JP6666550B2 - Capacitor life diagnosis device, power supply system, capacitor life diagnosis method and program - Google Patents

Description

  The present invention relates to a capacitor life diagnosis device, a power supply system, a capacitor life diagnosis method, and a program.

  2. Description of the Related Art A capacitor life determining device that is connected to a DC-DC converter and a load circuit and determines whether an output capacitor of the DC-DC converter is at the end of its life is known (see Patent Document 1). The DC-DC converter has an output capacitor charged by a DC power supply, a switching element for turning on and off charging of the output capacitor from the DC power supply, and a control unit. The control unit periodically turns on and off the switching element, detects the voltage across the output capacitor, and determines the on-duty of the switching element by feedback control such that the voltage across the output capacitor is set to a predetermined target voltage. The load circuit is a load circuit that converts output power of the DC-DC converter and outputs the converted output power to the load, and varies output power to the load according to an external input. The capacitor life determining device includes a load control unit, a voltage detecting unit, and a life determining unit. The load control unit periodically performs the determination control of temporarily changing the output power of the load circuit at intervals longer than the duration of the determination control. The voltage detector detects at least an AC component of the voltage across the output capacitor immediately after the start of the control for determination. The life determining unit determines whether or not the output capacitor is at the end of life based on the amplitude of the voltage between both ends detected by the voltage detecting unit.

  Further, there is known a switching power supply device having a DC voltage obtained by rectifying / smoothing an AC input to obtain a DC voltage, switching the DC voltage, performing a rectifying / smoothing process to obtain an output voltage, and having an electrolytic capacitor for a smoothing process. (See Patent Document 2). The switching power supply device has a process of measuring a frequency of an AC input, a process of measuring an output voltage and an output current, and a process of measuring a terminal voltage of an electrolytic capacitor. Further, the switching power supply device has a process of converting the terminal voltage into a terminal voltage at a rated load based on the measured frequency, output voltage and output current, and terminal voltage of the electrolytic capacitor. Further, the switching power supply device has a step of comparing the converted terminal voltage with a preset initial value of the terminal voltage to determine a decrease in the capacitance of the electrolytic capacitor.

JP 2011-97683 A JP 2000-308339 A

  Patent Literature 1 determines whether an output capacitor is at the end of its life at the present time. Japanese Patent Application Laid-Open No. H11-163873 determines a decrease in the capacitance of an electrolytic capacitor. However, Patent Documents 1 and 2 cannot notify the remaining life of the capacitor.

  An object of the present invention is to provide a capacitor life diagnosis device, a power supply system, a capacitor life diagnosis method, and a program that can notify the life expectancy of a first capacitor.

The capacitor life diagnosing device includes: a first fluctuation detecting unit that detects a maximum value of a fluctuation of an output voltage of a first capacitor at regular intervals; and a fluctuation of the output voltage detected by the first fluctuation detecting unit. An output unit that predicts the life expectancy of the first capacitor based on the time transition of the maximum value and outputs a signal indicating the life expectancy of the first capacitor, and a maximum value of the fluctuation of the output current of the first capacitor. A second variation detection unit that detects the constant time interval, wherein the output unit is configured to output the second variation when the maximum value of the variation of the output current detected by the second variation detection unit is smaller than a threshold value. Except for the maximum value of the fluctuation of the output voltage detected by the fluctuation detecting unit, the first value when the maximum value of the fluctuation of the output current detected by the second fluctuation detecting unit is larger than the threshold value Detected by the fluctuation detection unit Serial life expectancy of the first capacitor is predicted based on time changes of the maximum value of the variation of the output voltage, and outputs a signal indicating the remaining life of the first capacitor.

  By estimating the life expectancy of the first capacitor and outputting a signal indicating the life expectancy of the first capacitor, the life expectancy of the first capacitor can be notified.

FIG. 1 is a diagram illustrating a configuration example of a power supply system according to the first embodiment. FIG. 2 is a diagram illustrating a configuration example of the fluctuation detecting unit in FIG. FIG. 3 is a graph showing the relationship between the output voltage fluctuation value and the capacity decrease of the electrolytic capacitor. FIG. 4 is a diagram illustrating an example of a daily load change of the server. FIG. 5 is a diagram showing the time transition of the maximum value of the output voltage variation of the electrolytic capacitor at regular intervals. FIG. 6 is a flowchart showing a method for diagnosing the life of a capacitor of a power supply circuit. FIG. 7 is a diagram illustrating a configuration example of a power supply system according to the second embodiment. FIGS. 8A to 8C are diagrams showing current waveforms and voltage waveforms as a result of the simulation. FIG. 9 is a diagram illustrating a configuration example of a power supply system according to the third embodiment. FIGS. 10A to 10C are diagrams showing a power supply system according to the fourth embodiment. FIGS. 11A to 11C are diagrams illustrating a control unit according to the fifth embodiment. FIG. 12A is a diagram showing a voltage corresponding to a duty ratio, FIG. 12B is a diagram showing a waveform of an output voltage of the electrolytic capacitor, and FIG. 12C is a diagram of a voltage output by the low-pass filter. It is a figure showing a waveform. FIGS. 13A to 13C are diagrams for explaining a method of determining the reduction ratio. FIGS. 14A and 14B are flowcharts illustrating a processing example of the microcomputer. FIGS. 15A and 15B are diagrams illustrating a control unit according to the sixth embodiment.

(First embodiment)
FIG. 1 is a diagram illustrating a configuration example of a power supply system according to the first embodiment. The power supply system includes an AC power supply 101, a power supply circuit 100, and a server 124. The power supply circuit 100 is an alternating current (AC) -direct current (DC) power supply, and includes a capacitor life diagnosis device. The power supply circuit 100 includes a rectifier circuit 102, an inductor 107, an n-channel field-effect transistor 108, a diode 109, an electrolytic capacitor 110, a voltage detector 111, an n-channel field-effect transistor 112, and a transformer 113. Further, the power supply circuit 100 includes diodes 116 and 117, an inductor 118, an electrolytic capacitor 119, a current detection unit 120, a voltage detection unit 121, fluctuation detection units 122a to 122c, and a control unit 123. Transformer 113 includes a primary winding 114 and a secondary winding 115. The field effect transistors 108 and 112 are preferably gallium nitride (GaN) high electron mobility transistors (HEMTs), but may be MOS field effect transistors. HEMTs have the advantages of high breakdown voltage and high speed switching. The power supply circuit 100 converts an AC voltage input from the AC power supply 101 into a DC voltage, and supplies the converted DC voltage to the server 124 as a power supply voltage. The power supply circuit 100 may supply a DC voltage to electronic devices other than the server 124.

The AC power supply 101 is a commercial power supply such as a household outlet, and supplies an AC voltage of, for example, 100 to 240 V between the input nodes N1 and N2 of the power supply circuit 100. The rectifier circuit 102 has diodes 103 to 106. Diode 103 has an anode connected to node N1 and a cathode connected to node N3. Diode 104 has an anode connected to node N4 and a cathode connected to node N2. Diode 105 has an anode connected to node N4 and a cathode connected to node N1. Diode 106 has an anode connected to node N2 and a cathode connected to node N3. Rectifier circuit 10 2, an AC voltage between nodes N1 and N2 full-wave rectified, and outputs a voltage full-wave rectification between the nodes N3 and N4.

  Inductor 107 is connected between nodes N3 and N5. The field effect transistor 108 has a drain connected to the node N5, a gate connected to the control unit 123, and a source connected to a reference potential node (ground potential node). The field effect transistor 108 is a power factor correction circuit that controls the output voltage of the rectifier circuit 102 to a reference voltage (0 V) according to a gate control signal. The control unit 123 outputs a control pulse signal having a frequency higher than the frequency (50 Hz or 60 Hz) of the AC power supply 101 to the gate of the field effect transistor 108. The field effect transistor 108 repeats on and off in a short cycle. Diode 109 has an anode connected to node N5 and a cathode connected to node N6. Electrolytic capacitor 110 is connected between nodes N6 and N4.

  The inductor 107, the field effect transistor 108, the diode 109, and the electrolytic capacitor 110 are a boost chopper circuit. While the field effect transistor 108 is on, energy is accumulated in the inductor 107 by the output of the rectifier circuit 102. On the other hand, while the field effect transistor 108 is off, the electrolytic capacitor 110 is charged by the voltage obtained by superimposing the voltage across the inductor 107 on the output voltage of the rectifier circuit 102. That is, the electrolytic capacitor 110 is charged only while the field-effect transistor 108 is off. Electrolytic capacitor 110 is charged to a voltage obtained by boosting the voltage of rectifier circuit 102. For example, when AC power supply 101 outputs an AC voltage of 100 V, the voltage across electrolytic capacitor 110 is a DC voltage of 400 V. Electrolytic capacitor 110 outputs a charged voltage.

  Voltage detecting section 111 detects an output voltage of electrolytic capacitor 110. The fluctuation detecting unit 122a detects the maximum value of the fluctuation of the output voltage of the electrolytic capacitor 110 detected by the voltage detecting unit 111 at regular intervals, and outputs the detected maximum value of the fluctuation of the output voltage to the control unit 123.

  The primary winding 114 of the transformer 113 is connected between the node N6 and the drain of the field effect transistor 112. The field effect transistor 112 has a gate connected to the control unit 123 and a source connected to the node N4. Secondary winding 115 is connected between the anode of diode 116 and node N8. Node N8 is a ground potential node. Diode 116 has a cathode connected to node N7. Diode 117 has an anode connected to node N8 and a cathode connected to node N7. Inductor 118 is connected between nodes N7 and N9. Electrolytic capacitor 119 is connected between nodes N9 and N8.

  Transformer 113 transforms the voltage of primary winding 114 output from electrolytic capacitor 110, and outputs the transformed voltage to secondary winding 115. Specifically, when a voltage is applied to primary winding 114, a voltage lower than the voltage of primary winding 114 is generated in secondary winding 115. Diodes 116 and 117 are rectifier circuits that rectify the voltage of secondary winding 115.

  The inductor 118 and the electrolytic capacitor 119 are a smoothing circuit, which smoothes the voltage of the node N7 and outputs a smoothed voltage. The voltage between the nodes N9 and N8 is, for example, a DC voltage of 19 V and is supplied to the server 124 as a power supply voltage. The server 124 is a load on the power supply circuit 100.

  Current detection section 120 detects an output current of electrolytic capacitor 119. The fluctuation detecting unit 122b detects the maximum value of the fluctuation of the output current of the electrolytic capacitor 119 detected by the current detecting unit 120 at regular intervals, and outputs the detected maximum value of the fluctuation of the output current to the control unit 123.

  Voltage detecting section 121 detects an output voltage of electrolytic capacitor 119. The fluctuation detecting unit 122c detects the maximum value of the fluctuation of the output voltage of the electrolytic capacitor 119 detected by the voltage detecting unit 121 at regular intervals, and outputs the detected maximum value of the fluctuation of the output voltage to the control unit 123.

  A gate voltage of a high-frequency pulse is input to the gate of the field-effect transistor 112. The control unit 123 controls the pulse width of the gate voltage of the field-effect transistor 112 according to the output voltage of the electrolytic capacitor 119 detected by the voltage detection unit 121. Specifically, the control unit 123 widens the pulse width of the gate voltage of the field effect transistor 112 when the output voltage of the electrolytic capacitor 119 is lower than the target value (for example, 19 V), and the output voltage of the electrolytic capacitor 119 becomes lower than the target value (for example, 19V). If it is higher than 19 V, for example, the pulse width of the gate voltage of the field effect transistor 112 is reduced. Thus, the voltage between the nodes N9 and N8 can be controlled to a target value (for example, 19V).

  The control unit 123 predicts the life expectancy of the electrolytic capacitors 110 and 119 based on the time transition of the maximum value of the fluctuation detected by the fluctuation detecting units 122a and 122c, and outputs a signal indicating the life expectancy of the electrolytic capacitors 110 and 119. Output unit. Hereinafter, the details will be described. Note that the control unit 123 may be a computer having a processor, a memory, and a display unit.

  FIG. 2 is a diagram illustrating a configuration example of the fluctuation detection unit 122a in FIG. The fluctuation detecting unit 122a includes a peak hold unit 201, a bottom hold unit 202, a timer 203, and a difference unit 204. The timer 203 resets the values of the peak hold unit 201 and the bottom hold unit 202 every fixed time (for example, one day). The peak hold unit 201 detects the maximum value of the output voltage of the electrolytic capacitor 110 within a certain time. The bottom hold unit 202 detects the minimum value of the output voltage of the electrolytic capacitor 110 within a certain time. The difference unit 204 outputs the difference between the maximum value detected by the peak hold unit 201 and the minimum value detected by the bottom hold unit 202 to the control unit 123 as the maximum value of the fluctuation of the output voltage of the electrolytic capacitor 110.

  Next, the fluctuation detecting unit 122b of FIG. 1 will be described. The fluctuation detection unit 122b includes a peak hold unit 201, a bottom hold unit 202, a timer 203, and a difference unit 204, similarly to the above-described fluctuation detection unit 122a. The timer 203 resets the values of the peak hold unit 201 and the bottom hold unit 202 every fixed time (for example, one day). The peak hold unit 201 detects the maximum value of the output current of the electrolytic capacitor 119 within a certain time. The bottom hold unit 202 detects the minimum value of the output current of the electrolytic capacitor 119 within a certain time. The difference unit 204 outputs the difference between the maximum value detected by the peak hold unit 201 and the minimum value detected by the bottom hold unit 202 to the control unit 123 as the maximum value of the fluctuation of the output current of the electrolytic capacitor 119.

  Next, the fluctuation detecting unit 122c of FIG. 1 will be described. The fluctuation detection unit 122c includes a peak hold unit 201, a bottom hold unit 202, a timer 203, and a difference unit 204, similarly to the above-described fluctuation detection unit 122a. The timer 203 resets the values of the peak hold unit 201 and the bottom hold unit 202 every fixed time (for example, one day). The peak hold unit 201 detects the maximum value of the output voltage of the electrolytic capacitor 119 within a certain time. The bottom hold unit 202 detects a minimum value of the output voltage of the electrolytic capacitor 119 within a certain time. The difference unit 204 outputs the difference between the maximum value detected by the peak hold unit 201 and the minimum value detected by the bottom hold unit 202 to the control unit 123 as the maximum value of the fluctuation of the output voltage of the electrolytic capacitor 119.

  FIG. 3 is a graph showing the relationship between the output voltage fluctuation value of the electrolytic capacitor 110 or 119 and the capacity decrease. The vertical axis indicates the fluctuation value [mV] of the output voltage of the electrolytic capacitor 110 or 119. The horizontal axis shows the ratio [%] of the current capacity to the initial capacity of the electrolytic capacitor 110 or 119. A characteristic line 301 indicates a fluctuation value of the output voltage of the electrolytic capacitor 110 or 119 when the load (the server 124) of the power supply circuit 100 changes from 50% to 100%. A characteristic line 302 indicates a fluctuation value of the output voltage of the electrolytic capacitor 110 or 119 due to the switching of the field effect transistors 108 and 112. As shown by the characteristic line 302, even if the ratio of the current capacity to the initial capacity changes, the output voltage fluctuation value due to the switching of the field effect transistors 108 and 112 hardly changes. On the other hand, as shown by the characteristic line 301, when the ratio of the current capacity to the initial capacity changes, the output voltage fluctuation value due to the load fluctuation greatly changes. That is, if the fluctuation value of the output voltage of each of the electrolytic capacitors 110 and 119 is detected using the characteristic line 301, the ratio of the current capacity to the initial capacity of each of the electrolytic capacitors 110 and 119 can be known. For example, when the ratio of the current capacity to the initial capacity of the electrolytic capacitor is 80% or less, it may be specified that the operation is not guaranteed due to the life of the electrolytic capacitor. In this case, the life of the electrolytic capacitor can be determined using the output voltage fluctuation value (approximately 628 mV) corresponding to the ratio of the current capacity to the initial capacity of 80% (approximately 628 mV) as the threshold Va (FIG. 5). Here, in order to obtain the characteristic line 301, a load change of a predetermined value or more is required. Hereinafter, the load fluctuation will be described with reference to FIG.

  FIG. 4 is a diagram illustrating an example of a daily load change of the server 124. The horizontal axis indicates 24 hours a day. The vertical axis indicates the load of the server 124. For example, during the night, the server 124 generates a load fluctuation 401 due to the regular backup process. The load fluctuation 401 has almost the same fluctuation value every day. In the daytime, a load fluctuation 402 occurs in the server 124 due to normal business. The load fluctuation 402 changes from day to day. Therefore, the fluctuation detection units 122a to 122c only need to be able to detect the periodic and large load fluctuation 401. For example, the change detection units 122a to 122c may detect a change value every day. Due to the load fluctuation 401, the characteristic line 301 in FIG. 3 can be obtained.

  FIG. 5 is a diagram showing a time transition of the maximum value of the fluctuation of the output voltage of the electrolytic capacitor 110 or 119 for every fixed time (for example, one day). The horizontal axis indicates time. The vertical axis indicates the maximum value of the fluctuation of the output voltage of the electrolytic capacitor 110 or 119 every fixed time (for example, one day). At times t0 to t1, the maximum value of the fluctuation of the output voltage of the electrolytic capacitor 110 or 119 within a certain time is detected according to the life characteristic line 501. At time t1, the electrolytic capacitor 110 or 119 may change from the life characteristic line 501 to the life characteristic line 502 for some reason. Then, from time t1 to t2, the maximum value of the fluctuation of the output voltage of the electrolytic capacitor 110 or 119 within a certain time is detected according to the life characteristic line 502.

  Here, the threshold value Va is an output voltage fluctuation value (about 628 mV) corresponding to a ratio of the current capacity to the initial capacity of 80% in the characteristic line 301 of FIG. At time t2, the control unit 123 obtains the life characteristic line 502 by the least squares method based on the time transition from time t1 to time t2 of the maximum value of the fluctuation of the output voltage detected by the fluctuation detection units 122a and 122c, By extrapolation of the characteristic line 502, a characteristic point 503 corresponding to the threshold value Va is predicted, and a life time t3 corresponding to the characteristic point 503 is predicted. Further, the control unit 123 can predict the remaining life 504 obtained by subtracting the current time t2 from the life time t3. The remaining life 504 is the remaining life of the electrolytic capacitor 110 or 119.

  FIG. 6 is a flowchart illustrating a method of diagnosing the life of the capacitor of the power supply circuit 100. In step S601, upon confirming the stable operation, the power supply circuit 100 proceeds to step S602. In step S602, the timer 203 resets the value of the peak hold unit 201 and the value of the bottom hold unit 202 in the fluctuation detection unit 122a, and the timer 203 resets the value of the peak hold unit 201 and the bottom hold value in the fluctuation detection unit 122c. The value of the unit 202 is reset. Next, in step S603, in the fluctuation detecting unit 122b, the timer 203 resets the value of the peak hold unit 201 and the value of the bottom hold unit 202. Next, in step S604, each of the fluctuation detecting units 122a to 122c clears the value of the timer 203.

  Next, in step S605, in the fluctuation detecting unit 122a, if the current output voltage of the electrolytic capacitor 110 is larger than the internally held maximum value, the peak hold unit 201 updates the maximum value, When the current output voltage of electrolytic capacitor 110 is smaller than the internally held minimum value, hold unit 202 updates the minimum value. In the fluctuation detecting unit 122b, the peak hold unit 201 updates the maximum value when the current output current of the electrolytic capacitor 119 is larger than the internally held maximum value, and the bottom hold unit 202 When the current output current of the electrolytic capacitor 119 is smaller than the internally held minimum value, the minimum value is updated. In the fluctuation detecting unit 122c, the peak hold unit 201 updates the maximum value when the current output voltage of the electrolytic capacitor 119 is larger than the internally held maximum value, and the bottom hold unit 202 If the current output voltage of the electrolytic capacitor 119 is smaller than the internally held minimum value, the minimum value is updated.

  Next, in step S606, the fluctuation detecting units 122a to 122c each count up the value of the timer 203. Next, in step S607, the fluctuation detecting units 122a to 122c check whether or not the value of the timer 203 is larger than a certain value (for example, one day). If the value of the timer 203 is equal to or smaller than the predetermined value, the process returns to step S605, and the above processing is repeated. Thus, in the fluctuation detecting unit 122a, the peak hold unit 201 detects the maximum value of the output voltage of the electrolytic capacitor 110 at regular intervals, and the bottom hold unit 202 determines the minimum value of the output voltage of the electrolytic capacitor 110 for a constant period. Detect every time. In the fluctuation detecting unit 122b, the peak hold unit 201 detects the maximum value of the output current of the electrolytic capacitor 119 at regular intervals, and the bottom hold unit 202 determines the minimum value of the output current of the electrolytic capacitor 119 at regular intervals. To be detected. In the fluctuation detecting unit 122c, the peak hold unit 201 detects the maximum value of the output voltage of the electrolytic capacitor 119 at regular intervals, and the bottom hold unit 202 determines the minimum value of the output voltage of the electrolytic capacitor 119 at regular intervals. To be detected.

  In step S607, if the value of the timer 203 is larger than the certain value, the process proceeds to step S608. In step S608, in the variation detection unit 122a, the difference unit 204 determines the difference between the maximum value held by the peak hold unit 201 and the minimum value held by the bottom hold unit 202 as the maximum value of the change in the output voltage of the electrolytic capacitor 110. Output to the control unit 123. In the variation detecting unit 122b, the difference unit 204 determines the difference between the maximum value held by the peak hold unit 201 and the minimum value held by the bottom hold unit 202 as the maximum value of the change in the output current of the electrolytic capacitor 119. 123. In the fluctuation detecting unit 122c, the difference unit 204 determines the difference between the maximum value held by the peak hold unit 201 and the minimum value held by the bottom hold unit 202 as the maximum value of the fluctuation of the output voltage of the electrolytic capacitor 119 by the control unit. 123. Thereafter, the process returns to step S602, repeats the above processing, and proceeds to step S611.

  In step S611, the control unit 123 determines the maximum value of the fluctuation of the output voltage of the electrolytic capacitor 110 output by the fluctuation detecting unit 122a, the maximum value of the fluctuation of the output current of the electrolytic capacitor 119 output by the fluctuation detecting unit 122b, and the fluctuation detection. The maximum value of the fluctuation of the output voltage of the electrolytic capacitor 119 output from the unit 122c is recorded in an internal memory.

  Next, in step S612, the control unit 123 checks whether or not the maximum value of the fluctuation of the output current of the electrolytic capacitor 119 is larger than a specified value (threshold). If it is larger than the specified value, it means that the load fluctuation is larger than the predetermined value, and the process proceeds to step S614. If it is equal to or less than the specified value, it means that the load variation is equal to or less than the predetermined value, and the process proceeds to step S613. In step S613, since the reliability of the characteristic line 301 in FIG. 3 is low, the maximum value of the fluctuation of the output voltage of the electrolytic capacitors 110 and 119 detected within the same period as the maximum value of the fluctuation of the output current of the electrolytic capacitor 119 Is excluded from the calculation in step S614. Thereby, the accuracy of life expectancy prediction can be improved. Steps S612 and S613 can be omitted. Thereafter, the process proceeds to step S614.

  In step S614, the control unit 123 derives the life characteristic line 502 of the electrolytic capacitor 110 as shown in FIG. 5 based on the time transition of the maximum value of the fluctuation of the output voltage of the electrolytic capacitor 110. Further, the control unit 123 derives the life characteristic line 502 of the electrolytic capacitor 119 based on the time transition of the maximum value of the output voltage fluctuation of the electrolytic capacitor 119, as shown in FIG.

  Next, in step S615, the control unit 123 predicts the life characteristic point 503 by extrapolating the life characteristic line 502 of the electrolytic capacitor 110 as shown in FIG. Life expectancy 504 is predicted. Further, as shown in FIG. 5, the control unit 123 predicts the life characteristic point 503 by extrapolating the life characteristic line 502 of the electrolytic capacitor 119, and predicts the remaining life 504 of the electrolytic capacitor 119 based on the life characteristic point 503. .

  Next, in step S616, the control unit 123 checks whether the remaining life 504 of the electrolytic capacitor 110 or 119 is shorter than a specified value. If it is shorter than the specified value, the process proceeds to step S617. If it is not smaller than the specified value, the process returns to step S611.

  In step S617, the control unit 123 outputs an alarm signal indicating that the life expectancy 504 of the electrolytic capacitor 110 or 119 is shorter than a specified value, and notifies the alarm. For example, the control unit 123 can turn on an alarm by a light emitting diode (LED), display an alarm on a display, and sound an alarm by a speaker. Thereby, it is possible to notify the replacement time of the power supply circuit 100.

  As described above, in step S613, the control unit 123 determines whether the fluctuation of the output voltage detected by the fluctuation detecting units 122a and 122c when the maximum value of the fluctuation of the output current detected by the fluctuation detecting unit 122b is smaller than the threshold value. Exclude the maximum value. Then, the control unit 123 uses the time transition of the maximum value of the fluctuation of the output voltage detected by the fluctuation detection units 122a and 122c when the maximum value of the fluctuation of the output current detected by the fluctuation detection unit 122b is larger than the threshold value. The life expectancy 504 of the capacitors 110 and 119 is predicted. Then, the control unit 123 outputs a signal indicating the life expectancy 504 of the capacitors 110 and 119.

(Second embodiment)
FIG. 7 is a diagram illustrating a configuration example of a power supply system according to the second embodiment, and FIGS. 8A to 8C are diagrams illustrating current waveforms and voltage waveforms as a result of simulation. The present embodiment (FIG. 7) differs from the first embodiment (FIG. 1) in that low-pass filters 722a to 722b are provided instead of the fluctuation detecting units 122a to 122c. Hereinafter, the points of this embodiment different from the first embodiment will be described.

  The current detector 120 detects the output current of the electrolytic capacitor 119 shown in FIG. 8A, as in the first embodiment. The output current of the electrolytic capacitor 119 shown in FIG. 8A indicates a current fluctuation accompanying a load fluctuation. The voltage detector 121 detects the output voltage of the electrolytic capacitor 119 shown in FIG. 8B, as in the first embodiment. The output voltage of the electrolytic capacitor 119 shown in FIG. 8B indicates a voltage change due to a load change. A voltage waveform 801 shows a waveform obtained by enlarging the area 802, and shows a voltage fluctuation due to switching of the field effect transistors 108 and 112. Thus, it can be seen that the voltage fluctuation due to switching is much smaller than the voltage fluctuation due to load fluctuation. The voltage detector 111 detects the output voltage of the electrolytic capacitor 110, as in the first embodiment.

  The low-pass filter 722c performs low-pass filtering on the output voltage of the electrolytic capacitor 119 detected by the voltage detecting unit 121, and outputs the low-pass filtered output voltage illustrated in FIG. The voltage waveform 803 shows a waveform in which the area 804 is enlarged, and it can be seen that the voltage fluctuation due to the switching of the field-effect transistors 108 and 112 disappears, and the voltage becomes constant. The control unit 123 detects the maximum value MAX and the minimum value MIN of the output voltage shown in FIG. 8C within a certain time, and determines the difference between the maximum value MAX and the minimum value MIN as the maximum value of the fluctuation of the output voltage of the electrolytic capacitor 119. Detect as a value.

  Similarly, low-pass filter 722 a performs low-pass filtering on the output voltage of electrolytic capacitor 110 detected by voltage detecting section 111, and outputs the low-pass filtered output voltage to control section 123. The low-pass filter 722b performs low-pass filtering on the output current of the electrolytic capacitor 119 detected by the current detection unit 120, and outputs the low-pass filtered output current to the control unit 123.

  The control unit 123 performs the processing of the fluctuation detection units 122a to 122c in FIG. That is, the control unit 123 detects the maximum value of the fluctuation of the output voltage of the electrolytic capacitor 110 output from the low-pass filter 722a within a certain period of time, similarly to the fluctuation detecting unit 122a. Further, the control unit 123 detects the maximum value of the fluctuation of the output current of the electrolytic capacitor 119 output from the low-pass filter 722b within a certain period of time, similarly to the fluctuation detecting unit 122b. Further, the control unit 123 detects the maximum value of the fluctuation of the output voltage of the electrolytic capacitor 119 output from the low-pass filter 722c within a certain period of time, similarly to the fluctuation detecting unit 122c. Thereafter, the control unit 123 predicts the remaining life 504 of the electrolytic capacitors 110 and 119 and notifies an alarm, as in the first embodiment.

(Third embodiment)
FIG. 9 is a diagram illustrating a configuration example of a power supply system according to the third embodiment. The power supply system has a power supply device and a server 124. The power supply device includes a power supply circuit 100a, a diode 901a, a power supply circuit 100b, and a diode 901b. Each of the power supply circuits 100a and 100b has the same configuration as the power supply circuit 100 of FIG. The diode 901a has an anode connected to the output terminal of the power supply circuit 100a and a cathode connected to the power supply terminal of the server 124. The diode 901b has an anode connected to the output terminal of the power supply circuit 100b and a cathode connected to the power supply terminal of the server 124. The power supply circuits 100a and 100b supply a power supply voltage to the server 124. A voltage waveform 902a indicates a waveform of an output voltage of the power supply circuit 100a. A voltage waveform 902b indicates a waveform of an output voltage of the power supply circuit 100b. When the server 124 always keeps a medium load or a heavy load like a cloud server, the output voltage of one of the power supply circuits 100a and 100b is intentionally fluctuated during a certain period, so that the load of the server 124 is changed. Is varied. With this load change, the maximum value of the change in the output voltage of the electrolytic capacitors 110 and 119 can be obtained. Thereafter, the power supply circuit 100b may return the output voltage to a constant value.

(Fourth embodiment)
FIG. 10A is a diagram illustrating a configuration example of a power supply system according to the fourth embodiment. The power supply system includes a management server 1001 and a server group 1002. The server group 1002 includes a plurality of power supply circuits (power supply devices) 1003a to 1003d and a plurality of servers 1004a to 1004d. Each of the plurality of power supply circuits 1003a to 1003d has the configuration of the power supply circuit 100 in FIG. 7, and supplies a power supply voltage to the plurality of servers 1004a to 1004d. However, the management server 1001 performs the processing of the control unit 123 in FIG. The management server 1001 is a control device, and allocates a plurality of virtual machines VM to a plurality of servers 1004a to 1004d.

The management server 1001 detects the maximum value of the fluctuation of the output voltages of the capacitors 110 and 119 accompanying the load fluctuation of the electrolytic capacitors 110 and 119 of the plurality of power supply devices 1003a to 1003d at regular intervals. Then, the management server 1001 predicts the remaining lives 504 of the electrolytic capacitors 110 and 119 of the plurality of power supply circuits 1003a to 1003d, respectively, based on the detected time change of the maximum value of the output voltage fluctuation. Then, the management server 1001, at the time of load fluctuation, assign multiple virtual machines VM to multiple servers 1004a~1004d depending on life expectancy 504 of the electrolytic capacitor 110 and 11 9 of a plurality of power supply circuits 1003a~1003d that the prediction.

  For example, FIG. 10A illustrates an example in which the management server 1001 allocates virtual machines VM in the servers 1004a to 1004d due to heavy load. When the load switches from the heavy load to the light load after the state shown in FIG. 10A, the management server 1001 performs a virtual operation on the servers 1004a to 1004d to reduce the power consumption as shown in FIG. 10B. Reassign the machine VM. At this time, the management server 1001 reduces the number of virtual machines VM in the server 1004d to which the power supply voltage is supplied from the power supply circuit 1003d having the short life expectancy 504 from three to two. That is, the management server 1001 has priority over the servers 1004a to 1004c to which the power supply voltage is supplied from the power supply circuits 1003a to 1003c having the longer life expectancy 504, than the server 1004d to which the power supply voltage is supplied from the power supply circuit 1003d having the shorter life expectancy 504. A virtual machine VM is allocated. Thus, the frequency of use of the server 1004d corresponding to the power supply circuit 1003d having low reliability can be reduced. Then, the frequency of use of the power supply circuit 1003d is reduced, and the reduction in the life expectancy 504 of the power supply circuit 1003d can be delayed. As a result, the life expectancy of all power supply circuits 1003a to 1003d can be equalized, and the cost of power supply circuit replacement can be reduced.

  When the load is switched from the light load to the heavy load after the state of FIG. 10B, the management server 1001 virtualizes the servers 1004a to 1004d to reduce power consumption as shown in FIG. Reassign the machine VM. At this time, the management server 1001 reduces the number of virtual machines VM in the server 1004d to which the power supply voltage is supplied from the power supply circuit 1003d having the short life expectancy 504 from two to zero. That is, the management server 1001 has priority over the servers 1004a to 1004c to which the power supply voltage is supplied from the power supply circuits 1003a to 1003c having the longer life expectancy 504, than the server 1004d to which the power supply voltage is supplied from the power supply circuit 1003d having the shorter life expectancy 504. A virtual machine VM is allocated. When the number of virtual machines VM allocated to the server 1004d becomes 0, the power supply circuit 1003d and the server 1004d are stopped, and the power supply circuit 1003d with a short life expectancy 504 can be replaced.

  As described above, according to the present embodiment, the virtual machines VM are preferentially assigned to the servers 1004a to 1004c corresponding to the power supply circuits 1003a to 1003c having a long life expectancy 504, thereby leveling the life expectancy 504 of the power supply circuits 1003a to 1003d. As a result, power supply circuit replacement costs can be reduced.

  Further, by repeating the above-described reallocation of the virtual machine VM over a long period of time, the server 1004d corresponding to the power supply circuit 1003d having a short life expectancy 504 and having a high maintenance priority increases the frequency of being in a stopped state, and performs maintenance. It is not necessary to move the virtual machine VM or stop the server 1004d again, so that the maintenance cost can be reduced.

  Also, for a user who uses the servers 1004a to 1004d as a data center, it is possible to reduce the possibility of failure of the power supply circuits 1003a and 1003b corresponding to the servers 1004a and 1004b in which the virtual machines VM are operating, thereby improving reliability. Can be. In addition, a virtual machine VM of a user who pays a higher charge with an emphasis on reliability can be preferentially assigned to the servers 1004a to 1004c corresponding to the power supply circuits 1003a to 1003c having a longer life expectancy 504. In addition, the server 1004d corresponding to the power supply circuit 1003d having a short life expectancy 504 is allocated with a virtual machine VM of a user who permits the temporary stop of the virtual machine VM with emphasis on cost, thereby eliminating excessive redundancy. And contribute to the improvement of profit and loss in the entire data center.

(Fifth embodiment)
FIG. 11A is a diagram illustrating a configuration example of a part of the control unit 123 in FIGS. 1 and 7 according to the fifth embodiment. The control unit 123 includes a microcomputer 1100, low-pass filters 1101 and 1107, gain units 1102, 1105 and 1108, analog-digital converters 1103, 1106 and 1109, and a target voltage unit 1104. As illustrated in FIG. 11C, the microcomputer 1100 is a computer, and includes a digital signal processor (DSP) 1121, a timer 1122, a ROM 1123, and a RAM 1124. The DSP 1121 performs digital signal processing. The timer 1122 counts a timer value. The ROM 1123 stores programs and the like. The RAM 1124 is a working area of the DSP 1121. The DSP 1121 executes a program in the ROM 1123 to perform various processes including the processes of the capacitor life diagnosing method of the first to fourth embodiments and the processes of the functional modules 1110 to 1115 in FIG. The microcomputer 1100 includes a subtraction unit 1110, a compensator 1111, a reduction ratio calculation unit 1112, a timer 1113, a duty ratio change unit 1114, and a pulse width modulation (PWM) unit 1115 as function modules of a program.

  1 and 7 detects the output voltage Vo1 of the electrolytic capacitor 119. The low-pass filter 1101 attenuates and outputs a component of a frequency higher than the cutoff frequency in the output voltage Vo1 detected by the voltage detection unit 121. Gain section 1102 outputs a voltage obtained by multiplying output voltage of low-pass filter 1101 by gain k1. The analog-to-digital converter 1103 converts the output voltage of the gain unit 1102 from analog to digital, and outputs a digital output voltage Vd1 to the microcomputer 1100.

  The target voltage section 1104 outputs a target voltage Vt1. The target voltage Vt1 is, for example, 19V. Gain section 1105 outputs a voltage obtained by multiplying target voltage Vt1 by gain k2. The analog-to-digital converter 1106 converts the output voltage of the gain unit 1105 from analog to digital, and outputs a digital target voltage Vd2 to the microcomputer 1100.

  Subtraction unit 1110 subtracts digital output voltage Vd1 from digital target voltage Vd2, and outputs the result of the subtraction. The compensator 1111 is a duty ratio calculator, and calculates the duty ratio of the gate voltage Vg1 of the field effect transistor 112 based on the output value of the subtractor 1110. The duty ratio of the gate voltage Vg1 is a value obtained by dividing the high level time of the gate voltage Vg1 by the cycle of the gate voltage Vg1. The duty ratio changing unit 1114 normally outputs the duty ratio calculated by the compensator 1111 to the PWM unit 1115 without changing the duty ratio. The PWM unit 1115 outputs the gate voltage Vg <b> 1 subjected to pulse width modulation to the gate of the field effect transistor 112 based on the duty ratio output from the duty ratio changing unit 1114. Thereby, the microcomputer 1100 generates the gate voltage Vg1 such that the output voltage Vo1 approaches the target voltage Vt1.

  In the first to fourth embodiments, the control unit 123 detects the maximum value of the fluctuation of the output voltage Vo1 of the electrolytic capacitor 119 due to a sudden change in the load of the electrolytic capacitor 119. However, the control unit 123 operates constantly at a constant output voltage Vo1. In such a case, it is difficult to predict the life expectancy of the electrolytic capacitor 119. In this embodiment, the microcomputer 1100 forcibly changes the pulse width (duty ratio) of the gate voltage Vg1 of the field effect transistor 112 by one pulse during the stable operation, as shown in FIG. The same fluctuation of the output voltage Vo1 is generated. However, the change amount of the duty ratio is determined based on the output current Io1 and the duty ratio at that time so as not to deviate from the required specifications of the load (server 124). Hereinafter, a method of forcibly changing the pulse width of the gate voltage Vg1 by one pulse will be described.

  1 and 7 detects the output current Io1 of the electrolytic capacitor 119. The low-pass filter 1107 attenuates and outputs a component of a frequency higher than the cutoff frequency in the output current Io1 detected by the current detection unit 120. Gain section 1108 outputs a current obtained by multiplying output current of low-pass filter 1107 by gain k1. The analog-to-digital converter 1109 converts the output current of the gain unit 1108 from analog to digital, and outputs a digital output current to the microcomputer 1100.

  Reduction rate calculator 1112 calculates reduction rate β of the duty ratio of gate voltage Vg1, based on the digital output current output from analog-to-digital converter 1109 and the duty ratio output from compensator 1111. The duty ratio changing unit 1114 reduces the duty ratio by one pulse based on the reduction ratio β with respect to the duty ratio output from the compensator 1111. The PWM unit 1115 outputs a gate voltage Vg1 whose duty ratio has been reduced by one pulse based on the duty ratio output by the duty ratio changing unit 1114, as shown in FIG. 11B.

  FIG. 12A is a diagram showing voltages 1201 to 1203 corresponding to the duty ratio output by duty ratio changing section 1114. The voltage 1201 is a voltage when the output current Io1 is 10 A. The voltage 1202 is a voltage when the output current Io1 is 20 A. The voltage 1203 is a voltage when the output current Io1 is 30 A. The duty ratio changing unit 1114 lowers the voltages 1201 to 1203 corresponding to the duty ratio only during the period 1204 to reduce the duty ratio.

  FIG. 12B is a diagram showing waveforms of output voltages 1211 to 1213 of the electrolytic capacitor 119. The output voltage 1211 is the output voltage Vo1 when the output current Io1 is 10 A. The output voltage 1212 is the output voltage Vo1 when the output current Io1 is 20 A. The output voltage 1213 is the output voltage Vo1 when the output current Io1 is 30 A. When the voltages 1201 to 1203 corresponding to the duty ratio shown in FIG. 12A decrease, the output voltages 1211 to 1213 shown in FIG. 12B also decrease. Thus, the output voltages 1211 to 1213 fluctuate in the same manner as in the case of the sudden load change.

  FIG. 12C is a diagram illustrating waveforms of the voltages 1221 to 1223 output from the low-pass filter 1101. The voltage 1221 is the output voltage of the low-pass filter 1101 when the output current Io1 is 10 A. The output voltage 1222 is the output voltage of the low-pass filter 1101 when the output current Io1 is 20 A. The output voltage 1223 is the output voltage of the low-pass filter 1101 when the output current Io1 is 30 A. When the voltages 1201 to 1203 corresponding to the duty ratio shown in FIG. 12A decrease, the voltages 1221 to 1223 shown in FIG. 12C also decrease.

  Note that the number of pulses for reducing the duty ratio is not limited to one, and the duty ratio of a plurality of consecutive pulses may be reduced. Instead of reducing the duty ratio, the duty ratio may be increased.

The power supply circuit 100 reduces the output power P1 to the output power P2 when the duty ratio is β times n cycles. The power fluctuation ΔP is represented by the following equation (1).
ΔP = P1−P2 = n × (1−β) × P1 (1)

FIGS. 12A to 12C show the case where n = 1 and β = 1/4. If n is small, the compensator 1111 does not respond, and the insufficient current is drawn from the electrolytic capacitor 119. Further, the voltage fluctuation ΔV of the output voltage Vo1 is first-order approximated based on the capacitance value C of the electrolytic capacitor 119, the resistance value R of the ESR 1315, the output voltage Vo1, and the period T1 of the gate voltage Vg1 in FIG. It is represented by (2).
ΔV = Vo1 − {[Vo1 ² − {(2 / C) × (1−β) × P1 × n × T1}]
+ R × (1-β) × P1 / Vo1 (2)

  By determining the pulse number n and the reduction ratio β so that the voltage fluctuation ΔV falls within the standard of the power supply circuit 100, the life expectancy of the electrolytic capacitor 119 can be predicted without affecting the load (server 124). Can be.

FIG. 13A is a diagram illustrating a structural example of the electrolytic capacitor 119. The electrolytic capacitor 119 has an anode foil 1301, a dielectric (Al ₂ O ₃ ) 1302, an electrolyte solution 1303, an electrolytic paper 1304, and a cathode foil 1305.

  FIG. 13B is a diagram illustrating an equalizing circuit of the electrolytic capacitor 119. The electrolytic capacitor 119 has an inductor 1311, a diode 1312, a capacitor 1313, a resistor 1314, a resistor 1315, a diode 1316, a capacitor 1317, a resistor 1318, and an inductor 1319. The resistor 1315 is an equalized series resistance (ESR).

  FIG. 13C is a diagram for explaining a method of determining the reduction ratio β, and shows the relationship between the resistance value of the ESR 1315 and the voltage fluctuation ΔV when the output current Io1 is 10 A, 20 A, 30 A, and 40 A. For example, the power supply circuit 100 is required to have a specification that the absolute value of the voltage fluctuation ΔV is 600 mV or less and a specification that the resistance value of the ESR 1315 is 20 mΩ or less. It is necessary to determine the reduction ratio β so as to satisfy this specification. For example, if the steady-state output current Io1 is 20 A, the reduction ratio β may be determined to be a value equal to or more than ４. In this case, the duty ratio changing unit 1114 changes the duty ratio from 40% to 10%, for example. Thus, the life expectancy of the electrolytic capacitor 119 can be predicted without affecting the load (the server 124). When the output current Io1 is larger than 20 A, the reduction ratio β may be set to a larger value.

  FIGS. 14A and 14B are flowcharts illustrating a processing example of the microcomputer 1100. This process is performed once at regular intervals (for example, one day). In step S1401, the reduction ratio calculation unit 1112 obtains the duty ratio D from the compensator 1111 and obtains a digital output current from the analog-to-digital converter 1109. Next, in step S1402, the reduction ratio calculation unit 1112 calculates the average duty ratio D_ave so far based on the current duty ratio D. Next, in step S1403, the reduction ratio calculation unit 1112 calculates the absolute value of the difference between the average duty ratio D_ave and the duty ratio D as the variation D_err. Next, in step S1404, the reduction ratio calculation unit 1112 proceeds to step S1405 if the variation D_err is greater than the threshold, and proceeds to step S1406 if the variation D_err is equal to or less than the threshold. In step S1405, the timer 1113 resets the timer value T2 to 0, and starts counting the timer value T2. After that, since the voltage fluctuation ΔV of the output voltage Vo1 is large, the reduction ratio calculation unit 1112 ends the process without determining the reduction ratio β. This makes it possible to reduce the duty ratio when the fluctuation of the output voltage Vo1 is large, and prevent the absolute value of the voltage fluctuation ΔV of the output voltage Vo1 from exceeding the specification of 600 mV.

  In step S1406, if the timer value T2 is equal to or less than the stabilization time, the fluctuation of the output voltage Vo1 has not been stabilized yet, so the processing returns to step S1401 and the above processing is repeated. When the timer value T2 is longer than the stabilization time, the reduction ratio calculation unit 1112 advances the process to step S1411 because the fluctuation of the output voltage Vo1 is stable.

  In step S1411, the reduction ratio calculation unit 1112 calculates a reduction ratio β satisfying the specifications based on the duty ratio D obtained from the compensator 1111 and the digital output current obtained from the analog-to-digital converter 1109. Next, in step S1412, the duty ratio changing unit 1114 multiplies the duty ratio D by the reduction ratio β to change the duty ratio for n pulses. Next, in step S1413, the PWM unit 1115 outputs the gate voltage Vg1 in which the duty ratio for n pulses is reduced based on the duty ratio changed by the duty ratio changing unit 1114. As a result, the output voltage Vo1 fluctuates, so that the control unit 123 predicts the remaining life of the electrolytic capacitor 119 as in the first to fourth embodiments.

  As described above, the field effect transistor 112 is a switch that supplies power to the electrolytic capacitor 119. The compensator 1111 is a duty ratio calculator, and calculates the duty ratio of the gate voltage (control pulse) Vg1 of the field effect transistor 112 so that the output voltage Vo1 of the electrolytic capacitor 119 approaches the target voltage (target value) Vt1. The duty ratio changing unit 1114 and the PWM unit 1115 are pulse generation units, change the duty ratio calculated by the compensator 1111 by one pulse or a plurality of pulses, and change the duty ratio of the field effect transistor 112 based on the changed duty ratio. A gate voltage Vg1 is generated. The fluctuation detecting unit 122c in FIG. 1 detects the maximum value of the fluctuation of the output voltage Vo1 of the electrolytic capacitor 119 due to the change in the duty ratio. The control unit 123 predicts the remaining life of the electrolytic capacitor 119 based on the detection result of the fluctuation detection unit 122c.

(Sixth embodiment)
FIG. 15A is a diagram illustrating a configuration example of a part of the control unit 123 in FIGS. 1 and 7 according to the sixth embodiment. In the fifth embodiment, an example in which the control unit 123 controls the gate voltage Vg1 of the field-effect transistor 112 has been described. However, in the sixth embodiment, the control unit 123 controls the gate voltage Vg2 of the field-effect transistor 108. An example will be described. Hereinafter, a point of difference in FIG. 15A compared with FIG. 11A will be described.

  1 and 7 detects the output voltage Vo2 of the electrolytic capacitor 110. The low-pass filter 1101 attenuates and outputs a component having a frequency higher than the cutoff frequency in the output voltage Vo2 detected by the voltage detection unit 111. Gain section 1102 outputs a voltage obtained by multiplying output voltage of low-pass filter 1101 by gain k1. The analog-to-digital converter 1103 converts the output voltage of the gain unit 1102 from analog to digital, and outputs a digital output voltage Vd1 to the microcomputer 1100.

  Target voltage section 1104 outputs target voltage Vt2. The target voltage Vt2 is, for example, 400V. Gain section 1105 outputs a voltage obtained by multiplying target voltage Vt2 by gain k2. The analog-to-digital converter 1106 converts the output voltage of the gain unit 1105 from analog to digital, and outputs a digital target voltage Vd2 to the microcomputer 1100.

  1 and 7 detects the output current Io2 of the electrolytic capacitor 110. The low-pass filter 1107 attenuates and outputs a component having a frequency higher than the cutoff frequency in the output current Io2 detected by the current detection unit 125. Gain section 1108 outputs a current obtained by multiplying output current of low-pass filter 1107 by gain k1. The analog-to-digital converter 1109 converts the output current of the gain unit 1108 from analog to digital, and outputs a digital output current to the microcomputer 1100.

  The microcomputer 1100 outputs the gate voltage Vg2 of the field-effect transistor 108 based on the digital output current, the digital output voltage Vd1, and the digital target voltage Vd2 output from the analog-to-digital converter 1109, as in the fifth embodiment. Subtraction unit 1110 subtracts digital output voltage Vd1 from digital target voltage Vd2, and outputs the result of the subtraction. Compensator 1111 calculates the duty ratio of gate voltage Vg2 of field effect transistor 108 based on the output value of subtraction unit 1110. The PWM unit 1115 outputs the gate voltage Vg2 pulse-width modulated to the gate of the field-effect transistor 108 based on the duty ratio output from the duty ratio changing unit 1114. Thereby, the microcomputer 1100 generates the gate voltage Vg2 such that the output voltage Vo2 approaches the target voltage Vt2. The duty ratio changing unit 1114 changes the duty ratio of a plurality of continuous pulses.

  The AC voltage 1501 in FIG. 15B is an AC voltage output from the AC power supply 101 and has a cycle of 20 ms. 1 and 7 is a power factor improving circuit for improving the power factor of the AC voltage 1501, and is required to have a momentary interruption resistance from a half cycle (10 ms) to one cycle (20 ms) of the AC voltage 1501. Therefore, the capacity of the electrolytic capacitor 110 is very large. Therefore, the fluctuation of the output voltage Vo2 of the electrolytic capacitor 110 cannot be detected to the extent that the control unit 123 reduces the duty ratio of several pulses of the gate voltage Vg2 of the field effect transistor 108. In order to vary the output voltage Vo2 of the electrolytic capacitor 110, it is necessary to reduce the duty ratio of the gate voltage Vg2 of the field effect transistor 108 by a reduction rate β with a plurality of pulses in a period equal to or longer than the threshold. The reduction ratio calculation unit 1112 outputs, for example, the reduction ratio β = 1/4 to the duty ratio change unit 1114. For example, as shown in FIG. 15B, the duty ratio changing unit 1114 reduces the voltage 1503 corresponding to the duty ratio in a first period of 5 ms near the peak of the AC voltage 1501. The PWM unit 1115 generates the gate voltage Vg2 having a narrow pulse width in the first period of 5 ms. Accordingly, the on-time of the field effect transistor 108 is shortened, and the output voltage 1502 of the electrolytic capacitor 110 fluctuates. The control unit 123 can predict the remaining lives of the electrolytic capacitors 110 and 119 based on the fluctuation of the output voltage 1502, as in the first to fourth embodiments.

  As described above, the compensator 1111 is a duty ratio calculator, and the duty of the gate voltage (control pulse) Vg2 of the field effect transistor 108 is set so that the output voltage Vo2 of the electrolytic capacitor 110 approaches the target voltage (target value) Vt2. Calculate the ratio. The duty ratio changing unit 1114 and the PWM unit 1115 are pulse generating units, and change the duty ratio calculated by the compensator 1111 for the first period, and use the gate of the field effect transistor 108 based on the changed duty ratio. A voltage Vg2 is generated. 1 detects a maximum value of a change in output voltage Vo2 of electrolytic capacitor 110 due to a change in the duty ratio. Fluctuation detecting section 122c detects the maximum value of the fluctuation of output voltage Vo1 of electrolytic capacitor 119 due to the change of the duty ratio. The control unit 123 predicts the remaining life of the electrolytic capacitor 110 based on the detection result of the fluctuation detecting unit 122a, and predicts the remaining life of the electrolytic capacitor 119 based on the detection result of the fluctuation detecting unit 122c.

  The microcomputer 1100 of the present embodiment can be realized by a computer executing a program. Further, a computer-readable recording medium on which the above-mentioned program is recorded and a computer program product such as the above-mentioned program can also be applied as an embodiment of the present invention. As the recording medium, for example, a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a magnetic tape, a nonvolatile memory card, a ROM, and the like can be used.

  It should be noted that each of the above-described embodiments is merely an example of a concrete example for carrying out the present invention, and the technical scope of the present invention should not be interpreted in a limited manner. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features.

REFERENCE SIGNS LIST 100 power supply circuit 101 AC power supply 102 rectifier circuit 103 to 106 diode 107 inductor 108 n-channel field-effect transistor 109 diode 110 electrolytic capacitor 111 voltage detector 112 n-channel field-effect transistor 113 transformer 114 primary winding 115 secondary winding 116, 117 Diode 118 Inductor 119 Electrolytic capacitor 120 Current detector 121 Voltage detectors 122a to 122c Fluctuation detector 123 Controller 124 Server

Claims (10)

A first fluctuation detection unit that detects a maximum value of the fluctuation of the output voltage of the first capacitor at regular intervals;
An output for predicting the life expectancy of the first capacitor based on a time transition of the maximum value of the fluctuation of the output voltage detected by the first fluctuation detection unit, and outputting a signal indicating the life expectancy of the first capacitor; Department and
And a second variation detecting unit that detects the maximum value of the variation of the output current of the first capacitor for each of the predetermined time,
The output unit calculates a maximum value of the fluctuation of the output voltage detected by the first fluctuation detection unit when a maximum value of the fluctuation of the output current detected by the second fluctuation detection unit is smaller than a threshold value. Time transition of the maximum value of the fluctuation of the output voltage detected by the first fluctuation detecting section when the maximum value of the fluctuation of the output current detected by the second fluctuation detecting section is larger than the threshold value The life expectancy of the first capacitor is predicted based on the following equation, and a signal indicating the life expectancy of the first capacitor is output. A first fluctuation detection unit that detects a maximum value of the fluctuation of the output voltage of the first capacitor at regular intervals;
An output for predicting the life expectancy of the first capacitor based on a time transition of the maximum value of the fluctuation of the output voltage detected by the first fluctuation detection unit, and outputting a signal indicating the life expectancy of the first capacitor; Part and
The capacitor life diagnostic device according to claim 1, wherein the first fluctuation detecting unit detects a maximum value of a fluctuation of an output voltage of the first capacitor due to a fluctuation of a load of the first capacitor at regular intervals. The first capacitor outputs a voltage to a load;
A power supply circuit that outputs a voltage to the load;
3. The apparatus according to claim 2, wherein the power supply circuit varies the load by varying an output voltage. A first fluctuation detection unit that detects a maximum value of the fluctuation of the output voltage of the first capacitor at regular intervals;
An output for predicting the life expectancy of the first capacitor based on a time transition of the maximum value of the fluctuation of the output voltage detected by the first fluctuation detection unit, and outputting a signal indicating the life expectancy of the first capacitor; Department and
A switch for supplying power to the first capacitor;
A duty ratio calculator for calculating a duty ratio of a control pulse of the switch so that an output voltage of the first capacitor approaches a target value;
A pulse generation unit that changes the calculated duty ratio by one pulse or a plurality of pulses, and generates a control pulse of the switch based on the changed duty ratio;
The capacitor life diagnostic device, wherein the first fluctuation detecting unit detects a maximum value of a fluctuation of an output voltage of the first capacitor accompanying a change of the duty ratio. A first fluctuation detection unit that detects a maximum value of the fluctuation of the output voltage of the first capacitor at regular intervals;
An output for predicting the life expectancy of the first capacitor based on a time transition of the maximum value of the fluctuation of the output voltage detected by the first fluctuation detection unit, and outputting a signal indicating the life expectancy of the first capacitor; Department and
A transformer that includes a primary winding and a secondary winding, transforms the voltage of the primary winding, and outputs the transformed voltage to the secondary winding;
A first rectifier circuit that rectifies the voltage of the secondary winding of the transformer and outputs the rectified voltage to the first capacitor;
A second rectifier circuit for rectifying the AC voltage;
A second capacitor to which a voltage rectified by the second rectifier circuit is applied;
A third fluctuation detecting unit that detects a maximum value of the fluctuation of the output voltage of the second capacitor;
A first transistor connected between the second rectifier circuit and the primary winding of the transformer;
A duty ratio calculator for calculating a duty ratio of a control pulse of the first transistor so that an output voltage of the first capacitor approaches a target value;
A pulse generation unit that changes the calculated duty ratio by one pulse or a plurality of pulses, and generates a control pulse of the first transistor based on the changed duty ratio;
The transformer transforms an output voltage of the second capacitor;
The output unit predicts a life expectancy of the second capacitor based on a time transition of a maximum value of the fluctuation of the output voltage detected by the third fluctuation detection unit, and indicates a life expectancy of the second capacitor. Output a signal,
The capacitor life diagnostic device, wherein the first fluctuation detecting unit detects a maximum value of a fluctuation of an output voltage of the first capacitor accompanying a change of the duty ratio. A first fluctuation detection unit that detects a maximum value of the fluctuation of the output voltage of the first capacitor at regular intervals;
An output for predicting the life expectancy of the first capacitor based on a time transition of the maximum value of the fluctuation of the output voltage detected by the first fluctuation detection unit, and outputting a signal indicating the life expectancy of the first capacitor; Department and
A transformer that includes a primary winding and a secondary winding, transforms the voltage of the primary winding, and outputs the transformed voltage to the secondary winding;
A first rectifier circuit that rectifies the voltage of the secondary winding of the transformer and outputs the rectified voltage to the first capacitor;
A second rectifier circuit for rectifying the AC voltage;
A second capacitor to which a voltage rectified by the second rectifier circuit is applied;
A third fluctuation detecting unit that detects a maximum value of the fluctuation of the output voltage of the second capacitor;
A second transistor having a source connected to the ground potential node;
An inductor connected between the second rectifier circuit and the drain of the second transistor;
A diode having an anode connected to the drain of the second transistor and a cathode connected to the second capacitor;
A duty ratio calculator for calculating a duty ratio of a control pulse of the second transistor so that an output voltage of the second capacitor approaches a target value;
A pulse generator that changes the calculated duty ratio only for a first period, and generates a control pulse for the second transistor based on the changed duty ratio;
The transformer transforms an output voltage of the second capacitor;
The output unit predicts a life expectancy of the second capacitor based on a time transition of a maximum value of the fluctuation of the output voltage detected by the third fluctuation detection unit, and indicates a life expectancy of the second capacitor. Output a signal,
The third variation detecting unit detects a maximum value of a variation of an output voltage of the second capacitor according to a change of the duty ratio. A first fluctuation detection unit that detects a maximum value of the fluctuation of the output voltage of the first capacitor at regular intervals;
An output for predicting the life expectancy of the first capacitor based on a time transition of the maximum value of the fluctuation of the output voltage detected by the first fluctuation detection unit, and outputting a signal indicating the life expectancy of the first capacitor; Department and
A transformer that includes a primary winding and a secondary winding, transforms the voltage of the primary winding, and outputs the transformed voltage to the secondary winding;
A first rectifier circuit that rectifies the voltage of the secondary winding of the transformer and outputs the rectified voltage to the first capacitor;
A second rectifier circuit for rectifying the AC voltage;
A second capacitor to which a voltage rectified by the second rectifier circuit is applied;
A third fluctuation detecting unit that detects a maximum value of the fluctuation of the output voltage of the second capacitor;
A second transistor having a source connected to the ground potential node;
An inductor connected between the second rectifier circuit and the drain of the second transistor;
A diode having an anode connected to the drain of the second transistor and a cathode connected to the second capacitor;
A duty ratio calculator for calculating a duty ratio of a control pulse of the second transistor so that an output voltage of the second capacitor approaches a target value;
A pulse generator that changes the calculated duty ratio only for a first period, and generates a control pulse for the second transistor based on the changed duty ratio;
The transformer transforms an output voltage of the second capacitor;
The output unit predicts a life expectancy of the second capacitor based on a time transition of a maximum value of the fluctuation of the output voltage detected by the third fluctuation detection unit, and indicates a life expectancy of the second capacitor. Output a signal,
The capacitor life diagnostic device, wherein the first fluctuation detecting unit detects a maximum value of a fluctuation of an output voltage of the first capacitor accompanying a change of the duty ratio. Multiple servers,
A control device that allocates a plurality of virtual machines to the plurality of servers;
A plurality of power supply devices for supplying a power supply voltage to each of the plurality of servers,
Each of the plurality of power supply devices has a first capacitor that outputs a charged voltage,
The control device detects the maximum value of the fluctuation of the output voltage of the first capacitor of each of the plurality of power supply devices at regular time intervals, and based on the time transition of the detected maximum value of the fluctuation of the output voltage. Predicting a life expectancy of the first capacitor of the plurality of power supplies, and allocating a plurality of virtual machines to the plurality of servers according to the predicted life expectancy of the first capacitor of the plurality of power supplies. Power supply system characterized by the following. A first variation detection unit that detects a maximum value of the variation of the output voltage of the first capacitor at regular intervals,
A second variation detection unit that detects a maximum value of the variation of the output current of the first capacitor at the predetermined time intervals,
The output unit excludes the maximum value of the output voltage fluctuation detected by the first fluctuation detection unit when the maximum value of the fluctuation of the output current detected by the second fluctuation detection unit is smaller than a threshold value. The time transition of the maximum value of the fluctuation of the output voltage detected by the first fluctuation detecting section when the maximum value of the fluctuation of the output current detected by the second fluctuation detecting section is larger than the threshold value; And estimating a life expectancy of the first capacitor and outputting a signal indicating the life expectancy of the first capacitor based on the life expectancy of the first capacitor. Detecting the maximum value of the fluctuation of the output voltage of the first capacitor at regular intervals,
Detecting the maximum value of the variation of the output current of the first capacitor at each of the fixed time intervals,
Except for the detected maximum value of the fluctuation of the output voltage when the detected maximum value of the fluctuation of the output current is smaller than a threshold value, the detected maximum value of the fluctuation of the output current is larger than the threshold value. Predicting the life expectancy of the first capacitor based on the time transition of the maximum value of the detected fluctuation of the output voltage in the case, and outputting a signal indicating the life expectancy of the first capacitor;
A program that causes a computer to execute processing.

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