JP2007322171A - Battery state estimation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery state estimation device capable of estimating an exact state of a battery. <P>SOLUTION: In this estimation device, a storage part 12 stores a characteristic pattern 12a indicating a relation between reference release voltage values of a reference battery under a plurality of charged conditions including a full charge condition and an overcharge condition, and a difference value between the reference release voltage values and reference discharge voltage values under a discharged condition connected to electric loads. A voltage detecting part 13 detects the release voltage values and the discharge voltage values of the battery 20 under the conditions connected and not connected to the electric loads 31, 32 etc., and a voltage-drop amount calculating part 11a calculates the deference value between the voltages under the both conditions. The reference release voltage value corresponding to the calculated difference value is drawn out based on the characteristic pattern 12a, and a deterioration degree calculating part 11b calculates a deterioration degree of the battery, based on the reference release voltage value, the release voltage value and the full-charge reference release voltage value under the full charge condition of the reference battery stored in the storage part 12. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a battery state estimation device that estimates a state of a battery.

Relationship information indicating the relationship between the reference open circuit voltage value of a reference battery (new battery) serving as a reference and the lower limit voltage value when discharging at engine start is stored in advance in a storage unit and mounted in a vehicle. The open circuit voltage value and the lower limit voltage value when the discharged battery is discharged at engine start are measured, the reference open circuit voltage value of the reference battery corresponding to the lower limit voltage value is derived based on the relationship information, and the open circuit voltage A technique for determining the degree of deterioration of a battery based on a difference between a value and a derived reference open-circuit voltage value is disclosed (see Patent Document 1). By using such a technique, it is possible to accurately determine the deterioration regardless of the deterioration state of the battery.
JP 2006-15914 A

  However, as shown in FIG. 9, the technique disclosed in Patent Document 1 is deteriorated by an index in which an open voltage value VO is applied to the horizontal axis and a lower limit voltage value (discharge voltage value) VL during discharge is applied to the vertical axis. Since the determination is made, two components, the voltage drop component accompanying discharge and the internal resistance rise component are mixed on the vertical axis, and the reference line for deterioration determination becomes a left-down line, which is complicated to handle. There was a problem.

  The present invention has been made in view of such circumstances, and has made the handling of a reference line for battery state estimation (degradation level and / or remaining capacity) extremely simple, and has made accurate battery state estimation. An object of the present invention is to provide a battery state estimation device that can be performed.

  A battery state estimation device according to a first invention is a battery state estimation device that estimates a state of a battery, and is connected to a reference open voltage value in a plurality of discharge states including a full charge state and an overdischarge state, and an electric load. Storage means for storing relationship information indicating a relationship between a reference discharge voltage value in each discharge state and a difference value between the reference open voltage values, and an open voltage value and an electric load of the battery in a state where the electric load is not connected. Detecting means for detecting a discharge voltage value of the battery in a connected state; difference value calculating means for calculating a difference value between the open-circuit voltage value and the discharge voltage value detected by the detecting means; and the difference value A reference open-circuit voltage value corresponding to the difference value calculated by the calculation unit is derived based on the relationship information, and the derived reference open-circuit voltage value is stored by the storage unit Fully charged during the reference open circuit voltage value in a charged state, and based on the detected open-circuit voltage value by the detecting means, characterized by comprising a deterioration degree calculating means for calculating a degree of deterioration of the battery.

  In the first invention, a reference open voltage value in a plurality of discharge states including a fully charged state and an overdischarge state such as a reference battery in which the connection of the electric load is substantially opened, and the reference open voltage value and the electric load The relation information indicating the relation with the difference value with the reference discharge voltage value in each discharge state to which is connected is stored. Then, an open-circuit voltage value and a discharge voltage value, which are output voltages of the estimation target battery in a state where the electric load is connected and a state where the electric load is not connected, are detected, and the output voltage (open-circuit voltage value and discharge) in both states is detected. The difference value of the voltage value is calculated. Further, a reference open-circuit voltage value corresponding to the calculated difference value is derived based on the related information, and the derived reference open-circuit voltage value, the reference open-circuit voltage value in the fully charged state (full-charge reference open-circuit voltage value), and detection Based on the open circuit voltage value, the degree of deterioration of the battery is calculated.

  The battery state estimation device according to a second aspect of the present invention includes a difference value between a reference open voltage value at full charge and a reference open voltage value corresponding to the difference value calculated by the difference value calculation means, and the reference open at full charge. A ratio calculating means for calculating a ratio between a voltage value and a difference value between the open-circuit voltage values detected by the detecting means; an overdischarge in the overdischarge state stored by the full-charge reference open-circuit voltage value and the storage means; An open-circuit voltage value in which the ratio between the difference value of the hour reference open-circuit voltage value and the difference value with respect to the full-charge reference open-circuit voltage value is equal to the ratio calculated by the ratio calculation means is calculated as the overdischarge open-circuit voltage value. Overdischarge open-circuit voltage value calculation means, overdischarge open-circuit voltage value calculated by the overdischarge open-circuit voltage value calculation means, full-charge reference open-circuit voltage value, and open-circuit detected by the detection means Based on voltage value , And further comprising a remaining capacity calculating means for calculating the remaining capacity of the battery.

  In the second invention, the difference value of the reference open circuit voltage value corresponding to the difference value calculated by the full charge reference open circuit voltage value and the difference value calculation means, and the full open reference open voltage value and the detection means The first ratio with the difference value of the open circuit voltage value detected in this way is calculated. Next, an open-circuit voltage in which a second ratio between the difference value between the full-charge reference open-circuit voltage value and the over-discharge reference open-circuit voltage value in the over-discharge state and the full charge reference open-circuit voltage value is equal to the first ratio. The value is calculated as the open-circuit voltage value during overdischarge. Then, the remaining battery capacity is calculated based on the calculated overdischarge open-circuit voltage value, the full-charge reference open-circuit voltage value, and the open-circuit voltage value detected by the detection means.

  A battery state estimation device according to a third aspect of the present invention is a battery state estimation device that estimates the state of a battery, to which a reference open voltage value in a plurality of discharge states including a full charge state and an overdischarge state and an electric load are connected. Storage means for storing relationship information indicating a relationship between a reference discharge voltage value in each discharge state and a difference value between the reference open voltage values, and an open voltage value and an electric load of the battery in a state where the electric load is not connected. Detection means for detecting a discharge voltage value of the battery in a connected state, difference value calculation means for calculating a difference value between the open-circuit voltage value and the discharge voltage value detected by the detection means, and the storage means The reference open voltage value at full charge in the fully charged state stored by the difference value of the reference open voltage value corresponding to the difference value calculated by the difference value calculation means and Ratio calculation means for calculating a ratio between the full-charge reference open-circuit voltage value and the difference value of the open-circuit voltage value detected by the detection means, and the full-charge reference open-circuit voltage value and the storage means When the overdischarge state is the overvoltage state, the ratio between the difference value of the reference open circuit voltage value at the time of overdischarge and the difference value with respect to the reference open voltage value at the time of full charge is equal to the ratio calculated by the ratio calculation means. Overdischarge open-circuit voltage value calculating means for calculating as an open-circuit voltage value, overdischarge open-circuit voltage value calculated by the overdischarge open-circuit voltage value calculating means, the full-charge reference open-circuit voltage value, and the detecting means And a remaining capacity calculating means for calculating the remaining capacity of the battery based on the open circuit voltage value detected in step (1).

  In the third invention, a reference open voltage value in a plurality of discharge states including a fully charged state and an overdischarge state such as a reference battery in which the connection of the electric load is substantially opened, and the reference open voltage value and the electric load The relation information indicating the relation with the difference value with the reference discharge voltage value in each discharge state to which is connected is stored. Then, an open-circuit voltage value and a discharge voltage value, which are output voltages of the estimation target battery in a state where the electric load is connected and a state where the electric load is not connected, are detected, and the output voltage (open-circuit voltage value and discharge) in both states is detected. The difference value of the voltage value is calculated. Next, the reference open voltage value in the fully charged state (reference open voltage value at full charge) and the difference value of the reference open voltage value corresponding to the calculated difference value, the reference open voltage value at full charge and the detection means A first ratio with the difference value of the detected open-circuit voltage value is calculated. Next, an open-circuit voltage in which a second ratio between the difference value between the full-charge reference open-circuit voltage value and the over-discharge reference open-circuit voltage value in the over-discharge state and the full charge reference open-circuit voltage value is equal to the first ratio. The value is calculated as the open-circuit voltage value during overdischarge. Then, the remaining battery capacity is calculated based on the calculated overdischarge open-circuit voltage value, the full-charge reference open-circuit voltage value, and the open-circuit voltage value detected by the detection means.

  According to the present invention, since the battery state is estimated from the difference value (that is, the voltage drop amount) between the open-circuit voltage value and the discharge voltage value, unlike the conventional index using the discharge voltage value, Therefore, the battery state estimation can be accurately performed even though the handling of the reference line for the battery state estimation is extremely simple.

  According to the present invention, the reference open-circuit voltage value corresponding to the difference value between the open-circuit voltage value and the discharge voltage value of the battery when the electric load is connected and when the electric load is not connected, and the full-charge state Since the battery deterioration level is calculated based on the reference open voltage value during charging and the battery open voltage value when the electric load is not connected, the battery deterioration level can be obtained through extremely simple arithmetic processing. Can do.

  According to the present invention, the difference value of the reference open circuit voltage value corresponding to the difference value calculated by the full charge reference open circuit voltage value and the difference value calculation means, and the full charge reference open circuit voltage value and the detection means are detected. The first ratio with the difference value of the open circuit voltage value calculated, the difference value between the reference open voltage value at full charge and the reference open voltage value at over discharge in the overdischarge state, and the difference with respect to the reference open voltage value at full charge An open-circuit voltage value in which the second ratio to the value is equal to the first ratio is calculated as an over-discharge open-circuit voltage value. Since the remaining battery capacity is calculated based on the calculated overdischarge open-circuit voltage value, the full-charge reference open-circuit voltage value, and the open-circuit voltage value detected by the detection means, an extremely simple calculation process is performed. As a result, the remaining capacity of the battery can be obtained.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof.

FIG. 1 is a block diagram showing a battery state estimating apparatus according to the present invention.
In the present embodiment, a mode for estimating the state (degradation level and remaining capacity) of the battery 20 mounted on the vehicle will be described. A starter 30 and electrical loads 31, 32,... Are connected to the battery 20 via the switching units 14, 15, and power is supplied to the electrical loads 31, 32,. Be controlled.

The battery state estimation device according to the present invention includes a control unit 11, a storage unit 12, a voltage detection unit 13, and a display unit 40.
The storage unit 12 is a non-volatile flash memory for storing various types of information, and the storage unit 12 has a reference release that is an output voltage of the reference battery in a state where the electrical loads 31, 32,. The relationship between the voltage value VOS and the difference value (reference voltage drop ΔVS) between the reference discharge voltage value VLS and the reference open-circuit voltage value VOS, which is the output voltage of the reference battery in a state where the electrical loads 31, 32,. The relationship information (characteristic pattern) 12a to be shown is stored. The characteristic pattern 12a is derived by performing voltage measurement on a reference battery serving as a reference of the battery 20 in a plurality of discharge states including a full charge state and an overdischarge state. Here, the reference battery is, for example, a new battery (substantially a new battery (same below)).

  The voltage detector 13 is a voltmeter that detects the output voltage of the battery 20, and detects an open voltage value VO that is an output voltage of the battery 20 in a state where the electric loads 31, 32,. A discharge voltage value VL that is an output voltage of the battery 20 in a state where 31, 32,... Are connected is detected.

  The connection between the electric loads 31, 32,... And the battery 20 is controlled by the switching unit 14. When the switching unit 14 is turned on, the electrical loads 31, 32,... Are connected to the battery 20, and when the switching unit 14 is turned off, the electrical loads 31, 32,.

The control unit 11 includes a voltage drop amount calculation unit 11a, a deterioration degree calculation unit 11b, and a remaining capacity calculation unit 11c.
The voltage drop amount calculation unit 11a calculates a voltage drop amount ΔV by subtracting the discharge voltage value VL from the open circuit voltage value VO of the battery 20 detected by the voltage detection unit 13.

  The deterioration degree calculation unit 11b derives the reference open circuit voltage value VOS of the reference battery corresponding to the voltage drop amount ΔV calculated by the voltage drop amount calculation unit 11a from the characteristic pattern 12a. Further, the reference open voltage value VOSF at the time of full charge in the fully charged state of the reference battery is read from the characteristic pattern 12a stored in the storage unit 12. Then, based on the derived reference open-circuit voltage value VOS, the full-charge reference open-circuit voltage value VOSF, and the open-circuit voltage value VO detected by the voltage detection unit 13, the deterioration degree SOH (State Of Health) of the battery 20 with respect to the reference battery is calculated. calculate.

  The remaining capacity calculation unit 11c derives the reference open circuit voltage value VOS of the reference battery corresponding to the voltage drop amount ΔV calculated by the voltage drop amount calculation unit 11a from the characteristic pattern 12a, and at the same time the full charge state of the reference battery in the fully charged state. The reference open voltage value VOSF at the time of charging is read from the characteristic pattern 12a. Then, the ratio R1 between the difference value between the reference open voltage value VOSF at full charge and the reference open voltage value VOS and the difference value between the reference open voltage value VOSF at full charge and the open voltage value VO detected by the voltage detection unit 13 is calculated. calculate.

  Next, the remaining capacity calculation unit 11c reads the overdischarge reference open voltage value VOSE from the characteristic pattern 12a in the overdischarge state of the reference battery, and sets the full charge reference open voltage value VOSF and the overdischarge reference open voltage value VOSE. An open-circuit voltage value VOP (corresponding to the over-discharge open-circuit voltage value of the battery 20) at which the ratio R2 between the difference value and the differential value with respect to the full-charge reference open-circuit voltage value VOSF is equal to the ratio R1 is calculated. The remaining capacity calculation unit 11c then calculates the remaining capacity SOC (State of the battery 20) based on the calculated open-circuit voltage value VOP, the full-charge reference open-circuit voltage value VOSF, and the open-circuit voltage value VO detected by the voltage detection unit 13. Of Charge) is calculated.

  The display unit 40 is for displaying the calculated degree of degradation SOH and the remaining capacity SOC and allowing the user to grasp the state of the battery 20.

  Next, a method for estimating the state (degradation level and remaining capacity) of the battery 20 will be described in detail. FIG. 2 is a graph showing the correlation between the open-circuit voltage of the battery and the difference value between the open-circuit voltage and the discharge voltage, which is the lower limit voltage at engine start. Specifically, in a battery having a different degree of deterioration and remaining capacity, an open circuit voltage value VO before starting discharge at engine start and a discharge voltage value VL at engine start are measured by a test, and the open circuit voltage value VO and the discharge voltage value are measured. A voltage drop amount ΔV that is a difference value of VL is calculated, and the open voltage value VO is plotted on the horizontal axis and the voltage drop amount ΔV is plotted on the vertical axis. As shown in FIG. 3, the open circuit voltage value VO is the output voltage of the battery 20 when the battery 20 is not substantially discharged, and the discharge voltage value VL is the output voltage of the battery 20 due to the discharge at the start of the engine. It is the minimum voltage when it drops.

  In FIG. 2, G1 indicates a new battery, G2 to G4 indicate curves for a battery that has been used and deteriorated to some extent, and the deterioration of the battery proceeds in the order of curves G2, G3, and G4. It should be noted that, by measuring the open circuit voltage after a certain period of time rather than measuring the open circuit voltage immediately after the end of charging (when the engine is stopped), the accuracy of obtaining the discharge characteristics and estimating the state of the battery 20 is further improved.

  It can be seen that the corresponding curves G1 to G4 are shifted substantially to the right (upper right) of the graph according to the deterioration of the battery 20. From this, if the discharge characteristics at the time of engine start of a new battery corresponding to the curve G1 (the amount of voltage drop due to discharge at the time of engine start with respect to each discharge voltage value corresponding to each remaining charge amount) are stored, this is used as a reference. As a result, the state of the battery 20 can be estimated.

  FIG. 4 is a circuit diagram schematically showing the relationship between the electric load connected to the battery and the internal resistance of the battery. The resistance value of the electrical loads 31, 32,... (Loads other than the internal resistance of the battery 20) connected to the battery 20 when the engine is started is RS, the internal resistance value of the battery 20 is RB, and the open-circuit voltage value of the battery 20 is When VO is set, VL is a discharge voltage value when the electric load 31, 32,... Is connected to the battery 20 and discharge is performed, and ΔV is a difference value between the open-circuit voltage value and the discharge voltage value, these parameters RS, The following relationship holds between RB, VO, and VL.

  ΔV / VO = (VO−VL) / VO = RB / (RB + RS) (Formula 1)

  Since the internal resistance value RB in Equation 1 increases as the open-circuit voltage value VO decreases, the difference value (voltage drop amount ΔV) between the open-circuit voltage value VO and the discharge voltage value VL is the open-circuit voltage value VO as shown by the curve G1. It increases with decreasing. That is, the amount of deviation in the positive direction of the vertical axis from the straight line G5 of the curve G1 in FIG. 2 gradually increases as the open circuit voltage value VO decreases. It can be said that this is due to the increase.

  When the battery is in a new state, such as when the vehicle is assembled at the factory, the battery when the open circuit voltage value (reference open circuit voltage value) VOS and the electrical loads 31, 32,. Discharge voltage value (reference discharge voltage value) VLS is measured, and a difference value (voltage drop amount ΔVS) between the reference open circuit voltage value VOS and the reference discharge voltage value VLS is calculated. Note that by measuring the reference open voltage value VOS and the reference discharge voltage value VLS a plurality of times and using an average of them, it is possible to reduce measurement errors and obtain accurate discharge characteristics.

  The plurality of discharge states described above include a full charge state and an overdischarge state, and a reference open voltage value (reference open voltage value VOSF at full charge) when the battery is in a full charge state and a reference discharge voltage. Value (full charge reference discharge voltage value VLSF) is calculated, a difference value (voltage drop amount ΔVSF) between the full charge reference open voltage value VOSF and the full charge reference discharge voltage value VLSF is calculated, and the battery is overcharged. The reference open voltage value (reference discharge voltage value VOSE during overdischarge) and the reference discharge voltage value (reference discharge voltage value VLSE during overdischarge) when the battery is in the discharge state are measured, and the reference open voltage value VOSE during overdischarge and A difference value (voltage drop amount ΔVSE) of the reference discharge voltage value VLSE during overdischarge is calculated. Whether or not the battery is fully charged is determined by, for example, measuring the open-circuit voltage value of the battery and determining whether or not the value is equal to or higher than a predetermined reference level corresponding to the fully charged state. Is called.

  Further, the relationship between the reference open circuit voltage value VOS of a new battery and the voltage drop amount ΔVS in a plurality of discharge states obtained by measurement as described above is stored as a characteristic pattern 12a. This characteristic pattern 12a may be stored as a data table as shown in FIG. 5, or may be stored as a mathematical expression indicating the relationship between the reference open circuit voltage value VOS and the voltage drop amount ΔVS.

  When the deterioration state of the battery 20 is estimated, the open circuit voltage value VO before the electric loads 31, 32,. .. Are measured with an open circuit voltage value VL which is a lower limit voltage when connected to the battery 20, and a difference value (voltage drop amount ΔV) between the open circuit voltage value VO and the discharge voltage value VL is calculated. At this time, the remaining charge of the battery 20 does not have to be in a fully charged state, and may be in an arbitrary discharged state.

  Next, a corresponding reference open circuit voltage value VOSR corresponding to the reference voltage drop amount ΔVS equal to the voltage drop amount ΔV is derived based on the characteristic pattern 12a. That is, the reference open circuit voltage value VOS when the voltage drop amount on the curve G1 in FIG. 6 is equal to the voltage drop amount ΔV is derived as the corresponding reference open circuit voltage value VOSR. When the characteristic pattern 12a is prepared as a discretized data table as in this example, the corresponding reference open voltage value VOSR corresponding to the reference voltage drop amount ΔVS (that is, the voltage drop amount ΔV) is displayed in the characteristic pattern 12a. If not, the corresponding reference open voltage value VOSR is derived by appropriate interpolation processing.

  Note that the values VOSF and ΔVSF in FIG. 6 correspond to the open voltage value and voltage drop value of the new battery in the fully charged state, and the values VOSE and ΔVSE correspond to the open voltage value and voltage drop value of the new battery in the overdischarge state. ing.

  Then, the full charge reference open voltage value VOSF and the voltage drop ΔVSF stored as the characteristic pattern 12a are read, and the difference value D1 between the full charge reference open voltage value VOSF and the corresponding reference open voltage value VOSR is By comparing the difference value D2 between the reference open circuit voltage value VOSF and the open circuit voltage value VO, the degree of deterioration of the battery 20 at that time is calculated. For example, the ratio of the difference value D2 to the difference value D1 is calculated as the degree of deterioration.

  The deterioration degree estimation method as described above is such that the battery 20 shifts substantially to the left (downward to the left) so that the measurement point P11 (VO, ΔV) on the graph approaches the curve G1 as the deterioration degree of the battery 20 decreases. It uses characteristics. That is, as the deterioration degree of the battery 20 is smaller, the measurement point P11 (VO, ΔV) in FIG. 6 is closer to the coordinate point P12 on the corresponding curve G1, and the battery is based on the degree of approach of the measurement point P11 to the coordinate point P12. A degree of degradation of 20 is estimated.

  Furthermore, the remaining capacity of the battery 20 can be calculated by the same estimation method as the degree of deterioration. First, in a state where the use of the battery 20 is started, the open circuit voltage value VO that is the open circuit voltage before the electrical loads 31, 32,... Are connected to the battery 20 and the electrical loads 31, 32,. An open-circuit voltage value VL that is a lower limit voltage when connected to is measured, and a difference value (voltage drop amount ΔV) between the open-circuit voltage value VO and the discharge voltage value VL is calculated. At this time, the deterioration state of the battery 20 does not need to be equivalent to a new one, and may be an arbitrary deterioration state.

  Then, a corresponding reference open circuit voltage value VOSR corresponding to the reference voltage drop amount ΔVS equal to the voltage drop amount ΔV is derived based on the characteristic pattern 12a. The processing so far is the same as the method for estimating the degree of deterioration of the battery 20 described above, and the corresponding reference open-circuit voltage value VOSR derived when the degree of deterioration is estimated is appropriately stored in the memory, so that the processing is repeated. Can be prevented.

  Then, the full charge reference open voltage value VOSF and the voltage drop ΔVSF stored as the characteristic pattern 12a are read, and the difference value D1 between the full charge reference open voltage value VOSF and the corresponding reference open voltage value VOSR is A ratio R1 of the difference value (D2) between the reference open circuit voltage value VOSF and the open circuit voltage value VO is calculated.

  Next, the overdischarge reference open voltage value VOSE and the voltage drop ΔVSE stored as the characteristic pattern 12a are read from the characteristic pattern 12a, and the difference between the full charge reference open voltage value VOSF and the overdischarge reference open voltage value VOSE. The open-circuit voltage value VOP is calculated such that the ratio R2 between the value and the difference value with respect to the full-charge reference open-circuit voltage value VOSF is equal to the ratio R1. This open-circuit voltage value VOP corresponds to an overdischarge closed / closed voltage value.

  Then, by comparing the difference value D3 between the full charge reference open circuit voltage value VOSF and the overdischarge open circuit voltage value VOP and the open voltage value VO and the overdischarge open circuit voltage value VOP, The remaining capacity of the battery 20 is calculated. For example, the ratio of the difference value D4 to the difference value D2 is calculated as the remaining capacity.

  In the remaining capacity estimation method as described above, as the remaining capacity of the battery 20 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 FIG. This is based on the battery characteristic of approaching from the coordinate point P22 side corresponding to the fully charged state to the coordinate point P23 side corresponding to the overdischarged state.

Next, the operation of the battery state estimation device having the above-described configuration will be described. FIG. 7 is a flowchart showing a processing procedure of the battery state estimation apparatus according to the present invention.
First, when an ignition key (hereinafter referred to as an IG key) 50 is turned on (step S1), the control unit 11 controls the switching unit 14 to be turned off to cut off the electric loads 31, 32,. An open circuit voltage value VO is detected (step S2). It should be noted that the load cutting process is not required in the form in which the electrical loads 31, 32,... Are disconnected in the initial state.

  Then, the control unit 11 controls the switching unit 14 to turn on to connect the electric loads 31, 32,..., And when the starter 30 starts an engine (not shown) (step S3), the voltage of the battery 20 The detection is continuously performed, and the lower limit voltage value of the detection voltage is detected as the discharge voltage value VL (step S4). The voltage of the battery 20 drops to the discharge voltage value VL when the engine is started. However, since the voltage gradually recovers in about several seconds, the period for performing continuous voltage detection may be about several seconds in which the voltage is recovered. .

  Then, a voltage drop amount ΔV that is a difference value between the open circuit voltage value VO and the discharge voltage value VL is calculated (step S5). Then, the above-described deterioration degree calculation process for the battery 20 is performed based on the voltage drop amount ΔV (step S6), and the remaining capacity calculation process for the battery 20 is further performed (step S7). Note that the deterioration degree of the battery 20 is very small in the time level, so that the deterioration degree calculation process is sufficient at one time. However, since the remaining capacity of the battery 20 changes every moment, the remaining capacity calculation is performed. The remaining capacity is monitored by performing processing at appropriate intervals. In this way, the processes in S6 and S7 are repeated until the engine is stopped.

  The state of the battery 20 calculated by the above-described processes is displayed on the display unit 40 in a level-divided manner as shown in FIG. For example, when the battery 20 has no problem of deterioration, the display area 40a indicating that the battery 20 is good is turned on, and when the battery 20 is deteriorated, the display area 40b indicating that attention is required is turned on. . The display unit 40 is also provided with a display area 40 c for displaying the remaining capacity of the battery 20. In this way, the user can easily grasp the deterioration degree and remaining capacity of the battery 20. Further, since the state of the battery 20 is estimated based on the reference open voltage value VOS corresponding to the voltage drop amount ΔV that is the difference value between the open circuit voltage value VO and the discharge voltage value VL at the time of evaluation, the voltage drop amount ΔV is Even if it is an arbitrary value, the deterioration degree and remaining capacity of the battery 20 can be accurately estimated.

  Note that, by monitoring the remaining capacity of the battery 20, the remaining capacity of the battery 20 during traveling is grasped, and, for example, the power generation amount (output voltage, etc.) of an alternator not shown is maintained so that the remaining capacity is maintained within a predetermined range. ) Can be controlled.

  As described above, since the state of the battery 20 is estimated based on the voltage drop amount ΔV that is the difference value between the open circuit voltage value VO and the discharge voltage value VL, the conventional open circuit voltage value VO and discharge voltage value VL are applied. Unlike the index, handling of the reference line for estimating the state of the battery 20 is extremely simple, and the state of the battery 20 can be estimated accurately.

  Further, the deterioration degree and remaining capacity of the battery 20 can be obtained by extremely simple arithmetic processing. For this reason, the time required for the arithmetic processing is short, and the state of the battery 20 can be constantly monitored. Therefore, it is suitable for power management that controls the switching unit 15 to control the connection of the electrical loads 31, 32,.

  Note that a temperature sensor that measures the temperature of the battery 20 may be added to the apparatus configuration of FIG. 1 to perform state estimation in consideration of the temperature of the battery 20. More specifically, for example, two-dimensional coordinate information representing the relationship between the open-circuit voltage of the reference battery and the voltage drop amount at each temperature (in this case, it can also be referred to as three-dimensional coordinate information when the temperature is included) is derived. Then, based on this, the state is estimated at the current temperature, or the value of parameters (such as open-circuit voltage) depending on the temperature is corrected (for example, corrected to the value of the standard temperature) to estimate the state. May be.

It is a block diagram which shows the battery state estimation apparatus which concerns on this invention. It is a graph which shows the correlation with the open circuit voltage of a battery, the open circuit voltage, and the difference value of the discharge voltage which is the minimum voltage at the time of engine starting. 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 electrical load connected to a battery, and the internal resistance of a battery. It is a figure which shows an example of a characteristic pattern (related information). It is a graph for demonstrating the estimation method which estimates the state (deterioration degree and remaining capacity) of a battery. It is a flowchart which shows the process sequence of the battery state estimation apparatus which concerns on this invention. It is a figure which shows the example of an output of the battery state estimation result. It is a graph for demonstrating the parameter | index used for the conventional battery state estimation method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Control part 11a Voltage drop amount calculation part 11b Deterioration degree calculation part 11c Remaining capacity calculation part 12 Storage part 12a Characteristic pattern (related information)
DESCRIPTION OF SYMBOLS 13 Voltage detection part 14,15 Switching part 20 Battery 30 Starter 31, 32, ... Electric load 40 Display part 50 Ignition key (IG key)

Claims (3)

A battery state estimation device for estimating a battery state,
Relationship information indicating the relationship between the reference open voltage value in a plurality of discharge states including a full charge state and an overdischarge state, the reference discharge voltage value in each discharge state to which an electric load is connected, and the difference value of the reference open voltage value Storage means for storing
Detecting means for detecting an open voltage value of the battery in a state where the electric load is not connected and a discharge voltage value of the battery in a state where the electric load is connected;
Difference value calculating means for calculating a difference value between the open circuit voltage value and the discharge voltage value detected by the detecting means;
A reference open-circuit voltage value corresponding to the difference value calculated by the difference value calculation means is derived based on the relationship information, and the derived reference open-circuit voltage value, when fully charged in the fully charged state stored by the storage means A battery state estimation device comprising: a deterioration degree calculating means for calculating a deterioration degree of the battery based on a reference open voltage value and an open voltage value detected by the detecting means. A difference value between the reference open voltage value at full charge and a reference open voltage value corresponding to the difference value calculated by the difference value calculation means, the reference open voltage value at full charge and the detection means detected by the detection means A ratio calculating means for calculating a ratio of the difference value between the open circuit voltage values;
A ratio between a difference value between the full-charge reference open-circuit voltage value and an over-discharge reference open-circuit voltage value in the over-discharge state stored by the storage means and a difference value with respect to the full-charge reference open-circuit voltage value is the ratio calculation. An overdischarge open-circuit voltage value calculating means for calculating an open-circuit voltage value equal to the ratio calculated by the means as an overdischarge open-circuit voltage value;
Based on the overdischarge open-circuit voltage value calculated by the overdischarge open-circuit voltage value calculation means, the full-charge reference open-circuit voltage value, and the open-circuit voltage value detected by the detection means, the remaining battery level is determined. The battery state estimation apparatus according to claim 1, further comprising: a remaining capacity calculation unit that calculates a capacity. A battery state estimation device for estimating a state of a battery,
Relationship information indicating the relationship between the reference open voltage value in a plurality of discharge states including a full charge state and an overdischarge state, the reference discharge voltage value in each discharge state to which an electric load is connected, and the difference value of the reference open voltage value Storage means for storing
Detecting means for detecting an open voltage value of the battery in a state where the electric load is not connected and a discharge voltage value of the battery in a state where the electric load is connected;
Difference value calculating means for calculating a difference value between the open circuit voltage value and the discharge voltage value detected by the detecting means;
The reference open voltage value at full charge in the fully charged state stored by the storage means and the difference value of the reference open voltage value corresponding to the difference value calculated by the difference value calculation means, and the reference open voltage at full charge A ratio calculating means for calculating a ratio between the value and the difference value of the open circuit voltage value detected by the detecting means;
A ratio between a difference value between the full-charge reference open-circuit voltage value and an over-discharge reference open-circuit voltage value in the over-discharge state stored by the storage means and a difference value with respect to the full-charge reference open-circuit voltage value is the ratio calculation. An overdischarge open-circuit voltage value calculating means for calculating an open-circuit voltage value equal to the ratio calculated by the means as an overdischarge open-circuit voltage value;
Based on the overdischarge open-circuit voltage value calculated by the overdischarge open-circuit voltage value calculation means, the full-charge reference open-circuit voltage value, and the open-circuit voltage value detected by the detection means, the remaining battery level is determined. A battery state estimation device comprising: a remaining capacity calculation unit that calculates a capacity.

Images