JP2001218468A - Parallel connection circuit for power supply unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a parallel connection circuit capable of parallel-connecting a plurality of power supply units with a simple structure. SOLUTION: A plurality of stabilizing power circuits are provided which consists of a transistor Tr11, MOS-FET11, 12 connected to the primary side of the transistor Tr11, and a current multiplying-rectifying circuit connected to the secondary side of the transistor Tr11, and the output terminals of the respective stabilizing power circuits are connected in parallel to supply electric power to loads. Each of the stabilizing power circuits includes the current multiplying-rectifying circuit, therefore an output current value is always constant. It is thus possible to operate a plurality of power supply units very easily by connecting them in parallel without any troublesome work such as setting the output currents of the respective power circuits to fixed values.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a parallel connection circuit of a power supply device for reducing stress.

[0002]

2. Description of the Related Art Generally, in electric and electronic devices using a semiconductor integrated circuit such as a personal computer and an AV device, a stable DC power supply of about 5 to 10 volts is required to operate the integrated circuit. Conventionally, a power supply device using a switching regulator has been widely used as a stable DC stabilized power supply device. The switching regulator has advantages that it can be reduced in size as compared with other DC stabilized power supply devices such as a series regulator and a shunt regulator, and that the power loss is small and the efficiency is high.

In recent years, in order to make the power supply device redundant and reduce the stress of the power supply circuit,
Many schemes for connecting a plurality of power supply units in parallel have been proposed and are commonly used. In other words, by changing from the centralized power supply to the distributed power supply, even if one power supply fails, there is an advantage that power can be supplied to the load as usual by operating the other power supply.
On the other hand, the current value flowing through each power supply device can be small, so that the thermal stress applied to each power supply device can be reduced.

Conventionally, a power supply as a reference has been set as such a parallel connection circuit of the power supply, and a current output from this power supply has been detected to detect a current output from another power supply as a reference. Adjustments to equal the current of the device are known and are in practical use.

[0005]

However, in a conventional parallel connection circuit of power supply devices, an operation of measuring a current value of a reference power supply device and adjusting an output current of another power supply device to this current value is performed. However, there is a drawback that the circuit configuration becomes large-scale, a large number of parts are required, and a failure is caused.

The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide a parallel connection circuit that can connect a plurality of power supply devices in parallel with a simple configuration. To provide.

[0007]

This and other objects are achieved by the present invention which is defined below as (1) to (6).

(1) A plurality of stabilized power supply units each having a transformer, switching means connected to the primary side of the transformer, and a current doubler rectifier circuit connected to the secondary side of the transformer are provided. And an output terminal of each of the stabilized power supply devices connected in parallel to supply power to a load.

(2) It has a plurality of transformers, and a double current rectifier circuit is connected to the secondary winding of each of the transformers,
Primary windings of the respective transformers are connected in series, and switching means connected to both ends of the series connection, and a DC power supply connected to the switching means,
A parallel connection circuit for a power supply device, wherein output terminals of the current doubler rectifier circuit are connected in parallel to supply power to a load.

(3) The transformer is a resonance transformer, and a resonance capacitor is connected in parallel to a secondary winding of the resonance transformer to cause a secondary current of the resonance transformer to resonate in series. ) Or the parallel connection circuit of the power supply device according to (2).

(4) The transformer is a resonance transformer composed of an ideal transformer and a resonance coil connected to the primary side of the ideal transformer.
The parallel connection circuit of the power supply device according to (1) or (2), wherein a resonance capacitor is connected in parallel to the next winding, and a secondary current of the resonance transformer is caused to resonate in series.

(5) A switching means comprising a first switching element and a second switching element connected in series to a DC power supply, and a first means arranged in parallel with the first switching element. A capacitor and a first diode, and a second capacitor and a second capacitor installed in parallel with the second switching element.
And one end of a primary winding is connected to a connection point between the first switching element and the second switching element, and the other end is connected to the minus side of the DC power supply via a capacitor. And a resonance capacitor connected to the secondary side of the resonance transformer for serially resonating the secondary current of the resonance transformer, and a double current rectifier circuit provided at the subsequent stage of the capacitor. Wherein a plurality of power supply units are connected in parallel and output terminals of the respective stabilized power supply units are connected in parallel to supply power to a load.

(6) The number of the stabilized power supply circuits is n (n =
The switching means of each stabilized power supply circuit is turned on and off by shifting the phase angle by (2π / n) radians.
A parallel connection circuit of the power supply device according to any one of (5) to (5).

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing a configuration of a first embodiment of a parallel connection circuit of a power supply device to which the present invention is applied. As shown in the figure, the parallel connection circuit 100 of the power supply device includes a DC power supply E1, and three power supply devices 1, 2, and 3 connected in parallel to the DC power supply E1. The output terminals of the power supply devices 1, 2, 3 are connected in parallel, and the output terminals P1, P2 are connection points for connecting a load.

Since each of the power supply units 1, 2, and 3 has the same configuration (however, the phase of the pulse signal for driving the MOS-FET is different as described later), the suffix "-" 1 ", and the suffixes" -2 "and
The description of the configuration is omitted by adding “-3”.

The power supply device 1 includes a first MOS-FET (switching element) connected in series to the DC power supply E1.
11-1 and the second MOS-FET 12-1 and their M
A driving pulse is applied to the gates of the OS-FETs 11-1 and 12-1 to control the ON / OFF operation of the MOS-FETs 11-1 and 12-1; A first capacitor C11-1 connected in parallel to the MOS-FET 11-1 and a diode D11-1
And a second capacitor C12-1 connected in parallel to the second MOS-FET 12-1 and a diode D
12-1 and a transformer (resonant transformer) Tr11-1. One end of a primary coil (primary winding) L11-1 of the transformer Tr11-1 is connected to one of the MOS-FETs 11-1 and 12-. 1
And the other end is connected to the minus terminal (ground) of the DC power supply E1 via the capacitor C13-1.

On the other hand, both ends of a secondary coil (secondary winding) L12-1 of the transformer Tr11-1 are connected to a resonance capacitor C12.
14-1 are connected to both ends, and furthermore, a series connection circuit of diodes (rectification means) D13-1 and D14-1
And a series connection circuit of the choke coils L13-1 and L14-1. Further, each diode D13-1, D
14-1 and each of the choke coils L13-1 and L14
A capacitor C15-1 is interposed between the power supply circuit 2 and the connection point of the power supply circuit 2,
3 are connected to both ends of capacitors C15-2 and C15-3, respectively, and this connection point is connected to load connection terminals P1 and P15.
It is 2.

The oscillator 13 includes MOS-FETs 11 (11-1 to 11-3) and 12 (1
2-1 to 12-3), and the phase is shifted by 2π / 3 radians (that is, 120 °) for each of the power supply devices 1 to 3. In this embodiment, since three power supplies 1 to 3 are used, the phase angle is set to 2π / 3 radian. However, when the number of power supplies is n (n = 2, 3,...), Is 2π / n radians.

FIGS. 2 to 4 are equivalent circuit diagrams of the power supply device 1 shown in FIG. 1 (since the choke coils L13-1 and L14-1 are present, the secondary side of the transformer Tr11-1 has a constant current. Only the circuit on the left side of the capacitor C14-1 of the power supply device 1 may be considered). FIG. 5 is a timing chart, and the operation of the present embodiment will be described with reference to the drawings. When the coupling coefficient of the transformer Tr11-1 of the power supply device 1 is K and converted to the primary side, as shown in FIGS. 2 to 4, the transformer Tr11-1 has two leakage inductances L21-1 and L22-1 ( L21-1 and L22-1 = (1
−K) * L11-1) and main inductance L23-1
(L23-1 = K * L11-1), and the resonance capacitor C14-1 of the power supply circuit 1 is C
^{21-1 (C21-1 = C14-1 / N 2} ; however, N is the turns ratio of the transformer Tr 11 - 1) can be expressed by.

FIG. 5A shows the ON / OFF state of the MOS-FET 11-1, FIG. 5B shows the ON / OFF state of the MOS-FET 12-1, and FIG. 5C shows the voltage Vds across the MOS-FET 12-1. FIG. 4D shows the primary side current waveform, and FIG.
Indicates a secondary voltage waveform.

Now, FIGS. 5 (a) and 5 (b)
In other words, the driving signal as shown in FIG.
A drive signal that turns on the ET 11-1 and then turns off and turns on the MOS-FET 12-1 with a slight delay from the off time (that is, two MOS-FETs 11-1 and
12-1 is not turned on at the same time), the MOS-FET 11-1 is turned on at time t0 (at this time, the MOS-FET 12-1 is turned off), as shown in FIG. As described above, the MOS-FET 11-1, the inductances L21-1 and L22-1 and the capacitors C21-1 and C2-1
Through 13-1, the resonance current i1 flows from the plus side to the minus side of the DC power supply E1 (the voltage value is Vin). At this time, the capacitor C12-1 is charged with the voltage Vin, and as shown in FIG.
The voltage applied to T12-1 is Vin volt.

Next, at time t1, the MOS-FE
Since T11-1 is turned off (at this time, the MOS-FET
12-1 is also off), as shown in FIG. 2B, the discharge current i3 of the capacitor C12-1 and the capacitor C11-1
Charging current i2 flows as a resonance current, and
When the voltage of the capacitor C12-1 becomes 0 volt in Step 2, the resonance current i4 flows through the body diode D12-1, as shown in FIG. At this time, MO
Since the voltage Vds of the S-FET 12-1 becomes 0 volt, if the MOS-FET 12-1 is turned on within the time from t2 to t3, zero volt switching becomes possible and power loss can be reduced.

At time t3, the MOS-FET 12-1
Is turned on, the electric charge accumulated in the capacitor C13-1 is discharged, so that the resonance current i5 passes through the MOS-FET 12-1 as shown in FIG. Will flow in the direction. At this time, the capacitor C11-1 is charged with the voltage Vin. Then, at time t
4 turns off the MOS-FET 12-1.
As shown in (2), the electric charges charged in the capacitor C11-1 are discharged, so that the currents i6 and i7 flow, whereby the capacitor C12-1 is charged to Vin.

Further, as shown in FIG.
When the voltage Vds across the MOS-FET 12-1 becomes Vin volt at 5, the resonance current i8 flows via the body diode D11-1, as shown in FIG. 4B.
At this time, the voltage Vds between both ends of the MOS-FET 11-1 becomes 0 volt.
Turning on the OS-FET 11-1 enables zero volt switching.

Then, when the MOS-FET 11-1 is turned on again, the above-described operations of FIGS. 2 to 4 are repeated, and a sine-wave primary current as shown in FIG. A sinusoidal secondary voltage waveform as shown in (e) can be obtained. That is, a sinusoidal voltage waveform is generated between both ends of the resonance capacitor C14-1 shown in FIG.

Further, as can be understood from the figure, the switching timing on the primary side and the switching timing on the secondary side are not synchronized, so that the switching noise generated on the primary side and the switching noise on the secondary side are not synchronized. The generated switching noise is not superimposed, and the noise can be dispersed. Further, the resonance current continues to flow without interruption via the leakage inductances L21-1 and L22-1. Therefore, occurrence of ringing noise in the secondary voltage waveform can be prevented.

Next, FIGS. 6 and 7 are explanatory diagrams showing the circuit operation of the current doubling rectifier circuit. Referring to FIGS. 6 and 7, the power supply device 1 shown in FIG. Will be described.

Now, when the voltage at one end Pa of the capacitor C14-1 becomes a positive voltage, as shown in FIG. 6, the choke coil L13-1 and the load RL (the capacitor C15-
1), a current i11 flows through the diode D14-1, and further, the capacitor C15-1 and the diode D14-1
And the loop current i via the choke coil L14-1
12 flows. Therefore, the current (i11
+ I12) flows, and the current value is doubled, so that a double current is achieved.

The other end Pb of the resonance capacitor C14-1
Is positive, the choke coil L14-1, load RL (capacitor C
15-1), a current i13 flows through the diode D13-1, while the capacitor C15-1 and the diode D13-
1. Loop current i1 via choke coil L13-1
4 flows. Therefore, the current (i13 +
Since i14) flows, the current value is doubled.

In the power supply device 1, the transformer T
A double current rectifier circuit is provided on the secondary side of r11-1. Since the double current rectifier circuit has choke coils L13-1 and L14-1, the output current value is constant. Similarly, the output current values of the power supply circuits 2 and 3 shown in FIG. 1 are constant, and the output voltage values of the power supply circuits 1 to 3 are the same. Therefore, if these output terminals are connected in parallel, Parallel operation becomes possible.

In the power supply device 1, the output voltage becomes a desired voltage by adjusting the frequency and duty ratio of the driving pulse signals of the MOS-FETs 11-1 and 12-1 outputted from the oscillator 13 as needed. You can do so. Thus, a stable DC voltage can be supplied to the load. Further, the output voltage of the parallel connection circuit 100 (the voltage applied to the load RL shown in FIG. 1) is measured and fed back to the oscillator 13, and the frequency or the duty ratio is adjusted according to the measured voltage value. With this configuration, the output voltage can be constantly stabilized.

As described above, in the parallel connection circuit of the power supply device according to the present embodiment, a plurality of power supply devices (three in the present embodiment) having the current doubler rectifier circuit mounted on the secondary side of the transformer Tr11 are installed. The output terminals of these power supply devices are connected in parallel. Therefore, unlike the related art, it is not necessary to perform an operation such as matching output current values for each power supply device, and a plurality of power supply devices can be easily operated in parallel. Therefore, the number of components can be reduced, and the circuit configuration can be simplified.

The MOS-F mounted on the power supply 1
ET11-1 and MOS-FET12-1, MOS-FET11-2 and MOS-FET12-2 mounted on the power supply device 2,
In addition, since the MOS-FET-3 and the MOS-FET12-3 mounted on each power supply device 3 are provided with the drive signal from the oscillator 13 with the phase angles shifted by 2π / 3 radians, the ripple of the output current is reduced. Can be reduced.

That is, since each of the power supply devices 1 to 3 has a current doubling rectifier circuit, a substantially stable DC current can be obtained.
Since the switching operation of the power supply device 12 is performed, the output current of each of the power supply devices 1 to 3 has a slight ripple. Therefore, if the MOS-FETs 11 and 12 are switched by shifting the phase angle by 2π / 3 radians for each of the power supplies 1 to 3, the output terminals of the power supplies 1 to 3 can be connected in parallel. The resulting output current cancels out the peaks and valleys of the ripple, so that a stable DC current with very little ripple can be obtained, and the ripple of the input current also decreases.

Further, since a double current rectifier circuit is used as a circuit for rectifying the secondary current of the transformer Tr11, there is no need to provide a center tap on the secondary winding of the transformer Tr11. Can be simplified.

In the above embodiment, the transformer T
Leakage inductance of r11 and resonance capacitor C
An example in which the secondary side current of the transformer Tr11 is subjected to series resonance with the transformer 14 has been described. As shown in FIG. 8, an ideal transformer (transformer having no leakage inductance) Tr31 and a primary side of the ideal transformer Tr31 are provided. A resonance transformer may be configured with the resonance coil L41 connected to the coil. Even in such a configuration,
The same effects as in the above-described embodiment can be obtained.

In the above embodiment, an example in which three power supply circuits 1 to 3 are operated in parallel has been described. However, the present invention is not limited to this, and two or four or more power supply circuits may be used. May be connected.

In the above embodiment, the transformer (resonant transformer) Tr11 (Tr11-1 to Tr11-3)
Although an example in which the resonance capacitor C14 (C14-1 to C14-3) is connected to the secondary side has been described, the present invention is not limited to this, and a circuit having a resonance capacitor on the primary side of the transformer Tr11, Alternatively, a non-resonant circuit that does not use the resonance phenomenon may be used. In other words, regardless of the resonance type or non-resonance type, the current doubling rectifier circuit operates so that the output current is always constant. Therefore, the output terminals of a plurality of stabilized power supply units equipped with the current doubling rectifier circuit are connected in parallel. , The above-described effect can be obtained.

In the current doubling rectifier circuit of the above-described embodiment, the transformer Tr is provided by using the diodes D13 and D14.
Although the secondary side current of No. 11 is configured to be rectified, a synchronous rectification method may be adopted by arranging a MOS-FET as the rectification means and turning it on and off.

Further, in the above-described embodiment, the half bridge type circuit using two MOS-FETs 11 and 12 as the switching means has been described as an example. However, a full bridge circuit using four switching means may be used. It is possible.

FIG. 9 is a circuit diagram showing the configuration of the second embodiment of the parallel connection circuit of the power supply device of the present invention. As shown in the figure, the parallel connection circuit 200 includes a DC power supply E2
And MOS-FETs 21 and 22 (switching elements) connected in series to the output terminal of the DC power supply E2. A capacitor C31 and a body diode D31 are provided in parallel with the MOS-FET 21, and a capacitor C32 and a body diode D32 are provided in parallel with the MOS-FET 22. The MOS-FETs 21 and 22 are connected to the oscillator 23
And is turned on / off by a drive pulse given from the oscillator 23.

Further, two transformers (resonant transformers) T
r21-1 and Tr21-2.
21-1 and primary coils L31-1 and L31-2 of Tr 21-2
Are connected in series, and one end of this series connection is
-The other end is connected to the minus point of the DC power supply E2 via the capacitor C33.

A secondary current rectifier circuit is connected to each of the secondary coils L32-1 and L32-2 of each of the transformers Tr21-1 and Tr21-2, and the secondary current rectifier circuit includes a resonance capacitor C34-1. , C34-2, rectifying diode D33
-1, D34-1, D33-2, D34-2, choke coil L
33-1, L34-1, L33-2, L34-2, and output capacitors C35-1, C35-2. And it has the same configuration as the double current rectifier circuit mounted on the power supply devices 1 to 3 shown in FIG.

One end of the capacitor C35-1 and the capacitor C
One end of 35-2 is connected, and this connection point is used as an output terminal P11. The other end of the capacitor C35-1 is connected to the other end of the capacitor C35-2, and the connection point of the connection point is set to the output terminal P12. The output terminals P11 and P12 are connection points to the load RL.

When the drive pulse from the oscillator 23 is given to the MOS-FETs 21 and 22 of the parallel connection circuit of the power supply device configured as described above, the same procedure as that shown in the first embodiment is performed. Transformers Tr21-1 and Tr21-2
A primary voltage is generated on the primary coils L31-1 and L32-1 side. Then, a constant current flows through each of the secondary side double current rectifier circuits, so that parallel connection operation is possible.

The two primary coils L31-1 and L32
-1 are connected in series, so the primary voltage is divided, and the primary coils L31-1 and L32-1 have 1
Since half of the next voltage is applied, the current doubling rectifier circuit
As compared with the case of the number of pieces, the output voltage (the voltage applied to the load RL) is １ ／, and the current value is doubled. This is extremely advantageous for lowering the voltage and increasing the current, which are the trends in power supply circuits in recent years.

Although FIG. 9 illustrates an example in which two double current rectifier circuits are connected in parallel, the present invention is not limited to this, and three or more double current rectifier circuits are connected in parallel. May be. That is, n units (n = 2, 3,.
If the double current rectifier circuit of ()) is connected in parallel, it becomes possible to perform a parallel connection operation with a voltage value of 1 / n times and a current value of n times as compared with the case of one unit.

As described above, the parallel connection circuit of the power supply device of the present invention has been described based on the illustrated embodiment. However, the present invention is not limited to this, and the configuration of each unit may be any arbitrary having the same function. It can be replaced with a configuration.

[0049]

As described above, in the parallel operation circuit of the power supply device according to the present invention, the output terminal of the stabilized power supply circuit having the current doubling circuit mounted on the secondary side of the transformer is connected.
Since the output current of each stabilized power supply circuit is controlled to be constant,
A plurality of power supply circuits can be operated in parallel without requiring any operation such as adjusting the output current of each power supply circuit to a constant value.

Further, if the on / off control is performed by shifting the phase angle of the switching means of a plurality of stabilized power supply circuits by 2π / n (n is the number of power supply circuits), ripples of input and output currents can be reduced. Can be.

Further, if the primary side coils of a plurality of transformers are connected in series, the primary side voltage can be halved, and the output current can be doubled. Low voltage and large current can be easily achieved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a first embodiment of a parallel operation circuit of a power supply device of the present invention.

FIG. 2 is an equivalent circuit of the power supply circuit 1 shown in FIG. 1,
(A) is an explanatory view showing a current flow from time t0 to t1, and (b) is an explanatory diagram showing a current flow from time t1 to t2.

FIG. 3 is an equivalent circuit of the power supply circuit 1 shown in FIG. 1,
(A) is an explanatory view showing a current flow from time t2 to t3, and (b) is an explanatory diagram showing a current flow from time t3 to t4.

FIG. 4 is an equivalent circuit of the power supply circuit 1 shown in FIG. 1,
(A) is a time t4 to t5, (b) is a time t5 to t6 (t
It is explanatory drawing which shows the flow of the electric current in 0).

5A and 5B are timing charts showing the operation of the power supply circuit 1, wherein FIG. 5A is an on-off state of the MOS-FET 11-1, FIG. 5B is an on-off state of the MOS-FET 12-1,
(C) is the voltage Vds across the MOS-FET 12-1, (d)
Shows a primary side current waveform, and (e) shows a secondary side voltage waveform (a voltage waveform applied to both ends of the capacitor C14).

FIG. 6 is an explanatory diagram showing a current flow of the current doubler rectifier circuit when one end Pa of the capacitor C14 is at a positive voltage.

FIG. 7 is an explanatory diagram showing a current flow of the current doubler rectifier circuit when the other end Pb of the capacitor C14 has a positive voltage.

FIG. 8 is a circuit diagram showing an example in which a resonance transformer is configured by an ideal transformer and a resonance coil.

FIG. 9 is a circuit diagram illustrating a configuration of a second embodiment of the parallel operation circuit of the power supply device of the present invention.

[Explanation of symbols]

100, 200 Parallel connection circuit of power supply device 1, 2, 3 Power supply device 11, 12, 21, 22 MOS-FET
(Switching means) 13, 23 Oscillator C11 to C15, C31 to C35 Capacitor Tr11, Tr21 Transformer (resonant transformer) Tr31 Ideal transformer L11, L31 Primary coil (primary winding) L12, L32 Secondary coil (secondary winding) L13, L14, L33, L34 Choke coil L41 Resonance coil E1, E2 DC power supply D11-D14, D31-D34 Diode RL load

Claims (6)

[Claims] 1. A plurality of stabilized power supplies each including a transformer, switching means connected to a primary side of the transformer, and a current doubler rectifier circuit connected to a secondary side of the transformer, An output terminal of each of the stabilized power supply devices is connected in parallel to supply power to a load. 2. A transformer comprising a plurality of transformers, a current doubler rectifier circuit connected to a secondary winding of each transformer, a primary winding of each transformer connected in series, and Switching means connected to both ends of the connection, and a DC power supply connected to the switching means, wherein power is supplied to a load by connecting output terminals of the current doubler rectifier circuit in parallel. The parallel connection circuit of the power supply device. 3. The resonance transformer according to claim 1, wherein a resonance capacitor is connected in parallel to a secondary winding of the resonance transformer, and a secondary current of the resonance transformer resonates in series. 3. The parallel connection circuit of the power supply device according to 2. 4. The transformer is a resonance transformer including an ideal transformer and a resonance coil connected to a primary side of the ideal transformer. A resonance capacitor is connected in parallel to a secondary winding of the resonance transformer, 2 of the resonant transformer
The parallel connection circuit of the power supply device according to claim 1, wherein the secondary current causes series resonance. 5. A switching means comprising a first switching element and a second switching element connected in series to a DC power supply, and a first capacitor arranged in parallel with the first switching element. And a first diode; a second capacitor and a second diode installed in parallel with the second switching element; and one end of a primary winding is connected to the first switching element and the second diode.
A resonant transformer connected to a connection point with the switching element, and the other end is connected to the minus side of the DC power supply via a capacitor; and a secondary current of the resonant transformer is connected to a secondary side of the resonant transformer. A resonance capacitor for performing series resonance, a current doubler rectifier circuit provided on the subsequent stage side of the capacitor,
A plurality of stabilized power supply devices each having: a plurality of stabilized power supply devices, and an output terminal of each of the stabilized power supply devices is connected in parallel to supply power to a load. 6. The stabilized power supply circuit includes n units (n = 2,
The switching means of each of the stabilized power supply circuits is turned on and off with a phase angle shifted by (2π / n) radians. A parallel connection circuit of the power supply device according to claim 1.