KR20140049331A - Battery stste of charge estimation method using ultrasonic sensor - Google Patents

Abstract

The present invention relates to a method of calculating the charge state of the interior of a battery using an ultrasonic sensor instead of an additional battery sensor. The ultrasonic sensor system according to an aspect of the present invention includes: a transmitting part disposed on one side of a vehicle battery and transmitting an ultrasonic signal; and a receiving part disposed on the other side which opposes the one side thereof and receiving the ultrasonic signal. The receiving part calculates the transmission speed of the ultrasonic signal and estimates the charge state of the battery by calculating electrolytic density of the interior of the battery based on the transmission speed. [Reference numerals] (AA) Start; (BB) End; (S21) Calculate the transmission speed of an ultrasonic signal; (S22) Calculate electrolytic density of the interior of the battery; (S23) Estimate SOC based on the electrolytic density

Description

Calculation method of battery charge state using ultrasonic sensor {BATTERY STSTE OF CHARGE ESTIMATION METHOD USING ULTRASONIC SENSOR}

The present invention relates to a method of calculating an internal state of charge of a vehicle battery, and more particularly, to a method of calculating an internal state of charge of a battery using an ultrasonic sensor instead of a separate battery sensor.

Current battery sensor features include a voltage measurement function that measures the voltage across the battery, a current measurement function that measures the battery's input and output current, and a temperature measurement function that measures the ambient temperature to predict the battery's internal temperature. Then, a value such as SOC (%) indicating the state of charge of the battery, SOH (%) indicating the state of the battery, and SOF (%) indicating the battery voltage DROP estimated voltage at the start are provided.

At this time, SOC (%), SOH (%), SOF (%) are measured values based on the capacity of the battery currently installed, and to estimate the capacity of the currently installed battery in preparation for a change in battery capacity such as battery replacement. A self-adaptive (SELF-ADAPTATION) system is provided.

According to the self-adaptive logic provided in a conventional battery sensor, the battery internal resistance value is used to predict the battery capacity. However, when measuring the internal resistance value of the battery, it is impossible to accurately measure the internal resistance value of the wire due to the layout constraint of the vehicle, and the internal resistance value of the battery is very small, There is a problem that self-determination of the battery capacity is difficult.

In this case, the battery sensor makes a wrong determination of the nominal capacity of the battery, and the erroneously judged nominal capacity causes an error in the calculation of the SOC indicating the state of charge of the battery. As a result, the fuel efficiency of the vehicle may be lowered, and a false condition may occur in the entry condition of the ISG (Idle Stop & Go).

The present invention has been made in the technical background as described above. It is an object of the present invention to provide a new method of calculating the state of charge of a battery using an ultrasonic sensor instead of a separate battery sensor.

According to an aspect of the present invention, there is provided an ultrasonic sensor system for transmitting an ultrasonic signal located on one surface of a vehicle battery, and receiving the ultrasonic signal on another surface facing the one surface. And a receiver, wherein the receiver calculates a transmission speed of the ultrasonic signal, and calculates an electrolyte density inside the battery based on the transmission speed to estimate a state of charge (hereinafter, SOC) of the battery. .

The receiving unit calculates the transmission rate by using a clock generator for generating a clock having a predetermined time interval and the transmission time of the ultrasonic signal measured by the clock generator, and at least one for estimating the state of charge of the battery. And a processor for calculating the transmission rate of the ultrasonic signal, calculating an electrolyte density in the battery, and a program for estimating the SOC, and an internal memory for storing parameters.

The receiver calculates the electrolyte density inside the battery by using an inverse correlation between the electrolyte density inside the battery and the transfer speed and the elastic modulus of the electrolyte inside the battery.

In addition, the receiver compares the electrolyte density inside the battery with an electrolyte density-SOC relationship table, and extracts an SOC matching the electrolyte density inside the battery.

According to another aspect of the present invention, there is provided a method of calculating a state of charge of a battery according to another aspect of the present invention, comprising: calculating a transmission speed of an ultrasonic signal; calculating an electrolyte density inside the battery based on the transmission speed; Estimating the state of charge of the battery based on electrolyte density.

In the calculating of the electrolyte density, the electrolyte density inside the battery is calculated using Equation 1 below.

Equation 1

, v: 전송 속도v =

, v: baud rate

 In estimating the state of charge of the battery, the electrolyte density inside the battery is compared with an electrolyte density-SOC relationship table, and the SOC matching the electrolyte density inside the battery is extracted.

On the other hand, the method for calculating the battery charge state according to the present invention may be written in a program and recorded on a computer-readable recording medium.

According to the present invention, apart from the method of calculating the internal state of charge of the battery using various parameters such as battery current, voltage, and temperature measured by a separate battery sensor, the battery is charged using the electrolyte concentration measured in the ultrasonic sensor. By computing the state, there is an advantage that the operation speed can be improved.

1 is a block diagram of an ultrasonic sensor system for calculating a state of charge inside the battery according to an embodiment of the present invention.
2 is a flowchart illustrating a method for calculating an internal state of charge of a battery according to an exemplary embodiment of the present invention.
3 is a diagram illustrating an example of a change in density of an electrolyte density inside a battery according to a state of charge of a battery;
4 illustrates an example density-SOC relationship.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being 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. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. As used herein, the terms " comprises, " and / or "comprising" refer to the presence or absence of one or more other components, steps, operations, and / Or additions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a configuration diagram of an ultrasonic sensor system for calculating an internal state of charge of a battery according to an exemplary embodiment of the present invention, and FIG. 2 is a flowchart illustrating a method of calculating an internal state of charge of a battery according to an exemplary embodiment of the present invention. to be.

As shown in FIG. 1, the ultrasonic sensor system according to the present invention includes a battery 10, a transmitter 20 positioned on one surface of the battery 10 to transmit an ultrasonic signal, and one of the batteries 10. It may be configured to include a receiver 30 for receiving the ultrasonic signal located on the other surface facing the surface.

The ultrasonic sensor system provides a new method for measuring a state of charge (%) representing the state of charge of a battery in place of the current battery sensor. The ultrasonic sensor system according to the present invention does not require information such as battery voltage, temperature, and current required to calculate an SOC in a conventional battery sensor, and transmits an ultrasonic signal passing through the battery and the electrolyte inside the battery. The SOC is extracted using only the concentration-SOC correlation.

That is, the ultrasonic sensor system according to the present invention is to provide a new platform for calculating the SOC representing the state of charge inside the battery, the SOC operation speed can be dramatically improved under the new platform. An ultrasonic sensor system in which such a function is implemented will be described in detail below.

In general, ultrasonic waves have almost the same properties of sound waves, but also have some properties of light (electromagnetic waves) that the medium reflects at different boundary surfaces. To summarize the characteristics of these ultrasounds,

① It is a longitudinal wave transmitted through solid, liquid, and gas. It is not transmitted in vacuum.

② It has strong strength and straightness, so it can be transferred inside the material.

(3) A change in sensitivity or sensitivity along the direction, that is, directivity is good.

④ The traveling distance is relatively long and the medium reflects at different boundary or discontinuous surfaces.

⑤ Waveform variation occurs depending on the condition.

. Underwater and ultrasonic flaw detectors because of the unique properties of these ultrasounds. Although it is most widely used in ultrasonic processing, medical applications, etc., the present invention uses the principle of ultrasonic flaw detection.

Ultrasonic flaw detection is a method of measuring the thickness of an object and detecting discontinuities in the object by sending ultrasonic waves (0.1-25 MHz) into the object. If the thickness of the object is to be measured, when the ultrasonic beam is incident perpendicularly to the object, the ultrasonic wave is reflected from the opposite side. At this time, the thickness of the object can be easily measured by knowing the time when the ultrasonic wave is incident and returning, or the speed of the ultrasonic wave.

Also, if there is a defect inside the object, moving the transducer (Prob: ultrasonic transmitting and receiving device) on the object will change the time interval and the amount of reflected energy to transmit and receive the ultrasonic wave in the region where the defect is present and the defect-free region. . By comparing the difference between the transmission and reception time interval and the amount of reflected energy of the ultrasonic wave with the appropriate standard data, the location and size of the defect can be known. This inspection method is called pulse-reflection method.

The receiver 30 calculates the transmission speed of the ultrasonic signal transmitted from the transmitter 20 through the inside of the battery 10 by using the characteristics of the ultrasonic signal and the ultrasonic flaw test (S21).

In general, sound waves are longitudinal waves (compressed waves) transmitted by the compression (dense part) and expansion (small part) of the medium, and the speed v depends on the type and temperature of the medium. As the temperature of the medium increases, the speed of sound increases, and the speed can be expressed by Equation 1 below.

[Equation 1]

(Tc : 섭씨온도)

(Tc: Celsius temperature)

Thereafter, the receiver 30 calculates the electrolyte density inside the battery based on the transmission speed of the ultrasonic signal calculated in step S21 (S22).

The speed of sound by the type of medium is determined by the density of the medium and the elastic modulus. In general, the smaller the density, the larger the elastic modulus, the larger the speed of sound, and is generally represented by Equation 2 below.

&Quot; (2) "

, v: 전송 속도v =

, v: baud rate

Here, the modulus of elasticity is a constant indicating the degree of compression when the medium is subjected to a force (pressure), and the larger the value, the less the compression becomes. That is, the speed of sound only relates to the type of medium at a constant temperature regardless of frequency.

Equation 3 is modified to clearly show the relationship between the medium through which the ultrasound passes and the transmission speed of the ultrasound.

 &Quot; (3) "

As can be seen from Equation 3, the transmission speed of the ultrasonic signal passing through the medium is inversely related to the density of the medium.

Thereafter, the receiver 30 estimates a state of charge (SOC) inside the battery based on the electrolyte density calculated in step S22 (S23).

As an example, the receiver 30 compares the electrolyte density inside the battery with an electrolyte density-SOC relationship table, and extracts an SOC matched to the electrolyte density inside the battery. The electrolyte density-SOC relationship table represents a correlation between the electrolyte density inside the battery and the state of charge of the battery, and data calculated through experiments may be prepared as a look-up table.

The correlation between the electrolyte density inside the battery and the state of charge of the battery will be described with reference to FIGS. 3 and 4. 3 is a diagram illustrating an example of a change in density of an electrolyte density inside a battery according to a state of charge of a battery (discharge rate = C / 10).

As shown in FIG. 3, the electrolyte in the upper part of the battery participates in the reaction at the initial stage of discharging, and the electrolyte in the lower part of the battery is expected to participate in the reaction as the discharge proceeds. The concentration of electrolyte in the lower part of the battery is due to the shift of sulfuric acid to water, and relatively light water moves upward and relatively heavy sulfuric acid moves downward due to the difference in specific gravity. In addition, it is predicted that the electrolyte concentration on the PbO2 electrode side decreases faster than the electrolyte concentration on the Pb electrode side. This is because the Pb electrode has higher electrical conductivity than the PbO 2 electrode, and thus the ohmic loss is reduced due to the increased utilization of the active material. Since there is little charge transfer resistance in the separator, there is no difference in concentration.

4 is a contour graph showing the change in SOC distribution inside the battery (discharge rate = C / 10). As the discharge proceeds, the SOC value decreases, the SOC value of the PbO2 electrode decreases slowly than the SOC value of the Pb electrode, the SOC value of the upper battery layer is low, and the SOC value of the cell lower layer is expected to be high. This is because at the initial stage of discharge, the active material is consumed from the upper portion of the battery. In the separator, there is no charge transfer resistance, so the SOC value is zero.

As shown in FIG. 3 and FIG. 4, the correlation between the electrolyte density inside the battery and the SOC may be constructed through testing, and the receiver 30 of the present invention may calculate the electrolyte density calculated using the data. Extract the matching SOC.

On the other hand, in order to perform the series of processes as described above, the receiver 30 generates a clock using a clock generator for generating a clock having a predetermined time interval and the transmission time of the ultrasonic signal measured by the clock generator. At least one processor for calculating a state of charge of the battery, calculating a transmission speed of the ultrasonic signal, calculating an electrolyte density in the battery, and calculating a program for the SOC and an internal memory for storing parameters. It may include.

The above-described method for calculating a state of charge of a battery according to the present invention may be implemented as computer readable codes on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording media storing data that can be decoded by the multimedia device. For example, there may be a ROM (Read Only Memory), a RAM (Random Access Memory), a magnetic tape, a magnetic disk, a flash memory, an optical data storage device and the like. In addition, the computer-readable recording medium can be distributed and executed as a code that can be distributed to multimedia devices connected to a computer network and read in a distributed manner.

While the present invention has been described in detail with reference to the accompanying drawings, it is to be understood that the invention is not limited to the above-described embodiments. Those skilled in the art will appreciate that various modifications, Of course, this is possible. Accordingly, the scope of protection of the present invention should not be limited to the above-described embodiments, but should be determined by the description of the following claims.

Claims (8)

In the ultrasonic sensor system comprising a transmitter for transmitting the ultrasonic signal located on one surface of the vehicle battery, and a receiver for receiving the ultrasonic signal located on the other surface facing the one surface,
The receiver calculates a transmission speed of the ultrasonic signal, and calculates an electrolyte density inside the battery based on the transmission speed to estimate a state of charge (hereinafter, SOC) of the battery.
Ultrasonic sensor system. The method of claim 1, wherein the receiving unit,
A clock generator for generating clocks having a predetermined time interval,
At least one processor for calculating the transmission rate by using the transmission time of the ultrasonic signal measured by the clock generator and estimating the state of charge of the battery;
And a program for calculating the transmission rate of the ultrasonic signal, calculating the electrolyte density in the battery, and estimating the SOC, and an internal memory for storing parameters.
Ultrasonic sensor system.
The method of claim 1, wherein the receiving unit,
Calculating the electrolyte density inside the battery using an inverse correlation between the electrolyte density inside the battery and the transfer rate and the elastic modulus of the electrolyte inside the battery
Ultrasonic sensor system. The method of claim 1, wherein the receiving unit,
Comparing the electrolyte density inside the battery with an electrolyte density-SOC relationship table and extracting an SOC matched to the electrolyte density inside the battery
Ultrasonic sensor system. A method of calculating a state of charge of a battery in an ultrasonic sensor system comprising: a transmitter positioned on one surface of a vehicle battery and transmitting an ultrasonic signal; and a receiver positioned on the other surface facing the one surface to receive the ultrasonic signal.
Calculating a transmission rate of the ultrasonic signal;
Calculating an electrolyte density inside the battery based on the transfer rate; And
Estimating the state of charge of the battery based on the electrolyte density
Battery charging state calculation method comprising a. The method of claim 5, wherein calculating the electrolyte density comprises:
Computing a state of charge of the battery comprising the step of calculating the electrolyte density inside the battery using the equation (1) below.
Equation 1
v =

, v: baud rate The method of claim 5, wherein estimating the state of charge of the battery,
Comparing the electrolyte density inside the battery with an electrolyte density-SOC relationship table, and extracting an SOC matched to the electrolyte density inside the battery.
How to calculate the battery charge status. A computer-readable recording medium having recorded thereon a program for executing the battery charge state calculating method according to any one of claims 5 to 7.

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