JP6485329B2 - Method for detecting state of liquid lead battery and method for controlling charging of liquid lead battery - Google Patents

Description

  The present invention relates to a liquid lead battery, and more particularly to state detection or charge control.

  Since the characteristics of the lead battery change depending on the state, it is useful to detect the state in order to perform accurate control. For example, in Patent Document 1, in a method for charging a lead-acid battery, a charging current is cut at a predetermined interval during charging for a predetermined time, and a voltage between a voltage immediately before the charging current is cut off and a voltage at the time when the predetermined time has elapsed. It is described that the difference is measured and the charge mode is switched based on the time when the voltage difference starts to increase.

JP-A-11-176482

  However, the conventional technique has a problem that the influence of errors due to disturbance is large.

  For example, in the technique of Patent Document 1, in order to take the difference between the battery voltage at energization and the battery voltage at rest, the charging current fluctuates due to disturbance such as fluctuation of the primary voltage, May be erroneously detected.

  The present invention has been made in order to solve such problems, and when detecting the state of the liquid lead battery or controlling the charging of the liquid lead battery, the effect of the error due to the disturbance is eliminated. An object is to provide a method of reducing.

In order to solve the above-mentioned problem, the method according to the present invention is a method for detecting the state of a liquid lead battery, in which a pause period for pausing constant current charging is provided at a constant period,
-Identifying a first time point at which a first time has passed since the start of the pause;
-Identifying a second time point at which a second time has elapsed since the start of the pause;
-Acquiring a voltage decrease amount from the first time point to the second time point;
And a step of detecting that the charging rate of the liquid lead battery has reached 100% in response to the tendency of the change in the acquired value acquired during the rest period.

  According to such a configuration, the state of the liquid lead battery is detected based on the amount of voltage decrease after a while after charging is suspended.

  The length of the rest period may be equal to the second time.

Further, the method according to the present invention is a method for detecting the state of the liquid lead battery, in which a pause section for pausing constant current charging is provided at a constant period, and in each of the pause sections,
-Identifying a first time point at which a first time has passed since the start of the pause;
-Identifying a second time point at which the voltage has dropped by a first voltage difference from the first time point;
-Obtaining the elapsed time from the first time point to the second time point;
And a step of detecting that the charging rate of the liquid lead battery has reached 100% in response to the tendency of the change in the acquired value acquired during the rest period.

  Even with such a configuration, the state of the liquid lead battery is detected based on the amount of voltage decrease after a while after charging is suspended.

  Further, the method according to the present invention is a method for controlling the charging of the liquid lead battery, and the amount of charging current is determined based on the step of detecting the state of the liquid lead battery and the state of the liquid lead battery. Determining the step.

The change may be detected in response to the fact that the maximum value of the voltage decrease amount or the minimum value of the elapsed time is not updated in a predetermined number of consecutive pause intervals.
The change is that the voltage decrease amount in the last pause interval is smaller than the voltage decrease amount in the previous pause interval, or the elapsed time in the last pause interval is longer than the elapsed time in the immediately previous pause interval. It may be detected accordingly.
The change may be detected using the least square method based on the voltage decrease amount or the elapsed time in each pause period.
You may further provide the process of acquiring the liquid temperature of a liquid lead battery, and the process of determining 2nd time or a 1st voltage difference based on liquid temperature.

  According to the method of the present invention, a region where the error due to the disturbance immediately after the start of the charging suspension section is excluded is excluded, and the state is detected based on a change after a certain amount of time has elapsed, thereby reducing the influence of the error due to the disturbance can do.

It is a graph which shows the change of the voltage by control concerning Embodiment 1 of the present invention. 6 is a graph for explaining a method of acquiring a voltage decrease amount according to the first embodiment. 6 is a graph illustrating a third time point detection method according to the first embodiment. 10 is a graph for explaining an elapsed time acquisition method according to the second embodiment. 10 is a graph illustrating a method for determining a first time according to the third embodiment. 10 is a graph illustrating an effect according to the fourth embodiment.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1 FIG.
The present invention relates to a method for detecting the state of a lead battery. The “lead battery state” is represented by, for example, a charging rate, but may be represented by another physical quantity or a combination thereof, and may be represented by, for example, an integrated current amount from the charging start time. The present invention also relates to a method for controlling charging of a lead battery based on the state of the lead battery.

  The lead battery according to the present invention is of a liquid type and is mounted on a vehicle, for example. A control device that controls charge / discharge operation of the lead battery is connected to the lead battery. The control device is constituted by a computer, for example, and includes a calculation means such as a microprocessor and a storage means such as a semiconductor memory. The control device executes the method (or each step thereof) according to the present invention by executing a program stored in the storage means.

  The control device controls a current value related to charging the lead battery. The control device can measure, calculate, or obtain time and the voltage between terminals of the lead battery. Further, the control device may be capable of measuring, calculating, or obtaining the charge rate of the lead battery, the charge / discharge power of the lead battery, the charge / discharge amount of the lead battery, the charge rate of the lead battery, and the like. For the measurement or acquisition of these values, suitable sensors may be provided in connection with the control device. In the present specification, “charge amount” may mean the amount of power related to charging, and “discharge amount” may mean the amount of power related to discharge.

  FIG. 1 is a graph showing a change in voltage by control according to Embodiment 1 of the present invention. Although this graph uses a curve and is represented so that the voltage value changes continuously, in practice, the voltage acquisition may be performed discretely, in which case the graph of FIG. Alternatively, it may be expressed by a discrete plot. The same applies to the graphs of FIGS.

  The control in FIG. 1 represents a charging operation by a constant current method. In this figure, an example of the charging operation at the current value I1 is shown. A charging operation not based on the constant current method may be performed before or after the time period shown in FIG. The charging operation not based on the constant current method may be, for example, a charging operation by constant voltage charging, constant power charging, or semi-constant voltage charging.

  In the charging operation, the control device provides a pause section in which constant current charging is paused. FIG. 1 shows pause intervals Int1 and Int2. The rest period is provided at a constant period. In this embodiment, this period is Tx [s]. In each of the pause periods, the control device pauses charging for a predetermined pause time (that is, the charging current is set to 0).

  The period Tx is, for example, 120 seconds, but an appropriate value may be set between 1 minute and 5 minutes according to the control characteristics of the control device. In addition, the pause time (that is, the length of the pause interval) intx [s] is constant, for example, 4 seconds, but this is also appropriate between 1 second and 10 seconds depending on the control characteristics of the control device. A value should be set.

  Since the charging operation is suspended in each suspension period, the voltage of the lead battery (for example, the voltage between terminals) decreases with time. The control device acquires, for each pause interval, a voltage decrease amount during a certain time that occupies a part of the pause interval.

  FIG. 2 is a graph illustrating a method for acquiring the voltage decrease amount. In this graph, the start point (pause start time) of the pause section is time t0, and the end point (pause end time) of the pause section is time t2. The control device first specifies a time t1 (first time) at which a predetermined time TA [s] (first time) has elapsed from time t0 in each of the pause periods, and acquires a voltage VA [V] at time t1. .

  Next, the control device specifies a time t2 (second time point) at which a predetermined time TB [s] (second time) has elapsed from time t0, and acquires a voltage VB [V] at the time t2. Then, the control device acquires a voltage decrease amount ΔV [V] from time t1 to time t2. For example, the voltage decrease amount ΔV is calculated as a voltage difference by subtracting the voltage at time t2 from the voltage at time t1, and in this case, ΔV = VA−VB [V]. An absolute value may be taken and defined as ΔV = | VA−VB |. In the present embodiment, the length of time TB is fixed.

  In the example of FIG. 2, the time TB is measured with the time t0 as a reference. However, in the present embodiment, the time TA is a constant, and therefore it is equivalent to define the second time with the time t1 as a reference. (In that case, first, the time t1 when the time TA (first time) has elapsed from the time t0 is defined as the first time point, and further, the time t2 when the fixed time TB-TA has elapsed from the time t1 is defined as the second time point. May be.)

  In this way, the control device acquires the voltage decrease amount ΔV for each of the pause periods. Then, the control device detects a time point (third time point) at which the voltage decrease amount ΔV starts to decrease from an increase based on the voltage decrease amount ΔV acquired for each pause period.

  FIG. 3 is a graph for explaining a detection method at the third time point. As the charging operation proceeds, the charging rate increases to 100%, and when the charging operation further proceeds, the charging rate exceeds 100%. In FIG. 3, the time t3 corresponds to the third time point (that is, the voltage decrease amount ΔV changes from increasing to decreasing at the time t3). Although the actual graph includes a portion corresponding to the pause period, FIG. 3 shows that the charge proceeds continuously ignoring the pause period for convenience of explanation.

  In the example of FIG. 3, the horizontal axis is the charging rate [%], and the time t3 and the amount of integrated current (described later) are shown with the horizontal axis as a reference. Since the quantities correspond one-to-one with each other, they can be converted to each other. In addition, the third time point is detected in relation to one of the pause intervals, and the strict temporal relationship between the pause interval and the third time point is not essential, but if necessary, The trader can make an appropriate decision.

  Time t3 is a point in time at which the voltage decrease amount ΔV related to the plurality of pause intervals has changed from increasing to decreasing with the passage of time or in time order of the pause intervals. That is, the voltage decrease amount ΔV related to the next pause interval becomes larger than the voltage decrease amount ΔV related to the first pause interval. The point at which begins to decrease appears. Time t3 corresponds to the pause interval at such time.

  Although the time t3 may be detected in any way, for example, it can be detected as follows. The control device determines whether or not the maximum value of the voltage decrease amount ΔV has been updated for each pause period after the start of charging. If the maximum value of the voltage decrease amount ΔV is not updated after a predetermined number of times, it is determined that the voltage decrease amount ΔV has changed from increasing to decreasing. This point in time (that is, the point in time related to the pause period in which it is determined that the voltage decrease amount ΔV has changed from increasing to decreasing) is time t3.

  In this example, it can be said that the change in the voltage decrease amount ΔV from the increase to the decrease is detected in response to the fact that the maximum value of the voltage decrease amount ΔV is not updated in a predetermined number of consecutive pause intervals. For example, the number of consecutive pause intervals serving as a determination criterion is five. In this case, the voltage decrease amount ΔV reaches a peak in the pause interval Int (N), and then the voltage decrease amounts ΔV acquired in five consecutive pause intervals Int (N + 1) to Int (N + 5) are all paused. If the voltage decrease amount ΔV in the section Int (N) is equal to or less than the voltage decrease amount ΔV, it is determined that the voltage decrease amount ΔV has changed from increase to decrease in the pause section Int (N + 5). Will be detected. It should be noted that the number of consecutive pause intervals as a criterion may be another value.

  Next, the control device detects the state of the lead battery in response to the voltage decrease amount ΔV changing from increasing to decreasing. For example, as shown in FIG. 3, it is detected that the charging rate of the lead battery has reached 100% in response to the voltage decrease amount ΔV changing from increasing to decreasing.

  The time when the voltage decrease amount ΔV starts to decrease and the time when the charging rate reaches 100% coincide with each other with high accuracy. Therefore, if it is detected that the voltage decrease amount ΔV reaches the peak from the increase and starts to decrease, it can be determined that the charging rate is 100% with high accuracy.

  Here, the voltage between the terminals during charging of the lead battery may include an error due to a disturbance (a fluctuation in the primary side voltage or the like). This disturbance does not always become zero immediately after charging is stopped, and a certain amount of error may remain immediately after the start of the pause period. Therefore, according to the method according to the first embodiment of the present invention, a region having a large error due to disturbance immediately after the start of the charging suspension period is excluded, and the state is detected based on a change after a certain amount of time TA has elapsed. Therefore, the influence of the error due to the disturbance can be reduced, and the state of the lead battery can be detected more accurately. In particular, by using the voltage difference between the two time points during the pause instead of the voltage difference between the one point during the energization and the one time during the pause, the influence of the fluctuation of the charging current and the like is suppressed and the detection is accurately performed. be able to.

  Thereafter, in the present embodiment, charging is controlled based on the detected state. In particular, in this embodiment, charging is controlled by determining the amount of charging current after time t3. The amount of charging current after time t3 can be determined, for example, as follows.

  As shown in FIG. 3, the control device acquires and stores the accumulated charging current amount AX [Ah] from the charging start time to time t3. Based on this value, an integrated charge current amount AY [Ah] to be charged after time t3 is determined. The relationship between AY and AX can be appropriately determined by those skilled in the art. For example, AY can be calculated as a linear function of AX, and in particular, can be calculated as a value proportional to AX.

  As a specific example, when the target charging rate is K [%], AY = AX × (K−100) / 100 [Ah] may be used. For example, when AX = 100 [Ah] and K = 115 [%], charging ends when the accumulated charge current amount of AY = 15 [Ah] is charged after time t3.

  According to the method according to the first embodiment of the present invention, as described above, the region where the error due to the disturbance immediately after the start of the charging suspension period is excluded is excluded, and the state is changed based on the change after a certain amount of time TA has passed. Since it detects, the influence of the error by disturbance can be reduced and more exact charge control can be implement | achieved.

In the first embodiment, the following modifications can be made.
Specific values of the time TA (first time) and the time TB (second time) can be appropriately determined by those skilled in the art based on experiments and the like. In particular, an error due to a disturbance appearing in the voltage may be reduced as the time TA becomes longer, and the time efficiency of the charging operation may be improved as the time TB becomes shorter. On the other hand, when the time TA is long and the time TB is short, the measurement accuracy of the voltage decrease amount ΔV may be lowered. However, those skilled in the art can appropriately design these balances.

  In the first embodiment, the second time point when the time TB has elapsed from the suspension start time point coincides with the suspension end time point, but these may be different time points. That is, it may be designed such that TB <intx. In this case, even after the second time point has elapsed and the voltage decrease amount ΔV has been calculated, the pause period continues further. In this way, the time TB that is a parameter for detecting the state of the lead battery and the pause time intx that is a control parameter for the charging operation can be designed independently, and finer control is possible.

  In this case, it is preferable that the length of the time TB is determined so that an error depending on various conditions is reduced. For example, when the voltage decrease amount ΔV is expected to vary depending on the liquid temperature of the lead battery, the time TB may be determined to a value that minimizes the influence of the change in the liquid temperature. Such a determination method can be implemented, for example, by experiments.

  In the first embodiment, the detected state (for example, the state where the charging rate is 100%) is used for determination of the amount of charging current. However, if charging control is used, it is used for processing other than determination of the amount of charging current. Also good. The detected state can also be used for purposes other than charging control. For example, the value of the charging rate has a wide range of uses in the control related to the lead battery in addition to the direct control of the charging operation, and those skilled in the art can appropriately determine the use.

  In the first embodiment, the fact that the voltage decrease amount ΔV has started to decrease is detected in response to the maximum value of the voltage decrease amount ΔV not being updated a predetermined number of times. As a modification, the fact that the voltage decrease amount ΔV has changed from increasing to decreasing may be detected in response to the voltage decreasing amount ΔV decreasing once. That is, the fact that the voltage decrease amount ΔV has changed from increasing to decreasing may be detected in response to the voltage decrease amount ΔV in the last pause interval being smaller than the voltage decrease amount ΔV in the immediately preceding pause interval.

  Further, the fact that the voltage decrease amount ΔV has changed from increasing to decreasing may be detected based on the slope when the voltage decreasing amount ΔV is expressed as a function of the charging rate (for example, the graph of FIG. 3). For example, it may be detected that the voltage decrease amount ΔV has changed from an increase to a decrease in response to the inclination changing from positive to zero. Alternatively, it may be detected that the voltage decrease amount ΔV has changed from an increase to a decrease in response to the inclination changing from positive to negative or from 0 to negative.

  For the inclination, for example, a difference, a derivative, a differential coefficient, or the like can be used, and a person skilled in the art can appropriately design a calculation method. The slope may be calculated using a least square method. In this case, it can be said that the change in the voltage decrease amount ΔV from the increase to the decrease is detected using the least square method based on the voltage decrease amount ΔV in each pause period. Further, a method for calculating the slope of the voltage decrease amount ΔV using the least square method (for example, the number of data) can be appropriately designed by those skilled in the art. As a specific example, the voltage decrease amount ΔV related to the latest four rest periods is used. May be used.

Embodiment 2. FIG.
In the first embodiment, the second time point is specified based on a certain elapsed time. In the second embodiment, the second time point is specified based on a constant voltage change. Hereinafter, differences from the first embodiment will be described.

  In the second embodiment, the control device acquires the elapsed time required for the voltage to decrease by a certain value in a part of each pause period. FIG. 4 is a graph for explaining a method of acquiring this elapsed time. In this graph, the start point (pause start time) of the pause section is time t4, and the end point (pause end time) of the pause section is time t7. As in the first embodiment, the control device first identifies a time t5 (first time point) at which a predetermined time TA [s] (first time) has elapsed from time t4 in each of the pause intervals, and at time t5. The voltage VC [V] is acquired.

  Next, the control device specifies time t6 (second time point) at which the voltage decreases by a constant voltage difference VD [V] (first voltage difference) from time t5 to VE [V] (that is, VE = VC-VD or VE = | VC-VD |). Then, the control device acquires an elapsed time ΔT [s] from time t5 to time t6. For example, it is calculated as ΔT = t6−t5 [s].

  The magnitude of the voltage difference VD can be appropriately designed by those skilled in the art, but it is preferable that the voltage difference VD is determined so that an error depending on various conditions is reduced. For example, when the elapsed time ΔT is expected to vary depending on the liquid temperature of the lead battery, the voltage difference VD may be determined so that the influence of the change in the liquid temperature is minimized. Such a determination method can be implemented, for example, by experiments.

  In this way, the control device acquires the elapsed time ΔT for each of the pause sections. Then, the control device detects the time point (third time point) at which the elapsed time ΔT has started to increase from the decrease based on the elapsed time ΔT acquired for each pause interval. Note that the third time point is detected in relation to one of the pause intervals, and the exact temporal relationship between the pause interval and the third time point is not essential, but if necessary, The trader can decide as appropriate.

  The time t8 (the time corresponding to the time t3 in FIG. 3; not particularly shown), which is the time when the elapsed time ΔT has started to increase, may be detected in any way. In the modification, it can be detected by a method similar to the method of detecting the time t3 when the voltage decrease amount ΔV has changed from increasing to decreasing.

  The time t8 can be detected as follows, for example. The control device determines whether or not the minimum value of the elapsed time ΔT has been updated for each pause interval after the start of charging. Then, if the minimum value of the elapsed time ΔT is not updated beyond a certain number of times, it is determined that the elapsed time ΔT has started to increase from a decrease. This time point (that is, the time point relating to the pause period in which the elapsed time ΔT is determined to have changed from a decrease to an increase) is time t8. In this example, it can be said that the change of the elapsed time ΔT from the decrease to the increase is detected in response to the minimum value of the elapsed time ΔT not being updated in a predetermined number of consecutive pause intervals.

  Next, the control device detects the state of the lead battery in response to the elapsed time ΔT changing from decreasing to increasing. For example, it detects that the charging rate of the lead battery has reached 100% in response to the elapsed time ΔT changing from decreasing to increasing.

  The time when the elapsed time ΔT starts to increase from the decrease coincides with the time when the charging rate reaches 100% with high accuracy. Therefore, if it is detected that the elapsed time ΔT has reached the minimum value from the decrease and started to increase, it can be determined that the charging rate has become 100% with high accuracy.

  As described above, according to the method according to the second embodiment of the present invention, as in the first embodiment, a region having a large error due to disturbance immediately after the start of the charging suspension period is excluded, and a certain time TA has elapsed. Since the state is detected based on the change from, the influence of the error due to the disturbance can be reduced, and the state of the lead battery can be detected more accurately.

  In the second embodiment, similarly to the first embodiment, the charging can be controlled based on the detected state. For example, charging is controlled by determining the amount of charging current after time t8. The amount of charging current after time t8 can be determined in the same manner as the amount of charging current after time t3 in the first embodiment.

  According to the method according to the second embodiment of the present invention, as in the first embodiment, the region having a large error due to the disturbance immediately after the start of the charging suspension period is excluded, and the change after a certain time TA has elapsed. Since the state is detected based on this, it is possible to reduce the influence of an error due to disturbance and to realize more accurate charge control.

  In the above-described second embodiment, the same modification as in the first embodiment can be performed. For example, specific values of the time TA (first time) and the voltage difference VD (first voltage difference) can be appropriately determined by those skilled in the art based on experiments and the like.

  In the second embodiment, the detected state (for example, the state where the charging rate is 100%) is used for determination of the amount of charging current. However, if charging control is used, it is used for processing other than determination of the amount of charging current. Also good. The detected state can also be used for purposes other than charging control.

  The change in the elapsed time ΔT from the decrease to the increase may be detected in response to the increase in the elapsed time ΔT once. That is, the fact that the elapsed time ΔT has changed from decreasing to increasing may be detected in response to the elapsed time ΔT in the last pause interval being longer than the elapsed time ΔT in the immediately preceding pause interval.

  Further, the fact that the elapsed time ΔT has changed from a decrease to an increase may be detected based on a slope when the elapsed time ΔT is expressed as a function of the charging rate. For example, it may be detected that the elapsed time ΔT has changed from a decrease to an increase in response to the slope changing from negative to zero. Alternatively, it may be detected that the elapsed time ΔT has changed from a decrease to an increase in response to the slope changing from negative to positive or from 0 to positive.

  For the inclination, for example, a difference, a derivative, a differential coefficient, or the like can be used, and a person skilled in the art can appropriately design a calculation method. The slope may be calculated using a least square method. In this case, it can be said that the change in the elapsed time ΔT from the decrease to the increase is detected using the least square method based on the elapsed time ΔT in each pause interval. Further, a method for calculating the slope of the elapsed time ΔT using the least square method (for example, the number of data) can be designed as appropriate by those skilled in the art. For example, the elapsed time ΔT related to the latest four pause intervals may be used. Good.

Embodiment 3 FIG.
In the first and second embodiments and the modifications thereof, the fixed time TA (first time) serving as a reference for specifying the time t1 and the time t5 (both are the first time points) is always fixed. However, the time TA may be variable. For example, it may be changed or determined for each charging process so as to be constant for one charging process, or may be changed or changed during one charging process.

  The standard for calculating or determining the time TA can be appropriately designed by those skilled in the art. In the third embodiment, measurement data relating to charging current is used as a specific example of such a reference. Hereinafter, differences from the first and second embodiments will be described.

  FIG. 5 is a graph illustrating a method for determining time TA (first time) according to the third embodiment. In the third embodiment, the control device has a function of acquiring a cycle of noise appearing in the charging current. Such a function can be realized using a known sensor or the like. In the example of FIG. 5, noise having a period P is generated in the charging current in the constant current charging.

  The control device calculates or determines the time TA based on the charging current cycle P. In this embodiment, it is determined that TA> P. Such a determination method can be appropriately designed by those skilled in the art. For example, P may be multiplied by a constant CP larger than 1 and calculated as TA = P × CP.

  According to the method according to the third embodiment of the present invention, as in the first and second embodiments, it is possible to reduce the influence of errors due to disturbance and to detect the state of the lead battery more accurately. Moreover, charge control can be performed based on the detected state.

  Furthermore, according to the method according to the third embodiment, the time TA can be determined to be a reasonably long value with respect to the charge current noise period P, so that voltage fluctuation due to noise affects the voltage decrease amount ΔV or the elapsed time ΔT. The error can be efficiently reduced, and more accurate detection can be performed. For example, when the period P is short, the influence of noise is reduced at an early stage, so that the measurement start can be accelerated by increasing the measurement start time of the voltage decrease amount ΔV or the elapsed time ΔT, thereby improving the measurement accuracy. On the other hand, when the period P is long, the measurement accuracy can be improved by delaying the measurement start of the voltage decrease amount ΔV or the elapsed time ΔT and waiting until the influence of noise is sufficiently reduced.

  In the third embodiment, the frequency of changing the time TA can be designed as appropriate. If the period P of the charging current noise is known, the time TA may be a fixed value. The time TA may be determined for each charging process. In this case, as the period P used as a reference for determination, a value acquired in the immediately preceding charging process may be used, or a value acquired after the start of charging may be used. Moreover, you may change in the middle of a charging process, and in that case, you may change for every rest area. In the case of changing in the middle of the charging process, it is possible to appropriately design which time period P is used as a reference.

  In Embodiment 3 described above, the time TA is calculated or determined based on the period P of the noise that appears in the charging current. However, as a modification, the time TA is calculated or determined based on the amplitude of the noise that appears in the charging current. May be. For example, the time TA may be calculated by multiplying the amplitude by a constant determined in advance. Further, the time TA may be calculated or determined based on both the period and the amplitude.

Embodiment 4 FIG.
In the first embodiment and its modifications (including the third embodiment), the fixed time TB (second time) that serves as a reference for specifying the time t2 (second time point) is always fixed. In the second embodiment and its modifications (including the third embodiment), the constant voltage difference VD (first voltage difference) serving as a reference for specifying the time t6 (second time point) is always fixed. Yes. However, these values may be variable. For example, it may be changed or determined for each charging process so as to be constant for one charging process, or may be changed or changed during one charging process.

  In Embodiment 1 and its modifications (including Embodiment 3), the standard for calculating or determining the time TB can be appropriately designed by those skilled in the art. Further, in the second embodiment and its modified examples (including the third embodiment), a standard for calculating or determining the voltage difference VD can be appropriately designed by those skilled in the art. Embodiment 4 uses the liquid temperature of a lead battery as a specific example of such a reference. Hereinafter, differences from the first to third embodiments will be described.

  In the fourth embodiment, the control device has a function of acquiring the liquid temperature of the lead battery. Such a function can be realized using a known temperature sensor or the like. The control device first acquires the liquid temperature of the lead battery, and determines the time TB or the voltage difference VD based on the acquired liquid temperature.

  FIG. 6 is a graph for explaining the effect according to the fourth embodiment. This figure corresponds to the first embodiment and shows the effect when the time TB is variable. Graphs G1 to G4 of the voltage decrease amount ΔV corresponding to the four conditions are shown. Graphs G1 and G2 are examples when the liquid temperature of the lead battery is relatively low, and graphs G3 and G4 are examples when the liquid temperature of the lead battery is relatively high. In each liquid temperature, graphs G2 and G4 are examples when time TB is a certain value TB = bL, and graphs G1 and G3 are examples when TB = bH (where bL ≠ bH). . In this example, an example of an appropriate value for a relatively low liquid temperature is bL, and an example of an appropriate value for a relatively high liquid temperature is bH.

  The horizontal axis represents the charging rate, and the point at which the charging rate is 100% is indicated by a broken line. In the first embodiment, it is considered that the peak of the voltage decrease amount ΔV corresponds to the charging rate of 100%. However, an error may actually occur according to the liquid temperature. For example, when the liquid temperature is low, when the voltage decrease amount ΔV is acquired with TB = bL (graph G2) than when the voltage decrease amount ΔV is acquired with TB = bH (graph G1), the voltage decrease is greater. The peak of the amount ΔV approaches the time point when the charging rate is 100% (arrow L). That is, it is possible to detect a state where the charging rate is 100% more accurately.

  Further, when the liquid temperature is high, the voltage decrease is more when the voltage decrease amount ΔV is acquired with TB = bH (graph G3) than when the voltage decrease amount ΔV is acquired with TB = bL (graph G4). The peak of the amount ΔV approaches the time point when the charging rate is 100% (arrow H). That is, it is possible to detect a state where the charging rate is 100% more accurately.

  A person skilled in the art can appropriately design a method for calculating or determining the time TB based on the liquid temperature. For example, the control device may store in advance values of the time TB corresponding to various values (or various ranges) of the liquid temperature. Alternatively, the value of time TB may be calculated as a function of the liquid temperature.

  The above is a description of the case where the time TB is variable in the first embodiment. However, the same configuration can be obtained when the voltage difference VD is variable in the second embodiment, and the same effect can be obtained.

  As described above, according to the method according to the fourth embodiment of the present invention, as in the first and second embodiments, it is possible to reduce the influence of the error due to the disturbance and to detect the state of the lead battery more accurately. . Moreover, charge control can be performed based on the detected state.

  Further, according to the fourth embodiment, time TB or voltage difference VD can be appropriately determined according to the liquid temperature, so that the evaluation of the state (for example, the detection of the state where the charging rate becomes 100%) is further performed. Can be done accurately.

  AX, AY Integrated charge current, Int1, Int2 pause period, intx pause time (length of pause period), t0 time (rest start time), t1, t5 time (first time), t2, t6 time (second Time), TA time (first time), TB time (second time), Tx constant period, VD voltage difference (first voltage difference), ΔT elapsed time, ΔV voltage decrease amount.

Claims (12)

A method of detecting the state of a liquid lead battery,
In each of the pause intervals, a pause interval in which constant current charging is paused is provided at a fixed period.
-Identifying a first time point at which a first time has passed since the start of the pause;
-Identifying a second time point at which a second time has elapsed since the start of the pause;
-Acquiring a voltage decrease amount from the first time point to the second time point;
A step of executing
Detecting that the charge rate of the liquid lead battery has reached 100% in response to a change in the trend of the acquired value acquired during the pause period.   The method of claim 1, wherein a length of the pause period is equal to the second time. The method according to claim 1, wherein the turning is detected in response to a fact that the maximum value of the voltage decrease amount is not updated in a predetermined number of consecutive pause intervals. The turning point
-The voltage decrease amount in the last pause interval is smaller than the voltage decrease amount in the immediately preceding pause interval.
The method according to claim 1, wherein the method is detected in response to. The method according to claim 1, wherein the turning is detected using a least square method based on the voltage decrease amount in each pause period. Obtaining a liquid temperature of the liquid lead battery;
Determining the second time based on the liquid temperature;
The method according to any one of claims 1 to 5, further comprising: A method of detecting the state of a liquid lead battery,
In each of the pause intervals, a pause interval in which constant current charging is paused is provided at a fixed period.
-Identifying a first time point at which a first time has passed since the start of the pause;
-Identifying a second time point at which the voltage has dropped by a first voltage difference from the first time point;
-Obtaining the elapsed time from the first time point to the second time point;
A step of executing
Detecting that the charge rate of the liquid lead battery has reached 100% in response to the tendency of the change in the acquired value acquired during the pause period to change.
A method comprising: The method according to claim 7, wherein the turning is detected in response to a minimum value of the elapsed time not being updated in a predetermined number of consecutive pause intervals. The turning point
The method according to claim 7, wherein the elapsed time in the last pause interval is detected in response to being longer than the elapsed time in the immediately preceding pause interval. The method of claim 7, wherein the turning is detected using a least squares method based on the elapsed time in each pause interval. Obtaining a liquid temperature of the liquid lead battery;
Determining the first voltage difference based on the liquid temperature;
The method according to any one of claims 7 to 10, further comprising: A method of controlling charging of a liquid lead battery,
Detecting the state of the liquid lead battery using the method according to any one of claims 1 to 11;
Determining a charging current amount based on the state of the liquid lead battery; and
A method comprising:

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