KR101473156B1 - The way of forecasting the life cycle of rechargeable secondary batteries - Google Patents

Abstract

The present invention relates to an apparatus and a method of forecasting a life cycle of a rechargeable secondary battery capable of previously tracking and repairing a disorder expectation battery to estimate an exact life by calculating a remaining life of a battery using an average discharge rate per hour. The apparatus and a method of forecasting a life cycle of a rechargeable secondary battery includes: calculating a sum of a charge current by measuring and summing the charge current; calculating an average discharge rate per hour by dividing the sum of the charge current by the hour when a predetermined time elapses after a charge current measuring value is accumulated and summed; calculating the number of expectation cycles using the average discharge rate per hour; calculating and accumulating a contribute value per hour of one cycle value by replacing the number of expectation cycles with an expected life cycle to obtain a sum; determining whether the accumulated value of the contribute value per hour of one cycle value is greater than one cycle, and increasing the total number of times of rotation and the number of charge in a period by one, and substituting the accumulated value of the contribute value per hour of one cycle value by zero; calculating a remaining life in a period unit when a predetermine period elapses after starting calculation; and substituting the number of charge in the period by zero and returning to a start position.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rechargeable secondary battery,

The present invention relates to an apparatus and method for predicting the life of a secondary battery, and more specifically, by calculating the remaining lifetime of a battery using the average discharge rate per hour, it is possible to predict an accurate lifetime, And an apparatus and method for predicting the life of the secondary battery.

(NiCd), a nickel metal hydride battery (NiMH), a nickel-metal hydride battery (NiMH), and the like are known as a secondary battery. , A lithium ion battery (Li-ion), and a lithium ion polymer battery (Li-ion polymer). There are ESS (Energy Storage System), electric vehicle and so on, which are used to make large capacity battery by combining such secondary battery. In the configuration of one large capacity battery system, the number of secondary batteries is as small as several tens to hundreds of thousands Batteries are used in combination in series and in parallel.

A plurality of individual cells connected in series and in parallel constituted in one large capacity battery system have difficulty in having the same expected lifetime (CYCLE) due to the characteristics of the battery. The constituent components of the negative electrode material, the positive electrode material, and the separator constituting the secondary battery differ depending on the manufacturer of the secondary battery, and the lifetime (CYCLE) of the secondary battery varies depending on the constituent materials of the positive electrode active material, the negative electrode material, to be.

If the individual expected lifetime (CYCLE) of each battery constituted in the large-capacity battery system can be accurately predicted and displayed, only the problematic battery can be replaced in advance while maintaining the SOH (System Of Health) It is very important to accurately predict the individual life expectancy (CYCLE) of each battery.

As a conventional method of predicting the lifetime of a secondary battery, there is a method of estimating the lifetime of the secondary battery, regardless of the type and constituent material of the battery, such as the deterioration degree of the battery, the voltage change of the battery, Of the total population.

For reference, KR 10-0372879 entitled " Method and apparatus for measuring secondary battery residual amount "includes a method of calculating a total capacity change according to deterioration degree of a battery as a FUZZY value, estimating a power amount value by the amount of change, A method of measuring the remaining life of the battery by a method of increasing the value is disclosed.

In addition, KR 10-041497, "Method for estimating the capacity of a lithium ion battery" includes estimating the charging capacity of a battery by determining a specific charging time, for example, a point of time from a constant current to a constant voltage, using a constant- Is disclosed.

In addition, KR 10-0740113 entitled " Battery life determination method and battery management system using the same "includes a method of calculating the battery internal voltage, calculating the maximum output using the battery voltage, and estimating the battery deterioration state as a warning and a defect signal .

Also, KR 10-1238478 entitled "Method for measuring remaining battery capacity" includes calculating an estimated OCV in consideration of a discharge discharge current of a battery, calculating an SOC by adding or subtracting a total current accumulation value of the battery, A method of estimating the SOC by a method of correcting the reference SOC value table is disclosed.

However, in the conventional method of predicting the lifetime of the secondary battery, the lifetime prediction based on the constituent material of the most important battery is not considered. As a result, the expected lifetime value of the battery is expected to wait for a certain period of time There is a problem that it is necessary to confirm that certain conditions are being met during use, and accurate measurement values must be always accompanied by tracking changes in charge / discharge current accumulation value and charge / discharge voltage so that the system can accurately measure external conditions There is a problem that not only the external control device is necessarily provided but also the accuracy of the expected life span is influenced by the accuracy of the external control device.

In addition, the conventional method of predicting the lifetime of a secondary battery is incapable of coping with various charge / discharge conditions that can occur, such as the case where no full charge full discharge is carried out until the life of the battery is completed under charging / discharging conditions, There is a problem that it is difficult to predict.

In addition, the conventional method of predicting the lifetime of the secondary battery is not a product in which the secondary battery is taken out from the same frame as the mold product, so that even if the secondary battery is manufactured by a slight difference in battery components such as a cathode material, an anode material, an electrolyte, There is a problem that a difference occurs in capacity and life expectancy (CYCLE).

An object of the present invention is to solve the above-mentioned problems of the prior art, and it is an object of the present invention to provide a method and apparatus for estimating the remaining life of a battery by using an average discharge rate per hour, And an apparatus and method for predicting the life of the secondary battery.

In order to attain the above object, the present invention provides a battery charger comprising: a current sensor provided between a voltage source and a battery; a current sensor connected to both ends of the current sensor; The total charge current is summed, and when the sum of the charge current measurements is over a certain period of time, the total charge current is divided by the time to calculate the average discharge rate per hour, and the expected cycle number f ), Calculates a contribution value (DELTA CYCLE) per hour of one cycle value by substituting the estimated cycle count f (x) into the expected life cycle, calculates cumulative value and accumulates the contribution per hour (DELTA CYCLE) is greater than one cycle, the total number of times of charging and the number of times of charging within the period are increased by 1, and the integrated value of the contribution value per hour of one cycle value is replaced with zero And a microcontroller for calculating the life P remaining in a unit of time when a predetermined period of time has elapsed since the start of the calculation and returning to the start position while replacing the charge count within the period with zero.

Configuration, the expected cycle number (f (x)) of the apparatus of this invention the formula (f (x) = p1 · x 6 + p2 · x 5 + p3 · x 4 + p4 · x 3 + p5 · x ² + p6 x + p7).

In the construction of the apparatus of the present invention, the above-mentioned contribution value (DELTA CYCLE) of the above-described one cycle value is preferably calculated using the formula (DELTA CYCLE = aver_sum / (cir_data - stack_cycle)). Where aver_sum is the average discharge rate per hour, cir_data is the expected life cycle, and stack_cycle is the total charge count.

In the configuration of the apparatus of the present invention, it is preferable to calculate the remaining lifetime (P) by using the formula (P = (max_cycle - stack_cycle) / interval_cycle). Here, max_cycle is the maximum expected lifetime cycle, and interval_cycle is the charge count within the period.

According to an aspect of the present invention, there is provided a method of measuring a charging current, the method comprising: calculating a sum of charging currents by measuring and summing charging currents; calculating a sum of charging currents, Calculating a predicted cycle count f (x) by using an average discharge rate per hour, calculating a predicted cycle count f (x) by substituting the expected cycle count f (x) Calculating a cumulative contribution value (DELTA CYCLE) per cycle of the cycle value, calculating an integrated value, and determining whether the cumulative value of the contribution value per cycle (DELTA CYCLE) per cycle is greater than one cycle, Increasing the total number of times of charging and the number of times of charging within the period by one and replacing the accumulated value of the contribution value per hour of one cycle value with zero; Substituting step, a charging period of times to calculate the remaining life (P) in the unit period to 0, and preferably comprising, including the step of returning to the starting position.

Configuration of the method of this invention, the expected cycle number (f (x)) is the formula (f (x) = p1 · x 6 + p2 · x 5 + p3 · x 4 + p4 · x 3 + p5 · x ² + p6 x + p7).

In the construction of the method of the present invention, the above-mentioned contribution value (DELTA CYCLE) of the above-described one cycle value is preferably calculated by using the formula (DELTA CYCLE = aver_sum / (cir_data - stack_cycle)). Where aver_sum is the average discharge rate per hour, cir_data is the expected life cycle, and stack_cycle is the total charge count.

In the construction of the method of the present invention, it is preferable to calculate the remaining lifetime P by using the formula (P = (max_cycle - stack_cycle) / interval_cycle). Here, max_cycle is the maximum expected lifetime cycle, and interval_cycle is the charge count within the period.

The present invention has an effect that it is possible to estimate the remaining life of the battery by using the average discharge rate per hour, thereby predicting the accurate life span and thereby to keep track of the failure predicted battery in advance.

1 is a configuration diagram of an apparatus for predicting the life of a secondary battery according to an embodiment of the present invention.
2 is a flowchart illustrating a method of predicting the lifetime of a secondary battery according to an embodiment of the present invention.
3 is a graph of an apparatus for predicting the life of a secondary battery according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily carry out the present invention. Other objects, features, and operational advantages, including the purpose, operation, and effect of the present invention will become more apparent from the description of the preferred embodiments.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory only and are not to be construed as limiting the scope of the invention as disclosed in the accompanying claims. It is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and similarities, many of which are within the scope of the present invention.

Also, terms and words used in the description and claims of the present invention are defined based on the principle that the inventor can properly define the concept of a term in order to explain its invention in the best way, And should not be construed as limited to only the prior art, and should be construed in a meaning and concept consistent with the technical idea of the present invention. For example, the terms relating to directions are set on the basis of the position represented on the drawing for convenience of explanation.

1 is a configuration diagram of an apparatus for predicting the life of a secondary battery according to an embodiment of the present invention.

As shown in FIG. 1, the configuration of an apparatus for predicting the life of a secondary battery according to an embodiment of the present invention includes a current sensor 1 provided between a voltage source Vcc and a battery 2, A current sensor and both ends of the battery 2 are connected to each other. The charging current sum (cur_sum) is calculated by measuring and summing the charging currents and the sum of the charging current measurement values cur_chk ) Is calculated by dividing the charge current sum (cur_sum) by the time (t) and calculating the average discharge rate (aver_sum) per hour and the expected cycle count f (x) by using the average discharge rate per hour (aver_sum) , The predicted cycle count f (x) is substituted into the expected life cycle cir_data to calculate the cumulative contribution value DELTA CYCLE per cycle and accumulates to calculate the cumulative value DELTA sum_cycle, When the cumulative value? Sum_cycle of the contribution value per cycle? CYCLE is larger than one cycle The accumulation value (? Sum_cycle) of the contribution value (? CYCLE) per hour of one cycle value is replaced with 0, and the accumulation value (? Sum_cycle) The microcontroller 3 calculates the life P remaining in the unit of time in the case where? T_time has elapsed, and returns to the start position while replacing the interval_cycle in the period with zero.

2 is a flowchart illustrating a method of predicting the lifetime of a secondary battery according to an embodiment of the present invention.

As shown in FIG. 2, the configuration of a method for predicting the life of a secondary battery according to an embodiment of the present invention includes a step S1 of starting an operation, a step S2 of measuring a charging current, (S4) of calculating a charging current sum (cur_sum) by summing the current measurement values (cur_chk) and (S4) judging whether or not the sum of the charging current measurement values (cur_chk) (S6) calculating an average discharge rate (aver_sum) per hour by dividing the charge current sum (cur_sum) by the time ([Delta] t) when the charge current measurement values are accumulated or summed and a predetermined time A step S7 of calculating the expected cycle number f (x) using the average discharge rate aver_sum and a step S8 of substituting the expected cycle number f (x) into the expected life cycle cir_data (S9) of calculating a contribution value (DELTA CYCLE) per cycle of one cycle value, and calculating a contribution (S10) of calculating a cumulative value (DELTA sum_cycle) of accumulation values (DELTA CYCLE) of the one cycle value and a cumulative value (DELTA sum_cycle) of the contribution value (DELTA CYCLE) S11) and the cumulative value (DELTA sum_cycle) of the contribution value per cycle (DELTA CYCLE) of one cycle is larger than one cycle, the total charge count (stack_cycle) is increased by 1, the charge count (interval_cycle) (S13) of replacing the accumulated value (DELTA sum_cycle) of the cycle value with the contribution value DELTA CYCLE per hour to 0, a step (S14) of judging whether a predetermined period (DELTA t_time) A step S16 of calculating the remaining life P in units of a period when the predetermined period Δt_time of the calculation has elapsed, the step S17 of replacing the interval_cycle in the period with 0, (S18). ≪ / RTI >

The operation of the apparatus for predicting the life of the secondary battery according to an embodiment of the present invention and the method thereof will be described below.

In the late 1700s, Charles-Augustin de Coulomb defined the battery as flowing 1 C every second to receive a charge current of 1A. In 10 seconds, 10C will flow through the battery. In the case of a discharge, this principle works in reverse.

Today, the battery industry uses a discharge rate (C-rate) as a measure of the charge and discharge current, with most portable batteries applied at 1C. This means that a 1,000 mAh battery discharged at 1 C under ideal conditions provides 1,000 mA of current per hour. 500 mA is delivered for 2 hours at 0.5 C, and 2,000 mA is delivered at 2 C for 30 minutes. That is, 1C means 1 hour discharge, 0.5C means 2 hours, and 2C means 30 minutes discharge.

When the operation is started (S1), the microcontroller 3 measures the charge current using the signal input from the current sensor 1 (S2). Next, the microcontroller 3 calculates the charging current sum cur_sum by summing the charging current measurement values cur_chk (S3).

Subsequently, the microcontroller 3 judges whether or not a predetermined time Δt has elapsed since the sum of the measured charging current values (S4), and when the predetermined time Δt has elapsed since the sum of the measured charging current values, cur_sum) is divided by the time? t to calculate an average discharge rate aver_sum per hour (S6).

Next, the microcontroller 3 calculates the expected cycle count f (x) by substituting the average discharge rate (aver_sum) per hour into the following equation (1) (S7).

The above equation (1) is obtained from the graph shown in FIG. 3, and the graph of FIG. 3 is obtained through experiment based on the DOD (Discharge of Depth) data provided by the manufacturer.

A p1 ~ p7 is a constant value in the above equation 1, p1 is 6.944e ^-7, p2 is -0.0002958, p3 is 0.05132, p4 is -4.635, p5 is 230.0, p6 is -6143, p7 is of 7.51e ⁴ Value.

The expected cycle number f (x) is determined to be a value between a minimum of 2,000 and a maximum of 75,000. When the average discharge rate aver_sum per hour is 100%, the expected cycle number f (x) 2,000, and if the average discharge rate per hour (aver_sum) is 40%, the expected number of cycles (f (x)) is 6,000.

Subsequently, the microcontroller 3 substitutes the expected cycle count f (x) for the expected life cycle (cir_data) (S8) and calculates the contribution value (CYCLE) per cycle of one cycle value using the following equation (2) (S9).

Where aver_sum is the average rate of discharge per hour, cir_data is the expected life cycle, and stack_cycle is the total charge count.

Subsequently, the microcontroller 3 accumulates the contribution value (DELTA CYCLE) per one cycle value to calculate the integrated value DELTA sum_cycle (S10).

Next, the microcontroller 3 determines whether the accumulated value DELTA sum_cycle of the accumulated value DELTA CYCLE of one cycle value is greater than the value of one cycle (S11) When the accumulated value (DELTA sum_cycle) of the contribution value (DELTA CYCLE) is greater than one cycle value, the total charge count (stack_cycle) is increased by 1, the interval_cycle within the period is increased by 1, The sum (? Sum_cycle) of the difference value? CYCLE is replaced with 0 (S13). Therefore, the above-described total number of charge cycles (stack_cycle) and the number of charge cycles in the period (interval_cycle) are increased by 1 each time the secondary battery is fully charged.

Next, the microcontroller 3 determines whether a predetermined period (DELTA t_time) in units of a month or a day has elapsed since the start of the calculation, and if the predetermined period (DELTA t_time) Using the formula 3, the remaining life P is calculated in units of a month or a unit of a day (S16).

Here, max_cycle is the maximum expected life cycle, stack_cycle is the total charge count, and interval_cycle is the charge count within the period.

After obtaining the remaining service life P in the unit of time, the microcontroller 3 replaces the interval_cycle within the period with zero (S17) and returns to the start position (S18).

In this way, if the remaining life (P) is applied to all the individual cells constituted in the system in units of a unit of a month or a unit of a day, System is possible.

Therefore, the user can predict the remaining lifetime (P) of dozens to tens of thousands of batteries in advance and replace the problematic battery.

1: current sensor 2: battery
3: Microcontroller

Claims (8)

A current sensor provided between the voltage source and the battery,
The current sensor and the battery are connected at both ends thereof. The charging current is summed by measuring and summing the charging current. When the sum of the charging current measurement values is accumulated, the charging current is divided by the time The predicted cycle number f (x) is substituted into the expected life cycle, and the contribution value per hour (? (X)) of one cycle value is calculated by calculating the average discharge rate per hour, calculating the estimated cycle number f CYCLE) is calculated and accumulated to calculate an integrated value. When the integrated value of the contribution value per cycle (DELTA CYCLE) of one cycle value is larger than one cycle, the total number of times of charging and the number of times of charging within the period are increased by 1, The accumulation value of the contribution per hour is replaced by 0, the life remaining in the period unit is calculated when a certain period of time has elapsed from the start of calculation, Comprised, including the micro-controller for controlling to return to the starting position,
Wherein the contribution value (DELTA CYCLE) of the one cycle value is calculated using the formula DELTA CYCLE = aver_sum / (cir_data - stack_cycle).
Where aver_sum is the average discharge rate per hour, cir_data is the expected life cycle, and stack_cycle is the total charge count. The method according to claim 1,
The expected cycle number (f (x)) is the formula (f (x) = p1 · x 6 + p2 · x 5 + p3 · x 4 + p4 · x 3 + p5 · x 2 + p6 · x + p7) Of the life of the secondary battery. delete The method according to claim 1,
Wherein the remaining lifetime (P) is calculated using the formula (P = (max_cycle - stack_cycle) / interval_cycle).
Here, max_cycle is the maximum expected lifetime cycle, and interval_cycle is the charge count within the period. Calculating and summing charge currents to calculate a sum of charge currents;
Calculating an average discharge rate per hour by dividing the sum of the charge currents by the time when the charge current measurements are accumulated and summed and a predetermined time elapses;
Calculating an expected cycle count f (x) using an average discharge rate per hour,
Calculating a cumulative contribution value (DELTA CYCLE) per one cycle value by substituting the expected cycle count (f (x)) into the estimated life cycle,
It is judged whether or not the integrated value of the contribution value per cycle (ΔCYCLE) of one cycle value is larger than one cycle, and when it is larger than one cycle, the total charge number and the number of times of charge within the period are increased by 1, and the integrated value of the contribution value per hour 0 < / RTI >
Calculating a lifetime remaining in a unit of time when a predetermined period of time has elapsed since the start of the calculation;
Replacing the charge count within the period with zero and returning to the start position,
Wherein the contribution value (DELTA CYCLE) of the one cycle value is calculated using the formula DELTA CYCLE = aver_sum / (cir_data - stack_cycle).
Where aver_sum is the average discharge rate per hour, cir_data is the expected life cycle, and stack_cycle is the total charge count. 6. The method of claim 5,
The expected cycle number (f (x)) is the formula (f (x) = p1 · x 6 + p2 · x 5 + p3 · x 4 + p4 · x 3 + p5 · x 2 + p6 · x + p7) Of the secondary battery. delete 6. The method of claim 5,
Wherein the remaining lifetime P is calculated using a formula (P = (max_cycle - stack_cycle) / interval_cycle).
Here, max_cycle is the maximum expected lifetime cycle, and interval_cycle is the charge count within the period.

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