 to obtain , according to the coordinate transformation, convert and into the displacement data Px and Py in the 90° coordinate system.
[0026] As Figure 4 shown, when the center points of two Hall sensors (the fourth Hall sensor 5_4 and the fifth Hall sensor 5_5 in this embodiment) coincide with the intersection points M1 and M2 of the virtual circle 1 formed by the N and S pole dividing line of the impeller and the Hall sensor, at this time, the absolute values of the output values of two Hall sensors are less than the set value , |V5_4| < , |V5_5| < , discard the voltages V5_4 and V5_5 output by the fourth Hall sensor 5_4 and the fifth Hall sensor 5_5, then calculate the corresponding displacement from the output voltages V5_1 and V5_2 of the first Hall sensor 5_1 and the second Hall sensor 5_2 according to , calculate the corresponding displacement from the third Hall sensor 5_3 and the sixth Hall sensor 5_6 according to , where k2 is also a calibration coefficient and needs to be manually calibrated according to the actual situation. According to the coordinate transformation, convert and into the displacement data Px and Py in the 90° coordinate system.
[0027] Through the above scheme, both the temperature drift problem of the traditional eddy current sensor can be avoided, and the misjudgment problem that occurs in the prior art when the N and S pole dividing line of the impeller passes through the center of the sensor can be avoided, and the accurate detection of the impeller displacement can be realized, the faults such as the impeller rubbing against the wall can be avoided, and the continuous and stable operation of the motor can be ensured.
Claims
1. A method for detecting the rotor displacement of a magnetic levitation pump, characterized in that: At least three pairs of relatively arranged Hall sensors are evenly distributed with the physical center of the volute as the center; First, collect the detection data of n pairs of Hall sensors, where n≥3; Then, the collected data is screened to determine whether the impeller is at the physical center; when the center point of the Hall sensor coincides with the N / S pole dividing line of the impeller, and the impeller is at the physical center, the distances between the two relatively arranged Hall sensors and the impeller are the same, and the detected magnetic field intensities are also the same, but with opposite signs. Assuming that the amplitudes detected by the nth pair of Hall sensors are Vn1 and Vn2 respectively, at this time ; there is no need to calculate the displacement of the impeller center; When the impeller is not at the physical center, the distances between the same pair of Hall sensors and the impeller are different, and the detected magnetic field intensities are also different, but the signs are still opposite. If , it means that the impeller is close to the Hall sensor that outputs Vn1. If , it means that the impeller is close to the Hall sensor that outputs Vn2; displacement calculation of the impeller center is required. Finally, calculate the specific position of the impeller in the xy plane coordinate system through the output data of the remaining Hall sensors and in combination with the preset calibration coefficient.
2. The method for detecting the rotor displacement of a magnetic levitation pump according to claim 1, characterized in that: The specific determination method for whether the impeller is at the physical center is as follows: Compare the output value of the Hall sensor with the set value and is a very small value close to zero. If the absolute value of the output value of the Hall sensor is less than , it indicates that the center point of the Hall sensor corresponding to the value coincides with the N and S pole dividing line of the impeller; if the absolute value of the output value of the Hall sensor is greater than or equal to , it indicates that the center point of the Hall sensor corresponding to the value does not coincide with the N and S pole dividing line of the impeller.
3. The method for detecting the rotor displacement of a magnetic levitation pump according to claim 1, characterized in that: The calculation process of the impeller center displacement is as follows: When the absolute values of the output values of all Hall sensors are greater than or equal to the set value , the output data of each pair of Hall sensors are used for calculation, and the displacement detected by the nth pair of Hall sensors is defined as , where k1 is the calibration coefficient, representing and correspondence, which needs to be calibrated according to the actual situation; Vn1 and Vn2 are the output values of a pair of Hall sensors; any two displacement data and are taken, and according to the coordinate transformation, the specific position of the impeller in the xy coordinate system of the plane is obtained; When the absolute value of the output value of only one Hall sensor is less than the set value the data of this sensor and the sensor at its relative position are discarded, and the displacements detected by the remaining Hall sensors are still defined as Arbitrarily select two displacement data and According to the coordinate transformation, the specific position of the impeller in the xy coordinate system of the plane is obtained; When the absolute values of the detected values Vp_1 and Vq_1 of both Hall sensors are less than the set value , the data detected by these two sensors are discarded, and the displacements detected by the sensors paired with these two sensors are calculated according to . Here, k2 is also a calibration coefficient, representing the corresponding relationship with , which also needs to be calibrated according to the actual situation. The displacements detected by the remaining Hall sensors are still calculated according to . Arbitrarily select two displacement data and or arbitrarily select one displacement data and . According to the coordinate transformation, the specific position of the impeller in the xy coordinate system of the plane is obtained.