Induction motor speed measuring device
By designing an induction motor speed measurement device including a main body, a detection probe and a magnetic sensor, the problems of weak magnetic field signal, large device and high cost in the prior art are solved, and the motor speed measurement with high accuracy and flexibility are achieved .
Patent Information
- Application Number
- CN202420606772.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-27
- Publication Date
- 2025-02-07
- Estimated Expiration
- 2034-03-27
AI Technical Summary
When measuring the motor speed measurement device of the existing induction motor, it is necessary to place an induction sensor close to the motor shaft, resulting in weak magnetic field signals and difficult to detect; at the same time, the device has a large size, high cost, complex algorithms and high computing capabilities.
A speed measurement device for induction motor is designed, including a main body, a detection probe and a magnetic sensor. The magnetic sensor is arranged at the far end of the detection probe to obtain the motor air gap leakage magnetic field signal and is sent to the calculation unit through the signal conditioning circuit, which calculates the motor speed based on these signals. The detection probe is scalable and suitable for different scenarios.
The device structure is simplified, manufacturing costs are reduced, measurement accuracy and flexibility are improved, and suitable for different working scenarios.
Smart Images
Figure CN222439525U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of induction motor speed measurement, and in particular to an induction motor speed measurement device. Background Art
[0002] In industrial applications, motor speed is crucial for condition monitoring and fault diagnosis of induction motors, but in many cases it is difficult to obtain the actual speed of the motor.
[0003] If the rotating parts of the motor are visible from the outside, the motor speed can be measured by a tachometer, but this method is not suitable for motors whose rotating parts are not exposed to the outside. Therefore, measuring the leakage flux of the motor and obtaining the motor speed after signal processing is a better way to measure the motor speed in scenarios where the rotating parts are not exposed.
[0004] In the related technical field, the induction sensor detects the leakage magnetic field at the end of the motor, extracts the synchronous frequency and slip frequency, and then obtains the motor speed. The motor speed detection in the related field mainly has the following problems:
[0005] First, since the magnetic field at the motor shaft end needs to be measured, the inductive sensor needs to be placed on the end cover close to the motor shaft. Usually, the non-drive end of the motor is equipped with a cooling fan, while the drive end of the motor is connected to the pump or blower load, which causes the measurement point to be far away from the stator and rotor of the motor, and the magnetic field signal is weak and not easy to detect.
[0006] Second, inductive sensors typically contain hundreds or even thousands of turns of copper wire to obtain a sufficiently strong voltage signal from a weak magnetic field, resulting in a large speed measuring device that requires custom manufacturing and is costly.
[0007] In addition, some induction motor speed measuring devices in the related art need to obtain vibration signals and leakage magnetic signals to obtain the rotational speed, which makes the speed measuring device more complicated, requires higher computing power of the computing unit, and has a more complicated algorithm. Utility Model Content
[0008] In order to solve the above technical problems, the present application provides an induction motor speed measuring device.
[0009] The embodiment of the present application provides an induction motor speed measuring device including: a main body, a detection probe and a magnetic sensor. The main body accommodates a calculation unit; the detection probe is arranged on the main body; the magnetic sensor is arranged at one end of the detection probe away from the main body, and the magnetic sensor is used to obtain the motor air gap leakage magnetic field signal and send it to the calculation unit through a signal conditioning circuit. The calculation unit calculates the motor speed based on the motor air gap leakage magnetic field signal.
[0010] According to some embodiments of the present application, the detection probe is in the shape of a thin rod, and one end of the detection probe along its own length direction is arranged on the main body.
[0011] According to some embodiments of the present application, the detection probe is retractable along its own length.
[0012] According to some embodiments of the present application, the induction motor speed measuring device further includes a display screen, which is disposed on the main body and is used to display the motor speed calculated by the calculation unit.
[0013] According to some embodiments of the present application, the induction motor speed measuring device further includes a control switch for controlling the opening and closing of the induction motor speed measuring device.
[0014] The embodiment of the present application also provides an induction motor speed measuring device, comprising: a magnetic sensing unit and a computing unit. The magnetic sensing unit is configured to obtain a motor air gap leakage magnetic field signal; the computing unit is configured to receive the motor air gap leakage magnetic field signal obtained by the magnetic sensing unit through a signal conditioning circuit; and the computing unit calculates the motor speed based on the motor air gap leakage magnetic field signal.
[0015] According to some embodiments of the present application, the calculation unit is configured to obtain the stator synchronous frequency and the eccentric sideband frequency through Fourier transform based on the motor air gap leakage magnetic field signal.
[0016] According to some embodiments of the present application, the calculation unit is configured to use the formula:
[0017] n=60·|f s -f ecc1or2 |Calculate the motor speed, where f s is the stator synchronous frequency, f ecc1or2 is the eccentric sideband frequency.
[0018] According to some embodiments of the present application, the induction motor speed measuring device further includes a display unit configured to display the motor speed calculated by the calculation unit.
[0019] According to some embodiments of the present application, the induction motor speed measuring device further includes a power management unit configured to provide or disconnect power to the magnetic sensing unit, the computing unit, and the signal conditioning circuit.
[0020] With the induction motor speed measuring device of the present application, a detection probe with a magnetic sensor is provided on the main body, and there is no need to provide additional vibration signal sensors, etc., so the structure is simple and the manufacturing cost is low. In addition, due to the simple structure, the induction motor speed measuring device can be manufactured to be more portable and compact. For example, the main body is designed as a grip-type structure, which is convenient for the staff to hold and operate. The magnetic sensor can adopt a Hall sensor. The detection probe is small in size and is easier to be placed between the two heat dissipation ribs of the motor for testing. A relatively strong air gap leakage magnetic field signal can be obtained for processing, so that the magnetic sensor can more easily obtain the signal and can improve the accuracy of the measurement. In addition, the detection probe can be designed to be retractable, and the length of the detection probe can be adjusted as needed, which improves the flexibility of the use of the induction motor speed measuring device and can be suitable for different working scenarios. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0022] Figure 1 A schematic structural diagram of an induction motor speed measuring device according to an embodiment of the present application is shown;
[0023] Figure 2 shows A structural block diagram of an induction motor speed measuring device according to an embodiment of the present application is shown; and
[0024] Figure 3 A schematic diagram of a frequency spectrum obtained by Fourier transforming an air gap leakage magnetic field signal of a motor according to an embodiment of the present application is shown. DETAILED DESCRIPTION
[0025] In order to make the purpose, technical scheme and advantages of the embodiments of the present disclosure clearer, the technical scheme of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the described embodiments of the present application, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of this application.
[0026] According to an embodiment of the present application, an induction motor speed measuring device is provided. The induction motor speed measuring device is used to measure the rotation speed of the induction motor.
[0027] Figure 1 FIG. 2 shows a schematic diagram of the structure of an induction motor speed measuring device according to an embodiment of the present application. Figure 1As shown, the induction motor speed measuring device includes a main body 1, a detection probe 2 and a magnetic sensor 3. The main body 1 contains a calculation unit. The detection probe 2 is arranged on the main body 1. The magnetic sensor 3 is arranged at one end of the detection probe 2 away from the main body 1, and the magnetic sensor 3 is used to obtain the motor air gap leakage magnetic field signal and send it to the calculation unit through a signal conditioning circuit. The calculation unit calculates the motor speed n based on the motor air gap leakage magnetic field signal.
[0028] The motor air gap leakage magnetic field signal is a leakage magnetic field signal between the stator and the rotor of the motor. The calculation unit can perform Fourier transform (FFT) on the motor air gap leakage magnetic field signal obtained by the magnetic sensor 3, and obtain the stator synchronous frequency and the eccentric sideband frequency by analysis, so as to calculate the motor speed n.
[0029] Through the above scheme, the magnetic sensor 3 can adopt a Hall sensor, and there is no need to set up additional vibration signal sensors, etc. Only the magnetic sensor 3 needs to be set up, so that the structure of the detection probe 2 can be simplified, the volume of the detection probe 2 can be smaller, and the manufacturing cost can be reduced.
[0030] In addition, the main body 1 can also be designed as a handle-type structure to facilitate workers to hold and operate.
[0031] In some optional embodiments, the detection probe 2 is in the shape of a thin rod, one end of the detection probe 2 along its own length direction is arranged on the main body 1, and the magnetic sensor 3 is arranged at the end of the detection probe 2 away from the main body 1.
[0032] Through the above scheme, the thin rod-shaped probe 2 is easier to be placed between the two heat dissipation ribs of the motor for testing, and a relatively strong air gap leakage magnetic field signal can be obtained for processing, making it easier for the magnetic sensor 3 to obtain the signal and improving the measurement accuracy.
[0033] In some optional embodiments, the detection probe 2 can also be designed to be retractable along its own length direction. For example, the shell structure of the detection probe 2 is formed by a multi-stage tubular structure sleeve, and can also be a retractable structure made of elastic retractable deformation material. Of course, the detection probe 2 can also be designed as other structures that are retractable along its own length direction, which is not limited here.
[0034] Through the above solution, the length of the detection probe 2 can be adjusted as needed, which improves the flexibility of the use of the induction motor speed measuring device and can be applied to different working scenarios.
[0035] In some optional embodiments, the induction motor speed measuring device may further include a display screen 4, which is disposed on the main body 1 and is used to display the motor speed n calculated by the calculation unit. In this way, the induction motor speed measuring device can integrate the magnetic sensor 3 for acquiring signals, the calculation unit for calculating and analyzing signals, and the display screen 4 for displaying the motor speed, so that the staff can obtain the motor speed n in a timely and intuitive manner, which is convenient to use.
[0036] In some other embodiments, the induction motor speed measuring device may also be externally connected to other display devices or data processing devices, so that the obtained motor speed n data is output to other external devices for display or further data processing.
[0037] In some optional embodiments, the induction motor speed measuring device further comprises a control switch 5 for controlling the opening and closing of the induction motor speed measuring device. The control switch 5 can be arranged on the main body 1 to facilitate the staff to operate the opening or closing device.
[0038] According to an embodiment of the present application, an induction motor speed measuring device is also provided. Figure 2 shows FIG. 1 is a block diagram of a device for measuring speed of an induction motor according to an embodiment of the present application. Figure 2 The induction motor speed measuring device includes a magnetic sensing unit 10 and a calculation unit 20. The magnetic sensing unit 10 is configured to obtain a motor air gap leakage magnetic field signal; the calculation unit 20 is configured to receive the motor air gap leakage magnetic field signal obtained by the magnetic sensing unit 10 through a signal conditioning circuit 30; and the calculation unit 20 calculates the motor speed n based on the motor air gap leakage magnetic field signal.
[0039] The magnetic sensing unit 10 may be a magnetic sensor 3 , the computing unit 20 may be disposed in the main body 1 , and the signal conditioning circuit 30 may connect the magnetic sensing unit 10 and the computing unit 20 through the main body 1 and the detection probe 2 .
[0040] Further, Figure 3 FIG. 2 shows a schematic diagram of a spectrum obtained by Fourier transforming a motor air gap leakage magnetic field signal according to an embodiment of the present application. Figure 3 As shown, the calculation unit 20 is configured to obtain the stator synchronous frequency f based on the motor air gap leakage magnetic field signal through Fourier transform (FFT) s , eccentric sideband frequency f ecc1 and f ecc2 .
[0041] Further, the calculation unit 20 is configured to use the formula:
[0042] n=60·|fs-fecc1or2 |
[0043] Calculate the motor speed n.
[0044] Among them, the frequency f is in seconds -1 , the speed n is in r / min, so the motor speed n is the stator synchronous frequency f s With the eccentric sideband frequency f ecc1 (or f ecc2 )Multiply the absolute value of the difference by the second-minute conversion factor of 60.
[0045] In addition, if Figure 3 As shown, the eccentric sideband frequency f ecc1 and f ecc2 Synchronous frequency with stator f s equidistant, therefore, the stator synchronous frequency f s and the eccentric sideband frequency f ecc1 The absolute value of the stator synchronous frequency f s and the eccentric sideband frequency f ecc2 The absolute value of is equal. In the above formula, f ecc1or2 Meaning the eccentric sideband frequency f ecc1 and f ecc2 You can select any one of them to enter into the calculation without affecting the result.
[0046] In some optional embodiments, the induction motor speed measuring device further includes a display unit 40, which is configured to display the motor speed n calculated by the calculation unit 20. The display unit 40 may be a display screen 4, which is arranged on the main body 1. The display unit 40 may also be an external display device. In this way, the staff can obtain the motor speed n in a timely and intuitive manner, which is convenient to use.
[0047] In some optional embodiments, the induction motor speed measuring device further includes a power management unit 50, which is configured to provide or disconnect power to the magnetic sensor unit 10, the calculation unit 20, and the signal conditioning circuit 30. Of course, the power management unit 50 can also provide or disconnect power to the display unit 40.
[0048] The power management unit 50 may include a power supply unit and a control switch 5. The power supply unit of the power management unit 50 may be integrated inside the main body 1 so that the induction motor speed measuring device provides power by itself, or may be an external power supply device. The control switch 5 may be arranged on the main body 1 to facilitate the staff to operate the device to open or close.
[0049] With the induction motor speed measuring device of the present application, a detection probe 2 with a magnetic sensor 3 is arranged on the main body 1, and there is no need to arrange a vibration signal sensor or the like separately, so the structure is simple and the manufacturing cost is low. In addition, due to the simple structure, the induction motor speed measuring device can be made more portable and compact, for example, the main body 1 is designed as a grip-type structure, which is convenient for the staff to hold and operate. The magnetic sensor 3 can be a Hall sensor, and the detection probe 2 is small in size and is easier to be placed between the two heat dissipation ribs of the motor for testing. A relatively strong air gap leakage magnetic field signal can be obtained for processing, so that the magnetic sensor 3 is easier to obtain a signal and the measurement accuracy can be improved. In addition, the detection probe 2 can be designed to be retractable, and the length of the detection probe 2 can be adjusted as needed, which improves the flexibility of the use of the induction motor speed measuring device and can be applied to different working scenarios.
[0050] Although possible embodiments are described by way of example in the above description, it should be understood that there are still a large number of variations of embodiments through the combination of all known and other technical features and embodiments that are easily conceivable to the skilled person. It should also be understood that the exemplary embodiment is only an example and that such an embodiment in no way limits the scope of protection, application and configuration of the present application. The above description is more to provide the skilled person with a technical guide for converting at least one exemplary embodiment, wherein various changes can be made, especially changes in the functions and structures of the components, as long as they do not depart from the scope of protection of the claims.
[0051] Reference numerals list
[0052] 1. Main body; 2. Detection probe; 3. Magnetic sensor; 4. Display; 5. Control switch;
[0053] 10. Magnetic sensing unit; 20. Calculation unit; 30. Signal conditioning circuit; 40. Display unit;
[0054] 50.Power management unit.
Claims
1. An induction motor speed measuring device, characterized in that: include A main body (1) containing a computing unit; A detection probe (2) is arranged on the main body (1); and A magnetic sensor (3), which is arranged at one end of the detection probe (2) away from the main body (1), and the magnetic sensor (3) is used to obtain a motor air gap leakage magnetic field signal and send it to the calculation unit through a signal conditioning circuit; The calculation unit calculates the motor speed (n) based on the motor air gap leakage magnetic field signal.
2. The induction motor speed measuring device according to claim 1, characterized in that: The detection probe (2) is in the shape of a thin rod, and one end of the detection probe (2) along its own length direction is arranged on the main body (1).
3. The induction motor speed measuring device according to claim 2, characterized in that: The detection probe (2) is retractable along its own length direction.
4. The induction motor speed measuring device according to claim 1, characterized in that: Also includes A display screen (4) is arranged on the main body (1) and is used to display the motor speed (n) calculated by the calculation unit.
5. The induction motor speed measuring device according to claim 1, characterized in that: Also includes A control switch (5) is used to control the opening and closing of the induction motor speed measuring device.
6. An induction motor speed measuring device, characterized in that: include A magnetic sensor unit (10) configured to obtain a leakage magnetic field signal of an air gap of a motor; as well as A calculation unit (20) is configured to receive the motor air gap leakage magnetic field signal acquired by the magnetic sensor unit (10) through a signal conditioning circuit (30); and the calculation unit (20) calculates the motor speed (n) based on the motor air gap leakage magnetic field signal.
7. The induction motor speed measuring device according to claim 6, characterized in that: Also includes A display unit (40) is configured to display the motor speed (n) calculated by the calculation unit (20).
8. The induction motor speed measuring device according to claim 6, characterized in that: Also includes A power management unit (50) is configured to provide or cut off power to the magnetic sensing unit (10), the computing unit (20) and the signal conditioning circuit (30).