CN113125512A

CN113125512A - Equipment for monitoring damage of fiber winding layer

Info

Publication number: CN113125512A
Application number: CN202110535342.3A
Authority: CN
Inventors: 高阳; 轩福贞; 董富贵; 凌小峰; 汪楠; 兰程; 闫亚兵; 温建锋; 梅志宇; 张颢出
Original assignee: East China University of Science and Technology
Current assignee: East China University of Science and Technology
Priority date: 2021-05-17
Filing date: 2021-05-17
Publication date: 2021-07-16

Abstract

The invention discloses a device for monitoring damage of a fiber winding layer, which comprises: a current source for providing an excitation current; a plurality of electrodes distributed at the edge of the fiber winding layer and connected with the fiber winding layer, wherein one of the plurality of electrodes is grounded to be used as a grounding electrode; the current electrode gating switch is arranged between the current source and the plurality of electrodes on the fiber winding layer and is used for gating a pair of adjacent electrodes except the grounding electrode in the plurality of electrodes as excitation electrodes to be connected with the excitation current; and the voltage electrode gating switch is arranged between the upper computer and the plurality of electrodes on the fiber winding layer and is used for gating the electrodes except the exciting electrode in the plurality of electrodes so as to output a response signal responding to the exciting current to the upper computer.

Description

Equipment for monitoring damage of fiber winding layer

Technical Field

The invention relates to the field of damage detection of vehicle-mounted hydrogen storage cylinders, in particular to equipment for monitoring damage of a fiber winding layer.

Background

In recent years, with the development of markets, the number of various types of automobiles in China is increased sharply, and a large amount of automobile exhaust emission becomes an important factor of urban environmental pollution.

In order to effectively deal with air pollution caused by automobile emission, from the beginning of the twentieth century, humans began to explore hydrogen fuels that utilize zero emission. By the beginning of the twenty-first century, hydrogen fuel cell vehicles have seen unprecedented development as an important member of the new energy vehicle family. The hydrogen energy is taken as a zero-carbon energy source, has a series of advantages of rich sources, cleanness, environmental protection, high combustion value, no pollution, storage and transportation and the like, and is known as a secondary energy source with the most development potential in the 21 st century.

The hydrogen energy utilizes a complete chain to comprise production, storage, transportation, application and the like, and the key for determining whether the hydrogen energy is widely applied is a safe and reliable hydrogen storage technology. The vehicle-mounted hydrogen storage technology mainly comprises high-pressure gaseous hydrogen storage, low-temperature liquid hydrogen storage, solid hydrogen storage and organic liquid hydrogen storage. In the process of storing hydrogen, as the hydrogen is colorless and odorless, the lung is anoxic after the hydrogen is inhaled by a human body, and the hydrogen is combustible and explosive, the safety of the vehicle-mounted hydrogen storage winding gas cylinder is very important in the development and popularization stages of new energy automobiles.

In the prior art, in order to ensure the safety and reliability of the hydrogen storage wound gas cylinder during use, the commonly used detection technologies include a series of composite material nondestructive detection technologies including ultrasonic detection, ray detection, laser detection and the like. Although the technologies are mature, the detection technologies can only be used for intermittent detection, and the damage condition of the hydrogen storage wound gas cylinder cannot be monitored in real time.

Disclosure of Invention

The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

As described above, common nondestructive testing technologies for composite materials in the prior art, such as ultrasonic testing technology, ray testing technology, laser testing technology, and the like, are suitable for intermittent testing, and cannot perform continuous and uninterrupted real-time testing on the vehicle-mounted hydrogen storage wound gas cylinder.

In order to solve the problems in the prior art, the invention provides a device for monitoring damage of a fiber winding layer, which comprises: a current source for providing an excitation current; a plurality of electrodes distributed at the edge of the fiber winding layer and connected with the fiber winding layer, wherein one of the plurality of electrodes is grounded to be used as a grounding electrode; the current electrode gating switch is arranged between the current source and the plurality of electrodes on the fiber winding layer and is used for gating a pair of adjacent electrodes except the grounding electrode in the plurality of electrodes as excitation electrodes to be connected with the excitation current; and the voltage electrode gating switch is arranged between the upper computer and the plurality of electrodes on the fiber winding layer and is used for gating the electrodes except the exciting electrode in the plurality of electrodes so as to output a response signal responding to the exciting current to the upper computer. The device for monitoring the damage of the fiber winding layer is used for realizing real-time detection of the vehicle-mounted hydrogen storage winding gas cylinder.

In one embodiment, the current electrode gating switch gates all adjacent electrodes except the ground electrode in turn to apply the excitation current, and the voltage electrode gating switch gates the remaining electrodes except the excitation electrode in turn to obtain a potential difference signal between the remaining electrodes responding to the excitation current and the ground electrode as one frame of electrical impedance data of the response signal, corresponding to each pair of adjacent electrodes being excited.

In one embodiment, the apparatus for monitoring damage to the filament wound layer further comprises a differential amplification circuit connected to the plurality of electrodes on the filament wound layer via the voltage electrode gating switch to amplify the collected potential difference signal.

Furthermore, the differential amplifying circuit is provided with two wires for voltage acquisition, wherein one wire is connected with the voltage electrode gating switch, and the other wire is connected with the grounding electrode on the fiber board to realize relative common grounding.

In an embodiment, the apparatus for monitoring damage to filament wound layers further comprises an inverse adder circuit and an inverter circuit for applying a dc voltage on the potential difference signal to obtain a unipolar sinusoidal voltage and inverting the unipolar sinusoidal voltage back to the original phase.

In an embodiment, the apparatus for monitoring damage to a filament wound layer further comprises a low pass filter, the inverter circuit being coupled to the low pass filter to reduce noise interference with the collected potential difference signal.

In one embodiment, the apparatus for monitoring damage to the filament winding layer further comprises a microcontroller, the low pass filter is connected to the microcontroller for analog-to-digital converting the potential difference signal, and the converted digital signal of the potential difference signal is uploaded to the upper computer to generate an electrical impedance tomography map of the filament winding layer.

In one embodiment, the apparatus for monitoring damage to the filament winding further comprises a microcontroller coupled to the current electrode gating switch and the voltage electrode gating switch to control the opening and closing of the current electrode gating switch and the voltage electrode gating switch.

Further, the microcontroller employs a microcontroller of the STM32F103 series.

In one embodiment, the current source uses an AD5933 chip to generate a bipolar sinusoidal current as a current, and a voltage-controlled current source circuit is further disposed between the current source and the current electrode gating switch to stably output the bipolar sinusoidal current.

In an embodiment, the apparatus for monitoring damage to a filament wound layer further comprises the upper computer for generating an electrical impedance tomography map of the filament wound layer based on the response data.

The invention provides equipment for monitoring damage of a fiber winding layer. Acquiring the boundary voltage of the fiber winding layer and uploading the voltage signal to an upper computer to obtain an electrical impedance tomography image of the fiber winding layer. Compared with the detection equipment such as common laser detection, ultrasonic detection and the like, the detection equipment provided by the invention is simple, is convenient and fast to operate, and is easier to arrange at a mobile end for real-time monitoring.

By observing the real-time electrical impedance tomography image, the user can continuously monitor the conductivity of each part of the winding layer of the vehicle-mounted hydrogen storage cylinder. When the fiber winding layer of the vehicle-mounted hydrogen storage cylinder is damaged by interface stripping, matrix cracking, fiber fracture, delamination and the like, the local conductivity of the winding layer of the cylinder is abnormal, and the abnormal condition can be directly displayed in an electrical impedance tomography image.

Drawings

The above features and advantages of the present disclosure will be better understood upon reading the detailed description of embodiments of the disclosure in conjunction with the following drawings. In the drawings, components are not necessarily drawn to scale, and components having similar relative characteristics or features may have the same or similar reference numerals.

FIG. 1 illustrates a connection diagram of an apparatus for monitoring damage to a filament wound layer in some embodiments of the present invention;

FIG. 2 illustrates an electrode identification map of an apparatus for monitoring damage to a filament wound layer in some embodiments of the present invention;

FIG. 3 illustrates a filament winding layer measurement connection diagram for adjacent excitation-common measurement mode of an apparatus for monitoring filament winding layer damage in some embodiments of the present invention;

FIG. 4 shows a prior art filament wound layer measurement connection diagram for the adjacent excitation-adjacent measurement mode of electrical resistance tomography; and

FIG. 5 shows a connection diagram of an apparatus for monitoring damage to filament wound layers in further embodiments of the present invention.

Description of reference numerals:

100: means for monitoring damage to the filament winding layer;

101: a current source;

102: a current electrode gating switch;

103: a voltage electrode gating switch;

104: a fiber winding layer;

105: an upper computer;

1041: an excitation electrode;

1042: a ground electrode;

200: means for monitoring damage to the filament winding layer;

201: a current source;

202: a current electrode gating switch;

203: a voltage electrode gating switch;

205: an upper computer;

206: a microcontroller;

207: a voltage controlled current source;

208: a differential amplifier circuit;

209: an inverse adder;

210: an inverter circuit;

211: a low-pass filter;

1: an electrode 1;

2: an electrode 2;

3: an electrode 3;

4: an electrode 4;

5: an electrode 5;

6: an electrode 6;

7: an electrode 7;

8: an electrode 8;

9: an electrode 9;

10: an electrode 10;

11: an electrode 11;

12: an electrode 12;

13: electrode 13:

14: an electrode 14;

15: an electrode 15; and

16: and an electrode 16.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments. It is noted that the aspects described below in connection with the figures and the specific embodiments are only exemplary and should not be construed as imposing any limitation on the scope of the present invention.

The following description is presented to enable any person skilled in the art to make and use the invention and is incorporated in the context of a particular application. Various modifications, as well as various uses in different applications will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to a wide range of embodiments. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

In the following detailed description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. It will be apparent, however, to one skilled in the art that the practice of the invention may not necessarily be limited to these specific details. In other instances, well-known structures and devices are shown in block diagram form, rather than in detail, in order to avoid obscuring the present invention.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Additionally, the terms "upper," "lower," "left," "right," "top," "bottom," "horizontal," "vertical" and the like as used in the following description are to be understood as referring to the segment and the associated drawings in the illustrated orientation. The relative terms are used for convenience of description only and do not imply that the described apparatus should be constructed or operated in a particular orientation and therefore should not be construed as limiting the invention.

It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, regions, layers and/or sections, these elements, regions, layers and/or sections should not be limited by these terms, but rather are used to distinguish one element, region, layer and/or section from another element, region, layer and/or section. Thus, a first component, region, layer or section discussed below could be termed a second component, region, layer or section without departing from some embodiments of the present invention.

The embodiment provides equipment for monitoring damage of a fiber winding layer, which is used for monitoring damage of the fiber layer of a vehicle-mounted hydrogen storage cylinder in real time. When the fiber layer of the vehicle-mounted hydrogen storage cylinder is damaged in different degrees, the fiber layer of the vehicle-mounted hydrogen storage cylinder can be clearly and visually displayed in an electrical impedance tomography image, so that accidents such as hydrogen leakage and the like which seriously harm personal safety due to the damage of the fiber layer of the vehicle-mounted hydrogen storage cylinder are prevented.

Referring to the drawings, FIG. 1 shows a connection diagram of an apparatus for monitoring damage to filament wound layers in some embodiments of the present invention.

The apparatus 100 for monitoring damage to a filament wound layer in this embodiment generally comprises a current source 101, a plurality of electrodes disposed at the edges of a filament wound layer 104, a current electrode gating switch 102, and a voltage electrode gating switch 103. Of course, the present embodiment does not specifically limit the components of the apparatus 100 for monitoring damage of a fiber winding layer, and corresponding other components may be added according to actual situations on the premise that the functions provided by the present embodiment can be implemented.

As shown in particular in fig. 1, the current source 101 in this embodiment is used to provide the excitation current. In the embodiment, an AD5933 chip is adopted to generate a bipolar sinusoidal current as an excitation current.

The AD5933 is a high-precision impedance measurement chip, and a frequency generator of an AD converter with 12 bits and a sampling rate as high as 1MSPS is integrated inside the high-precision impedance measurement chip. The frequency generator may generate a specific frequency to excite the external resistor, and the response signal obtained from the resistor is sampled by the ADC and subjected to discrete fourier transform by the DSP on chip. The fourier transform is followed by a return of the real value R and the imaginary value I obtained at this output frequency. The phase angles of the fourier transformed modes and resistors at each scanning frequency can thus be easily calculated.

AD5933 has mainly the following properties: the frequency generator is programmable, and the maximum frequency can reach 100 KHz; the device can be used as a device to communicate with a host through an interface, so that frequency scanning control is realized; its frequency resolution is 27 bits (<0.1 Hz); the impedance measurement range is 100 omega to 10M omega; a temperature sensor is arranged in the device, and the measurement error range is +/-2 ℃; with an internal clock; phase measurement can be realized; the system precision is 0.5%; alternative power ranges are 2.7V to 5V; the normal working temperature range is-40 ℃ to +125 ℃; there is a 16-pin SSOP package.

In this embodiment, a plurality of electrodes are provided, which are spaced apart from each other at equal intervals at the edges of the filament winding layer 104 and are connected to the filament winding layer 104. An optional one of the plurality of electrodes is grounded to serve as a grounded electrode 1042.

Referring to fig. 2, fig. 2 illustrates an electrode identification diagram of an apparatus for monitoring damage to a filament wound layer in some embodiments of the present invention. In this embodiment, a part of the filament wound composite material is cut from the fiber layer of the vehicle-mounted hydrogen storage cylinder, and 16 electrodes are distributed and connected to the edge of the cut filament wound composite material. To facilitate the unification of concepts, the subsequent operations performed on the filament wound composite material are unified in this description as operations performed on the filament wound layer 104.

In the embodiment of fig. 2, all of the electrodes are equidistantly distributed at the edge of the filament wound composite material. For ease of understanding, reference numerals are given to each electrode in this embodiment, with all electrodes at the edges of the filament wound layer 104 being numbered one-to-one as in figures 1-16.

With continued reference to fig. 1, as shown in fig. 1, the present embodiment includes a current electrode gating switch 102 and a voltage electrode gating switch 103. The current electrode gating switch 102 is disposed between the current source 101 and the plurality of electrodes on the filament winding layer 104, and is configured to gate a pair of adjacent electrodes of the plurality of electrodes except the ground electrode 1042 as the excitation electrode 1041 to connect the excitation current. The voltage electrode gating switch 103 is disposed between the upper computer 105 and the plurality of electrodes on the filament winding layer 104, and is configured to gate the electrodes except the pair of excitation electrodes 1041 among the plurality of electrodes, so as to output a response signal in response to the applied excitation current to the upper computer 105. The upper computer 105 generates an electrical impedance tomography map of the filament wound layer 104 based on the received response data.

In the device 100 for monitoring damage of the fiber winding layer according to the embodiment, the existing vehicle-mounted hydrogen storage winding gas cylinder is subjected to real-time damage detection by using a resistance tomography technology through a data acquisition mode of adjacent excitation-common ground measurement.

Electrical Resistance Tomography (ERT) technology originates from the medical field, and is a simplified form of the art of Electrical Impedance Tomography (EIT), that is, only real part information of Electrical Impedance is utilized.

In the embodiment of the invention, the electrical resistance tomography technology is applied to the field of damage detection of the vehicle-mounted hydrogen storage cylinder.

The resistance tomography technology can obtain the distribution of the multiphase flow media according to the conductivity distribution of objects in a sensitive field based on the difference of the conductivity among the mediums of the multiphase flow, thereby realizing the visual measurement of the parameters of the multiphase component substances in a closed pipeline or process container device. By injecting current into the material in a crossed manner, the voltage change of the electrode on the surface of the object is measured, and the distribution condition of the punctuation conductivity of the object can be obtained. In general, given an electrode array, there are an infinite number of possible current-voltage combinations, i.e., data acquisition modes, for making measurements.

In the prior art, the main working mode adopted by the electrical resistance tomography technology is the single-layer 16-electrode adjacent excitation-adjacent measurement mode. The excitation signal is a sine wave alternating current signal, and the detection signal is a boundary voltage signal on the adjacent electrode pair. When the conductivity distribution in the field changes, the distribution of the current field changes with it, resulting in a change in the potential distribution in the field and thus in the measured voltage at the field boundaries. The voltage on the boundary is measured and the conductivity distribution in the field can be reconstructed through a corresponding imaging algorithm, so that visual measurement is realized.

However, during the development of electrical resistance tomography, the mode of operation of adjacent excitation-adjacent measurement mainly exposes three problems: (1) since the excitation source and the three adjacent pairs of electrodes are not detected, the obtained boundary voltage data information is insufficient. According to the reciprocity principle, a single layer of 16 electrodes is tested for one circle, and the measured effective data is 104. (2) The excitation current mainly flows through the region near the excitation electrode 1041, which causes the current distribution to be uneven, and the region near the excitation source is very sensitive, thus causing the weighting coefficient of the uneven coal quality to be not easy to be given. (3) The detection electrode end lacks the grounding point, so that the detected data is easily influenced by interference.

In the embodiment of the invention, the data acquisition mode of adjacent excitation-adjacent measurement is applied to the field of damage detection of the vehicle-mounted hydrogen storage cylinder, and is further improved into the data acquisition mode of adjacent excitation-common ground measurement, so that real-time damage detection of the vehicle-mounted hydrogen storage cylinder is realized through a resistance tomography image.

The number of output ports of the current electrode gating switch 102 is equal to the number of electrodes at the edge of the filament winding layer 104. In the present embodiment, since the number of the electrodes disposed at the edge of the filament winding layer 104 is 16, an ADI ADG1206 analog switch is selected as the current electrode gating switch 102.

The ADG1206 is a single-chip iCMOS analog multiplexer, and 16 single channels and 8 differential channels are respectively arranged in the ADG. The ADG1206 switches one of the 16 inputs to a common output according to an address determined by the 4-bit binary address lines a0, a1, a2, and A3. The ADG1206 provides an EN input to enable or disable the device. When disabled, all channels are turned off.

iCMOS is a modular fabrication process that integrates high voltage CMOS (complementary metal oxide semiconductor) and bipolar technologies. By using the process, various high-performance analog ICs with the working voltage of 33V can be developed, and the size which cannot be realized by the conventional high-voltage device can be realized. Unlike analog ICs that use conventional CMOS processes, the CMOS devices can not only withstand high supply voltages, but also improve performance, greatly reduce power consumption, and reduce package size.

In this embodiment, 16 outputs of the current electrode gating switch 102ADG1206 chip are connected to the electrodes on the filament winding layer 104 via alligator clamps.

The number of output ports of the voltage electrode gating switch 103 is equal to the number of electrodes at the edge of the filament winding layer 104. In the present embodiment, since the number of the electrodes disposed at the edge of the filament winding layer 104 is 16, an analog switch of ADG1606 manufactured by ADI corporation is selected as the voltage electrode gating switch 103.

The ADG1606 is a single-chip iCMOS analog multiplexer, and has 16 single channels and 8 differential channels built therein. The ADG1606 switches one of the 16 inputs to a common output based on the address determined by the 4-bit binary address lines A0, A1, A2, and A3. ADG1606 provides an EN input to enable or disable the device. When disabled, all channels are turned off. When the power supply is enabled, the conductivity of each channel in two directions is the same, and the input signal range can be expanded to the power supply voltage range.

Both the ADG1206 and ADG1606 multiplexers have ultra-low capacitance and charge injection characteristics and are therefore ideal solutions for data acquisition and sample-and-hold applications that require low glitch and fast settling times, and both switches have fast switching speeds and high signal bandwidths. The iCMOS architecture ensures very low power consumption, and thus these devices are well suited for portable battery powered meters.

The number of address lines, enable lines and signal output ports of the ADG1606 and ADG1206 are the same. In particular, in order to ensure that the signal is always in a stable state in the process of collecting the voltage signal, no matter the current electrode gating switch 102 or the voltage electrode gating switch 103 is turned on, the time is delayed by 10ms each time, and then the next operation is carried out, so that the continuous on-time selected by each electrode is ensured to be greater than or equal to the AD sampling time.

Before the edges of the filament winding layer 104 are connected to the plurality of electrodes, the filament winding layer 104 is further processed to enhance its conductivity for later collection of response data. In this embodiment, the insulating resin coated on the surface of the filament winding layer 104 is removed by high temperature burning. Then, the carbon fiber surface was cleaned with alcohol. And then coating conductive silver paste on the surface of the carbon fiber to connect the dispersed carbon fibers into a whole. Finally, a conductive copper wire is secured to the wrap carbon fibers 104 with a two-part epoxy to enhance its conductivity.

Turning next to fig. 3, fig. 3 illustrates a filament winding layer measurement connection diagram for adjacent excitation-common ground measurement mode of an apparatus for monitoring filament winding layer damage in some embodiments of the present invention.

In this embodiment, a data acquisition mode of adjacent excitation-common ground measurement is employed. The current electrode gating switch 102ADG1206 gates all adjacent electrodes except the ground electrode 1042 in turn to apply the excitation current.

In the embodiment of fig. 3, 16 electrodes are connected on the edges of the filament winding layer 104. For ease of understanding, each electrode corresponds to a numerical designation from 1-16. Any selected one of all the electrodes on the edge of the filament wound layer 104 is grounded as a grounded electrode 1042. In this embodiment, the electrode 4 is grounded as the grounding electrode 1042. As shown in fig. 1, a current electrode gating switch 102 is connected to a filament winding layer 104. The current electrode gating switch 102 first gates two adjacent electrodes, electrode 1 and electrode 2, of the filament winding layer 104 as the excitation electrode 1041, and applies an excitation current I to the electrode 1 and the electrode 2₁。

For each pair of adjacent electrodes being energized, the voltage electrode gating switch 102 alternately gates the remaining electrodes except the pair of energized electrodes 1041 to obtain a potential difference signal between the remaining electrodes responsive to the energizing current and the determined ground electrode 1042 as a frame of electrical impedance data of the response signal.

In the embodiment of FIG. 3, the

electrodes

1 and 2 are definedTo excite the electrode 1041, after an excitation current is applied thereto, a potential difference between the remaining electrodes other than the electrode 1 and the electrode 2 and the ground electrode 1042 is gated by the voltage electrode gating switch 103, respectively. In this embodiment, the electrode 4 is selected as the ground electrode 1042. I.e. the potential difference V between the collecting electrode 3 and the electrode 4₁Potential difference V between electrode 5 and electrode 4₂… potential difference V between electrode 16 and electrode 4₁₃. Potential difference V₁～V₁₃The potential difference response signals acquired in the first round in response to the excitation current applied to the pair of excitation electrodes 1041, electrode 1 and electrode 2.

In the case where the ground electrode 1042 is the electrode 4, the current electrode gating switch 102 alternately gates a pair of adjacent electrodes other than the ground electrode 1042 electrode 4 as the excitation electrodes 1041. In the present embodiment, the current electrode gate switch 102 switches on the

electrodes

2 and 3 as the excitation electrodes 1041 in the second round in the clockwise direction, and applies the excitation current I thereto₂. At this time, the voltage electrode gate switch 103 gates the potential difference between the remaining electrodes other than the electrode 2 and the electrode 3 and the ground electrode 1042, that is, the potential difference V between the collecting electrode 1 and the electrode 4₁', potential difference V between electrode 5 and electrode 4₂Potential difference V between' … electrode 16 and electrode 4₁₃'. Potential difference V₁’～V₁₃' is the potential difference response signal acquired in the second round in response to the excitation current applied to the pair of

excitation electrodes

1041, 2 and 3.

The order of selection of each pair of excitation electrodes 1041 in each turn is not limited to this embodiment, as long as all electrodes at the edges of the filament winding layer 104 are rotated one by one.

In particular, during the process that the current electrode gate switch 102 selects to alternately turn on the pair of excitation electrodes 1041, the grounding electrode 1042 is always unchanged, or is the electrode 4, and the grounding electrode 1042 cannot apply the excitation current as the excitation electrode 1041.

By analogy, in this embodiment, with the ground electrode 1042 unchanged, applying an excitation current to each pair of excitation electrodes 1041 can obtain 13 potential difference signals in response to the excitation current. In this embodiment, 16 electrodes are provided, and the excitation electrodes 1041 on the edge of the filament winding layer 104 are alternated one by one without changing the grounding electrode 1042, for example, the excitation electrodes 1041 in each round may be the

electrodes

1 and 2, the

electrodes

2 and 3 …, the

electrodes

15 and 16, and the

electrodes

16 and 1, respectively, and 14 rounds may be alternated. During the rotation of the excitation electrodes 1041, the grounding electrode 1042 does not participate in the rotation as the excitation electrode 1041, i.e. the

electrodes

3 and 4, and the

electrodes

4 and 5, which cannot be used as a pair of excitation electrodes 1041, to which the excitation current is applied.

Therefore, in the present embodiment, the data acquisition mode of adjacent excitation-common ground measurement can obtain 182(14 × 13) independent potential measurement values.

By analogy, when N electrodes are provided at the edge of the filament winding layer 104, (N-2) × (N-3) independent potential measurements can be obtained using the data acquisition mode of adjacent excitation-common ground measurements. (N-2) indicates that current excitation of (N-2) rounds was performed for one complete data acquisition. The N electrode adjacent excitation modes should be excited N times, but since the ground electrode 1042 is not excited by current due to the introduction of the ground electrode 1042, the two current excitations related to the ground electrode 1042 in the adjacent excitation modes are not carried out, and only (N-2) current excitations are left. (N-3) represents that (N-3) voltage values are obtained in response to each round of current excitation. Except for 2

excitation electrodes

1041 and 1 grounding electrode 1042 in all the N electrodes, the rest (N-3) electrodes respectively measure potential differences with the grounding electrode 1042, thereby obtaining (N-3) voltage values.

Compared with the data acquisition mode of the adjacent excitation-common ground measurement in the prior art, the data acquisition mode of the adjacent excitation-common ground measurement of the electrical resistance tomography in the embodiment breaks the symmetry between current injection and voltage measurement, and all the measurement values obtained by the adjacent excitation-common ground measurement mode are independent, so that higher resolution can be obtained.

Referring to FIG. 4, FIG. 4 shows a prior art filament winding measurement connection diagram for adjacent excitation-adjacent measurement mode in electrical resistance tomography.

In the embodiment of fig. 4, for a 16 electrode filament wound layer 104, there is symmetry between current injection and voltage measurement using a data acquisition mode of adjacent excitation-adjacent measurement. Because there is no ground electrode 1042 in the adjacent measurement mode, 16 electrodes rotate the excitation electrodes 1041 at the edge of the filament winding layer 104 one by one, for example, each round of excitation electrodes 1041 may be electrode 1 and electrode 2, electrode 2 and electrode 3 …, electrode 15 and electrode 16, and electrode 16 and

electrode

1, and 16 rounds may be rotated. After a pair of excitation electrodes 1041 is determined, the potential difference between the remaining adjacent electrodes is collected. Assuming that the

electrodes

1 and 2 are the excitation electrodes 1041, the current electrode gating switch 102 gates the

electrodes

1 and 2 and applies the excitation current. The voltage electrode gating switch 103 gates the rest of the electrodes except for the electrode 1 and the electrode 2, and collects the potential difference between the electrode 3 and the electrode 4, the potential difference between the electrode 4 and the electrode 5, and the potential difference between the electrode 15 and the electrode 16 of …, wherein the collected potential differences are 13.

208(16 × 13) data were measured for 16 electrodes using the data acquisition mode of adjacent excitation-adjacent measurement, but since the potential difference data in response to each round of excitation current, the remaining electrodes except the excitation electrode 1041 participated in two measurements. When the

electrodes

1 and 2 are the excitation electrodes 1041 as in the above, the potential difference between the

electrodes

3 and 4 and the potential difference between the

electrodes

4 and 5 are collected, wherein the electrode 4 is collected twice. Therefore, the data acquisition mode of adjacent excitation-adjacent measurement measures 104(16 × 13 ÷ 2) independent potential measurement values.

It is apparent that when the same number of electrodes are connected to the edges of the filament wound layer 104, the number of independent potential measurements acquired in the adjacent excitation-common ground measurement mode (182) of the electrical resistance tomography technique in this embodiment is greater than the number of independent potential measurements acquired in the adjacent excitation-adjacent measurement mode (104). Therefore, the electrical resistance tomography generated by the acquired data of the adjacent excitation-common ground measurement mode in the present embodiment possesses higher resolution.

Furthermore, for an actual measurement circuit, the potential difference of the edges of the filament wound layers 104 measured in the common ground measurement mode is larger than the potential difference of the edge potential values measured in the adjacent measurement mode. The signal-to-noise ratio of the measured signal in the co-site measurement mode is greater for the same measurement noise. Generally, a higher signal-to-noise ratio indicates less noise mixed in the signal.

The electrodes in this embodiment are equidistantly disposed at the edge of the filament winding layer 104, so that the voltage signals at each position of the filament winding layer 104 can be collected more conveniently, and it is not easy to measure several potential values in a local area of the filament winding layer 104, and the measured values in other areas are not sufficient, so that a complete image cannot be formed.

With continued reference to fig. 1, the voltage gating switch 103 in this embodiment uploads all of the potential difference signals collected through the adjacent excitation-common ground measurement mode in response to each round of excitation current to the upper computer 105. The upper computer 105 is responsible for processing the acquired potential difference data to obtain an electrical impedance tomography image of the fiber winding layer 104.

Referring to fig. 5, fig. 5 shows a connection diagram of an apparatus for monitoring damage to filament wound layers in further embodiments of the present invention.

The apparatus 200 for monitoring damage to a filament winding layer in the embodiment of fig. 5 mainly comprises an upper computer 205, a microcontroller 206, a current source 201, a voltage controlled current source 207, a current electrode gating switch 202, a voltage electrode gating switch 203, a differential amplification circuit 208, an inverse adder 209, an inverter circuit 210, and a low pass filter 211.

In this embodiment, the current source 201 is still an AD5933 chip, and the current electrode gating switch 202 and the voltage electrode gating switch 203 still employ two multiplexers ADG1206 and ADG 1606.

The microcontroller 206 is a microcontroller of the STM32F103 series. STM32 is a 32-bit microcontroller developed by ST corporation, the core of which is the 32Cortex-M3 microcontroller core of ARMv7 architecture produced by ARM corporation. The microcontroller 206STM32 has various common communication interfaces, such as USART, I2C, SPI, etc. to which a large number of sensors can be connected, and can control a large number of devices.

The voltage-controlled current source 207 is an AD8021 high-speed voltage feedback amplifier from ADI. AD8021 can be used for 16bit resolution systems. AD8021 has low voltage noise and low current noise (typical values are 2.1nV/√ Hz and 2.1pA/√ Hz, respectively), and is the lowest quiescent power supply current (7mA @ + -5V) in the high-speed low-noise operational amplifier products of today. The working voltage range of the AD8021 is wider, is +/-2.25V to +/-12V, and can also adopt a 5V single power supply for power supply, so the power supply is very suitable for high-speed low-power-consumption instruments and meters. The output disable pin may further reduce the quiescent supply current to 1.3 mA. Compared with the similar amplifier, the AD8021 not only has superior technical performance, but also has obvious price advantage and much lower quiescent current. The AD8021 is a high-speed, general-purpose amplifier that is well suited for various gain configurations, and can be used in signal processing links as well as control loops. AD8021 is packaged by adopting standard 8-pin SOIC and MSOP, and the working temperature range is-40 ℃ to +85 ℃.

In the present embodiment, the microcontroller 206STM32F103 is connected to the current source 201AD5933 chip through an I2C bus. The microcontroller 206STM32F103 controls the current source 201AD5933 chip to generate a sine wave with a peak-to-peak value of 2.68V and a frequency of 10KHz as a signal source of the excitation current. The signal source of the excitation current generated by the AD5933 flows into the voltage-controlled current source 207 composed of the AD8021 high-voltage feedback amplifier, and is used for stably outputting the bipolar sinusoidal current of 10KHz and 1mA generated by excitation.

The current electrode gating switch 202 in this embodiment is connected to the microcontroller 206STM32 and the voltage controlled current source 207, respectively. The GPIO port of the microcontroller 206STM32F103 is connected to the current electrode gating switch 202 to control the gating of the 4 input ports of the current electrode gating switch 202ADG 1206. The 16 output ports of the current electrode gating switch 202 are respectively connected to the 16 electrodes on the filament winding layer 104, so that the current outputted from the voltage controlled current source 207 can sequentially flow into the selected excitation electrodes 1041 on each turn of the filament winding layer 104 according to a selected sequence.

The 4 address bits and 1 enable port of the current electrode gating switch 202ADG1206 are controlled by the GPIO port output high-low level of the microcontroller 206STM32F 103. Specifically, 4 GPIO ports of STM32F103 are used to control address selection of ADG 1206. Because ADG1206 has 4 address lines, 0000 ~ 1111, it corresponds 0 ~ 15 switches of output port respectively. STM32 controls ADG1206 to gate two adjacent switches in the output port per pass, injecting excitation current through an alligator clamp connecting two excitation electrodes 1041 on filament winding layer 104. In the adjacent excitation-common ground measurement mode of operation employed in the present embodiment, except that no excitation current is applied to the fixed ground electrode 1042, two adjacent electrodes of the remaining electrodes alternately apply excitation currents, and thus 13 excitation currents are cyclically applied.

The GPIO port of the microcontroller 206STM32F103 is also connected to the voltage electrode strobe switch 203 to control the 4 address bits and 1 enable port of the voltage electrode strobe switch 203ADG 1606. Specifically, 4 GPIO ports of STM32F103 are used to control address selection of ADG 1606. Because ADG1606 also has 4 address lines, 0000 ~ 1111, it also corresponds 0 ~ 15 switches of output port respectively. STM32 controls the switches of 13 electrodes in the output port of ADG1606 except for the grounding electrode 1042 and the two excitation electrodes 1041 in the present round to be switched on and switched off, the electrodes on the fiber winding layer 104 are connected through alligator pliers, and the voltage values of the other electrodes except the grounding electrode 1042 in response to the excitation current of each round are collected in turn.

The number of address lines, enable lines and signal output ports of the ADG1606 and ADG1206 are the same. In particular, in order to ensure that the signal is always in a stable state in the process of collecting the voltage signal, no matter the current electrode gating switch 202 or the voltage electrode gating switch 203 is opened, the time is delayed by 10ms every time, and then the next operation is carried out, so as to ensure that the continuous opening time selected by each electrode is greater than or equal to the AD sampling time.

With continued reference to fig. 5, the apparatus 200 for monitoring damage to a filament wound layer in this embodiment further includes a differential amplifier circuit 208. The differential amplifier circuit 208 in this embodiment is an AD8422 amplifier manufactured by ADI corporation.

Analog Devices AD8422 is a high-precision, low-power, low-noise rail-to-rail instrumentation amplifier. Analog Devices AD8422 processes signals with ultra-low distortion performance, loading does not affect performance over the entire output range. AD8422 has a very low bias current, high source impedance without error, allowing multiplexing of multiple sensors to the input. The low voltage noise and low current noise characteristics make AD8422 an ideal choice for measuring a wheatstone bridge. The AD8422 has robust input protection, can ensure stability, and does not sacrifice noise performance. AD8422 has high ESD suppression capability and continuous voltage input protection up to 40V from the opposite supply rail. The gain can be set to 1 to 1000 by a resistor. The reference pin may be used to apply a precise offset to the output voltage. The rated working temperature range of AD8422 is-40 ℃ to +85 ℃, and a typical performance curve can be ensured at the temperature of 125 ℃. The AD8422 has a total of two packages, 8 pin MSOP and 8 pin SOIC.

In the present embodiment, the differential amplifier AD8422 constituting the differential amplification circuit 208 connects the plurality of electrodes on the filament winding layer 104 via the voltage electrode gate switch 203 to amplify the collected potential difference signal in response to each round of the excitation current.

Two wires for voltage collection are provided in the differential amplifier circuit 208, one of which is connected to the voltage electrode gating switch 203 and the other of which is connected to the ground electrode 1042 on the filament winding layer 104 to achieve a relative common ground. The relatively common ground connection in this embodiment is simple to operate. The potential of the access point relative to the common ground connection is not substantially zero, which has the effect of measuring the potential difference relative to this ground for all the remaining electrodes except the ground electrode 1042 and each excitation electrode 1041.

In another embodiment, the differential amplifier circuit 208 and the ground electrode 1042 on the filament winding layer 104 may both be grounded separately. In this case, the potential of the access point of the two respective grounding modes is zero, which achieves the effect that the absolute voltage is measured, and the relative potential difference between the grounding point and the other electrodes except the grounding electrode 1042 and the excitation electrode 1041 of each round is acquired, but the relative potential difference is the voltage value of the other electrodes.

After the electric potential at two ends controlled by the voltage electrode gating switch 203 is connected to a differential circuit 208 formed by an AD8422 amplifier, the acquired electric potential difference signal is amplified by 20.8 times, and the amplified electric potential difference signal enters an inverse adder 209 and an inverter circuit 210. In this embodiment, the TI OPA2227 operational amplifier is selected to form the inverting adder 209 and the inverter circuit 210.

The OPA2227 operational amplifier has the characteristics of low noise, wide bandwidth, high precision and the like, and is therefore an ideal choice for applications requiring both ac and precision dc performance. OPA2227 has a stable unity gain and has a high slew rate (2.3V/. mu.s) and wide bandwidth (8 MHz). Furthermore, the low quiescent current and low cost make them well suited for portable applications. The OPA2227 series operational amplifier is a pin-to-pin replacement for the industry standard type OP-27, with significant improvements over the entire circuit board. In order to save space and reduce cost per channel, dual channel and four channel versions are also provided. OPA2227 was packaged with DIP-8 and rated for operation in the range of-40 deg.C to 85 deg.C.

In the present embodiment, the amplified potential difference signal is added to the 1.15V dc by the inverse adder 209 in the OPA2227 operational amplifier, so that the overall voltage becomes a unipolar sinusoidal voltage.

Because the input impedance of the same-direction adder is high, signals cannot easily flow into the adder, and the normal use of other paths is influenced. And the input impedance of the inverse adder 209 is low, so that the signal at the input end can flow into the adder more easily without affecting the normal use of other circuits. The inverting adder 209 is thus selected in this embodiment.

To ensure that the front and back phases of the potential difference signal are consistent, the unipolar sinusoidal voltage obtained in the inverting adder 209 is then restored to the original phase by the inverter circuit 210.

Subsequently, the potential difference signal passes through a first order low pass filter 211 constituted by OPA 2227. Low-pass filtering can be simply thought of as: a frequency point is set that cannot pass when the signal frequency is higher than this frequency. In the digital signal, this frequency point is also the cut-off frequency, and when the frequency domain is higher than this cut-off frequency, all values are assigned to 0. Since the low frequency signal is passed through in its entirety during this process, it is called low pass filtering.

In the field of digital image processing, from the aspect of frequency domain, low-pass filtering can perform smooth denoising processing on an image. In this embodiment, the collected potential difference signal data is used to generate an electrical impedance tomography map of the filament wound layer 104. Therefore, the potential difference signal passes through the first order low pass filter 211 formed by OPA2227 to reduce noise interference, and the image is smoothly denoised.

The filtered potential difference signal is returned to the microcontroller 206STM32F103 and AD sampled by an analog to digital converter of the 12 bit successive approximation type of STM32F 103. In this embodiment, the AD clock is 12MHz, and the sampling period is 1.5 periods.

The microcontroller 206STM32 has 1-3 ADCs (the STM32F101/102 series has only 1 ADC), and these ADCs can be used independently, also can use dual mode in order to improve the sampling rate. The ADC of STM32 is a 12-bit successive approximation type analog-to-digital converter. It has 18 channels and can measure 16 external and 2 internal signal sources. The a/D conversion of each channel may be performed in a single, continuous, scanning, or discontinuous mode. The results of the ADC may be stored in a 16-bit data register in either a left-aligned or right-aligned manner.

The converted digital signal of the potential difference signal is continuously uploaded to the upper computer 205 to generate an electrical impedance tomography map of the filament winding layer 104. The upper computer 205 is connected with the microcontroller 206STM32F103 through a Universal Asynchronous Receiver/Transmitter (UART) port to acquire acquired data, and acquires an electrical impedance tomography image by calling an electrical impedance tomography algorithm.

A universal asynchronous receiver-transmitter (UART) transmits bytes of data in bit order. The UART at the other end assembles the bits into bytes. Each UART contains a shift register. Serial communication over one wire or other medium has a lower cost than parallel communication over multiple wires. UARTs do not typically directly generate or receive signals external to other devices. The separate interface device is used to convert the logic level of the signal to the UART. The communication may be simplex, full duplex or half duplex.

In summary, the present invention provides an apparatus for monitoring damage to a filament winding layer. The whole wound layer of the vehicle-mounted hydrogen storage cylinder is taken as a conductor, and the electrode is directly connected with the carbon fiber of the wound layer. When the gas cylinder winding layer is damaged by interface stripping, matrix cracking, fiber fracture, layering and the like, the local conductivity of the gas cylinder winding layer is abnormal. The invention reconstructs the three-dimensional distribution of the conductivity of the winding layer of the gas cylinder by measuring a limited number of boundary voltages so as to discover the internal damage of the winding gas cylinder.

The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An apparatus for monitoring damage to a filament winding layer, comprising:

a current source for providing an excitation current;

the electrodes are distributed at the edge of the fiber winding layer and connected with the fiber winding layer, and one of the electrodes is grounded to be used as a grounding electrode;

a current electrode gating switch disposed between the current source and the plurality of electrodes on the filament winding layer for gating a pair of adjacent electrodes other than the ground electrode among the plurality of electrodes as excitation electrodes to switch in the excitation current; and

and the voltage electrode gating switch is arranged between the upper computer and the plurality of electrodes on the fiber winding layer and is used for gating the electrodes except the exciting electrode in the plurality of electrodes so as to output response signals responding to the exciting current to the upper computer.

2. The apparatus for monitoring damage to an enwound layer of claim 1, wherein said current electrode gating switch alternately gates all adjacent electrodes except said ground electrode to apply an excitation current, and said voltage electrode gating switch alternately gates the remaining electrodes except said excitation electrode to obtain a potential difference signal between the remaining electrodes except said excitation electrode and said ground electrode in response to said excitation current as a frame of electrical impedance data of said response signal, for each pair of adjacent electrodes being excited.

3. The apparatus of claim 2, further comprising a differential amplification circuit connecting the plurality of electrodes on the filament winding via the voltage electrode gating switch to amplify the collected potential difference signal.

4. The apparatus for monitoring damage to a filament winding according to claim 3 wherein the differential amplifier circuit has two wires for voltage acquisition, one of which is connected to the voltage electrode gating switch and the other of which is connected to the ground electrode on the fiber board for relative common ground.

5. The apparatus for monitoring damage to filament wound layers according to claim 3 further comprising an inverse adder circuit and an inverter circuit for applying a DC voltage on said potential difference signal to obtain a unipolar sinusoidal voltage and inverting said unipolar sinusoidal voltage back to an original phase.

6. The apparatus for monitoring damage to filament wound layers of claim 5 further comprising a low pass filter, wherein said inverter circuit is coupled to said low pass filter to reduce noise interference with said collected potential difference signal.

7. The apparatus according to claim 6, further comprising a microcontroller, wherein the low pass filter is connected to the microcontroller for analog-to-digital converting the potential difference signal, and the converted digital signal of the potential difference signal is uploaded to the upper computer for generating an electrical impedance tomography map of the filament wound layer.

8. The apparatus for monitoring damage to an enwound layer of claim 1, further comprising a microcontroller coupled to the current electrode gating switch and the voltage electrode gating switch to control the opening and closing of the current electrode gating switch and the voltage electrode gating switch.

9. The apparatus for monitoring damage to filament wound layers according to claim 7 or 8, wherein said microcontroller is a microcontroller of the STM32F103 series.

10. The apparatus for monitoring damage to filament winding layer according to claim 1, wherein the current source uses AD5933 chip to generate bipolar sinusoidal current as the excitation current, and a voltage-controlled current source circuit is further disposed between the current source and the current electrode gating switch to stably output the bipolar sinusoidal current.

11. The apparatus for monitoring damage to a filament wound layer of claim 1 further comprising said host computer for generating an electrical impedance tomography map of said filament wound layer based on said response data.