A high-speed motor rotating speed detection method based on MEMS micro coil

Abstract

This invention discloses a high-speed motor speed detection method based on MEMS microcoils, relating to the field of high-speed motor speed detection. The method includes: non-contactly placing at least one MEMS microcoil sensor at a key electromagnetic field coupling position on the high-speed motor body or drive circuit; the MEMS microcoil sensor outputting a raw induced voltage signal; conditioning the raw induced voltage signal; using an analog-to-digital converter to perform high-speed synchronous sampling of the conditioned signal to obtain a digital signal sequence; extracting the speed characteristic frequency; calculating the real-time motor speed based on the speed characteristic frequency and preset motor parameters through a preset mapping relationship, and outputting the calculation result. This invention employs a miniaturized coil sensor based on MEMS technology, combined with intelligent signal processing algorithms, to achieve high-precision, high-response speed measurement in ultra-high-speed scenarios.

Description

Technical Field

[0001] This invention relates to the field of high-speed motor speed detection, and in particular to a method for high-speed motor speed detection based on MEMS micro-coils. Background Technology

[0002] High-speed motors, as core drive components of modern high-end equipment, are widely used in precision machine tool spindles, aero engines, turbomachinery, centrifugal separators, high-speed compressors, and new energy vehicles. The operating status of these motors directly affects the performance, efficiency, and reliability of the entire system. Especially in ultra-high-speed applications, accurate speed detection is not only a key feedback parameter for the control system but also a crucial safety barrier against catastrophic failures.

[0003] With the development of Industry 4.0 and smart manufacturing, high-speed motors are evolving towards higher speeds, higher power densities, and smaller sizes. However, speed detection faces significant challenges. Traditionally, motor speed detection mainly relies on technologies such as resolvers, photoelectric encoders, and Hall / magnetoresistive sensors. These solutions perform well in conventional or low-to-medium speed motor applications, but their inherent limitations become significantly apparent when dealing with high-speed or ultra-high-speed motors. At high speeds, resolvers produce significant signal phase lag and waveform distortion. The saturation effect of their internal magnetic circuit intensifies with increasing frequency, leading to a sharp decline in calculation accuracy. At the same time, resolvers are large in size and difficult to integrate into compact high-speed motors. External installation introduces additional vibrations, affecting high-speed stability.

[0004] Photoelectric encoders are extremely sensitive to high-vibration environments. Mechanical vibrations generated by high-speed rotation can easily cause photoelectric devices to fail or readings to jump. In addition, their glass code disks are at risk of cracking at ultra-high speeds, and heat dissipation issues also limit their application in high-power-density motors. The optical window is susceptible to oil and dust contamination, resulting in high maintenance costs.

[0005] Although magnetoresistive / Hall sensors have a simple structure, their limited bandwidth (typically <100 kHz) makes it difficult to accurately capture high-frequency signals generated at ultra-high speeds (>50,000 rpm). At the same time, the complex electromagnetic environment inside the motor can introduce serious interference and reduce the signal-to-noise ratio. The size and lead structure of traditional magnetic sensors also limit their integrated application in micro high-speed motors.

[0006] Existing technologies generally suffer from response delays, making it impossible to capture in real time the instantaneous speed fluctuations, oscillations, or stall phenomena that may occur in high-speed motors. These are often early signs of bearing failure, rotor imbalance, or control system instability. A deeper technical bottleneck lies in the fact that the aforementioned traditional sensors are all "macroscopic" devices. Their physical size, material properties, and working mechanisms determine that they are difficult to exceed the signal bandwidth limit of several hundred kHz. In contrast, a 100,000 rpm motor, even with only a few magnetic poles, generates a fundamental frequency signal that is close to the kHz level, and harmonic components can even reach the MHz level.

[0007] Therefore, those skilled in the art are dedicated to developing a high-speed motor speed detection method based on MEMS micro-coils, which can adapt to the compact design of high-speed motors and has high bandwidth and high anti-interference capability. Summary of the Invention

[0008] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is that traditional sensors are large in size and difficult to integrate, have limited bandwidth and cannot capture high-frequency magnetic field signals, and are mostly invasive measurements, which are difficult to adapt to the detection requirements of miniaturized high-speed motors and high dynamic response.

[0009] To achieve the above objectives, the present invention provides a method for detecting the speed of a high-speed motor based on a MEMS micro-coil, the method comprising the following steps: Step 1: Place at least one MEMS micro-coil sensor in a non-contact manner at a critical electromagnetic field coupling position on the high-speed motor body or drive circuit. Step 2: When the high-speed motor is running, the MEMS micro-coil sensor senses the time-varying magnetic field generated by the electromagnetic process of the motor at its setting location and outputs an original induced voltage signal that is proportional to the rate of change of the magnetic field. Step 3: Perform signal conditioning on the original induced voltage signal, and use an analog-to-digital converter to perform high-speed synchronous sampling on the conditioned signal to obtain a digital signal sequence; Step 4: Extract the rotational speed characteristic frequency based on the digital signal sequence; Step 5: Based on the speed characteristic frequency and the preset motor parameters, calculate the real-time speed of the motor through the preset mapping relationship, and output the calculation result.

[0010] Furthermore, in step 1, the MEMS micro-coil sensor is set at any of the following locations: At the stator tooth shoe or winding end, used to sense the high-frequency current and its harmonics generated by PWM drive in the stator winding; At the air gap magnetic field path of the motor, it is used to directly sense the change in the main air gap magnetic field modulated by the rotor rotation; At the rotor shaft grounding circuit or bearing current path, it is used to sense shaft voltage discharge pulses or bearing current pulse signals caused by rotor rotation; The high-frequency component in the non-invasive induction phase current is located at the DC bus or phase current output cable of the motor driver.

[0011] Furthermore, the signal conditioning in step 3 includes low-noise amplification and bandpass filtering to enhance the signal-to-noise ratio and focus on the frequency band related to rotational speed.

[0012] Furthermore, step 4 also includes: Step 4.1: Perform time-frequency analysis on the acquired digital signal sequence, and obtain the spectrum of the digital signal sequence using Fast Fourier Transform or Short Time Fourier Transform; Step 4.2: Identify the characteristic frequencies directly related to the mechanical speed of the motor in the frequency spectrum; the relationship between the characteristic frequencies and the mechanical speed of the motor and the number of pole pairs of the motor depends on the sensor placement location and the physical quantity sensed. Step 4.3: Use an adaptive peak tracking algorithm or digital phase-locked loop technology to lock and track the characteristic frequency corresponding to the rotational speed characteristic peak in the spectrum in real time.

[0013] Furthermore, in step 4.2, if the sensor senses the PWM switching frequency sideband of the stator current or the rotor magnetic field modulation harmonic, its characteristic frequency is usually related to the electrical frequency; if the sensor senses the periodic change of the magnetic field directly caused by the rotor rotation, the characteristic frequency corresponds to the mechanical rotation frequency, or the multiple frequency corresponding to multiple marks per revolution.

[0014] Further, in step 5, the preset mapping relationship includes: or ,in, This refers to the real-time speed of the motor. For characteristic frequencies, This represents the number of pole pairs of the motor. For the number of markers.

[0015] Furthermore, the method also includes: When multiple MEMS micro-coil sensors are deployed, the output signals of the multiple sensors can be fused or used to identify the rotation direction, thereby improving the robustness and reliability of the system.

[0016] Furthermore, the method also includes: utilizing the inherent characteristics of MEMS micro-coil sensors to perform online self-diagnosis and temperature compensation, ensuring long-term monitoring accuracy.

[0017] Furthermore, the MEMS microcoil sensor includes a glass substrate, a Cr / Cu seed layer, a MEMS microcoil array, and a polyimide insulating layer; the MEMS microcoil array includes a bottom coil layer, an intermediate connecting pillar layer, a top coil and an electrode layer, and the bottom coil layer and the top coil and electrode layer are electrically connected in series through the intermediate connecting pillar layer to form a three-dimensional spiral path.

[0018] Furthermore, the MEMS micro-coil sensor is manufactured using MEMS technology, and the fabrication process includes: The glass substrate was ultrasonically cleaned for 10 minutes each with deionized water, acetone, and alcohol, then ultrasonically cleaned with deionized water for 10 minutes, dried with nitrogen, and then dried in a 60°C oven. A Cr / Cu seed layer was deposited on a cleaned glass substrate using a magnetron sputtering machine, wherein the Cr seed layer was 10 nm thick and the Cu seed layer was 150 nm thick. Spin-coat a 50μm thick first layer of photoresist and dry it. After photolithographic patterning, electroplate a 50μm thick bottom copper coil layer. Immerse the device in acetone solution for 20 minutes to remove the photoresist. Rinse twice with deionized water. After drying with nitrogen, place it in a 90°C oven to dry for 2 hours. Spin-coat a second layer of photoresist with a thickness of 50μm and dry it. After photolithography patterning, electroplate a 50μm thick copper intermediate connection pillar layer. Immerse the device in acetone solution for 20 minutes to remove the photoresist. Rinse twice with deionized water. After drying with nitrogen, place it in a 90°C oven to dry for 2 hours. Remove the excess seed layer by reactive ion etching. Spin-coat a 110μm thick polyimide layer onto the copper layer surface, cure in a 250°C oven for 4 hours, use chemical mechanical polishing to smooth the polyimide layer until the intermediate connecting pillars are exposed and there are no visible scratches, rinse twice with deionized water, dry with nitrogen, and then place in a 90°C oven to dry for 2 hours. A Cr / Cu seed layer with the same specifications as the base layer was deposited using a magnetron sputtering machine. A 50μm thick third layer of photoresist was spin-coated and dried. After photolithography patterning, a 50μm thick top coil and electrode layer were electroplated. The device was then immersed in acetone solution for 20 minutes to remove the photoresist. It was rinsed twice with deionized water, dried with nitrogen, and then placed in a 90°C oven for constant temperature drying for 2 hours. Excess seed layer was removed by reactive ion etching.

[0019] Compared with the prior art, the present invention has at least the following beneficial technical effects: 1. This invention uses a miniaturized coil sensor based on MEMS technology to achieve chip-level size and embedded deployment. The sensor occupies almost no extra space, perfectly matching the trend of device miniaturization and reducing external lead interference. The coreless "hollow" structure eliminates magnetic saturation and eddy current loss, making it possible to measure ultra-high speed and monitor high dynamic performance, solving the core problem of insufficient bandwidth of traditional sensors. 2. This invention achieves completely non-invasive, non-physical contact speed monitoring, significantly improving system reliability, vibration resistance and overall lifespan, and is particularly suitable for interference-free measurement at ultra-high speeds; 3. This invention employs passive sensing MEMS micro-coils and standard mass production processes to achieve extremely low power consumption and low cost, meeting the long-term monitoring needs of battery-powered devices and lowering the cost threshold for large-scale applications such as new energy vehicles and IoT terminals; it also expands the applicability of sensors in harsh industrial environments such as aero-engines and high-speed compressors, and improves long-term stability.

[0020] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a preferred embodiment of the present invention; Figure 2 This is a schematic diagram of the installation position of the MEMS micro-coil induction rotor magnetic field according to a preferred embodiment of the present invention; Figure 3 This is a three-dimensional model diagram of a 4×4 double-layer MEMS micro-coil array according to a preferred embodiment of the present invention; Figure 4 This is a preferred embodiment of the fabrication process of a dual-layer MEMS micro-coil sensor according to the present invention.

[0022] Among them, 1-MEMS micro-coil sensor; 2-glass substrate; 3a-Cr seed layer; 3b-Cu seed layer; 4-MEMS micro-coil array; 4a-bottom coil layer; 4b-intermediate connecting pillar layer; 4c-top coil and electrode layer; 5-polyimide insulating layer. Detailed Implementation

[0023] The following description, with reference to the accompanying drawings, illustrates several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0024] In the accompanying drawings, components with the same structure are indicated by the same numerical designation, and components with similar structures or functions are indicated by similar numerical designations. The dimensions and thicknesses of each component shown in the drawings are arbitrary, and the present invention does not limit the dimensions and thicknesses of each component. To make the illustrations clearer, the thickness of some components has been appropriately exaggerated in the drawings.

[0025] This embodiment provides a method for detecting the speed of a high-speed motor based on MEMS micro-coils, such as... Figure 1 As shown, it includes the following steps: Step 1: Sensor deployment and integration.

[0026] At least one MEMS micro-coil sensor 1 is disposed in a non-contact manner at a critical electromagnetic field coupling location on the high-speed motor body or drive circuit; the placement location includes, but is not limited to: (1) At the stator tooth shoe or winding end, used to sense the high-frequency current and its harmonics generated by PWM drive in the stator winding, and its current change rate ( It contains information related to the electrical cycle; the characteristic frequency is related to the electrical frequency. , (Number of pole pairs), suitable for enclosed motors where the end caps cannot be modified; (2) At the air gap magnetic field path of the motor, specifically, a non-magnetic window (such as a ceramic insert) is reserved in the motor end cover, and the MEMS micro-coil sensor 1 is attached to the inside of the window, so that its coil plane is perpendicular to the rotor rotation axis, for directly sensing the change of the main air gap magnetic field modulated by the rotor rotation; the characteristic frequency corresponds strictly to the mechanical speed ( ), suitable for permanent magnet synchronous motors; (3) At the rotor shaft grounding circuit or bearing current path, it is used to sense the shaft voltage discharge pulse or bearing current pulse signal caused by rotor rotation; a fixed number of pulses are generated per revolution, and the speed is calculated by counting. It is suitable for high-speed motor fault diagnosis scenarios with bearing current problems. (4) The high-frequency component in the non-intrusive induced phase current is used at the DC bus or phase current output cable of the motor driver.

[0027] In this embodiment, the preferred position is (2), as follows: Figure 2 As shown, the MEMS micro-coil sensor 1 is bonded to the inside of the ceramic window of the end cap with epoxy resin. The MEMS micro-coil sensor 1 has dimensions of 7.5 mm × 8.9 mm × 0.15 mm. After installation, it does not affect the original sealing and dynamic balance characteristics of the motor.

[0028] Step 2: Induction of characteristic electromagnetic signals.

[0029] When the high-speed motor is running, the MEMS micro-coil sensor 1, based on Faraday's law of electromagnetic induction, senses the time-varying magnetic field generated by the electromagnetic process of the motor at its deployment location and outputs a signal corresponding to the rate of change of the magnetic field (i.e., the specific rate of change of the current). The original induced voltage signal is proportional to the original voltage signal. .

[0030] Step 3: Signal conditioning and acquisition.

[0031] For the original induced voltage signal Signal conditioning is performed, including low-noise amplification and bandpass filtering, to enhance the signal-to-noise ratio and focus on a speed-related frequency band (e.g., covering tens of times the motor's fundamental frequency to the switching frequency range). The conditioned signal is then rapidly and synchronously sampled using an analog-to-digital converter to obtain a digital signal sequence.

[0032] Step 4, Feature Frequency Extraction, including: Step 4.1: Perform time-frequency analysis on the acquired digital signal sequence. Preferably, the spectrum of the digital signal sequence is obtained by using Fast Fourier Transform (FFT) or Short Time Fourier Transform (STFT). Step 4.2: Identify characteristic frequencies in the frequency spectrum that are directly related to the mechanical speed of the motor. Characteristic frequency and motor mechanical speed (Unit: revolutions per minute, RPM) and number of motor pole pairs The relationship depends on the sensor's location and the physical quantity sensed, specifically: (1) If the sensor senses the PWM switching frequency sideband of the stator current or the rotor magnetic field modulation harmonic, its characteristic frequency is usually the same as the electrical frequency. Related, Characteristic frequency may be Or its specific harmonics / sidebands; (2) If the sensor senses the periodic change in the magnetic field directly caused by the rotor rotation (e.g., by setting magnetic markers on the rotor surface), then the characteristic frequency is... Corresponding mechanical rotation frequency Or, the multiple frequency corresponding to each mark per revolution; Step 4.3: To cope with high-speed variable operating conditions, an adaptive peak tracking algorithm or digital phase-locked loop technology is adopted to lock and track the characteristic frequency corresponding to the most stable and significant amplitude speed characteristic peak in the spectrum in real time.

[0033] Step 5: Rotational speed calculation and output.

[0034] Based on the characteristic frequency of the rotational speed and combined with preset motor parameters, the real-time speed of the motor is calculated through a preset mapping relationship. The calculation results are then output via a digital communication interface (such as SPI, I2C, CAN); the preset motor parameters are the number of motor pole pairs. Number of tags The preset mapping relationships include: or .

[0035] Step 6: Multi-sensor fusion and fault tolerance.

[0036] When multiple MEMS micro-coil sensors 1 are arranged (e.g., they are spatially separated by a certain electrical angle), the output signals of multiple sensors can be fused (e.g., weighted averaging, consistency verification) or used to identify the rotation direction, thereby improving the robustness and reliability of the system.

[0037] Step 7: Self-diagnosis and calibration.

[0038] By utilizing the inherent characteristics of the MEMS micro-coil sensor 1 (such as coil resistance and inductance), online self-diagnosis and temperature compensation are performed to ensure long-term monitoring accuracy.

[0039] like Figure 3 As shown, this embodiment uses a 4×4 dual-layer MEMS micro-coil sensor 1 as the sensing unit, including a glass substrate 2, a Cr / Cu seed layer (Cr seed layer 3a, Cu seed layer 3b), a MEMS micro-coil array 4, and a polyimide insulating layer 5; the MEMS micro-coil array 4 includes a bottom coil layer 4a, an intermediate connecting pillar layer 4b, and a top coil and electrode layer 4c.

[0040] Key parameters for a single coil unit include: The number of coil turns q is 5 turns; the coil thickness t is 50μm for a single layer and 200μm for a double layer; the coil line width w is 50μm; the coil line spacing s is 100μm; the layer spacing ds is 50μm (determined by the height of the intermediate connecting post); and the horizontal spacing ls in the same layer is 2000μm.

[0041] The bottom coil layer 4a and the top coil and electrode layer 4c are electrically connected in series through the central connecting pillar layer 4b (50μm high) located at the center of the array, forming a three-dimensional spiral path, which significantly improves the magnetic flux capture efficiency. The measured total array inductance is 1.511μH and the DC resistance is 4.79 Ω.

[0042] MEMS micro-coil sensor 1 is manufactured using MEMS technology, such as Figure 4 As shown, the specific preparation process includes: Step 1: Clean the substrate, such as... Figure 4As shown in (a), the substrate was ultrasonically cleaned with deionized water for 10 minutes, then wiped with acetone cotton and ultrasonically cleaned in acetone for 10 minutes, then wiped with alcohol cotton and ultrasonically cleaned in alcohol for 10 minutes, and finally ultrasonically cleaned with deionized water for 10 minutes. After drying with nitrogen, it was dried in an oven at 60°C.

[0043] Step 2, depositing a seed layer, such as Figure 4 As shown in (b), a Cr seed layer 3a with a thickness of 10 nm and a Cu seed layer 3b with a thickness of 150 nm were deposited using a magnetron sputtering machine to form a Cr / Cu seed layer. Step 3: Spin-coat photoresist, such as... Figure 4 As shown in (c), spin-coat the first layer of photoresist to a thickness of 50 μm and then dry. Step 4: Photolithography patterning, such as... Figure 4 As shown in (d), the first photomask pattern is exposed and developed to form the corresponding photoresist pattern. After cleaning with deionized water, the development is checked and the image is dried. Step 5: Electroplating the coil, such as... Figure 4 As shown in (e), the electroplated bottom copper coil layer has a thickness of 50 μm; Step 6: Remove the photoresist, such as... Figure 4 As shown in (f), the device was immersed in acetone solution for 20 minutes to remove most of the photoresist. It was then rinsed twice with deionized water and dried with nitrogen. Finally, it was dried in a 90°C oven for 2 hours. Step 7: Spin-coat photoresist, such as... Figure 4 As shown in (g), spin-coat a second layer of photoresist 50μm thick and dry; Step 8: Photolithography patterning, such as... Figure 4 As shown in (h), the second photomask pattern is exposed and developed to form the corresponding photoresist pattern. After cleaning with deionized water, the development is checked and the image is dried. Step 9: Electroplat the intermediate connecting column layer, such as... Figure 4 As shown in (i), the second electroplated layer has an intermediate connecting column layer with a thickness of 50 μm; Step 10: Remove the photoresist, such as... Figure 4 As shown in (j), the device was immersed in acetone solution for 20 minutes to remove most of the photoresist. It was then rinsed twice with deionized water and dried with nitrogen. Finally, it was dried in a 90°C oven for 2 hours. Step 11, etching, such as Figure 4 As shown in (k), reactive ion etching is used to remove excess seed layer; Step 12: Spin-coat polyimide, such as... Figure 4 As shown in (l), a 110 μm thick polyimide coating was spin-coated onto the surface of the copper layer and cured in an oven at 250°C for 4 hours. Step 13, Chemical Mechanical Polishing (CMP), such as Figure 4 As shown in (m), the polyimide layer was smoothed by chemical mechanical polishing until the intermediate connecting pillars were exposed and there were no visible scratches. It was then rinsed twice with deionized water, dried with nitrogen, and dried in a 90°C oven for 2 hours. Step 14: Deposit a seed layer, such as Figure 4 As shown in (n), a Cr seed layer 3a with a thickness of 10 nm and a Cu seed layer 3b with a thickness of 150 nm are deposited using a magnetron sputtering machine to form a Cr / Cu seed layer. Step 15: Spin-coat photoresist, such as... Figure 4 As shown in (o), spin-coat a third layer of photoresist 50μm thick and dry; Step 16: Photolithography patterning, such as... Figure 4 As shown in (p), the third photomask pattern is exposed and developed to form the corresponding photoresist pattern. After cleaning with deionized water, the development is checked and the image is dried. Step 17: Electroplating the top coil and electrode layer 4c, as shown. Figure 4 As shown in (q), the third layer of top copper coil and electrode layer are electroplated with a thickness of 50μm; Step 18: Remove the photoresist, such as... Figure 4 As shown in (r), the device was immersed in acetone solution for 20 minutes to remove most of the photoresist. It was then rinsed twice with deionized water and dried with nitrogen. Finally, it was dried in a 90°C oven for 2 hours. Step 19, etching, as shown Figure 4 As shown in (s), reactive ion etching is used to remove excess seed layer.

[0044] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for detecting the speed of a high-speed motor based on a MEMS micro-coil, characterized in that, The method includes the following steps: Step 1: Place at least one MEMS micro-coil sensor in a non-contact manner at a critical electromagnetic field coupling position on the high-speed motor body or drive circuit. Step 2: When the high-speed motor is running, the MEMS micro-coil sensor senses the time-varying magnetic field generated by the electromagnetic process of the motor at its setting location and outputs an original induced voltage signal that is proportional to the rate of change of the magnetic field. Step 3: Perform signal conditioning on the original induced voltage signal, and use an analog-to-digital converter to perform high-speed synchronous sampling on the conditioned signal to obtain a digital signal sequence; Step 4: Extract the rotational speed characteristic frequency based on the digital signal sequence; Step 5: Based on the speed characteristic frequency and the preset motor parameters, calculate the real-time speed of the motor through the preset mapping relationship, and output the calculation result.

2. The high-speed motor speed detection method based on MEMS micro-coil as described in claim 1, characterized in that, In step 1, the MEMS micro-coil sensor is set at any of the following locations: At the stator tooth shoe or winding end, used to sense the high-frequency current and its harmonics generated by PWM drive in the stator winding; At the air gap magnetic field path of the motor, it is used to directly sense the change in the main air gap magnetic field modulated by the rotor rotation; At the rotor shaft grounding circuit or bearing current path, it is used to sense shaft voltage discharge pulses or bearing current pulse signals caused by rotor rotation; The high-frequency component in the non-invasive phase current is used at the DC bus or phase current output cable of the motor driver.

3. The high-speed motor speed detection method based on MEMS micro-coil as described in claim 1, characterized in that, The signal conditioning in step 3 includes low-noise amplification and bandpass filtering to enhance the signal-to-noise ratio and focus on the speed-related frequency band.

4. The high-speed motor speed detection method based on MEMS micro-coil as described in claim 2, characterized in that, Step 4 also includes: Step 4.1: Perform time-frequency analysis on the acquired digital signal sequence, and obtain the spectrum of the digital signal sequence using Fast Fourier Transform or Short Time Fourier Transform; Step 4.2: Identify the characteristic frequencies directly related to the mechanical speed of the motor in the frequency spectrum; the relationship between the characteristic frequencies and the mechanical speed of the motor and the number of pole pairs of the motor depends on the sensor placement location and the physical quantity sensed. Step 4.3: Use an adaptive peak tracking algorithm or digital phase-locked loop technology to lock and track the characteristic frequency corresponding to the rotational speed characteristic peak in the spectrum in real time.

5. The high-speed motor speed detection method based on MEMS micro-coil as described in claim 4, characterized in that, In step 4.2, if the sensor senses the PWM switching frequency sideband of the stator current or the rotor magnetic field modulation harmonic, its characteristic frequency is related to the electrical frequency; if the sensor senses the periodic change of the magnetic field directly caused by the rotor rotation, the characteristic frequency corresponds to the mechanical rotation frequency, or the multiple frequency corresponding to multiple marks per revolution.

6. The high-speed motor speed detection method based on MEMS micro-coil as described in claim 5, characterized in that, In step 5, the preset mapping relationship includes: or ,in, This refers to the real-time speed of the motor. For characteristic frequencies, This represents the number of pole pairs of the motor. For the number of markers.

7. The high-speed motor speed detection method based on MEMS micro-coil as described in claim 1, characterized in that, The method further includes: When multiple MEMS micro-coil sensors are deployed, the output signals of the multiple sensors can be fused or used to identify the rotation direction, thereby improving the robustness and reliability of the system.

8. The high-speed motor speed detection method based on MEMS micro-coil as described in claim 1, characterized in that, The method also includes: utilizing the inherent characteristics of MEMS micro-coil sensors to perform online self-diagnosis and temperature compensation, ensuring long-term monitoring accuracy.

9. The high-speed motor speed detection method based on MEMS micro-coil as described in claim 1, characterized in that, The MEMS microcoil sensor includes a glass substrate, a Cr / Cu seed layer, a MEMS microcoil array, and a polyimide insulating layer. The MEMS microcoil array includes a bottom coil layer, an intermediate connecting pillar layer, a top coil layer, and an electrode layer. The bottom coil layer and the top coil layer and electrode layer are electrically connected in series through the intermediate connecting pillar layer to form a three-dimensional spiral path.

10. The high-speed motor speed detection method based on MEMS micro-coil as described in claim 9, characterized in that, The MEMS micro-coil sensor is manufactured using MEMS technology, and the fabrication process includes: The glass substrate was ultrasonically cleaned for 10 minutes in sequence with deionized water, acetone, and alcohol, then ultrasonically cleaned with deionized water for 10 minutes, dried with nitrogen, and then dried in a 60°C oven. A Cr / Cu seed layer was deposited on a cleaned glass substrate using a magnetron sputtering machine, wherein the Cr seed layer was 10 nm thick and the Cu seed layer was 150 nm thick. Spin-coat a 50μm thick first layer of photoresist and dry it. After photolithographic patterning, electroplate a 50μm thick bottom copper coil layer. Immerse the device in acetone solution for 20 minutes to remove the photoresist. Rinse twice with deionized water. After drying with nitrogen, place it in a 90°C oven to dry for 2 hours. Spin-coat a second layer of photoresist with a thickness of 50μm and dry it. After photolithography patterning, electroplate a 50μm thick copper intermediate connection pillar layer. Immerse the device in acetone solution for 20 minutes to remove the photoresist. Rinse twice with deionized water. After drying with nitrogen, place it in a 90°C oven to dry for 2 hours. Remove the excess seed layer by reactive ion etching. Spin-coat a 110μm thick polyimide layer onto the copper layer surface, cure in a 250°C oven for 4 hours, use chemical mechanical polishing to smooth the polyimide layer until the intermediate connecting pillars are exposed and there are no visible scratches, rinse twice with deionized water, dry with nitrogen, and then place in a 90°C oven to dry for 2 hours. A Cr / Cu seed layer with the same specifications as the base layer was deposited using a magnetron sputtering machine. A 50μm thick third layer of photoresist was spin-coated and dried. After photolithography patterning, a 50μm thick top coil and electrode layer were electroplated. The device was then immersed in acetone solution for 20 minutes to remove the photoresist. It was rinsed twice with deionized water, dried with nitrogen, and then placed in a 90°C oven for constant temperature drying for 2 hours. Excess seed layer was removed by reactive ion etching.

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