JP4813053B2 - Battery state management device - Google Patents

Description

  The present invention relates to a battery state management device that manages the state of a battery of an automobile.

  In the automobile, as shown in FIG. 7, when the engine 1 is rotating, the generator 3 converts the rotational force of the engine 1 into current energy, and supplies the generated electric power to various loads 5. The battery 7 is charged using surplus power.

  Further, the engine 1 of the automobile is started by driving the starter 9. When the starter 9 is driven, a large voltage drop due to an inrush current is involved, so that a sufficient starting voltage needs to be supplied from the battery 7. Therefore, it is important to accurately manage the state of charge (SOC) of the battery 7, that is, the remaining charge of the battery 7, so that the starter 9 can be driven to start the engine 1.

  In general, when the battery 7 is new, the state of charge of the battery 7 can be determined from the output voltage of the battery 7.

  However, the state of charge of the battery 7 varies greatly depending on the deterioration state of the battery 7. The deterioration state of the battery 7 includes various types such as a case where lattice corrosion and sulfation overlap. And, depending on the deterioration situation, the correlation between the actual internal resistance and the open circuit voltage of the battery is deteriorated, and the correlation between the actual internal resistance and the amount of decrease in the battery output voltage at the time of engine start is also deteriorated. There is. Therefore, it is difficult to accurately determine the state of charge (remaining charge) simply by detecting the output voltage of the battery 7 and using the amount of decrease in the output voltage.

  Therefore, the problem to be solved by the present invention is to provide a battery state management device that can easily detect the substantial remaining charge of the battery.

In order to solve the above-mentioned problem, the invention according to claim 1 is a battery state management device that manages the state of a battery of an automobile, and a battery having a different deterioration level from a voltage detection unit that detects an output voltage of the battery. Each shows a relationship between an open-circuit voltage value that is an output voltage in a state where the battery is not substantially discharged and a discharge-time voltage value that is an output voltage of the battery when a predetermined discharge is performed. The first relation information is stored, and for each battery having a different deterioration level, the battery is associated with the open-circuit voltage value of the first relation information and the battery functions in a maximum load state with a new battery as a reference. and a storage means for storing a second relationship information for deriving the charge remaining zero until no fulfill the said second relationship information, for different battery degradation degree, before A straight line connecting a starting point that is zero remaining charge obtained in association with the open circuit voltage value based on the first relationship information and an end point that is initial charge remaining obtained in association with a common maximum open circuit voltage value has the formula, and detects the open-circuit voltage value of the battery in a state in which substantially discharge is not performed through the voltage detecting means, when the discharge of the battery when the predetermined discharge is performed A voltage value is detected via the voltage detection means, and the linear expression in the second relation information corresponding to the degree of deterioration of the battery specified from the discharge voltage value and the open-circuit voltage value is extracted, extracted by using the linear equation, the derive the remaining charge corresponding to the previous KiHiraki discharge voltage value in the first related information, determining means for determining the remaining charge relative to the new battery It is to be prepared.

  Invention of Claim 2 is a battery state management apparatus of Claim 1, Comprising: The said voltage value at the time of discharge is a lower limit voltage value of the said battery at the time of the said predetermined discharge being performed.

  A third aspect of the present invention is the battery state management device according to the first or second aspect, wherein the predetermined discharge is a discharge performed when the engine is started by the starter.

  A fourth aspect of the present invention is the battery state management device according to any one of the first to third aspects, wherein the detected voltage value during discharge is equal to or lower than a predetermined determination necessity threshold voltage. Only in this case, the remaining charge level is determined based on a new battery.

  The battery state management device according to the first aspect of the present invention stores in advance the relationship between the open-circuit voltage value and the discharge voltage value as first relationship information for each battery having a different degree of deterioration, and this first relationship. Second relationship information related to the information is stored in advance, and the remaining charge amount is determined based on the new battery using both the relationship information. A substantial charge remaining amount can be obtained accurately, and the battery state can be accurately managed.

  In the battery state management device according to the second aspect of the invention, since the lower limit voltage value of the battery when the predetermined discharge is performed is used as the discharge voltage value, the discharge voltage value that effectively represents the characteristics of the battery is obtained. It can be acquired easily and reliably.

  In the battery state management device according to the third aspect of the invention, since the predetermined discharge is a discharge performed when the engine is started by the starter, a special discharge for determining the remaining battery charge is applied to the battery. It is not necessary to perform this, and the remaining battery charge can be detected before the start of traveling.

  The battery state management device according to claim 4 determines the remaining charge based on a new battery only when the detected discharge voltage value is equal to or lower than a predetermined determination necessity threshold voltage. Therefore, the reliability of the determination of the remaining charge can be maintained.

<Configuration>
FIG. 1 is a block diagram showing a battery state management device according to an embodiment of the present invention. As shown in FIG. 1, this battery state management device includes a current sensor 11, a voltage sensor (voltage detection means) 13, a processing unit (determination unit) 15, a storage unit (storage unit) 17, and an output unit 19. The state of the battery 21 mounted on the vehicle is managed.

  The current sensor 11 detects a current output from the battery 21, and for example, a shunt resistor is used. The voltage sensor 13 detects the output voltage of the battery 21. The processing unit 15 is an electronic control unit having a function of a computing device that includes a ROM, a RAM, a CPU, and the like, and performs various information processing operations (including control operations) for managing the battery 21. Do. 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 21 and the like. In FIG. 1, reference numeral 23 denotes an ignition switch, and reference numeral 25 denotes a starter.

<Whole predetermined operation>
First, the overall processing operation of the battery state management device will be described with reference to FIG. In step S1, an ignition switch (hereinafter referred to as “IG switch”) 23 is turned on. At this time, the processing unit 15 measures the open circuit voltage value of the battery 21 (output voltage that is not substantially discharged) via the voltage sensor 13. This open circuit voltage value is used for the determination operation in the next step S3. In the subsequent step S2, the starter 25 is driven and an engine (not shown) is started.

  Then, the processing unit 15 performs an engine start-up deterioration determination operation in step S3, and performs an initial charge remaining amount (initial remaining capacity) detection operation in the next step S4. The operations in steps S3 and S4 will be described later.

  Further, the processing unit 15 performs a deterioration determination operation after engine start in the subsequent step S5. In this post-startup deterioration determination operation, a current inflow state to the battery 21 that is 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 21 is determined.

  Moreover, the process part 15 performs charge control (charge remaining amount management of the battery 21) with respect to the battery 21 by continuing step S6. In this charge control, by integrating the measured current values of the current sensor 11, the total amount of current discharged from the battery 21 from a predetermined reference time such as when the engine is started is sequentially detected, and the battery 21 is based on the detection result. The amount of charge to be performed is determined. As a result, the remaining charge of the battery 21 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 S5 and S6 are repeatedly continued until the engine is stopped.

<Deterioration judgment operation at engine start>
The engine start-time deterioration determining operation will be described in step S3 in FIG.

  Prior to the processing operation of the battery state management device shown in FIG. 2, a predetermined reference battery (in this case, a new battery 21) is tested in advance and is actually mounted on the vehicle using the test result. The battery 21 is judged to be deteriorated.

  In the test, the remaining amount of charge of the battery 21 in various deterioration states including a new one is changed variously, and the engine 21 discharges at the time of engine start (predetermined discharge) in each state where the remaining amount of charge differs. ), And the output voltage before and during the discharge of the battery 21 was measured. Then, an open-circuit voltage value (output voltage that is not substantially discharged) before discharging at each engine start in each remaining charge state of each battery 21 having a different deterioration state and discharge at engine start are performed. The relationship with the lower limit voltage value (discharge voltage value) at the time of breakage was investigated. Here, the engine start discharge is a discharge (or an equivalent discharge) that is performed when the starter 25 is driven and the engine is started. The lower limit voltage value is the lowest value when the output voltage of the battery 21 is reduced due to the discharge at the start of the engine. As the output voltage value (discharge voltage value) of the battery 21 detected at the time of engine start-up discharge, in addition to the above-mentioned minimum value of the output voltage, the discharge during the engine start-up discharge period is performed. An output voltage value after a predetermined time has elapsed from the start may be detected and used for determination.

  FIG. 3 is a graph of the test results, and is stored in advance in the storage unit 17 in the form of a data table or approximate expression. The horizontal axis in FIG. 3 corresponds to the open circuit voltage value of the battery 21 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 21 during discharge at engine start in each discharge test. Yes. Further, a curve G1 in FIG. 3 is drawn based on the measurement result of the new battery 21, and the curves G2 to G5 are drawn based on the measurement result of the battery 21 deteriorated by use. Curves G1 to G5 are obtained as a result of tests on the batteries 21 having different deterioration conditions. Among these, the curves G2 to G4 correspond to the battery 21 that has been repeatedly charged and discharged in a manner close to a normal use state, and the use period of the battery 21 becomes longer in the order of the curves G2, G3, and G4, and the deterioration is progressing. . The curve G5 corresponds to the battery 21 that is frequently overcharged. The curves G4 and G5 have different deterioration conditions (deterioration factors), but the degree of deterioration (deterioration degree) is almost the same.

  Specifically, when attention is paid to the curve G1 to which the new battery 21 corresponds, the lower limit voltage value when the engine start-up discharge is performed when the open-circuit voltage value is about 12.9 V (almost fully charged) is about This indicates that the lower limit voltage value when the engine start-up discharge is performed when the open-circuit voltage value is approximately 12.1V is approximately 8.1V. Further, when paying attention to the curve G4 corresponding to the battery 21 that has deteriorated, the lower limit voltage value when the engine start discharge is performed when the open circuit voltage value is about 12.5V is about 8.1V. Show.

  From the graph of FIG. 3, it was found that the corresponding curves G <b> 1 to G <b> 5 are shifted substantially in the right direction (or lower right direction) of the graph as the deterioration of the battery 21 progresses. 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 G5 with respect to the curve G1 increases as the deterioration of the corresponding battery 21 progresses. It turns out that there is a tendency to.

  Therefore, in this embodiment, the new battery 21 corresponds to the point P1 (VO, VL) on the graph of FIG. 3 determined by the open circuit voltage value and the lower limit voltage value of the battery 21 when the engine is discharged at engine start. The deterioration degree of the battery 21 is determined using the shift amount D shifted in the right direction of the horizontal axis with reference to the corresponding point P2 (VN, VL) on the curve G1.

  In order to make this determination, first, information on the curve G1 for a new battery 21 as a reference (that is, first relation information indicating a relation between the open-circuit voltage value (reference open-circuit voltage value) VN and the lower limit voltage value VL). Is stored in the storage unit 17 in advance. As a specific means, a relational expression that approximately represents the curve G as a function with the lower limit voltage value VL as a variable is stored in the storage unit 17, and the lower limit voltage value VL that is a measured value is stored in the relational expression. A structure for substituting a corresponding reference open voltage value VN by substituting, and as a data table, associating a plurality of lower limit voltage values VL provided at predetermined numerical intervals and a plurality of reference open circuit voltage values VN corresponding thereto The reference open voltage value VN corresponding to the measured lower limit voltage value VL is derived using the data table. In this embodiment, for example, the former configuration is adopted. Note that the new battery 21 is not necessarily used as the reference battery, and the battery 21 having the same capability as the new battery may be used as the reference battery. In the above description, the data table is taken as an example, but information such as an approximate expression may be stored in the storage unit 17.

  Specifically, the processing unit 15 measures the open voltage value VO of the battery 21 when the IG switch 23 is turned on (immediately before the engine is started) through the voltage sensor 13 and discharges at the time of engine start. The lower limit voltage value VL of the battery 21 is measured through the voltage sensor 13, and the measured values VO and VL are substituted into the following expression (1) (evaluation expression) for determining deterioration and evaluated. The value Q is calculated, and the deterioration degree of the battery 21 is determined using the evaluation value Q.

  Here, VN in the equation (1) is the open circuit voltage value VN of the new battery 21 given as a function of the lower limit resistance value VL which is a measured value. Information regarding the expressions (1) and (2) is also stored in the storage unit 17 in advance, and the deterioration determination process by the processing unit 15 is performed using the information.

  In equation (1), the difference value (D) between VO and VN is divided by R (VL) even if the degree of deterioration is the same, the difference value increases as the lower limit voltage value VL increases. Since (D) becomes smaller, by dividing and correcting the difference value (D) by the function value R (VL), the difference value (D) substantially changes only depending on the degree of deterioration regardless of the value of the lower limit voltage value VL. The evaluation value Q can be derived. Here, it is assumed that the change mode of the difference value (D) when the lower limit voltage value VL is changed when the degree of deterioration is the same is approximated by a quadratic function of VL, and the function value R (VL) is set. (Refer to the above formula (2)). More specifically, for example, the coefficients C1, C2, and C3 in Expression (2) are set to C1 = 0.088, C2 = −1.36, and C3 = 4.94.

  In this embodiment, the value obtained by dividing the difference value D by the function value R (VL) and raising the value e to the power value is used as the evaluation value Q. However, the difference value D is used as the function value R (VL). ) May be used for deterioration determination as it is, or may be substituted into another evaluation function. For example, an expression function obtained by expanding the power series up to the first or second order from the above equation (1) may be used.

  As a specific example of the evaluation value Q, for example, in the case of a new battery 21 corresponding to the curve G1 in FIG. 3, Q = 1.0, and in the case of the battery 21 corresponding to the curve G2, Q = 0.6. In the case of the battery 21 to which the curve G3 corresponds, Q = 0.4, and in the case of the battery 21 to which the curves G4 and G5 correspond, Q = 0.3. For example, when the evaluation value Q is equal to or less than a predetermined value, it is determined that the battery 21 is deteriorated.

  FIG. 4 is a flowchart regarding deterioration determination processing by the processing unit 15. As the starter 25 is driven in step S2 of FIG. 2 described above, the processing unit 15 performs a start-up deterioration determination process in the procedure shown in FIG. 4 in step S3.

  That is, the processing unit 15 measures the lower limit voltage value VL of the battery 21 when the engine start-up discharge is performed via the voltage sensor 13 (step S11), and the measured lower limit voltage value VL is a predetermined reference. It is determined whether or not the level is lower than the reference level (for example, 9V) (step S12). If the level is lower than the reference level, the process proceeds to step S13 and the deterioration determination process is performed. The process proceeds to the next process (step S4 in FIG. 2) without performing the determination process.

  In the deterioration determination process in step S13, the open circuit voltage value VO measured in step S1 of FIG. 2 and the lower limit voltage value VL measured in step S11 are substituted into the above equation (1) to calculate the evaluation value Q. Based on the evaluation value Q, the deterioration degree of the battery 21 is determined.

<Detection principle of initial charge level>
Next, the detection principle of the initial charge remaining amount (SOC) in step S4 in FIG. 2 will be described. Here, the definition of the initial charge remaining amount (SOC) is treated as a new capacity and a capacity from the full charge until the battery 21 can no longer function as a maximum load state.

  FIG. 5 is a diagram showing the principle of detection of the initial charge remaining amount. FIG. 5A is a diagram of FIG. 3 used in step S3 in FIG. 2 (deterioration determination operation at engine start). The horizontal axis corresponds to the open circuit voltage value of the battery 21 before starting the engine start discharge in each discharge test, and the vertical axis represents the battery 21 during the engine start discharge in each discharge test. Corresponds to the lower limit voltage value. In addition, a curve G1 in FIG. 5A is drawn based on the measurement result of the new battery 21, and the curve G2 is based on the measurement result of the battery 21 that has deteriorated by half due to use. G3 is drawn based on the measurement results for the battery 21 that has deteriorated to 30% remaining due to use. Further, an area ArX in FIG. 5A is a non-restartable area where the starter 25 cannot be driven (that is, the engine cannot be restarted), and the line Vth1 is determined because the initial charge remaining amount is sufficient. Indicates a threshold value (determination necessity threshold voltage) that is unnecessary, and a line Vth2 determines whether the starter 25 can be driven (that is, the engine can be restarted) in consideration of the non-restartable region ArX. A restart determination line (threshold value) is shown. FIG. 5A is stored in the storage unit 17 in a format such as a data table or an approximate expression. In FIG. 5A, only three curves G1 to G3 are drawn, but actually, many curves are drawn together with G1 to G3.

  FIG. 5B shows the initial charge remaining amount (SOC), that is, the role of the battery 21 in the maximum load state for each battery 21 having a different degree of deterioration based on the new and fully charged battery 21. It is a figure of the information (2nd relationship information) which shows the change of the charge remaining until it cannot be fulfilled, a horizontal axis is the initial charge remaining (SOC) of the new battery 21, and a vertical axis is a substantial initial charge remaining. This means an amount (SOC: hereinafter referred to as “actual SOC”), and both the horizontal axis and the vertical axis are shown as percentage (%) values.

  The second relation information shown in FIG. 5B is also stored in advance in a format such as a data table or an approximate expression in the storage unit 17, similarly to the first relation information shown in FIG. Is. The concept of FIG. 5 (B) is shown.

  First, intersections P01 to P03 of all the curves G1 to G3 arranged in FIG. 5A and the restart determination line Vth2 are obtained. For example, for the curve G1 corresponding to the new and fully charged battery 21, the intersection of the curve G1 and the restart determination line Vth2 is a point P01. Therefore, the position on the horizontal axis is applied as it is to the position on the horizontal axis in FIG. 5B, and a point P11 where the vertical axis in FIG. 5B has a zero value is plotted. The coordinates of this point P11 are the origin (0, 0) in FIG.

  Further, for example, for the other curves G2 and G3, intersections P02 and P03 between the curves G2 and G3 and the restart determination line Vth2 are obtained, and the positions on the horizontal axes are left as shown in FIG. Plot points P12 and P13 that are applied to positions on the axis and whose vertical axis in FIG.

  Next, the open-circuit voltage value (about 12.9 V) when the almost new battery 21 is almost fully charged is applied as it is to the position on the horizontal axis of FIG. 5B, and the coordinates of this point are (100, 0). ).

  Then, the coordinate (100, 100) in FIG. 5B is set as a point P21, and a straight line L1 connecting the point P21 and the point P11 is obtained. Similarly, for a curve G2 with a degree of deterioration of half (50%), for example, a point at coordinates (100, 50) is P22. And a straight line L2 connecting the points P22 and P12 and a straight line L3 connecting the points P23 and P13 are obtained. The straight lines L1 to L3 in FIG. 5B are stored in advance in the storage unit 17 in the form of a data table or an approximate expression. As described above, since many curves are drawn in addition to the three curves G1 to G3 in FIG. 5A, the corresponding straight lines are also shown in FIG. ).

<Detection of initial charge level>
As described above, the first relation information in FIG. 5A and the second relation information in FIG. 5B are stored in the storage unit 17 as information for each battery 21 having a different deterioration state. As a premise, an initial charge remaining amount (SOC) detection operation in step S4 in FIG. 2 is executed.

  First, when the lower limit voltage value measured in the above step S11 exceeds a predetermined determination necessity threshold voltage Vth1, the battery 21 is sufficiently charged. Since only the value is a state in which the deterioration state of the battery 21 is difficult to identify, the processing unit 15 determines that the battery is in a sufficiently charged state without performing the subsequent initial charge remaining amount detection operation.

  On the other hand, when the lower limit voltage value measured in step S11 is equal to or lower than the predetermined determination necessity threshold voltage Vth1, the deterioration state of the battery 21 can be identified from the lower limit voltage value and the open-circuit voltage value. 15 executes the following initial charge remaining amount detection operation (step S13).

  Here, the curve of the deterioration state of the battery 21 determined in step S3 is applied as it is. For example, when the curve G2 is applied in the process of step S3 and the point Px is obtained from the open circuit voltage value and the lower limit voltage value in FIG. 5A, the position of the point Px on the horizontal axis. Is directly associated with the position on the horizontal axis in FIG. 5B to obtain a point Py on the straight line L2 corresponding to the curve G2. The value α of the position of the point Py on the vertical axis (actual SOC) is set as the initial charge remaining amount (SOC) of the battery 21. This value α means the capacity until the battery 21 can no longer function in the maximum load state, assuming that the battery 21 is new and fully charged. Therefore, even when the battery 21 is deteriorated, the remaining charge amount based on the new battery 21 can be obtained.

  And the determination result of the charge remaining amount is output via the output part 19 by the output mode shown, for example in FIG. 6 (step S14). For example, in the display unit 31 provided in the output unit 19, a display region 32 for displaying the actual SOC (substantial remaining charge) of the battery 21 is formed, and the actual SOC is displayed in a predetermined manner such as a gauge shape. Is displayed. Further, the deterioration state of the battery 21 determined in step S3 is also displayed in the display areas 33 and 35. For example, the display area 33 is turned on when the deterioration state of the battery 21 is good, and the display area 35 is turned on when the battery 21 is deteriorated below a certain level.

  As described above, in this embodiment, FIGS. 5A to 5B are obtained in advance for various deterioration states and charging states of the battery 21, and the open-circuit voltage value and the lower limit are determined when the starter 25 operates. Since the actual SOC, that is, the remaining charge level based on the new battery 21 can be obtained from the voltage value using FIG. 5B, the substantial remaining charge level can be accurately obtained even if the battery 21 deteriorates. Can get to. Therefore, it is possible to provide a battery state management device that can accurately manage the battery state.

It is a block diagram which shows the battery state management apparatus which concerns on one embodiment of this invention. It is a flowchart which shows the whole process operation | movement of a battery state management apparatus. It is a graph which shows the measurement result which measured the open circuit voltage value and the lower limit voltage value at the time of engine starting by the test about the battery from which a deterioration condition and charge remaining amount differ. It is a flowchart regarding a deterioration determination process. It is a principle figure for demonstrating the detection operation of the initial charge residual amount in the battery state management apparatus which concerns on one embodiment of this invention. It is a figure which shows the example of an output of the determination result of a battery. It is a block diagram which shows the power supply system of a common motor vehicle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Current sensor 13 Voltage sensor 15 Processing part 17 Memory | storage part 19 Output part 21 Battery 23 Switch 25 Starter 31 Display part

Claims (4)

A battery state management device for managing the state of a vehicle battery,
Voltage detecting means for detecting the output voltage of the battery;
For each battery having a different degree of deterioration, an open-circuit voltage value that is an output voltage in a state in which the battery is not substantially discharged, and a discharge-time voltage value that is an output voltage of the battery when a predetermined discharge is performed Is stored in a maximum load state for each battery having a different degree of deterioration, and is associated with the open-circuit voltage value of the first relationship information and based on a new battery. Storage means for storing second relation information for deriving zero remaining charge until the battery can no longer function as a battery ,
The second relation information is for each battery having a different degree of deterioration.
A starting point that is zero charge remaining obtained in association with the open circuit voltage value based on the first relation information and an end point that is initial charge remaining obtained in association with a common maximum open circuit voltage value are connected. Has a linear formula,
The open circuit voltage value of the battery is detected through the voltage detection means in a state where the discharge is not substantially performed, and the voltage value at the time of discharge of the battery when the predetermined discharge is performed is the voltage. The linear equation in the second relation information detected by the detection means and extracted from the voltage value at the time of discharge and the degree of deterioration of the battery specified from the open-circuit voltage value is extracted, and the extracted linear equation using said derive the remaining charge corresponding to the previous KiHiraki discharge voltage value in the first related information, battery status management and a determining means for determining the remaining charge relative to the new battery apparatus. The battery state management device according to claim 1,
The battery voltage management device according to claim 1, wherein the discharging voltage value is a lower limit voltage value of the battery when the predetermined discharging is performed. The battery state management device according to claim 1 or 2,
The battery state management device according to claim 1, wherein the predetermined discharge is a discharge performed when the engine is started by a starter. The battery state management device according to any one of claims 1 to 3,
A battery state management device that determines a remaining charge level based on a new battery only when the detected voltage value during discharge is equal to or lower than a predetermined determination necessity threshold voltage.

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