JPS6149221A - Power supply device - Google Patents

Abstract

PURPOSE:To obtain a power supply device having a small rush current by specifically connecting the 1st and 2nd constant voltage diodes, resistance and transistors, respectively and conducting with control a switching element. CONSTITUTION:A capacitor input type power supply device contains a rush current preventing circuit consisting of a thyristor 4, a resistance 5, etc. This circuit functions to reduce a rush current produced when a power supply is switched on. The desired DC voltage V5 is outputted via a voltage converting part 12. At the same time, the thyristor 4 is controlled by a control part 13. Here a series matter consisting of the 1st constant voltage diode 17 set in parallel to a smoothing capacitor 6 through the cathode of the diode 17 and the 2nd resistance 16 is provided together with a pnp transistor TR19 connected to the base of an npn TR9, the 2nd constant voltage diode 12, a capacitor 11, etc. Thus the part 13 is driven. Then the TR19 is turned on when a switch 2 is turned off and then turned on again. Thus the capacitor 11 is quickly discharged, and a rush current can be reduced despite a short time of a 2nd make mode.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a so-called capacitor input type power supply device that is equipped with a smoothing capacitor at the input section, and in particular, to limit the current flowing into the smoothing capacitor when an input voltage is applied. related to a power supply device.

(Prior Art) In a capacitor input type power supply device, an inrush current prevention circuit using a switching element such as a thyristor has been developed in order to reduce the inrush current when the power is turned on. 2. Conventional Kame-ryo system using the prevention circuit. The waveform diagrams of the gll path length and various signals are shown in FIGS. 1 and 2, respectively. In this power supply device, the cross-current voltage of the input AC power source 1 is turned on by the switch 2 and rectified by the rectifier stack 3. The pulsating current output from the stack 3 charges the smoothing capacitor 6 through the resistor 5.The voltage v across the smoothing capacitor 6 is equal to the smoothed DC voltage.The DC voltage V,
is a desired DC voltage V by the voltage converter 12.

The direct voltage I# and the voltage V are supplied to the output terminals 21 and 22. The voltage converter 12 generates a voltage V when the control voltage v3 becomes a high potential, and simultaneously generates a thyristor drive vJ.
The voltage v4 is set to a high potential and the thyristor 4 is made conductive. The control unit 13 sets the VC control voltage V to a high potential when the voltage V exceeds the threshold voltage E. Resistor 14 is a discharge resistance of capacitor 6.

Next, the voltages V, , V2. Regarding the relationship between V and v4, when the switch 2 is turned on at to, the output voltage of the AC trace 1 is rectified by the rectifier stack 3 and charges the capacitor 6 via the resistor 5.
The voltage v1 increases and charging ends at tl. The emitter voltage v2 of the transistor 9, which is the voltage for operating the control unit 13, rises according to a time constant determined by the resistor 8, the resistor 15, and the capacitor 11, and reaches t, when it reaches the threshold voltage 82 or more, and the control voltage v3 becomes high potential.

At the same time that the control voltage v3 becomes a high potential, the thyristor drive voltage v4 becomes a high potential, gates the thyristor 4, makes the thyristor 4 conductive, and short-circuits the resistor 5. The above is the operation when the power is turned on. Next, let us consider the case where the switch 2 is turned off and then turned on again.

When the switch 2 is disconnected at t, the voltage v1 of the capacitor 6 starts to decrease, and the emitter voltage of the transistor 9 v
2 also decreases. Then, at time t4, the voltage v2 becomes lower than the threshold voltage E2, and the operation of the control unit 13 stops, and at the same time the control voltage v3 becomes a low potential, the thyristor drive voltage v4 also becomes a low potential, and the thyristor 4 enters the cut-off state. .

After that, the voltage vl of the capacitor 6 is discharged by the discharge resistor 14 and so on and decreases, but the capacitance of the capacitor 6 is large.
Since the discharge resistor 14 cannot be designed to have a small eb due to loss, the voltage Vl of the capacitor 6 decreases very slowly. For this reason, v2 is also V! decreases slowly as well. Therefore, if switch 2 is turned on again at time t5, when v2 has not decreased much, Ml will immediately rise, so
At time t6, the control section 13 starts operating, and the control voltage v
3 and the thyristor drive voltage v4 become high potentials, and the thyristor 4 is turned on. In this way, in the conventional power supply device, the thyristor 4 is turned on at time t6 when charging of the capacitor 6 is not completed, so a large charging current (rush current) flows through the capacitor 6, so if the time between t4 and t6 is short, Inrush current is not effectively limited. Therefore, in order to limit the inrush current to a low level in a conventional power supply device, the time required to turn off the switch 2 and turn it on again (14 in Fig. 2) is required.
to t5) had to be increased.

(Objective of the Invention) An object of the present invention is to provide a power supply device in which inrush current is small even when the time from input voltage cutoff to input voltage restart is short.

(Structure of the Invention) The structure of the present invention is such that when an input voltage is applied, a first resistor is inserted in series in the path of the current flowing into the smoothing capacitor of the input section, and the charging voltage of the smoothing capacitor is A power supply device that short-circuits the first resistor by a switching element when the voltage exceeds a predetermined value includes a first voltage regulator diode whose cathode is connected to the positive potential side of the smoothing capacitor; a second resistor connected between the anode side of the voltage regulator diode and the negative potential side of the smoothing capacitor; and an NPN transistor whose collector is connected to the cathode of the first voltage regulator diode;
A third resistor is connected between the pace and the collector of the NPN transistor, the pace is connected to the anode, the emitter is connected to the pace of the NPN transistor, and the collector is connected to the negative potential side of the smoothing capacitor. %5 contact between a PNP transistor and the emitter and collector of this PNP transistor.
a capacitor whose cathode is connected to the emitter of the PNP transistor and whose anode is connected to the PNP transistor
- A second 2g voltage diode connected to the collector of the transistor, and a circuit that makes the switching element conductive when the voltage at the emitter of the PNP transistor exceeds a predetermined value. All features.

(Example) Next, the present invention will be explained in detail with reference to Examples.

FIG. 3 is a circuit diagram showing one embodiment of the present invention, and FIG. 4 is a waveform diagram of various signals of this practical example. In this embodiment, 1 is an input power supply, 2 is a switch for turning on and off the voltage of the power supply 1, 3 is a rectifier stack, 4 is a thyristor, 5,
8, 14, 15.16 are resistors, 9 is an NPN resistor, 19 is a PNP transistor, in, 17 is a constant voltage diode, 18 is a diode, 6, 1.1 is a capacitor, 12 is a voltage converter, 13 is a control unit, and 21.22 is an output terminal.

Next, the operation of FIG. 3 will be explained with reference to FIG. 4, which is an operational waveform diagram. When the switch 2 is turned on at time t0, the AC voltage supplied from the AC power source 1 is rectified by the rectifier stack 3. The pulsating current in the rectifier stack 3 charges the smoothing capacitor 6 via the resistor 5, and charging ends at t2. The voltage v1 across the smoothing capacitor 6 is a smoothed DC voltage. On the other hand, the emitter voltage v2 of the transistor 9, which is the power source for operating the control unit 13, is at the time t.
The constant voltage diode 17 is off between o and t),
Resistance 16. Since the transistor 19 is turned on by the diode 18, the voltage is 0.

Next, at time t1, the voltage regulator diode 17 turns on/off.
Therefore, the transistor 19 is turned off, and the voltage v1 rises according to a time constant determined by the capacitor 11 and the resistor i, and at time t3, it exceeds the threshold voltage E2, and the control section 13 starts operating, and the control voltage v3 increases. The potential becomes high, and the voltage converter 12 outputs a predetermined voltage V5, and the thyristor drive voltage v4 is made high potential, turning on the thyristor 4.

Short-circuit resistor 5. The above is the operation when the power is turned on. Next, let us consider the case where the switch 2 is turned off and then turned on again.

When the switch 2 is turned off at time t4, the voltage v1 of the capacitor 6 starts to decrease, and at the time ts, the constant voltage diode 17 is turned off and the transistor 19 is turned on, so that the capacitor 11 is connected to the transistor 19.
Discharges quickly. Therefore, v2 rapidly decreases, the operation of the control unit 13 is stopped, voltages v3 and v4 become low potentials, and the thyristor 4 is turned off. Thereafter, the voltage Yl of the smoothing capacitor 6 is discharged by the discharge resistor 14, etc., but since the capacitor 6 has a large capacity and the discharge resistor 14 cannot be set to a very small value due to loss, the voltage Yl is discharged at a very slow rate. After υ, t, it cannot fall too quickly. However, the voltage v2 for operating the control section 13 is 0■ due to the above-described operation. Therefore, even if the switch 2 is turned on at time t6 when the discharge of the capacitor 6 is not completed, the voltage v
2 starts rising only from time t7, the control unit 13 at time t when charging of the capacitor 6 has finished.
starts operating, voltage v3ev4 becomes high potential, thyristor 4 is triggered and turned on. Even if the thyristor 4 is turned on at time t8, since the capacitor 6 has finished charging, the current flowing into the smoothing capacitor 6 can be limited to a sufficiently small value. In this way, in this example,
Even if the time between turning off the switch 2 and turning it on again (from t4 to t6 in FIG. 4) is short, the incoming current can be limited to a small value.

(Effect of the invention) According to the present invention, K as detailed above.

It is possible to provide a power supply device with a small inrush current even when the time from input voltage cutoff to input voltage is short.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing a conventional power supply device, Fig. 2 is a waveform diagram of various signals of this conventional device, Fig. 3 is a circuit diagram showing an embodiment of the present invention, and Fig. 4 is a circuit diagram of this embodiment. It is a waveform diagram of each part signal.

Claims (1)

[Claims] A first resistor is inserted in series in the path of the current flowing into the smoothing capacitor in the input section when the input voltage is applied.
A first constant voltage whose cathode is connected to the positive potential side of the smoothing capacitor in a power supply device that short-circuits the first resistor by a switching element when the charging voltage of the smoothing capacitor is equal to or higher than a predetermined value. diode and
a second resistor connected between the anode side of the first voltage regulator diode and the negative potential side of the smoothing capacitor; and an NPN transistor whose collector is connected to the cathode of the first voltage regulator diode. , a third resistor connected between the base and the collector of the NPN transistor; the base is connected to the anode, the emitter is connected to the base of the NPN transistor, and the collector is connected to the negative potential side of the smoothing capacitor. PNP with
a transistor, and a capacitor connected between the emitter and the collector of the PNP transistor;
a cathode is connected to the emitter of the PNP transistor;
a second voltage regulator diode, each having an anode connected to the collector of the PNP transistor;
A power supply device comprising: a circuit that makes the switching element conductive when the voltage of the emitter of the PN transistor exceeds a predetermined value.