JPS6237023A - Charge controlling circuit - 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 (Field of Industrial Application) The present invention relates to a charging control circuit suitable for charging a 2-N-cadmium storage battery or the like more safely and in a shorter time.

(Prior art) Conventionally, as described in Yuasa Battery Technical Data A 10 (B) page 13, as a charge control circuit for nickel-cadmium storage batteries, etc., a large current is applied to the battery at the initial stage of charging, and a large current is applied to the battery at the end of charging. For example, in the initial stage of charging, the charging method switches to a safe minute current. For example, the charging method quickly charges at 0.3 CmA at the beginning of charging, detects when the charging voltage of the battery reaches a predetermined voltage value or a predetermined temperature, and then switches to a trickle charging current ( α02～0
．． A charging control circuit that switches to 0.05 CmA or less (sometimes simply written as C) is known.

(Problem to be solved by the invention) However, if the voltage detection and switching circuit fails, 0.5 CmA rapid charging continues, causing overcharging and increasing battery temperature due to gas consumption. had the disadvantage of damaging the storage battery due to thermal runaway. Also,
In order to continue charging by switching from quick charging to trickle charging and fully charging the battery, trickle charging takes a long time, which has the disadvantage of increasing the overall charging time.

The purpose of the present invention is to prevent thermal runaway and shortened battery life due to overcharging, prevent damage to storage batteries and prolong their life, and perform supplementary charging to obtain usable discharge capacity for a short period of time. An object of the present invention is to provide a charging control circuit that brings a storage battery into a fully charged state.

(Means for Solving the Problems) A feature of the present invention to achieve the above object is that in a charging control circuit for charging a storage battery, it is detected that the voltage or temperature of the storage battery (1) exceeds a predetermined value. Detection circuit (2, 3
, 4, 5), a timer (7) which outputs an output after the activation setting time has elapsed based on the output of the circuit, and a storage battery (1) which is switched by a switch controlled by the timer and a switch controlled by the detection circuit. ) and a power supply, and under the control of each of the switches, rapid charging is performed with the first large current until the voltage of the storage battery reaches a predetermined value, and then the Supplementary charging is performed using a second current smaller than the first current until the timer generates an output, and then a third current smaller than the second current is used for supplementary charging.
The charge control circuit performs trickle charging with a current of .

(effect) According to the present invention, the charging current is switched in three stages.

When the voltage of the storage battery is lower than a predetermined value, rapid charging is performed using the first large current.

When the voltage of the storage battery reaches a predetermined value, supplementary charging is performed for a predetermined time using a second current smaller than the first current,
Thereafter, trickle charging is performed using a sixth current that is still smaller.

By the above-mentioned current switching and time monitoring, charging can be performed in a short time without causing battery deterioration.

(Example) FIG. 1 shows the first charging control circuit with battery protection circuit of the present invention.
It is a block diagram showing an example of.

1 is a nickel-cadmium storage battery (hereinafter referred to as a nickel-cadmium battery) that can be charged and discharged at a nominal voltage of 1.2 . 2 is stable against changes in temperature and input voltage, with a constant voltage V
This is a voltage generator that generates s.

3 uses a varistor, semiconductor temperature sensor, thermistor, etc. to detect the voltage that changes depending on the temperature of the NiCd battery 1, and has a negative temperature characteristic where the voltage changes by 13 mV per degree. This is a temperature detector that generates a voltage VT proportional to the change in ambient temperature. Reference numeral 4 denotes an adder that receives the constant voltage VS output from the voltage generator 2 and the voltage VT output from the temperature detector 3, and adds the voltages Vs and VT. The output voltage of adder 4 as a reference voltage V RE F id, (VS + VT)
), the ambient temperature of Nikato battery 1 is 20℃, 0℃ and 40℃
At the time of h i, 5V, 1.56V and h1.
Naru to 44V. 5 is a comparator which receives the detected voltage VB of the battery 1 and the reference voltage VREF output from the adder 4 as input, and has a hysteresis width for determining the magnitude of the detected voltage VB and the reference voltage VREF. Its output is V
B (becomes L level when VREFO, and becomes H level when VB≧VREFO. 6 consists of a differentiating circuit, a monostable multivibrator, etc., and uses the output of comparator 5 as input, and the output of comparator 5 changes from L level to This is a short pulse generator that generates a short pulse of H level when the level changes to H level. 7 is a short pulse generator that generates a short pulse of H level when an external DC power supply (not shown) is connected to the input terminal IN or the short pulse generator 6 generates a short pulse of H level. After inputting a short pulse of , H
This is a timer that outputs the level.

In this embodiment, the set time of the timer 7 is selected to be 4 hours. R1, R2, and R3 are resistors that determine the charging current from the external DC power source to the nickel-cadmium battery 1, and are current-limiting resistors that determine a quick charging current, a safe maximum charging current, and a trickle charging current, respectively. The rapid charging current is a current (
0.3C or higher), and in this embodiment, 0.3C is selected.

The safe maximum charging current is the current that does not cause deterioration of NiCd battery 1 even if a constant current is passed for a long time (O, OS ~ 0.2C)
In this embodiment, 0.1C is selected. Trickle charging current is generally used at 0.02 to 0.05C, but in this embodiment, 0.055C is selected. Trickle charging compensates for non-self-discharge of the NiCd battery 1, and is not necessarily necessary and can be omitted. SW1 and SW2 are switches that are made up of analog switches, semiconductor switches, relays, etc., and are activated according to the level of the control terminal C. switch SW1
An external DC power supply is connected to the common terminal CO of the input terminal IN. The output of timer 7 is sent to switch SW1.
It is connected to control terminal C of. When the output of timer 7 is at L level, the common terminal C of switch SW1
O is connected to a normally closed (hereinafter referred to as NC) terminal, and the NC terminal is connected to the nickel-cadmium battery 1 through the resistor R1 and switch SW2, or through the resistors R1 and R2.
The nickel-cadmium battery 1 is charged with a charging current of 0.3C or 0.1C from an external DC power source. When the output of the timer 7 is at the H level, the common terminal CO of the switch SW1 is connected to the normally open (hereinafter referred to as NO 5) terminal, and the No terminal is connected to the NiCd battery 1 via the resistor R6. The Ni-Cd battery 1 is trickle charged with a charging current of 0.033C from an external DC power source. The output of the comparator 5 is connected to the control terminal C of the switch SW2.

When the output of comparator 5 is at L level, switch S
Connect the common terminal CO and NC terminal of W2, and connect the resistor R
2 is short-circuited, a charging current of 0.5C flows through the two-cadmium battery 1. When the output of the comparator 5 is at H level, the common terminal CO and the NC terminal of the switch SW2 are in an open state, and a charging current of 0.1C is applied to the 2-cad battery 1 via the resistors R1 and R2. flows. external DC
The power source is a DC power source that generates a voltage 2 to 5 times the initial charging voltage of the NiCd battery 1. In this embodiment, the initial charging voltage of the NiCd battery 1 is approximately 1V, and the voltage of the DC power source is selected to be 5V. ing.

The operation of this embodiment will be described below with reference to FIG. 1 and FIG. 2 showing a charging characteristic diagram in 2GC.

When an external DC power source is connected to the input terminal IN, the charging control circuit with battery protection circuit shown in FIG. is compared with the reference voltage vRIF produced by the adder 4, and since VB<VREF, an L level is outputted to its output. Therefore, the Ni-Cd battery 1 has an external D
Switch SW1, resistor R1 and switch SW from C power supply
2 with a charging current of 0.3C (as shown in charging current curve 9 in FIG. 2). As shown in charging voltage curve 8 in Figure 2, the charging voltage characteristic at this time is that the voltage rises rapidly for about an hour from the beginning, and after that, the voltage gradually decreases at a low slope. increases, and due to changes in the internal state of the NiCd battery 1, the voltage begins to rise rapidly at the end of charging. When the charging voltage VB of the Ni-Cd battery 1 suddenly rises and becomes higher than the reference voltage VREF generated by the adder 4 (at point A of the charging voltage curve 8 in FIG. 2), the output cuff %H of the comparator 5 increases. /L/, and the switch SW2 is opened. Therefore, the charging current of the nickel-cadmium battery 1 is
(as in charging current curve 9 in FIG. 2) through 0. I
It becomes C.

Furthermore, since the output of the comparator 5 becomes H level, the short pulse generator 6 generates a short pulse, and the timer 7
and restart timing.

If the charging voltage VB of the nickel-cadmium battery 1 does not become higher than the reference voltage VREF within the time set by the timer 7, the timer 7 times up and its output becomes H level, which causes the common terminals CO and N of the switch SW1 to rise.

The charging current changes from 0.3C to trickle charging of 0.033C via resistor R5.

When the charging current changes from α3C to [1)C, as shown in Figure 2, it first suddenly drops by about 0.1V, then gradually drops by about 0.1V, and the time amplifier's time increases. That is, 4 hours after starting charging with a charging current of 0.1C (
In other words, when the time period A-8 of the charging voltage curve 8 in FIG. 2 has elapsed, the timer 7 times out, completes the supplementary charging, and outputs an H level to its output. Therefore, the common terminal CO and NO terminal of the switch SW1 are connected, and the Ni-Cd battery 1 is trickle charged via the resistor R3.

FIG. 3 shows a second embodiment in which the charging control circuit of the present invention is incorporated into a portable device.

In this embodiment, the current limiting resistors R1 and R of the first embodiment are
2 and R3 are replaced by a charging control circuit 21 using a current setting device and a constant current circuit, and blocks that operate in the same manner as in the first embodiment are given the same numbers.

1) is 0.3C, 0,IC and a voltage corresponding to a current of 0.033C (for example, 1.5V, 0.5V and 0.03C).
This is a current setting device that generates a voltage of 165V. 12 is a constant current circuit that generates a constant current proportional to the output voltage of the current setting device 1). 22 is a small portable device (hereinafter referred to as
(referred to as load). 25 is an AC adapter for converting a commercial power source into a DC power source and supplying an operating current and a charging current to the load 22 and the charging control circuit 21, respectively.

SW5 is a power supply disconnection switch and is also used to detect power on.

First, the configuration of the charging control circuit 21 of this embodiment will be described. However, the description of the same configuration as the first embodiment will be omitted.

The outputs of (lL3C and l1lL1C) of current setting device 1) are connected to the NC terminal and NO terminal of switch SW2, respectively. The 0.033C output of current setting device 1) and the Co terminal of switch SW2 are connected to switch SW1. NO
It is connected to the terminal and the NC terminal, respectively. The Co terminal of the switch SW1 is connected to the control terminal C of the constant current circuit 12. Current output I of constant current circuit 12,
OUT is connected to the NiCd battery 1 via a diode D1 for blocking reverse current. One of the inputs of the OR gate 15 is connected to the output of the single pulse generator 6, and the other input is pulled up by a resistor R4 and grounded via the normally shorted switch 5W3-2. OR gate 1
One of the inputs of the timer 6 is connected to the output of the timer 7, and the other one is connected to one of the inputs of the OR gate 15. A voltage detection input of the comparator 5 is connected to the Ni-Cd battery 1 via a switch 5W3-3 which is normally in a short-circuited state.

In this example, since the Ni-Cd battery 1 is used, which is made up of four batteries connected in series with a nominal voltage of 1.2 V, it has a negative temperature characteristic where the voltage changes by -12 mV per 1 degree.
It has been replaced with a temperature detector 3 that generates a voltage VT proportional to the change in the ambient temperature of the Ni-Cd battery 1.

Further, the output voltage VREF of the adder 4 as a reference voltage is selected to be 6V, 6.24V, and 5.76V when the ambient temperature of the Ni-Cd battery 1 is 20°C, 0°C, and 40°C, respectively.

Next, the overall configuration of this embodiment will be explained.

One output 0UT1 of the AC adapter 26 is connected to the input IN of the charging control circuit 21, and the other output 0tJT2 is connected to the load 22 via the reverse blocking diode D3 and the switch 5W3-1.
are connected to each. Output O of charging control circuit 21
UT is a reverse blocking diode D2 and a switch 5W3-
1 to a load 22.

FIG. 4 is a diagram illustrating an example of a time chart during AC drive for long-term use at home with AC drive.

FIG. 5 is a diagram showing an example of a time chart when the battery-powered device is used in a place without a commercial power source, such as inside a car or outdoors.

Using Figures 3 and 4, regarding the operation during AC drive,
This will be explained below.

When the AC adapter 23 is connected to a commercial power source, the charging control circuit 21 is activated and starts the timer 7 (at this time,
output is L level), and the voltage V of the Ni-Cd battery 1
'B is compared with the reference voltage VREF created by the adder 4, and outputs L level as V'B (VREF). Therefore, the Ni-Cd battery 1
．． 30 output is sent to the control terminal C of the constant current circuit 12 via the NC terminal-Co terminal of the switch SW2 and the NC terminal-Co terminal of the switch SW1, and the constant current circuit 12 (charging current curve 9a in FIG. Start charging with a charging current of 0.3C (as shown in Figure 1). As shown in charging voltage curve 8a in Figure 4, the charging voltage characteristics at this time are that the voltage rises rapidly for the first hour, and after that, the voltage gradually decreases at a low slope. Rise.

When switch SW3 is turned on after approximately 2 hours have elapsed from the start of charging, diode D3 is connected from output 0UT2 of AC adapter 23.
Power is supplied to the load 22 through the switch 5W3-1 and the switch 5W3-1, and the load 22 is operated.

At this time, the switch 5W3-2 becomes open, and one input of each of the OR gates 15 and 16 becomes H level, resetting the timer 7 and activating the switch SW1. Switch SW1 is activated and switch SW1 is N.
n033c of current setting device 1) via o terminal - Co terminal
The output is sent to the control terminal C of the constant current circuit 12, and trickle charging of 0.033C is performed on the two-cadmium battery 1 from the current output 1 and OUT of the constant current circuit 12 via the diode D1 while the load 22 is operating. . Also, switch 5W
3-3 is also in an open state, and since V'B<VREF, the output of the comparator becomes L level.

When the switch SW3 is operated after the load 22 has been operated for about 5 hours (see FIG. 4, 17a), the switch 5W3-2 becomes conductive, and the NC terminal and Co terminal of the switch SW1 are connected. In addition, the switch 5W3-3 also becomes conductive, and the comparator 5 detects the voltage V' of the Ni-Cd battery 1.
B is compared with the reference voltage VREF, and since V'B<VREF, an L level is output as the output, but the switch 5W2
Fi does not change. Therefore, in the Nicad battery 1, the 0.3C output of the current setting device 1) is at the NC terminal -C of the switch SW2.
It is sent to the control terminal C of the constant current circuit 12 through the o terminal and the NC terminal-Co terminal of the switch SW1, and the constant current circuit 12 receives the 0.0. Charging is started with a charging current of 30°C. As shown in the charging voltage curve 8a in Figure 4, the charging voltage characteristic at this time is that the voltage rises rapidly for the first 20 minutes, and after that, the voltage gradually decreases at a low slope. Due to changes in the internal state of the NiCd battery 1, the voltage begins to rise rapidly at the end of charging. When the charging voltage V'B of the Ni-Cd battery 1 suddenly rises and becomes higher than the reference voltage VREF generated by the adder 4 (at point A of the charging voltage curve 8a in FIG. 4), the output of the comparator 5 becomes H level. , the switch SW2 is activated, and the α1C output of the current setting device 1) is set to the switch SW2.
Control terminal C of constant current circuit 12 via No terminal-Co terminal of switch SW1 and NC terminal-Co terminal of switch SW1.
will be sent to. Therefore, the current output 1. of the constant current circuit 12.
OUT (as shown in charging current curve 9a in FIG. 4). The nickel-cadmium battery 1 is charged with the charging current of the IC. Further, since the output of the comparator 5 becomes H level, the short pulse generator 6 generates a short pulse, resets the timer 7, and restarts timekeeping.

If the charging voltage V'B of the Ni-Cd battery 1 does not become higher than the reference voltage VREF within the time set by the timer 7, the timer 7 performs a time amplification and its output becomes H level, and the common terminal CO and NΦ terminal of the switch SW1 are Connect with
The o and o33c outputs of the current setting device 1) are sent to the control terminal C of the constant current circuit 12, and the Ni-Cd battery 1 is 0.3
Instead of the charging current of C, the current output of the constant current circuit 12 1. O
Changes from UT to trickle charging of α033C.

When the charging current changes from L3C to α1C, as shown in Fig. 4, it first rapidly drops by about α4■, then gradually drops by about α4■, and then the time-up time, that is, the charging of α1C. When 4 hours have elapsed since the start of charging with current (in other words, the time between A and 8 of charging voltage curve 8a in Figure 4), timer 7 times out, completes supplementary charging, and outputs an H level. Output. Therefore, the common terminal CO and the N6 terminal of the switch SW1 are connected, and the 0.033C output of the current setting device 1) is sent to the control terminal C of the constant current circuit 12, and the Ni-Cd battery 1 is charged with a charging current of α1C. Current output of constant current circuit 12 1. It is charged by trickle charging at 0.033C from OUT.

Next, the case where the load 22 is driven by the nickel-cadmium battery 1 will be described below using FIGS. 3 and 5.

First, in order to fully charge the Nicad battery 1, the AC adapter 26 is connected to a commercial power source. Then, charging control circuit 2
1 is activated, starts the timer 7 (at this time, the output is at L level), and compares the voltage V'B of the Ni-Cd battery 1 with the reference voltage VREF created by the adder 4,
Since V'B<VREF, an L level is outputted. Therefore, the nickel-cadmium battery 1 has a current setting device 1) of 0.3C.
The output is connected to the constant current circuit 12 via the NC terminal-CO terminal of switch SW2 and the NC terminal-CO terminal of switch SW1.
is sent to the control terminal C of the constant current circuit 12,
As shown in the charging current curve 9b of FIG.
Charging is started with a charging current of C. As shown in charging voltage curve 8b in Figure 5, the charging voltage characteristic at this time is that the voltage rises rapidly for the first hour, and after that, the voltage gradually decreases at a low slope. Due to changes in the internal state of the NiCd battery 1, the voltage begins to rise rapidly at the end of charging. When the charging voltage V'B of the Ni-Cd battery 1 suddenly rises and becomes higher than the reference voltage VREF generated by the adder 4 (at point A1 of the charging voltage curve 8b in FIG. 5), the output of the comparator 5 becomes H. level, the switch SW2 is activated, and the α1C output of the current setting device 1) is set to the NO terminal -c of the switch SW2.
The control terminal CK of the constant current circuit 12 is sent through the o terminal and the NC terminal-CO terminal of the switch SW1. Therefore, from the current output (1) of the constant current circuit 12, OUT (as shown in the charging current curve 9b in FIG. 5), 0. The nickel-cadmium battery 1 is charged with the charging current of the IC. Further, since the output of the comparator 5 becomes H level, the short pulse generator 6 generates a short pulse, resets the timer 7, and restarts timekeeping.

When the charging current changes from 0.30 to olc, 8 in Figure 5
As shown in b, after the first sudden drop of about 0.4V, the drop is further gradually about α4V, and the time of the time amplifier is 4 hours after starting charging at a charging current of 0.1 ('). (In other words, the AI of the charging voltage curve 8b in FIG.
-81), the timer 7 times out, completes supplementary charging, and outputs an H level. Therefore, the common terminals CO and N' of switch sw1? 5 terminal, the 0.053C output of the current setting device 1) is sent to the control terminal C of the constant current circuit 12, and the Ni-Cd battery 1 receives the current output of the constant current circuit 12 instead of the 0.1C charging current. 1. It is charged by trickle charging of α033C from OUT.

After charging the Ni-Cd battery 1 for about 1 hour (see FIG. 5, 18), the AC adapter 23 is removed for use inside the car or outdoors.

When the switch SW3 is activated (see FIG. 5, 17b),
A current of 0.20 flows from the Ni-Cd battery 1 through the diode D2 to the load 22 as shown in FIG. 5, 9b.

At this time, the voltage of the nickel-cadmium battery 1 is approximately 0.15 when the switch 5W3-1 is turned on, as shown in FIG. 5, 8b.
The voltage drops to a constant voltage (about 5.2 V) at a gradient of about 0.01 V/min, then drops at 1 for about 40 minutes, and then gradually drops.

When the switch is turned off (see FIG. 5, 17b), the voltage of the nickel-cadmium battery 1 rises by about 0.1 sV and is maintained until it is charged again.

When the AC adapter 1 is connected to a commercial power source again, the NiCd battery is charged again and the device operates in almost the same way as when AC is driven.

In addition, in FIG. 1 or FIG. 5, the comparator 5 is configured to generate an output not only when the voltage of the storage battery exceeds a predetermined value, but also when the temperature of the storage battery exceeds a predetermined value. When the temperature rises, it is possible to switch to supplementary charging.

(Effects of the Invention) The present invention detects the voltage of a Ni-Cd battery that rises rapidly at the end of charging due to chemical changes within the Ni-Cd battery due to the quick charging current, switches from the quick charging current to charging at the safe maximum charging current, and By performing supplementary charging at a controlled safe maximum charging current, it is possible to obtain a long-life, highly safe full charge in a short time without causing any deterioration of the Ni-Cd battery.

In addition, the charging of the quick charging current is monitored over time, and if the charging voltage does not reach a predetermined voltage within a certain period of time, the protection of the nickel-cadmium battery and charging control circuit is achieved by switching to trickle charging or terminating charging. It is possible to plan.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first embodiment of the present invention. FIG. 2 is a graph showing charging current versus charging voltage characteristics. FIG. 3 is a block diagram showing a second embodiment of the invention. FIGS. 4 and 5 are operation time charts of the second embodiment when driven by an AC power source and a battery, respectively. 1; Storage battery; 2; Voltage generator.

Claims (3)

[Claims] (1) In a charging control circuit that charges a storage battery, (a)
A detection circuit (2, 3, 4, 5) that detects that the voltage or temperature of the storage battery (1) exceeds a predetermined value, and (b) a timer (2, 3, 4, 5) that outputs an output after the activation setting time has elapsed using the output of the circuit. (7); (c) a resistor or constant current circuit inserted between the storage battery (1) and the power source, which is switched by a switch controlled by the timer and a switch controlled by the detection circuit; (d) performing rapid charging at the first large current until the voltage of the storage battery reaches a predetermined value by controlling each of the switches;
Thereafter, the charging control circuit performs supplementary charging with a second current smaller than the first current until the timer generates an output, and thereafter performs trickle charging with a third current smaller than the second current. . (2) The charging control circuit according to claim 1, wherein the timer setting time is adjustable. (3) The charging control circuit according to claim 2, wherein the set time of the timer is adjusted according to the operating time of the load.