CN111220101B - Microwave-based online measurement method and device for rotor-stator axial gap - Google Patents

Abstract

The invention belongs to the field of non-contact distance measurement, and aims to realize the non-contact real-time online accurate measurement of the axial gap of the rotor and stator of an aero-engine under the condition of limited space. To this end, the technical solution adopted in the present invention is that the microwave-based rotor-stator axial gap online measuring device is composed of a microwave signal generating module, a signal power amplifying module, a signal receiving and frequency mixing module, a signal conditioning and acquisition module, a circulator, a microwave It consists of a sensor. The carrier signal generated by the microwave signal generation module is amplified by the signal power amplifying module, and then enters the first port of the circulator and is output from the second port of the circulator; the second port of the circulator is connected to the microwave sensor. , the microwave sensor transmits the carrier signal to the axial end face of the rotor under test, and simultaneously receives the reflected signal of the carrier wave from the axial end face of the rotor, returns it to the second port of the circulator, and outputs it from the third port of the circulator. The invention is mainly applied to the occasion of non-contact distance measurement.

Description

Microwave-based online measurement method and device for rotor-stator axial gap

technical field

The invention belongs to the field of non-contact distance measurement. Specifically, the present invention relates to a microwave-based method and device for online measurement of rotor-stator axial gap, in particular to an on-line rotor-stator axial gap using a carrier path and a reference path cross-mixing structure to suppress co-frequency interference signals Measurement methods and devices.

Background technique

Modern aero-engines are developing in the direction of high thrust-to-weight ratio, high boost ratio and high vortex front temperature. On the one hand, aero-engines are affected by speed changes, temperature loads and aerodynamic loads. The thermal expansion of the box is inconsistent, and too small axial clearance will increase the shaft work, reduce the efficiency, reduce the flow capacity, deteriorate the aerodynamic performance, and even cause the rotor and the stator to rub against each other, affecting the safety and reliability of the engine; on the other hand, the shaft The narrowing design of the clearance is conducive to shortening the size of the engine, making the engine stages more compact, reducing the weight of the engine, and effectively increasing the thrust-to-weight ratio. At present, aero-engine active clearance control technology has become one of the symbol technologies of modern engines. The acquisition and analysis of aero-engine operating state parameters is the basis for realizing active clearance control. Non-contact online monitoring of aero-engine rotor-stator clearance is very important. meaning.

At present, the measurement object of the relatively mature non-contact rotor-stator clearance measurement method is mainly the blade tip clearance, and the bench test has been completed. However, there are few domestic and foreign research results on the axial clearance. The actual assembly usually uses the engine prototype. The calculated value is standard, there are installation clearance error and clearance error, and there is no mature online measurement system for rotor and stator axial clearance.

In the traditional aero-engine micro-gap measurement method, the optical method is easily affected by environmental oil pollution, and the measurement life is shortened, and the processing cost is very high when applied in a high temperature (450°C) test environment; the capacitance method has a measuring range of 10mm. The size of the sensor is too large, and it is not suitable for the measurement environment where the internal space of the aero-engine is very limited; the eddy current method is only suitable for the working environment of the engine at room temperature and low speed, and is not suitable for gap measurement at high temperature; compared with other methods, the microwave method is not easily affected by the internal work of the engine. It is more suitable for the measurement of small gaps in the engine due to environmental influences. However, under the condition of limited space, the sensor is easy to receive stray reflection signals from the stator parts around the rotor to be measured.

The microwave method can be divided into reflection intensity method, linear frequency modulation method and phase difference method. The reflection intensity method is easily affected by temperature, and the measurement accuracy cannot meet the measurement requirements; the linear frequency modulation method requires a high signal bandwidth to achieve high measurement accuracy, but The structure is too complex; the phase difference method uses quadrature demodulation and high and low pass filtering to realize the axial gap measurement of the rotor and stator, but there are radio frequency leakage signals, reflection signals from the sensor end face and stray reflection signals from the stator parts around the object to be measured. The signal affects the measurement accuracy of the axial clearance.

SUMMARY OF THE INVENTION

In order to overcome the deficiencies of the prior art, the present invention aims to provide a microwave-based online measurement method and device for the rotor-stator axial gap, so as to realize the non-contact real-time online accurate measurement of the rotor-stator axial gap of aero-engine under the condition of limited space. To this end, the technical solution adopted in the present invention is that a microwave-based rotor-stator axial gap online measurement device includes a microwave signal generation module, a signal power amplification module, a signal receiving and frequency mixing module, a signal conditioning and acquisition module, a circulator, a microwave Sensor, the carrier signal generated by the microwave signal generating module is amplified by the signal power amplifying module, then enters the first port of the circulator, and is output from the second port of the circulator; the second port of the circulator is connected to the microwave sensor, The microwave sensor transmits the carrier signal to the axial end face of the rotor under test, and simultaneously receives the reflected signal of the carrier wave from the axial end face of the rotor, returns it to the second port of the circulator, and outputs it from the third port of the circulator;

The reference signal generated by the microwave signal generation module is amplified by the signal power amplifying module as the local oscillator input signal Y ₂ of the signal receiving and frequency mixing module; at the same time, the carrier signal generated by the microwave signal generating module is amplified by the signal power amplifying module and received as a signal and the radio frequency input signal X ₁ of the frequency mixing module; the signal receiving and frequency mixing module outputs a demodulated signal, and the signal is preprocessed by the signal conditioning acquisition module and then output to the computer;

The carrier signal output by the third port of the circulator is used as the radio frequency input signal Y ₁ of the signal receiving and frequency mixing module; at the same time, the reference signal output by the microwave signal generating module is amplified by the signal power amplifying module as the signal receiving and frequency mixing module. The local oscillator input signal X ₂ ; the signal receiving and frequency mixing module outputs two channels of quadrature demodulation signals, and the two channels of signals are output to the computer after passing through the signal conditioning and acquisition module.

One demodulated signal output by the signal receiving and frequency mixing module forms a signal Z _I1 , and the signal receiving and frequency mixing module outputs two quadrature demodulated signals to form signals Z _I2 and Z _Q2 respectively. In the computer, the transmitted Z _I2 and Z _I1 performs mixing operation and low-pass filtering to obtain the signal V _I (d), and Z _Q2 and Z _I1 are subjected to mixing operation and low-pass filtering to obtain the signal V _Q (d), through the spatial distance scanning, namely The rotor-stator axial gap sampling is carried out at equal intervals, and the change value of the rotor-stator axial gap is finally calculated from V _I (d) and V _Q (d).

The microwave signal generation module mainly includes: clock reference, controller, carrier circuit phase locked loop, carrier circuit voltage controlled oscillator, carrier circuit loop filter, reference circuit phase locked loop, reference circuit voltage controlled oscillator, reference circuit loop filter;

The signal power amplifier module includes: carrier circuit power amplifier, carrier circuit medium power amplifier, reference circuit power amplifier, and reference circuit medium power amplifier;

The signal receiving and mixing module includes: reference channel mixer, reference channel RF low-noise amplifier, carrier channel mixer, carrier channel RF low-noise amplifier, first low-pass filter, second low-pass filter, the third low-pass filter;

The clock reference provides a stable frequency reference for the system;

The controller sets the carrier circuit phase-locked loop to work in the carrier frequency ω _r mode; the carrier circuit phase-locked loop outputs the pulse current signal through the internal charge pump, and after band-pass filtering by the carrier circuit loop filter, the carrier circuit voltage-controlled oscillation is made. At the same time, through the internal phase detector, the phase difference between the frequency multiplied signal of the clock reference and the carrier feedback signal of the carrier voltage controlled oscillator is _monitored in real time, and the phase difference between the two is zero. ;

The carrier signal output by the voltage-controlled oscillator of the carrier circuit is amplified by the power amplifier of the carrier circuit, and then enters the first port of the circulator, and is output from the second port of the circulator; the second port of the circulator is connected to the microwave sensor. Connected, the microwave sensor transmits the carrier signal to the axial end face of the rotor under test, and simultaneously receives the reflected signal of the carrier wave from the axial end face of the rotor, returns it to the second port of the circulator, and outputs it from the third port of the circulator;

The controller sets the reference circuit phase-locked loop to work in the reference frequency ω _s mode; the reference circuit phase-locked loop outputs the pulse current signal through the internal charge pump, and after band-pass filtering by the reference circuit loop filter, the reference circuit voltage-controlled oscillation is made. The device outputs a reference signal with a reference frequency of ω _s , and at the same time, through the internal phase detector, the phase difference between the frequency multiplied signal of the clock reference and the reference feedback signal of the reference circuit voltage-controlled oscillator is monitored in real time, and the phase difference between the two is zero. ;

The reference signal output by the reference circuit voltage-controlled oscillator is amplified by the reference circuit power amplifier and the reference circuit radio frequency low-noise amplifier as the local oscillator input signal Y ₂ of the reference circuit mixer; at the same time, the carrier circuit voltage-controlled oscillator The output carrier signal is amplified by the medium gain power of the medium power amplifier in the carrier circuit as the RF input signal X ₁ of the reference circuit mixer; Z _I1 , the signal is preprocessed by the signal conditioning acquisition module, and then sent to the computer;

The carrier signal output from the third port of the circulator is amplified by the carrier circuit radio frequency low noise amplifier as the radio frequency input signal Y ₁ of the carrier circuit mixer; at the same time, the reference signal output by the reference circuit voltage controlled oscillator passes through the reference circuit and so on. The medium gain of the power amplifier is amplified as the local oscillator input signal X ₂ of the carrier mixer; the carrier mixer outputs two quadrature demodulation signals, which pass through the second low-pass filter and the third low-pass filter respectively. After the filter, it is Z _I2 and Z _Q2 , and these two signals are also preprocessed by the signal conditioning acquisition module, and then sent to the computer;

The local oscillator input signal Y ₂ and the radio frequency input signal X ₁ input by the reference mixer are expressed by equation (1) and equation (2) respectively:

为射频输入信号X₁的相位，

为本振输入信号Y₂的相位；Among them, A ₁ is the amplitude of the radio frequency input signal X ₁ , A ₆ is the amplitude of the local oscillator input signal Y ₂ , ω _s is the reference frequency, ω _r is the carrier frequency,

is the phase of the RF input signal X ₁ ,

is the phase of the local oscillator input signal Y ₂ ;

Referring to the demodulated signal output by the mixer of the reference channel, after the first low-pass filter filters out the frequency components with the frequency ω _r + ω _s , the obtained signal Z _I1 is expressed by equation (3):

Among them, ω _IF =ω _s -ω _r is the intermediate frequency;

The RF input signal Y ₁ and the local oscillator input signal X ₂ input by the carrier mixer are expressed by formula (4) and formula (5) respectively:

为本振输入信号X₂的相位，

为射频输入信号Y₁中载波反射信号部分、传感器端面反射部分和待测转子周围静子件杂散反射部分在传输线缆上延迟的相位，

为射频输入信号Y₁中由于射频芯片或环形器隔离度不高造成的射频同频串扰部分在传输路径上延迟的相位，

为射频输入信号Y₁中载波反射信号部分受转静子轴向间隙变化产生的待测相位；Among them, A ₂ is the amplitude of the local oscillator input signal X ₂ , A ₃ is the amplitude of the reflected signal part of the carrier wave in the radio frequency input signal Y ₁ , A ₄ is the reflected part of the sensor end face in the radio frequency input signal Y ₁ and around the rotor to be measured The amplitude of the stray reflection part of the static component, A ₅ is the amplitude of the RF co-frequency crosstalk part in the RF input signal Y ₁ due to the low isolation of the RF chip or the circulator,

is the phase of the local oscillator input signal _X2 ,

is the phase delay on the transmission cable of the reflected signal part of the carrier wave, the reflected part of the sensor end face and the stray reflection part of the stator around the rotor to be measured in the RF input signal Y ₁ ,

is the phase delayed on the transmission path of the RF co-frequency crosstalk part in the RF input signal Y ₁ due to the low isolation of the RF chip or the circulator,

is the phase to be measured generated by the change of the axial gap of the rotor stator in the reflected signal part of the carrier wave in the RF input signal Y ₁ ;

The two quadrature demodulated signals output by the carrier mixer are respectively filtered by the second low-pass filter and the third low-pass filter to filter out the frequency components with frequency ω _r + ω _s , the obtained signal Z _I2 and Z _Q2 , respectively expressed by formula (6) and formula (7):

Z _I2 =S _{I_IF} (t)+S _{I_tip} (t)+S _{I_le} (t) (6)

Z _Q2 =S _{Q_IF} (t)+S _{Q_tip} (t)+S _{Q_le} (t) (7)

是Z_I2中的载波反射信号部分；in,

is the reflected signal part of the carrier in Z _I2 ;

是Z_I2中的传感器端面反射部分和待测转子周围静子件杂散反射部分；

It is the reflection part of the sensor end face in Z _I2 and the stray reflection part of the stator around the rotor to be tested;

是Z_I2中的由于射频芯片或环形器隔离度不高造成的射频同频串扰部分；

It is the RF co-frequency crosstalk part in Z _I2 due to the low isolation of the RF chip or circulator;

是Z_Q2中的载波反射信号部分；

is the reflected signal part of the carrier in Z _Q2 ;

是Z_Q2中的传感器端面反射部分和待测转子周围静子件杂散反射部分；

It is the reflection part of the sensor end face in Z _Q2 and the stray reflection part of the stator around the rotor to be tested;

是Z_Q2中的由于射频芯片或环形器隔离度不高造成的射频同频串扰部分；

It is the RF co-frequency crosstalk part in Z _Q2 due to the low isolation of the RF chip or circulator;

为相位不平衡因子；k is the amplitude imbalance factor,

is the phase imbalance factor;

In the computer, the transmitted Z _I2 and Z _I1 are subjected to mixing operation and low-pass filtering to obtain the signal V _I (d), and Z _Q2 and Z _I1 are subjected to mixing operation and low-pass filtering to obtain the signal V _Q (d), V _I (d) and V _Q (d) are represented by equations (8) and (9), respectively:

当工作环境的温度稳定不变、传感器安装环境振动状态稳定不变时，

A_tip、A_le均为定值，不随转静子轴向间隙改变而变化，而A_IF仅与转静子轴向间隙有关，与转静子轴向间隙d的二次幂成反比关系；in,

When the temperature of the working environment is stable and the vibration state of the sensor installation environment is stable and unchanged,

A _tip and A _le are both fixed values and do not change with the change of the rotor-stator axial gap, while A _IF is only related to the rotor-stator axial gap, and inversely proportional to the second power of the rotor-stator axial gap d;

By the principle of microwave phase ranging:

where ω ₁ is the spatial angular frequency of the transmitted microwave radio frequency signal;

It is obtained by formulas (8), (9) and (10):

j为虚数单位。in,

j is an imaginary unit.

Taking advantage of the fact that the V(d) signal spectrum mainly consists of three parts: the main frequency ω ₁ , the mirror frequency -ω ₁ and the DC frequency, the three parts are obtained by scanning the space distance, that is, sampling the axial gap of the rotor and stator at equal intervals. The amplitudes at the frequencies are A(ω ₁ ), A(-ω ₁ ), and A(0) respectively; the amplitude-phase unbalance correction factor uses equations (12), (13), (14) and (15) means:

A model for suppressing co-channel interference signals is established as shown in equation (17):

Therefore, the axial gap d of the rotor and stator after suppressing the same-frequency interference signal is expressed by equation (18):

不随待测转静子轴向间隙变化，通过标定获得这一常数值。in,

This constant value is obtained by calibration without changing with the axial clearance of the rotor and stator to be measured.

The microwave-based on-line measurement method of rotor-stator axial gap is realized by using the aforementioned device, wherein:

The local oscillator input signal Y ₂ and the radio frequency input signal X ₁ input by the reference mixer are expressed by equation (1) and equation (2) respectively:

为射频输入信号X₁的相位，

为本振输入信号Y₂的相位；Among them, A ₁ is the amplitude of the radio frequency input signal X ₁ , A ₆ is the amplitude of the local oscillator input signal Y ₂ , ω _s is the reference frequency, ω _r is the carrier frequency,

is the phase of the RF input signal X ₁ ,

is the phase of the local oscillator input signal Y ₂ ;

Referring to the demodulated signal output by the mixer of the reference channel, after the first low-pass filter filters out the frequency components with the frequency ω _r + ω _s , the obtained signal Z _I1 is expressed by equation (3):

Among them, ω _IF =ω _s -ω _r is the intermediate frequency;

The RF input signal Y ₁ and the local oscillator input signal X ₂ input by the carrier mixer are expressed by formula (4) and formula (5) respectively:

为本振输入信号X₂的相位，

为射频输入信号Y₁中载波反射信号部分、传感器端面反射部分和待测转子周围静子件杂散反射部分在传输线缆上延迟的相位，

为射频输入信号Y₁中由于射频芯片或环形器隔离度不高造成的射频同频串扰部分在传输路径上延迟的相位，

为射频输入信号Y₁中载波反射信号部分受转静子轴向间隙变化产生的待测相位；Among them, A ₂ is the amplitude of the local oscillator input signal X ₂ , A ₃ is the amplitude of the reflected signal part of the carrier wave in the radio frequency input signal Y ₁ , A ₄ is the reflected part of the sensor end face in the radio frequency input signal Y ₁ and around the rotor to be measured The amplitude of the stray reflection part of the static component, A ₅ is the amplitude of the RF co-frequency crosstalk part in the RF input signal Y ₁ due to the low isolation of the RF chip or the circulator,

is the phase of the local oscillator input signal _X2 ,

is the phase delay on the transmission cable of the reflected signal part of the carrier wave, the reflected part of the sensor end face and the stray reflection part of the stator around the rotor to be measured in the RF input signal Y ₁ ,

is the phase delayed on the transmission path of the RF co-frequency crosstalk part in the RF input signal Y ₁ due to the low isolation of the RF chip or the circulator,

is the phase to be measured generated by the change of the axial gap of the rotor stator in the reflected signal part of the carrier wave in the RF input signal Y ₁ ;

The two quadrature demodulated signals output by the carrier mixer are respectively filtered by the second low-pass filter and the third low-pass filter to filter out the frequency components with frequency ω _r + ω _s , the obtained signal Z _I2 and Z _Q2 , respectively expressed by formula (6) and formula (7):

Z _I2 =S _{I_IF} (t)+S _{I_tip} (t)+S _{I_le} (t) (6)

Z _Q2 =S _{Q_IF} (t)+S _{Q_tip} (t)+S _{Q_le} (t) (7)

是Z_I2中的载波反射信号部分；in,

is the reflected signal part of the carrier in Z _I2 ;

是Z_I2中的传感器端面反射部分和待测转子周围静子件杂散反射部分；

It is the reflection part of the sensor end face in Z _I2 and the stray reflection part of the stator around the rotor to be tested;

是Z_I2中的由于射频芯片或环形器隔离度不高造成的射频同频串扰部分；

It is the RF co-frequency crosstalk part in Z _I2 due to the low isolation of the RF chip or circulator;

是Z_Q2中的载波反射信号部分；

is the reflected signal part of the carrier in Z _Q2 ;

是Z_Q2中的传感器端面反射部分和待测转子周围静子件杂散反射部分；

It is the reflection part of the sensor end face in Z _Q2 and the stray reflection part of the stator around the rotor to be tested;

是Z_Q2中的由于射频芯片或环形器隔离度不高造成的射频同频串扰部分；

It is the RF co-frequency crosstalk part in Z _Q2 due to the low isolation of the RF chip or circulator;

为相位不平衡因子；k is the amplitude imbalance factor,

is the phase imbalance factor;

In the computer, the transmitted Z _I2 and Z _I1 are subjected to mixing operation and low-pass filtering to obtain the signal V _I (d), and Z _Q2 and Z _I1 are subjected to mixing operation and low-pass filtering to obtain the signal V _Q (d), V _I (d) and V _Q (d) are represented by equations (8) and (9), respectively:

当工作环境的温度稳定不变、传感器安装环境振动状态稳定不变时，

A_tip、A_le均为定值，不随转静子轴向间隙改变而变化，而A_IF仅与转静子轴向间隙有关，与转静子轴向间隙d的二次幂成反比关系；in,

When the temperature of the working environment is stable and the vibration state of the sensor installation environment is stable and unchanged,

A _tip and A _le are both fixed values and do not change with the change of the rotor-stator axial gap, while A _IF is only related to the rotor-stator axial gap, and inversely proportional to the second power of the rotor-stator axial gap d;

By the principle of microwave phase ranging:

where ω ₁ is the spatial angular frequency of the transmitted microwave radio frequency signal;

It is obtained by formulas (8), (9) and (10):

j为虚数单位。in,

j is an imaginary unit.

Taking advantage of the fact that the V(d) signal spectrum mainly consists of three parts: the main frequency ω ₁ , the mirror frequency -ω ₁ and the DC frequency, the three parts are obtained by scanning the space distance, that is, sampling the axial gap of the rotor and stator at equal intervals. The amplitudes at the frequencies are A(ω ₁ ), A(-ω ₁ ), and A(0) respectively; the amplitude-phase unbalance correction factor uses equations (12), (13), (14) and (15) means:

A model for suppressing co-channel interference signals is established as shown in equation (17):

Therefore, the axial gap d of the rotor and stator after suppressing the same-frequency interference signal is expressed by equation (18):

不随待测转静子轴向间隙变化，通过标定获得这一常数值。in,

This constant value is obtained by calibration without changing with the axial clearance of the rotor and stator to be measured.

The characteristics and beneficial effects of the present invention are:

It breaks the current situation that there is no mature rotor-stator axial gap measurement solution at home and abroad, and solves the existence of radio frequency leakage signals and sensor end-face reflection signals when measuring the rotor-stator axial gap in the existing microwave micro-gap measurement method based on the phase difference method. And the problem that the stray reflection signal of the static component around the object to be measured and the same frequency interference signal affect the measurement accuracy of the axial gap. A microwave-based on-line measurement method and device for rotor-stator axial gap is designed. Using the cross-mixing structure of carrier path and reference path based on the principle of phase ranging, a co-frequency interference signal suppression method based on spatial distance scanning is proposed. In the presence of radio frequency leakage signals from the transmitter end to the receiver end, reflection signals from the end face of the microwave sensor, and stray reflection signals from the stator parts around the rotor to be measured, the measurement accuracy of the rotor-stator axial gap is improved.

Description of drawings:

FIG. 1 shows a schematic diagram of the microwave-based on-line measurement method and device of the rotor-stator axial gap of the present invention.

In Figure 1: 1 is the clock reference, 2 is the controller, 3 is the phase-locked loop of the carrier circuit, 4 is the voltage-controlled oscillator of the carrier circuit, 5 is the loop filter of the carrier circuit, 6 is the phase-locked loop of the reference circuit, and 7 is the phase-locked loop of the reference circuit. Reference circuit voltage controlled oscillator, 8 is the reference circuit loop filter, 9 is the carrier circuit power amplifier, 10 is the carrier circuit medium power amplifier, 11 is the reference circuit power amplifier, 12 is the reference circuit medium power amplifier, and 13 is the reference circuit. mixer, 14 is the reference channel RF low noise amplifier, 15 is the carrier channel mixer, 16 is the carrier channel RF low noise amplifier, 17 is the first low-pass filter, 18 is the second low-pass filter, 19 is the third low-pass filter, 20 is the microwave signal generation module, 21 is the signal power amplifying module, 22 is the signal receiving and mixing module, 23 is the signal conditioning and acquisition module, 24 is the computer, 25 is the circulator, 26 For the microwave sensor, 27 is the axial end face of the rotor.

Detailed ways

In order to overcome the aforementioned deficiencies of the prior art, the present invention designs a microwave-based on-line measurement method and device for the axial gap of the rotor and stator, and the main technical problems to be solved are:

It breaks the current situation that there is no mature rotor-stator axial gap measurement solution at home and abroad, and solves the existence of radio frequency leakage signals and sensor end-face reflection signals when measuring the rotor-stator axial gap in the existing microwave micro-gap measurement method based on the phase difference method. And the problem that the stray reflection signal of the static component around the object to be measured and the same frequency interference signal affect the measurement accuracy of the axial gap. A microwave-based on-line measurement method and device for rotor-stator axial gap is designed. Using the cross-mixing structure of carrier path and reference path based on the principle of phase ranging, a co-frequency interference signal suppression method based on spatial distance scanning is proposed. In the presence of radio frequency leakage signals from the transmitter end to the receiver end, reflection signals from the end face of the microwave sensor, and stray reflection signals from the stator parts around the rotor to be measured, the measurement accuracy of the rotor-stator axial gap is improved.

In order to achieve the above goal, the technical solution adopted in the present invention is to design a microwave-based on-line measurement method and device for the axial gap of the rotor and stator, as shown in FIG. , signal receiving and mixing module 22, signal conditioning and acquisition module 23, computer 24, circulator 25, microwave sensor 26;

Among them, the microwave signal generation module 20 mainly includes: a clock reference 1, a controller 2, a carrier circuit phase-locked loop 3, a carrier circuit voltage-controlled oscillator 4, a carrier circuit loop filter 5, a reference circuit phase-locked loop 6, a reference circuit Voltage controlled oscillator 7, reference circuit loop filter 8;

The signal power amplifying module 21 mainly includes: a carrier circuit power amplifier 9, a carrier circuit middle power amplifier 10, a reference circuit power amplifier 11, and a reference circuit middle power amplifier 12;

The signal receiving and mixing module 22 mainly includes: the reference channel mixer 13, the reference channel RF low noise amplifier 14, the carrier channel mixer 15, the carrier channel RF low noise amplifier 16, the first low-pass filter 17, the first Two low-pass filters 18 and a third low-pass filter 19;

Further, the microwave-based rotor-stator axial gap online measurement device is a coherent measurement system, and the clock reference 1 provides a stable frequency reference for the system;

Further, the controller 2 sets the carrier phase-locked loop 3 to work under the carrier frequency ω _r mode; the carrier phase-locked loop 3 outputs the pulse current signal through the internal charge pump, and after band-pass filtering by the carrier circuit loop filter 5, Make the carrier circuit VCO 4 output a carrier signal with a carrier frequency of ω _r , and at the same time monitor the phase difference between the frequency multiplication signal of the clock reference 1 and the carrier feedback signal of the carrier circuit voltage controlled oscillator 4 through the internal phase detector , and make the phase difference between the two zero;

Further, the carrier signal output by the carrier circuit voltage-controlled oscillator 4 enters the first port of the circulator 25 after being amplified by the power amplifier 9 of the carrier circuit, and flows from the second port of the circulator 25 with a small insertion loss. Output; the second port of the circulator 25 is connected to the microwave sensor 26, and the microwave sensor 26 transmits a carrier signal to the axial end face 27 of the rotor under test, and simultaneously receives the reflected signal of the carrier wave from the axial end face 27 of the rotor, and outputs it back to the circulator 25 The second port of , and output from the third port of the circulator 25 with a smaller insertion loss;

Further, the controller 2 sets the reference circuit phase-locked loop 6 to work under the reference frequency ω _s mode; the reference circuit phase-locked loop 6 outputs the pulse current signal through the internal charge pump, and after band-pass filtering by the reference circuit loop filter 8, Make the reference circuit voltage controlled oscillator 7 output a reference signal with a reference frequency of ω _s , and at the same time monitor the phase difference between the frequency multiplied signal of the clock reference 1 and the reference feedback signal of the reference circuit voltage controlled oscillator 7 through the internal phase detector , and make the phase difference between the two zero;

Further, the reference signal output by the reference circuit VCO 7 is used as the local oscillator input signal Y ₂ of the reference circuit mixer 13 after the power amplification of the reference circuit power amplifier 11 and the amplification of the reference circuit radio frequency low noise amplifier 14; at the same time, The carrier signal output by the carrier circuit voltage-controlled oscillator 4 is amplified by the medium gain power of the carrier circuit medium power amplifier 6 as the radio frequency input signal X ₁ of the reference circuit mixer 13; the reference circuit mixer 13 outputs a demodulated signal, After the first low-pass filter 17 is Z _I1 , the signal is preprocessed by the signal conditioning acquisition module 23, and then sent to the computer 24;

Further, the carrier signal output by the third port of the circulator 25 is amplified by the carrier path radio frequency low noise amplifier 16 as the radio frequency input signal Y ₁ of the carrier path mixer 15; After the reference signal is amplified by the medium gain of the medium power amplifier 12 of the reference circuit, it is used as the local oscillator input signal X ₂ of the carrier circuit mixer 15; After the pass filter 18 and the third low-pass filter 19, they are Z _I2 and Z _Q2 , and these two signals are also preprocessed by the signal conditioning acquisition module 23, and then sent to the computer 24;

Further, the signal receiving and frequency mixing module 22 of the present invention adopts a carrier path and a reference path cross-mixing structure, that is, among the two signals uploaded to the computer, one signal uses the carrier path carrier signal as the radio frequency input signal and the reference path reference. The signal is used as the local oscillator input signal, and is obtained by mixing in the reference channel mixer 13, and the other channel signal is obtained by using the carrier channel carrier signal as the RF input signal and the reference channel reference signal as the local oscillator input signal, which is mixed in the carrier channel mixer 15. The two-way signals output by the carrier circuit voltage-controlled oscillator 4 and the two-way signals output by the reference circuit voltage-controlled oscillator 7 are mixed in the reference circuit and the carrier circuit respectively. This structure is called the carrier circuit and the reference circuit. Crossover mixing structure;

The cross-mixing structure of the carrier circuit and the reference circuit adopted in the present invention can suppress the frequency stability of the output signal of the carrier circuit voltage-controlled oscillator 4 or the reference circuit voltage-controlled oscillator 7 is not high, or the frequency drifts with temperature to measure the axial gap of the rotating stator. The effect of precision;

Further, the local oscillator input signal Y ₂ and the radio frequency input signal X ₁ input by the reference channel mixer 13 can be expressed by Equation 1 and Equation 2 respectively:

为射频输入信号X₁的相位，

为本振输入信号Y₂的相位；Among them, A ₁ is the amplitude of the radio frequency input signal X ₁ , A ₆ is the amplitude of the local oscillator input signal Y ₂ , ω _s is the reference frequency, ω _r is the carrier frequency,

is the phase of the RF input signal X ₁ ,

is the phase of the local oscillator input signal Y ₂ ;

With reference to the demodulated signal output by the mixer 13, after the first low-pass filter 17 filters out the frequency components with the frequency ω _r +ω _s , the obtained signal Z _I1 can be expressed by Equation 3:

Among them, ω _IF =ω _s -ω _r is the intermediate frequency;

Further, the radio frequency input signal Y ₁ and the local oscillator input signal X ₂ input by the carrier path mixer 15 can be expressed by Equation 4 and Equation 5 respectively:

为本振输入信号X₂的相位，

为射频输入信号Y₁中载波反射信号部分、传感器端面反射部分和待测转子周围静子件杂散反射部分在传输线缆上延迟的相位，

为射频输入信号Y₁中由于射频芯片或环形器隔离度不高造成的射频同频串扰部分在传输路径上延迟的相位，

为射频输入信号Y₁中载波反射信号部分受转静子轴向间隙变化产生的待测相位；Among them, A ₂ is the amplitude of the local oscillator input signal X ₂ , A ₃ is the amplitude of the reflected signal part of the carrier wave in the radio frequency input signal Y ₁ , A ₄ is the reflected part of the sensor end face in the radio frequency input signal Y ₁ and around the rotor to be measured The amplitude of the stray reflection part of the static component, A ₅ is the amplitude of the RF co-frequency crosstalk part in the RF input signal Y ₁ due to the low isolation of the RF chip or the circulator,

is the phase of the local oscillator input signal _X2 ,

is the phase delay on the transmission cable of the reflected signal part of the carrier wave, the reflected part of the sensor end face and the stray reflection part of the stator around the rotor to be measured in the RF input signal Y ₁ ,

is the phase delayed on the transmission path of the RF co-frequency crosstalk part in the RF input signal Y ₁ due to the low isolation of the RF chip or the circulator,

is the phase to be measured generated by the change of the axial gap of the rotor stator in the reflected signal part of the carrier wave in the RF input signal Y ₁ ;

After the two channels of quadrature demodulation signals output by the carrier channel mixer 15 pass through the second low-pass filter 18 and the third low-pass filter 19 to filter out the frequency components whose frequency is ω _r +ω _s , the obtained The signals Z _I2 and Z _Q2 can be represented by equations 6 and 7, respectively:

Z _I2 =S _{I_IF} (t)+S _{I_tip} (t)+S _{I_le} (t) (6)

Z _Q2 =S _{Q_IF} (t)+S _{Q_tip} (t)+S _{Q_le} (t) (7)

是Z_I2中的载波反射信号部分；in,

is the reflected signal part of the carrier in Z _I2 ;

是Z_I2中的传感器端面反射部分和待测转子周围静子件杂散反射部分；

It is the reflection part of the sensor end face in Z _I2 and the stray reflection part of the stator around the rotor to be tested;

是Z_I2中的由于射频芯片或环形器隔离度不高造成的射频同频串扰部分；

It is the RF co-frequency crosstalk part in Z _I2 due to the low isolation of the RF chip or circulator;

是Z_Q2中的载波反射信号部分；

is the reflected signal part of the carrier in Z _Q2 ;

是Z_Q2中的传感器端面反射部分和待测转子周围静子件杂散反射部分；

It is the reflection part of the sensor end face in Z _Q2 and the stray reflection part of the stator around the rotor to be tested;

是Z_Q2中的由于射频芯片或环形器隔离度不高造成的射频同频串扰部分；

It is the RF co-frequency crosstalk part in Z _Q2 due to the low isolation of the RF chip or circulator;

为相位不平衡因子；k is the amplitude imbalance factor,

is the phase imbalance factor;

Further, in computer 24, Z _I2 and Z _I1 that are transmitted are carried out mixing operation and low-pass filtering processing, obtain signal V _I (d), Z _Q2 and Z _I1 are carried out mixing operation and low-pass filtering processing, The obtained signal V _Q (d), V _I (d) and V _Q (d) can be expressed by equations 8 and 9, respectively:

当工作环境的温度稳定不变、传感器安装环境振动状态稳定不变时，

A_tip、A_le均为定值，不随转静子轴向间隙改变而变化，而A_IF仅与转静子轴向间隙有关，与转静子轴向间隙d的二次幂成反比关系；in,

When the temperature of the working environment is stable and the vibration state of the sensor installation environment is stable and unchanged,

A _tip and A _le are both fixed values and do not change with the change of the rotor-stator axial gap, while A _IF is only related to the rotor-stator axial gap, and inversely proportional to the second power of the rotor-stator axial gap d;

Further, based on the principle of microwave phase ranging, we set

where ω ₁ is the spatial angular frequency of the transmitted microwave radio frequency signal;

From equations 8, 9, and 10, we can get:

j为虚数单位。in,

j is an imaginary unit.

Further, the present invention utilizes the characteristic that the V(d) signal spectrum mainly consists of three parts: the main frequency ω ₁ , the mirror frequency -ω ₁ and the DC frequency, through the spatial distance scanning, that is, the rotor-stator axial gap sampling is performed at equal intervals, Obtain the amplitudes at these three frequencies, respectively A(ω ₁ ), A(-ω ₁ ), and A(0); the amplitude-phase imbalance correction factor can be expressed by Equation 12, Equation 13, Equation 14 and Equation 15 :

Further, the present invention proposes a method for suppressing co-channel interference signals based on spatial distance scanning, which can effectively suppress the radio frequency leakage signal from the crosstalk from the transmitting end to the receiving end, the reflected signal from the end face of the microwave sensor, and the signal to be measured by using the amplitude-phase unbalance correction factor. The stray reflection signal of the stator around the rotor is the same frequency interference signal;

The model for suppressing co-channel interference signals is shown in Equation 17:

Therefore, the axial gap d of the rotor and stator after suppressing the same-frequency interference signal can be expressed by Equation 18:

不随待测转静子轴向间隙变化，可通过标定获得这一常数值。in,

This constant value can be obtained by calibration without changing with the axial clearance of the rotor and stator to be measured.

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific examples.

The invention designs a microwave-based on-line measurement method and device for the axial gap of the rotor and stator, adopts the cross-mixing structure of the carrier path and the reference path and the same-frequency interference signal suppression method based on the space distance scanning, so as to realize the aero-engine under the condition of limited space. Non-contact real-time online accurate measurement of rotor and stator axial clearance.

The present invention is realized in this way:

The present invention designs a microwave-based on-line measurement method and device for rotor-stator axial gap, as shown in FIG. 1 , which mainly includes: a microwave signal generating module 20 , a signal power amplifying module 21 , a signal receiving and frequency mixing module 22 , and a signal conditioning module acquisition module 23, computer 24, circulator 25, microwave sensor 26;

Among them, the microwave signal generation module 20 mainly includes: a clock reference 1, a controller 2, a carrier circuit phase-locked loop 3, a carrier circuit voltage-controlled oscillator 4, a carrier circuit loop filter 5, a reference circuit phase-locked loop 6, a reference circuit Voltage-controlled oscillator 7, reference circuit loop filter 8;

The signal power amplifying module 21 mainly includes: a carrier circuit power amplifier 9, a carrier circuit middle power amplifier 10, a reference circuit power amplifier 11, and a reference circuit middle power amplifier 12;

The signal receiving and mixing module 22 mainly includes: the reference channel mixer 13, the reference channel RF low noise amplifier 14, the carrier channel mixer 15, the carrier channel RF low noise amplifier 16, the first low-pass filter 17, the first Two low-pass filters 18 and a third low-pass filter 19;

The invention will be further described below in conjunction with the accompanying drawings and embodiments.

Further, in the present invention, the microwave-based rotor-stator axial gap online measurement device is a coherent measurement system, the clock reference 1 provides a stable frequency reference for the system, and an analog temperature-compensated crystal oscillator and a digital temperature-compensated crystal oscillator with high frequency stability can be selected. Wait;

Further, in the present invention, the controller 2 sets the carrier circuit phase-locked loop 3 to work under the carrier frequency; the carrier circuit phase-locked loop 3 outputs the pulse current signal through the internal charge pump, and after the carrier circuit loop filter 5 band-pass filtering , make the carrier circuit voltage controlled oscillator 4 output the carrier signal, and at the same time through the internal phase detector, monitor the phase difference between the frequency multiplication signal of the clock reference 1 and the carrier feedback signal of the carrier circuit voltage controlled oscillator 4 in real time, and make the two The phase difference is zero;

Further, in the present invention, the controller 2 can select a single-chip microcomputer, an advanced reduced instruction set machine (ARM), etc.;

Further, in the present invention, the carrier circuit phase-locked loop 3 can select an analog phase-locked loop, a digital phase-locked loop, etc.;

Further, in the present invention, the carrier circuit loop filter 5 can select passive filter, active filter, etc.;

Further, in the present invention, the carrier signal output by the carrier circuit voltage-controlled oscillator 4 enters the first port of the circulator 25 after being amplified by the carrier circuit power amplifier 9, and is transmitted from the circulator 25 with a small insertion loss. The second port is output; the second port of the circulator 25 is connected to the microwave sensor 26, and the microwave sensor 26 transmits a carrier signal to the axial end face 27 of the rotor under test, and receives the reflected signal of the carrier wave from the axial end face 27 of the rotor, and sends it back. to the second port of the circulator 25 and output from the third port of the circulator 25 with a small insertion loss;

Further, in the present invention, the circulator 25 can be selected from a surface-mounted circulator, a line circulator, a coaxial circulator, and the like;

Further, in the present invention, the microwave sensor 26 can be selected from a microwave resonant cavity structure, a microstrip antenna structure, a planar inverted-F antenna structure, and the like;

Further, in the present invention, the controller 2 sets the reference circuit phase-locked loop 6 to work under the reference frequency; the reference circuit phase-locked loop 6 outputs the pulse current signal through the internal charge pump, and after band-pass filtering by the reference circuit loop filter 8 , so that the reference circuit voltage-controlled oscillator 7 outputs the reference signal, and at the same time, through the internal phase detector, the phase difference between the frequency multiplication signal of the clock reference 1 and the reference feedback signal of the reference circuit voltage-controlled oscillator 7 is monitored in real time, and the two are The phase difference is zero;

Further, in the present invention, the reference phase-locked loop 6 can be selected from an analog phase-locked loop, a digital phase-locked loop, etc.;

Further, in the present invention, a passive filter, an active filter, etc. can be selected for the reference circuit loop filter 8;

Further, in the present invention, the reference signal output by the reference circuit voltage-controlled oscillator 7 is used as the local oscillator input signal of the reference circuit mixer 13 after the power amplification of the reference circuit power amplifier 11 and the amplification of the reference circuit radio frequency low noise amplifier 14; At the same time, the carrier signal output by the carrier circuit voltage-controlled oscillator 4 is amplified by the medium gain power of the carrier circuit medium power amplifier 10 as the radio frequency input signal of the reference circuit mixer 13; the reference circuit mixer 13 outputs a demodulated signal, After the first low-pass filter 17 is Z _I1 , the signal is preprocessed by the signal conditioning acquisition module 23, and then sent to the computer 24;

Further, in the present invention, the carrier signal output by the third port of the circulator 25 is amplified by the carrier circuit radio frequency low noise amplifier 16 as the radio frequency input signal of the carrier circuit mixer 15; at the same time, the reference circuit voltage controlled oscillator 7 The output reference signal is amplified by the medium gain of the medium power amplifier 12 of the reference channel and then used as the local oscillator input signal of the carrier channel mixer 15; the carrier channel mixer 15 outputs two channels of quadrature demodulation signals, which pass through the second low After the pass filter 18 and the third low-pass filter 19, they are Z _I2 and Z _Q2 , and these two signals are also preprocessed by the signal conditioning acquisition module 23, and then sent to the computer 24;

Further, in the present invention, the signal conditioning and acquisition module 23 may be composed of a signal amplifying circuit, a signal filtering circuit and an analog-digital conversion circuit;

Further, in the present invention, the computer 24 can be an industrial control computer, a general personal computer, etc.;

Further, in the present invention, in the computer 24, the Z _I2 and Z _I1 that are transmitted are carried out mixing operation and low-pass filtering processing to obtain the signal VI (d), Z _Q2 and Z _{I1 are} carried out mixing operation and low-pass filtering. Through filtering, the signal V _Q (d) is obtained;

Further, in the present invention, a method for suppressing co-frequency interference signals based on spatial distance scanning is proposed, which can effectively suppress the radio frequency leakage signal from the crosstalk from the transmitting end to the receiving end, the reflected signal from the end face of the microwave sensor, and The stray reflection signal of the stator around the rotor to be tested is the same frequency interference signal; the model for suppressing the same frequency interference signal is shown in Equation 17 above;

Further, in the present invention, the axial gap d of the rotor and stator after suppressing the same-frequency interference signal can be represented by the foregoing formula 18.

Claims (4)

1. a microwave-based rotor-stator axial gap online measuring device, is characterized in that, comprises microwave signal generation module, signal power amplification module, signal reception and frequency mixing module, signal conditioning acquisition module, circulator, microwave sensor, microwave The carrier signal generated by the signal generating module is amplified by the signal power amplifying module, enters the first port of the circulator, and is output from the second port of the circulator; the second port of the circulator is connected to the microwave sensor, and the microwave sensor emits The carrier signal is sent to the axial end face of the rotor under test, and at the same time, the reflected signal of the carrier wave from the axial end face of the rotor is received, returned to the second port of the circulator, and output from the third port of the circulator; The reference signal generated by the microwave signal generation module is amplified by the signal power amplifying module as the local oscillator input signal Y ₂ of the signal receiving and frequency mixing module; at the same time, the carrier signal generated by the microwave signal generating module is amplified by the signal power amplifying module and received as a signal and the radio frequency input signal X ₁ of the frequency mixing module; the signal receiving and frequency mixing module outputs a demodulated signal, and the signal is preprocessed by the signal conditioning acquisition module and then output to the computer; The carrier signal output by the third port of the circulator is used as the radio frequency input signal Y ₁ of the signal receiving and frequency mixing module; at the same time, the reference signal output by the microwave signal generating module is amplified by the signal power amplifying module as the signal receiving and frequency mixing module. The local oscillator input signal X ₂ ; the signal receiving and frequency mixing module outputs two channels of quadrature demodulation signals, and the two channels of signals are output to the computer after passing through the signal conditioning and acquisition module. 2. The microwave-based on-line measuring device for rotor-stator axial gap as claimed in claim 1, wherein the signal receiving and the one-way demodulation signal output by the frequency mixing module form a signal Z _I1 , and the signal receiving and the frequency mixing module output two signals. The quadrature demodulated signals form signals Z _I2 and Z _Q2 respectively. In the computer, the transmitted Z _I2 and Z _I1 are subjected to mixing operation and low-pass filtering to obtain the signal V _I (d), Z _Q2 and Z _I1 performs frequency mixing operation and low-pass filtering to obtain the signal V _Q (d), which is scanned by the spatial distance, that is, the rotor stator axial gap is sampled at equal intervals, and is finally calculated by V _I (d) and V _Q (d) Obtain the change value of the axial clearance of the rotor and stator. 3. microwave-based rotor-stator axial gap online measuring device as claimed in claim 1, is characterized in that, microwave signal generation module mainly comprises: clock reference, controller, carrier circuit phase-locked loop, carrier circuit voltage-controlled oscillator , carrier circuit loop filter, reference circuit phase-locked loop, reference circuit voltage controlled oscillator, reference circuit loop filter; The signal power amplifier module includes: carrier circuit power amplifier, carrier circuit medium power amplifier, reference circuit power amplifier, and reference circuit medium power amplifier; The signal receiving and mixing module includes: reference channel mixer, reference channel RF low-noise amplifier, carrier channel mixer, carrier channel RF low-noise amplifier, first low-pass filter, second low-pass filter, the third low-pass filter; The clock reference provides a stable frequency reference for the system; The controller sets the carrier circuit phase-locked loop to work in the carrier frequency ω _r mode; the carrier circuit phase-locked loop outputs the pulse current signal through the internal charge pump, and after band-pass filtering by the carrier circuit loop filter, the carrier circuit voltage-controlled oscillation is made. At the same time, through the internal phase detector, the phase difference between the frequency multiplied signal of the clock reference and the carrier feedback signal of the carrier voltage controlled oscillator is _monitored in real time, and the phase difference between the two is zero. ; The carrier signal output by the voltage-controlled oscillator of the carrier circuit is amplified by the power amplifier of the carrier circuit, and then enters the first port of the circulator, and is output from the second port of the circulator; the second port of the circulator is connected to the microwave sensor. Connected, the microwave sensor transmits the carrier signal to the axial end face of the rotor under test, and simultaneously receives the reflected signal of the carrier wave from the axial end face of the rotor, returns it to the second port of the circulator, and outputs it from the third port of the circulator; The controller sets the reference circuit phase-locked loop to work in the reference frequency ω _s mode; the reference circuit phase-locked loop outputs the pulse current signal through the internal charge pump, and after band-pass filtering by the reference circuit loop filter, the reference circuit voltage-controlled oscillation is made. The device outputs a reference signal with a reference frequency of ω _s , and at the same time, through the internal phase detector, the phase difference between the frequency multiplied signal of the clock reference and the reference feedback signal of the reference circuit voltage-controlled oscillator is monitored in real time, and the phase difference between the two is zero. ; The reference signal output by the reference circuit voltage-controlled oscillator is amplified by the reference circuit power amplifier and the reference circuit radio frequency low-noise amplifier as the local oscillator input signal Y ₂ of the reference circuit mixer; at the same time, the carrier circuit voltage-controlled oscillator The output carrier signal is amplified by the medium gain power of the medium power amplifier in the carrier circuit as the RF input signal X ₁ of the reference circuit mixer; Z _I1 , the signal is preprocessed by the signal conditioning acquisition module, and then sent to the computer; The carrier signal output from the third port of the circulator is amplified by the carrier circuit radio frequency low noise amplifier as the radio frequency input signal Y ₁ of the carrier circuit mixer; at the same time, the reference signal output by the reference circuit voltage controlled oscillator passes through the reference circuit and so on. The medium gain of the power amplifier is amplified as the local oscillator input signal X ₂ of the carrier mixer; the carrier mixer outputs two quadrature demodulation signals, which pass through the second low-pass filter and the third low-pass filter respectively. After the filter, it is Z _I2 and Z _Q2 , and these two signals are also preprocessed by the signal conditioning acquisition module, and then sent to the computer; The local oscillator input signal Y ₂ and the radio frequency input signal X ₁ input by the reference mixer are expressed by equation (1) and equation (2) respectively:

Among them, A ₁ is the amplitude of the radio frequency input signal X ₁ , A ₆ is the amplitude of the local oscillator input signal Y ₂ , ω _s is the reference frequency, ω _r is the carrier frequency,

is the phase of the RF input signal X ₁ ,

is the phase of the local oscillator input signal Y ₂ ; Referring to the demodulated signal output by the mixer of the reference channel, after the first low-pass filter filters out the frequency components with the frequency ω _r + ω _s , the obtained signal Z _I1 is expressed by equation (3):

Among them, ω _IF =ω _s -ω _r is the intermediate frequency; The RF input signal Y ₁ and the local oscillator input signal X ₂ input by the carrier mixer are expressed by formula (4) and formula (5) respectively:

Among them, A ₂ is the amplitude of the local oscillator input signal X ₂ , A ₃ is the amplitude of the reflected signal part of the carrier wave in the radio frequency input signal Y ₁ , A ₄ is the reflected part of the sensor end face in the radio frequency input signal Y ₁ and around the rotor to be measured The amplitude of the stray reflection part of the static component, A ₅ is the amplitude of the RF co-frequency crosstalk part in the RF input signal Y ₁ due to the low isolation of the RF chip or the circulator,

is the phase of the local oscillator input signal _X2 ,

is the phase delayed on the transmission cable of the reflected signal part of the carrier wave, the reflected part of the sensor end face and the stray reflection part of the stator around the rotor to be measured in the RF input signal Y ₁ ,

is the phase delayed on the transmission path of the RF co-frequency crosstalk part in the RF input signal Y ₁ due to the low isolation of the RF chip or the circulator,

is the phase to be measured generated by the change of the axial gap of the rotor stator in the reflected signal part of the carrier wave in the RF input signal Y ₁ ; The two quadrature demodulated signals output by the carrier mixer are respectively filtered by the second low-pass filter and the third low-pass filter to filter out the frequency components with frequency ω _r + ω _s , the obtained signal Z _I2 and Z _Q2 , respectively expressed by formula (6) and formula (7): Z _I2 =S _{I_IF} (t)+S _{I_tip} (t)+S _{I_le} (t) (6) Z _Q2 =S _{Q_IF} (t)+S _{Q_tip} (t)+S _{Q_le} (t) (7) in,

is the reflected signal part of the carrier in Z _I2 ;

It is the reflection part of the sensor end face in Z _I2 and the stray reflection part of the stator around the rotor to be tested;

It is the RF co-frequency crosstalk part in Z _I2 due to the low isolation of the RF chip or circulator;

is the reflected signal part of the carrier in Z _Q2 ;

It is the reflection part of the sensor end face in Z _Q2 and the stray reflection part of the stator around the rotor to be tested;

It is the RF co-frequency crosstalk part in Z _Q2 due to the low isolation of the RF chip or circulator; k is the amplitude imbalance factor,

is the phase imbalance factor; In the computer, the transmitted Z _I2 and Z _I1 are subjected to mixing operation and low-pass filtering to obtain the signal V _I (d), and Z _Q2 and Z _I1 are subjected to mixing operation and low-pass filtering to obtain the signal V _Q (d), V _I (d) and V _Q (d) are represented by equations (8) and (9), respectively:

in,

When the temperature of the working environment is stable and the vibration state of the sensor installation environment is stable and unchanged,

A _tip and A _le are both fixed values and do not change with the change of the rotor-stator axial gap, while A _IF is only related to the rotor-stator axial gap, and inversely proportional to the second power of the rotor-stator axial gap d; By the principle of microwave phase ranging:

where ω ₁ is the spatial angular frequency of the transmitted microwave radio frequency signal; It is obtained by formulas (8), (9) and (10):

in,

j is an imaginary unit; Taking advantage of the fact that the V(d) signal spectrum mainly consists of three parts: the main frequency ω ₁ , the mirror frequency -ω ₁ and the DC frequency, the three parts are obtained by scanning the space distance, that is, sampling the axial gap of the rotor and stator at equal intervals. The amplitudes at the frequencies are A(ω ₁ ), A(-ω ₁ ), and A(0) respectively; the amplitude-phase unbalance correction factor uses equations (12), (13), (14) and (15) means:

A model for suppressing co-channel interference signals is established as shown in equation (17):

Therefore, the axial gap d of the rotor and stator after suppressing the same-frequency interference signal is expressed by equation (18):

in,

This constant value is obtained by calibration without changing with the axial clearance of the rotor and stator to be measured. 4. a kind of on-line measuring method of rotor-stator axial gap based on microwave, is characterized in that, realizes by means of the device described in claim 1, wherein: the local oscillator input signal Y ₂ and the radio frequency input signal of reference road mixer input X ₁ is represented by formula (1) and formula (2) respectively:

Among them, A ₁ is the amplitude of the radio frequency input signal X ₁ , A ₆ is the amplitude of the local oscillator input signal Y ₂ , ω _s is the reference frequency, ω _r is the carrier frequency,

is the phase of the RF input signal X ₁ ,

is the phase of the local oscillator input signal Y ₂ ; Referring to the demodulated signal output by the mixer of the reference channel, after the first low-pass filter filters out the frequency components with the frequency ω _r + ω _s , the obtained signal Z _I1 is expressed by equation (3):

Among them, ω _IF =ω _s -ω _r is the intermediate frequency; The RF input signal Y ₁ and the local oscillator input signal X ₂ input by the carrier mixer are expressed by formula (4) and formula (5) respectively:

Among them, A ₂ is the amplitude of the local oscillator input signal X ₂ , A ₃ is the amplitude of the reflected signal part of the carrier wave in the radio frequency input signal Y ₁ , A ₄ is the reflected part of the sensor end face in the radio frequency input signal Y ₁ and around the rotor to be measured The amplitude of the stray reflection part of the static component, A ₅ is the amplitude of the RF co-frequency crosstalk part in the RF input signal Y ₁ due to the low isolation of the RF chip or the circulator,

is the phase of the local oscillator input signal _X2 ,

is the phase delay on the transmission cable of the reflected signal part of the carrier wave, the reflected part of the sensor end face and the stray reflection part of the stator around the rotor to be measured in the RF input signal Y ₁ ,

is the phase delayed on the transmission path of the RF co-frequency crosstalk part in the RF input signal Y ₁ due to the low isolation of the RF chip or the circulator,

is the phase to be measured generated by the change of the axial gap of the rotor stator in the reflected signal part of the carrier wave in the RF input signal Y ₁ ; The two quadrature demodulated signals output by the carrier mixer are respectively filtered by the second low-pass filter and the third low-pass filter to filter out the frequency components with frequency ω _r + ω _s , the obtained signal Z _I2 and Z _Q2 , respectively expressed by formula (6) and formula (7): Z _I2 =S _{I_IF} (t)+S _{I_tip} (t)+S _{I_le} (t) (6) Z _Q2 =S _{Q_IF} (t)+S _{Q_tip} (t)+S _{Q_le} (t) (7) in,

is the reflected signal part of the carrier in Z _I2 ;

It is the reflection part of the sensor end face in Z _I2 and the stray reflection part of the stator around the rotor to be tested;

It is the RF co-frequency crosstalk part in Z _I2 due to the low isolation of the RF chip or circulator;

is the reflected signal part of the carrier in Z _Q2 ;

It is the reflection part of the sensor end face in Z _Q2 and the stray reflection part of the stator around the rotor to be tested;

It is the RF co-frequency crosstalk part in Z _Q2 due to the low isolation of the RF chip or circulator; k is the amplitude imbalance factor,

is the phase imbalance factor; In the computer, the transmitted Z _I2 and Z _I1 are subjected to mixing operation and low-pass filtering to obtain the signal V _I (d), and Z _Q2 and Z _I1 are subjected to mixing operation and low-pass filtering to obtain the signal V _Q (d), V _I (d) and V _Q (d) are represented by equations (8) and (9), respectively:

in,

When the temperature of the working environment is stable and the vibration state of the sensor installation environment is stable and unchanged,

A _tip and A _le are both fixed values and do not change with the change of the rotor-stator axial gap, while A _IF is only related to the rotor-stator axial gap, and inversely proportional to the second power of the rotor-stator axial gap d; By the principle of microwave phase ranging:

where ω ₁ is the spatial angular frequency of the transmitted microwave radio frequency signal; It is obtained by formulas (8), (9) and (10):

in,

j is an imaginary unit; Taking advantage of the fact that the V(d) signal spectrum mainly consists of three parts: the main frequency ω ₁ , the mirror frequency -ω ₁ and the DC frequency, the three parts are obtained by scanning the space distance, that is, sampling the axial gap of the rotor and stator at equal intervals. The amplitudes at the frequencies are A(ω ₁ ), A(-ω ₁ ), and A(0) respectively; the amplitude-phase unbalance correction factor uses equations (12), (13), (14) and (15) means:

A model for suppressing co-channel interference signals is established as shown in equation (17):

Therefore, the axial gap d of the rotor and stator after suppressing the same-frequency interference signal is expressed by equation (18):

in,

This constant value is obtained by calibration without changing with the axial clearance of the rotor and stator to be measured.

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