JPH1051966A - Automatic battery charger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of the parts used in an automatic battery charger and to more safely operate the charger, so as to reduce the cost of the charger, by controlling the charging current of the charger by controlling the AC current inputted to the primary input of the charger by transmitting the variation of the internal resistance of a battery to the gate of a triac. SOLUTION: When the internal resistance of a battery 9 increases, the impedance of a power transformer 7 also increases and the gate current of a triac 5 decreases, resulting in the turning off of the triac 5. The primary input current of an automatic battery charger is by-passed to a saturating reactor 6 and the voltage across the terminals V1 and V2 of the transformer 7 drops by the amount of the impedance of the reactor 6 and becomes 20V. When the primary input voltage of the transformer 7 drops by the amount of the impedance of the reactor 6 and becomes 20%, the DC voltage across the terminals V3 and V4 of the battery 9 also drops to 20% and becomes 2.8V (=14×0.2). When the final charging current is recalculated, the current becomes 0.08 A (=2.8/35), because the internal resistance of the battery 9 is 35Ω, and the overcharging of the battery 9 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery automatic charging apparatus for safely charging a battery such as a battery for an automobile and a mobile phone, a battery for an emergency power supply of a personal computer, and without damaging the battery. It is about.

[0002]

2. Description of the Related Art FIG. 1 shows a constant current / constant voltage charging method which has been widely used in the past, and is converted into a direct current by a power transformer 1 and a rectifier 2, and is converted into an electronic circuit section 3 formed by transistors, ICs, resistors and capacitors. It has a disadvantage that the number of parts is very large and the cost is high.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an inexpensive charging device which has a reduced number of parts, operates more safely, and has a reduced cost.

[0004]

Means for Solving the Problems A triac is used to determine the amount of change by utilizing the change in the internal resistance of the battery without using a constant current and a constant voltage, which is constituted by the secondary DC side electronic circuit forming unit 3 shown in FIG. And controls the charging current by controlling the AC input current of the primary input.

[0005]

When the battery 9 is fully charged, the battery 9
, The impedance of the power transformer 7 also increases, so that the gate current of the triac 5 decreases,
The triac 5 is in the OFF state between T and T2, and the charging current is controlled.

[0006]

FIG. 2 shows an embodiment of the present invention. If the internal resistance of the battery 9 at the time of discharging is 4 ohms and the terminal voltages of V3 and V4 are 14 volts, the charging current is E according to Ohm's law.
/ R = I becomes 14/4 = 3.5 amperes. If the internal resistance of the battery 9 becomes 35 ohms as the charging progresses, it becomes 14/35 = 0.4 amperes and the charging current decreases.

[0007] Even if the charging is continued in this state, the internal resistance of the battery 7 is saturated, and the internal resistance does not increase any more. It becomes overcharged.

However, the above state is a case where the gate current of the triac 5 is invariable and the triac 5 is kept on. In this embodiment, if the internal resistance of the battery 9 is increased, the impedance of the power transformer 7 is increased. Therefore, the gate current of the triac 5 also decreases, and the triac 5 is turned off.

When the triac 5 is turned off, the primary input current is bypassed to the saturation reactor 6, and V1 and V2
Is the impedance of the saturation reactor 6,
The voltage drops to 20 volts.

The primary input voltage drops due to the impedance of the saturation reactor 6, and when it reaches 20%, the DC voltage of V3 and V4 also becomes 20% and V3 and V3
The voltage of 4 becomes 14 × 0.2 = 2.8 volts.

Here, if the final charging current is recalculated, the internal resistance of the battery 9 is 35 ohms.
= 0.08 amperes, and overcharge can be prevented.

[0012]

According to the conventional charging method, at least I
C, one or more, several transistors, a semiconductor, a resistor, a capacitor, and a composite part, composed of several tens of points. The cost will be low and the performance and durability will be excellent.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an embodiment according to a conventional product.

FIG. 2 is a circuit diagram of an embodiment according to the basics of the present invention.

FIG. 3 is a circuit diagram of an embodiment according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power transformer 2 Rectifier 3 Electronic circuit constituent part 4 Battery 5 Triac 6 Saturation reactor 7 Power transformer 8 Rectifier 9 Battery

Claims (2)

[Claims] 1. A power transformer is connected in series to a circuit in which a saturation reactor in which a magnetic flux is saturated and a triac are connected in parallel, and a gate current of the triac is controlled by a change resistance of an impedance of the power transformer. A charging device that controls the charging current by controlling the charging current. 2. A secondary coil is set in a saturation reactor in which a magnetic flux is saturated, and the secondary coil is connected to a triac T1.
And a device connected between the gate and the gate (G) to generate a reverse current of the gate current of the triac when the voltage is distributed to the main coil of the saturation reactor, thereby turning off the triac.