JP2013038847A - Power supply and life detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the life of a smoothing electrolytic capacitor (therefore, a power supply) from a change in the behavior of the power supply.SOLUTION: The present invention relates to a power supply which includes at least a switching control part which forms a switching control signal by monitoring power supply output, a switching element which turns on or off according to the switching control signal, and a smoothing electrolytic capacitor whose own charge voltage is made the power supply output. And, the power supply further includes a frequency measurement part which measures the frequency of the switching control signal, a comparison part which compares the measured frequency with a preset threshold, and a life notification part which, when the measured frequency has exceeded the threshold, notifies that the smoothing electrolytic capacitor has reached its life span.

Description

  The present invention relates to a power supply device and a life detection device, and can be applied to, for example, a hysteretic control power supply device in which an aluminum electrolytic capacitor is applied for smoothing the power supply.

  Generally, when a switching power supply is deteriorated and failed, there are many causes due to the life of an electrolytic capacitor having the shortest life among the components included in the circuit. If the life of this electrolytic capacitor cannot be grasped, the electrolytic capacitor will deteriorate and adversely affect the load due to an increase in ripple.If the replacement time is delayed, the capacitor will burst or break, causing the load to malfunction. If the system goes down, there is a risk of serious damage.

  In order to avoid such an inconvenience, Patent Document 1 proposes a method for detecting the life of the power supply capacitor. In the method described in Patent Document 1, an electrolytic capacitor for life detection is provided in addition to the electrolytic capacitor for smoothing in the power supply device, and the charge / discharge speed of the electrolytic capacitor for life detection is observed. The life of the electrolytic capacitor for smoothing was detected (predicted) based on the change in the charge / discharge rate.

Japanese Patent Laid-Open No. 2001-231253

  However, the method described in Patent Document 1 detects the degree of deterioration (life) of the electrolytic capacitor for life detection, and does not detect the degree of deterioration of the electrolytic capacitor for smoothing in the power supply device. Absent. That is, the life of the power supply device is not detected from the behavior of the power supply device having a smoothing electrolytic capacitor, and it is not always possible to determine whether the power supply device has actually reached the end of its life.

  Therefore, a life detection device that detects the life of a smoothing electrolytic capacitor (and hence a power supply device) from a change in behavior of the power supply device and a power supply device having such a life detection device are desired.

  According to a first aspect of the present invention, a switching control unit that monitors a power supply output to form a switching control signal, a switching element that performs an on / off operation in response to the switching control signal, and a smoothing circuit that uses its own charging voltage as the power supply output. In a power supply device having at least an electrolytic capacitor, (1) a frequency measuring unit that measures the frequency of the switching control signal, and (2) a first comparison that compares the measured frequency with a preset first threshold value. And (3) a life notification unit for notifying the arrival of the life of the smoothing electrolytic capacitor when the measured frequency exceeds the first threshold value.

  According to a second aspect of the present invention, there is provided a switching control unit that monitors a power supply output to form a switching control signal, a switching element that operates on and off in response to the switching control signal, and a smoothing device that uses its own charging voltage as the power supply output. In the life detecting device for detecting the life of the smoothing electrolytic capacitor of the power supply device having at least an electrolytic capacitor, (1) a frequency measuring unit for measuring the frequency of the switching control signal, and (2) the measured frequency A first comparison unit for comparing with a preset first threshold; and (3) a life notification unit for notifying the arrival of the life of the smoothing electrolytic capacitor when the measured frequency exceeds the first threshold. It is characterized by having.

  According to the present invention, it is possible to determine the end of the life of the smoothing electrolytic capacitor based on the parameter, which is the frequency of the switching control signal, which varies depending on the behavior of the power supply device.

It is a block diagram which shows schematic structure of the power supply device which concerns on 1st Embodiment. It is a block diagram which shows schematic structure of the power supply device which concerns on 2nd Embodiment.

(A) 1st Embodiment Hereinafter, 1st Embodiment of the power supply device and lifetime detection apparatus by this invention is described, referring drawings. The power supply device according to the first embodiment is a DC-DC converter.

(A-1) Configuration of First Embodiment FIG. 1 is a block diagram showing a schematic configuration of a power supply device according to the first embodiment. In FIG. 1, a power supply device 1 according to the first embodiment includes a power supply main body 10 and a life detection device 20.

  The power supply main body 10 has the same configuration as an existing power supply. In FIG. 1, a power supply device body 10 including a switching element Q, a diode D, an inductor L, an electrolytic capacitor C, an output voltage monitor circuit 11, and a switching control unit 12 is illustrated.

  A series circuit of a switching element Q and a diode D is connected between the power input terminal and the ground. The switching element Q is turned on and off under the control of the switching control device 12 and intermittently applies the first DC voltage applied to the power input terminal. For example, when a p-type transistor is applied as the switching element Q, the emitter is connected to the power supply input terminal, and the collector is connected to the cathode of a diode D provided for rectification. For example, when an FET is applied as the switching element Q, the source is connected to the power input terminal, and the drain is connected to the cathode of the diode D provided for rectification. The anode of the diode D is grounded.

  The inductor L and the electrolytic capacitor C constitute a smoothing circuit. One end of the inductor L is connected to a connection point between the switching element Q and the diode D, and the other end of the inductor L is connected to one end of the electrolytic capacitor C. The other end of the electrolytic capacitor C is grounded. The rectified output appearing at the cathode of the diode D is smoothed by the smoothing circuit. Although the kind of the electrolytic capacitor C is not limited, for example, a small-sized and large-capacity aluminum electrolytic capacitor can be applied.

  A connection point between the inductor L and the electrolytic capacitor C is output to the power supply output terminal of the power supply device (DC-DC converter) 1. An output voltage monitor circuit 11 is provided to monitor the output voltage (second DC voltage) output from the power supply output terminal. The output voltage monitor circuit 11 includes two resistors R1 and R2 connected in series between the power supply output terminal and the ground. A voltage obtained by dividing the output voltage by the resistors R1 and R2 is input to the switching control unit 12 as a monitor voltage.

  The output control terminal of the switching control unit 12 is connected to the base of the switching element Q. The switching control unit 12 controls ON / OFF of the switching element Q so that the output voltage from the power supply device 1 becomes a predetermined voltage. For example, the switching control unit 12 generates an on / off control signal in accordance with a hysteresis control method. That is, the switching control unit 12 generates a switching control signal that turns on the switching element Q when the output voltage reaches the lower limit set value, and turns off the switching element Q when the output voltage reaches the upper limit set value.

  The life detection device 20 added to the power supply main body 10 having the same configuration as the existing power supply device includes a frequency measurement circuit 21, a comparison circuit 22, and a life notification unit 23.

  The frequency measurement circuit 21 receives a switching control signal given from the switching control unit 12 to the switching element Q, and the frequency measurement circuit 21 measures the frequency (= switching frequency) of the switching control signal. When the switching control unit 12 applies the hysteretic control method, the switching frequency varies depending on the value of ESR (equivalent series resistance) of the electrolytic capacitor. In general, as the life of an electrolytic capacitor (for example, an aluminum electrolytic capacitor) C approaches, its ESR value increases (= capacitor capacitance value decreases), the charge / discharge time constant decreases, and the switching frequency increases. Get higher. In other words, the lifetime of the power supply device 1 can be grasped by increasing the switching frequency. Therefore, in the first embodiment, the frequency measurement circuit 21 measures the switching frequency.

  As a specific configuration of the frequency measurement circuit 21, any existing configuration may be applied. For example, a switching control signal is sampled by a clock having a predetermined period, converted into a binary sequence of “H” and “L”, and a continuous period in which “H” is taken and a continuous period in which “L” is taken Based on the above, the switching frequency may be calculated. Further, for example, an FFT analysis circuit may be applied, and a frequency component having the highest analysis result level may be set as the measurement frequency. Further, for example, the number of rising edges (or the number of 0 crosses) of the switching control signal may be counted every predetermined time, and the counted value may be used as information representing the switching frequency.

  The frequency measurement circuit 21 may be one that performs constant measurement, or may perform measurement periodically, and when the power supply of the device in which the power supply device 1 is mounted, Measurement may be performed under a predetermined rule.

  The comparison circuit 22 compares the switching frequency measured by the frequency measurement circuit 21 with a preset threshold value. Here, the threshold value is selected as a value that can determine whether or not the power supply device 1 has a lifetime. Although the switching frequency changes depending on the load of the load of the power supply device 1, the characteristics of the load that can be connected are determined by the rating of the power supply device 1, and the change range of the switching frequency due to the load of the load is almost constant. is there. Therefore, the switching frequency due to the heavy load and the switching frequency due to the lifetime are different to such a degree that they can be distinguished. In view of these points, a threshold value is selected.

  When the comparison result of the comparison circuit 22 is that the switching frequency exceeds the threshold value, the life notification unit 23 notifies the user of the device in which the power supply device 1 is mounted. For example, a light emitting element (LED) can be applied as the life notification unit 23, and the light is turned on when the comparison result of the comparison circuit 22 indicates that the switching frequency exceeds the threshold value to notify the user that the life has been reached. . Also, for example, if the device equipped with the power supply device 1 is an information processing device such as a personal computer or a smartphone, the comparison result of the comparison circuit 22 is a result that the switching frequency exceeds the threshold value. A predetermined processing program is started and the user is notified that the life has expired by displaying the screen on the display.

(A-2) Operation of the First Embodiment Since the operation of the power supply main body 10 of the power supply device 1 according to the first embodiment is the same as that of the existing one, the description thereof is omitted.

  The frequency measurement circuit 21 of the life detection device 20 starts the measurement operation at the measurement timing. The frequency (= switching frequency) of the switching control signal output from the switching control unit 12 is measured by the frequency measurement circuit 21 and given to the comparison circuit 22, and is compared with the threshold value by the comparison circuit 22. When the measured switching frequency exceeds the threshold value, the life notification unit 23 notifies the user of the device in which the power supply device 1 is mounted that the life has been reached.

(A-3) Effect of First Embodiment As described above, according to the first embodiment, the frequency of the switching control signal that controls the on / off of the switching element is measured, and the measured frequency is compared with a threshold value. Thus, since the end of life is determined (detected), it is possible to correctly determine whether the life has been reached. That is, since it is detected from the behavior of the power supply device 1 (power supply device main body 10) whether the electrolytic capacitor C has reached the end of its life, the detection accuracy can be increased.

(B) Second embodiment)
Next, a second embodiment of the power supply device and the life detection device according to the present invention will be described with reference to the drawings. FIG. 2 is a block diagram showing a schematic configuration of the power supply device according to the second embodiment, in which the same and corresponding parts as those in FIG.

  In FIG. 2, a power supply device 1A according to the second embodiment includes a power supply device body 10 and a life detection device 20A. The power supply main body 10 is the same as that described in the first embodiment.

  In addition to the comparison circuit 22 and the life notification unit 23, the life detection apparatus 20A according to the second embodiment includes N (N is an integer of 1 or more) sets of comparison circuits 22-1 to 22-N and a life extension notification unit 23-. 1-23-N.

  Each of the comparison circuits 22-1 to 22-N also compares the measured switching frequency with a threshold value as in the comparison circuit 22, but the comparison threshold values are the comparison circuits 22-1 to 22-N. Is different. For example, the switching frequency is measured in advance for each capacitance value (for each ESR value), and threshold values for the comparison circuits 22-1 to 22-N are prepared.

  The electrolytic capacitor C reaches the end of its life and gradually decreases its capacitance value. Immediately after starting to lower, only the comparison circuit 22-1 outputs the comparison result of “H”. This means that the grace period until the end of the service life is considerably long. When the capacitance value further decreases, the comparison circuits 22-1 and 22-2 output a comparison result of “H”. This means that the grace period until the end of the life is shortened by one step. Similarly, this means that as the number of comparison circuits that output the “H” comparison results increases, the grace period until the end of the lifetime is shortened. When the comparison circuit 22 also outputs the “H” comparison results, the lifetime is reached. Means that

  Based on the notification contents of the life extension notification units 23-1 to 23 -N and the life notification unit 23 corresponding to each of the comparison circuits 22-1 to 22-N and 22, the user can obtain a grace period until the end of the life and the life arrival. Can be recognized.

  According to the second embodiment, from the behavior of the power supply device 1A (power supply device main body 10), it is possible not only to detect whether the electrolytic capacitor C has reached the end of its life, but also to detect a grace period until the end of the life. .

(C) Other Embodiments In the description of each of the above embodiments, various modified embodiments have been described, and further modified embodiments as exemplified below can be given.

  In the second embodiment, the circuit including the plurality of comparison circuits 22-1 to 22-N and 22 is shown. However, the second embodiment can be implemented with one comparison circuit that can switch (select) the threshold value. You may make it fulfill | perform the function similar to a form. For example, when a comparison result of “H” is obtained by comparison using a certain threshold value, the threshold value may be switched from the previous threshold value to a threshold value that is larger by one level.

  In the second embodiment, the notification units 23-1 to 23-N and 23 are shown. However, a single notification unit may handle a plurality of notification contents. For example, if the device on which the power supply device 1A is mounted is an information processing device such as a personal computer or a smartphone, a predetermined processing program is started by a display based on a comparison result of “H” from any comparison circuit. You may make it notify a user of life end or a grace period by a screen display.

  All or part of the frequency measurement circuit and the comparison circuit may be realized by software processing executed by the CPU.

  The configuration of the power supply main body 10 to which the present invention is applicable is not limited to the illustrated one. In short, the switching control unit has a switching element to which a switching control signal is given, has a smoothing electrolytic capacitor, and the switching control unit has a switching control method in which the frequency of the switching control signal changes depending on the life of the electrolytic capacitor. The present invention can be applied to any power supply device that is employed. For example, if the switching control signal from the switching control unit is a pulse density signal (PDM), the frequency of the switching control signal changes depending on the life of the electrolytic capacitor.

  As long as the above requirements are satisfied, the power supply device of the present invention is not limited to a DC-DC converter, and the present invention can be applied to an AC-DC converter.

  DESCRIPTION OF SYMBOLS 1, 1A ... Power supply device, 10 ... Power supply device main body, 12 ... Switching control part, 20, 20A ... Life detection device, 21 ... Frequency measurement circuit, 22, 222-1 to 22-N ... Comparison circuit, 23 ... Life notification , 23-1 to 23-N ... life extension notification part, Q ... switching element, C ... electrolytic capacitor.

Claims (5)

A power source having at least a switching control unit that monitors a power source output to generate a switching control signal, a switching element that performs an on / off operation in response to the switching control signal, and a smoothing electrolytic capacitor that uses a self-charging voltage as the power source output In the device
A frequency measurement unit for measuring the frequency of the switching control signal;
A first comparison unit that compares the measured frequency with a preset first threshold;
A power supply device comprising: a life notification unit for notifying that the life of the smoothing electrolytic capacitor has reached when the measured frequency exceeds the first threshold value. A second comparison unit that compares the measured frequency with a preset second threshold;
The apparatus further comprises a life delay notification unit for notifying that a predetermined grace period is reached until the life of the smoothing electrolytic capacitor comes when the measured frequency exceeds the second threshold value. The power supply device according to 1.   The switching control unit turns on the switching element when the power supply output reaches a lower limit value, and turns off the switching element when the power supply output reaches an upper limit value. The power supply device according to claim 1, wherein the power supply device forms a signal.   The power supply device according to claim 1, wherein the smoothing electrolytic capacitor is an aluminum electrolytic capacitor. A power source having at least a switching control unit that monitors a power source output to generate a switching control signal, a switching element that performs an on / off operation in response to the switching control signal, and a smoothing electrolytic capacitor that uses a self-charging voltage as the power source output In the life detection device for detecting the arrival of the life of the smoothing electrolytic capacitor of the device,
A frequency measurement unit for measuring the frequency of the switching control signal;
A first comparison unit that compares the measured frequency with a preset first threshold;
A life notifying unit for notifying the arrival of the life of the smoothing electrolytic capacitor when the measured frequency exceeds the first threshold value.

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