JP2008296689A - Method for preventing over discharge of on-vehicle battery, and power source control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for preventing over discharge of an on-vehicle battery, achieving reduced cost of a component without using a current detector and capable of accurately preventing the over discharge of the on-vehicle battery. <P>SOLUTION: This method prevents the over discharge of the on-vehicle battery charged by a generator generating electric power in conjunction with an engine and supplying generated electric power to a plurality of electric loads. The open voltage value of the on-vehicle battery is detected and stored (S1), the voltage value of the on-vehicle battery is detected (S5), and it is determined whether or not the detected voltage value is below the stored open voltage value (S7). The over discharge of the on-vehicle battery is prevented based on the determined result. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an overdischarge prevention method for an in-vehicle battery for preventing overdischarge of an in-vehicle battery charged by a generator that supplies generated electric power to a plurality of electric loads, and a power source for executing the overdischarge prevention method for the in-vehicle battery. The present invention relates to a control device.

  The number of electrical components mounted on vehicles is increasing steadily in terms of safety, convenience, comfort, and product power. Large-capacity electric loads such as wind defoggers and seat heaters for cold regions are adopted, and equipment that has been operated with hydraulic pressure or engine power is electrified to improve control performance and efficiency. It is out. Electric loads such as electric brakes and electric power steering devices (EPS) that require high reliability have been adopted, and the degree of dependence of vehicles on in-vehicle batteries is increasing.

  In the power supply system of a vehicle, the power generation capability of an alternator (generator) depends on the engine speed, and when idling for a long time due to traffic congestion or the like, the output current decreases as shown in FIG. In this state, as shown in FIG. 7, if the load is used excessively, the total power used for all loads becomes larger than the amount of power generation, and the power supply voltage drops from the output voltage of the generator to the output voltage of the (onboard) battery. . When the power supply voltage is reduced to the output voltage of the battery, as shown in FIG. 6, the discharge current of the battery assists the shortage of the load current, and these relations are summarized as shown in FIG. The output characteristic diagram of the (in-vehicle) generator and the (in-vehicle) battery and the charge / discharge characteristic diagram of the (in-vehicle) battery in FIG.

8 (a) and 8 (b), when the output current (load current) of the generator is increased, the charge / discharge current of the battery is substantially 0 (slightly charged) while the output current is small. is there. When the output current exceeds, for example, about 19 A, the regulator adjustment voltage suddenly decreases because the generated voltage command value cannot be maintained, and accordingly, the battery terminal voltage also decreases abruptly.
The generator increases the output current until the terminal voltage of the battery reaches the open-circuit voltage V _OC (voltage at the time of charge / discharge current 0) while rapidly decreasing the regulator adjustment voltage. When the terminal voltage of the battery becomes equal to or lower than the open circuit voltage V _OC , the battery is discharged when the load current is insufficient.

In Patent Document 1, the output voltage of the battery is monitored, and based on the monitoring result, whether the plunger can be driven, whether the cranking rotational speed is equal to or higher than the engine ignition possible rotational speed, or the cranking rotational speed is until the engine starts. There is disclosed a battery state detection device that performs three condition determinations of whether or not the battery is maintained and determines whether or not the battery is normal based on the determination result.
JP 2006-240541 A

In a vehicle power supply system, if the load is excessively used during idling for a long time, there is a problem that the battery runs out and the engine stops even though the engine is rotating. As a countermeasure against this, a system that detects charging / discharging of a battery by using a current detector and prevents overdischarge has been put into practical use, but the current detector is expensive, and there is a problem that the cost of parts increases.
In addition, there is a method to prevent overdischarge only with the voltage detector, but since the voltage detector cannot detect the discharge of the battery, the object is to maintain the battery in a normal state as compared with the case where the current detector is used. Therefore, there is a problem that accuracy is low.

The present invention has been made in view of the circumstances as described above. In the first to fourth inventions, the component cost is low without using a current detector, and it is possible to prevent over-discharge of an on-vehicle battery with high accuracy. An object of the present invention is to provide a method for preventing overdischarge of an on-vehicle battery.
It is an object of the fifth to eighth aspects of the invention to provide a power supply control device that can prevent over-discharge of an in-vehicle battery with high accuracy without using a current detector and with low component cost.

  According to a first aspect of the present invention, there is provided a method for preventing overdischarge of an in-vehicle battery that is generated by interlocking with an engine and charged by a generator that supplies the generated power to a plurality of electric loads. Detecting and storing the open-circuit voltage value of the in-vehicle battery, detecting the voltage value of the in-vehicle battery, determining whether the detected voltage value is less than the stored open-circuit voltage value; Based on the determined result, over-discharge of the in-vehicle battery is prevented.

  According to a second aspect of the present invention, there is provided an overdischarge prevention method for an in-vehicle battery, wherein the open circuit voltage value is estimated based on a voltage value of the in-vehicle battery detected immediately before the engine is started.

  According to a third aspect of the present invention, there is provided a method for preventing over-discharge of an on-vehicle battery, wherein the electric load having a known resistance value is increased or decreased during an idling period of the engine to obtain a current-voltage characteristic in a region lower than the estimated open-circuit voltage value. Calculate, calculate the discharge current of the in-vehicle battery based on the open-circuit voltage value and the low-voltage current-voltage characteristics, integrate the calculated discharge current, and reduce the operating electrical load based on the integrated discharge current It is characterized by that.

  According to a fourth aspect of the present invention, there is provided a method for preventing overdischarge of an in-vehicle battery, wherein a predetermined voltage value is added to an open-circuit voltage value detected by the in-vehicle battery, an open-circuit voltage value after addition is stored, and the in-vehicle battery detects It is determined whether or not the voltage value is less than the open circuit voltage value after the addition.

  A power supply control device according to a fifth aspect of the present invention is the power supply control device for preventing over-discharge of a vehicle-mounted battery that is generated by interlocking with an engine and charged by a generator that supplies the generated power to a plurality of electric loads. An open-circuit voltage detection means for detecting an open-circuit voltage value of the battery; a storage means for storing the open-circuit voltage value detected by the open-circuit voltage detection means; a voltage detection means for detecting the voltage value of the in-vehicle battery; and the voltage detection means And a means for determining whether or not the voltage value detected by the storage means is less than the open-circuit voltage value stored in the storage means, and based on the result determined by the means, prevents over-discharge of the in-vehicle battery. It is configured as described above.

  In the on-vehicle battery overdischarge prevention method according to the first invention and the power supply control device according to the fifth invention, the on-vehicle battery is generated by being linked to the engine and is charged by a generator that supplies the generated power to a plurality of electric loads. Prevent over-discharge. The open-circuit voltage detection means detects the open-circuit voltage value of the in-vehicle battery, and the storage means stores the open-circuit voltage value detected by the open-circuit voltage detection means. The voltage detection means detects the voltage value of the on-vehicle battery, and the determination means determines whether the voltage value detected by the voltage detection means is less than the open circuit voltage value stored in the storage means, and Based on the determined result, overdischarge of the in-vehicle battery is prevented.

  The power control apparatus according to a sixth aspect of the invention is configured such that the open-circuit voltage detecting means estimates the open-circuit voltage value based on the voltage value detected by the voltage detecting means immediately before the engine is started. It is characterized by that.

  In the on-vehicle battery overdischarge prevention method according to the second aspect of the invention and the power supply control device according to the sixth aspect of the invention, the open-circuit voltage detection means is based on the voltage value detected by the voltage detection means immediately before the engine is started. Is estimated.

  The power supply control device according to a seventh aspect of the invention is a calculation means for calculating a current-voltage characteristic in a region lower than the estimated open-circuit voltage value by performing increase / decrease control of the electric load whose resistance value is known during an idling period of the engine. And means for calculating the discharge current of the in-vehicle battery based on the open circuit voltage value and the current-voltage characteristic calculated by the calculation means, and means for integrating the discharge current calculated by the means, Is configured to reduce the electric load during operation based on the discharge current accumulated by.

  In the on-vehicle battery overdischarge prevention method according to the third invention and the power supply control device according to the seventh invention, the calculation means performs increase / decrease control of the electric load whose resistance value is known during the engine idling period, and estimated opening A means for calculating and calculating a current-voltage characteristic in a region lower than the voltage value calculates a discharge current of the in-vehicle battery based on the open-circuit voltage value and the current-voltage characteristic calculated by the calculating means. The means for integrating integrates the calculated discharge current, and reduces the operating electric load based on the integrated discharge current.

  The power supply control device according to an eighth aspect of the present invention further comprises means for adding a predetermined voltage value to the open-circuit voltage value detected by the open-circuit voltage detection means, and the storage means stores the open-circuit voltage value after addition by the means, It is configured to determine whether or not the voltage value detected by the voltage detection means is less than the open circuit voltage value after addition stored in the storage means.

  In the on-vehicle battery overdischarge prevention method according to the fourth invention and the power supply control device according to the eighth invention, the adding means adds a predetermined voltage value to the open-circuit voltage value detected by the open-circuit voltage detecting means, and the storage means is The open circuit voltage value after the addition is stored. It is determined whether or not the voltage value detected by the voltage detection means is less than the open circuit voltage value after addition stored in the storage means.

  According to the overdischarge prevention method for an in-vehicle battery according to the first to third inventions, the overdischarge prevention of the in-vehicle battery can be prevented with high accuracy and low cost without using a current detector. A method can be realized.

  According to the overdischarge prevention method for an in-vehicle battery according to the fourth aspect of the invention, there is provided an overdischarge prevention method for an in-vehicle battery that can prevent the overdischarge of the in-vehicle battery with high accuracy and low cost without using a current detector. Can be realized. In addition, since the charge amount of the in-vehicle battery can be maintained larger, over-discharge of the in-vehicle battery can be prevented even when left for a longer period.

  According to the power supply control devices according to the fifth to seventh inventions, it is possible to realize a power supply control device that can prevent over-discharge of the in-vehicle battery with high accuracy without using a current detector and with low component cost.

  According to the power supply control device according to the eighth aspect of the present invention, it is possible to realize a power supply control device that can prevent over-discharge of the in-vehicle battery with high accuracy without using a current detector and with low component cost. In addition, since the charge amount of the in-vehicle battery can be maintained larger, over-discharge of the in-vehicle battery can be prevented even when left for a longer period.

Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments thereof.
FIG. 1 is a block diagram showing a schematic configuration of an embodiment of an on-vehicle battery overdischarge prevention method and a power supply control device according to the present invention.
In this power supply control device, DC power generated and rectified by an in-vehicle generator (alternator, AC generator) 7 is supplied to an in-vehicle battery 5 connected in parallel to the generator 7. The generator 7 has a generator body 8 and an internal resistance Ra (regulator is not shown), and the battery 5 has an open voltage (electromotive force) V _OC and an internal resistance Rb.

The DC power generated and rectified by the generator 7 and the power output from the battery 5 are also switched to an ignition switch (hereinafter referred to as IG switch) S5 and switches S1 to S1 disposed in a power distribution box (not shown). The electric loads R _{L1 to} R _L4 are supplied through S4 and supplied to the ignition device 2 only through the IG switch S5. Here, it is assumed that the IG switch S5 includes an accessory switch.

The IG switch S5 is turned on / off when an ignition key (hereinafter referred to as IG key) 1 is turned on / off, and an on / off signal of the IG key 1 is also supplied to the power supply control unit 3. A vehicle speed signal from a vehicle speed sensor (not shown) is also supplied to the power supply control unit 3.
The power control unit 3 is disposed in the power distribution box and controls the switches S1 to S4 on / off.
The voltage detector 4 detects the terminal voltage value of the battery 5 and supplies it to the power supply control unit 3.

Hereinafter, the operation of the power supply control device having such a configuration will be described with reference to the flowcharts of FIGS.
Before the IG key 1 is turned on (S3), the power supply controller 3 sequentially reads the voltage of the battery 5 detected by the voltage detector 4 as the open circuit voltage V _OC , updates it, and stores it (S1). When the IG key 1 is turned on (S3), the predetermined voltage Vd is added to the updated open voltage V _OC (S1), and the open voltage Va after the addition is stored (S4).

Next, the power supply controller 3 reads the voltage V of the battery 5 detected by the voltage detector 4 (S5), and determines whether or not the read voltage V is lower than the open circuit voltage Va after addition (S7). ). If the read voltage V is lower than the open circuit voltage Va, the vehicle speed signal is read (S9), it is determined whether the vehicle speed is 0 (S11), and if the vehicle speed is 0, the time T is counted ( S13).
Next, the power supply control unit 3 determines whether or not the measured time T (S13) is equal to or longer than the predetermined time (S15). If the time T is equal to or longer than the predetermined time, the time T is reset (S17). Thereafter, the IV characteristics of the battery 5 are learned (S19).

When the read voltage V is not lower than the open circuit voltage Va (S7) or when the vehicle speed is not 0 (S11), the power control unit 3 resets the time T (S25), and then the voltage detector 4 detects The voltage V of the battery 5 is read (S5).
The power supply controller 3 reads the voltage V of the battery 5 detected by the voltage detector 4 (S5) unless the time T is longer than the predetermined time (S15).
As described above, by setting the open circuit voltage Va after the addition as a condition for executing the overdischarge prevention operation of the battery 5, as shown in FIG. 5, the charge amount of the battery 5 is maintained to be larger by the added voltage. Therefore, over-discharge of the in-vehicle battery can be prevented even when left for a longer period.

When the power supply control unit 3 learns the IV characteristics of the battery 5 (S19), the switches S1 to S4 are turned on / off to turn on / off the known electrical loads R _{L1 to} R _L4. When the current is supplied to the single resistor or the combined resistor, the voltage V detected by the voltage detector 4 is read.
For example, turn on only the switch S1, when a current is supplied to an electrical load R _L1, the voltage in which the voltage detector 4 detects V1, the current flowing through the electric load R _L1 and I1, V1 = R _L1 × From I1,
I1 = V1 / R _L1 (1)

Here, as shown in FIG. 4, the IV characteristic of the battery 5 is expressed by V = −a × I + b, and when V = V _OC (here, the open-circuit voltage Va after addition is not used). Since I = 0, V _OC = b,
V = −a × I + V _OC (2)
When I = I1 and V = V1, from the equations (1) and (2),
V1 = −a × V1 / R _L1 + V _OC
Therefore, a = (V _OC −V1) R _L1 / V1
Substituting this into equation (2) and summing up for I yields equation (3).
I = (V _OC −V) V1 / (V _OC −V1) R _L1 (3)
From the equation (3), the output current (discharge current) I of the battery 5 can be obtained (estimated) from the voltage V detected by the voltage detector 4.

The power supply control unit 3 learns the IV characteristic of the battery 5 and obtains the expression (3) (S19), and then reads the voltage V of the battery 5 detected by the voltage detector 4 (S21), (3 ) To estimate the discharge current I of the battery 5 (S23).
Next, the power supply controller 3 calculates the integrated value It of the estimated discharge current I (S23) (S27), and determines whether or not the calculated integrated value It is equal to or greater than a predetermined value (S29). If the integrated device It is greater than or equal to a predetermined value, the integrated device It is reset (S38), and then the switches S1 to S4 are turned on / off to reduce the electric loads R _{L1 to} R _L4 that are turned on. The load control is executed (S39), and after the discharge current is reduced, the voltage V of the battery 5 detected by the voltage detector 4 is read (S5).

The power supply control unit 3 reads the voltage V of the battery 5 detected by the voltage detector 4 (S31) unless the integrated value It is greater than or equal to a predetermined value (S29). It is determined whether or not it is lower than the open circuit voltage Va (S33). If the read voltage V is lower than the open circuit voltage Va, the vehicle speed signal is read (S35), and it is determined whether or not the vehicle speed is 0 (S37). If the vehicle speed is 0, the condition for executing the overdischarge prevention operation of the battery 5 is still established, so the voltage V of the battery 5 detected by the voltage detector 4 is read again (S21), (3) Thus, the discharge current I of the battery 5 is estimated (S23).
The power supply control unit 3 reads the voltage V of the battery 5 detected by the voltage detector 4 when the read voltage V is not lower than the open circuit voltage Va (S33) or when the vehicle speed is not 0 (S37) ( S5).

It is a block diagram which shows schematic structure of embodiment of the overdischarge prevention method of a vehicle-mounted battery which concerns on this invention, and a power supply control apparatus. It is a flowchart which shows operation | movement of embodiment of the overdischarge prevention method of a vehicle-mounted battery and power supply control apparatus which concern on this invention. It is a flowchart which shows operation | movement of embodiment of the overdischarge prevention method of a vehicle-mounted battery and power supply control apparatus which concern on this invention. It is a characteristic view which shows the IV characteristic of a vehicle-mounted battery. It is explanatory drawing for demonstrating maintaining the charging amount of a vehicle-mounted battery more largely, and preventing an overdischarge even if left for a long period of time. It is a characteristic view which shows the rotation speed-output current characteristic of a vehicle-mounted generator. It is explanatory drawing which shows the relationship between load current and a power supply voltage. It is a characteristic view which shows the output characteristic of a vehicle-mounted generator and a vehicle-mounted battery, and a characteristic figure which shows the charging / discharging characteristic of a vehicle-mounted battery.

Explanation of symbols

1 Ignition key (IG key)
3 Power Control Unit 4 Voltage Detector 5 (On-vehicle) Battery 7 (On-vehicle) Generator S1 to S4 Switch S5 Ignition Switch (IG Switch)
R _{L1 to} R _L4 electric load

Claims (8)

In a method for preventing over-discharge of an in-vehicle battery that is generated by interlocking with an engine and charged by a generator that supplies the generated power to a plurality of electric loads,
Detecting and storing the open-circuit voltage value of the in-vehicle battery, detecting the voltage value of the in-vehicle battery, determining whether the detected voltage value is less than the stored open-circuit voltage value; An over-discharge prevention method for an in-vehicle battery, wherein over-discharge of the in-vehicle battery is prevented based on the determined result.   The overdischarge prevention method for an in-vehicle battery according to claim 1, wherein the open circuit voltage value is estimated based on a voltage value of the in-vehicle battery detected immediately before the engine is started.   During the idling period of the engine, the electric load whose resistance value is known is increased or decreased to calculate a current-voltage characteristic in a region lower than the estimated open-circuit voltage value, and the open-circuit voltage value and the current-voltage characteristic in a low region The method according to claim 1, further comprising: calculating a discharge current of the in-vehicle battery based on the calculation, integrating the calculated discharge current, and reducing an operating electric load based on the integrated discharge current. .   A predetermined voltage value is added to the open-circuit voltage value detected by the in-vehicle battery, the open-circuit voltage value after addition is stored, and the detected voltage value of the in-vehicle battery is less than the open-circuit voltage value after addition. The overdischarge prevention method of the vehicle-mounted battery of any one of Claims 1 thru | or 3 which determines whether it is. In the power supply control device that prevents overdischarge of the in-vehicle battery that is generated by interlocking with the engine and charged by a generator that supplies the generated power to a plurality of electric loads,
An open-circuit voltage detecting means for detecting an open-circuit voltage value of the in-vehicle battery; a storage means for storing the open-circuit voltage value detected by the open-circuit voltage detecting means; a voltage detecting means for detecting the voltage value of the in-vehicle battery; And a means for determining whether or not the voltage value detected by the detection means is less than the open circuit voltage value stored in the storage means, and based on the result determined by the means, the vehicle battery is overdischarged. A power supply control device characterized by being configured to prevent.   The power supply control device according to claim 5, wherein the open-circuit voltage detection unit is configured to estimate the open-circuit voltage value based on a voltage value detected by the voltage detection unit immediately before the engine is started.   Calculation means for calculating a current-voltage characteristic in a region lower than the estimated open-circuit voltage value by performing increase / decrease control of the electric load having a known resistance value during an idling period of the engine, the open-circuit voltage value, and the calculation Means for calculating the discharge current of the in-vehicle battery based on the current-voltage characteristics calculated by the means, and means for integrating the discharge current calculated by the means, and is operating based on the discharge current accumulated by the means 7. The power supply control device according to claim 5 or 6, wherein the power supply control device is configured to reduce the electrical load.   The circuit further comprises means for adding a predetermined voltage value to the open-circuit voltage value detected by the open-circuit voltage detection means, wherein the storage means stores the open-circuit voltage value after addition by the means, and the voltage value detected by the voltage detection means is The power supply control device according to any one of claims 5 to 7, wherein the power supply control device is configured to determine whether or not the open circuit voltage value after the addition stored in the storage unit is smaller.

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