A method and terminal for calculating direct current resistance based on a fast Fourier algorithm

Abstract

The present invention relates to the field of DC internal resistance detection, and in particular to a method and terminal for calculating DC internal resistance based on a fast Fourier algorithm. A battery is adjusted to a neutral state by charging and discharging, and data records of voltage and current under charging states with preset large current values ​​and preset small current values ​​are collected; current step points are screened in the data records according to current changes, and a preset number of sampling point data before and after the current step are taken to obtain sampling sequence data; a fast Fourier algorithm is used to extract the voltage amplitude and current amplitude of the sampling sequence data, and the DC internal resistance of the battery is calculated based on the voltage amplitude and the current amplitude; the present invention does not require the battery to be left stationary for a long time, and uses fast Fourier transform to extract the voltage amplitude and current amplitude through sampling points near the step points, and calculates the DC internal resistance based on the voltage amplitude and the current amplitude. Compared with traditional calculation methods, the DC internal resistance of the battery can be calculated more accurately.

Description

Technical Field

[0001] The present invention relates to the technical field of internal resistance calculation, and in particular to a method and terminal for calculating direct current internal resistance based on a fast Fourier algorithm. Background Art

[0002] With the gradual decline of traditional energy resources and the growing problem of environmental pollution, the development and utilization of new energy sources has become increasingly urgent. Against this backdrop, energy storage batteries, as a key technology, have attracted considerable attention. Energy storage batteries are increasingly popular in various fields, from homes to industry, not just electric vehicles.

[0003] One of the core metrics of energy storage batteries is DC internal resistance, which plays a crucial role in evaluating battery performance and safety. Monitoring and evaluating the stability of DC internal resistance is crucial, both in home energy storage systems and industrial applications. This not only ensures efficient operation of the battery system but also improves overall safety.

[0004] Therefore, improving the stability and accuracy of DC internal resistance detection technology is of great significance for the safety and performance evaluation of various energy storage battery systems.

[0005] Existing testing solutions require the battery to rest for a period of time while charging. Furthermore, the test conditions often fail to fully meet standard operating conditions. Multiple tests of the same battery's DC internal resistance can produce significant fluctuations in results, significantly interfering with safety assessments. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method and terminal for calculating DC internal resistance based on a fast Fourier algorithm, so as to more accurately detect the DC internal resistance of a battery.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] A method for calculating DC internal resistance based on a fast Fourier algorithm, comprising the steps of:

[0009] S1. Charge and discharge the battery to a neutral state, and collect data on the voltage and current under the preset high current value and the preset low current value charging state;

[0010] S2. Filtering current step points in the data record according to current changes, and taking a preset number of sampling point data before and after the current step to obtain sampling sequence data;

[0011] S3. Use a fast Fourier transform algorithm to extract the voltage amplitude and the current amplitude of the sampling sequence data, and calculate the DC internal resistance of the battery according to the voltage amplitude and the current amplitude.

[0012] In order to solve the above technical problems, another technical solution adopted by the present invention is:

[0013] A terminal for calculating DC internal resistance based on a fast Fourier algorithm comprises a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the method for calculating DC internal resistance based on the fast Fourier algorithm are implemented.

[0014] The beneficial effects of the present invention are: a method and terminal for calculating DC internal resistance based on the fast Fourier algorithm of the present invention do not need to keep the battery stationary for a long time, and screen the step points through the charging data of large current values ​​and small current values ​​in the neutral state of the battery. The voltage amplitude and current amplitude are extracted by fast Fourier transform through the sampling points near the step points, and the DC internal resistance is calculated based on the voltage amplitude and current amplitude. Compared with the traditional calculation method, the DC internal resistance of the battery can be calculated more accurately. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a flow chart of a method for calculating DC internal resistance based on a fast Fourier algorithm according to an embodiment of the present invention;

[0016] Figure 2 This is a structural diagram of a terminal for calculating DC internal resistance based on a fast Fourier algorithm according to an embodiment of the present invention;

[0017] Figure 3 This is a flowchart illustrating an example of effective step point screening in a method for calculating DC internal resistance based on a fast Fourier algorithm according to an embodiment of the present invention;

[0018] Figure 4 This is an example flow chart of a method for calculating DC internal resistance based on a fast Fourier algorithm according to an embodiment of the present invention, which uses a fast Fourier algorithm to calculate the DC internal resistance corresponding to a step point;

[0019] Figure 5 This is an example flow chart of calculating the final DC internal resistance based on multiple step-point DC internal resistances in a method for calculating DC internal resistance based on a fast Fourier algorithm according to an embodiment of the present invention;

[0020] Description of labels:

[0021] 1. A terminal for calculating DC internal resistance based on a fast Fourier algorithm; 2. A processor; 3. A memory. DETAILED DESCRIPTION

[0022] To illustrate the technical content, achieved objectives and effects of the present invention in detail, the following description is given in conjunction with the embodiments and accompanying drawings.

[0023] Name explanation:

[0024] DCR: DC internal resistance;

[0025] Fast Fourier Transform (FFT): FFT, also known as Fast Fourier Transform, is a mathematical algorithm used to convert a signal in the time domain into a signal in the frequency domain, or vice versa.

[0026] Current step point: the point where the current changes significantly during the charging detection process.

[0027] Amplitude: The amplitude of FFT (Fast Fourier Transform) refers to the amplitude or magnitude corresponding to each frequency component in the frequency domain.

[0028] Please refer to Figure 1 as well as Figures 3 to 5 , a method for calculating DC internal resistance based on fast Fourier algorithm, comprising the steps of:

[0029] S1. Charge and discharge the battery to a neutral state, and collect data on the voltage and current under the preset high current value and the preset low current value charging state;

[0030] S2. Filtering current step points in the data record according to current changes, and taking a preset number of sampling point data before and after the current step to obtain sampling sequence data;

[0031] S3. Use a fast Fourier transform algorithm to extract the voltage amplitude and the current amplitude of the sampling sequence data, and calculate the DC internal resistance of the battery according to the voltage amplitude and the current amplitude.

[0032] From the above description, it can be seen that the beneficial effects of the present invention are: a method and terminal for calculating DC internal resistance based on the fast Fourier algorithm of the present invention do not need to keep the battery stationary for a long time. The step points are screened through the charging data of large current values ​​and small current values ​​of the battery in the neutral state, and the voltage amplitude and current amplitude are extracted by fast Fourier transform through the sampling points near the step points. The DC internal resistance is calculated based on the voltage amplitude and current amplitude. Compared with the traditional calculation method, the DC internal resistance of the battery can be calculated more accurately.

[0033] Furthermore, step S3 includes the steps of:

[0034] S31. For each step point, extract the voltage amplitude and the current amplitude of the sampling sequence data using a fast Fourier transform algorithm, and calculate the DC internal resistance of the battery based on the voltage amplitude and the current amplitude;

[0035] S32 , performing validity screening on the DC internal resistances calculated from multiple step points, and performing average calculation on the DC internal resistances that pass the screening to obtain a final DC internal resistance.

[0036] As can be seen from the above description, the DC internal resistance calculated at multiple step points is averaged to obtain the final DC internal resistance, thereby improving the accuracy of the DC internal resistance calculation.

[0037] Furthermore, the DC internal resistance of the battery is calculated based on the voltage amplitude and the current amplitude as follows:

[0038] S311. Calculate the DC internal resistance DCR corresponding to each sampling point based on the voltage amplitude vol_fft and current amplitude cur_fft of each sampling point extracted by the fast Fourier algorithm:

[0039]

[0040] S312, filtering the DC internal resistance corresponding to the sampling point;

[0041] S313 , performing average calculation on the filtered data to obtain the DC internal resistance corresponding to the step point.

[0042] As can be seen from the above description, the DC internal resistance of the step point is calculated based on the average of the DC internal resistances of the preceding and following sampling points after filtering, thereby improving the accuracy of the DC internal resistance calculation.

[0043] Furthermore, step S312 includes the following steps:

[0044] Filter out data with DCR < 0;

[0045] Filter out data with voltage amplitude absolute value abs(vol_fft) < 0.2.

[0046] As can be seen from the above description, the DC internal resistance at the sampling point is filtered through the function step to remove noise, so as to calculate the DC internal resistance corresponding to the step point more accurately.

[0047] Furthermore, the following steps are included between step S312 and step S313:

[0048] S3121. Determine the validity of the DC internal resistance corresponding to the remaining sampling points:

[0049] Determine whether the number of remaining sampling point data is greater than the preset number threshold, if not, the data is invalid;

[0050] Determine whether the DC internal resistance corresponding to the remaining sampling point data exists:

[0051] DCR max -DCRmin <0.5*DCR min ;

[0052] If so, the data is valid, otherwise the data is invalid;

[0053] Go to step S313 only when the data is valid;

[0054] Among them, DCR max Indicates the maximum value of the DC internal resistance corresponding to the remaining sampling point data, DCR min Indicates the minimum value of the DC internal resistance corresponding to the remaining sampling point data.

[0055] From the above description, it can be seen that the validity of the DC internal resistance of the filtered sampling points is judged. If the number of DC internal resistance samples remaining after filtering is small or the value span is too large, the calculation is considered invalid. Otherwise, the data is valid.

[0056] Furthermore, the effectiveness screening of the DC internal resistance calculated at multiple step points in step S32 is specifically as follows:

[0057] S321. Determine whether the DC internal resistance calculated from all the step points satisfies a filtering condition:

[0058] DCR max -DCR min >0.5*DCR min ;

[0059] If yes, filter the step point with the largest value;

[0060] S322: Repeat step S321 until the filtering condition is no longer met.

[0061] As can be seen from the above description, the DC internal resistance calculated from the step point is filtered through the above steps.

[0062] Furthermore, step S1 includes the steps of:

[0063] S11, charge and discharge to adjust the battery SOC to a neutral state;

[0064] S12, outputting a constant current at a preset low current value for a preset time, and collecting voltage and current data during the preset time;

[0065] S13, outputting a constant current at a preset high current value for a preset time, and collecting voltage and current data during the preset time;

[0066] S14. Take steps S12 to S13 as one data collection action, repeat it for a preset number of times, and obtain data records of voltage and current.

[0067] From the above description, it can be seen that the voltage and current data are collected for the constant current output in both large current and small current situations, and the process is repeated multiple times to ensure the validity of the collected data.

[0068] Furthermore, step S2 includes the steps of:

[0069] S21, screening the voltage and current data obtained from each data collection action in the data record to obtain first data that meets the screening condition;

[0070] The screening conditions are:

[0071] I max -I min >0.3*I max ;

[0072] S22. In the first data, determine whether there are a number of consecutive current data points that meet the determination criteria, and record them as current step points;

[0073] The judgment conditions are:

[0074] I pre -I next >0.1*(I max -I min );

[0075] Extract the preset number of sampling point data before and after to obtain sampling sequence data.

[0076] As can be seen from the above description, according to the above steps, the current step point is determined by collecting the current difference between the points.

[0077] Furthermore, step S2 further includes the steps of:

[0078] S23 , judging the validity of the sampling sequence data. If the sampling time intervals of the sampling points are consistent, the sampling sequence data is valid; otherwise, the sampling sequence data is invalid.

[0079] As can be seen from the above description, the sampling interval in the sampling sequence data is judged to determine whether the sampling sequence data is valid.

[0080] Please refer to Figure 2 A terminal for calculating DC internal resistance based on the fast Fourier algorithm includes a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the method for calculating DC internal resistance based on the fast Fourier algorithm are implemented.

[0081] The present invention provides a method and terminal for calculating DC internal resistance based on a fast Fourier algorithm, which are suitable for detecting the DC internal resistance of energy storage batteries, and are particularly suitable for measuring the internal resistance of batteries of new energy vehicles.

[0082] Please refer to Figure 1 as well as Figures 3 to 5 , embodiment 1 of the present invention is:

[0083] A method for calculating DC internal resistance based on a fast Fourier algorithm, comprising the steps of:

[0084] S1. Charge and discharge the battery to a neutral state, and collect data on the voltage and current under the preset high current value and the preset low current value charging state;

[0085] Step S1 includes the steps of:

[0086] S11. Charge and discharge to adjust the battery's SOC to a neutral state.

[0087] In this embodiment, the SOC of the electric power system is adjusted to 50% by charging and discharging the entire vehicle (including onboard electrical equipment).

[0088] S12: Outputting a constant current at a preset small current value for a preset time period, and collecting voltage and current data within the preset time period.

[0089] In this embodiment, a constant current output of 0.1I (A) is applied for 10 seconds, and the current and voltage of the power battery system during this period are recorded. Where I represents the rated current of the battery system.

[0090] S13: Outputting a constant current at a preset high current value for a preset time period, and collecting voltage and current data within the preset time period.

[0091] In this embodiment, a constant current output of I (A) is maintained for 10 seconds, and the current and voltage of the power battery system at this stage are recorded.

[0092] In this embodiment, the rated charging current is 1C, the preset large current value range is around 0.8C, which can reach 1C, and the preset small current value range is around 0.1C.

[0093] S14. Take steps S12 to S13 as one data collection action, repeat it for a preset number of times, and obtain data records of voltage and current.

[0094] In this embodiment, steps S12 and S13 are repeated multiple times to collect the recorded current and voltage data.

[0095] S2. Filtering current step points in the data record according to current changes, and taking a preset number of sampling point data before and after the current step to obtain sampling sequence data;

[0096] In this embodiment, refer to Figure 3 , step S2 comprises the steps of:

[0097] S21, screening the voltage and current data obtained from each data collection action in the data record to obtain first data that meets the screening condition;

[0098] The screening conditions are:

[0099] I max -I min >0.3*I max .

[0100] In this embodiment, it is determined whether the current charging order meets the conditions. max -I min >0.3*I max If the condition is not met, the calculation is interrupted.

[0101] S22. In the first data, determine whether there are a number of consecutive current data points that meet the determination criteria, and record them as current step points;

[0102] The judgment conditions are:

[0103] I pre -I next >0.1*(I max -I min );

[0104] Extract the preset number of sampling point data before and after to obtain sampling sequence data.

[0105] In this embodiment, the current step point is screened and the continuous current sampling points meet I pre -I next >0.1*(I max -I min ), defined as the current step point.

[0106] Extract 5 sampling points before and after the step point, for a total of 11 sampling points.

[0107] S23 , judging the validity of the sampling sequence data. If the sampling time intervals of the sampling points are consistent, the sampling sequence data is valid; otherwise, the sampling sequence data is invalid.

[0108] In this embodiment, it is checked whether the time intervals of the sampling points are consistent. If not, the calculation is interrupted. If they are consistent, the step point sampling data, that is, the sampling sequence data, is obtained.

[0109] S3. Use a fast Fourier transform algorithm to extract the voltage amplitude and the current amplitude of the sampling sequence data, and calculate the DC internal resistance of the battery according to the voltage amplitude and the current amplitude.

[0110] Step S3 includes the steps of:

[0111] S31. For each step point, extract the voltage amplitude and the current amplitude of the sampling sequence data using a fast Fourier transform algorithm, and calculate the DC internal resistance of the battery based on the voltage amplitude and the current amplitude;

[0112] In this embodiment, refer to Figure 4 , the DC internal resistance of the battery is calculated based on the voltage amplitude and the current amplitude as follows:

[0113] S311. Calculate the DC internal resistance DCR corresponding to each sampling point based on the voltage amplitude vol_fft and current amplitude cur_fft of each sampling point extracted by the fast Fourier algorithm:

[0114]

[0115] S312, filtering the DC internal resistance corresponding to the sampling point;

[0116] Step S312 includes the following steps:

[0117] Filter out data with DCR < 0;

[0118] Filter out data with voltage amplitude absolute value abs(vol_fft) < 0.2.

[0119] In this embodiment, refer to Figure 4 , a total of 11 DC internal resistances are calculated from the step point sampling data, and the first one is filtered out; the sampling points with DCR < 0 are filtered out; and the sampling points with the absolute value of the voltage amplitude abs(vol_fft) < 0.2 are filtered out.

[0120] The following steps are also included between step S312 and step S313:

[0121] S3121. Determine the validity of the DC internal resistance corresponding to the remaining sampling points:

[0122] Determine whether the number of remaining sampling point data is greater than the preset number threshold, if not, the data is invalid;

[0123] Determine whether the DC internal resistance corresponding to the remaining sampling point data exists:

[0124] DCR max -DCR min <0.5*DCR min ;

[0125] If so, the data is valid, otherwise the data is invalid;

[0126] Go to step S313 only when the data is valid;

[0127] Among them, DCR max Indicates the maximum value of the DC internal resistance corresponding to the remaining sampling point data, DCR min Indicates the minimum value of the DC internal resistance corresponding to the remaining sampling point data.

[0128] In this embodiment, it is checked whether the number of remaining sampling points is greater than or equal to 3, and the calculation is interrupted if it is less than 3; check DCR max -DCR min <0.5*DCR min , the calculation is interrupted if the conditions are not met.

[0129] S313 , performing average calculation on the filtered data to obtain the DC internal resistance corresponding to the step point.

[0130] In this embodiment, the average value of the DCRs of the sampling points is taken as the DCR of the step point.

[0131] S32, screening the DC internal resistances calculated at multiple step points for effectiveness, averaging the DC internal resistances that pass the screening to obtain a final DC internal resistance;

[0132] In this embodiment, refer to Figure 5 In step S32, the effectiveness screening of the DC internal resistance calculated at multiple step points is specifically as follows:

[0133] S321. Determine whether the DC internal resistance calculated from all the step points satisfies a filtering condition:

[0134] DCR max -DCR min >0.5*DCR min ;

[0135] If yes, filter the step point with the largest value;

[0136] S322: Repeat step S321 until the filtering condition is no longer met.

[0137] In this embodiment, if the step point data has been filtered, the calculation is terminated. Otherwise, the average value of the DC internal resistance corresponding to all step points is calculated as the final DC internal resistance. The final DCR of the charging test order is returned.

[0138] Please refer to Figure 2 , the second embodiment of the present invention is:

[0139] A terminal 1 for calculating a DC internal resistance based on a fast Fourier algorithm includes a processor 2, a memory 3, and a computer program stored in the memory 3 and executable on the processor 2. When the processor 2 executes the computer program, the steps of the method for calculating a DC internal resistance based on a fast Fourier algorithm described in the first embodiment above are implemented.

[0140] In summary, the present invention provides a method and terminal for calculating DC internal resistance based on the fast Fourier algorithm. There is no need to keep the battery stationary for a long time. The step points are screened through the charging data of large current values ​​and small current values ​​in the neutral state of the battery. The voltage amplitude and current amplitude are extracted by fast Fourier transform through the sampling points near the step points. The DC internal resistance is calculated based on the voltage amplitude and current amplitude. At the same time, the data is denoised and screened during the calculation process, so that the final calculated DC internal resistance result is more stable and robust, and the DC internal resistance of the battery can be calculated more accurately than the traditional calculation method.

[0141] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's description and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for calculating DC internal resistance based on fast Fourier algorithm, characterized in that: Including steps: S1. Charge and discharge the battery to a neutral state, and collect data on the voltage and current under the preset high current value and the preset low current value charging state; S2. Filtering current step points in the data record according to current changes, and taking a preset number of sampling point data before and after the current step point to obtain sampling sequence data; S3. Using a fast Fourier transform algorithm to extract the voltage amplitude and the current amplitude of the sampling sequence data, and calculating the DC internal resistance of the battery according to the voltage amplitude and the current amplitude; Step S3 includes the steps of: S31. For each step point, extract the voltage amplitude and the current amplitude of the sampling sequence data using a fast Fourier transform algorithm, and calculate the DC internal resistance of the battery based on the voltage amplitude and the current amplitude; S32, screening the DC internal resistances calculated at multiple step points for effectiveness, averaging the DC internal resistances that pass the screening to obtain a final DC internal resistance; The DC internal resistance of the battery is calculated according to the voltage amplitude and the current amplitude as follows: S311. Calculate the DC internal resistance DCR corresponding to each sampling point based on the voltage amplitude vol_fft and current amplitude cur_fft of each sampling point extracted by the fast Fourier algorithm: ； S312, filtering the DC internal resistance corresponding to the sampling point; S313, performing average calculation on the filtered data to obtain the DC internal resistance corresponding to the step point; The following steps are also included between step S312 and step S313: S3121. Determine the validity of the DC internal resistance corresponding to the remaining sampling points: Determine whether the number of remaining sampling point data is greater than the preset number threshold, if not, the data is invalid; Determine whether the DC internal resistance corresponding to the remaining sampling point data exists: ； If so, the data is valid, otherwise the data is invalid; Go to step S313 only when the data is valid; in, Indicates the maximum value of the DC internal resistance corresponding to the remaining sampling point data. Indicates the minimum value of the DC internal resistance corresponding to the remaining sampling point data.

2. The method for calculating DC internal resistance based on the fast Fourier transform algorithm according to claim 1, characterized in that: Step S312 includes the following steps: Filter out data with DCR < 0; Filter out data with the absolute value of the voltage amplitude abs(vol_fft) < 0.

2.

3. The method for calculating DC internal resistance based on fast Fourier algorithm according to claim 1, characterized in that: The effectiveness screening of the DC internal resistance calculated at multiple step points in step S32 is specifically as follows: S321. Determine whether the DC internal resistance calculated from all the step points satisfies a filtering condition: ； If yes, filter the step point with the largest value; S322: Repeat step S321 until the filtering condition is no longer met.

4. The method for calculating DC internal resistance based on the fast Fourier transform algorithm according to claim 1, characterized in that: Step S1 includes the steps of: S11, charge and discharge to adjust the battery SOC to a neutral state; S12, outputting a constant current at a preset low current value for a preset time, and collecting voltage and current data during the preset time; S13, outputting a constant current at a preset high current value for a preset time, and collecting voltage and current data during the preset time; S14. Take steps S12 to S13 as one data collection action, repeat it for a preset number of times, and obtain data records of voltage and current.

5. The method for calculating DC internal resistance based on fast Fourier algorithm according to claim 4, characterized in that: Step S2 includes the steps of: S21, screening the voltage and current data obtained from each data collection action in the data record to obtain first data that meets the screening condition; The screening conditions are: ； S22. In the first data, determine whether there are a number of consecutive current data points that meet the determination criteria, and record them as current step points; The judgment conditions are: ； Extract the preset number of sampling point data before and after to obtain sampling sequence data.

6. The method for calculating DC internal resistance based on fast Fourier algorithm according to claim 5, characterized in that: Step S2 further includes the steps of: S23 , judging the validity of the sampling sequence data. If the sampling time intervals of the sampling points are consistent, the sampling sequence data is valid; otherwise, the sampling sequence data is invalid.

7. A terminal for calculating DC internal resistance based on a fast Fourier algorithm, comprising a processor, a memory, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method for calculating DC internal resistance based on the fast Fourier algorithm described in any one of claims 1 to 6 are implemented.

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