CN103217651B - A kind of evaluation method of storage battery charge state and system - Google Patents

Abstract

The present invention relates to the related technical field of storage battery parameter estimation, in particular to a method and system for estimating the state of charge of a storage battery. The first function of the variable discharge capacity, and a plurality of second functions of the discharge capacity with the discharge current as the independent variable; according to at least one first function and at least one second function to obtain the state of the measured terminal voltage and the measured discharge current Measuring an estimated value of the discharge capacity; obtaining a corresponding estimated value of the state of charge according to the estimated value of the measured discharge capacity. The invention uses the Newton interpolation method to estimate the SOC value of the storage battery, and can accurately deduce the change trend of the remaining capacity of the storage battery, so that problems can be analyzed more intuitively and phenomena can be predicted more quickly, and online measurement can be realized with high accuracy.

Description

Method and system for estimating battery state of charge

technical field

The invention relates to the technical field related to battery parameter estimation, in particular to a method and system for estimating the state of charge of a battery.

Background technique

In solar photovoltaic power generation systems and photovoltaic/wind hybrid power generation systems, battery packs are used as energy sources to store and regulate electric energy. Usually, the battery pack in the system is composed of multiple batteries connected in series and in parallel, and is often in a cycle state. During operation, due to the individual differences of the batteries, there will inevitably be the phenomenon that the lagging batteries are over-discharged and under-charged in the battery pack. Repeatedly, the backward battery will fail early, which will seriously affect the service life of the battery.

According to the requirements of relevant specifications, the single terminal voltage of each battery is not allowed to exceed ±50mV of the average single voltage of the battery. Batteries outside this range may be due to improper charging or battery failure. According to the consistency of the battery terminal voltage, initially find out the faulty battery in the battery pack. On this basis, it is of great significance to ensure the stability of the system and prolong the service life of the battery by real-time and accurate online detection of the remaining capacity or State of Charge (SOC) of the battery to avoid overcharging and overdischarging of the battery .

The technology of lead-acid battery is relatively mature, and the relevant theory and experience are relatively rich. It is currently the most widely used battery, and is widely used in solar power generation, electric vehicles and other fields. The charging and discharging of lead-acid batteries is a complex electrochemical process, and its actual capacity is also affected by many factors, so it is difficult to accurately measure the battery SOC. The current common practice is to predict the SOC of the battery according to the external characteristic parameters of the battery. Commonly used methods mainly include internal resistance method, ampere-hour measurement method, neural network method and Kalman filter method, and their specific characteristics are as follows:

The internal resistance method is mainly applicable when the SOC of the battery is lower than 40%, because when the SOC is above 40%, the internal resistance basically does not change, and only when the SOC is below 40%, the internal resistance of the battery will be very fast. raised.

The ampere-hour measurement method needs to calibrate the initial value of SOC and accurate charge and discharge efficiency in the application, as well as accurately measure the current. The current measurement is not accurate, and there will be cumulative errors in the current integration for a long time. At the same time, the fluctuation of the charging and discharging current will also affect the remaining capacity of the battery, which will lead to inaccurate SOC estimation.

The neural network method can better reflect the nonlinear characteristics of battery capacity. However, the error of this method is greatly affected by the training data and training method, and meeting the accuracy requirements usually requires a large computer resource.

The Kalman filter method can maintain good accuracy in estimation. However, the estimation accuracy of this method depends heavily on the accuracy of the battery equivalent circuit model, and the amount of calculation data is large.

It can be seen that the above methods cannot improve the flexibility of the algorithm and reduce the amount of calculation while satisfying the requirement of accurately estimating the SOC value of the battery.

Contents of the invention

Based on this, it is necessary to provide a method and system for estimating the state of charge of a battery to address the technical problems that the existing technology cannot meet the technical problems of accurately estimating the SOC value of the battery while improving the flexibility of the algorithm and reducing the amount of calculation.

A method for estimating the state of charge of a storage battery, comprising:

Acquiring a plurality of battery online state feature data, the battery online state feature data including multiple terminal voltage discrete point data values, discharge current discrete point data values, and discharge capacity discrete point data values of the battery;

According to the plurality of terminal voltage discrete point data values, discharge current discrete point data values and discharge capacity discrete point data values, a plurality of first functions of discharge capacity with terminal voltage as an independent variable are obtained by using Newton interpolation method, and a plurality of The second function of the discharge capacity with the discharge current as an independent variable;

Measure the terminal voltage of the storage battery as the measurement terminal voltage, and measure the discharge current of the storage battery as the measurement discharge current;

Obtaining an estimated value of the measured discharge capacity under the state of the measured terminal voltage and the measured discharge current according to at least one first function and at least one second function;

A corresponding estimated value of the state of charge is obtained according to the estimated value of the measured discharge capacity.

Further, the step of acquiring a plurality of battery online status feature data specifically includes:

The charging requirement determined according to the battery type of the storage battery is to charge the electric quantity of the rated capacity of the storage battery;

Discharging the storage battery at a constant current with at least three discharge rates, and discharging the storage battery to multiple states of charge in stages at each discharge rate;

measuring and saving at least three discharge current discrete point data values and at least three terminal voltage discrete point data values of the storage battery in each state of charge, and the discharge current discrete point data values and terminal voltage discrete point data values The data value of the discrete point of the discharge capacity corresponding to the value combination state.

Still further, according to the multiple terminal voltages, discharge currents, and discharge capacities, the Newton interpolation method is used to obtain a plurality of first functions of the discharge capacity with the terminal voltage as the argument, and a plurality of discharge currents as the argument The steps of the second function of the discharge capacity specifically include:

Using the Newton interpolation method to obtain multiple first functions of the discharge capacity with the terminal voltage as the independent variable, specifically including:

For all R discharge current discrete point data values I _i (i=1,2,...,R), calculate R first functions Q ₁ =f ₁ (I _i ,U):

$\begin{array}{c}{f}_1(I_i,u)=f_1\left(u_1\right)+f_1[u_1,u_2](u-u_1)+f_1[u_1,u_2,u_3](u-u_1)(u-u_2)+...\\ +f_1[u_1,u_2,...,u_t](u-u_1)...(u-u_{t-1})+f_1[u,u_1,...,u_t](u-u_1)...(u-u_t)\end{array}$ , where, t is the number of interpolation nodes, t≥3; U _j (j=1,2,…,t) is the data value of t discrete points of the terminal voltage; f ₁ [U ₁ , U ₂ ,.. .,U _j ] is the j-1 order mean difference of f ₁ on U ₁ , U ₂ ,...,U _j ; f ₁ (U _j ) is the data value I _i and terminal voltage discrete Discrete point data value Q _ij of discharge capacity corresponding to point data value U _j combination state;

Using the Newton interpolation method to obtain multiple second functions of the discharge capacity with the discharge current as the independent variable, specifically including:

For all T discrete point data values of terminal voltage U _j (j=1,2,…,T), calculate T second functions Q ₂ =f ₂ (U _j , I):

$\begin{array}{c}{f}_2(u_j,I)=f_2\left(I_1\right)+f_2[I_1,I_2](I-I_1)+f_2[I_1,I_2,I_3](I-I_1)(I-I_2)+...\\ +f_2[I_1,I_2,...,I_r](I-I_1)...(I-I_{r-1})+f_2[I_1,I_2,...,I_r](I-I_1)...(I-I_r)\end{array}$ , where r is the number of interpolation nodes, r≥3; I _i (i=1,2,...,r) is the data value of r discrete points of the discharge current; f ₂ [I ₁ ,I ₂ ,.. .,I _i ] is the i-1 order average difference of f ₂ on I ₁ , I ₂ ,...,I _i ; f ₂ (I _i ) is the data value I _i and terminal voltage discrete Discrete point data value Q _ij of discharge capacity corresponding to point data value U _j combination state.

Furthermore, the step of obtaining the estimated value of the measured discharge capacity under the state of the measured terminal voltage and the measured discharge current according to at least one first function and at least one second function specifically includes:

If the measured terminal voltage U _M is equal to one of the terminal voltage discrete point data values U _j (j=1,2,...,T), then the measured discharge current I _N is substituted into the corresponding second function Q ₂ =f ₂ ( U _j ,I), to obtain the estimated discharge capacity Q=f ₂ (UM , _{IN )} of the battery under the state of terminal voltage U _M and discharge current I _N ;

If the measured discharge current I _N is equal to one of the discharge current discrete point data values I _i (i=1,2,...,R), then the measured terminal voltage U _M is substituted into the corresponding first function Q ₁ =f ₁ ( I _i , U), to obtain the estimated discharge capacity Q=f ₁ ( _IN , U _M ) of the battery under the state of terminal voltage U _M and discharge current I _N ;

If the measured terminal voltage U _M is not equal to any one of the terminal voltage discrete point data values U _j and the measured discharge current I _N is not equal to any one of the discharge current discrete point data values I _i , substitute U _M into the R The first function Q ₁ =f ₁ (I _i , U) to obtain a set of R discrete data, the discrete data is discharge current discrete point data value I _i , R discharges under the state of measuring terminal voltage U _M Estimated capacity value.

Newton interpolation is performed on the _R pieces of discrete data to obtain a second function Q ₂ =f ₂ ( _UM ,I) of the discharge capacity with the discharge current I as an independent variable when U=UM.

Substituting I ₌ IN into the second function Q ₂ =f ₂ (U _M ,I) to obtain the estimated discharge capacity Q ₌ f ₂ ( _{U M} , I _N ).

Further, it also includes: using a storage battery state detection circuit to detect the terminal voltage difference of the battery, and find out the faulty battery in the storage battery.

A system for estimating the state of charge of a storage battery, comprising:

A feature data acquisition module, configured to acquire a plurality of battery online state feature data, the battery online state feature data including multiple terminal voltage discrete point data values, discharge current discrete point data values and discharge capacity discrete point data values of the battery point data value;

The function acquisition module is used to obtain a plurality of terminal voltage discrete point data values, discharge current discrete point data values, and discharge capacity discrete point data values by using the Newton interpolation method to obtain a plurality of terminal voltage as independent variables. a function, and a plurality of second functions of the discharge capacity with the discharge current as an independent variable;

The measurement terminal voltage and measurement discharge current acquisition module is used to measure the terminal voltage of the storage battery as the measurement terminal voltage, and measure the discharge current of the storage battery as the measurement discharge current;

An estimated value acquisition module of the measured discharge capacity, configured to obtain an estimated value of the measured discharge capacity under the state of the measured terminal voltage and the measured discharge current according to at least one first function and at least one second function;

The estimated state of charge acquisition module is configured to obtain a corresponding estimated value of the state of charge according to the estimated value of the measured discharge capacity.

Further, the feature quantity data acquisition module is specifically used for:

The charging requirement determined according to the battery type of the storage battery is to charge the electric quantity of the rated capacity of the storage battery;

Discharging the storage battery at a constant current with at least three discharge rates, and discharging the storage battery to multiple states of charge in stages at each discharge rate;

measuring and saving at least three discharge current discrete point data values and at least three terminal voltage discrete point data values of the storage battery in each state of charge, and the discharge current discrete point data values and terminal voltage discrete point data values The data value of the discrete point of the discharge capacity corresponding to the value combination state.

Still further, the function acquisition module is specifically used for:

Using the Newton interpolation method to obtain multiple first functions of the discharge capacity with the terminal voltage as the independent variable, specifically including:

For all R discharge current discrete point data values I _i (i=1,2,...,R), calculate R first functions Q ₁ =f ₁ (I _i ,U):

$\begin{array}{c}{f}_1(I_i,u)=f_1\left(u_1\right)+f_1[u_1,u_2](u-u_1)+f_1[u_1,u_2,u_3](u-u_1)(u-u_2)+...\\ +f_1[u_1,u_2,...,u_t](u-u_1)...(u-u_{t-1})+f_1[u,u_1,...,u_t](u-u_1)...(u-u_t)\end{array}$ , where, t is the number of interpolation nodes, t≥3; U _j (j=1,2,…,t) is the data value of t discrete points of the terminal voltage; f ₁ [U ₁ , U ₂ ,.. .,U _j ] is the j-1 order mean difference of f ₁ on U ₁ , U ₂ ,...,U _j ; f ₁ (U _j ) is the data value I _i and terminal voltage discrete Discrete point data value Q _ij of discharge capacity corresponding to point data value U _j combination state;

Using the Newton interpolation method to obtain multiple second functions of the discharge capacity with the discharge current as the independent variable, specifically including:

For all T discrete point data values of terminal voltage U _j (j=1,2,…,T), calculate T second functions Q ₂ =f ₂ (U _j , I):

$\begin{array}{c}{f}_2(u_j,I)=f_2\left(I_1\right)+f_2[I_1,I_2](I-I_1)+f_2[I_1,I_2,I_3](I-I_1)(I-I_2)+...\\ +f_2[I_1,I_2,...,I_r](I-I_1)...(I-I_{r-1})+f_2[I_1,I_2,...,I_r](I-I_1)...(I-I_r)\end{array}$ , where r is the number of interpolation nodes, r≥3; I _i (i=1,2,...,r) is the data value of r discrete points of the discharge current; f ₂ [I ₁ ,I ₂ ,.. .,I _i ] is the i-1 order average difference of f ₂ on I ₁ , I ₂ ,...,I _i ; f ₂ (I _i ) is the data value I _i and terminal voltage discrete Discrete point data value Q _ij of discharge capacity corresponding to point data value U _j combination state.

Furthermore, the module for obtaining an estimated value of the measured discharge capacity is specifically used for:

If the measured terminal voltage U _M is equal to one of the terminal voltage discrete point data values U _j (j=1,2,...,T), then the measured discharge current I _N is substituted into the corresponding second function Q ₂ =f ₂ ( U _j ,I), to obtain the estimated discharge capacity Q=f ₂ (UM , _{IN )} of the battery under the state of terminal voltage U _M and discharge current I _N ;

If the measured discharge current I _N is equal to one of the discharge current discrete point data values I _i (i=1,2,...,R), then the measured terminal voltage U _M is substituted into the corresponding first function Q ₁ =f ₁ ( I _i , U), to obtain the estimated discharge capacity Q=f ₁ ( _IN , U _M ) of the battery under the state of terminal voltage U _M and discharge current I _N ;

If the measured terminal voltage U _M is not equal to any one of the terminal voltage discrete point data values U _j and the measured discharge current I _N is not equal to any one of the discharge current discrete point data values I _i , substitute U _M into the R The first function Q ₁ =f ₁ (I _i , U) to obtain a set of R discrete data, the discrete data is discharge current discrete point data value I _i , R discharges under the state of measuring terminal voltage U _M Estimated capacity value.

Newton interpolation is performed on the _R pieces of discrete data to obtain a second function Q ₂ =f ₂ ( _UM ,I) of the discharge capacity with the discharge current I as an independent variable when U=UM.

Substituting I ₌ IN into the second function Q ₂ =f ₂ (U _M ,I) to obtain the estimated discharge capacity Q ₌ f ₂ ( _{U M} , I _N ).

Further, it also includes: a faulty battery finding module, which is used to detect the terminal voltage difference of the battery by using the battery state detection circuit, and find out the faulty battery in the battery.

The invention uses the Newton interpolation method to estimate the SOC value of the storage battery, and can accurately deduce the change trend of the remaining capacity of the storage battery, so that problems can be analyzed more intuitively and phenomena can be predicted more quickly, and online measurement can be realized with high accuracy. This method can select different numbers of interpolation nodes according to engineering precision requirements, has strong recursion, and its function composition is regular, so it has small calculation amount and good flexibility, and is easy to realize by computer programming.

At the same time, without affecting the normal operation of the battery power supply system, by accurately measuring the terminal voltage values of the battery pack and the single battery, the uniformity of the terminal voltage of the entire battery pack is tested. Initially find out the faulty batteries in the battery pack, maintain the safety of the entire battery pack, and improve the cycle efficiency and life of the entire battery pack.

Description of drawings

Fig. 1 is the working flow chart of the estimation method of a kind of storage battery state of charge of the present invention;

Fig. 2 is a structural block diagram of an estimation system of a storage battery state of charge according to the present invention;

Fig. 3 is a battery state detection circuit diagram of an example of the present invention;

FIG. 4 is a flowchart of an SOC estimation method in an example of the present invention.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

As shown in FIG. 1 , it is a working flow chart of a method for estimating the battery state of charge of the present invention.

A method for estimating the state of charge of a storage battery, used for estimating the state of charge of the storage battery under a preset measurement terminal voltage and measurement discharge current state, comprising:

Step S101, acquiring a plurality of battery online state feature data, the battery online state feature data including multiple terminal voltage discrete point data values, discharge current discrete point data values and discharge capacity discrete point data values of the battery;

Step S102, according to the plurality of terminal voltage discrete point data values, discharge current discrete point data values, and discharge capacity discrete point data values, using the Newton interpolation method to obtain a plurality of first functions of discharge capacity with terminal voltage as an argument, and a plurality of second functions of the discharge capacity with the discharge current as an independent variable;

Step S103, measuring the terminal voltage of the storage battery as the measurement terminal voltage, and measuring the discharge current of the storage battery as the measurement discharge current;

Step S104, according to at least one first function and at least one second function, obtain the estimated value of the measured discharge capacity under the state of the measured terminal voltage and the measured discharge current;

Step S105, obtaining a corresponding estimated value of the state of charge according to the estimated value of the measured discharge capacity.

In one of the embodiments, the step S101 specifically includes:

The charging requirement determined according to the battery type of the storage battery is to charge the electric quantity of the rated capacity of the storage battery;

Discharging the storage battery at a constant current with at least three discharge rates, and discharging the storage battery to multiple states of charge in stages at each discharge rate;

measuring and saving at least three discharge current discrete point data values and at least three terminal voltage discrete point data values of the storage battery in each state of charge, and the discharge current discrete point data values and terminal voltage discrete point data values The data value of the discrete point of the discharge capacity corresponding to the value combination state.

In one of the embodiments, the step S102 specifically includes:

Using the Newton interpolation method to obtain multiple first functions of the discharge capacity with the terminal voltage as the independent variable, specifically including:

For all R discharge current discrete point data values I _i (i=1,2,...,R), calculate R first functions Q ₁ =f ₁ (I _i ,U):

$\begin{array}{c}{f}_1(I_i,u)=f_1\left(u_1\right)+f_1[u_1,u_2](u-u_1)+f_1[u_1,u_2,u_3](u-u_1)(u-u_2)+...\\ +f_1[u_1,u_2,...,u_t](u-u_1)...(u-u_{t-1})+f_1[u,u_1,...,u_t](u-u_1)...(u-u_t)\end{array}$ , where, t is the number of interpolation nodes, t≥3; U _j (j=1,2,…,t) is the data value of t discrete points of the terminal voltage; f ₁ [U ₁ , U ₂ ,.. .,U _j ] is the j-1 order mean difference of f ₁ on U ₁ , U ₂ ,...,U _j ; f ₁ (U _j ) is the data value I _i and terminal voltage discrete Discrete point data value Q _ij of discharge capacity corresponding to point data value U _j combination state;

Using the Newton interpolation method to obtain multiple second functions of the discharge capacity with the discharge current as the independent variable, specifically including:

For all T discrete point data values of terminal voltage U _j (j=1,2,…,T), calculate T second functions Q ₂ =f ₂ (U _j , I):

$\begin{array}{c}{f}_2(u_j,I)=f_2\left(I_1\right)+f_2[I_1,I_2](I-I_1)+f_2[I_1,I_2,I_3](I-I_1)(I-I_2)+...\\ +f_2[I_1,I_2,...,I_r](I-I_1)...(I-I_{r-1})+f_2[I_1,I_2,...,I_r](I-I_1)...(I-I_r)\end{array}$ , where r is the number of interpolation nodes, r≥3; I _i (i=1,2,...,r) is the data value of r discrete points of the discharge current; f ₂ [I ₁ ,I ₂ ,.. .,I _i ] is the i-1 order average difference of f ₂ on I ₁ , I ₂ ,...,I _i ; f ₂ (I _i ) is the data value I _i and terminal voltage discrete Discrete point data value Q _ij of discharge capacity corresponding to point data value U _j combination state.

In one of the embodiments, the step S104 specifically includes:

If the measured terminal voltage U _M is equal to one of the terminal voltage discrete point data values U _j (j=1,2,...,T), then the measured discharge current I _N is substituted into the corresponding second function Q ₂ =f ₂ ( U _j ,I), to obtain the estimated discharge capacity Q=f ₂ (UM , _{IN )} of the battery under the state of terminal voltage U _M and discharge current I _N ;

If the measured discharge current I _N is equal to one of the discharge current discrete point data values I _i (i=1,2,...,R), then the measured terminal voltage U _M is substituted into the corresponding first function Q ₁ =f ₁ ( I _i , U), to obtain the estimated discharge capacity Q=f ₁ ( _IN , U _M ) of the battery under the state of terminal voltage U _M and discharge current I _N ;

If the measured terminal voltage U _M is not equal to any one of the terminal voltage discrete point data values U _j and the measured discharge current I _N is not equal to any one of the discharge current discrete point data values I _i , substitute U _M into the R The first function Q ₁ =f ₁ (I _i , U) to obtain a set of R discrete data, the discrete data is discharge current discrete point data value I _i , R discharges under the state of measuring terminal voltage U _M Estimated capacity value.

Newton interpolation is performed on the _R pieces of discrete data to obtain a second function Q ₂ =f ₂ ( _UM ,I) of the discharge capacity with the discharge current I as an independent variable when U=UM.

Substituting I ₌ IN into the second function Q ₂ =f ₂ (U _M ,I) to obtain the estimated discharge capacity Q ₌ f ₂ ( _{U M} , I _N ).

In one of the embodiments, the present invention may further include: using a storage battery state detection circuit to detect the terminal voltage difference of the battery, and find out the faulty battery in the storage battery. This embodiment adopts the battery state detection circuit, which can detect the uniformity of the battery terminal voltage by accurately measuring the terminal voltage values of the battery pack and the single battery without affecting the normal operation of the battery power supply system. Initially find out the faulty batteries in the battery pack, maintain the safety of the entire battery pack, and improve the cycle efficiency and life of the entire battery pack.

As shown in FIG. 2 , it is a structural block diagram of a battery state-of-charge estimation system of the present invention.

A system for estimating the state of charge of a storage battery, used to estimate the state of charge of the storage battery under the preset measurement terminal voltage and measurement discharge current state, including:

A feature data acquisition module 210, configured to acquire a plurality of battery online state feature data, the battery online state feature data including multiple terminal voltage discrete point data values, discharge current discrete point data values and discharge capacity of the battery Discrete point data values;

The function acquisition module 220 is used to obtain a plurality of discharge capacity values with the terminal voltage as an argument according to the multiple terminal voltage discrete point data values, discharge current discrete point data values, and discharge capacity discrete point data values by using Newton interpolation method a first function, and a plurality of second functions of discharge capacity with discharge current as an independent variable;

The measurement terminal voltage and measurement discharge current acquisition module 230 is used to measure the terminal voltage of the storage battery as the measurement terminal voltage, and measure the discharge current of the storage battery as the measurement discharge current;

A measured discharge capacity estimation value acquisition module 240, configured to obtain a measured discharge capacity estimated value under the state of the measured terminal voltage and the measured discharge current according to at least one first function and at least one second function;

The state of charge estimated value obtaining module 250 is configured to obtain a corresponding state of charge estimated value according to the measured discharge capacity estimated value.

In one of the embodiments, the feature quantity data acquisition module 210 is specifically used for:

The charging requirement determined according to the battery type of the storage battery is to charge the electric quantity of the rated capacity of the storage battery;

Discharging the storage battery at a constant current with at least three discharge rates, and discharging the storage battery to multiple states of charge in stages at each discharge rate;

measuring and saving at least three discharge current discrete point data values and at least three terminal voltage discrete point data values of the storage battery in each state of charge, and the discharge current discrete point data values and terminal voltage discrete point data values The data value of the discrete point of the discharge capacity corresponding to the value combination state.

In one of the embodiments, the function obtaining module 220 is specifically used for:

Using the Newton interpolation method to obtain multiple first functions of the discharge capacity with the terminal voltage as the independent variable, specifically including:

For all R discharge current discrete point data values I _i (i=1,2,...,R), calculate R first functions Q ₁ =f ₁ (I _i ,U):

$\begin{array}{c}{f}_1(I_i,u)=f_1\left(u_1\right)+f_1[u_1,u_2](u-u_1)+f_1[u_1,u_2,u_3](u-u_1)(u-u_2)+...\\ +f_1[u_1,u_2,...,u_t](u-u_1)...(u-u_{t-1})+f_1[u,u_1,...,u_t](u-u_1)...(u-u_t)\end{array}$ , where, t is the number of interpolation nodes, t≥3; U _j (j=1,2,…,t) is the data value of t discrete points of the terminal voltage; f ₁ [U ₁ , U ₂ ,.. .,U _j ] is the j-1 order mean difference of f ₁ on U ₁ , U ₂ ,...,U _j ; f ₁ (U _j ) is the data value I _i and terminal voltage discrete Discrete point data value Q _ij of discharge capacity corresponding to point data value U _j combination state;

Using the Newton interpolation method to obtain multiple second functions of the discharge capacity with the discharge current as the independent variable, specifically including:

For all T discrete point data values of terminal voltage U _j (j=1,2,…,T), calculate T second functions Q ₂ =f ₂ (U _j , I):

$\begin{array}{c}{f}_2(u_j,I)=f_2\left(I_1\right)+f_2[I_1,I_2](I-I_1)+f_2[I_1,I_2,I_3](I-I_1)(I-I_2)+...\\ +f_2[I_1,I_2,...,I_r](I-I_1)...(I-I_{r-1})+f_2[I_1,I_2,...,I_r](I-I_1)...(I-I_r)\end{array}$ , where r is the number of interpolation nodes, r≥3; I _i (i=1,2,...,r) is the data value of r discrete points of the discharge current; f ₂ [I ₁ ,I ₂ ,.. .,I _i ] is the i-1 order average difference of f ₂ on I ₁ , I ₂ ,...,I _i ; f ₂ (I _i ) is the data value I _i and terminal voltage discrete Discrete point data value Q _ij of discharge capacity corresponding to point data value U _j combination state.

In one of the embodiments, the measured discharge capacity estimation value acquisition module 240 is specifically used for:

If the measured terminal voltage U _M is equal to one of the terminal voltage discrete point data values U _j (j=1,2,...,T), then the measured discharge current I _N is substituted into the corresponding second function Q ₂ =f ₂ ( U _j ,I), to obtain the estimated discharge capacity Q=f ₂ (UM , _{IN )} of the battery under the state of terminal voltage U _M and discharge current I _N ;

If the measured discharge current I _N is equal to one of the discharge current discrete point data values I _i (i=1,2,...,R), then the measured terminal voltage U _M is substituted into the corresponding first function Q ₁ =f ₁ ( I _i , U), to obtain the estimated discharge capacity Q=f ₁ ( _IN , U _M ) of the battery under the state of terminal voltage U _M and discharge current I _N ;

If the measured terminal voltage U _M is not equal to any one of the terminal voltage discrete point data values U _j and the measured discharge current I _N is not equal to any one of the discharge current discrete point data values I _i , substitute U _M into the R The first function Q ₁ =f ₁ (I _i , U) to obtain a set of R discrete data, the discrete data is discharge current discrete point data value I _i , R discharges under the state of measuring terminal voltage U _M Estimated capacity value.

Newton interpolation is performed on the _R pieces of discrete data to obtain a second function Q ₂ =f ₂ ( _UM ,I) of the discharge capacity with the discharge current I as an independent variable when U=UM.

Substituting I ₌ IN into the second function Q ₂ =f ₂ (U _M ,I) to obtain the estimated discharge capacity Q ₌ f ₂ ( _{U M} , I _N ).

In one of the embodiments, it further includes: a faulty battery finding module, configured to use a storage battery state detection circuit to detect the voltage difference between the terminals of the battery, and find out the faulty battery in the storage battery.

As an example, the battery state detection circuit diagram, as shown in Figure 3, is mainly used to obtain the battery state detection circuit of the online state characteristic data of the battery. Terminal voltage difference, so as to preliminarily find out whether there is a faulty battery. Among them, R ₁ is a DC load box selected according to the characteristics of the system load, which has a constant current discharge function and can detect discharge time and capacity online; S ₁ , S ₂ , and S ₃ are circuit breakers.

During normal operation, S ₂ is closed, S ₁ and S ₃ are both disconnected, and battery 1 is in a normal online operation state. When detecting terminal voltage, first close S ₁ and then disconnect S ₂ . When the floating charging voltage of the charger 2 is slightly higher than the terminal voltage of the battery 1, the diode 3 will not reverse breakdown, which is equivalent to the data measured by the battery 1 in an offline state. The measured results can truly reflect the characteristics of the terminal voltage of the single battery 1 and the whole battery pack.

When testing, first close S ₁ , disconnect S ₂ , and close S ₃ for a short time, then the battery 1 starts to discharge at a constant current, and use the capacity measured by the DC load box R ₁ as the value of the discrete point function. The data table of battery terminal voltage U and discharge current I and its corresponding discharge capacity Q feature data, select 6 data values of discharge current discrete points: I _i (i=1,2,...,6), terminal voltage discrete points There are 6 data values: U _j (j=1,2,…,6). Record the data value Q _ij of discrete points of discharge capacity measured under the state of discrete point data values of discharge current and terminal voltage values for each group, as shown in the characteristic quantity data table shown in Table 1:

What needs to be emphasized here is: during the detection process, when a power failure occurs or the charger 2 fails to output the DC voltage, the DC bus voltage will drop. When the DC bus voltage is lower than the battery 1 terminal voltage, the battery 1 will supply power to the DC bus through S ₁ and diode 3, ensuring the continuity of the power supply of the system. At this time, close S ₂ , disconnect S ₁ and S ₃ , and restore the normal wiring operation of the battery.

The flow chart of the SOC value estimation method in this example is shown in Figure 4:

In step S401, the terminal voltage discrete point data value U _j , the discharge current discrete point data value I _i , and the discharge capacity discrete point data value Q _ij are obtained. The specific data are obtained from the feature quantity data table shown in Table 1.

Step S402, when I=I _i (i=1,2,...,6), use the Newton interpolation method to construct 6 functions Q′=N(I _i ,U) with the terminal voltage U as the independent variable, so that Infinitely approximates the corresponding original function Q ₁ =f ₁ (I _i ,U). When I=I _i , as shown in Table 1, when the independent variable U=U _j (j=1,2,…,6), the corresponding function value f ₁ (U ₁ ),…, f ₁ ( U ₆ ) are Q _i1 , . . . , Q _i6 , respectively. Construct a 5th degree interpolation polynomial N(I _i ,U) to infinitely approximate the original function Q ₁ =f ₁ (I _i ,U).

$\begin{array}{c}{f}_1(I_i,u)=f_1\left(u_1\right)+f_1[u_1,u_2](u-u_1)+f_1[u_1,u_2,u_3](u-u_1)(u-u_2)+...\\ +f_1[u_1,u_2,...,u_6](u-u_1)...(u-u_5)+f_1[u,u_1,...,u_6](u-u_1)...(u-u_6)\end{array}$ , let the first 6 terms of the polynomial be recorded as N(I _i ,U), and the last term be recorded as R(I _i ,U). Among them, f ₁ [U ₁ , U ₂ ,...,U _j ] is the j-1 order mean difference of f ₁ on U ₁ , U ₂ ,...,U _j , and f ₁ (U _j ) is The corresponding discharge capacity discrete point data value Q _ij under the combined state of discharge current discrete point data value I _i and terminal voltage discrete point data value U _j ;

R(I _i ,U) is the remainder. The smaller the value of the remainder, the closer Q′=N(I _i ,U) is to the original function Q ₁ =f(I _i ,U). The size of the residual value is related to the selection of the interpolation node of the Newton interpolation method. Select the node whose distance is closer to the U value to be inserted as the interpolation interval, and the value of the remainder is smaller. In addition, the more nodes are selected, the smaller the residual value is usually. However, the analysis of the differential error propagation-the analysis of the stability problem shows that different numbers of nodes should be selected according to the engineering accuracy, and blindly pursue high The step quotient is not desirable.

Step S403, when U=U _j (j=1,2,...,6), in the same way, 6 functions Q′′=N(U _j ,I) with the discharge current I as the independent variable can be constructed, so that Infinite approximation corresponds to the original function Q ₂ =f ₂ (U _j ,I), that is:

$\begin{array}{c}{f}_2(u_j,I)=f_2\left(I_1\right)+f_2[I_1,I_2](I-I_1)+f_2[I_1,I_2,I_3](I-I_1)(I-I_2)+...\\ +f_2[I_1,I_2,...,I_6](I-I_1)...(I-I_5)+f_2[I_1,I_2,...,I_6](I-I_1)...(I-I_6)\end{array}$ , where, f ₂ [I ₁ ,I ₂ ,...,I _i ] is the i-1 order mean difference of f ₂ on I ₁ ,I ₂ ,...,I _i , f ₂ (I _i ) is the corresponding discharge capacity discrete point data value Q _ij in the combined state of the discharge current discrete point data value I _i and the terminal voltage discrete point data value U _j .

In step S404, it is detected that the battery terminal voltage is U _M and the discharge current is I _N .

Step S405, judging whether U _M is equal to U _j , or whether _IN is equal to I _i . If the judgment result is true, go to step S406; otherwise, go to step S407.

Step S406, if U _M is equal to U _j , then substitute I ₌ IN into Q ₂ =f ₂ (U _j ,I), and calculate the corresponding estimated value of discharge capacity Q=f ₂ (U _M ,I _N ); if If I _N is equal to I _i , then U=U _M is substituted into Q ₁ =f ₁ (I _i , U), and the corresponding estimated value of discharge capacity Q=f ₁ (I _N , U _M ) is calculated, and step S412 is executed.

In step S407, input U= _UM , and execute step S408.

Step S408, substituting the function expression Q ₁ =f ₁ (I _i , U) to obtain the corresponding discharge capacity Q _1M , . . . , Q _6M when I=I _i (i=1,2,...,6).

Step S409, perform interpolation on the discrete data obtained in step S408, and then execute step S410.

In step _S410 , when U=UM, the discharge capacity function Q ₂ =f ₂ ( _UM , I) with the discharge current I as an argument is obtained, and then enters step S411.

Step S411, substituting I ₌ IN into Q ₂ =f ₂ (U _M , I), and calculating the corresponding estimated value of discharge capacity Q=f ₂ (U _M , I _N ), and performing step S412;

Step S412, outputting the discharge capacity estimated value Q, and finally entering step S413;

Step S413, output the calculated SOC value, the depth of discharge (Depth of Discharge, DOD) of the battery, which is the percentage of the battery discharge capacity to its rated capacity, and the state of charge SOC=1-DOD, to obtain the battery at the measuring end Voltage U _M , measure the SOC value under the discharge current _IN state.

The telecommunications power supply maintenance regulations stipulate that: the battery should be subjected to a check discharge test with the actual load every year, a capacity test every 3 years, and a year after 6 years of use. According to the data measured during battery maintenance, according to the battery SOC estimation method of the present invention, the previous curve function can be corrected to overcome the problem that the error of the SOC estimation function becomes larger due to factors such as battery aging.

The above-mentioned embodiments only express several implementation modes of the present invention, and the description thereof is relatively specific and detailed, but should not be construed as limiting the patent scope of the present invention. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (10)

1. an evaluation method for storage battery charge state, is characterized in that, comprising:

Obtain multiple presence characteristic quantity data of accumulator, multiple presence characteristic quantity data of described accumulator comprise multiple terminal voltage discrete points data values of described accumulator, discharge current discrete points data value and discharge capacity discrete points data value;

According to described multiple terminal voltage discrete points data value, discharge current discrete points data value and discharge capacity discrete points data value, Newton interpolating method is adopted to obtain multiple with first function of the terminal voltage U discharge capacity Q that is independent variable, and multiple with second function of the discharge current I discharge capacity Q that is independent variable;

Measurement obtains the terminal voltage U of described accumulator as measuring junction voltage U _m, measurement obtains the discharge current I of described accumulator as measurement discharge current I _n;

Obtain in measuring junction voltage U according at least one first function and at least one the second function _mwith measurement discharge current I _nmeasurement discharge capacity estimated value under state;

The estimated value of corresponding state-of-charge is obtained according to described measurement discharge capacity estimated value.

2. the evaluation method of storage battery charge state according to claim 1, is characterized in that, the step of multiple presence characteristic quantity data of described acquisition accumulator, specifically comprises:

The charging requirement determined according to the battery types of described accumulator is filled with the electricity of described battery rating;

By described accumulator with the discharge-rate constant-current discharge of at least three kinds, under often kind of discharge-rate, make described battery discharging to multiple state-of-charges stage by stage;

Measure and preserve at least three the discharge current discrete points data values of described accumulator under each state-of-charge and at least three terminal voltage discrete points data values, and discharge capacity discrete points data value corresponding under described discharge current discrete points data value and terminal voltage discrete points data value assembled state.

3. the evaluation method of storage battery charge state according to claim 1, it is characterized in that, according to described multiple terminal voltage discrete points data value, discharge current discrete points data value and discharge capacity discrete points data value, Newton interpolating method is adopted to obtain multiple with first function of the terminal voltage U discharge capacity Q that is independent variable, and multiple with the step of second function of the discharge current I discharge capacity Q that is independent variable, specifically comprise:

Adopt Newton interpolating method to obtain multiple with first function of the terminal voltage U discharge capacity Q that is independent variable, specifically comprise:

To all R discharge current discrete points data value I _i(i=1,2 ..., R), calculate with R the first function Q of the terminal voltage U discharge capacity Q that is independent variable ₁=f ₁(I _i, U):

wherein, t is interpolation knot number, t>=3; U _j(j=1,2 ..., t) be t described terminal voltage discrete points data value; f ₁[U ₁, U ₂..., U _j] be f ₁at U ₁, U ₂..., U _jon j-1 rank inequality; f ₁(U _j) be at discharge current discrete points data value I _iwith terminal voltage discrete points data value U _jdischarge capacity discrete points data value Q corresponding under assembled state _ij;

Adopt Newton interpolating method to obtain multiple with second function of the discharge current I discharge capacity Q that is independent variable, specifically comprise:

To all T terminal voltage discrete points data value U _j(j=1,2 ..., T), calculate with T the second function Q of the discharge current I discharge capacity Q that is independent variable ₂=f ₂(U _j, I):

wherein, r is interpolation knot number, r>=3; I _i(i=1,2 ..., r) be r described discharge current discrete points data value; f ₂[I ₁, I ₂..., I _i] be f ₂at I ₁, I ₂..., I _ion i-1 rank inequality; f ₂(I _i) be at discharge current discrete points data value I _iwith terminal voltage discrete points data value U _jdischarge capacity discrete points data value Q corresponding under assembled state _ij.

4. the evaluation method of storage battery charge state according to claim 3, is characterized in that, described according at least one first function and at least one second function obtain in measuring junction voltage U _mwith measurement discharge current I _nthe step of the measurement discharge capacity estimated value under state, specifically comprises:

If described measuring junction voltage U _mequal one of them terminal voltage discrete points data value U _j(j=1,2 ..., T), then will measure discharge current I _nsubstitute into corresponding second function Q ₂=f ₂(U _j, I), obtain accumulator in measuring junction voltage U _m, measure discharge current I _nmeasurement discharge capacity estimated value Q=f under state ₂(U _m, I _n);

If described measurement discharge current I _nequal one of them discharge current discrete points data value I _i(i=1,2 ..., R), then by measuring junction voltage U _msubstitute into corresponding first function Q ₁=f ₁(I _i, U), obtain accumulator in measuring junction voltage U _m, measure discharge current I _nmeasurement discharge capacity estimated value Q=f under state ₁(I _n, U _m);

If described measuring junction voltage U _mbe not equal to the terminal voltage discrete points data value U of any one _jand measure discharge current I _nbe not equal to the discharge current discrete points data value I of any one _itime, by measuring junction voltage U _msubstitute into the first function Q described in R ₁=f ₁(I _i, U), try to achieve one group of R discrete data, described discrete data is discharge current discrete points data value I _i, measuring junction voltage U _mr discharge capacity value estimated value under state, carries out Newton interpolation to a described R discrete data, draws U=U _mtime, the second function Q of the discharge capacity that is independent variable with discharge current I ₂=f ₂(U _m, I), by I=I _nthe second function Q described in substitution ₂=f ₂(U _m, I), obtain accumulator in measuring junction voltage U _m, measure discharge current I _nmeasurement discharge capacity estimated value Q=f under state ₂(U _m, I _n).

5. the evaluation method of storage battery charge state according to claim 1, is characterized in that, also comprises: adopt battery condition testing circuit, detects the terminal voltage pressure reduction of battery, finds out the fail battery in described accumulator.

6. an estimating system for storage battery charge state, is characterized in that, comprising:

Characteristic quantity data acquisition module, for obtaining multiple presence characteristic quantity data of accumulator, multiple presence characteristic quantity data of described accumulator comprise multiple terminal voltage discrete points data values of described accumulator, discharge current discrete points data value and discharge capacity discrete points data value;

Function acquisition module, for according to described multiple terminal voltage discrete points data value, discharge current discrete points data value and discharge capacity discrete points data value, Newton interpolating method is adopted to obtain multiple with first function of the terminal voltage U discharge capacity Q that is independent variable, and multiple with second function of the discharge current I discharge capacity Q that is independent variable;

Measuring junction voltage and measure discharge current acquisition module, for measure obtain described accumulator terminal voltage U as measuring junction voltage U _m, measurement obtains the discharge current I of described accumulator as measurement discharge current I _n;

Measure discharge capacity estimated value acquisition module, for obtaining in measuring junction voltage U according at least one first function and at least one the second function _mwith measurement discharge current I _nmeasurement discharge capacity estimated value under state;

State-of-charge estimated value acquisition module, for obtaining the estimated value of corresponding state-of-charge according to described measurement discharge capacity estimated value.

7. the estimating system of storage battery charge state according to claim 6, is characterized in that, described characteristic quantity data acquisition module, specifically for:

The charging requirement determined according to the battery types of described accumulator is filled with the electricity of described battery rating;

By described accumulator with the discharge-rate constant-current discharge of at least three kinds, under often kind of discharge-rate, make described battery discharging to multiple state-of-charges stage by stage;

Measure and preserve at least three the discharge current discrete points data values of described accumulator under each state-of-charge and at least three terminal voltage discrete points data values, and discharge capacity discrete points data value corresponding under described discharge current discrete points data value and terminal voltage discrete points data value assembled state.

8. the estimating system of storage battery charge state according to claim 6, is characterized in that, described function acquisition module, specifically for:

Adopt Newton interpolating method to obtain multiple with first function of the terminal voltage U discharge capacity Q that is independent variable, specifically comprise:

To all R discharge current discrete points data value I _i(i=1,2 ..., R), calculate with R the first function Q of the terminal voltage U discharge capacity Q that is independent variable ₁=f ₁(I _i, U):

wherein, t is interpolation knot number, t>=3; U _j(j=1,2 ..., t) be t described terminal voltage discrete points data value; f ₁[U ₁, U ₂..., U _j] be f ₁at U ₁, U ₂..., U _jon j-1 rank inequality; f ₁(U _j) be at discharge current discrete points data value I _iwith terminal voltage discrete points data value U _jdischarge capacity discrete points data value Q corresponding under assembled state _ij;

Adopting Newton interpolating method to obtain multiple take discharge current as the second function of the discharge capacity of independent variable, specifically comprises:

To all T terminal voltage discrete points data value U _j(j=1,2 ..., T), calculate with T the second function Q of the discharge current I discharge capacity Q that is independent variable ₂=f ₂(U _j, I):

wherein, r is interpolation knot number, r>=3; I _i(i=1,2 ..., r) be r described discharge current discrete points data value; f ₂[I ₁, I ₂..., I _i] be f ₂at I ₁, I ₂..., I _ion i-1 rank inequality; f ₂(I _i) be at discharge current discrete points data value I _iwith terminal voltage discrete points data value U _jdischarge capacity discrete points data value Q corresponding under assembled state _ij.

9. the estimating system of storage battery charge state according to claim 6, is characterized in that, described measurement discharge capacity estimated value acquisition module, specifically for:

If described measuring junction voltage U _mequal one of them terminal voltage discrete points data value U _j(j=1,2 ..., T), then will measure discharge current I _nsubstitute into corresponding second function Q ₂=f ₂(U _j, I), obtain accumulator in measuring junction voltage U _m, measure discharge current I _nmeasurement discharge capacity estimated value Q=f under state ₂(U _m, I _n);

If described measurement discharge current I _nequal one of them discharge current discrete points data value I _i(i=1,2 ..., R), then by measuring junction voltage U _msubstitute into corresponding first function Q ₁=f ₁(I _i, U), obtain accumulator in measuring junction voltage U _m, measure discharge current I _nmeasurement discharge capacity estimated value Q=f under state ₁(I _n, U _m);

If described measuring junction voltage U _mbe not equal to the terminal voltage discrete points data value U of any one _jand measure discharge current I _nbe not equal to the discharge current discrete points data value I of any one _itime, by measuring junction voltage U _msubstitute into the first function Q described in R ₁=f ₁(I _i, U), try to achieve one group of R discrete data, described discrete data is discharge current discrete points data value I _i, measuring junction voltage U _mr discharge capacity value estimated value under state, carries out Newton interpolation to a described R discrete data, draws U=U _mtime, the second function Q of the discharge capacity that is independent variable with discharge current I ₂=f ₂(U _m, I), by I=I _nthe second function Q described in substitution ₂=f ₂(U _m, I), obtain accumulator in measuring junction voltage U _m, measure discharge current I _nmeasurement discharge capacity estimated value Q=f under state ₂(U _m, I _n).

10. the estimating system of storage battery charge state according to claim 6, it is characterized in that, also comprise: fail battery searches module, for adopting battery condition testing circuit, detect the terminal voltage pressure reduction of battery, find out the fail battery in described accumulator.