WO2021051449A1

WO2021051449A1 - Apparatus and method for detecting internal micro short circuit of battery

Info

Publication number: WO2021051449A1
Application number: PCT/CN2019/108829
Authority: WO
Inventors: 唐元安; 廖文昌
Original assignee: 深圳市众能达自动化设备有限公司
Priority date: 2019-09-19
Filing date: 2019-09-29
Publication date: 2021-03-25
Also published as: CN110501654B; CN110501654A

Abstract

An apparatus for detecting an internal micro short circuit of a battery. A battery is continuously monitored during a formation and charging process of the battery, and a signal of a quickly changing voltage is filtered out by using a differentiation circuit. The direct-current voltage of a battery is isolated according to the characteristics of the differentiation circuit, and furthermore, a separated signal of a slightly changing voltage is sent to an amplifier for amplification, such that the requirement for a high-precision meter is lowered; and amplified signals are collected by using a high-speed AD converter, a captured voltage change signal is transmitted to a computer by means of a single-chip microcomputer, and finally, a product in which an internal micro short circuit occurs is determined. Moreover, positive amplification and negative amplification can both be used, and secondary amplification is carried out, such that a subtle voltage or current change of the battery is detected more effectively and accurately, thereby detecting a faulty battery, or observing the status of a battery at any time to estimate the service life of the battery.

Description

Device and method for detecting micro-short circuit inside battery

Technical field

The invention relates to a detection device inside a battery and a detection method thereof.

Background technique

At present, the battery production process sometimes has some process problems, for example, the electrode foil will produce burrs when trimming, or the electrolyte and electrolyte paper contain impurities; as the battery charging voltage increases and the internal temperature of the battery increases, The burrs or impurities in the battery will pierce the electrolytic paper and produce instantaneous discharge. At the same time, a large amount of heat energy will be generated, ranging from carbonization of the electrolytic paper to severe fire and explosion of the battery. The location of the short-circuit point will vaporize the electrolyte due to the high temperature, and the electrolytic paper will dry up and become temporarily insulated. However, it will be immersed in the electrolyte again and repeated micro-short circuits will occur.

Summary of the invention

technical problem

The capacity of the battery is very large, and the slight short circuit of the glitch has very little effect on the change of the battery voltage. If you directly monitor the battery voltage, a very high-precision instrument is required, and the battery will quickly recover to the voltage before the micro-short circuit. The acquisition rate can be captured. Due to the uncertainty of the micro-short-circuit phenomenon again in the product that has experienced the micro-short-circuit, it is difficult to detect the micro-short-circuit phenomenon of the battery.

The solution to the problem

Technical solutions

The technical problem to be solved by the present invention is to use the characteristics of the differential circuit to isolate the DC voltage of the battery, and at the same time to send the separated small change voltage signal to the amplifier for amplification, reducing the requirements for high-precision instruments, and adopting high-speed AD conversion The amplifier performs analog-to-digital conversion on the amplified signal, and transmits the AD conversion result to the computer through the single-chip microcomputer, and finally determines the product with a slight internal short circuit. The specific plan is as follows:

A detection device for micro short circuit inside a battery, comprising

The voltage detection unit is used to detect the voltage change value of the battery,

The data storage unit is connected to the single-chip microcomputer, and may also be the internal data storage of the single-chip microcomputer.

The single-chip microcomputer is connected to the upper computer through a data transmission unit,

The host computer is used to send control information to the single-chip microcomputer through the data transmission unit, and to receive the signal output by the single-chip microcomputer through the data transmission unit;

AD conversion unit, the voltage detection unit is connected to the single-chip microcomputer through the AD conversion unit,

The AD conversion unit, the single-chip microcomputer, the data storage unit, and the data transmission unit are all connected to the power supply module unit, and are powered by the power supply module; characterized in that:

The voltage detection unit includes at least one independent amplifying circuit:

The amplifying circuit includes

The first capacitor C1, the positive electrode of the first capacitor C1 is connected to the positive electrode of the battery under test, and the negative electrode of the first capacitor C1 is connected to the inverting input terminal of the first operational amplifier,

The second capacitor C2, the positive electrode of the second capacitor C2 is connected to the output terminal of the first operational amplifier, the negative electrode is connected to the positive input of the second operational amplifier, and the output of the second operational amplifier is connected with an electronic switch.

The electronic switch is connected to an AD conversion unit, the electronic switch is an independent or integrated electronic switch inside the single-chip microcomputer, and the AD conversion unit is an independent AD converter or an AD converter built in the single-chip microcomputer.

The amplifying circuit also includes a resistor R1, a resistor R2, a resistor R3, and a resistor R4,

The resistor R1 is connected to the inverting input and output terminals of the first operational amplifier;

The resistor R2 and the resistor R3 are respectively connected to the non-inverting input terminal and the inverting input terminal of the second operational amplifier, and the other ends are both grounded;

The resistor R4 is connected to the inverting input and output terminals of the second operational amplifier;

The first operational amplifier works in reverse amplification, and the second operational amplifier works in forward amplification, and can also work in forward or reverse amplification at the same time.

The power supply module unit includes a wireless power supply unit and a wireless power receiving unit. The wireless power supply unit is used to emit electromagnetic radiation energy. The wireless power receiving unit is used to receive the electromagnetic radiation energy emitted by the wireless power supply unit and transmit the electromagnetic radiation. The energy is converted into electrical energy for the work of the AD conversion unit, the single-chip microcomputer, the data storage unit and the data transmission unit.

The data transmission unit is an RS232 interface communication unit or a wireless data transmission unit. The data transmission unit communicates with the upper computer and is directly connected with the single-chip microcomputer.

A method for detecting micro-short circuit inside a battery, including:

Step A: Connect the battery detection unit to the battery, that is, connect the positive electrode of the first capacitor to the positive electrode of the battery to be tested. The purpose of the first capacitor here is to isolate the DC voltage of the battery and send the weak change signal to The negative input of the first operational amplifier performs amplification processing;

Step B: Connect the positive pole of the second capacitor to the output terminal of the first operational amplifier, and connect the negative pole to the positive input of the second operational amplifier. The function of the second capacitor is to isolate the DC voltage output by the first operational amplifier. , The voltage change signal amplified by the first operational amplifier is sent to the second operational amplifier for the second amplification;

Step C, the voltage change signal output by the second operational amplifier after the second amplification is sent to the electronic switch for switching and then sent to the AD converter for data collection;

Step D: After the AD converter performs digital-to-analog conversion on the voltage value amplified by the second operational amplifier, the single-chip microcomputer processes the digital-to-analog conversion result, and transfers the processed data to the data storage unit for storage;

In step E, the data processed by the single-chip microcomputer is sent to the upper computer through the data transmission unit for judgment, and the hidden danger battery is screened out according to the judgment result.

In step A and step B, more than one battery can be connected in parallel, and more than one electronic switch can be connected at the same time;

In the steps A and B, the first operational amplifier and the second operational amplifier select either forward amplification or reverse amplification.

The present invention continuously monitors the battery during the formation and charging process of the battery. The voltage characteristic of the battery during charging is that the voltage changes slowly. Therefore, the focus of the present invention is to filter out the rapidly changing voltage signal by using a differential circuit. The invention uses the characteristics of the differential circuit to isolate the DC voltage of the battery, and at the same time sends the separated small change voltage signal to the amplifier for amplification, reducing the requirements for high-precision instruments, and adopts a high-speed AD converter to analyze the amplified signal. Collect, transmit the captured voltage change signal to the computer through the single-chip microcomputer, and finally determine the product with a slight internal short circuit. Moreover, either forward or direction amplification is possible, and secondary amplification can be performed to detect the subtle voltage or current changes of the battery more effectively and accurately, so as to detect the problematic battery or observe the battery status at any time to estimate the service life of the battery.

The beneficial effects of the invention

Beneficial effect

The present invention is an unprecedented detection device that can truly solve the internal slight short circuit caused by defective products in the current battery production process, prevents more serious accidents due to the inflow of battery defects into the market, and provides a safe guarantee for the end user to use the battery. In particular, the safety of power batteries can be further improved.

Brief description of the drawings

Description of the drawings

In order to explain the technical solutions of the embodiments of the present invention more clearly, the following will briefly introduce the drawings used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative work, other drawings can be obtained from these drawings. In the drawings:

Figure 1 is a detection circuit diagram of the present invention;

Figure 2 is a flow chart of the detection method of the present invention.

Invention embodiment

detailed description

In order to make the objectives, technical solutions and advantages of the present invention clearer, the various embodiments to be described below will refer to the corresponding drawings. These drawings constitute a part of the embodiments, which describe the various possible implementations of the present invention. Kind of examples. It should be understood that other embodiments may be used, or structural and functional modifications may be made to the embodiments listed herein without departing from the scope and essence of the present invention.

In the process of battery formation, the internal temperature of the battery rises, and the pressure will increase with the temperature rise. The burrs or impurities will pierce the electrolytic paper due to the pressure, causing an instant short circuit or explosion. Due to the large capacity of the battery, the short circuit point will be burnt instantly when a micro short circuit caused by internal burrs or impurities occurs, and the voltage at both ends of the battery will also change slightly, and then it will quickly rise to the voltage before the micro short circuit occurs. Therefore, collecting these voltage changes requires a very fast speed. However, the battery itself will output direct current. To amplify these weak voltage change signals requires isolation of the battery’s own direct current voltage, so we propose a solution:

1, a detection device for flash fire inside a battery includes a voltage detection unit for detecting the voltage change value of the battery. In this embodiment, the voltage detection unit in FIG. 1 includes a plurality of circuit units 1. According to the storage unit not shown in the figure, the data storage unit is provided in the single-chip microcomputer U4, and the single-chip U4 is connected to the upper computer through the data transmission unit. In this embodiment, the upper computer is the computer.

This embodiment takes a detection circuit unit 1 as an example for description: the circuit unit 1 amplifies the voltage of the detection battery and transmits it to the single-chip microcomputer U4 through the electronic switch U2, connected to the AD conversion unit U3, and sent to the PC for judgment after being processed by the single-chip microcomputer U4; The computer sends control information to the single-chip microcomputer through the data transmission unit, and receives the signal output by the single-chip microcomputer through the data transmission unit; the batteries with hidden dangers are screened out to prevent them from flowing into the market. Effectively solve the danger of fire and explosion when products with internal short circuits in the battery flow into the end market application.

The circuit unit 1, the AD conversion unit U3, the single-chip microcomputer U4, the data storage unit, and the data transmission unit in the voltage detection unit described above are all connected to the power supply module unit and powered by the power supply module.

The voltage detection unit includes at least one independent circuit unit. As shown in FIG. 1, it may include N circuit units. The circuit unit here is an amplifying circuit: the amplifying circuit includes a first capacitor C1, and the positive electrode of the first capacitor C1 Connected to the positive electrode of the battery under test, and the negative electrode of the first capacitor C1 is connected to the inverting input terminal of the first operational amplifier U1A. The amplifying circuit as shown in FIG. 1 also includes a resistor R1, a resistor R2, a resistor R3, and a resistor R4, so The resistor R1 is connected to the reverse input and output ends of the first operational amplifier U1A; the resistor R2 and the resistor R3 are respectively connected to the non-inverting input terminal and the inverting input terminal of the second operational amplifier U1B, and the other ends are both grounded; the resistor R4 is connected to the input and output ends of the second operational amplifier U1B; the first operational amplifier U1A is a reverse amplifier, and the second operational amplifier U1B is a forward amplifier.

The second capacitor C2, the positive electrode of the second capacitor C2 is connected to the output terminal of the first operational amplifier U1A, the negative electrode is connected to the positive input of the second operational amplifier U1B, and the output terminal of the second operational amplifier U1B is connected to the electronic switch U2 .

The electronic switch U2 is an independent or integrated electronic switch inside the single-chip microcomputer, and the AD conversion unit is an independent AD converter or an AD converter built in the single-chip U4.

The power supply module unit may be connected via a wired connection, and at the same time, a wireless power supply unit and a wireless power receiving unit may be used. The wireless power supply unit is used to transmit electromagnetic radiation energy, and the wireless power receiving unit is used to receive the power transmitted by the wireless power supply unit. Electromagnetic radiation energy, and the electromagnetic radiation energy is converted into electrical energy for the work of AD conversion unit, single chip microcomputer, data storage unit and data transmission unit.

The data transmission unit may adopt wired data transmission or a wireless data transmission unit; when a wireless data transmission unit is adopted, an infrared communication module is used to communicate with the upper computer and is directly connected to the single-chip microcomputer.

As described in Figure 1 above, the present invention can monitor multiple batteries at the same time, and each battery monitor has an independent amplifying circuit. As shown in Figure 1, there can be N units in parallel, where N is an integer greater than or equal to 1.

The above-mentioned electronic switch U2 is connected to the AD converter U3. The electronic switch U2 is an independent or integrated electronic switch within the single-chip microcomputer. In this embodiment, the electronic switch model is 4052, or other types of electronic switches, or integrated inside the single-chip microcomputer. Electronic switch.

The AD converter U3 is an independent unit or an AD converter built in a single-chip microcomputer. In this embodiment, an AD converter of the ADS8320 model is used, and the AD converter is electrically connected to the MCU single-chip microcomputer. The single-chip microcomputer model in this embodiment is ATMEGA8A, and it can also be any other single-chip microcomputer. After reading the AD conversion result, it is transmitted to the computer through the RS232 interface, and the computer determines whether an internal short circuit occurs.

As shown in Figure 2, a method for detecting micro-short circuit inside a battery includes:

Step A: Connect the battery detection unit to the battery, that is: connect the positive electrode of the first capacitor C1 to the positive electrode of the battery to be tested. The purpose of the first capacitor C1 here is to isolate the DC voltage of the battery and send a weak change signal Enter the negative input of the first operational amplifier U1A for amplification processing;

Step B: Connect the positive pole of the second capacitor C2 to the output terminal of the first operational amplifier U1A, and the negative pole to the positive input of the second operational amplifier U1B, where the second capacitor C2 is used to output the first operational amplifier U1A The DC voltage is isolated, and the voltage change signal amplified by the first operational amplifier U1A is sent to the second operational amplifier U1B for the second amplification;

Step C: Send the voltage change signal output by the second operational amplifier U1B after the second amplification to the electronic switch for switching and then to the AD converter for data collection;

Step D: After the AD converter performs digital-to-analog conversion on the voltage value amplified by the second operational amplifier, the single-chip microcomputer processes the voltage value at both ends of the capacitor, and transfers the processed signal to the data storage unit for storage;

Step E: Send the data processed by the single-chip microcomputer to the upper computer through the data transmission unit for judgment. According to the judgment result, the batteries with hidden dangers are screened out.

In step A and step B, more than one battery can be connected in parallel, and more than one electronic switch can be connected at the same time.

In the steps A and B, the first operational amplifier U1A is a reverse amplification, and the second operational amplifier U1B is a forward amplification.

The invention amplifies the weak voltage change when the battery is short-circuited and sends it to analog-to-digital conversion for collection. After processing by the single-chip microcomputer, it is sent to the PC for judgment, and the hidden danger battery is screened out to prevent it from flowing into the market. Effectively solve the risk of fire and explosion when the internal short-circuit product of the battery flows into the terminal market application.

In order to verify the effect of the present invention, the inventor obtained the following data through experiments:

If the battery is 2000mA/H and the power loss caused by the micro-short circuit is 0.0033 Coulomb, the first-stage amplification in the circuit is 1000 times, and the second-stage amplification is 1000 times. This circuit can capture a peak change of about 0.8V.

In this circuit simulation, a 3600F capacitor is used to replace the 2000mA/H lithium battery, and a 1000uF capacitor that has discharged the power is connected to the 3600F capacitor instantaneously through the switch, thereby simulating the instantaneous loss of power when the battery is short-circuited, and the capacitor is charged by 1000uF. To 3.3V requires 0.0033 Coulomb of electricity, so this circuit simulates the voltage change waveform captured when the battery loses 0.0033 Coulomb when a micro short circuit occurs. Use high-speed AD to collect the amount of change, and finally send the collected data to the computer for judgment.

Compared with batteries, when an internal micro short circuit occurs, the energy loss accounts for a small proportion of the capacity. However, the battery that has undergone a micro short circuit has the potential to catch fire and explode. This circuit isolates the battery's own direct current to reduce the battery's weak voltage. The changes are sent to a level 2 magnification of about 1000 times for collection, which can effectively capture the internal micro short circuit phenomenon.

Changing the magnification can change the detection sensitivity, which can be determined according to specific product requirements. This simulation experiment just shows that the battery micro short circuit can be detected.

The parameters in the simulation circuit can detect the voltage variation range of 1nV～5uV, and the magnification can also be changed according to actual needs to achieve a larger range of detection values.

In addition to RS232 wireless communication, the above wireless communication can also use Bluetooth communication; RS232 wireless module communication is half-duplex, that is, the module cannot receive data when the wireless module transmits data, and the module cannot transmit data when receiving data.

The above are only preferred embodiments of the present invention, and those skilled in the art know that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teaching of the present invention, these features and embodiments can be modified to adapt to specific conditions and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of the present application belong to the protection scope of the present invention.

Claims

A device for detecting micro short circuit inside a battery, which is characterized in that it comprises:

The voltage detection unit is used to detect the voltage change value of the battery,

According to the storage unit, the data storage unit is connected to the single-chip microcomputer,

The single-chip microcomputer is connected to the upper computer through a data transmission unit,

The host computer is used to send control information to the single-chip microcomputer through the data transmission unit, and communicate with

Receive the signal output by the single-chip microcomputer through the data transmission unit;

AD conversion unit, the voltage detection unit is connected to the single-chip microcomputer through the AD conversion unit,

The AD conversion unit, the single-chip microcomputer, the data storage unit, and the data transmission unit are all connected to the power supply module unit and are powered by the power supply module;

The voltage detection unit includes at least one independent amplifying circuit:

The amplifying circuit includes

A first capacitor, the positive electrode of the first capacitor is connected to the positive electrode of the battery under test, and the negative electrode of the first capacitor is connected to the reverse input terminal of the first operational amplifier,

A second capacitor, the positive electrode of the second capacitor is connected to the output terminal of the first operational amplifier, the negative electrode is connected to the positive input of the second operational amplifier, and the output of the second operational amplifier is connected with an electronic switch.
The device for detecting micro-short circuit inside a battery according to claim 1, wherein the electronic switch is connected to an AD conversion unit, the electronic switch is an independent or integrated electronic switch inside a single-chip microcomputer, and the AD conversion unit is Independent AD converter or the built-in AD converter of the single-chip microcomputer.
The device for detecting micro short circuit inside the battery according to claim 2, wherein the amplifying circuit further comprises a resistor R1, a resistor R2, a resistor R3, and a resistor R4,

The resistor R1 is connected to the reverse input and output ends of the first operational amplifier;

The resistor R2 and the resistor R3 are respectively connected to the non-inverting input terminal and the inverting input terminal of the second operational amplifier, and the other ends are both grounded;

The resistor R4 is connected to the reverse input and output ends of the second operational amplifier;

The first operational amplifier is reverse amplification, and the second operational amplifier is forward amplification.
The device for detecting micro short circuit inside the battery according to claim 3, the power supply module unit includes a wireless power supply unit and a wireless power receiving unit, the wireless power supply unit is used to emit electromagnetic radiation energy, and the wireless power receiving unit The unit is used to receive the electromagnetic radiation energy emitted by the wireless power supply unit and convert the electromagnetic radiation energy into electrical energy for the AD conversion unit, the single-chip microcomputer, the data storage unit and the data transmission unit.
The device for detecting micro-short circuit inside the battery according to claim 4, wherein the data transmission unit is a wireless data transmission unit, and the wireless data transmission unit uses an RS232 interface to communicate with the upper computer and directly communicates with the single-chip microcomputer. Connected.
A method for detecting micro-short circuit inside the battery, which is characterized by:

Step A, connect the battery detection unit to the battery, that is, connect the positive electrode of the first capacitor to the positive electrode of the battery to be tested. The purpose of the first capacitor here is to isolate the DC voltage of the battery and send the weak change signal into To the negative input of the first operational amplifier for amplifying processing;

Step B: Connect the positive pole of the second capacitor to the output terminal of the first operational amplifier, and connect the negative pole to the positive input of the second operational amplifier. The function of the second capacitor here is to perform the DC voltage output by the first operational amplifier. Isolation, the voltage change signal amplified by the first operational amplifier is sent to the second operational amplifier for second amplification;

Step C: Send the voltage change signal output by the second operational amplifier after the second amplification to the electronic switch for switching, and then send it to the AD converter for data collection;

Step D: After the AD converter performs digital-to-analog conversion on the voltage value of the output terminal amplified by the second operational amplifier, the single-chip microcomputer processes the AD conversion result and transfers the processed signal to the data storage unit for storage;

Step E: Send the data processed by the single-chip microcomputer to the upper computer through the data transmission unit for judgment, and screen out the hidden danger battery according to the judgment result.
The method for detecting micro-short circuit inside a battery according to claim 6, characterized in that: in step A and step B, more than one battery can be connected in parallel, and more than one electronic switch can be connected at the same time;
7. The method for detecting micro-short circuit inside a battery according to claim 6, characterized in that: in the steps A and B, the first operational amplifier is a reverse amplifier, and the second operational amplifier is a forward amplifier.