KR20230057592A - Welding inspection system and methods of welding inspection using eddy current - Google Patents

Abstract

The present invention relates to a welding condition inspection system that improves an ability to distinguish between weak welds and normal welds, comprising: an inspection part including a first sensor that irradiates a primary magnetic field to a welding part of a battery cell and a second sensor that detects an eddy current signal induced by the first sensor; and a data processing part that collects the eddy current signal detected by the inspection part and evaluates the welding state of the battery cell weld part, wherein a sinusoidal wave is input to the first sensor, and the data processing part determines the welding state of the welding part based on the amplitude of the eddy current signal.

Description

Welding condition inspection system and inspection method using eddy current {WELDING INSPECTION SYSTEM AND METHODS OF WELDING INSPECTION USING EDDY CURRENT}

The present invention relates to a system and method for inspecting the welding state of a welded portion of a battery cell, and relates to an inspection system and method capable of determining whether a welded portion is normal, cosmetic, or weakly welded using eddy current. will be.

As the price of energy sources rises due to the depletion of fossil fuels and interest in environmental pollution increases, the demand for eco-friendly alternative energy sources becomes an indispensable factor for future life. In particular, technology development for mobile devices As the demand for secondary batteries as an energy source increases, the demand for secondary batteries is rapidly increasing.

Typically, in terms of battery shape, there is a high demand for prismatic secondary batteries and pouch-type secondary batteries that can be applied to products such as mobile phones with a thin thickness, and in terms of materials, lithium ion batteries with high energy density, discharge voltage, and output stability, lithium Demand for lithium secondary batteries such as ion polymer batteries is high.

Secondary batteries are also classified according to the structure of the positive electrode, the negative electrode, and the electrode assembly of the separator structure interposed between the positive electrode and the negative electrode. Typically, long sheet-type positive electrodes and negative electrodes are wound with a separator interposed therebetween. A jelly-roll (wound type) electrode assembly in one structure, a stack type (laminated type) electrode assembly in which a plurality of cathodes and anodes cut in units of a predetermined size are sequentially stacked with a separator interposed therebetween, anodes and cathodes in a predetermined unit and a stack-folding type electrode assembly having a structure in which unit cells such as a bi-cell or a full cell are stacked with a separator interposed therebetween.

Such a battery may be provided with a structure in which an electrode assembly is embedded in a battery case. The battery may include electrode terminals configured by welding electrode tabs protruding from the electrode current collector to electrode leads.

At this time, if a process such as welding is not normally performed in the tab-lead connection area of the battery, current may flow abnormally, or electrical connection may become unstable due to shock or vibration applied to the battery, and in severe cases, the electrode tab and the electrode lead can be separated.

Therefore, in inspecting the welding state of the welded part in the tab-lead connection area of the battery, a method for distinguishing cosmetic welding and weak welding from normal welding is required.

Korean Patent Registration No. 2023739 discloses a technology for detecting cracks using eddy currents. The above document is for nondestructively detecting cracks, and can detect a non-welding state, but has limitations in detecting weak welding.

Korea Patent No. 2023739

The present invention is to solve the above problems, and to provide a welding condition inspection system and inspection method for improving the detection power of weak welding.

A welding state inspection system according to the present invention includes a first sensor for irradiating a primary magnetic field to a welded portion of a battery cell and a second sensor for detecting an eddy current signal induced by the first sensor; And a data processing unit that collects the eddy current signal detected by the inspection unit and evaluates the welding state of the battery cell welding part, wherein the first sensor receives a sine wave, and the data processing unit determines the welding part based on the amplitude of the eddy current signal. Assess the welding condition.

In one embodiment of the present invention, the sine wave may be a sine wave.

In one embodiment of the present invention, the frequency of the sinusoidal wave is 100 to 1000 Hz.

In one embodiment of the present invention, the first sensor and the second sensor are arranged to face each other on the top and bottom of the welded portion of the battery cell.

In one embodiment of the present invention, the first sensor and the second sensor are spaced apart from the welding part of the battery cell by a predetermined distance, and are configured to move along a set travel path and perform eddy current inspection in a non-contact state with the welding part.

In one embodiment of the present invention, the first sensor includes a transmission coil for irradiating a primary magnetic field to a welded portion, and the second sensor is a secondary magnetic field radiated by an eddy current generated by the welded portion by the primary magnetic field. and a receiving coil for receiving and generating electromotive force.

In one embodiment of the present invention, the data processing unit determines normal welding/weak welding/non-welding of the welded part through the shape, symmetry, and area of a graph plotting the amplitude of the eddy current signal.

In one embodiment of the present invention, weak or cosmetic welds are determined by comparison with normal weld data.

The welding state inspection method of the present invention uses a first sensor for irradiating a primary magnetic field on a welded portion of a battery cell and a second sensor for detecting an eddy current signal induced by the first sensor to check the welding state of a welded portion of a battery cell. As a method of inspection, a sine wave having a frequency in a predetermined range is input to the first sensor, and the normal welding / weak welding / beauty of the welded part through the shape, symmetry and area of a graph plotted with the amplitude of the eddy current signal judge the fold

In one embodiment of the present invention, the first sensor and the second sensor perform eddy current inspection along a set driving path in a non-contact state at a position spaced apart from the battery cell welding part.

In one embodiment of the present invention, the frequency of the sinusoidal wave is 100 to 1000 Hz.

The welding state inspection system and the welding state inspection method of the present invention can distinguish between weak welding and normal welding, and thus have an improved ability to detect weak welding.

1 is a schematic diagram of an inspection system according to an embodiment of the present invention.
2 is a view showing how the eddy current sensor of the present invention performs an inspection.
3 to 6 are amplitude graphs of eddy current signals according to embodiments.
7 to 10 are amplitude graphs of eddy current signals according to comparative examples.

Since the present invention may have various changes and various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, it should be understood that this is not intended to limit the present invention to the specific disclosed form, and includes all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

In this application, the terms "include" or "have" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that it does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof. In addition, when a part such as a layer, film, region, plate, etc. is said to be "on" another part, this includes not only the case where it is "directly on" the other part, but also the case where another part is present in the middle. Conversely, when a part such as a layer, film, region, plate, etc. is said to be "under" another part, this includes not only the case where it is "directly under" the other part, but also the case where there is another part in between. In addition, in the present application, being disposed "on" may include the case of being disposed not only on the top but also on the bottom.

Hereinafter, a welding state inspection system according to the present invention will be described in detail.

1 is a schematic diagram of a system for inspecting a welding state of a battery cell according to an embodiment of the present invention. Referring to Figure 1, the inspection system 100 of the present invention, a first sensor 111 for irradiating a primary magnetic field to the welding portion (A) of the battery cell and detecting the eddy current signal induced by the first sensor Inspection unit 100 including a second sensor 112; and a data processing unit 120 that collects the eddy current signal detected by the inspection unit 100 and evaluates the welding state of the battery cell welding part.

The inspection system of the present invention uses an eddy current sensor to non-destructively inspect a welded part included in a battery cell, a sinusoidal wave is input to the eddy current sensor, and the welding state is determined based on the amplitude of the eddy current signal collected by the eddy current sensor. Determine

In a conventional system or method for inspecting the welding state of a welded part using eddy current, the welding state is evaluated based on a phase difference of an eddy current signal received by an eddy current sensor. However, this method can detect welding defects due to cosmetic welding, but has a disadvantage in that it is difficult to distinguish welding defects caused by weak welding from normal welding.

In the present invention, a sine wave having a frequency of a specific range is input to a first sensor, the first sensor applies a sine wave of a specific frequency to a welding part of a battery cell, and a second sensor receives an eddy current signal induced by the first sensor. and the data processing unit analyzes the waveform data of the eddy current signal detected by the second sensor to determine whether the welding state of the welding part is normal welding, weak welding, or non-welding.

Compared to the method of evaluating the welding state based on the phase difference of the eddy current signal, the inspection system of the present invention, which determines the welding quality of the welded part based on the amplitude of the eddy current signal, accurately distinguishes between normal welding and weak welding. It works.

In one specific example, the sine wave input to the first sensor may be a sine wave, and the frequency of the sine wave is 100 to 1000 Hz. In the present invention, when the numerical range is less than 100 Hz, the inspection speed may be too slow, and conversely, when it exceeds 1000 Hz, the detecting power of weak welding may be degraded, which is not preferable.

In the inspection system of the present invention, the battery cell welded portion to be inspected may be an electrode current collector, an electrode tab, or an electrode lead included in the battery cell, or a connection area where the electrode current collector, the electrode tab, or the electrode lead are connected to each other. etc. Specifically, as shown in FIG. 1, a tab-lead connection area (A) in which an electrode tab 11 protruding from an electrode current collector and an electrode lead 12 engaged in an electrical terminal of an external device are connected to each other by welding or the like. can be

2 is a view showing how the eddy current sensor of the present invention performs an inspection. Referring to FIG. 2, the first sensor 111 and the second sensor 112 are welded to the battery cell 10 (A ) are disposed facing each other at the top and bottom of the At this time, the first sensor 111 and the second sensor 112 are separated by a predetermined distance from the welded portion A of the battery cell. Specifically, the first sensor 111 is spaced apart from the welded portion A in an upward direction by a predetermined distance, and the second sensor 112 is spaced apart from the welded portion A downward by a predetermined distance. Further, the first sensor 111 and the second sensor 112 are configured to move while maintaining a non-contact state with the welded portion along a predetermined travel path (dotted line) within the region of the welded portion. In this way, the first sensor and the second sensor induce eddy currents, sense the induced eddy current signals, and perform eddy current inspection while moving on the welded portion along the travel path.

In the inspection system of the present invention, the welding state is determined based on the amplitude of the eddy current signal, and the detection target welding portion must be located between the first sensor and the second sensor to be able to determine based on the amplitude. That is, it is difficult to implement the present invention with an eddy current sensor in which both the first sensor and the second sensor are positioned on the upper surface of the welded part or both the first sensor and the second sensor are positioned on the lower surface of the welded part.

In one specific example, the first sensor 111 includes a transmission coil (not shown) for irradiating a primary magnetic field to the welded portion A, and the second sensor 112 is configured to transmit a primary magnetic field to the welded portion A. (A) includes a receiving coil (not shown) for receiving a secondary magnetic field radiated by the eddy current generated and generating an electromotive force.

The transmitting coil and the receiving coil may be provided in a cylindrical shape, a rectangular columnar shape, or a polygonal columnar shape, respectively, and may have a wire wound shape such that a magnetic field is generated in a longitudinal direction of the transmitting coil and the receiving coil.

The data processing unit 120 determines normal welding/weak welding/non-welding of the welding part through the shape, symmetry, and area of a graph plotting the amplitude of the eddy current signal.

The data processing unit 120 may store eddy current signals detected while the first sensor and the second sensor move along a predetermined driving path, and plot the amplitude of the eddy current signal according to the length of the moving path ( plotting) can be done.

Referring to FIG. 2 , the first sensor 111 and the second sensor 112 move along the dotted line on the weld A and perform an inspection by eddy current. The eddy current signal can be detected in real time from the point B to the point E where the inspection ends, and sent to the data processing unit. Accordingly, the data processing unit may plot the amplitude of the eddy current signal according to the length of the welded portion.

In general, a graph in which the amplitude of the eddy current signal is plotted forms a “U” shape and is symmetrical when the welded portion A is normally welded. On the other hand, when there is a non-welded portion in a part of the weld A, the amplitude of the eddy current signal changes in the non-welded portion compared to normal welding, so that the open shape of the graph is not symmetrical.

On the other hand, when the welding part is a weak welding, in the graph remodeling, it may have a symmetrical “U” shape like normal welding, but since the value of the amplitude increases as a whole, the internal area of the “U” shape is reduced.

As described above, according to the present invention, cosmetic welding and weak welding can be distinguished from normal welding through the shape, symmetry, and area of the graph plotting the amplitude of the eddy current signal, and the detectability of the weak welding is improved.

A battery cell to be inspected by the inspection system of the present invention may have a structure in which an electrode assembly having a structure in which a positive electrode, a separator, and a negative electrode are alternately stacked is accommodated in a battery case. The positive and negative electrodes each have a structure in which an active material layer is formed through a drying and rolling process after an electrode slurry containing an electrode active material is applied to a current collector. When the electrode assembly is accommodated in the battery case, a battery cell may be manufactured by injecting an electrolyte into the battery case and sealing the battery case.

Here, the current collector may be a positive electrode current collector or a negative electrode current collector, and the electrode active material may be a positive electrode active material or a negative electrode active material. In addition, the electrode slurry may further include a conductive material and a binder in addition to the electrode active material.

In the present invention, the cathode current collector is generally made to have a thickness of 3 to 500 μm. The positive electrode current collector is not particularly limited as long as it does not cause chemical change in the battery and has high conductivity. For example, stainless steel, aluminum, nickel, titanium, fired carbon, or aluminum or stainless steel. A surface treated with carbon, nickel, titanium, silver, etc. may be used. The current collector may form fine irregularities on its surface to increase the adhesion of the positive electrode active material, and various forms such as films, sheets, foils, nets, porous materials, foams, and non-woven fabrics are possible.

In the case of a negative electrode current collector sheet, it is generally made to have a thickness of 3 to 500 μm. The negative electrode current collector is not particularly limited as long as it has conductivity without causing chemical change in the battery, and for example, the surface of copper, stainless steel, aluminum, nickel, titanium, fired carbon, copper or stainless steel. For example, a surface treated with carbon, nickel, titanium, silver, or the like, an aluminum-cadmium alloy, or the like may be used. In addition, like the positive electrode current collector, fine irregularities may be formed on the surface to enhance the bonding strength of the negative electrode active material, and may be used in various forms such as films, sheets, foils, nets, porous bodies, foams, and nonwoven fabrics.

In the present invention, the positive electrode active material is a material that can cause an electrochemical reaction, and is a lithium transition metal oxide, including two or more transition metals, for example, lithium cobalt oxide substituted with one or more transition metals (LiCoO ₂ ), layered compounds such as lithium nickel oxide (LiNiO ₂ ); lithium manganese oxide substituted with one or more transition metals; Formula LiNi _1-y M _y O ₂ (Where M = Co, Mn, Al, Cu, Fe, Mg, B, Cr, Zn, or Ga, including at least one of the above elements, 0.01≤y≤0.7) Lithium nickel-based oxide represented by; Li _1+z Ni _1/3 Co _1/3 Mn _1/3 O ₂ , Li _1+z Ni _0.4 Mn _0.4 Co _0.2 O ₂ , etc. Li _1+z Ni _b Mn _c Co _{1-(b+c+d )} M _d O _(2-e) A _e (where -0.5≤z≤0.5, 0.1≤b≤0.8, 0.1≤c≤0.8, 0≤d≤0.2, 0≤e≤0.2, b+c+d <1, M = Al, Mg, Cr, Ti, Si or Y, and A = F, P or Cl); Formula Li _1+x M _1-y M' _y PO _4-z X _z where M = transition metal, preferably Fe, Mn, Co or Ni, M' = Al, Mg or Ti and X = F, S, or N, and -0.5≤x≤+0.5, 0≤y≤0.5, 0≤z≤0.1), olivine-based lithium metal phosphates, etc., but are not limited thereto.

Examples of the negative electrode active material include carbon such as non-graphitizing carbon and graphite-based carbon; Li _x Fe ₂ O ₃ (0≤x≤1), Li _x WO ₂ (0≤x≤1), Sn _x Me _1-x Me' _y O _z (Me: Mn, Fe, Pb, Ge; Me' : Metal composite oxides such as Al, B, P, Si, elements of groups 1, 2, and 3 of the periodic table, halogens, 0<x≤1;1≤y≤3;1≤z≤8); lithium metal; lithium alloy; silicon-based alloys; tin-based alloys; SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , GeO, GeO ₂ , Bi ₂ O ₃ , Bi ₂ O ₄ , metal oxides such as Bi ₂ O ₅ ; conductive polymers such as polyacetylene; A Li-Co-Ni-based material or the like can be used.

The conductive material is typically added in an amount of 1 to 30% by weight based on the total weight of the mixture including the cathode active material. The conductive material is not particularly limited as long as it has conductivity without causing chemical change in the battery, and examples thereof include graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskeys such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives may be used.

The binder is a component that assists in the binding of the active material and the conductive material and the binding to the current collector, and is typically added in an amount of 1 to 30% by weight based on the total weight of the mixture including the positive electrode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, poly propylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber, fluororubber, various copolymers, and the like.

Meanwhile, the separator is interposed between an anode and a cathode, and an insulating thin film having high ion permeability and mechanical strength is used. The pore diameter of the separator is generally 0.01 to 10 μm, and the thickness is generally 5 to 300 μm. Examples of such a separator include olefin-based polymers such as chemical-resistant and hydrophobic polypropylene; A sheet or non-woven fabric made of glass fiber or polyethylene is used.

Meanwhile, in the electrode assembly, an electrode tab is formed on one side of the electrode, and the electrode tab may be a positive electrode tab or a negative electrode tab. A positive lead and a negative lead are respectively connected to the positive and negative tabs. The positive and negative leads are drawn out of the battery case and serve as terminals electrically connected to the outside. In this case, the anode lead and the anode lead may be bonded to the anode tab and the cathode tab, respectively, by welding. A known welding method can be used, and for example, ultrasonic welding or laser welding can be used.

At this time, the battery case is not particularly limited as long as it is used as an exterior material for packaging the battery, and a cylindrical, prismatic or pouch type may be used, but in detail, a pouch type battery case may be used. A pouch-type battery case is usually made of an aluminum laminate sheet, and may be composed of an inner sealant layer for sealing, a metal layer to prevent penetration of materials, and an outer resin layer forming the outermost part of the case. The battery cell is manufactured by heat-sealing the upper case and the lower case in a state in which the electrode lead is drawn out after the electrode assembly is accommodated in the pouch-type battery case, and a heat-sealing portion may be formed at the end of the battery case. Hereinafter, detailed descriptions of the battery case are omitted because they are known to those skilled in the art.

In addition, the present invention provides a welding state inspection method.

The welding state inspection method according to the present invention uses a first sensor for irradiating a primary magnetic field on a welded portion of a battery cell and a second sensor for detecting an eddy current signal induced by the first sensor to determine the welding state of a welded portion of a battery cell. As a method of inspecting, a sine wave having a frequency in a predetermined range is input to the first sensor, and normal welding/weak welding/ Evaluate cosmetic surgery.

In a conventional method of inspecting the welding state of a welded part using eddy current, the welding state is evaluated based on a phase difference of an eddy current signal received by an eddy current sensor. However, this method has a disadvantage in that it is difficult to distinguish welding defects due to weak welding from normal welding.

In the present invention, a sine wave having a frequency of a specific range is input to a first sensor, the first sensor applies a sine wave of a specific frequency to a welding part of a battery cell, and a second sensor receives an eddy current signal induced by the first sensor. and analyzes the waveform data of the eddy current signal detected by the second sensor to determine whether the welding state of the weld is a normal welding factor, weak welding, or non-welding.

Compared with the method of evaluating the welding state based on the phase difference of the eddy current signal, the inspection method of the present invention has an accurate distinction between normal welding and weak welding.

In one specific example, the frequency of the sine wave is 100 to 1000 Hz. If the numerical range is less than 100 Hz, the inspection speed may be too slow, and conversely, if it exceeds 1000 Hz, the detecting power of weak welding may be degraded, which is not preferable.

In one specific example, the first sensor and the second sensor perform the eddy current test along a set driving path in a non-contact state at a position spaced apart from the battery cell welding part.

In the inspection method of the present invention, the welding state is determined based on the amplitude of the eddy current signal, and the detection based on the amplitude is possible only when the welded portion to be inspected is located between the first sensor and the second sensor. That is, it is difficult to implement the present invention with an eddy current sensor in which both the first sensor and the second sensor are positioned on the upper surface of the welded part or both the first sensor and the second sensor are positioned on the lower surface of the welded part.

Example 1

As shown in FIG. 1, the eddy current test was performed by the first sensor and the second sensor on the welded portion of the battery cell where the electrode tab and the electrode lead were normally welded. At this time, the frequency of the sine wave input to the first sensor is 500 Hz.

Based on the eddy current signal sensed by the second sensor, the welding length was plotted on the X axis and the amplitude value was plotted on the Y axis, and the results are shown in FIG. 3 .

Example 2

The eddy current test was performed by the first sensor and the second sensor, as shown in FIG. At this time, the frequency of the sine wave input to the first sensor is 500 Hz.

Based on the eddy current signal sensed by the second sensor, the welding length was plotted on the X-axis and the amplitude value was plotted on the Y-axis, and the results are shown in FIG. 4 .

Example 3

As shown in FIG. 1 , the eddy current test was performed using the first sensor and the second sensor on the welded portion of the battery cell where the electrode tab and the electrode lead were weakly welded. At this time, the frequency of the sine wave input to the first sensor is 500 Hz.

Based on the eddy current signal sensed by the second sensor, the welding length was plotted on the X-axis and the amplitude value was plotted on the Y-axis, and the results are shown in FIG. 5 .

Comparative Example 1

In Example 1, a plotting graph was obtained in the same manner as in Example 1, except that the frequency of the saipan input to the first sensor was changed to 20 kHz. The results are shown in FIG. 7 .

Comparative Example 2

In Example 2, a plotting graph was obtained in the same manner as in Example 2, except that the frequency of the saipan input to the first sensor was changed to 20 kHz. The results are shown in FIG. 8 .

Comparative Example 3

In Example 3, a plotting graph was obtained in the same manner as in Example 3, except that the frequency of the saipan input to the first sensor was changed to 20 kHz. The results are shown in FIG. 9 .

The graphs of FIGS. 3 to 5 obtained in Examples 1 to 3 are combined and shown in FIG. 6, and the graphs of FIGS. 7 to 9 obtained in Comparative Examples 1 to 3 are combined and shown in FIG. 10 .

Referring to FIGS. 3 to 5, the amplitude graphs of normal welding and weak welding show a “U”-shaped symmetrical graph, and the amplitude graph of cosmetic welding does not have symmetry in certain parts as shown in FIG. there is.

Referring to FIG. 6 , compared to the normal welding graph, the amplitude value of the weak welding graph is generally higher and is smaller than the “U” shape of the normal welding graph. Therefore, according to the inspection system and inspection method of the present invention, cosmetic welding as well as weak welding can be distinguished from normal welding.

Referring to FIGS. 7 to 9 , in the amplitude graph of the cosmetic welding shown in FIG. 8 , certain parts are not symmetrical. Referring to FIG. 10 , since the normal welding graph and the weak welding graph completely overlap, normal welding and weak welding cannot be distinguished.

As described above, the inspection system and inspection method of the present invention have an effect of improving detection capability capable of detecting weak welding conditions.

Although preferred embodiments of the present invention have been described above with reference to the drawings, those skilled in the art or those having ordinary knowledge in the art do not deviate from the spirit and technical scope of the present invention described in the claims. It will be understood that the present invention can be variously modified and changed within the scope not specified.

Therefore, the technical scope of the present invention is not limited to the contents described in the detailed description of the specification, but should be defined by the claims.

10: battery cell
11: electrode tab
12: electrode lead
100: welding condition inspection system
110: inspection unit
111: first sensor
112: second sensor
120: data processing unit
A: Weld

Claims (11)

An inspection unit including a first sensor for irradiating a primary magnetic field to a welded portion of a battery cell and a second sensor for detecting an eddy current signal induced by the first sensor; and
A data processing unit for collecting the eddy current signal detected by the inspection unit and evaluating the welding state of the battery cell welding unit,
The first sensor receives a sinusoidal wave,
The data processing unit, the welding state inspection system of the battery cell for determining the welding state of the welded part based on the amplitude of the eddy current signal.
The system of claim 1, wherein the sine wave is a sine wave.
According to claim 1,
The frequency of the sine wave is 100 to 1000 Hz of the battery cell welding state inspection system.
According to claim 1,
The first sensor and the second sensor are welded state inspection system of a battery cell disposed opposite to the upper and lower portions of the welded portion of the battery cell, respectively.
According to claim 4,
The first sensor and the second sensor are spaced apart from the welding part of the battery cell by a predetermined distance,
A welding condition inspection system of a battery cell configured to move along a set driving path and perform an eddy current inspection in a non-contact state with a welding part.
According to claim 1,
The first sensor includes a transmitting coil for irradiating a primary magnetic field to the welding portion,
The second sensor is a welding state inspection system of a battery cell including a receiving coil for receiving a secondary magnetic field radiated by an eddy current generated in a welded portion by the primary magnetic field and generating an electromotive force.
According to claim 1,
The data processing unit, the welding state inspection system of the battery cell for determining the normal welding / weak welding / non-welding of the welding part through the shape, symmetry and area of the graph plotting the amplitude of the eddy current signal.
According to claim 7,
A welding condition inspection system of a battery cell that determines weak welding or non-welding by comparing with normal welding data.
A method for inspecting the welding state of a welded portion of a battery cell using a first sensor for irradiating a primary magnetic field on a welded portion of a battery cell and a second sensor for detecting an eddy current signal induced by the first sensor,
Inputting a sine wave having a frequency in a predetermined range to the first sensor;
A method for inspecting the welding condition of a battery cell for determining normal welding / weak welding / non-welding of a welded part through the shape, symmetry and area of a graph plotting the amplitude of an eddy current signal.
10. The method of claim 9, wherein the first sensor and the second sensor perform the eddy current inspection along a set travel path in a non-contact state at a location spaced apart from the battery cell welding part.
The method of claim 9, wherein the frequency of the sine wave is 100 to 1000 Hz.

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