JP2000350455A - Switching power supply unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To replace a power supply unit by preventing adverse effects to occur on the load and malfunctions of a system, even if a capacitor is not in working order and is dead. SOLUTION: If a capacitor 11 is dead and output voltage is under a reference voltage, an LED 15 is lit to notify of this, and a relay 22 is driven to turn on a relay contact 21. A backup capacitor 12 is connected to the output side to be operated in place of the capacitor 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply such as a switching power supply, and more particularly, to protection of a power supply during its life.

[0002]

2. Description of the Related Art Conventionally, for example, for detecting the life of a switching power supply, the life of an electrolytic capacitor having the shortest life among circuit components used in the switching power supply is regarded as the expected life of the switching power supply.

[0003]

However, there are few cases where the device is used according to the condition of the expected life, and the service life greatly changes depending on the use condition. If the service life cannot be ascertained, the capacitor will deteriorate and adversely affect the load due to increased ripple.If the replacement time is delayed, the capacitor will burst or be damaged, and important data will be lost due to the malfunction of the load. There is a drawback in that the system goes down and causes serious damage.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has been made to prevent an adverse effect on a load and a system down when a capacitor stops performing its function and reaches the end of its life. It is intended to make it possible to replace the power supply.

[0005]

In order to achieve the above-mentioned object, the present invention is configured as follows.

That is, a power supply device according to a first aspect of the present invention includes a power supply device having a main capacitor that smoothes an input voltage and outputs the smoothed voltage to an output side. Detecting means for providing a detection output when the output of the output becomes equal to or less than a predetermined value;
A connection means for connecting the backup capacitor to the output side in response to a detection output of the detection means to enable smoothing of an input voltage by the backup capacitor.

According to a second aspect of the present invention, in the power supply device according to the first aspect, the detecting means includes an output voltage detecting section for detecting an output voltage and a comparing section for comparing the detected output voltage with a reference voltage. A switch provided between the other end of the backup capacitor, one end of which is connected to one of the output lines, and the other of the output lines,
A switch control unit that controls the switch based on an output of the comparison unit.

According to a third aspect of the present invention, there is provided a power supply device including a main capacitor for smoothing an input voltage and outputting the smoothed voltage to an output side, wherein a backup capacitor for smoothing an input voltage is provided separately from the main capacitor. A path control means for electrically disconnecting the backup capacitor from the output side in a normal state and electrically connecting the backup capacitor to the output side in response to an output of a predetermined value or less of the power supply device. I have.

According to a fourth aspect of the present invention, in the power supply apparatus according to the third aspect, the path control means includes a first diode between a secondary winding of a transformer and the main capacitor, and a secondary winding of the transformer. A second diode between the second capacitor and the backup capacitor; and a third diode between the backup capacitor and the output side.

According to a fifth aspect of the present invention, there is provided a power supply device comprising:
In any one of the inventions, a switching-type power supply device that controls a switching element connected to a primary winding of a transformer based on an output, wherein the notification is performed when an output becomes equal to or less than the predetermined value. Means.

According to the power supply device of the first aspect, when the main capacitor reaches the end of its life and a predetermined output cannot be obtained, the backup capacitor is connected to the output side and operates instead of the main capacitor. Become.

According to the power supply device of the second aspect, when the main capacitor reaches the end of its life and a predetermined output voltage cannot be obtained,
By turning on the switch, the backup capacitor can be connected to the output side to operate.

According to the power supply device of the third aspect, when the main capacitor reaches the end of its life and a predetermined output cannot be obtained, the backup capacitor is electrically connected to the output side by the passage control means and is replaced with the main capacitor. Will work.

According to the power supply device of the fourth aspect, when a predetermined output cannot be obtained, the backup capacitor is electrically connected to the output side by the third diode between the backup capacitor and the output side to operate. Will be.

According to the power supply device of the present invention, when the output becomes equal to or less than the predetermined value, the notification is made, so that it is possible to know that the main capacitor has reached the end of its life.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a block diagram of a switching power supply as a power supply according to one embodiment of the present invention.

The switching power supply according to this embodiment includes an AC power supply 1 and a rectifier circuit 3 composed of a diode bridge connected via an AC filter 2. , A smoothing capacitor 4 is connected. A primary winding 5 of a high-frequency transformer 5 is provided between one end of the smoothing capacitor 4 and the other end.
A switching element 6 composed of an FET is connected via a, and this switching element 6 is on / off controlled by an output of a control circuit 7. The secondary winding 5b of the high-frequency transformer 5 includes diodes 8, 9, a reactor 10,
It is connected to a load (not shown) via a rectifying / smoothing circuit including the capacitor 11.

The control circuit 7 detects the output voltage, compares it with a reference voltage, controls the on / off of the switching element 6, and controls the output voltage to be stabilized and output even if the AC input changes. is there.

In this embodiment, a capacitor 11 composed of a secondary-side electrolytic capacitor as a main capacitor is
When a predetermined output cannot be obtained due to the end of the service life, a normal operation can be performed and the load is not adversely affected.

That is, the switching power supply of this embodiment has a backup capacitor 12, a detecting means 13 for detecting that the output has become equal to or less than a predetermined value, and an output based on the detected output of the detecting means 13. When the output falls below a predetermined value, the connection means 14 for connecting the backup capacitor 12 to the output side, based on the detection output of the detection means 13, and when the output falls below the predetermined value, lights it to notify And an LED 15 as an informing means for performing the notification.

The detecting means 13 compares the detected output voltage with a reference voltage of the Zener diode 17 when the output voltage falls below the reference voltage. Comparison section 18 for providing output
In this embodiment, the capacitor 11
When the output voltage drops and becomes lower than the reference voltage, for example, the lower limit value of the rated output, the comparing section 18 gives a detection output and holds (latches) the detection output.

In this example, the detection output is given when the output voltage falls below the reference voltage. However, the detection output may be given when the output voltage falls below the reference voltage.

The connection means 14 includes a transistor 19 serving as a switch control unit to which the detection output of the comparison unit 18 is supplied to the base, and a coil 20 connected to the transistor 19, while connecting the output line to one end of the backup capacitor 12. And a relay 22 having a relay contact 21 interposed therebetween. When the output voltage falls below the reference voltage, the transistor 19 is turned on by the detection output of the comparing unit 18 to energize the coil 20 and the relay contact 21 Turns on and the backup capacitor 12 is connected in parallel with the capacitor 11, that is, on the output side.

FIG. 2 is a flowchart for explaining the operation of this embodiment.

First, during operation, the output voltage Vo is detected (step n1), and it is determined whether or not the capacitor 11 has reached the end of its life and the output voltage Vo has fallen below the reference voltage Vlimit (step n2). In response to the detection output of the detection means 13, the connection means 14 determines that the capacitor 11 has reached the end of its life.
2 is connected to the output side (step n3), and the backup capacitor 12 starts operating (step n2). Further, the LED 15 is turned on to notify the end of the life (step n5), and the user who knows that the life has expired by turning on the LED 15 replaces the switching power supply (step n6).

As described above, when the output voltage falls below the reference voltage due to the end of the life of the capacitor 11, the backup capacitor 12 is immediately connected to start the operation in place of the capacitor 11, so that adverse effects on the load can be prevented. The life of the switching power supply device can be prolonged and the replacement time can be prolonged, so that the switching power supply device can be replaced with a margin.

In this embodiment, the backup capacitor 12 is connected by a mechanical contact using the relay 22. However, a semiconductor switch may be used as another embodiment of the present invention.

In this embodiment, when the output voltage falls below the reference voltage, the backup capacitor 1
Although the second embodiment is only connected to the output side, as another embodiment of the present invention, the backup capacitor 12 may be connected to the output side and the capacitor 11 may be disconnected from the output side.

In this embodiment, the life of the capacitor 11 is notified by the LED, but may be notified by a buzzer or the like.

(Embodiment 2) FIG. 3 is a configuration diagram of a switching power supply according to another embodiment of the present invention.
Parts corresponding to those in FIG. 1 described above are denoted by the same reference numerals.

Although the above-described embodiment employs the forward system, this embodiment employs the flyback system. The secondary winding 5b of the high-frequency transformer 5 includes a first rectifying diode 23 and a capacitor. 11 is connected to a load (not shown) via a rectifying / smoothing circuit.

In this embodiment, a capacitor 11 composed of a secondary-side electrolytic capacitor as a main capacitor is
When the specified output cannot be obtained due to the end of the service life, in order to switch to normal operation and eliminate the adverse effect on the load,
It is configured as follows.

That is, in this embodiment, the backup capacitor 12 for smoothing the input voltage separately from the capacitor 11 and the backup capacitor 12 are electrically disconnected from the output side in a normal state to respond to an output of a predetermined value or less. And a path control means 24 for electrically connecting the backup capacitor 12 to the output side.

The path control means 24 includes the first diode 23 described above, a second diode 25 for rectification in parallel with the first diode 23, and the backup capacitor 12.
And a third diode 26 between the first side and the output side.

Further, a transistor 27 driven by the output of the backup capacitor 12 serves as a notifying means for turning on and notifying when the output falls below a predetermined value.
And an LED 28 illuminated by the transistor 27
And 29 is a bias resistor.

In the switching power supply having the above configuration, when the capacitor 11 has not reached the end of its life and is operating normally, the first
Is supplied with power through the diode 23, at this time, the voltage at the connection of the third diode 26 of the backup capacitor 12 is lower by the forward voltage V _F content of the third diode 26 in comparison with the output voltage Therefore, the third diode 26 is in an off state,
The backup capacitor 12 is electrically disconnected from the output side.

Next, when the capacitor 11 reaches the end of its service life and does not operate normally, the output voltage drops. When the forward voltage V _F of the third diode 26 drops below the normal output voltage, the third diode 26 turns on and power is supplied through the second diode 25 indicated by the arrow B. At the same time, the transistor 27 turns on and the LED 28
Is driven to light up.

The supply in the case where switching to the backup capacitor 12 power than the normal output voltage although the forward voltage V _F content lower by the third diode 26, to prevent an adverse effect to the load compared with the case of no backup Is enough.

Incidentally, a plurality of third diodes 26 may be provided in series.

Also, instead of the third diode 26, an LED
It is good also as composition which also serves as a notifying means using.

(Other Embodiments) In the above embodiments, the secondary side capacitor 11 is backed up by the backup capacitor 12, but as another embodiment of the present invention, the primary side capacitor 4 is backed up. You may make it.

Although the above embodiment is applied to a switching power supply, the present invention can be applied to other power supply devices having a capacitor other than the switching power supply.

[0044]

As described above, according to the present invention, when the life of the main capacitor expires and a predetermined output cannot be obtained, the backup capacitor is connected to the output side and operates instead of the main capacitor. Therefore, it is possible to avoid adverse effects on the load, for example, a situation in which the load malfunctions or the system goes down, and the life of the power supply is extended, so that the power supply can be replaced with a margin.

Further, when the backup capacitor is switched, it is notified that the main capacitor has reached the end of its life.

[Brief description of the drawings]

FIG. 1 is a block diagram of a power supply device according to one embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of FIG. 1;

FIG. 3 is a block diagram of a power supply device according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 AC power supply 5 High frequency transformer 11 Capacitor (main capacitor) 12 Backup capacitor 13 Detecting means 14 Connecting means 15, 28 LED 24 Path control means

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Claims (5)

[Claims] 1. A power supply device having a main capacitor for smoothing an input voltage and outputting the smoothed voltage to an output side, wherein a backup capacitor disconnected from the output side and an output of the power supply device become a predetermined value or less. Detecting means for providing a detection output when the power supply is turned on, and connecting means for connecting the backup capacitor to the output side to enable smoothing of the input voltage by the backup capacitor in response to the detection output of the detection means. A power supply device comprising: 2. The detecting means includes: an output voltage detecting unit for detecting an output voltage; and a comparing unit for comparing the detected output voltage with a reference voltage. 2. A switch provided between the other end of the backup capacitor connected to the other end of the output line and a switch control unit that controls the switch based on an output of the comparison unit. Power supply. 3. A power supply device comprising a main capacitor for smoothing an input voltage and outputting the smoothed voltage to an output side, wherein a backup capacitor for smoothing an input voltage is provided separately from the main capacitor; Path control means for electrically disconnecting a capacitor from the output side and electrically connecting the backup capacitor to the output side in response to an output of a predetermined value or less of the power supply device. apparatus. 4. The path control means includes: a first diode between a secondary winding of a transformer and the main capacitor; a second diode between a secondary winding of the transformer and the backup capacitor; The power supply device according to claim 3, further comprising a third diode between the backup capacitor and an output side. 5. A switching type power supply device for controlling a switching element connected to a primary winding of a transformer based on an output, wherein a notifying means for notifying when an output becomes equal to or less than the predetermined value. The power supply device according to any one of claims 1 to 4, further comprising: