JP2503796B2 - Charge detection circuit for battery charger - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a storage battery (for example, Ni
-Cd storage battery), charge the end of charging -ΔV
The present invention relates to a charge detection circuit of a charging device that detects (voltage drop), and more specifically, to a charge detection circuit of a storage battery that can be applied to various storage batteries by detecting -ΔV by a logic circuit.

[0002]

2. Description of the Related Art Conventionally, in this type of charging device, a storage battery has the charging characteristics shown in FIG. 4, for example, and when it approaches full charge (when it reaches about 90% of full charge), the charge voltage of the storage battery is -ΔV.
Since it descends only (indicated by arrow A in the figure), this −
When ΔV is detected, the charging circuit is switched to the trickle charging circuit after this voltage drop, and the storage battery is fully charged by a trickle current of, for example, about 20 mA.

A one-chip microcomputer having an A / D conversion function is usually used as a charge detection circuit for detecting the voltage drop (-ΔV). The charge voltage of the storage battery is converted into a digital signal and this digital data is predetermined. By processing, the charging voltage is detected, and its −Δ
It is designed to detect V.

[0004]

The charge detection circuit for the storage battery uses a one-chip microcomputer equipped with an A / D conversion port, so the program (software) must be developed. In addition to the above, a program corresponding to the type of the storage battery is required, the cost is high, and the one-chip microcomputer is used only for the detection of −ΔV, which is a problem from the economical aspect. . Furthermore, if the charge detection circuit fails, it is a one-chip microcomputer, and therefore it is difficult to analyze the failure.

The present invention has been made in view of the above problems, and an object thereof is to configure a discrete digital circuit to reduce the development cost and to use it for various storage batteries.
It is an object of the present invention to provide a charge detection circuit for a storage battery, which is excellent in economic efficiency and can easily analyze a failure or the like.

[0006]

To achieve the above object, a charging detection circuit of a charging device of the present invention comprises a V / F converter 1 for converting the voltage of the storage battery into a rectangular wave signal of a predetermined frequency, and A shift register unit 2 for shifting a rectangular wave signal converted by the V / F converter 1 by a predetermined bit;
A first clock generating section 3 for generating a first clock having a predetermined cycle for shift-driving the shift register section 2.
And a second clock generator 5 for generating a second clock having a shorter cycle than the first clock, and a logical product of the rectangular wave signal converted by the V / F converter 1 and the second clock. The second logical product section 7, the third logical product section 8 that obtains the logical product of the rectangular wave signal shifted by the shift register section 2 and the second clock thereof, and the V / F converter 1 are used for conversion. OR unit 9 for ORing the rectangular wave signal and the rectangular wave signal shifted by the shift register unit 2
The rectangular wave signal obtained by the logical sum unit 9 is used as a clear signal in the first counter unit 10 and the third logical product unit 8 which count the clocks obtained by the second logical product unit 7. A second counter unit 11 for counting the clocks obtained by
The rectangular wave signal obtained by the logical sum unit 9 is used as a clear signal,
When the count value of the first counter unit 10 is compared with the count value of the second counter unit 11, and when the count value of the first counter unit 10 becomes larger than the count value of the second counter unit 11, And a comparator unit 12 that outputs a detection signal of the end of charging of the storage battery, detects a voltage drop (−ΔV) that occurs when the storage battery is charged,
The gist is that the end of the charging is detected.

[0007]

With the above configuration, when the storage battery mounted in the charging device is charged, the voltage of the storage battery rises, and this voltage is converted into a rectangular wave signal of a predetermined frequency by the V / F converter. The frequency of the rectangular wave signal is increased, and the rectangular wave signal is shifted by a predetermined bit in the shift register section. When the logical product of the clocks having the same period as those of the rectangular wave signals is taken in the second and third logical product sections,
When the voltage of the storage battery is rising, the number of output clocks of the second AND section is smaller than the output clock number of the third AND section. Further, when the charging is close to full charge due to the charging characteristics of the storage battery, the voltage of the storage battery drops, that is, due to the voltage drop (−ΔV) of the storage battery,
The frequency of the output rectangular wave signal of the V / F converter 1 becomes low, and the number of output clocks of the second AND section becomes smaller than the output clock number of the third AND section.

The first counter section counts the output clock of the second AND section, the second counter section counts the output clock of the third AND section, and the comparator section The count value of the first counter unit and the count value of the second counter unit are compared with each other, and the output rectangular wave signal of the V / F converter and the output rectangular wave signal of the shift register unit are ORed to obtain The rectangular wave signal is used as a clear signal for the first counter section, the second counter section and the comparator section.

That is, when the voltage of the storage battery is rising, the count value of the first counter unit does not become larger than the count value of the second counter unit, but the storage battery approaches full charge and the voltage of the storage battery becomes When falling (-ΔV), the count value is reversed,
The output of the comparator section becomes "H" level when the charging of the storage battery is started, for example, and becomes "L" level with the voltage drop of -ΔV.

Therefore, it is possible to detect the charging start time of the storage battery by the output signal of the comparator section and detect the charging end of the storage battery, and after detecting the charging end, switch the charging circuit to the trickle charging circuit. , The storage battery can be fully charged.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS. In FIG. 1, a charge detection circuit of the charging device includes a V / F converter 1 for converting a voltage of a storage battery (for example, a Ni-cd storage battery) mounted therein into a rectangular wave signal of a frequency, and the converted rectangular wave signal. A shift register unit 2 for shifting a predetermined bit (for example, 3 bits),
A first clock generating section 3 for generating a first clock having a predetermined cycle for shifting the shift register section 2 and an output signal of the shift register section 2 (shifted rectangular wave signal)
Is used as a clock, and the power supply (V; 5V) is set. D
Type flip-flop circuit 4, a second clock generator 5 for generating a second clock having a shorter cycle than the clock generated by the first clock generator 3, and a Q output of the flip-flop circuit 4. And a first logical product (AND) circuit 6 for taking the logical product of
/ F converter 1 output rectangular wave signal and its first AND
The second logical product (A
ND) circuit 7, a third logical product (AND) circuit 8 for taking a logical product of the output rectangular wave signal of the shift register section 2 and the output clock of the first AND circuit 6, and the V / F converter 1 And an output rectangular wave signal of the shift register unit 2 and a logical sum (OR) circuit 9
The rectangular wave signal output from the OR circuit 9 is used as a clear (CLK) signal, and the first counter section 10 of a predetermined bit (for example, 4 bits) for counting the output clock of the second AND circuit 7 and the OR circuit thereof. The output rectangular wave signal is used as a clear signal, and the second counter section 11 of a predetermined bit (for example, 4 bits) for counting the output clock of the third AND circuit and the output rectangular wave signal of the OR circuit 9 are cleared (CLK ) Signal and compare the count values of these predetermined bits, and when the value of the first counting unit 10 is smaller than the value of the second counter value 11, for example, output an "H" level signal, and vice versa. At this time, the comparator section 12 that outputs an "L" level signal is provided.

Next, the operation of the charge detection circuit of the charging device having the above configuration will be described with reference to the timing charts of FIGS. For the sake of explanation, FIG. 2 (h) and FIG. 3 (j) and FIG. 2 (i) and FIG. 3 (k) are the same timing charts.

First, when a storage battery is attached to the charging device, the charging switch is turned on, and charging of the storage battery is started, the voltage of the storage battery rises as described above (shown in FIG. 4). . At this time, the V / F converter 1
The rectangular wave signal having the frequency corresponding to the rising voltage is output at (indicated in FIG. 2B), and the first and second clock generators 3 and 5 generate clocks having a predetermined cycle, respectively. (As shown in FIGS. 2C and 2D), the rectangular wave signal is shifted by 3 bits in the shift register unit 2 (shown in FIG. 2C).

As shown in FIG. 2 (f), the output rectangular wave signal of the shift register section 2 sets the power supply (V; 5V) of the charge detection circuit in the flip-flop circuit 4, and this flip-flop circuit. Since the Q output of 4 becomes the “H” level, the second clock generated by the second clock generation section 5 is passed through the first AND circuit 6 to the second AND circuit 7 and the third AND circuit. Is output to the AND circuit 8. Further, the output rectangular wave signal of the V / F converter 1 and the output rectangular wave signal of the shift register unit 2 are input to the OR circuit 9.

As a result, from the first AND circuit 7,
Only when the output rectangular wave signal of the V / F converter 1 is at "H" level, the output clock of the first AND circuit 6 is output (shown in FIG. 2 (h)), and the second AND circuit 7 is output. From the above, the output clock of the first AND circuit 6 is output only when the output rectangular wave signal of the shift register unit 2 is at the “H” level (shown in FIG. 2 (i)),
A rectangular wave signal is output from the OR circuit 9 (see FIG. 2).
(Shown in (g)).

That is, in the "H" level section of the output rectangular wave signal of the OR circuit 9, the higher the charging voltage of the storage battery, the smaller the number of clocks output from the first AND circuit 6 becomes. The number of clocks output from the AND circuit 7 of 2 decreases after this clock. In addition,
As shown in FIG. 2H, since the flip-flop circuit 4 is not set in the first “H” level section of the output rectangular wave signal of the V / F converter 1, the second AND circuit 7 No clock is output.

Since the output rectangular wave signal of the OR circuit 9 is the clear signal of the first and second counter sections 10 and 11, only when the clear signal is at the "H" level, the first and second counter signals are generated. The counting operation of the counter units 10 and 11 is performed, and the output clocks of the second and third AND circuits 7 and 8 are counted. Therefore, in the “H” level section of the output rectangular wave signal of the OR circuit 9, the count value of the first counter unit 10 does not become larger than the count value of the second counter unit 11 as long as the voltage of the storage battery rises. .

At the start of charging the storage battery,
Although the second counter unit 11 counts (see FIG.
(Shown in (p) to (s)), the first counter unit 11 does not count (shown in (l) to (o) of FIG. 3). As a result, the count values (Q _{0 to} Q ₃ and Q _{4 to} Q ₇ ) are compared in the comparator unit 12, but the count value of the first counter unit 10 is “0”.
Since the count value of the second counting unit 11 is large, the “H” level signal is output.

While the voltage of the storage battery is rising, V
/ F converter 1 output rectangular wave signal pulse width ("H"
Since the level becomes narrower, the count value (Q _{0 to} Q ₃ ) of the first counter unit 10 does not become larger than the count value (Q _{4 to} Q ₇ ) of the second counter unit 11, and the comparator unit 12 The output signal remains at "H" level (shown in FIG. 3 (t)).

However, as described above, when the voltage of the storage battery approaches full charge, for example, when it reaches about 90% of full charge, the voltage of the storage battery decreases by -ΔV (arrow in FIG. 2A). B), the rectangular wave signal output from the V / F converter 1 has a pulse width (“H”) different from that before.
Level) becomes wider (shown in FIG. 2 (a)).

Then, in the section where the pulse width is widened,
In addition, the number of output clocks of the second AND circuit 7 is the third
The number of output clocks of the AND circuit 8 of
(Shown in (h) and (i)) of the first counter section 10
Count value (Q₀To Q₃) Of the second counter unit 11
Count value (Q₄To Q₇) Becomes larger. This
The count value (Q₀No
To Q₃And Q₄To Q ₇) Comparison is made, but first
Since the count value of the counter section 10 of is larger,
The "L" level signal is output. This "L" level signal
Is a −ΔV detection signal (charge end signal) of the storage battery,
The charging circuit of the charging device can be turned off.

As described above, since the charge detection circuit of the storage battery can be configured by the logic circuit, as shown in the conventional example, the program is not required, the development cost can be reduced, and even when troubles such as breakdown occur. , Its analysis is easy, and design and development with short feedback is possible.

Further, in the above charge detection circuit, if the V / F converter 1 having a wide input voltage range is used, it can be applied to storage batteries having different full charges, and a charging device applicable to various storage batteries should be developed. Therefore, compared with the case where the program is developed for each storage battery, the development need can be completed at low cost.

After the output signal of the comparator section 12 becomes "L" level, the trickle charging circuit of the charging device is switched to the conventional one as shown in FIG.
(Indicated by arrow C in (t)), the attached storage battery is fully charged by the trickle current.

[0025]

As described above, according to the charge detection circuit of the charging device of the present invention, the V / F converter for converting the voltage of the installed storage battery into the rectangular wave signal of the frequency and the converted rectangular wave. A shift register for shifting the wave signal by a predetermined number of bits, a first clock for generating a first clock of the shift register, and a second clock for generating a second clock having a shorter period than the first clock, A logical product circuit that obtains a logical product of the output rectangular wave signal of the V / F converter and the second clock, and obtains a logical product of the output rectangular wave signal of the shift register and the second clock;
A logical sum circuit that takes the logical sum of the output rectangular wave signals of the V / F converter and the shift register, and the output clocks of the logical product circuit, and the output rectangular wave signal of the logical sum circuit is used as the clear signal. The output rectangular wave signals of the first and second counter sections and their OR circuits are used as clear signals, the count value of the first counter section is compared with the count value of the second counter section, and the comparison result is It is provided with a comparator section for outputting H "and" L "level signals, and by using the" L "level signal, -ΔV, which is the characteristic of the storage battery, is detected and a charge end signal is obtained. Therefore, a microcomputer is used. Instead, it is possible to detect the full charge of the storage battery with a discrete digital circuit, that is, it is possible to switch from the charging circuit to the trickle charging circuit, It does not require the development of a program (software), the development cost can be reduced, and it can be used for various storage batteries with different full charges. The effect is that you can do it.

[Brief description of drawings]

FIG. 1 is a schematic circuit diagram of a charge detection circuit of a charging device showing an embodiment of the present invention.

2 is a timing chart illustrating the operation of the charge detection circuit shown in FIG.

3 is a timing chart illustrating the operation of the charge detection circuit shown in FIG.

FIG. 4 is a characteristic diagram showing charging characteristics of a storage battery.

[Explanation of symbols]

 1 V / F Converter 2 Shift Register Section 3 First Clock Generation Section 4 D-Type Flip-Flop Circuit 5 Second Clock Generation Section 6 First Logical Product (AND) Section 7 Second Logical Product (AND) Section 8 third logical product (AND) section 9 logical sum section 10 first counter section 11 second counter section 12 comparator section

Claims (1)

(57) [Claims] 1. A charging detection circuit of a battery charging device for detecting the end of charging when charging a storage battery,
V / F conversion means for converting the voltage of the storage battery into a rectangular wave signal of a predetermined frequency, shift means for shifting the rectangular wave signal converted by the V / F conversion means by a predetermined bit, and shift driving of the shift means. A first clock generating means for generating a first clock having a predetermined cycle, a second clock generating means for generating a second clock having a shorter cycle than the first clock, and the V / F converting means. ANDing means for taking the logical product of the rectangular wave signal converted by the above-mentioned second clock and the logical product of the rectangular wave signal shifted by the above-mentioned shifting means and the above-mentioned second clock, and the V / F conversion. Means for taking a logical sum of the rectangular wave signal converted by the means and the rectangular wave signal shifted by the shift means, and the rectangular wave signal obtained by the logical sum means as a clear signal, and the logical product means Clock obtained at Comparing the count value of the first counting means and the count value of the second counting means with the rectangular wave signal obtained by the logical sum means as the clear signal However, when the count value of the first counting means becomes larger than the count value of the second counting means, there is provided a comparing means for outputting a detection signal of the end of charging of the storage battery, and the voltage generated when the storage battery is charged. A charge detection circuit for a battery charger, which detects a drop (-ΔV) and detects the end of charging.