JPS6369435A - Charging control circuit - Google Patents

Abstract

(57) [Abstract] 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 for a rechargeable vacuum cleaner or the like used in general households.

(Prior Art) Conventionally, this type of charging control circuit has generally had the configuration shown in FIG. The conventional technology will be explained below based on the drawings.

In the figure, it is assumed that terminals (1) and (2) are connected to a charging adapter, and a pulsating current obtained by full-wave rectification of an AC power source is applied to the terminals (1) and (2). Here, a main thyristor (01) and a battery (02) are connected in series between terminals (I) and (2). The diode (03) is an element for preventing reverse discharge of the battery (02), and is inserted between the anode of the battery (02) and the cathode of the main thyristor (01).

In addition, the diode (04) and capacitor (05) smooth the full-wave rectified current, and the second thyristor (06) connects the gate terminal of the main thyristor (01), which should maintain the on state when turned on. is connected to a gate resistor (07), and a gate sensitivity adjustment resistor (08) is connected between the gate and the cathode.

Cathode end of main thyristor (01) - FCA point) and GN
A Zener diode (09) and a resistor (0
10) are connected in series, and the Zener diode (θB)
There is a resistor (010) at the connection point between the anode terminal of
One end of the thyristor (θth) is connected, and the other end is connected to the second thyristor (0
6) is connected to the gate terminal. Further, resistors (012) (013) and a light emitting diode (014) are connected in series to both ends of the smoothing capacitor (05).

Further, the anode terminal of the diode (015) is connected to the connection point with the resistors (012) and (013), and the cathode terminal at the other end is connected to the anode terminal of the second thyristor (06). Furthermore, a resistor (OIG) is connected between the anode and cathode of the main thyristor (01).

In the above circuit configuration, the gate current flows into the gate terminal of the main thyristor (old) from the DC power supply through the gate resistor (07), so it is in the on state and passes through the JE thyristor (Ofi) and the diode (03) to the battery ( 02)
Charging current flows into and sustains charging. At this time, the light emitting diode (014) fishes because current flows through the resistors (012) and (013). On the other hand, the diode (
The old 5) is in a reverse bias state and is cut off.

In this way, when battery (02) continues to be charged, battery (02)
) gradually increases to 1', 5ii', approaches the set potential (charging completion voltage), and the Zener diode (09) enters the stable region.
), and the voltage between the terminals of the resistor (OXO) increases by -L. When this terminal voltage reaches the gate trigger voltage of the second thyristor (06), the resistor (
The gate current flows through the second thyristor (
θB) is turned on. When the second thyristor (OG) turns on in this way, the gate potential of the main thyristor (OP) is pulled lower than the cathode potential, so the main thyristor (OI) turns off and stops charging. The diode (014) is also connected to the second thyristor (O
When G) is turned on, the diode (015) becomes conductive, so the light goes out. 7I: Even if the thyristor (old) is turned off, a weak current flows through the battery through the resistor (old 6) to perform supplementary charging.

Figure 4 shows the charging characteristics of the above circuit.
The voltage between the terminals of 2) increases with time, and when it reaches the set potential of the Zener diode (09), the main thyristor (Ol) turns off, and when charging is completed, You can see how the current is cut. however,
Since supplementary charging by the resistor (01G) is continued, the battery (
The voltage across the terminals of θ2) rises again.

(Problem to be solved by the invention) However, if the battery is left connected to a load (such as an electric blower) for a long time during use, the internal resistance of the battery (02) increases and If left unused for ~3 months, the internal resistance will reach several hundred ohms. If you try to charge such an over-discharged battery with a conventional charging circuit that has two batteries, problems will occur. This situation is shown in FIG.

When the battery (02) with increased internal resistance as described above is connected to the charging circuit, the resistance value of the internal resistance is large, so when the charging current (I) flows, it appears that the electric current '1t! 1(
02), the voltage between the terminals is high, and as shown in FIG. 5, charging is stopped immediately after starting charging.

This is because the charging control circuit shown in FIG. 3 detects the potential at point A. As described above, over-discharged batteries cannot be charged using conventional charging circuits, causing great dissatisfaction among users. Also, although battery over-discharge does not easily occur during normal use, if it does occur,
The batteries had to be replaced, which was problematic from an economic point of view.

As described above, the conventional charging control circuit has the problem of not being able to charge an over-discharged battery.

The present invention aims to eliminate these conventional drawbacks and provide a charging control circuit that can charge even over-discharged batteries.

(Means for Solving the Problem) In order to solve this problem, the present invention connects a voltage transformer, a rectifier, a main current control element, and a rechargeable battery in series. The voltage across the terminals of the battery is input to a comparator, and the output of this comparator is connected to the drive side of the main current control element in 1]11 through a switching circuit that turns on and off the output.The operation of this switching circuit is controlled by the power supply. The switching circuit is delayed by giving a time lag from the time it is turned on, and is further provided with a timer circuit on the input side of the switching circuit.

(Function) With the configuration shown in L, the main current control element operates (turns on) a little later than when the power is turned on, and by detecting the voltage of the battery in the open state, it is possible to detect the voltage of the battery in the over-discharged state. In this case, it can be determined because the voltage in the open state is much lower than that of a normal battery, and in that case, normal charging can be performed by forcing charging under timer control until the internal resistance recovers. will be possible.

(Example) An example of the present invention will be described below in detail based on the accompanying drawings.

FIG. 1 is a circuit diagram showing a charging control circuit for a rechargeable vacuum cleaner or the like according to the present invention.

In the figure, (11) is a transformer whose negative side is connected to AClooV, (+2) is a rectifier for converting the secondary output of transformer (11) to DC, and (+3) is a transistor for main current control during charging. , (14) are rechargeable batteries such as small sealed lead-acid batteries, and when the main current side control transistor (13) is turned on, the voltage is stepped down by the transformer (11) and converted to DC by the rectifier "?A (12). The converted current flows to the battery (14), and the battery (14) is charged.The magnitude of the current during charging depends on the voltage and internal resistance of the battery (I4), and the transformer. It is determined by the impedance of (II).

Further, (15) is a detection circuit, (+6) is a drive transistor, (17) is a light emitting diode, (18) is a thyristor, and the C terminal of the detection circuit (+5) is a battery (I
4) voltage is input, and the b terminal is connected to the transistor (
The C terminal is connected to the gate terminal of the thyristor (18), the C terminal is on the ground side and is common to the θ side of the battery (14), and the C terminal is connected to the base terminal of the thyristor (18). When IG) is turned on, the base current flows to the main current control transistor (13) through the current limiting resistor (+9) and the light emitting diode (17), and the transistor (13) is turned on. On the other hand, the base current is supplied to the drive transistor (If;) through the resistor (20), and when the SIRISK (+8) is off, the current that has passed through the resistor (20) flows to the base of the transistor (+6). However, when the thyristor (18) turns on, the resistance (
The current passing through 20) flows into the thyristor (18) and turns off the drive transistor (16).

Further, (2) is a capacitor for providing a delay so that the drive transistor (16) operates after the power is turned on, and its time constant is determined by the resistor (2o) and the constant of the capacitor (2).

Note that the resistor (22) is the main current control transistor (+3
), and the light emitting diode (17) is connected to the main current control transistor (13).
) is on and the battery (I4) is charged, it also raises the level of the emitter of the drive transistor (1B) and activates the thyristor (
18) also has the role of stabilizing the off state of the drive transistor (IB) when it is turned on.

FIG. 2 shows details of the detection circuit (15) described above, and each end γ· of a to d corresponds to that in FIG. 1, respectively.

In the figure, (23) is a comparator, (24) is a battery for applying a reference voltage, (25) is a switching circuit, (2G) is a transistor, (27) is an AND circuit, and the comparator (
One of the inputs in 23) is connected to the battery (14) as the C terminal.
The other side is connected to the reference voltage from the battery (24), and the output of this comparator (23) is passed through the switching circuit (25) and connected to the thyristor (18) as the C terminal.
connected to the gate terminal of

Further, the transistor (26) is driven by receiving a signal input to the b terminal, and the AND circuit (27) has one side connected to the output of the comparator (23) and the other side connected to the transistor (2B). , its output is connected to a control terminal of a switching circuit (25) via a timer circuit (28).

To explain the operation using the above configuration, after turning on the power α,
Due to the time constants of the resistor (20) and capacitor (21),
The drive transistor (16) is off, so the power is off! No current flows through (14). If the battery (14) is in an overdischarged state at that time, its voltage exhibits an extremely low value compared to a normal battery. Then, the voltage at this time is detected and compared with the normal voltage (24) by the comparator (23), and it is determined that the battery (14) is over-discharged, and the voltage is sent to the ANI) circuit (27). input. This is the state before the third transistor (2B) is turned on, that is, the state immediately after the power is turned on.
By the function of the ND) circuit (27), the timer circuit (28
) is activated, and the switching circuit (25) is kept open during the timer setting time, so the cyrisk (I8) connected to the C terminal is kept off, and the battery (I4) is connected to the voltage. It is forced to charge without any charge. By this charging, the internal resistance (14) is restored and the internal resistance is lowered, and from then on, it can be charged like a normal battery, that is, the internal resistance of the battery (I4) is lowered as described above, and the battery (I4) is restored to its normal state. After that, the main current control transistor (I3) remains on and charging continues, thereby increasing the voltage of the battery (I4) to 1-9? , L, when the charging completion voltage is reached, the comparison n (23) works again to turn on the output of the switching circuit (25). Accordingly, the thyristor (18) becomes conductive, turning off the transistor (1G), and turning off the main current control transistor (I3) to cut the charging current.

As described above, by detecting the voltage in the open state before charging current is applied to an over-discharged battery, determining the over-discharge state, and performing forced charging, the battery can be forcibly charged without any special operation. The battery can be recovered and charged normally.

(Effects of the Invention) As described above, according to the present invention, when charging a discharged battery, over-discharge can be determined based on the voltage in the open state before charging, and the battery can be recovered by performing forced charging. So,
The effects of improved usability and reliability of the equipment can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a charging control circuit according to an embodiment of the present invention, FIG. 2 is a detailed circuit diagram of the same main part, FIG. 3 is a circuit diagram showing a conventional charging control circuit, and FIGS. The figure is a graph showing charging characteristics according to a conventional example. (11)...Transformer, (12)...Rectifier circuit, (
13)...Main current control transistor (current control element), (I4)...Battery, (23)...Comparator,
(25)...Switching circuit. %””' ＼ (Fig. 4 L @ Sakiyami (H) Fig. 5 Photoelectric terminal tin (H)

Claims (1)

[Claims] Switching that connects a voltage drop transformer, rectifier, main current control element, and rechargeable battery in series, inputs the terminal voltage of this battery to a comparator, and turns on and off the output of this comparator. A charging control circuit that is connected to the drive side of the main current control element through a circuit, delays the operation of the switching circuit by giving a time difference from power-on, and further includes a timer circuit on the input side of the switching circuit.