JP2010031740A - Battery managing device - Google Patents

Abstract

An object of the present invention is to accurately calculate the internal resistance of a battery and improve the determination accuracy of the deterioration state of the battery.
A battery management device that calculates an internal resistance value of a battery based on voltage and current when starting the engine and determines a deterioration state of the battery based on the internal resistance value. The calculation of the internal resistance value of the battery 4 based on the voltage and current of the battery 4 at the start within the time is restricted.
[Selection] Figure 1

Description

  The present invention relates to a battery management device, and more particularly to a technique for determining a deterioration state of a battery in an idle stop vehicle.

An idle stop vehicle has been developed that automatically stops the engine when driving is stopped to improve fuel efficiency. In such an idle stop vehicle, the engine may be stopped and started frequently, and when the battery is deteriorated and the capacity is reduced, the battery may not be charged in time and the start may be difficult. is there.
In view of this, a technology has been developed that estimates the deterioration state of the battery based on the travel distance of the vehicle and regulates the idle stop control when the battery is in the deterioration state (Patent Document 1).
JP 2007-56745 A

However, in the method of determining the deterioration state of the battery according to the travel distance, the variation is large due to the difference in the traveling state or the like, and it is difficult to accurately determine the deterioration state of the battery.
As another method for determining the deterioration state of the battery, there is a method based on the internal resistance of the battery. In this determination method, the internal resistance of the battery is calculated based on the voltage and current during cranking.

However, even with such a determination method based on internal resistance, variations occur in the calculation of internal resistance. In particular, when the engine is stopped and started frequently as in an idling stop vehicle, the variation becomes large. Therefore, there is a possibility that the deterioration state of the battery cannot be accurately determined without sufficiently ensuring the calculation accuracy of the internal resistance. .
The present invention has been invented in view of such a problem, and an object of the present invention is to provide a battery management apparatus capable of improving the calculation accuracy of the internal resistance of a battery and accurately determining a deterioration state in an idle stop vehicle. And

  In order to achieve the above object, an invention according to claim 1 is provided in an idle stop vehicle that stops an engine when a predetermined stop condition is satisfied and starts the engine when a predetermined start condition is satisfied, and starts the engine. Sometimes, internal resistance calculation means for calculating the internal resistance of the battery based on the voltage and current of the battery of the vehicle, and determination means for determining the deterioration state of the battery based on the internal resistance of the battery calculated by the internal resistance calculation means And a calculation restricting means for restricting the calculation of the internal resistance of the battery by the internal resistance calculating means at the start within a predetermined time from the stop of the engine.

  Further, the invention of claim 2 further comprises stop restriction means for restricting engine stoppage when the stop condition is satisfied when the determination means determines that the battery is in a deteriorated state. It is characterized by.

  According to the battery management device of the first aspect of the present invention, since the calculation of the internal resistance of the battery based on the voltage and output current of the battery at the time of starting within a predetermined time from the engine stop is restricted, the battery after the engine stops The calculation error of the internal resistance due to the influence of the polarization can be eliminated. Therefore, the calculation accuracy of the internal resistance of the battery can be improved, and the deterioration state of the battery can be accurately determined.

  According to the battery management device of claim 2 of the present invention, when the determination unit determines that the battery is in the deteriorated state, the engine stop is regulated even when the stop condition is satisfied in the idle stop vehicle. Thus, it is possible to avoid inability to start the engine in an idle stop vehicle due to battery deterioration.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a starter for an idle stop vehicle according to the present invention.
The battery management device of this embodiment is mounted on a vehicle with an idle stop control function (hereinafter referred to as an idle stop vehicle). As shown in FIG. 1, the idle stop vehicle includes an engine 1, an alternator 2, a starter motor 3, and a battery 4. The alternator 2 is driven by the engine 1 to generate electric power, supplies electric power to an electric device such as a headlamp (not shown), and supplies electric power to the battery 4 to charge it. The starter motor 3 is driven by power supplied from the battery 4 and starts the engine 1. Further, the starter motor 3 has a function as a generator during engine operation, and supplies power to other electrical devices and the battery 4.

  The vehicle control unit 5 that performs overall control of the engine 1 is provided with an idle stop control unit. The idle stop control unit controls the fuel injection valve of the engine 1 when a predetermined stop condition, for example, an ignition switch, an idle switch, and a brake switch are on, the vehicle speed is equal to or lower than a predetermined vehicle speed, and the engine speed is equal to or lower than a predetermined speed. The fuel injection is stopped and the engine operation is stopped. Further, the idle stop control unit operates the starter motor 3 after the engine operation is stopped when the idle switch is turned off by depressing an accelerator pedal or the brake switch is turned off by releasing the brake operation after the engine operation is stopped. The engine 1 is restarted.

A voltage sensor 10 that measures the voltage of the battery 4 is provided between the terminals of the battery 4. A current sensor 11 that detects an input / output current of the battery 4 is provided on a line connecting the alternator 2 and the terminal of the battery 4. The battery 4 is provided with a temperature sensor 12 that detects the temperature of the battery 4.
The idle stop vehicle according to the present embodiment is provided with a battery management unit 20 that determines a deterioration state of the battery 4. The battery management unit 20 includes an input / output device, a storage device (ROM, RAM, nonvolatile RAM, etc.), a central processing unit (CPU), and a timer. The battery management unit 20 includes a voltage sensor 10, a current sensor 11, and a temperature sensor 12. Enter detection information.

  Further, the battery management unit 20 is connected to the vehicle control unit 21 so as to be able to transmit information by CAN communication, and inputs information such as an ignition switch signal of the vehicle. Then, the internal resistance of the battery 4 is calculated (internal resistance calculating means), and it is determined that the battery is in a deteriorated state when the internal resistance is equal to or greater than a predetermined value (deterioration determining means). Further, when the battery management unit 20 determines that the battery is in a deteriorated state, the battery management unit 20 outputs a restriction signal to the idle stop control unit so as not to stop the engine 1 even if the stop condition is satisfied (stop restriction means). ).

Hereinafter, the calculation procedure of the internal resistance of the battery 4 in the battery management unit 20 will be described.
The battery management unit 20 inputs the voltage V of the battery 4 from the voltage sensor 10 and the current I from the current sensor 11 when the engine 1 is started, specifically, during cranking, and calculates R = V / I. The internal resistance value R of the battery 4 is obtained. The measurement of the voltage V and the current I is performed a plurality of times, and the internal resistance is determined from the plurality of data by the least square method. Further, the determined internal resistance is corrected based on the temperature of the battery 4 input by the temperature sensor 12 and used as an internal resistance for determining the deterioration state.

  In the present embodiment, the time (idle stop time Ts) from when the engine 1 is stopped to when it is restarted by idle stop control is measured, and when the idle stop time Ts is less than the predetermined time T1, the internal resistance value R Is restricted (calculation restricting means). That is, the calculation of the internal resistance value R is performed based on the voltage V and current I of the battery 4 during cranking only when the idle stop time Ts is equal to or longer than the predetermined time T1. As will be described later, the predetermined time T1 is set to a time when the influence of polarization is eliminated with respect to the voltage V of the battery 1 when the engine is stopped.

  FIG. 2 is a graph showing the relationship between the idle stop time Ts and the internal resistance value R. FIG. 3 is a graph showing the relationship between the voltage V and current I of the battery 4 at the time of starting. As shown in FIG. 2, the internal resistance value R varies greatly when the idle stop time Ts is less than the predetermined time T1, while the variation in the internal resistance value R decreases when the idle stop time Ts is equal to or longer than the predetermined time T1. Further, when the idle stop time Ts is less than the predetermined time T1, the internal resistance value R tends to be low. Therefore, as shown in FIG. 3, the internal resistance obtained by the least square method is also smaller when the idle stop time Ts is less than the predetermined time T1 than when the idle stop time Ts is longer than the predetermined time T1 (the inclination is smaller in the figure).

Hereinafter, the relationship between the idle stop time Ts and the internal resistance value R will be described in detail with reference to FIG. FIG. 4 is a time chart showing the transition of the voltage V of the battery 4 after the engine is stopped.
As shown in FIG. 4, since the power generation by the alternator 2 is stopped immediately after the engine is stopped, the voltage V drops instantaneously (a → b). After that, the voltage V decreases due to the influence of polarization (b → c), but after the predetermined time T1, the influence of the polarization is eliminated and the voltage drop becomes moderate and becomes substantially stable (after c). Therefore, if the internal resistance value R is calculated by starting before the predetermined time T1 during which the influence of polarization remains, the calculated value of the internal resistance value R varies greatly because of the large variation in the voltage V at the time of starting. Further, since the current I increases so as to eliminate the polarization from the engine stop until the predetermined time T1 elapses, the calculated value of the internal resistance value R decreases. Note that the power consumed to eliminate the polarization is larger than the power required at the start, so the voltage difference due to the polarization cannot be absorbed at the start, and the variation in the voltage V affects the calculation of the internal resistance value R. End up.

FIG. 5 is a graph showing the internal resistance value R and its frequency. FIG. 5A shows this embodiment, and FIG. 5B shows a conventional example in which the internal resistance value R is calculated regardless of the idle stop time Ts.
In the present embodiment, when the idle stop time Ts is shorter than the predetermined time T1, the internal resistance value R is not calculated. Therefore, as shown in FIG. Compared to the conventional example shown in (B), the overall variation is reduced.

  Thus, since the variation of the internal resistance value R is reduced and the calculation accuracy is improved, the deterioration state of the battery 4 can be accurately determined. In addition, by restricting the engine stop by the idle stop control when the battery is deteriorated, it is possible to avoid the inability to start due to the deterioration of the battery at the time of the idle stop control.

It is a schematic block diagram of the starting device of an idle stop vehicle. It is a graph which shows the relationship between idle stop time and internal resistance value. It is a graph which shows the relationship between the voltage and current of the battery at the time of starting. It is a time chart which shows transition of the voltage of the battery after an engine stop. It is a graph which shows an internal resistance value and its frequency, (A) is this embodiment, (B) shows a prior art example.

Explanation of symbols

1 Engine 2 Alternator 3 Starter Motor 4 Battery 5 Vehicle Control Unit 20 Battery Management Unit

Claims (2)

The engine is stopped when a predetermined stop condition is satisfied, and is provided in an idle stop vehicle that starts the engine when a predetermined start condition is satisfied,
Internal resistance calculating means for calculating the internal resistance of the battery based on the voltage and current of the battery of the vehicle at the time of starting the engine;
Determining means for determining a deterioration state of the battery based on the internal resistance of the battery calculated by the internal resistance calculating means;
Calculation restriction means for restricting calculation of the internal resistance of the battery by the internal resistance calculation means at the start within a predetermined time from the stop of the engine;
A battery management device comprising:   The stop restriction means for restricting stop of the engine when the stop condition is satisfied when the determination means determines that the battery is in a deteriorated state. Battery management device.

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