JPH0191626A - Battery charging equipment - Google Patents

Abstract

PURPOSE:To contrive to shorten an electrification time by controling the duty cycle of a charging pulse signal according to the terminal voltage of a secondary battery. CONSTITUTION:Charging of a secondary battery 9 is repeated by the ON-OFF action of a switching transistor 8 by means of a signal A. The terminal voltage C of the secondary battery 9 is compared with the given voltage of a reference voltage resistor 15 in a voltage compare part 14a via sampling and hold circuit 12 and A/D converter circuit 13. At the time of signal F>6V, the signal G of a timing controller 14b sends out 'High' and the signal A with 20% duty cycle is outputted from a timing circuit 11. The switching transistor 8 receiving said signal A repeats 80% ON state and 20% OFF state, while the same operation is repeated also in charging of the secondary battery 9 and the terminal voltage C also rises gradually. When the terminal voltage C exceeds a given value, an electrification time is shortened to a certain value.

Description

[Detailed description of the invention] The battery charging device of the present invention will be explained according to the following items.

A. Industrial field of application B1 Overview of the invention C0 Prior art [Figure 6] a. - Shooting background Example of a conventional charging device [Figure 6] D1 Problems to be solved by the invention E0 Problems Means F for solving the problem, Example F-1, First example [Fig. 1, Fig. 2 Komi 9 circuit [Fig. 1 (b), Operation [Fig. 2] b-1, Before switching b -2, C1 characteristic after switching [Fig. 3] F-2, Second embodiment [Fig. 4, Fig. 5 Comi 1 circuit [Fig. 4] b, Timing chart [Fig. 5] C1 characteristic [Fig. FIG. 3G1 Effects of the invention (A. Field of industrial application) The present invention relates to a novel battery charging device. Specifically, in a battery charging device that uses a negative power source to supply power to the secondary battery and each control circuit, faster charging is possible by supplying more current to the secondary battery. The purpose of this invention is to provide a new battery charging device.

(B. Summary of the Invention) The battery charging device of the present invention includes a switching means between the power line and the secondary battery, detects the terminal voltage of the secondary battery, and generates a pulse signal according to the terminal chamber pressure. By operating the switching means to supply power to the secondary battery using a charging pulse signal, the TL source can be directly connected to the secondary battery, and the charging time can be shortened. It is.

(C, Prior Art) [Figure 6] (a, - Shooting background) Some charging devices used to charge secondary batteries such as nickel-cadmium batteries and lead batteries are capable of rapid charging. Yes, charging time can be shortened compared to normal charging.

By the way, in such a charging device, if the power source for charging and the power source for the control circuit are supplied from the same power source, the supply of charging power source voltage becomes excessive during rapid charging, especially at the beginning of charging, and the power source voltage is not supplied to the control circuit. The power supply voltage decreases,
Therefore, there is a risk that the control circuit may malfunction.

It is also conceivable to use separate power supplies for the above-mentioned charging power supply and control circuit power supply, but this would increase product cost and is not practical.

Therefore, at the initial stage of charging, quick charging is not performed but normal charging is performed, and after the terminal voltage of the battery reaches a predetermined value or higher and the power supply voltage of the control circuit does not drop, the rapid charging is performed in line 8. There is something I did.

(b. Example of conventional charging device) [Figure 6] Figure 6 shows a conventional charging device that automatically switches from normal charging to quick charging by measuring the terminal voltage of the secondary battery at the beginning of charging. 1 shows an example a of a circuit of the charging device.

In the figure, an AC power source is connected to a rectifier circuit C composed of a transformer, a diode bridge, and the like.

d is a power supply line extending from one end of the diode bridge in the rectifier circuit C and connecting it to other circuit elements.

e is a changeover switch, which is used to switch between normal charging and quick charging, and the common contact point is + at 7 above.
? One of the independent contacts is connected to the anode of the diode f for quick charging, and the other independent contact is connected to one end of the limiting resistor g.

Further, unless there is a command from a timing control circuit to be described later, the changeover switch e has its movable element in contact with an independent contact on the limiting resistor side, so that normal charging is performed.

h is a secondary battery, the positive electrode side of which is connected to the cathode of the diode f and the other terminal of the limiting resistor g;
The negative electrode side is grounded.

i%j is a voltage dividing resistor, which is inserted in series between the power supply line d and the ground.

k is a comparator, one of its input terminals is connected between voltage dividing resistors i and j arranged in series, and the other input terminal is connected between a diode f, a limiting resistor g, and a secondary battery. The terminal voltage of the secondary battery is compared with a predetermined voltage determined by the voltage dividing resistor j.

1 is a timing control circuit whose input side is connected to the output terminal of the comparator, and receives a signal from the comparator and outputs a switching signal to the changeover switch e.

When charging starts, the current rectified by the rectifier circuit C flows to the secondary battery via the power line d, the changeover switch e, and the limiting resistor g, and also flows from the power line d to the secondary battery. It is directly supplied to the voltage dividing resistors i and j, the comparator k, and the timing control circuit °C, respectively.

Then, as time passes, as the amount of charge in the secondary battery increases, the terminal voltage of the secondary battery increases, and when it becomes higher than the predetermined voltage by the voltage dividing resistor j, this is determined by the comparator k. , outputs an "H" signal to the timing system f'J11 circuit °C. The timing control circuit A to which the rHJ signal has been input outputs a switching command signal to the changeover switch e, thereby switching the movable element of the changeover switch e to an independent contact on the side of the diode f.

When the movable element of the changeover switch e comes into contact with the independent contact on the side of the diode f, current from the power supply line d passes through the diode f and flows directly to the secondary battery, starting rapid charging.

FIG. 3 shows a charging curve, and the conventional example a obtains a charging curve m shown by a dotted line.

In the figure, the vertical axis represents the terminal voltage of the secondary battery, and the horizontal axis represents the charging time.

In the charging curve m in the conventional example a, the terminal voltage of the secondary battery is at a predetermined value ■ from the start of charging. Time to reach (V)
(minutes), that is, during normal charging, it is represented by a relatively smooth slope (charging curve ml), and at time to (minutes) 8 lines, that is, during rapid charging, it is represented by a relatively smooth slope (charging curve m). It is expressed by a gradient (charging curve m2).

(D. Problem that the invention seeks to solve) However,
In such a conventional charging device a, the terminal voltage of the secondary battery is set to a predetermined value at the initial stage of charging (a voltage value that does not allow excessive current to flow to the secondary battery side during rapid charging).
There is a problem in that only normal charging can be used to raise the battery level to 100%, and it takes a long time to charge the entire battery.

(E. Means for Solving the Problems) Therefore, in order to solve the above-mentioned problems, the battery charging device of the present invention has a power supply line inserted between the negative power line and the power supply line and the secondary battery. a voltage detection means for detecting a terminal voltage of a secondary battery; and a timing control means for controlling the switching means in accordance with the terminal voltage of the secondary battery detected by the voltage detection means. In the device, the timing control means outputs a pulse signal, operates the switching means, supplies power to the secondary battery using the charging pulse signal, and determines the duty cycle of the pulse signal output from the timing control means by the voltage detection means. The duty cycle of the charging pulse signal is shortened in the initial stage of charging.

Therefore, according to the battery charging device of the present invention, since the secondary battery is charged by the charging pulse signal and the duty cycle of this charging pulse signal is controlled according to the terminal voltage of the secondary battery, the power supply to the control unit is also possible. In particular, in the early stages of charging, sufficient power can be supplied to the control unit to prevent malfunctions, and since the power line is connected to the secondary battery without going through an element that causes a voltage drop, the charging time can be shortened.

(F. Examples) Below, details of the battery charging device of the present invention will be described according to examples shown in the accompanying drawings.

(F-1, First Embodiment) [Fig. 1, Fig. 2 (a, circuit) [Fig. 1] Fig. 1 shows the first embodiment 1 of the battery charging device of the present invention. be.

2 is an AC power source.

3 is a constant current circuit whose input terminal is connected to the AC power supply 2.

Reference numeral 4 denotes a constant voltage circuit, which is connected to the output terminal of the constant current circuit 3 via a power supply line 5.

Reference numeral 6 denotes a power supply line for control, which is a line for applying a predetermined voltage to a control circuit to be described later.

7 is a backup capacitor, one end of which is connected to the power supply line 6, and the other end grounded. The capacitor 7 is placed immediately after the constant voltage circuit 4, and is provided to compensate for a drop in the source voltage supplied to the control circuit due to fluctuations in the charging voltage.

Reference numeral 8 denotes a PNP type Toshi transistor, which uses its switching operation to generate a charging pulse signal to control the supply of charging voltage to the secondary battery 9. Its emitter is connected to the power supply line 5, and its collector is connected to the battery. 9 are respectively connected to the positive electrode side.

10 is a control circuit, which includes a timing circuit 11, a sample hold circuit 12, an A/D conversion circuit 13, and a control section 14.
For example, it may be configured by software processing on a microcomputer.

The timing circuit 11 is connected to the control unit 14 and the base of the switching transistor 8, applies a base voltage to the switching transistor 8 in response to a command signal from the control unit 14, controls the operation of the switching transistor 8, and controls the sample timing. Hold circuit 12 and A
It is connected to the /D conversion circuit 13 and sends a predetermined pulse signal thereto.

The sample hold circuit 12 has its input terminal connected between the switching transistor 8 and the secondary battery 9, and its output terminal connected to the input terminal of the A/D conversion circuit 13.

The control section 14 includes a voltage comparison section 14a and a timing control section 1.
4b, and the voltage comparator 14a is composed of A/4b.
It is connected to the D conversion circuit 13 and the reference voltage resistor 15, and is preset by the A/D converted and encoded digital signal output from the A/D conversion circuit 13 and the reference voltage resistor 15. A digital signal obtained by A/D converting a voltage, for example, 6V, by means not shown is compared with a digital signal, and the comparison result is sent to the timing control section 14b.

Further, the timing control section 14b is configured as the voltage comparison section 1 described above.
A command signal is sent to the timing circuit 11 according to the comparison result obtained in step 4a.

(b, Operation) [Figure 2C] Below, the circuit operation of the first embodiment 1 of the battery charging device of the present invention is explained in accordance with the timing chart shown in Figure 2. This will be explained as an example.

In the first embodiment, the duty cycle of the charging pulse signal is switched when the terminal voltage of the secondary battery exceeds 6.

Note that the period from the start of charging until the duty cycle of the charging pulse signal is switched is referred to as "before switching", and the period during and after switching of the charging pulse is referred to as "after switching".

Further, A to G in the diagram of FIG. 2 indicate the signal contents of the signal lines as also shown in the block diagram of FIG. 1, and A is the signal sent from the timing circuit 11 to the switching transistor 8; B is a charging pulse signal sent from the switching transistor 8 to the secondary battery 9, C is the secondary battery 9
Indicates the terminal voltage of

D is a voltage level signal of the power supply line 5, and the maximum voltage level is, for example, IOV.

E is from the timing circuit 11 to the sample hold circuit 12
This is a gate pulse that is sent out after a slight delay from the rise of "ON" of B.

F is a signal sent from the sample hold circuit to the A/D conversion circuit 13.

G is a signal sent from the timing control section 14b of the control section 14 to the timing circuit 11.

(b-1, before switching) Immediately after the start of charging, the voltage level of the power supply line 5 is 10■ (signal D), and the terminal voltage of the secondary battery 9 is Ov.
(Signal C). In this state, the switching transistor 8 is in an OFF state, and no current is supplied to the secondary battery 9 (signal B).

Since the terminal voltage of the secondary battery 9 is OV, the sample hold circuit 12 sends a signal F(OV) to the voltage comparison section 14a of the control section 14 via the A/D conversion circuit 13. The voltage comparison unit 14a compares this signal F with a predetermined voltage (6V) obtained by the reference voltage resistor 15, and after determining that the signal F (OV)<6V, the control unit 14
The timing control unit 14b sends a signal G to the timing circuit 11 indicating that the signal is 'Low'. The timing circuit 11 receiving the signal G has a duty cycle of 80
% pulse signal (signal A) is sent to the switching transistor 8, and the switching transistor 8 receives the signal A and operates to turn off during the duty period of the signal A and turn on during the non-duty period. Then, by turning on the switching transistor 8, the signal D(
IOV) is applied to the secondary battery 9 via the switching transistor 8, and when the switching transistor 8 is turned off, power supply to the secondary battery 9 is stopped.

In addition, in the initial stage of charging, the switching transistor 8
When power is supplied to the secondary battery 9 by turning ON, since the terminal voltage C of the secondary battery 9 is Ov, the current flowing to the secondary battery 9 side becomes excessive, and the signal level of the power supply line 5 becomes 0. There is a habit of falling to the vicinity and not being able to supply enough power to the control circuit 10 side. For this purpose, power is supplied to the backup capacitor 7 and stored until the switching transistor 8 is turned on after charging is started.
Even if power supply from the power line 5 side is stopped, power is supplied to the control circuit 10 by discharging the backup capacitor 7.

Further, the timing circuit 11 outputs the gate pulse signal E to the sample and hold circuit 12 with a slight delay from the rise of the signal A, and the sample and hold circuit 12 that receives the signal E samples the terminal voltage C of the secondary battery 9, and as described above. A signal F is outputted to the voltage comparison section 14a of the control section 14 via the A/D conversion circuit 13 as shown in FIG.

Therefore, the switching transistor 8 is turned ON by the signal A sent from the timing circuit 11.
- Charging is repeated by OFF operation, and the terminal voltage C
will gradually rise.

(b-2, after switching) Due to the rise in the terminal voltage C of the secondary battery 9, the voltage is transferred to the reference voltage in the voltage comparison unit 14a of the control unit 14 via the sample and hold circuit 12 and the A/D conversion circuit 13. Compared with a predetermined voltage (6■) by resistor 15, F>6V
When this happens, the signal G from the timing control section 14b sends out that it is rHfgJ, and a duty cycle switching command is output to the timing circuit 11. Upon receiving this, the timing circuit 11 outputs a signal with a duty cycle of 20%. It is designed to output A.

Then, the switching transistor 8 that receives the signal A with a duty cycle of 20% repeats an 80% ON state and a 20% OFF state, and the charging of the secondary battery 9 is also repeated by the ON-OFF operation of the switching transistor 8. Therefore, the terminal voltage C will also gradually rise.

(c, Characteristics) [Figure 3 In Figure 3, the charging curve according to the first embodiment 1 is shown by a solid line 16.

The charging curve 16 in the first embodiment 1 is the charging curve 16a before switching from the start of charging until the terminal voltage C of the secondary battery 9 reaches a predetermined value (6■) is the charging curve 16a of the conventional example a. It can be seen that the charging curve 16b becomes steeper than the curve m1, and when the terminal voltage C of the secondary battery 9 exceeds a predetermined value (6V), the charging curve 16b becomes even steeper, and the time is shortened until it reaches a certain value.

(F-2, Second Embodiment) [Figs. 4 and 5] Figs. 4 and 5 show a second embodiment IA of the battery charging device of the present invention.

The difference between this second embodiment IA and the first embodiment 1 is the reference voltage resistor 15 and the control section 14.
It has a search section and a voltage detection table which will be described later. Therefore, only the different parts will be explained, and the same parts will be explained in the first part.
The explanation will be omitted by assigning the same reference numerals as those in Example 1.

(a, Circuit) [Figure 4] The second embodiment IA controls charging by changing the duty cycle of the charging pulse in multiple stages according to the terminal voltage of the battery 9.

14c is a search unit of the control unit 14, which together with the timing control unit 14b constitutes the control unit 14;
A digital signal from the D conversion circuit 13 is input.

Reference numeral 17 denotes a voltage detection table in which command signals are written in correspondence with predetermined addresses.
Connected to 4c.

When the digital signal F is input from the sample and hold circuit 12 through the A/D conversion circuit 13, the search unit 14c accesses the voltage detection table 17 and uses the address corresponding to the digital signal. The specified designation signal is read out, and this command signal is further sent to the timing control section 14b of the control section 14.

Then, in response to this command signal, the timing control section 14b
A 4-bit binary signal is sent to the timing circuit 11, and in response to this, the timing circuit 11 can control the duty cycle of the charging pulse in 2'=16 stages.

Of course, in order to make this control more precise, the number of bits described above may be increased.

(b, Timing Chart) [FIG. 5] The circuit operation of the second embodiment IA of the battery charging device of the present invention will be described below with reference to the timing chart shown in FIG.

Note that the signal B is controlled to have a duty cycle of 16 stages, and for example, a charging pulse signal having a duty cycle of 20% to 80% equally divided into 4% intervals is used.

Further, the signal G is composed of a 4-bit timing signal.

Immediately after the start of charging, the level of signal F is D (V), and the level of signal G is G1, G2, G8, G
4 are signals in the digits of 2° 21, 22, and 23, respectively, are in the state of hexadecimal code "0", and signal B is a charging pulse signal with a duty cycle of 20%. Then, as the level of signal F gradually increases, signal G
are in a state corresponding to "1", "2", ..., "E", "F", and furthermore, the duty cycle of the charging pulse signal shown in signal B is also 24%, 28%, ..., 76%, 8
The charge to the secondary battery 9 is increased stepwise to 0%.

After that, the duty cycle is 80 until the end of charging.
% pulse charging will continue.

(c. Characteristics) [Figure 3 In Figure 3, the charging curve according to the second embodiment IA is shown by a solid line 18.

The charging curve 18 in the second embodiment IA is represented by a slope of - since the duty cycle of the charging pulse signal is controlled in stages from the start of charging to the completion of charging.

(G. Effects of the Invention) As is clear from the above description, the battery charging device according to the invention includes a - power line and a switching means inserted between the power line and the secondary battery. , a battery charging device having a voltage detection means for detecting a terminal voltage of a secondary battery, and a timing control means for controlling a switching means according to a terminal voltage of the secondary battery detected by the voltage detection means, the timing control means; outputs a pulse signal, operates the switching means, and supplies power to the secondary battery using the charging pulse signal. The duty cycle of the pulse signal output from the timing control means is made to vary according to the terminal voltage of the secondary battery detected by the voltage detection means until the voltage increases to a level that does not cause malfunction of the control unit. It is characterized by having been.

Therefore, according to the battery charging device of the present invention, since the secondary battery is charged by the charging pulse signal and the duty cycle of this charging pulse signal is controlled according to the terminal voltage of the secondary battery, the power supply to the control unit is also possible. In particular, in the early stages of charging, sufficient power can be supplied to the control unit to prevent malfunctions, and since the power line is connected to the secondary battery without going through an element that causes a voltage drop, the charging time can be shortened.

[Brief explanation of the drawing]

Fig. 1 and Fig. 2 show an example of implementation of the battery charging device of the present invention, Fig. 1 is a circuit diagram, Fig. 2 is a time chart, and Fig. 3 is a charging curve in each embodiment and a conventional example. FIGS. 4 and 5 show a second embodiment of the battery charging device of the present invention. FIG. 4 is a circuit diagram, FIG. 5 is a time chart, and FIG. 6 is a conventional battery charging device. FIG. 3 is a circuit diagram of the battery charging device of FIG. Explanation of symbols 5...Power supply line, 8...Switching means, 9...Secondary battery, 11...Timing control means, 12...Voltage detection means 5--Plug------- −−−−±1 Akebonojiyu. 2nd position charging curve diagram Fig. 6 G4 ------1 time chart diagram Fig. 5

Claims (1)

[Claims] A power supply line, a switching means interposed between the power supply line and the secondary battery, a voltage detection means for detecting the terminal voltage of the secondary battery, and a voltage detection means comprising: In a battery charging device having timing control means for controlling the switching means according to the detected terminal voltage of the secondary battery, the timing control means outputs a pulse signal, operates the switching means, and controls power supply to the secondary battery. This is done using a charging pulse signal, and at least the terminal voltage of the secondary battery rises to a level that will not cause malfunction of other control parts even if the terminal voltage of the secondary battery is continuously supplied with power from the power supply line. A battery charging device characterized in that the duty cycle of the output pulse signal is varied according to the terminal voltage of the secondary battery detected by the voltage detection means.