JP2006149070A - Vehicle battery residual capacity operation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle battery residual capacity operation device that can measure the residual capacity of a battery at higher accuracy compared with a conventional current integration method. <P>SOLUTION: The accurate residual capacity SOC can be obtained by a simple circuit constitution by calculating the loss of the residual capacity SOC caused by the dark current discharge of the in-vehicle battery 20 by using a timer contained in a microcomputer 4, and correcting the residual capacity SOC. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle battery remaining capacity calculation device.

Various methods are known for calculating the remaining capacity of a vehicle battery. In particular, the current integration method for detecting and integrating the charging / discharging current of the battery as described in Patent Document 1 below, for example, is more accurate than that using the battery voltage, so that the remaining capacity (SOC) calculation is performed. Widely used as a method.
JP 2004-85574 A

  However, in recent years, more and more kinds of electronic circuit devices have been mounted on vehicles. Many of these electronic circuit devices have a circuit part (also called an always-on circuit) that is operating for early start of operation or communication maintenance even when the ignition switch is turned off. Battery discharge in the off state (hereinafter also referred to as dark current discharge) has become a state that cannot be ignored. As an example of such an always-on circuit, for example, there is a vehicle security system, a ventilating device during parking, and the like.

  However, since the accuracy of current sensors used for current integration has a certain practical limit, it has been difficult to accurately integrate a small current such as the dark current discharge described above. In addition, when the ignition switch is turned off and the battery discharge current is a small current value such as dark current discharge (hereinafter also referred to as sleep period or sleep mode), the current sensor, its integrating circuit, Continuing such current integration during the sleep period also deviates from the purpose of extending the remaining capacity of the battery because the current consumption of the power supply circuit that supplies constant voltage power supply exceeds the other dark current. Become unrealistic.

  For this reason, when the conventional vehicle battery is kept in a parked state for a long period of time, for example, the remaining capacity decreases due to the dark current discharge, and in some cases, the engine cannot be started.

  In addition, even if the engine can be started, the decrease in the remaining capacity due to the dark current discharge in the sleep period cannot be calculated even if the current integration is started again after the sleep period ends. The remaining capacity of the battery obtained by the integration method becomes an inaccurate value, which leads to various problems due to an unexpected decrease in the remaining capacity.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a vehicle battery remaining capacity calculation device capable of measuring the remaining capacity of the battery with higher accuracy than the conventional current integration method. .

  The vehicle battery remaining capacity computing device of the present invention that solves the above problem is supplied with power from a vehicle-mounted battery, and is supplied with power from the battery, a current sensor that detects charge / discharge current of the battery. And a remaining capacity calculation circuit for a vehicle that calculates the remaining capacity of the battery by integrating the charging / discharging current, and the calculation of the normal charging / discharging of the battery and the remaining capacity calculation circuit A sleep time measurement timer that counts the length of the sleep period during a sleep period in which the battery is idle, and the remaining capacity calculation circuit has a predetermined discharge period in which the battery is discharged during the sleep period at least immediately after the end of the sleep period. Multiply the dark current value by the sleep period to Kicking estimates the sleep period discharge amount of the battery, is characterized by subtracting the sleep period discharge amount from the value immediately before the sleep period of the remaining capacity of the battery and calculates the remaining capacity of the battery.

  That is, in the present invention, when the discharge current of the in-vehicle battery becomes a small value that is not suitable for measurement and the power supply to the current detection circuit function and the integration circuit function is not desirable, that is, when these circuit functions fall into the sleep mode. However, it is noted that only the timer function usually remains in these circuits.

  Utilizing this timer function, the present invention counts the period during which the sleep mode lasts, that is, the length of the sleep period, and after the sleep period ends, a constant sleep period discharge current value (dark current value) is multiplied by this sleep period, Accumulate the discharge current during the sleep period. This is called a sleep period integrated current value. The discharge current in the sleep period is the current consumption of a specific electronic circuit load that constantly consumes power or the amount of self-discharge of the vehicle battery, and can be regarded as almost constant.

  Therefore, even if the sleep period extends over a long period, the amount of discharge during this period can be added to the integrated current value almost accurately by a simple method, reducing the integration error and improving the detection accuracy of the remaining battery capacity. can do. Further, the circuit configuration for dark current integration is not complicated and battery discharge does not increase.

  In a preferred aspect, the remaining capacity calculation circuit periodically estimates the sleep period discharge amount up to the present time during the sleep period, and calculates the sleep period discharge amount from a value immediately before the sleep period of the remaining capacity of the battery. The current remaining capacity of the battery is calculated by subtraction, and it is determined whether or not the remaining capacity of the battery is equal to or less than a predetermined threshold value. That is, in this aspect, the remaining capacity calculation circuit periodically wakes up during the sleep period to check the decrease in the current battery remaining capacity due to the dark current discharge. It is possible to instruct measures that do not fall below the amount of power or a predetermined minimum required amount of power.

  In a preferred aspect, the threshold value is set to a level higher than the required electric energy required for starting the engine. As a result, the engine can be reliably started.

  In a preferred aspect, when the remaining capacity during the sleep period becomes equal to or less than a predetermined threshold value, a predetermined electric load can be cut off or consumed while the discharge current of the battery can be further reduced when the ignition switch is turned off. An emergency dark current reduction circuit for commanding power reduction is provided. As a result, the subsequent decrease in the remaining capacity of the battery can be delayed. As the predetermined electric load, an electronic device other than an electronic device essential for starting the engine, such as an electronic device for entertainment or an electronic device for navigation, is selected. At this time, it is also possible to prohibit the turning on of power devices other than the engine start such as the headlamp.

  In a preferred aspect, there is provided an emergency battery charge command circuit for commanding an automatic engine start after confirming the safety of the engine start when the remaining capacity during the sleep period becomes a predetermined threshold value or less. As a result, as long as there is fuel, it is possible to prevent a state in which the engine cannot be started due to the battery rising. As a safety for starting the engine, for example, a state where the gear is in the parking level may be detected.

  In a preferred aspect, the sleep period is started by a predetermined external signal that causes a low battery discharge state in which the discharge current of the battery falls below a predetermined threshold, and the discharge current of the battery is predetermined during the sleep period. The process is terminated by a predetermined external input signal that causes a large battery discharge state exceeding the threshold value. As a result, current integration is immediately performed during a period in which the current increases, so that the remaining capacity of the battery can be accurately calculated following the current change.

  An embodiment of a vehicle battery remaining capacity computing device of the present invention will be described below for an engine vehicle that provides traveling power only by engine power. However, the vehicle battery remaining capacity computing device of the present invention can also be employed for managing secondary batteries mounted in hybrid vehicles and fuel cell vehicles.

(Circuit configuration)
FIG. 1 is a block circuit diagram showing a vehicle battery management device employing the vehicle battery remaining capacity calculation device of the present invention. This vehicle battery management device includes an external sensor 1, a voltage detection circuit 2, an A / D converter 3, a microcomputer 4, a microcomputer power supply circuit 5, a sensor power supply circuit 6, a sensor side power cut-off switch 7, and a reverse flow cut-off switch. A diode 8 is provided. The A / D converter 3 and the microcomputer 4 are connected by a serial bus 9. Each circuit other than the external sensor 1 is configured as a one-chip microcomputer 10 by a BiCMOS semiconductor chip manufacturing technique. Reference numeral 20 denotes an on-vehicle battery made of a lead battery, which is supplied with power from the vehicle generator 30 and supplies power to various electric loads 40 for the vehicle.

  The external sensor 1 includes a current sensor 11 that detects the charge / discharge current of the in-vehicle battery 20, a temperature sensor 12 that detects the temperature of the in-vehicle battery 20, and an amplifier 13 that amplifies the output voltage of these sensors to an analog voltage of a predetermined magnitude. It consists of. The voltage detection circuit 2 includes an operational amplifier circuit that converts the voltage of the in-vehicle battery 20 into an analog voltage having a predetermined magnitude. Output voltages of the amplifier 13 and the voltage detection circuit 2 are converted into digital signals in time sequence by the A / D converter 3 and read into the microcomputer 4 through the serial bus 9. The in-vehicle battery 20 supplies power to the microcomputer power supply circuit 5 through the backflow blocking diode 8, and supplies power to the sensor power supply circuit 6 through the backflow blocking diode 8 and the sensor side power supply cutoff switch 7. The microcomputer power supply circuit 5 applies a power supply voltage to the microcomputer 4, and the sensor power supply circuit 6 applies a power supply voltage to the external sensor 1, the voltage detection circuit 2, and the A / D converter 3. The sensor power supply circuit 6 is designed with higher accuracy than the microcomputer power supply circuit 5.

(Description of operation)
The operation of the vehicle microcomputer device will be described. The microcomputer 4 has a regular mode, a sleep mode, and an wake mode. The microcomputer 4 determines whether or not an ignition key (not shown) is turned on by an external signal such as an operation signal of the ignition switch, selects the regular mode when it is turned on, and sleep mode when it is turned off. Select. The away mode will also be described later.

(Regular mode)
The operation in the regular mode will be described with reference to the regular mode flowchart shown in FIG. This regular mode starts when the ignition switch is turned on. When the ignition switch is turned on, a voltage of an unillustrated assembled battery, that is, a battery voltage is applied to the microcomputer power supply circuit 5, and the microcomputer power supply circuit 5 supplies the microcomputer 4 with a constant voltage power supply of 5V. When the start signal indicating the ignition switch is turned on, the microcomputer 4 starts the following regular mode.

  In this regular mode routine, each part of the microcomputer is first reset and the sensor-side power cut-off switch 7 is turned on. As a result, the sensor power supply circuit 6 supplies the external sensor 1, the voltage detection circuit 2, and the A / D converter 3 with high-accuracy constant-voltage power supply. After that, after waiting for a short time until the operation states of the external sensor 1, the voltage detection circuit 2 and the A / D converter 3 are stabilized, the battery voltage V, the charging / discharging current I, the battery of the vehicle-mounted battery 20 are passed through the A / D converter 3. The temperature T is detected.

  The microcomputer 4 reads the battery voltage V, the charging / discharging current I, and the battery temperature T of the in-vehicle battery 20 every predetermined time Δtr indicated by the built-in timer, calculates the current integrated value IΔtr, and calculates the current integrated value. IΔtr is added to the past accumulated discharge amount stored in its own accumulation register or subtracted from the remaining capacity SOC to obtain the current accumulated discharge amount or the present remaining capacity SOC. Thereafter, a predetermined other routine is executed. Other routines include a routine for determining whether or not the battery temperature T is within a predetermined range, a battery voltage V detected when the engine is started, and a discharge capacity when the battery is at a high current from the battery voltage V when the engine is started. Routine for determining battery overcharge and overdischarge from battery voltage V and charge / discharge current I, routine for determining full charge state and complete discharge state for canceling current integration error, and calculating on-vehicle Although there is a routine for transmitting the remaining capacity of the battery 20 to an external ECU, etc., these are not the main part of this embodiment and will not be described.

  Next, it is determined whether or not the ignition switch is turned off, and further whether or not the in-vehicle battery 20 is in a large current discharge state. If not, or if the in-vehicle battery 20 is in a large current discharge state, the state of the in-vehicle battery 20 is monitored. The routine is repeated, and if it is off or not in a large current discharge state, the sensor-side power cut-off switch 7 is turned off to cut off the power supply to the sensor power supply circuit 6 and start the sleep mode.

  In addition, the large current discharge state said here means the state in which the vehicle-mounted battery 20 is discharging the discharge current which needs to perform an electric current integration, since the predetermined electric load is on. The determination of the large current discharge state is performed by the vehicle ECU that manages the operating state of the electric load. When the vehicle ECU determines that the large current discharge state is present, a predetermined external signal that commands the maintenance of the regular mode is transmitted to the microcomputer 4. It is easiest to do. As a result, the remaining capacity SOC of the in-vehicle battery 20 can be accurately measured even during a period in which, for example, the headlamp is turned on in the engine stopped state. In addition, the microcomputer 4 itself may monitor the intermittent state of each electric load, or may determine this large current discharge state based on the discharge current of the in-vehicle battery 20.

  Thereby, during the period when the ignition switch is on, the remaining capacity of the in-vehicle battery 20 is periodically measured by the current integration of the in-vehicle battery 20, and the safety ensuring determination of the in-vehicle battery 20 is periodically performed. In this embodiment, the value of the remaining capacity of the in-vehicle battery 20 obtained by the current integration of the in-vehicle battery 20 is retained even in the sleep mode executed after the ignition switch is turned off. Of course, it may be stored in the above, and it is merely a design change matter as appropriate. When the ignition switch is turned off, the power supply to the external sensor 1, the voltage detection circuit 2, the A / D converter 3 and the sensor power supply circuit 6 is cut off except for the microcomputer 4 that needs to be operated subsequently. Therefore, power consumption can be reduced. In particular, the sensor power supply circuit 6 is a high-precision constant-voltage power supply compared to the microcomputer power supply circuit 5 and consumes a large amount of power, so that it can be stopped in the sleep mode is effective in reducing consumption of the in-vehicle battery 20. .

(sleep mode)
The operation of the sleep mode will be described with reference to the flowchart of the sleep mode shown in FIG. In this sleep mode, the microcomputer 4 has an extremely reduced clock frequency and its power consumption is reduced. In the sleep mode, the microcomputer 4 may instruct the microcomputer power supply circuit 5 to reduce the output voltage within a range that does not hinder the operation of the microcomputer 4 and perform further power saving. In addition, power supply to circuit parts such as an internal register and a memory which are not necessary for executing the sleep mode among the respective circuits of the microcomputer 4 may be stopped.

  In the sleep mode, first, the count of the built-in timer, that is, the timing program is started from zero. Next, an external signal from the vehicle ECU is determined to determine whether or not the above-described large current discharge state is reached. If it is not a high current discharge state, it is determined whether or not an external signal indicating that the ignition switch is turned on is input. If it occurs, the wake mode described later is started. If not, it is determined whether the built-in timer has reached the predetermined set time. If not, the ignition switch state is set. Returning to the determination step, if it has reached, the wake mode is started and the routine is terminated.

  In this embodiment, power is not supplied to the sensor power supply circuit 6 in the sleep mode and the wake mode in order to save power. However, when the discharge current of the in-vehicle battery 20 is detected in the sleep mode, this discharge current is When the predetermined threshold value is exceeded, it may be determined that the current discharge state is high.

  The above-mentioned predetermined wake condition has occurred when a determination result based on a predetermined external signal input to the microcomputer 4 or a predetermined determination signal detected or calculated by the microcomputer 4 is satisfied. Since a specific example of the wake condition is not a main part of this embodiment, the description thereof is omitted.

(Away mode)
The operation in the wake mode will be described with reference to the flowchart in the wake mode shown in FIG. In this wake mode, a predetermined dark current value id is added to the sleep mode duration Δta counted by the built-in timer to obtain the dark current discharge amount idΔta discharged by the in-vehicle battery 20 during the sleep period thus far. . The dark current value id is a total value of the self-discharge amount of the in-vehicle battery 20, the standby power of the in-vehicle electronic device, and the power consumption of the electronic device that needs to be fed even when the ignition switch is turned off.

  Next, the remaining capacity SOC is newly calculated by subtracting the remaining capacity SOC by an amount corresponding to the dark current discharge amount from the remaining capacity SOC of the in-vehicle battery 20 that is held. Next, it is determined whether or not the calculated remaining capacity SOC has fallen below a predetermined remaining capacity threshold value SOCth1, and if it falls, standby current of an electronic device for entertainment is mainly cut.

  Next, it is determined whether or not the calculated remaining capacity SOC has fallen below a predetermined remaining capacity threshold value SOCth2 that is smaller than the remaining capacity threshold value SOCth1, and if so, it is confirmed whether or not the gear state of the vehicle is in the parking state. The in-vehicle battery 20 is charged by operating the engine for a predetermined short time. Naturally, the remaining capacity threshold value SOCth2 is set to a value exceeding at least the minimum electric energy required for starting the engine.

  In addition, it may be confirmed whether or not the occupant is seated in the driver's seat using an occupant sensor or the like, and if the occupant is seated, an alarm requesting the occupant to start the engine may be output. Of course, this warning can be reported regardless of the gear state of the vehicle. With this wake mode, the in-vehicle battery 20 rises due to long-term parking or the like, and the problem that the engine cannot be restarted can be solved.

  Also, although not shown in FIG. 4, when a large current discharge occurs due to turning on of the electric load during execution of the wake mode or when the ignition switch is turned on and current integration is required, the regular integration is performed immediately. It goes without saying that the mode is changed.

(Explanation of charge state)
FIG. 5 shows a change in the remaining capacity SOC of the in-vehicle battery 20 when the sleep mode is relatively short. The engine is stopped at time t1, and then the main electrical load is cut off at time t2, the regular mode is terminated, and the sleep mode is started. At time t3, some electric load is turned on, and the regular mode is started by inputting a large current discharge signal. At time t4, the electric load is turned off, the regular mode is ended, and the sleep mode is started again.

  FIG. 6 shows a change in the remaining capacity SOC of the in-vehicle battery 20 when the sleep mode continues for a relatively long time. The engine is stopped at time t1, and then the main electrical load is cut off at time t5, the regular mode is terminated, and the sleep mode is started. When the sleep mode continues for a certain period of time T1, the wake mode is executed at time t6, dark current integration is performed, and the remaining capacity SOC is confirmed. This wake mode is also performed at time t7 after a certain time T1, and after that, some electric load is turned on, the regular mode is started by input of a large current discharge signal, and current integration is performed.

(Modification)
In the above-described embodiment, the dark current value id is constant. However, the change may be based on the temperature or the deterioration state of the in-vehicle battery 20 as a matter of design change as appropriate.

1 is a block circuit diagram illustrating a microcomputer device for a vehicle according to a first embodiment. It is a flowchart which shows the regular mode of the microcomputer apparatus for vehicles of FIG. It is a flowchart which shows the sleep mode of the microcomputer apparatus for vehicles of FIG. It is a flowchart which shows the away mode of the microcomputer apparatus for vehicles of FIG. It is a time chart which shows change of remaining capacity SOC in a sleep mode. It is a time chart which shows change of remaining capacity SOC in a sleep mode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 External sensor 2 Voltage detection circuit 3 A / D converter 4 Microcomputer 5 Microcomputer power supply circuit 6 Sensor power supply circuit 7 Sensor side power cut-off switch 10 1-chip microcomputer 11 Current sensor 12 Temperature sensor 13 Amplifier 20 In-vehicle battery 30 For vehicle Generator 40 Electric load for vehicles

Claims (6)

A current sensor that receives power from an in-vehicle battery and detects charge / discharge current of the battery; and
A remaining capacity calculation circuit for calculating a remaining capacity of the battery by supplying power from the battery and integrating the charge / discharge current;
In a vehicle battery remaining capacity calculation device comprising:
A sleep time measurement timer that counts the length of the sleep period during a sleep period in which the calculation of the remaining charge and discharge of the battery and the remaining capacity calculation circuit pauses;
The remaining capacity calculation circuit includes:
At least immediately after the end of the sleep period, a predetermined dark current value that the battery discharges during the sleep period is multiplied by the sleep period to estimate the sleep period discharge amount of the battery during the sleep period, and the remaining capacity of the battery A remaining battery capacity calculation device for a vehicle, wherein the remaining battery capacity is calculated by subtracting the sleep period discharge amount from a value immediately before the sleep period. In the vehicle battery remaining capacity calculation device according to claim 1,
The remaining capacity calculation circuit includes:
The amount of discharge during the sleep period is periodically estimated during the sleep period, and the current remaining capacity of the battery is calculated by subtracting the amount of discharge during the sleep period from the value immediately before the sleep period of the remaining capacity of the battery. The battery remaining capacity computing device for a vehicle is characterized by determining whether or not the remaining capacity of the battery is equal to or less than a predetermined threshold value. In the vehicle battery remaining capacity calculating device according to claim 2,
The vehicle battery remaining capacity calculation device according to claim 1, wherein the threshold value is set to a level higher than an essential electric energy required for starting the engine. In the vehicle battery remaining capacity calculation device according to claim 3,
When the remaining capacity during the sleep period falls below a predetermined threshold value, a command to cut off a predetermined electric load or reduce power consumption that can further reduce the discharge current of the battery with the ignition switch turned off is commanded. A vehicle battery remaining capacity computing device comprising an emergency dark current reduction circuit. In the vehicle battery remaining capacity calculation device according to claim 3,
A vehicle having an emergency battery charge command circuit for commanding an automatic engine start after confirming the safety of the engine start when the remaining capacity during the sleep period becomes a predetermined threshold value or less. Battery remaining capacity calculator. In the vehicle battery remaining capacity calculation device according to claim 1,
The sleep period is
Initiated by a predetermined external signal that causes a battery small discharge condition where the battery discharge current is below a predetermined threshold;
The vehicle battery remaining capacity computing device is terminated by a predetermined external input signal that causes a large battery discharge state in which the battery discharge current exceeds a predetermined threshold value during the sleep period.

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