Rotor for non-contact angle measurement and angle measuring and calculating method

Abstract

The invention discloses a rotor for non-contact angle measurement and an angle measuring and calculating method. The rotor comprises a cylindrical rotor body and a plurality of arc-shaped concave parts which are uniformly distributed along the peripheral surface of the cylindrical rotor body; the outline of each arc-shaped concave part is composed of an elliptical arc, the long axis size of the ellipse is equal to the outer diameter a of the rotor, the short axis size is b, and a is larger than b. The measuring and calculating method comprises the following steps: configuring a position sensor to acquire a distance d to the edge of a rotor in real time; recording the number n of signals generated by the arc-shaped concave part passing through the sensor; calculating an ellipse polar angle alpha according to the distance d in combination with an ellipse polar radius formula; calculating a mechanical angle according to alpha and n; and calculating the electrical angle by combining the motor pole pair number p. According to the invention, non-contact high-precision angle measurement is realized.

Description

A rotor for non-contact angle measurement and an angle calculation method Technical Field

[0001] This invention relates to the field of motor rotor and rotation angle measurement technology, and in particular to a rotor and angle calculation method for non-contact angle measurement. Background Technology

[0002] In the field of motor control, accurately obtaining the rotor's rotation angle is crucial for achieving high-performance vector control and speed control. Traditional methods often employ contact or shaft-mounted position sensors such as rotary transformers or photoelectric encoders. Rotary transformers typically need to be mounted on the motor shaft and rotate at the same speed as the motor, which presents problems such as frictional losses, complex installation dimension matching, and long-term reliability being affected by mechanical wear.

[0003] To address the aforementioned issues, non-contact position sensor technology has emerged. These sensors offer advantages such as no mechanical wear, long lifespan, and good environmental adaptability. Their core principle involves indirectly calculating the absolute or relative angle of the rotor by detecting changes in electromagnetic, electric, or magnetic fields as the rotor rotates. Currently, a common approach to achieving non-contact angle measurement involves machining specific physical features (such as salient poles or grooves) onto the rotor. A stationary position sensor then detects changes in physical quantities (such as distance or magnetic reluctance) caused by these features, thereby calculating the angle. Therefore, designing a rotor structure that is simple, easy to manufacture, and capable of high-precision angle calculation is crucial for improving the performance and application range of non-contact position sensors. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a rotor structure that is simple in structure, easy to process, and capable of high-precision non-contact angle measurement, as well as a corresponding angle calculation method.

[0005] To achieve the above objectives, a first aspect of the present invention provides a rotor for non-contact angle measurement, comprising: a rotor body, which is cylindrical; and a plurality of arc-shaped recesses uniformly distributed along the outer circumferential surface of the rotor body for cooperating with a non-contact position sensor to achieve angle measurement by detecting changes in the edge position of the rotor body; wherein the contour of each arc-shaped recess is formed by a quadratic curve arc, the major axis of the quadratic curve arc being equal to the outer diameter of the rotor body, and the minor axis of the quadratic curve arc being smaller than the major axis; adjacent arc-shaped recesses are smoothly connected through the outer circumferential surface of the rotor body, wherein the smooth connection means having first-order geometric continuity at least at the connection point.

[0006] Furthermore, the quadratic curve arc is an elliptical arc, the major axis of the ellipse containing the elliptical arc is equal to the outer diameter a of the rotor body, the minor axis is b, and a > b.

[0007] Furthermore, the included angle θ between the central symmetry lines of two adjacent arcuate concave portions satisfies: θ = 360° / z, where z is the total number of arcuate concave portions and z is a positive integer greater than 1.

[0008] In one embodiment, when z is an even number, the z arc-shaped recesses on the rotor body are formed based on z / 2 complete ellipses, and the elliptical contours corresponding to each arc-shaped recess are staggered sequentially by the included angle θ.

[0009] In another embodiment, when z is an odd number, the z arcuate recesses on the rotor body are formed based on z complete ellipses, and the elliptical contours corresponding to each arcuate recess are staggered sequentially by the included angle θ.

[0010] The second aspect of this invention provides a non-contact rotor angle measurement method using any of the above-mentioned rotors, comprising the following steps: S1, configuring the rotor and position sensor: mounting a rotor having z arc-shaped concave portions on a motor shaft, and fixing a non-contact position sensor at a predetermined position on the outer periphery of the rotor body, wherein the detection direction of the position sensor is perpendicular to the rotation axis of the rotor; S2, acquiring real-time detection distance: during the rotor rotation, acquiring detection signals in real time through the position sensor, and converting the signals into a real-time detection distance d from the position sensor to the edge of the rotor body; S3, recording the number of signal outputs: recording in real time the number of signal outputs n generated by the arc-shaped concave portions passing through the position sensor during the current rotation cycle, where n is an integer and 0≤n≤z-1; the recording of the number of signal outputs is achieved by a threshold comparison method: when the detection distance d is less than a preset threshold d... th When it is determined that the region has entered the arc-shaped concave area, and d is greater than d, it is considered to have entered the arc-shaped concave region. th S4. Calculate the elliptical polar angle: Based on the real-time detection distance d, calculate the elliptical polar angle α corresponding to the current measurement point; the elliptical polar angle α is defined as the angle coordinate with the center of the ellipse as the pole and the positive direction of the major axis of the ellipse as the polar axis, and its zero point is located at the intersection of each arc-shaped concave part and the outer circumference of the rotor; S5. Calculate the mechanical angle: Based on the elliptical polar angle α and the number of signal outputs n, calculate the current rotational mechanical angle θ of the rotor. m S6. Calculate the electrical angle: based on the preset number of pole pairs p of the motor and the mechanical angle θ. m Calculate the electrical angle θ corresponding to the rotor. e .

[0011] Further, in step S4, the calculation process of the elliptic polar angle α includes: calculating the radial distance D from the rotor center to the current measurement point based on the real-time detection distance d, using the following formula: Where L is the fixed installation distance from the position sensor probe to the outermost circumferential surface of the rotor body, and a is the outer diameter of the rotor body; substituting the radial distance D into the elliptic polar radius formula to solve for the elliptic polar angle α, the elliptic polar radius formula is: Where b is the minor axis dimension of the ellipse corresponding to the arc-shaped concave portion.

[0012] Further, in step S5, the rotor mechanical angle θ m The calculation formula is: In the formula: α is the elliptic polar angle, n is the number of signal outputs in the arc-shaped concave part, and z is the total number of slots in the arc-shaped concave part.

[0013] Further, in step S6, the rotor electrical angle θ e The calculation formula is: In the formula: p is the preset number of pole pairs of the motor, θ m This represents the current mechanical angle of rotation of the rotor.

[0014] Furthermore, the non-contact position sensor is a non-contact displacement position sensor, whose detection optical path or detection axis is perpendicular to the outer peripheral surface of the rotor body, and the detection point is located in the radial plane of the rotor.

[0015] Preferably, the minor axis b of the ellipse is selected to satisfy the following relationship: b = (0.6~0.9)a. The specific value of b is determined according to the resolution and range of the position sensor, and should ensure that the distance change Δd generated at the lowest point of the arc-shaped concave part is within acceptable limits. min It should be at least three times greater than the sensor resolution to ensure the reliability of signal acquisition.

[0016] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are: 1. Simple structure and easy to process: By directly processing the concave part composed of elliptical arcs on the outer circle of a standard cylindrical rotor, the structure is ingeniously designed and can be accurately formed by CNC machine tools and other equipment, resulting in low manufacturing cost.

[0017] 2. Achieve contactless measurement with high reliability: The rotor structure itself is passive and requires no wiring. Combined with an external stationary position sensor, it achieves completely contactless angle measurement, completely eliminating mechanical wear and significantly improving the system's service life and environmental adaptability.

[0018] 3. High measurement accuracy and simple algorithm: By utilizing the geometric characteristics of an elliptical arc, a clear mathematical relationship is established between the detection distance of the position sensor and the polar angle of the ellipse. Combined with the counting of the grooves, the mechanical angle can be accurately calculated. The algorithm is simple, reliable, and highly accurate.

[0019] 4. Strong versatility of position sensors: This method has no special restrictions on the specific type of position sensor (such as laser, eddy current, Hall effect, etc.), as long as it can accurately measure distance, which improves the versatility and flexibility of position sensor selection. Attached Figure Description

[0020] Figure 1 is a schematic diagram of the structure of a four-slot motor rotor in one embodiment of the present invention; Figure 2 is a schematic diagram of the structure of a five-slot motor rotor in another embodiment of the present invention; Figure 3 is a schematic diagram of the principle of the non-contact measurement of the rotation angle of a four-slot motor rotor in the present invention; Figure 4 is a schematic diagram of the principle of the non-contact measurement of the rotation angle of a five-slot motor rotor in the present invention.

[0021] In the diagram: 1-Rotor body, 2-Position sensor. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it.

[0023] As shown in Figures 1 and 2, the present invention provides a rotor for non-contact angle measurement. The rotor mainly comprises a cylindrical rotor body 1. Multiple arc-shaped recesses are evenly distributed along the circumferential direction on the outer circumferential surface of the rotor body 1. These arc-shaped recesses are key structural features of the rotor; their function is to change the relative distance between the rotor and an externally stationary position sensor 2 when the rotor rotates, thereby generating a signal change that can be detected by the position sensor and used to calculate the angle.

[0024] The outline of each arc-shaped concave part is composed of an elliptical arc. The design of this elliptical arc follows specific geometric rules: Elliptical positioning: the major axis of the ellipse containing the elliptical arc is consistent with or parallel to the diameter direction of the rotor body 1, and the length of the major axis of the ellipse is equal to the outer diameter a of the rotor body 1.

[0025] Elliptical shape: The minor axis of the ellipse is b, and a > b must be satisfied. The size of the minor axis b determines the depth of the arc-shaped concave part, which is a designable parameter. The smaller b is, the deeper the groove and the more obvious the signal change.

[0026] The selection principle for the short shaft b: The value of b needs to comprehensively consider the sensor's performance and measurement accuracy requirements. Generally, the preferred range is b = (0.6-0.9)a. When b is small, the groove depth is large, and the signal change is significant, but it may increase the manufacturing difficulty; when b is large, the groove is shallow, and the rotor structure is closer to a cylinder, but the signal change is smaller. During design, it should be ensured that at the lowest point of the arc-shaped concave section, the change in detection distance d relative to the cylindrical surface is Δd. min It should be at least three times greater than the sensor resolution to ensure the reliability of signal acquisition.

[0027] Smooth connection: Adjacent arc-shaped recesses are smoothly connected by the unprocessed outer peripheral surface of the rotor body 1. In this way, the outer peripheral profile of the rotor forms a petal-like periodic structure composed of alternating circular and elliptical arc segments.

[0028] To ensure measurement accuracy, all arc-shaped concave sections must be uniformly distributed on the circumference. Let the total number of arc-shaped concave sections be z (z is a positive integer greater than 1). Then, the angle θ between the central symmetry lines of two adjacent arc-shaped concave sections is constant, satisfying: Depending on whether the number of slots z is even or odd, the machining datum for the arc-shaped concave part is slightly different, but this does not affect the final shape and function: when z is even, as shown in Figure 1, z=4; it can be based on A complete ellipse is formed by successively offsetting the outline of each ellipse by an included angle θ, thereby creating z arc-shaped recesses on the outer periphery of the rotor.

[0029] When z is an odd number, as shown in Figure 2, z=5; based on z complete ellipses, by successively offsetting the outline of each ellipse with an included angle θ, z arc-shaped concave parts can be formed on the outer periphery of the rotor.

[0030] Angle Measurement Method Implementation Example: The following, with reference to Figures 3 and 4, details a method for non-contact angle measurement using the aforementioned rotor structure. This method includes the following steps: S1, System Configuration: A rotor with z arc-shaped recesses is mounted on the motor shaft. A non-contact position sensor 2 is fixedly installed at a fixed position on the outer periphery of the rotor body 1. During installation, it must be ensured that the detection direction of the position sensor 2 is perpendicular to the rotor's rotation axis, and that the detection point of the position sensor is located within the radial plane of the rotor. The fixed installation distance L from the probe of the position sensor 2 to the outermost edge of the rotor body 1 is recorded.

[0031] S2. Obtaining Real-Time Detection Distance: As the rotor rotates, the straight-line distance between its outer circumference and the probe of position sensor 2 changes periodically as the arc-shaped concave portion passes through. Position sensor 2 acquires the detection signal in real time and, based on its internal working principle, converts the signal into the real-time detection distance d from the position sensor probe to the edge of the rotor body 1.

[0032] S3. Record the number of signal outputs: During rotor rotation, whenever a complete arc-shaped concave section passes by position sensor 2, the detection distance d will first decrease and then increase, forming a complete signal pulse. The system records in real time the number of such signal outputs n detected within the current rotation cycle. n is an integer with a value range of 0≤n≤z-1, representing that the current position sensor is facing the (n+1)th arc-shaped concave section area.

[0033] To accurately record the number of signal outputs, this method employs a threshold comparison approach: a preset distance threshold d is used. th This threshold lies between the detection distance L of the cylindrical surface and the detection distance of the lowest point of the concave section. When the detection distance d is less than d... th When d is greater than d, it is determined that the sensor has entered the arc-shaped concave region; th When the rotor is stationary or in low-speed reciprocating motion, it is determined to have left the arc-shaped concave region. The counter increments by 1 for each complete "entry-exit" process detected. When the rotor is stationary or in low-speed reciprocating motion, a hysteresis interval is set to avoid repeated triggering near the threshold, ensuring counting reliability.

[0034] S4. Calculate the elliptical polar angle: When the position sensor is directly facing a certain arc-shaped concave part, the current detection point is located on the elliptical arc profile of that concave part. At this time, the distance d detected by the position sensor and the radial distance D from the rotor center to the detection point have the following geometric relationship (see the geometric auxiliary lines in Figure 3 or Figure 4): Where 'a' is the diameter of the rotor body, and 'L' is the fixed installation distance recorded in step one. For an elliptical arc profile, the radial distance D from the center of the ellipse (i.e., the rotor center) to any point on the ellipse satisfies the elliptical polar angle α at that point according to the elliptical polar radius formula: Where a is the major axis of the ellipse (i.e., the rotor diameter), and b is the minor axis of the ellipse (a preset design value). Here, the polar angle α of the ellipse is defined as the angular coordinate with the center of the ellipse as the pole and the positive direction of the major axis of the ellipse (i.e., the direction from the center of the rotor to the intersection of the arc-shaped concave part and the cylindrical surface) as the polar axis. Each arc-shaped concave part uses an independent polar coordinate system, with its zero point located at the initial boundary of the concave part.

[0035] By combining the two formulas above, the elliptical polar angle α corresponding to the current detection point can be calculated. α is the angle in the elliptical arc coordinate system, which precisely indicates the specific position of the position sensor detection point on the current arc-shaped concave contour.

[0036] S5. Calculate the mechanical angle: The elliptic polar angle α is a local angle relative to the coordinate system of the current arc-shaped concave portion. To obtain the global mechanical angle θ of the rotor relative to the fixed position sensor... m This requires combining α with the previously recorded number of signal outputs, n. The calculation formula is: The meaning of this formula is: the total mechanical angle is equal to the local angle (α) within the groove plus the angle corresponding to the number of complete grooves (n) that have been rotated.

[0037] S6. Calculate the electrical angle: In motor control, the electrical angle θ is often of greater concern. e Electrical angle and mechanical angle θ m And it is related to the number of pole pairs p of the motor. Based on the preset number of pole pairs p of the motor, the electrical angle of the rotor can be calculated: Through the above steps, the system can calculate the current mechanical and electrical angles of the rotor rotation in real time and accurately.

[0038] Application Example 1: Number of Slots The length of the major axis of the ellipse is equal to the outer diameter of the rotor body. The minor axis dimension of the ellipse Number of pole pairs of the motor The fixed installation distance from the sensor probe to the outermost part of the rotor body. At the current moment, the real-time detection distance from the position sensor probe to the edge of the rotor body is detected. And the number of times the detected signal output is... The radial distance from the rotor center to the detection point was calculated. Substituting into the formula for the polar radius of an ellipse, we obtain the polar angle of the ellipse. The mechanical angle is obtained according to the formula for calculating mechanical angle. Substituting into the formula for calculating the electrical angle, we obtain the electrical angle. .

[0039] Application Example 2: Number of Slots The length of the major axis of the ellipse is equal to the outer diameter of the rotor body. The minor axis dimension of the ellipse Number of pole pairs of the motor The fixed installation distance from the sensor probe to the outermost part of the rotor body. At the current moment, the real-time detection distance from the position sensor probe to the edge of the rotor body is detected. And the number of times the detected signal output is... The radial distance from the rotor center to the detection point was calculated. Substituting into the formula for the polar radius of an ellipse, we obtain the polar angle of the ellipse. The mechanical angle is obtained according to the formula for calculating mechanical angle. Substituting into the formula for calculating the electrical angle, we obtain the electrical angle. .

[0040] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A rotor for non-contact angle measurement, characterized in that, include: The rotor body is cylindrical; multiple arc-shaped recesses are evenly distributed along the outer circumference of the rotor body for use with a non-contact position sensor to measure angles by detecting changes in the edge position of the rotor body; wherein, the contour of each arc-shaped recess is formed by a quadratic curve arc, the major axis of the quadratic curve arc is equal to the outer diameter of the rotor body, and the minor axis of the quadratic curve arc is smaller than the major axis; adjacent arc-shaped recesses are smoothly connected through the outer circumference of the rotor body, and the smooth connection means that there is at least first-order geometric continuity at the connection point.

2. The rotor according to claim 1, characterized in that, The quadratic curve arc is an elliptical arc. The major axis of the ellipse containing the elliptical arc is equal to the outer diameter a of the rotor body, and the minor axis is b, where a > b.

3. The rotor according to claim 1, characterized in that, The included angle θ between the central symmetry lines of two adjacent arc-shaped concave portions satisfies: θ = 360° / z, where z is the total number of arc-shaped concave portions and z is a positive integer greater than 1.

4. The rotor according to claim 3, characterized in that, When z is an even number, the z arc-shaped recesses on the rotor body are formed based on z / 2 complete ellipses, and the elliptical contours corresponding to each arc-shaped recess are staggered sequentially by the included angle θ; when z is an odd number, the z arc-shaped recesses on the rotor body are formed based on z complete ellipses, and the elliptical contours corresponding to each arc-shaped recess are staggered sequentially by the included angle θ.

5. A non-contact rotor angle calculation method using the rotor described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Configure the rotor and position sensor: Install the rotor with z arc-shaped concave portions onto the motor shaft, and fix the non-contact position sensor at a predetermined position on the outer periphery of the rotor body; S2. Obtain the real-time detection distance: Collect the detection signal in real time through the position sensor and convert it into the real-time detection distance d from the position sensor to the edge of the rotor body; S3. Record the number of signal outputs: Record the number of signal outputs n generated by the arc-shaped concave portions passing through the position sensor in the current rotation cycle in real time; S4. Calculate the elliptic polar angle: Based on the real-time detection distance d, calculate the elliptic polar angle α corresponding to the current measurement point; S5. Calculate the mechanical angle: Based on the elliptic polar angle α and the number of signal outputs n, calculate the mechanical angle θ of the rotor's current rotation. m S6. Calculate the electrical angle: based on the preset number of pole pairs p of the motor and the mechanical angle θ. m Calculate the electrical angle θ corresponding to the rotor. e .

6. The non-contact rotor angle calculation method according to claim 5, characterized in that, In step S4, the calculation process of the elliptic polar angle α includes: calculating the radial distance D from the rotor center to the current measurement point based on the real-time detection distance d, using the following formula: Where L is the fixed installation distance from the position sensor probe to the outermost circumferential surface of the rotor body, and a is the outer diameter of the rotor body; substituting the radial distance D into the quadratic curve polar radius formula to solve for the elliptic polar angle α, the quadratic curve is an ellipse, and the quadratic curve polar radius formula is the elliptic polar radius formula: Where b is the minor axis dimension of the ellipse corresponding to the arc-shaped concave portion.

7. The non-contact rotor angle calculation method according to claim 5, characterized in that, In step S5, the rotor mechanical angle θ m The calculation formula is: In the formula: α is the elliptic polar angle, n is the number of signal outputs in the arc-shaped concave part, and z is the total number of slots in the arc-shaped concave part.

8. The non-contact rotor angle calculation method according to claim 5, characterized in that, In step S6, the rotor electrical angle θ e The calculation formula is: In the formula: p is the preset number of pole pairs of the motor, θ m This represents the current mechanical angle of rotation of the rotor.

9. The non-contact rotor angle calculation method according to claim 5, characterized in that, The non-contact position sensor is a non-contact displacement position sensor, whose detection optical path or detection axis is perpendicular to the outer peripheral surface of the rotor body, and the detection point is located in the radial plane of the rotor.

Images