JPH07147765A - Starting means of power converting circuit - Google Patents

Abstract

PURPOSE:To realize a starting means which needs a smaller number of components by a method wherein the starting means of a power converting circuit is composed of a first capacitance means, a second capacitance means and a negative resistance means. CONSTITUTION:A capacitor 3 which is a first capacitance means is charged by a DC power supply 2 and, when the charged voltage of the capacitor 3 exceeds a designated value, a DIAC 5 which is negative resistance means is turned off. By the negative resistance characteristics of the DIAC 5, a charging current is applied to a capacitor 4 which is a second capacitance means at one stroke. The charging current is applied to a power converting circuit composed of transistors 6 and 7, etc., as a starting signal. With this constitution, a starting signal receiving means for the power converting circuit can be realized with a small number of components.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a starting means for a power conversion circuit, which requires fewer parts than the prior art.

[0002]

[Background Technology] As a conventional technique, a well-known power conversion circuit starting means is shown in FIGS.

Prior art: JP-A-60-51475,
JP-A-61-273187, JP-A-63-3947
No. 2, JP-A-63-59772, JP-A-1-23
No. 4060, Japanese Patent Laid-Open No. 1-274671.

In the circuit of FIG. 2, the power switch 1 turns
After turning on, the current of the resistor 13 charges the capacitor 4, and the voltage is diac (bidirectional 2-terminal thyristor).
When the breakover voltage of 5 is exceeded, diac 5
Turns on. Then, due to the negative resistance characteristic of the diac 5, the capacitor 4 is discharged all at once, and this discharge current becomes a start signal and is applied to the power conversion circuit formed by the transistors 6 and 7 although not shown in the figure.
However, the maximum value of the discharge current is limited by the diac 5.

As a result, the transistors 6 and 7 are alternately turned on and off, and the transistor 7, the diode 14 and the resistor 15 prevent the voltage of the capacitor 4 from reaching the breakover voltage, so that the activation means is The start signal is no longer output. Therefore, the extra activation signal is
It does not interfere with the operation of the transistor 7 that turns on and off.

Instead of the diac 5, any negative resistance means can be used which exhibits a negative resistance characteristic when the voltage across the diac 5 exceeds a predetermined value. Although there is a conventional example in which the cathode of the diode 14 is directly connected to the collector of the transistor 7, it is preferable to have the resistor 15 in order to prevent an overcurrent from flowing to the transistor 7.

The structure and operation of the starting means of each power conversion circuit in FIGS. 3 and 4 are the same as this. However, in the circuit of FIG. 4, transistors 18, 19 and Zener diode 1
6 and the resistors 17 and 20 form an equivalent circuit of SUS (silicon unilateral switch). The diode 21 is provided as a countermeasure against the reverse voltage of the emitter junction of the transistor 18.

However, the starting means for these power conversion circuits has a problem that the number of parts is large.

Therefore, an object of the present invention is to provide a starting means for a power conversion circuit which requires a smaller number of parts than the prior art.

[0010]

That is, the present invention provides a negative resistance characteristic between the terminals of the first capacitance means which is charged by the DC power supply, the second capacitance means, and the voltage across the second capacitance means exceeding a predetermined value. The negative resistance means and the activation signal receiving means for receiving the activation signal are connected in series to activate the power conversion circuit.

As a result, the first and second capacitance means and the negative resistance means can constitute the starting means of the power conversion circuit, and this starting means is different from the conventional starting means shown in FIGS. The number of parts is small. As described above, the present invention has an effect that the number of parts is smaller than that in the conventional technique.

The operation is as follows. When the DC power supply charges the first capacitance means and its voltage exceeds the predetermined value, the negative resistance means is turned on. Therefore, due to the negative resistance characteristic, the charging current flows through the second capacitance means at once, and this charging current becomes the activation signal for the activation signal receiving means. After this, once the second capacitance means has been charged, this activation means will no longer output an activation signal.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In order to describe the present invention in more detail, it will be described below with reference to the accompanying drawings. In the circuit of FIG. 1, the transistors 6, 7, the transformer 8,
The inductor 9, the capacitors 11 and 12, and the load 10 constitute a series resonance type self-excited power conversion circuit, and the power supply capacitor 3, the capacitor 4 and the diac 5 constitute the starting means (one embodiment of the present invention). To do. The power supply capacitor 3 corresponds to the above-mentioned first capacitance means, the capacitor 4 corresponds to the above-mentioned second capacitance means, and the diac 5 corresponds to the above-mentioned negative resistance means.

The operation of this circuit is as follows. When the power switch 1 is closed, the DC power supply 2 charges the power supply capacitor 3. When the charging voltage exceeds the breakover voltage of the diac 5, the diac 5 is turned on, and the charging current of the capacitor 4 suddenly flows into the emitter junction of the transistor 7 or the like. As a result, the transistor 7 is turned on, and the self-excited power conversion circuit starts oscillating. However, the maximum value of the charging current is limited by the diac 5.

Instead of the diac 5, any negative resistance means can be used as long as the voltage across the diac 5 exceeds a predetermined value, which exhibits negative resistance characteristics. For example, trigger diode, SUS (silicon unilateral switch), SBS (silicon bilateral switch),
Two resistors are connected in series between both main terminals of the thyristor, and the connection point of both resistors and its gate are connected, or
There is an equivalent circuit of any of these. Further, in the present invention, since the series circuit of the capacitors 11 and 12 serves as the above-mentioned first capacitance means, the power supply capacitor 3 may be omitted. However, as the power conversion circuit, the power supply capacitor 3 that absorbs the feedback current is used.
It is better to have By the way, it is obvious that the number of parts of this embodiment is smaller than that of each of the conventional activation means shown in FIGS. Such effects are included in the present invention including this embodiment.

In the embodiment of FIG. 5, the transistors 18, 1
9, Zener diode 16, and resistors 17, 20
Is used as a negative resistance means. Instead of the Zener diode 16, a resistor may be connected between the collector and emitter of one of the transistors 18 and 19. The diode 21 is the transistor 18
This is to prevent the reverse voltage of the emitter junction.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing one embodiment of the present invention used in a conventional power conversion circuit.

2 to 4 are circuit diagrams each showing a starting means of a conventional power conversion circuit.

FIG. 5 is a circuit diagram showing an embodiment of the present invention.

[Explanation of code]

 5 ... Diac 10 ... Load

Claims (7)

[Claims] 1. A second capacitance means between both terminals of the first capacitance means charged by a DC power source, a negative resistance means exhibiting a negative resistance characteristic when the voltage across the second capacitance means exceeds a predetermined value, and A starting means for a power conversion circuit, characterized in that starting signal receiving means for receiving a starting signal are connected in series. 2. The starting means of a power conversion circuit according to claim 1, wherein a trigger diode is used as the negative resistance means. 3. The starting means for a power conversion circuit according to claim 1, wherein a silicon unilateral switch or an equivalent circuit thereof is used for the negative resistance means. 4. The starting means for the power conversion circuit according to claim 1, wherein a silicon bilateral switch or its equivalent circuit is used for the negative resistance means. 5. The starting means for the power conversion circuit according to claim 1, wherein a bidirectional two-terminal thyristor or an equivalent circuit thereof is used for the negative resistance means. 6. The negative resistance means is characterized in that two resistors are connected in series between both main terminals of a thyristor or its equivalent circuit, and the connection point of both resistors is connected to its gate. The starting means of the power conversion circuit according to claim 1. 7. The power conversion circuit start-up means according to claim 1, wherein a power supply capacitor is used as the first capacitance means.