JP2004359004A - In-vehicle battery control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an in-vehicle battery control device capable of carrying out an initial check to a main battery by a simple circuit structure and processing, while keeping reliability. <P>SOLUTION: A control portion 5 carries out power supply from a main battery MB to a load 17 through a switching portion 1 during a predetermined check period, determines whether a detection voltage detected by a voltage detecting portion 3 during the check period is not less than a standard level or not, and controls the switching portion 1 on the basis of the determined result, thereby determining from which battery between the main battery MB and a sub buttery SB power supply for the normal operation of the load 17 after the expiration of the check period should be carried out. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an in-vehicle battery control device that controls a main battery and a sub-battery provided as an auxiliary for the main battery.
[0002]
[Prior art]
In this type of conventional vehicle battery control device, when the ignition switch is turned on, the main battery status is checked as an initial check before the start of normal operation, and as a result of the check, if there is no abnormality in the main battery status The main battery is used for power supply to the load, and the sub-battery is used for power supply to the load when the main battery has an abnormality such as insufficient battery power.
[0003]
In the initial check for the main battery, power supply from the main battery to the load is performed on a trial basis only for a predetermined check period, and a voltage level and a current level supplied from the main battery to the load during the check period are detected. . Then, the microcomputer determines a state of the main battery such as the remaining battery level based on the detected voltage level and current level. The state determination by the microcomputer using the voltage level and the current level is performed using a preset map based on the voltage level and the current level.
[0004]
[Problems to be solved by the invention]
However, in the above-described conventional vehicle-mounted battery control device, both the voltage level and the current level during the check period are detected, and the initial check for the main battery is performed, so that the state of the main battery can be checked with high reliability. On the other hand, a circuit configuration (current sensor, etc.) for detecting the current level is required, which complicates the circuit configuration and performs complicated processing using a map on the microcomputer based on the detected voltage level and current level. Need to be done.
[0005]
Therefore, an object of the present invention is to provide an in-vehicle battery control device capable of performing an initial check on a main battery with a simple circuit configuration and processing while maintaining reliability.
[0006]
[Means for Solving the Problems]
Technical means for achieving the object is a vehicle-mounted battery control device that controls a main battery and a sub-battery provided as an auxiliary for the main battery, and supplies power to a load using either the main battery or the sub-battery. A switching unit that switches between the first and second operations, a voltage detection unit that detects a voltage at any point on a power supply path between the main battery and the load, and the ignition switch is turned on. The power supply from the main battery is performed through the switching unit for a predetermined check period, and it is determined whether the detection voltage detected by the voltage detection unit during the check period is equal to or higher than a predetermined reference level, By controlling the switching unit based on the determination result, the power supply to the load after the check period has elapsed can be controlled by the main unit. And a control unit for determining whether to perform from any of the battery and the sub-battery.
[0007]
Preferably, the predetermined reference level is set higher by a predetermined value than a minimum value at which the load can operate.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a block diagram of a vehicle-mounted battery control device according to one embodiment of the present invention. The on-vehicle battery control device is mounted on a vehicle and includes a switching unit 1, a voltage detection unit 3, and a control unit 5, and manages and controls a main battery MB and a sub-battery SB mounted on the vehicle. . The sub-battery SB is provided as an auxiliary when an abnormality such as insufficient battery level occurs in the main battery MB, and is used only when the main battery MB has an abnormality.
[0009]
The current output from the alternator 11 is supplied to and stored in the main battery MB, and is also supplied to and stored in the sub-battery SB via the DC / DC converter 13. The current from the main battery MB is supplied to the load 17 via the diode 15 for backflow prevention and the switching unit 1. The current from the sub-battery SB is supplied to the load 17 via the diode 19 for backflow prevention and the switching unit 1.
[0010]
The switching unit 1 switches whether to supply power to the load 17 from the main battery MB or the sub-battery SB under the control of the control unit 5. In the present embodiment, the switching unit 1 is configured by a changeover switch, and switches under control of the control unit 5 which of the main battery MB and the sub-battery SB is connected to the load 17.
[0011]
The voltage detection unit 3 is provided at any point on the power supply path between the main battery SB and the load 17, and detects a voltage (supply voltage to the load 17) at that point. In the example illustrated in FIG. 1, the voltage detection unit 3 is provided upstream of the switching unit 1 and the diode 15 in the energization direction. However, this is merely an example, and the voltage detection unit 3 may be provided at another position. .
[0012]
The control unit 5 is constituted by a microcomputer or the like, and when the ignition switch (not shown) is turned on as shown in the timing waveform C1 in FIG. 2, the control unit 5 controls the main battery MB as shown in the timing waveform C2 in FIG. A predetermined initial check is performed. It should be noted that there is a delay of a minute time dt from when the ignition switch is turned on to when the initial check is started. After the end of the initial check, normal operations such as starting the engine are started.
[0013]
In this initial check, after the ignition switch is turned on and before the normal operation starts, the control unit 5 supplies power from the main battery MB to the load 17 via the switching unit 1 for a predetermined check period T, and The detection voltage of the voltage detection unit 3 during the check period T, that is, the supply voltage (see the waveform C3 in FIG. 2) supplied from the main battery MB to the load 17 is a reference level La registered in advance (FIG. 2). It is determined whether or not this is the case. The reference level La is set higher by a predetermined value than the minimum value at which the load 17 can operate, from the viewpoint of ensuring reliability.
[0014]
Here, as the load 17 used for the initial check, a load that plays an essential role in running the vehicle (for example, a power steering device, an electronically controlled fuel injection device, an automatic transmission device, and the like) can be given.
[0015]
At the time of this initial check, if the state of the main battery MB is good, the output voltage of the main battery MB is maintained at a sufficient level. It does not fall below the level La. On the other hand, for example, when the remaining battery level of the main battery MB is insufficient, the output voltage of the main battery MB also decreases, so the supply voltage to the load 17 during the check period T falls below the reference level La. Therefore, based on the value of the supply voltage to the load 17 during the check period T, it is possible to determine whether the state of the main battery MB is good or not.
[0016]
If the supply voltage to the load 17 during the check period T is equal to or higher than the reference level La and the state of the main battery MB is good, the control unit 5 Is connected to the load 17. In this case, power is supplied from the main battery MB to the normal operation of the load 17 after the elapse of the check period T. On the other hand, when the supply voltage to the load 17 during the check period T is lower than the reference level La and the state of the main battery MB is abnormal due to the initial check, the control unit 5 The SB is connected to the load 17. In this case, power is supplied from the sub-battery SB for the normal operation of the load 17 after the elapse of the check period T.
[0017]
As described above, according to the present embodiment, the supply voltage to the load 17 detected by the voltage detection unit 3 during the predetermined check period T in which power is supplied from the main battery MB to the load 17 on a trial basis is determined by the predetermined reference. Since the control unit 5 determines whether or not the level is equal to or higher than the level La, an initial check on the state of the main battery MB is performed. Therefore, the reliability of the initial check on the main battery MB is maintained by a simple circuit configuration and processing. It can be done while doing.
[0018]
Further, the reference level La, which is a criterion at the time of the initial check for the main battery MB, is set higher by a predetermined value than the minimum value at which the load 17 can operate. Can be initially checked.
[0019]
【The invention's effect】
According to the first aspect of the present invention, during a predetermined check period in which power is supplied from the main battery to the load on a trial basis, the detected voltage on the power supply path from the main battery to the load, which is detected by the voltage detection unit, is a predetermined voltage. An initial check on the state of the main battery is performed by the control unit determining whether or not the level is equal to or higher than the reference level. Therefore, the initial check on the main battery is performed while maintaining reliability by a simple circuit configuration and processing. be able to.
[0020]
According to the second aspect of the present invention, the reference level, which is a criterion at the time of the initial check of the main battery, is set higher by a predetermined value than the minimum value at which the load can operate. The initial check for the main battery can be performed with reliability.
[Brief description of the drawings]
FIG. 1 is a block diagram of a vehicle-mounted battery control device according to an embodiment of the present invention.
FIG. 2 is a diagram for explaining an operation of the vehicle-mounted battery control device of FIG. 1;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Switching part 3 Voltage detection part 5 Control part 17 Load MB Main battery SB Sub-battery

Claims (2)

An in-vehicle battery control device that controls a main battery and a sub-battery provided as an auxiliary thereof,
A switching unit that switches whether to supply power to a load from the main battery or the sub-battery,
A voltage detection unit that detects a voltage at any point on a power supply path between the main battery and the load,
As the ignition switch is turned on, power is supplied from the main battery to the load via the switching unit for a predetermined check period, and a voltage detected by the voltage detection unit during the check period is a predetermined voltage. By determining whether or not the load is equal to or higher than a reference level, and controlling the switching unit based on the determination result, power supply to the load after the check period has elapsed can be performed by either the main battery or the sub-battery. A control unit that determines whether to perform from
An in-vehicle battery control device comprising: The vehicle-mounted battery control device according to claim 1,
The vehicle-mounted battery control device, wherein the predetermined reference level is set higher by a predetermined value than a minimum value at which the load can operate.

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