JP2004297852A - Controllfr for battery of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To offer a controller for the battery of a vechile, which can suppress a power consumption and can compute the residual capacity of a battery, securing a precision sufficient for practical use. <P>SOLUTION: This controller has temperature detecting means 12 and 13 that detect the cooling water temperature and the ambient temperature of an engine 2, a storage means 14 which stores the cooling water temperature Twini and the ambient temperatures TAoff detected at ignition off, a voltage measuring means 11 which measures the path opening volatge of a battery 9, and an operation means 6 which operates the estimated water temperature Twx after lappse of a certain time since ignition off, based on the outside air temperature TA detected at ignition on after ignition off. This controller compares the coolling water temperature Tw detected at ignition on with the estimated water temperature Twx, and in case the cooling water temperature Tw is lower than the estimated water temperature Twx, it computes the residual capacity of a battery to the path opening voltage measured at ignition on, and in case the cooling water temperature Tw is higher than the estimated water temperature Twx, it uses the residual capacity of the battery at ignition off or just after it. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a vehicular battery control device for detecting a remaining capacity of a battery mounted on a vehicle.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a technique for estimating a state of charge (SOC) of a battery (storage battery) using an open circuit voltage (OCV) has been known. The battery has a characteristic that the open-circuit voltage changes depending on the concentration of the electrolytic solution, and the open-circuit voltage is proportional to the remaining capacity. Therefore, the remaining capacity can be estimated by using the open-circuit voltage.
By the way, if the electrolyte concentration of the battery is not stable, the remaining capacity estimated from the detected open circuit voltage has a large error from the actual remaining capacity. Therefore, when detecting the open circuit voltage, it is necessary to leave the battery unloaded for a certain period of time (for example, several hours) after use in order to stabilize the concentration of the electrolytic solution in the battery. However, in the case of a battery mounted on a vehicle, since the battery is often restarted before the predetermined time has elapsed, even if the open circuit voltage is measured and the remaining capacity is estimated, sufficient accuracy for practical use is obtained. In many cases, it cannot be secured.
On the other hand, in Patent Document 1, the remaining capacity of a battery mounted on a vehicle is periodically measured, and a correspondence relationship between a battery voltage at a predetermined timing and a battery open circuit voltage after the battery is sufficiently left is determined in advance. In addition, a technique has been proposed for estimating the remaining capacity of a battery based on an open circuit voltage corresponding to a battery voltage sampled at a predetermined timing.
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-134706
[Problems to be solved by the invention]
However, in the above-described conventional technique, even after the vehicle is stopped (ignition off), it is necessary to operate a device (e.g., ECU) for measuring the elapsed time after the vehicle is stopped or a battery voltage detection device. Electric power is consumed even when the vehicle stops. For this reason, it is necessary to secure the electric power at the time of starting the vehicle after the vehicle stops, and it is necessary to perform control for monitoring the state of the device that operates when the vehicle stops, which causes a problem that the control load is large.
[0005]
The present invention has been made in view of such circumstances, and suppresses the power consumption from the time when the ignition is turned off to the time when the ignition is turned on again, and calculates the remaining capacity of the battery with sufficient accuracy for practical use. It is an object of the present invention to provide a vehicle battery control device that can perform the control.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention described in claim 1 is based on temperature detection means (for example, a water temperature sensor 12 in the embodiment) for detecting a cooling water temperature and an outside air temperature of an engine (for example, the engine 2 in the embodiment). , An outside air temperature sensor 13), a storage unit (for example, the memory 14 in the embodiment) for storing the cooling water temperature Twini and the outside air temperature TAoff detected when the ignition is turned off, and a voltage measurement unit for measuring the open circuit voltage of the battery ( For example, based on the voltage sensor 11 in the embodiment and the outside air temperature TA detected when the ignition is turned on after the ignition is turned off, a calculation unit (for example, a calculation unit that calculates a predicted water temperature Twx after a lapse of a predetermined time after the ignition is turned off) ECU 6) according to the embodiment, and a coolant temperature detected when the ignition is turned on. w and the predicted water temperature Twx, and when the cooling water temperature Tw is lower than the predicted water temperature Twx, the remaining battery capacity with respect to the open circuit voltage measured at the time of turning on the ignition is calculated. When the temperature is higher than the predicted water temperature Twx, the remaining battery capacity at or immediately after the ignition is turned off is used.
[0007]
According to the present invention, when the ignition is turned off, the cooling water temperature Twini and the outside air temperature TAoff are detected by the temperature detecting means, and the temperatures Twini and TAoff are stored in the storage means, and then the vehicle is stopped (ignition is stopped). Off). Next, when the ignition is turned on after the ignition is turned off, the cooling water temperature Tw and the outside air temperature TA are detected by the temperature detecting means. Then, a predicted water temperature Twx after the lapse of the predetermined time at the outside air temperature TAoff is calculated by the calculating means. The cooling water temperature Tw is compared with the predicted water temperature Twx after the lapse of the predetermined time. Here, the certain time is preferably set to a time during which it can be determined that the electrolyte concentration of the battery is stable. Since the cooling water temperature Twini at the time of the ignition off is higher than the normal temperature, it decreases as time passes. Therefore, when the cooling water temperature Tw is lower than the predicted water temperature Twx, it can be estimated that the ignition is turned on after the lapse of the predetermined time. In this case, since it can be estimated that the electrolyte concentration of the battery is stable, the remaining battery capacity with respect to the open circuit voltage measured when the ignition is turned on is calculated. When the cooling water temperature Tw is higher than the predicted water temperature Twx, it can be estimated that the ignition has been turned on before the predetermined time has elapsed. In this case, since it can be estimated that the electrolyte concentration of the battery is not yet stable, the remaining battery capacity at or immediately after the ignition is turned off is used. As described above, if the water temperature and the outside air temperature are detected when the ignition is turned off and when the ignition is turned on, the remaining battery capacity can be calculated based on the water temperature and the outside temperature.Therefore, it is not necessary to operate the device between the time when the ignition is turned off and the time when the ignition is turned on. Thus, power consumption can be reduced. Further, when the electrolyte concentration of the battery can be estimated to be stable, the remaining battery capacity with respect to the open circuit voltage measured at the time of ignition on is calculated, and when it can be estimated that the electrolyte concentration of the battery is not yet stable, Since the remaining battery charge at or immediately after the ignition is turned off is used, the remaining battery charge can be calculated with sufficient accuracy for practical use.
[0008]
The invention described in claim 2 is a temperature detecting means for detecting an engine cooling water temperature and an outside air temperature, a storage means for storing a cooling water temperature Twini and an outside air temperature TAoff detected when an ignition is turned off, and an open circuit voltage of the battery. Average external temperature calculating means for calculating an average external temperature TAave from a voltage measuring means for measuring, an external air temperature TA detected when the ignition is turned on after the ignition is turned off, and an external air temperature TAoff detected when the ignition is turned off (for example, ECU 6 in the embodiment), a calculating means for calculating a predicted water temperature Twx after a lapse of a predetermined time from the ignition OFF based on the average outside temperature TAave, a cooling water temperature Tw detected at the time of the ignition ON and the predicted water temperature Tw Compared with Twx, the cooling water temperature Tw is higher than the predicted water temperature Twx. If the cooling water temperature Tw is higher than the predicted water temperature Twx, the remaining battery charge at or immediately after the ignition is turned off is calculated if the cooling water temperature Tw is higher than the predicted water temperature Twx. It is characterized by using.
[0009]
According to the present invention, the cooling water temperature Twini and the outside air temperature TAoff detected at the time of the ignition off are stored in the storage means, and then the vehicle is stopped (ignition off). Then, when the ignition is turned on after the ignition is turned off, the outside air temperature TA and the outside air temperature TAoff are detected, and the average outside air temperature TAave is calculated from these by the average outside air temperature calculation means. By calculating the predicted coolant temperature Twx based on the average outside temperature TAave, it is possible to consider the change in the outside air temperature between the ignition off and the ignition on, and it is possible to improve the accuracy of the predicted coolant temperature Twx. Further, when the cooling water temperature Tw is lower than the predicted water temperature Twx, it can be estimated that the electrolyte concentration of the battery is sufficiently stable, so that the accuracy of the calculated remaining battery capacity can be improved.
[0010]
The invention described in claim 3 is characterized in that the battery is maintained in a no-load state for a predetermined time from when the ignition is turned on until when the engine is started.
According to the present invention, when the open-circuit voltage is measured by the voltage measuring unit when the ignition is turned on, by maintaining the battery in a no-load state, the open-circuit voltage can be measured in a state where the electrolyte concentration is stabilized, The accuracy of the calculated remaining capacity can be further improved.
[0011]
The invention described in claim 4 is characterized in that the predicted water temperature Twx is calculated by the following equation.
Twx = (Twini−TAave) × exp (−K × ΔT) + TAave
Here, ΔT is the predetermined time, K is a heat passage coefficient, and the heat quantity of the cooling water is Q, which is calculated by the following equation.
K = -ln ((Tw-TAave) / (Twini-TAave)). Times.Q / .DELTA.T According to the present invention, a highly accurate predicted water temperature Twx can be uniquely obtained. Properties can be further enhanced.
[0012]
The invention described in claim 5 is characterized in that the predicted water temperature Twx is read from a data table stored in advance.
According to the present invention, a highly accurate predicted water temperature Twx can be uniquely obtained, so that the reliability of the calculated remaining capacity can be further increased.
[0013]
The invention described in claim 6 is characterized in that the process when the battery is turned off is set to one of a charge process and a discharge process.
According to the present invention, since the relationship between the elapsed time from the time when the ignition is turned off and the remaining capacity can be uniquely determined, the control for estimating the remaining capacity can be simplified. That is, since the relationship between the elapsed time and the open circuit voltage differs depending on whether the battery process at the time of the ignition off is a charging process or a discharge process, when estimating the remaining capacity from the open circuit voltage, the battery at the time of the ignition off is used. It is necessary to switch the data of the open circuit voltage depending on whether the process is charging or discharging, but it is necessary to switch the data by setting the process at the time of ignition off to either the charging process or the discharging process as described above. The open circuit voltage can be uniquely determined from the elapsed time.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a control device for a vehicle battery according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a vehicle battery control device 1 according to an embodiment of the present invention. As shown in FIG. 1, a vehicle to which the control device 1 is applied uses an engine 2 and a motor 3 as drive sources, and supplies power from the drive sources to wheels (not shown) via an automatic transmission 4. This is a hybrid vehicle that can transmit power. In the present embodiment, the engine 2 and the motor 3 are directly connected, and are configured to rotate at the same rotational speed Ne.
[0015]
The motor 3 is connected to a lead battery 9 via a PDU (power drive unit) 8. The motor 3 has the functions of an electric motor and a generator. When the motor 3 operates as a motor, the motor 3 or the motor-assisted driving is possible. When the motor 3 operates as a generator, the battery 9 can be charged. For this purpose, the PDU 8 controls the transfer of electric power between the motor 3 and the battery 9. The battery 9 is connected to an SOC detection device 15 that detects the remaining capacity (SOC) of the battery 9. The SOC detection device 15 calculates, for example, the integrated charge amount and the integrated discharge amount by integrating the charge current and the discharge current of the battery every predetermined period, and calculates the integrated charge amount and the integrated discharge amount in the initial state or the charge / discharge start state. The current remaining capacity can be calculated by adding or subtracting to the immediately preceding remaining capacity. When the ignition switch 7 is turned on (IG-ON), the remaining capacity of the battery 9 is set at a predetermined interval. Detect every time. A current sensor 10 and a voltage sensor 11 are provided between the PDU 8 and the battery 9 to detect the current of the battery 9 and the voltage between terminals, respectively.
[0016]
A radiator 5 is connected to the engine 2 via a cooling water circulation passage, and cooling water circulates between the two 2 and 5 through the circulation passage. The circulation passage is provided with a water temperature sensor 12 for detecting the temperature of the cooling water.
[0017]
Further, the hybrid vehicle includes a control unit (ECU) 6. The control unit 6 is connected to the outside temperature sensor 13 for detecting the outside temperature of the vehicle and the ignition switch 7 in addition to the current sensor 10, the voltage sensor 11, the water temperature sensor 12, and the SOC detection device 15. 6 controls the various devices 2 to 5, 8, and 9 based on the input values from the sensors 10 to 13, the device 15, and the switch 7.
[0018]
The ECU 6 includes a memory 14 therein, and stores the water temperature and the outside temperature detected by the water temperature sensor 12 and the outside temperature sensor 13 and the remaining capacity detected by the remaining capacity detection device 15 in the memory 14 as described later. You. The memory 14 also includes a map (see FIG. 4) indicating the relationship between the open circuit voltage and the elapsed time in a data table including a plurality of data, a map indicating the relationship between the open circuit voltage and the remaining capacity in a data table including a plurality of data, A map and the like shown in a data table including a plurality of data relating to the average outside air temperature TAave of the predicted water temperature Twx, which is a threshold value described later, and the cooling water temperature Tw are stored.
[0019]
The operation of the vehicle battery control device 1 configured as described above will be described. First, when the ignition is turned on such as when the vehicle is running, the remaining capacity of the battery 9 is detected at predetermined intervals by the remaining capacity detection device 15, and the detected remaining capacity is stored in the memory 14 of the ECU 6.
When the ignition switch 7 stops when the vehicle stops, and when the ignition is turned off, the cooling water temperature Twini and the outside air temperature TAoff at this time are detected by the water temperature sensor 12 and the outside air temperature sensor 13, and the detected values Twini and TAoff are stored in the memory 14. And then the vehicle stops. At this time, each of the devices 2 to 15 constituting the vehicle battery control device 1 stops its operation.
[0020]
Then, when the ignition switch 7 is operated again, the remaining capacity of the battery 9 is calculated. This will be described with reference to FIG.
FIG. 2 is a flowchart showing the remaining capacity SOC calculation control. When the remaining capacity (SOC) calculation control based on the open circuit voltage (OCV) shown in step S10 in FIG. 4 is started, the ignition switch 7 is operated to turn on the ignition (IG-ON) in step S12. In step S14, the external temperature TAoff stored in the memory 14 when the ignition is turned off is read from the memory 14.
[0021]
Then, in step S16, the battery voltage Vocv at no load is measured by the voltage sensor 11. In the present embodiment, the battery 9 is maintained in a no-load state for a predetermined time from the time when the ignition is turned on until the time when the engine 2 is started. As a result, the open circuit voltage can be measured with the electrolyte concentration of the battery 9 being stabilized.
[0022]
In step S18, the outside air temperature TA and the water temperature Tw when the ignition is turned on (present) are measured by the outside air temperature sensor 13. Then, in step S20, the average outside air temperature TAave when left unattended (from the time when the ignition is turned off to the time when the ignition is turned on) is determined by the following equation.
[0023]
TAave = | (TA + TAoff) | / 2
[0024]
Then, in step S22, a threshold (predicted water temperature) Twx is searched on a map based on the average outside air temperature TAave and the water temperature Tw. FIG. 5 is a graph showing the relationship between the time elapsed since the ignition was turned off and the water temperature. As shown in the figure, since the cooling water temperature Twini at the time of the ignition off is heated by the engine 2, the cooling water temperature Twini is higher than the normal temperature (for example, about 80 degrees), and decreases as time passes. I will do it. Further, the degree of temperature decrease of the cooling water temperature differs depending on the outside air temperature. In the present embodiment, from the data table shown in FIG. 5, a predicted water temperature Twx after a lapse of a certain time after the ignition is turned off under the average outside temperature TAave is obtained. Here, as the certain time, it is preferable to set a time (for example, 4 hours) in which it can be determined that the electrolyte concentration of the battery 9 is stable. Thus, since the predicted water temperature Twx is read from the data table, a highly accurate predicted water temperature Twx can be uniquely obtained. Further, by calculating the predicted water temperature Twx based on the average outside air temperature TAave, a change in the outside air temperature between the ignition off and the ignition on can be considered, and the accuracy of the predicted water temperature Twx can be improved.
[0025]
Then, in step S24, it is determined whether or not the water temperature Tw is higher than the predicted water temperature Twx. If the determination result is Yes, the process proceeds to step S26, and if the determination result is No, the process proceeds to step S28. As described above, since the cooling water temperature Tw decreases in accordance with the elapsed time from the time when the ignition is turned off, when the cooling water temperature Tw is lower than the predicted water temperature Twx (when the determination result is No), It can be estimated that the ignition is turned on after a certain time has elapsed. In this case, since the electrolyte concentration of the battery 9 can be estimated to be stable, the remaining battery capacity with respect to the open circuit voltage measured by the voltage sensor 11 when the ignition is turned on is calculated as shown in step S28. On the other hand, when the cooling water temperature Tw is higher than the predicted water temperature Twx (when the determination result is Yes), it can be estimated that the ignition has been turned on before the predetermined time has elapsed. In this case, since it can be estimated that the electrolyte concentration of the battery 9 is not yet stable, the remaining battery capacity at or immediately after the ignition is turned off is used. Then, a series of processing ends.
[0026]
As described above, when the water temperature Tw and the outside air temperature TA are detected when the ignition is turned off and when the ignition is turned on, the remaining battery capacity can be calculated based on the detected water temperature Tw and the outside temperature TA. Power consumption can be suppressed. When it can be estimated that the electrolyte concentration of the battery 9 is stable, the remaining battery capacity with respect to the open circuit voltage measured when the ignition is turned on is calculated, and it can be estimated that the electrolyte concentration of the battery 9 is not yet stable. In this case, the remaining battery capacity at or immediately after the ignition is turned off is used, so that the remaining capacity of the battery 9 can be calculated with sufficient accuracy for practical use.
[0027]
FIG. 3 is another flowchart showing the remaining capacity calculation process by the vehicle battery control device shown in FIG. The same processes as those in FIG. 2 are denoted by the same reference numerals and description thereof will be omitted. First, after the ignition is turned on in step S12, the cooling water temperature Twini when the ignition is turned off is read from the memory 14 in addition to the outside air temperature TAoff when the ignition is turned off in step S13.
[0028]
Then, the predicted water temperature Twx is calculated by the following equation.
First, in step S30, a heat transfer coefficient K is calculated. The coefficient K is calculated by the following equation, where Q is the amount of heat of the cooling water and ΔT is a certain time.
[0029]
K = −ln (Tw−TAave) / (Twini−TAave) × Q / ΔT
[0030]
Then, using the heat transfer coefficient K, the predicted water temperature Twx is calculated by the following equation.
[0031]
Twx = (Twini−TAave) × exp (−K × ΔT) + TAave
[0032]
Even when the predicted water temperature Twx is calculated in this manner, a highly accurate predicted water temperature Twx can be uniquely obtained, so that the reliability of the calculated remaining capacity can be further increased.
[0033]
As described above, the control device for a vehicle battery according to the present invention has been described in the above-described embodiment, but the present invention is not limited to this content. For example, a lithium battery may be used instead of a lead battery. Further, in the embodiment, since the predicted water temperature Twx is obtained using the average outside air temperature TAave, the accuracy can be improved. However, the present invention is not limited to this, and the predicted water temperature may be obtained from the outside air temperature TA.
[0034]
Further, the process when the battery 9 is turned off may be set to one of a charging process and a discharging process. As shown in FIG. 4, the relationship between the elapsed time and the open circuit voltage differs depending on whether the process of the battery 9 at the time of the ignition off is a charging process or a discharging process. For this reason, when estimating the remaining capacity from the open circuit voltage, it is necessary to change the data of the open circuit voltage depending on whether the process of the battery 9 at the time of ignition off is charging or discharging. By setting any one of the discharge processes, it is not necessary to change the data, and the open circuit voltage can be uniquely determined from the elapsed time.
[0035]
【The invention's effect】
As described above, according to the first aspect of the present invention, it is possible to suppress the power consumption between the time when the ignition is turned off and the time when the ignition is turned on, and calculate the remaining capacity of the battery with sufficient accuracy for practical use. can do.
[0036]
According to the invention described in claim 2, the accuracy of the predicted water temperature Twx can be improved, and the reliability of the remaining battery capacity calculated when the cooling water temperature Tw is lower than the predicted water temperature Twx can be improved. .
According to the third aspect of the invention, the open circuit voltage can be measured with the electrolyte concentration of the battery stabilized, and the reliability of the calculated remaining capacity can be further improved.
[0037]
According to the invention described in claim 4 or claim 5, since the highly accurate predicted water temperature Twx can be uniquely obtained, the reliability of the calculated remaining capacity can be further increased.
According to the invention described in claim 6, since the relationship between the elapsed time from the time when the ignition is turned off and the remaining capacity can be uniquely determined, it is possible to simplify the control for estimating the remaining capacity.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a main configuration of a vehicle battery control device according to an embodiment of the present invention.
FIG. 2 is a flowchart illustrating a remaining capacity calculation process performed by the vehicle battery control device illustrated in FIG. 1;
FIG. 3 is another flowchart showing a remaining capacity calculation process by the vehicle battery control device shown in FIG. 1;
FIG. 4 is a graph showing a relationship between an elapsed time from an ignition off time and an open circuit voltage.
FIG. 5 is a graph showing the relationship between the elapsed time since the ignition was turned off and the water temperature.
[Explanation of symbols]
1 control device for vehicle battery 2 engine 6 control unit (ECU)
11 voltage sensor 12 water temperature sensor 13 outside temperature sensor 14 memory

Claims (6)

Temperature detection means for detecting an engine cooling water temperature and an outside air temperature;
Storage means for storing the cooling water temperature Twini and the outside air temperature TAoff detected when the ignition is turned off;
Voltage measuring means for measuring the open circuit voltage of the battery;
Calculating means for calculating, based on the outside air temperature TA detected when the ignition is turned on after the ignition is turned off, a predicted water temperature Twx after a lapse of a predetermined time since the ignition is turned off,
The cooling water temperature Tw detected at the time of turning on the ignition is compared with the predicted water temperature Twx. If the cooling water temperature Tw is lower than the predicted water temperature Twx, the remaining battery capacity with respect to the open circuit voltage measured at the time of turning on the ignition is calculated. The control device for a vehicle battery according to claim 1, wherein when the calculated cooling water temperature Tw is higher than the predicted cooling water temperature Twx, the remaining battery capacity at or immediately after the ignition is turned off is used. Temperature detection means for detecting an engine cooling water temperature and an outside air temperature;
Storage means for storing the cooling water temperature Twini and the outside air temperature TAoff detected when the ignition is turned off;
Voltage measuring means for measuring the open circuit voltage of the battery;
An average outside air temperature calculating means for calculating an average outside air temperature TAave from the outside air temperature TA detected when the ignition is turned on after the ignition is turned off and the outside air temperature TAoff detected when the ignition is turned off,
Calculating means for calculating, based on the average outside temperature TAave, a predicted water temperature Twx after a lapse of a predetermined time from the ignition off;
The cooling water temperature Tw detected at the time of turning on the ignition is compared with the predicted water temperature Twx. If the cooling water temperature Tw is lower than the predicted water temperature Twx, the remaining battery capacity with respect to the open circuit voltage measured at the time of turning on the ignition is calculated. The control device for a vehicle battery according to claim 1, wherein when the calculated cooling water temperature Tw is higher than the predicted cooling water temperature Twx, the remaining battery capacity at or immediately after the ignition is turned off is used. 3. The control device for a vehicle battery according to claim 1, wherein the battery is maintained in a no-load state for a predetermined time from when the ignition is turned on until the engine is started. The vehicle battery control device according to claim 2 or 3, wherein the predicted water temperature Twx is calculated by the following equation.
Twx = (Twini−TAave) × exp (−K × ΔT) + TAave
Here, ΔT is the predetermined time, K is a heat transfer coefficient, and the heat quantity of the cooling water is Q, which is calculated by the following equation.
K = −ln ((Tw−TAave) / (Twini−TAave)) × Q / ΔT The vehicle battery control device according to claim 2 or 3, wherein the predicted water temperature Twx is read from a data table stored in advance. The control device for a vehicle battery according to any one of claims 1 to 5, wherein a process when the battery is turned off is set to one of a charge process and a discharge process.

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