JP2007278853A - Battery state determining apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery state determining apparatus capable of accurately determining the state of degradation of lead batteries. <P>SOLUTION: The battery state determining apparatus measures an open-circuit voltage OCV of a lead battery and a lowest voltage Vst when an engine is started and determines which region the voltages belong to in a property map determining the relation between OCV and Vst and divided into five regions indicating the state of degradation to determine the state of degradation of the lead battery. The property map is divided into the five regions of a first region of high OCV and high Vst; a second region located on the left side of the first region and of low OCV; a third region located below the first region and of high OCV and low Vst; a fourth region between the first and third regions; and a fifth region between the second and third regions. Each of the boundaries between the first and fourth regions; the second and fifth regions; the fourth and third regions; and the fifth and third regions is a curve having a positive gradient in logarithmic-curve form. The boundaries between the first and second regions and between the fourth and fifth regions are straight lines of 50% SOC of a new lead battery. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a battery state determination device, and more particularly to a battery state determination device that determines a deterioration state of a lead battery mounted in a vehicle.

  A lead battery for starting an internal combustion engine (hereinafter referred to as a lead battery) ensures a reliable start of the engine in a gasoline engine vehicle, a diesel engine vehicle or the like (hereinafter referred to as a vehicle) equipped with an internal combustion engine system. Therefore, it is an extremely important part. In recent years, due to the popularization of in-vehicle information devices such as car navigation systems and the electrification of auxiliary equipment such as electric power steering, in-vehicle electrical components are increasing, and lead batteries are also required to respond to the increasing power supply. Yes. On the other hand, in consideration of environmental problems, hybrid electric vehicles combining an electric motor and an engine, vehicles that are stopped when a signal is stopped, and restarted when the vehicle is started (equipped with an ISS system) have been developed.

  In such a lead battery usage environment, the deterioration state of the lead battery is accurately detected, and the current state of charge is grasped so as to eliminate any obstacles to driving the vehicle (for example, when various electric devices are If the remaining capacity of the lead battery is reduced by the load, sufficient output to start the engine will not be obtained, and it may not be possible to restart the engine after it has stopped)). Technology for detecting the state of charge (SOC) and the state of health (SOH) of a battery is important.

  Until now, attempts have been made to detect the SOC and SOH of lead batteries by various techniques such as open circuit voltage measurement of lead batteries, internal resistance measurement using alternating current, charging current, and discharge current measurement. For example, a technique for measuring the voltage of a lead battery when starting a starter motor to detect a state has been proposed (see Patent Document 1).

JP 2001-163129 A

  However, in the conventional lead battery SOC and SOH detection technologies, the basis for the SOH determination is often not clearly indicated. That is, there are many cases where the grounds for determining that the state of the lead battery indicates that the SOH is lowered are poor. This is considered to be due to the lack of knowledge about the characteristics of the lead battery because it generally takes a lot of time to collect data on the characteristics of each lead battery in each SOH.

  The present invention provides a battery state determination device that can accurately determine the deterioration state of a lead battery using a characteristic map that defines the relationship between the SOH of the lead battery, the open circuit voltage, and the minimum voltage. Let it be an issue.

  In order to solve the above-mentioned problems, the present invention provides an open circuit voltage measuring means for measuring an open circuit voltage (OCV) of the lead battery in a battery state determination device for determining a deterioration state of a lead battery mounted on a vehicle. A minimum voltage measuring means for measuring a minimum voltage (Vst) at the time of starting the engine of the lead battery, and a characteristic map defining a relationship between the OCV and Vst of the lead battery, and a plurality of characteristics maps representing a deterioration state of the lead battery A plurality of characteristic maps stored in the storage means, the storage means storing in advance the characteristic map divided into the regions of the above, the OCV measured by the open circuit voltage measurement means, and the Vst measured by the minimum voltage measurement means A deterioration state determination unit that determines a deterioration state of the lead battery by determining which of the regions belongs, and the characteristic map stored in the storage unit includes OCV on the horizontal axis and Vs Is the first region where both OCV and Vst are high, the second region is located on the left side of the first region and has a low OCV, and the OCV is high and Vst is located below the first region. Is divided into five regions, a third region having a low height, a fourth region between the first and third regions, and a fifth region between the second and third regions. The boundary of the four regions, the boundary of the second and fifth regions, the boundary of the fourth and third regions, and the boundary of the fifth and third regions have a positive slope and are logarithmic curves It is a curve.

  The battery state determination apparatus according to the present invention is a characteristic map that defines the relationship between the open circuit voltage (OCV) of a lead battery and the minimum voltage (Vst) at the time of engine start of the lead battery, and represents a plurality of deterioration states of the lead battery. Storage means for storing in advance a characteristic map divided into these areas. When the OCV is taken on the horizontal axis and Vst is taken on the vertical axis, this characteristic map is located in the first area where OCV and Vst are both high, the second area where the OCV is low and the first area is located on the left side of the first area. It is divided into five regions, a third region located on the lower side and having a high OCV and a low Vst, a fourth region between the first and third regions, and a fifth region between the second and third regions. The boundary between the first and fourth regions, the boundary between the second and fifth regions, the boundary between the fourth and third regions, and the boundary between the fifth and third regions have a positive slope and are logarithmic. It is a curved curve, and is created based on the actual use state of each lead battery in each SOH. The OCV of the lead battery is measured by the open circuit voltage measuring means, and the Vst at the start of the lead battery engine is measured by the minimum voltage measuring means. Then, the deterioration state determination means determines which of the five regions of the characteristic map stored in the storage means the OCV measured by the open circuit voltage measurement means and the Vst measured by the minimum voltage measurement means belongs. The deterioration state of the lead battery is determined.

  In the present invention, the boundary between the first and second regions and the boundary between the fourth and fifth regions of the characteristic map stored in the storage unit may be a straight line. As such a straight line, for example, a straight line having a predetermined percentage SOC in a new state of the lead battery can be used. Further, when the deterioration state determining means determines that the OCV measured by the open circuit voltage measuring means and the Vst measured by the minimum voltage measuring means belong to the fourth to fifth regions of the characteristic map, the lead battery has deteriorated. It may be determined that the lead battery needs to be replaced when it is determined that it belongs to the third region. Furthermore, in order to eliminate the inaccuracy of voltage measurement due to charge / discharge polarization by the lead battery, it is desirable that the open circuit voltage measuring means measures the OCV of the lead battery after a predetermined time has elapsed after the engine is stopped.

  According to the present invention, since the deterioration state is determined using the characteristic map created based on the actual use state of each lead battery in each SOH by the deterioration state determination means, the deterioration determination of the lead battery can be accurately performed. The effect of being able to be obtained can be obtained.

  Hereinafter, the best mode of a battery state determination device according to the present invention will be described with reference to the drawings.

(Constitution)
As shown in FIG. 1, the battery state determination device 1 of this embodiment includes a differential amplifier circuit and the like, a voltage sensor 3 that measures the voltage between terminals of the lead battery 2 and a micro that determines the battery state of the lead battery 2. A computer (hereinafter referred to as a microcomputer) 10 is provided.

  The lead battery 2 has a substantially rectangular battery case serving as a battery container, and a total of six electrode plate groups are accommodated in the battery case. The battery case material is excellent in terms of moldability, electrical insulation, corrosion resistance and durability, for example, polymer resins such as acrylic butadiene styrene (ABS), polypropylene (PP), polyethylene (PE), etc. Can be selected. In each electrode plate group, a plurality of negative electrodes and positive electrodes are laminated via a separator, and the cell voltage is 2.0V. Therefore, the nominal voltage of the lead battery 2 is 12V. The upper part of the battery case is bonded or welded to an upper lid made of a polymer resin such as ABS, PP, PE or the like that seals the upper opening of the battery case. The upper lid is provided with a positive external output terminal and a negative external output terminal for supplying electric power to the outside using a lead battery as a power source.

  A positive external output terminal of the lead battery 2 is connected to a central terminal of an ignition switch (hereinafter referred to as IGN switch) 5. The IGN switch 5 has an OFF terminal, an ON / ACC terminal, and a START terminal in addition to the central terminal, and the central terminal and any of these OFF, ON / ACC, and START terminals can be switched in a rotary manner. Is possible.

  The START terminal is connected to an engine starting cell motor (starter) 9. The cell motor 9 can transmit a rotational driving force to the rotating shaft of the engine 8 via a clutch mechanism (not shown).

  Further, the ON / ACC terminal is one end of a generator 7 that generates electricity by the rotation of the engine 8 through an auxiliary device 6 such as an air conditioner, a radio, a lamp, and a regulator that allows current flow in one direction and smoothes the voltage. It is connected to the. That is, one end side (anode side) of the regulator is connected to one end of the generator 7 and the other end (cathode side) is connected to the ON / ACC terminal. The rotating shaft of the engine 8 can transmit power to the generator 7 via a clutch mechanism (not shown). For this reason, when the engine 8 is in a rotating state, the generator 7 is operated via a clutch mechanism (not shown), and the electric power from the generator 7 is supplied (charged) to the auxiliary machine 6 and the lead battery 2. Note that the OFF terminal is not connected to any of them. The other end of the generator 7, the cell motor 9 and the auxiliary machine 6, the negative external output terminal of the lead battery 2, and the microcomputer are each connected to the ground.

  The external output terminal of the lead battery 2 is connected to the voltage sensor 3, and the output side of the voltage sensor 3 is built in the microcomputer 10, and is an A / D converter that converts the analog voltage input from the voltage sensor 3 into a digital voltage. It is connected to the. For this reason, the microcomputer 10 can take in the voltage of the lead battery 2 as a digital value. In this embodiment, an A / D converter having a sampling rate of 1 ms is used.

  The microcomputer 10 functions as a central processing unit, a ROM in which program data such as a basic control program of the battery state determination device 1 and a characteristic map described later is stored, a work area of the CPU, and temporarily stores data. It includes a RAM and the like.

  Here, the characteristic map stored in the ROM will be described.

  Generally, in a vehicle, electric power is supplied from a lead battery, a cell motor is rotated, and an engine is started. Although a large current flows at the moment of starting the engine, the voltage of the lead battery greatly drops accordingly (see FIG. 3). In this embodiment, the minimum voltage (Vst) of the lead battery at the time of starting the engine is used as an indicator of the characteristics of the lead battery. Vst indicates the output of the lead battery. From another viewpoint, Vst strongly correlates with the magnitude of the internal resistance of the lead battery, and is appropriate as an index representing the SOH of the lead battery. Vst varies depending on the SOC of the lead battery, and Vst increases as the SOC increases. Vst also changes depending on the SOH of the lead battery. If the SOH is high, Vst increases.

  FIG. 2 shows a relationship between SOC and Vst in a lead battery (new battery) having 100% SOH and a battery (deteriorated battery) in which each SOH is lowered. As an SOC index, an open circuit voltage (OCV), which is a battery voltage in a no-load state, was used. Hereinafter, FIG. 2 is referred to as a characteristic map, and the relationship between OCV and Vst of a lead battery is referred to as a battery characteristic. This battery characteristic is represented by a characteristic curve.

  As shown in FIG. 2, when OCV is taken on the horizontal axis and Vst is taken on the vertical axis, the battery characteristics (characteristic curve) of the deteriorated battery are located below the battery characteristics of the new battery. When the battery characteristics are measured with each SOH after the lead battery is deteriorated, the battery characteristics (characteristic curve) move downward as the deterioration progresses and the SOH decreases. Thereby, OCV and Vst of a lead battery are measured together, and the degradation state of a lead battery can be classified by seeing where it is located on a characteristic map. Specifically, as described in detail below, the first region where both OCV and Vst are high, the second region located on the left side of the first region and having a low OCV, and the OCV is located below the first region. Each region of the third region having a high Vst and a low Vst is set. In addition, a fourth region that shows intermediate characteristics between the first region and the third region, and a fifth region that shows intermediate properties between the second region and the third region are set.

  In the first region, both OCV and Vst are high, and the lead battery in this region has a sufficient remaining capacity. When such a healthy lead battery is discharged and the SOC decreases, Vst goes higher and enters the second region. In the second area, only the SOC is lowered, and the lead battery is returned to the first area only by charging. Therefore, it is not necessary to replace the lead battery. In many of the lead batteries belonging to the third region, which are deteriorated and the remaining capacity is reduced due to a decrease in SOH, the OCV in a fully charged state is almost the same as that of a new lead battery. However, even if the OCV is the same, Vst is low, and in such a deteriorated battery, Vst drastically drops with a slight decrease in SOC, and the engine starting ability decreases. The boundary line that divides the battery state can be expressed by using a mathematical shape showing the battery characteristics of the new battery and the deteriorated battery shown in FIG. That is, the boundary between the first and fourth regions, the boundary between the second and fifth regions, and the boundary between the fourth and third regions have a positive slope when the horizontal axis is OCV and the vertical axis is Vst. And a logarithmic curve. In order to obtain a curve of such a shape, the battery characteristics of a lead battery with a reduced SOH as much as necessary may be measured, but the load required in the vehicle for which the battery state is to be determined is calculated. It is also possible to calculate and set the relationship between OCV and Vst.

  The battery characteristics (shape of the characteristic curve) shown in FIG. However, the characteristic curve shifts in the Y-axis direction in FIG. 2 due to the difference in the vehicle load when the engine is started. When the engine load is large even with the same lead battery and the same OCV (charged state), Vst decreases, so the characteristic curve moves in the negative direction of the Y axis. In this case, all the areas of the first to fifth areas are equally moved in the negative direction of the Y-axis, so the mutual positional relationship between the areas does not change. For this reason, it is possible to deal with various vehicles by obtaining new battery characteristics (characteristic curves) in one lead battery and correcting the difference in vehicle load.

In the present embodiment, in order to create the characteristic map shown in FIG. 2, a JIS standard 55B24 size lead battery is used, and a gasoline engine vehicle with an electronically controlled fuel injection device with a displacement of 2000 cc is used as an internal combustion engine to be applied. I chose. This lead battery is JIS
The lead battery was accelerated and deteriorated by a light load life test of D 5301, and a lead battery having SOH at 50% and 30% at a capacity of 5 hours was produced. Next, the OCV in a fully charged state of the lead battery having SOH of 50% and 30% was measured and attached to the automobile. Subsequently, the engine was started and Vst was measured when the engine was started. While measuring and recording the terminal voltage of the lead battery with a general digital recorder with a sampling rate of 1.0 ms, the engine start key was operated to start the engine. Vst was read from the obtained time / terminal voltage curve. Thereafter, a predetermined amount of electricity was discharged at a 5-hour rate current to lower the SOC. Thereafter, OCV and Vst were measured in the same manner as in the fully charged state. This operation was repeated to obtain battery characteristics (characteristic curves) for each lead battery.

  In this embodiment, the battery characteristics of the lead battery with 50% SOH are used for the boundary line between the first and second regions and the fourth and fifth regions, and the battery characteristics of the lead battery with 30% SOH are It was used for the boundary line between the third region and the fourth and fifth regions. Furthermore, a characteristic map was created using a straight line of SOC 50% in the new state at the boundary between the first region and the second region and the boundary between the fourth region and the fifth region.

  Next, the created characteristic map was evaluated. That is, a new lead battery 1 was attached to an automobile and started to be used. The lead battery was used for a long time in normal private use. The voltage was measured by the same procedure as described above in a state where a lead battery that has deteriorated over a period of use was mounted on the vehicle, and OCV and Vst were obtained. The obtained OCV and Vst were applied to the characteristic map to determine the battery state. After determining the battery state, the remaining capacity of the lead battery was measured by a 5-hour rate discharge test, and SOC and SOH were calculated. The validity of the determination was evaluated based on the determination result of the battery state and the correspondence between SOC and SOH. Table 1 below shows the validity evaluation results. It can be seen from the characteristic map that the deterioration state of the lead battery 1 can be correctly determined by measuring OCV and Vst.

(Operation)
Next, with reference to a flowchart, the operation of the battery state determination device 1 of the present embodiment will be described with the CPU of the microcomputer 10 as a main component. When the microcomputer 10 is powered on, the CPU executes a battery state determination routine for determining the battery state of the lead battery 2. Note that the program stored in the ROM and the above-described characteristic map are developed in the RAM by an initial setting process (not shown) after the microcomputer 10 is powered on.

  As shown in FIG. 4, in the battery state determination routine, in step 112, it is determined whether or not the engine has been started by determining whether or not a notification that the center terminal of the IGN switch 5 is connected to the START terminal has been received. Determine whether. The notification that the center terminal is connected to the START terminal may be received directly from the IGN switch 5 or via the vehicle control system 11.

  If a negative determination is made in step 112, it is determined in the next step 114 whether or not a predetermined time (for example, 6 hours) has elapsed since the engine stopped. When the determination is negative, the process returns to step 112. When the determination is affirmative, the open circuit voltage (OCV) of the lead battery 2 is taken in via the voltage sensor 3 and the A / D converter, and the process returns to step 112. The reason why the OCV is taken in after a lapse of a predetermined time after the engine is stopped is to eliminate inaccuracy of voltage measurement due to charge / discharge polarization by the lead battery 2. In addition, the OCV measurement of the lead battery 2 in step 116 may be performed every predetermined time, and once the OCV is measured, it may be performed after a predetermined time (for example, 6 hours) has passed (this step in FIG. 4). Is abandoned.)

  On the other hand, when an affirmative determination is made in step 112, in step 118, the minimum voltage (Vst) of the lead battery 2 at the time of engine start is measured. In other words, the voltage data of the lead battery 2 at the time of engine start-up is taken in (stored in RAM) at the sampling rate of 1 msec of the A / D converter built in the microcomputer 10, and the minimum value of the taken-in voltage data is extracted. Then, the minimum voltage Vst of the lead battery 2 at the time of starting the engine is measured (see also FIG. 3).

  In the next step 120, an area determination process is executed. That is, the latest (latest) OCV captured in step 116 and the Vst measured in step 118 are applied to the characteristic map shown in FIG. 2, and the deterioration state of the lead battery 2 is in any of the five areas of the characteristic map. Determine if it belongs. Next, in step 122, it is determined whether or not the deterioration state of the lead battery 2 belongs to the third region of the characteristic map. If a negative determination is made, the process returns to step 112. If an affirmative determination is made, in the next step 124, the vehicle control system 11 is notified that the lead battery 2 has deteriorated, and the process returns to step 112.

  The vehicle control system 11 that has received the notification that the lead battery 2 has deteriorated may not be able to restart the engine (ISS) after the vehicle stops, so the driver panel displays that the lead battery 2 has deteriorated on the installation panel. Prompts replacement of the lead battery 2. The driver can know that the lead battery 2 has deteriorated by referring to the installation panel, and the ISS can be secured by replacing the lead battery 2 with a lead battery of the same specification at the service station.

(Action / Effect)
Next, functions and effects of the battery state determination device 1 of the present embodiment will be described.

  As shown in FIG. 2, the battery state determination device 1 of the present embodiment is divided into five regions in the ROM of the microcomputer 10, and the relationship between the OCV of the lead battery 2 and the Vst at the time of engine start of the lead battery 2. Is stored in the characteristic map. As described above, this characteristic map is created based on the actual use state of each lead battery 2 in each SOH. By applying the captured OCV (step 116) and the measured Vst (step 118) to this characteristic map, it is possible to accurately and in real time which region the lead battery 2 that deteriorates due to engine start belongs. (Step 120, see Table 1).

  In the present embodiment, an example in which the vehicle control system 11 is informed that the lead battery 2 needs to be replaced when it is determined that it belongs to the third region has been shown, but it belongs to the third region or the fifth region. When it is determined, the vehicle control system 11 may be notified that the lead battery 2 has deteriorated. In the present embodiment, an example is shown in which one of the five regions is determined by one measurement of each of OCV and Vst. However, the battery state determination device 1 is accommodated in, for example, an engine room. In some cases, a voltage measurement error due to noise or the like may occur. Therefore, in order to further improve the deterioration determination accuracy of the lead battery 2, the deterioration determination may be performed by making a plurality of determinations. Furthermore, in the present embodiment, the characteristic map is schematically described. However, it is not a matter of course that the above-described five regions can be expressed using mathematical formulas or the like.

  The present invention provides a battery state determination device that can accurately determine the deterioration state of a lead battery using a characteristic map that defines the relationship between the SOH of the lead battery and the open circuit voltage and the minimum voltage. Since it contributes to the manufacture and sale of judgment devices, it has industrial applicability.

1 is a block wiring diagram of a battery state determination device and a vehicle according to an embodiment to which the present invention is applicable. It is explanatory drawing which shows the concept of the characteristic map stored in ROM in the microcomputer of the battery state determination apparatus of embodiment. It is explanatory drawing of the minimum voltage of the lead battery at the time of engine starting. It is a flowchart of the battery state determination routine which CPU of the microcomputer of a battery state determination apparatus performs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery state determination apparatus 2 Lead battery 3 Voltage sensor (a part of open circuit voltage measurement means, a part of minimum voltage measurement means)
10 Microcomputer (part of open circuit voltage measurement means, part of minimum voltage measurement means, storage means, deterioration state determination means)

Claims (4)

In a battery state determination device for determining a deterioration state of a lead battery mounted on a vehicle,
Open circuit voltage measuring means for measuring an open circuit voltage (OCV) of the lead battery;
Minimum voltage measuring means for measuring the minimum voltage (Vst) at the time of engine start of the lead battery;
Storage means for preliminarily storing a characteristic map that is a characteristic map that defines a relationship between OCV and Vst of the lead battery and that is divided into a plurality of regions that indicate a deterioration state of the lead battery;
By determining which of the plurality of regions of the characteristic map stored in the storage means the OCV measured by the open circuit voltage measurement means and the Vst measured by the minimum voltage measurement means belong to the lead battery. A deterioration state determining means for determining a deterioration state;
The characteristic map stored in the storage means has OCV as the horizontal axis and Vst as the vertical axis.
A first region where both OCV and Vst are high, a second region located on the left side of the first region and having a low OCV, a third region located under the first region and having a high OCV and a low Vst, the first region And a fourth region between the third region and a fifth region between the second region and the third region.
A boundary between the first and fourth regions, a boundary between the second and fifth regions, a boundary between the fourth and third regions, and a boundary between the fifth and third regions have a positive slope; and , Characterized by a logarithmic curve,
Battery state determination device.   2. The battery state determination according to claim 1, wherein a boundary between the first and second regions and a boundary between the fourth and fifth regions of the characteristic map stored in the storage unit are straight lines. apparatus.   When the deterioration state determination means determines that the OCV measured by the open circuit voltage measurement means and the Vst measured by the minimum voltage measurement means belong to the fourth to fifth regions of the characteristic map, the lead battery 2. The battery state determination device according to claim 1, wherein it is determined that the lead battery needs to be replaced when it is determined that the lead battery belongs to the third region.   The battery state determination device according to claim 1, wherein the open circuit voltage measurement unit measures an OCV of the lead battery after a predetermined time has elapsed after the engine is stopped.

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