Patent Publication Number: US-2022216715-A1

Title: Device and method for preventing application of overcurrent

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Korean Patent Application No. 10-2019-0057089, filed on May 15, 2019, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a device and method for preventing application of overcurrent. 
     BACKGROUND ART 
     Recently, research and development of secondary batteries has been actively carried out. Here, the secondary batteries, which are rechargeable batteries, represent both conventional Ni/Cd batteries and Ni/MH batteries and up-to-date lithium ion batteries. The lithium ion batteries among the secondary batteries have the merit of high energy density compared to the conventional Ni/Cd batteries or Ni/MH batteries. Furthermore, the lithium ion batteries can be made small in size and light in weight, and are thus used as power sources of mobile devices. Moreover, since the scope of use of the lithium ion batteries extend to power sources of electric vehicles, the lithium ion batteries attract attention as next-generation energy storage media. 
     A secondary battery is typically used as a battery rack including a battery module in which a plurality of battery cells are connected in series and/or in parallel. The state and operation of the battery rack are managed and controlled by a battery management system. 
     A plurality of battery modules are connected in series or in parallel to constitute a battery rack, and a plurality of battery racks are connected in parallel to constitute a battery bank. Such a battery bank may be used as an energy storage system (ESS). 
     Regarding ESSs that are used in underdeveloped countries, application of overcurrent to ESS packs frequently occurs according to a charging environment, causing a short circuit of an ESS pack fuse or continuous occurrence of an alarm. Thus, it is often difficult to operate ESSs normally. 
     A normal charger charges an ESS by applying a current limited by a voltage suitable for an ESS pack. However, an abnormal charger causes a phenomenon in which overcurrent is applied from the charger to an ESS at the moment when the ESS is connected to the charger. 
     Although this is a problem of a charger, ESS packs which can be operated normally in such an environment are required. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Technical Problem 
     An object of the present invention is to provide an overcurrent application prevention device and method for making it possible to safely charge a battery without being affected by instantaneous overcurrent even when an abnormal charger is connected. 
     Technical Solution 
     An overcurrent application prevention device according to an embodiment is characterized by including a current sensor configured to measure a charging current applied from a charging unit to a battery; a bypass unit; a 3-terminal switch having a first end connected to charging unit and a second end that is switched to be connected to the battery or the bypass unit; a comparator configured to: receive the charging current from the current sensor and control the 3-terminal switch to be connected to the battery or to the bypass unit on the basis of a result of a comparison between the received charging current and a preset value. 
     The overcurrent application prevention device according to an embodiment is characterized in that the current sensor is a Hall sensor. 
     The overcurrent application prevention device according to an embodiment is characterized in that the 3-terminal switch is switched to be connected to the battery when the measured current value is smaller than the preset value, and is switched to be connected to the bypass unit when the measured current value is greater than the preset value. 
     The overcurrent application prevention device according to an embodiment is characterized in that the bypass unit includes a first resistor having a first terminal connected to the 3-terminal switch, a capacitor connected to a second terminal of the first resistor, and a second resistor connected in parallel to the capacitor. 
     The overcurrent application prevention device according to an embodiment is characterized in that when the 3-terminal switch is switched to be connected to the bypass unit by being controlled by the comparator, the charging current applied from the charging unit flows to the capacitor so that energy is stored in the capacitor. 
     The overcurrent application prevention device according to an embodiment is characterized in that when the 3-terminal switch is switched to be connected to the battery by being controlled by the comparator, the current flows to the second resistor due to the energy stored in the capacitor. 
     The overcurrent application prevention device according to an embodiment is characterized in that the bypass unit includes a first resistor having a first terminal connected to the 3-terminal switch, a battery cell connected to a second terminal of the first resistor, and a second resistor connected in parallel to the battery cell. 
     The overcurrent application prevention device according to an embodiment is characterized in that when the 3-terminal switch is switched to be connected to the bypass unit by being controlled by the comparator, the charging current applied from the charging unit flows to the battery cell so that energy is stored in the battery cell. 
     The overcurrent application prevention device according to an embodiment is characterized in that when the 3-terminal switch is switched to be connected to the battery by being controlled by the comparator, the current flows to the second resistor due to the energy stored in the battery cell. 
     An overcurrent application prevention method according to an embodiment of the present invention is characterized by including the steps of: measuring a charging current applied from a charging unit to a battery; amplifying a value of the measured current; comparing the amplified value with a preset value; and controlling a 3-terminal switch so that the charging current is bypassed when the amplified value is greater than the preset value, and controlling the 3-terminal switch so that the charging current flows to the battery when the amplified value is smaller than the preset value. 
     The overcurrent application prevention method according to an embodiment of the present invention is characterized in that the step of measuring the current is performed by a Hall sensor. 
     The overcurrent application prevention method according to an embodiment of the present invention is characterized in that when the 3-terminal switch is controlled so that the charging current applied from the charging unit is bypassed, the current flows to a capacitor so that energy is stored in the capacitor. 
     The overcurrent application prevention method according to an embodiment of the present invention is characterized in that when the 3-terminal switch is controlled so that the charging current applied from the charging unit flows to the battery, the battery is charged, and the current flows to a resistor connected in parallel to the capacitor due to the energy stored in the capacitor. 
     The overcurrent application prevention method according to an embodiment of the present invention is characterized in that when the 3-terminal switch is controlled so that the charging current applied from the charging unit is bypassed, the current flows to a battery cell so that energy is stored in the battery cell. 
     The overcurrent application prevention method according to an embodiment of the present invention is characterized in that when the 3-terminal switch is controlled so that the charging current applied from the charging unit flows to the battery, the battery is charged, and the current flows to a resistor connected in parallel to the battery cell due to the energy stored in the battery call. 
     Effects of the Invention 
     The present invention has the effect of safely charging a battery without being affected by instantaneous overcurrent even when an abnormal charger is connected. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a configuration diagram illustrating an overcurrent application prevention device according to an embodiment of the present invention. 
         FIG. 2  is a diagram illustrating an implementation example of an overcurrent application prevention device according to an embodiment of the present invention. 
         FIG. 3  is a flowchart illustrating an overcurrent application prevention method according to an embodiment of the present invention. 
         FIG. 4  is a diagram illustrating an installation example of an overcurrent application prevention device according to another embodiment of the present invention. 
         FIG. 5  is a configuration diagram illustrating an overcurrent application prevention device according to another embodiment of the present invention. 
         FIG. 6  is a configuration diagram illustrating an overcurrent application prevention device according to another embodiment of the present invention. 
         FIG. 7  is a flowchart illustrating an overcurrent application prevention method according to another embodiment of the present invention. 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
     Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, it should be understood that the present invention is not limited to specific embodiments, but rather includes various modifications, equivalents and/or alternatives of various embodiments of the present invention. Regarding description of the drawings, like reference numerals may refer to like elements. 
     The terminology used herein is only used for describing specific embodiments and is not intended to limit the scope of other embodiments. The terms of a singular form may include plural forms unless otherwise specified. The terms used herein, including technical or scientific terms, have the same meanings as understood by those skilled in the art. Commonly-used terms defined in a dictionary may be interpreted as having meanings that are the same as or similar to contextual meanings defined in the related art, and should not be interpreted in an idealized or overly formal sense unless otherwise defined explicitly. Depending on cases, even the terms defined herein should not be such interpreted as to exclude various embodiments of the present invention. 
     The terms “first”, “second”, “A”, “B”, “(a)”, “(b)” and the like may be used herein to describe elements of the embodiments of the present invention. However, the terms are only used to distinguish one element from other elements, and the attributes or order of the elements are not limited by the terms. It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element, or other intervening elements may “connected” or “coupled” therebetween. 
       FIG. 1  is a configuration diagram illustrating an overcurrent application prevention device according to an embodiment of the present invention. 
     According to the prior art, a negative temperature coefficient (NTC) thermistor is connected to a charging path to consume energy by increasing a resistance value when overcurrent flows, thereby preventing abnormal overcurrent from being applied to an ES S. This configuration makes it possible to efficiently consume energy in an overcurrent situation, but causes a voltage drop and heat generation due to a resistance value of an NTC itself even in a normal operation state. In order to supplement this conventional configuration, the overcurrent application prevention device of the present invention monitors through a Hall sensor to bypass a current having at least a reference value when the current having at least the reference value is applied, so as to block overcurrent from being directly applied to an ESS pack. 
     In detail, an overcurrent application prevention device  10  of the present invention includes a current sensor  100 , an amplifier  101 , a comparator  102 , a 3-terminal switch  104 , and a bypass unit  106 . 
     The current sensor  100  measures a current flowing between one terminal of a charging unit  20  and the 3-terminal switch  104 . 
     A current value measured by the current sensor  100  is transferred to the amplifier  101 . The amplifier  101  that has received the measured current value from the current sensor  100  amplifies the measured current value. 
     The amplifier  101  transfers the amplified current value to the comparator  102 . Here, the amplifier  101  may be omitted, and the measured current value may be directly transferred to the comparator  102 . 
     The comparator  102  receives the amplified current value from the amplifier and compares the amplified current value with a preset value. The comparator  102  may compare the amplified current value with the preset value to control the 3-terminal switch  104  to contact the bypass unit  106  when the amplified current value is greater than the preset value, and may compare the amplified current value with the preset value to control the 3-terminal switch  104  to contact one terminal side of a battery  30  when the amplified current value is smaller than the preset value. 
     One end of the 3-terminal switch  104  is electrically connected to the charging unit  20 , and another end is connected to one end of the battery  30  or one end of the bypass unit  106  according to a result value from the comparator  102 . 
     As described above, the 3-terminal switch  104  is connected to the side of the bypass unit  106  when the current value (or amplified value) measured by the current sensor is greater than the preset value, and is connected to the side of the battery  30  when the current value (or amplified value) measured by the current sensor is smaller than the preset value. 
     When the 3-terminal switch  104  is connected to the side of the bypass unit  106 , a current applied from the charging unit  20  flows to the bypass unit  106  and is thus not applied to the battery  30 , thereby protecting the battery  30  from overcurrent. 
     When the 3-terminal switch  104  is connected to the side of the battery  30 , the current applied from the charging unit  20  is applied to the battery  30 , and thus the battery  30  is charged safely. 
       FIG. 2  is a diagram illustrating an implementation example of an overcurrent application prevention device according to an embodiment of the present invention. 
     The overcurrent application prevention device  10  includes a current sensor  204 , an amplifier  206 , a comparator  208 , a 3-terminal switch  210 , a first resistor  212 , a capacitor  214 , and a second resistor  216 . 
     The current sensor  204  measures a current flowing between a first terminal  202  of a charging unit  200  and the 3-terminal switch  210 . The current sensor  204  may be a Hall sensor, which does not consume a current output from the charging unit  200  or does not cause a voltage drop due to resistance. A value of the current output from the charging unit  200  is measured by the Hall sensor  204 . 
     The current value measured by the Hall sensor  204  is transferred to the amplifier  206 . The amplifier  206  that has received the measured current value from the Hall sensor  204  amplifies the current value. Here, the amplifier  206  may be omitted, and the measured current value may be directly transferred to the comparator  208 . 
     The comparator  208  receives the amplified current value from the amplifier and compares the amplified current value with a preset value. The comparator  208  may compare the amplified current value with the preset value to control the 3-terminal switch  210  to contact the first resistor  212  when the amplified current value is greater than the preset value, and may compare the amplified current value with the preset value to control the 3-terminal switch  210  to contact one terminal side  218  of a battery  220  when the amplified current value is smaller than the preset value. 
     One end of the 3-terminal switch  210  is connected to the first terminal  202  of the charging unit  200 , and another end is connected to the first terminal  218  of the battery  220  or the first resistor  212  according to a result value from the comparator  208 . Further, the charging unit  200  is also connected to a second terminal  222  of the battery and to the capacitor  214 . 
     As described above, the 3-terminal switch  210  is connected to the side of the first resistor  212  when the current value (or amplified value) measured by the current sensor is greater than the preset value, and is connected to the side of the first terminal  218  of the battery  220  when the current value (or amplified value) measured by the current sensor is smaller than the preset value. 
     When the 3-terminal switch  210  is connected to the first resistor  212 , the current applied from the charging unit  200  is applied to the first resistor  212  and dropped to a voltage suitable for a battery module for bypass, and energy is stored in the capacitor  214 . Further, the capacitor  214  may be replaced with a battery cell  214 . 
     When the 3-terminal switch  210  is connected to the side of the first terminal  218  of the battery  220 , the current applied from the charging unit  200  is applied to the battery  220 , and thus the battery  220  is charged safely. Furthermore, when the 3-terminal switch  210  is connected to the first terminal  218  of the battery  220  or is not connected to the first resistor  212 , energy stored in the capacitor  214  is discharged by the second resistor  216 . 
     Since the energy stored in the capacitor  214  is discharged as described above, when overcurrent is applied from the charging unit  200  thereafter, the current is applied and thus energy may be stored. That is, the capacitor  214  stores energy when overcurrent is applied, and discharges energy while overcurrent is not applied. Although the above descriptions are given using the capacitor as an example, a battery cell or a battery module rather than the capacitor may be used as the same corresponding configuration. The battery module or the battery cell may be replaced with a configuration having the same function as the capacitor in an embodiment of the present invention or another embodiment. 
       FIG. 3  is a flowchart illustrating an overcurrent application prevention method according to an embodiment of the present invention. 
     A current applied from the charging unit  200  is measured by the Hall sensor  204  (S 300 ). The hall sensor  204  may measure a current without consuming a current output from the charging unit  200  or causing a voltage drop due to resistance. 
     The current value measured by the Hall sensor  204  is transferred to the amplifier  206 . The amplifier  206  that has received the measured current value from the Hall sensor  204  amplifies the current value (S 302 ). Here, the amplifier  206  may be omitted, and the measured current value may be directly transferred to the comparator  208 . 
     The comparator  208  receives the amplified current value from the amplifier and compares the amplified current value with a preset value (S 304 ). The comparator  208  may compare the amplified current value with the preset value to control the 3-terminal switch  210  to contact the first resistor  212  when the amplified current value is greater than the preset value, and may compare the amplified current value with the preset value to control the 3-terminal switch  210  to contact one terminal side of the battery  220  when the amplified current value is smaller than the preset value. 
     The comparator  208  compares the amplified current value with the preset value to determine whether the amplified current value is greater than the preset value (S 306 ). When the amplified current value is greater than the preset value, the comparator  208  controls the 3-terminal switch  210  to contact the first resistor  212 . That is, the comparator  208  switches the 3-terminal switch to a bypass unit (S 308 ). 
     When the 3-terminal switch  210  is connected to the first resistor  212 , the current applied from the charging unit  200  is applied to the first resistor  212  and dropped to a voltage suitable for a battery module for bypass, and energy is stored in the capacitor  214  (S 310 ). 
     When the amplified current value is smaller than the preset value, the 3-terminal switch  210  is connected to the side of the first terminal  218  of the battery  220  (S 312 ). When the 3-terminal switch  210  is connected to the side of the first terminal  218  of the battery  220 , the current applied from the charging unit  200  is applied to the battery  220 , and thus the battery  220  is charged safely (S 316 ). 
     Furthermore, when the 3-terminal switch  210  is connected to the first terminal  218  of the battery  220  or is not connected to the first resistor  212 , energy stored in the capacitor  214  is discharged by the second resistor  216  (S 314 ). 
       FIG. 4  is a diagram illustrating an installation example of an overcurrent application prevention device according to another embodiment of the present invention. 
     An overcurrent application prevention device  402  is installed between a charging unit  400  and a battery  404 . A connected spring center axis of the overcurrent application prevention device  402  is configured with a fuse and is cut when a current increases, and thus the spring is compressed and a contact surface of a current transfer part increases, thus increasing resistance. 
     Detailed descriptions will be given with reference to  FIG. 5 . 
       FIG. 5  is a configuration diagram illustrating the overcurrent application prevention device  402  according to another embodiment of the present invention. 
     The overcurrent application prevention device  402  includes a current transfer part  502 , through which a current flows and which includes a plurality of metal (conductor) rods connected in a rail form so as to have a length that reduces or extends, a spring part  504  connected to the current transfer part, and a fuse part  506 , which supports the spring part  504  in an extended state. When a transferred current has at least a fixed reference value, the overcurrent application prevention device  402  generates heat, and thus the fuse part  506  is cut. When the fuse part  506  is cut, a support portion in which the fuse part supports between one ends of the spring part  504  disappears, and thus the spring part  504  restores to a compressed state, thus extending the current transfer part  502 . 
     Any conductor that allows a flow of current may be used as the current transfer part  502 . Since a plurality of conductor rods are connected to each other by rail or the like in the current transfer part  502 , the current transfer part  502  is capable of performing a motion of reducing and extending the length thereof. When an applied current has at least a fixed value, the overcurrent application prevention device  402  generates heat, and thus the fuse part  506  that supports the spring part  504  is cut. When the fuse part  506  is cut, the spring part  504  that was supported by the fuse part  506  restores to a compressed state, thus extending the current transfer part  502 . Since the current transfer part  502  is extended, the contact surface increases, thus increasing resistance. When the resistance of the current transfer part  502  increases, a current applied from a charging unit is transferred to a battery after consuming energy while passing through the current transfer part  502 , and thus the battery may be prevented from being damaged by overcurrent. 
       FIG. 6  is a configuration diagram illustrating an overcurrent application prevention device according to another embodiment of the present invention. 
     The overcurrent application prevention device includes a current sensor  602 , a capacitor  604 , an amplifier  606 , and a comparator  608 . 
     The current sensor  602  may be a Hall sensor, which does not consume a current output from a charging unit  600  or does not cause a voltage drop due to resistance. 
     The current sensor  602  measures a current which is output from the charging unit  600  and flows to the side of a battery  610 . The current value measured by the current sensor  602  is transferred to the amplifier  606 . The amplifier  606  that has received the measured current value from the current sensor  602  amplifies the measured current value. 
     Here, the amplifier  606  may be omitted, and the measured current value may be directly transferred to the comparator  608 . 
     The comparator  608  receives the amplified current value from the amplifier and compares the amplified current value with a preset value. The comparator  608  compares the amplified current value with the preset value to control a 3-terminal switch  609  to connect to a terminal  611  so as to connect the battery  610  and the capacitor  604  when the amplified current value is greater than the preset value, and compares the amplified current value with the preset value to control the  3 -terminal switch  609  to connect to a terminal  612  so as to safely charge the battery  610  when the amplified current value is smaller than the preset value. 
       FIG. 7  is a flowchart illustrating an overcurrent application prevention method according to another embodiment of the present invention. 
     A current applied from the charging unit  600  is measured by the Hall sensor  602  (S 700 ). The hall sensor  602  may measure a current without consuming a current output from the charging unit  600  or causing a voltage drop due to resistance. 
     The current value measured by the Hall sensor  602  is transferred to the amplifier  606 . The amplifier  606  that has received the measured current value from the Hall sensor  602  amplifies the current value (S 702 ). Here, the amplifier  606  may be omitted, and the measured current value may be directly transferred to the comparator  608 . 
     The comparator  608  receives the amplified current value from the amplifier  606  and compares the amplified current value with a preset value (S 704 ). Here, the amplifier  606  may be omitted, and the measured current value may be directly transferred to the comparator  608 . 
     The comparator  608  determines whether the amplified current value from the amplifier  606  is greater than the preset value (S 706 ). The comparator  608  controls the 3-terminal switch  609  to contact the terminal  611  when the amplified current value is greater than the preset value (S 712 ), and controls the 3-terminal switch  609  to contact the terminal  612  when the amplified current value is smaller than the preset value (S 708 ). 
     When the 3-terminal switch  609  is connected to the terminal  612 , a current is applied from the charging unit  600  to charge the battery  610  (S 710 ). 
     In the present disclosure, the term “an embodiment” or various modified expressions thereof indicate that specific features, structures, and characteristics related to this embodiment are included in at least one embodiment of the principle of the present invention. Therefore, the term “in an embodiment” and various modified expressions thereof should not be construed as indicating the same embodiment. 
     All of the embodiments and conditional examples disclosed herein are intended to assist those skilled in the art with understanding the principle and concept of the present invention, and, thus, those skilled in the art could understand that the present invention can be implemented in modified forms without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed herein should be considered to be not limitative but illustrative. The scope of the present invention should be defined not by the above description but by the claims, and all differences that fall within the same scope as the claims should be construed as being covered by the present invention.