An aero-engine gas path working medium detection system and a detection method thereof

Abstract

The application provides an aero-engine gas path working medium detection system and a detection method thereof, which collects abnormal electrostatic particle signals through an electrostatic sensor arranged on an engine tail nozzle device, converts the abnormal electrostatic particle signals into induced voltage signals through a signal conversion device, and outputs the induced voltage signals to a data processing terminal for processing through a multi-channel high-speed acquisition device, so that the fault degree of abnormal particles is determined by calculating the root mean square value of the abnormal electrostatic signals, the sensitivity of the monitoring system is improved, the signal is amplified and filtered through the signal conversion device, the phenomenon of single gain unpredictable signal measurement range distortion caused by the change of particle charge amount due to factors such as the speed of the engine, the size of the particles, the concentration of the particles, the material of the particles and the like is avoided, and real-time monitoring of the state of the engine gas path is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aero-engine state monitoring, in particular to an aero-engine gas path working medium detection system and a detection method thereof. BACKGROUND

[0002] The change of the particle charge in the aero-engine gas path often indicates that the operation of the gas path components is abnormal, such as blade coating peeling, tip ablation block, combustion chamber overburning, and light wear between the tip and the casing. The gas path working medium detection technology using an electrostatic sensor is an aero-engine gas path working state detection technology based on electrostatic induction theory. The electrostatic sensor is used to detect the electrostatic signal of the charged particles in the engine gas path to determine the running state of the aero-engine gas path components and diagnose potential faults, effectively solving the problem of real-time monitoring of the engine gas path state.

[0003] In existing research, the aero-engine gas path monitoring system based on the electrostatic sensor usually uses a single electrostatic sensor and a signal conditioning device. This results in uneven sensitivity of the electrostatic monitoring system and insufficient amount of useful information, which significantly affects the detection effect. SUMMARY

[0004] To solve the problem of real-time monitoring of the engine gas path state in the prior art, the present application provides an aero-engine gas path working medium detection system and a detection method thereof. The electrostatic sensor is arranged on the engine tail spray device to collect abnormal electrostatic particle signals. The signal conversion device is arranged to convert the abnormal electrostatic particle signals into induced voltage signals. The multi-channel high-speed acquisition device is arranged to output the induced voltage signals to the data processing terminal for processing. The degree of abnormal particle fault is determined by calculating the size of the root mean square value of the abnormal electrostatic signal. The sensitivity of the monitoring system is improved. The signal conversion device amplifies and filters the signal to avoid the phenomenon of single gain unpredictable signal measurement range distortion caused by the change of particle charge due to factors such as engine speed, particle size, particle concentration, and particle material. Real-time monitoring of the engine gas path state is realized.

[0005] The present application is implemented as follows:

[0006] An aero-engine gas path working medium detection system, comprising an engine tail spray device, an electrostatic sensor, a high-temperature-resistant shielding cable, a signal conversion device, a multi-channel high-speed acquisition device, and a data processing terminal.

[0007] The electrostatic sensor is installed on the engine tail spray device and connected to the signal conversion device through the high-temperature-resistant shielding cable. It is used to output the collected abnormal particle electrostatic signals to the signal conversion device.

[0008] The signal conversion device is connected with the multi-channel high-speed acquisition device through a high-temperature-resistant shielding cable, and is used for converting the abnormal particle electrostatic signal obtained from the electrostatic sensor into an induced voltage signal and outputting to the multi-channel high-speed acquisition device.

[0009] The data processing terminal is connected with the multi-channel high-speed acquisition device, and is used for processing the induced voltage signal obtained from the multi-channel high-speed acquisition device to calculate the root mean square value of the abnormal electrostatic signal to determine the fault degree of the abnormal particle.

[0010] In order to better realize the present application, further, the signal conversion device comprises a power supply circuit, a signal pickup circuit and a signal amplification filtering circuit.

[0011] The power supply circuit is connected with the signal amplification filtering circuit, and is used for taking the generated positive power supply VCC+ and negative power supply VCC- as the working voltage of the signal amplification filtering circuit.

[0012] The signal pickup circuit is connected with the electrostatic sensor and the signal amplification circuit, and is used for converting the abnormal electrostatic signal obtained from the electrostatic sensor into an induced voltage signal and outputting to the signal amplification filtering circuit.

[0013] The signal amplification filtering circuit is connected with the multi-channel high-speed acquisition device, and is used for outputting the amplified and filtered induced voltage signal to the multi-channel high-speed acquisition device for acquisition.

[0014] In order to better realize the present application, further, the signal amplification filtering circuit comprises a first-stage parallel amplification circuit.

[0015] The first-stage parallel amplification circuit comprises an amplifier U1, resistors R6, R7, R8, R9, R10, R11, R12, R13, R14, R15, R16, R17, capacitors C4 and C5.

[0016] The pin 3 of the amplifier U1 is connected with the pins 5, 10 and 12 of the amplifier U1.

[0017] The pin 2 of the amplifier U1 is connected with the resistors R6 and R10.

[0018] The pin 1 of the amplifier U1 is connected with the resistors R10 and R14.

[0019] The pin 4 of the amplifier U1 is connected with the power supply VCC+ and the grounded capacitor C4.

[0020] The pin 6 of the amplifier U1 is connected with the resistors R7 and R11.

[0021] Pin 7 of the amplifier U1 is connected with the resistor R11 and the resistor R15;

[0022] Pin 9 of the amplifier U1 is connected with the resistor R8 and the resistor R12;

[0023] Pin 8 of the amplifier U1 is connected with the resistor R12 and the resistor R16;

[0024] Pin 13 of the amplifier U1 is connected with the resistor R9 and the resistor R13;

[0025] Pin 14 of the amplifier U1 is connected with the resistor R13 and the resistor R17;

[0026] Pin 11 of the amplifier U1 is connected with the capacitor C5 of the power supply VCC- and the ground;

[0027] The resistor R14, the resistor R15, the resistor R16 and the resistor R17 are connected with the multi-channel high-speed acquisition device.

[0028] In order to better realize the application, further, the signal amplification filter circuit further comprises an adder, a first high-pass filter, a fourth-order Butterworth low-pass filter and a follower;

[0029] The adder comprises an amplifier U2, a resistor R18 and a capacitor C12;

[0030] The first high-pass filter comprises a capacitor C6 and a resistor R37;

[0031] The fourth-order Butterworth low-pass filter comprises a first second-order voltage-controlled power supply low-pass filter and a second second-order voltage-controlled power supply low-pass filter connected in sequence;

[0032] The first second-order voltage-controlled power supply low-pass filter comprises an amplifier U2, a resistor R19, a resistor R20, a resistor R21, a resistor R22, a capacitor C7 and a capacitor C8;

[0033] The second second-order voltage-controlled power supply low-pass filter comprises an amplifier U2, a resistor R25, a resistor R26, a resistor R23, a resistor R24, a capacitor C9 and a capacitor C10;

[0034] The follower comprises an amplifier U2 and a capacitor C11;

[0035] Pin 2 of the amplifier U2 is connected with the resistor R14, the resistor R15, the resistor R16, the resistor R17 and the resistor R18;

[0036] Pin 11 of the amplifier U2 is connected with the capacitor C12 of the power supply VCC- and the ground;

[0037] Pin 1 of the amplifier U2 is connected with the resistor R18 and the capacitor C6;

[0038] Pin 5 of the amplifier U2 is connected with the capacitor C7 grounded, the resistor R19, the resistor R20 connected in series with each other;

[0039] Pin 6 of the amplifier U2 is connected with the resistor R21, the resistor R22;

[0040] Pin 7 of the amplifier U2 is connected with the capacitor C8, the resistor R22, the resistor R25;

[0041] Pin 12 of the amplifier U2 is connected with the resistor R26, the capacitor C9 grounded;

[0042] Pin 13 of the amplifier U2 is connected with the resistor R23, the resistor R24;

[0043] Pin 14 of the amplifier U2 is connected with the capacitor C10, pin 10 of the amplifier U2;

[0044] Pin 4 of the amplifier U2 is connected with the power supply VCC+, the capacitor C11 grounded;

[0045] Pin 8 of the amplifier U2 is connected with pin 9 of the amplifier U2, the multi-channel high-speed acquisition device.

[0046] In order to better realize the present application, further, the signal amplification filter circuit further comprises a first inverting amplifier, a second high-pass filter, a third second-order Butterworth low-pass filter, a second inverter, a first-order active low-pass filter circuit, a third high-pass filter;

[0047] The first inverting amplifier comprises an amplifier U3, a resistor R27, a resistor R28, a capacitor C13;

[0048] The second high-pass filter comprises a resistor R38, a capacitor C14;

[0049] The third second-order Butterworth low-pass filter comprises an amplifier U3, a resistor R29, a resistor R30, a resistor R31, a resistor R32, a capacitor C15, a capacitor C16;

[0050] The second inverter comprises an amplifier U3, a capacitor C17, a resistor R33, a resistor R34, a capacitor C18;

[0051] The first-order active low-pass filter circuit comprises an amplifier U3, a resistor R35, a capacitor C19, a capacitor C20;

[0052] The third high-pass filter comprises a resistor R36, a capacitor C21;

[0053] The pin 13 of the amplifier U3 is connected with the pin 8 of the amplifier U2, the resistance R28, the capacitor C13 and the resistance R27 which are connected in series with each other;

[0054] The pin 14 of the amplifier U3 is connected with the resistance R28 and the capacitor C14;

[0055] One end of the resistance R38 is connected between the capacitor C14 and the resistance R29, and the other end is connected with the ground;

[0056] The pin 10 of the amplifier U3 is connected with the capacitor C15 which is grounded, the resistance R29 and the resistance R30 which are connected in series with each other;

[0057] The pin 9 of the amplifier U3 is connected between the resistance R31 and the resistance R32 which are connected in series with each other and grounded;

[0058] The pin 8 of the amplifier U3 is connected with the capacitor C16, the capacitor C17 and the resistance R32;

[0059] The pin 6 of the amplifier U3 is connected with the resistance R34, the capacitor C17 and the resistance R33 which are connected in series with each other;

[0060] The pin 11 of the amplifier U3 is connected with the power supply VCC- and the capacitor C18 which is grounded;

[0061] The pin 7 of the amplifier U3 is connected with the resistance R34 and the resistance R35;

[0062] The pin 3 of the amplifier U3 is connected with the resistance R35 and the capacitor C19 which is grounded;

[0063] The pin 4 of the amplifier U3 is connected with the power supply VCC+ and the capacitor C20 which is grounded;

[0064] The capacitor C21 is connected between the pin 1 of the amplifier U3 and the multi-channel high-speed acquisition device;

[0065] One end of the resistance R36 is connected between the capacitor C21 and the multi-channel high-speed acquisition device, and the other end is connected with the ground.

[0066] In order to better realize the application, further, the signal pickup circuit comprises a resistance R1, a capacitor C1, a resistance R2, a diode D1 and a diode D2;

[0067] One end of the resistance R1 is connected with the electrostatic sensor, and the other end is connected with the signal amplification and filtering circuit;

[0068] The capacitor C1, the resistance R2, the diode D1 and the diode D2 are connected in parallel with each other, one end of which is connected between the resistance R1 and the input end of the signal amplification and filtering circuit, and the other end is connected with the ground.

[0069] In order to better realize the present application, further, the power supply circuit comprises a triode D3, a capacitor C22, a capacitor C23, a triode D4;

[0070] One end of the triode D3 is connected with the power supply VCC+, and the other end is connected with the signal amplification filter circuit;

[0071] One end of the triode D4 is connected with the power supply VCC-, and the other end is connected with the signal amplification filter circuit;

[0072] One end of the capacitor C22 is connected between the triode D3 and the signal amplification filter circuit, and the other end is connected with the ground;

[0073] One end of the capacitor C23 is connected between the triode D4 and the signal amplification filter circuit, and the other end is connected with the ground.

[0074] In order to better realize the present application, further, the electrostatic sensor is arranged as a plurality of sensors.

[0075] Based on the above-mentioned aero-engine gas path working medium detection system, in order to better realize the present application, further, an aero-engine gas path working medium detection method is provided, comprising the following steps:

[0076] Step 1: The electrostatic sensor collects abnormal electrostatic signals, and converts the abnormal electrostatic signals into induced voltage signals in the signal conversion device;

[0077] Step 2: The multi-channel high-speed acquisition device acquires the converted induced voltage signals and outputs them to a data processing terminal;

[0078] Step 3: The data processing terminal judges the range of the acquired induced voltage signals and labels the effectiveness of the induced voltage signals;

[0079] Step 4: The induced voltage signals with effectiveness are processed by the rolling mean filter method to remove the direct current component;

[0080] Step 5: The charge quantity of the induced voltage signal processed in step 4 is calculated to obtain the voltage sampling signal at the current time;

[0081] Step 6: The voltage sampling signal obtained in step 5 is labeled to obtain the start data n1 and the end data n2 of the voltage sampling value at time t;

[0082] Step 7: The root mean square value of the voltage sampling signal at time t is calculated according to the start data n1 and the end data n2 obtained in step 6,

[0083] For better implementation of the present application, further, the specific operation of step 3 is that the data processing terminal judges the range of the obtained induction voltage signal, judges whether the obtained induction voltage signal is less than 10v, if yes, judges that the induction voltage signal has validity, if not, judges whether there are continuous multiple induction voltage signals of 10V, if yes, judges that the induction voltage signal does not have validity, if not, judges that the induction voltage signal has validity.

[0084] For better implementation of the present application, further, the specific operation of step 3 is that the data processing terminal judges the range of the obtained induction voltage signal, judges whether the obtained induction voltage signal is less than 10v, if yes, judges that the induction voltage signal has validity, if not, judges whether there are continuous multiple induction voltage signals of 10V, if yes, judges that the induction voltage signal does not have validity, if not, judges that the induction voltage signal has validity.

[0085] Step 61: calculate the average value of the voltage sampling signal amplitude obtained in step 5, and take the average value of the voltage sampling signal amplitude as a flatness coefficient;

[0086] Step 62: divide the voltage sampling signal into several equal small segments, and calculate the difference between the average value of each point in the current small segment and the average value of the current small segment.

[0087] Step 63: judge whether the average value difference of the current small segment is less than the flatness coefficient, if yes, it is a flat area, otherwise it is a non-flat area, and the start point data n1 and the end point data n2 of the voltage sampling signal at the current time.

[0088] The present application has the following beneficial effects:

[0089] (1) The present application adopts multiple electrostatic sensors to sense the electrostatic signal of the fault particles, and sets multiple channel high-speed acquisition devices to output the induction voltage signal to the data processing terminal for processing, thereby improving the sensitivity of the monitoring system.

[0090] (2) The present application adopts a signal conversion device to convert the electrostatic signal detected by the electrostatic sensor, and amplifies and filters the signal, thereby avoiding the phenomenon of unpredictable signal measurement range distortion caused by the change of particle charge due to factors such as the speed of the engine, the size of the particle, the concentration of the particle, and the material of the particle.

[0091] (3) The present application processes the converted electrostatic signal voltage value collected by the multiple channel high-speed acquisition device, judges the signal validity, eliminates the invalid measurement signal, and processes the valid signal, thereby strengthening the effective measurement of the particle fault signal.

[0092] (4) The processing of the valid signal eliminates the difference of the hardware circuit itself, has good applicability, and provides a new idea for engine air path fault detection. BRIEF DESCRIPTION OF DRAWINGS

[0093] Figure 1 is a system structure schematic diagram of the present application;

[0094] Figure 2 is the circuit schematic of the power supply circuit;

[0095] Figure 3 is the circuit schematic of the signal pickup circuit;

[0096] Figure 4 is the circuit schematic of the signal amplification and filtering circuit;

[0097] Figure 5 is the schematic diagram of the signal processing flow of the present application;

[0098] Figure 6 is the schematic diagram of the fault signal starting point and ending point identification of the data processing of the present application;

[0099] Figure 7 is the circuit schematic of the first parallel amplification circuit in the signal amplification and filtering circuit;

[0100] Figure 8 is the circuit schematic of the adder circuit in the signal amplification and filtering circuit;

[0101] Figure 9 is the circuit schematic of the first high-pass filter circuit in the signal amplification and filtering circuit;

[0102] Figure 10 is the circuit schematic of the fourth-order Butterworth low-pass filter circuit in the signal amplification and filtering circuit;

[0103] Figure 11 is the circuit schematic of the follower circuit in the signal amplification and filtering circuit;

[0104] Figure 12 is the circuit schematic of the first inverting amplifier circuit in the signal amplification and filtering circuit;

[0105] Figure 13 is the circuit schematic of the second high-pass filter circuit in the signal amplification and filtering circuit;

[0106] Figure 14 is the circuit schematic of the third second-order Butterworth low-pass filter circuit in the signal amplification and filtering circuit;

[0107] Figure 15 is the circuit schematic of the second inverter circuit in the signal amplification and filtering circuit;

[0108] Figure 16 is the circuit schematic of the first-order active low-pass filter circuit in the signal amplification and filtering circuit;

[0109] Figure 17 is the circuit schematic of the third high-pass filter circuit in the signal amplification and filtering circuit;

[0110] Wherein, 1, engine tail spray device, 2, electrostatic sensor, 3, high temperature resistant shielded cable, 4, signal conversion device, 5, multi-channel high-speed acquisition device, 6, data processing terminal. DETAILED DESCRIPTION

[0111] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. It should be understood that the described embodiments are only a part of the embodiments of the present application, not all the embodiments, and therefore should not be regarded as limiting the scope of protection. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0112] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "set", "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected, it can be mechanically connected, or it can be electrically connected, it can be directly connected, or indirectly connected through an intermediate medium, it can be the communication inside two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0113] Embodiment 1

[0114] The present embodiment proposes an aero-engine gas path working medium detection system, as shown in Figure 1 Fig. 1, comprising an engine tail spray device 1, an electrostatic sensor 2, a high temperature resistant shielded cable 3, a signal conversion device 4, a multi-channel high-speed acquisition device 5, and a data processing terminal 6.

[0115] The electrostatic sensor 2 is installed on the engine tail spray device 1 and connected with the signal conversion device 4 through the high temperature resistant shielded cable 3, for outputting the collected abnormal particle electrostatic signals to the signal conversion device 4.

[0116] The signal conversion device 4 is connected with the multi-channel high-speed acquisition device 5 through the high temperature resistant shielded cable 3, for converting the abnormal particle electrostatic signals obtained from the electrostatic sensor 2 into induced voltage signals and outputting to the multi-channel high-speed acquisition device 5.

[0117] The data processing terminal 6 is connected with the multi-channel high-speed acquisition device 5, for processing the induced voltage signals obtained from the multi-channel high-speed acquisition device 5, calculating the root mean square value of the abnormal electrostatic signals to judge the fault degree of the abnormal particles.

[0118] Working principle: the embodiment collects the abnormal electrostatic particle signal by arranging the electrostatic sensor 2 on the engine tail spray device 1, converts the abnormal electrostatic particle signal into an induced voltage signal through the signal conversion device, and outputs the induced voltage signal to the data processing terminal 6 for processing through the multi-channel high-speed acquisition device 5, judges the abnormal particle fault degree by calculating the root mean square value of the abnormal electrostatic signal, improves the sensitivity of the monitoring system, and avoids the phenomenon of single gain unpredictable signal measurement range distortion caused by the change of particle charge due to the factors such as the speed of the engine, the size of the particle, the concentration of the particle, and the material of the particle, realizes the real-time monitoring of the engine gas path state.

[0119] Embodiment 2:

[0120] Based on the above-mentioned embodiment 1, the aviation engine gas path working medium detection system proposed by the present application is described in detail as shown in Figure 2 、 Figure 3 、 Figure 4 、 Figure 7 、 Figure 8 、 Figure 9 、 Figure 10 、 Figure 11 、 Figure 12 、 Figure 13 、 Figure 14 、 Figure 15 、 Figure 16 、 Figure 17 .

[0121] Working principle: the signal amplification and filtering circuit includes a parallel amplification circuit;

[0122] As shown in Figure 7 , the parallel amplification circuit includes an amplifier U1, resistors R6, R7, R8, R9, R10, R11, R12, R13, R14, R15, R16, R17, capacitors C4 and C5.

[0123] The pin 3 of the amplifier U1 is connected with the pins 5, 10 and 12 of the amplifier U1;

[0124] The pin 2 of the amplifier U1 is connected with the resistors R6 and R10;

[0125] The pin 1 of the amplifier U1 is connected with the resistors R10 and R14;

[0126] The pin 4 of the amplifier U1 is connected with the power supply VCC+ and the ground capacitor C4;

[0127] Pin 6 of the amplifier U1 is connected with the resistor R7 and the resistor R11;

[0128] Pin 7 of the amplifier U1 is connected with the resistor R11 and the resistor R15;

[0129] Pin 9 of the amplifier U1 is connected with the resistor R8 and the resistor R12;

[0130] Pin 8 of the amplifier U1 is connected with the resistor R12 and the resistor R16;

[0131] Pin 13 of the amplifier U1 is connected with the resistor R9 and the resistor R13;

[0132] Pin 14 of the amplifier U1 is connected with the resistor R13 and the resistor R17;

[0133] Pin 11 of the amplifier U1 is connected with the capacitor C5 of the power supply VCC- and the ground;

[0134] The resistor R14, the resistor R15, the resistor R16 and the resistor R17 are connected with the multi-channel high-speed acquisition device 5.

[0135] The signal amplification and filtering circuit further comprises an adder, a first high-pass filter, a fourth-order Butterworth low-pass filter and a follower;

[0136] As shown in Figure 8 , the adder comprises an amplifier U2, a resistor R18 and a capacitor C12;

[0137] As shown in Figure 9 , the first high-pass filter comprises a capacitor C6 and a resistor R37;

[0138] As shown in Figure 10 , the fourth-order Butterworth low-pass filter comprises a first second-order voltage-controlled power supply low-pass filter and a second second-order voltage-controlled power supply low-pass filter connected in sequence;

[0139] As shown in Figure 10 , the first second-order voltage-controlled power supply low-pass filter comprises an amplifier U2, a resistor R19, a resistor R20, a resistor R21, a resistor R22, a capacitor C7 and a capacitor C8;

[0140] As shown in Figure 10 , the second second-order voltage-controlled power supply low-pass filter comprises an amplifier U2, a resistor R25, a resistor R26, a resistor R23, a resistor R24, a capacitor C9 and a capacitor C10;

[0141] As shown in Figure 11 , the follower comprises an amplifier U2 and a capacitor C11;

[0142] Pin 2 of the amplifier U2 is connected with the resistor R14, the resistor R15, the resistor R16, the resistor R17, the resistor R18;

[0143] Pin 11 of the amplifier U2 is connected with the power supply VCC-, the capacitor C12 grounded;

[0144] Pin 1 of the amplifier U2 is connected with the resistor R18, the capacitor C6;

[0145] Pin 5 of the amplifier U2 is connected with the capacitor C7 grounded, the resistor R19, the resistor R20 connected in series with each other;

[0146] Pin 6 of the amplifier U2 is connected with the resistor R21, the resistor R22;

[0147] Pin 7 of the amplifier U2 is connected with the capacitor C8, the resistor R22, the resistor R25;

[0148] Pin 12 of the amplifier U2 is connected with the resistor R26, the capacitor C9 grounded;

[0149] Pin 13 of the amplifier U2 is connected with the resistor R23, the resistor R24;

[0150] Pin 14 of the amplifier U2 is connected with the capacitor C10, pin 10 of the amplifier U2;

[0151] Pin 4 of the amplifier U2 is connected with the power supply VCC+, the capacitor C11 grounded;

[0152] Pin 8 of the amplifier U2 is connected with pin 9 of the amplifier U2, the multi-channel high-speed acquisition device 5.

[0153] The signal amplification filter circuit further comprises a first inverting amplifier, a second high-pass filter, a third second-order Butterworth low-pass filter, a second inverter, a first-order active low-pass filter circuit, a third high-pass filter;

[0154] The first inverting amplifier comprises an amplifier U3, a resistor R27, a resistor R28, a capacitor C13;

[0155] The second high-pass filter comprises a resistor R38, a capacitor C14;

[0156] The third second-order Butterworth low-pass filter comprises an amplifier U3, a resistor R29, a resistor R30, a resistor R31, a resistor R32, a capacitor C15, a capacitor C16;

[0157] The second inverter comprises a capacitor C17, a resistor R33, a resistor R34, a capacitor C18;

[0158] The first-order active low-pass filter circuit comprises an amplifier U3, a resistor R35, a capacitor C19, and a capacitor C20;

[0159] The third high-pass filter comprises a resistor R36 and a capacitor C21;

[0160] Pin 13 of the amplifier U3 is connected with pin 8 of the amplifier U2, a resistor R28, a capacitor C13, and a resistor R27 in series;

[0161] Pin 14 of the amplifier U3 is connected with the resistor R28 and a capacitor C14;

[0162] One end of the resistor R38 is connected between the capacitor C14 and the resistor R29, and the other end is connected with the ground;

[0163] Pin 10 of the amplifier U3 is connected with a grounded capacitor C15, a resistor R29, and a resistor R30 in series;

[0164] Pin 9 of the amplifier U3 is connected between a grounded resistor R31 and a resistor R32 in series;

[0165] Pin 8 of the amplifier U3 is connected with a capacitor C16, a capacitor C17, and a resistor R32;

[0166] Pin 6 of the amplifier U3 is connected with a resistor R34, a capacitor C17, and a resistor R33 in series;

[0167] Pin 11 of the amplifier U3 is connected with a power supply VCC- and a grounded capacitor C18;

[0168] Pin 7 of the amplifier U3 is connected with a resistor R34 and a resistor R35;

[0169] Pin 3 of the amplifier U3 is connected with a resistor R35 and a grounded capacitor C19;

[0170] Pin 4 of the amplifier U3 is connected with a power supply VCC+ and a grounded capacitor C20;

[0171] The capacitor C21 is connected between pin 1 of the amplifier U3 and a multi-channel high-speed acquisition device 5;

[0172] One end of the resistor R36 is connected between the capacitor C21 and the multi-channel high-speed acquisition device 5, and the other end is connected with the ground.

[0173] The signal pickup circuit comprises a resistor R1, a capacitor C1, a resistor R2, a diode D1, and a diode D2;

[0174] One end of the resistor R1 is connected with the electrostatic sensor 2, and the other end is connected with the signal amplification and filtering circuit;

[0175] The capacitor C1, the resistor R2, the diode D1 and the diode D2 are connected in parallel with each other, one end of which is connected between the resistor R1 and the input end of the signal amplification filter circuit, and the other end of which is connected with the ground.

[0176] The power supply circuit comprises a triode D3, a capacitor C22, a capacitor C23 and a triode D4.

[0177] One end of the triode D3 is connected with the power supply VCC+, and the other end of the triode D3 is connected with the signal amplification filter circuit.

[0178] One end of the triode D4 is connected with the power supply VCC-, and the other end of the triode D4 is connected with the signal amplification filter circuit.

[0179] One end of the capacitor C22 is connected between the triode D3 and the signal amplification filter circuit, and the other end of the capacitor C22 is connected with the ground.

[0180] One end of the capacitor C23 is connected between the triode D4 and the signal amplification filter circuit, and the other end of the capacitor C23 is connected with the ground.

[0181] Wherein, Figure 7 , Figure 8 , Figure 9 , Figure 10 , Figure 11 , Figure 12 , Figure 13 , Figure 14 , Figure 15 , Figure 16 , Figure 17 The circuit principle diagrams in the above are connected with each other in sequence, and the signal amplification filter circuit in Figure 4 is formed.

[0182] The other parts of the embodiment are the same as those of the above-mentioned embodiment 1, and thus will not be described herein.

[0183] Embodiment 3

[0184] The embodiment is based on any one of the above-mentioned embodiments 1-2, and as shown in Figure 5 , Figure 6 proposes an aero-engine gas path working medium detection method.

[0185] Working principle: the aero-engine gas path working medium detection method proposed in the embodiment comprises the following steps:

[0186] Step 1: the electrostatic sensor 2 collects an abnormal electrostatic signal, and converts the abnormal electrostatic signal into an induced voltage signal in the signal conversion device;

[0187] Step 2: the multi-channel high-speed acquisition device 5 acquires the converted induced voltage signal and outputs the converted induced voltage signal to the data processing terminal 6;

[0188] Step 3: The data processing terminal 6 judges the range of the acquired induced voltage signal, and labels the validity of the induced voltage signal;

[0189] Step 4: The induced voltage signal with validity is processed by removing direct current component by using rolling mean filtering method;

[0190] Step 5: The charge amount of the induced voltage signal processed in step 4 is calculated, and the voltage sampling signal at time t is obtained;

[0191] Step 6: The voltage sampling signal obtained in step 5 is labeled, and the start data n1 and the end data n2 of the voltage sampling value at time t are obtained;

[0192] Step 7: The root mean square value of the voltage sampling signal at time t is calculated according to the start data n1 and the end data n2 obtained in step 6, and the fault degree of the abnormal electrostatic signal is judged according to the size of the root mean square value. The greater the root mean square value, the higher the fault degree.

[0193] The specific operation of step 3 is that the data processing terminal 6 judges the range of the acquired induced voltage signal, judges whether the acquired induced voltage signal is less than 10v, if yes, it is judged that the induced voltage signal has validity, if not, it is judged whether there are continuous multiple induced voltage signals of 10V, if yes, it is judged that the induced voltage signal does not have validity, if not, it is judged that the induced voltage signal has validity.

[0194] The step 6 specifically includes the following steps:

[0195] Step 61: The average value of the amplitude of the voltage sampling signal obtained in step 5 is calculated, and the average value of the amplitude of the voltage sampling signal is taken as a flatness coefficient;

[0196] Step 62: The voltage sampling signal is divided into several equal small segments, and the difference between the average value of each point in the current small segment and the average value of the current small segment is calculated;

[0197] Step 63: It is judged whether the average value difference of the current small segment is less than the flatness coefficient, if less than, it is a flat area, otherwise it is a non-flat area, and the start data n1 and the end data n2 of the voltage sampling signal at the current time are obtained.

[0198] The other parts of the embodiment are the same as any one of the above embodiments 1-2, and will not be described again.

[0199] Embodiment 4:

[0200] This embodiment is further described in detail in combination with a specific embodiment on the basis of any one of the above embodiments 1-3.

[0201] Working principle: as Figure 1The engine tail nozzle device 1, the electrostatic sensor 2, the high-temperature shielding cable 3, the signal conversion device 4, the multi-channel high-speed acquisition device 5, and the data processing terminal 6.

[0202] The electrostatic sensor 2 is installed on the engine tail nozzle device 1 in an array mode at positions with an interval of 90 degrees in a threaded mode, the electrostatic sensor 2 is connected with the signal conversion device 4 through the high-temperature shielding cable 3, the cable plug is connected in a pinhole type connection threaded fastening mode to ensure reliable connection and shielding, the signal conversion device 4 is connected with the multi-channel high-speed acquisition device 5 through the high-temperature shielding cable 3 to transmit the electrostatic signal, and the data processing terminal 6 judges and processes the collected electrostatic signal and displays the result.

[0203] First, the electrostatic sensor 2 array senses the abnormal particle electrostatic signal of the aircraft engine gas path.

[0204] Second, the signal conversion device combination includes four signal conversion circuits with different gains, and the amplification gains are 96dB, 106dB, 114dB, and 121dB, respectively, which cover the measurement of different sizes of charged signals caused by different engine speeds, different particle sizes, different particle concentrations, and different particle materials.

[0205] As shown in Figure 2 The power supply circuit is composed of diode D3, diode D4, capacitor C22, and capacitor C23, wherein the diode adopts IN4148 for current limiting protection, and the generated power supply VCC+ and power supply VCC- provide working voltage for the subsequent amplifier.

[0206] As shown in Figure 3 The VIN signal is the input signal, and the resistor R1, the capacitor C1, the diode D1, and the diode D2 constitute the signal pickup circuit to convert the electrostatic signal into a voltage signal and output the signal Vin1.

[0207] As shown in Figure 4 The first-stage parallel amplification is composed of the amplifier U1, the resistor R6, the resistor R7, the resistor R8, the resistor R9, the resistor R10, the resistor R11, the resistor R12, the resistor R13, the resistor R14, the resistor R15, the resistor R16, the resistor R17, the capacitor C4, and the capacitor C5. The amplification multiples of the four channels of the amplifier U1 are 1+R10 / R6, 1+R11 / R7, 1+R12 / R8, and 1+R13 / R9, respectively, and the capacitor C4 and the capacitor C5 are power filter capacitors.

[0208] The 1, 2, 3, 11 pins of the amplifier U2 and the resistor R18, the capacitor C12 form a adder, the gain of the first stage parallel amplifier is added to be 20*lg(1+R10 / R6)+20*lg(1+R11 / R7)+20*lg(1+R12 / R8)+20*lg(1+R13 / R9), unit: dB.

[0209] The signal after the adder is isolated from the direct current component by the isolation capacitor C6, and the resistor R37 is an impedance matching resistor. Then it enters a four-order Butterworth low-pass filter composed of two second-order voltage-controlled voltage source low-pass filter circuits, which is used to filter out the interference brought by the previous stage circuit. The 5, 6, 7 pins of the amplifier U2, the resistor R19, the resistor R20, the resistor R21, the resistor R22, the capacitor C7, and the capacitor C8 form a second-order voltage-controlled voltage source low-pass filter circuit, which is composed of two RC filter circuits and a same-phase proportional amplification circuit, and the amplification gain is 20*lg(1+R22 / R21), unit: dB. Similarly, the 12, 13, 14 pins of the amplifier U2, the resistor R25, the resistor R26, the resistor R23, the resistor R24, the capacitor C9, and the capacitor C10 form a second-order voltage-controlled voltage source low-pass filter circuit, which is composed of two RC filter circuits and a same-phase proportional amplification circuit, and the amplification gain is 20*lg(1+R24 / R23), unit: dB.

[0210] After the signal passes through the four-order Butterworth low-pass filter, it passes through the follower composed of the 8, 9, 10 pins of the amplifier U2, wherein the 4 pin is connected to the power supply VCC+, and is grounded through the capacitor C11. The follower circuit mainly plays an isolation role.

[0211] After the signal passes through the follower and the isolation capacitor C13, it enters the inverting amplifier composed of the 12, 13, 14 pins of the amplifier U3 and the resistors R27 and R28 for amplification, and the amplification gain is 20*lg(1+R27 / R28), unit: dB.

[0212] The signal flowing out of the inverting amplifier is isolated from the direct current component by the isolation capacitor C14, and the resistor R38 is an impedance matching resistor. Then it enters the two-order Butterworth low-pass filter composed of the 8, 9, 10 pins of the amplifier U3, the resistors R29, R30, R31, R32, the capacitor C15, and the capacitor C16, and the interference signal is filtered out again.

[0213] The filtered signal flows through the isolation capacitor C17 and enters the inverting amplifier composed of the 5, 6, 7 pins of the amplifier U3 and the resistors R33 and R34 for amplification, and the amplification gain is 20*lg(1+R33 / R34), unit: dB.

[0214] The resistor R35, the capacitor C19, the capacitor C20, the pins 1, 2 and 3 of the amplifier U3 together constitute a first-order active low-pass filter circuit, and the signal is filtered again, and then flows through the high-pass filter circuit composed of the capacitor C21 and the resistor R36 to isolate the direct current signal, so that the conditioned induced voltage signal is obtained.

[0215] Different amplification gains are obtained by adjusting the resistance values related to amplification.

[0216] Again, the converted signal is collected by the multi-channel high-speed acquisition device 5, and in this embodiment, the USB7104B acquisition box is used, the input setting range is-10V~+10V, the maximum acquisition frequency is 2.5MHz, and the sampling frequency can be set independently.

[0217] Finally, the data of the four channels are comprehensively processed to obtain a division of the fault state of the air path working condition.

[0218] The data processing method is as follows:

[0219] (1) Data acquisition

[0220] As shown in Figure 5 , the range of the electrostatic conversion signal collected by each channel is judged, and the validity of the fault signal of each channel is marked. The specific operation steps are as follows:

[0221] After the system is powered on, the electrostatic conversion signal of the analog fault of each channel is collected;

[0222] It is judged whether the voltage data collected by each channel is all less than 10V, if yes, it is determined that the data of this channel is valid, if not, it is judged whether there are continuous multiple data of 10V, if yes, it is determined that the data of this channel is invalid, if not, it is determined that the data of this channel is valid;

[0223] Then, the valid data is processed according to the valid identification of each valid channel.

[0224] (2) Data preprocessing

[0225] The rolling mean filter method is used to process the data.

[0226] The processing formula is:

[0227]

[0228] Wherein, n is a variable, U is the voltage value obtained by collection, each variable n corresponds to a data, is the average value of n U, U n is the voltage value after removing the direct current component, and y(U, n) is the rolling filter function.

[0229] The rolling filter function formula is:

[0230] y(U,n) = (y(n-2) + y(n-1) + y(n) + y(n+1) + y(n+2) / (n+1)).

[0231] (3) Single-channel charge calculation

[0232] The single-channel charge calculation formula is:

[0233]

[0234] Where R is the resistance of the electrostatic detection system, t is the time of the calculation taken, which is a variable value, and U(t) is the voltage sampling value at time t.

[0235] (4) Fault signal starting point and ending point identification

[0236] As shown in Figure 6 , the starting point data n1 and the ending point data n2 of the fault signal are marked using the gentle zone determination method, and the steps are as follows:

[0237] a) Calculate the average value of the entire data amplitude as the gentle coefficient;

[0238] b) Divide the data into several equal small sections, and calculate the difference between each point in the small section and the average value of the small section;

[0239] c) Determine whether the difference between the average values of the small sections is less than the gentle coefficient. If it is less than the gentle coefficient, it is a gentle zone, otherwise it is a non-gentle zone, and the starting point data n1 and the ending point data n2 of the fault signal are marked.

[0240] (5) Effective channel signal processing calculation

[0241] The single effective channel fault signal uses the root mean square value calculation, and the formula is

[0242]

[0243] Where n1 is the starting point data of the fault signal, n2 is the ending point data of the fault signal, i is the data variable parameter, and Q i (t) is the electric quantity data of the i-th sampling point.

[0244] The formula for calculating all effective channel fault signals is

[0245]

[0246] The average value of the root mean square value of the effective fault signal is used as an index to determine the division of the fault degree of the particles. The root mean square value starts from 0V, and each increase of 1V increases the fault degree by one level, with a maximum of 10V, and a total of ten levels of fault degree.

[0247] The other parts of this embodiment are the same as any one of the above-mentioned embodiments 1-3, and thus will not be described again.

[0248] The above is only the preferred embodiment of the present application, and does not limit the present application in any form. Any simple modification or equivalent change of the above embodiment according to the technical essence of the present application falls within the protection scope of the present application.

Claims

1. An aircraft engine gas path working fluid detection system, characterized by, It comprises engine tail jet device (1), electrostatic sensor (2), high temperature resistant shielded cable (3), signal conversion device (4), multi-channel high-speed acquisition device (5), data processing terminal (6); The electrostatic sensor (2) is installed on the engine tail jet device (1) and connected with the signal conversion device (4) through the high temperature resistant shielded cable (3), for outputting the collected abnormal particle electrostatic signal to the signal conversion device (4); The signal conversion device (4) is connected with the multi-channel high-speed acquisition device (5) through the high temperature resistant shielded cable (3), for converting the abnormal particle electrostatic signal obtained from the electrostatic sensor (2) into induced voltage signal and outputting to the multi-channel high-speed acquisition device (5); The data processing terminal (6) is connected with the multi-channel high-speed acquisition device (5), for processing the induced voltage signal obtained from the multi-channel high-speed acquisition device (5) and calculating the root mean square value of the abnormal electrostatic signal to judge the fault degree of the abnormal particle; The signal conversion device (4) comprises power supply circuit, signal pickup circuit and signal amplification filter circuit; The signal amplification filter circuit comprises adder, first high-pass filter, fourth-order Butterworth low-pass filter and follower; The adder comprises amplifier U2, resistor R18 and capacitor C12; The first high-pass filter comprises capacitor C6 and resistor R37; The fourth-order Butterworth low-pass filter comprises first two-order voltage-controlled power supply low-pass filter and second two-order voltage-controlled power supply low-pass filter connected in sequence; The first two-order voltage-controlled power supply low-pass filter comprises amplifier U2, resistor R19, resistor R20, resistor R21, resistor R22, capacitor C7 and capacitor C8; The second two-order voltage-controlled power supply low-pass filter comprises amplifier U2, resistor R25, resistor R26, resistor R23, resistor R24, capacitor C9 and capacitor C10; The follower comprises amplifier U2 and capacitor C11; Pin 2 of the amplifier U2 is connected with resistor R14, resistor R15, resistor R16, resistor R17 and resistor R18; Pin 11 of the amplifier U2 is connected with power supply VCC- and grounded capacitor C12; Pin 1 of the amplifier U2 is connected with resistor R18 and capacitor C6; Pin 5 of the amplifier U2 is connected with grounded capacitor C7, resistor R19 and resistor R20 connected in series with each other; Pin 6 of the amplifier U2 is connected with resistor R21 and resistor R22; Pin 7 of the amplifier U2 is connected with capacitor C8, resistor R22 and resistor R25; Pin 12 of the amplifier U2 is connected with resistor R26 and grounded capacitor C9; Pin 13 of the amplifier U2 is connected with resistor R23 and resistor R24; Pin 14 of the amplifier U2 is connected with capacitor C10 and pin 10 of the amplifier U2; Pin 4 of the amplifier U2 is connected with power supply VCC+ and grounded capacitor C11; Pin 8 of the amplifier U2 is connected with pin 9 of the amplifier U2 and multi-channel high-speed acquisition device (5).

2. An aircraft engine gas path working fluid detection system as claimed in claim 1, wherein, The signal conversion device (4) comprises a power supply circuit, a signal pickup circuit and a signal amplification filter circuit; The power supply circuit is connected with the signal amplification filter circuit, and is used for taking the generated positive power supply VCC+ and negative power supply VCC- as the working voltage of the signal amplification filter circuit; The signal pickup circuit is connected with the electrostatic sensor (2) and the signal amplification circuit, and is used for converting the abnormal electrostatic signal acquired from the electrostatic sensor (2) into an induced voltage signal and outputting to the signal amplification filter circuit; The signal amplification filter circuit is connected with the multi-channel high-speed acquisition device (5), and is used for outputting the amplified and filtered induced voltage signal to the multi-channel high-speed acquisition device (5) for acquisition.

3. An aircraft engine gas path working fluid detection system as claimed in claim 2, wherein, The signal amplification filter circuit comprises a first parallel amplification circuit; The first parallel amplification circuit comprises an amplifier U1, resistors R6, R7, R8, R9, R10, R11, R12, R13, R14, R15, R16, R17, capacitors C4 and C5; Pin 3 of the amplifier U1 is connected with pins 5, 10 and 12 of the amplifier U1; Pin 2 of the amplifier U1 is connected with resistors R6 and R10; Pin 1 of the amplifier U1 is connected with resistors R10 and R14; Pin 4 of the amplifier U1 is connected with the power supply VCC+ and the grounded capacitor C4; Pin 6 of the amplifier U1 is connected with resistors R7 and R11; Pin 7 of the amplifier U1 is connected with resistors R11 and R15; Pin 9 of the amplifier U1 is connected with resistors R8 and R12; Pin 8 of the amplifier U1 is connected with resistors R12 and R16; Pin 13 of the amplifier U1 is connected with resistors R9 and R13; Pin 14 of the amplifier U1 is connected with resistors R13 and R17; Pin 11 of the amplifier U1 is connected with the power supply VCC- and the grounded capacitor C5; The resistors R14, R15, R16 and R17 are connected with the multi-channel high-speed acquisition device (5).

4. An aircraft engine gas path working fluid detection system as recited in claim 1 wherein, The signal amplification filter circuit further comprises a first inverting amplifier, a second high-pass filter, a third second-order Butterworth low-pass filter, a second inverter, a first-order active low-pass filter circuit and a third high-pass filter; The first inverting amplifier comprises an amplifier U3, resistors R27 and R28 and a capacitor C13; The second high-pass filter comprises a resistor R38 and a capacitor C14; The third second-order Butterworth low-pass filter comprises an amplifier U3, resistors R29, R30, R31 and R32, capacitors C15 and C16; The second inverter comprises an amplifier U3, a capacitor C17, resistors R33 and R34 and a capacitor C18; The first-order active low-pass filter circuit comprises an amplifier U3, a resistor R35, capacitors C19 and C20; The third high-pass filter comprises a resistor R36 and a capacitor C21. Pin 13 of the amplifier U3 is connected with pin 8 of the amplifier U2, the resistance R28, the capacitor C13 and the resistance R27 in series with each other; Pin 14 of the amplifier U3 is connected with the resistance R28 and the capacitor C14; One end of the resistance R38 is connected between the capacitor C14 and the resistance R29, and the other end is connected with the ground; Pin 10 of the amplifier U3 is connected with the capacitor C15 grounded, the resistance R29 and the resistance R30 in series with each other; Pin 9 of the amplifier U3 is connected between the resistance R31 and the resistance R32 grounded in series with each other; Pin 8 of the amplifier U3 is connected with the capacitor C16, the capacitor C17 and the resistance R32; Pin 6 of the amplifier U3 is connected with the resistance R34, the capacitor C17 and the resistance R33 in series with each other; Pin 11 of the amplifier U3 is connected with the power supply VCC- and the capacitor C18 grounded; Pin 7 of the amplifier U3 is connected with the resistance R34 and the resistance R35; Pin 3 of the amplifier U3 is connected with the resistance R35 and the capacitor C19 grounded; Pin 4 of the amplifier U3 is connected with the power supply VCC+ and the capacitor C20 grounded; The capacitor C21 is connected between pin 1 of the amplifier U3 and the multi-channel high-speed acquisition device (5); One end of the resistance R36 is connected between the capacitor C21 and the multi-channel high-speed acquisition device (5), and the other end is connected with the ground.

5. An aircraft engine gas path working fluid detection system as recited in claim 1 wherein, The signal pickup circuit comprises the resistance R1, the capacitor C1, the resistance R2, the diode D1 and the diode D2; One end of the resistance R1 is connected with the electrostatic sensor (2), and the other end is connected with the signal amplification and filtering circuit; The capacitor C1, the resistance R2, the diode D1 and the diode D2 are connected in parallel with each other, one end is connected between the resistance R1 and the input end of the signal amplification and filtering circuit, and the other end is connected with the ground.

6. An aircraft engine gas path working fluid detection system as recited in claim 1 wherein, The power supply circuit comprises the triode D3, the capacitor C22, the capacitor C23 and the triode D4; One end of the triode D3 is connected with the power supply VCC+, and the other end is connected with the signal amplification and filtering circuit; One end of the triode D4 is connected with the power supply VCC-, and the other end is connected with the signal amplification and filtering circuit; One end of the capacitor C22 is connected between the triode D3 and the signal amplification and filtering circuit, and the other end is connected with the ground; One end of the capacitor C23 is connected between the triode D4 and the signal amplification and filtering circuit, and the other end is connected with the ground.

7. An aero-engine gas path working medium detection system according to any one of claims 1 to 3, characterized in that, The electrostatic sensor (2) is provided in multiple.

8. An aeroengine gas path working fluid detection method, characterized in that, The method comprises the following steps: Step 1: The electrostatic sensor (2) collects abnormal electrostatic signals, and converts the abnormal electrostatic signals into induced voltage signals in the signal conversion device (4); Step 2: The multi-channel high-speed acquisition device (5) collects the converted induced voltage signals and outputs them to the data processing terminal (6); Step 3: The data processing terminal (6) judges the range of the obtained induced voltage signals and labels the validity of the induced voltage signals; Step 4: The induced voltage signals with validity are processed by the rolling mean filtering method to remove the direct current components; Step 5: The charge quantity of the induced voltage signals processed in step 4 is calculated to obtain the voltage sampling signal at the current time. Step 6: the voltage sampling signal obtained in step 5 is marked to obtain the start data n1 and the end data n2 of the voltage sampling value at the current time; Step 7: the root mean square value of the voltage sampling signal at the current time is calculated according to the start data n1 and the end data n2 obtained in step 6, and the fault degree of the abnormal particle is judged according to the size of the root mean square value of the voltage sampling signal; The specific operation of the step 3 is that the data processing terminal (6) judges the range of the obtained induced voltage signal, judges whether the obtained induced voltage signal is less than 10v, if yes, it is judged that the induced voltage signal has validity, if not, it is judged whether there are continuous multiple induced voltage signals of 10V, if yes, it is judged that the induced voltage signal does not have validity, if not, it is judged that the induced voltage signal has validity.

9. A method of detecting a working fluid in a gas path of a gas turbine engine as recited in claim 8, wherein, The step 6 specifically includes the following steps: Step 61: calculate the average value of the amplitude of the voltage sampling signal obtained in step 5, and take the average value of the amplitude of the voltage sampling signal as the flatness coefficient; Step 62: divide the voltage sampling signal into several equal small segments, and calculate the difference between each point in the current small segment and the average value of the current small segment; Step 63: judge whether the difference between the average value of the current small segment is less than the flatness coefficient, if less than, it is a flat area, otherwise it is a non-flat area, and the start data n1 and the end data n2 of the voltage sampling signal at the current time.

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