JPH0510555Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a ringing chain converter for boosting or stepping down a DC voltage.

(Prior Art) FIG. 2 shows an example of a basic circuit of a ringing chain converter. In FIG. 2, a transformer 1 has a main winding 1a and a feedback winding 1b on its primary side, and an output winding 1a on its secondary side. The main winding 1a is the collector of the switching transistor 2 (npn type).
It is connected to both ends of the DC power supply 3 via the emitters. Further, the feedback winding 1b is connected between the base and emitter of the transistor 2 via a capacitor 4 and a resistor 5, and is provided so as to apply positive feedback to the transistor 2 by its induced voltage. Further, a rectifying diode 6 and a smoothing capacitor 7 of the polarity shown are connected to both ends of the output winding 1c, and a load (not shown) is connected to both ends of the capacitor 7. Note that 8 is a resistor connected between the base of the transistor 2 and the positive terminal of the DC power supply 3.

The ringing chain converter configured in this way operates as described below. That is, if the base current IB starts to flow through the transistor 2 which is now in the OFF state, the collector current IC of the transistor 2 that flows thereby induces an electromotive force e1 in the direction of the arrow in the main winding 1a. Accordingly, an electromotive force e2 in the direction of the arrow is also induced in the feedback winding 1b. Since this electromotive force e2 acts to increase the base current IB of the transistor 2 and positive feedback is applied, the collector current IC further increases and the transistor 2 becomes saturated. At this time, the collector current 1 is applied to the main winding 1a.
When C flows, an electromotive force e3 is induced in the output winding 1c in the direction of the arrow, but no current flows through the capacitor 7 because the diode 6 is reverse biased. Therefore, since the load on the transistor 2 is only the inductance of the transformer 1, the collector current IC increases linearly as shown in FIG. 3b. Such an increase may be due to insufficient base current IB after transistor 2 is saturated, or
If the DC current amplification factor h _FE becomes insufficient, it is stopped in a short time, and the electromotive forces e1 and e2 become zero accordingly. In this case, the capacitor 5 is charged by the electromotive force e2 while the base current IB flows through the transistor 2, and the terminal voltage Vc (the direction of which is indicated by the arrow) is at a negative level, so as described above, As the electromotive forces e1 and e2 become zero, the transistor 2 is rapidly turned off. At this time, if the on time of transistor 2 is Ton, the inductance of transformer 1 is L, and the terminal voltage of DC power supply 3, that is, the input voltage is Ein, then the collector current of transistor 2 is
The peak value IP of IC and the energy E stored in the transformer 1 are as follows: IP=Ein·Ton/LE E=L·IP ² /2. Then, when the transistor 2 is turned off, an electromotive force e'3 in the direction of the arrow is induced in the output winding 1c, and a forward voltage is applied to the diode 6. A current corresponding to the current is supplied to the load. At this time, the terminal voltage of capacitor 7, that is, the output voltage,
Eout, the number of turns of the main winding 1a is _n1 , and the number of turns of the output winding 1c is _n2 , the time Toff during which current is supplied to the load is Toff=( _n2 / _n1 )L・IP/Eout.

The load current IL supplied in this way gradually decreases as shown in Figure 3c.
When the supply of the load current IL is stopped, the base current starts flowing to the transistor 2 due to the back electromotive force appearing in the feedback winding 1b, and in response, the transistor 2 is turned on in the same manner as described above. It is. By repeating such on and off of transistor 2, transformer 1
The operation in which the energy E stored in the primary side of the circuit is released to the secondary side is repeated, and accordingly, an output voltage Eout having a different level from the input voltage Ein can be obtained. Furthermore, in Figure 3,
Collector current IC and load current of transistor 2
In addition to IL, the state of change in the collector-emitter voltage V _CE of transistor 2 is also shown.

The basic structure and operation of the ringing chain converter are as described above, but in reality, the third
In the circuit configuration shown in the figure, it is unavoidable that the output voltage Eout changes greatly depending on the input voltage Ein and the size of the load, so a constant voltage function as shown in Figure 4 is generally added. Ru. That is, the fourth
In the figure, a series circuit of a capacitor 9 and a diode 10 with the polarity shown is connected to both ends of the feedback winding 1b, and a constant voltage diode 11 with the polarity shown is connected between the anode of the diode 10 and the base of the transistor 2. is connected. As a result, when the transistor 2 is turned off, the electromotive force e'2 induced in the feedback winding 1b in the direction of the arrow is applied to the capacitor 9 via the diode 10. At this time, the electromotive force e′2 is equal to the electromotive force e′3 of the output winding (that is, the output voltage Eout),
It is uniquely determined by the turns ratio of the feedback winding 1b and the output winding 1c, and therefore the terminal voltage V'c of the capacitor 10 is proportional to the output voltage Eout. Then, when the output voltage Eout rises and the terminal voltage V'c of the capacitor 9 exceeds the Zener voltage of the voltage regulator diode 11 and breaks over, when the transistor 2 is turned on afterwards, The base current IB supplied to the transistor 2 is bypassed by the constant voltage diode 11 and is reduced. As a result, the collector current of transistor 2 is
Transistor 2 is turned off before the IC rises sufficiently, and the energy E stored in transformer 1 decreases, causing the output voltage Eout to drop. The output voltage Eout is maintained at a constant voltage.

(Problem to be solved by the invention) When the output voltage Eout is made constant as described above, the level of the output voltage Eout is determined by the turns ratio between the feedback winding 1b and the output winding 1c, and This corresponds to the Zener voltage of the constant voltage diode 11. However, in reality, the inductance L of the transformer 1 is involved in the transfer of energy E between the primary side and the secondary side of the transformer 1, so the output voltage Eout depends on the magnitude of the inductance L. will change. Generally, as a means to suppress such fluctuations, strict control is carried out so that the inductance L of the transformer 1 is within a certain tolerance range when manufacturing the transformer 1. There is a problem that the manufacturing process becomes complicated and the cost increases. In addition, the fluctuation factors of the output voltage Eout are:
Another problem was that the Zener voltage of the constant voltage diode 11 varied, and the output voltage Eout actually varied from product to product.

The present invention was developed in view of the above circumstances, and its purpose is to provide a ringing chain converter that can stabilize the output voltage and effectively suppress variations in output voltage from product to product with a simple configuration. is to provide.

[Structure of the invention] (Means for solving the problem) The present invention supplies current from a DC power source to the primary main winding of the transformer through the transistor while the switching transistor is turned on. At this time, the base current is positively fed back to the transistor through the primary feedback winding of the transformer, and the energy stored in the main winding when the transistor is on is transferred to the secondary side of the transformer when the transistor is off. In a ringing chain converter configured to discharge electricity through an output winding, a capacitor charged via a diode by an electromotive force induced in the feedback winding when the transistor is off, and a terminal voltage of this capacitor. a nonlinear circuit element that bypasses the base current that is positively fed back from the feedback winding to the transistor when The configuration is such that it can be connected to.

(Function) The electromotive force induced in the feedback winding when the transistor is off is proportional to the output voltage from the output winding, and therefore the terminal voltage of the capacitor is also proportional to the output voltage. Therefore, when the output voltage increases and the terminal voltage of the capacitor exceeds a predetermined value, the base current that is positively fed back to the transistor is bypassed by the nonlinear circuit element when the transistor is turned on. The transistor is turned off early. As a result, an increase in the output voltage is suppressed, and this operation stabilizes the output voltage.
In this case, the output voltage corresponds to the terminal voltage of the capacitor, but since the terminal voltage can be adjusted by a variable resistor, such adjustment can reduce the inductance of the transformer or the nonlinear circuit. Variations in element constants can be absorbed, thereby suppressing variations in output voltage from product to product.

(Embodiment) Hereinafter, an embodiment of the present invention will be described with reference to FIG. 1. The same parts as in FIG.

That is, in FIG. 1, 12 is a variable resistor interposed in series between the capacitor 9 and the diode 10, and the resistance value of the variable resistor 12 can be arbitrarily adjusted by external operation.

Next, the effect of the above configuration will be described. Since the effect of making the output voltage Eout a constant voltage is the same as described above, it will be omitted, and only the effect due to the provision of the variable resistor 12 will be described. That is, the electromotive force e'2 induced in the feedback winding 1b when the transistor 2 is off is:
The voltage is applied to the capacitor 9 via the diode 10 and the variable resistor 12. Therefore, by adjusting the resistance value of the variable resistor 12, the terminal voltage V'c of the capacitor 9 can be changed. Now, considering the state in which the transistor 2 is turned on, a base current is supplied to the transistor 2 through the resistor 5 and the capacitor 4 by the electromotive force e2 induced in the feedback winding 1b. . At this time, if the base-emitter voltage of the transistor 2 is V _BE and the Zener voltage of the voltage regulator diode 11 is Vz, then when the base current IB flows through the transistor 2, the base current IB flows through the voltage regulator diode 11. The condition for bypassing is when V'c>V _BE +Vz...(I). In other words, when the above condition (I) is satisfied in the process in which the output voltage Eout increases and the base current is supplied from the feedback winding 1b in response, the base current IB is bypassed through the voltage regulator diode 11. Ru. Therefore, since transistor 2 is turned off early and the energy stored in transistor 1 is reduced,
The output voltage Eout begins to decrease, and this operation maintains the output voltage Eout at a constant voltage.

In short, according to the present embodiment described above, the output voltage Eout can be made constant;
At this time, with a simple configuration in which the terminal voltage V'c of the capacitor 9 is adjusted by the variable resistor 12, variations in the output voltage Eout from product to product can be suppressed. In other words, according to this embodiment, variations in the inductance L of the transformer 1 and the Zener voltage Vz of the constant voltage diode 11 can be easily absorbed by adjustment by the variable resistor 12. As a result, it is no longer necessary to strictly control the inductance L during the manufacture of the transformer 1 as in the past, which simplifies the manufacturing process of the transformer 1, improves the yield, and reduces costs. obtain.

In the above embodiment, the constant voltage diode 11 was used as a nonlinear circuit element, but instead of this, a transistor, a trigger diode (PNPN
A nonlinear circuit element such as a diode) may also be used.

[Effect of the invention] According to the invention, as is clear from the above explanation, when the switching transistor is turned on, current is supplied from the DC power source to the primary main winding of the transformer through the transistor. At the same time, at this time, the base current is fed back positively to the transistor through the primary feedback winding of the transformer, and the energy stored in the main winding when the transistor is on is transferred to the secondary of the transformer when the transistor is off. In a ringing chain converter configured to discharge electricity through the next output winding, the output voltage can be made constant, and variations in output voltage from product to product can be effectively reduced with a simple configuration that can suppress cost increases. This has the practical effect of suppressing the

[Brief explanation of the drawing]

FIG. 1 is a wiring diagram showing an embodiment of the present invention. In addition, Fig. 2 is a wiring diagram showing the conventional example, Fig. 3 is a voltage and current waveform diagram for explaining the operation of the conventional example, and Fig. 4 is a diagram showing the conventional example.
This figure is a wiring diagram showing a conventional example different from that in FIG. 2. In the figure, 1 is a transformer, 1a is a main winding, 1b is a feedback winding, 1c is an output winding, 2 is a transistor, 3 is a DC power supply, 9 is a capacitor, 10 is a diode, and 11 is a constant voltage diode ( (nonlinear circuit element), 12 indicates a variable resistor.

Claims (1)

[Scope of utility model registration request] A transformer having a main winding and a feedback winding on a primary side and an output winding on a secondary side, and a collector current is supplied from a DC power source through the main winding in an on state, and the feedback winding a switching transistor to which a base current is positively fed back through the switching transistor, and a ringing device configured to release energy stored in the main winding when the transistor is on through the output winding when the transistor is off. In the choke converter, a capacitor is charged via a diode by an electromotive force induced in the feedback winding when the transistor is turned off, and the feedback winding is charged when the terminal voltage of this capacitor exceeds a predetermined value. A ringing choke converter comprising: a nonlinear circuit element that bypasses a base current that is positively fed back to the transistor from a line; and a variable resistor that is connected in series with the diode and changes the terminal voltage of the capacitor. .