Patent Publication Number: US-2023163606-A1

Title: Battery management system and method of managing battery using the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. §119 to Korean Patent Application No. 10-2021-0163833, filed on Nov. 24, 2021, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The following disclosure relates to a battery management system capable of preventing damage to a battery, and a method of managing a battery using the same. 
     BACKGROUND 
     Hybrid vehicles, electric vehicles, or the like, are provided with batteries such as nickel hydride batteries or lithium ion batteries. Such a vehicle is provided with a battery management system (BMS) in order to prevent damage to the battery in charging and discharging processes of the battery and manage a lifespan of the battery. 
     When an error such as an overcurrent or an overvoltage occurs at the time of charging the battery, the BMS perform diagnosis and detection of the error for a predetermined time. When the diagnosis and the detection of the error by the BMS are completed, a relay of the battery is cut off by a fuse provided in the vehicle. 
     However, even after the error occurs, an overcurrent or overvoltage state continues for the predetermined time for the purpose of the diagnosis and the detection of the error by the BMS, which causes damage to the battery. In a case where the battery is repeatedly damaged, it affects stability of a battery cell. 
     In addition, in a case where the overcurrent or the overvoltage instantaneously occurs, the relay of the battery is not cut off by the fuse, such that stress is generated in the battery and is accumulated. 
     SUMMARY 
     The present invention has been made in order to solve the problems as described above. 
     An object of the present invention is to prevent damage to a battery due to an overcurrent or an overvoltage while a battery management system (BMS) diagnoses a failure of the battery. 
     Another object of the present invention is to prevent damage to a battery due to an overcurrent or an overvoltage that instantaneously occurs in the battery. 
     Objects of the present invention are not limited to the objects mentioned above, and other objects that are not mentioned may be obviously understood by those skilled in the art from the following description. 
     In one general aspect, a battery management system includes: a battery management system (BMS) monitoring a battery, turning on/off a main relay connected to an output of the battery, and receiving power through a power switch; a sensor unit measuring a state of the battery to generate battery state information; and a controller configured to receive the battery state information from the sensor unit, detect an occurrence of a failure event of the battery based on the battery state information, control the main relay based on a maintenance time of the failure event and the number of times of the occurrence of the failure event, and provide a turn on/off command to the power switch. 
     The battery state information may include at least one of voltage information, current information, and temperature information of the battery. 
     The controller may determine that the failure event has occurred when a measured voltage of the battery exceeds a reference voltage V max  or a measured temperature of the battery exceeds a reference temperature T max . 
     When the maintenance time of the failure event is longer than a reference time T 1d , the controller may diagnose the failure event and determine whether or not the battery is abnormal for a predetermined time T 2 . 
     The controller may turn off the main relay when the predetermined time T 2  is longer than a reference time T 2th  greater than T 1a . 
     In a case where the predetermined time T 2  is equal to or shorter than a reference time T 2th  greater than T 1d , when a current of the battery is I0 that is a predetermined reference, the controller may provide a turn-off command to the power switch. 
     In a case where the predetermined time T 2  is equal to or shorter than a reference time T 2th  greater than T 1d , when a current of the battery is greater than I0 that is a predetermined reference, the controller may turn off the main relay, and provide a turn-on maintenance command to the power switch. 
     The controller may accumulatively increase a stress index of the battery when the failure event occurs, and may turn off the main relay when a duration of the failure event is equal to or shorter than a reference time T 1a  and the stress index of the battery is greater than a reference set value S th . 
     The controller may determine that the failure event has occurred when a measured voltage of the battery exceeds a reference voltage V max  or a measured temperature of the battery exceeds a reference temperature T max , and the stress index of the battery may be a count value of the number of times the measured voltage of the battery exceeds the reference voltage V max  or the measured temperature of the battery exceeds the reference temperature T max . 
     The controller may determine that the failure event has occurred when a measured voltage of the battery exceeds a reference voltage V max  or a measured temperature of the battery exceeds a reference temperature T max , and the stress index of the battery may be a degree to which the measured voltage of the battery exceeds the reference voltage V max  or a degree to which the measured temperature of the battery exceeds the reference temperature T max . 
     In another general aspect, a method of managing a battery using a battery management system (BMS) monitoring the battery, turning on/off a main relay connected to an output of the battery, and receiving power through a power switch includes: measuring battery state information, detecting an occurrence of a failure event of the battery based on the battery state information, controlling the main relay based on a maintenance time of the failure event and the number of times of the occurrence of the failure event, and turning on/off the power switch. 
     The battery state information may include at least one of voltage information, current information, and temperature information of the battery. 
     It may be determined that the failure event has occurred when a measured voltage of the battery exceeds a reference voltage V max  or a measured temperature of the battery exceeds a reference temperature T max . 
     The method may further include: accumulatively increasing a stress index of the battery when the failure event occurs, and turning off the main relay when a duration of the failure event is equal to or shorter than a reference time T 1a  and the stress index of the battery is greater than a reference set value S th . 
     The method may further include: when the maintenance time of the failure event is longer than a reference time T 1d , diagnosing the failure event, and determining whether or not the battery is abnormal for a predetermined time T 2 . 
     The method may further include turning off the main relay when the predetermined time T 2  is longer than a reference time T 2th  greater than T 1a . 
     The method may further include: in a case where the predetermined time T 2  is equal to or shorter than a reference time T 2th  greater than T 1d , when a current of the battery is I0 that is a predetermined reference, turning off the power switch, and when the current of the battery is longer than I0 that is the predetermined reference, turning off the main relay and maintaining turn-on of the power switch. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic block diagram illustrating a battery management system according to an embodiment of the present invention. 
         FIG.  2    is a flowchart illustrating a flow of a method of managing a battery according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF MAIN ELEMENTS 
     
         
           10 : battery management system 
           100 : battery 
           300 : main relay 
           400 : sensor unit 
           500 : BMS 
           700 : power switch 
           800 : controller 
       
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, when it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description will be omitted. In addition, although exemplary embodiments of the present invention will be described below, the scope of the present invention is not limited thereto, and may be variously modified by those skilled in the art. 
       FIG.  1    is a schematic block diagram illustrating a battery management system  10  according to an embodiment of the present invention. The battery management system  10  is provided in order to monitor a battery provided in a vehicle. Referring to  FIG.  1   , the battery management system  10  includes a battery  100 , an inverter  200 , a sensor unit  400 , a battery management system (BMS)  500 , a power switch  700 , and a controller  800 . 
     The battery  100  is a battery provided in a vehicle such as a hybrid vehicle, an electric vehicle, or a hydrogen fuel cell vehicle. In an example, the battery  100  may be a secondary battery such as a nickel hydride battery or a lithium ion battery. In an example, the battery  100  may be a battery pack configured in the form of one pack by connecting cells to each other in series according to a required capacity. The inverter  200  converts direct current (DC) power of the battery into alternating current (AC) power for driving a motor. 
     The sensor unit  400  measures a state of the battery  100  to generate battery state information. In an example, the battery state information may include at least one of voltage information, current information, and temperature information of the battery  100 . In an example, the sensor unit  400  includes a voltage sensor measuring a voltage of the battery  100 , a current sensor measuring a current of the battery  100 , and a temperature sensor measuring a temperature of the battery  100 . 
     The BMS  500  turns on/off a main relay  300  connected to an output of the battery  100 , and receives power through the power switch  700 . In addition, the BMS  500  monitors the state of the battery  100 . In an example, the BMS  500  operates all the time while the vehicle is driving, and operates for charging (direct charging by a charger, a solar system, etc.) while the vehicle is not driving. The BMS  500  operates all the time in order to prevent ignition, explosion or the like of the battery  100  at the time of charging and discharging of the battery  100 . The BMS  500  operates in a state in which the vehicle is started. The BMS  500  receives the battery state information from the sensor unit  400 , and controls turn-on/off of the main relay  300  based on the received battery state information. 
     In addition, the BMS  500  may be implemented to calculate a state of charge (SOC) of the battery  100  for prediction of a travelable distance of the vehicle, predict a state of health estimation (SOH) for replacement of the battery  100 , perform an alarm and prior safety protection for safe operation of a battery system, perform diagnosis of the battery system, or maintain an optimum temperature of the battery  100  through control of a cooling fan. 
     The controller  800  is configured to be able to communicate with the BMS  500 . The controller  800  receives the battery state information from the sensor unit  400 , and controls the main relay  300  and the power switch  700 . In an example, the controller  800  is configured to communicate with the sensor unit  400  through the BMS  500 . Optionally, the controller  800  is configured to be able to communicate directly with the sensor unit  400 . The controller  800  may detect the occurrence of a failure event of the battery  100  based on the battery state information, control the main relay  300  based on a maintenance time of the failure event and the number of times of the occurrence of the failure event, and provide a turn on/off command to the power switch. 
     Hereinafter, a method of managing a battery according to the present invention will be described in detail with reference to  FIG.  2   . 
     While the vehicle is started, the controller  800  continuously determines whether or not a failure event has occurred in the battery  100 . In an example, the controller  800  determines whether or not a measured voltage of the battery  100  exceeds a reference voltage V max  (V&gt;V max ) or a measured temperature of the battery  100  exceeds a reference temperature T max  (T&gt;T max ) and whether or not the battery  100  is in a normal state on the basis of the maintenance time T 1  of the failure event. In a case where the measured voltage V of the battery  100  exceeds the reference voltage V max  or the measured temperature T of the battery  100  exceeds the reference temperature T max , and a time T 1  for which the failure event occurs and continues is longer than a reference time lid, the controller  800  determines that the battery  100  is in an abnormal state (S 100 ). 
     First, a case where it is determined that the battery  100  is in an abnormal state will be described. When maintenance time T 1  of the failure event is longer than the reference time T 1d , the BMS  500  diagnoses the failure event and determines whether or not the battery is abnormal for a predetermined time T 2 . The controller  800  determines whether or not the time T 2  is longer than a reference time T 2th  (S 120 ). 
     The controller  800  causes the BMS  500  to turn off the main relay  300  when T 2  is longer than the reference time T 2th . In this case, a value of T 2th &gt;T 1d  is provided. This prevents a time for which the BMS  500  diagnoses the failure event from becoming excessive long by turning off the main relay  300  when a predetermined time elapses after the failure event has occurred. Accordingly, a phenomenon in which the battery  100  is damaged or is ignited or exploded due to an overvoltage, an overtemperature or the like while the BMS  500  detects and diagnoses the failure event for a long time may be prevented. 
     The controller  800  determines a current value of the battery  100  (S 140 ) in a case where T 2  is equal to or shorter than the reference time T 2th . When a current of the battery  100  is I0, which is a predetermined reference, the controller  800  may provide a turn-off command to the power switch  700 . In an example, I0 is a case where a current value of the current flowing through the battery  100  is 0. In a case where the current value of the current flowing through the battery  100  is 0, the controller  800  turns off the power switch  700 . Accordingly, power of the BMS  500  is turned off. The controller  800  turns off the power switch  700  itself, and thus, a problem occurring because a current is passed to the battery  100  and other components connected to the BMS  500  is prevented. 
     In a case where T 2  is equal to or shorter than the reference time T 2th , the controller  800  may turn off the main relay  300  and provide a turn-on maintenance command to the power switch  700  when the current of the battery  100  is greater than I0, which is the predetermined reference. In an example, a case where the current of the battery  100  is greater than I0 is a case where the current value of the battery  100  exceeds 0. 
     Next, a case where it is determined that the battery  100  is in a normal state will be described. When a condition in which the measured voltage of the battery  100  exceeds the reference voltage V max  or the measured temperature of the battery  100  exceeds the reference temperature T max  and a condition in which a time T 1  for which the failure event occurs and continues is longer than the reference time T 1d  are not satisfied, the controller  800  determines that the battery  100  is in a normal state (S 100 ). 
     In a case where it is determined that the battery  100  is in the normal state, it is first determined whether or not the failure event has occurred. Whether or not the failure event has occurred is determined on the basis of whether or not the measured voltage of the battery  100  exceeds the reference voltage V max  (V&gt;V max ) or the measured temperature of the battery  100  exceeds the reference temperature T max  (T&gt;T max ) (S 160 ). A case where the failure event has occurred is a case where the measured voltage of the battery  100  exceeds the reference voltage V max  (V&gt;V max ) or the measured temperature of the battery  100  exceeds the reference temperature T max  (T&gt;T max ). 
     In a case where the failure event has not occurred, the controller  800  issues a maintenance command to the BMS  500  so that the main relay  300  may be maintained. 
     In a case where the failure event has occurred, the controller  800  determines whether or not a stress index S of the battery  100  is greater than a reference set value S th . In a case the stress index S of the battery  100  is greater than the reference set value S th , the controller  800  turns off the main relay  300 . In a case where the stress index S of the battery  100  is not greater than the reference set value S th , the controller  800  maintains a turn-on state of the main relay  300 , but accumulatively increases the stress index of the battery  100 . 
     In an example, the stress index S of the battery  100  is a count value Cntn of the number of times the measured voltage of the battery  100  exceeds the reference voltage V max  or the measured temperature of the battery  100  exceeds the reference temperature T max , and the reference value S th  may be a reference count value Cnt th . Accordingly, as illustrated in  FIG.  2   , when a value Cnt n  is greater than the reference value Cnt th , the controller  800  turns off the main relay  300 . 
     Alternatively, the stress index S of the battery may be provided as a degree to which the measured voltage of the battery  100  exceeds the reference voltage V max  or a degree to which the measured temperature of the battery  100  exceeds the reference temperature T max . Alternatively the stress index of the battery  100  may be provided as another condition that may adversely affect the battery  100  in a case where the number of times of occurrences is accumulated. An accumulatively increased value may be initialized by a user or may be initialized in a case where a specific condition is satisfied by a separate logic. 
     In a case where the value Cnt n  is not greater than the reference value Cnt th , the controller  800  issues a maintenance command to the BMS  500  so that the main relay  300  may be maintained in the turn-on state. In addition, a count value is accumulated. 
     Therefore, even though a duration of the failure event is equal to or shorter than the reference time T 1d , when the stress index S of the battery  100  is greater than the reference set value S th , the main relay  300  is turned off, such that a phenomenon in which an effect of an overvoltage or an overtemperature that occurs instantaneously is accumulated to damage to the battery  100  may be prevented. 
     According to an embodiment of the present invention, it is possible to prevent damage to a battery due to an overcurrent or an overvoltage while a BMS diagnoses a failure of the battery. 
     According to an embodiment of the present invention, it is possible to prevent damage to a battery due to an overcurrent or an overvoltage that instantaneously occurs in the battery. 
     Meanwhile, effects of the present invention are not limited to the above-mentioned effects, and various effects may be included within the range apparent to those skilled in the art from a description to be described later. 
     The technical spirit of the present invention has been described only by way of example hereinabove, and the present invention may be variously modified, altered, and substituted by those skilled in the art to which the present invention pertains without departing from essential features of the present invention. Accordingly, embodiments disclosed in the present invention and the accompanying drawings do not limit but describe the spirit of the present invention, and the scope of the present invention is not limited by these embodiments and accompanying drawings. The scope of the present invention should be interpreted by the following claims, and it should be interpreted that all spirits equivalent to the following claims fall within the scope of the present invention.