JPH061956B2 - Charging circuit - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging circuit using an inverter circuit, and more particularly to a charging circuit capable of switching a charging rate or driving a load in parallel with charging.

(Prior Art) Normally, in a charging circuit that can also drive a load during charging, in order to perform normal charging even after energizing the load, it is necessary to increase the output of the charging circuit in conjunction with driving the load. There is.

In case of emergency, the charge rate for charging in a short time
For example, it is necessary to increase the output of the charging circuit in order to switch from the 8-hour rate to the 1-hour rate.

In such a case, in the inverter type charging circuit as shown in FIG. 4, the value of the resistor 50 is provided by inserting the resistor 50 in parallel with the discharging resistor 25 of the capacitor 24 inserted in the base circuit of the switching transistor 18. And the discharge time constant of the capacitor 24 when the transistor 18 is off to increase the oscillation frequency of the inverter circuit 15, the output from the inverter circuit 15 can be increased.

(Problems to be Solved by the Invention) However, in such a method, the inverter circuit 1
When the drive voltage of 5 changes, the discharge current amount of the capacitor 24 also changes, and as a result, the oscillation frequency of the inverter circuit 15 also changes, making it difficult to obtain a stable output.

The present invention has been made in view of the above problems, and makes it possible to increase the charging output when the charging rate is changed or when a load is driven, and a stable charging current for a rechargeable battery regardless of fluctuations in the circuit driving voltage. Can be supplied.

(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
By further connecting the secondary coil 26, which is wound on the same iron core as the primary coil 19, through the rectifying diode 27 to the output voltage of the secondary coil 26 to the rechargeable battery 16 provided as a load, The inverter circuit 15 is constructed almost in the same manner as the conventional one.

In such an inverter circuit 15, the present invention is provided with an output changing section 42 that constitutes a discharge path of the capacitor 24, and in conjunction with the switching operation of the switch 44, the inverter circuit 15
The output from is increased or decreased to enable simultaneous use of loads such as motors.

The output changing unit 42 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 electrode of the rechargeable battery 16 via the motor 41. As the switch 44, for example, a switch with 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.

(Operation) In the above configuration, when a full-wave rectified voltage is applied to the charging circuit, charging I ₁ to the capacitor 24 of the feedback section 21 is started via the resistor 25, as shown in FIG. The charging voltage of the capacitor 24 is the switching transistor 18
When the saturation voltage between the base and emitter is exceeded, 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 a voltage, and a reverse bias is applied to the base end of the transistor 18 to rapidly turn off the transistor 18.

Simultaneously with turning off, the rechargeable battery 16 is charged from the secondary coil 26 through the diode 27, and the high-value resistance 25
Through which the electric charge in the capacitor 24 is discharged with a substantially constant time constant irrespective of fluctuations in the power supply voltage, and the next charging cycle starts.

Next, as shown in FIG. 2 (c), the switch 44 is switched, and the feedback section 2 is placed between the base and emitter ends of the switching element 43.
Connect to both ends of 1. Then, at the same time that the transistor 18 is turned off, the switching element 43 is turned on, and both ends of the capacitor 24 are closed by a circuit passing from the rechargeable battery 16 to the motor 41. At this time, the armature coil of the motor, which is a load 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.
The discharge has proceeded, and the voltage across the capacitor 24 has changed to the rechargeable battery 16
When it becomes equal to the terminal voltage of, the discharge by the closed circuit ends, and thereafter, the discharge is made through the resistor 25, and the process proceeds to the next cycle. The discharge 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 to the rechargeable battery 16 increases, and as a result, the rechargeable battery is increased. The charge rate of 16 can be changed from, for example, 8 hour rate to 1 hour rate. Furthermore, since the discharge path at this time is a closed loop, a substantially constant pulse rate is maintained regardless of fluctuations in the power supply voltage, and a constant charging current is supplied to the rechargeable battery.

Here, as shown in FIG. 2D, when the switch 44 is further switched, the motor 41 is directly connected to both ends of the secondary coil 26 of the inverter circuit 15, and the output of the inverter circuit 15 enables the motor 41 to be driven simultaneously with charging. Become. At the same time, since the switching element 43 is turned on, both ends of the capacitor 24 are substantially directly connected by setting the value of the resistor 45 sufficiently small. The discharge time constant at this time is smaller than that through the load described above, and therefore the charge charged in the capacitor 24 rapidly self-discharges I ₅ through the switching element 43, and the off period of the switching transistor 18 is reduced. By further shortening and increasing the pulse rate of the voltage output from the secondary coil 26, the charging output is further increased, and charging and motor driving are possible at the same time.

Since the discharge from the capacitor 24 in this case is self-discharge, the amount of current is determined only by the time constant of the discharge path that returns from the feedback unit 21 through the switching element 43, and has a constant cycle even with variations in the circuit drive voltage. Hold it.

(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 includes the 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 provided at both ends of, and a feedback portion 21 is connected to the base side. The feedback unit 21 is composed of a feedback coil 22 wound on the same iron core as the primary coil 19, a resistor 23, and a capacitor 24 connected in series.
Is connected to the base and the emitter ends of the same, 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 unit 21 is charged through the resistor 25 and the base current flows to the switching transistor 18 at the same time as 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. But capacitor 2
As the charging of 4 proceeds, 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, so that the charging voltage of the capacitor 24 acts as a blocking voltage. 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 a secondary coil 26 wound on the same iron core as the primary coil 19 and a voltage connected to the secondary coil 26 and output to the secondary coil 26 when the switching transistor 18 is turned off. 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 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 detection unit 29 has an emitter current detection 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 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 3
Activate 0.

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 of 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 is made to flow 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 was gradually charged while being regulated by the relatively large time constant of the circuit that goes around the base side of the switching transistor 18 until then, is changed 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 charging path
Is applied in the forward direction, the charging of the capacitor 24 progresses rapidly, and as a result, the base current of the switching transistor 18 sharply decreases to immediately turn off the transistor 18 and the current flowing through the primary coil 19, that is, the transistor 18. During the ON period, 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, The average value of the charging current for the rechargeable battery 16 is kept 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.
The secondary coil voltage is detected by 7 and the current control unit 28 is delayed with a shorter time delay as the voltage value increases.
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 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 such a 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 a lapse of time regulated by the output voltage of the second transistor 34. 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, when the output voltage of the secondary coil 26, that is, the input voltage exceeds the set voltage regulated by the constant voltage diode 40 and the second transistor 34, the ON period of the switching transistor 18 increases as the input voltage becomes higher than the set voltage. By shortening and decreasing the peak current flowing through the primary coil 19, the increase in the average current due to the increase in the period exceeding the set voltage in one cycle period as the input voltage increases is corrected. 11
As a result, it is possible to maintain the average value of the charging current substantially constant regardless of the use in a 100V use area or a 240V use area.

The present invention is characterized in that, in addition to directly driving the motor 41 by the rechargeable battery 16, an output changing unit 42 is provided that enables a change in the charging rate of the rechargeable battery 16 and a load drive in parallel with charging. .

[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.

Therefore, when the switch 44 is turned on to supply power to the load 41 during charging of the rechargeable battery 16, the switching transistor 1
8, the transistor 43 is turned on at the same time as the start of the off period of 8, that is, the discharge of the capacitor 24, and the switch 44
The electric charge of the capacitor 24, which was discharged through the load with a relatively large time constant before turning 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, the pulse rate of the voltage output from the secondary coil 26 is increased, and the current capacity capable of supplying power to the rechargeable battery 16 and the load 41 is also increased.

Note that the output changing unit 42 is not limited to one in which the motor drive and the output are switched by one switch 44 as described above, and a switch may be separately provided to change the charging rate.

Further, a light emitting diode 46 is interposed in the discharge path passing through the transistor 43, and if the load 41 is used during charging of the rechargeable battery 16, the blinking cycle of the light emitting diode 46 is changed and the switch 44 is turned on. Is displayed.

As described above, by arranging the light emitting diode 46 in the discharge path, it can be recognized that the output changing unit 42 is operating, but the forward drop voltage of the light emitting diode 46 limits the control range. If you don't need this specifically. Further, instead of the interposition at this position, even when the secondary coil 26 is connected in parallel and in the opposite direction to the rectifying diode 27, it is turned on and it can be recognized that the load is in use.

(Advantages of the Invention) As described above, according to the present invention, when the rechargeable battery 16 is charged, the capacitor 2 of the feedback unit 21 has a relatively large time constant through the load.
4 is discharged, and if a high output is required, switch 44
By substantially directly connecting both ends of the capacitor 24 and discharging with a small time constant, the output can be increased or decreased as necessary. Further, in any of the above cases, the capacitor 24 is self-discharged, so that stable charging of the rechargeable battery and load driving can be performed regardless of fluctuations in the circuit driving voltage.

Further, when the rechargeable battery 16 directed in the direction opposite to the discharge current is interposed as a load provided in the discharge path of the capacitor 24, a voltage remains in the capacitor 24 during self-discharge, and the discharge time is further increased without impairing the stability. It has the advantage that it can be increased.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram of a charging circuit according to the present invention, and FIGS. 2 (a) to 2 (d) are explanatory diagrams showing an operating condition of the 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. FIG. 4 is an electric circuit diagram showing a conventional example. 15 ... Inverter circuit, 16 ... Rechargeable battery, 18 ... Switching transistor, 19 ... Primary coil, 21 ... Feedback section, 24 ... Capacitor, 41 ...・ Motor 42 ... Output changer 43 ... Switching element 44 ... Switch

Claims (1)

[Claims] 1. An inverter type charging circuit for controlling an output of a secondary coil (26) by controlling on / off of a current flowing through a primary coil (19) by a switching transistor (18), said transistor (18). A feedback coil (22) for supplying a base current to the base side of the capacitor and a capacitor (24) charged by the output of the feedback coil (24)
And a discharge path that is connected in parallel only when the capacitor (24) is discharged to change the discharge time constant of the capacitor (24), and the discharge path is a discharge that directly connects both ends of the capacitor (24). And a discharge path connecting both ends of the capacitor (24) via a load, and the time constant of the discharge path passing through the load is directly connected to the discharge path. A charging circuit that is set larger than the time constant of.