Active magnetic bearing eddy current displacement sensor based on improved Colpitts oscillator

Abstract

The utility model provides an active magnetic bearing eddy current displacement sensor based on an improved Colpitts oscillator, and relates to the technical field of active magnetic bearing motor rotor unbalance signal extraction and disturbance suppression. The active magnetic bearing eddy current displacement sensor comprises a probe housing, a signal processing module based on an improved Colpitts oscillator, and an output port. The signal processing module based on the improved Colpitts oscillator is arranged in the probe shell and is electrically connected with the output port; and the output port is arranged at one end of the probe shell. Wherein the signal processing module based on the improved Colpitts oscillator comprises the improved Colpitts oscillator, a peak detection module and a linear fitting module which are connected in sequence. According to the utility model, small displacement changes between the rotor and the stator are obtained in real time, corresponding analog signals, namely rotor displacement signals, are output, and the stable sensing capability of the active magnetic bearing system to high-speed rotor displacement is effectively improved.

Description

Technical Field

[0001] The utility model relates to the technical field of active magnetic bearing motor rotor imbalance signal extraction and disturbance suppression, in particular to an active magnetic bearing eddy current displacement sensor based on an improved Colpitts oscillator. Background Art

[0002] Active magnetic bearings (AMBs) are widely used in high-end applications such as high-speed rotating machinery, aerospace, and semiconductor processing due to their non-contact, high-speed, and low-wear properties. However, due to uneven load and mass distribution within internal components, AMBs can generate rotor imbalance disturbances, making them unstable open-loop systems. AMBs rely on rotor displacement sensors to accurately measure rotor position changes and implement closed-loop control to maintain stable rotor suspension, thereby reducing bearing friction and wear and improving motor efficiency. Therefore, accurate and reliable displacement sensors are crucial for AMB suspension control.

[0003] Eddy current displacement sensors, as a typical non-contact displacement sensor, have broad application prospects in the field of rotor displacement in active magnetic bearings. Based on the principle of electromagnetic induction, eddy current sensors are insensitive to any non-conductive media and are unaffected by environmental conditions such as dirt, dust, and humidity. They offer advantages such as simple structure, high sensitivity, and a wide frequency response. They operate over a wide temperature range and can achieve micron-level resolution. Consequently, eddy current displacement sensors are also widely used in other fields. For example, in aerospace, eddy current sensors are used in aircraft attitude control and navigation systems. They can be installed on key components to measure aircraft displacement and attitude changes, providing accurate data input to flight control systems and ensuring aircraft safety and stability. In industrial automation, eddy current sensors are used for displacement detection and control of mechanical equipment. However, eddy current displacement sensors suffer from short measurement ranges, nonlinearity, and temperature drift. They are also susceptible to electromagnetic interference generated by the high-frequency switching of active magnetic bearing drive converters, which affects the accuracy and stability of their engineering applications. Therefore, compensating for nonlinearity and reducing temperature drift and electromagnetic interference are particularly important in the research of eddy current displacement sensors.

[0004] A large body of literature has been devoted to optimizing eddy current sensors, including selecting the optimal excitation frequency and geometry, improving the efficiency of the drive circuit, and increasing linearity. These are as follows:

[0005] BAW series eddy current displacement sensors: The BAW002Y sensor has a linear range of 3.0-15.0 mm, a maximum nonlinearity within ±360 μm, a repeatability of ±12 μm, and a limit frequency of 350 Hz. It features advanced sensing parameters with an adjustable linear range, can measure different positions and distances, and can distinguish between different materials. However, this sensor does not account for the effects of nonlinearity, and its temperature performance is also poor.

[0006] Colpitts oscillator eddy current displacement sensor: Existing eddy current sensors based on the Colpitts oscillator have attracted attention due to their simple circuit structure, stable frequency, and low power consumption. However, these sensors only achieve high linearity at a small detection distance, and there is no analysis of how to improve the linearity and measurement distance of the Colpitts circuit.

[0007] PCB eddy current displacement sensor: Used to detect radial displacement of the rotor in active magnetic bearings. This sensor utilizes a coil etched onto a printed circuit board (PCB), replacing the sensor probe of traditional sensors. This design allows for a compact active magnetic bearing. However, the PCB coil structure, unlike a hollow coil, has a limited measurement range and is susceptible to external electromagnetic interference. Utility Model Content

[0008] The technical problem to be solved by the present invention is to address the deficiencies of the above-mentioned existing technologies and provide an active magnetic bearing eddy current displacement sensor based on an improved Colpitts oscillator, which is designed to obtain tiny displacement changes between the rotor and stator in real time and output corresponding rotor displacement signals. The sensor has a compact structure, excellent anti-interference performance, an expanded measurement range, and high linear accuracy, effectively improving the active magnetic bearing system's stable perception of high-speed rotor displacement.

[0009] In order to solve the above technical problems, the technical solution adopted by the present invention includes the following process:

[0010] An active magnetic bearing eddy current displacement sensor based on an improved Colpitts oscillator comprises: a probe housing, a signal processing module based on the improved Colpitts oscillator, and an output port;

[0011] The signal processing module based on the improved Colpitts oscillator is installed inside the probe housing, and the signal processing module based on the improved Colpitts oscillator is electrically connected to the output port; the output port is arranged at one end of the probe housing.

[0012] Furthermore, the signal processing module based on the improved Colpitts oscillator includes: an improved Colpitts oscillator, a peak detection module and a linear fitting module;

[0013] The improved Colpitts oscillator, the peak detection module and the linear fitting module are electrically connected in sequence to form a signal processing path.

[0014] Furthermore, the improved Colpitts oscillator comprises: a ferrite core inductor coil , capacitor voltage divider network, transistor , temperature compensation diode , bias resistor , bias resistor , emitter resistance and decoupling capacitors ; wherein the capacitor voltage divider network is composed of capacitors and capacitors Series composition;

[0015] The ferrite core inductor coil Connected in parallel with the capacitor voltage divider network to form an LC oscillation circuit; one end of the LC oscillation circuit is connected to the transistor The collector of the LC oscillation circuit is grounded; the capacitor and capacitors The midpoint of the transistor is connected The emitter resistor One end of the transistor is connected The emitter, the emitter resistor The other end of the temperature compensation diode is connected The anode of the temperature compensation diode The cathode is connected in series with a bias resistor and bias resistors , and the bias resistor The other end of the transistor is grounded; The base is connected to the bias resistor and bias resistors The midpoint of the decoupling capacitor Temperature compensation diode in parallel and bias resistors The two ends of the temperature compensation diode The anode of the .

[0016] Furthermore, the bias resistor and bias resistors The resistance value meets >> .

[0017] Furthermore, the peak detection module includes: a temperature sensor, a detection circuit, a filter capacitor and an impedance matching device;

[0018] The temperature sensor collects the temperature signal of the environment where the temperature sensor is located or the ferrite core inductor coil The temperature rise signal is obtained and all the collected signals are transmitted to the linear fitting module; the input end of the detection circuit is connected to the output end of the improved Colpitts oscillator; the output end of the detection circuit is connected to the input end of the filter capacitor; the output end of the filter capacitor is connected to the input end of the impedance matching device; the output end of the impedance matching device transmits the output analog voltage signal to the linear fitting module.

[0019] Furthermore, the temperature sensor is of model ADT7301; the detection circuit adopts a diode half-wave detection structure; and the impedance matching device is in the form of a voltage follower composed of an operational amplifier.

[0020] Furthermore, the linear fitting module includes: a single chip microcomputer and a digital-to-analog converter;

[0021] The input end of the single chip microcomputer is connected to the output end of the temperature sensor and the output end of the impedance matcher; the output end of the single chip microcomputer is connected to the input end of the digital-to-analog converter; and the output end of the digital-to-analog converter is connected to the output port through a wire.

[0022] Furthermore, the model of the single chip microcomputer is STC8A8K32S4; the model of the digital-to-analog converter is TLC5618.

[0023] The beneficial effects of adopting the above technical solution are:

[0024] The utility model proposes an active magnetic bearing eddy current displacement sensor based on an improved Colpitts oscillator. The sensor uses a high-sensitivity ferrite core excitation coil as the inductive element of the oscillation circuit. Compared with the traditional air-core coil structure, the utility model significantly improves the sensor's magnetic flux concentration capability and inductive sensitivity, reduces the influence of external electromagnetic interference, enhances the responsiveness of the oscillation signal to displacement changes, makes the oscillator output signal respond more significantly to rotor displacement changes, enhances the system's resolution and anti-interference capability, and helps to achieve stable measurement at the micron level. It is particularly suitable for precision control scenarios such as high-speed magnetic bearings.

[0025] Traditional eddy current sensors have a narrow measurement range, which can easily cause the rotor to move beyond the measurable range. However, this utility model introduces a linear fitting module in the signal post-stage, enabling the active magnetic bearing eddy current displacement sensor based on an improved Colpitts oscillator to maintain good linear characteristics over a large measurement range. This overcomes the problem of large output errors in traditional eddy current displacement sensor structures under eccentric starting or high-speed disturbance conditions. This enables the active magnetic bearing system to stably identify rotor offset trends under conditions such as eccentric starting and transient disturbances, thereby improving system robustness and measurement range.

[0026] Active magnetic bearing systems are often accompanied by electromagnetic interference sources such as high-current drives and frequent PWM switching. Therefore, this utility model improves the Colpitts oscillator, introduces a temperature compensation path, a matched filter network, a stable-amplitude transistor amplifier design, and a detection filter module, and sets a temperature-stable operating point in the amplifier. This effectively suppresses the impact of high-frequency coupling interference from high-frequency PWM signal sources such as the magnetic bearing power driver on the oscillation signal, ensuring a stable oscillator operating point, clear sensor signals, and strong anti-interference capabilities, thereby making the input signal of the rotor control algorithm more stable and reliable.

[0027] This utility model has the characteristics of compact structure, fast response and high signal quality. It is particularly suitable for high-speed, high-precision and strong anti-interference rotor position measurement scenarios in active magnetic bearing systems, providing a solid sensing foundation for achieving system closed-loop control, stable suspension and low-power operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of a single-degree-of-freedom radial active magnetic bearing system with an eddy current displacement sensor in this embodiment;

[0029] Figure 2 is a structural diagram of an active magnetic bearing eddy current displacement sensor based on an improved Colpitts oscillator in this embodiment;

[0030] Figure 3 Schematic diagram of the structure of the signal processing module based on the improved Colpitts oscillator in this embodiment;

[0031] Figure 4 Schematic diagram of the improved Colpitts oscillator circuit in this embodiment;

[0032] Figure 5 Schematic diagram of the equivalent transformer model of the active magnetic bearing eddy current displacement sensor in this embodiment;

[0033] Figure 6 This is a signal processing flow chart of an active magnetic bearing control system based on an eddy current displacement sensor in this embodiment;

[0034] In the figure: 1-probe housing; 2-output port. DETAILED DESCRIPTION

[0035] The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

[0036] like Figure 1 As shown, a single-degree-of-freedom radial active magnetic bearing system with an eddy current displacement sensor includes a position controller, a digital-to-analog / analog-to-digital converter, a power amplifier, and an eddy current displacement sensor. After the eddy current displacement sensor detects rotor displacement, it inputs the collected displacement analog signal into an analog-to-digital converter to convert it into a digital signal, which is then compared with the rotor reference position. The resulting displacement error is then input into the position controller to generate a control signal. This is then converted into an analog signal, or control current, by the analog-to-digital converter. The power amplifier then inputs equal and opposite control currents into the stator coils, generating a differential electromagnetic force on the rotor, which maintains stable suspension.

[0037] It can be seen that eddy current displacement sensors are crucial for the suspension control of active magnetic bearings.

[0038] like Figure 2 、 Figure 3 、 Figure 4 and Figure 5 As shown, this embodiment provides an active magnetic bearing eddy current displacement sensor based on an improved Colpitts oscillator. The active magnetic bearing eddy current displacement sensor includes: a probe housing, a signal processing module based on the improved Colpitts oscillator, and an output port.

[0039] The signal processing module based on the improved Colpitts oscillator is installed inside the probe housing, and the signal processing module based on the improved Colpitts oscillator is electrically connected to the output port; the output port is arranged at one end of the probe housing.

[0040] In this embodiment, the probe housing is used to fix the signal processing module based on the improved Colpitts oscillator inside the probe housing and protect the signal processing module based on the improved Colpitts oscillator to work normally. Figure 2 As shown in the figure, the probe housing is fixedly installed in the preset mounting hole of the magnetic bearing stator core, close to the radial surface of the rotor, to ensure that the active magnetic bearing eddy current displacement sensor based on the improved Colpitts oscillator can accurately detect the rotor displacement signal and transmit the rotor displacement signal to the external signal conditioning circuit through the output port.

[0041] The signal processing module based on the improved Colpitts oscillator includes: an improved Colpitts oscillator, a peak detection module and a linear fitting module.

[0042] The improved Colpitts oscillator, the peak detection module and the linear fitting module are electrically connected in sequence to form a signal processing path.

[0043] In this embodiment, if Figure 3 As shown, the active magnetic bearing eddy current displacement sensor based on an improved Colpitts oscillator exploits the relationship between changes in circuit parameters and output voltage: the sensor coil generates an alternating magnetic field, which produces eddy currents on the rotor surface. When the rotor displacement changes, the air gap changes, and the mutual inductance and equivalent impedance between the sensor coil and the rotor also change, causing changes in the circuit parameters and the output electrical signal. Therefore, the active magnetic bearing eddy current displacement sensor based on the improved Colpitts oscillator is suitable for high-speed, high-precision, and highly anti-interference rotor position measurement scenarios in active magnetic bearing systems.

[0044] The improved Colpitts oscillator comprises: a ferrite core inductor coil , capacitor voltage divider network, transistor , temperature compensation diode , bias resistor , bias resistor , emitter resistance and decoupling capacitors ; wherein the capacitor voltage divider network is composed of capacitors and capacitors Series composition.

[0045] The ferrite core inductor coil Connected in parallel with the capacitor voltage divider network to form an LC oscillation circuit; one end of the LC oscillation circuit is connected to the transistor The collector of the LC oscillation circuit is grounded; the capacitor and capacitors The midpoint of the transistor is connected The emitter resistor One end of the transistor is connected The emitter, the emitter resistor The other end of the temperature compensation diode is connected The anode of the temperature compensation diode The cathode is connected in series with a bias resistor and bias resistors , and the bias resistor The other end of the transistor is grounded; The base is connected to the bias resistor and bias resistors The midpoint of the decoupling capacitor Temperature compensation diode in parallel and bias resistors The two ends of the temperature compensation diode The anode of the .

[0046] In this embodiment, the high-frequency oscillation signal generated by the improved Colpitts oscillator is a modulated electrical signal reflecting the displacement of the magnetic bearing rotor, and serves as the original physical measurement information carrier in the entire signal processing chain.

[0047] In this embodiment, the improved Colpitts oscillator is based on the traditional Colpitts oscillator and has been improved in terms of stability and temperature compensation. Figure 4 As shown in the figure, the core of the improved Colpitts oscillator is a resonant circuit based on the Colpitts oscillator, in which the ferrite core inductor coil serves as the inductor element of the resonant circuit, and forms an LC oscillation circuit with the capacitor voltage divider network. The improved Colpitts circuit is constructed with the transistor Q1 as the excitation device to generate a high-frequency oscillation signal related to the rotor position. and bias resistors to stabilize the operating point, and use decoupling capacitors Filter out high frequency interference. Set emitter resistor in oscillator , used to suppress the temperature drift on the base-emitter voltage Improve the reference voltage of Colpitts oscillator by reducing the influence of the reference voltage, enhancing the thermal stability of the DC operating point, and introducing moderate negative feedback to improve the linearity of the circuit gain and the amplitude self-stabilization ability. Provide a stable bias for the base of the transistor to ensure that the transistor maintains normal operation in the amplification region.

[0048] In this embodiment, since the improved Colpitts oscillator operates from a relatively low single power supply, it must utilize the nonlinearity of the amplifier gain A as the amplitude stabilization component. Otherwise, a nonlinear circuit must be added to the LC feedback network F to achieve the transition from initial oscillation (AF>1) to stable oscillation (AF=1). While operational amplifiers offer excellent performance, their gain is relatively linear, making it difficult to achieve a smooth transition from AF>1 to AF=1 under low power supply conditions. Therefore, operational amplifiers are generally unsuitable for Colpitts oscillator designs operating at low power supply voltages. In contrast, transistors have a highly nonlinear gain and can serve as both amplifiers and amplitude stabilization components.

[0049] According to Kirchhoff's voltage law, >> When the bias resistor is set, the temperature drift can be fully compensated. Therefore, by setting the bias parameters, the temperature drift of the DC operating point can be stabilized and the amplitude can be stabilized. Specifically, by setting the bias resistor >> To form a stable base bias voltage, when R3>>R4, the potential of the voltage divider point is less affected by temperature, which is conducive to forming a stable base bias voltage; emitter resistance The setting can introduce appropriate negative feedback to improve the thermal stability of the amplifier; set the forward voltage drop of the temperature compensation diode and the transistor The temperature coefficients of the transistors are similar, which can effectively offset the downward trend of the bias voltage caused by temperature rise, thereby compensating for the transistors at different temperatures. Drift is reduced, thereby stabilizing the oscillator's DC operating point and achieving amplitude self-stabilization. By properly configuring the above parameters, it is possible to ensure that the oscillator maintains stable oscillation conditions under temperature changes.

[0050] The peak detection module includes: a temperature sensor, a detection circuit, a filter capacitor and an impedance matcher.

[0051] The temperature sensor collects the temperature signal of the environment where the temperature sensor is located or the ferrite core inductor coil The temperature rise signal is obtained and all the collected signals are transmitted to the linear fitting module; the input end of the detection circuit is connected to the output end of the improved Colpitts oscillator; the output end of the detection circuit is connected to the input end of the filter capacitor; the output end of the filter capacitor is connected to the input end of the impedance matching device; the output end of the impedance matching device transmits the output analog voltage signal to the linear fitting module.

[0052] The model of the temperature sensor is ADT7301; the detection circuit adopts a diode half-wave detection structure; and the impedance matching device is in the form of a voltage follower composed of an operational amplifier.

[0053] In this embodiment, if Figure 3As shown, the output of the ADT7301 temperature sensor is connected to the Serial Peripheral Interface (SPI) module within the STC8A8K32S4 microcontroller in the linear fitting module. This module collects the ambient temperature near the probe (the active magnetic bearing eddy current displacement sensor) or the temperature rise of the coil itself, providing a reference for the microcontroller's temperature compensation algorithm and enhancing the system's environmental adaptability. The detector circuit rectifies the high-frequency oscillating signal into a unidirectional pulse signal, which is used to extract the signal envelope. The filter capacitor and the detector circuit form an RC low-pass filter to smooth the pulse signal. The filter capacitor outputs a stable DC voltage signal representing the rotor displacement information. The output of the impedance matching device is connected to the ADC module within the subsequent-stage STC8A8K32S4 microcontroller. Placed after the filter capacitor, it buffers the signal to prevent load interference with the preceding filtering stage. It also adjusts the output impedance to meet the input characteristics of the subsequent-stage ADC, improving system stability.

[0054] The linear fitting module includes: a single chip microcomputer and a digital-to-analog converter.

[0055] The input end of the single chip microcomputer is connected to the output end of the temperature sensor and the output end of the impedance matcher; the output end of the single chip microcomputer is connected to the input end of the digital-to-analog converter; and the output end of the digital-to-analog converter is connected to the output port through a wire.

[0056] In this embodiment, if Figure 3 As shown in the figure, the STC8A8K32S4 microcontroller has a built-in analog-to-digital conversion unit ADC, which is used to convert the analog voltage signal output by the peak detection module into a digital signal, and then convert the digital signal into an analog signal, namely the rotor displacement signal, through a digital-to-analog converter. The analog output pin of the digital-to-analog converter is connected to the output port through a wire, and then output to the signal conditioning circuit of the active magnetic bearing system through the output port, thereby realizing high-precision detection and transmission of the rotor displacement information.

[0057] In this embodiment, if Figure 5As shown in the figure, the active magnetic bearing eddy current displacement sensor based on the improved Colpitts oscillator is modeled by an equivalent transformer model. The characteristics of the ferrite core inductor and the rotor can be represented by series resistance and inductance, which serve as the primary and secondary sides of the transformer respectively. The ferrite core inductor and the rotor form a mutual inductance coupling structure, and the equivalent impedance in the probe loop changes with the distance from the rotor, thereby changing the frequency or amplitude of the oscillation signal. The magnetic coupling caused by the eddy current effect can be represented by the mutual inductance between the primary and secondary sides. The equivalent transformer model includes the parallel resonant capacitor C, the equivalent resistance R1 and equivalent inductance L1 of the ferrite core inductor in the eddy current displacement sensor, and the rotor equivalent resistance R2 and inductance L2. Where M is the mutual inductance coefficient between L1 and L2. The larger the distance between the coil and the rotor, the smaller the mutual inductance value. U osc The signal output voltage is 1. Ferrite core inductor L1 acts as the resonant inductor element of the modified Colpitts oscillator, generating a high-frequency magnetic field that induces eddy currents on the metal rotor surface. As the rotor approaches, the equivalent impedance of the excitation coil changes, causing the output signal of the modified Colpitts oscillator to change in frequency or amplitude, thus enabling non-contact displacement detection. The rotor displacement change signal is sensed by the ferrite core inductor, and the subsequent stage sequentially performs peak extraction and linear fitting compensation to achieve a linearized displacement signal output.

[0058] The active magnetic bearing eddy current displacement sensor based on the improved Colpitts oscillator proposed in this embodiment can be integrated into the entire active magnetic bearing system and will have broad application prospects in displacement control in the aviation and industrial fields, such as Figure 6 The system includes an active magnetic bearing eddy current displacement sensor based on an improved Colpitts oscillator, a signal conditioning circuit, a DSP minimum system, an FPGA minimum system, and a host computer.

[0059] The active magnetic bearing eddy current displacement sensor based on the improved Colpitts oscillator is used to obtain small displacement changes between the magnetic bearing rotor and stator in real time, and output the corresponding analog signal, namely the rotor displacement signal, to the signal conditioning circuit.

[0060] The signal conditioning circuit is used to perform filtering, temperature compensation, amplification and shaping on the received rotor displacement signal, and convert the output voltage signal of the eddy current displacement sensor into an acceptable range for the controller processor to ensure that it meets the requirements of the subsequent sampling.

[0061] The DSP minimum system is used to complete analog signal sampling and digital processing, run the displacement closed-loop control algorithm, and output the control quantity.

[0062] The FPGA minimum system is used to receive control instructions from the DSP minimum system and generate corresponding PWM pulse signals, wherein the PWM pulse signals are used to directly drive the magnetic bearing coils to achieve dynamic adjustment of the magnetic bearing rotor position.

[0063] The host computer is used to realize the parameter adjustment, status monitoring and data recording functions of the DSP minimum system, so as to enhance the adjustability and visual operation capability of the active magnetic bearing system.

[0064] The following describes a one-time use process of the present invention in conjunction with the accompanying drawings.

[0065] like Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 and Figure 6 As shown, when in use, the probe housing is fixedly installed in the preset mounting hole of the stator core of the magnetic bearing, close to the radial surface of the rotor. Under normal working conditions, there is a certain air gap between the rotor and the ferrite core inductor coil; when the rotor displaces, the air gap between the rotor and the ferrite core inductor coil changes, and the change in the air gap causes the mutual inductance and equivalent impedance between the ferrite core inductor coil and the rotor to change. The change in mutual inductance and equivalent impedance will directly affect the circuit parameters of the improved Colpitts oscillator. Based on its circuit characteristics, the improved Colpitts oscillator converts these parameter changes into high-frequency oscillation signals and transmits them to the detection circuit in the peak detection module by rectifying the high-frequency oscillation signal into a unidirectional pulse signal and using a filter capacitor to smooth the unidirectional pulse signal to output a stable DC voltage signal; then the DC voltage signal is converted into a displacement voltage signal through an impedance matcher and transmitted to the linear fitting module. At the same time, the output end of the temperature sensor is connected to the SPI module inside the STC8A8K32S4 microcontroller in the linear fitting module to collect the ambient temperature near the active magnetic bearing eddy current displacement sensor or the temperature rise of the coil itself, and output the collected temperature signal to the microcontroller.

[0066] The linear fitting module uses the built-in analog-to-digital conversion unit (ADC) of the STC8A8K32S4 microcontroller to convert the displacement voltage signal output by the peak detection module into a digital signal. Based on the collected temperature and displacement voltage signals, the control module integrated within the microcontroller adjusts the output amplitude of the displacement voltage signal to ensure that the adjusted displacement voltage output signal remains stable under different temperature conditions. The resulting displacement signal is converted by the digital-to-analog converter into a rotor displacement signal, enabling high-precision detection and transmission of rotor displacement information.

[0067] Finally, it should be noted that the solutions in the embodiments are not intended to limit the patent protection scope of the present utility model. Any equivalent implementation or modification that does not deviate from the present utility model is included in the patent scope of this case.

Claims

1. Active magnetic bearing eddy current displacement sensor based on improved Colpitts oscillator, characterized in that: The active magnetic bearing eddy current displacement sensor includes: a probe housing, a signal processing module based on an improved Colpitts oscillator, and an output port; The signal processing module based on the improved Colpitts oscillator is installed inside the probe housing, and the signal processing module based on the improved Colpitts oscillator is electrically connected to the output port; the output port is arranged at one end of the probe housing.

2. The active magnetic bearing eddy current displacement sensor based on the improved Colpitts oscillator according to claim 1, characterized in that: The signal processing module based on the improved Colpitts oscillator includes: an improved Colpitts oscillator, a peak detection module and a linear fitting module; The improved Colpitts oscillator, the peak detection module and the linear fitting module are electrically connected in sequence to form a signal processing path.

3. The active magnetic bearing eddy current displacement sensor based on the improved Colpitts oscillator according to claim 2, characterized in that: The improved Colpitts oscillator comprises: a ferrite core inductor coil , capacitor voltage divider network, transistor , temperature compensation diode , bias resistor , bias resistor , emitter resistance and decoupling capacitors ; wherein the capacitor voltage divider network is composed of capacitors and capacitors Series composition; The ferrite core inductor coil Connected in parallel with the capacitor voltage divider network to form an LC oscillation circuit; one end of the LC oscillation circuit is connected to the transistor The collector of the LC oscillation circuit is grounded; the capacitor and capacitors The midpoint of the transistor is connected The emitter resistor One end of the transistor is connected The emitter, the emitter resistor The other end of the temperature compensation diode is connected The anode of the temperature compensation diode The cathode is connected in series with a bias resistor and bias resistors , and the bias resistor The other end of the transistor is grounded; The base is connected to the bias resistor and bias resistors The midpoint of the decoupling capacitor Temperature compensation diode in parallel and bias resistors The two ends of the temperature compensation diode The anode of the .

4. The active magnetic bearing eddy current displacement sensor based on the improved Colpitts oscillator according to claim 3, characterized in that: The bias resistor and bias resistors The resistance value meets >> .

5. The active magnetic bearing eddy current displacement sensor based on the improved Colpitts oscillator according to claim 4, characterized in that: The peak detection module includes: a temperature sensor, a detection circuit, a filter capacitor and an impedance matching device; The temperature sensor collects the temperature signal of the environment where the temperature sensor is located or the ferrite core inductor coil The temperature rise signal is obtained and all the collected signals are transmitted to the linear fitting module; the input end of the detection circuit is connected to the output end of the improved Colpitts oscillator; the output end of the detection circuit is connected to the input end of the filter capacitor; the output end of the filter capacitor is connected to the input end of the impedance matching device; the output end of the impedance matching device transmits the output analog voltage signal to the linear fitting module.

6. The active magnetic bearing eddy current displacement sensor based on the improved Colpitts oscillator according to claim 5, characterized in that: The model of the temperature sensor is ADT7301; the detection circuit adopts a diode half-wave detection structure; and the impedance matching device is in the form of a voltage follower composed of an operational amplifier.

7. The active magnetic bearing eddy current displacement sensor based on the improved Colpitts oscillator according to claim 6, characterized in that: The linear fitting module includes: a single chip microcomputer and a digital-to-analog converter; The input end of the single chip microcomputer is connected to the output end of the temperature sensor and the output end of the impedance matcher; the output end of the single chip microcomputer is connected to the input end of the digital-to-analog converter; and the output end of the digital-to-analog converter is connected to the output port through a wire.

8. The active magnetic bearing eddy current displacement sensor based on the improved Colpitts oscillator according to claim 7, characterized in that: The model of the single chip microcomputer is STC8A8K32S4; the model of the digital-to-analog converter is TLC5618.

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