JP4912649B2 - Battery status management method - Google Patents

Description

  The present invention relates to a battery state management method for managing the state of a battery (in this specification, a lead battery) mounted on a vehicle.

  When managing the battery state with the internal resistance of the battery taken into account, the internal resistance changes depending on the open circuit voltage (remaining charge) of the battery. It is necessary to know the dependency characteristics in advance. The open circuit voltage of the battery has a correlation with the remaining charge at that time.

  Conventionally, however, there are differences in the types of batteries (capacity, grade, manufacturer, etc.). Therefore, it is difficult to uniformly handle the dependence characteristics of the internal resistance of the battery on the open voltage. It was necessary to evaluate the characteristics of the internal resistance and set the conditions.

  Therefore, the problem to be solved by the present invention is to provide a battery state management method capable of uniformly handling the change mode of the internal resistance with respect to the change of the open circuit voltage of different types of batteries.

A battery state management method according to a first aspect of the present invention is a battery state management method for managing the state of a battery mounted on a vehicle, and has a predetermined constant current value for a battery that is substantially fully charged. While discharging, the transition of the output voltage of the battery over time is measured, and a characteristic that linearly approximates the transition of the measured open circuit voltage value of the battery from the start of the discharge and a predetermined reference start at the start of discharge An increase / decrease time is determined using a voltage value, and the discharge voltage in the transition of the output voltage is complemented or deleted from the transition of the output voltage by complementing or deleting the output voltage for the increase / decrease time from the start of the discharge. The elapsed time from the start is corrected to increase / decrease by the increase / decrease time, and the change in the open voltage of the battery is controlled based on the output voltage change mode in which the elapsed time is corrected to increase / decrease That derives the variant of the internal resistance, and performing battery state management based on the variant of the internal resistance that the derivation.

A battery state management method according to a second aspect of the present invention is a battery state management method for managing the state of a battery mounted on a vehicle, and has a predetermined constant current value for a battery in a substantially fully charged state. While discharging, measure the transition of the output voltage of the battery over time, and the time required until the value of the output voltage reaches a predetermined drop reference voltage value from the start of the discharge, An increase / decrease time is obtained using a characteristic that linearly approximates the transition of the measured open-circuit voltage value of the battery from the start of the discharge and a predetermined open-circuit reference open-circuit voltage value, and the start of the discharge with respect to the transition of the output voltage Compensating or deleting the output voltage corresponding to the increase / decrease time from the time, the elapsed time from the start of the discharge in the transition of the output voltage is increased / decreased by the increase / decrease time. According to the difference between the time and a predetermined reference time, the value of the output voltage at each time measured with the progress of the discharge of the battery is increased or decreased, and the elapsed time and the value of the output voltage are Deriving a change mode of the internal resistance with respect to a change in the open circuit voltage of the battery based on the change mode of the output voltage that has been corrected for increase / decrease, and managing the state of the battery based on the derived change mode of the internal resistance Features.

According to the battery state management method according to the first aspect of the present invention, output is performed using a characteristic that linearly approximates the transition of the measured open-circuit voltage value of the battery from the start of discharge and a predetermined reference open-circuit voltage value at the start of discharge. Increase / decrease the elapsed time from the start of discharge in the voltage transition. For this reason, it is possible to uniformly handle the change state of the internal resistance with respect to the change in the open-circuit voltage of the battery while suppressing the influence of the battery capacity variation.

According to the battery state management method of the second aspect of the present invention, output is performed using a characteristic that linearly approximates the transition of the measured open-circuit voltage value of the battery from the start of discharge and a predetermined open-circuit reference open-circuit voltage value. Increase / decrease the elapsed time from the start of discharge in the voltage transition. It also measures the time required from the start of discharge until the output voltage reaches the specified drop reference voltage value, and determines the battery discharge according to the difference between the required time and the reference time according to the test standard. A series of output voltage values measured with progress is corrected for increase or decrease. For this reason, it is possible to uniformly handle the change state of the internal resistance with respect to the change in the open-circuit voltage of the battery while suppressing the influence of the battery capacity variation.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the element which attached | subjected the same code | symbol in different drawing shall show the same or corresponding element.

<Overall explanation>
Before describing the main part of the battery state management method according to the present embodiment, the overall configuration of the battery state management device to which the battery state management method according to the present embodiment is applied will be described.

<Principle explanation>
First, the evaluation principle of the battery state in this battery state management apparatus will be described.

  FIG. 1 shows an open-circuit voltage (output voltage when the battery is not substantially discharged) and a lower limit voltage at engine start (battery output voltage due to discharge at engine start) for batteries with different deterioration conditions and remaining charge levels. Is a minimum voltage when the voltage drops, and corresponds to the voltage at the time of discharge according to the present invention). The horizontal axis corresponds to the open circuit voltage value of the battery before the start of discharge at engine start in each discharge test, and the vertical axis corresponds to the lower limit voltage value of the battery during discharge at engine start in each discharge test. Further, a curve G1 in FIG. 1 is drawn based on a measurement result of a new battery (substantially a new one (hereinafter the same)), and the curves G2 to G4 are used and deteriorated to some extent. It is drawn based on the measurement result about the battery, and the use period of the battery becomes longer in the order of the curves G2, G3, G4, and the deterioration progresses. It should be noted that by using the open-circuit voltage value after a certain time has elapsed from the end of charging (when the engine is stopped), the accuracy of obtaining the discharge characteristics and evaluating the state of the battery 1 is further improved.

  From the graph of FIG. 1, it can be seen that the corresponding curves G1 to G4 are shifted in the right direction (or the lower right direction) of the graph as the deterioration of the battery proceeds. In particular, in a region where the lower limit voltage value is a predetermined reference level (for example, 9 V) or less, the shift amount in the right direction of the curves G2 to G4 with respect to the curve G1 increases as the deterioration of the corresponding battery progresses. It turns out that there is a tendency. From this, if the discharge characteristic at the time of engine start of the new battery corresponding to the curve G1 (the lower limit voltage value during discharge at the start of the engine with respect to each discharge voltage value corresponding to each remaining charge amount) is derived, this is used as a reference. As a result, the battery state can be evaluated.

  However, the state of the load connected to the battery when the engine is started varies greatly depending on the vehicle type. For this reason, applying the conventional method to obtain the engine start-up discharge characteristic of the battery corresponding to the curve G1, for example, the engine start-up discharge of the battery corresponding to the curve G1 under a certain reference condition. The characteristic is detected by a test, and the discharge characteristic is finely adjusted using an adjustment parameter set for each vehicle type.

  Therefore, the inventor of the present application pays attention to the problems of the conventional method, and automatically calculates the discharge characteristics at the time of engine start of the battery reflecting the load condition at the time of engine start specific to the car body without using the adjustment parameters peculiar to the car body. Measures were taken so that it could be acquired in an efficient manner. The principle is as follows.

FIG. 2 is a graph for explaining the discharge characteristics of the battery when the engine is started. A curve G1 in the graph of FIG. 2 corresponds to the curve G1 of FIG. As shown in FIG. 3, the resistance value of the engine start load L _S (which is a load other than the internal resistance of the battery and includes a starter, other resistance elements, etc.) connected to the battery 1 at the time of engine start is expressed as R _S. and then, the internal resistance of the battery 1 and R _B, the open circuit voltage value of the battery 1 and V _O, at a minimum value of the output voltage at the time of to perform the discharge by connecting a load L _S when starting the engine in the battery 1 When a certain lower limit voltage value is V _L , the following relationship is established among these parameters R _S , R _B , V _O , and V _L.

Solving this equation (1) for V _L gives the following.

In the formula (2), the internal resistance value R _B is open voltage value V _O (i.e., the remaining charge of the battery 1) Assuming no change, the resistance value R _S when the load L _S engine start open voltage value because it is constant regardless of the value of V _O, the formula corresponding to the straight line G5 through the origin of the coordinate system of the graph of FIG. 2 (equation representing the proportionality relationship between the values V _O, V _L) is obtained.

Actually, since the internal resistance value R _B in the equation (2) increases with a decrease in the open circuit voltage value V _O (remaining charge of the battery 1), the lowering rate of the lower limit voltage value V _L is represented by the curve G1. In this way, it increases as the open circuit voltage value V _O decreases. In other words, parts with the longitudinal axis of the deviation amount in the negative direction is gradually increased with a decrease in open circuit voltage value V _O is reduced open-circuit voltage value V _O from a straight line G1 of the curve G1 in the graph of FIG. 2 it can be said to be due to increase in the resistance R _B.

Therefore, the present inventor has increased the proportion of open-circuit voltage value V _O internal resistance of the battery 1 with decreasing (remaining charge of the battery 1) R _B is approximately for any battery 1 if battery 1 of new Focusing on the common characteristics, and effectively using the characteristics, it is possible to easily detect the vehicle-specific discharge characteristics with respect to the engine start load L _S of the new battery 1. It came.

In other words, may be stored in the system previously acquired by the information about the rate of increase of the open circuit voltage value V _O internal resistance value R _B with decreasing of the battery 1 is new, when the vehicle completely assembled at the factory, the factory, vehicle When the battery 1 is delivered to the end user, or when the battery 1 is in a new state, such as within a certain period after the end user is delivered, the discharge characteristics using the engine start load L _S for the battery 1 (remaining charge remaining as a reference) 2 is obtained by measuring the open-circuit voltage value V _O of the new battery 1 and the lower limit voltage value V _L when the engine start load L _S is connected) in the graph of FIG. , based on the information about the rate of increase of pre-stored internal resistance value R _B and the measurement points, acquires the vehicle-specific discharge characteristics for when starting the engine of the new battery 1 load L _S It was found that the kill. In addition, about the measurement point peculiar to the vehicle, a result obtained by performing numerical processing such as averaging (including weighted average) on the measurement result obtained by performing the measurement a plurality of times may be used. Depending on the value of the open-circuit voltage (remaining charge) of the battery 1 at the time of measurement, methods such as preferential use of the measurement point with the maximum open-circuit voltage or increasing the contribution of the weighted average can be considered.

More specifically, first, the open-circuit voltage value V _OIF and the internal resistance value R when the remaining charge of the new battery 1 is in a fully charged state (substantially fully charged state (the same applies hereinafter)). _{The BIF} and the rate of change (R _BI / R _BIF ) of the internal resistance value R _BI with respect to R _BIF at each open-circuit voltage value V _OI when the remaining charge amount is reduced are measured by tests. The function changing rate of the internal resistance value R _BI and (R _BI / R _BIF), where the open-circuit voltage value V _OI and variable with respect to a change in open-circuit voltage value V _OI of new battery 1 (e.g., Formula (3) Information about the function is previously stored in the system. Alternatively, as a modified example, the open circuit voltage value V _OI and the corresponding change rate (R _BI / R _BIF ) of the internal resistance value R _BI are stored in the system in advance as a data table. May be. A specific method for measuring the rate of change (R _BI / R _BIF ) of the internal resistance value R _BI at each open circuit voltage value V _OI will be described later.

Next, when the battery 1 at the time of vehicle assembly completion at the factory is in a new state and the battery 1 is fully charged, the open-circuit voltage value (initial reference discharge voltage value) V _OIF and the battery 1 The lower limit voltage value (initial reference lower limit voltage value) V _LIF of the battery 1 when the engine starting load L _S is connected is measured. Whether or not the battery 1 is in a fully charged state is determined by, for example, measuring the open-circuit voltage value of the battery 1 and determining whether or not the value is equal to or higher than a predetermined reference level corresponding to the fully charged state. Is done. As described above, the initial reference discharge voltage value V _OIF and the initial reference lower limit voltage value V _LIF may be measured a plurality of times and averaged.

By using the measurement result of the initial reference discharge voltage value V _OIF and the initial reference lower limit voltage value V _LIF and the function of the above equation (3) (or a data table equivalent thereto), a new battery mounted on the vehicle A relational expression indicating a change in the lower limit voltage value V _LI accompanying a change in the open circuit voltage value V _OI with respect to the engine starting load L _S is given by the following expression.

Here, the parameter V _LK in the above equation (4) is a lower limit voltage value when the open-circuit voltage value on the straight line G5 in the graph of FIG. 2 is V _OI , and is given by the following equation (5).

The relational expression of the expression (4) is derived, for example, as follows. That is, when considering that the relationship of the above equation (1) is applied to the coordinate point P _F in the graph of FIG. 2, the internal resistance value R _B when the open-circuit voltage value is V _OIF (at full charge) is expressed as R _BIF . Then, the following relational expression (6) is obtained.

Also, when considering the fitting the relationship of the above equation (1) coordinate point P _I in the graph of FIG. 2, internal resistance value R _B is above equation when the open circuit voltage value V _OI (3) from R _B = F (V _OI ) · R _BIF is obtained, the following relational expression (7) is obtained.

Therefore, when the parameter V _LI is solved by substituting the right side of the relational expression (6) for the parameter (R _S / R _BIF ) on the left side of the relational expression (7), the relational expression (4) is obtained.

From another point of view, the relational expression of the above formula (6) is based on the straight line G5 in the graph of FIG. 2, and the open circuit voltage at that point given by the relation of the above formula (3) by shifted in the vertical axis minus direction by a shift amount corresponding to the variant of the change rate of the internal resistance of the battery 1 in accordance with the value V _OI, the lower limit voltage value at each remaining charge (each open-circuit voltage value V _OI) V _LI is derived.

The information regarding the relationship between the open circuit voltage value V _OI and the lower limit voltage value V _LI derived in this way reflects the resistance value R _S of the engine starting load L _S inherent to the vehicle. Thus, the state evaluation of the battery 1 reflecting the vehicle-specific load environment and the like can be performed.

Here, the values V _OIE and V _{LIE in} the graph of FIG. 2 are the open-circuit voltage values when the new battery 1 has a remaining charge level of zero (the remaining charge level should be substantially zero (the same applies hereinafter)). And the lower limit voltage value. Further, specific examples of the values V _OIF and V _OIE are 12.8V and 11.9V, for example.

Next, a method for acquiring information related to the increase rate of the internal resistance value R _B accompanying the decrease in the open circuit voltage value V _O in the new battery 1 will be schematically described. That is, in the present embodiment, a plurality of different fully charged new batteries 1 are discharged with a constant current value conforming to the JIS standard, and the transition of the output voltage of the battery 1 at that time is measured. By performing standardization processing and averaging processing, which will be described later, based on the measurement result, the battery 1 discharge characteristic data in which differences in characteristics and variations due to differences in the types of batteries 1 and individual differences are standardized and averaged are acquired ( Details of the standardized and averaged method for obtaining the discharge characteristic data will be described later). A curve G7 in the graph of FIG. 4 shows the transition of the output voltage of the battery 1 thus standardized and averaged, and the value V _AF in the graph is the value of the fully charged battery 1 before the start of discharging. The output voltage value (open voltage value) corresponds to the above-described value V _OIF . The value V _AE is an open-circuit voltage value at the end of discharging corresponding to zero remaining charge of the battery 1, and corresponds to the aforementioned value V _OIE described above. The value V _BF is the output voltage value of the battery 1 immediately after the start of discharging, the value V _BE is the output voltage value at the end of discharging corresponding to the remaining charge amount of the battery 1, and the value _TE is the remaining charge amount. The time at the end of discharge corresponding to zero is shown. A straight line G8 approximates the transition of the open-circuit voltage of the battery 1 that changes with a decrease in the remaining charge amount due to discharge by a straight line. Further, the hatched region in the graph is the impact portion reflecting the increase in the internal resistance R _B of the battery 1 with decreasing remaining charge, the graph of FIG. 5 to FIG. 2 and described below Corresponds to the hatched area.

Note that the above values V _AF and V _AE are obtained before the discharge of each battery 1 (at the time of full charge) and after the completion of the discharge in accordance with a standard discharge characteristic data acquisition test performed using a plurality of new batteries 1 described later. It is desirable to average and use the measured open-circuit voltage value when the remaining charge is zero. Alternatively, separate tests may be performed to determine the values V _AF and V _AE .

Subsequently, the magnitude of the difference along the vertical axis of the graph between the point at point a straight line G8 in the upper curve G7 in the graph of FIG. 4 is proportional to the internal resistance value R _B of the battery 1 at that point in time The ratio (D3 / D3) of the difference D2 between the value V _AF and the value V _BF at the start of discharge (at the time of full charge) and the difference D3 between each point on the straight line G8 and each point on the curve G7 By D2), the rate of change (R _B / R _BF ) of the internal resistance value R _B at each open circuit voltage value V _O can be derived. A curve G9 in the graph of FIG. 5 shows the rate of change (R _B / R _BF ) of the internal resistance value R _{B with} respect to the change of the open-circuit voltage value V _O derived as described above. (3) is determined.

Next, referring to FIG. 6, the relational expressions (4) and (5) above (or the data table in which the open circuit voltage value V _OI and the lower limit voltage value V _LI equivalent to the relational expressions are associated) are shown. An evaluation principle of the state (deterioration degree and remaining charge amount) of the used battery 1 will be described.

First, the evaluation principle of the degree of deterioration will be described. The curve G1 in the graph of FIG. 6 indicates the relational expressions (4) and (5) previously stored in the system as described above (or the open-circuit voltage value V _OI and the lower limit voltage value equivalent to the relational expressions). (Data table in which V _LI is associated) and the above-described initial reference open circuit voltage value V _OIF and initial reference lower limit voltage value V _LIF . Information on the curve G1 and the values V _OIF and V _{LIF in} FIG. 6 is stored in the system and used for evaluating the state of the battery 1.

When the use of the battery 1 is started, when the degree of deterioration of the battery 1 is evaluated, the engine start load L _S at the start of the engine is an open voltage before being connected to the battery 1. A post-opening voltage value V _OR and a post-use lower limit voltage value V _LR that is a lower limit voltage when the engine starting load L _S is connected to the battery 1 are measured. At this time, the remaining charge of the battery 1 does not have to be fully charged.

Subsequently, the open-circuit voltage value when the lower-limit voltage value on the curve G1 in the graph of FIG. 6 is equal to the post-use lower-limit voltage value V _LR is derived as the corresponding reference open-circuit voltage value V _{OS and} stored in advance. A first difference value D11 that is the difference between the reference open circuit voltage value V _OIF and its corresponding reference open circuit voltage value V _OS, and a second that is the difference between the initial reference open circuit voltage value V _OIF and the used open circuit voltage value V _OR . The degree of deterioration of the battery 1 at that time is detected by comparing the difference value D12.

This detection principle has a characteristic that the measurement point (V _O , V _L ) on the graph shifts substantially to the left so as to approach the curve G1 as the deterioration degree of the battery 1 described with reference to FIG. 1 is smaller. It is used. That is, as the degree of deterioration of the battery 1 is smaller, the measurement point P11 (V _OR , V _LR ) on the graph of FIG. 6 is closer to the coordinate point P12 on the corresponding curve G1. The degree of deterioration of the battery 1 is evaluated based on the degree of approach to the coordinate point P12 of P11.

Next, the evaluation principle of the remaining charge will be described. Similar to the evaluation of the degree of deterioration, the evaluation of the remaining charge amount is performed using the relationship between the discharge voltage and the lower limit voltage when the battery 1 represented by the curve G1 in the graph of FIG. In the evaluation, the post-use open-circuit voltage value V _OR and the post-use lower limit voltage value V _LR are measured. The storage unit 17 stores a minimum reference open circuit voltage value V _OIE that is an open circuit voltage when the remaining amount of charge of the new battery 1 acquired with the acquisition of the internal resistance change rate of the above equation (3) is zero. It is stored in advance as an initial setting.

Similarly to the evaluation of the degree of deterioration, the open-circuit voltage value when the lower-limit voltage value on the curve G1 of the graph of FIG. 6 is equal to the post-use lower-limit voltage value V _LR is used as the corresponding reference open-circuit voltage value V _OS. Derived as Then, a minimum post-use open-circuit voltage value V _ORE that is an open-circuit voltage when it is assumed that the remaining charge of the battery 1 at the time when the use is started is zero is derived as follows. That is, a ratio of a value D14 obtained by subtracting the minimum post-use open-circuit voltage value V _ORE from the initial reference open-circuit voltage value V _OIF to a value D13 obtained by subtracting the minimum standard open-circuit voltage value V _OIE from the initial reference open-circuit voltage value V _OIF acquired in advance. but to be equal to the ratio of the initial reference open circuit voltage value V corresponding reference from the _OIF open voltage value V _OS initial reference to the value D11 obtained by subtracting the open circuit voltage value V value obtained by subtracting the open circuit voltage value V _OR after use _OIF D12 The minimum post-use open-circuit voltage value V _ORE is derived.

The difference between the initial reference open-circuit voltage value V _OIF and the minimum post-use open-circuit voltage value V _ORE, and the difference between the post-use open-circuit voltage value V _OR and the minimum post-use open-circuit voltage value V _OS. Is compared with the fourth difference value D22, so that the remaining charge of the battery 1 at that time is detected.

  According to this detection principle, as the remaining charge of the battery 1 decreases from the fully charged state, the coordinate point P21 corresponding to the measurement point P11 on the virtual line L1 parallel to the horizontal axis of the graph of FIG. This utilizes the characteristic of approaching from the coordinate point P22 side corresponding to the amount to the coordinate point P23 side corresponding to the state of zero remaining charge.

<Device configuration>
FIG. 7 is a block diagram of a battery state management apparatus to which the battery state management method according to one embodiment of the present invention is applied. As shown in FIG. 7, the battery state management device includes a current sensor 11, a voltage sensor (voltage detection means) 13, a processing unit 15, a storage unit 17, and an output unit 19, and is mounted on a vehicle. The state of the battery 1 is managed.

  The current sensor 11 detects an input / output amount of current to the battery 1. The voltage sensor 13 detects the output voltage of the battery 1. The processing unit 15 includes a CPU and the like, and performs various information processing operations (including control operations) for managing the battery 1. The storage unit 17 includes a memory and the like, and stores information necessary for various information processing operations performed by the processing unit 15. The output unit 19 is for outputting a determination result of the state of the battery 1 and the like.

<Whole predetermined operation>
First, the overall processing operation of the battery state management apparatus will be described with reference to FIG. As the ignition switch (hereinafter referred to as “IG switch”) 21 is turned on in step S1, the processing unit 15 performs an initial charge remaining amount detection operation in step S2. In this detection operation, the open-circuit voltage of the battery 1 is measured via the voltage sensor 13, and the remaining charge (initial charge remaining) of the battery 1 before starting the engine is detected based on the measured value of the open-circuit voltage. At this time, it is also determined whether or not the battery 1 is fully charged. Note that the open-circuit voltage of the battery 1 measured here is used for engine start state determination in step S5 described later or reference discharge characteristic derivation processing in step S6.

  As the starter 23 is driven and the engine (not shown) is started in the subsequent step S3, the processing unit 15 determines whether or not the process for deriving the reference discharge characteristics of the battery 1 is necessary in step S4. That is, after the vehicle assembly is completed, if the reference discharge characteristic derivation process has not yet been performed, the process proceeds to step S6, where the reference discharge characteristic derivation process is performed. If the derivation process has already been performed, step S6 is performed. Proceeding to S5, engine starting state determination processing is performed. Whether or not the reference discharge characteristics have already been derived is determined, for example, by whether or not the relational expression (or equivalent data table) relating to the above expressions (4) and (5) is stored in the storage unit 17. It is done by judging. In addition, the derivation of the reference discharge characteristics does not need to be performed until the battery 1 is replaced if it is substantially performed once at the time of completion of vehicle assembly. When the reference discharge characteristic deriving process in step S6 or the starting state determination process in step S5 is performed, the process proceeds to step S7, and a post-startup deterioration determination process is performed. The specific contents of the reference discharge characteristic derivation process and the starting state determination process will be described later.

  Then, the processing unit 15 performs a deterioration determination operation after engine start in the subsequent step S7. In this deterioration determination operation after starting, a current inflow state to the battery 1 that has become fully charged (or a state close thereto) by charging after the engine is started is detected via the current sensor 11, and the battery is determined based on the current inflow state. A degradation degree of 1 is determined.

  Moreover, the process part 15 performs charge control (charge remaining amount management of the battery 1) with respect to the battery 1 by continuing step S8. In this charge control, by integrating the measured current value of the current sensor 11, the total amount of current discharged from the battery 1 from a predetermined reference time such as when the engine is started is sequentially detected, and the battery 1 is based on the detection result. The amount of charge to be performed is determined. As a result, the remaining charge of the battery 1 during traveling is maintained within a predetermined range. The charge amount is controlled, for example, by controlling the power generation amount (output voltage or the like) of an alternator (not shown).

  The deterioration determination operation and charge control after engine start in steps S7 and S8 are repeatedly continued until the engine is stopped.

<Standard discharge characteristics derivation process>
Here, the reference discharge characteristic process performed in step S6 of FIG. 8 described above will be described. As a premise of the reference discharge characteristic deriving process, the storage unit 17 has an open circuit that approximately represents the rate of change (R _BI / R _BIF ) of the internal resistance value R _{BI with} respect to the change of the open circuit voltage value V _OI of the new battery 1. Information on the function such as the above expression (3) with the voltage value V _OI as a variable (or the equivalent open circuit voltage value V _OI and the rate of change of the internal resistance value R _BI at each open circuit voltage value V _OI (R _BI / R _BIF ) must be stored in advance.

  The processing unit 15 performs the reference discharge characteristic derivation process only when the battery 1 is in a fully charged state based on the detection in step S2. If the battery 1 is not in the fully charged state, For example, the process proceeds to step S7 without performing the derivation process. If the battery 1 is in a fully charged state at the next engine start, a reference discharge characteristic derivation process is performed at step S6.

In this derivation process, as described above, the lower limit voltage value when the engine starting load L _S is connected to the battery 1 is measured via the voltage sensor 13 as the initial reference lower limit voltage value V _LIF , and this initial reference lower limit voltage is set. Using the value V _LIF , the initial reference open circuit voltage value V _OIF that is the open circuit voltage measured in the immediately preceding step S 2, and the above equation (3) (or a data table equivalent to the above equation (3)) The reference discharge characteristic of the new battery 1 with respect to the engine starting load L _S is derived. That is, the reference discharge characteristic of the new battery 1 is derived as a relational expression of the above expression (4) indicating the change in the lower limit voltage value V _LI accompanying the change in the open circuit voltage value V _OI . However, the parameter R _LK in the equation (4) is given by the above equation (5).

In the present embodiment, the relationship between the change in the open circuit voltage value V _{OI and} the change in the lower limit voltage value V _LI in the new battery 1 derived in this way is expressed in the form of relational expressions (4) and (5) in the storage unit 17. However, a data table substantially equivalent to the relational expressions (4) and (5) (a curve G1 on a two-dimensional coordinate with the open-circuit voltage and the lower limit voltage taken on the vertical axis and the horizontal axis is shown. The coordinate information may be stored in the storage unit 17 in the form of coordinate information.

In this reference discharge characteristic derivation process, the initial reference open circuit voltage value V _OIF and the initial reference lower limit voltage value V _LIF used for the derivation process are stored in the storage unit 17.

<Start-up state determination process>
Next, the starting state determination process performed in step S5 of FIG. 8 described above will be described. This start-up state determination process is executed regardless of the remaining charge of the battery 1, but it is a precondition that the reference discharge characteristic deriving process in step S6 has been completed.

In this starting state determination process, as described above, the lower limit voltage value when the engine starting load L _S is connected to the battery 1 is measured via the voltage sensor 13 as the lower limit voltage value V _LR after use. Post-lower limit voltage value V _LR , post-use open-circuit voltage value V _OR which is the open-circuit voltage measured in the immediately preceding step S2, and information acquired by the reference discharge characteristic derivation process in step S6 and stored in the storage unit 17 Based on the above, the degree of deterioration and the remaining charge of the battery 1 at that time are determined.

First, the case processing for the degree of deterioration will be described. First, when the lower limit voltage value on the curve G1 of the graph of FIG. 6 represented by the relational expressions (4) and (5) stored in the storage unit 17 is equal to the lower limit voltage value V _LR after use. The open circuit voltage value is derived as the corresponding reference open circuit voltage value V _OS . Alternatively, the value of the variable V _OI when the post-use lower limit voltage value V _LR is substituted for the variable V _LI in the equations (4) and (5) is derived as the corresponding reference open circuit voltage value V _OS .

Subsequently, a first difference value D11 that is a difference between the initial reference open circuit voltage value V _OIF stored in the storage unit 17 and the corresponding reference open circuit voltage value V _OS , the initial reference open circuit voltage value V _OIF, and the open circuit after use. By comparing the second difference value D12, which is the difference from the voltage value _VOR , the degree of deterioration of the battery 1 at that time is detected. For example, the degree of deterioration of the battery 1 is detected based on the ratio of the second difference value D12 to the first difference value D11 (corresponding to the hatched portion C1 in FIG. 6).

Next, the remaining charge determination process will be described. In this determination process, the process is performed using the post-use lower limit voltage value V _LR and the corresponding reference open circuit voltage value V _OS acquired by the deterioration degree determination process.

Subsequently, a minimum post-use open-circuit voltage value V _ORE that is an open-circuit voltage when assuming that the remaining charge of the battery 1 at that time is zero is derived as follows. In other words, the initial reference open circuit voltage value V _OIF acquired in advance is subtracted from the initial reference open circuit voltage value V _OIF for the value D13 obtained by subtracting the minimum standard open circuit voltage value V _OIE stored in the storage unit 17 by the initial setting. The ratio of the value D14 obtained by subtracting the voltage value V _ORE is the initial reference open voltage value V _OIF to the post-use open circuit voltage value V _OR for the value D11 obtained by subtracting the corresponding reference open voltage value V _OS from the initial reference open circuit voltage value V _OIF. The minimum post-use open-circuit voltage value V _ORE is derived so as to be equal to the ratio of the subtracted value D12.

The difference between the initial reference open-circuit voltage value V _OIF and the minimum post-use open-circuit voltage value V _ORE, and the difference between the post-use open-circuit voltage value V _OR and the minimum post-use open-circuit voltage value V _OS. Is compared with the fourth difference value D22, so that the remaining charge of the battery 1 at that time is detected. For example, the remaining charge of the battery 1 is detected based on the ratio of the second difference value D22 to the third difference value D21 (corresponding to the hatched portion C2 in FIG. 6).

<Acquisition method of standard discharge characteristics data>
Next, a method for acquiring standard discharge characteristic data of the battery 1 in the battery state management method according to the present embodiment will be described.

  First, in this embodiment, the output voltage of the battery 1 is measured while discharging a predetermined current value corresponding to the JIS standard (JIS D 5301) relating to the battery capacity test for a plurality of new batteries 1 in a fully charged state. The test to do. This test averages variations in characteristics due to differences in the types of batteries 1 and individual differences, and obtains average characteristics data for various batteries 1 that are actually mounted on the vehicle. It is desirable to perform tests on various types of batteries 1 having different types, and it is also desirable to test a plurality of batteries 1 for the batteries 1 in the same type.

  Here, the capacity test of the JIS standard (JIS D 5301) refers to a fully charged battery 1 until the output voltage of the battery 1 drops to a predetermined drop reference voltage value (10.5 V). A constant current value (5 hour rate current (0.2 CA), for example, 48 × 0.2 = 9.6 A for a battery with a standard capacity of 48 Ah) corresponding to the standard capacity of 1 is discharged, and the output voltage drops. The elapsed time from the start of discharge until the reference voltage value is reached is measured. In the present embodiment, the output voltage is measured at intervals of, for example, 1 second.

  Hereinafter, a case where the standard capacity of the battery 1 is 48 Ah will be described as an example.

<Output voltage correction process>
FIG. 9 is a graph showing a first test result of the battery capacity test. The horizontal axis represents time t, and the horizontal axis time T0 corresponds to 5 hours, that is, 18000 seconds. The vertical axis represents the output voltage V (t), V1 on the vertical axis corresponds to the drop reference voltage (10.5V), and V2 corresponds to the open circuit voltage (12.8V). The result of the capacity test for the battery 1 is represented as a characteristic K1. The characteristic L represents the transition of the open circuit voltage value from the start of discharge to the end of the test approximated by a straight line.

  If the actual capacity of the battery 1 is 48 Ah as specified, the output voltage V (t) should drop to the drop reference voltage value V1 at time T0. However, as shown by the characteristic K1, the battery 1 drops to the drop reference voltage value V1 at time T1 earlier than time T0. This means that the actual capacity of the battery 1 was smaller than 48 Ah due to product variations and the like. That is, although the actual capacity is smaller than 48 Ah, the discharge voltage is 9.6 A, so that the output voltage V (t) drops to the reference voltage value V1 at a time earlier than the time T0. It is.

  The actual capacity of the battery 1 can be obtained by multiplying the time T1 and the current value of 9.6 A. For example, if the value is 46 Ah, the battery 1 is originally 46 × 0.2 = 9. The capacity test should have been performed using a 2 A discharge current.

Therefore, in the present embodiment, the characteristic K1 is corrected according to the difference between the time T1 and the time T0. Specifically, the discharge current value actually used in the capacity test is I ₀ (in this example, 9.6 A), the discharge current value that should have been originally used is I _r (in this example, 9.2 A), Assuming that the open-circuit voltage value at time t is V ₀ (t) and the output voltage value at each time t is V (t), the corrected output voltage value V (t) ′ is calculated by the following equation (8). .

In FIG. 9, the corrected output voltage value V (t) ′ is represented as a characteristic K2. In the example shown in FIG. 9, since I ₀ > I _r , a characteristic K 2 in which the characteristic K 1 is corrected in the increasing direction by ΔV as a whole is obtained.

  FIG. 10 is a graph showing a second test result of the battery capacity test. Contrary to the example shown in FIG. 9, the battery 1 drops to the drop reference voltage value V1 at a time T2 later than the time T0. This means that the actual capacity of the battery 1 was larger than 48 Ah. That is, although the actual capacity is larger than 48 Ah, the discharge voltage is 9.6 A, so that the output voltage V (t) falls to the reference voltage value V1 at a time later than the time T0. It is.

  Assuming that the actual capacity of the battery 1 obtained by multiplying the time T2 and the current value 9.6A is, for example, 50 Ah, the battery 1 originally performed a capacity test using a discharge current of 50 × 0.2 = 10 A. It should have been done.

Therefore, in this case as well, the characteristic K1 is corrected by the equation (8) as described above. In FIG. 10, the corrected output voltage value V (t) ′ is represented as a characteristic K3. In the example shown in FIG. 10, since I ₀ <I _r , the characteristic K3 in which the characteristic K1 is corrected in the decreasing direction by ΔV as a whole is obtained.

<Elapsed time correction processing>
FIG. 11 is a graph showing a third test result of the battery capacity test. The vertical axis Y1 is the output voltage V (t), V1 corresponds to the drop reference voltage (10.5V), V2 corresponds to the reference open voltage (12.8V), and V3 is the actual initial open of the battery 1. This corresponds to the voltage (open voltage at the start of discharge). The horizontal axis represents time t, and time T3 on the horizontal axis corresponds to the time from the start of discharge (time t = 0) until the output voltage V (t) drops to the drop reference voltage V1. The result of the capacity test for the battery 1 is represented as a characteristic K1. The characteristic L represents the transition of the open circuit voltage value from the start of discharge to the end of the test approximated by a straight line.

  Focusing on the vertical axis Y1, the initial open circuit voltage V3 of the battery 1 is higher than the reference open circuit voltage V2 due to product variations, repeated charge / discharge, and the like.

  Therefore, in the present embodiment, the following correction is performed according to the difference between the initial open circuit voltage V3 and the reference open circuit voltage V2. First, a point where the open circuit voltage value is equal to the reference open circuit voltage V2 on the characteristic L is determined, and a new vertical axis Y2 passing through the point is defined. Then, a time T4 corresponding to the intersection of the vertical axis Y2 and the horizontal axis is obtained, and the elapsed time from the start of discharge to each time point in the capacity test is corrected by the obtained time T4. In the example shown in FIG. 11, the vertical axis Y2 is defined in the positive direction of the horizontal axis with respect to the vertical axis Y1, and therefore, for example, time T5 is corrected to T5-T4 and time T3 is corrected to T3-T4. In other words, it is equivalent to performing correction to delete the portion on the left side of the vertical axis Y2 (the portion indicated by the broken line) from the entire characteristic K1 obtained in the actual capacity test.

  FIG. 12 is a graph showing a fourth test result of the battery capacity test. V4 on the vertical axis Y1 corresponds to the actual initial open-circuit voltage of the battery 1 (open-circuit voltage at the start of discharge). Contrary to the example shown in FIG. 11, the initial open circuit voltage V4 of the battery 1 is lower than the reference open circuit voltage V2 due to product variations and the like.

  Therefore, in the present embodiment, the following correction is performed according to the difference between the initial open circuit voltage V4 and the reference open circuit voltage V2. First, the characteristic L is linearly extended in the negative direction of the horizontal axis. Next, a point where the open circuit voltage value becomes equal to the reference open circuit voltage V2 on the extended characteristic L is determined, and a new vertical axis Y3 passing through the point is defined. Then, a time T6 obtained by converting the distance between the vertical axis Y3 and the vertical axis Y1 into time is obtained, and the elapsed time from the start of discharge to each time point in the capacity test is corrected by the obtained time T6. Similarly to the characteristic L, the characteristic K1 also extends linearly toward the vertical axis Y3. In the example shown in FIG. 12, since the vertical axis Y3 is defined in the minus direction of the horizontal axis from the vertical axis Y1, for example, the time T7 is corrected to T7 + T6 and the time T3 is corrected to T3 + T6. In other words, it is equivalent to performing correction for adding a portion on the left side of the vertical axis Y1 to the characteristics K1, L obtained in the actual capacity test.

  In the above description, the output voltage value correction process and the elapsed time correction process have been described separately. However, both correction processes can be performed on one result of the capacity test.

In the present embodiment, the discharge characteristics of the new battery 1 that is averaged and standardized for the types of differences and individual differences obtained as described above (the output voltage V ( using data) concerning the transition of t), it is adapted to obtain information about the percentage increase of the internal resistance value R _B with decreasing of the output voltage value V of the battery 1 of a standard new (t). The method for deriving the increasing rate of the internal resistance value R _B based on the data relating to the transition of the output voltage V (t) is as described above.

<Summary>
As described above, according to the present embodiment, while the discharge of the current value at a predetermined level conforming to the JIS standard for the battery capacity test is performed, the transition of the output voltage of the battery 1 over time is measured, Since the state management of the battery 1 is performed based on the discharge characteristic data of the battery 1 obtained by averaging the measurement results, there are individual differences even if the types of the batteries 1 are different in capacity, grade, etc. With respect to the battery 1, it is possible to uniformly handle changes in the internal resistance value with respect to changes in the output voltage. As a result, it is not necessary to perform characteristic evaluation or condition setting of the internal resistance for each type of the battery 1.

  Also, as shown in FIGS. 9 and 10, the required times T1 and T2 from the start of discharge until the value of the output voltage V (t) reaches the predetermined drop reference voltage value V1 are measured. According to the difference between T2 and the reference time T0 based on the test standard, the value of the series of output voltages V (t) measured as the battery 1 is discharged is increased or decreased. For this reason, it is possible to uniformly handle the change mode of the internal resistance with respect to the change in the open-circuit voltage of the battery 1 while suppressing the influence of the variation in the capacity of the battery 1.

  Further, as shown in FIGS. 11 and 12, the output voltage V (t (t) is determined in accordance with the difference between the measured open circuit voltage values V3 and V4 of the battery 1 at the start of discharge and the predetermined discharge start reference open circuit voltage value V2. ), The elapsed times T3, T5, and T7 from the start of discharge in the transition are corrected to increase or decrease. For this reason, it is possible to uniformly handle the change mode of the internal resistance with respect to the change in the open-circuit voltage of the battery 1 while suppressing the influence of the variation in the capacity of the battery 1.

In addition, since the standardization process is performed on the output voltage value V _O at the start of discharge based on the measured initial value V _SM that is the value V _O of the output voltage of each battery 1 after a predetermined time has elapsed since the start of discharge in the discharge test. Standardization can be performed without being affected by the unstable behavior of the output voltage immediately after the start.

Further, since the rate of change of the internal resistance of the battery 1 with respect to the change of the open-circuit voltage according to the change of the remaining charge of the new battery 1 is almost the same regardless of the grade of the battery 1, the change in the internal resistance Rate and the voltage drop characteristic at the time of full charge of the battery 1 with respect to the engine starting load L _S unique to the vehicle at the time of vehicle assembly completion or the like. Discharge characteristics can be acquired automatically without setting parameters specific to each vehicle type, reducing human and equipment costs for parameter settings, as well as variations due to individual vehicle differences within the same vehicle type. Can be easily accommodated.

  Further, as described above, by evaluating the degree of deterioration and the remaining charge based on the reference discharge characteristics of the battery 1 and the discharge characteristics of the battery 1 due to the discharge at the time of engine start at each evaluation time point, Without taking special measures such as parameter setting for individual differences, it is possible to accurately detect the degree of deterioration of the battery 1 and the remaining charge amount by a simple calculation process.

  Further, the degree of deterioration of the battery 1 at each time point can be detected without depending on the remaining charge amount of the battery 1, and the remaining charge amount of the battery 1 at each time point can be detected without depending on the degree of deterioration of the battery 1. Can be detected.

  In this embodiment, since the lowest value of the output voltage of the battery 1 when the engine is discharged is used as the discharge voltage value of the battery 1, the discharge voltage that effectively represents the characteristics of the battery 1 is used. The value can be acquired easily and reliably, and it is not necessary to cause the battery 1 to perform a special discharge for evaluating the state of the battery 1, and the engine starting ability of the battery 1 can be accurately evaluated. As a modification of this point, the discharge characteristics of the battery 1 may be detected by using a discharge by another load instead of a discharge at the time of starting the engine of the battery 1. Moreover, although the minimum value of the output voltage of the battery 1 at the time of discharge was used as the voltage value at the time of discharge, for example, the output voltage value after a predetermined minute time has elapsed from the start of discharge may be used as the voltage value at the time of discharge. .

  Moreover, since the fully charged state is used as a reference for the remaining charge of the battery 1 when acquiring the discharge characteristics of the battery 1 in a new state, the remaining charge of the battery 1 can be easily and accurately set to the reference state. As a result, the discharge characteristics of the battery 1 can be detected easily and accurately. In this regard, the discharge characteristics of the new battery 1 may be acquired with reference to another remaining charge level.

<Modification>
In addition, since the method for evaluating the state of the battery 1 according to the above-described embodiment tends to decrease in reliability as the lower limit voltage value V _LR of the battery 1 at each evaluation increases, in order to ensure the reliability of the evaluation result, The determination of the degree of deterioration of the battery 1 and the remaining charge amount may be performed only when the lower limit voltage value V _LR is equal to or lower than a predetermined reference level.

  In addition, a temperature sensor that measures the temperature of the battery 1 may be added to the apparatus configuration of FIG. 7 according to the above-described embodiment, and the state evaluation in consideration of the temperature of the battery 1 may be performed. More specifically, for example, two-dimensional coordinate information representing the relationship between the open circuit voltage and the lower limit voltage of a new battery 1 at each temperature (in this case, it can also be referred to as three-dimensional coordinate information when considering the temperature). Deriving and evaluating the state at the current temperature based on it, and evaluating the state by correcting the temperature-dependent parameters (open voltage, lower limit voltage, etc.) to a temperature (for example, correcting to the standard temperature value) May be performed.

It is a graph which shows the measurement result which measured the open circuit voltage and the minimum voltage at the time of engine starting about the battery from which a deterioration condition and charge remaining amount differ. It is a graph for demonstrating the discharge characteristic at the time of engine starting of a battery. It is a circuit diagram which shows typically the relationship between the load connected to a battery at the time of engine starting, and the internal resistance of a battery. It is the graph of the data obtained by measuring transition of the output voltage at the time of discharge of a new battery using a JIS capacity test, and performing predetermined averaging processing etc. about the data. It is a graph which shows transition of the internal resistance change rate with respect to the change of the open circuit voltage accompanying discharge. It is a graph for demonstrating the principle which performs the state evaluation of a battery based on the discharge characteristic at the time of engine starting of the derived | led-out battery. It is a block diagram of the battery state management apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows the whole processing operation of the battery state management apparatus of FIG. It is a graph which shows the 1st test result of a battery capacity test. It is a graph which shows the 2nd test result of a battery capacity test. It is a graph which shows the 3rd test result of a battery capacity test. It is a graph which shows the 4th test result of a battery capacity test.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery 11 Current sensor 13 Voltage sensor 15 Processing part 17 Memory | storage part 19 Output part 21 IG switch 23 Starter

Claims (2)

A battery state management method for managing a state of a battery mounted on a vehicle,
For a battery in a substantially fully charged state, while measuring the change in the output voltage of the battery over time, while discharging a predetermined constant current value,
An increase / decrease time is obtained using a characteristic that linearly approximates the transition of the measured open-circuit voltage value of the battery from the start of the discharge and a predetermined reference open-circuit voltage value at the start of discharge, and the discharge with respect to the transition of the output voltage Compensate or delete the output voltage for the increase / decrease time from the start of the correction to increase / decrease the elapsed time from the start of the discharge in the transition of the output voltage by the increase / decrease time,
Based on the output voltage change mode in which the elapsed time is corrected, the internal resistance change mode with respect to the battery open-circuit voltage change is derived, and the battery state management is performed based on the derived internal resistance change mode. The battery state management method characterized by performing. A battery state management method for managing a state of a battery mounted on a vehicle,
For a battery in a substantially fully charged state, while discharging at a predetermined constant current value, the transition of the output voltage of the battery over time, and the value of the output voltage from the start of the discharge Measure the time required to reach the specified drop reference voltage value,
An increase / decrease time is obtained using a characteristic that linearly approximates the transition of the measured open-circuit voltage value of the battery from the start of the discharge and a predetermined reference open-circuit voltage value at the start of discharge, and the discharge with respect to the transition of the output voltage Compensate or delete the output voltage for the increase / decrease time from the start of the correction to increase / decrease the elapsed time from the start of the discharge in the transition of the output voltage by the increase / decrease time,
According to the difference between the required time and a predetermined reference time, the value of the output voltage at each time measured with the progress of the discharge of the battery is increased or decreased,
Based on the change mode of the output voltage in which the elapsed time and the value of the output voltage are corrected to increase or decrease, a change mode of the internal resistance with respect to a change in the open circuit voltage of the battery is derived, and the change mode of the derived internal resistance is derived. A battery state management method comprising performing battery state management based on the above.

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