JPH0630550B2 - Charging circuit - Google Patents

Description

The present invention relates to a charging circuit using an inverter circuit, and more particularly to a charging circuit for displaying a charging state.

(Prior Art) Conventionally, this kind of charge state display has been performed by, for example, displaying the light emitting diode by the output of an inverter circuit or providing a dedicated display circuit.

(Problems to be solved by the invention) However, all of them have many problems such as a large amount of power wasted and the structure becomes complicated when an appropriate display is made.

The present invention has been made in view of the above problems, and it is possible to appropriately display the output switching state and the like without requiring a special circuit for display, and to display a display element regardless of fluctuations in power supply voltage. It is an object of the present invention to provide a charging circuit in which damage can be prevented and stable display can be performed.

(Means for Solving Problems) That is, according to the present invention, as shown in FIG. 1, a primary coil 19 is provided on the collector side of a switching transistor 18, and a primary coil is provided between a base end and an emitter end. Feedback coil 22, resistor 2 wound on the same iron core as 19
Feedback unit 21 formed by connecting 3 and a capacitor 24 in series
Is connected, and the output voltage of the secondary coil 26 can be applied to the rechargeable battery 16 from the secondary coil 26 wound on the same iron core as the primary coil 19 through the rectifying diode 27. Inverter circuit 15 is configured.

In the inverter circuit 15 according to the present invention, the feedback coil 22 is provided during the ON period of the switching transistor 18.
A discharge path for discharging the capacitor 24 charged by the output of the transistor 18 during the off period of the transistor 18 is provided in parallel with the feedback section 21, and a display element 46 that is turned on by the discharge current is provided in the discharge path. It is characterized by that.

The discharge path is configured, for example, as a part of the output changing unit 42, and includes a switching element 43 such as a transistor and a switch 44 that switches the output from the inverter circuit 15. Switching element 43
Allows the base end and the collector end to be selectively connected to one end of the feedback unit 21 via the switch 44, and the emitter end to be connected to the other end of the feedback unit 21 via the resistor 45.
The collector end is connected to the negative pole of the charging place 16 via the load 14. As the switch 44, for example, a switch having one circuit and three contacts is used, and in cooperation with the switching operation, one end of the feedback unit 21 can be connected to the base end and the collector end of the switching element 43 from the open state.

Further, a display element 41 such as a light emitting diode is provided between the collector terminal of the switching element 43 and the load 41.

(Operation) In the above configuration, when a full-wave rectified voltage is applied to the charging circuit, as shown in FIG.
The charging I 1 of the capacitor 24 of ₁ is started. When the charging voltage of the capacitor 24 exceeds the base-emitter saturation voltage of the switching transistor 18, the transistor 18 is turned on as shown in FIG. 2 (b) in the same manner as in the conventional case, and the collector current I ₂ starts to flow.

After the switching transistor 18 is turned on, the base current I ₃ is maintained by the voltage output to the feedback coil 22, and the capacitor 24 is charged for a time regulated by the time constant of the base circuit, and then the capacitor 24 is charged. A reverse bias is applied to the base end of the switching transistor 18 by the voltage to rapidly turn off the transistor 18.

Simultaneously with turning off, the charging place 16 is charged from the secondary coil 26 through the diode 27 and the high-value resistor 25
Through which the electric charge in the capacitor 24 is discharged with a substantially constant time constant regardless of fluctuations in the power supply voltage, and the next charging cycle starts. In this case, the switching element 43 continues to be in the off state, the display element 46 is extinguished, indicating that the battery is being charged normally for 8 hours.

Next, as shown in FIG. 2 (c), the switch 44 is switched, and the feedback section 21 is connected between the base and emitter ends of the switching element 43.
Connect to both ends of. Then, the switching transistor 18
The switching element 43 is turned on at the same time as the turning off, and both ends of the capacitor 24 are closed by a circuit passing from the rechargeable battery 16 to the load 41. At this time, if a motor is used as the load 41, the armature coil of the motor interposed in the discharge path acts as a reactance, and the discharge current I ₄ flows from the capacitor 24 with a relatively large time constant. When the discharge progresses and the voltage across the capacitor 24 becomes equal to the terminal voltage of the rechargeable battery 16, the discharge by the closed circuit ends, and thereafter the resistance 2
Discharge through 5 and move to the next cycle. The discharging time constant of the capacitor 24 at this time is smaller than that in the case where the output changing unit 42 is not operated. Therefore, the pulse rate of the charging current from the secondary coil 26 increases, and as a result, the rechargeable battery 16 is charged. The rate can be changed from, for example, 8 hour rate to 1 hour rate. In this case, since the switching element 43 is turned on, the display element 46 interposed in the discharge path emits light due to the discharge current of the capacitor 24, indicating that rapid charging is in progress.

When the switch 44 is further switched as shown in FIG. 2 (d), the load 41 is directly connected to both ends of the secondary coil 26 of the inverter circuit 15, and the rechargeable battery 16 is charged by the output of the inverter circuit 15. At the same time, the load 41 can be driven. At the same time, the switching element 43 is turned on. Therefore, by setting the value of the resistor 45 to a sufficiently small value, the electric charge charged in the capacitor 24 is changed to the switching element 43.
Through the self-discharge I ₅ rapidly, the off period of the switching transistor 18 is further shortened and the pulse rate of the voltage output from the secondary coil 26 is increased, thereby further increasing the charge output and charging. Allows load driving at the same time.

In this case, the display element 46 emits light at a faster pulse rate than the above state, and indicates that the load 41 is being energized.

(Embodiment) As shown in FIG. 3, a commercial AC voltage 11 input through a power plug or the like is full-wave rectified by a rectifier circuit 12 having a diode bridge, and then noise disturbance to a power line is prevented. It is applied to the charging unit 14 through the filter circuit 13 that operates.

[Charging part]

The charging unit 14 includes an inverter circuit 15 that generates a pulse voltage having a frequency higher than that of the commercial AC voltage 11, and an output circuit 17 that applies the pulse voltage generated by the inverter circuit 15 to a rechargeable battery 16 to flow a charging current. Prepare

The inverter circuit 15 is a switching transistor 1
8, a primary coil 19 on the collector side, and the primary coil 19
A shock absorbing portion 20 that absorbs a shock voltage generated when the switching transistor 18 is turned off is interposed at both ends of, and a feedback portion 21 on the base side is connected. The feedback unit 21 is composed of a feedback coil 22, a resistor 23, and a capacitor 24, which are wound on the same iron core as the primary coil 19, and are connected in series.
Is connected to the base and emitter ends of each of the above, and the full-wave rectified voltage is further applied to the base end via the resistor 25.

Therefore, when the capacitor 24 of the feedback section 21 is charged through the resistor 25 and the base current flows to the switching transistor 18 at the same time when the voltage is applied to the inverter circuit 15, the transistor 18 shifts from the off state to the active state, and the collector current flows. Begins to flow. Such an increase in the collector current is fed back from the primary coil 19 to the feedback coil 22 in the direction of increasing the base voltage to further increase the base current, and as a result, the switching transistor 18 is rapidly turned on. After turning on, a substantially constant feedback voltage is output to the base end by the increase of the collector current flowing through the primary coil 19, the base current is maintained, and the switching transistor 18 is kept in the on state. However, as the charging of the capacitor 24 progresses, the base current decreases, and when the transistor 18 enters the active region again, the increase of the current flowing through the primary coil 19 stops and the feedback voltage decreases.
The charging voltage of the capacitor 24 acts as a blocking voltage, and the transistor 18 rapidly returns to the off state. Further, the energy stored in the primary coil 19 side when turned on flows as a charging current toward the rechargeable battery 16 of the output circuit 17 during the off period of the transistor 18.

The output circuit 17 selectively connects the secondary coil 26 wound on the same iron core as the primary coil 19 and the voltage output to the secondary coil 26 when the switching transistor 18 is turned off by being connected to the secondary coil 26. And a rechargeable battery 16 connected to the diode 27 and supplied with a pulsed charging current.

The average value of the charging current supplied to the rechargeable battery 16 is controlled by controlling the current value flowing through the primary coil 19 by the current control unit 28, regardless of variations in various constants of the transistor 18 or slight variations in the input voltage. Maintained constant.

[Current controller]

The current control unit 28 is turned on in cooperation with the emitter current detection unit 29 of the switching transistor 18 and the detection operation of the detection unit 29, and is a control that bypasses the current of the feedback unit 21 and regulates the ON period of the transistor 18. And part 30.

The current detecting unit 29 has an emitter current detecting resistor 31 inserted on the emitter side of the switching transistor 18 and the emitter and base ends of a first transistor 33 connected to both ends of the resistor 31 via a diode 32. If it is detected that the voltage across the current detection resistor 31 exceeds the set value and the current in the primary coil 19 reaches the set value, the first transistor 33 is turned on and the control unit 30
Operate.

The control unit 30 connects the collector end of the second transistor 34 and the base end of the switching transistor 18 via the diode 35, connects the emitter end to the connection point between the secondary coil 26 and the rectifying diode 27, and The end is connected to the collector end of the first transistor 33, and at the same time when the first transistor 33 is turned on, a base current flows from the emitter side of the switching transistor 18 to the second transistor 34 via the first transistor 33. Then, the transistor 34 is turned on. Then, the capacitor 24, which has been gradually charged while being regulated by the comparatively large time constant of the circuit that goes around the base side of the switching transistor 18 until then, changes to the diode 35,
Second transistor 34, secondary coil 26 and rechargeable battery 1
By forming a bypass path through 6, the time constant of the circuit including the capacitor 24 is substantially reduced, and
The output voltage of the secondary coil 26 and the rechargeable battery 16 in the discharge path
Is applied in the forward direction, the charging proceeds rapidly, and as a result, the base current of the switching transistor 18 sharply decreases and immediately turns off the transistor 18, so that the current flowing in the primary coil 19, that is, the ON period of the transistor 18 The energy stored in the primary coil 19 is kept constant and the charging current flowing into the rechargeable battery 16 is kept constant.

In addition to the control by detecting the current fluctuation, the control unit 30 operates in cooperation with the detection operation of the voltage control unit 36 described below even for a large fluctuation of the commercial AC voltage 11 of about 100 to 240V, Keep the average value of the charging current constant.

[Voltage controller]

The voltage control unit 36 utilizes the fact that the voltage induced in the secondary coil 26 of the output circuit 17 during the ON period of the switching transistor 18 is proportional to the input voltage.
7, the secondary coil voltage is detected, and as the voltage value increases, the current control unit 28 is delayed with a shorter time delay.
The control unit 30 is operated.

The voltage detection unit 37 connects the capacitor 38 to the base end of the second transistor 34 and the anode side of the rectifying diode 27, and also connects the resistor 39 and the constant voltage diode 4 to each other.
A series connection of 0s is connected to the base end of the second transistor 34 and the cathode side of the rectifying diode 27.

With this configuration, the sum of the voltage generated in the secondary coil 26 and the voltage of the rechargeable battery 16 at the same time when the switching transistor 18 is turned on is the breakover voltage of the constant voltage diode 40 and the base-emitter saturation voltage of the second transistor 34. When the sum is exceeded, current flows in a loop that goes around the secondary coil 26, the rechargeable battery 16, the constant voltage diode 40, the resistor 39, and the capacitor 38 to charge the capacitor 38, and the time constant of the loop and the secondary coil 26.
The second transistor 34 is turned on by the terminal voltage of the capacitor 38 after the lapse of the time regulated by the output voltage. Then, as in the case of the current control unit 28 described above, the control unit 30 bypasses the charging loop of the feedback unit 21 to accelerate the charging of the capacitor 24, thereby turning off the switching transistor 18. Therefore, the constant voltage diode 40
When the output voltage of the secondary coil 26, and thus the input voltage, exceeds the set voltage regulated by the second transistor 34, the ON period of the switching transistor 18 is shortened as the input voltage becomes higher than the set voltage, and the primary coil 19 increases. By reducing the peak current flowing in the input voltage, the increase in the average current due to the increase in the period exceeding the set voltage in one cycle as the input voltage increases is corrected. It makes it possible to maintain the average value of the charging current substantially constant regardless of the use in the 240V area.

The present invention is characterized in that the output from the secondary coil 26 can be changed and the changed state is displayed.

[Output change part]

The output changing unit 42 increases the oscillation frequency of the inverter circuit 15 by changing the discharge time constant of the capacitor 24 of the feedback unit 21, and consequently can increase the output of the output circuit 17.

That is, the base end of the transistor provided as the switching element 43 is connected to the connection point between the feedback unit 21 and the rechargeable battery 16, and the emitter end is connected via the resistor 45 to the feedback unit 2.
1 and the collector end is connected to the negative pole of the rechargeable battery 16 via a load 41 such as a motor. Further, a display element 46 is provided between the collector end of the switching element 43 and the load 41.
As a light emitting diode.

Therefore, when the switch 44 is turned on to supply power to the load 41 during charging of the rechargeable battery 16, a base current flows to the transistor 43 at the same time when the off period of the switching transistor 18 starts and the transistor 43 is turned on to turn on the switch 44. The charge of the capacitor 24, which was discharged through the load with a relatively large time constant before being turned on, is rapidly discharged from the switch 44 through the transistor 43. As a result, the off period of the switching transistor 18 is shortened and the secondary The pulse rate of the voltage output to the coil 26 increases, and the current capacity capable of supplying power to the rechargeable battery 16 and the load 41 also increases.

At the same time, the blinking cycle of the display element 46 is changed to indicate that the output is switched.

The position where the display element 46 is interposed is not limited to the common path as described above, and can be appropriately changed as long as it is in the discharge path of the capacitor 24, such as between the switch 44 and the load 41. In this case, the same display as described above is performed depending on whether or not the display element 46 is lit.

(Effects of the Invention) As described above, the present invention provides the discharge path in parallel with the capacitor 24 of the inverter circuit 15, and the display element 46 is provided in the discharge path to display the output change state of the charging circuit. As a result, the display element 46 is prevented from being damaged due to an overvoltage because a substantially constant voltage is applied to the display element 46 in spite of fluctuations in the power supply voltage.

Further, it does not require a dedicated power source for driving the display element 46,
The structure is simple and there is no unnecessary power consumption. Further, there is an advantage that an appropriate display can be performed such that the blinking cycle of the display element 46 is changed corresponding to the changeover and switching of the output.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram of a charging circuit according to the present invention, and FIG.
(a) thru | or (d) are explanatory drawings which show the operating condition of a circuit. FIG. 3 is an electric circuit diagram showing an example in which the present invention is applied to a small electric device capable of simultaneously charging and driving a load. Reference numeral 15 ... Inverter circuit, 18 ... Switching transistor, 19 ... Primary coil, 24 ... Capacitor, 26 ... Secondary coil, 42 ... Output changing section, 46 ... Display element.

Claims (1)

[Claims] 1. A self-excited inverter circuit (15) for controlling an output from a secondary coil (26) by controlling on / off of a current flowing through a primary coil (19) by a switching transistor (18), and the inverter circuit. Discharge for discharging the capacitor (24) connected in parallel with the feedback section (21) of (15) and charged by the output of the feedback coil (22) during the ON period of the switching transistor (18) during the OFF period. And a discharge changing section (42) for changing the discharge time constant of the capacitor (24) in association with the switching operation of the switch (44) in the discharge path, and in the discharge path, Display element (4
6) A charging circuit having the interposition.