Device for preventing over-discharge
阅读说明:本技术 防止过放电的设备 (Device for preventing over-discharge ) 是由 金坰稷 孙荣洙 李镇贤 于 2019-03-06 设计创作,主要内容包括:一种防止过放电的设备,包括:第一开关,位于将电池单元和输出端子电连接的第一放电路径上;第二开关,位于第一放电路径上并且具有分别与第一开关的另一端和输出端子电连接的一端和另一端;限流电阻器,位于第二放电路径上,所述第二放电路径将位于第一开关与第二开关之间的第一节点和位于第二开关与输出端子之间的第二节点电连接,所述限流电阻器具有电连接至第一节点的一端;第三开关,位于第二放电路径上并且具有分别与限流电阻器的另一端和第二节点电连接的一端和另一端;和处理器,配置成利用电池单元的最小工作电压、限流电阻器引起的第一电压降和电池单元的内部电阻器引起的第二电压降中的至少一个设定基准电压,并且基于基准电压控制第一开关、第二开关和第三开关的工作状态。(An over-discharge prevention apparatus comprising: a first switch located on a first discharge path electrically connecting the battery cell and the output terminal; a second switch located on the first discharge path and having one end and the other end electrically connected to the other end of the first switch and the output terminal, respectively; a current limiting resistor on a second discharge path electrically connecting a first node between the first switch and the second switch and a second node between the second switch and the output terminal, the current limiting resistor having one end electrically connected to the first node; a third switch on the second discharge path and having one end and the other end electrically connected to the other end of the current limiting resistor and the second node, respectively; and a processor configured to set a reference voltage using at least one of a minimum operating voltage of the battery cell, a first voltage drop caused by the current limiting resistor, and a second voltage drop caused by an internal resistor of the battery cell, and to control operating states of the first switch, the second switch, and the third switch based on the reference voltage.)
1. An over-discharge prevention apparatus comprising:
a first switch on a first discharge path electrically connecting the battery cell and the output terminal;
a second switch located on the first discharge path and having one end and the other end electrically connected to the other end of the first switch and the output terminal, respectively;
a current limiting resistor on a second discharge path electrically connecting a first node between the first switch and the second switch and a second node between the second switch and the output terminal, the current limiting resistor having one end electrically connected to the first node;
a third switch located on the second discharge path and having one end and the other end electrically connected to the other end of the current limiting resistor and the second node, respectively; and
a processor configured to set a reference voltage using at least one of a minimum operating voltage of the battery cell, a first voltage drop caused by the current limiting resistor, and a second voltage drop caused by an internal resistor of the battery cell, and to control operating states of the first switch, the second switch, and the third switch based on the reference voltage.
2. The overdischarge prevention apparatus of claim 1,
wherein the processor is configured to calculate the first voltage drop using a temperature-based variable resistance of the current-limiting resistor and a discharge current of the battery cell.
3. The overdischarge prevention apparatus of claim 1,
wherein the processor is configured to calculate the second voltage drop using a temperature-based internal resistance of the battery cell and a discharge current of the battery cell.
4. The overdischarge prevention apparatus of claim 1,
wherein the processor is configured to calculate the reference voltage using the following equation:
< equation >
Vref=Vmin+IoRv+IoRi
Wherein VrefIs said reference voltage, VminIs the minimum operating voltage, I, of the battery celloIs the discharge current, R, of the battery cellvIs a temperature-based variable resistance, R, of said current-limiting resistoriIs the temperature-based internal resistance of the battery cell.
5. The overdischarge prevention apparatus of claim 1,
wherein when receiving an output request signal, the processor is configured to control the operating states of the first switch and the second switch to an on state and the third switch to an off state.
6. The overdischarge prevention apparatus of claim 5,
wherein the processor is configured to compare a cell voltage of the battery cell with the reference voltage and control operation states of the first switch, the second switch, and the third switch according to a comparison result.
7. The overdischarge prevention apparatus of claim 6,
wherein when the cell voltage of the battery cell is equal to or lower than the reference voltage, the processor is configured to control the operating states of the first switch and the third switch to an on state and the operating state of the second switch to an off state.
8. A battery pack comprising the overdischarge prevention apparatus as claimed in any one of claims 1 to 7.
9. An electronic device comprising the overdischarge prevention apparatus according to any one of claims 1 to 7.
Technical Field
This application claims priority to korean patent application No. 10-2018-0028619, filed in korea on 12.3.2018, the disclosure of which is incorporated herein by reference.
The present disclosure relates to an over-discharge preventing apparatus, and more particularly, to an over-discharge preventing apparatus by gradually reducing an output of a battery.
Background
Recently, demands for portable electronic products such as notebook computers, video cameras, and portable phones have sharply increased, and electric vehicles, energy storage batteries, robots, satellites, and the like have been actively developed. Therefore, high-performance secondary batteries that allow repeated charging and discharging are being actively studied.
Currently commercially available secondary batteries include nickel cadmium batteries, nickel hydrogen batteries, nickel zinc batteries, lithium secondary batteries, and the like. Among these batteries, lithium secondary batteries are receiving much attention because of having little memory effect compared to nickel-based secondary batteries and also having a very low self-discharge rate and high energy density.
In addition, the secondary battery may be used as a single secondary battery, but in order to be used as a high-voltage and/or large-capacity power storage system, a plurality of secondary batteries are connected in series and/or parallel, or in the form of a battery pack including a battery management system for controlling the overall charge/discharge operation of the secondary batteries included therein.
A battery management system used in a battery pack monitors the state of a battery using a temperature sensor, a current sensor, a voltage sensor, etc., and estimates SOC and SOH using the monitoring results, balances the voltage between battery cells, or protects the battery from overcharge, overdischarge, high voltage, overcurrent, low temperature, and high temperature.
In particular, the battery management system may include a protection circuit to prevent the battery from being over-discharged to have a voltage lower than a minimum operating voltage. For example, the battery management system has a switch on a discharge path of the battery, and when the voltage of the battery falls below a preset minimum operating voltage, the battery management system turns off the switch to cut off the discharge of the battery, thereby preventing the overdischarge of the battery.
In the over-discharge prevention technique of the conventional battery management system, the output of the battery is cut off when the voltage of the battery falls below the minimum operating voltage, and thus the system powered by the battery is suddenly shut down.
Disclosure of Invention
Technical problem
The present disclosure is directed to providing an over-discharge prevention apparatus for preventing over-discharge of a battery cell by setting a reference voltage using a minimum operating voltage and a voltage drop of a current limiting resistor whose resistance varies according to its own temperature and an internal resistor of the battery cell and then controlling electrical connection of the current limiting resistor based on a comparison result of a cell voltage of the battery cell and the reference voltage.
Objects of the present disclosure are not limited to the above objects, and other objects and advantages of the present disclosure may be understood from the following detailed description and will become more apparent from exemplary embodiments of the present disclosure. Further, it will be readily understood that the objects and advantages of the present disclosure may be realized by the means set forth in the appended claims and combinations thereof.
Technical scheme
In an aspect of the present disclosure, there is provided an over-discharge prevention apparatus including: a first switch on a first discharge path electrically connecting the battery cell and the output terminal; a second switch located on the first discharge path and having one end and the other end electrically connected to the other end of the first switch and the output terminal, respectively; a current limiting resistor on a second discharge path electrically connecting a first node between the first switch and the second switch and a second node between the second switch and the output terminal, the current limiting resistor having one end electrically connected to the first node; a third switch located on the second discharge path and having one end and the other end electrically connected to the other end of the current limiting resistor and the second node, respectively; and a processor configured to set a reference voltage using at least one of a minimum operating voltage of the battery cell, a first voltage drop caused by the current limiting resistor, and a second voltage drop caused by an internal resistor of the battery cell, and to control operating states of the first switch, the second switch, and the third switch based on the reference voltage.
Preferably, the processor may be configured to calculate the first voltage drop using a temperature-based variable resistance of the current limiting resistor and a discharge current of the battery cell.
Preferably, the processor may be configured to calculate the second voltage drop using a temperature-based internal resistance of the battery cell and a discharge current of the battery cell.
Preferably, the processor may be configured to calculate the reference voltage using the following equation:
< equation >
Vref=Vmin+IoRv+IoRi
Wherein VrefIs said reference voltage, VminIs the minimum operating voltage, I, of the battery celloIs the discharge current, R, of the battery cellvIs a temperature-based variable resistance, R, of said current-limiting resistoriIs the temperature-based internal resistance of the battery cell.
Preferably, when receiving an output request signal, the processor may be configured to control the operating states of the first switch and the second switch to an on state and the operating state of the third switch to an off state.
Preferably, the processor may be configured to compare a cell voltage of the battery cell with the reference voltage and control the operation states of the first switch, the second switch, and the third switch according to a comparison result.
Preferably, when the cell voltage of the battery cell is equal to or lower than the reference voltage, the processor may be configured to control the operation states of the first switch and the third switch to an on state and the operation state of the second switch to an off state.
A battery management system according to the present disclosure may include the over-discharge prevention apparatus.
The battery pack according to the present disclosure may include the over-discharge prevention apparatus.
An electronic device according to the present disclosure may include the over-discharge prevention apparatus.
Advantageous effects
According to the present disclosure, a reference voltage is set using a minimum operating voltage and a voltage drop of a current limiting resistor whose resistance varies according to its own temperature and an internal resistor of a battery cell, and then a flow of current flowing through the current limiting resistor is controlled based on a comparison result of a cell voltage of the battery cell and the reference voltage, thereby preventing over-discharge of the battery cell. As a result, since the output of the battery cell gradually decreases, the power supplied to the load can be prevented from being suddenly cut off.
Drawings
Fig. 1 is a diagram illustrating a configuration of an over-discharge prevention apparatus according to an embodiment of the present disclosure.
Fig. 2 is a diagram schematically illustrating a connection configuration of an over-discharge prevention apparatus, a battery pack, and a load according to an embodiment of the present disclosure.
Fig. 3 is a diagram illustrating an example of switching control when a processor of an over-discharge prevention apparatus according to an embodiment of the present disclosure receives an output request signal.
Fig. 4 is a diagram illustrating an example of switching control performed by a processor of the over-discharge prevention apparatus according to an embodiment of the present disclosure.
The accompanying drawings illustrate preferred embodiments of the present disclosure and together with the foregoing disclosure serve to provide a further understanding of the technical features of the present disclosure, and therefore the present disclosure should not be construed as being limited to the accompanying drawings.
Detailed Description
Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms used in the specification and the appended claims should not be construed as limited to general and dictionary meanings, but interpreted based on the meanings and concepts corresponding to technical aspects of the present disclosure on the basis of the principle that the inventor is allowed to define terms appropriately for the best explanation.
Accordingly, the description made herein is just a preferred example for the purpose of illustration only, and is not intended to limit the scope of the present disclosure, so it should be understood that other equivalents and modifications may be made to the present disclosure without departing from the scope thereof.
In addition, in describing the present disclosure, a detailed description of related known elements or functions will be omitted herein when it is considered that the detailed description makes the subject matter of the present disclosure unclear.
Terms including ordinal numbers such as "first," "second," etc., may be used to distinguish one element from another element, but are not intended to limit the elements.
Throughout this application, when a portion is referred to as "comprising" or "includes" any element, it means that the portion may further include other elements without excluding other elements, unless specifically stated otherwise. Further, the term "processor" described in the present application refers to a unit that processes at least one function or work, which may be implemented by hardware, software, or a combination of hardware and software.
Further, throughout the application, when it is said that one portion is "connected" to another portion, it is not limited to the case where they are "directly connected", but also includes the case where other elements are interposed "indirectly connected".
Fig. 1 is a diagram illustrating a configuration of an over-discharge prevention apparatus according to an embodiment of the present disclosure, and fig. 2 is a diagram schematically illustrating a connection configuration of the over-discharge prevention apparatus, a battery pack, and a load according to an embodiment of the present disclosure.
First, referring to fig. 1 and 2, an
In addition, the over-discharge
The over-discharge
The battery pack includes a plurality of battery cells B electrically connected in series and/or parallel, the battery cells B being the smallest unit cells that diagnose a change in the electrode in response to a resistance. Here, the scope of the present disclosure also includes a case in which the battery pack includes only one unit cell.
The battery cell B is not particularly limited to any kind as long as it allows repeated charge and discharge. For example, the battery cell B may be a pouch-type lithium polymer battery.
The battery cell B may be electrically connected to various electronic devices through the output terminals Pack +, Pack-. The electronic device may be an electrically driven operating device. For example, the electronic device may be an electric vehicle, a hybrid electric vehicle, an unmanned aerial vehicle such as a drone, an Energy Storage System (ESS) included in an electrical grid, or a mobile device.
Thus, the battery unit B can output power to the output terminals Pack +, Pack-, and supply power to the load L provided in the electronic device.
For example, when the electronic device connected to the battery unit B is an unmanned aerial vehicle, the battery unit B can supply power to a motor as a load L provided in the unmanned aerial vehicle by outputting power to the output terminals Pack +, Pack-.
In addition, a first switch SW1 may be located on a first discharge path L1 that electrically connects battery cell B and output terminals Pack +, Pack-.
The first switch SW1 may output power from the battery cell B to the output terminal Pack +, Pack-, or cut off the output power.
The second switch SW2 is located on the first discharge path L1, and one end and the other end of the second switch SW2 may be electrically connected to the other end of the first switch SW1 and the output terminals Pack +, Pack-, respectively.
That is, on the first discharge path L1 electrically connecting the battery cell B and the output terminal Pack +, Pack-, the first switch SW1 may be disposed closer to the battery cell B than the second switch SW2, and the second switch SW2 may be disposed closer to the output terminal Pack +, Pack-than the
In addition, a current limiting resistor Rptc is located on the second discharge path L2, the second discharge path L2 electrically connects a first node N1 located between the first switch SW1 and the second switch SW2 and a second node N2 located between the second switch SW2 and the output terminals Pack +, Pack-, one end of the current limiting resistor Rptc may be electrically connected to the first node N1.
The third switch SW3 is located on the second discharge path L2, and one end and the other end of the third switch SW3 may be electrically connected to the other end of the current limiting resistor Rptc and the second node N2, respectively.
That is, on the second discharge path L2 electrically connecting the first node N1 and the second node N2, the current limiting resistor Rptc may be disposed closer to the first node N1 than the third switch SW3, and the third switch SW3 may be disposed closer to the second node N2 than the current limiting resistor Rptc.
Therefore, when the operating state of the first switch SW1 is controlled to the off state, the electric power output from the battery cell B to the output terminals Pack +, Pack-can be cut off regardless of the operating states of the second switch SW2 and the third switch SW 3.
When the operation state of the first switch SW1 is controlled to an on state, the operation state of the second switch SW2 is controlled to an off state, and the operation state of the third switch SW3 is controlled to an on state, the power output from the battery cell B may be output to the output terminal Pack +, Pack-through the second discharge path L2.
When the operation state of the first switch SW1 is controlled to the on state and the operation state of the second switch SW2 is controlled to the on state, the power output from the battery cell B may be output to the output terminal Pack +, Pack-through the first discharge path L1 regardless of the operation state of the third switch SW 3.
In addition, the current limiting resistor Rptc may be a Positive Temperature Coefficient (PTC) device whose variable resistance rapidly increases when a threshold Temperature is reached. Therefore, when a current flows through the current limiting resistor Rptc until a threshold temperature is reached, the current flowing through the second discharge path L2 may be cut off. That is, when a current flows through the current limiting resistor Rptc for a predetermined time, the power output from the battery cell B through the second discharge path L2 may be cut off.
The
To this end, the
The
When the measurement signal is received from the
The
The
First, a case will be described in which the
Fig. 3 is a diagram illustrating an example of switching control when a processor of an over-discharge prevention apparatus according to an embodiment of the present disclosure receives an output request signal.
When receiving the output request signal, the
Therefore, the electric power output from the battery cell B may be output to the load L through the first discharge path L1.
Thereafter, the
Here, the minimum operating voltage of the battery cell B may be a minimum voltage of the battery cell B that must be maintained so that the battery cell B is not deteriorated by overdischarge.
For example, the minimum operating voltage of the battery cell B may be "3V".
In addition, the
At this time, the
The
Thereafter, the
In addition, the
At this time, the
The
Thereafter, the
Finally, the
At this time, the
<
Vref=Vmin+IoRv+IoRi
Here, VrefIs a reference voltage, VminIs the minimum operating voltage of the battery cell, IoIs the discharge current of the battery cell, RvIs a temperature-based variable resistance of a current-limiting resistor, RiIs the temperature-based internal resistance of the battery cell.
The
More specifically, when the cell voltage of the battery cell B is equal to or lower than the reference voltage, the
That is, when the cell voltage of the battery cell B is equal to or lower than the reference voltage, the
Therefore, the discharge current of the battery cell B may flow at the current limiting resistor Rptc. Thereafter, as the discharge current continues to flow through the current limiting resistor Rptc, the temperature of the current limiting resistor Rptc increases, which may rapidly increase the resistance of the variable resistor.
Finally, as the discharge current flows, the current limiting resistor Rptc increases the variable resistance to approach infinity so that the discharge current flowing through the second discharge path L2 may be interrupted, which may gradually cut off the power output to the output terminals Pack +, Pack-.
According to this configuration of the present disclosure, when the voltage of the battery cell B is equal to or lower than the minimum operating voltage, the power output from the battery cell B to the load L is not immediately cut off, but the power may be gradually reduced in inverse proportion to the increased variable resistance as the discharge current flows into the current limiting resistor Rptc.
In addition, the
More specifically, the
Here, the current-time lookup table may be a lookup table in which the threshold resistance arrival time is matched such that when a current flows through the current limiting resistor Rptc, the variable resistance of the current limiting resistor Rptc becomes close to infinity according to the initial current value of the corresponding current.
For example, when the initial current value of the current initially flowing into the current limiting resistor Rptc is "5A" and the variable resistance of the current limiting resistor Rptc becomes close to infinity "10 seconds" after the current of "5A" starts to flow into the current limiting resistor Rptc, the initial current value of "5A" and the threshold resistance arrival time of "10 seconds" may be mapped and stored in the current-time lookup table. Here, the current-time lookup table may be stored in the
When the cell voltage of the battery cell B is equal to or lower than the reference voltage, the
Thereafter, the
The
By using the configuration of the present disclosure, the time at which the output of the battery cell B supplied to the load L is cut off can be predicted in advance so as to prevent overdischarge of the battery cell B.
In addition, the
The
In addition, the battery management system according to the present disclosure may include the above-described over-discharge prevention apparatus. In this way, overdischarge of the battery cell B managed by the battery management system can be prevented.
In addition, the electronic device according to the present disclosure may receive power from the battery cell B and include the above-described overdischarge prevention apparatus.
The above-described embodiments of the present disclosure need not be implemented by apparatuses and methods, but may also be implemented by a program for realizing functions corresponding to the configurations of the present disclosure or a recording medium having the program recorded thereon. Such a solution is easily implemented by those skilled in the art from the description of the above embodiments.
The present disclosure has been described in detail. It should be understood, however, that the detailed description and the specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the scope of the disclosure will become apparent to those skilled in the art from this detailed description.
In addition, a person skilled in the art may make many substitutions, modifications and changes to the above-described present disclosure without departing from the technical aspects of the present disclosure, the present disclosure is not limited to the above-described embodiments and drawings, and each embodiment may be selectively combined partially or entirely to allow various modifications.
(reference symbol)
B: battery unit
L: load(s)
100: device for preventing over-discharge
110: sensing unit
120: memory cell
130: processor with a memory having a plurality of memory cells
140: notification unit
SW 1: first switch
SW 2: second switch
SW 3: third switch
Rptc: current-limiting resistor