JPH05344661A - Charger - Google Patents

Abstract

PURPOSE:To use low power control element and to reduce in size and cost an entire charger by rapidly controlling an oscillation of an inverter by a small current. CONSTITUTION:A capacitor 182 is charged by an output voltage from a feedback coil 60 during OFF period of an output transistor 54 of an inverter 30. When an oscillation of the inverter 30 is forcibly stopped, a charging voltage of a capacitor 182 is applied in a reverse bias state between a base and an emitter of the transistor 54 through a switching transistor 184.

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 a rechargeable battery such as a nickel-cadmium battery, and in particular, the oscillation operation of the inverter can be forcibly stopped in response to the input of a detection signal. Regarding what was said.

[0002]

2. Description of the Related Art Conventionally, a charging device of this type has been premised on that a secondary battery to be charged is fixed in the device or in a state close to the secondary battery. All of them are generally driven by a low voltage DC voltage output from an inverter circuit.

[0003]

However, in the case of the type in which the user arbitrarily inserts / removes the secondary battery to be charged, the secondary battery may be mishandled during operation of the inverter circuit. Nevertheless, a sufficient output voltage cannot be obtained, and the inverter circuit may be overloaded and damaged.

To solve this problem, it is conceivable to directly step down the high voltage DC voltage on the input side of the inverter circuit and use it for detection and control. However, in order to stop the inverter circuit, a relatively large current control is performed. Therefore, it is necessary to use a high power one for each element.
It was an obstacle to miniaturization and price reduction.

As a result of consideration made in view of the above-mentioned inconvenience, the inventor of the present invention has charged the capacitor with the voltage output from the feedback coil during the off period of the output transistor in the inverter circuit, and has the output voltage of this output transistor. It was found that the inverter circuit can be stopped quickly by controlling a small current by reversely biasing. The present invention has been made based on the above findings, and an object thereof is to provide a charging device in which a control element for low power consumption can be used, and the overall size and cost of the device can be reduced.

[0006]

In order to achieve the above object, in a charging device according to the present invention, a primary coil 56 is provided on the collector side of an output transistor 54 as shown in the basic configuration of FIG. The output transistor 54 is turned off from the inverter circuit section 30 including the feedback circuit 58 having the feedback coil 60 between the base end and the emitter end, and the secondary coil 86 wound on the same iron core as the primary coil 56. The charging unit 34 is capable of supplying a predetermined charging current to the secondary battery 16 during the period.

Further, a capacitor 182 which is connected in parallel with the feedback coil 60 and is charged by the output voltage of the feedback coil 60 during the off period of the output transistor 54.
And the base end of the output transistor 54 and the capacitor 18
The emitter / collector end is connected to one end of the output transistor 54 and is turned on in conjunction with the input of the detection signal 104, and the capacitor 1 is connected between the base and the emitter of the output transistor 54.
And a switching transistor 184 capable of applying a reverse bias voltage based on the charging voltage of 82.

[0008]

With the above configuration, the output transistor 54 of the inverter circuit section 30 normally repeats the on / off operation to interrupt the current flowing through the primary coil 56, and as a result, the output transistor 54 is turned off during the off period of FIG. As described above, the charging unit 34 charges the secondary battery 16, and at the same time, the capacitor 182 is charged by the output voltage of the feedback coil 60.

When the detection signal 104 is input to the switching transistor 184 when the terminal voltage of the secondary battery 16 during charging exceeds a set value, the transistor 184 is turned on. At this time, FIG. 2 (b)
As shown in, if the output transistor 54 of the inverter circuit unit 30 is in the ON period, the feedback coil 6 is in the OFF period.
As a result that the charging voltage of the capacitor 182, which is charged with the output voltage of 0, is applied between the emitter and the base of the output transistor 54 in the reverse bias state, the output transistor 54
Is turned off rapidly.

[0010]

As described above, the present invention precharges the capacitor 182 with the output voltage of the feedback coil 60 during the off period of the output transistor 54, and the inverter circuit section 30.
When it is necessary to stop the output transistor 54, the charging voltage of the capacitor 182 is applied in a reverse bias state between the base and the emitter of the output transistor 54 to forcibly turn off the output transistor 54.
The current value to be controlled by 4 is suppressed to a small value, each control element including the transistor 184 can be used with low power, and there is an advantage that the overall size and cost of the device can be reduced.

[0011]

EXAMPLES The charging device according to the present invention will be described below based on an example in which a gum type nicad battery is charged, but the charging device is not limited to this, and is used exclusively for charging various types of secondary batteries. It is needless to say that the same can be applied to the built-in devices or circuits built in various small electric devices.

In the charging device 10 according to the present invention, as shown in the overall structure of FIG. 3, the mounting portion 18 for the secondary battery 16 is recessed on the front surface 14 side of the main body case 12 formed in a substantially rectangular shape. At the same time, a light emitting diode 20 is arranged around it so that the charging time can be displayed. On the other hand, a plug blade 24 is provided on the back surface 22 side so as to be retractable from the main body case 12, and an electric circuit is housed inside.

The electric circuit housed in the main body case 12 is
As shown in FIG. 4, a rectifying unit 28 that full-wave rectifies the commercial AC voltage 26 input via the plug blade 24, and an inverter circuit unit 30 that converts the rectified high-voltage DC voltage into a low-frequency pulse signal. , Is driven by the output voltage of the inverter circuit unit 30 and the 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 it to the secondary battery 16. Secondary battery 1
The charge state detection unit 36 that outputs the detection signal 104 corresponding to the charge state of 6 and the detection signal 10 that is directly driven by the output voltage of the rectification unit 28 and that corresponds to the temperature inside the main body case 12.
The temperature detection unit 38 that outputs 4 and the inverter control unit 40 that forcibly stops the operation of the inverter circuit unit 30 in association with the input of the detection signal 104 are provided.

The commercial AC voltage 26 is input to the rectifying unit 28 via the temperature fuse 42, is full-wave rectified by the rectifying unit 28, and outputs a high-voltage DC voltage. As shown in FIGS. 3 and 5, the high voltage DC voltage is applied to the inverter circuit unit 30 via the normally open switch 44 that is turned on in response to the insertion timing of the secondary battery 16 into the mounting unit 18, and Applying to the inverter control unit 40 and the temperature detection unit 38 what has been converted into a predetermined low-voltage DC voltage by the step-down circuit 52 including the high resistance 46 for voltage drop, the constant voltage diode 48 for voltage stabilization, and the capacitor 50. As a result, regardless of the presence or absence of the output voltage from the inverter circuit section 30, both 40 and 38 can be operated reliably to control the inverter circuit section 30.

[0015]

[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 a series connection of a feedback coil 60, a capacitor 62, and a resistor 64. A high resistor 68 is further connected between the base end and the power supply line 66, and the primary coil 56 and the output transistor 54 are connected in parallel. The shock voltage absorption circuit 70 at the time of off is connected.

With this configuration, the output transistor 54
During the off period, when the capacitor 62 is completely discharged through the resistor 68, the base current starts to flow in the output transistor 54. Then, current also starts to flow in the primary coil 56, and a change in current in the primary coil 56 causes a feedback voltage in the feedback coil 60. This feedback voltage increases the base current of the output transistor 54 through the capacitor 62 and the resistor 64, and as a result, the output transistor 54 is turned on rapidly. Then, the magnitude of the current flowing through the primary coil 56 increases in a substantially linear manner, and a substantially constant feedback voltage is output from the feedback coil 60, and this voltage causes the constant voltage diode 72 connected to the base end of the output transistor 54 to be output. By driving and stabilizing the base voltage, the output transistor 54 maintains a stable ON state.

In this state, when the charging of the capacitor 62 proceeds with a predetermined time constant, the base current of the output transistor 54 decreases, and this decrease of the base current suppresses the increase of the current flowing through the primary coil 56, resulting in the feedback voltage. Decreases and its polarity is reversed. This feedback voltage reversal is
The output transistor 54 is abruptly 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 comprises an output current limiting circuit 74 and a feedback voltage limiting circuit 76 in addition to the basic circuit described above. In the output current limiting circuit 74, a resistor 78 is provided on the emitter side of the output transistor 54, and the transistor 80 can be turned on by the voltage across the resistor 78, so that the output transistor is connected between the emitter and collector of the transistor 80. Bypass 54 base current. That is, when the magnitude of the current flowing through the primary coil 56 exceeds the set value, the base-emitter of the output transistor 54 is forcibly short-circuited to be turned off, and the amount of current taken out when the transistor 54 is turned off is determined by the input voltage. Regardless of increase, it is limited to a substantially constant value.

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

[0020]

[Charging Unit] As shown in FIG. 6, 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. And a display circuit 92 that lights up according to the charging period of the secondary battery 16.
Composed of and.

The display circuit 92 is for energizing the light emitting diode 20 with the current output during the ON period of the output transistor 54 to display the charging timing, and is a negative electrode provided in the mounting portion 18 of the main body case 12. Two pin-shaped electrodes 94, which are arranged at a slight distance as shown in FIG.
a.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. is 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 with the negative electrode of the secondary battery 16, and the light emitting diode 20 is energized to display the charging time.

[0022]

[Charging state detection unit] The charging state detection unit 36 checks the terminal voltage during charging and a timer 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 sets the terminal voltage. An overvoltage detection circuit 100 that generates a signal when the value exceeds a 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 interlocked with the input of each signal described above. And a power supply circuit 108 that supplies a predetermined amount of power to the entire charging state detection unit 36.

The power supply circuit 108 includes an inverter circuit section 30.
Tertiary coil 1 wound in the same iron core shape as the primary coil 56 of
The current output from the transistor 10 during the off period of the output transistor 54 is selectively taken out from the diode 10 and stabilized by the capacitor 114 or the constant voltage diode 116.

The timer circuit 98 includes the inverter circuit section 3
A reset circuit 120 that generates a predetermined reset signal 118 when 0 is activated and a voltage is output from the power supply circuit 108.
Then, counting is started in conjunction with the input of the reset signal 118, and when the counting of a predetermined number is completed, the output terminal 121
Is turned off and outputs a signal.

The reset circuit 120 receives the output voltage from the power supply circuit 108 and the capacitor 124 to which the output voltage of the power supply circuit 108 that rises in conjunction with the start of the inverter circuit section 30 is applied, and the voltage is predetermined. A constant voltage diode 128 that energizes the capacitor 126 when the zener voltage is exceeded, and both ends of the capacitor 126 are connected between the base and the emitter. Short both ends of the counter 1
22 and a transistor 132 capable of applying the reset signal 118.

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

Here, the reference voltage is set to a value slightly lower than the peak value of the terminal voltage of the secondary battery 16 with the progress of charging, and the reference voltage and the detection voltage are compared.
At 46, when the detection voltage exceeds the reference voltage, a signal is sent to the detection signal generation circuit 106, so that overcharging and rechargeable battery 16 internal even before the timer circuit 98 times out, as will be described later. The open state of the battery or the charging state due to low temperature is detected, and the inverter circuit unit 30
To forcibly stop and end charging.

The capacitor 14 is connected in parallel with the resistor 144.
The connection of 8 prevents the terminal voltage from being disturbed due to the contact resistance when the rechargeable battery 16 is attached, thereby preventing an erroneous detection of an overvoltage state. The element 150 inserted in parallel with the resistors 142 and 144 is for discharging static electricity.

The present embodiment further includes a zero voltage detection circuit 102 that detects a short circuit state of the secondary battery 16 and forcibly stops the inverter circuit section 30.
That is, the output line from the power supply circuit 108 is connected to the resistor 1
It is connected to the positive electrode 138 of the charging circuit 90 via 52, 154 and 140 and the constant voltage diode 156, and is connected in parallel with the resistor 152 between the emitter and base of the transistor 158.

Therefore, 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 to start the inverter circuit section 30, and the power supply circuit 108 of the charging state detecting section 36 is operated. A predetermined drive voltage is output. However, if the secondary battery 16 is internally short-circuited, the potential of the positive electrode 138 of the charging circuit 90 becomes substantially zero, and the resistor 15 is connected via the constant voltage diode 156.
2 is energized, the transistor 158 is turned on, and a predetermined signal is sent to the detection signal generation circuit 106.

The detection signal generation circuit 106 outputs a signal from any one of the timer circuit 98, the overvoltage detection circuit 100 and the zero voltage detection circuit 102.
The detection signal 104 is sent to the inverter control unit 40 in a state of being electrically separated by using the photo coupler 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 described above 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 is turned on, and the power supply circuit 108 causes 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 included in the inverter control unit 40 shown in FIG.

[0033]

[Temperature Detecting Unit] The temperature detecting unit 38 divides the output voltage of the step-down circuit 52 by the resistors 170 and 172 to generate a reference voltage, while fixing the voltage inside the main body case 12 at a proper 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 detected voltage by the thermistor 174 and the resistor 176 to extract the detected voltage and comparing the reference voltage with the detected 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.

[0034]

[Inverter control unit] The present invention is characterized by the configuration of the inverter control unit 40, which is connected in parallel with the feedback coil 60 in the above-mentioned inverter circuit unit 30 and during the off period of the output transistor 54. A capacitor 182 charged via the diode 180,
The switching transistor 184 is turned on in synchronization with the input of the detection signal 104, and the lock circuit 186 that keeps the transistor 184 on.

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

Therefore, the charging state detecting section 36 described above is used.
When the detection signal 104 is sent from the phototransistor 168 to turn on the phototransistor 168 or the output end 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 184 to turn on the transistor 184. Then, the current flowing through the resistor 188 up to now flows through the switching transistor 184 in the ON state via the diode 194. Therefore, 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
Has its emitter end connected to a capacitor 182 and a diode 1
Between 80, the collector end is connected to the base end of the output transistor 54. Therefore, at the same time when the switching transistor 184 is turned on, the voltage stored in the capacitor during the off period of the output transistor 54 is applied between the base and emitter of the output transistor 54 via the switching transistor 184 in a reverse bias state. , 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, the minute current supplied through the high resistance 68 is applied to the diode 1
By grounding through 80 and the feedback coil 60, the base voltage of the output transistor 54 is maintained in a substantially zero state, and the stopped state of oscillation in the inverter circuit section 30 is maintained.

In this case, of course, if not only the inverter circuit section 30 is completely stopped but also a slight base voltage is left, the output transistor 54 oscillates weakly and a small amount of power is supplied to the secondary side for consumption. It is also possible to continue driving the charge state detection unit 36 with low power. Further, by doing so, it is possible to perform supplementary charging after the completion of charging of the secondary battery 16. The inverter circuit unit 30 may be a separately excited type that is driven by a separately provided oscillator.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram showing a basic configuration of the present invention.

FIG. 2 is an explanatory diagram showing an operation state of FIG.

FIG. 3 is an external perspective view showing an example in which the present invention is implemented.

FIG. 4 is a schematic diagram showing an overall configuration of a charging device according to the present invention.

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

FIG. 6 is an electric circuit diagram specifically showing a configuration of a charging unit and a charging state detecting unit in FIG.

[Explanation of symbols]

 10 Charging Device 12 Body Case 16 Secondary Battery 26 Commercial AC Voltage 30 Inverter Circuit Section 34 Charging Section 36 Charging State Detection Section 38 Temperature Detection Section 40 Inverter Control Section 54 Output Transistor 56 Primary Coil 60 Feedback Coil 86 Secondary Coil 98 Timer Circuit 100 Overvoltage Detection Circuit 102 Zero Voltage Detection Circuit 104 Detection Signal 106 Detection Signal Generation Circuit 160 Photocoupler 182 Capacitor 184 Switching Transistor

Claims (1)

[Claims] 1. An inverter circuit section (30) having a primary coil (56) on the collector side of an output transistor (54) and a feedback circuit (58) having a feedback coil (60) between a base end and an emitter end. ) And a secondary coil (86) wound on the same iron core as the primary coil (56), a predetermined charging current can be supplied to the secondary battery (16) during the off period of the output transistor (54). The charging unit (34) is connected in parallel with the feedback coil (60) described above, and the feedback coil (60) is provided during the off period of the output transistor (54).
(182) charged by the output voltage of the output transistor, the base end of the output transistor (54) and the capacitor (1
82) is connected to one end of the output transistor (54) and the emitter / collector end is connected to one end of the output transistor (54), and is turned on in conjunction with the input of a predetermined detection signal (104). A charging device including a switching transistor (184) capable of applying a reverse bias voltage based on a charging voltage.