JP2744071B2 - Charge control circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge control circuit that starts operation by being supplied with power from a storage battery, detects full charge of the storage battery, and performs charge control.

[Conventional technology]

Conventionally, a charge control circuit that controls charging of a storage battery by a microcomputer has been known.

That is, as shown in FIG. 6, when the AC power supply 5 is connected to the charging circuit 11, the charging of the storage battery B is started.

Then, when the storage battery B is fully charged, the microcomputer 3 sends a charge control signal to the charging circuit 11, switches the charging current to the storage battery B to a very small current, and maintains the full charge of the storage battery B.

[Problems to be solved by the invention]

However, in the above-described conventional charge control circuit, since the storage battery B is used as the power supply of the microcomputer 3, for example, the capacity of the storage battery B is reduced due to overdischarge from the storage battery B to the load 6, and the terminal voltage of the storage battery B is reduced. Is lower than the operation start voltage of the microcomputer 3, the microcomputer 3 does not operate for the first time even if charging is started thereafter.

In many cases, a plurality of the storage batteries B are used in series. However, a variation in the capacity of each storage battery B causes a reversal or the like after the connection, and the voltage between the terminals of the storage battery B is lower than the operation start voltage of the microcomputer 3. Is low, the microcomputer 3 does not operate at the beginning of charging.

Further, the charging control circuit prevents only a very small current from flowing through the storage battery B until the microcomputer 3 operates normally in order to prevent overcharge and the like of the storage battery B and secure safety. For this reason, even if the AC power supply 5 is connected to the charging circuit 11 and charging is started, it takes a considerable time until the voltage between the terminals of the storage battery B increases and the microcomputer 3 starts operating.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problem and to provide a charge control circuit that hasten the start of charging and hasten the rise of the voltage between terminals of a storage battery.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a charge control method that starts operation by being supplied with power from a storage battery, and switches a charging current supplied from the charging unit to the storage battery to a small current after detecting the full charge of the storage battery. In a charge control circuit including a charge control unit having a microcomputer that sends out a signal, power is supplied from one of the charging unit and the storage battery, and operation starts at a voltage lower than an operation start voltage of the microcomputer, A second charging control means for supplying a charging current from the charging section to the storage battery until the supply voltage to the microcomputer reaches the operation start voltage of the microcomputer.

[Action]

According to the charge control circuit having the above configuration, when the voltage supplied from the storage battery to the microcomputer is lower than the operation start voltage of the microcomputer, the supply of the charging current from the charging unit to the storage battery is performed by the second charging control means. Then, the supply of the charging current is continued until the operation start voltage of the microcomputer is reached.

〔Example〕

FIG. 1 is a block diagram showing a first embodiment of a charge control circuit according to the present invention.

The charging control circuit includes a charging unit 1, a filter circuit 2, a microcomputer 3, a display unit 4, a runaway detection circuit 7, and a transistor Q1.

The charging unit 1 includes a charging circuit 11 and a storage battery B,
When the AC power supply 5 is connected, the charging current is supplied to the storage battery B. When a charge control signal is input from the microcomputer 3, the charging circuit 11
A small current (trickle current), which is a much smaller current than the charging current, is supplied to maintain full charge.

The filter circuit 2 is for removing noise on the power supply line. That is, the voltage from the storage battery B is supplied to the microcomputer 3 and the runaway detection circuit 7 via the filter circuit 2.

The microcomputer 3 detects the charging time, the voltage between the terminals of the storage battery B, and the like, and detects the full charge of the storage battery B. When full charge is detected, a high signal as a charge control signal is sent from the output terminal O1 of the microcomputer 3 to the input terminal P1 of the charging unit 1. The microcomputer 3 sends a display signal indicating the capacity of the storage battery B to the display unit 4.

The display unit 4 includes an LCD or an LED, and displays the capacity of the storage battery B according to a display signal from the microcomputer 3.

That is, as shown in FIG. 4A, the display unit 4 includes LEDs 1 to 5 having a length corresponding to the capacity of the storage battery B.
For example, when the capacity of the storage battery B is 81% to 99%, the LED 5 blinks, and when the capacity reaches 100%, the LED 5 is turned on. The LED 8 is turned on when the storage battery B is being charged.

In addition, as a second embodiment of the display unit 4, as shown in FIG.
There is one at each of the nine tips. This display section 41
In this example, the LEDs are turned on up to a level corresponding to the capacity of the storage battery B. That is, for example, if the level is 3, the LEDs 11 to 13 are turned on.
The levels are divided into five levels according to the capacity of the storage battery B, and levels 1, 2, and
...

Further, as a third embodiment of the display unit 4, FIG.
As shown in FIG. 1, there is a type in which the capacity of the storage battery B is indicated by the number of LEDs 10 and 10 in the vertical direction. That is, this display section
In 42, for example, if the capacity of the storage battery B is equal to or more than level 2 and less than level 3, the LEDs 10 in the three rows from the left in the figure are turned on, and the LED 10 at the tip of the third row is blinking (in the figure,
(Indicated by diagonal lines). When the capacity of the storage battery B reaches the level 3, the blinking LED 10 is also switched on.

Runaway detection circuit 7 detects a detection pulse from microcomputer 3 and controls on / off of transistor Q1.

That is, the microcomputer 3 sends out a detection pulse when normal. While the detection pulse is being input, the runaway detection circuit 7 turns the output low to turn off the transistor Q1.

On the other hand, when the detection pulse is no longer input, the runaway detection circuit 7 determines that the microcomputer 3 has runaway, and makes the output open. As a result, the voltage from the filter circuit 2 is applied to the base of the transistor Q1 via the resistor R1, and the transistor Q1 turns on. Therefore, the output terminal O1 of the microcomputer 3 is short-circuited to GND, and the transmission of the charge control signal from the microcomputer 3 is prohibited.

That is, the runaway detection circuit 7 and the transistor Q1 double as a safety circuit for preventing erroneous charge control due to the runaway of the microcomputer 3 and a charge control circuit for the storage battery B at the start of charging.

The switch SW1 controls on / off switching of current supply from the storage battery B to the load 6.

Next, the operation of the above embodiment will be described with reference to FIG. The voltage V1 is an operation start voltage of the microcomputer 3 and the runaway detection circuit 7, and the voltage V2 is an ON voltage of the transistor Q1. Also, for convenience of explanation,
The capacity of the storage battery B is 0%, and the voltage of the power supply terminal VDD of the microcomputer 3 before the AC power supply 5 is connected is 0V.

When the AC power supply 5 is connected to the charging unit 1, the charging circuit 11 starts a charging operation. At this time, since the voltage of the power supply terminal VDD of the microcomputer 3 is 0 V, the microcomputer 3 does not operate and the output terminal O1 is in an open state. As a result, this is the same as when high is input to the input terminal P1 of the charging circuit 11, and the charging circuit 11 performs the same operation as when the storage battery B is fully charged.

Accordingly, a trickle current flows from the charging circuit 11 to the storage battery B, and the voltage of the power supply terminal VDD gradually increases.

Then, at time t1, the voltage of the power supply terminal VDD is a transistor
It increases to the ON voltage V2 of Q1. The microcomputer 3 and the runaway detection circuit 7 do not operate because the microcomputer 3 and the runaway detection circuit 7 are much lower than the operation start voltage V1, and the output of the microcomputer 3 and the runaway detection circuit 7 are both open. Remains in a state.

Therefore, the transistor Q1 is connected to the above-described voltage via the resistor R1.
V2 is applied to the base and turns on. When the transistor Q1 turns on, the output terminal of the microcomputer 3
O1 is short-circuited to GND, the input terminal P1 of the charging circuit 11 becomes low, and the supply of charging current from the charging circuit 11 to the storage battery B is started. That is, as shown in FIG. 5 (a), after the lapse of the time point t1, the voltage of the power supply terminal VDD of the microcomputer 3 (solid line A) is a trickle current when the microcomputer 3 does not operate as in the prior art. Rises in a shorter time as compared with the case of charging (dashed-dotted line B, time 0 to t3).

On the other hand, when the voltage of the power supply terminal VDD becomes V1 at time t2, the microcomputer 3 and the runaway detection circuit 7 start operating. For this reason, the microcomputer 3 starts sending detection pulses to the runaway detection circuit 7 and outputs
Sends a row from O1. At the same time, the microcomputer 3 starts sending a display signal to the display unit 4.

Further, the runaway detection circuit 7 detects the above detection pulse, determines that the microcomputer 3 is operating normally, outputs low, and turns off the transistor Q1. That is,
The charging circuit 11 continuously supplies a charging current to the storage battery B.
The display unit 4 displays the capacity of the storage battery B.

Thereafter, when the microcomputer 3 detects that the storage battery B is fully charged, the microcomputer 3 sends the charging circuit
A charge control signal is sent to 11, and the current to the storage battery B is switched to the trickle current.

As described above, in the above embodiment, the transistor Q1 is turned on at a voltage V2 lower than the voltage V1 at which the microcomputer 3 starts operating, a low is input to the input terminal P1 of the charging circuit 11, and the charging current is supplied to the storage battery B. Let it be supplied.

Next, a second embodiment of the charge control circuit according to the present invention
This will be described with reference to the drawings. In the figure, the same reference numerals as in FIG. 1 denote the same parts.

The charge control circuit in this embodiment includes a resistor R2 and a diode D1 from a power supply terminal P2 of the charging circuit
Are inserted in series.

That is, the power supply terminal P2 of the charging circuit 11 is connected to the output of a stabilized power supply unit (not shown) provided in the charging circuit 11. This stabilizing power supply unit is for supplying power to an oscillation control IC and the like (also not shown) in the charging circuit 11, and when the AC power supply 5 is connected to the charging unit 1, the output becomes the above-mentioned voltage.
The voltage is increased to a predetermined voltage V3 equal to or higher than V1 (see FIG. 5B).

Next, the operation of the second embodiment will be described with reference to FIG. In this embodiment, as in FIG. 5 (a), the capacity of the storage battery B is 0%, and the voltage of the power supply terminal VDD before the AC power supply 5 is connected to the charging unit 1 is 0V.

When the AC power supply 5 is connected to the charging unit 1 and the charging circuit 11 starts the charging operation, the output voltage of the power supply terminal P2 of the charging circuit 11 becomes a predetermined voltage V3 as shown by a solid line C in FIG. Rises steeply towards. Also, this output voltage is
2, transistor Q1 via diode D1 and resistor R1
Applied to the base. Then, when the output voltage rises to the on-voltage V2 of the transistor Q1 at time t4, the transistor Q1 turns on and a low is input to the input terminal P1 of the charging circuit 11. As a result, the supply of the charging current from the charging circuit 11 to the storage battery B is started, and the terminal voltage of the storage battery B rises relatively quickly. When the voltage of the power supply terminal VDD becomes the voltage V1 at time t5, the microcomputer 3 and the runaway detection circuit 7 start operating, and the microcomputer 3 sends out a detection pulse. Runaway detection circuit 7 detects the detection pulse and turns off transistor Q1, and display unit 4 starts displaying the capacity of storage battery B.

In this embodiment, since the voltage of the power supply terminal VDD rises simultaneously with the start of the operation of the charging circuit 11, the time until the microcomputer 3 operates is reduced, and the time until the capacity of the storage battery B is displayed can be further reduced. .

Next, a third embodiment of the charge control circuit according to the present invention
This will be described with reference to the drawings. In the figure, the same reference numerals as in FIG. 1 denote the same parts.

In the charging control circuit of the present embodiment, a resistor R3 and a diode D2 are inserted in series between the power supply terminal P2 of the charging circuit 11 and the base of the transistor Q1 instead of the resistor R1.

Next, the operation of the third embodiment will be described with reference to FIG. In this embodiment, the capacity of the storage battery B is 0%.
Assume that the voltage of the power supply terminal VDD before the AC power supply 5 is connected to the charging unit 1 is 0V.

When the AC power supply 5 is connected to the charging unit 1 and the charging circuit 11 starts the charging operation, the output voltage of the power supply terminal P2 of the charging circuit 11 becomes the predetermined voltage in the same manner as the solid line C in FIG.
It rises steeply toward V3. Then, at time t4, the voltage rises to the ON voltage V2 of the transistor Q1, the transistor Q1 turns on, and a low is input to the input terminal P1 of the charging circuit 11. Therefore, a charging current is supplied from the charging circuit 11 to the storage battery B, and the terminal voltage of the storage battery B increases.

As a result, as shown by the dashed line D in FIG.
At time t6, the voltage of the power supply terminal VDD reaches the voltage V1, and the microcomputer 3 and the runaway detection circuit 7 start operating. Therefore, the microcomputer 3 sends out a detection pulse, which causes the runaway detection circuit 7 to output the transistor Q1.
Turn off. Further, the display unit 4 displays the capacity of the storage battery B based on a display signal from the microcomputer 3.

In this embodiment, when the AC power supply 5 is connected to the charging unit 1, the output voltage of the power supply terminal P2 of the charging circuit 11 rises sharply and the transistor Q1 turns on, so that the time until the microcomputer 3 operates is reduced. The time required for displaying the capacity of the storage battery B can be further reduced.

The microcomputer 3 and the runaway detection circuit 7
Since the power is supplied from the storage battery B, the load on the stabilized power supply unit of the charging circuit 11 can be reduced.

〔The invention's effect〕

According to the present invention, the charging current is supplied from the charging unit to the storage battery by the second charging control means until the voltage supplied from the storage battery to the microcomputer reaches the operation start voltage of the microcomputer. By increasing the voltage between the terminals of the storage battery in a relatively short period of time, it is possible to prevent the charging time from being prolonged, and to quickly start the operation of the microcomputer.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a charge control circuit according to the present invention, FIG. 2 is a block diagram showing a second embodiment of the present charge control circuit, and FIG. 4 (a), (b) and (c) are diagrams showing an embodiment of a display unit, and FIGS. 5 (a) and (b) are diagrams for explaining the operation of the present charge control circuit. FIG. 6 is a block diagram showing a conventional charge control circuit. 1 ... charging part, 3 ... microcomputer, 4 ... display part, 7 ... runaway detection circuit, 11 ... charging circuit, B ... storage battery, Q1 ... transistor, R1, R2, R3 ... resistance, D1, D2
……diode.

Claims (1)

(57) [Claims] An operation is started by being supplied with power from a storage battery,
After detecting the full charge of the storage battery, in a charge control circuit including charge control means having a microcomputer that sends a charge control signal to switch a charging current supplied from the charging unit to the storage battery to a small current, While the power is supplied from one of the storage batteries, the operation starts at a voltage lower than the operation start voltage of the microcomputer, and the charging is performed during a period until the supply voltage to the microcomputer reaches the operation start voltage of the microcomputer. A charging control circuit for supplying a charging current from the unit to the storage battery.