JPH0628509B2 - Ringing / Choke / Converter - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ringing choke converter, and more particularly to a ringing choke that can quickly stop oscillation when the input voltage drops after being activated. -Regarding the converter.

[Background of the Invention]

A conventional ringing choke converter has a structure as shown in FIG. 4, as disclosed in, for example, Japanese Patent Laid-Open No. 59-20446. In the figure, 1 is a main transistor, 2 is a transformer having _first and second primary windings n ₁ and n ₂ and a secondary winding n _S , 3, 6 and 19 are capacitors,
4 is a starting resistor, 7 and 18 are diodes, and 5 and 8 are resistors.

In FIG. 4, the input voltage V _i is applied and the input voltage V _i
When the value obtained by dividing _i by the resistors 4 and 5 reaches the base-emitter saturation voltage V _BE of the transistor 1, current is supplied to the base of the transistor 1 and the transistor 1 is turned on. As a result, the collector current i _{c of the} transistor increases with a slope determined by the inductance of the primary winding n ₁ , and the base current I _B and the current amplification factor h of the transistor 1 increase.
Upon reaching the product I _B · h _FE of _FE, the transistor 1 is abruptly cut off. When the transistor 1 is cut off, the energy stored in the transformer 2 is transmitted to the load 20 via the diode 18. When the secondary current of the transformer 2 becomes zero, a surge generated by the leakage inductance of the transformer 2 is applied to the base of the transistor 1 via the primary winding n ₂ , the transistor 1 is turned on again, and so on. Repeat off.

As is clear from the above description, the conventional ringing choke converter does not start until the value obtained by dividing the input voltage V _i by the resistors 4 and 5 reaches the base-emitter saturation voltage V _BE of the transistor 1. . However, once activated, the on / off state of the transistor 1 is not stopped even if the _divided voltage value of the input voltage V _i becomes equal to or lower than the base-emitter saturation voltage V _BE . Generally, assuming that the input voltage at which the transistor 1 is activated is V _th , ON / OFF of the transistor 1 is not stopped until the input voltage V _i drops to about 1/2 V _th .

Therefore, the conventional ringing choke converter is
There is a problem that it cannot be used as a power supply to be stopped when the input voltage drops or a power supply to be stopped immediately when the input voltage is cut off.

[Object of the Invention]

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a ringing choke converter that can quickly stop oscillation when the input voltage drops even if it is once started. .

[Outline of Invention]

The ringing choke converter of the present invention includes a main transistor that applies an input voltage to the first primary winding of the transformer and a secondary winding of the transformer with a polarity that provides power to the load during the off period of the main transistor. A first rectifier circuit connected thereto, and a feedback circuit connected to the second primary winding of the transformer and generating a positive feedback voltage for turning on the main transistor during the off period of the main transistor, It has the following features.

That is, a third primary winding connected to the transformer, a second rectifying circuit for rectifying the output of the third primary winding, and a first output terminal of the second rectifying circuit An emitter terminal is connected, a base terminal is connected to a second output end of the second rectifier circuit via a Zener diode and a resistance DC circuit, and an emitter terminal is connected to connect / disconnect the feedback circuit. And a sub-transistor whose collector terminal is connected to the feedback circuit.

Example of Invention

Hereinafter, the present invention will be described in more detail with reference to the embodiments shown in the accompanying drawings.

FIG. 1 is a circuit diagram showing a first embodiment of the present invention. The same parts as those of the conventional example shown in FIG. The difference between the embodiment shown in FIG. 1 and the conventional example shown in FIG. 4 is that the transformer 2 has a third primary winding n ₃
And the diode 13 and the capacitor 1
4, Zener diode 15, resistor 16, sub-transistor 17
Is arranged as shown in the figure. Here, the diode 13 and the capacitor 14 form a rectifier circuit that supplies power to the sub-transistor 17.

In the above configuration, since the input voltage V _i is set higher than V _th , the divided voltage value of the starting resistor 4 and the resistor 5 becomes higher than the base-emitter saturation voltage V _{BE of} the transistor 1, and the transistor 1 is turned on. Voltages V ₂ and V _{3 in} the directions of arrows are generated in the primary windings n ₂ and n ₃ , respectively. At the same time, the value of the voltage V ₃ changes to the base of the auxiliary transistor 17.
If the primary winding n ₃ of the Zener voltage is set so as to be higher than the emitter saturation voltage Vα, the sub-transistor 17
Is turned on. Therefore, the base current is supplied from the winding n ₂ to the transistor 1 through the sub transistor 17,
After that, the transistor 1 is repeatedly turned on and off as in the case of the conventional example shown in FIG.

Further, once the transistor 1 starts to be turned on and off, the input voltage V _i decreases, and V ₃ generated in the winding n ₃ during the on period of the transistor 1 is the zener voltage of the zener diode 15 and the base When it becomes smaller than the sum value Vα of the emitter saturation voltage, the sub-transistor 17 is turned off. Therefore, when the transistor 1 is in the off state, the secondary current of the transformer 2 becomes zero, and the transistor 17 is in the off state even if the surge generates the voltage V _{2 in} the direction of the arrow in the secondary winding n _2. Therefore, the transistor 1 does not turn on. Therefore, it is possible to surely stop the ringing choke covert. FIG. 2 shows the relationship between the input voltage V _i and the main transistor 1 and the sub transistor 17 in the first embodiment.

As is apparent from the above description, according to the first embodiment shown in FIG. 1, depending on the selection of the voltage division ratio of the resistors 4 and 5, the winding n ₃ and the winding, and the Zener voltage of the Zener diode 15. It can be seen that the on / off start voltage and stop voltage of the ringing choke converter can be set freely.

FIG. 3 is a block diagram showing a second embodiment of the present invention. In FIG. 2, the same parts as those in the first embodiment shown in FIG. 1 are designated by the same reference numerals. The second embodiment shown in FIG. 2 is one in which the winding n ₃ shown in FIG. 1 is omitted and the winding n ₂ is shared, and has the same action and effect as those of the first embodiment. Is.

〔The invention's effect〕

As is clear from the above description, since the ringing choke converter of the present invention can freely set the on / off start voltage and stop voltage of the main transistor, it is possible to reliably stop the input voltage when the input voltage falls below a predetermined value. Have.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram showing a first embodiment of the present invention, FIG. 2 is a time chart showing the operation of the first embodiment shown in FIG. 1, and FIG. Circuit diagram showing a second embodiment of the invention, a fourth
The figure is a circuit diagram showing a conventional ringing choke converter. 1 ... Main transistor, 2 ... Transformer, 3, 6, 14,
19 …… Capacitor, 4 …… Starting resistance, 5,8,16 …… Resistance, 7,13,18 …… Diode, 15 …… Zener diode, 17 …… Subtransistor, 20 …… Load.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Teruhiko Endo 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Stock company Hitachi Totsuka factory (72) Inventor Yoshinori Kuroki 216 Totsuka-cho, Totsuka-ku, Yokohama, Kanagawa Inside the Hitachi Ltd. Totsuka Plant (72) Inventor Masayuki Komatsu 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Inside the Hitachi Ltd. Totsuka Plant (56) Bibliography Sho 60-192686 (JP, U) 57-31087 (JP, U) Actually opened 60-18682 (JP, U) Actually opened 57-45293 (JP, U)

Claims (1)

[Claims] 1. A main transistor that applies an input voltage to a first primary winding of a transformer and a first transistor that is connected to a secondary winding of the transformer with a polarity that supplies power to a load while the main transistor is off. And a feedback circuit connected to the second primary winding of the transformer to generate a positive feedback voltage for turning on the main transistor during the off period of the main transistor. A third primary winding connected to the second primary winding, a second rectifying circuit for rectifying the output of the third primary winding, and an emitter terminal connected to the first output end of the second rectifying circuit. The base terminal is connected to the second output terminal of the second rectifier circuit via a series circuit of a Zener diode and a resistor, and further, an emitter terminal and a collector terminal are connected so as to conduct / block the feedback circuit. Ringing choke, characterized in that instead and a sub Totanjisuta connected to the circuit
converter.