KR20090056847A - Internal resistance or equivalent capacitance calculating methord of battery equivalent circuit, and the circuits there of - Google Patents

Abstract

A method for calculating an equivalent capacitor value or an inner resistor according to a factor of a storage battery equivalent circuit, and a circuit for performing the same are provided to enhance accuracy of a measuring value by reducing an error generated in a process for measuring or calculating a phase difference angle. One or more values among a resistor component value(Rs) parallel connected to an equivalent capacitor component, a resistor component value(Ro) serially connected to the capacitor component, and an equivalent capacitor component value are calculated. A measuring current signal having an angular frequency of different three kinds is flowed to a storage battery to be measured. An inner impedance value of the storage battery corresponding to each measuring current signal is calculated. One or more values among the resistor component values and the equivalent capacitor component value are calculated from a relational equation about each component of the inner impedance value and the storage battery equivalent circuit.

Description

Internal Resistance or Equivalent Capacitance calculating methord of Battery Equivalent Circuit, and the Circuits there of}

In general, the equivalent circuit for the alternating current of a battery cell, which is a secondary battery, has been proved to be equivalent to a series circuit of resistance, inductance, and capacitance (R-L-C) components.

 In IEEE 1188-1996 / 2005 STD, in order to diagnose the aging (health presence) condition of a sealed battery, the internal impedance of the battery is most correlated with the factors of lattice corrosion or decrease of electrolyte in the electrode plate which is deteriorated according to the year of use. The internal resistance value of nickel-cadmium is also recommended by the manufacturer of nickel-cadmium batteries by measuring only internal resistance components that are considered to be high. This indicates a correlation with the state or state of charge (SOC).

In addition, in recent years, as personal digital assistants (PDAs) and notebook PCs have become more popular and hybrid cars or electric cars have been commercially available, nickel secondary batteries or lithium ion (polymer) -based secondary batteries having a higher degree of electric integration than conventional lead acid batteries have been developed. In the case of such a secondary battery (battery), a number of papers have been published in which the change of each component of the internal equivalent circuit is correlated with the aging state or the state of charge (SOC). have.

In the case of lead-acid batteries, in the internal equivalent circuit represented by the RLC series circuit, the resistance component value (Rs) connected in parallel with the capacitor component indicates the internal resistance of the electrode plate according to the sulfation (SO ₄ ) of the electrode plate. This corresponds to about 40% of the total resistance. In addition, the resistance component value Ro connected in series with this means a connection resistance for the junction point between the pole plates, a joint resistance between the pole and the junction point, and a synthetic resistance corresponding to the ion conductivity resistance of the electrolyte. The ion conductivity of the electrolyte may vary slightly depending on the frequency of the measurement signal.

The capacitive reactance due to the equivalent capacitor component (Xc) is related to the change in the electric field and occurs between two separate pole plates via an insulator. The capacitor component composed of the pole plates has a tendency to fundamentally prevent the voltage or potential difference between the two conductor plates from changing. Therefore, the presence of a capacitor component in the electrical circuit results in a delay of the alternating voltage relative to the alternating current.

In addition, the inductive reactance component (X _L ) is an inductor component formed at the connection terminal portion of the battery pole plate and depends on the structure of the pole plate and the connection part between the pole plates and the surrounding medium. The inductive reactance X _L does not affect the current of the direct current component, but the alternating current flowing during the measurement is delayed by the inductor component, which is added to the equivalent capacitor component Xc to affect it.

In general, a battery performs its function through a discharge cycle that converts chemical energy into electrical energy and a charge cycle that converts electrical energy into chemical energy. I'm done.

In the case of lead-acid batteries, the sulfate (sulfate, SO ₄ ) is combined with the electrode plate during discharge to generate water (H ₂ O), resulting in a lower specific gravity. During charging, the combined sulfate is returned to the electrolyte to increase the specific gravity. do. However, during long periods of charging / discharging cycles, sulfates that are stuck during discharge (including self-discharge) do not escape during charging, but stick to the plates as they are. This is called sulfate.

That is, the sulfate (SO ₄ ) forms a bond with the pole plate and a bond between the SO ₄ in the active material layer to cover the pole plate in the form of a film and to form an insulating film to block the passage of the chemical electric reaction, as described above When this occurs, the voltage capacity and specific gravity of the battery are reduced, as well as the sulfur molecules of the battery are removed from the electrolyte, thereby making the electrolyte in the battery inefficient.

These phenomena become more severe as the batteries are discharged and the number of charge / discharge cycles is increased. As a result of the repetition of these phenomena, the batteries are at the end of their lifespan.

In addition, the equivalent capacitor component Xc is a capacitive reactance component generated between the pole plates and is a correlated factor that varies depending on the degree of dry out (depletion of the electrolyte) .The equivalent capacitor component value is equivalent to the internal resistance component value (serial resistance component). Value (Ro) and parallel resistance component value (Rs)) to determine whether the battery electrolyte is depleted (Dry out).

In general, if the battery is operating in the floating state or 100% recombination mode, there is no chemical rebound in appearance, and all overcharge energy is converted to heat and dispersed, so there is no overheating problem. However, when the heat generated by the recombination reaction exceeds the heat dissipation ratio, the temperature of the battery rises and a larger current is required to maintain the floating voltage. Larger currents cause more recombination and heat generation, which further heats the battery's temperature, facilitating evaporation of the electrolyte and consequently depleting the electrolyte (ie dry out) of the battery.

Also, as is well known, when an AC voltage is applied to a battery or a battery is discharged so that a measurement current (AC current) signal having a predetermined frequency flows, the internal circuit of the battery with respect to the AC current has a resistance, inductance, and capacitance (R). As it can be equalized by series circuit of -L-C component, AC voltage signal (impedance voltage) waveform generated between pole terminals of battery is higher than phase of current signal due to L component. The lower the frequency is, the C component tends to delay the phase of the voltage than the phase of the current.

은 100Hz 부근에 있으며 이의 특성을 이용하여 주파수 범위(10~1000Hz)의 정현파 전류를 축전지 셀에 흐르게 함으로써 인덕턴스, 커패시턴스 성분을 제외한 내부저항 성분 (컨덕턴스값의 역수)만에 의한 교류전압 신호만이 측정될 수 있도록 하는 방안도 소개되어 있다.In addition, AC measurement current flows through the sealed lead-acid battery, and the AC voltage generated between terminals of the battery changes the measurement frequency and observes the waveform.

Is near 100Hz, and uses this characteristic to make the sinusoidal current in the frequency range (10 ~ 1000Hz) flow into the battery cell so that only the AC voltage signal is measured by the internal resistance component (inverse of the conductance value) excluding inductance and capacitance components. There are also ways to help.

As a technique for measuring an equivalent internal impedance value correlated with the aging degree of a battery cell, an AC current method and a momentary load discharge method are mainly used.

의 수식원리에 따라 계산된다.In the AC current measuring method, a sine wave-shaped measurement current signal (AC current) I _S flows through a measurement object such as a battery, and thus a voltage drop component due to internal impedance obtained at both ends of the terminal (hereinafter, referred to as internal impedance voltage (V _IS)). Signal) and calculate the internal impedance value based on them. That is, when the measured current signal I _S is generated from the constant current source or the voltage source and flows through the AC 4-terminal network across the terminals of the battery cell under measurement, the sine wave impedance voltage is formed on the cell voltage V _DC at the battery terminal. The signals V _IS are superimposed and measured. The impedance voltage V _IS signal is coupled as a capacitor and converted and amplified into a pure AC signal through an operational amplifier, so that the measured current signal I _S is converted into a voltage signal through a current sensor (a classifier or a DC converter). The two values are input to a digital measurement circuit (incorporated system) consisting of an A / D converter and a CPU, and by a calculation program mounted on the digital measurement circuit, the composite internal resistance value of the battery is

It is calculated according to the formula principle.

Here, V _{IS and RMS} are effective values of the impedance voltage V _IS , I _{S and RMS} are effective values of the sine wave measurement current signal I _S , and cos (θ) is a phase difference value between them.

On the other hand, when measuring the characteristics of a battery cell during floating charging (that is, connected to a charger and a load in a normal floating charging state), a high frequency ripple voltage is applied to the battery terminal voltage due to a harmonic ripple current component included in the charging current of the battery. Is generated.

      Therefore, it is technically difficult to obtain accurate measured values only by excluding the effects of noise noise caused by the high frequency ripple voltage generated by the charging ripple current and the parasitic impedance of the measuring circuit during charging. The disadvantage is that the system becomes complicated and expensive.

Korean Patent Application Nos. 10-2003 -0028521 and 10-2004 -0007050 filed by the present inventors propose ways to exclude the influence of the charging ripple voltage.

Conventionally, the synthetic resistance value corresponding to the equivalent internal resistance of a measured object such as a battery is obtained by a synchronous detection calculation method or by a predetermined calculation process, the impedance voltage effective value V _s and the AC measured current effective value I _s ) to obtain the internal impedance (Z) from [Equation 1], and then, using the phase difference θ obtained through hardware, synthesized internal resistance component values (R) as shown in [Equation 1] and [Equation 2] below. ) Or by reactance component (X).

또는

or

As described above, in the method of obtaining the impedance effective component (resistance component) by multiplying the internal impedance value Z by the phase difference value cosθ, particularly in the method of accurately calculating the phase angle θ, the internal impedance is determined by the noise of the measurement circuit or the ripple current during charging. Even if the voltage or measurement signal current waveform is distorted or noise is included, and a very precise hardware is adopted to reduce the influence, even if the phase angle θ is measured relatively accurately, the error increases when the phase angle θ is calculated.

In addition, when measuring a battery such as a large-capacity flooded type using a very high frequency current signal, the phase difference between the measured current signal and the impedance voltage signal is close to 90 °. In this case, the mathematical principle of the conventional synchronous detection method is used. Even if you choose to measure the phase angle θ by adopting very precise hardware, the phase difference value cosθ is almost close to zero, so even if an accurate value of 0.5% of the phase angle θ is measured, cos θ has a relatively large error.

수식에 의해 위상차 값 cosθ를 곱하여 내부 저항값을 연산시에는 오차가 증가되는 단점이 있는 것이다. therefore,

The error is increased when the internal resistance value is calculated by multiplying the phase difference value cos θ by the equation.

In addition, since the internal synthetic resistance value of the battery equivalent circuit does not have an absolute proportional relationship with the aging state (SOH), the aging state (SOH) of the battery is more comprehensively analyzed in order to properly determine the replacement time according to aging of the emergency power storage battery. Therefore, the series resistance component including the connection resistance between the junction points between the pole plates and the coupling resistance between the pole and the junction points, as well as the composite internal ohmic measuring of the battery equivalent circuit, as well as the components of the battery equivalent circuit components. The value of Ro or equivalent capacitor and the value of parallel internal resistance (Rs) connected in parallel with each other are obtained, and the results are analyzed comprehensively to accurately determine the aging state of the battery and to determine what factors cause the battery to age. There is a need to do so.

의 수식 관계의 위상각 θ을 필수적으로 구하지 않으면서, 3가지의 주파수를 가지는 측정전류신호에 대하여 이에 해당된 내부 임피던스 값(Z)을 측정하여 구하고, 상기 피측정 축전지에 대한 등가회로의 수식적 결과에 의하여 얻어진 각각의 내부 임피던스 값을 가지는 3개의 4차 연립 방정식에서 3개의 미지수 항인 내부 저항 요소성분에 해당되는 Rs, Ro 값 또는 등가 캐패시터 성분에 해당되는 Xc의 값을 구할 수 있다.The present invention has been made for the purpose of calculating the value corresponding to each internal resistance component and or equivalent capacitor component of each element of the battery, which is used in the conventional internal resistance calculation method

Without necessarily calculating the phase angle θ of the relation of the equation, the internal impedance value (Z) of the measured current signal having three frequencies is measured and calculated, and the equivalent circuit of the storage battery under test is obtained. As a result, in the three fourth-order simultaneous equations having the respective internal impedance values, the values of Rs, Ro, or Xc corresponding to the equivalent capacitor component may be obtained.

In still another embodiment, when the phase difference value cos θ between the measured current signal and the impedance voltage signal is calculated by a synchronous detection algorithm or a measuring method using a hardware circuit, two angular frequencies (ω ₁ , From the four quadratic simultaneous equations obtained by measuring the respective internal impedance values (Z ₁ , Z ₂ ) for the measured current signal with ω _2, ) and the result of the equation of the equivalent circuit for the battery under test The three unknown terms Rs, Ro, or Xc, which are the battery equivalent circuit component elements, can be calculated, and in addition, the series reactance X _L value, which is an inductive reactance component, can be calculated.

Also, as another example, in a similar manner, two secondary simultaneous pairs having respective impedance values are obtained for the measured current signals having two frequencies, and the mathematical results of the equivalent circuits. From the equation, the composite internal resistance (Rint) element and the equivalent capacitor component (Xc ') of the battery cell can be obtained.

In addition, the present invention converts an AC signal into a DC signal through an effective mean conversion unit to reduce the amount of CPU required by the calculation method and inputs the equivalent circuit component into the CPU. We present an economical and simple measurement calculation circuit that can operate.

In the calculation method proposed in the present invention, the Rs, Ro value corresponding to each internal resistance component that is an element component of a battery (secondary battery) equivalent circuit, and the value of Xc corresponding to the equivalent capacitor component are determined through three fourth order simultaneous equations. As a method of obtaining, the error generated in the process of measuring or calculating the phase difference θ in the conventional measurement operation method can be reduced, thereby increasing the accuracy of the measured value.

In another embodiment, when the phase difference value cos θ between the measured current signal and the impedance voltage signal is calculated by a synchronous detection algorithm or a measurement method using a hardware circuit, two angular frequencies (ω ₁ , Obtain the internal impedance values (Z ₁ , Z ₂ ) for the measured current signals with ω _2, ) and obtain the Rs, Ro values or the corresponding values for each internal resistance component by the common solution of the four quadratic simultaneous equations, or Since the value of the equivalent capacitor component Xc can be obtained, the value can be obtained relatively easily using an embedded system with a limited computation speed.

The battery equivalent circuit element component that can be obtained by the above calculation is at least three, wherein the parallel internal resistance (Rs) is a factor that correlates to the sulfation of the electrode plate in the case of lead-acid batteries, and the series internal resistance (Ro) ) Is the sum of the internal connection resistance to the junction point between the pole plates, the coupling resistance between the pole and the junction point, and the ion conductivity resistance of the electrolyte. In addition, the equivalent capacitor reactance component (Xc) value is a correlation factor that varies according to the electrolyte depletion state (Dry out) of the battery, and the equivalent capacitor component value is compared with the parallel resistance component (Rs) to deplete the battery electrolyte (Dry out). ) Can be judged.

In addition, the hardware configuration proposed as an embodiment of the present invention is a circuit capable of implementing the above-described calculation principle or method, and employs commercially available effective mean value (DC) converting means 102 or 103 to relatively simplify the circuit required for the measurement operation. can do. In addition, since the measurement signal obtained through the effective mean value (DC) converting means 102 or 103 is a direct current component, a large amount of sampling is not required, and a calculated value required for calculating an internal impedance value is relatively small. Therefore, the CPU processing speed is not required because the fast CPU processing speed is not required, and the relatively accurate measurement value can be calculated.

1 shows an equivalent circuit of a theoretical battery, and FIG. 2 shows components of each element of the battery equivalent circuit obtained in the present invention.

_Three measured current signals having angular frequencies ω ₁ , ω ₂ , and ω ₃ can be obtained by measuring the internal impedance values (Z ₁ , Z ₂ , Z ₃ ) of the corresponding batteries. Here, the corresponding impedance values Z ₁ , Z ₂ , and Z ₃ for the respective frequencies may be represented by Equations 11 to 13 below.

In Equations 11 to 13, ω ₂ = k * ω ₁ and When a frequency corresponding to a condition that satisfies ω ₃ = m * ω ₁ (where k and m are positive real numbers) is selected and a measured current signal having the corresponding frequency flows to the battery under test, Impedance values Z _1, Z ₂ and Z ₃ are represented by the following equations (14) to (16) in the form of a real term and a complex term.

It can also be simplified as follows.

It can also be simplified as follows.

It can also be simplified as follows.

와 같이 실수항 제곱과 복소수항 제곱의 합으로 표시될 수 있으므로, 각각의 내부 임피던스 제곱값은 수학식 17 내지 수학식 19 으로 표시될 수 있다. On the other hand, in general, in the RLC equivalent circuit, the magnitude of the absolute value of the synthesized internal impedance is

Since it can be represented by the sum of the real term square and the complex term square as shown, each internal impedance square value can be represented by equations (17) to (19).

Wherein Z ² _1, Z ² ₂ and Z ² ₃ are For each measured current signal with angular frequencies ω _1, ω _{2 and} ω ₃ , the square of the absolute value of each internal impedance obtained by measuring the internal impedance.

As described above, three angular frequencies ω _1, ω ₂ , By selecting each frequency corresponding to ω ₃ and passing the measurement current signal having the frequency, the squares of the internal impedances Z ² _1, Z ² ₂ and Z ² ₃ can be measured and calculated through the measurement calculation circuit. .

On the other hand, although there are differences depending on the type of battery (eg lithium ion), manufacturing method, type of battery, size structure of the capacitor and the properties of the insulator, in general, when measuring unit batteries, three angular frequencies (ω _1, ω _{2 ,} ω ₃ ) is preferably less than 1KHz, where the series inductance term ωL in Equations 17 to 19 becomes negligibly small (almost zero).

에 가까워져 임피던스전압 신호와 측정전류 신호의 위상이 거의 일치되게 된다. For example, in the case of a sealed lead acid battery, when the angular frequency (ω _1, ω _2, ω ₃ ) of the measurement current signal is selected to about 300 Hz, the impedance voltage signal is about 50 to 70 ^o based on the measurement current signal. Resonance point based on angular frequency (ω _1, ω _2, ω ₃ ) about 100Hz

As the phase is close to, the phases of the impedance voltage signal and the measured current signal become almost coincident.

을 무시할 수 있게 되므로 상기 직렬 인덕턴스 항

을 영(0)으로 취하여 각 요소 성분을 연산하여도 이의 연산 결 과값의 정확성이 확보될 수 있게 된다.When the angular frequency (ω _1, ω _2, ω ₃ ) is selected to 100 Hz or less, the inductive reactance component (X _L ), which is the series inductance term, among the equivalent circuit element components of the battery under test is close to a very small value (almost zero). The condition of Equation 20 may be satisfied. Therefore, the series inductance term in Equations 17 to 19

Can be ignored so that the series inductance term

When 0 is calculated and each element component is calculated, the accuracy of the calculation result can be ensured.

In this case, the equations (17) to (19) correspond to three quadratic simultaneous equations having only the unknown terms Rs, Ro, and Xc, respectively, since all terms corresponding to ωL are eliminated. The value of, Ro, or Xc can be obtained.

In general, it is sometimes difficult to analytically find a common solution (root) that completely satisfies the three nonlinear quadratic equations. Particularly, in the case of calculating the common solution (root) using an embedded system with extremely limited computing power, the nonlinear equations are easy to find since the common time (root) is practically limited. We may need a computational algorithm that can convert the form of into a preprocessing and efficiently obtain a reliable common solution within a limited time.

The algorithms can be solved by linearizing nonlinear equations, or a recursive method (numerical analysis) can be used, and three to four such as Newton-Rapson are known. Adopt appropriate algorithm and can use efficiently.

1,

2,

3 를 포함하고 있다.) ③ 상기에서 정의된 편미분 방정식을 사용하여 Jacobian maxtirx (J)를 정의하는 것이다.Briefly introduce the steps to solve the nonlinear simultaneous equations using Newton-Rapson: (1) Arrange all the simultaneous equations to be solved in the form of f (x) = 0. ② Newton Raphson function (f) (E.g., a given process consists of three simultaneous equations (f1, f3, f5) with three unknown terms.

One,

2,

3)) ③ Jacobian maxtirx (J) is defined using the partial differential equation defined above.

In addition, when using the recursive method (numerical analysis), the convergence problem (convergence rate and convergence speed) of the common solution and its accuracy problem can be expected, and the numerical result is determined according to the expected initial value of the common solution. The dependence can be very large.

In reality, since the internal impedance value of the battery or the range of the equivalent circuit component can be estimated, an efficient method can be adopted in which an initial value similar to a common solution to be obtained can be put in place so that an accurate solution can be quickly obtained.

In addition, if you put the initial value that has a considerable difference from the common solution to be actually obtained, it may take a long time and may not be able to find a perfectly accurate solution. Therefore, in this case, Z ² _1, The difference between the Z ² ₂ and Z ² ₃ values and the expected initial values common to the above equations (17) to (19) is included, and the difference between the calculation result values on the right side is within a predetermined limit (usually within ± 1% in consideration of the measurement accuracy). If a solution that satisfies the condition is found, it is necessary to judge it as a correct common solution (root).

In addition, in selecting the magnitudes of the angular frequencies ω _1, ω _{2, and} ω ₃ , when a large difference between the magnitudes of the angular frequencies is selected, the reliability of the accuracy of the common root obtained through the calculation result is high. Since it becomes high, it is necessary to optimize the selection of the three angular frequencies (ω _1, ω _2, ω ₃ ) magnitude difference (interval).

On the other hand, the above method for calculating the common solution (root) of nonlinear quadratic equations using an embedded system with extremely limited computing power requires a lot of computation time and is subject to practical time constraints, thus reducing its industrial use value. There is.

In this case, as another embodiment of the present invention, cosθ, which is a phase difference between the measured current signal and the impedance voltage signal, can be accurately measured by a conventional synchronous detection algorithm or a measurement method using a hardware circuit. According to the idea, the internal impedance value (Z ₁ , Z ₂ ) of the battery under measurement for the measured current signal having _two angular frequencies (ω _1, ω _2, ) is measured or presented in the present invention. Three or more unknown terms Rs, Ro, and equivalent capacitors, which are the battery equivalent circuit components, from four quadratic simultaneous equations represented by real terms and complex terms obtained from the internal equivalent circuits of the battery. Xc or X _L of inductive reactance can be obtained.

Hereinafter, the operation principle thereof will be described in detail. Looking at the equations (14) to (15) is composed of the sum of the real term and the complex term, in this embodiment each of the internal for the measurement current signal having _two angular frequencies (ω _1, ω _2, ) The impedance values Z ₁ and Z ₂ may be briefly expressed as in Equations 21 and 22 below.

여기서 각주파수는 ω₁ 이다.

Where the angular frequency is ω ₁ .

여기서 각주파수는 kω₁ 이다.

Where angular frequency is kω ₁ .

In addition, when the phase difference angle (phase difference between the measured current signal and the impedance voltage signal) calculated by the synchronous detection calculation method or the measurement method using a hardware circuit is θ, the internal impedance is expressed as shown in Equation (23).

는 내부 임피던스의 절대값을 나타 내는 것으로, 임피던스 전압 실효치(V_IS,RMS)를 측정전류신호 실효치(I_S,RMS)로 나눈 값이며 측정 연산회로를 통해 용이하게 연산할 수 있다. here

Denotes the absolute value of the internal impedance, which is the value obtained by dividing the impedance voltage rms (V _{IS, RMS} ) by the measured current signal rms (I _{S, RMS} ) and can be easily calculated through a measurement calculation circuit.

Further, from Equations 21 to 23, A ₁ = │Z ₁ │ * cosθ, B ₁ = │Z ₁ │ * sinθ, A ₂ = │Z ₂ │ * cosθ, and B ₂ = │Z ₂ It can be seen that sinθ is established.

Also, cosθ and sinθ values are the values that can be obtained by the measurement calculation method using a conventional synchronous detector operation method or a hardware circuit, and thus the angular frequency ω ₁ when constants A _1, B ₁ and angular frequency is ω ₂ Can compute A ₂ and B ₂ values.

Further, from Equation 14 or 15 and Equation 21 or 22, the constants A ₁ , B ₁ , A ₂ , and B ₂ represented by real and complex terms with respect to the angular frequency ω _{1 can be obtained} . Equations 24 to 27 may be derived.

Where the constants A ₁ , B ₁ , A ₂ , B ₂ , and k, ω ₁ are positive real numbers and are known or can be obtained from measurement results using conventional synchronous detection or hardware circuits. .

Since the equations 24 to 27 are quadratic simultaneous equations having four unknown terms (Rs, Ro, Xc, and X _L ), these equations are derived from four quadratic simultaneous equations composed of the equations (24) to (27). obtaining a common year can be easily calculated for the unknowns, wherein the value of Rs, Ro, or Xc, X or _L battery element equivalent circuit component values.

As described above, if the two angular frequencies (ω _1, ω _2, ) are selected below an appropriate magnitude, the ω ₁ L term is almost zero enough to be ignored, and it is preferable to calculate the series inductance term ω ₁ L after zero. one, of Fig above four unknowns, wherein the including ω ₁ L by the equation because it is composed of four secondary simultaneous equations with four unknowns calculated on the handle in terms unknown to ω ₁ L, wherein Rs, Ro, Alternatively, the value of Xc or X _L can be obtained.

In addition, as described above, the cos θ and sin θ values obtained by the conventional synchronous detection calculation method or the measurement method using a hardware circuit vary according to the magnitude of the measured current signal frequency of the battery under measurement. It is more preferable to calculate the above four unknown terms which are battery equivalent circuit element component values by taking the value obtained by the measurement current signal frequency corresponding to the average value of ω _1, ω _2, ).

In the battery equivalent circuit shown in Fig. 2, the internal resistance component Rs value connected in parallel with the capacitor component Xc among the component components of the equivalent circuit obtained from the system equation through the above-described calculation process is It is the internal resistance of the electrode plate due to sulfation of the electrode plate, which is approximately 40% of the total series resistance.

The Ro value, which is a series internal resistance component of the battery equivalent circuit element, corresponds to the sum of the connection resistance to the junction point between the pole plates, the coupling resistance between the pole and the junction point, and the ion conductivity resistance of the electrolyte solution. May be measured slightly differently depending on the measurement current signal frequency.

Further, among the battery equivalent circuit element components, the Xc value, which is the equivalent capacitor component obtained from the simultaneous equation, indicates a value correlated with the degree of dry out of the electrolyte. That is, when the Xc value of the equivalent capacitor component is analyzed to be relatively different from the normal battery in comparison with the resistance component Rs connected in parallel, the electrolyte of the battery under test is depleted (Dry out). It can be judged.

As shown in FIG. 2, since the circuit characteristics of the battery are a series / parallel circuit represented by RLC, the amount of change of each component of the equivalent circuit of the battery is accurately calculated according to the present invention, and as a result, the aging state of the battery and The degree of correlated property change can be assessed.

In addition, in FIG. 1, R _terminals represent connection resistances of the pole terminals, R _{straps & posts} are connection resistances of the junction points between the pole plates, and R _electrolyte represents the ion conductivity resistance of the electrolyte. Where R _electrolyte is the resistance that changes with frequency.

The sum of the internal resistance components (R _terminals + R _{straps & post} + R _electrolyte ) shown in FIG. 1 may be simplified by the synthetic internal resistance (Internal Ohmic Resistance) shown in FIG. 3, and Equations 11 to 16 Since is composed of a real term and a complex term, if you compare the schematic equivalent circuit of the battery shown in Figure 3 and the configuration terms of the above equations (14) to (16), two angular frequencies (ω _11, ω ₁₂ ) It can be seen that the real terms of the impedance values Z _{11 and} Z ₁₂ correspond to the composite internal resistance value (Rint), and the complex term represents the capacitor value (Xc ').

Therefore, the impedance current (Z _11, Z obtained through a measurement calculation circuit presented in the present invention or known in the art) by flowing a measurement current signal corresponding to two frequency signals such as angular frequency ω _11, ω _12, etc. ₁₂ ) and two second simultaneous equations obtained from the results of Equations 28 and 29, the ω ₁₁ L value approaches zero when the measured current signal frequency is less than or equal to 100 Hz according to the technical idea described above. Therefore, the values of the composite internal resistance Rint and the capacitor component Xc ', which are unknown terms, can be calculated. Where ω ₁₂ is k * ω ₁₁ , ω ₁₂ = k × ω ₁₁ and k is a positive real number.

therefore,

therefore,

In addition, in the above formula, Z ₁₁ │, │ Z ₁₂ │ mean absolute values of the impedance values Z _11, Z ₁₂ , and Z ₁₁ ² , Z ₁₂ ² are the impedance values Z _11, Z ₁₂ ) means the square value.

In addition, since the equations (14) to (16) are composed of the sum of the real term and the complex term, and the results of the equations (28) and (29) also consist of the sum of the square terms of each of the real term and the complex term, Rint may correspond to a real term in Equation 30 and may be represented by Equation 30.

IEEE 1188-1996 STD recommends to diagnose the aging status of sealed lead acid batteries by measuring the synthetic internal resistance value corresponding to the internal resistance component (or conductance) of the battery.

Such embodiments of the present invention, the phase difference θ value between the internal impedance voltage (V _IS ) and the measured current signal (I _S ) in calculating the composite internal resistance, element-specific internal resistance or equivalent capacitor value of the battery equivalent circuit. Without measuring or calculating, the effective values of the internal impedance voltage (V _IS ) and the measured current signal (I _S ) of the battery can be obtained to measure the internal resistance of the battery, thereby ensuring accuracy in the measurement operation.

In a more specific embodiment, a process in which the effective values required for the measurement operation are calculated from the instantaneous values of the internal impedance voltage Vis and the measurement current signal Is is calculated through an operation program in the numerical operation apparatus called MPU. It looks like this:

,

를 우선적으로 연산한다. When the period of the impedance voltage Vis and the measured current signal Is is determined, the instantaneous values of the impedance voltage Vis and the measured signal current Is for one period are read and averaged during the period, and their average values are obtained.

,

Calculate first.

와 측정전류신호(Is)의 평균치

와 내부 임피던스 전압의 순시치 및 측정전류신 호의 순시치를 이용하여 다음 [수학식 31] 및 [수학식 32]와 같이 임피던스 전압실효치(V_IS,RMS)와 측정전류신호 실효치(I_S,RMS)를 연산함으로써 구할 수 있다.Further, the internal impedance of the voltage effective value (V _{IS, RMS)} and the rms value of the measured current signal _{(Is) (I S, RMS} ) is the average value of the impedance of the voltage during the one period calculated from the

And average value of measured current signal Is

Using the instantaneous value of the internal impedance voltage and the instantaneous value of the measured current signal _{, the} impedance voltage effective value (V _{IS, RMS} ) and the measured current signal effective value (I _{S, RMS} ) as shown in [Equation 31] and [Equation 32] below. Can be obtained by calculating

은 저장된 임피던스 전압 파형의 각 순시치를 의미하고

은 저장된 측정전류 신호 파형의 각 순시치를 의미하고 N은 전체 주기 동안의 순시치 저장 회수이다. here,

Means each instant of the stored impedance voltage waveform

Is the instantaneous value of each stored measurement current signal waveform and N is the number of instantaneous values stored for the entire period.

In addition, as described above, Z ² _1, Z ² ₂ Z ² ₃ is the square of the impedance voltage effective value (V _{IS, RMS} ) divided by the measured current signal effective value (I _{S, RMS} ) squared. The ripple noise voltage is often mixed with the internal impedance voltage signal due to the charging current during floating charging when calculating the value, so that the charging ripple noise in such a large ripple noise environment is calculated. The square of the impedance voltage effective value (V _{IS, RMS} ) is obtained by excluding the influence of the charging current ripple from the voltage signal including the voltage and only by the true value of the impedance voltage Vis induced by the measurement current signal Is. We need a way to make it work.

As an embodiment for realizing the present method, the calculation method presented in the patent (Korean Patent Application No. 10-2003-0028521) filed by the present applicant can be used.

To explain this, first, in the first section T1, the ripple voltage instantaneous value (Vrp) generated by the charging ripple of the battery cell during floating charging without flowing the measurement current signal Is is measured, stored, read and stored. The difference between the internal high speed timer / counter value tmin1 at the moment when the voltage instantaneous voltage Vrp reaches the lowest point and the counter value tmin2 reaching the next lowest point is calculated. This value is a counter value (trp) corresponding to one cycle period (Trp) of the ripple voltage instantaneous value (Vrp) signal, and the time required for accurate measurement thereof is at least one cycle longer than the aforementioned vibration period of the harmonic ripple voltage. This takes

The stored voltage instantaneous value Vrp is shifted and stored in the memory inside the MPU 11 at intervals of one cycle period Trp and is always updated with the latest data. After the ΔT time, the measurement current signal Is flows in the second section T2 and increases to the value trp corresponding to the Nth cycle Trp after the fast timer / counter value tmin1 is input. Is interrupted at the moment (that is, the counter value becomes tmin1 + N × trp) and the interrupt program is executed, and the impedance of the cycle ripple voltage signal (Vrp) already stored in the memory and the current input through the D / A converter The instantaneous alternating voltage (Vrp + Vis) value including the voltage (Vis) and the ripple voltage (Vrp) is read during the period (trp) and is not affected by the ripple voltage from the difference between the two values ((Vrp + Vis)-Vrp). The impedance voltage (Vis) value or the impedance voltage effective value (V _{IS, RMS} ) can be obtained.

In the above, a method of calculating the period trp by measuring the lowest point is presented. However, the period trp may be calculated using the waveform highest point. In addition, if the period trp can be more easily calculated by measuring the instantaneous AC voltage value Vrp + Vis, the measured current signal Is flows in the section T1 to read the instantaneous AC voltage Vrp + Vis value. Store and read the value of the ripple voltage instantaneous value (Vrp) in the period (T2) and obtain the pure impedance voltage (Vis) value or the impedance voltage effective value (V _{IS, RMS} ) from these two values through the calculation method described above. Can be calculated.

In addition, another embodiment for realizing the above scheme, after the ripple voltage signal generated by the charging current ripple of the battery cell during the floating charge passes through the appropriate filter means harmonic ripple voltage (V _{RP, FLT} ) In this case, the square value of the impedance voltage effective values V _{IS and RMS} that are not affected by the harmonic ripple voltages V _{RP and FLT} may be calculated through the calculation process of another embodiment as described below.

First, the harmonic ripple voltages V _{RP and FLT} are obtained at regular intervals in the period T1 in which the measurement current signal Is does not flow.

을 할당된 특정 메모리(M1)에 입력시킨다. 이후 두 번째 획득시점(T_2,RP)에서 리플전압 순시치(V_RP,FLT)를 획득하여 기준값 V_O를 차감하고 상기와 같이 제곱승 연산을 행한다. 이후 연산 결과인

를 메모리(M1)에 이미 저장되어 있는 리플전압 제곱값

에 더하고 이 결과를 다시 메모리(M1)에 저장하면 상기 메모리(M1)에는

값이 저장된다. In the case of the first acquisition time point T _{1, RP} , the squared power is obtained after subtracting the reference value V _O calculated in advance from the obtained instantaneous values V _{RP, FLT} .

Is input to the allocated specific memory M1. Thereafter _{, the} instantaneous ripple voltage values V _{RP and FLT} are obtained at the second acquisition time point T _{2, RP} , and the reference value V _O is subtracted, and the square power operation is performed as described above. The result of the operation

Ripple voltage squared already stored in the memory M1

And store this result again in memory M1,

The value is stored.

값이 저장된다.Thereafter, the above-described series of operations and storage processes are repeated at each acquisition point of a predetermined periodic interval (for example, half cycle or one period of commercial power frequency) during the predetermined integration period T _D selected through the above-described process. As a result, the specified memory M1 has a first arithmetic value.

The value is stored.

값을 지정된 별도의 메모리(M2)에 저장한다. 두 번째 획득시점(T_2,RP)에서 교류순시전압(V_SM)을 획득하여 기준값(VO)를 차감하고 상기와 같이 제곱승 연산을 행한다. Then, when the measurement current signal Is flows in the battery cell in order to obtain the impedance voltage V _IS in the second section P2, the harmonic ripple voltages V _{RP and FLT} after passing through the noise removing circuit and the impedance voltage ( AC instant voltage V _SM mixed with V _IS is obtained. By acquiring the AC instantaneous voltage V _SM at regular intervals by a method similar to the above, in the case of the first acquisition time T _{1, SM} , the reference value obtained by calculating in advance from the obtained AC instantaneous voltage V _SM ( Calculated by subtracting V _O ) and then multiplying this result again

The value is stored in the specified separate memory (M2). Acquiring the AC instantaneous voltage V _SM at the second acquisition point T _{2, RP} and subtracting the reference value VO and performing a square power operation as described above.

값을 이미 메모리(M2)에 저장되어 있는

값과 더하여 이 결과를 다시 메모리(M2)에 저장한다. 따라서 상기 메모리(M2)에는

값이 저장된다. The result of the operation

Value is already stored in memory (M2)

In addition to the value, the result is stored in the memory M2 again. Therefore, in the memory M2

The value is stored.

값이 지정된 메모리(M2)에 저장된다. Subsequently, if the above-described series of operations and storage processes are repeated at each acquisition point of a predetermined periodic interval during the predetermined integration period TD, the second arithmetic sum is a result.

The value is stored in the specified memory M2.

값이 저장되어 있고, 메모리(M2)에는 교류순시전압(V_SM)을 제곱하고 일정 주기동안 적분을 행하여 얻어진 결과인

값이 저장되어 있다. After the above-described series of steps, the memory M1 has a result obtained by squaring the harmonic ripple voltages V _{RP and FLT} after passing through the noise canceling circuit and integrating for a predetermined period.

The value is stored, and the result obtained by squaring the AC instantaneous voltage (V _SM ) and integrating for a predetermined period is stored in the memory M2.

The value is stored.

) 연산을 취하여 상기 측정하고자 하는 정확한 임피던스 전압(V_IS)를 얻을 수 있게 된다.In addition, by subtracting the two values stored in the memory M1 and the memory M2 and performing a division operation on the predetermined integral period T _D previously applied, the square value of the pure impedance voltage V _IS effective value is calculated. You can get the square root of the

) To obtain the exact impedance voltage V _IS to be measured.

In the above, in order to easily explain the gist of the present technology, the preceding section is represented as the section P1, and the method described above is a method of acquiring only the harmonic ripple voltages V _{RP and FLT} without flowing the measurement current signal Is in this section. The same result can be obtained even by calculating the AC instantaneous voltage V _SM first by flowing the measurement current signal Is in the preceding section P1.

In order to implement the calculation principle or calculation scheme presented in the present invention, the battery cell voltage and internal impedance measurement circuit of the patent application No. 10-2004-0099962 filed by the applicant in the Republic of Korea can be adopted to use the calculation process The program which can implement | achieve easily can be mounted.

On the other hand, the above calculation methods include the step of calculating the effective value of the measurement current signal Is and the impedance voltage signal waveform by the CPU, such a measurement calculation circuit can be configured relatively simply, but the measurement waveform Since the instantaneous value of the waveform corresponding to several dozen or more times in one cycle must be read and calculated, it has a disadvantage of increasing the amount of calculation.

In all the calculation methods used in the embodiments of the present invention, since the effective values of the impedance voltage signal Vis and the measurement current signal Is are required at the time of calculation, the same as the embodiment of the present invention of FIG. By using a relatively simple measurement calculation circuit, it is possible to easily calculate and calculate the respective internal impedance rms values corresponding to the two to three frequencies.

In FIG. 4, the measured current signal Is is converted into an average value by the effective mean value DC converting means 102, and the impedance voltage signal Vis also undergoes an amplification and filtering means 101, and then another effective mean value DC. The conversion means 103 converts the average value.

The effective mean value (DC) converting means 102 or 103 converts an AC signal into a DC signal and may use a commercially available integrated circuit device called an RMS to DC converter.

The average values are converted into digital values through the ADC conversion circuit 104, and an internal impedance RMS value is calculated by the average value in the CPU 105.

Since the average value converted by the effective mean value (DC) converting means 102 or 103 is a DC component signal, a relatively accurate value can be obtained by calculating a relatively accurate value even if the sampling rate is a little slow, and measured with the average value of the impedance voltage signal Vis. The internal impedance effective value can be calculated by dividing the average value of the current signal Is.

The effective mean value (DC) converting means (102 or 103) is called an RMS to DC converter. For example, commercially available devices include AD637 model of ANALOGE DEVICE, MX536 model of MAXIM, or LTC1966 model of LINEAR TECHNOLOGY. have.

Preferred embodiments of the present invention described above, are disclosed for the purpose of illustration only, the solution of the technical idea or technical problem of the present invention is applicable to all secondary batteries (storage battery), Various permutations, modifications, and changes will be possible to those skilled in the art without departing from the technical spirit of the present invention while using the technical spirit as it is. Should be regarded as falling within the scope of the claims.

1 is an electrical equivalent circuit showing the internal components of the battery.

2 is an equivalent circuit represented by each series equivalent resistance of a battery, the sum of the series connection resistance and the ion conductive resistance of the electrolyte, the parallel connection resistance, and the equivalent capacitor element component.

Figure 3 is a schematic equivalent circuit represented by the composite internal resistance and equivalent capacitor element components of the battery.

Figure 4 is an embodiment of a measurement operation circuit for implementing the measurement operation method of the present invention.

Claims (12)

A method of obtaining at least one of a resistance component value (Rs) connected in parallel with an equivalent capacitor component of a battery equivalent circuit, a resistance component value (Ro) connected in series with the capacitor component, or an equivalent capacitor component value (Xc), A measurement current signal having three different angular frequencies (ω _1, ω _2, ω ₃ ) flows to the battery under measurement, and the internal impedance value of the battery corresponding to each measurement current signal (Z ₁ , Z ₂₎ , Z ₃ ); Calculating one or more of the values of Rs, Ro, and Xc from relational expressions for the internal impedance (Z ₁ , Z ₂ , Z ₃ ) values and respective element components of the battery equivalent circuit; Element component value calculation method of a battery equivalent circuit comprising a. The method of claim 1, The relationship is

Is defined by three nonlinear quadratic equations such as In the above equation, Z ₁ ² , Z ₂ ² , Z ₃ ² are the squares of the absolute values of the respective internal impedances Z ₁ , Z ₂ , Z ₃ , k and m are positive real numbers, respectively, ω ₂ = kω ₁ and ω ₃ = mω ₁ , wherein the element component value calculation method of the battery equivalent circuit is characterized in that it is a value. The method of claim 2, In the simultaneous equation, the elemental component of the battery equivalent circuit characterized in that the values of the angular frequencies (ω _1, ω _2, ω ₃ ) are calculated such that the values of ω ₁ L, kω ₁ L and mω ₁ L are approximated to zero. How the value is calculated. At least one of a resistance component value (Rs) connected in parallel with an equivalent capacitor component of a battery equivalent circuit, a resistance component value (Ro) connected in series with the capacitor component, an equivalent capacitor component value (Xc), or a series reactance value (X _L ) As a way to get the value, A measurement current signal (I _s ) having two different angular frequencies (ω _1, ω ₂ ) flows to the battery under measurement, and the internal impedance value (Z ₁ ,) of the battery corresponding to each measurement current signal is passed. Obtaining Z ₂ ); Obtaining a current measurement signal (I _s) and the mutual phase difference value (cosθ sinθ or) of the internal impedance voltage (V _Is) by the measured current signal flowing through the secondary battery; Calculating one or more of the values of Rs, Ro, Xc, and X _L from relational expressions for the internal impedance (Z ₁ , Z ₂ ) value and the phase difference value (cosθ or sinθ); Element component value calculation method of a battery equivalent circuit comprising a. The method of claim 4, wherein The relationship is, Z ₁ = A ₁ + jB ₁ , Z ₂ = A ₂ + jB ₂ ,

Is defined by four quadratic equations such as In the above equation, k is a positive real number, and ω ₂ = kω ₁ , wherein the element component value calculation method of a battery equivalent circuit is characterized in that it is a value. The method of claim 4, wherein The mutual phase difference value (cosθ or sinθ) is characterized in that each other to obtain the flow to two different angular frequencies (ω _1, ω ₂₎ measuring the current signal (I _s) of each frequency corresponding to the average value of the measured battery A method of calculating element component values of an equivalent battery circuit. The method of claim 5, The angular frequency such that ω ₁ L and kω ₁ L values are approximated to 0 in the equation. A method of calculating element components of a battery equivalent circuit characterized in that values of (ω _1, ω ₂ ) are calculated. A method of obtaining at least one of a synthetic internal resistance value (Rint) or a capacitor value (Xc ') of a battery equivalent circuit, A measurement current signal having two different angular frequencies (ω _11, ω ₁₂ ) flows to the battery under measurement, and the internal impedance value (Z ₁₁ , Z ₁₂ ) of the battery corresponding to each measurement current signal is measured. Obtaining; Calculating at least one of Rint or Xc 'from a relationship between the internal impedance (Z ₁₁ , Z ₁₂ ) and the composite internal resistance value of the battery equivalent circuit and the capacitor value; Element component value calculation method of a battery equivalent circuit comprising a. The method of claim 8, The relationship is

Defined as two nonlinear quadratic equations such as In the above equation, k is a positive real number, and ω ₁₂ = kω ₁₁ , wherein the element component value calculation method of a battery equivalent circuit is characterized in that it is a value. The method of claim 8, And a value of the angular frequencies (ω _11, ω ₁₂ ) is calculated such that ω ₁₁ L and kω ₁₁ L are approximated to 0 in the equation. The method according to any one of claims 1, 4 or 8, Internal impedance value of the battery, And calculating a square root of a result obtained by dividing the square of the effective value of the impedance voltage induced by the measured current signal by the square of the square of the measured current signal. In a circuit for measuring and calculating each component element of a battery equivalent circuit. First mean value converting means for converting the measured current signal I _s flowing through the battery under test into an average value; Second average value converting means for converting an internal impedance voltage signal V _Is corresponding to the measured current signal into an average value; ADC converter circuit converting the first conversion means and the effective value of the average effective value of the second average value the average conversion of (I _s) the measured current signal is converted to a voltage signal via the means and the internal impedance (V _Is) to a digital value; And A central processing unit for computing a battery equivalent circuit components from the ADC measured current signal output from the converting circuit (I _s) and the internal impedance of the voltage signal (V _Is); Measurement operation circuit of the battery equivalent circuit element component comprising a.

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