A speed detection system for an electric motor, an electric motor

Abstract

This disclosure provides a speed detection system for an electric motor and an electric motor. The speed detection system includes: a speed measuring reference component; a speed measuring rotor, the first end of which is connected to the rotor of the motor so that the speed measuring rotor can rotate synchronously with the rotor; a second end of the speed measuring rotor is correspondingly disposed with the speed measuring reference component, and the second end of the speed measuring rotor has a diameter of different lengths; wherein, during the rotation of the speed measuring rotor, a periodically changing distance is formed between the outer peripheral surface of the second end of the speed measuring rotor and the speed measuring reference component; a distance detection device configured to detect the distance data between the outer peripheral surface of the second end of the speed measuring rotor and the speed measuring reference component, and convert the distance data into a corresponding electrical signal; and a main control chip, including a speed calculation unit configured to calculate the rotor speed based on the distance data. This speed detection system can accurately measure the motor speed, has a simple structure, and a large measurement range.

Description

Technical Field

[0001] This disclosure relates to the field of motor-related technologies, and in particular to a speed detection system for an electric motor and an electric motor. Background Technology

[0002] In related technologies, speed sensors with custom magnetic circuits are typically used to detect the rotational speed of magnetic levitation motors. When using a speed sensor with a custom magnetic circuit to detect the rotor speed of a magnetic levitation motor, the magnetic signal generated during rotor operation is first received and converted into a voltage signal. This voltage signal is then filtered and digitized to determine the motor's rotational speed. However, this detection method also has some limitations. For example, it is restricted by the frequency limit of the speed sensor, making it impossible to accurately detect the rotational speed signal of a high-speed magnetic levitation motor. Furthermore, when detecting the speed signal using digital signals, the rotational speed is determined based on the switching frequency of the speed sensor, which is susceptible to signal interference from the external environment. Summary of the Invention

[0003] The following is an overview of the subject matter described in detail in this disclosure. This overview is not intended to limit the scope of the claims.

[0004] This disclosure provides a speed detection system for an electric motor and an electric motor.

[0005] According to a first aspect of the present disclosure, a speed detection system for a motor is provided, the speed detection system comprising:

[0006] Speed ​​measuring reference components;

[0007] A speed measuring rotor, the first end of which is connected to the rotor of the motor so that the speed measuring rotor can rotate synchronously with the rotor; the second end of the speed measuring rotor is correspondingly set with the speed measuring reference component, and the second end of the speed measuring rotor has a diameter of different lengths; wherein, during the rotation of the speed measuring rotor, a periodically changing gap is formed between the outer peripheral surface of the second end of the speed measuring rotor and the speed measuring reference component.

[0008] The distance detection device is configured to detect the distance data between the outer peripheral surface of the second end of the speed measuring rotor and the speed measuring reference element, and convert the distance data into a corresponding electrical signal.

[0009] The main control chip includes a speed calculation unit configured to calculate the rotational speed of the rotor based on the spacing data.

[0010] According to some embodiments of this disclosure, the speed measuring reference component includes: a speed measuring stator, which is sleeved on the second end of the speed measuring rotor.

[0011] According to some embodiments of this disclosure, the distance detection device is disposed on the inner peripheral wall of the velocimeter stator.

[0012] According to some embodiments of this disclosure, the second end of the speed measuring rotor adopts an elliptical columnar structure.

[0013] According to some embodiments of this disclosure, the major axis of the second end of the speed measuring rotor is coplanar with the magnetic pole boundary line of the rotor; or, the minor axis of the second end of the speed measuring rotor is coplanar with the magnetic pole boundary line of the rotor.

[0014] According to some embodiments of this disclosure, the distance detection device includes:

[0015] An infrared ranging sensor assembly is disposed on the inner peripheral wall of the velocity measuring stator, and the infrared ranging sensor assembly is used to collect the distance data;

[0016] The signal acquisition module is configured to acquire the spacing data and convert it into a corresponding electrical signal.

[0017] According to some embodiments of this disclosure, the infrared ranging sensor assembly includes: a first infrared ranging sensor and a second infrared ranging sensor.

[0018] The angle between the installation positions of the first infrared ranging sensor and the second infrared ranging sensor and the axis of the velocity measuring stator is 90°.

[0019] According to some embodiments of this disclosure, the speed calculation unit includes:

[0020] A filtering module is configured to filter the electrical signal.

[0021] The bias processing module is configured to bias the electrical signal processed by the filtering processing module.

[0022] The amplification processing module is configured to amplify the electrical signal processed by the bias processing module.

[0023] The rotational speed calculation module is configured to calculate the period of the electrical signal processed by the amplification processing module, and calculate the rotational speed of the rotor based on the period.

[0024] According to a second aspect of the present disclosure, a motor is provided, the motor including the speed detection system described in the above embodiments of the present disclosure.

[0025] According to some embodiments of this disclosure, the motor includes: a housing, a rotor disposed within the housing, and a speed measuring reference element disposed on the housing.

[0026] Beneficial Effects: This disclosure presents a motor speed detection system. It utilizes the periodic distance changes between the speed-measuring rotor and the speed-measuring reference component as the rotor rotates. A distance detection device detects these changes in distance, and a speed calculation module calculates the motor's rotational speed. This speed detection system accurately measures motor speed, has a simple structure, and a large measurement range, making it suitable for measuring the speed of high-speed motors.

[0027] After reading and understanding the accompanying diagrams and detailed descriptions, other aspects can be understood. Attached Figure Description

[0028] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of these embodiments. In these drawings, similar reference numerals are used to denote similar elements. The drawings described below are some embodiments of the present disclosure, but not all embodiments. Other drawings will be readily available to those skilled in the art based on these drawings without inventive effort.

[0029] Figure 1 This is a schematic diagram of a motor speed detection system according to an exemplary embodiment;

[0030] Figure 2 This is a schematic diagram of the rotor assembly of a speed measuring rotor and a motor, according to an exemplary embodiment.

[0031] Figure 3 This is a schematic diagram illustrating the engagement state of the speed measuring stator and the speed measuring rotor according to an exemplary embodiment;

[0032] Figure 4 It is a graph showing the correspondence between an electrical signal and a rotation angle according to an exemplary embodiment;

[0033] Figure 5 This is a flowchart illustrating the electrical signal processing of a speed detection system according to an exemplary embodiment;

[0034] Figure 6 It is a graph showing the relationship between the biased electrical signal and the rotation angle according to an exemplary embodiment;

[0035] Figure 7 It is a graph showing the relationship between an amplified electrical signal and a rotation angle, according to an exemplary embodiment.

[0036] In the diagram: 11. Speed ​​measuring rotor; 12. Speed ​​measuring stator; 13. Distance detection device; 131. First infrared ranging sensor; 132. Second infrared ranging sensor; 14. Main control chip; 20. Rotor. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions in the disclosed embodiments will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this disclosure can be arbitrarily combined with each other.

[0038] With the widespread application of magnetic levitation motors, precise measurement of their rotational speed is often required. In related technologies, speed sensors with custom magnetic circuits are typically used to detect the rotational speed of magnetic levitation motors. When using a speed sensor with a custom magnetic circuit to detect the rotor speed of a magnetic levitation motor, the magnetic signal generated by the rotor during operation is first received and converted into a voltage signal. This voltage signal is then filtered and digitized to determine the rotational speed. However, the detection of the rotational speed of a magnetic levitation motor is limited by the frequency limit of the speed sensor, making it impossible to accurately detect the rotational speed signal of a high-speed magnetic levitation motor. Furthermore, when detecting the speed signal using digital signals, the rotational speed is determined based on the switching frequency of the speed sensor, which is susceptible to signal interference from the external environment.

[0039] Based on this, this disclosure proposes a speed detection system capable of accurately detecting the rotational speed of a magnetic levitation motor. This speed detection system utilizes the periodic changes in distance between the speed-measuring rotor and the speed-measuring reference element as the rotor rotates. A distance detection device detects these changes in distance, and a speed calculation module calculates the motor's rotational speed. This speed detection system accurately measures motor speed, has a simple structure, and a large measurement range, making it suitable for measuring the speed of motors with relatively high rotational speeds. It should be noted that this speed detection system can also be used for other conventional motors.

[0040] The present disclosure will now be described in conjunction with the accompanying drawings and specific embodiments.

[0041] Exemplary embodiments of this disclosure provide a speed detection system for a motor, such as... Figure 1 As shown, Figure 1 This is a schematic diagram of a motor speed detection system according to an exemplary embodiment. The motor speed detection system includes: a speed measuring reference element, a speed measuring rotor 11, a distance detection device 13, and a main control chip 14.

[0042] like Figure 2 As shown, Figure 2 This is a schematic diagram of the rotor assembly of a speed measuring rotor and a motor according to an exemplary embodiment. The first end of the speed measuring rotor 11 is connected to the rotor 20 so that the speed measuring rotor 11 can rotate synchronously with the rotor 20; the second end of the speed measuring rotor 11 is correspondingly provided with a speed measuring reference component, and the second end of the speed measuring rotor 11 has a diameter of different lengths; wherein, during the rotation of the speed measuring rotor 11, a periodically changing gap is formed between the outer peripheral surface of the second end of the speed measuring rotor 11 and the speed measuring reference component.

[0043] The distance detection device 13 is configured to detect the distance data between the outer peripheral surface of the second end of the speed measuring rotor 11 and the speed measuring reference element, and convert the distance data into a corresponding electrical signal.

[0044] The main control chip 14 includes a speed calculation unit, which is configured to calculate the rotational speed of the rotor 20 based on the spacing data.

[0045] In this exemplary embodiment, a motor speed detection system can accurately measure the rotational speed of the motor rotor 20. The detection principle of this system is as follows: based on the different diameters at the second end of the speed-measuring rotor 11, and connecting the first end of the speed-measuring rotor 11 to the motor rotor 20, the second end of the speed-measuring rotor 11 rotates synchronously with the motor rotor 20 during rotation. At this time, a periodically changing distance occurs between the outer circumferential surface of the second end of the speed-measuring rotor 11 and the speed-measuring reference component. The distance detection device 13 then detects this distance change between the speed-measuring reference component and the speed-measuring rotor 11, thus acquiring the distance data between the outer circumferential surface of the second end of the speed-measuring rotor 11 and the speed-measuring reference component. Finally, the speed calculation module in the main control chip 14 calculates the rotational speed of the motor rotor 20. This speed detection system not only accurately measures the rotational speed of the motor rotor 20, but also has a simple structure, a large measurement range, and is suitable for measuring the speed of motors with relatively high rotational speeds.

[0046] In some exemplary embodiments, considering that the speed measuring reference component is a structural component fixed relative to the motor and needs to maintain an appropriate distance from the speed measuring rotor 11, the speed measuring reference component can be constructed as a speed measuring stator 12 located at the second end of the speed measuring rotor 11. This not only facilitates installation and fixation but also avoids the risks caused by the exposure of the second end of the speed measuring rotor 11.

[0047] For example, such as Figure 3 As shown, Figure 3This is a schematic diagram illustrating the mating state of a speed-measuring stator and a speed-measuring rotor according to an exemplary embodiment. The speed-measuring reference component includes a speed-measuring stator 12, which is sleeved on the second end of the speed-measuring rotor 11. The speed-measuring stator 12 adopts a cylindrical structure, which, after being sleeved on the second end of the speed-measuring rotor 11, not only maintains a sufficiently large clearance between itself and the second end of the speed-measuring rotor 11, but also occupies less space within the motor.

[0048] In some exemplary embodiments, based on the design of the speed measuring reference element as a speed measuring stator 12, in order to facilitate the distance detection device 13 to measure the distance between the speed measuring stator 12 and the outer peripheral surface of the second end of the speed measuring rotor 11, the distance detection device 13 can be set on the inner peripheral wall of the speed measuring stator 12.

[0049] In this exemplary embodiment, the test stator can be provided with a preset number of fixing holes and fixed to the motor housing by a corresponding number of fasteners such as screws or pins. To avoid affecting the movement space of the motor rotor 20, the minimum gap between the speed measuring stator 12 and the speed measuring rotor 11 is greater than the gap between the magnetic levitation bearing of the motor and the motor rotor.

[0050] In some exemplary embodiments, considering that the second end of the speed measuring rotor 11 rotates synchronously with the rotor 20 of the motor, if the second end of the speed measuring rotor 11 has an irregular structure, a large centrifugal force will be generated, increasing the vibration of the motor. To prevent or reduce the vibration of the motor, the second end of the speed measuring rotor 11 needs to adopt a more regular shape, and the distance between the outer circumferential surface of the second end of the speed measuring rotor 11 and the central axis of the speed measuring rotor 11 cannot be equal, that is, the second end of the speed measuring rotor 11 has a diameter of different lengths. For example, the radial section around the second end of the speed measuring rotor 11 is symmetrical about the central axis of the speed measuring rotor 11. For example, the second end of the speed measuring rotor 11 adopts an elliptical columnar structure. It should be noted that the second end of the speed measuring rotor 11 can also adopt other regular shapes such as a rectangular columnar structure, that is, the second end of the speed measuring rotor 11 can cause a change in distance between the outer circumferential surface of the second end of the speed measuring rotor 11 and the speed measuring reference element during rotation, without causing an increase in vibration of the rotor 20 of the motor during rotation.

[0051] In this exemplary embodiment, the speed measuring rotor 11 can be provided with a preset number of fixing holes and connected to the rotor 20 of the motor by a corresponding number of fasteners such as screws or pins.

[0052] In some exemplary embodiments, considering that the rotor 20 of the motor needs to determine the magnetic poles before starting, the second end of the speed measuring rotor 11 can be used to determine the magnetic pole positions of the rotor 20 to facilitate finding them. For example, when the second end of the speed measuring rotor 11 adopts an elliptical cylindrical structure, the major axis of the second end of the speed measuring rotor 11 can be coplanar with the magnetic pole boundary line of the rotor 20; or, the minor axis of the second end of the speed measuring rotor 11 can be coplanar with the magnetic pole boundary line of the rotor 20.

[0053] In this exemplary embodiment, by associating the magnetic pole position of the motor rotor 20 with the highest point of the major axis or the highest point of the minor axis of the ellipse, that is, when the highest point of the minor axis or the highest point of the major axis of the ellipse is detected during the rotation of the rotor 20, it corresponds exactly to the magnetic pole boundary line of the rotor 20, and this feedback is given to the motor controller. Before the rotor 20 of the drive motor rotates, it is no longer necessary to use a frequency converter to determine the magnetic pole.

[0054] In some exemplary embodiments, the distance detection device 13 includes: an infrared ranging sensor assembly disposed on the inner peripheral wall of the velocimeter stator 12, the infrared ranging sensor assembly being used to collect distance data and convert the distance data into corresponding electrical signals; and a signal acquisition module configured to acquire the corresponding electrical signals. Exemplarily, the infrared ranging sensor assembly includes: an infrared ranging sensor. The infrared position sensor transmits the electrical signal to the signal acquisition module via a signal line. The signal acquisition module performs preliminary filtering on the signal, amplifies it, and then transmits the electrical signal to the main control chip 14. This method of collecting and transmitting distance data can effectively resist interference.

[0055] In this exemplary embodiment, the infrared position sensor can convert the distance signal between the motor rotor 20 and itself into an electrical signal, U = KX + B, using a non-contact method. K and B are constants, X is the distance between them, and U is the voltage signal.

[0056] To improve the reliability of the speed detection system, the infrared ranging sensor assembly includes a first infrared ranging sensor 131 and a second infrared ranging sensor 132. The installation positions of the first infrared ranging sensor 131 and the second infrared ranging sensor 132 form a 90° angle with respect to the axis of the speed measuring stator 12. Using two identical infrared position sensors provides redundancy. Since the sensors are installed inside the motor, which has high stability requirements, the system can continue to operate normally even if one fails, allowing for maintenance later.

[0057] Based on the two infrared ranging sensors, the speed detection system can also determine the rotational position of the motor rotor 20. According to the different values ​​returned by the collected distance data, the current rotational position of the rotor can be determined.

[0058] In some exemplary embodiments, the speed calculation unit in the main control chip 14 includes: a filtering module configured to filter the electrical signal; a biasing module configured to bias the electrical signal processed by the filtering module; an amplification module configured to amplify the electrical signal processed by the biasing module; and a rotational speed calculation module configured to calculate the period of the electrical signal processed by the amplification module and calculate the rotational speed of the rotor 20 based on the period.

[0059] In this exemplary embodiment, the main control chip 14 analyzes the collected distance data. According to the polar coordinate formula for an ellipse, the correspondence between the distance X and the rotation angle α of the rotor 20 is as follows:

[0060]

[0061] Where R is the distance between the infrared position sensor and the center of the rotor, a is the length of the major axis of the ellipse, and b is the length of the minor axis of the ellipse.

[0062] After calculation based on the above relationship, the curve showing the correspondence between the electrical signal corresponding to the distance data and the rotation angle can be obtained, such as... Figure 4 As shown.

[0063] In this exemplary embodiment, after the main control chip 14 acquires the aforementioned electrical signal, it processes the electrical signal through software. The processing procedure is as follows: Figure 5 As shown. The processing includes: filtering, biasing, and amplification, where the electrical signal after biasing is as follows. Figure 6 As shown, the amplified electrical signal is as follows: Figure 7 As shown. The processed electrical signal is calculated by the speed calculation unit. From the calculated period T, the frequency f of the electrical signal can be derived.

[0064]

[0065] The actual speed n of the motor can be calculated from the frequency of the electrical signal.

[0066] n = 2 × f × 60

[0067] This motor speed detection system overcomes the limitation of conventional speed sensors' upper frequency range on the measured motor speed, making it more suitable for high-speed suspension motors; through the above... Figure 5 The process in this paper processes electrical signals, eliminating the need for traditional signal amplification circuits and reducing hardware costs.

[0068] This disclosure provides an exemplary embodiment of an electric motor that includes the speed detection system described in the exemplary embodiment of this disclosure. The motor includes: a housing, a rotor 20 disposed within the housing, and a speed measuring reference element disposed on the housing.

[0069] The motor in this disclosure, equipped with the aforementioned speed detection system, can detect the speed of its rotor 20 operating at a relatively high speed, and processes the electrical signal using the above method, eliminating the need for complex signal filtering and amplification circuits. The infrared distance sensor used in the speed detection system of this disclosure provides a non-contact measurement method for the rotor 20 speed of the motor, making it widely applicable, including for levitation motors such as magnetic levitation and air levitation motors.

[0070] This speed detection system acquires electrical signals transmitted by an infrared distance sensor in real time, and then performs calculations using algorithms within the main control chip 14. Compared to traditional methods of acquiring digital signals, this improves acquisition accuracy and signal precision. This speed detection system not only solves the problem of detecting the rotational position of a magnetic levitation motor, but also enables the detection of the motor's current rotational position. Furthermore, the speed measuring rotor 11 and the motor rotor are designed separately, allowing for adaptation to different series and sizes of motor rotors without altering the structure of the speed measuring rotor 11.

[0071] In this disclosure, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase “comprising…” does not exclude the presence of additional identical elements in the article or device that includes that element.

[0072] Although preferred embodiments of the present disclosure have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this disclosure.

[0073] Obviously, those skilled in the art can make various modifications and variations to this disclosure without departing from its spirit and scope. Therefore, if such modifications and variations fall within the scope of the claims of this disclosure and their equivalents, the intent of this disclosure also includes these modifications and variations.

Claims

1. A speed detection system for an electric machine, characterized by The speed detection system comprises: a speed detection reference member; a speed detection rotor, a first end of the speed detection rotor being connected with a rotor of the motor so that the speed detection rotor can rotate synchronously with the rotor, a second end of the speed detection rotor being correspondingly arranged with the speed detection reference member, and the second end of the speed detection rotor having different lengths of diameters; wherein a periodically changing distance is formed between an outer circumferential surface of the second end of the speed detection rotor and the speed detection reference member during rotation of the speed detection rotor; the second end of the speed detection rotor adopts an elliptical columnar structure, a long axis of the second end of the speed detection rotor being coplanar with a magnetic pole boundary line of the rotor, or a short axis of the second end of the speed detection rotor being coplanar with the magnetic pole boundary line of the rotor; a distance detection device configured to detect distance data between the outer circumferential surface of the second end of the speed detection rotor and the speed detection reference member, and convert the distance data into corresponding electrical signals; a master control chip, the master control chip comprising a speed calculation unit configured to calculate a rotation speed of the rotor according to the distance data; the distance detection device comprises: an infrared distance measuring sensor assembly arranged on an inner circumferential wall of a speed detection stator, the infrared distance measuring sensor assembly being used to collect the distance data; the speed detection reference member comprises: a speed detection stator, the speed detection stator being sleeved on the second end of the speed detection rotor; the infrared distance measuring sensor assembly comprises: a first infrared distance measuring sensor and a second infrared distance measuring sensor, wherein a clamped angle formed by a mounting position of the first infrared distance measuring sensor and a mounting position of the second infrared distance measuring sensor with respect to an axis of the speed detection stator is 90°.

2. The speed detection system of an electric motor according to claim 1, characterized in that, The distance detection device is arranged on the inner circumferential wall of the speed detection stator.

3. The speed detection system of an electric motor according to claim 1, characterized in that, The distance detection device further comprises: a signal acquisition module configured to acquire the corresponding electrical signals.

4. The speed detection system of an electric motor according to claim 1, characterized in that, The speed calculation unit comprises: a filtering processing module configured to perform filtering processing on the electrical signals; an offset processing module configured to perform offset processing on the electrical signals processed by the filtering processing module; an amplification processing module configured to perform amplification processing on the electrical signals processed by the offset processing module; a rotation speed calculation module configured to calculate a period of the electrical signals processed by the amplification processing module, and calculate the rotation speed of the rotor according to the period.

5. An electric machine characterized by The motor comprises the speed detection system according to any one of claims 1-4.

6. The electric machine of claim 5, wherein, The motor comprises: a shell, the shell being arranged with the rotor inside, and the speed detection reference member being arranged on the shell.

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