JP2008089417A - Battery state detection system and automobile having it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery state detection system capable of accurately calculating the remaining capacity of a battery even if a current sensor has a performance limit. <P>SOLUTION: An announcing system has a current sensor whose detectable maximum current value is 100A. The announcing system determines direct current internal resistance R of a lead acid battery 1 with the gradient of approximate straight line determined by a least squares method using current I and voltage V in a range of -100 A to 0 A flowing in the lead acid battery measured every 1 ms when an engine is started (S120), and calculates the remaining capacity of the lead acid battery by substituting the value of the direct current internal resistance R and the value of the temperature T of the lead acid battery 1 into a predetermined map where the relation among the direct current internal resistance R and the temperature T and the remaining capacity of the lead acid battery 1 is predetermined (S122). The influence of integration error of the charge/discharge current and variation of the initial remaining capacity by self discharge is not received. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a battery state detection system and an automobile, and more particularly, to a battery state detection system for detecting a battery state of a battery for an automobile, particularly a lead storage battery, and an automobile equipped with the same.

  Conventionally, an automobile battery is charged by an alternator during traveling. The load at this time is limited to a lamp or the like, and there is no very deep discharge, and it has been used in a state in which it is kept almost fully charged.

  However, from the viewpoint of recent environmental problems, system cars with an idling stop / start function are becoming popular, mainly for large buses and trucks. In such a system vehicle, since the electric power of the air conditioner, car navigation, etc. is all supplied from the battery while the engine is stopped, the remaining capacity of the mounted battery is expected to be smaller than in the conventional case.

  Since the output of the battery depends on the remaining capacity, the engine may not be restarted if the battery capacity becomes low while the engine is stopped. For this reason, it is necessary to estimate the remaining capacity of the battery and to monitor the presence / absence of an output necessary for starting the engine. Further, when the output is insufficient for starting the engine, it is necessary to stop the idling stop and transmit a signal to the vehicle side that the battery needs to be charged.

  As a technique for estimating the remaining capacity of the battery, a technique for integrating the charging / discharging current from the initial remaining capacity of the battery over time (for example, see Patent Document 1), or measuring the charge / discharge power amount of the battery and correcting the temperature. A technique for detecting the remaining capacity of a battery is known (for example, see Patent Document 2).

JP-A-6-59003 JP-A-9-98504

  However, in the technique of the above publication, measurement error of charge / discharge current is accumulated, and when the battery is not in use, there is a change in the initial remaining capacity due to self-discharge, etc. It is difficult to calculate well.

  The charge / discharge current of the battery is a relatively small current of 100 A or less during normal (running), but a large current exceeding 500 A flows only when the engine is started. In conventional vehicles (vehicles other than system vehicles), the number of engine starts is small and the amount of battery discharge at engine startup is so small that it can be ignored. Therefore, using a current sensor that can accurately detect a current of 100 A or less is relatively accurate. While the remaining capacity of the battery could be estimated well, in the system car, the number of engine start due to idling stop start is large and the amount of discharge at engine start cannot be ignored, so even with such a current sensor, It is difficult to accurately estimate (calculate) the remaining capacity of the battery. On the other hand, even if an attempt is made to estimate the remaining capacity of a battery using a current sensor capable of detecting a large current in a system car, a current sensor capable of measuring a large current cannot accurately measure a current of 100 A or less during normal operation. The remaining capacity of the battery cannot be calculated accurately.

  An object of the present invention is to provide a battery state detection system capable of accurately calculating the remaining capacity of a battery even when the current sensor has a performance limit, and an automobile equipped with the battery state detection system.

  In order to solve the above-described problem, a first aspect of the present invention is a battery state detection system having a current sensor capable of detecting a current up to a predetermined current value and having a detection error of 5% or less, and flowing to the battery. Current measuring means for measuring current, voltage measuring means for measuring the voltage of the battery, temperature measuring means for measuring the temperature of the battery, and calculating the remaining capacity of the battery from the measured amounts measured by the respective means Remaining capacity calculation means, wherein the remaining capacity calculation means is a current I less than the predetermined current value flowing through the battery at the time of engine start, measured at predetermined times by the current measurement means and the voltage measurement means, The DC internal resistance R of the battery is obtained from the slope of the approximate straight line obtained by the least square method using the voltage V, and the value of the obtained DC internal resistance R and the bar measured by the temperature measuring means are obtained. By substituting the value of the temperature T of Teri to a predetermined map or equation the relationship between the temperature T and state of charge of the direct current internal resistance R and battery, and calculates the remaining capacity of the battery.

  In the present invention, a Hall element or a shunt resistor having a maximum detectable current value of 100 A or less may be used for the current sensor. The remaining capacity calculating means measures current I and voltage V that are less than the predetermined current value flowing through the battery after the engine is started and exceeds the maximum discharge current value Ipeak after being measured every predetermined time by the current measuring means and the voltage measuring means. The DC internal resistance R of the battery is preferably obtained from the slope of the approximate straight line obtained by the least square method used, and the remaining capacity calculating means has 150 or more measured values of the current I measured by the current measuring means, and is approximate. When the linear correlation coefficient satisfies the condition of 0.95 or more, the remaining capacity of the battery can be calculated by substituting the value of the DC internal resistance R and the value of the battery temperature T into a map or formula. Further preferred.

  Moreover, in order to solve the said subject, the 2nd aspect of this invention is a motor vehicle provided with the battery state detection system of the 1st aspect.

  According to the present invention, the remaining capacity calculating means uses a current I and a voltage V that are less than a predetermined current value flowing through the battery at the time of starting the engine measured by the current measuring means and the voltage measuring means every predetermined time, and uses the least square method. The DC internal resistance R of the battery is obtained from the slope of the obtained approximate straight line, and the value of the obtained DC internal resistance R and the value of the battery temperature T measured by the temperature measuring means are used as the DC internal resistance R and the battery temperature T. The remaining capacity of the battery is calculated by substituting the relationship between the remaining capacity and the remaining capacity into a predetermined map or mathematical expression. Since it is not affected by the change in the initial remaining capacity, it is possible to obtain an effect that the remaining capacity of the battery can be calculated with high accuracy.

  Hereinafter, an embodiment in which the present invention is applied to a notification system for notifying a vehicle control system of an insufficient charge state of a lead storage battery mounted on a vehicle having an idling stop / start function will be described with reference to the drawings.

(Constitution)
As shown in FIG. 1, the notification system 12 of the present embodiment includes a temperature sensor 2 such as a thermistor that measures the temperature of the lead storage battery 1, a voltage sensor that has a differential amplifier circuit and the like and measures the voltage across the lead storage battery 1. 3, a current sensor 4 such as a Hall element that measures current flowing in the lead storage battery 1 with a detection error of 5% or less and a microcomputer that calculates the remaining capacity of the lead storage battery 1 (hereinafter referred to as a microcomputer). 10) is provided.

  The lead storage battery 1 has a rectangular battery case that serves as a battery container. A sensor insertion hole is formed in the partition wall at the center of the battery case. The temperature sensor 2 is inserted into the sensor insertion hole, and is fixed in the sensor insertion hole with an adhesive. A total of six sets of electrode plates are accommodated in the battery case. In each electrode plate group, a plurality of negative electrodes and positive electrodes are laminated via a retainer (separator) made of glass fiber, and the cell voltage is 2.0V. Therefore, the nominal voltage of the lead storage battery 1 is 12V. The upper part of the battery case is bonded or welded to an upper lid that seals the upper opening of the battery case. A rod-like positive electrode output terminal and a negative electrode output terminal are provided on the upper lid for supplying electric power to the outside using a lead storage battery as a power source.

  The positive electrode output terminal of the lead-acid battery 1 described above is connected to the center terminal of an ignition switch (hereinafter referred to as IGN switch) 5 via a current sensor 4. 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 current sensor 4 can detect the current based on the Hall voltage that changes in accordance with the current flowing through the Hall element. The START terminal is connected to an engine starting cell motor (engine starting 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 connected to one end of a generator 7 that generates electric power by rotation of the engine 8 through an auxiliary device 6 such as an air conditioner, a radio, and a lamp and a regulator that allows a current flow in one direction. . That is, the anode side of the regulator is connected to one end of the generator 7, and the 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 or the lead storage battery 1. Note that the OFF terminal is not connected to any of them.

  The output side of the current sensor 4 is connected to an A / D converter built in the microcomputer 10. For this reason, the Hall voltage output from the current sensor 4 is converted into a digital value by the A / D converter, and the microcomputer 10 can take in the current flowing through the lead storage battery 1. The external output terminal of the lead storage battery 1 is connected to the voltage sensor 3, and the output side of the voltage sensor 3 is connected to another A / D converter built in the microcomputer 10. For this reason, the microcomputer 10 can take in the voltage of the lead storage battery 1 as a digital value. Further, the output terminal of the temperature sensor 2 is connected to another A / D converter built in the microcomputer 10. For this reason, the microcomputer 10 can take in the temperature of the lead storage battery 1 as a digital value. The microcomputer 10 samples the voltage and current at 1 ms intervals, and stores the sampling result in the RAM. The microcomputer 10 can communicate with the host vehicle control system 11 via the interface.

  The microcomputer 10 includes a CPU that functions as a central processing unit, a ROM that stores program data such as a basic control program for the notification system 12 and a map that will be described later, and a RAM that functions as a work area for the CPU and temporarily stores data. It is comprised including. The other end of the generator 7, the cell motor 9 and the auxiliary machine 6, the negative external output terminal of the lead storage battery 1, and the microcomputer are each connected to the ground.

(Operation)
Next, the operation of the notification system 12 of the present embodiment will be described focusing on the CPU of the microcomputer 10 (hereinafter simply referred to as CPU). Note that when the vehicle control system 11 detects that the IGN switch 5 is located at the ON / ACC terminal, the vehicle control system 11 turns on a switch of a power supply circuit (not shown) that supplies operating power to the microcomputer 10. Thereby, the microcomputer 10 executes a remaining capacity calculation routine for calculating the remaining capacity of the lead storage battery 1 through an initial setting process for expanding a program or the like stored in the ROM into the RAM.

  As shown in FIG. 2, in the remaining capacity calculation routine, in step 102, it is determined whether or not engine start is started. For example, when the discharge current flowing through the lead storage battery 1 is 60 A or more, it is determined that the engine is started. If the determination is negative, the process waits. If the determination is affirmative, it is determined in next step 104 whether the current I flowing through the lead storage battery 1 is in the range of −100 A to 0 A. If the determination is negative, the process proceeds to step 108, and if the determination is affirmative, the current I in the range of -100A to 0A and the data of the corresponding voltage V are accumulated (stored in the RAM). In the present embodiment, the process in step 106 is executed every 1 ms.

  Next, in step 108, it is determined whether or not the engine start has been completed. If a negative determination is made, the process returns to step 104. If an affirmative determination is made, the process proceeds to step 110. For example, when the charging current starts to flow through the lead storage battery 1, it is determined that the engine has been started.

  In step 110, the temperature T of the lead storage battery 1 is measured, and in the next step 112, the data of the current I and voltage V after the maximum discharge current value Ipeak is selected from the data of the current I and voltage V accumulated in step 106. To do.

  FIGS. 3 and 4 schematically show the voltage V of the lead storage battery 1 and the current I flowing through the lead storage battery 1 when the engine is started. When the IGN switch 5 is positioned at the START terminal, as shown in FIG. 4, after the lead-acid battery 1 is suddenly discharged and reaches the maximum discharge current value Ipeak, the decay of the discharge current is repeated several times. The start is finished. At the maximum discharge current value Ipeak, as shown in FIG. 3, the voltage of the lead storage battery 1 also becomes the minimum voltage value. In FIG. 4, the discharge current from the lead storage battery is represented on the negative side, and the charge current to the lead storage battery is represented on the positive side.

  The current sensor 4 of the present embodiment cannot detect a current exceeding −100 A because the maximum detectable current value is 100 A as described above. However, as shown in FIG. 4, since the current value after the maximum discharge current value Ipeak tends to decrease in time series, the CPU determines the maximum discharge current among the data of the current I and voltage V accumulated in step 106. Data of current I and voltage V of −100 A to 0 A after the value I peak can be selected.

  Next, it is determined whether or not the number of currents I selected in step 114 is 150 or more. If the determination is negative, the remaining capacity calculation routine is terminated. If the determination is affirmative, the determination is made in step 112 in step 116. A correlation coefficient of an approximate straight line obtained from the current I and voltage V data by the least square method is calculated, and it is determined whether or not the correlation coefficient calculated in step 118 is 0.95 or more. When the determination is negative, the remaining capacity calculation routine is terminated. When the determination is affirmative, in step 120, the slope of the approximate straight line obtained from the data of the current I and voltage V selected in step 112 by the least square method, that is, lead The DC internal resistance R of the storage battery 1 is calculated. FIG. 5 schematically shows a plot of the current I and voltage V after selection of the lead storage battery 1 at the time of starting the engine and an approximate straight line obtained from the data of the current I and voltage V by the least square method.

  Next, in step 122, the value of the DC internal resistance R of the lead storage battery 1 calculated in step 120 and the value of the temperature T of the lead storage battery 1 measured in step 110 are stored in the ROM and expanded in the RAM in the initial setting process. The remaining capacity of the lead storage battery 1 is calculated by substituting the relationship between the direct current internal resistance R, the temperature T of the lead storage battery, and the remaining capacity into a predetermined map, and the remaining capacity calculation routine is terminated. FIG. 6 shows a map that defines the relationship between the DC internal resistance R after correction of temperature (for example, to room temperature) and the remaining capacity of the lead storage battery 1.

  By executing the above remaining capacity calculation routine, the CPU, as a rule, calculates the remaining capacity of the lead storage battery 1 every time the engine is started, and thereafter (during vehicle travel), the CPU calculates the remaining capacity of the lead storage battery 1 every predetermined time. The remaining capacity is monitored. That is, after the engine is started, the charging current and the discharging current flowing through the lead storage battery 1 are integrated separately every 1 ms, and the lead storage battery calculated by the remaining capacity calculation routine with the integrated charging current and discharging current every predetermined time. The remaining capacity of 1 is corrected, and the current remaining capacity of the lead storage battery 1 is calculated. However, if a negative determination is made in step 114 or 118 of the remaining capacity calculation routine, the remaining capacity of the lead storage battery 1 at the time of the latest engine start is not calculated in step 122, so the engine start calculated before that The remaining capacity of the lead storage battery 1 at that time is corrected by the charging current and discharge current accumulated so far, and the current remaining capacity of the lead storage battery 1 is calculated.

  Then, the CPU determines whether or not the current remaining capacity of the lead storage battery 1 is larger than a predetermined threshold value. When the remaining capacity is smaller or equal, the CPU stops idling due to power consumption of the lead storage battery 1 by the auxiliary machine 6 or the like. -Since there is a possibility that the engine cannot be restarted at the time of starting, the vehicle control system 11 is notified of the insufficient charging of the lead storage battery 1 (a warning is issued). On the other hand, when it is large, there is no problem in idling stop / start even if power is consumed by the auxiliary machine 6 or the like, so that the vehicle control system 11 is not notified. Receiving this notification, the vehicle control system 11 stops idling stop, supplies the power generated by the generator 7 to the lead storage battery 1, and charges the lead storage battery 1.

(Effects etc.)
Next, effects and the like of the notification system 12 of the present embodiment will be described.

  In the notification system 12 of the present embodiment, the microcomputer 10 (CPU) is measured every 1 ms when the engine is started using a Hall element having a maximum current value that can be detected by the current sensor 4 of 100 A and a detection error of 5% or less. The direct current internal resistance R of the lead storage battery 1 is obtained by the slope of the approximate straight line obtained by the least square method using the current I and the voltage V in the range of −100 A to 0 A flowing through the lead storage battery 1 (step 120). The remaining capacity of the lead storage battery 1 is calculated by substituting the relationship between the direct current resistance R, the temperature T of the lead storage battery 1 and the remaining capacity with the value of the temperature T and the remaining capacity of the lead storage battery 1 into a predetermined map. (Step 122). Therefore, in the notification system 12, even if the current sensor has a performance limit (maximum current value is 100A), it is not affected by the integration error of the charge / discharge current or the change in the initial remaining capacity due to self-discharge. The remaining capacity can be calculated with high accuracy. Further, by using a current sensor having a maximum current value of 100 A, it is possible to reduce the cost of the current measurement component.

  In the notification system 12 of the present embodiment, the current I and voltage V data of −100 A to 0 A after the maximum discharge current value I peak is selected from the accumulated data of the current I and voltage V (step 112). Data on the current I of −100 A to 0 A and the voltage V corresponding to this at the time of sudden discharge from the engine start to the maximum discharge current value Ipeak is excluded. For this reason, the approximate straight line between the current I and the voltage V, in particular, the approximate straight line for obtaining the DC internal resistance R of the lead storage battery 1 can be accurately calculated by the least square method.

  On the other hand, when the number of currents I measured is small, the slope of the approximate line (DC internal resistance R of the lead storage battery 1) varies. In addition, when the correlation coefficient of the approximate line is small, it causes an error when obtaining the approximate line (DC internal resistance R). In this embodiment, when the number of currents I measured is small or the correlation coefficient is small, the remaining capacity is not estimated (steps 114 and 118). FIG. 7 shows an approximate line when the number of measured currents I is less than 150, but the slope of the approximate line is smaller than that of FIG. Is calculated to be small. For this reason, the remaining capacity of the lead storage battery 1 cannot be determined appropriately. In the notification system 12 of the present embodiment, the number of currents I measured is 150 or more, and the correlation coefficient of the approximate line is 0.95 or more, so the remaining capacity of the lead storage battery 1 can be calculated more accurately.

  In addition, the notification system 12 according to the present embodiment corrects the remaining capacity of the lead storage battery 1 calculated every time the engine is started in the remaining capacity calculation routine with the integrated value of the charge / discharge current, and the remaining capacity of the lead storage battery 1 while the vehicle is running. Since the capacity is obtained, it is possible to accurately determine whether or not idling can be stopped and to notify the vehicle control system 11 of it.

  In the present embodiment, the Hall element current sensor 4 capable of detecting current up to 100 A is exemplified, but the present invention is not limited to this, and a current sensor having a maximum detectable current value of about 50 to 200 A is used. In addition, the current may be measured by a shunt circuit including a shunt resistor instead of the Hall element.

  In the present embodiment, an example in which the engine start start (step 102) and the engine start end (step 108) are determined based on the current detected by the current sensor 4 is shown. However, a signal (from the IGN switch 5 or the vehicle control system 11) Notification) may be received.

  Furthermore, in this embodiment, although the map which defined the relationship between direct current | flow internal resistance R, the temperature T of lead acid battery, and remaining capacity was illustrated (refer also FIG. 6), it replaces with a map and uses a numerical formula, a map, and a numerical formula together. You may do it. Moreover, in this embodiment, although the map which defined the relationship between the DC internal resistance R after temperature correction and the remaining capacity of the lead storage battery 1 was illustrated, the remaining capacity of the lead storage battery 1 is calculated from the DC internal resistance R, and the remaining You may make it temperature correct | amend a capacity | capacitance.

  Further, a nonvolatile memory such as an EEPROM may be externally attached to the microcomputer 10 and the remaining capacity of the lead storage battery 1 calculated in step 122 may be written. In such an embodiment, after the operation power is supplied to the microcomputer 10, when the engine is started for the first time, as a result of the negative determination in step 114 or step 118, even if the remaining capacity is not calculated, the previous calculation was performed from the nonvolatile memory. The remaining capacity of the lead storage battery 1 can be read. Alternatively, the remaining capacity of the lead storage battery 1 calculated in step 112 is notified to the vehicle control system 11, and the remaining capacity of the lead storage battery 1 is notified from the vehicle control system 11 as necessary. Good.

  The present invention provides a battery state detection system capable of accurately calculating the remaining capacity of a battery even if the performance limit of the current sensor is limited, and contributes to the manufacture and sale of a battery state detection system or a vehicle equipped with the battery state detection system. Therefore, it has industrial applicability.

It is a block diagram of the alerting | reporting system of embodiment which can apply this invention. It is a flowchart of the remaining capacity calculation routine which CPU of the microcomputer of an alerting | reporting system performs. It is explanatory drawing which shows typically the waveform of the voltage of the lead storage battery at the time of engine starting in a vehicle. It is explanatory drawing which shows typically the waveform of the electric current of the lead acid battery at the time of engine starting in a vehicle. It is explanatory drawing which shows typically the approximate straight line calculated | required by the least squares method from the plot of the electric current of the lead acid battery at the time of engine starting, a voltage, and the data of electric current and voltage. It is explanatory drawing which shows typically the map which defined the relationship between the direct current | flow internal resistance after temperature correction | amendment, and the residual capacity of a lead acid battery. It is explanatory drawing which shows typically an approximate line when the plot of the electric current of the lead acid battery at the time of engine starting and a voltage does not satisfy | fill a threshold value.

Explanation of symbols

1 Lead acid battery (battery)
2 Temperature sensor (part of temperature measurement means)
3 Voltage sensor (part of voltage measurement means)
4 Current sensor 10 Microcomputer (part of current measurement means, part of voltage measurement means, part of temperature measurement means, remaining capacity calculation means)
12 Notification system (battery condition detection system)

Claims (5)

A current measuring unit that has a current sensor capable of detecting a current up to a predetermined current value and having a detection error of 5% or less;
Voltage measuring means for measuring the voltage of the battery;
Temperature measuring means for measuring the temperature of the battery;
A remaining capacity calculating means for calculating a remaining capacity of the battery from a measured amount measured by each of the means;
The remaining capacity calculation means includes a least square method using a current I and a voltage V that are less than the predetermined current value flowing through the battery at the time of engine start, measured at predetermined times by the current measuring means and the voltage measuring means. The DC internal resistance R of the battery is obtained from the slope of the approximate straight line obtained, and the value of the obtained DC internal resistance R and the value of the battery temperature T measured by the temperature measuring means are determined as DC internal resistance R. A battery state detection system, wherein the remaining capacity of the battery is calculated by substituting the relationship between the battery temperature T and the remaining capacity into a predetermined map or mathematical expression.   The battery state detection system according to claim 1, wherein the current sensor is a Hall element or a shunt resistor having a maximum detectable current value of 100 A or less.   The remaining capacity calculation means is measured by the current measurement means and the voltage measurement means at predetermined time intervals, and the current I and voltage less than the predetermined current value flowing through the battery after the engine discharge exceeds the maximum discharge current value Ipeak. 3. The battery state detection system according to claim 1, wherein a direct current internal resistance R of the battery is obtained from an inclination of an approximate straight line obtained by a least square method using V. 4.   The remaining capacity calculating means has the DC internal resistance when the measured value of the current I measured by the current measuring means satisfies 150 or more and the correlation coefficient of the approximate straight line satisfies 0.95 or more. The remaining capacity of the battery is calculated by substituting the value of R and the value of the temperature T of the battery into the map or mathematical expression. Battery status detection system.   An automobile provided with the battery state detection system according to any one of claims 1 to 4.

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