JPH0442778A - One-transistor type converter - Google Patents

Abstract

PURPOSE:To quicken the switching speed by connecting one end of resistance to the source of a first transistor, and connecting the base of a second transistor to the connection between this resistance and the source, and connecting the collector of a second transistor to the gate of a first transistor, and connecting a control circuit to the emitter of the second transistor. CONSTITUTION:When input DC power 1 is supplied, by the partial voltages of starting resistance 3, resistance 14, and resistance 15, a field effect transistor (FET) 13 is turned on, and a current flows through the resistance 15. And, when it reaches a certain value, the gate potential of the FET 13 is lowered through a transistor 16 and a control circuit 17, and the FET 13 is turned off, and the energy accumulated in a voltage converting transformer 9 is supplied to the load 12. Moreover, by the control circuit 17, the fluctuation of the output voltage is detected, and the transistor 16 is turned on or turned off, and the FET 13 is turned on or turned off, and the output voltage becomes stable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a self-excited converter of an old type.

[Conventional technology]

FIG. 8 is a circuit diagram showing a conventional single-stone converter.

In the figure, -1 is an input DC power supply, 2 is an input capacitor, 3 is a starting resistor, 37 is a clamp circuit consisting of a diode 4° resistor 5 and a capacitor 6, 9 is a voltage conversion transformer, 10 is a rectifier diode, and 11 is a smoothing capacitor,
12 is a load, 29 is a control resistor, 30 is a diode, 31
32 is a switching transistor, 38 is a current control circuit consisting of a resistor 15 and a transistor 16, and 39 is a resistor 33. Variable shunt regulator 34. Resistance 35, 36. This is a control circuit consisting of a diode 18 and a capacitor 19.

Next, the operation of this old-style converter will be explained.

When the input DC power source 1 is supplied, a base current flows to the switching transistor 32 through the starting resistor 3, and its operation is started. Switching transistor 32
When turned on, a voltage is applied to the primary winding N of the voltage conversion transformer 9, a voltage proportional to the winding ratio is induced in the control winding NR of the voltage conversion transformer 9, and is applied to the switching transistor 32 through the control resistor 29. supplies base current,
This switching transistor 320 is kept on,
Energy is stored in the voltage conversion transformer 9.

When the switching transistor 32 is saturated at a certain point, the switching transistor 32 is turned off.
A back electromotive force is generated between the base and emitter and the device turns off rapidly. As a result, the energy stored in the voltage conversion transformer 9 is transferred to the rectifier diode 10 and the smoothing capacitor 1.
1 to a load 12.

In the control circuit 39, the voltage conversion transformer 9 is controlled by
The output potential proportional to the turns ratio between m and the secondary winding N is
Diode 18 and capacitor 19 reduce resistance 35
and resistor 36 appear at both ends of the series connection circuit. and,
A voltage obtained by dividing the output potential appearing at both ends of this series connection circuit by a resistor 35 and a resistor 36 is applied to the switching transistor 3 via the variable shunt regulator 34.
It controls the base IT current of No. 2, turns on and off the switching transistor 32, and stabilizes the output voltage.

The current control circuit 38 uses the connection point potential between the resistor 15 and the emitter of the switching transistor 32 as a detection potential, turns on the transistor 16, and reduces the base current flowing through the switching transistor 32.

[Problem to be solved by the invention]

However, in such a conventional single-stone converter, since a bipolar transistor is used as the switching transistor 32, there is a limit to increasing the switching speed due to the storage time of the bipolar transistor, and it is difficult to increase the size of the converter. The problem was that I couldn't do it.

[Means to solve the problem]

The present invention has been devised to solve such problems, and involves connecting one end of a resistor to the source of the first transistor, and connecting the base of the second transistor to the connection point between this resistor and the source. The collector of the second transistor is connected to the gate of the first transistor, and the control circuit is connected to the emitter of the second transistor.

[Effect]

Therefore, according to the present invention, it is possible to increase the switching speed by using the first transistor as a field effect transistor.

〔Example〕

Hereinafter, the single-stone converter according to the present invention will be explained in detail.

FIG. 1 is a circuit diagram showing an embodiment of this single-stone converter, and a portion thereof is shown in a block diagram. In this figure, the same reference numerals as in FIG. 8 indicate the same or equivalent components, and the explanation thereof will be omitted.

This -Bandai converter differs from the one shown in FIG. 8 in that a field effect transistor 13 is used instead of the switching transistor 32. That is, one end of the resistor 15 is connected to the source of the field effect transistor 13, and the base of the transistor 16 is connected to the connection point between the source of the field effect transistor 13 and the resistor 15. The collector of the transistor 16 is connected to the gate of the field effect transistor 13, and a resistor 14 is connected between the gate and source of the field effect transistor 13.
On the other hand, a control circuit 17 is connected to the emitter of the transistor 16.

In the single-stone converter configured in this way, when input DC power source 1 is supplied, starting resistor 3 and resistor 1
4. At the divided voltage of the resistor 15, the field effect transistor 1
3 is turned on, and current flows through the field effect transistor 13 and the resistor 15 while storing energy in the voltage conversion transformer 9. When a certain current value is reached, a voltage is generated in the resistor 15 that turns on the transistor 16, and the gate potential of the field effect transistor 13 is lowered via the transistor 16 and the control circuit 17. Then, the field effect transistor 13 is turned off, and the energy stored in the voltage conversion transformer 9 is supplied to the load 12 via the rectifier diode 10 and the smoothing capacitor 11. Furthermore, the control circuit 17 detects fluctuations in the output potential and turns the transistor 16 on and off. Through the above series of operations, the field effect transistor 13 is turned on and off, and the output voltage is stabilized.

FIGS. 2 to 5 show an embodiment of the control circuit 17 shown in FIG.

In the control circuit 17 shown in FIG. 2, the transistor 21 is controlled via the variable shunt regulator 20 by a voltage obtained by dividing the output potential detected on the negative side by the resistor 23 and the resistor 24, and the transistor 16 is Turn it on and off to stabilize the output voltage. In this case, the transistor 21 and the resistor 22 also serve to turn on the transistor 16 at the initial stage.

In the control circuit 17 shown in FIG. 3, a variable shunt regulator 20 directly controls the output potential detected on the negative side by a voltage divided by a resistor 23 and a resistor 24, and turns the transistor 16 on and off. , to stabilize the output voltage. In this case, the resistor 22 also serves to turn on the transistor 16 initially.

In the control circuit 17 shown in FIG. 4, the insulating element 25 controls the transistor 21 based on the output potential detected on the secondary side, turns the transistor 16 on and off, and stabilizes the output voltage. In this case, the transistor 21 and the resistor 26 also serve to turn on the transistor 16 at the initial stage.

In the control circuit 17 shown in FIG. 5, the insulating element 25 directly turns on and off the transistor 16 based on the output potential detected on the secondary side, thereby stabilizing the output voltage. In this case, the resistor 26 also serves to turn on the transistor 6 at the initial stage.

Figure 6 shows that in the old type conharter shown in Figure 1,
A diode 27 is provided between the emitter of the transistor 16 and the other end of the resistor 15. By providing such a diode 27, the transistor 1 is initially
6 can be turned on more reliably. Note that the diode 27 may be a resistor 28, as shown in FIG.

〔Effect of the invention〕

As explained above, according to the single-stone converter according to the present invention, one end of the resistor is connected to the source of the first transistor, the heath of the second transistor is connected to the connection point between this resistor and the source, and the second transistor is connected to the source of the first transistor. Since the collector of the transistor is connected to the gate of the first transistor and the control circuit is connected to the emitter of the second transistor, it is possible to increase the switching speed by using the first transistor as a field effect transistor. It becomes possible to promote downsizing of the converter.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of an old type converter according to the present invention, FIGS. 2 to 5 are circuit diagrams showing an example of a control circuit of the older type converter shown in FIG. 1,
6 and 7 are diagrams showing modifications of the old converter shown in FIG. 1, and FIG. 8 is a circuit diagram showing a conventional single-stone converter. 9...Voltage conversion transformer, N,...-next winding, NR
...Control winding, N,...Secondary winding, 13...Field effect transistor, 15...Resistor, 16...Transistor, 17...Control wholesale circuit.

Claims (1)

[Claims] A single-stone converter that operates in self-excitation mode: a first transistor; a resistor whose one end is connected to the source of the first transistor; and a base connected to the connection point between the resistor and the source. A single-stone converter comprising: a second transistor having a collector connected to the gate of the first transistor; and a control circuit connected to the emitter of the second transistor.