CN102221678A - On-line life calculation method for battery system - Google Patents

Abstract

The invention provides an on-line life calculation method for a battery system. The on-line life calculation method for the battery system provided by the invention comprises the following three steps: inputting the total energy of charging and discharging of the battery system during the entire life process; calculating the total energy of the finished charging and discharging of the batter system at the moment; and utilizing the two energies to obtain an on-line life of the battery system. Compared with the existing calculation method, the on-line life calculation method for the battery system provided by the invention has the following two advantages: few input parameters are needed for calculating the on-line life and the parameters can be collected by a simple device, namely, the battery system can be carried out the on-line life calculation simply by calculating the total energy of charging and discharging of the battery system; and meanwhile, the calculation process is relatively simple and can be realized without the complicated software and hardware devices.

Description

A battery system online life calculation method

technical field

The invention belongs to the field of battery systems of new energy vehicles, and in particular relates to a battery system online life calculation method.

Background technique

Energy shortage and environmental pollution are major problems facing the world, and making full use of clean energy is an effective way to alleviate this problem. The development of energy-saving and environment-friendly automobiles has become an important direction of technological innovation in the world automobile industry and an inevitable choice for the sustainable development of the automobile industry. The high complexity and design difficulty of the battery system have always been the bottleneck restricting the promotion and application of this technology to new energy electric vehicles.

The types of power batteries currently used in new energy vehicles include: lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries and lithium batteries. Because of its small size, high energy density, long storage life, no memory effect, high voltage and low self-discharge rate, lithium batteries will replace lead-acid batteries and nickel-metal hydride batteries and become the winner of power batteries.

The battery is a complex electrochemical system, its degradation and failure mechanism is complicated, and the degradation mode is affected by many factors, so it is difficult to reflect it with a general model. The battery monitoring device used in many occasions only detects the floating charge voltage data. Through actual work, it is found that it is very difficult to accurately estimate the deterioration state of the battery relying on pure floating charge state data. Therefore, it is also necessary to use floating charge data to model obstacles encountered. Changes in internal resistance are important information for battery performance deterioration, but the internal resistance value does not strictly correspond to the degree of deterioration and can only be used as a reference. The degradation status of the battery system is very important for production and research, so an effective method must be proposed to calculate the online life of the battery system.

In order to improve the accuracy of battery system online life calculation and prevent the production research from causing heavy losses due to battery system degradation, the present invention proposes a battery system online life calculation method.

In existing patents, there have also been related descriptions of online life prediction for battery systems, such as a utility model named Method and Device for Estimating Battery Health State (Patent No. 200680022995.5). The patent is a device and method for estimating the state of health of a battery by using internal resistance, and the internal resistance has been found to be the parameter exerting the greatest influence on the state of health of the battery. The estimating method comprises the steps of: storing an SOH estimating table in a memory, said SOH estimating table establishing state of health values corresponding to various internal resistance values according to temperature and state of charge (SOC); When requested, perform temperature measurement and battery SOC estimation; detect the internal resistance value of the battery; and read the battery corresponding to the measured temperature, the estimated battery SOC, and the detected battery internal resistance value from the SOH estimation table. Health status value.

Another example is the invention patent titled diagnosis method of battery health status (Patent No. 200610078848). The patent includes the following steps for diagnosing battery health status: providing a battery discharge voltage and discharge current data; setting a predetermined time interval and the predetermined Acceptable value of discharge current change in time interval; analyze the change of discharge voltage and discharge current data within the predetermined time interval; record the discharge voltage, discharge current data and its change data; within the acceptable value of discharge current change Comparing the discharge voltage data and its change data; and displaying the comparison result as a health status diagnosis indicator.

Compared with the existing patents, the battery system online life calculation method described in this patent can calculate the battery system online life only by calculating the total amount of charging and discharging energy of the battery system. However, the above method and device for estimating the state of health of the battery require a greater workload and difficulty in obtaining the SOH estimation table, and are affected by many unstable factors. Especially when the battery deterioration is serious, the data to be collected is more difficult to obtain. In the above-mentioned patents on the diagnosis method of the battery health state, it is difficult to accurately set the acceptable value of the discharge current variation, and the selection of the acceptable value has a great impact on the diagnosis of the battery health state. However, in this patent, the online life of the battery system can be calculated conveniently by simply and accurately calculating the total amount of charging and discharging energy of the battery system.

Contents of the invention

Aiming at the existing technical defects, the present invention provides a battery system online life calculation method, which can conveniently realize the battery system online life calculation by calculating the total amount of charging and discharging energy of the battery system.

The further technical problem to be solved by the present invention is to consider how to reduce the impact of factors such as battery self-discharge and battery capacity changes at different temperatures on the calculation of charging and discharging energy, so as to calculate the online life of the battery system more accurately.

The present invention specifically adopts the following technical solutions.

An online life calculation method for a battery system. The method calculates and accumulates each charge and discharge energy of the battery system, and combines the total amount of charge and discharge energy that the battery system has currently completed with the charge and discharge energy of the battery system during the entire life of the battery system. The total amount of discharge energy is compared to obtain the online life of the battery system; it is characterized in that the steps of the method are as follows:

(1) Obtain the rated capacity (C) and number of cycles (N) of the battery system according to the factory parameters, and calculate the total amount of charging and discharging energy Q ₀₀ =C×N×2 during the entire service life of the battery system;

为电池系统充电过程或放电过程中的总电流；(2) Integrate the total current flowing into the battery system during the charging process and the total current flowing out of the battery system during the working state of the battery system, that is, the discharge process, and use the integrated value as the charging or discharging energy Q _n of the battery system this time, the energy ,in,

The total current during the charging process or discharging process for the battery system;

(3) Add the current charging or discharging energy Q _n of the battery system to the total amount of charging and discharging energy that has been completed before this charging and discharging of the battery system, so as to obtain the total amount of charging and discharging energy of the battery system Q ₀₁ = Q ₁ +Q ₂ +…+Q _n ;

(4) According to the total amount of charge and discharge energy Q ₀₀ obtained in step (1) during the entire service life of the battery system and the total amount of charge and discharge energy of the battery system obtained in step (3) Q ₀₁ , calculate the battery system

Compared with the existing calculation method, a battery system online life calculation method proposed by the present invention has the following two advantages:

The invention requires few input parameters to calculate the online life and can be collected by a simple device, that is, the online life of the battery system can be calculated only by calculating the total amount of charging and discharging energy of the battery system.

The calculation process of the invention is relatively simple and can be realized without complicated hardware and software equipment.

Description of drawings

Fig. 1 is the overall flowchart of the battery system online life calculation method proposed by the present invention;

Fig. 2 is a flow chart of calculating the charging and discharging energy of the battery system in the online life calculation method of the battery system proposed by the present invention;

Fig. 3 is a flow chart of calculating the sum of the charging and discharging energy of the battery system currently completed in the online life calculation method of the battery system proposed by the present invention.

Detailed ways

The battery system online life calculation method proposed by the present invention is composed of the following three parts: 1. Input the sum of charging and discharging energy of the battery system during the entire life; 2. Calculate the sum of charging and discharging energy that the battery system has currently completed; 3. The online life of the battery system is obtained by dividing the above two energies.

The total charge and discharge energy of the input battery system during the entire service life can be calculated by obtaining the two parameters of the rated capacity and cycle times marked by the battery factory, so that the total charge and discharge energy during the entire service life of the battery system can be calculated;

The calculation of the sum of the charging and discharging energy that the battery system has completed currently involves first integrating the total current flowing into or out of the battery system during each charging and discharging, and using the value obtained by the integration as the current charging and discharging power of the battery system, and then Then calculate the sum of all the charging and discharging energy that the battery system has currently completed;

The online service life of the battery system obtained by dividing the above two energies is obtained by calculating the ratio of the total charge and discharge energy of the battery system to the total charge and discharge energy of the battery system during the entire life of the battery system. online lifespan.

The method for calculating the online life of the battery system will be further described below in conjunction with the accompanying drawings.

Figure 1 is the overall flowchart of the online life calculation method of the battery system. This method first calculates the sum of charging and discharging energy during the entire life of the battery system, and then calculates the battery system by integrating and accumulating the total current flowing into and out of the battery system each time. The sum of the charging and discharging energy that has been completed at present, the online life of the battery system is predicted by the ratio of the above two energy sums. Specific steps are as follows:

(1) Obtain the rated capacity (C) and number of cycles (N) of the battery system according to the factory parameters, and calculate the total amount of charging and discharging energy Q ₀₀ =C×N×2 during the entire service life of the battery system;

，其中，

为电池系统充电过程或放电过程中的总电流；(2) Integrate the total current flowing into the battery system during the charging process and the working state of the battery system, that is, the total current flowing out of the battery system during the discharging process, and use the integrated value as the charging or discharging energy Q _n of the battery system this time, the energy

,in,

The total current during the charging process or discharging process for the battery system;

(3) Add the current charging or discharging energy Q _n of the battery system to the total amount of charging and discharging energy that has been completed before this charging and discharging of the battery system, so as to obtain the total amount of charging and discharging energy of the battery system Q ₀₁ = Q ₁ +Q ₂ +…+Q _n ;

。(4) According to the total amount of charge and discharge energy Q ₀₀ obtained in step (1) during the entire service life of the battery system and the total amount of charge and discharge energy of the battery system obtained in step (3) Q ₀₁ , calculate the battery system online life

.

，将

通过模数转换(ADC)变为数字量(CR)，之后以时基确定的速率进行累加（相当于对

进行积分），累加结果 (ACR)经过换算后即得到以安时为单位的充放电能量Q_n，能量公式为：。模数转换结果和累加后的结果都带有符号位，根据模块连接方式的不同而不同。通过微控制器可以读取ACR值并经过换算后得到真实的充放电能量Q_n。Fig. 2 is a flow chart of calculating the energy of each charge and discharge of the battery system in the online life calculation method of the battery system proposed by the present invention. The general idea is to integrate the total current flowing into or out of the battery system, and use the value obtained by the integration as the energy Q _n of the current (nth) charge and discharge of the battery system. total current in the circuit

,Will

It becomes a digital quantity (CR) through analog-to-digital conversion (ADC), and then accumulates at a rate determined by the time base (equivalent to the

Integrate), the cumulative result (ACR) is converted to get the charge and discharge energy Q _n in ampere-hours, and the energy formula is: . Both the analog-to-digital conversion result and the accumulated result have a sign bit, which varies according to the way the module is connected. The ACR value can be read by the microcontroller and converted to obtain the real charge and discharge energy Q _n .

Fig. 3 is a flow chart of calculating the sum of charging and discharging energy of the battery system currently completed in the online life calculation method of the battery system proposed by the present invention. The current (nth) charging and discharging energy Q _n of the battery system and the current The total amount of charging and discharging energy that has been completed before charging and discharging is added to obtain the latest sum of charging and discharging energy Q ₀₁ of the battery system.

Claims (1)

1. online Life Calculation method of battery system, this method is by calculating the each charging of battery system and discharge energy and adding up, with the total amount of current charging of having finished of battery system and discharge energy and battery system charges in whole life and the total amount of discharge energy compares, thereby draw the online life-span of battery system; It is characterized in that the step of described method is as follows:

(1), calculates and charge in the battery system process in whole serviceable life and the total amount Q of discharge energy according to dispatching from the factory rated capacity (C) and two parameters of cycle index (N) of parameter acquiring battery system ₀₀=C * N * 2;

(2) be that the total current that flows out battery system in the discharge process is carried out integration to the total current that in charging process, flows into battery system and in the battery system duty, and with integration institute value as this charge or discharge energy of battery system Q _n, described energy

, wherein, Be the total current in battery system charging process or the discharge process;

(3) with this charge or discharge energy of battery system Q _nThis charging finished before discharging and recharging and the total amount addition of discharge energy with battery system, thus the total amount Q of battery system charging at present and discharge energy obtained ₀₁=Q ₁+ Q ₂+ ... + Q _n

(4) the total amount Q of charging and discharge energy in the battery system process in whole serviceable life that obtains according to step (1) ₀₀And the total amount Q of charging at present of the battery system that obtains of step (3) and discharge energy ₀₁, calculate the online life-span of battery system

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