JP6991591B2 - How to predict the state of charge of the battery - Google Patents

Description

The present invention relates to a prediction method, and more particularly to a method of predicting the state of charge of a battery.

With the evolution of battery technology, many electronic devices are now equipped with batteries, and the amount of electricity stored in the batteries is used to supply the energy required to operate the electronic devices. The amount of electricity stored in the battery gradually decreases as the electronic device operates. Normally, the electronic device predicts the state of charge (SOC) of the battery so that the amount of electricity stored in the battery is not completely used and the electronic device does not stop the operation without notice. The state of charge (SOC) of a battery is also defined as the state of available electrical energy in the battery and is usually expressed as a percentage. For example, SOC = Remaining Capacity (RM) / Full Charged Capacity (FCC). By predicting the state of charge (SOC) of the battery, the user of the electronic device can perform a charging operation on the battery in advance when the amount of electricity stored in the battery is insufficient.

In the prior art, the state of charge (SOC) of the battery is often predicted by a look-up table method such as the voltage lookup method (OVC Loop Table). The table of the voltage lookup method lists the state of charge (SOC) corresponding to each voltage. Therefore, by detecting the voltage of the battery at that time, the corresponding charge state (SOC) is collated from the table of the voltage lookup method. According to the voltage lookup method, the state of charge (SOC) of the battery can be predicted quickly and easily, but the battery discharge process is caused by a large current discharge or a harsh environment (for example, a high temperature or low temperature environment). As a result, errors often occur in the prediction of the state of charge (SOC). Therefore, when the battery is discharged to the cutoff voltage, the state of charge (SOC) drops sharply to 0% and the battery discharge is stopped, and the battery-powered electronic device may suddenly stop operating. be. For example, when a battery is used in an electric vehicle, the electric vehicle may stop running without notice due to a prediction error of the state of charge (SOC), which may cause a problem in running safety.

In view of the above, the present invention provides an innovative method for predicting the state of charge of a battery. According to the above method, since the accurate state of charge (SOC) of the battery can be predicted, the situation that the electronic device using the battery as electric power stops the operation without notice is avoided. This is an object of the present invention.

The present invention makes it possible to predict the accurate charge state of the battery, thereby avoiding the situation where the charge state instantly drops to 0% when the battery is discharged and the battery discharge stops, and the battery is used as electric power. It is an object of the present invention to provide a method for predicting battery capacity, which improves the operational safety and stability of the electronic device used.

In order to achieve the above object, the present invention provides a method for predicting the state of charge of a battery. The prediction method is used for an electronic device having a battery, and includes a step of executing a procedure for adjusting the remaining capacity when the battery is discharged when the current of the battery is determined to be less than zero. As a step in performing the remaining capacity adjustment procedure when the battery is discharged, the voltage of the battery is detected, the corresponding reference charge state is searched from the lookup table based on the detected battery voltage, and the detected battery voltage is detected. The voltage difference is obtained by subtracting the voltage threshold from, the first slope is obtained by dividing the current charge state by the voltage difference, and the second slope is obtained by dividing the reference charge state by the voltage difference. Obtain the adjustment ratio by dividing the first slope by the second slope, calculate the discharge count capacity by counting the charge capacity discharged by the battery by the Coulomb counting method, and count the discharge. The adjustment value is obtained by multiplying the capacity by the adjustment ratio, the new remaining capacity is predicted by subtracting the adjustment value from the remaining capacity recorded in advance, and the new remaining capacity is divided by the full charge capacity. This predicts the state of charge of the new battery.

The embodiment of the present invention further includes a procedure for updating the full charge capacity, and as a step thereof, it is determined whether or not the detected battery voltage is below the voltage threshold, and if the battery voltage is not below the voltage threshold, it is determined. Stop the full charge capacity update procedure, continue to determine if the battery current is less than 0 if the battery voltage is below the voltage threshold, and if the battery current is less than 0 the full charge capacity The update procedure is stopped, and if the battery current is not less than 0, the execution of the full charge capacity update procedure is started. As a step to execute the procedure for updating the full charge capacity, the charge capacity charged in the battery is counted by the Coulomb counting method to calculate the charge count capacity, and the remaining capacity recorded in advance is charged. By adding the count capacity of, the remaining capacity to be newly recorded is acquired, it is judged whether or not the battery is fully charged, and if it is fully charged, the remaining capacity to be newly recorded is updated as the fully charged capacity. If the battery is not fully charged, the process returns to the step of determining whether or not the battery current is less than zero.

In the embodiment of the present invention, as a further step, it is determined whether or not the current or the average current of the battery is 0, and if the current or the average current of the battery is 0, the remaining capacity correction procedure in the static state of the battery is performed. If the current or average current of the battery is non-zero, the battery is charging or discharging. As a step to perform the remaining capacity correction procedure in the static state of the battery, the voltage of the battery is detected, and based on the detected battery voltage, the corresponding reference remaining capacity is searched from the lookup table and pre-recorded. A step to determine whether the remaining capacity is larger than the reference remaining capacity, and if the pre-recorded remaining capacity is smaller than the reference capacity, determine whether the battery current or average current is 0. If the pre-recorded remaining capacity is larger than the standard remaining capacity, the pre-recorded remaining capacity will be consumed in-house so that the newly recorded remaining capacity will be smaller than the standard remaining capacity. When the capacity deduction procedure is executed at least once and the self-consumption capacity deduction procedure is completed, the process returns to the step of determining whether the battery current or the average current is 0 or not.

In the embodiment of the present invention, further includes a step of executing a remaining capacity counting procedure at the time of charging the battery when it is determined that the current of the battery is larger than 0, and executing the remaining capacity counting procedure at the time of charging the battery. As a step to do, the charge capacity is calculated by counting the charge capacity charged in the battery by the Coulomb count method, and the charge count capacity is added to the pre-recorded remaining capacity. The remaining capacity is acquired, and the new remaining capacity is divided by the full charge capacity to predict the charge state of the new battery.

In the embodiments of the present invention, the voltage threshold is a specific voltage or discharge end voltage corresponding to a low charge state.

In the embodiment of the present invention, the look-up table is a correspondence table between the voltage of the battery and the reference charge state and the reference remaining capacity.

FIG. 1 is a diagram showing a circuit structure of an electronic device in the present invention. FIG. 2 is a flowchart of a method for predicting a state of charge of a battery in the present invention. FIG. 3 is a flowchart of the remaining capacity adjusting procedure when the battery of the present invention is discharged. FIG. 4 is a graph of the voltage and charge state of the battery in the present invention. FIG. 5 is a flowchart of the remaining capacity correction procedure in the static state of the battery of the present invention. FIG. 6 is a flowchart of updating the full charge capacity of the battery in the present invention. FIG. 7 is a diagram showing a charge state prediction curve when the battery is discharged in the present invention and a charge state prediction curve when the battery is discharged in the prior art.

FIG. 1, showing the circuit structure of the electronic device in the present invention, FIG. 2, which is a flowchart of the method for predicting the charge state of the battery in the present invention, FIG. 3, which is a flowchart of the remaining capacity adjusting procedure when the battery of the present invention is discharged, FIG. Refer to FIG. 4 which is a graph of the voltage and charge state of the battery in the present invention, and FIG. 5 which is a flowchart of the remaining capacity correction procedure in the static state of the battery of the present invention. As shown in FIG. 1, the electronic device 100 in the present invention may be an electric vehicle, a portable electronic device, or a device whose main power supply is a battery, and includes a battery 10, a processor 11, a storage unit 12, and a display. It includes a unit 13, a current detection circuit 14, and a voltage detection circuit 15. The processor 11 is connected to the battery 10, the storage unit 12, the display unit 13, the current detection circuit 14, and the voltage detection circuit 15. The storage unit 12 stores the battery capacity prediction program 120 and the look-up table 121, and records the remaining capacity of the battery (Remaining Capacity, RM) and the full charge capacity of the battery (Full Charged Capacity, FCC) as information. To. The electronic device 100 of the present invention predicts the state of charge (SOC) of the battery 10 by the battery capacity prediction program 120. The predicted charging state (SOC) is stored in the storage unit 12 and displayed on the display unit 13.

As shown in FIG. 2, the flow of the method for predicting the state of charge (SOC) of the battery in the present invention is as follows. First, in step S201, the processor 11 activates the battery capacity prediction program 120, and the current detection circuit 14 detects the current (I) of the battery 10, so that the current (I) or the average current (I _avg ) of the battery 10 is detected. Judges whether or not is 0. If the current (I) or the average current (I _avg ) of the battery 10 is not 0, the battery 10 is in a charged / discharged state. Therefore, step S203 is subsequently executed, and whether the current (I) of the battery 10 is smaller than 0. Whether or not it is determined by the processor 11. If the current (I) of the battery 10 is less than 0, the battery capacity prediction program 120 executes the remaining capacity adjusting procedure S21 when the battery is discharged. On the other hand, when the current (I) of the battery 10 is not less than 0, the battery capacity prediction program 120 executes the remaining capacity counting procedure S23 at the time of charging the battery. Then, returning to step S201, when the current (I) or the average current (I _avg ) of the battery 10 is 0, the battery 10 is in a non-charged / discharged state, so that the battery capacity prediction program 120 remains in the static state of the battery. The capacity correction procedure S25 is executed.

As shown in FIG. 3, when the battery 10 is being discharged, the battery capacity prediction program 120 executes the remaining capacity adjusting procedure S21 when the battery is discharged. First, in step S211 the processor 11 detects the voltage (V _X ) of the battery 10 by the voltage detection circuit 15, and based on the detected voltage (V _X ), the corresponding reference charge state (SOC) is obtained from the look-up table 121. Search for _ref ). In the embodiment of the present invention, the look-up table 121 is a correspondence table between the voltage of the battery and the reference charge state (SOC _ref ) and the reference remaining capacity (RM _ref ), and the reference charge state (reference charge state) corresponding to the voltage of each battery. SOC _ref ) and standard remaining capacity (RM _ref ) are listed. For example, the voltage A1 (mV) corresponds to the reference charge state B1 (%) and the reference remaining capacity C1 (mA), and the voltage A2 (mV) corresponds to the reference charge state B2 (%) and the reference remaining capacity C2 (mA). Then, ..., the voltage _AN (mV) corresponds to the reference charge state _BN (%) and the reference remaining capacity _CN (mA). In step S213, the voltage difference (V _d = V _X −V _th ) is acquired by subtracting the voltage threshold value (V _th ) from the detected voltage (V _X ). In an embodiment of the invention, the voltage threshold ( _Vth ) is a specific voltage corresponding to a low state of charge (SOC), for example, a voltage value corresponding to 0% SOC or a voltage value corresponding to 5% SOC. May be. Alternatively, in another embodiment of the present invention, the voltage threshold value ( _Vth ) may be the discharge end voltage (EDV, End of Discharge Voltage). As shown in FIG. 4, in step S215, the first slope (Slope 1) in the discharge curve 301 of the battery 10 is acquired by dividing the current state of charge (SOC _now ) by the voltage difference (V _d ). Further, the second slope (Slope 2) is acquired by dividing the reference charge state (SOC _ref ) by the voltage difference (V _d ). Then, the adjustment ratio (Adj (%)) is obtained by dividing the first slope (Slope1) by the second slope (Slope2). Subsequently, in step S217, the discharge count capacity (Count_Dsg) is calculated by counting the charge capacity discharged by the battery 10 by the Coulomb counting method. Then, the adjustment value (Adj_Value = Count_Dsg × Adj (%)) is acquired by multiplying the discharge count capacity by the adjustment ratio. After that, if the adjustment value (Adj_Value) is subtracted from the pre-recorded remaining capacity (RM _prev ), the new remaining capacity (RM _new = RM _prev -Adj_Value) is compensated. With reference to FIG. 2 again, after the execution of the remaining capacity adjusting procedure S21 at the time of discharging the battery is completed, the step S205 is executed, and the compensated remaining capacity (RM _new ) is divided by the full charge capacity (FCC). If so, a new battery charge state (SOC _new = RM _new / FCC) can be obtained.

As mentioned above, in the process of using the battery, an error is often generated in the prediction of the state of charge (SOC) due to the discharge of a large current or the harsh environment. Therefore, when the first inclination (Slope1) is larger than the second inclination (Slope2), the current charging state is higher than the actual charging state, so that the remaining capacity recorded in advance (Slope1). The large adjustment value (Adj_Value) is subtracted from RM _prev ). On the contrary, when the first inclination (Slope1) is smaller than the second inclination (Slope2), the current charging state is lower than the actual charging state, and the remaining capacity recorded in advance is recorded. A small adjustment value (Adj_Value) is subtracted from (RM _prev ). In this way, by rapidly adjusting the remaining capacity (RM) in the process of discharging the battery 10, the predicted state of charge (SOC) of the battery can be made more accurate.

Returning to step S203, when the processor 11 determines that the current (I) of the battery 10 is larger than 0, the battery capacity prediction program 120 executes the remaining capacity counting procedure S23 at the time of charging the battery. In the remaining capacity counting procedure S23 at the time of charging the battery, the charge capacity (Count_chg) of charging is calculated by counting the charge capacity charged in the battery 10 by the Coulomb counting method. Then, by adding the charge count capacity (Count_chg) to the pre-recorded remaining capacity (RM _prev ), a new remaining capacity (RM _new = RM _prev + Count_chg) can be obtained. After that, when the execution of the remaining capacity counting procedure S23 at the time of charging the battery is completed, step S205 is executed, and the new remaining capacity (RM _new ) is divided by the full charge capacity (FCC) to obtain a new battery charge state (FCC). SOC _new ) is obtained.

Next, returning to step S201, when the processor 11 determines that the current (I) or the average current (I _avg ) of the battery 10 is 0, the battery 10 is in a non-charged / discharged state, so that the battery capacity prediction program 120 executes the remaining capacity correction procedure S25 in the static state of the battery. As shown in FIG. 5, in the remaining capacity correction procedure S25 in the static state, first, in step S251, the processor 11 detects the voltage (V _X ) of the battery 10 by the voltage detection circuit 15, and the detected voltage (V _X ). ), The corresponding reference remaining capacity (RM _ref ) is searched from the look-up table 121. In step S253, the processor 11 determines whether or not the pre-recorded remaining capacity (RM _prev ) is larger than the reference remaining capacity (RM _ref ). If the pre-recorded remaining capacity (RM _rev ) is smaller than the reference remaining capacity (RM _ref ), the process returns to step S201 again without updating the remaining capacity (RM _rev ), and the current (I) of the battery 10 is reached. ) Or whether the average current (I _avg ) is 0 or not is continuously determined by the processor 11. On the contrary, if the pre-recorded remaining capacity (RM _prev ) is larger than the reference remaining capacity (RM _ref ), step S255 is executed and the pre-recorded remaining capacity (RM _prev ) is self-contained. By executing the deduction procedure of the consumption capacity (self-consumption capacity) at least once, a new remaining capacity (RM _new = RM _prev -Self_con) is acquired. After that, steps S253 and S255 are continuously executed until the new remaining capacity (RM _new ) becomes smaller than the reference remaining capacity (RM _ref ). In the present invention, the self-consumed capacity (Self_con) is a self-correcting value of the remaining capacity, and is a numerical value in a small unit such as 1 mAh or another numerical value. When the self-consumption capacity (Self_con) deduction procedure is completed and the new remaining capacity (RM _new ) becomes smaller than the reference remaining capacity (RM _ref ), the new remaining capacity (RM _new ) is recorded in the storage unit 12. Then, the process returns to step S201 again, and the processor 11 continues to determine whether or not the current (I) or the average current (I _avg ) of the battery 10 is 0. In this way, by correcting the recorded remaining capacity (RM _new ) multiple times by the self-consumed capacity (Self_con), the recorded remaining capacity (RM _new ) is adjusted to the corresponding reference remaining capacity (RM) in the look-up table 121. You can gradually get closer to _ref ). After that, when the execution of the remaining capacity correction procedure S25 in the static state is completed, step S205 is executed, and if the new remaining capacity (RM _new ) is divided by the full charge capacity (FCC), the new battery charge state (SOC _new ) is executed. ) Is obtained.

Further, in one embodiment of the present invention, as shown in FIG. 6, a procedure for updating the full charge capacity (FCC) is further included. In the procedure for updating the full charge capacity (FCC), first, in step S271, the processor 11 determines whether or not the voltage (V _X ) of the battery 10 is equal to or less than the voltage threshold (V _th ). The voltage threshold value ( _Vth ) may be the discharge end voltage (EDV). If the voltage (V _X ) is not equal to or less than the voltage threshold (V _th ), step S272 is executed, the full charge update flag (FCC_Update_Flag) is set to 0, and the full charge capacity (FCC) update is stopped. On the contrary, when the voltage (V _X ) is equal to or less than the voltage threshold (V _th ), step S273 is continuously executed to determine whether or not the current (I) of the battery 10 is smaller than 0. If the current (I) of the battery 10 is less than 0, the process returns to step S272 and the update of the full charge capacity (FCC) is stopped. On the contrary, when the current (I) of the battery 10 is not smaller than 0, the full charge update flag (FCC_Update_Flag) is set to 1, and the execution of the full charge capacity (FCC) update procedure S28 is started. In the full charge capacity (FCC) update procedure S28, in step S281, the charge capacity (Count_chg) is calculated by counting the charge capacity charged in the battery 10 by the Coulomb counting method. Then, a new remaining capacity (RM _new = RM _prev + Count_chg) is acquired by adding the charge count capacity (Count_chg) to the previously recorded remaining capacity (RM _prev ). Subsequently, in step S282, it is determined whether or not the battery 10 is fully charged. When the battery 10 is in a fully charged state, step S283 is executed, and the new remaining capacity (RM _new ) is updated as a new fully charged capacity (FCC _new = RM _new ). On the contrary, if the battery 10 is not fully charged, the process returns to step S273, determines whether the current (I) of the battery 10 is smaller than 0, and continues the full charge capacity (FCC) update procedure S28. Decide whether or not. By updating the full charge capacity (FCC) in this way, it becomes possible to predict the state of charge (SOC) of the battery more accurately.

FIG. 7 shows a charge state prediction curve when the battery is discharged in the present invention and a charge state prediction curve when the battery is discharged in the prior art. As shown in FIG. 7, in the conventional technique, the state of charge (SOC) at the time of discharging the battery is predicted only by the voltage lookup method, and the prediction result in that case is as shown in the curve 303. The curve 303 is a linear curve. Further, when the charge state (SOC) at the time of discharging the battery is predicted only by the voltage lookup method, an error is likely to occur in the prediction of the charge state (SOC) due to the discharge of a large current or harsh environmental conditions. .. If the amount of electricity in the battery is overestimated and its state of charge (SOC) is at a low level, the state of charge (SOC) may drop sharply to 0% if discharging is continued. For example, in curve 303, if the amount of electricity in the battery is overestimated and is in a low state of charge (SOC) of 10%, the state of charge (SOC) of the battery goes from 10% to 0% as the battery continues to discharge. As a result of the sudden drop, battery-powered electronic devices stop operating without notice.

In the present invention, the battery capacity prediction program 120 predicts the state of charge (SOC) when the battery is discharged. The prediction result in this case is as shown in the curve 305. Further, the curve 305 has a parabolic shape. Taking FIG. 7 as an example, the battery capacity prediction program 120 in the present invention adjusts an inaccurate remaining capacity (RM) and charge state (SOC). When the charge state (SOC) of the battery 10 is discharged to 40% or less, the charge state (SOC) on the curve 305 is clearly adjusted as compared to the charge state (SOC) on the linear curve 303. As described above, in the present invention, the state of charge (SOC) of the battery is quickly adjusted by the battery capacity prediction program 120. Therefore, even if the battery 10 is in a low charge state (SOC) and continues to be discharged, the charge state (SOC) of the battery does not suddenly drop to 0%. For example, since the state of charge (SOC) of the battery 10 does not suddenly drop from 10% to 0% in the discharging process, the operational safety and stability of the electronic device using the battery 10 as electric power are improved. improves.

The above is merely a preferred embodiment of the present invention and does not limit the scope of implementation of the present invention. That is, the equivalent modifications and supplements made based on the shapes, structures, features and spirits described in the claims of the present invention are all included in the claims of the present invention.

100 Electronic equipment 10 Battery 11 Processor 12 Storage unit 120 Battery capacity prediction program 121 Look-up table 13 Display unit 14 Current detection circuit 15 Voltage detection circuit 301 Curve 303 Curve 305 Curve

Claims (6)

A method for predicting the state of charge of a battery used in an electronic device having a battery.
If it is determined that the current of the battery is less than 0, the step including executing the step of adjusting the remaining capacity at the time of discharging the battery is included.
As a step of executing the remaining capacity adjustment procedure when the battery is discharged,
Detecting the voltage of the battery,
Based on the detected voltage of the battery, the look-up table is searched for the corresponding reference charge state.
The voltage difference is obtained by subtracting the voltage threshold value from the detected voltage of the battery.
The first slope is obtained by dividing the current state of charge by the voltage difference.
The second slope is obtained by dividing the reference charge state by the voltage difference.
The adjustment ratio is obtained by dividing the first slope by the second slope.
The discharge count capacity is calculated by counting the charge capacity discharged by the battery by the Coulomb counting method.
The adjustment value is obtained by multiplying the discharge count capacity by the adjustment ratio.
A new remaining capacity is predicted by subtracting the adjustment value from the remaining capacity recorded in advance.
A method of predicting the state of charge of a new battery by dividing the new remaining capacity by the full charge capacity. Further, as a step of the procedure for updating the full charge capacity, including the procedure for updating the full charge capacity,
It is determined whether or not the detected voltage of the battery is equal to or less than the voltage threshold value.
If the voltage of the battery is not equal to or less than the voltage threshold, the procedure for updating the full charge capacity is stopped, and if the voltage of the battery is equal to or less than the voltage threshold, whether or not the current of the battery is smaller than 0 is continued. Judge,
If the current of the battery is less than 0, the procedure for updating the full charge capacity is stopped, and if the current of the battery is not less than 0, the execution of the procedure for updating the full charge capacity is started.
As a step of executing the procedure for updating the full charge capacity,
The charge capacity is calculated by counting the charge capacity charged in the battery by the Coulomb counting method, and the charge count capacity is added to the pre-recorded remaining capacity. By doing so, you can get the remaining capacity to be newly recorded.
It is determined whether or not the battery is in a fully charged state, and if it is in a fully charged state, the newly recorded remaining capacity is updated as the fully charged capacity, and if it is not in a fully charged state, the current of the battery is 0. The method for predicting the state of charge of a battery according to claim 1, which returns to the step of determining whether or not the battery is smaller. As a further step
Judging whether or not the current or average current of the battery is 0,
When the current or the average current of the battery is 0, the remaining capacity correction procedure in the static state of the battery is executed, and when the current of the battery or the average current is not 0, the battery is charged or discharged. ,
As a step of executing the remaining capacity correction procedure in the static state of the battery,
Detecting the voltage of the battery,
Based on the detected voltage of the battery, the corresponding reference remaining capacity is searched from the look-up table.
It is determined whether or not the pre-recorded remaining capacity is larger than the reference remaining capacity, and if the pre-recorded remaining capacity is smaller than the reference remaining capacity, the battery is used. Returning to the step of determining whether the current or the average current is 0, if the pre-recorded remaining capacity is larger than the reference remaining capacity, the new remaining capacity is larger than the reference remaining capacity. When the self-consumption capacity deduction procedure is executed by repeating the update of the new remaining capacity by subtracting the self-consumption capacity from the pre-recorded remaining capacity until the value becomes smaller, and the self-consumption capacity deduction procedure is completed. The method for predicting the state of charge of the battery according to claim 1, wherein the process returns to the step of determining whether or not the current or the average current of the battery is 0.
In addition,
If it is determined that the current of the battery is greater than 0, it includes a step of performing a remaining capacity counting procedure when charging the battery.
As a step of executing the remaining capacity counting procedure at the time of charging the battery,
The charge capacity is calculated by counting the charge capacity charged in the battery by the Coulomb counting method.
The new remaining capacity is obtained by adding the charge count capacity to the previously recorded remaining capacity.
The method for predicting a battery charge state according to claim 1, wherein the new remaining capacity is divided by the full charge capacity to predict the charge state of the new battery. The method for predicting the state of charge of a battery according to claim 1, wherein the voltage threshold is a voltage corresponding to a low charge state or a discharge end voltage. The method for predicting a battery charge state according to claim 3, wherein the look-up table is a correspondence table between the voltage of the battery, the reference charge state, and the reference remaining capacity.

Images