JPS5917827A - Charger for battery - 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 (A) Technical Field The present invention relates to a battery charging device that includes a detection control circuit that detects a predetermined state of charge of a battery to be charged and controls charging of the battery. This type of device is widely praised because it can rapidly charge a battery to be charged with a large charging current.

(B) Background Art Among the batteries to be charged, some are internally short-circuited for some reason, and when such a short-circuited battery is charged, a short-circuited large current flows through the charging circuit, which may cause the charging device to burn out. There is. For this reason, it is desirable to provide a detection circuit in the detection control circuit that detects an internal short-circuit state of the battery to be charged and stops charging the battery.

On the other hand, some of the batteries to be charged are in an overdischarged state (hereinafter referred to as overdischarged batteries). Here, the overdischarge state refers to a state in which the remaining electricity of the battery is completely discharged to the load and the battery voltage at the time of load is zero. Charged battery or nickel
In the case of a cadmium battery, the anode is made of nickel oxide, the cathode is made of a cadmium compound, and the electrolyte is made of caustic potassium. The reaction during discharge is N at the anode.
100H-1-H2O-1-e −+N i ((
If the overdischarge state is short, the chemical reaction with 2 + OH will proceed only on the anode surface, and Ni0O]11 will remain in the deep part of the anode, and this Ni00H
becomes the nucleus for the next charging, and a charging chemical reaction occurs immediately.

However, when the overdischarge condition becomes long, the Ni00H to N
The change to 1(OH)z goes deep, and the amount of Ni00H that should form the core during charging decreases, making the battery inactive.

In addition, in the case of forced discharge, for example, when two batteries with different residual amounts of electricity are connected in series and discharged, one battery with a small remaining amount of electricity becomes zero, and then the other battery's remaining amount of electricity becomes zero. It is charged in the opposite direction with the discharge current. In one of the batteries, after the remaining amount of electricity becomes zero, gas is generated due to redundant decomposition of water, and N1(0,Ei
) The reaction to 2 does not proceed deep into the anode. Therefore, a battery in a reverse charging state (hereinafter referred to as a reverse charging battery) is not inactivated.

The above-mentioned over-discharged batteries and reverse-charged batteries recover their voltage when placed under no load, just like normal batteries, but over-discharged batteries have a voltage below the normal battery voltage, and reverse-charged batteries have a negative voltage. . If charging current is supplied to these over-discharged batteries and reverse-charged batteries, the voltage will recover and return to normal.Therefore, a detection circuit that detects the internal short-circuit state of the battery will be installed.
If the operation is started immediately after charging starts, the voltage of over-discharged batteries or reverse-charged batteries at the start of charging is low, so these batteries cannot be charged in the same way as short-circuited batteries.

Conventional devices detect battery voltage, delay the detected voltage, and compare whether or not the delayed detection voltage is greater than a reference voltage using a comparator, such as an operational amplifier, as a means of detecting an internal short-circuit state of a battery. It is something. However, in this conventional device, the battery voltage is detected to detect an internal short circuit in the battery, and the detected voltage is delayed using a delay circuit such as an integrating circuit. Since this battery direct pressure detection is affected by the delay circuit described in 13iJ, even if a fully charged battery is mistakenly charged, a predetermined state of charge can only be detected after a delay time, which is an inconvenience.

The structure of the comparator is still complicated and the cost is high.

(C) Disclosure of the Invention The present invention was invented in view of the above points, and the internal short-circuit state of the battery is detected by the magnitude of the charging current, and the output of this detection means is delayed by a delay circuit. It is something.

That is, the present invention provides a device that includes a detection circuit that detects a predetermined state of charge of a battery to be charged and a control circuit that controls charging of the battery based on the detection output of the circuit, the device including a charging current in a charging path of the battery. A detection means for detecting an overcurrent condition is provided, and a delay circuit is provided between an output terminal of the means and a control circuit.

Therefore, unlike conventional devices, the battery voltage is not detected to detect an internal short-circuit state of the battery, and there is no need to provide a delay circuit related to the detection of battery voltage. When detecting voltage, there is no relationship between this battery voltage and the delay circuit.
Stable battery voltage detection can be performed. Over-discharged batteries and reverse-charged batteries return to their normal states during the delay time of the delay circuit, so they are normally charged, and for internally short-circuited batteries, a short-circuit current flows even after the delay time has elapsed, so Ir1J A control circuit is activated by the output of the detection means to control charging. Therefore, an excessive short-circuit current does not continue to flow, and damage to the charging device can be prevented.

B) Embodiment An embodiment of the present invention will be described with reference to FIG. 1, which is a circuit diagram of an electric lamp of an apparatus according to the present invention. In this drawing, (P
I) (P2) is a DC power supply terminal, and the positive and negative fins (I,
+ ) (L2) respectively. Both lines are connected to a pair of charging terminals (P3) via a relay switch (R8).
P4). A voltage (■0) is taken out from the positive line (L) via the diode (Dl), and this voltage is applied to various circuits described later.
A control circuit (1) consisting of a relay coil (Ity) and a first transistor (Ql) is connected to L2).
A start switch (SS) is inserted between the transistor (Ql > and the positive line (Ll) via a capacitor (CI) having a discharge resistance (几3). The switch is an automatic reset type push button switch. However, until the capacitor (C1) is charged when the capacitor (C1) is closed, a current flows through the first transistor CQ1) and the transistor becomes conductive.
L, the relay switch (R8) is closed by the excitation of the relay coil (RY), and the battery to be charged (B) is charged. As the charging current flows to the negative line (L2), the voltage across the current reducing resistor (R2) causes the second transistor (C
2) becomes conductive and the charging indicator light (LE) lights up to indicate that charging is in progress. Further, the sixth transistor (C3) becomes conductive due to the voltage across the current reducing resistor (R2), and its collector voltage decreases. Therefore, the base voltage of the fourth transistor (C4) whose collector and emitter are connected between the base and emitter of the first transistor (Ql) decreases, and the fourth transistor is cut off.

(2) is a detection circuit that detects a predetermined state of charge of the battery to be charged (B), and includes a memory circuit (3), a first and second comparison circuit (C
01) (CO2) and a voltage dividing circuit (4).

The storage circuit (3) stores a voltage corresponding to the peak point voltage of the charging voltage characteristic of the battery (B), and is constituted by an electrochemical potential storage element (M).

The element is connected to a first voltage dividing circuit (5) to which a voltage (■0) is applied.
) is applied via the first analog switch (ASl) and the resistor (R4). The first analog switch (ASI) is closed to the high level output of the first comparator circuit (C01), and this high level output indicates that the ai partial pressure (■2) of the battery voltage is the storage voltage (2) of the storage circuit (3). ■3)
It is given when it is big. This first partial voltage (v2) is obtained from a voltage dividing circuit (4) that is connected between a pair of charging terminals (Pa) (P4), and the voltage dividing circuit is connected to a resistor (R5).
~ (R9), a potentiometer (PM), and a first constant voltage element (Zl). .

The second partial voltage (■4) obtained from the voltage dividing circuit (4) is
The voltage is υ higher than the partial voltage (■2), and this second partial voltage is the storage voltage (■3) of the storage circuit (3) and the second comparison circuit (CO2).
The comparison output (6) is applied to the base of the first transistor (Ql). Second comparison circuit (00
2) essentially detects the predetermined state of charge of the battery (B).

(6) is the overcurrent detection means, iE negative line (Ll)
(L2) and a resistor (approximately 10) between the fifth transistor (C
5) is inserted, and a series circuit of a resistor (Rh) and a second constant voltage element (z2) is inserted between the positive fin (Ll) and the negative DC power supply terminal (P2), and the element The reference voltage of
It is connected to the base of the That is, this detection means (6
), when the charging current flowing to the negative line (L2) is an overcurrent and the voltage across the current reducing resistor (R2) is higher than the reference voltage of the second constant voltage element (z2), the fifth transistor (C5 ) is cut off, and its collector voltage becomes high level. This high level output is applied to the base of the fourth transistor (C4) via a delay circuit (7) consisting of a resistor (R13) and a capacitor (C2).
) becomes conductive, the first transistor (Ql) is cut off, and the relay switch (R
8) is opened and charging current no longer flows.

In the above configuration, a normal battery (B) is connected to a charging terminal (P
a) (P4) and temporarily closes the start switch (S8), the first transistor (Ql) becomes conductive, the relay switch (R8) closes, and the charging WW flow starts. flows. The voltage across the current reducing resistor (R2) due to the charging current turns on the third transistor (C3) and opens the second analog switch (AS2). As a result, the discharge circuit of the memory circuit (3) is opened. In addition, since the second partial voltage (■4) is larger than the storage voltage (V3) of the storage circuit (3), the output of the second comparison circuit (002) is at a high level, and the first transistor (Ql) is in a conductive state. to hold. The battery (B) is thus rapidly charged, and its charging voltage characteristic is shown by (V8) in FIG. 2, which has a peak point (b) and then decreases. In this 'decreasing region, the charge M and quantity characteristics (Q) of the battery (B) become fully charged.

When the battery voltage increases according to the characteristic (v, 1),
The first divided voltage (■2) of the voltage dividing circuit (4) is the storage voltage (V3)
The first comparison circuit (c.

When the output (■6) of 1) is at a high level, the first analog switch (ASI) is substantially closed, and the storage voltage (■3) follows the first partial voltage (V2), By equalizing the first partial pressure, the first analog switch (As 1
) becomes open. Thus, the memory voltage (■3) is at the time (tl) of the peak point (b) of the charging voltage characteristic (V''61.)
However, after time (tl), the battery voltage drops below the peak point voltage, so the output of the first comparator circuit (C0l) becomes low level (vK), so the first analog The switch (ASI) is held open. After time (tl), the second partial pressure (■4
) decreases and becomes equal to the storage voltage (V3) corresponding to the battery voltage at the peak point (b) (t2), the second
The output (5) of the comparator circuit (CO2) is switched to low level, the first transistor (Ql) is cut off, the relay switch (R8) is opened, and battery charging is completed. In this case, the period between time (tl) and (t2) is the voltage dividing circuit (
4) The difference voltage between the first partial pressure (■2) and the second partial pressure (■4) (
■Determined by 4-V2).

Therefore, when the internally shorted battery is connected between the charging terminals (P3) and (P4), an excessive charging current flows through the current reducing resistor (R2), so the fifth transistor (C5) shuts off.
Its collector voltage increases. This state is the delay circuit (7
) continues, so after the delay time, the fourth transistor (C4) becomes conductive and the first transistor (Ql) is cut off, stopping charging.

On the other hand, when charging an over-discharged battery or a reverse-charged battery, an excessive charging current flows at the start of charging, but returns to normal charging current within the delay time of the delay circuit (7). C4 does not become conductive and can be charged like a normal battery.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram showing an embodiment of the device according to the present invention, and FIG. 2 is a charging characteristic diagram. (B)...Battery to be charged, (2)...Detection circuit, (1)...Control circuit, (L2)...
... Charging path (negative line), (6) ... Detection means, (7) ... Delay circuit.

Claims (1)

[Claims] (1) A device equipped with a detection circuit that detects a predetermined state of charge of a battery to be charged and a control circuit that controls charging of the battery based on the detection output of the circuit, the device including an overcurrent of charging current in the battery charging path. A battery charging device comprising: a detection means for detecting a state; and a delay circuit between an output terminal of the means and a control circuit.