JP5459751B2 - Stabilized power supply device and control method thereof - Google Patents

Description

  The present invention relates to a stabilized power supply device and a control method thereof, and more particularly to a stabilized power supply device using a photocoupler inserted in a feedback path and a control method thereof.

  In a stabilized power supply device, there are an electrolytic capacitor and a photocoupler as typical parts that deteriorate. Electrolytic capacitors can be extended in life by using capacitors having a long life such as ceramic capacitors, film capacitors, and functional polymer capacitors. On the other hand, the photocoupler inserted in the feedback path can only slow the progress of deterioration only by adjusting the value of the current flowing to the light emitting side, and there is a limit to extending the life.

  Therefore, Patent Document 1 discloses a switching power supply device that can determine the life of a photocoupler and notify the replacement time. This switching power supply device includes a deterioration detecting means for detecting and notifying the deterioration state of the photocoupler based on the current flowing through the photodiode of the photocoupler, so that the lifetime of the photocoupler deteriorates from the current value flowing through the photodiode. Can be determined and notified.

  As a related technique, Patent Document 2 describes a transmission control circuit having a duplex configuration in which photocouplers are connected in parallel and automatically switching from a current use to a backup when a failure occurs. Specifically, a configuration is disclosed in which a circuit in which a light emitting diode is connected in series to a spare photocoupler is connected in parallel to an active photocoupler.

Japanese Patent Laid-Open No. 2005-245092 Japanese Utility Model Publication No. 04-85845

  The following analysis is given in the present invention.

  The switching power supply device described in Patent Document 1 prompts the replacement of the power supply device before the power supply device abnormally stops by detecting and notifying the deterioration of the photocoupler. There wasn't.

  On the other hand, the duplex configuration in which the photocouplers described in Patent Document 2 are connected in parallel can be applied to the photocoupler in the switching power supply device. However, when the drive current of the current photocoupler decreases and the drive side voltage exceeds the sum of the threshold values of the drive side of the backup photocoupler and the light emitting diode, the drive side of the backup photocoupler operates only. To do. In this case, generally, there is no instantaneous switching from the current photocoupler to the spare photocoupler, and an unstable operation period exists.

  In general, the performance of a photocoupler is expressed by a current transfer ratio (CTR), and deterioration of the photocoupler appears as a decrease in current transfer ratio. Further, the failure of the photocoupler occurs due to various factors such as a short circuit or open state on the light emitting side (driving side) and a short circuit or open state on the light receiving side. In such a case, it is not sufficient to detect the failure of the photocoupler based solely on the decrease in the current value on the light emission side (drive side), and the stable operation at the time of switching the photocoupler may be sustained. Can not.

  Accordingly, an object of the present invention is to provide a stabilized power supply apparatus that can maintain stable operation even when a photocoupler fails due to various factors, and a control method therefor.

A stabilized power supply according to one aspect of the present invention feeds back a difference from a reference value in an output voltage via a photocoupler, and converts the input voltage according to the difference to obtain a stable output voltage. In the obtained stabilized power supply device, a plurality of photocouplers, a switching circuit for selecting one of the plurality of photocouplers, a driving circuit for supplying a difference to the photocoupler selected by the switching circuit, and driving of the selected photocoupler And a photocoupler monitoring means for controlling the switching circuit to change the selection of the photocoupler when the state is monitored and it is detected that the drive state is outside the predetermined state. The photocoupler monitoring means is a voltage monitoring circuit that monitors the output voltage, and the voltage monitoring circuit switches to change the selection of the photocoupler when detecting that the output voltage is out of a predetermined range. Control the circuit.

  In the stabilized power supply device of the present invention, the photocoupler monitoring means is a photocoupler deterioration detection circuit that monitors the drive voltage and / or drive current of the selected photocoupler, and the photocoupler deterioration detection circuit includes the drive voltage and When it is detected that the drive current is outside the predetermined range, the switching circuit may be controlled so as to change the selection of the photocoupler.

  In the stabilized power supply device of the present invention, the photocoupler monitoring means is a voltage monitoring circuit for monitoring the output voltage, and when the voltage monitoring circuit detects that the output voltage is outside the predetermined range, The switching circuit may be controlled to change the selection of the coupler.

According to another aspect of the present invention, there is provided a stabilized power supply control method in which a difference from a reference value in an output voltage is fed back through a photocoupler, and the input voltage is converted into a voltage according to the difference and stabilized. A method of controlling a stabilized power supply device that obtains an output voltage, the step of selecting one from a plurality of photocouplers, the step of supplying a difference to the selected photocoupler, and the driving state of the selected photocoupler And a step of changing the selection of the photocoupler when it is detected that the driving state is outside the predetermined state. The step of monitoring is a step of monitoring the output voltage, and the step of changing changes the selection of the photocoupler when it is detected that the output voltage is outside the predetermined range.

  In the control method of the stabilized power supply apparatus of the present invention, the monitoring step is a step of monitoring the drive voltage and / or drive current of the selected photocoupler, and the changing step is a drive voltage and / or drive current. May be a step of changing the selection of the photocoupler.

  In the control method of the stabilized power supply device of the present invention, the step of monitoring is a step of monitoring the output voltage, and the step of changing is a photo when it is detected that the output voltage is out of a predetermined range. It may be a step of changing the selection of the coupler.

  According to the present invention, a long life of a stabilized power supply circuit can be realized, and stable operation can be maintained even when a photocoupler failure occurs due to various factors.

  A stabilized power supply according to an embodiment of the present invention feeds back a difference (error) from a reference value in an output voltage via a photocoupler, and obtains a stable output voltage by converting the input voltage according to the difference. . In this stabilized power supply device, two photocouplers are mounted in advance, one photocoupler is operated at the start of use, and no current flows to the other photocoupler. Then, it is detected that the selected photocoupler has deteriorated by monitoring the drive state of the selected photocoupler and detecting that the drive state is out of the predetermined state, by detecting that the photocoupler in use has deteriorated. In such a case, the operation is switched to the stopped photocoupler.

  The purpose of using the photocoupler in the stabilized power supply device is to transmit information (difference from the reference value in the output voltage) while ensuring insulation between the input and output of the stabilized power supply device. That is, in the case of a photocoupler in a stabilized power supply device, this information is transmitted accurately and plays the role of stabilizing the output voltage. In this case, when a threshold value is simply set and monitored for the current on the light emitting side, the threshold value for the light emitting side current must be set in accordance with the minimum value of CTR variation of the photocoupler. Therefore, for example, in the case of a high CTR product, there is a possibility that it may be switched because it is judged to be deteriorated even though it is still usable.

  According to the stabilized power supply device of the present invention, since the driving state of the photocoupler is monitored, there is an advantage that the first photocoupler can be used for a long time in the case of a high CTR product. That is, not only the open or short failure of the photocoupler but also the deterioration including the CTR variation can be detected, and the photocoupler can be used up to the limit where it can be used.

  In addition, it is possible to perform switching by monitoring, including faults on the light receiving side of the photocoupler (all transfer characteristics such as open and short). Furthermore, by directly monitoring the characteristics (stabilization of output voltage) that the stabilized power supply is originally required, the performance guarantee becomes more reliable.

  FIG. 1 is a block diagram showing a configuration of a stabilized power supply apparatus according to a first embodiment of the present invention. In FIG. 1, the stabilized power supply device includes a voltage conversion circuit 11, a reference voltage source 12, a comparison error amplification circuit 13, a photocoupler driving circuit 14, a switching circuit 16, photocouplers 17 and 18, and a control circuit 19. The photocoupler drive circuit 14 includes a photocoupler deterioration detection circuit 15.

  The voltage conversion circuit 11 converts the input voltage IN according to the control of the control circuit 19 and outputs an output voltage OUT having a stable voltage. The comparison error amplifier circuit 13 compares the output voltage OUT with the reference voltage of the reference voltage source 12, amplifies an error (difference) signal as a comparison result, and outputs the amplified signal to the photocoupler drive circuit 14. The photocoupler drive circuit 14 connects the output of the comparison error amplifier circuit 13 to the light emitting side of the photocoupler 17 or the photocoupler 18 via the switching circuit 16 and allows a current corresponding to the error signal to flow. The control circuit 19 controls the operation of the voltage conversion circuit 11 by a current flowing to the light receiving side of the photocoupler 17 or the photocoupler 18.

  The photocoupler deterioration detection circuit 15 monitors the drive state of the drive element, that is, the drive voltage and / or drive current of the photocoupler drive circuit 14, and detects that the drive voltage and / or drive current is outside a predetermined range. In this case, the switching signal SEL is output to the switching circuit 16.

  The switching circuit 16 connects the output of the photocoupler driving circuit 14 to either the photocoupler 17 or the photocoupler 18 when the stabilized power supply is started, and allows a current to flow to the light emission side of the photocoupler. Further, when the switching signal SEL is input, the switching circuit 16 switches and connects the output of the photocoupler driving circuit 14 to the other photocoupler that has not been connected so far, to the light emitting side of the other photocoupler. Apply current.

  Next, a control method of the stabilized power supply device having the above configuration will be described. FIG. 2 is a flowchart showing a control method of the stabilized power supply apparatus according to the first embodiment of the present invention.

  After activation of the stabilized power supply device, the switching circuit 16 selects one from the photocoupler 17 or the photocoupler 18 in step S11.

  In step S12, the photocoupler drive circuit 14 supplies a drive signal based on the difference calculated by the comparison error amplification circuit 13 to the selected photocoupler.

  In step S13, the photocoupler deterioration detection circuit 15 monitors the drive voltage and / or drive current of the selected photocoupler, and detects that the drive voltage and / or drive current is outside a predetermined range (step S13). In Y of S13, the switching signal SEL is output to the switching circuit 16 so as to change the selection of the photocoupler (step S14).

  In step S15, the stabilized power supply device is continuously operated by operating the photocoupler switched by the switching circuit 16.

  Here, the monitoring of the driving voltage and driving current of the photocoupler in the photocoupler deterioration detection circuit 15 will be described. From the viewpoint of detecting the failure mode of the photocoupler, the failure factor of the photocoupler varies depending on each monitoring item, and is as follows.

  When performing voltage monitoring (voltage drop Vf on the light emission side), the maximum drive voltage is detected when the drive side is open, an abnormal drop in drive voltage is observed when the drive side is short, and a slight increase in drive voltage is observed when the CTR deteriorates. Observed.

  In addition, when performing current monitoring (light emission side drive current If), an abnormal drop in drive current is observed when the drive side is open, the maximum drive current is detected when the drive side is short, and the maximum drive current is detected when the CTR is degraded. Is done.

  As described above, there is a case where the determination of the CTR deterioration is not sufficient only by the voltage monitoring (light emission side Vf), and it is difficult to determine the short (light emission side) and the CTR deterioration only by the current monitoring (light emission side If). Therefore, it is more preferable to monitor both the driving voltage and the driving current.

  When both the driving voltage and the driving current are monitored, the failure mode of the photocoupler can be determined from each detection result. That is, when the light emission side is open, the maximum drive voltage is detected or a drive current abnormality drop is detected. Further, in the case of the light emitting side short circuit, the maximum drive current is detected, or the drive voltage abnormal drop is detected. Further, in the case of CTR degradation, the maximum drive current is detected, and the normal drive voltage range (not the drive current abnormal drop) is detected.

  As described above, by observing the driving state of the photocoupler, it is possible to grasp various failure factors of the photocoupler and perform stable switching control.

  FIG. 3 is a block diagram showing the configuration of the stabilized power supply apparatus according to the second embodiment of the present invention. 3, the same reference numerals as those in FIG. 1 represent the same items, and the description thereof is omitted. The stabilized power supply device of FIG. 3 is different from that of FIG. In addition, a transmission circuit 21 that transmits the switching signal SEL output from the voltage monitoring circuit 20 to the control circuit 19a is provided. Further, the switching circuit 16 a is switched by the voltage monitoring circuit 20.

  The voltage monitoring circuit 20 monitors the output voltage OUT of the voltage conversion circuit 11. When the output voltage OUT becomes a voltage outside the design accuracy range, the voltage monitoring circuit 20 determines that the photocoupler has deteriorated, and the switching circuit 16a and the control circuit 19a. The switching signal SEL is output.

  The transmission circuit 21 is a circuit that electrically insulates the switching signal SEL and transmits it to the control circuit 19a. For example, the transmission circuit 21 is a circuit that can be turned on and off, such as a photocoupler or a latching relay.

  The control circuit 19a receives the electrically isolated switching signal SEL, selects the light receiving side of the photocoupler 17 or photocoupler 18 based on the switching signal SEL, and receives the light receiving side of the selected photocoupler 17 or photocoupler 18. The operation of the voltage conversion circuit 11 is controlled by the current flowing in the direction.

  Next, a control method of the stabilized power supply device having the above configuration will be described. FIG. 4 is a flowchart showing a control method of the stabilized power supply apparatus according to the second embodiment of the present invention. In FIG. 4, steps with the same reference numerals as in FIG. 2 perform the same processing, and a description thereof is omitted.

  In step S13a, the voltage monitoring circuit 20 monitors the output voltage OUT of the voltage conversion circuit 11. If the output voltage OUT is out of the design accuracy range (Y in step S13a), the photocoupler is selected. The switching signal SEL is output to the switching circuit 16a so as to be changed (step S14).

  According to the stabilized power supply device that operates as described above, since the voltage monitoring circuit 20 monitors the output voltage OUT, the functional failure of the entire photocoupler including the failure on the photocoupler light-receiving side is detected and the photocoupler switching control is performed. Can be done.

  In the above description, the switching signal SEL can be output to the outside of the apparatus, and one of the photocouplers can not be used at the end of its life, and the outside can be informed to replace the defective photocoupler.

  Further, in the above description, the number of photocouplers is two, but it is possible to further increase the life by sequentially switching to three or more photocouplers.

  It should be noted that the disclosures of the aforementioned patent documents and the like are incorporated herein by reference. Within the scope of the entire disclosure (including claims) of the present invention, the embodiments and examples can be changed and adjusted based on the basic technical concept. Various combinations and selections of various disclosed elements are possible within the scope of the claims of the present invention. That is, the present invention of course includes various variations and modifications that could be made by those skilled in the art according to the entire disclosure including the claims and the technical idea.

It is a block diagram which shows the structure of the stabilized power supply device which concerns on 1st Example of this invention. It is a flowchart which shows the control method of the stabilization power supply device which concerns on 1st Example of this invention. It is a block diagram which shows the structure of the stabilized power supply device which concerns on 2nd Example of this invention. It is a flowchart which shows the control method of the stabilized power supply device which concerns on 2nd Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Voltage conversion circuit 12 Reference voltage source 13 Comparison error amplification circuit 14, 14a Photocoupler drive circuit 15 Photocoupler deterioration detection circuit 16, 16a Switching circuit 17, 18 Photocoupler 19, 19a Control circuit 20 Voltage monitoring circuit 21 Transmission circuit IN Input Voltage OUT Output voltage SEL switching signal

Claims (2)

In a stabilized power supply that obtains a stable output voltage by feeding back a difference from a reference value in an output voltage via a photocoupler and converting the input voltage according to the difference,
A plurality of photocouplers;
A switching circuit for selecting one of the plurality of photocouplers;
A drive circuit for supplying the difference to the photocoupler selected by the switching circuit;
Photocoupler monitoring means for monitoring the driving state of the selected photocoupler and controlling the switching circuit to change the selection of the photocoupler when it is detected that the driving state is outside a predetermined state; ,
Equipped with a,
The photocoupler monitoring means is a voltage monitoring circuit for monitoring the output voltage,
Wherein the voltage monitoring circuit, when the output voltage is detected to be outside the predetermined range, stabilized power supply apparatus characterized that you control the switching circuit so as to change the selection of optocouplers. A method for controlling a stabilized power supply that obtains a stable output voltage by feeding back a difference from a reference value in an output voltage via a photocoupler and converting the input voltage according to the difference,
Selecting one from a plurality of photocouplers;
Supplying the difference to the selected photocoupler;
Monitoring the driving state of the selected photocoupler;
Changing the selection of the photocoupler when detecting that the drive state is outside a predetermined state; and
Only including,
The step of monitoring is a step of monitoring the output voltage,
The method of controlling a stabilized power supply apparatus, wherein the changing step is a step of changing selection of a photocoupler when it is detected that the output voltage is outside a predetermined range .

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