KR101662154B1 - Apparatus and method for diagnosing status of battery using high frequency and impedance, and computer-readable recording medium with program therefor - Google Patents

Abstract

The present invention provides an apparatus and method for diagnosing a battery condition using harmonics and impedances that can diagnose the aging degree of a battery and predict a battery life and replacement cycle. A charge / discharge unit for charging / discharging the battery, a current injection unit for applying a constant current to the battery, and a controller for collecting the state information of the battery by the charging and discharging cycles of the battery, An impedance measuring unit for measuring an impedance value using a charge state and an impedance change rate of the battery through the measuring unit and the data collecting unit; and an impedance measuring unit for measuring a voltage and an impedance based on the impedance value measured by the impedance measuring unit. Measure current component by frequency and measure frequency characteristic to measure harmonic rate of change And a harmonic measuring unit.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery state diagnostic apparatus and method using harmonics and impedances, and a computer-readable recording medium storing a program for executing the method. therefor}

The present invention relates to an apparatus and method for diagnosing a battery condition, and more particularly, to an apparatus and method for diagnosing a battery condition using a harmonic and an impedance that can predict a battery life and a replacement cycle by diagnosing a degree of aging of the battery.

A large capacity battery (battery module) capable of generating a large amount of electric power can be used to drive a transmission device (an electric car, a hybrid car, an electric motorcycle, a golf cart, etc.) constituted by a battery. In particular, interest in energy storage systems (ESS), which can maximize the efficiency of energy storage and quality, and energy use as core of smart grid, is increasing with the spread of renewable energy .

The energy storage system (ESS) may include a large-capacity battery module having a plurality of battery cells, and may include a power grid (not shown) to supply remaining power (remaining energy) ) Is a system that can optimize the quality and efficiency of electric power.

A device for managing the battery module more efficiently and stably is a battery management system. The battery management system may be connected to a plurality of battery cells to read a voltage value of each battery cell through an analog to digital converter, and then control charging or discharging of the battery cell.

The method of calculating the state of charge (SOC) of a battery (battery cell) includes a current accumulation method (Ah method) for calculating the SOC by calculating the capacity used in relation to the current (Ampere) and the time (hour) There may be an impedance measurement method that calculates SOC in relation to internal impedance and SOC.

The current integration method is a method of estimating the remaining capacity by multiplying the discharge current and time. The SOC error (error rate) may become larger as time goes by due to current or time error accumulation. 1 is a graph illustrating the error rate of the conventional current integration method.

Referring to FIG. 1, an estimated SOC value 1 indicates a calculated value when a current or time is measured to be smaller than an actual value, and an estimated SOC value 1 indicates a difference with an accurate actual value of the SOC over time Can be large. The estimated value 2 of the SOC indicates a value calculated when the current or time is measured to be larger than the actual value, and the estimated value 2 of the SOC may be different from the accurate actual value of the SOC with the passage of time.

Further, the impedance measurement method may have a problem that the SOC of the battery can not be accurately calculated (measured or estimated) because the internal impedance of the battery changes when the battery is charged or discharged, that is, when a current flows.

As described above, in the case of the conventional battery management system (BMS), the battery's state of health (SOH) is often measured by measuring the state of charge (SOC) and impedance of the battery. However, And thus the accuracy and reliability are degraded.

Patent Registration No. 10-1354081: Device for diagnosing battery condition and method thereof Patent Registration No. 10-1463394: Battery management system and method for estimating battery charging state using battery management system

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an apparatus and method for diagnosing a battery condition using harmonics and impedance that can diagnose the aging degree of a battery, have.

It is another object of the present invention to provide a battery state diagnostic apparatus and method using harmonics and impedances capable of improving the accuracy and reliability of SOH judgment by analyzing harmonic characteristics in addition to a method of using a state of charge (SOC) and impedance of a conventional battery .

Other objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided a device for diagnosing a battery condition using harmonics and impedance, comprising: a measuring unit for measuring a voltage and a charging state of the battery during charging and discharging of the battery; A data collecting unit for collecting the state information of the battery by the charging and discharging cycles of the battery and storing the current and voltage components in an array form, An impedance measuring unit for measuring an impedance value by using a charge state of the battery and a rate of change of impedance through a collecting unit; and a voltage measuring unit for measuring a voltage and a current component on the basis of the impedance value measured by the impedance measuring unit, And a harmonic measurement unit for measuring a harmonic change rate.

Preferably, the impedance measuring unit includes a polarization resistor R_CT and a bug resistor R_W connected in series with each other, a double layer capacitor C_DL connected in parallel with the polarization resistor R_CT and the bug resistor R_W, And a corrosion resistor R_E connected in series with a dual-layer capacitor C_DL connected in parallel to the battery voltage on the other side.

Preferably, the harmonic measurement unit applies a voltage equal to the voltage value indicated by the battery through a 1-ohm (Ω) resistor connected in series with the battery and a DC power supply to measure a charging and discharging state of the battery And a NimyDAQ for measuring harmonic waves by measuring a voltage value at a resistance of 1 ohm and a current value at the battery.

Preferably, the harmonic measuring unit compares the harmonics measured by the measuring method designed in the software Labview using the voltage and current of the impedance value corresponding to the value obtained by dividing the voltage component by the current component.

According to another aspect of the present invention, there is provided a method for diagnosing a state of a battery using harmonics and impedance, the method comprising the steps of: measuring a voltage state of the battery based on a value of the impedance, The current component is measured for each frequency, the frequency characteristic is grasped, and the battery condition is diagnosed based on the measured change rate of the harmonics.

According to another aspect of the present invention, there is provided a method of diagnosing a battery condition using harmonics and impedance, comprising the steps of: (A) performing charging and discharging of a battery based on a constant current applied to the battery in a current injector; (B) measuring the voltage and charging state of the battery through charging and discharging of the battery through the measuring unit; (C) collecting the state information of the battery by the charging and discharging cycle of the battery through the data collecting unit, The method comprising the steps of: (a) storing voltage components in an array format; (d) measuring an impedance value using a collected state of charge of the battery and an impedance change rate through an impedance measuring unit; (E) It measures voltage and current components for each frequency, determines frequency characteristics, measures harmonic rate, and diagnoses battery status. The place is makin including.

Preferably, the measurement of the impedance value in the step (D) includes a polarization resistor R_CT and a bug resistor R_W connected in series to each other, a double layer capacitor connected in parallel to the polarization resistor R_CT and the bug resistor R_W, (C_DL) and a corrosion resistance (R_E) connected in series with a dual-layer capacitor (C_DL) connected in parallel to the battery voltage on one side and the battery voltage on one side.

Preferably, in the step (D), the harmonic comparison is performed by comparing the voltage and the current by FFT to diagnose the battery condition.

The apparatus and method for diagnosing a battery condition using harmonics and impedances according to the present invention as described above have the following effects.

First, in the case of a conventional battery management system (BMS), the battery life (SOH) is measured by measuring the state of charge (SOC) and impedance of the battery. However, in addition to these two methods, the harmonic characteristic is analyzed, And reliability can be improved.

Secondly, generally, a method widely used for battery impedance analysis is a method using EIR (Electrochemical Impedance Spectroscopy), EIS is expensive equipment of tens of thousands of won, and the present invention is composed of a battery equivalent circuit using a LANDEL equivalent circuit model , It is possible to provide a battery analysis system capable of replacing an expensive EIS at a low cost by allowing the impedance measurement to be performed.

Third, harmonic analysis of battery can represent SOH more precisely than existing battery equivalent circuit. Harmonic analysis, in contrast to impedance measurement system, does not require very accurate measurement, so it is easy to measure SOH of battery .

1 is a graph illustrating the error rate of the conventional current integration method
2 is a block diagram showing the configuration of a battery condition diagnosis apparatus using harmonics and impedances according to an embodiment of the present invention.
Fig. 3 is a circuit diagram showing an equivalent circuit showing the configuration of the impedance measuring unit of Fig. 2
FIG. 4 is a graph showing a result of actual impedance measurement of the battery using the impedance measuring unit of FIG.
FIG. 5 is a graph showing a magnitude comparison of harmonics for grasping the aging state of the battery using the harmonic measurement unit of FIG. 2. FIG.
6 is a flowchart illustrating a method of diagnosing a battery state using harmonics and impedances according to an embodiment of the present invention.
Fig. 7 is a device configuration diagram for illustrating a configuration state of a harmonic measuring apparatus in the present invention. Fig.

Other objects, features and advantages of the present invention will become apparent from the detailed description of the embodiments with reference to the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of an apparatus and method for diagnosing a battery condition using harmonics and impedances according to the present invention will be described with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. It is provided to let you know. Therefore, the embodiments described in the present specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and are not intended to represent all of the technical ideas of the present invention. Therefore, various equivalents It should be understood that water and variations may be present.

2 is a block diagram showing the configuration of a battery condition diagnosis apparatus using harmonics and impedances according to an embodiment of the present invention.

As shown in FIG. 2, the battery charger includes a measuring unit 10 for measuring a voltage and a charging state at the time of charging and discharging the battery, a charging unit 20 for charging the battery, a discharging unit 30 for discharging the battery, A data collecting unit 50 for collecting the state information of the battery by the charging and discharging cycles of the battery and storing the current and voltage components in an array form, An impedance measuring unit 60 for measuring an impedance value using the state of charge and the rate of change of impedance of the battery through the unit 10 and the data collecting unit 50 and an impedance measuring unit 60 for measuring the impedance value measured by the impedance measuring unit 60 And a harmonic measuring unit 70 for measuring voltage and current components for each frequency to determine a frequency characteristic and measuring a harmonic change rate.

3, the impedance measuring unit 60 includes a polarization resistor R_CT, a bug resistor R_W, a polarization resistor R_CT, and a bug resistor R_W, which are connected in series to each other, (C_DL) connected in parallel with the battery, and a corrosion resistance (R_E) connected in series with a double layer capacitor (C_DL) connected in parallel to the battery voltage on one side and a parallel circuit on the other side, The impedance value as shown in Fig.

7, the harmonic measurement unit 70 includes a battery 71, a 1-ohm resistor 72 connected in series with the battery, and a DC power supply A voltage source 64 for maintaining the charging and discharging state of the battery by applying a voltage equal to the voltage value indicated by the battery 61, And a NimyDAQ (63) for performing harmonic analysis by measuring the value.

Since the harmonic measurement unit 70 corresponds to a value obtained by dividing the voltage value by the current value, the harmonic measurement unit 70 can compare the harmonics measured by the measurement method designed by the software Labview using the voltage and the current of the impedance value . That is, as shown in FIGS. 5 (a) and 5 (b), when the voltage and the current are compared by FFT, the difference between the aged and the harmonics in the normal battery appears. The aging state can be grasped.

The operation of the battery condition diagnosis apparatus using harmonics and impedances according to the present invention will now be described in detail with reference to the accompanying drawings. The same reference numerals as those in Fig. 2 designate the same members performing the same function.

6 is a flowchart illustrating a method of diagnosing a battery state using harmonics and impedances according to an embodiment of the present invention.

Referring to FIG. 6, the charging and discharging of the battery is performed by controlling the charging unit 20 and the discharging unit 30 of the battery based on a constant current applied to the battery in the current injecting unit 40 (S10) .

Then, the measuring unit 10 measures the voltage and the charged state at the time of charging and discharging the battery (S20), and collects the state information of the battery by the charging and discharging cycle of the battery through the data collecting unit 50 And stores the current and voltage components in an array format (S30).

The impedance measuring unit 60 measures the impedance value using the charge state and impedance change rate of the battery collected through the data collecting unit 50 (S40). At this time, the measurement of the impedance value is performed by connecting the polarization resistor R_CT, the bug resistor R_W, and the polarization resistor R_CT and the bug resistor R_W in parallel with each other as shown in FIG. A dual circuit capacitor (C_DL) is used and a LAN equivalent circuit model consisting of a double-layer capacitor (C_DL) connected in parallel to the battery voltage on one side and a corrosion resistor (R_E) connected in series.

Then, the voltage and current components are measured for each frequency based on the impedance value measured through the LANDel equivalent circuit model through the harmonic measurement unit 70, and the frequency characteristics are grasped to measure the harmonic change rate to diagnose the battery state (S50 ).

FIG. 7 shows a method of measuring the magnitude of harmonics using a voltage.

7, the battery 71 measures the current value and the 1-ohm resistor 72, and performs the harmonic analysis through the NImyDAQ 73.

At this time, an important point in the harmonic charging and impedance measurement of the battery 71 is that the battery 71 should be measured in a state where charging and discharging are not occurring. Therefore, since the charging and discharging state of the battery can be maintained by applying a voltage equal to the voltage value indicated by the battery 71 through the DC power supply, the state of the battery can be maintained using the voltage source 74 shown in FIG. Should be maintained.

Since the measured impedance value corresponds to a value obtained by dividing the voltage component by the current component, the measurement method designed by the software Labview using the voltage and the current of the impedance value as shown in FIG. 5 (a) By comparing the currents with the FFT, harmonic comparisons can be made.

Accordingly, the battery life (SOH) can be represented more accurately than the conventional battery equivalent circuit through harmonic analysis of the battery. In particular, harmonic analysis is simpler to measure the SOH of a battery in that it does not require very precise measurement, unlike an impedance measurement system.

Meanwhile, the embodiment of the present invention can be made into a program that can be executed in a computer. That is, the various steps involved in the method according to the present invention may be stored in a computer readable recording medium. The medium may be a magnetic storage medium such as a ROM, a floppy disk, a hard disk, etc., an optical reading medium such as CD-ROM or DVD, a digital storage medium such as a USB memory, XD), etc.) and carrier waves (e.g., transmission over the Internet).

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It will be apparent to those skilled in the art that various modifications may be made without departing from the scope of the present invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

Claims (9)

A measuring unit for measuring a charging and discharging voltage and a charging state of the battery,
A charge / discharge unit for charging and discharging the battery,
A current injection unit for applying a constant current to the battery,
A data collecting unit for collecting state information of the battery by a charge and discharge cycle of the battery and storing current and voltage components in an array form,
An impedance measuring unit for measuring an impedance value using the charge state of the battery and the impedance change rate through the measuring unit and the data collecting unit;
And a harmonic measuring unit for measuring voltage and current components on the basis of the impedance value measured by the impedance measuring unit for each frequency to determine a frequency characteristic and measuring a harmonic change rate,
At this time, the harmonic measurement unit
A 1 ohm resistor in series with the battery,
A voltage source for maintaining a charged and discharged state of the battery by applying a voltage while varying the magnitude of the input voltage to the same magnitude as the voltage value indicated by the battery through a DC power supply;
And a NImyDAQ for measuring harmonic waves by measuring a voltage value of an input voltage while changing the value of the current through the battery and the voltage value indicated by the battery at a resistance of 1 ohm. A battery status diagnosis apparatus using a battery. The impedance measuring apparatus according to claim 1, wherein the impedance measuring unit
A polarization resistor R_CT and a bug resistor R_W connected in series,
A double layer capacitor C_DL connected in parallel to the polarization resistance R_CT and the bug resistor R_W,
And a corrosion resistor (R_E) connected in series with a double layer capacitor (C_DL) connected in parallel to the battery voltage on one side and the other side connected to the battery voltage on the other side. The method according to claim 1,
Wherein the harmonic measuring unit compares harmonics measured by a measuring method designed in a software Labview using voltage and current of an impedance value corresponding to a value obtained by dividing a voltage component by a current component, . delete delete (A) performing charging and discharging of the battery based on a constant current applied to the battery in the current injecting unit,
(B) measuring a voltage and a charged state at the time of charging and discharging the battery through the measuring unit,
(C) collecting state information of the battery by the charge and discharge cycle of the battery through the data collecting unit and storing the current and voltage components in an array form,
(D) measuring an impedance value using a collected state of charge of the battery and an impedance change rate through an impedance measuring unit;
(E) diagnosing a battery state by measuring voltage and current components inputted through a voltage value represented by a battery collected on the basis of the measured impedance value, measuring frequency characteristics of the voltage and current components, and measuring a harmonic change rate , ≪ / RTI >
In the step (E), a voltage of 1 ohm (Ω) connected in series with the battery and a voltage of the input voltage are changed by a DC power supply A voltage source for maintaining the charge and discharge state of the battery and a voltage value of an input voltage while changing the current value and the resistance value of 1 ohm through the voltage value indicated by the battery, Wherein the battery state is diagnosed using a circuit model consisting of NImyDAQ. The method according to claim 6,
The measurement of the impedance value in the step (D) includes a polarization resistor R_CT and a bug resistor R_W connected in series with each other, a double layer capacitor C_DL connected in parallel with the polarization resistor R_CT and the bug resistor R_W, And a corrosion resistance R_E connected in series with a double layer capacitor (C_DL) connected in parallel to one side of the battery voltage, and a harmonic and an impedance A method of diagnosing battery condition using. The method according to claim 6,
Wherein the step (E) comprises comparing the voltage and the current by FFT to compare the harmonics to diagnose the battery condition. A computer-readable recording medium having recorded thereon a program for executing each step of the method for diagnosing a battery condition according to any one of claims 6 to 8.

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