KR20220012003A - Apparatus and method for battery over-discharge protection and deterioration estimation - Google Patents

Abstract

The present invention relates to an apparatus and method for battery over-discharge protection and deterioration estimation. The method according to the present invention comprises the steps of: starting charging a battery in a constant current mode; and while charging the battery in a constant current mode according to a predetermined charge/discharge profile, whenever a predetermined battery voltage is reached, calculating the internal resistance of the battery during an idle period in which the charging of the battery is stopped for a predetermined time. According to the present invention, it is possible to determine deterioration characteristics of a battery in a limited system capable of measuring only a battery voltage without battery current information.

Description

Apparatus and method for battery over-discharge protection and deterioration estimation

The present invention relates to an apparatus and method for battery over-discharge protection and deterioration estimation.

In the case of the existing over-discharge protection algorithm, when the battery reaches a specific voltage, the battery is discharged and only a charging path is created to reach a stable voltage and charge. In the case of the conventional method, it is difficult to predict the remaining life of the battery because it is difficult to estimate the state of deterioration or one-string failure because only the voltage of the battery is monitored.

On the other hand, in the case of a system that supplies power to a satellite payload, since the deterioration estimation algorithm of the existing method monitors the current and voltage to determine the state of charge (SoC) of the battery, and determines the deterioration characteristics of the battery based on the determined state of charge, Since only voltage information can be used, it is difficult to use a general lifespan estimation method.

So without battery current information, such as systems powered by batteries to satellite load units. There is a need for a method of determining the deterioration characteristics of a battery even when only limited information about the battery voltage is available.

Accordingly, the technical problem to be solved by the present invention is to provide a method and an apparatus for determining deterioration characteristics of a battery in a limited system capable of measuring only a battery voltage without battery current information.

In a method for estimating battery overdischarge protection and deterioration according to an embodiment of the present invention for solving the above technical problem, starting charging of the battery in a constant current mode, and using the battery in a constant current mode according to a predetermined charge/discharge profile and calculating the internal resistance of the battery during a rest period during which charging of the battery is stopped for a predetermined time whenever a predetermined battery voltage is reached during charging.

The internal resistance of the battery may be respectively calculated corresponding to an entry time point and an ending time point of the idle period.

The state of the battery may be estimated by comparing the calculated internal resistance of the battery with internal resistance table data for each deterioration time and charging voltage level obtained through a test in advance for a battery of the same type as the battery.

The internal resistance corresponding to the entry point of the idle section is a difference between the voltage of the battery measured at the entry point of the idle section and the voltage of the battery measured after a predetermined time from the entry point of the idle section to the constant current mode It can be calculated as a value divided by the charging current set in .

The internal resistance corresponding to the end time of the idle period is a difference between the voltage of the battery measured after a predetermined time from the end of the idle period and the voltage of the battery measured at the end of the idle period in the constant current mode It can be calculated as a value divided by the charging current set in .

Battery overdischarge protection and deterioration estimation apparatus according to an embodiment of the present invention for solving the above technical problem, a voltage measuring unit for measuring the voltage of a battery, a charging circuit unit for charging the battery, and the charging circuit unit While charging the battery in a constant current mode according to a predetermined charge/discharge profile by controlling the battery, the voltage measured by the voltage measuring unit is in a rest period in which charging of the battery is stopped for a predetermined time whenever a predetermined battery voltage is reached and a control unit for calculating the internal resistance of the battery by using the voltage of

According to the present invention, it is possible to determine the deterioration characteristics of the battery in a limited system capable of measuring only the battery voltage without battery current information.

1 is a block diagram illustrating a configuration of a battery over-discharge protection and deterioration estimation apparatus according to an embodiment of the present invention.
2 is a flowchart illustrating an operation of an apparatus for estimating battery over-discharge protection and deterioration according to an embodiment of the present invention.
3 is a graph for explaining a charge/discharge profile of a constant current mode section according to an embodiment of the present invention.

Then, with reference to the accompanying drawings, the embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily implement them.

1 is a block diagram showing the configuration of a battery over-discharge protection and deterioration estimation apparatus according to an embodiment of the present invention.

Referring to FIG. 1 , the device according to the present invention may include a voltage measuring unit 110 , a charging circuit unit 130 , and a control unit 150 .

The voltage measuring unit 110 measures the voltage of the battery 200 .

The battery 200 may be embodied as a secondary battery that can be repeatedly used by recharging it even after discharging. The secondary battery may be a lead storage battery, a nickel-cadmium battery (NiCd), a nickel-metal hydride battery (Ni-MH), a lithium ion battery (Li-ion), a lithium ion polymer battery (Li-ion polymer), or the like. Of course, in addition to the examples illustrated here, the battery 210 may be a secondary battery that can be repeatedly used by recharging after discharging.

The charging circuit unit 130 receives power from a power supply device (not shown), for example, an iPDU (instrument power distribution unit) in the case of a satellite, and uses a charging voltage and a charging current according to a predetermined charging/discharging profile to the battery 200. It can be output to charge the battery 200 .

When the battery 130 reaches a predetermined discharge cutoff voltage, the control unit 150 cuts off the load connected to the battery 200 and activates a battery over-discharge protection algorithm that connects the charging circuit unit 130 to the battery 200 . can

The control unit 150 controls the charging circuit unit 1300 to charge the battery 200 in a constant current mode according to a predetermined charge/discharge profile, and whenever a predetermined battery voltage is reached, the battery 200 is charged for a predetermined time. The internal resistance of the battery 200 may be calculated using the voltage of the battery measured by the voltage measuring unit 110 in the idle period during which the battery is stopped.

The internal resistance of the battery 200 may be respectively calculated corresponding to the entry point and the end point of the idle period.

It may vary depending on the embodiment, but the internal resistance of the battery 200 may be calculated by the following equation.

[Equation 1]

Internal Impedance1(Ω) = ΔV1 / I_charge

Here, Internal Impedance1 is the internal resistance of the battery corresponding to the entry point of the idle period.

ΔV1 = battery voltage at the time of entering the idle period - the battery voltage after a predetermined time (eg, after 1 second) from the time of entering the idle period.

I_charge is the charging current set in the constant current charging mode.

[Equation 2]

Internal Impedance2(Ω) = ΔV2 / I_charge

Here, Internal Impedance2 is the internal resistance of the battery corresponding to the end time of the idle period.

ΔV2 = the voltage of the battery measured after a predetermined time (eg, after 1 second) from the end time of the idle period (eg, 10 minutes after entering the idle period) - the voltage of the battery measured at the end of the idle period.

I_charge is the charging current set in the constant current charging mode.

Equations 1 and 2 are examples in which the idle period is set to 10 minutes. In this way, to take a break of at least 10 minutes to measure the deterioration of the battery, it is to wait until the slope of the voltage that decreases due to ion diffusion that occurs when the charging of the battery is stopped is smoothed by ΔV2. This is to ensure the accuracy and consistency of the measured Internal Impedance2(Ω). Also, the reason for not waiting for too long more than 10 minutes is that in the case of batteries mounted on satellites, Because it is a degradation measurement, it is to achieve a fast recovery voltage and reduce the influence on satellite operation.

The number of pause periods for calculating internal resistance during charging in the constant current mode may vary depending on the system design, and the duration of the pause period may also be set differently depending on the system design. The battery voltage corresponding to the entry point of the idle period may also be set differently according to system design.

The controller 150 may estimate the state of the battery by comparing the internal resistance of the battery calculated in the idle period with internal resistance table data obtained through a test in advance for a battery of the same type on the ground in advance. The internal resistance table data may be implemented as a table having internal resistance data for each degradation time and each charging voltage level.

In this way, it is possible to judge battery health such as the estimated battery deterioration state and one-string failure state, and as a result, it is necessary to determine the operation method of the payload unit in the future according to the battery state and to extend the mission. In this case, it can be used as a basis for determining the remaining battery life.

2 is a flowchart illustrating an operation of an apparatus for estimating battery over-discharge protection and deterioration according to an embodiment of the present invention.

Figure 2 shows the charging/discharging profile of a discharge cutoff voltage of 22.5V, a constant current charging current of 3.8A, a first resting section voltage of 25V, a second resting section voltage of 25.5V, a resting section duration of 10 minutes, a constant voltage charging mode starting voltage of 26V, and constant voltage charging. An example in which the mode target voltage is set to 27.5V is shown. According to an embodiment, a voltage, a time preset in the charging/discharging profile, the number of idle periods during charging in the constant current mode, etc. may be designed differently.

3 is a graph for explaining a charging/discharging profile of a constant current mode section according to an embodiment of the present invention.

2 and 3 , first, when the voltage of the battery 200 reaches the discharge cutoff voltage of 22.5V (S210-Y), the control unit 150 cuts off the load connected to the battery 200 and the charging circuit unit 130 ) to the battery 200 may activate the battery over-discharge protection algorithm (S220).

Thereafter, the control unit 150 controls the charging circuit unit 1300 to charge the battery 200 in a constant current mode for charging with a charging current of 3.8A (S230).

After that, when the voltage of the battery 200 reaches the first rest period voltage of 25V (S240-Y), the control unit 150 stops charging the battery 200 for 10 minutes, and corresponds to the entering and ending points of the idle period Calculate the internal resistance of the battery 200 (S250).

Next, after step S250, the battery 200 is charged again in the constant current mode (S255), and when the voltage of the battery 200 reaches the second rest period voltage of 25.5V (S260-Y), the control unit 150 stops charging of the battery 200 for 10 minutes, and calculates the internal resistance of the battery 200 corresponding to the time of entering and ending the idle period (S270).

Next, after step S270, the battery 200 is charged again in the constant current mode (S275), and when the voltage of the battery 200 reaches the constant voltage charging mode starting voltage of 26V (S280-Y), the control unit 150 is The battery 200 is charged in the constant voltage mode (S290).

Thereafter, when the voltage of the battery 200 reaches the constant voltage charging mode target voltage of 27.5V (S295-Y), the controller 150 terminates charging of the battery 200 .

An embodiment of the present invention includes a computer-readable medium including program instructions for performing various computer-implemented operations. This medium records a program for executing the method described above. The medium may contain program instructions, data files, data structures, etc. alone or in combination. Examples of such media include hard disks, magnetic media such as floppy disks and magnetic tapes, optical recording media such as CDs and DVDs, optical disks and magneto-optical media, and program instructions such as ROM, RAM, flash memory, etc. hardware devices configured to store and perform Examples of program instructions include not only machine language codes such as those generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like.

Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims are also provided. is within the scope of the

Claims (8)

starting charging of the battery in constant current mode, and
While charging the battery in a constant current mode according to a predetermined charge/discharge profile, calculating the internal resistance of the battery in a rest period in which charging of the battery is stopped for a predetermined time whenever a predetermined battery voltage is reached
Battery over-discharge protection and deterioration estimation method comprising a. In claim 1,
The internal resistance of the battery is
A method for estimating battery over-discharge protection and deterioration, each calculated corresponding to an entry time and an end time of the idle period. In claim 2,
the calculated internal resistance of the battery,
A battery over-discharge protection and deterioration estimation method for estimating the state of the battery by comparing it with internal resistance table data for each degradation time and each charging voltage level obtained through a test in advance for a battery of the same type as the battery. In claim 2,
The internal resistance corresponding to the entry point of the rest period is,
Calculated as a value obtained by dividing the difference between the voltage of the battery measured at the entry point of the idle section and the voltage of the battery measured after a predetermined time from the entry point of the idle section by the charging current set in the constant current mode,
The internal resistance corresponding to the end time of the rest period is,
Battery overdischarge calculated by dividing the difference between the voltage of the battery measured after a predetermined time from the end of the idle period and the voltage of the battery measured at the end of the idle period by the charging current set in the constant current mode Protection and degradation estimation methods. A voltage measuring unit that measures the voltage of the battery;
a charging circuit for charging the battery; and
While charging the battery in a constant current mode according to a predetermined charge/discharge profile by controlling the charging circuit unit, the voltage is measured in a rest period in which charging of the battery is stopped for a predetermined time whenever a predetermined battery voltage is reached A control unit for calculating the internal resistance of the battery using the voltage of the battery measured in the unit
Battery over-discharge protection and deterioration estimation device comprising a. In claim 5,
The internal resistance of the battery is
An apparatus for estimating battery over-discharge protection and deterioration, each calculated corresponding to an entry time and an ending time of the idle period. In claim 6,
the calculated internal resistance of the battery,
Battery overdischarge protection and deterioration estimation apparatus for estimating the state of the battery by comparing it with internal resistance table data for each degradation time and each charging voltage level obtained through a test in advance for a battery of the same type as the battery. In claim 6,
The internal resistance corresponding to the entry point of the rest period is,
Calculated as a value obtained by dividing the difference between the voltage of the battery measured at the entry point of the idle section and the voltage of the battery measured after a predetermined time from the entry point of the idle section by the charging current set in the constant current mode,
The internal resistance corresponding to the end time of the rest period is,
Battery overdischarge calculated by dividing the difference between the voltage of the battery measured after a predetermined time from the end of the idle period and the voltage of the battery measured at the end of the idle period by the charging current set in the constant current mode Protection and deterioration estimation device.

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