JP3289075B2 - Charging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter-type charging device capable of charging various secondary batteries such as a nickel-cadmium battery, and in particular, forcibly stops a charging operation upon detecting an abnormality in a charging state. About what you do.

[0002]

2. Description of the Related Art Conventionally, this type of charging device is based on the premise that a secondary battery to be charged is fixed in or close to the device, so that the control of the inverter circuit is exclusively performed by appropriate charging. It was common to consider only what could be done.

[0003]

However, in the case where the secondary battery to be charged is arbitrarily inserted / removed by a user, for example, the secondary battery is erroneously handled and the inside of the secondary battery is short-circuited. In such a case, the inverter circuit may be damaged due to an overload state.

As a result of studying the above problem, the present inventor detects a terminal voltage of the secondary battery during charging, and immediately stops the oscillation state of the inverter circuit when the voltage drops below a set value. Even if the temperature detection and the stop control of the inverter circuit are performed at a voltage independent of the output voltage from the inverter circuit, the stop control of the inverter circuit due to the abnormality detection of the state of charge is not properly performed. It has been found that the stop control of the inverter circuit can be reliably performed.

The present invention has been made based on the above findings, and it is an object of the present invention to provide a charging device that can be reliably stopped when an abnormality is found in a device regardless of handling of a secondary battery. I do.

[0006]

As shown schematically in FIG. 1, the charging device according to the present invention is configured such that a commercial AC voltage 2 is applied to a rechargeable battery 16 which is removably connected.
The inverter circuit unit 30 and the charging unit 34 that convert the high-voltage DC voltage obtained by rectifying 6 into a low-voltage DC voltage and can supply a predetermined charging current, and the charging state of the secondary battery 16 are checked. When the condition is detected, the charging state detection unit 36 that can output a predetermined detection signal 104 and the inverter circuit unit 30
And an inverter control unit 40 for forcibly stopping the oscillating operation.

When detecting that the terminal voltage of the secondary battery 16 has dropped to substantially zero, the charge state detection unit 36 outputs a detection signal 104 to the zero voltage detection circuit 10.
2 is provided.

When the temperature of the device exceeds a set value, a temperature detector 3 sends a detection signal 104 to an inverter controller 40.
8, and drives the above-described temperature detection unit 38 and the inverter control unit 40 with a voltage obtained by directly stepping down the high-voltage DC voltage.
Are driven by the output voltage from the inverter circuit unit 30, and are further charged by the charging state detection unit 36 to the inverter control unit 4.
0, the detection signal 10 is electrically isolated from each other.
It is preferable to send 4.

[0009]

According to the above configuration, when the normal secondary battery 16 is being charged, the inverter circuit section 30 and the charging section 34 operate, and the secondary battery 16 is charged by supplying a specified charging current. Is performed. Here, for example, when the secondary battery 16 whose inside is short-circuited is inserted, the zero voltage detection circuit 102 operates to stop the oscillation of the inverter circuit unit 30.

On the other hand, when the charging state detecting section 36 does not operate normally due to an abnormal overload state of the inverter circuit section 30, the temperatures of the secondary battery 16 and the inverter circuit section 30 rise. As a result, the temperature detection unit 38 performs the detection operation, and stops the oscillation of the inverter circuit unit 30.

[0011]

As described above, according to the present invention, the charging state detecting section 36 is provided with the zero voltage detecting circuit 102, and the oscillation of the inverter circuit section 30 is immediately performed when the insertion of the short-circuited secondary battery 16 is detected. Since the operation is stopped, it is possible to prevent the device from being damaged due to poor handling of the secondary battery 16.

Further, a temperature detecting section 38 for detecting a temperature rise of the whole apparatus by a driving voltage of the inverter circuit section 30;
Since the configuration is such that the inverter control unit 40 that performs the stop control of the inverter circuit unit 30 is driven, the safety of the entire apparatus can be further improved.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The charging apparatus according to the present invention will be described below based on an example in which a gum type NiCd battery is charged. However, the present invention is not limited to this. It goes without saying that the present invention can be carried out in substantially the same manner for a device built in or a circuit built in various small electric devices.

As shown in FIG. 2, the charging device 10 according to the present invention has a mounting portion 18 for a secondary battery 16 recessed on the front surface 14 side of a main body case 12 formed in a substantially rectangular shape. At the same time, a light emitting diode 20 is disposed around the light emitting diode 20 so that the charging time can be displayed. On the other hand, a plug blade 24 is provided on the back surface 22 so as to be able to protrude and retract from the main body case 12, and further contains an electric circuit therein.

The electric circuit housed in the main body case 12 is:
As shown in FIG. 1, a rectifying unit 28 for full-wave rectifying a commercial AC voltage 26 input through a plug blade 24, an inverter circuit unit 30 for converting the rectified high-voltage DC voltage into a low-frequency pulse signal, and A charging unit 34 that performs step-down rectification of the output signal of the inverter circuit unit 30 using the transformer 32 to form a predetermined low-voltage DC voltage and supplies the low-voltage DC voltage to the secondary battery 16, and is driven by the output voltage of the inverter circuit unit 30; Secondary battery 1
6 and a detection signal 10 corresponding to the temperature inside the main body case 12 which is directly driven by the output voltage of the rectification unit 28 and outputs a detection signal 104 corresponding to the state of charge
4 and a inverter control unit 40 for forcibly stopping the operation of the inverter circuit unit 30 in conjunction with the input of the detection signal 104.

The commercial AC voltage 26 is input to a rectifier 28 via a temperature fuse 42, and the rectifier 28 performs full-wave rectification to output a high-voltage DC voltage. As shown in FIGS. 2 and 3, the high-voltage DC voltage is applied to the inverter circuit unit 30 via a normally-open switch 44 that is turned on in accordance with the timing of inserting the secondary battery 16 into the mounting unit 18, and A voltage converted into a predetermined low-voltage DC voltage by a step-down circuit 52 including a high resistance 46 for voltage drop, a constant voltage diode 48 for voltage stabilization, and a capacitor 50 is applied to an inverter control unit 40 and a temperature detection unit 38. Thus, regardless of the presence or absence of the output voltage from the inverter circuit section 30, both 40 and 38 are reliably operated so that the inverter circuit section 30 can be controlled.

[0017]

[Inverter Circuit Section] The inverter circuit section 30 includes a primary coil 56 on the collector side of the output transistor 54 and a feedback circuit 58 on the base side. Feedback circuit 58
Is composed of a feedback coil 60, a capacitor 62 and a resistor 64 connected in series. Further, a high resistance 68 is connected between the base end and a power supply line 66, and the output transistor 54 is connected in parallel with the primary coil 56. The off-state impact voltage absorbing circuit 70 is connected.

With this configuration, the output transistor 54
When the discharging of the capacitor 62 through the resistor 68 is completed during the OFF period, the base current starts to flow to the output transistor 54. Then, a current starts to flow also in the primary coil 56, and a change in the current in the primary coil 56 generates a feedback voltage in the feedback coil 60. As a result of this feedback voltage increasing the base current of the output transistor 54 through the capacitor 62 and the resistor 64, the output transistor 54 turns on rapidly. Then, the magnitude of the current flowing through the primary coil 56 increases substantially linearly, and a substantially constant feedback voltage is output from the feedback coil 60. This voltage causes the constant voltage diode 72 connected to the base end of the output transistor 54 to output a constant voltage. By driving and stabilizing the base voltage, the output transistor 54 maintains a stable ON state.

In this state, as the charging of the capacitor 62 progresses with a predetermined time constant, the base current of the output transistor 54 decreases, and this decrease in the base current suppresses the increase in the current flowing through the primary coil 56. Is reduced and its polarity is reversed. This inversion of the feedback voltage is
The output transistor 54 is rapidly turned off by biasing the base and emitter of the output transistor 54 in the reverse direction.

The inverter circuit section 30 embodying the present invention further includes an output current limiting circuit 74 and a feedback voltage limiting circuit 76 in addition to the above basic circuits. The output current limiting circuit 74 includes a resistor 78 interposed on the emitter side of the output transistor 54, and further allows the transistor 80 to be turned on by the voltage between both ends of the resistor 78 so that the output transistor is connected between the emitter and collector of the transistor 80. The base current at 54 is bypassed. That is, when the magnitude of the current flowing through the primary coil 56 exceeds a set value, the base and the emitter of the output transistor 54 are forcibly short-circuited and turned off. Limit to almost constant regardless of increase.

On the other hand, the feedback voltage limiting circuit 76 is a constant voltage circuit having a control transistor 82 connected in parallel with the capacitor 62. When the magnitude of the feedback voltage exceeds a set value, the diode 83, the resistor 85 and the constant Voltage diode 8
4 and a collector current flowing through the control transistor 82, regardless of the increase of the feedback voltage.
The voltage value at the emitter terminal of the control transistor 82 is limited to a set value or less.

[0022]

[Charging Unit] As shown in FIG. 4, the charging unit 34 selectively supplies the current output from the secondary coil 86 to the secondary battery 16 by the diode 88 during the OFF period of the output transistor 54 of the inverter circuit unit 30. Circuit 90 for charging the secondary battery 16 and a display circuit 92 that lights up in response to the charging period of the secondary battery 16
It is composed of

The display circuit 92 supplies current to the light emitting diode 20 with the current output during the ON period of the output transistor 54 to display the charging time. The negative electrode electrode provided on the mounting portion 18 of the main body case 12 is provided. Two pin-shaped electrodes 94 are arranged at a distance from each other as shown in FIG.
a and 94b, one electrode 94a is connected to one terminal of the secondary coil 86, and the other electrode 94b is connected to the other terminal of the secondary coil 86 via the light emitting diode 20 and the current limiting resistor 96. are doing. Therefore, the secondary battery 1
Only when 6 is correctly inserted into the mounting portion 18, the two electrodes 94a and 94b are short-circuited by the negative electrode of the secondary battery 16, and the light emitting diode 20 is energized to display the charging time.

[0024]

[Charge State Detecting Unit] The charging state detecting unit 36 checks a terminal circuit 98 that generates a predetermined signal after a set time of, for example, about 15 minutes has elapsed from the start of charging, and a terminal voltage during charging. An overvoltage detection circuit 100 that generates a signal when the value exceeds the value, a zero voltage detection circuit 102 that generates a signal when the terminal voltage drops to approximately 0 volt, and a detection signal 104 that is generated in conjunction with the input of each signal described above. And a power supply circuit 108 for supplying predetermined power to the whole of the charged state detection unit 36.

The power supply circuit 108 includes the inverter circuit unit 30
Tertiary coil 1 wound on the same core as primary coil 56
10, the current output during the off period of the output transistor 54 is selectively extracted from the output transistor 54 via the diode 112 and is stabilized by the capacitor 114 or the constant voltage diode 116.

The timer circuit 98 includes the inverter circuit unit 3
0 generates a predetermined reset signal 118 when a voltage is output from the power supply circuit 108 upon activation of the reset circuit 120.
Counting starts in conjunction with the input of the reset signal 118, and when a predetermined number of counts are completed, the output terminal 121
And a counter 122 for outputting a signal when the signal is turned off.

The reset circuit 120 receives the output voltage of the power supply circuit 108 and the capacitor 124 to which the output voltage of the power supply circuit 108 which rises in conjunction with the start of the inverter circuit section 30 is applied. When the Zener voltage is exceeded, a constant voltage diode 128 is connected to the capacitor 126. Both ends of the capacitor 126 are connected between the base and the emitter. When the charging voltage exceeds the turn-on voltage, the capacitor 124 is connected between the collector and the emitter and the diode 130. Short both ends of counter 1
22 and a transistor 132 that can apply the reset signal 118 to the transistor 22.

In the overvoltage detection circuit 100, the power supply circuit 10
8 is divided by the resistors 134 and 136 to form a reference voltage. On the other hand, by dividing both ends of the positive electrode 138 and one negative electrode 94b of the charging circuit 90 by the resistors 140, 142, and 144, a detection voltage proportional to the terminal voltage of the secondary battery 16 during charging is obtained. .

Here, the reference voltage is set to a value slightly lower than the peak value of the terminal voltage of the secondary battery 16 as the charging progresses, and the reference voltage and the detected voltage are compared with the comparator 1.
When the detection voltage exceeds the reference voltage, a signal is sent to the detection signal generation circuit 106 so that, as described later, even before the timer circuit 98 times out, overcharging or internal charging of the secondary battery 16 can be performed. The open circuit state or the charge state due to low temperature is detected, and the inverter circuit 30
Forcibly to stop charging.

The capacitor 14 is connected in parallel with the resistor 144.
By connecting the secondary battery 8, it is possible to prevent the terminal voltage from being disturbed due to the contact resistance when the secondary battery 16 is mounted, thereby preventing the overvoltage state from being erroneously detected. The element 150 inserted in parallel with the resistors 142 and 144 is for discharging static electricity.

The present invention further includes a zero voltage detection circuit 102 for detecting a short-circuit state of the secondary battery 16 and forcibly stopping the inverter circuit section 30. That is, the output line from the power supply circuit 108 is connected to the resistor 15
It is connected to the positive electrode 138 of the charging circuit 90 via 2.154.140 and the constant voltage diode 156, and is connected between the emitter and base of the transistor 158 in parallel with the resistor 152.

Accordingly, when the secondary battery 16 is inserted into the charging section 34, the switch 44 provided on the output side of the rectifying section 28 is turned on, the inverter circuit section 30 is started, and the power supply circuit 108 of the charging state detecting section 36 A predetermined drive voltage is output. However, if the secondary battery 16 is short-circuited internally, the potential of the positive electrode 138 of the charging circuit 90 becomes substantially zero, and the resistor 15
2, the transistor 158 is turned on, and a predetermined signal is sent to the detection signal generation circuit 106.

When a signal is output from any one of the timer circuit 98, the overvoltage detection circuit 100, and the zero voltage detection circuit 102, the detection signal generation circuit 106
The detection signal 104 is transmitted to the inverter control unit 40 in a state where the detection signal 104 is electrically separated using the photocoupler 160.

That is, the collector of the transistor 164 is connected in series with the light emitting diode 162 of the photocoupler 160.
The emitter terminal is connected, and the output voltage of the power supply circuit 108 can be applied as a signal to the base terminal via the diode 166. Therefore, when a signal is applied to the base end of the transistor 164, the transistor 1
64 turns on, and the photocoupler 160
The light emitting diode 162 is energized to emit light, and the detection signal 104 is sent to the phototransistor 168 of the photocoupler 160 provided in the inverter control unit 40 shown in FIG.

[0035]

[Temperature Detector] The temperature detector 38 divides the output voltage of the step-down circuit 52 by the resistors 170 and 172 to generate a reference voltage, and fixes the output voltage inside the main body case 12 to an appropriate position such as the back side of the secondary battery 16. The temperature inside the main body case 12 of the charging device 10 exceeds the set value by dividing the detection voltage by the thermistor 174 and the resistor 176 to extract the detection voltage, and comparing the reference voltage and the detection voltage by the comparator 178. Then, the detection signal 104 whose signal level changes from “H” to “L” is sent to the inverter control unit 40 via the diode 179.

[0036]

[Inverter Control Unit] The inverter control unit 40 is connected in parallel with the feedback coil 60 in the inverter circuit unit 30 and is charged via the diode 180 during the off period of the output transistor 54;
The switching transistor 184 is turned on in conjunction with the input of the detection signal 104, and a lock circuit 186 maintains the on state of the transistor 184.

The lock circuit 186 includes resistors 188 and 190
And the phototransistor 168 connected in series, the output voltage of the step-down circuit 52 is applied,
And the emitter and base terminals of the transistor 192 are connected in parallel. Further, the collector end of the transistor 192 is connected to the base end of the switching transistor 184, and the diode 1 is connected between the resistor 190 and the phototransistor 168 and the collector end of the switching transistor 184.
94.

Therefore, the above-mentioned charge state detection unit 36
When the detection signal 104 is sent to the phototransistor 168 and the phototransistor 168 is turned on or the output terminal of the temperature detection unit 38 is grounded, a current flows through the resistor 188 to turn on the transistor 192, and the switching transistor A base voltage is applied to the transistor 184 to turn on the transistor 184. Then, the current that has been flowing through the resistor 188 up to now flows through the switching transistor 184 in the ON state via the diode 194, so that the ON state of the lock circuit 186 is fixed regardless of the duration of the detection signal 104. , The on state of the switching transistor 184 is maintained as it is.

Here, the switching transistor 184
Is connected to the capacitor 182 and the diode 1
The collector terminal is connected to the base terminal of the output transistor 54 between the terminals 80. Therefore, at the same time when the switching transistor 184 is turned on, the voltage stored in the capacitor 182 during the off period of the output transistor 54 is applied between the base and the emitter of the output transistor 54 via the switching transistor 184 in a reverse bias state. As a result, the output transistor 54 is rapidly turned off with almost no current flowing through the switching transistor 184.

After the output transistor 54 is turned off, a small current supplied through the high resistance 68 is applied to the diode 1
By grounding through the output coil 80 and the feedback coil 60, the base voltage of the output transistor 54 is maintained at approximately zero, and the oscillation stop state of the inverter circuit unit 30 is maintained.

Of course, in this case, if the inverter circuit section 30 is not only completely stopped, but also a slight base voltage is left, the output transistor 54 oscillates weakly, supplies small power to the secondary side, and consumes less power. It is also possible to continue to drive the charge state detection unit 36 with low power. In addition, in this way, it is possible to perform supplementary charging after the charging of the secondary battery 16 is completed. Note that the inverter circuit section 30 may be a separately excited type driven by an oscillator provided separately.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an overall configuration of a charging device according to the present invention.

FIG. 2 is an external perspective view showing an example in which the present invention is implemented.

FIG. 3 is an electric circuit diagram specifically showing configurations of an inverter circuit unit, an inverter control unit, and a temperature detection unit in FIG.

FIG. 4 is an electric circuit diagram specifically showing configurations of a charging unit and a charging state detecting unit in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Charging device 12 Main body case 16 Secondary battery 26 Commercial AC voltage 30 Inverter circuit part 34 Charging part 36 Charge state detection part 38 Temperature detection part 40 Inverter control part 54 Output transistor 56 Primary coil 98 Timer circuit 100 Overvoltage detection circuit 102 Zero voltage Detection circuit 104 Detection signal 106 Detection signal generation circuit 160 Photocoupler

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02J ^7/ 00-7/12 H02J ⁷ /34-7/36

Claims (2)

(57) [Claims] 1. A rechargeable battery (16) connected detachably.
High voltage DC voltage obtained by rectifying the commercial AC voltage (26)
Can be converted to a low-voltage DC voltage to supply a predetermined charging current.
Inverter circuit section (30) and charging section (34)
Check the state of charge of the secondary battery (16), and
When a termination condition is detected, a predetermined detection signal can be output.
In conjunction with the charging state detection unit (36) that performs the detection signal input,SaidInverter circuit (3
Inverter system for forcibly stopping the oscillation operation in 0)
A charging device comprising a control unit (40);Said To the charging state detection unit (36)There, Secondary battery (1
When it is detected that the terminal voltage of 6) has dropped to substantially zero,
Zero voltage detection circuit (102) capable of outputting a detection signal
When, When the temperature exceeds the set value, the detection signal is controlled by the inverter.
A temperature detection unit (38) to be sent to the unit (40); The temperature detector (38) and the inverter controller (4)
0) is driven by a voltage directly reduced from the high-voltage DC voltage.
While The charge state detection unit (36) includes an inverter circuit unit (3).
Drive by the output voltage from 0) Characterized by
Charging device. Wherein said charging state detection unit from (36) an inverter control section (40), the charging apparatus according to claim 1, wherein that feed a detection signal in a state of being electrically separated from each other.