JP2010052582A - Battery state detection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery state detection system capable of exactly detecting a battery state by preventing an erroneous determination due to the lowering of battery voltage when an ignition is ON. <P>SOLUTION: The battery state detection system 12 includes a microcomputer 10 with built-in voltage sensor 3 and CPU. The CPU measures voltage of a lead battery 1 after the lapse of fixed time after the IGN switch 5 is located at the ON position, when measuring voltage when starting an engine. A capacitor 2 is connected in parallel with the lead battery 1. Even if current flows to a starter 9 and the voltage of the lead battery 1 is lowered since the IGN switch 5 is located at the ON position, the lowering of battery voltage of the lead battery 1 can be prevented from being erroneously decided that the IGN switch 5 is located at an OFF position. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a battery state detection system, and more particularly, to a battery state detection system that detects a battery state of a battery that is mounted on a vehicle and supplies power to a cell motor via an ignition switch when the engine is started.

  In recent years, idling stop / start (hereinafter abbreviated as ISS) has been performed in order to cope with the reduction of exhaust gas from engine cars, and a technique for keeping the battery in a state where idling can be stopped is desired. This type of battery is mounted on a vehicle and supplies power to the cell motor via an ignition switch when starting the engine to start the engine.

  The battery state of the battery can be grasped, for example, by detecting the state of charge (SOC) of the battery or the degree of deterioration (SOH) of the battery. As a technique for estimating the state of charge of the battery, a technique obtained from the differential internal resistance (the slope of the voltage / current line), a technique for integrating the charge / discharge current, and a technique obtained from the open circuit voltage of the battery (eg, see Patent Document 1) Etc. are known. As a technique for estimating the deterioration degree of the battery, a technique is known in which the internal resistance is calculated from the VI characteristic at the time of discharging such as when the engine is started, and the deterioration state is estimated from comparison with the initial value.

Japanese Patent Application No. 5-33161

  In order to accurately estimate the battery status of the battery, the voltage of the battery is incorrect from ignition-on (ignition switch is in the on position) to ignition-off (ignition switch is in the off position). It must be measured without judgment. However, in actuality, the battery state detection system may erroneously determine that the ignition is turned off due to a decrease in the battery voltage when the ignition is turned on. If this erroneous determination is made, the subsequent battery state detection becomes impossible or inaccurate. End up.

  An object of the present invention is to provide a battery state detection system that can accurately detect a battery state by preventing erroneous determination due to a decrease in battery voltage at the time of ignition-on.

  In order to solve the above-mentioned problems, the present invention measures the voltage of a battery in a battery state detection system that detects the battery state of a battery that is mounted on a vehicle and supplies power to a cell motor via an ignition switch when the engine is started. A voltage measuring means; a current measuring means for measuring a charge / discharge current flowing through the battery; a change in the voltage measured by the voltage measuring means at the time of starting the engine and a change in the current measured by the current measuring means; An internal resistance calculating means for calculating an internal resistance; an integrating means for integrating the charge / discharge current measured by the current measuring means; an open circuit voltage of the battery measured by the voltage measuring means when the engine is stopped; and the integrating means Charge state calculation means for calculating the charge state of the battery from the charge / discharge current accumulated in step Voltage measuring means, in the voltage measurement at the time of starting the engine, and measuring the voltage of the battery after the ignition switch has passed a predetermined time after the position in the ON position.

  In the present invention, if a capacitor connected in parallel with the battery and having a predetermined capacity is further provided, when the battery voltage decreases at the time of ignition-on, the capacitor is discharged, so that there is no erroneous determination due to a decrease in the battery voltage. The voltage drop can be alleviated to the extent. The capacitance of such a capacitor may be 40 to 100 μF, for example. Further, the deterioration degree calculating means for calculating the deterioration degree of the battery from the internal resistance value in the new state of the battery calculated by the internal resistance calculating means and the latest internal resistance value of the battery calculated by the internal resistance calculating means. You may make it prepare.

  According to the present invention, even when a current flows to the cell motor due to the ignition switch-on and the battery voltage decreases, the voltage measuring means measures the battery voltage after a certain period of time. It is possible to prevent the voltage drop from being erroneously determined as ignition-off and to obtain an effect that the battery state can be accurately detected.

  Embodiments of a battery state detection system according to the present invention will be described below with reference to the drawings.

<Configuration>
As shown in FIG. 1, the battery state detection system 12 of the present embodiment is fixed to the side of the battery case (battery outer wall) on the side away from the vent plug of the lead battery 1 (battery) mounted on the automobile, A microcomputer (hereinafter abbreviated as a microcomputer) 10 for detecting the battery state of the lead battery 1 is provided. As the lead battery 1, for example, one cell is composed of, for example, six positive electrodes and seven negative electrodes, and a lead battery for automobiles having a nominal 12V in 6 cells in series can be used.

  The microcomputer 10 includes a CPU that functions as a central processing unit, a ROM that stores basic control programs and program data for the battery state detection system 12, a RAM that functions as a work area for the CPU, a non-volatile memory such as an EEPROM (not shown), an A / D An interface for communicating with the converter and the host vehicle-side control system 11 is included.

  The input side of a voltage sensor 3 having a differential amplifier circuit or the like is connected to the positive terminal and the negative terminal of the lead battery 1. A capacitor 2 is connected in parallel with the lead battery 1. The capacity of the capacitor 2 is set to, for example, about 40 μF to 100 μF in the present embodiment in consideration of the overall size of the lead battery 1 and the battery state detection system 12 (to reduce the size). A larger capacity may be used.

  A positive terminal of the lead battery 1 is connected to a central terminal of an ignition switch (hereinafter referred to as IGN switch) 5 via a current sensor 4 constituted by a Hall element or the like. The IGN switch 5 has an OFF terminal, an ON / ACC terminal, and a START terminal in addition to the center terminal, and can be switched and connected in a rotary manner.

  The output side of the current sensor 4 is connected to an A / D converter built in the microcomputer 10, and the microcomputer 10 can capture the charge / discharge current flowing through the lead battery 1 as a digital value. The output side of the voltage sensor 3 is connected to another A / D converter built in the microcomputer 10, and the microcomputer 10 can take in the voltage of the lead battery 1 as a digital value. Note that the battery state detection system 12 includes such wiring.

  On the other hand, on the vehicle side, a starter 9 (cell motor) for transmitting the rotational driving force to the rotating shaft of the engine 8 via a clutch mechanism (not shown) and starting the engine 8 is arranged. The rotating shaft of the engine 8 can transmit power to a generator 7 (alternator) via a clutch mechanism (not shown). When the engine 8 is in a rotating state, the generator is connected via the clutch mechanism. 7 is activated, and power from the generator 7 is supplied (charged) to the auxiliary device 6 such as a lamp, wiper, air conditioner, radio, etc., and the lead battery 1 via a regulator (represented by a rectifying element symbol in FIG. 1). Is done. Such engine control and the like are executed by the vehicle control system 11 on the vehicle (automobile) side.

  The ON / ACC terminal of the IGN switch 5 is connected to one end of the generator 7 via the auxiliary machine 6 and the regulator. The START terminal is connected to one end of the starter 9. Furthermore, the other end of the generator 7, the starter 9 and the auxiliary machine 6, the negative terminal of the lead battery 1, and the microcomputer 10 are connected to the ground. Accordingly, the lead battery 1 is repeatedly charged by the generator 7.

  The microcomputer 10 is supplied with operating power from the lead battery 1 via a power circuit (not shown). Further, the microcomputer 10 knows whether the IGN switch 5 is in the on position (the position of the ON / ACC terminal) or the off position (the position of the OFF terminal) via a switch (not shown).

<Operation>
Next, with reference to a flowchart, the operation of the battery state detection system 12 of the present embodiment will be described with a CPU (hereinafter referred to as a CPU) of the microcomputer 10 as a subject.

  As shown in FIG. 2, when operating power is supplied from the lead battery 1 to the microcomputer 10 via a power circuit (not shown), the CPU performs an initial setting process for expanding a basic control program and program data from the ROM to the RAM. At the same time, the charging / discharging current flowing in the lead battery 1 is measured every predetermined time (for example, 2 msec), and the integration of the charging / discharging current is started separately for the discharge side and the charge side.

  In step 102, the process waits until the IGN switch 5 is positioned at the on position. When it is determined that the IGN switch 5 is positioned in the on position, it is determined in the next step 104 whether or not a predetermined time has elapsed. As this fixed time, for example, a time during which the IGN switch 5 is moved from the ON position to the position of the START terminal by the driver can be set. When the determination is negative, the process waits until a predetermined time is reached. When the determination is affirmative, a battery state calculation process for obtaining SOH and SOC of the lead battery 1 is performed at step 106.

  In step 106, first, the voltage of the lead battery 1 at the time of starting the engine is taken every predetermined time (for example, 2 msec). That is, in the voltage measurement at the time of starting the engine, the CPU measures the voltage of the lead battery 1 after a predetermined time has elapsed after the IGN switch 5 is positioned at the ON position, and stores the measured voltage value in the RAM. During this time, the CPU measures and integrates the charge / discharge current flowing through the lead battery 1. Next, the internal resistance r = ΔV / ΔI of the lead battery 1 is calculated from the change in voltage value (ΔV) and the change in current value (ΔI) stored in the RAM when the engine is started.

  Next, it is determined whether or not the internal resistance r of the lead battery 1 is already stored in the EEPROM. If the determination is negative, the calculated internal resistance r value is used as the internal resistance value of the lead battery 1 in a new state. When the affirmative determination is made, the internal resistance value in the new state of the lead battery 1 written in the predetermined address is read, and SOH = (inside the new state of the lead battery 1 written in the predetermined address) Resistance value) / (value of internal resistance r of lead battery 1 calculated this time) × 100 (the same applies to negative determination).

  Next, the open circuit voltage (OCV) of the lead battery 1 written in a predetermined address of the EEPROM is read (see step 118), and for example, a map or relational expression in which the relationship between the open circuit voltage and the SOC is determined in advance is referred to. Thus, the SOC when the lead battery 1 is at rest is calculated, and the SOC after correcting the amount of electricity corresponding to the SOC with the integrated charge / discharge current is calculated as the SOC of the current (most recent) lead battery 1.

  And the value of SOH and SOC calculated to the vehicle control system 11 is alert | reported as needed. Thereby, the vehicle control system 11 side can know the battery state of the lead battery 1, and can determine, for example, whether the engine can be restarted (ISS) before the engine 8 is stopped.

  In step 108, it is determined whether or not the IGN switch 5 is located at the OFF position. If a negative determination is made, the process returns to step 106. If an affirmative determination is made, end processing is performed in the next step 110.

  In this termination process, the microcomputer 10 shifts to a sleep mode with less power consumption by only operating the timer. At this time, if the charge / discharge current is not integrated, the power consumption of the microcomputer 10 supplied from the lead battery 1 is reduced. If the charge / discharge current is also integrated, the SOC calculation accuracy can be increased.

  Next, in step 112, it is determined whether or not a predetermined time (a time during which the polarization state of the lead battery 1 is eliminated, for example, 6 hours) has elapsed by the timer. If the determination in step 112 is negative, it is determined in the next step 114 whether or not the IGN switch 5 is in the on position. If the determination is negative, the process returns to step 112, and if the determination is affirmative, step 104 is determined. Return to. On the other hand, if the determination in step 112 is affirmative, in step 116, the sleep mode is shifted to the normal mode (the mode in which the microcomputer 10 can detect the battery state of the lead battery 1), and the open circuit voltage ( OCV) is measured, the value of OCV measured in the next step 118 is written in the EEPROM, the normal mode is shifted to the sleep mode, and the flow returns to step 112.

<Action and effect>
Next, the operation and effect of the battery state detection system 12 of this embodiment will be described.

  In the battery state detection system 12 of the present embodiment, the CPU measures the voltage of the lead battery 1 after a certain period of time has elapsed after the IGN switch 5 is located at the ON position in the voltage measurement at the time of engine start (step) 104). For this reason, even if a current flows through the starter 9 due to the IGN switch 5 being in the on position and the voltage of the lead battery 1 is lowered, the voltage drop of the lead battery 1 is erroneously determined as the IGN switch 5 is located in the off position. Can be prevented. Therefore, the battery state detection system 12 can accurately detect the battery state of the lead battery 1.

  Moreover, since the battery state detection system 12 of the present embodiment includes the capacitor 2 connected in parallel with the lead battery 1, when the IGN switch 5 is located at the on position and the voltage of the lead battery 1 decreases, As the capacitor 2 is discharged, the voltage drop can be alleviated to the extent that there is no misjudgment due to a drop in the voltage of the lead battery 1 (incorrect determination that the IGN switch 5 is located at the off position).

  In the present embodiment, for the sake of simplicity, reference is not made to temperature correction. However, if the temperature of the lead battery 1 is measured and temperature correction is performed for the integrated current and internal resistance, the SOC is corrected. , The accuracy of SOH can be further increased.

  Moreover, in this embodiment, although the example which comprised the battery state detection system 12 with the hardware (microcomputer 10) and software (refer flowchart) was shown, this invention is not limited to this and is comprised only with hardware. It may be.

  The present invention provides a battery state detection system capable of accurately detecting a battery state by preventing erroneous determination due to a decrease in battery voltage at the time of ignition-on, and thus contributes to the manufacture and sale of the battery state detection system. So it has industrial applicability.

It is a block wiring diagram of a battery state detection system and a car of an embodiment to which the present invention is applicable. It is a flowchart of the battery state detection routine which CPU of the microcomputer of the battery state detection system of embodiment performs.

Explanation of symbols

1 Lead battery (battery)
2 Capacitor 3 Voltage sensor (part of voltage measurement means)
4 Current sensor (part of current measurement means)
5 Ignition switch 9 Starter (cell motor)
10 Microcomputer (internal resistance calculating means, integrating means, battery state calculating means, deterioration degree calculating means)
12 Battery status detection system

Claims (4)

In a battery state detection system that detects the battery state of a battery that is mounted on a vehicle and supplies power to a cell motor via an ignition switch when the engine is started,
Voltage measuring means for measuring the voltage of the battery;
Current measuring means for measuring charge / discharge current flowing in the battery;
Internal resistance calculating means for calculating the internal resistance of the battery from the change in voltage measured by the voltage measuring means and the change in current measured by the current measuring means when the engine is started;
Integrating means for integrating the charge / discharge current measured by the current measuring means;
Charge state calculation means for calculating the charge state of the battery from the open circuit voltage of the battery measured by the voltage measurement means and the charge / discharge current accumulated by the accumulation means when the engine is stopped;
With
In the voltage measurement at the time of starting the engine, the voltage measuring means measures the voltage of the battery after a predetermined time has elapsed after the ignition switch is located at the ON position.   The battery state detection system according to claim 1, further comprising a capacitor connected in parallel with the battery and having a predetermined capacity.   The battery state detection system according to claim 2, wherein the capacitor has a capacity of 40 to 100 μF.   Deterioration calculation for calculating the deterioration degree of the battery from the internal resistance value of the battery in a new state calculated by the internal resistance calculation means and the latest internal resistance value of the battery calculated by the internal resistance calculation means. The battery state detection system according to claim 1, further comprising means.

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