Compensation device based on magnetic suspension motor and eddy current displacement sensor

Abstract

The utility model provides a compensation device based on a magnetic suspension motor and an eddy current displacement sensor, which belongs to the technical field of magnetic suspension motor unbalanced signal extraction and suppression and comprises a differential eddy current displacement sensor, a nonlinear compensation circuit, a digital signal processor, an eddy current effect compensation circuit and an upper computer. The differential eddy current displacement sensor is used for acquiring displacement information and rotor temperature of a rotor of the magnetic suspension motor, and temperature compensation is carried out on the displacement information of the rotor by adopting a temperature compensation circuit built in the differential eddy current displacement sensor according to a temperature compensation control signal of the upper computer; and the upper computer is used for correspondingly obtaining a resistance value of a variable resistor Rt in the temperature compensation circuit according to the rotor temperature and the environment temperature when receiving the rotor temperature, and sending a temperature compensation control signal to the differential eddy current displacement sensor according to the resistance value of the variable resistor Rt. According to the invention, the accuracy of signal acquisition under complex conditions is ensured.

Description

Technical Field

[0001] The utility model belongs to the technical field of unbalanced signal extraction and suppression of magnetic suspension motors, and in particular relates to a compensation device based on a magnetic suspension motor and an eddy current displacement sensor. Background Art

[0002] The magnetic levitation motor uses magnetic force to suspend the rotor and drive the rotor to rotate at high speed. It operates without contact and has the characteristics of high speed, high precision, low vibration, low noise, high efficiency and energy saving. It has been widely used in precision machining, medical equipment and other fields. Its research and discovery have broad prospects. However, the magnetic levitation motor has unbalanced vibration due to load influence, uneven mass distribution of internal components, assembly errors and other reasons.

[0003] As one of the core parts of the magnetic levitation motor system, the eddy current sensor can accurately monitor the radial and axial displacement of the rotor and provide real-time position feedback information. By monitoring the displacement changes of the rotor through the displacement sensor, the position of the rotor can be detected in time. Based on these data, the control system can take corresponding measures to suppress unbalanced vibration and ensure the stability and safety of the system at high speed. If the signal generated by the sensor cannot be well received by the controller, the unbalanced vibration of the magnetic bearing motor will not be controlled, thereby affecting the speed of the motor and causing major safety accidents due to rotor imbalance. Therefore, it is very important to process the displacement sensor signal.

[0004] At present, the temperature compensation of eddy current sensors is generally achieved by adding probes or changing the probe structure or by software algorithms to suppress the influence of temperature on signal output, or the influence of rotor temperature on eddy current sensors is not considered. At the same time, the nonlinear compensation module generally only suppresses the high-frequency signals in the signal. This makes the displacement sensor design costly and cannot handle the influence of the rotor's eddy current effect on the signal output, resulting in poor extraction and suppression of unbalanced vibration signals. When there is the influence of the rotor eddy current effect and temperature changes, a module and method that does not change the mechanical structure of the coil while achieving temperature compensation and harmonic suppression is needed. Utility Model Content

[0005] In view of the shortcomings of the prior art, the present application proposes a compensation device based on a magnetic levitation motor and an eddy current displacement sensor, comprising:

[0006] Differential eddy current displacement sensor, nonlinear compensation circuit, digital signal processor, eddy current effect compensation circuit, host computer;

[0007] The differential eddy current displacement sensor is connected to the magnetic levitation motor, the host computer and the eddy current effect compensation circuit respectively, and is used to obtain the displacement information of the rotor of the magnetic levitation motor, and simultaneously obtain the rotor temperature of the magnetic levitation motor, and according to the temperature compensation control signal of the host computer, the temperature compensation circuit built in the differential eddy current displacement sensor is used to perform temperature compensation on the displacement information of the rotor;

[0008] The nonlinear compensation circuit is connected to the differential eddy current displacement sensor and the digital signal processor, respectively, and is used to receive the displacement information of the rotor transmitted from the differential eddy current displacement sensor, eliminate the interference signal in the displacement information of the rotor, and send the displacement information of the rotor after the interference is eliminated to the digital signal processor;

[0009] The digital signal processor is connected to the nonlinear compensation circuit, the host computer and the eddy current effect compensation circuit respectively, and is used to set the displacement information of the rotor after interference removal to a differential mode, and perform analog-to-digital conversion on the displacement information of the rotor in the differential mode to obtain digital displacement information of the rotor, and send the digital displacement information of the rotor to the host computer;

[0010] The eddy current effect compensation circuit is connected to the digital signal processor and the differential eddy current displacement sensor respectively, and is used to perform eddy current effect compensation processing on the digital rotor displacement information, and send the compensation current generated by the eddy current effect compensation circuit to the differential eddy current displacement sensor;

[0011] The host computer is respectively connected to the differential eddy current displacement sensor, the nonlinear compensation circuit, and the digital signal processor, and is used to obtain the resistance value of the variable resistor Rt in the temperature compensation circuit according to the rotor temperature and the ambient temperature when the rotor temperature is received, send a temperature compensation control signal to the differential eddy current displacement sensor according to the resistance value of the variable resistor Rt, and receive and save the digital rotor displacement information at the same time.

[0012] The digital signal processor is further used to receive the coil current of the current sensor in the eddy current effect compensation circuit, generate a PWM signal according to the coil current, and send the PWM signal to the eddy current effect compensation circuit;

[0013] The eddy current effect compensation circuit is also used to receive a PWM signal and convert the PWM signal into a compensation current.

[0014] The host computer is also used to send a correction control signal to the nonlinear compensation circuit;

[0015] The nonlinear compensation circuit is further used to correct the displacement information of the rotor after interference according to the correction control signal, and send the corrected displacement information of the rotor to the digital signal processor.

[0016] The differential eddy current displacement sensor includes: a radial displacement sensor, an axial displacement sensor and a temperature sensor; the radial displacement sensor is installed on one side of the radial magnetic bearing of the magnetic levitation motor, and is used to detect the radial displacement of the rotor of the magnetic levitation motor; the axial displacement sensor is installed on one side of the axial magnetic bearing of the magnetic levitation motor, and is used to detect the axial displacement of the rotor of the magnetic levitation motor; the temperature sensor is installed between the sheath and the permanent magnet of the magnetic levitation motor, and is placed at multiple points along the axial and radial directions of the rotor of the magnetic levitation motor, and is used to detect the rotor temperature of the magnetic levitation motor.

[0017] The eddy current effect compensation circuit includes a current sensor, which is installed at the bearing winding coil of the magnetic levitation motor. A differential placement method is adopted to establish a three-dimensional coordinate system with the center of the cross section of the rotor of the magnetic levitation motor as the origin of the three-dimensional coordinate system, and the cross section of the rotor of the magnetic levitation motor is the plane composed of the X-axis and the Y-axis of the three-dimensional coordinate system. The rotor length direction of the magnetic levitation motor is the Z-axis direction of the three-dimensional coordinate system.

[0018] There are eight radial displacement sensors, four of which are respectively located on one side of a radial first magnetic bearing close to the magnetic levitation motor, and the other four are respectively located on one side of a second radial magnetic bearing close to the magnetic levitation motor. One radial displacement sensor is installed in the positive direction of the X-axis, one radial displacement sensor is installed in the negative direction of the X-axis, one radial displacement sensor is installed in the positive direction of the Y-axis, and one radial displacement sensor is installed in the negative direction of the Y-axis, wherein the two radial displacement sensors in the positive direction of the X-axis and the negative direction of the X-axis form a pair, and the two radial displacement sensors in the positive direction of the Y-axis and the negative direction of the Y-axis form a pair.

[0019] The temperature compensation circuit includes: a differential eddy current displacement sensor equivalent resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a first capacitor C1, a differential eddy current displacement sensor equivalent inductor L, a first operational amplifier A1, a first transistor Q1, and a variable resistor Rt;

[0020] Among them, the second end of the differential eddy current displacement sensor equivalent resistor R1 is connected to the second end of the first capacitor C1, the first end of the first capacitor C1 is connected to the first end of the differential eddy current displacement sensor equivalent inductor L, the second end of the differential eddy current displacement sensor equivalent inductor L is connected to the first end of the differential eddy current displacement sensor equivalent resistor R1, and the two ends of the first capacitor C1 are used as output signals of the displacement information of the rotor after temperature compensation; the collector of the first transistor Q1 is respectively connected to the second end of the differential eddy current displacement sensor equivalent resistor R1 and the second end of the seventh resistor R7, and the first end of the seventh resistor R7 is connected to the differential eddy current displacement sensor equivalent resistor R1. The first end of the inductor L is connected, the emitter of the first triode Q1 is connected to the first end of the eighth resistor R8, the collector of the first triode Q1 is respectively connected to the second end of the variable resistor Rt and the first end of the sixth resistor R6, the second end of the sixth resistor R6 is connected to the second end of the eighth resistor R8, the first end of the variable resistor Rt is respectively connected to the output end of the first operational amplifier A1 and the second end of the second resistor R2, the positive input end of the first operational amplifier A1 is respectively connected to the second end of the third resistor R3 and the first end of the fifth resistor R5, and the positive and negative input ends of the first operational amplifier A1 are respectively connected to the first end of the second resistor R2 and the first end of the fourth resistor R4.

[0021] The nonlinear compensation circuit includes: four operational amplifiers of the same model, the positive input terminal of the second operational amplifier B1 is connected to the moving end of the ninth resistor R9, the negative input terminal of the third operational amplifier B2 is connected to the first end of the tenth resistor R10, and the output terminal of the third operational amplifier B2 is respectively connected to the second end of the tenth resistor R10 and the moving end of the tenth resistor R10.

[0022] The nonlinear compensation circuit is also used to adjust the amplitude of the output signal of the nonlinear compensation circuit by adjusting the sizes of V1A and V1B in a balanced state of the nonlinear compensation circuit, thereby correcting the displacement information of the rotor output by the differential eddy current displacement sensor, wherein V1A is the voltage value between the first end of the ninth resistor R9 and the moving end of the ninth resistor R9, and V1B is the voltage value between the moving end of the tenth resistor R10 and the second end of the tenth resistor R10.

[0023] The host computer has a communication module, which is used to communicate with the digital signal processor and includes: a CAN communication unit and a USB to CAN converter. The first end of the CAN communication unit is connected to the digital signal processor, the second end of the CAN communication unit is connected to the first end of the USB to CAN converter, and the second end of the USB to CAN converter is connected to the host computer.

[0024] Beneficial Effects

[0025] The present application proposes a compensation device based on a magnetic levitation motor and an eddy current displacement sensor, and provides a temperature compensation circuit for the eddy current displacement sensor of the magnetic levitation motor. By coordinating the temperature sensor detection and the ambient temperature, the resistance value is adjusted to compensate for the drift caused by the temperature on the displacement signal measurement. A differential input is implemented for the displacement sensor signal, which reduces the nonlinearity of the signal output. The nonlinear compensation circuit can calibrate the eddy current sensor to reflect the correct position of the rotor on the host computer. The eddy current compensation circuit reduces the interference of the eddy current effect on the acquisition of the rotor displacement signal. Compared with the traditional displacement sensor compensation module, the differential eddy current displacement sensor of the present application ensures the accuracy of signal acquisition in complex situations, while reducing the complexity and design cost of the system hardware. At the same time, the present application better improves the speed of signal acquisition and conditioning through the mutual cooperation between hardware. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the principle of the compensation device based on the magnetic suspension motor and the eddy current displacement sensor according to the embodiment of the utility model;

[0027] Figure 2 A schematic diagram of the temperature compensation circuit principle of an embodiment of the utility model;

[0028] Figure 3 A diagram of a differential signal processing structure of an embodiment of the utility model;

[0029] Figure 4 A schematic diagram of a single-phase full-bridge main circuit according to an embodiment of the utility model;

[0030] Figure 5 Temperature compensation flow chart of the embodiment of the utility model;

[0031] Figure 6 A schematic diagram of harmonic detection in an embodiment of the utility model;

[0032] Figure 7 A cross-sectional structural diagram of a magnetic bearing according to an embodiment of the utility model;

[0033] Figure 8 Schematic diagram of the placement of the differential eddy current displacement sensor according to an embodiment of the utility model. DETAILED DESCRIPTION

[0034] The specific implementation of the present application is further described in detail below in conjunction with the drawings and examples.

[0035] Example:

[0036] This embodiment proposes a compensation device based on a magnetic levitation motor and an eddy current displacement sensor, such as Figure 1 As shown, including:

[0037] Differential eddy current displacement sensor, nonlinear compensation circuit, digital signal processor (DSP, Digital Signal Processing), eddy current effect compensation circuit, host computer;

[0038] The differential eddy current displacement sensor is connected to the magnetic levitation motor, the host computer and the eddy current effect compensation circuit respectively, and is used to obtain the displacement information of the rotor of the magnetic levitation motor, and simultaneously obtain the rotor temperature of the magnetic levitation motor, and according to the temperature compensation control signal of the host computer, the temperature compensation circuit built in the differential eddy current displacement sensor is used to perform temperature compensation on the displacement information of the rotor;

[0039] The nonlinear compensation circuit is connected to the differential eddy current displacement sensor and the digital signal processor, respectively, and is used to receive the displacement information of the rotor transmitted from the differential eddy current displacement sensor, eliminate the interference signal in the displacement information of the rotor, and send the displacement information of the rotor after the interference is eliminated to the digital signal processor;

[0040] The digital signal processor is connected to the nonlinear compensation circuit, the host computer and the eddy current effect compensation circuit respectively, and is used to set the displacement information of the rotor after interference removal to a differential mode, and perform analog-to-digital conversion on the displacement information of the rotor in the differential mode to obtain digital displacement information of the rotor, and send the digital displacement information of the rotor to the host computer;

[0041] The eddy current effect compensation circuit is connected to the digital signal processor and the differential eddy current displacement sensor respectively, and is used to perform eddy current effect compensation processing on the digital rotor displacement information, and send the compensation current generated by the eddy current effect compensation circuit to the differential eddy current displacement sensor;

[0042] The host computer is respectively connected to the differential eddy current displacement sensor, the nonlinear compensation circuit, and the digital signal processor, and is used to obtain the resistance value of the variable resistor Rt in the temperature compensation circuit according to the rotor temperature and the ambient temperature when the rotor temperature is received, send a temperature compensation control signal to the differential eddy current displacement sensor according to the resistance value of the variable resistor Rt, and receive and save the digital rotor displacement information at the same time.

[0043] In this embodiment, the magnetic suspension motor is the control object, the differential eddy current displacement sensor is the temperature compensation object, and the differential eddy current displacement sensor is used to measure the displacement signal of the unbalanced vibration of the magnetic suspension motor. The magnetic suspension motor is a magnetic suspension permanent magnet synchronous motor, which is composed of a magnetic suspension bearing and a permanent magnet synchronous motor, wherein the magnetic suspension bearing includes: two radial magnetic bearings and one axial magnetic bearing, such as Figure 7As shown, it is used to control the radial and axial displacement of the rotor, each magnetic pole is wound with a coil, and the rotor is suspended by generating electromagnetic force through power. The magnetic suspension permanent magnet synchronous motor is composed of a magnetic suspension bearing and a permanent magnet synchronous motor, wherein the magnetic suspension bearing includes two radial magnetic bearings and one axial magnetic bearing, which are used to control the radial and axial displacement of the rotor, each magnetic pole is wound with a coil, and the rotor is suspended by generating electromagnetic force through power.

[0044] The digital signal processor is further used to receive the coil current of the current sensor in the eddy current effect compensation circuit, generate a PWM signal according to the coil current, and send the PWM signal to the eddy current effect compensation circuit;

[0045] The eddy current effect compensation circuit is also used to receive a PWM signal and convert the PWM signal into a compensation current.

[0046] In this embodiment, the digital signal processor receives the coil current of the current sensor in the eddy current effect compensation circuit, uses the ip-iq detection algorithm to separate the harmonic and fundamental waves of the coil current of the current sensor, generates a PWM signal that offsets the harmonic source, and converts the PWM signal into a compensation current and injects it back into the circuit. Specifically, the compensation current is input into the circuit corresponding to the differential eddy current displacement sensor, such as Figure 2 As shown, the IP-IQ detection algorithm is a method for harmonic detection using instantaneous reactive power signals in the power system.

[0047] In this embodiment, the differential eddy current displacement sensor collects the displacement information of the rotor and feeds it back to the host computer; the differential eddy current displacement sensor includes a radial displacement sensor and an axial displacement sensor, the radial displacement sensor is installed at one side of the radial magnetic bearing, and the axial displacement sensor is installed at one side of the axial magnetic bearing; Figure 8 As shown, the current sensor is installed at the winding coil of the magnetic suspension bearing, and is placed differentially; a three-dimensional coordinate system is established with the center of the rotor cross section as the origin, the cross section is the XY plane, the rotor length direction is the Z axis direction, and the four radial displacement sensors are respectively placed in the positive and negative directions of the X axis and the positive and negative directions of the Y axis close to the radial magnetic bearing. The two displacement sensors in the positive and negative directions of the X axis are a pair, and the positive and negative directions of the Y axis are a pair. The displacement signal is collected by differential signal processing. Since there is a radial magnetic bearing at each end of the rotor, a total of eight radial displacement sensors are placed. Four axial displacement sensors are also placed 90 degrees apart and close to the side of the axial magnetic bearing.

[0048] The differential eddy current displacement sensor includes: a radial displacement sensor, an axial displacement sensor and a temperature sensor; the radial displacement sensor is installed on one side of the radial magnetic bearing of the magnetic levitation motor, and is used to detect the radial displacement of the rotor of the magnetic levitation motor; the axial displacement sensor is installed on one side of the axial magnetic bearing of the magnetic levitation motor, and is used to detect the axial displacement of the rotor of the magnetic levitation motor; the temperature sensor is installed between the sheath and the permanent magnet of the magnetic levitation motor, and is placed at multiple points along the axial and radial directions of the rotor of the magnetic levitation motor, and is used to detect the rotor temperature of the magnetic levitation motor.

[0049] In this embodiment, the differential eddy current displacement sensor adopts an eddy current sensor, and a capacitor C1 is connected in parallel on one side of the equivalent resistance and equivalent inductance L of the sensor coil as an excitation oscillation output circuit of the signal, and the collector of the transistor is connected to the sensor coil and the excitation oscillation circuit. The emitter of the transistor is connected to the resistor R8, and the collector temperature variable resistors Rt and R6 are connected in parallel. At the same time, Rt is connected in series with the amplifier circuit, and the positive input terminal R3 and the resistor R5 of the proportional amplifier circuit operational amplifier are connected in parallel. At the same time, a differential eddy current sensor is used, and the signals generated by the two are differentially calculated to improve the linearity of the output signal. The inverting input terminal of the A5 operational amplifier is connected to the capacitor to the output terminal of the operational amplifier, such as Figure 4 shown.

[0050] The host computer is also used to send a correction control signal to the nonlinear compensation circuit;

[0051] The nonlinear compensation circuit is further used to correct the displacement information of the rotor after interference according to the correction control signal, and send the corrected displacement information of the rotor to the digital signal processor.

[0052] The nonlinear compensation circuit includes four operational amplifiers of the same model, such as Figure 3 As shown, they are B1, B2, B3, and B4 respectively. The input voltage of operational amplifier B1 is adjusted by sliding rheostat V1A. The first operational amplifier B1 forms a voltage follower circuit. The output voltage of the eddy current sensor and the output end of B1 are connected to the reverse output end of B2, and the output end of B2 is connected to the same-direction input end of B3. A sliding rheostat V2A is placed between the reverse input end and the output end of B2. V1A and V2A jointly affect the output voltage of B2, thereby adjusting the eddy current sensor probe. The input and output ends of U1C are connected to a second-order low-pass filter circuit. Two diode array voltage regulator circuits are connected between U1C and U1D, one is connected to a 3.3V power supply, and the other is grounded.

[0053] In this embodiment, the nonlinear compensation circuit is also used to adjust the amplitude of the output signal of the nonlinear compensation circuit by adjusting the values ​​of V1A and V1B in a balanced state of the nonlinear compensation circuit, thereby correcting the displacement information of the rotor output by the differential eddy current displacement sensor, such as Figure 3 As shown, the positive input terminal of the second operational amplifier B1 is connected to the moving end of the ninth resistor R9, the negative input terminal of the third operational amplifier B2 is connected to the first end of the tenth resistor R10, the output terminal of the third operational amplifier B2 is respectively connected to the second end of the tenth resistor R10 and the moving end of the tenth resistor R10, V1A is the voltage value between the first end of the ninth resistor R9 and the moving end of the ninth resistor R9, and V1B is the voltage value between the moving end of the tenth resistor R10 and the second end of the tenth resistor R10.

[0054] The host computer communication module includes CAN, a host computer and an intelligent USB to CAN converter, one end of the CAN is connected to the DSP chip of the controller module, and the other end is connected to the intelligent USB to CAN converter, one end of the intelligent USB to CAN converter is connected to the CAN, and the other end is connected to the host computer.

[0055] The eddy current effect compensation circuit includes a drive isolation circuit, a Hall voltage sensor, and a current sensor. The input end of the eddy current effect compensation circuit is connected to the output end of the controller module of the host computer to receive the PWM signal output by the controller module. It specifically includes a drive module and a single-phase full-bridge main circuit. The isolation module is connected to the output end of the controller module. The input and output ends of the drive module are respectively connected to the isolation module and the single-phase full-bridge inverter circuit. The single-phase full inverter circuit is connected to the eddy current displacement sensor circuit; the single-phase full-bridge main circuit is composed of four bridge arms in parallel, and each bridge arm is composed of a diode, an IGBT (insulated gate bipolar transistor) and in parallel.

[0056] The temperature compensation circuit has the function of compensating for temperature drift, thereby reducing the error in rotor displacement measurement caused by ambient temperature changes. Figure 2 As shown, it includes: a differential eddy current displacement sensor equivalent resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a first capacitor C1, a differential eddy current displacement sensor equivalent inductor L, a first operational amplifier A1, a first transistor Q1, and a variable resistor Rt;

[0057] Among them, the second end of the differential eddy current displacement sensor equivalent resistor R1 is connected to the second end of the first capacitor C1, the first end of the first capacitor C1 is connected to the first end of the differential eddy current displacement sensor equivalent inductor L, the second end of the differential eddy current displacement sensor equivalent inductor L is connected to the first end of the differential eddy current displacement sensor equivalent resistor R1, and the two ends of the first capacitor C1 are used as output signals of the displacement information of the rotor after temperature compensation; the collector of the first transistor Q1 is respectively connected to the second end of the differential eddy current displacement sensor equivalent resistor R1 and the second end of the seventh resistor R7, and the first end of the seventh resistor R7 is connected to the differential eddy current displacement sensor equivalent resistor R1. The first end of the inductor L is connected, the emitter of the first triode Q1 is connected to the first end of the eighth resistor R8, the collector of the first triode Q1 is respectively connected to the second end of the variable resistor Rt and the first end of the sixth resistor R6, the second end of the sixth resistor R6 is connected to the second end of the eighth resistor R8, the first end of the variable resistor Rt is respectively connected to the output end of the first operational amplifier A1 and the second end of the second resistor R2, the positive input end of the first operational amplifier A1 is respectively connected to the second end of the third resistor R3 and the first end of the fifth resistor R5, and the positive and negative input ends of the first operational amplifier A1 are respectively connected to the first end of the second resistor R2 and the first end of the fourth resistor R4.

[0058] In this implementation, the DSP of the controller part of the host computer adopts TI's 28335 series chip, the current sensor adopts LA25-NP current transformer; the diode array MMBD7000, CAN adopts USBCAN-8E-U intelligent converter, in the power amplifier module, the isolation module adopts 6N137 optical coupler, and the drive module adopts IR2110 driver.

[0059] The compensation of the eddy current displacement sensor of the magnetic levitation motor is realized by a temperature compensation circuit built into the differential eddy current displacement sensor of the magnetic levitation motor, such as Figure 1 As shown, the specific steps are as follows:

[0060] Step 1: After the differential eddy current displacement sensor collects displacement information, it detects the ambient temperature and the rotor temperature. The temperature compensation structure inside the eddy current sensor compensates for the error caused by the temperature drift. According to the relationship between the coil output resistance and the temperature (technical personnel in this field can easily obtain the relationship between the difference between the ambient temperature and the rotor temperature and the variable resistance Rt, and save the relationship in the host computer), the resistance is adjusted to a suitable resistance value for temperature compensation, such as Figure 5As shown. Subsequently, the displacement information collected by the differential eddy current displacement sensor is converted into a voltage signal, and the current signal collected by the current sensor is converted into a voltage signal, and then processed together by a nonlinear compensation circuit to eliminate the high-frequency signal generated by the external sensor interference in the signal, and at the same time, the feedback voltage signal is within the receiving range of the DSP; finally, the current and displacement signals obtained after the nonlinear compensation circuit processing are transmitted to the AD sampling chip, and the sampling chip is connected to the DSP, and the displacement signal is set to the differential mode, and the digital-to-analog conversion is performed to generate the rotor displacement signal.

[0061] In the temperature compensation circuit, the temperature sensor adjusts the resistance value of the resistor Rt after monitoring the temperature, thereby adjusting the amplification factor of the transistor to compensate for temperature drift. Z0 is the impedance value after the sensor coil and the capacitor C1 are connected in parallel. When the temperature rises, the Z0 value will decrease, causing the output amplitude to decrease, and at the same time, the eddy current sensor is placed in a constant temperature environment, reducing the influence of the ambient temperature on the sensor probe, and only the influence of the temperature change inside the rotor on the measurement needs to be compensated. The temperature inside the rotor is measured using a wireless contact temperature sensor. The temperature sensor is installed between the sheath and the permanent magnet, and is placed at multiple points along the axial and radial directions of the motor rotor. The temperature sensor leads out a cable to transmit the temperature data to a wireless transmission device, which is placed at the end of the rotor and is equipped with an independent battery power supply. The wireless transmission device sends the measured temperature signal to the host computer, and the host computer stores the data. After the host computer receives the rotor temperature signal and the ambient temperature, it corresponds to the relationship between the preset temperature change and the variable resistor Rt, obtains the required Rt value, adjusts the Rt value through the digital potentiometer, and finally stabilizes the output voltage, and finally achieves the effect of temperature compensation.

[0062] Step 2: After the displacement signal is collected, the eddy current effect compensation processing is performed on the superharmonic and subharmonic frequency components in the generated displacement signal. The host computer collects the voltage and current signals on the circuit through the Hall current sensor and voltage sensor and sends them to the AD converter. The converted current is sent to the DSP for processing. The DSP uses the ip-iq detection algorithm to separate the harmonics and the fundamental wave, such as Figure 6 As shown, according to the obtained indication current signal, a PWM signal for offsetting the harmonic source is generated through the current control circuit, and the inverter module is driven to generate a harmonic suppression source with the same amplitude and frequency as the signal harmonic and a phase difference of 180°, so as to achieve harmonic signal offset, thereby eliminating the harmonic signal.

[0063] The eddy current effect processing module eliminates the influence of the eddy current effect on the rotor displacement measurement. The eddy current effect will cause the electromagnetic force of the magnetic suspension bearing to change, thereby causing the frequency response curve of the rotor to produce high harmonics and subharmonics.

[0064] Step 3: DSP processes and caches the displacement information of the rotor. In order to facilitate the adjustment, a virtual instrument is designed in the host computer using LABVIEW to edit the monitoring interface of the rotor position and operating status, and the rotor position is intuitively reflected at the same time. The host computer reflects the magnetic bearing status on the virtual instrument based on the displacement information transmitted by the eddy current sensor. In the balanced state, the amplitude of the output signal is adjusted by adjusting the size of V1A and V1B to calibrate the eddy current sensor.

[0065] The various embodiments in the present application are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0066] The protection scope of the present application is not limited to the above-mentioned embodiments. Obviously, those skilled in the art can make various changes and modifications to the present disclosure without departing from the scope and spirit of the present disclosure. If these changes and modifications fall within the scope of the claims of the present disclosure and their equivalents, the intention of the present disclosure also includes these changes and modifications.

Claims

1. A compensation device based on a magnetic levitation motor and an eddy current displacement sensor, characterized in that: include: Differential eddy current displacement sensor, nonlinear compensation circuit, digital signal processor, eddy current effect compensation circuit, host computer; The differential eddy current displacement sensor is connected to the magnetic levitation motor, the host computer and the eddy current effect compensation circuit respectively, and is used to obtain the displacement information of the rotor of the magnetic levitation motor, and simultaneously obtain the rotor temperature of the magnetic levitation motor, and according to the temperature compensation control signal of the host computer, the temperature compensation circuit built in the differential eddy current displacement sensor is used to perform temperature compensation on the displacement information of the rotor; The nonlinear compensation circuit is connected to the differential eddy current displacement sensor and the digital signal processor, respectively, and is used to receive the displacement information of the rotor transmitted from the differential eddy current displacement sensor, eliminate the interference signal in the displacement information of the rotor, and send the displacement information of the rotor after the interference is eliminated to the digital signal processor; The digital signal processor is connected to the nonlinear compensation circuit, the host computer and the eddy current effect compensation circuit respectively, and is used to set the displacement information of the rotor after interference removal to a differential mode, and perform analog-to-digital conversion on the displacement information of the rotor in the differential mode to obtain digital displacement information of the rotor, and send the digital displacement information of the rotor to the host computer; The eddy current effect compensation circuit is connected to the digital signal processor and the differential eddy current displacement sensor respectively, and is used to perform eddy current effect compensation processing on the digital rotor displacement information, and send the compensation current generated by the eddy current effect compensation circuit to the differential eddy current displacement sensor; The host computer is respectively connected to the differential eddy current displacement sensor, the nonlinear compensation circuit, and the digital signal processor, and is used to obtain the resistance value of the variable resistor Rt in the temperature compensation circuit according to the rotor temperature and the ambient temperature when the rotor temperature is received, send a temperature compensation control signal to the differential eddy current displacement sensor according to the resistance value of the variable resistor Rt, and receive and save the digital rotor displacement information at the same time.

2. The compensation device based on magnetic levitation motor and eddy current displacement sensor according to claim 1 is characterized in that: The digital signal processor is further used to receive the coil current of the current sensor in the eddy current effect compensation circuit, generate a PWM signal according to the coil current, and send the PWM signal to the eddy current effect compensation circuit; The eddy current effect compensation circuit is also used to receive a PWM signal and convert the PWM signal into a compensation current.

3. The compensation device based on magnetic levitation motor and eddy current displacement sensor according to claim 1 is characterized in that: The host computer is also used to send a correction control signal to the nonlinear compensation circuit; The nonlinear compensation circuit is further used to correct the displacement information of the rotor after interference according to the correction control signal, and send the corrected displacement information of the rotor to the digital signal processor.

4. The compensation device based on magnetic levitation motor and eddy current displacement sensor according to claim 1 is characterized in that: The differential eddy current displacement sensor includes: a radial displacement sensor, an axial displacement sensor and a temperature sensor; the radial displacement sensor is installed on one side of the radial magnetic bearing of the magnetic levitation motor, and is used to detect the radial displacement of the rotor of the magnetic levitation motor; the axial displacement sensor is installed on one side of the axial magnetic bearing of the magnetic levitation motor, and is used to detect the axial displacement of the rotor of the magnetic levitation motor; the temperature sensor is installed between the sheath and the permanent magnet of the magnetic levitation motor, and is placed at multiple points along the axial and radial directions of the rotor of the magnetic levitation motor, and is used to detect the rotor temperature of the magnetic levitation motor.

5. The compensation device based on magnetic levitation motor and eddy current displacement sensor according to claim 1 is characterized in that: The eddy current effect compensation circuit includes a current sensor, which is installed at the bearing winding coil of the magnetic levitation motor. A differential placement method is adopted to establish a three-dimensional coordinate system with the center of the cross section of the rotor of the magnetic levitation motor as the origin of the three-dimensional coordinate system, and the cross section of the rotor of the magnetic levitation motor is the plane composed of the X-axis and the Y-axis of the three-dimensional coordinate system. The rotor length direction of the magnetic levitation motor is the Z-axis direction of the three-dimensional coordinate system.

6. The compensation device based on magnetic levitation motor and eddy current displacement sensor according to claim 4 is characterized in that: There are eight radial displacement sensors, four of which are respectively located on one side of a radial first magnetic bearing close to the magnetic levitation motor, and the other four are respectively located on one side of a second radial magnetic bearing close to the magnetic levitation motor. One radial displacement sensor is installed in the positive direction of the X-axis, one radial displacement sensor is installed in the negative direction of the X-axis, one radial displacement sensor is installed in the positive direction of the Y-axis, and one radial displacement sensor is installed in the negative direction of the Y-axis, wherein the two radial displacement sensors in the positive direction of the X-axis and the negative direction of the X-axis form a pair, and the two radial displacement sensors in the positive direction of the Y-axis and the negative direction of the Y-axis form a pair.

7. The compensation device based on magnetic levitation motor and eddy current displacement sensor according to claim 1 is characterized in that: The temperature compensation circuit includes: a differential eddy current displacement sensor equivalent resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a first capacitor C1, a differential eddy current displacement sensor equivalent inductor L, a first operational amplifier A1, a first transistor Q1, and a variable resistor Rt; Among them, the second end of the differential eddy current displacement sensor equivalent resistor R1 is connected to the second end of the first capacitor C1, the first end of the first capacitor C1 is connected to the first end of the differential eddy current displacement sensor equivalent inductor L, the second end of the differential eddy current displacement sensor equivalent inductor L is connected to the first end of the differential eddy current displacement sensor equivalent resistor R1, and the two ends of the first capacitor C1 are used as output signals of the displacement information of the rotor after temperature compensation; the collector of the first transistor Q1 is respectively connected to the second end of the differential eddy current displacement sensor equivalent resistor R1 and the second end of the seventh resistor R7, and the first end of the seventh resistor R7 is connected to the differential eddy current displacement sensor equivalent resistor R1. The first end of the inductor L is connected, the emitter of the first triode Q1 is connected to the first end of the eighth resistor R8, the collector of the first triode Q1 is respectively connected to the second end of the variable resistor Rt and the first end of the sixth resistor R6, the second end of the sixth resistor R6 is connected to the second end of the eighth resistor R8, the first end of the variable resistor Rt is respectively connected to the output end of the first operational amplifier A1 and the second end of the second resistor R2, the positive input end of the first operational amplifier A1 is respectively connected to the second end of the third resistor R3 and the first end of the fifth resistor R5, and the positive and negative input ends of the first operational amplifier A1 are respectively connected to the first end of the second resistor R2 and the first end of the fourth resistor R4.

8. The compensation device based on magnetic levitation motor and eddy current displacement sensor according to claim 1 is characterized in that: The nonlinear compensation circuit includes: four operational amplifiers of the same model, the positive input terminal of the second operational amplifier B1 is connected to the moving end of the ninth resistor R9, the negative input terminal of the third operational amplifier B2 is connected to the first end of the tenth resistor R10, and the output terminal of the third operational amplifier B2 is respectively connected to the second end of the tenth resistor R10 and the moving end of the tenth resistor R10.

9. The compensation device based on magnetic levitation motor and eddy current displacement sensor according to claim 1 is characterized in that: The nonlinear compensation circuit is also used to adjust the amplitude of the output signal of the nonlinear compensation circuit by adjusting the sizes of V1A and V1B in a balanced state of the nonlinear compensation circuit, thereby correcting the displacement information of the rotor output by the differential eddy current displacement sensor, wherein V1A is the voltage value between the first end of the ninth resistor R9 and the moving end of the ninth resistor R9, and V1B is the voltage value between the moving end of the tenth resistor R10 and the second end of the tenth resistor R10.

10. The compensation device based on magnetic levitation motor and eddy current displacement sensor according to claim 1, characterized in that: The host computer has a communication module, which is used to communicate with the digital signal processor and includes: a CAN communication unit and a USB to CAN converter. The first end of the CAN communication unit is connected to the digital signal processor, the second end of the CAN communication unit is connected to the first end of the USB to CAN converter, and the second end of the USB to CAN converter is connected to the host computer.

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