JP2005073379A - Device for judging battery charge state of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a misjudge at the time of judging a battery state of charge by a battery charge current value. <P>SOLUTION: This device computes the number of revolutions of a generator, the current consumption value of a vehicle electric load apparatus, and the power generation critical current value of the generator severally(steps 1-3), and subtracts the current consumption value of the vehicle electric load apparatus from the power generation critical current value so as to compute a power generation surplus current value (step 4). Only in case this power generation surplus current value is not less than a specified reference value (step 5), this judges the battery state of charge by the battery charge current value (step 6). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an apparatus for determining a battery charge state of a vehicle.

Conventionally, as disclosed in Patent Document 1, a generator (alternator) driven by an engine and capable of controlling a generated voltage, and a battery charged by the generated power of the generator, Alternatively, when power is supplied from a battery to a vehicle electrical load device, a device that variably controls a target power generation voltage (power generation voltage command value) of a generator is known for improving fuel efficiency.
JP-A-7-87680

However, since the maximum generated current value of the generator is limited according to the number of revolutions of the generator, if the power demand of the vehicle electrical load equipment is high, the charging current value to the battery is limited regardless of the battery capacity. Is done.
Here, for example, when it is determined that a predetermined level of charging has been performed on the battery based on the charging current value of the battery, the battery is brought to a predetermined level when the amount of charge to the battery is low due to a small amount of surplus power generated by the generator. There was a problem that there was a possibility that it was erroneously determined that the charging was completed.

For this reason, when the charging current value of the battery mounted on the vehicle is monitored during engine rotation, and this value is used for the determination of the battery charging state, the magnitude of the battery current value depends on the capacity of the battery or the power generation surplus. It is necessary to determine whether it is due to restrictions.
The present invention has been made in view of the above problems, and an object of the present invention is to prevent erroneous determination when determining the battery charge state based on the battery charge current value.

  Therefore, in the present invention, the battery charge state is determined using the battery charge current value only when the power generation surplus of the generator is equal to or greater than a predetermined value.

  According to the present invention, in a state where the power demand of the vehicle electrical load device is excessive and the battery charging current value is small due to the lack of power generation capacity of the generator, the battery charging current value is It is possible to prevent erroneous determination as being small.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of a vehicle battery charge state determination device.
As illustrated, a generator (alternator) 2 is attached to the engine 1, and the generator 2 is driven by the engine 1 to generate power. The generator 2 is connected to the battery 4 via the electric wire 3. A current sensor 5 is attached to the battery 4, and a signal from the sensor 5 is sent to the vehicle controller 6. Further, a rotation speed sensor 9 for detecting the rotation speed is attached to the generator 2, and this signal is also sent to the vehicle controller 6.

The vehicle controller 6 performs various calculations for controlling the engine 1, sets a target power generation voltage (power generation voltage command value) of the generator 2, controls a CAN (Controller Area Network) 8, and charges the battery 4 (charge amount SOC). : State Of Charge).
When the generator 2 driven by the engine 1 generates power, the battery 4 is charged with electric current via the electric wire 3 and vehicle electric load equipment (window defogger, heater fan, headlight, etc.) 7 To supply power. On the other hand, when the battery voltage is larger than the power generation voltage of the generator 2 (battery voltage> power generation voltage of the power generator), power is supplied from the battery 4 to the vehicle electrical load device 7.

Here, it is known that the power generation voltage of the generator 2 is made variable to control the amount of power generation during traveling to improve fuel consumption and power performance. In order to improve fuel efficiency, a means is known in which the power generation amount of the generator 2 is increased when the deceleration fuel is cut to positively charge the battery 4 and the subsequent power generation amount of the generator 2 is suppressed.
Moreover, if the target power generation voltage can be lowered with respect to the voltage setting in the conventional regulator, the current consumption can be reduced (resistance load) and the driving torque of the generator can be reduced. As a result, fuel efficiency can be improved.

However, since the battery 4 that has always been controlled at full charge is not always controlled at full charge by performing power generation control, there is a concern that the battery is insufficiently charged. In order to solve this and further improve fuel efficiency, it is necessary to grasp to some extent the state of charge of the battery 4 which is one of the controlled objects.
It is conceivable to use the battery current value detected by the current sensor 5 as a means for grasping the state of charge of the battery 4 relatively easily.

Hereinafter, determination of the state of charge of the battery according to the present invention will be described with reference to FIGS.
FIG. 2 is a flowchart for determining when to determine the battery charge state based on the battery charge current value in the first embodiment. FIG. 3 is a diagram showing a power generation limit current value at the rotation speed of the generator 2.
FIG. 4 is a diagram showing a generated current value, a battery charging current value, and a consumed current value of the vehicle electrical load device 7 when the generator 2 is at a predetermined rotation speed. Note that the generated current value of the generator 2 in FIG. 4 is the sum of the consumed current value of the vehicle electrical load device 7 and the battery charging current value.

FIG. 5 is a diagram illustrating a state where the current consumption value of the vehicle electrical load device 7 in FIG. 4 is increased and the battery charging current value is limited. 3 to 5, the horizontal axis represents the rotational speed (rpm) of the generator 2 and the vertical axis represents the current value (A). FIG. 6 is a diagram illustrating the battery charge amount according to the battery charge current value at each target power generation voltage of the generator 2.
In step 1 of FIG. 2 (shown as “S1” in the figure, the same applies hereinafter), the rotational speed of the generator 2 is calculated based on the signal from the rotational speed sensor 9. The rotational speed of the generator 2 may be calculated based on an output signal of a sensor (crank angle sensor) that measures the rotational speed of the engine 1.

In step 2, the current consumption value of the vehicle electrical load device 7 is calculated. If the switches such as the window defogger, the fan heater, and the headlight which are the vehicle electrical load device 7 are ON, the current consumption value is added to the current consumption values of the devices 7 that are turned on. Calculated by
In step 3, the power generation limit current value of the generator 2 for each rotation speed is calculated. The power generation limit current value of the generator 2 is calculated from the power generation limit current value calculation table of the generator 2 shown in FIG. As shown in FIG. 3, when the rotational speed of the generator 2 is small, the power generation limit current value also decreases, whereas when the rotational speed of the generator 2 is large, the power generation limit current value tends to increase.

  Here, since the power generation limit current value of the generator 2 is limited in accordance with the number of revolutions of the generator 2, if the power demand of the vehicle electrical load device 7 is high, the power to the battery 4 is limited regardless of the capacity of the battery 4. The charging current value is limited (see B in FIG. 5). For this reason, when the charging current value of the battery 4 mounted on the vehicle is monitored during engine rotation and this value is used for determination of the battery charging state, whether the battery charging value depends on the capacity of the battery 4 or the remaining power generation capacity. It is necessary to determine whether it is due to restrictions by

Therefore, in step 4, the power generation surplus current value (power generation limit current value−vehicle consumption current value) is calculated by subtracting the current consumption value of the vehicle electrical load device 7 from the power generation limit current value of the generator 2.
In step 5, it is determined whether or not the power generation surplus current value is equal to or greater than the battery charging current reference value (predetermined reference value) for determining the battery charging state. The battery charging current reference value is set to a certain value (for example, 10 A).

  Then, as shown in FIG. 4, when the power generation limit current value of the generator 2 is larger than the sum of the battery charging current value and the power consumption of the vehicle electrical load device 7, that is, the power generation surplus current value is equal to or greater than the battery charging current reference value ( When power generation limit current value ≧ battery charging current reference value), the process proceeds to step 6. Thereby, the process of step 6 is performed only when the generated current value of the generator 2 is sufficiently larger than the consumed current value of the vehicle electrical load device 7.

  On the other hand, as shown in FIG. 5, when the current consumption value of the vehicle electrical load device 7 is large and the current value actually charged in the battery 4 is small due to the power generation limit current value of the generator 2 (A → B in the figure). State), that is, when the power generation surplus current value is less than the battery charging current reference value (power generation limit current value <battery charging current reference value), the process is performed without determining the battery charging state based on the battery charging current value. Exit.

Thus, when it is determined that the battery 4 has been charged at a predetermined level based on the charging current value of the battery 4, when the amount of charge to the battery 4 is low due to the small power generation surplus current value of the generator 2, It is possible to prevent erroneous determination that the battery 4 has been charged to a predetermined level.
In step 6, the battery charge state is determined based on the battery charge current value. This determination calculates | requires battery charge amount (%) from the target electric power generation voltage of the generator 2, and the present battery charging current value (A), as shown in FIG. When the battery charging current value reaches a predetermined value or less, it is determined that the battery 4 is substantially fully charged. This is because the power generation current of the generator 2 is larger than the predetermined reference value in step 5, that is, the power generation surplus current value is sufficiently large, so that the battery charging current value decreases as the battery 4 approaches substantially full charge, This is because the state of charge of the battery 4 can be determined.

The battery charging current value in step 6 may be an absolute value.
According to this embodiment, the generator 2 that is driven by the engine 1 and the battery 4 that is charged by the generated power of the generator 2 are provided, and the electric power is supplied to the vehicle electrical load device 7 by the generator 2 or the battery 4. In the generator control device for the vehicle that supplies the battery, the battery charging state is determined using the battery charging current value only when the power generation surplus of the generator 2 is equal to or greater than a predetermined value (step 5) (step 6). For this reason, only when the power generation surplus of the generator 2 is equal to or greater than a predetermined value, the battery charge state is determined based on the battery charge current value. On the other hand, if it is less than the predetermined value, the determination is not performed. Judgment can be prevented. For example, in a scene where the electric load of the vehicle electric load device 7 is excessive and the battery charging current value is small due to the lack of power generation capacity of the generator 2, the battery charging current value due to the high charge amount of the battery 4 is small. Can be prevented from being erroneously determined.

  Further, according to the present embodiment, the power generation surplus is calculated as a power generation surplus current value by subtracting the current consumption value of the vehicle electrical load device 7 from the power generation limit current value of the generator 2 for each rotation speed (step 4). Only when the power generation surplus current value is equal to or greater than the battery charging current reference value (step 5), the battery charging state is determined using the battery charging current value (step 6). For this reason, the battery charge state can always be determined using the battery charge current value flowing into the battery 4 from the generator 2.

According to the present embodiment, the determination of the battery charge state is performed by obtaining the battery charge amount according to the generated voltage of the generator 2 and the battery charge current value (step 6). For this reason, while preventing the above-mentioned misjudgment, the charge amount of the battery 4 can be calculated | required.
According to the present embodiment, the battery charging state is determined that the battery 4 is substantially fully charged when the battery charging current value is equal to or less than a predetermined value (step 6). For this reason, while preventing the above-mentioned erroneous determination, it can determine when the battery 4 has reached full charge.

Next, a second embodiment of the present invention will be described with reference to FIG. In the present embodiment, steps 11 to 13 are different from the first embodiment.
In step 1, the rotational speed of the generator 2 is calculated based on the signal from the rotational speed sensor 9.
In step 11, the current generated current value of the generator 2 is calculated using a map (not shown) between the rotational speed of the generator 2 and the target generated voltage. This map shows that the generated current value decreases when the rotational speed of the generator 2 and the target generated voltage are low, but the generated current value tends to increase when the rotational speed of the generator 2 and the target generated voltage are high. When the number increases, the generated current value is suppressed. Note that the generator 2 may be provided with a current sensor (not shown) to measure the generated current value of the generator 2.

In step 3, the power generation limit current value of the generator 2 for each rotation speed is calculated. The power generation limit current value of the generator 2 is calculated from the power generation limit current value calculation table of the generator 2 shown in FIG.
In step 12, the power generation surplus current value of the generator 2 is calculated by subtracting the current power generation current value of the generator 2 from the power generation limit current value for each rotation speed (power generation limit current value−current power generation current value).
In step 13, it is determined whether the power generation surplus current value (power generation limit current value−current power generation current value) calculated in step 12 is greater than 0 (power generation surplus current value> 0). Thereby, the presence or absence of power generation surplus is determined.

Then, as shown in FIG. 4, when the power generation surplus current value is larger than 0 (power generation surplus current value> 0), the process proceeds to Step 6. As a result, the process of step 6 is performed only when there is surplus power.
On the other hand, as shown in FIG. 5, when the power generation surplus current value is 0 or less (power generation surplus current value ≦ 0), the process is terminated without determining the battery charge state. As a result, in the scene where the electric load of the vehicle electric load device 7 is excessive and the battery charging current value is limited due to the absence of power generation capacity of the generator 2, it is erroneously assumed that the battery 4 has reached full charge. Prevent judging.

In step 6, the battery charge state is determined based on the battery charge current value.
In this embodiment, the power generation surplus current value is calculated as a power generation surplus current value by subtracting the current power generation current value of the power generator from the power generation limit current value of the power generator 2 for each rotation speed (step 12). Only when it is determined that is higher than 0 (step 13), the battery charging state is determined using the battery charging current value (step 6). For this reason, it is possible to determine the battery charge state using the battery charge current value only when there is power generation surplus. For example, in a scene where the electric load of the vehicle electric load device 7 is excessive and the battery charging current value is small due to the lack of power generation capacity of the generator 2, the battery charging current value due to the high charge amount of the battery 4. Can be prevented from being erroneously determined to be small.

Configuration diagram of vehicle generator control device Flowchart for determining when to determine the battery charge state The figure which shows the power generation limit current value of the generator The figure which shows the electric power generation electric current value, a battery charging current value, and the consumption electric current value of a vehicle electric load apparatus. The figure which shows the state in which battery charging current value is restrict | limited The figure which shows the battery charge amount according to the battery charge current value in target electric power generation voltage Flowchart for determining when to determine the battery charge state

Explanation of symbols

1 Engine 2 Generator (alternator)
3 Electric wire 4 Battery 5 Current sensor 6 Vehicle controller 7 Vehicle electric load device 8 CAN
9 Speed sensor

Claims (5)

In a generator control device for a vehicle that includes a generator driven by an engine and a battery that is charged by electric power generated by the generator, and supplies electric power to the vehicle electrical load device by the generator or the battery,
A battery charge state determination device for a vehicle, wherein a battery charge state is determined using a battery charge current value only when a power generation surplus of a generator is equal to or greater than a predetermined value.   The power generation surplus is calculated as a power generation surplus current value by subtracting the current consumption value of the vehicle electrical load device from the power generation limit current value of the generator for each rotation speed, and when the power generation surplus current value is equal to or greater than the battery charging current reference value The battery charge state determination device for a vehicle according to claim 1, wherein the battery charge state is determined using only the battery charge current value.   When the power generation surplus current value is calculated as a power generation surplus current value by subtracting the current power generation current value of the generator from the power generation limit current value of the generator for each rotation speed, and it is determined that the power generation surplus current value is higher than 0 The battery charge state determination device for a vehicle according to claim 1, wherein the battery charge state is determined using only the battery charge current value.   4. The vehicle battery according to claim 1, wherein the battery charge state is determined by determining a battery charge amount according to a power generation voltage of the generator and a battery charge current value. 5. Charge state determination device.   5. The battery charge state determination device for a vehicle according to claim 4, wherein the battery charge state is determined that the battery is substantially fully charged when a battery charge current value is equal to or less than a predetermined value.

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