JP2006217753A - Power supply device and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it possible to reduce rush current to a capacitor on the direct current side and reduce rush current when alternating-current input is turned on and off in a short time. <P>SOLUTION: A rectifier DC that rectifies inputted alternating-current voltage and a smoothing capacitor C1 are provided. A parallel circuit of a resistor R1 for suppressing rush current and a relay contact RL1 for short-circuiting this resistor is connected between the rectifier DC and the capacitor C1. A short-circuiting control circuit Vd1 detects the voltage of the capacitor C1 and controls turn-on/off of the relay contact RL1. The short-circuiting control circuit Vd1 takes a voltage equivalent to 2/3 of the saturation voltage of the capacitor C1 as threshold voltage, and controls and switches the relay contact RL1 from on to off when the voltage of the capacitor C1 becomes equal to or lower than the threshold voltage. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a power supply device and an electronic apparatus, and in particular, it is possible to reduce an inrush current to a DC-side capacitor in a power supply device that converts alternating current to direct current, and to turn off / on an alternating current input in a short time. The present invention relates to a power supply device that can reduce an inrush current in the case of the failure and an electronic device using the same.

  Various methods have been proposed as conventional techniques that can reduce inrush current in a power supply device. The one described in Patent Document 1 is to turn on the short-circuit means of the inrush current reduction resistor connected to the capacitor when the input voltage and the charging voltage of the capacitor are equal to or higher than a predetermined value. . Further, the one described in Patent Document 2 is to reduce the inrush current by inserting a choke in series with the capacitor, and the one described in Patent Document 3 is a switch and a heating element that are short-circuited when the power is turned off. Are connected to the output in series, and the switch that short-circuits the inrush current reduction resistor when the heat generating element generates heat is controlled to be turned off.

  In addition, the device described in Patent Document 4 monitors the terminal voltage and the input voltage of the capacitor and short-circuits the inrush current reducing resistor. The device described in Patent Document 5 includes an inrush current reducing resistor and FETs are connected in series to provide protection when power is turned on again in a short time. In addition, the device described in Patent Document 6 is provided with a thermal resistor and a power resistor in series as an inrush current reduction resistor to suppress an inrush current when the power supply is restarted in a short time.

Further, the one described in Patent Document 7 is to reduce the inrush current flowing to the load side of the DC output by the current limiting means and the bypass means, and the one described in Patent Document 8 is an inrush current reducing resistor. In the patent document 9 detects that the voltage is supplied to the load on the secondary side and opens the short circuit of the inrush current reduction resistor on the primary side. Is.
Japanese Patent Laid-Open No. 5-30746 JP-A-5-236762 Japanese Utility Model Publication No. 6-5391 Japanese Unexamined Patent Publication No. 7-99775 JP-A-8-140260 JP-A-8-182187 Japanese Patent Laid-Open No. 9-212042 Japanese Patent No. 2919363 Japanese Patent Laid-Open No. 11-243686

  None of the above-mentioned conventional techniques considers turning off the relay contact that short-circuits the resistor for reducing the inrush current. Therefore, after turning off the input switch of the power supply device, the input switch is turned on again several seconds later. In this case, since the relay contact or the like remains ON, there is a problem that an inrush current flows through the smoothing capacitor. As a result, the power supply device according to the conventional technique may cause the relay contact to be welded, and causes a problem that the voltage fluctuation of the commercial AC power supply is caused to adversely affect other electronic devices.

  The object of the present invention is to solve the above-mentioned problems of the prior art and reliably reduce the inrush power to the smoothing capacitor even when the power switch is frequently turned on and off. Another object of the present invention is to provide a power supply device that does not cause adverse effects on other electronic devices by causing voltage fluctuations of commercial AC power supply, and an electronic device using the same.

  In order to achieve the above object, according to a first aspect of the present invention, there is provided a power supply apparatus including a rectifier that rectifies an input AC voltage and a smoothing capacitor, and is connected in series to a charging current circuit of the smoothing capacitor. An inrush current reduction circuit in which an inrush current reducing resistor for suppressing an inrush current and a short-circuit switch for short-circuiting the resistor are connected in parallel, and the voltage of the smoothing capacitor is detected to turn on the short-circuit switch. A short-circuit control circuit for controlling / OFF, wherein the short-circuit control circuit uses a voltage that is 2/3 of the saturation voltage of the smoothing capacitor as a threshold voltage, and the short-circuit switch when the voltage of the smoothing capacitor becomes equal to or lower than the threshold voltage. Is controlled from ON to OFF.

  According to a second means of the present invention, in the first means, the short-circuit control circuit determines in advance that the voltage of the smoothing capacitor is equal to or higher than the threshold voltage, or the voltage of the smoothing capacitor is equal to or higher than the threshold voltage. When the voltage is reached, the short-circuit switch is controlled from OFF to ON.

  According to a third means of the present invention, in the first or second means, the inrush current reduction circuit is connected between the rectifier and a smoothing capacitor, and the short-circuit switch is a relay contact. .

  According to a fourth means of the present invention, in the first or second means, the inrush current reduction circuit is connected to an AC input side of the rectifier, and the short-circuit switch is a triac or a relay contact. .

  According to a fifth aspect of the present invention, in the power supply device including at least two power supply devices including a rectifier that rectifies the input AC voltage and a smoothing capacitor, the output of the first power supply device is equal to or greater than a predetermined value. The AC input of the second power supply device is turned ON, and when the output of the first power supply device becomes a predetermined value or less, the AC input of the second power supply device is turned OFF. It is controlled, and at least the second power supply device is any one of the first to fourth means.

  According to a sixth means of the present invention, in an electronic apparatus configured to include a power supply device, the power supply device is any one of the first to fifth means. .

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to reduce the inrush current to the direct current | flow side capacitor | condenser in a power supply device, and the inrush current at the time of turning off / on an alternating current input in a short time can be reduced.

  That is, according to the first means of the present invention, the charging state of the smoothing capacitor that generates the inrush current can be monitored, and the short circuit of the inrush current reducing resistor can be controlled with the voltage at which the inrush current becomes a predetermined value. Therefore, the inrush current to the capacitor can be surely reduced regardless of the timing when the AC input is turned ON / OFF / ON.

  According to the second means of the present invention, in the first means, the voltage at which the short-circuit switch is turned on and the voltage at which the short-circuit switch is turned off are equal to or higher than each other, so that the inrush current can be reliably reduced. The device can be realized with a simple circuit, in a small size and at a low cost.

  According to the third means of the present invention, even if an inrush current reducing resistor is inserted into the rectified DC circuit, a relay is used as a switch for short-circuiting it, so that ON / OFF control can be performed at an arbitrary timing. it can.

  According to the fourth means of the present invention, an inrush current reducing resistor is inserted into the AC circuit before rectification, and the triac is used as a switch for short-circuiting it. Therefore, ON / OFF control is performed for each zero cross point of AC. Moreover, ON / OFF control can be performed at an arbitrary timing by using a short-circuit switch as a relay.

  According to the fifth means of the present invention, even in a power supply device having a plurality of power supplies, inrush current can be reliably reduced no matter how the input switch is turned ON / OFF / ON.

  According to the sixth means of the present invention, it is possible to provide an electronic device that does not affect the commercial AC power supply side, such as voltage fluctuation, regardless of how the input switch of the electronic device is turned ON / OFF / ON. Can do.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a power supply device according to the present invention will be described in detail with reference to the drawings. The embodiment of the present invention described here is an example of a switching power supply device provided and used in an electronic device.

  FIG. 1 is a block diagram showing the configuration of the power supply device according to the first embodiment of the present invention. In FIG. 1, AC is an AC power source, FU1 is a fuse, SW1 is an input switch, NF1 and NF2 are noise filters, DB is a diode bridge, R1 and R2 are resistors, RL1 is a relay contact, C1 is a capacitor, and Vd1 is a DC voltage detection A circuit, CONT is a switching control circuit, Q1 is a transistor, T1 is a transformer, and OUT is an output circuit.

  The power supply apparatus according to the first embodiment of the present invention includes a fuse FU1, an input switch SW1, a first stage noise filter NF1, an input switch SW1, a second stage noise filter NF2, and a diode bridge DB on the AC power supply AC side. A rectifier is provided, and the DC side rectified by the diode bridge DB is configured by a parallel circuit of a smoothing capacitor C1, a resistor R1 for limiting an inrush current to the smoothing capacitor C1, and a relay contact RL1 as a short-circuit switch for short-circuiting the resistor R1. Controlled by an inrush current reduction circuit, a DC voltage detection circuit Vd1 as a short-circuit control circuit for controlling ON / OFF of the relay contact RL1, a switching control circuit CONT for performing control for converting DC voltage to AC again, and a switching control circuit CONT Transistor Q1, output overload Resistance to detect other defects R2, is configured provided with an output circuit OUT supplies a DC voltage transformer T1, the electronic device that performs voltage conversion of an AC which is converted again.

  In the power supply apparatus configured as described above, the commercial AC power supply AC is connected to the input switch SW1 through the fuse FU1, the first-stage noise filter NF1, and further through the second-stage noise filter NF2 to the diode bridge. Connected to DB. In the above description, the input switch SW1 is for manually switching ON / OFF of the power supply device. When the power supply device described is incorporated in an electronic device, the input switch SW1 is a switch for the electronic device itself. The input switch SW1 may be one that turns the input switch SW1 ON / OFF in conjunction with another switch without manually switching the input switch SW1 itself.

  The AC power supply AC input to the diode bridge DB is rectified by the diode bridge DB, which is a rectifier, and is input to the capacitor C1 through a parallel circuit of the resistor R1 and the relay contact RL1, and is generated into a DC voltage. The resistor R1 is for reducing the inrush current to the capacitor C1, and detects the magnitude of the DC voltage accumulated in the capacitor C1 to explain the short circuit of the resistor R1. And is short-circuited during normal operation by the relay contact RL1 that is ON / OFF controlled. Details of the control operation will be described later.

  The DC voltage charged and stored in the capacitor C1 is applied to the switching control circuit CONT to start the switching control circuit CONT. The switching control circuit CONT is connected in series to the primary winding of the transformer T1. The transistor Q1 is switched, and an AC voltage is applied to the primary winding of the transformer T1. The output on the secondary side of the transformer T1 is rectified and smoothed by the output circuit OUT to obtain a predetermined DC output V1, which is supplied as a DC power source for an electronic device (not shown). The output circuit OUT is provided with an output voltage detection circuit, and this detection voltage is fed back to the switching control circuit CONT to stabilize and control the voltage of the DC output V1. The resistor R2 connected in series with the transistor Q1 feeds back the current flowing through the resistor R2 as a voltage to the switching control circuit CONT, and performs a protection operation against an output overload or other malfunction.

  The operation of the power supply circuit described so far is the same as that of the prior art. Next, the operation for reducing the inrush current to the capacitor C1, which is a characteristic configuration of the present invention, will be described.

  The charging voltage of the capacitor C1 is finally the peak voltage of the voltage of the AC power supply AC. In Japan, the commercial power supply is 100V, so that the charging voltage is 100V × √2 = 141V. This voltage becomes the saturation voltage of the capacitor. In general, since the internal impedance of the capacitor C1 is very small, a large current flows in the initial stage after the input switch SW1 is turned on, and the current value decreases as the capacitor C1 is charged.

  FIG. 2 is a diagram showing a result of actual measurement with the input AC between the charging voltage and the charging current of the capacitor C1 of the power supply device shown in FIG. 1 as 100V, and FIG. 2 (a) shows the charging voltage Vc1 of the capacitor C1. (V) and the measured value of the charging current I (A) flowing from the diode bridge DB to the capacitor C1 in a state where the charging voltage Vc1 is accumulated in the capacitor C1, FIG. 2 (b) is a graph of FIG. 2 (a). Is a graph showing the actual measurement values shown in FIG.

  In general, when the input switch SW1 is turned on, the voltage of the capacitor C1 is almost zero, so that a large inrush current for charging the capacitor C1 is generated as can be seen from FIG. In order to reduce this inrush current, a resistor R1 is connected in series with the capacitor C1. The initial inrush current as described above may cause an overcurrent to flow through the commercial power supply line to drop the voltage, causing problems with other electronic devices connected to the same commercial power supply line. By connecting the resistor R1 in series with the capacitor C1, it is possible to prevent the above-described problems, but a loss occurs when a current flows through the resistor R1. For this reason, when the capacitor C1 is charged to a sufficient voltage, the resistor R1 is short-circuited. This short circuit is performed using the relay contact RL1 or a semiconductor switch.

  The power supply circuit according to the first embodiment of the present invention shown in FIG. 1 uses a relay contact RL1 to short-circuit the resistor R1. In general, the timing at which the relay contact RL1 is turned ON and the resistor R1 is short-circuited is that the input switch SW1 is turned ON by using another voltage for the transformer T1 or using the voltage of the transformer T1 or the like. Thereafter, the relay contact RL1 is turned on after a sufficient time.

  Conventionally, it has not been necessary to frequently turn on / off an electronic device. However, in recent years, the power supply device of an electronic device has been frequently turned on / off in view of energy saving, so it turned off unexpectedly. In rare cases, the situation of turning on again is happening.

  In the case of the prior art, since the relay contact RL1 that short-circuits the resistor R1 is not considered, the relay contact RL1 is turned off after the electronic device is turned off, that is, after the input switch SW1 of the power supply device is turned off. In some cases, it takes more than 5 seconds, and when the power supply is turned off from on and the input switch SW1 is turned on again after a few seconds, the relay contact RL1 remains on, and an inrush current flows through the capacitor C1. become.

  FIG. 3 is a diagram showing an actual measurement result of the voltage of the capacitor C1 after the input switch SW1 of the power supply device shown in FIG. 1 is turned off. FIG. 3A shows the time (seconds) after the input switch SW1 is turned off. ) With respect to the voltage Vc (V) of the capacitor C1, and FIG. 3B is a graph showing the actual value shown in FIG.

  As can be seen from FIG. 3, the capacitor C1 is completely discharged about 4.5 seconds after the input switch SW1 of the power supply device is turned off. If the input switch SW1 is turned off from ON and turned on again after 3 seconds, the voltage of the capacitor C1 at that time is about 70V from FIG. In this case, the inrush current to the capacitor C1 is found to be about 80A from FIG.

  When a standard 5 inrush current compatible product is used as the resistor R1, the current resistance of the resistor R1 is guaranteed up to 78A. Looking at a margin (× 0.8) with respect to this withstand current and aiming at about 60 A or less, the voltage of the capacitor C1 is about 90 V from FIG. This voltage is about 2/3 of the voltage 141V at saturation. That is, when the input switch SW1 is turned on at 2/3 or more of the saturation voltage, the inrush current to the capacitor C1 can be suppressed to 60 A or less.

  The short-circuit control of the resistor R1 in the power supply device according to the first embodiment of the present invention shown in FIG. 1 is performed by the DC voltage detection circuit Vd1. That is, the DC voltage detection circuit Vd1 detects the voltage of the capacitor C1, sets the preset threshold voltage Vth to 90V, and controls the relay contact RL1 to be OFF when the detected voltage becomes Vth, that is, 90V or less. To do. The voltage 90V of the capacitor C1 is an AC effective value voltage 63V, which is a value having a sufficient margin with respect to the guaranteed value of the voltage drop of the commercial power supply. The voltage detection of the capacitor C1 can be easily performed by dividing the voltage at both ends of the capacitor C1 with a resistor and comparing the voltage with a reference voltage using a comparator, so the details of the configuration of the DC voltage detection circuit Vd1 are as follows. Description is omitted.

  FIG. 4 is a block diagram showing a configuration of a power supply device according to the second embodiment of the present invention. In FIG. 4, TRC1 is a triac, Vd2 is a DC voltage detection circuit, and other symbols are the same as those in FIG.

  The second embodiment of the present invention shown in FIG. 4 is different from the first embodiment of the present invention shown in FIG. 1 in that a resistor R1 for reducing inrush current to the capacitor C1 is provided in front of the diode bridge DB. This is different from the first embodiment in that it is provided on the AC power source side and is used in the triac TRC1 instead of the relay contact RL1, and the other configuration is the same.

  In the power supply device according to the second embodiment of the present invention shown in FIG. 4, since an alternating current flows through the resistor R1, a comparatively inexpensive triac TRC1 is used as a short-circuiting element for the resistor R1. Used to configure. Since the triac TRC1 extinguishes when the AC voltage becomes 0V, when using a commercial power supply of 50 Hz, ON / OFF can be controlled at intervals of 10 ms. A problem with the operation of the input switch SW1 is the action of a human hand, and sufficient control can be performed at intervals of 10 ms. Of course, also in the configuration shown in FIG. 4, TRC 1 can be used as a relay contact. In this case, an AC-compatible one is selected as the relay contact.

  FIG. 5 is a diagram showing waveforms of respective parts in the power supply device according to the first and second embodiments of the present invention shown in FIGS. In FIG. 5, SW1 is a switch ON / OFF state that is manually turned ON / OFF, AC is an AC voltage waveform after SW1 is turned ON, Vc1 is a voltage waveform of the capacitor C1, and Vth is a circuit for short-circuiting the resistor R1. The threshold voltage RL1 / TRC1, which is the operating voltage of the relay contact RL1 or the triac TRC1, indicates ON or OFF of the relay RL1 or the triac TRC1.

  The timing when the relay contact RL1 or the triac TRC1 is turned on may be functionally the same as that when the relay contact RL1 or the triac TRC1 is turned off as described above. In other words, the voltage may be turned on when the voltage of the capacitor C1 exceeds Vth and turned off when the voltage of the capacitor C1 falls below Vth. In this case, since the comparison circuit of the DC voltage detection circuit Vd1 that detects the voltage of the capacitor C1 is common, the configuration is simple, small, and inexpensive. Further, the charging time of the capacitor C1 is several seconds at the longest, and the loss in the resistor R1 until the saturation charging is negligible. Therefore, when the AC power supply AC is 100V, the resistor R1 may be turned on as long as the voltage of the capacitor C1 is 90V or higher, and may be 141V. When the commercial AC power supply AC is 120V or 200V, the same effect can be obtained by using 2/3 of the saturation voltage as the switching voltage as the threshold voltage as described above.

  A thyristor is used for direct current as a semiconductor element capable of switching a large current at a relatively low cost. However, once the thyristor is ignited, it remains on until the input is turned off. Therefore, in the first embodiment of the present invention shown in FIG. 1, a relay contact is used as an element for controlling ON / OFF of the resistor R1.

  FIG. 6 is a block diagram showing a configuration of a power supply device according to the third embodiment of the present invention. The power supply device shown in FIG. 6 is an example when two power supply devices are provided in one power supply device. In FIG. 6, PSU1 and PSU2 are first and second power supply units, Vd3 is an output control circuit, RL2 is a relay contact, and other reference numerals are different from those of the reference numerals. Is the same as In the third embodiment of the present invention, in order to obtain the maximum energy saving effect, the power supply device that supplies the voltage necessary for energy saving and the power supply device that supplies the voltage required for operation are independent. Alternatively, it can be used as a power source device in which the power source is divided due to the optimization of the layout in the electronic device.

  In the power supply device shown in FIG. 6, the first power supply device PSU1 is configured by adding an output control circuit Vd3 to the transformer T1 output stage of the power supply device according to the first embodiment of the present invention shown in FIG. The other configurations and functions are exactly the same as those shown in FIG. The output control circuit Vd3 provided in the first power supply device PSU1 is a circuit that controls the relay contact RL2 of the second power supply device PSU2 to be ON or OFF when the output voltage V1 becomes a predetermined voltage.

  The second power supply unit PSU2 connects the input of the power supply unit according to the second embodiment of the present invention shown in FIG. 4 to the output of the input switch SW1 of the first power supply unit PSU1, so that the first stage The noise filter NF1 is deleted and a relay contact RL2 is used instead of the switch SW1, and the other configuration and function are exactly the same as those shown in FIG.

  FIG. 7 is a diagram showing waveforms of respective parts in the power supply device according to the third embodiment of the present invention shown in FIG. In FIG. 7, SW1 is the ON / OFF switch of the electronic device ON or OFF (same as SW1 in FIGS. 1 and 4), AC is the AC voltage waveform after SW1 is ON, and V1 is the first The output voltage waveform of the power supply unit PSU1, RL2 is the ON / OFF state of the relay contact connected to the input side of the second voltage unit PSU2, Vc2 is the voltage waveform of the capacitor C2 of the second power supply unit PSU2, and TRC1 is the first 2 shows the ON / OFF state of the triac of the power supply unit PSU2.

  As shown in FIG. 7, the output voltage waveform V1 of the first power supply unit PSU1 rises when an AC power supply is input, and falls when the AC power supply is turned off. The relay contact RL2 connected to the input side of the second voltage device PSU2 is controlled to be ON when the output voltage waveform V1 rises, and is controlled to be OFF when the output voltage waveform V1 falls. The triac TRC1 of the second power supply unit PSU2 is ON / OFF controlled when the voltage waveform Vc2 of the capacitor C2 of the second power supply unit PSU2 becomes a predetermined voltage Vth. These Vc2 and TRC1 are the same as Vc1 and RL1 / TRC1 shown in FIG.

  As can be seen from the waveform timing of each part shown in FIG. 7, the power supply device constituted by two power supply devices has a complicated timing at which the AC voltage is intermittently controlled, and is controlled by the output voltage as in the case of the prior art. However, when the winding is added to the transformer and controlled, the opening of the means for short-circuiting the inrush current reducing resistor to the smoothing capacitor cannot be properly controlled. In the third embodiment, since the voltage of the capacitor causing the inrush current can be detected and the short-circuit means can be opened with the most appropriate voltage, the power supply constituted by a plurality of power supply devices as described above Also in the apparatus, the inrush current can be appropriately reduced.

  The power supply apparatus according to each embodiment of the present invention described above can be used by being incorporated into various electronic devices such as home appliances, information processing apparatuses represented by PCs, copiers, printers, and the like.

It is a block diagram which shows the structure of the power supply device by the 1st Embodiment of this invention. It is a figure which shows the result of having measured the alternating current which inputs the relationship between the charging voltage and charging current of the capacitor | condenser C1 of the power supply device shown in FIG. 1 as 100V. It is a figure which shows the measurement result of the voltage of the capacitor | condenser C1 after turning off input switch SW1 of the power supply device shown in FIG. It is a block diagram which shows the structure of the power supply device by the 2nd Embodiment of this invention. It is a figure which shows the waveform of each part in the power supply device by the 1st, 2nd embodiment of this invention shown in FIG. 1, FIG. It is a block diagram which shows the structure of the power supply device by the 3rd Embodiment of this invention. It is a figure which shows the waveform of each part in the power supply device by 3rd Embodiment of this invention shown in FIG.

Explanation of symbols

AC AC power supply FU1, FU2 Fuse SW1 Input switch NF1, NF2 Noise filter DB, DB1, DB2 Diode bridge R1, R2, R3, R4 Resistor RL1, RL2 Relay contact C1, C2 Capacitor Vd1, Vd2 DC voltage detection circuit CONT, CONT, CONT2 switching control circuit Q1, Q2 transistor T1, T2 transformer OUT, OUT1, OUT2 output circuit TRC1 triac PSU1, PSU2 first and second power supply devices Vd3 output control circuit

Claims (6)

In a power supply device including a rectifier that rectifies an input AC voltage and a smoothing capacitor,
An inrush current reduction circuit that is connected in series to the charging current circuit of the smoothing capacitor, and in which an inrush current reduction resistor for suppressing inrush current and a short-circuit switch that short-circuits the resistor are connected in parallel, and the smoothing capacitor A short-circuit control circuit that detects the voltage of the capacitor and controls ON / OFF of the short-circuit switch, and the short-circuit control circuit uses a voltage that is 2/3 of the saturation voltage of the smoothing capacitor as a threshold voltage, A power supply device that controls the short-circuit switch from ON to OFF when a voltage becomes equal to or lower than the threshold voltage.   The short-circuit control circuit controls the short-circuit switch from OFF to ON when the voltage of the smoothing capacitor becomes equal to or higher than the threshold voltage, or when the voltage of the smoothing capacitor becomes a predetermined voltage equal to or higher than the threshold voltage. The power supply device according to claim 1.   The power supply apparatus according to claim 1, wherein the inrush current reduction circuit is connected between the rectifier and a smoothing capacitor, and the short-circuit switch is a relay contact.   The power supply apparatus according to claim 1, wherein the inrush current reduction circuit is connected to an AC input side of the rectifier, and the short-circuit switch is a triac or a relay contact. In a power supply device including at least two power supply devices each including a rectifier that rectifies an input AC voltage and a smoothing capacitor,
When the output of the first power supply device exceeds a predetermined value, the AC input of the second power supply device is turned on, and when the output of the first power supply device becomes less than the predetermined value, the second 5. The power supply device according to claim 1, wherein the power supply device is controlled to turn off the AC input of the power supply device, and at least the second power supply device is the power supply device according to claim 1.   6. An electronic apparatus comprising a power supply apparatus, wherein the power supply apparatus is the power supply apparatus according to any one of claims 1 to 5.

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