KR20080092151A - Protective circuit of secondary cell and method for controlling thereof - Google Patents

Abstract

A secondary cell protective circuit and a control method thereof are provided to analyze an error based on internal state information by storing the internal state information of a fuse operation time point. A secondary cell protective circuit includes a sensing wire(11), a sensing unit(12), a thermistor(13), a fuse(15), and a micro controller(17). The sensing wire senses a voltage of a secondary cell. The sensing unit senses a charging/discharging current of the secondary cell. The thermistor varies a resistance based on a temperature variation of the secondary cell. The fuse breaks a path of the charging/discharging current of the secondary cell in response to a fuse driving signal. When an abnormal state of the secondary cell occurs in a charging/discharging mode of the secondary cell, the micro controller applies the fuse driving signal. The micron controller acquires, stores and controls the internal state information of the secondary cell through the sensing wire, the sensing unit and the thermistor during a melting time point of the fuse.

Description

Secondary battery protection circuit and its control method {PROTECTIVE CIRCUIT OF SECONDARY CELL AND METHOD FOR CONTROLLING THEREOF}

The following drawings attached to this specification are illustrative of the preferred embodiments of the present invention, and together with the detailed description of the invention to serve to further understand the technical spirit of the present invention, the present invention is a matter described in such drawings It should not be construed as limited to.

1 is a circuit diagram showing a secondary battery protection circuit according to an embodiment of the present invention.

2 is a timing diagram illustrating a state change during fuse melting according to an exemplary embodiment of the present invention.

3 is a flowchart illustrating a control method of a secondary battery protection circuit according to an embodiment of the present invention.

<Description of main reference numerals in the drawings>

10: cell 11: sensing wire

12: sensing means 13: thermistor

14: fuse drive switch 15: fuse

16: switch 16a, 16b: field effect transistor

17: microcontroller 20: memory

100: secondary battery

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary battery protection circuit. In particular, when an abnormal phenomenon occurs in a secondary battery, a secondary battery protection circuit and a battery for storing a battery's internal state information of a secondary battery and analyzing a failure cause thereof It relates to a control method.

In general, as the demand for portable electronic products such as video cameras, portable telephones, portable PCs, etc. increases rapidly, and development of electric vehicles, energy storage batteries, robots, satellites, etc. is in earnest, high performance capable of repetitive charging and discharging is possible. Research on secondary batteries is intensively conducted.

Commercially available secondary batteries include nickel cadmium batteries, nickel hydride batteries, nickel zinc batteries, and lithium secondary batteries. Among them, lithium secondary batteries have no memory effect and are free to charge and discharge, and have a very low self discharge rate. High energy density has advantages in miniaturization and light weight, so it is widely used in general. The secondary battery performs the charging and discharging process by the secondary battery circuit during the charge and discharge cycle life. In this case, when an abnormal phenomenon occurs in a battery pack in which an example lithium-ion secondary battery is embedded during charging and discharging, the fuse is fused to protect the secondary battery. Subsequently, when the after-sales service (A / S) is requested to the manufacturer of the battery pack, if the state of the battery pack changes depending on the environment during the process of wearing the battery pack, the battery stored in the battery pack Due to the fact that the status data of the pack changed or the cause of the fuse fusion was not properly recorded, it was difficult to identify the cause in the actual analysis work.

The present invention has been made in view of the above problems, and when a secondary battery abnormality occurs, the secondary battery protection circuit for storing the battery internal state information of the secondary battery to analyze the cause of the failure and Its purpose is to provide its control method.

In addition, the object of the present invention is to fuse the fuse of the secondary battery protection circuit according to the abnormal phenomenon of the secondary battery, and to acquire and store the internal state information of the secondary battery to accurately analyze the cause of the fuse of the fuse A secondary battery protection circuit and a control method thereof are provided.

Another object of the present invention is to provide a secondary battery protection circuit and a control method thereof capable of storing internal battery state information of a secondary battery at a time before and after fuse melting of the secondary battery protection circuit according to an abnormal phenomenon of the secondary battery. It is.

The present invention for achieving the above object, the sensing wire for sensing the voltage of the secondary battery; Sensing means for sensing a charge / discharge current of the secondary battery; A thermistor whose resistance is changed according to a temperature change of the secondary battery; A fuse for blocking a charge / discharge current path of the secondary battery by a fuse driving signal; When an abnormality occurs in the secondary battery during the charging / discharging mode of the secondary battery, the fuse driving signal is applied, and the secondary battery is discharged through the sensing wire, the sensing means, and the thermistor during the fusion and after melting of the fuse. And a microcontroller configured to control to acquire and store internal state information.

Preferably, the microcontroller is configured to monitor the temperature inside the battery using the voltage of each cell of the secondary battery, the total voltage of the secondary battery cells, the current flowing through the sensing means, the thermistor element at predetermined intervals.

Preferably, the microcontroller further comprises a memory in which battery internal state information of the secondary battery is stored.

Preferably, the microcontroller may be configured to obtain battery internal state information of the voltage between the secondary battery cells monitored using the sensing wire, the sensing means, and the thermistor at a predetermined period, the current flowing through the secondary battery, and the internal temperature of the secondary battery. 1 is stored in a memory, and when an abnormal phenomenon of a secondary battery is detected, internal battery state information corresponding to a point in time before the fuse melting is read from the first memory and stored in the second memory. And the battery internal state information corresponding to the time point after the fuse is melted due to the abnormal phenomenon of the secondary battery is read out from the first memory and stored in the second memory.

Preferably, the memory stores battery internal state information of the voltage between the secondary battery cells monitored using the sensing wire, the sensing means, and the thermistor at a predetermined period, the current flowing through the secondary battery, and the internal temperature of the secondary battery. A first memory; When an abnormality occurs in the secondary battery, the battery internal state information corresponding to the time before and after the fuse melting is configured to include a second memory that is read out from the first memory and stored.

Preferably, the battery internal state information includes at least one or more of an overvoltage holding time, an overcurrent holding time, an abnormal temperature holding time, a battery operating holding time, a charging operating time, a discharge operating time, and a charge / discharge cycle information.

Preferably, the battery internal state information is RMA (Return Analysis Function) basic information.

In addition, the present invention for achieving the above object, the sensing wire for sensing the voltage of the secondary battery; Sensing means for sensing a charge / discharge current of the secondary battery; A thermistor whose resistance is changed according to a temperature change of the secondary battery; In a control method of protecting a secondary battery by melting the fuse when an abnormality occurs in the secondary battery in the secondary battery protection circuit comprising a fuse to block the charge-discharge current path of the secondary battery by the fuse drive signal. When an abnormality occurs in the secondary battery during the charging or discharging mode of the secondary battery, the battery internal state information of the secondary battery is acquired and stored through the sensing wire, the sensing means, and the thermistor before and after the fuse of the fuse. And melting the fuse between the fuse fusion before and after the fusion.

Preferably, the process of melting the fuse may be performed by using the sensing wire, the sensing means, and the thermistor at predetermined cycles to determine internal battery state information of the voltage between the secondary battery cells, the current flowing through the secondary battery, and the internal temperature of the secondary battery. Monitoring and storing in the first memory; When the abnormal state of the secondary battery is detected, reading battery internal state information corresponding to a time point from the time point before the fuse melting to the first memory, and storing the state information of the battery in the second memory; Storing the internal state information of the battery in the second memory and melting the fuse at the time of detecting the abnormality of the secondary battery; And reading out the battery internal state information corresponding to the time point after the fuse melting from the first memory and storing the internal state information in the second memory.

Preferably, the battery internal state information includes at least one or more of an overvoltage holding time, an overcurrent holding time, an abnormal temperature holding time, a battery operating holding time, a charging operating time, a discharge operating time, and a charge / discharge cycle information.

Preferably, the battery internal state information is RMA (Return Analysis Function) basic information.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that it can be defined, it should be interpreted as a concept and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

It should be noted that in the following description, only parts necessary for understanding the operation and operation according to the present invention will be described, and descriptions of other parts will be omitted so as not to distract from the gist of the present invention.

In addition, in the following description, specific details of the secondary battery protection circuit and control method thereof of the present invention are shown to provide a more general understanding of the present invention. It will be apparent to one of ordinary skill in the art that the present invention may be readily practiced without these specific details and also by their modifications.

In the following description, the battery internal state information refers to information including at least one or more of overvoltage holding time, overcurrent holding time, abnormal temperature holding time, battery operating holding time, charging operating time, discharging operating time, and charge / discharge cycle information. Will be used immediately.

On the other hand, the secondary battery protection circuit of the present invention and the control method thereof, when an abnormal phenomenon such as overvoltage, overcurrent, overcharge, overdischarge, temperature rise, etc. occurs in the secondary battery, the fuse of the Pack + stage and the fuse of the fuse Based on the time point t0, the secondary cell voltages, currents, temperatures, operation modes (charge or discharge), overvoltage holding time, at the time point t0-Δt before fuse melting and the time point t0 + Δt after melting, A technical configuration for acquiring and storing battery internal state information including overcurrent holding time, operating time, and charge / discharge cycle number information is proposed. Therefore, in order to improve the quality of the after-sales service or secondary battery, it is possible to easily and accurately analyze the cause of the failure of the secondary battery.

1 is a circuit diagram illustrating a secondary battery protection circuit according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the sensing wire 11 senses the voltage of each cell 10 of the secondary battery 100 or the total voltage of the entire cell 10. In addition, the sensing wire 11 senses the charge voltage or the discharge voltage of the secondary battery according to the charge / discharge mode.

The sensing unit 12 senses the charge / discharge current of the secondary battery 100. Wherein the sensing means 12 is a current flowing through the Pack-stage.

The thermistor 13 has a variable resistance according to the internal temperature change of the secondary battery 100. In addition, the thermistor 13 includes a negative temperature coefficient (NTC) thermistor whose resistance decreases rapidly with respect to a temperature rise, or a positive temperature coefficient (PTC) thermistor whose resistance rapidly increases with a temperature rise. . Preferably, the present invention uses a positive temperature thermistor whose resistance increases with temperature rise.

The fuse drive switch 14 is operated by the fuse drive signal to allow the fuse 15 to be fused.

The fuse 15 blocks the charge / discharge current path of the secondary battery 100. In addition, when the fuse driving switch 14 is turned on, the fuse 15 is charged and discharged to the resistors R1 and R2 so that Joule heat generated at the Pack + stage by Joule heat generated by the resistors R1 and R2. To cut.

The switch 16 is switched by a switch control signal. Thus, when the first switch control signal is input, the switch 16 is switched to provide a current path of a charging mode or a discharge current. However, when the second switch control signal is input, the switch 16 is switched such that the charge current and discharge current paths of the secondary battery 100 are blocked. In addition, the switch 16 is preferably provided with a switch individually to provide a path of the charging current, discharge current according to the charging mode, discharge mode. Herein, the switch 16 may be any switch element that can be switched by a switch control signal. As shown in FIG. 1, two field effect transistors (FETs) 16a and 16b switched by first and second switch control signals are used as shown in FIG. 1. Here, since the operation of the field effect transistors 16a and 16b of the switch 22 is the same as the operation of the general field effect transistor, detailed description thereof will be omitted.

The microcontroller 17 controls the overall operation of the recirculation circuit according to the charge mode and the discharge mode of the secondary battery 100. In addition, the microcontroller 17 monitors the voltage of each cell 10 of the secondary battery 100 and the total voltage of the cell 10 through the sensing wire 11. The microcontroller 17 also monitors the charge current or discharge current through the sensing means 12. In addition, the microcontroller 17 monitors the internal temperature of the secondary battery 100 through the thermistor 13. In addition, the microcontroller 17 may excessively increase both end voltages BAT + to BAT- of the secondary battery 100 due to the overcharging during the above-described monitoring, excessive current flows through the sensing means, or the inside of the secondary battery. When the temperature rises or falls above the limit, the fuse drive signal is applied to the fuse drive switch 14. In addition, the microcontroller 17 uses a fast clock speed to maintain the voltage, current, battery internal temperature, battery operating mode, and overvoltage holding time of each cell 10 at a predetermined time (for example, 125 msec). The internal current state information, that is, the overcurrent holding time, abnormal temperature holding time, battery cumulative usage time, battery cumulative charging time, battery cumulative discharge time, and accumulated charge / discharge cycle information of the battery, is stored in the internal first memory 21. In addition, the microcontroller 17 maintains a record of the battery internal state information for a predetermined time and deletes the memory 20 from the memory 20 after a predetermined time elapses. In addition, when the micro controller 17 detects an abnormal phenomenon of the secondary battery 100, the microcontroller 17 does not immediately drive the fuse driving switch 14, but the inside of the stored battery at the time before the fuse melting from the first memory 21. The state information is read out and stored in the second memory 22. In addition, the microcontroller 17 reads stored battery internal state information at the time after the fuse melting from the first memory 21 and stores the stored battery internal state information in the second memory 22. That is, the microcontroller 17 can separately manage the battery internal state information before and after the fuse fusion. Here, the first and second memories 21 and 22 are provided in the memory 20 inside the microcontroller 17.

1 and 2, the operation of the secondary battery protection circuit of the present invention will be described.

As shown in FIG. 2, the microcontroller 17 stores battery internal state information from the sensing wire 11, the sensing means 12, and the thermistor 13 at a predetermined cycle 125 mSec (FIGS. 2B to 2E). Information) is monitored and stored in the first memory 21. Thereafter, when the micro-controller 17 detects an abnormal phenomenon of the secondary battery 100 as shown in FIG. 2 at the point ①, the internal state information of the battery at the point ② that is the previous point of the point ① is stored. The data is read from the first memory 21 and stored in the second memory 22. The microcontroller 17 applies a fuse driving signal to the fuse driving switch 14 so that the fuse 15 is melted at the point ①. Thereafter, the microcontroller 17 reads the battery internal state information (information (b) to (e) of FIG. 2) stored in the first memory 21 at a point ③ after the fusion of the fuse 15, and then performs a second reading. It stores in the memory 22. Accordingly, the internal memory state information before and after the melting time of the fuse is stored in the second memory 22.

3 is a flowchart illustrating a control method of a secondary battery protection circuit according to an embodiment of the present invention. Here, in order to perform the process as shown in FIG. 3, the secondary battery protection circuit includes a sensing wire 11 for sensing a voltage of the secondary battery 100 and sensing means for sensing a charge / discharge current of the secondary battery 100 ( 12), the thermistor 13, the resistance of which varies according to the temperature change of the secondary battery 100, and a fuse 15 for blocking the charge and discharge current path of the secondary battery 100 by the fuse drive signal do.

Referring to FIG. 3, in operation 301, the microcontroller 17 performs an overall operation according to a charge mode or a discharge mode according to the remaining battery voltage of the secondary battery 100.

At this time, in step 303, the microcontroller 17 starts counting a predetermined time and proceeds to step 305.

In step 305, the microcontroller 17 determines whether the counted time has elapsed for a predetermined time. If it is determined that the predetermined time has elapsed, the microcontroller 17 proceeds to step 307. The process is repeated until step 303 is repeated.

In operation 307, the microcontroller 17 monitors battery internal state information and stores the monitored battery internal state information in the first memory 21 in step 309.

In operation 311, the microcontroller 17 checks whether an abnormal phenomenon of the secondary battery 100 is detected. The abnormal phenomenon is detected by the battery internal state information described above.

As a result of the detection, if an abnormal phenomenon of the secondary battery 100 is not detected, the process returns to step 301 and is repeatedly performed. In addition, even when an abnormal phenomenon of a secondary battery, which will be described later, occurs, the microcontroller 17 should recognize that the battery internal state information is continuously stored in the first memory 21 by performing steps 301 to 309.

However, when the abnormality of the secondary battery 100 is detected as a result of the detection, in operation 313, the microcontroller 17 performs a first memory 21 at a time t0-Δt before the fuse 15 is melted. The battery internal state information stored in the readout is read out and stored in the second memory 22.

In operation 315, the microcontroller 17 applies a driving signal to the fuse melting time t0 to melt the fuse 15 to block the current path.

In operation 317, the microcontroller 17 reads battery internal state information stored in the first memory 21 at the time point t0 + Δt after the fuse 15 is melted and stored in the second memory 22. Accordingly, by storing the battery internal state information of the secondary battery in the first and second memories 21 and 22, a secondary battery protection circuit having a RAM (Return Analysis Function) function can be implemented.

Therefore, the secondary battery protection circuit of the present invention and the control method thereof according to the voltage, current, battery internal temperature, secondary battery of the secondary battery periodically during the operation according to the charge mode or discharge mode of the secondary battery Internal battery status information of operation mode, overvoltage duration, overcurrent maintenance time, abnormal temperature maintenance time, battery cumulative usage time, battery cumulative charge time, battery cumulative discharge time and cumulative charge / discharge cycle information of the battery are stored in the first memory. When an abnormality of the secondary battery is detected, internal battery state information before and after fuse melting is read from the first memory and stored in the second memory. Therefore, it is possible to determine the cause of the abnormality causing the fuse fusion.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by the equivalents of the claims.

As described in detail above, the present invention stores battery internal state information of a secondary battery before and after a fuse operation time when an abnormality occurs in a secondary battery, thereby using the internal state information of the battery to determine a cause of failure later. There is an effect that can be analyzed.

In addition, by storing the battery internal state information of the secondary battery at the time before and after the melting of the fuse melted according to the abnormality of the secondary battery, it is possible to easily and accurately identify the cause of the abnormality causing the fuse melting, This saves time and costs for analysis.

Claims (11)

A sensing wire sensing the voltage of the secondary battery; Sensing means for sensing a charge / discharge current of the secondary battery; A thermistor whose resistance is changed according to a temperature change of the secondary battery; A fuse for blocking a charge / discharge current path of the secondary battery by a fuse driving signal; When an abnormality occurs in the secondary battery during the charging / discharging mode of the secondary battery, the fuse driving signal is applied, and the inside of the battery of the secondary battery is connected to the fuse through the sensing wire, the sensing means, and the thermistor during the melting and the melting of the fuse. And a microcontroller configured to control to acquire and store state information. According to claim 1, The microcontroller, A secondary battery protection circuit configured to monitor the temperature inside the battery using a voltage of each cell of the secondary battery, a total voltage of the secondary battery cells, a current flowing through the sensing means, and a thermistor element at predetermined cycles. . According to claim 1, The microcontroller, And a memory for storing battery internal state information of the secondary battery. According to claim 1, The microcontroller, Storing internal battery state information of the voltage between the secondary battery cells monitored using the sensing wire, the sensing means and the thermistor at a predetermined period, the current flowing through the secondary battery, and the internal temperature of the secondary battery in the first memory, and When the abnormality of the secondary battery is detected, the internal state information of the battery corresponding to the time before the fuse melting is detected from the first memory is read out from the first memory and stored in the second memory. And a battery internal state information corresponding to a time point after the fuse is melted is read from the first memory and stored in the second memory. The method of claim 3, wherein The memory, A first memory in which battery internal state information of a voltage between both ends of the secondary battery cell monitored using the sensing wire, the sensing means, and the thermistor at a predetermined period, a current flowing through the secondary battery, and an internal temperature of the secondary battery is stored; And a second memory in which battery internal state information corresponding to a time point before and after fuse fusion is read out from and stored in the first memory when an abnormality occurs in the secondary battery. According to claim 1, The battery internal state information, A secondary battery protection circuit comprising at least one of overvoltage holding time, overcurrent holding time, abnormal temperature holding time, battery operating holding time, charging operating time, discharging operating time and charge / discharge cycle information. According to claim 1, The battery internal state information, RMA (Return Analysis Function) Secondary battery protection circuit, characterized in that the basic information. A sensing wire sensing the voltage of the secondary battery; Sensing means for sensing a charge / discharge current of the secondary battery; A thermistor whose resistance is changed according to a temperature change of the secondary battery; In a control method of protecting a secondary battery by melting the fuse when an abnormality occurs in the secondary battery in the secondary battery protection circuit comprising a fuse to block the charge-discharge current path of the secondary battery by the fuse drive signal. , When an abnormality occurs in the secondary battery during the charging or discharging mode of the secondary battery, the battery internal state information of the secondary battery is obtained and stored through the sensing wire, the sensing means, and the thermistor during the fuse and after the fuse. And controlling the fuse between the fuse fusion before and after the fusion. The method of claim 8, The process of melting the fuse, Monitoring and storing, in a first memory, internal battery state information of voltages across the secondary battery cell, current flowing through the secondary battery, and internal temperature of the secondary battery using the sensing wire, the sensing means, and the thermistor at predetermined intervals; ; When the abnormal state of the secondary battery is detected, reading battery internal state information corresponding to a time point from the time point before the fuse melting to the first memory, and storing the state information of the battery in the second memory; Storing the internal state information of the battery in the second memory and melting the fuse at the time of detecting the abnormality of the secondary battery; And reading out the battery internal state information corresponding to the time point after the fuse melting from the first memory and storing the battery internal state information in the second memory. The method of claim 8, The battery internal state information, A control method of a secondary battery protection circuit comprising at least one of information of overvoltage holding time, overcurrent holding time, abnormal temperature holding time, battery operating holding time, charging operating time, discharging operating time and charging / discharging cycle information. The method of claim 8, The battery internal state information, RMA (Return Analysis Function) A control method of a secondary battery protection circuit, characterized in that the basic information.

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