KR-20260062878-A - ON-LINE REAL-TIME LI-ION BATTERY DEGRADATION FACTOR AND RISK DETERMINATION METHOD UNDER HIGH-SPEED EXCITATION VOLTAGE CONDITIONS

Abstract

The present invention relates to a method for determining online real-time battery degradation factors and risk under high-speed excitation voltage conditions, and more specifically, to a method for determining online real-time battery degradation factors and risk under high-speed excitation voltage conditions for diagnosing/predicting real-time battery degradation status and thermal runaway risk under high-speed excitation voltage conditions.

Inventors

• 정붕익
• 정인석
• 오승찬
• 류준희
• 박찬
• 최원균

Assignees

• (주) 테크윈

Dates

Publication Date

20260507

Application Date

20251029

Priority Date

20241029

Claims (7)

1. As a method for determining the soundness of the battery, A method for determining the soundness of a battery, which measures the voltage and current of a battery under excitation voltage conditions and determines the degradation or risk level of the battery based on waveform information of the measured voltage and current.
2. In paragraph 1, As a method for determining battery degradation, Step of measuring the voltage and current of the battery; A step of calculating the voltage peak value and the current peak value, respectively, based on the measured voltage and current values; A step of calculating the omnic resistance (R ohm ) and solid electrolyte interface resistance (R SEI ), which are battery internal resistance elements, based on the polarization voltage and peak value in the measured current and voltage changes; and A method for determining the condition of a battery, comprising the step of determining battery degradation by comparing the calculated internal resistance change trend information with the normalized polarization voltage change trend information and a set threshold value.
3. In paragraph 2, The step of calculating the internal resistance based on the measured current and voltage changes and peak values is: Calculate the battery reference voltage and omnic resistance according to the following mathematical formulas [1] and [2], and [Mathematical Formula 1] [Mathematical Formula 2] Here, : Connect the discharged capacitor to the battery output, at the start of charging, : Start time for calculating internal battery omnic resistance component (avoiding initial inductive transient period), : Omnic regression window for measuring voltage changes caused by internal omnic resistance components of the battery, and : This is the average interval prior to the start of capacitor charging for reference voltage measurement, and A method for determining the condition of a battery, comprising the step of determining that the battery has deteriorated when the omnic resistance deviates from the above threshold.
4. In paragraph 3, As a method for determining the risk level of a battery, Step of measuring the voltage and current of the battery; A step of analyzing the phase delay pattern of the polarization voltage, excluding the voltage change component caused by the omnic resistance component measured in paragraph 3, based on the measured voltage and current values; A method for determining the condition of a battery, comprising: a step of analyzing a solid electrolyte interface resistance component through an analyzed phase delay pattern; and a step of determining the risk level of the battery by comparing it to a set threshold value.
5. In paragraph 4, The steps for analyzing the phase delay pattern are: Based on changes in current and voltage output patterns, omnic components in the overall voltage change waveform Polarization voltage excluding the voltage change component caused by ( By analyzing the change trend of ), the delay characteristics occurring according to the parallel configuration of R SEI and C SEI in the battery equivalent model ( A step of calculating the solid electrolyte interfacial resistance (RSEI) value according to the following mathematical formulas [3] to [7] through comparison with ), and [Mathematical Formula 3] [Mathematical Formula 4] : Time of the lowest peak change in transient voltage v(t) [Mathematical Formula 5] [Mathematical Formula 6] [Mathematical Formula 7] The phase delay characteristic is normalized by the root mean square error of the polarization voltage change according to the following mathematical formulas [8], [9], and [Mathematical Formula 8] [Mathematical Formula 9] A method for determining the condition of a battery, comprising the step of determining a dangerous situation in which the battery may enter a thermal runaway stage due to damage to the separator, including the initial point of internal temperature rise in the pre-thermal runaway stage, the internal temperature rise section, and the thermal runaway stage when an abnormal change is detected in the solid electrolyte interface resistance component and normalized phase delay state information, including information on the slope of change of omnic resistance.
6. As a device for determining battery condition health under excitation voltage conditions, The here voltage generating circuit is, A switch element connected to one end of the above battery; An inductor connected in series with one end of the above switch element; A diode connected in series with the above inductor; A capacitor connected in series with the above diode; and A battery condition health determination device including a resistor connected in parallel with the above capacitor.
7. In paragraph 6, The processor, By turning off the above switch element, the voltage charged in the capacitor load to generate the excitation voltage in the battery thrust is discharged through the resistor, and After a predetermined period of time has elapsed, the switch element is turned on to charge the battery power into the capacitor, and A device for measuring the current and voltage of the battery during the charging period with the discharged capacitor load.

Description

Online Real-Time Li-ion Battery Degradation Factor and Risk Determination Method Under High-Speed Excitation Voltage Conditions The present invention relates to a secondary battery condition diagnosis technology, and more specifically, to a method and apparatus for determining the condition health of a battery in real time, including the risk of degradation and thermal runaway, by synchronously measuring voltage and current waveforms of battery terminals under conditions where a short impulse-shaped excitation voltage is applied to the battery, and analyzing voltage peaks, current peaks, and voltage-current phase delay characteristics from the waveforms to estimate changes in internal omnic resistance and separator (RSEI) resistance. More specifically, by utilizing an excitation voltage generating circuit composed of a switch, inductor, diode, capacitor, and resistor, and a processor controlling the same, real-time condition monitoring is enabled at the battery cell, module, and pack level regardless of charging, discharging, or standby states, and can be applied to battery management systems (BMS) in various application fields such as electric vehicles (EVs), energy storage systems (ESS), and portable electronic devices. The internal resistance of secondary batteries can increase depending on the degree of degradation, which can lead to capacity loss and increased internal heat generation during use. Furthermore, this phenomenon can cause an increase in internal temperature and internal short circuits due to causes such as mechanical misuse (crushing, collision, dropping, submersion, etc.), electrochemical misuse (overcharging, over-discharging, external short circuit, etc.), and thermal misuse (fire, thermal shock, overheating, etc.), thereby acting as a direct cause of fire resulting from thermal runaway. Conventional Battery Management Systems (BMS) manage batteries by periodically monitoring their voltage, current, and temperature to provide information on battery status and prevent fire accidents. They apply functions to prevent various battery misuses, such as overcharging, over-discharging, undervoltage, overvoltage, inter-cell voltage deviation, and temperature management. Nevertheless, the recent trend of fire accidents involving electric vehicles and ESS is becoming a social issue as cases leading to major accidents are occurring due to a continuous increase in the number of such incidents. This is raising safety concerns regarding secondary batteries and is hindering the development of battery-related industries, including the electric vehicle chasm. Therefore, various battery-related studies, including battery fire tests, are actively being conducted to establish fundamental countermeasures against battery fire accidents. According to recent research, when measuring the voltage, current, and temperature (external cell temperature) of a battery before and after the application of an internal short-circuit fault condition, changes in voltage, current, and temperature were found to lead to a fire accompanied by a rapid temperature change (temperature entering the thermal runaway stage) after maintaining a normal state for a certain period following the application of the fault condition. Consequently, to prevent such accidents and secure a golden time for immediate response, there is a need for technology to measure and manage changes in resistance of individual internal battery components under various battery degradation or failure conditions, in addition to the voltage, current, and temperature monitoring methods managed by existing BMSs. Conventional methods for measuring battery internal resistance typically include Electrochemical Impedance Spectroscopy (EIS) and Intermittent Current Interruption (ICI). Conventional EIS measures impedance by measuring changes in output in response to variable frequency input and projecting them onto a Nyquist plot, thereby determining the degree of degradation based on the measured internal resistance. This method enables precise measurement of AC and DC impedances and allows for the assessment of degradation under steady-state conditions. However, it has disadvantages, such as the measurement time being somewhat long (ranging from seconds to minutes), the need for complex computational processes involving frequency control input circuits, frequency measurement, and spectrum analysis, as well as complex control circuits, difficulties in miniaturization, and high costs. In the case of the intermittent current interruption method, a conventional internal resistance measurement method, impedance is measured through repetitive charge-discharge operation over the entire SOC range. It measures the Open Circuit Voltage (OCV) in the idle state and the voltage rising and falling during charge-discharge. Since the internal resistance of a secondary battery varies by SOC due to electrochemical reasons, it is necessary to measure the internal resistance in the range bet