JP2007230465A - Battery capacity detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automatically detect the battery capacity of a battery mounted on a vehicle. <P>SOLUTION: The battery capacity detection device is provided with a current sensor 3 for detecting an output current of the battery B; a charge remaining degree detection means 7a for detecting a battery charge remaining degree of the battery B at starting of an engine of the vehicle; a detection means 7b for detecting whether or not the battery charge remaining degree of the battery B reaches to a predetermined battery charge remaining degree; a current integration means 7c for integrating a current amount detected by a current sensor 3 until it is detected that the battery charge remaining degree of the battery reaches to the predetermined battery charge remaining degree by the detection means 7b from starting of the engine; and a battery capacity detection means 7d for detecting a battery capacity of the battery B based on an integrated current amount integrated by a difference value of the predetermined battery charge remaining degree and the battery charge remaining degree at starting of the engine detected by the charge remaining degree detection means 7a and the current integration means 7c. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a battery capacity detection device that detects the battery capacity of a battery mounted on a vehicle.

  In recent years, there has been proposed a battery state management device that detects a current battery remaining capacity of a battery mounted on a vehicle and performs battery state management based on the current battery remaining capacity.

  At that time, the current remaining battery capacity is detected as follows. That is, the remaining battery charge at the time of starting the engine is added to the battery capacity of the battery set in advance to obtain the remaining battery capacity at the time of starting the engine, and the output of the battery detected by the current sensor is calculated as the remaining battery capacity. By accumulating the current, the current remaining battery capacity is detected.

  In the above battery state management device, the remaining battery capacity at the present time is detected as described above, and therefore it is necessary to set the battery capacity of the battery mounted on the vehicle in advance.

  Therefore, every time a battery mounted on a vehicle is replaced with a battery having a different battery capacity, there is a drawback that it is necessary to manually reset the battery capacity, and a battery whose battery capacity is unknown cannot be mounted.

  Accordingly, an object of the present invention is to provide a battery capacity detection device that automatically detects the battery capacity of a battery mounted on a vehicle.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a battery capacity detection device for detecting a battery capacity of a battery mounted on a vehicle, wherein the current sensor detects an output current of the battery, and the vehicle. A remaining charge detection means for detecting a remaining battery charge level of the battery at the time of starting the engine, a detecting means for detecting whether or not the remaining battery charge level of the battery has reached a predetermined remaining battery charge level, A current that integrates the amount of current detected by the current sensor from when the engine is started until the detection means detects that the remaining battery charge level of the battery has reached the predetermined remaining battery charge level A difference value between the integration means, the predetermined remaining battery charge level and the remaining battery charge level at the time of starting the engine detected by the remaining charge level detection means, and the power Based on the integrated current amount of integrated by the integrating means, a battery capacity detection means for detecting a battery capacity of the battery, but with a.

  According to a second aspect of the present invention, the predetermined remaining battery charge is a predetermined value between 90% and full charge.

  According to the first aspect of the present invention, the difference value between the predetermined remaining battery charge and the remaining battery charge at the start of the engine, and the remaining battery charge of the battery from the start of the engine are the predetermined remaining battery charge. Since the battery capacity of the battery is detected based on the amount of accumulated current until it reaches (that is, the amount of charge current charged in the battery during that time), the battery capacity of the battery mounted on the vehicle can be automatically detected.

  According to the second aspect of the present invention, since the predetermined remaining battery charge is a predetermined value between 90% and full charge, the remaining battery charge can be easily obtained by using the output current of the battery. It is possible to detect whether or not the predetermined remaining battery charge has been reached.

  The battery capacity detection device according to this embodiment is a battery capacity detection device that detects the battery capacity of a battery B mounted on a vehicle, and a current sensor 3 that detects the output current of the battery B as shown in FIG. A voltage sensor 5 for detecting the output voltage of the battery B, a processing unit 7 for detecting the battery capacity of the battery B based on the detection results of the current sensor 3 and the voltage sensor 5, data necessary for processing of the processing unit 7, etc. And a storage unit 9 for storing.

  Battery B has its negative electrode grounded, and its positive electrode is connected to starter ST and in-vehicle device 13 via ignition switch IG. Thus, when the ignition switch IG is turned on, the power supply from the battery B is supplied (discharged) to the in-vehicle device 13 and the starter ST via the ignition switch IG, and the engine of the vehicle is started by the starter ST. The battery B is charged by a generator (not shown) mounted on the vehicle while the vehicle is running.

  The processing unit 7 includes a remaining charge detection means 7a for detecting the remaining battery charge SOCo of the battery B when the vehicle engine is started based on the detection result of the voltage sensor 5, and the current state of the battery B based on the detection result of the current sensor 3. The detection means 7b for detecting whether or not the remaining battery charge SOCn has reached a predetermined remaining battery charge SOCs (here, full charge), and the battery charge of the battery B by the detection means 7b from the start of the engine. Charge current amount detection means 7c for detecting a charge current amount ΔQ charged in the battery B until it is detected that the remaining SOC n has reached the predetermined battery charge remaining SOCs, and the predetermined battery charge A difference value ΔSOC (= SOCs−SOCo) between the remaining SOCs and the remaining battery charge SOCo at the time of engine start detected by the remaining charge detection means 7a; And a battery capacity detecting means 7d for detecting the battery capacity C of the battery B as C = ΔQ / ΔSOC based on the charging current quantity ΔQ detected by the charging current quantity detecting means 7c.

  Based on the detection result of the voltage sensor 5, the remaining charge detection means 7a detects an open voltage before discharge of the battery B (hereinafter referred to as an open voltage) Vo and a lower limit voltage after discharge (hereinafter referred to as a lower limit voltage) from the detection result of the engine. 2 is obtained based on the information of the characteristic curve I representing the relationship between the open circuit voltage and the lower limit voltage VL of the new battery and the open circuit voltage and the lower limit voltage of the new battery stored in the storage unit 9 in advance. Then, the remaining battery charge SOCo at the time of starting the engine is detected as follows.

  In the graph of FIG. 2, the vertical axis represents the lower limit voltage and the horizontal axis represents the open circuit voltage. The point Po is a point defined by the open voltage Vo and the lower limit voltage VL of the battery B detected by the voltage sensor 5 at the time of starting the engine. Point PE is a point defined by lower limit voltage VLE and open circuit voltage VoE when battery B is zero-charged. VoIF is an open-circuit voltage obtained from the characteristic curve I when a new battery is fully charged. VoIE is an open-circuit voltage obtained from the characteristic curve I when a new battery is zero-charged. VLE is a lower limit voltage obtained from the characteristic curve I when a new battery is zero-charged.

  That is, referring to FIG. 2, the remaining charge detection means 7a first obtains the open circuit voltage VoI corresponding to the lower limit voltage VL in the characteristic curve I based on the information on the characteristic curve I and the lower limit voltage VL. Then, the remaining charge detection means 7a determines the open circuit voltage VoE at the time of zero charging of the battery B as the ratio between the difference value between the lower limit voltage VoIF and the lower limit voltage VoE and the difference value between the lower limit voltage VoE and the lower limit voltage VoIE. The value is estimated to be the same as the ratio between the difference value between the lower limit voltage VoIF and the lower limit voltage Vo and the difference value between the lower limit voltage Vo and the lower limit voltage VoI. Then, the remaining charge detection means 7a has a difference value D3 (= VoIF−VoE) between the lower limit voltage VoIF and the estimated lower limit voltage VoE, and a difference value D4 (= Vo) between the lower limit voltage Vo and the estimated lower limit voltage VoE. Based on -VoE), the remaining battery charge SOCo at the time of starting the engine is obtained as SOCo = D4 / D3.

  The detection means 7b detects whether or not the remaining battery charge SOCn has reached a predetermined remaining battery charge SOCs (here, full charge) based on the detection result of the current sensor 3 as follows.

  That is, generally, the output current of the battery B is substantially constant Ia until the remaining battery charge SOCn of the battery B reaches about 90% (time point t1) while the vehicle is running as shown in FIG. When the remaining battery charge level SOCn of the battery B exceeds about 90%, it decreases to a substantially S shape, and when the remaining battery charge level SOCn of the battery B becomes almost fully charged, it converges to almost zero.

  Using this characteristic, the detection means 7b monitors the output current of the battery B based on the detection result of the current sensor 3, and determines whether or not the battery B has a battery B depending on whether or not the output current of the battery B has converged to zero. It is detected whether or not the remaining charge SOCn has reached a predetermined remaining battery charge SOCs (here, full charge).

  Here, the predetermined remaining battery charge SOCs is set to full charge (100%), but other settings may be set to a predetermined value (for example, 95%) between 90% and full charge. Good.

  For example, when the predetermined remaining battery charge SOCs is set to 90%, the remaining battery charge SOCn depends on whether the output current of the battery B starts to decrease from the constant value Ia based on the detection result of the current sensor 3. May be detected as to whether or not a predetermined remaining battery charge SOCs (90% in this case) has been reached.

  Further, for example, when the predetermined remaining battery charge SOCs is set to 95%, the remaining battery charge is determined depending on whether or not the output current of the battery B has become a half value of the constant value Ia based on the detection result of the current sensor 3. It may be detected whether or not the degree SOCn has reached a predetermined remaining battery charge SOCs (here, 95%).

  The charge current amount detection means (current integration means) 7c is a current sensor from when the engine is started until the detection means 7b detects that the remaining battery charge SOCn has reached the predetermined remaining battery charge SOCs. 3 is integrated to obtain an integrated current amount therebetween, and the integrated current amount is set as a charging current amount ΔQ charged in the battery B during that time.

  When the remaining charge SOCn of the battery B becomes 90% or more, the charging efficiency of the battery B is reduced (for example, less than 50%). Due to this reduction, the charging of the battery B out of the current input to the battery B is reduced. Since the contribution ratio is substantially reduced (for example, less than 50%), the amount of charge current actually charged to the battery B (hereinafter referred to as an actual value) and the amount of current detected by the current sensor 3 are integrated. Thus, the difference (that is, error) from the charging current amount (hereinafter referred to as a detected value) obtained in this way becomes considerably large.

  Therefore, in order to reduce the above error, when the charging current amount ΔQ is detected, if the remaining charge of the battery B is 90% or more, the integration of the current amount detected by the current sensor 3 may be stopped. . That is, in the range of the remaining battery charge SOCn (for example, a range of 90% or more) in which the error between the actual value and the detected value becomes large, the actual value and the detected value are stopped by stopping the integration of the current amount detected by the battery B. The error may be reduced.

  At this time, whether or not the remaining battery charge SOCn is in a range of, for example, 90% or more may be determined based on, for example, a current detected by a current sensor.

  Next, the operation of this battery capacity detection device will be described.

  When the engine of the vehicle is started, the battery B is discharged, and the processing unit 7 detects the open voltage Vo and the lower limit voltage VL of the battery B at the time of starting the engine based on the detection result of the current sensor 3. Then, the processing unit 7 detects the remaining battery charge SOCo of the battery B at the time of starting the engine based on the open voltage Vo and the lower limit voltage VL as described above.

  After the engine is started, the processing unit 7 determines whether or not the current remaining battery charge SOCn of the battery B has reached a predetermined remaining battery charge SOCo based on the detection result of the current sensor 3 as described above. While the detection is performed, the amount of current detected by the current sensor 3 is integrated from when the engine is started until it is detected that the remaining battery charge SOCn has reached a predetermined remaining battery charge SOCs. .

  Then, when the remaining battery charge SOCn of the battery B reaches a predetermined remaining battery charge SOCs and this is detected by the processing unit 7, the processing unit 7 performs a period between the engine start and the detection. The accumulated current amount is used as the charging current amount ΔQ charged in the battery B in the meantime (that is, the charging current amount ΔQ in the meantime is detected), and the predetermined battery remaining charge SOCs and the battery charging at the time of starting the engine are performed. A difference value ΔSOC (= SOCs−SOCo) with respect to the remaining degree SOCo is obtained, and the battery B capacity C of the battery B is detected as C = ΔQ / ΔSOC based on the charge current amount ΔQ and the difference value ΔSOC.

  According to the battery B capacity detection device configured as described above, the difference value ΔSOC between the predetermined battery charge remaining SOCs and the battery charge remaining SOCo at the time of engine start, and the battery charge remaining charge SOCn from the time of engine start. The battery capacity C (= ΔQ / ΔSOC) of the battery B is detected based on the integrated current amount ΔQ until the battery reaches a predetermined remaining battery charge SOCs (that is, the charging current amount charged in the battery B during that time) ΔQ. Therefore, the battery capacity of the battery B mounted on the vehicle can be automatically detected.

  Further, since the predetermined remaining battery charge SOCs is a predetermined value between 90% and full charge, the remaining battery charge SOCn of the battery B can be easily obtained by using the output current of the battery B. It is possible to detect whether or not the remaining charge SOCs has been reached.

  In addition, in the range of the remaining battery charge where the charging efficiency of the battery B is reduced, the amount of current detected by the current sensor is not integrated, so the amount of charging current actually charged to the battery B and the current sensor are detected. The error from the integrated current value obtained by integrating the current amount can be reduced.

1 is a schematic configuration diagram of a battery capacity detection device according to an embodiment of the present invention. It is a figure explaining the method of detecting battery charge remaining SOCo (= D2 / D1) at the time of engine starting based on the open circuit voltage Vo and the lower limit voltage VL at the time of engine starting. It is a figure explaining the method to detect whether a battery remaining charge reaches only a predetermined battery remaining charge based on the output current of a battery.

Explanation of symbols

3 Current sensor 5 Voltage sensor 7 Processing unit 7a Remaining charge detection means 7b Detection means 7c Charge current amount detection means (current integration means)
7d Battery capacity detection means 9 Storage unit 13 In-vehicle device B Battery SOCo Battery charge remaining at engine start SOCn Current battery charge remaining SOCs Predetermined battery charge remaining

Claims (2)

A battery capacity detection device for detecting a battery capacity of a battery mounted on a vehicle,
A current sensor for detecting the output current of the battery;
A remaining charge detection means for detecting a remaining battery charge of the battery when the engine of the vehicle is started;
Detecting means for detecting whether or not the remaining battery charge of the battery has reached a predetermined remaining battery charge;
A current that integrates the amount of current detected by the current sensor from when the engine is started until the detection means detects that the remaining battery charge level of the battery has reached the predetermined remaining battery charge level Integrating means;
Based on the difference value between the predetermined remaining battery charge and the remaining battery charge at the time of starting the engine detected by the remaining charge detection means, and the accumulated current amount accumulated by the current accumulation means. Battery capacity detecting means for detecting the battery capacity;
A battery capacity detection device comprising: The battery capacity detection device according to claim 1, wherein the predetermined remaining battery charge is a predetermined value between 90% and full charge.

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