JPH11202015A - Malfunction detecting circuit for switching power source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cause a power LED to emit light within a stated lighting range always with the same brightness, and to make it possible to perform a malfunction detection without a variation in the parallel operation of switching power sources. SOLUTION: When the input-side voltage of a block diode 5 is equal to or lower than the breakdown voltage of a zener diode 6, a transistor 10 is in an off-state, a power LED 7 is in a turned-off state, and the B contact of a relay 9 is in a closed state. When the input-side voltage of the block diode 5 becomes equal to or higher than the breakdown voltage of the zener diode 6, the transistor 10 is turned on, and the power LED 7 is in a on-state, and the B contact of the relay 9 becomes in an open-state. Since the transistor 10 performs the on/off operation of the power LED 7, it is regulated by one voltage value, and the power LED 7 repeats on/off operation within a stated lighting range always with a constant brightness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a failure detection circuit for a switching power supply in consideration of parallel operation.

[0002]

2. Description of the Related Art FIG. 6A shows the configuration of a conventional power LED lighting circuit of a switching power supply, and FIG. 6B shows the configuration of an alarm LED lighting circuit. (C) shows the configuration of the failure detection output circuit.
These circuits are provided between the output terminal of the switching power supply, that is, between the output (+) and the ground (GND). In the figure, 7 is a power LED, 8 is an alarm LED, 5 is a block diode, 6 is a Zener diode, 10, 11, and 22 are transistors, 9 is a B contact relay, 14, 15, 18, 19, 20, and 20. 21 is a resistor.

[0003] Since the breakdown voltage of the Zener diode 6 is lower than the output voltage of the switching power supply during normal operation,
During normal operation, the power LED 7 is lit. When the output voltage drops below the breakdown voltage of the Zener diode 6 due to an abnormality, the alarm LED 8 is turned on by turning on the transistor 10 and turning on the transistor 11 at the same time. At the same time, transistor 22
Is also turned off, the excitation of the B contact relay 9 is released, and the contact is turned off. Thereby, a failure signal is transmitted to an external circuit.

[0004]

For example, two or more switching power supplies are operated in parallel, each circuit of the conventional example shown in FIG. 6 is connected to each power supply, and switching of LED lighting display when power supply output is abnormal. When transmitting a failure signal, the following problem arises.

[0005] LED of each power supply connected in parallel
The off timing and the failure signal output timing vary, and the on / off timing of the LEDs 7 and 8 in the same power supply also varies.

[0006] The light emission level of the LED 7 depends on the voltage rise.

When one power supply fails, the LED does not light up. The relay cannot be driven. The failure of one power supply means a case where the output of the power supply becomes impossible for some reason. In this case, the system operates normally with the other power supply connected in parallel, but it is necessary to notify the presence of the abnormal power supply by LED or signal output.

Therefore, there is a problem that the parallel operation of the power supplies becomes difficult from the above.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a switching power supply failure detection circuit which solves the above problems.

[0010]

In order to achieve the above object, the present invention is directed to a first light emitting means, a relay and a first light emitting means for displaying on / off of a power output power connected in series between power output terminals. One transistor, a Zener diode connected between the power output terminals, and means for controlling on / off of the first transistor in response to a breakdown operation of the Zener diode.

According to a second aspect of the present invention, in the first aspect, a block diode provided on a power output side of the power output terminal is provided, and each of the connection portions is provided on an input side of the block diode. It is characterized by having.

Further, according to a third aspect of the present invention, there is provided a first light emitting means, a relay and a first transistor for indicating on / off of a power supply output power connected in series between power supply output terminals;
A Zener diode connected between the power output side and a control terminal of the first transistor, a second light emitting unit and a second transistor connected in series between the power output terminals, the first transistor and the relay, Connection,
Means for connecting to the control terminal of the second transistor;
The power supply system further includes a connection unit that connects a connection portion between the second transistor and the second light emitting unit and a terminal on the power output side of the zener diode.

Further, according to a fourth aspect of the present invention, in the third aspect, a block diode provided on a power output side of the power output terminal is provided, and each of the connection portions is provided on an input side of the block diode. It is characterized by having.

According to a fifth aspect of the present invention, in the third aspect, a block diode provided on a power output side of the power output terminal is provided, and a connection portion of the zener diode is provided on an input side of the block diode. And a connecting portion of the first and second light emitting means is provided on an output side of the block diode.

[0015]

FIG. 1 is a diagram showing a state in which energy obtained from an AC power supply 1 is converted into DC power and supplied to a load 4 by parallel operation of switching power supplies 2 and 3 enabled by the present invention. .

(Embodiment 1) FIG. 2 is a circuit diagram of a first embodiment, in which a voltage value on an input side of a block diode 5 is detected to control turning on / off of a power LED 7 and opening / closing of a relay 9. Things. The basic operation of this failure detection circuit is
It mainly depends on the on / off timing of the transistor 10 determined by the zener diode 6 and the resistors 14 and 20.

As shown in FIG. 2, a resistor 1 is connected between an output terminal of a power supply, that is, an output (+) and a ground (GND).
4, a series circuit of a zener diode 6 and a resistor 20 is provided, and a series circuit of a power LED 7, a relay 9 and a transistor 10 is provided. A resistor 16 is provided in parallel with the power LED 7, and a resistor 16 is provided in parallel with the relay 9. The diode 12 is connected, and the resistor 15 is connected between the base of the transistor 10 and the anode of the Zener diode 6.

Here, when the voltage on the input side of the block diode 5 is lower than the breakdown voltage of the Zener diode 6, the transistor 10 is off, the power LED 7 is turned off, and the B contact of the relay 9 is closed. . When the voltage on the input side of the block diode 5 becomes equal to or higher than the breakdown voltage of the Zener diode 6, the transistor 10 is turned on, the power LED 7 is turned on, and the B contact of the relay 9 is opened.

Since the power LED 7 is turned on and off by the transistor 10, it is defined by one voltage value, and the power LED 7 can be repeatedly turned on and off at a constant brightness within a predetermined lighting range. That is, there is no variation between the power supplies. Further, even when the power LED 7 fails, the relay 9 can output a signal because the relay 9 is connected in series.

(Embodiment 2) FIG. 3 is a circuit diagram of a second embodiment, in which a voltage value on the input side of a block diode 5 is detected to turn on / off a power LED 7, an alarm LED 8, and a relay 9 Open / close operation is performed without variation between the power supplies, and control is performed so that a constant LED luminance is selected.

The basic operation of the failure detection circuit mainly depends on the switching voltage determined by the zener diode 6 and the resistors 14 and 17.

As shown in FIG. 3, a series circuit of an alarm LED 8, a resistor 19 and a transistor 11 is further connected between the output terminal of the power supply, that is, the output (+) and the ground GND. The anode is connected to the base of the transistor 10 via the resistor 15, and a series circuit of the resistor 17 and the diode 13 is connected between the cathode of the Zener diode 6 and the connection of the resistor 14 and the collector of the transistor 11.

If the voltage on the input side of the block diode 5 is lower than the switching voltage, the transistor 1
When only 1 is turned on through the power LED 7 and the relay 9, the alarm LED 8 is turned on, and the B contact of the relay 9 is closed. At this time, the transistor 10 is off. When the voltage on the input side of the block diode 5 becomes higher than the switching voltage, the transistor 1
0 turns on and the transistor 11 turns off. Thereby, the alarm LED 8 is turned off and the power LED 7 is turned on. At the same time, the contact B of the relay 9 is opened.

According to the above configuration, it is possible to minimize the on / off timing of the power LED 7 and the alarm LED 8 and the variation of the LED and failure signal timing between the power supplies. Further, even when the power LED 7 fails, a signal can be output by the relay 9, and the alarm LED 8 can be turned on.

(Embodiment 3) FIG. 4 is a circuit diagram of a third embodiment, in which a block diode 5 is connected to a power supply input side of two LEDs 7 and 8 and is output from a voltage detection point of a zener diode 6. It is provided on the side. The basic operation is the same as in the second embodiment, and the effect is the same.
Further, since the power LED 7, the alarm LED 8, and the relay 9 are provided on the cathode side of the block diode 5, even when another power supply connected in parallel fails, the LED failure display and the relay output can be performed.

FIG. 5 shows the relationship between the power supply output voltage, the power LED 7, the alarm LED 8, and the B contact of the relay 9 in the second and third embodiments. It can be seen that the on / off timing of the LED has hysteresis.

[0027]

As described above, according to the present invention, the power light emitting means can always emit light with the same brightness within a predetermined lighting range. In addition, variations in the light emitting means and the failure signal can be minimized, and parallel operation of the power supplies has become possible. Further, when one of the power supplies connected in parallel fails or the light emitting means itself fails, a failure signal can be output. Furthermore, at the time of parallel operation, failures of other power sources can be detected.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a first embodiment of the present invention.

FIG. 3 is a diagram showing a second embodiment of the present invention.

FIG. 4 is a diagram showing a third embodiment of the present invention.

FIG. 5 is a diagram showing an operation time chart in the present invention.

FIGS. 6A, 6B, and 6C are diagrams showing a conventional failure detection circuit.

[Explanation of symbols]

 5 Block diode 6 Zener diode 7 Power LED 9 Relay 10 Transistor

Claims (5)

[Claims] A first light emitting unit, a relay, and a first transistor for indicating on / off of a power output power connected in series between power output terminals; a Zener diode connected between the power output terminals; Means for controlling on / off of the first transistor in response to a breakdown operation of the Zener diode. 2. The device according to claim 1, further comprising: a block diode provided on a power output side of the power output terminals, wherein each of the connection portions is provided on an input side of the block diode. Switching power supply failure detection circuit. 3. A first light emitting means, a relay and a first transistor for indicating on / off of a power supply output power connected in series between power supply output terminals, the first light emitting means, a relay and a first transistor; A Zener diode connected therebetween, a second light emitting unit and a second transistor connected in series between the power output terminals, a connection portion between the first transistor and the relay, and a control terminal of the second transistor. Connecting means for connecting the second transistor and the second light emitting means, and means for connecting a terminal on the power output side of the zener diode, for detecting a failure of the switching power supply. circuit. 4. The device according to claim 3, further comprising a block diode provided on a power output side of the power output terminals, wherein each of the connection portions is provided on an input side of the block diode. Switching power supply failure detection circuit. 5. The power supply output terminal according to claim 3, further comprising: a block diode provided on a power output side of the power output terminal, wherein a connection portion of the zener diode is provided on an input side of the block diode, and And a connection part for the second light emitting means is provided on the output side of the block diode.