JPS63157621A - Battery charging method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a battery charging method for charging a secondary battery (hereinafter referred to as a battery) by applying a charging voltage.

BACKGROUND ART In conventional battery charging methods, a charging voltage is applied to the battery, a rise in battery terminal voltage is monitored, and charging is stopped when the battery terminal voltage reaches a desired voltage near the so-called rated voltage. It was being done.

However, in a vehicle battery installed in a vehicle such as a motorcycle or a passenger car, the ambient temperature fluctuates greatly. However, as is clear from Figure 1(a),
The battery terminal voltage during charging varies greatly depending on not only the charging time but also the temperature. Therefore, when charging a battery used in a situation where the ambient temperature fluctuates rapidly, there is a problem in that appropriate charge management cannot be achieved using the above-described conventional charging method.

In addition, as shown in Figure 1 (a), there is a method (delta peak method) that focuses on the fact that the maximum voltage appears before overcharging and detects a terminal voltage drop of several millivolts from the maximum voltage to stop charging. However, as shown in Figure 1 (b), the terminal voltage changes with fluctuations in the charging current, so a stable constant current source is required, and for this purpose it is necessary to measure the terminal voltage. A large-scale system including In the case of a vehicle-mounted battery, the power source is a generator such as an alternator driven by the vehicle-mounted engine, and the power source fluctuates rapidly, making it impossible to use the delta-peak method.

SUMMARY OF THE INVENTION Therefore, in view of the above-mentioned points, it is an object of the present invention to provide a battery charging method that can appropriately charge a battery even under conditions where there are large fluctuations in the ambient temperature and the power source that supplies the charging current. .

In the battery charging method according to the present invention, the application of the charging voltage to the battery is temporarily stopped to cause the battery to discharge at a constant current, and the application of the charging voltage is continued until the battery terminal voltage reaches the desired voltage. do.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIG. 2 and the subsequent drawings.

FIG. 2 shows a specific circuit example of a charging device using the battery charging method according to the first invention of the present application. In the charging device, for example, the output of an alternating current generator (hereinafter referred to as ACG) 1 driven by an on-vehicle engine (not shown) is converted into direct current by a rectifier circuit (not shown) in a rectifier controller 2. and is supplied to an electrical load 3 such as a headlamp. Further, the DC output is also supplied to the battery 5 via a switch 4 made of an electronic switch or the like. The switch 4 is a changeover switch that can temporarily connect only the discharge constant current source 6 to the terminal of the battery 5. The switching operation of the switch 4 is controlled by a controller 7. The controller 7 controls the switching operation of the switch 4, detects the terminal voltage vB of the battery 5, and receives a temperature signal ST from a battery temperature detector 8 consisting of a thermistor or the like provided near the battery 4.
receive. The controller 7 further controls the rectification control unit 2 according to the detected terminal voltage VB and the received temperature signal ST.
Gate current 1. Determine whether to supply or not. Note that a resistor may be used as the discharge current source 6 in order to simplify the structure.

Next, the operation of the controller 7 will be explained with reference to the flowchart shown in FIG. 3.The controller 7 temporarily switches the switch 4 at a rate of, for example, once per second in response to a start signal (step 21). Due to this switching, the terminal of the battery 5 is connected only to the discharge constant current source 6 for, for example, about 10 m5ec, and the battery 5 performs constant current discharge. Next, the controller 7 detects the terminal voltage Ve of the battery 5 during the constant current discharge and takes in a temperature signal ST corresponding to the temperature of the battery 5 from the battery temperature detector 8 (step 22). The controller 7 receives a temperature signal ST
The target terminal voltage VT is read out from the memory and set according to the temperature signal ST taken in. . Next, step 24) eliminates the size discrimination between the terminal voltage VB and the target terminal voltage VT.
If the terminal voltage VB is equal to or higher than the target terminal voltage vT, the gate current G is supplied to the thyristor 9, the supply is maintained, and the supply of charging current to the battery is stopped (step 25). Conversely, if the terminal voltage Vs has not reached the target terminal voltage VT, the supply of the gate current IG is stopped and a charging current is supplied to the battery (step 26).

This operation is repeated from step 21 at predetermined time intervals.

As the target terminal voltage vT of the target value map stored in the memory (not shown), the low temperature side maximum value VLMAX (4th
It is preferable to use a value slightly lower than the value shown in the figure, because the control operation of the controller 7 prevents overcharging of the battery within the normal temperature range and allows a nearly fully charged state to be achieved. In addition, as shown in FIG. 2, a load state detector 10 is provided to detect the load state of the battery 5, and when the load of the battery 5 is large, the control operation of the controller 7 is changed to transfer the output of the ACGI to the load 3. It is also possible to supply it to the battery 5. As is clear from Fig. 4, the terminal voltage of the battery during constant current discharge is not affected much by temperature, so the target terminal voltage VT according to the target value map
Practically sufficient charge management can be achieved even if temperature correction is abolished, which is advantageous for cost reduction and system simplification. Furthermore, the fact that the controller 7 is computer controlled means that
÷Since the charging management control can be performed even under Luna Task, it is also possible to have a computer incorporated in another functional component control it, which is a great cost advantage.

FIG. 5 shows a specific circuit example of a charging device using the battery charging method according to the second invention of the present application. In such a charging device, the switch 4 of the charging device shown in FIG. 2 is a changeover switch that can temporarily connect only the discharge constant current source 6 to the terminal of the battery 5, whereas the switch 14 This is a changeover switch that can temporarily disconnect the ACQI from the terminal of the ACQI terminal and connect the discharge variable current source 16 in its place. Further, the variable discharge power source 16 is controlled by the controller 7 to keep the discharge current of the battery 5 constant. The controller 7 performs feedback control on the discharge variable current source 16 in response to a signal SL from a current detector 20 that detects the discharge current of the battery 5 and generates a signal SL corresponding thereto. In this way, the discharge current of the battery 5 is kept constant, the terminal voltage VB of the battery 5 at that time is detected, and charging is managed according to the terminal voltage V8.

Since the configuration other than the above-mentioned configuration is the same as that of the charging device shown in FIG. 2, the explanation thereof will be omitted.

Regarding the operation of the controller 7, after the operation in step 21 of the flowchart shown in FIG.
6 may be feedback-controlled to maintain the discharge current from the battery 5 at a predetermined value. Moreover, if the operation of the controller 7 is stopped when the battery 5 is discharging an excessive current, the output of the ACGl can be supplied to the load 3, and the load on the battery 5 can be reduced.

As described in detail, in the battery charging method according to the present invention, the discharge current of the battery is temporarily kept constant, and during that time, as shown in FIG. is measured, and application of charging voltage to the battery is controlled according to the terminal voltage. Therefore, variations in the amount of charge due to temperature can be reduced, and the battery can be charged with high precision and efficiency. Therefore, overcharging or undercharging is prevented, thereby preventing negative effects on battery life.

[Brief explanation of the drawing]

Fig. 1(a) shows the standard charging characteristics of a battery when constant current charging is performed, Fig. 1(b) shows the relationship between charging current and terminal voltage, and Fig. 2 is according to the first invention of the present application. A specific circuit example of a charging device using the battery charging method is shown, and FIG. 3 shows a flowchart following the operation of the charging device shown in FIG. 2, and FIG. 4 shows a battery when constant current discharge is performed. FIG. 5 shows a charging device using the battery charging method according to the second invention of the present application. Explanation of symbols of main parts 1... ACG 2... Rectification control section 3... Electrical load 4...
Switch 5...Battery 6...
・Discharge constant current source 7... Controller 14...
...Switch 16...Discharge variable current source 20...Current detector

Claims (2)

[Claims] (1) A battery charging method in which the battery is charged by applying a charging voltage, in which only a discharge constant current source is temporarily connected to the terminals of the battery, and the terminal voltage of the battery at this time is detected. A battery charging method comprising controlling application of the charging voltage to the battery according to a terminal voltage. (2) A battery charging method in which the battery is charged by applying a charging voltage, and if necessary, the application of the charging voltage is temporarily stopped and a variable discharge current source is connected to the battery, and at this time, the variable discharge current source is connected to the battery. The method is characterized in that a terminal voltage of the battery is detected while a discharge current from the battery is kept constant by controlling a current source, and application of the charging voltage to the battery is controlled according to the detected terminal voltage. Battery charging method.