Charging method for series battery cells

Abstract

This invention discloses a charging method for rechargeable battery cells. The method includes a Total Voltage Follow-up Procedure (TVFP) and an Artificial Intelligent Equalizing Procedure (AIEP). When a specific battery cell's voltage is too high, that specific cell is discharged while other cells with lower voltages continue charging. This allows each battery cell to be charged to a nearly uniform level. The TVFP detects the total voltage of the series-connected batteries and adjusts the equalization start voltage in real time. The AIEP controls the voltage difference between battery cells within a pre-set range, resulting in a uniform voltage distribution among the battery cells.

Description

Technical Field

[0001] This invention relates to a series charging method for rechargeable battery cells, particularly a charging method for series-connected lithium batteries. Prior Technology

[0002] Figure 1 Previous Technique

[0003] Previous techniques demonstrated charging 160 series-connected lithium battery cells at a charging voltage of 550V and a charging current of 15A as an example. The first step is to set the charging voltage / current of the charger (550V / 15A). The second step is to start the charger to charge the series-connected battery cells. The third step is to determine whether the total voltage of the series-connected battery cells is higher than the target voltage of 550V. If yes, charging ends. If not, return to step two to continue charging.

[0004] This conventional technique, after charging the battery cells, ensures that the total voltage meets the requirements; however, the voltage of individual battery cells will vary. Using 550V / 160 = 3438mV, the average voltage of each battery cell is calculated to be 3438mV. If one cell has a voltage of 3238mV, then another must have a voltage of 3638mV for the average to equal 3438mV. This is due to inherent differences in each battery cell, including material variations, manufacturing process errors, etc., which cause uneven charging of individual cells under the same charging conditions.

[0005] Figure 2A Previous Technique

[0006] Figure 2A shows that after charging the series-connected battery cells using the conventional technique shown in Figure 1, the different battery cells will have different charging states. For example, the charge of battery cell 31 is lower than the average charge line L1, the charge of battery cell 32 is higher than the average charge line L1, and the charge of battery cell 33 is approximately equal to the average charge line L1. This difference in charge between battery cells will lead to a decrease in overall power supply efficiency. Summary of the Invention

[0007] This invention discloses a charging method for series batteries, comprising a Total Voltage Follow-up Procedure (TVFP) and an Intelligent Equalizing Procedure (AIEP). The TVFP detects the total voltage of the series batteries and adjusts the equalization start voltage in real time; the AIEP charges each cell of the series batteries to nearly the same level. Simple Explanation of the Diagram

[0008] Figure 1 Previous Technique

[0009] Figure 2A Previous Technique

[0010] Figure 2B shows the charging effect of the present invention.

[0011] Figures 3-4 show the charging method of the present invention. Implementation

[0012] Figure 2B shows the charging effect of the present invention.

[0013] Figure 2B shows that after charging using the present invention, the charging states of different battery cells are approximately the same. For example, the charge of battery cells 34, 35, and 36 is approximately equal to the average charge line L2. Therefore, the approximately equal charge of these battery cells will improve the overall power supply efficiency of the system.

[0014] Figures 3-4 show the charging method of the present invention.

[0015] The Total Voltage Follower Program (TVFP) of this invention is equipped with an Equalizing Trigger Voltage (ETV) to initiate the voltage equalization program of the battery cells and discharge over-voltage battery cells. The Intelligent Equalization Program (AIEP) of this invention is equipped with an Intelligent Equalizing Trigger Voltage (AI_ETV) to control the voltage of the battery cells to be equalized within a preset range.

[0016] This invention is illustrated by assuming a charging voltage of 550V / 15A for charging 160 series-connected lithium battery cells. Figures 3-4 show the charging method of this invention:

[0017] A method for charging series-connected battery cells includes a charger and series-connected batteries, wherein the charger charges the series-connected batteries according to the following steps:

[0018] Step 1: Set the charging voltage (CV) on the charger, for example, 550V / 15A;

[0019] Step 2: Start charging to charge the series-connected batteries; the theoretical average cell voltage is 550V / 160 = 3438mV;

[0020] Step 3: Start the Total Voltage Follow-up Procedure (TVFP);

[0021] Step 4: The Battery Management System (BMS) measures the total voltage of a single battery string. Is it greater than or equal to the target voltage (TV)? If not, return to Step 2; if yes, proceed to the next step. For example, the target voltage is set to 550V * 0.99 = 545V, where the coefficient 0.99 can be adjusted as needed.

[0022] Step 5: Calculate the average voltage of the battery cells. For example, if the measured voltage of the series-connected battery cells is 545V, then the average voltage of the battery cells is equal to 545V / 160 = 3406mV; and

[0023] Set the equalizing trigger voltage (ETV) to 3406mV + 2mV; where 2mV can be adjusted as needed.

[0024] Step Six: Measure whether the battery cell voltage is greater than or equal to the Equalization Start-up Voltage (ETV); if not, return to Step Four; if yes, proceed to the next step.

[0025] Step 7: Start the battery cell voltage equalization program to discharge specific battery cells;

[0026] Step 8: Check if all battery cell voltages are below the Equalization Start-up Voltage (ETV). If not, return to Step 7; if yes, proceed to the next step.

[0027] Step Nine: Check if the minimum battery cell voltage is lower than the minimum voltage setting. For example, the minimum voltage setting is 3320mV (adjust as needed). If not, return to Step Eight; if yes, proceed to the next step.

[0028] Step 10: Start the intelligent equalization program;

[0029] Step Eleven: Inspection:

[0030] (1) Is the total battery voltage greater than the Total Voltage Low Limit (TVLL) setting? For example, the TVLL setting is 550V-2V, where 2V can be adjusted as needed;

[0031] (2) Is the minimum battery cell voltage lower than the battery cell voltage low limit setting (BCVL)? For example: the battery cell voltage low limit setting is set to 3390mV (adjustable as needed);

[0032] (3) Is the maximum battery cell voltage greater than the upper limit setting value (Battery Cell Voltage High Limit, BCVHL)? For example: the upper limit setting value is set to 3438mV-2mV, where 2mV can be adjusted as needed;

[0033] If not, return to step three; if yes, proceed to the next step.

[0034] Step 12: Set the AI ​​Equalizing Trigger Voltage (AI_ETV); For example: Set the AI ​​Equalizing Trigger Voltage to 3438mV-2mV, where 2mV can be adjusted as needed;

[0035] Step 13: Activate the intelligent balancing program to discharge specific battery cells until the voltage of all battery cells is lower than the intelligent balancing activation voltage (AI_ETV);

[0036] Step Fourteen: Check if the battery cell voltage difference (BCVD) is less than the set value. For example, the BCVD is set to 20mV (adjustable as needed).

[0037] If not, return to step eleven; if yes, return to step three to start the Total Voltage Follower (TVFP) program.

[0038] Step 10, the intelligent balancing program, includes an optional step X: setting the program to close after a specified period. For example, running for 5 hours (the duration can be adjusted as needed), and then closing the program.

[0039] The reference values ​​used in the foregoing embodiments of this invention are for ease of understanding and are not intended to limit the scope of the claims. The following further explains the applicable scope of the reference values ​​of this invention:

[0040] The target voltage mentioned in step four is lower than the charging voltage. The target voltage mentioned in step four is equal to the charging voltage multiplied by a coefficient k1, where k1 = 98.5% to 99.5%.

[0041] The equalization start-up voltage mentioned in step five is equal to the average voltage of the battery cells in step five multiplied by a coefficient k2, where k2 is equal to 1.0005~1.0007.

[0042] The minimum voltage setting value in step nine is equal to the average voltage of the battery cells in step five multiplied by a coefficient k3, where k3 = 96.5%~98.5%.

[0043] The total voltage lower limit setting value in step eleven is equal to the charging voltage multiplied by a coefficient k4, where k4 = 99.5~99.7%.

[0044] The lower limit setting value of the battery cell voltage in step eleven is equal to the average voltage of the battery cell in step five multiplied by k5, where k5 = 99.3 ~ 99.7%.

[0045] The upper limit setting value of the battery cell voltage in step eleven is equal to the average voltage of the battery cell in step five multiplied by k6, where k6 = 1.007~1.010.

[0046] The battery cell differential voltage setting value in step fourteen is equal to the average battery cell voltage in step five multiplied by k7; where k7 = 0.5~3.5%.

[0047] The parameters used in the foregoing description are merely illustrative examples to help readers understand the spirit of this case and are not intended to limit the scope of the claims. The foregoing description discloses preferred embodiments and design drawings of the present invention; however, the preferred embodiments and design drawings are merely illustrative examples and are not intended to limit the scope of the claims of the present invention. Any implementation of the present invention by equivalent technical means, or implementation within the scope of the claims covered by the following claims, shall not depart from the spirit of the present invention and shall be within the scope of the applicant's claims.

[0048] L1: Average Battery Level Line 31: Battery Cell 32: Battery Cell 33: Battery Cell L2: Average Battery Level Line 34: Battery Cell 35: Battery Cell 36: Battery Cell

Claims

1. A method for charging series-connected battery cells, comprising a charger and series-connected batteries, wherein the charger charges the series-connected batteries according to the following steps: Step 1: The charger sets a charging voltage (CV); Step 2: Charging is initiated to charge the series-connected batteries; Step 3: A total voltage follow-up procedure (TVFP) is initiated; Step 4: The battery management system (BMS) measures the total voltage of a single series of batteries to determine if it is greater than or equal to the target voltage (TV). If yes, proceed to the next step; Step 5: The average voltage of the battery cells is calculated, and an equalizing trigger voltage (ETV) is set; Step 6: The battery cell voltage is measured to determine if it is greater than or equal to the equalizing trigger voltage (ETV). If yes, proceed to the next step; Step 7: A battery cell voltage equalization procedure is initiated to discharge specific battery cells whose cell voltage is greater than or equal to the equalizing trigger voltage (ETV); Step 8: Is the voltage of all battery cells lower than the equalizing trigger voltage (ETV)? If yes, proceed to the next step; Step Nine: Check if the lowest battery cell voltage is less than the lowest voltage setting value? If yes, proceed to the next step; Step Ten: Start the intelligent balancing program; Step Eleven: Check: (1) Is the total battery voltage greater than the total voltage low limit (TVLL) setting value? (2) Is the lowest battery cell voltage less than the battery cell voltage low limit (BCVLL) setting value? (3) Is the highest battery cell voltage greater than the battery cell voltage high limit (BCVHL) setting value? If yes, proceed to the next step; Step Twelve: Set the intelligent balancing start voltage (AI Equalizing Trigger Voltage, AI_ETV); Step Thirteen: Start the intelligent balancing program, discharge specific battery cells with cell voltages greater than or equal to the intelligent balancing start voltage (AI_ETV) until all battery cell voltages are lower than the intelligent balancing start voltage (AI_ETV); Step Fourteen: Check if the battery cell voltage difference (BCVD) is less than the battery cell voltage difference setting value? If so, return to step three to start the Total Voltage Follower (TVFP) program; where, The target voltage mentioned in step four is equal to the charging voltage multiplied by a coefficient k1, where k1 = 98.5~99.5%; the battery cell voltage difference setting value in step fourteen is equal to the average battery cell voltage in step five multiplied by k7, where k7 = 0.5~3.5%.

2. The series-connected battery cell charging method as described in claim 1, wherein, Step 10, the intelligent equalization program, further includes: Step X: Set the program to close after a certain period of time.

3. The series-connected battery cell charging method as described in claim 1, wherein, The equalization start-up voltage mentioned in step five is equal to the average voltage of the battery cells in step five multiplied by a coefficient k2, where k2 is equal to 1.0005~1.0007.

4. The series-connected battery cell charging method as described in claim 1, wherein, The minimum voltage setting value in step nine is equal to the average voltage of the battery cells in step five multiplied by a coefficient k3, where k3 = 96.5%~98.5%.

5. The series-connected battery cell charging method as described in claim 1, wherein, The total voltage lower limit setting value in step eleven is equal to the charging voltage multiplied by a coefficient k4, where k4 = 99.5~99.7%.

6. The charging method for series-connected battery cells as described in claim 1, wherein, The lower limit setting value of the battery cell voltage in step eleven is equal to the average voltage of the battery cell in step five multiplied by k5, where k5 = 99.3 ~ 99.7%.

7. The charging method for series-connected battery cells as described in claim 1, wherein, The upper limit setting value of the battery cell voltage in step eleven is equal to the average voltage of the battery cell in step five multiplied by k6, where k6 = 1.007~1.010.

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