CN104166097B - How to measure battery power - Google Patents

Abstract

The present invention provides a battery power measurement method, which includes the following steps: providing a query table storing a plurality of preset measurement confirmation voltages and a plurality of set power levels; measuring a first voltage of the battery as a starting point; calculating an end point according to the query table and the starting point; measuring the voltage and current of the battery until a measured voltage reaches a preset measurement confirmation voltage corresponding to the end point; calculating a set power level from the starting point to the end point according to the query table; calculating an actual power level from the starting point to the end point; and correcting the set power level according to the difference between the actual power level and the set power level.

Description

How to measure battery power

technical field

The invention relates to a battery measurement, in particular to a battery power measurement method.

Background technique

In general, there are roughly the following methods for measuring power with a battery measuring IC (gas gauge IC).

The first method of measuring electricity uses a coulomb counter. The coulomb counter obtains the battery capacity by integrating the current flowing into/out of the battery. However, the disadvantage is that it is effective for new batteries but cannot overcome the problems of battery aging and battery self-discharge. In addition, the power of the battery must be obtained after the battery is completely discharged.

The second power measurement method uses open circuit voltage (OCV) for measurement. The power of the battery is monitored by the correlation between the battery voltage and the state of charge (SOC). However, the disadvantage is that the battery needs to reflect the change of power when there is no load. In addition, when measuring the open circuit voltage, the battery usually returns to a steady state after 30 minutes of discharge. Therefore, it takes a period of waiting time to measure the power, and it cannot be measured during the battery discharge process.

The third power measurement method uses internal resistance to measure. Since the internal impedance of the battery will vary with the battery capacity, the remaining capacity of the battery can be predicted by measuring the internal impedance of the battery. However, the disadvantage is that it is not easy to measure the internal resistance of the battery, and the difference in internal resistance changes will be greater when the battery is aged.

However, the above-mentioned methods have their disadvantages, so a better method for measuring the power of the battery is needed.

Contents of the invention

In view of this, the present invention proposes a battery power measurement method to solve the problems mentioned in the prior art.

The invention provides a method for measuring the power of a battery. The power measurement method includes the following steps. A look-up table is provided, storing multiple preset measurement confirmation voltages and multiple set electric quantities. The first voltage of the battery is measured as a starting point. Calculate the end point from the lookup table and the start point. Measure the voltage and current of the battery until a measured voltage reaches a preset measurement confirmation voltage corresponding to the end point. Calculate the set power from the start point to the end point according to the look-up table. Calculate the actual power from the start point to the end point. And correct the set electric quantity according to the difference between the actual electric quantity and the set electric quantity.

In an embodiment of the present invention, the preset measurement confirmation voltages include a full voltage and a cutoff voltage.

In one embodiment of the present invention, in the step of "calculating the set electric quantity from the start point to the end point according to the look-up table", if the start point falls between the voltage at point N and the voltage at point N+1 of the look-up table, Use the internal difference method to calculate the corresponding set electric quantity.

In an embodiment of the present invention, the look-up table further stores a plurality of temperature information and electric power information corresponding to each temperature information.

In an embodiment of the present invention, the step of "calculating the end point according to the look-up table and the start point" includes: measuring the temperature value of the battery; judging whether the temperature value can be found from the temperature information in the look-up table, if "Yes ", the preset measurement confirmation voltage of the corresponding temperature value is taken as the end point, and if "No", the preset measurement confirmation voltage of the corresponding temperature value is calculated by the internal difference method as the end point.

In an embodiment of the present invention, the look-up table also includes storing a plurality of current information, and the step of "calculating the end point according to the look-up table and the starting point" includes: measuring the current of the battery and calculating the battery current within a preset time the average current; judge whether the average current can be found from the current information in the look-up table, if "Yes", the preset measurement confirmation voltage of the corresponding average current will be used as the end point, if "No", the internal difference method will be used to calculate the corresponding The preset measurement of the average current confirms the voltage as the end point.

In an embodiment of the present invention, the preset time is 5 seconds.

In an embodiment of the present invention, the method for measuring the battery capacity further includes calculating the remaining capacity percentage of the battery according to the corrected set capacity.

The invention further provides a method for measuring the power of the battery. The power measurement method includes the following steps. Acquiring a plurality of battery measurement parameters at preset time intervals; generating an average current based on at least one battery measurement parameter of the battery measurement parameters; using the average current in the look-up table to calculate a set electric quantity in a voltage range; calculating the voltage at the actual power generated in the interval; and correct the set power according to the difference between the actual power and the set power.

In an embodiment of the present invention, the look-up table stores a plurality of preset average currents and information about the full voltage to the cut-off voltage.

In one embodiment of the present invention, in the step of "using the average current in the look-up table to calculate the set electric quantity of the voltage interval", if the average current falls between the Nth voltage interval and the N+1th voltage interval of the lookup table , using the internal difference method to calculate the corresponding set electric quantity.

Based on the above, the present invention can correct the set electric quantity of the lookup table according to the difference between the actual electric quantity and the set electric quantity of the lookup table when measuring the electric quantity of the battery. Further, the remaining capacity percentage of the battery can be calculated. The invention does not require the battery to go through a complete discharge procedure and does not require complicated calculations. The power measurement method of the present invention also improves the existing open-circuit voltage measurement method, and does not need to wait for a recovery time of 30 minutes. In this way, the set power can be corrected according to battery characteristics, aging results or temperature effects, which can improve measurement efficiency.

It should be understood that the above general description and the following specific embodiments are only illustrative and explanatory, and cannot limit the scope of the present invention.

Description of drawings

The accompanying drawings, which are a part of the specification of this invention, illustrate example embodiments of the invention and together with the description serve to explain the principles of the invention.

FIG. 1 is a flowchart of a battery power measurement method according to an embodiment of the invention.

FIG. 2 is a flowchart of a power measurement method according to another embodiment of the present invention.

FIG. 3 is a detailed flowchart of step S213.

FIG. 4 is a flow chart of a method for measuring battery capacity according to another embodiment of the present invention.

Reference signs:

S110-S170: each step of the battery power measuring method according to an embodiment of the present invention

S201-S225: each step of the power measurement method according to another embodiment of the present invention

S301～S311: details of step S213 and each step

S410-S450: each step of the battery power measuring method according to another embodiment of the present invention

detailed description

FIG. 1 is a flowchart of a battery power measurement method according to an embodiment of the invention. See Figure 1. The power measurement method of this embodiment may include the following steps.

As shown in step S110, a lookup table is provided, and the lookup table stores a plurality of preset measurement confirmation voltages and a plurality of preset electric quantities, wherein the preset measurement confirmation voltages include full voltage and Cutoff voltage (cutoff voltage). Therefore, the look-up table stores information about the full voltage to the cut-off voltage. In addition, the look-up table also stores a plurality of temperature information and power information corresponding to each temperature information. For example, the lookup table may include Table 1 to Table 3 as follows. Table 1 is the 35°C/1C comparison table, Table 2 is the 35°C/0.7C comparison table, and Table 3 is the 5°C/0.1C comparison table. Among them, the charge and discharge current based on 1 hour is called 1C. For example, "1C current of a battery with a set capacity of 1000mAH" means that the current is 1000mA, and "0.1C current of a battery with a set capacity of 1000mAH" is Indicates that the current is 100mA.

Table 1 (35℃/1C comparison table)

Preset measurement confirmation voltage (mV) Set power (mAH) 4032 (full voltage) 4328 3932 152 3882 192 3832 (assumed to be the Nth point) 225 3782 (assumed to be the N+1th point) 249 3732 282 3682 329 3632 391 3582 494 3532 688 3482 591 3432 321 3382 145 3331 80 3232 89 3000 (cut-off voltage) 98 0 16

Table 2 (35℃/0.7C comparison table)

Preset measurement confirmation voltage (mV) Set power (mAH) 4100 4293 3990 305 3935 252 3880 265 3825 301 3770 355 3715 469 3660 683 3605 816 3550 453 3495 160 3440 64 3384 41 3330 32 3220 46 3000 51 0 17

Table 3 (5℃/0.1C comparison table)

Preset measurement confirmation voltage (mV) Set power (mAH) 4177 4253 4067 439 4012 279 3957 308 3902 350 3847 324

3792 472 3737 994 3682 481 3627 442 3572 59 3517 44 3462 35 3407 28 3297 43 3000 54 0 92

As shown in step S120, the first voltage of the battery is measured as a starting point. The battery is measured during the discharge procedure, and the measured first voltage is taken as a starting point. For example, the measured battery is 35°C/1C/3830mV, so the starting point is set to 3830mV.

As shown in step S130, the end point is calculated according to the lookup table and the start point. For example, according to Table 1 (35°C/1C comparison table), the first voltage 3830mV is between the preset measurement confirmation voltage 3832mV (assumed to be the Nth point) and the preset measurement confirmation voltage 3782mV (assumed to be the N+1th point ), the voltage value at the end point needs to be smaller than the voltage value at the start point, so the end point can be calculated to be 3782mV.

As shown in step S140 , measure the voltage and current of the battery until a measured voltage reaches a preset measurement confirmation voltage corresponding to the end point.

As shown in step S150, the set electric quantity from the start point to the end point is calculated according to the look-up table.

As shown in step S160, the actual power from the start point to the end point is calculated. For example, the starting point (3830mV) can be expressed as SOVstart and falls on the preset measurement confirmation voltage of 3832mV (assumed to be the Nth point, the set power is 225mAH) and the preset measurement confirmation voltage of 3782mV (assumed to be the N+1th point , which can be expressed as SOVend or SOV _N+1 , and the set power is 249mAH), please refer to equation (1), and the internal difference method can be used to calculate the distance between the starting point (SOVstart) and the ending point (SOVend or SOV _N+1 ) The corresponding set power is 239mAH.

$\frac{\mathrm{SOVstart}-{\mathrm{SOV}}_{N+1}}{{\mathrm{SOV}}_N-{\mathrm{SOV}}_{N+1}}\×Q_{N+1}=\frac{3830-3782}{3832-3782}\×249=239\left(\mathrm{mAH}\right)$ (1).

As shown in step S170, the set electric quantity is corrected according to the difference between the actual discharged electric quantity and the set electric quantity. For example, assuming that the set capacity of the original battery is 1000mAH, and if the difference between the actual capacity and the set capacity is 20mAH, then the set capacity Qmax of the updated battery is 1000mAH minus 20mAH to equal 980mAH.

In addition, the remaining capacity percentage (relative state of charge, RSOC) of the battery can be calculated according to the corrected set electric capacity. For example, if the battery is discharged for 10 seconds with an average current of 700mA and a temperature of 35°C, it can be calculated according to Table 2 (35°C/0.7C comparison table); assuming that the original battery set power is 1000mAH, the updated The set capacity of the battery is 980mAH. For the calculation formulas of the original RSOC and the updated RSOC, please refer to equations (2) and (3) respectively.

original $\mathrm{RSOC}=\frac{1000\mathrm{mAH}-(1000\mathrm{mA}\×10\sec )}{1000\mathrm{mAH}}\×`100\%$ …(2).

updated $\mathrm{RSOC}=\frac{980\mathrm{mAH}-(1000\mathrm{mA}\×10\sec )}{980\mathrm{mAH}}\×`100\%$ ...(3).

Generally speaking, in this embodiment, during the discharge process of the battery, the set power of the lookup table is corrected by the difference between the actual power and the set power, and the power of the battery or the remaining capacity of the battery can be calculated without complete discharge percentage. In other words, this embodiment does not need to add additional hardware or interrupt the discharge behavior of the battery. In addition, the aging degree of the battery can be detected according to the set electric quantity of the battery. In this embodiment, there is no need to create a huge table to record parameter values. Therefore, the present embodiment will help to reduce the hardware cost and the complexity of the related circuits when the power measurement is performed.

FIG. 2 is a flow chart of a battery power measurement method according to another embodiment of the present invention. See Figure 2. The power measurement method of this embodiment is based on the principle of the embodiment shown in FIG. 1 and may include the following steps.

As shown in step S201, the lookup table is loaded. Next, as shown in step S203, a preset time of the timer is set, for example, 5 seconds.

In step S205, judge whether to reach 5 seconds, if "yes", go to step S207, otherwise go back to step S205.

As shown in step S207, the state of the battery, such as voltage/current/temperature, is measured. Then, as shown in step S209, it is judged whether to discharge, if "yes", go to step S311, otherwise go to step S205.

As shown in step S211 , the average current within a preset time (for example, 5 seconds) is calculated, and the first voltage of the battery is measured as a starting point (which may be expressed as SOVstart). Next, as shown in step S213, the end point (which can be expressed as SOVend) is obtained through calculation according to the lookup table and the start point. Then, as shown in step S215, the voltage and current of the battery are measured until a measured voltage reaches the preset measurement confirmation voltage corresponding to the end point (SOVend). If "Yes", go to step S217, otherwise go back to step S205.

As shown in step S217 , the set electric quantity (QT) from the start point to the end point is calculated according to the look-up table, and the actual electric quantity (QC) from the start point to the end point is calculated. Then, as shown in step S219, it is judged whether QC is greater than QT, if "Yes", enter step S221, otherwise, enter step S223.

As shown in step S221, it means that the actual power (QC) in this interval is greater than the set power (QT), and the set power of the battery is corrected Qmax=Qmax+(QC-QT), where Qmax on the right side of the equation is the value before the update, and Qmax on the left side of the equation is the updated value, and then enter step S225.

As shown in step S223, it means that the actual power (QC) in this interval is less than the set power (QT), and the set power of the battery is corrected Qmax=Qmax-(QT-QC), where Qmax on the right side of the equation is the value before updating, The Qmax on the left side of the equation is the updated value, and then enter step S225.

As shown in step S225, the lookup table is updated. Then go back to step S205 to perform another power measurement process (such as steps S205 to S225 ).

The detailed steps of step S213 will be introduced below. See Figure 3. The step S213 of calculating the end point according to the lookup table and the start point further includes the following steps S301 to S311.

As shown in step S301, the average current and the measured temperature are calculated. Then, as shown in step S303, it is judged whether the look-up table has the above-mentioned temperature value, if "yes", go to step S307, otherwise go to step S305.

As shown in step S305 , the voltage corresponding to the above temperature value is calculated using the internal difference method as the end point (SOVend), and then enters step S307 .

As shown in step S307, it is judged whether the look-up table has the above-mentioned average current, if "yes", go to step S311, otherwise go to step S309.

As shown in step S309, the voltage corresponding to the above-mentioned average current is calculated by using the internal difference method as the end point (SOVend), and then enters step S311.

As shown in step S311, the end point (SOVend) is recorded according to the value calculated or found out from the lookup table.

FIG. 4 is a flow chart of a method for measuring battery capacity according to another embodiment of the present invention. See Figure 4. The power measurement method of this embodiment may include the following steps.

As shown in step S410, a plurality of battery measurement parameters are acquired at preset intervals. For example, the preset time may be 5 seconds, and the battery measurement parameters may include voltage, current, temperature, and power, but are not limited thereto.

As shown in step S420, an average current is generated according to at least one battery measurement parameter of the battery measurement parameters.

As shown in step S430, the set electric quantity of a voltage range is calculated by using the average current in the look-up table. For example, when the average current is 100mA and the temperature is 5°C, it can be calculated according to Table 3 (5°C/0.1C comparison table). Relevant detailed steps can be performed by imitating the aforementioned steps S120 to S150 and steps S211 to S217.

As shown in step S440, the actual power generated in the voltage range is calculated. Relevant detailed steps can be performed in imitation of the aforementioned step S160 and step S217.

As shown in step S450, the set electric quantity is corrected according to the difference between the actual electric quantity and the set electric quantity. Relevant detailed steps can be performed by imitating the aforementioned steps S219 and S225.

To sum up, in the embodiment of the present invention, when measuring the power of the battery, the set power of the lookup table can be corrected according to the difference between the actual power and the set power of the lookup table. Further, the remaining capacity percentage of the battery can be calculated. The embodiment of the present invention does not require the battery to undergo a complete discharge procedure, and does not require complex calculations. The power measurement method of the embodiment of the present invention also improves the existing open-circuit voltage measurement method, and does not need to wait for a recovery time of 30 minutes. In this way, the set power can be corrected according to battery characteristics, aging results or temperature effects, which can improve measurement efficiency.

Although the present invention has been disclosed above with the embodiments, it is not intended to limit the present invention, and any person of ordinary skill in the art may make some changes and modifications without departing from the spirit and scope of the present invention.

In addition, any embodiment or claims of the present invention need not achieve all the objects or advantages or features disclosed in the present invention. In addition, the abstract and titles are only used to aid in searching patent documents, and are not intended to limit the scope of the present invention.

Claims (13)

1. an electricity method for measurement for battery, including:

One inquiry table is provided, stores multiple default measurement and confirm voltage and multiple setting electricity；

Measure one first voltage of this battery as a starting point；

An end point is calculated according to this inquiry table and this starting point；

Measure the voltage and current of this battery, until default measurement that a measurement voltage reaches this end point corresponding confirms electricity Pressure；

Calculate this starting point according to this inquiry table and set electricity to the one of this end point；

Calculate this starting point to an actual electricity of this end point；And

Difference according to this actual electricity Yu this setting electricity revises this setting electricity；

Wherein this inquiry table also stores multiple current information, and " calculating this end point according to this inquiry table and this starting point " Step includes:

Measure the electric current of this battery and calculate this battery average current in a Preset Time；

Judge whether to find this average current from those current informations of this inquiry table, if "Yes", should average current by phase Default measurement confirm voltage as this end point, if "No", using interpolation method to calculate mutually should the default measurement of average current Confirm that voltage is using as this end point.

Electricity method for measurement the most according to claim 1, wherein those are preset to measure and confirm that voltage includes full voltage and cuts Only voltage.

Electricity method for measurement the most according to claim 1, wherein " is calculating this starting point according to this inquiry table to terminate to this This setting electricity of point " step, if this starting point fall a N point voltage of this inquiry table and a N+1 point voltage it Between, use interpolation method to calculate this setting electricity corresponding.

Electricity method for measurement the most according to claim 1, wherein this inquiry table also stores multiple temperature information and phase Should the information about power of each temperature information.

Electricity method for measurement the most according to claim 4, wherein " is calculating this according to this inquiry table with this starting point to terminate Point " step include:

Measure a temperature value of this battery；

Judge whether to find this temperature value from those temperature informations of this inquiry table, if "Yes", by mutually should temperature value pre- If measurement confirms that voltage, as this end point, if "No", uses interpolation method to calculate and should measure confirmation electricity by the default of temperature value mutually Pressure is using as this end point.

Electricity method for measurement the most according to claim 1, wherein this Preset Time is 5 seconds.

Electricity method for measurement the most according to claim 1, also includes:

The residual capacity percentage rate of this battery is calculated according to this setting electricity being corrected.

8. an electricity method for measurement for battery, including:

Multiple battery measurement parameters are obtained every a Preset Time；

An average current is produced according at least one battery measurement parameters of those battery measurement parameters；

This average current is utilized to calculate a setting electricity of a voltage range in an inquiry table；

Calculate at an actual electricity produced by this voltage range；And

Difference according to this actual electricity Yu this setting electricity revises this setting electricity.

Electricity method for measurement the most according to claim 8, wherein this inquiry table store multiple default average current and Information about full voltage to blanking voltage.

Electricity method for measurement the most according to claim 9, wherein " is utilizing this average current to calculate in this inquiry table This setting electricity of this voltage range " step, if this average current falls at a N voltage range and one of this inquiry table Between N+1 voltage range, interpolation method is used to calculate this setting electricity corresponding.

11. electricity method for measurement according to claim 8, wherein this inquiry table also stores multiple temperature information and phase Should the information about power of each temperature information.

12. electricity method for measurement according to claim 8, wherein this Preset Time is 5 seconds.

13. electricity method for measurement according to claim 8, also include:

The residual capacity percentage rate of this battery is calculated according to this setting electricity being corrected.