JP2006271135A - Power supply unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply unit which reduces noises generated at an output. <P>SOLUTION: The power supply unit includes a first series circuit 5 which is connected between input terminals of a noise source circuit 1 which generates the noises, and in which a first capacitor C11 and a second capacitor C12 are connected in series, a second series circuit 6 which is connected between output terminals of the noise source circuit 1, and in which a third capacitor C13 and a fourth capacitor C14 are connected in series, a substrate 20 on which the noise source circuit 1, the first series circuit 5 and the second series circuit 6 are mounted, and a metal plate 2 which connects a connection point of the first capacitor C11 and the second capacitor C12 to a connection point of the third capacitor C13 and the fourth capacitor C14, outside the substrate 20. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a power supply device, and more particularly to a technique for reducing noise appearing in the output thereof.

  2. Description of the Related Art Conventionally, power supply apparatuses that are incorporated in various systems and used as a DC power supply are known. In such a power supply device, a power supply board composed of a wiring board on which various components are mounted is housed in, for example, a sheet metal case formed in a box shape, and fixed to a self stud fixed to the sheet metal case with a board fixing screw. It is comprised by doing.

  The ground pattern formed on the power supply substrate is connected to the sheet metal case through the substrate fixing screw and the self stud. Further, the sheet metal case is fixed to the system casing with screws. And the output of a power supply device is supplied to the control board of a system.

  FIG. 4 is a circuit diagram showing an example of the electrical configuration of such a conventional power supply apparatus. In this power supply device, a DC voltage (DC input) input between the first input terminal IN1 and the second input terminal IN2 is converted into a predetermined DC voltage, and the first output terminal OUT1 and the second output are converted as DC outputs. It is output from between the terminal OUT2.

  This power supply apparatus includes a first line bypass capacitor C1, a second line bypass capacitor C2, a third line bypass capacitor C3, a fourth line bypass capacitor C4, a first choke coil L1, a second choke coil L2, and a DC / DC converter 1. It is composed of

  The first input terminal IN1 is connected to one terminal of the first line bypass capacitor C1 and is connected to one input terminal of the DC / DC converter 1 via the first choke coil L1. The second input terminal IN2 is connected to one terminal of the second line bypass capacitor C2, and is connected to the other input terminal of the DC / DC converter 1 via the first choke coil L1. The other terminal of the first line bypass capacitor C1 and the other terminal of the second line bypass capacitor C2 are connected to a sheet metal case (frame ground).

  The DC / DC converter 1 converts a DC voltage input from the first input terminal IN1 and the second input terminal IN2 via the first choke coil L1 into a predetermined DC voltage and outputs the same. One output terminal of the DC / DC converter 1 is connected to the first output terminal OUT1 via the second choke coil L2, and the other output terminal is connected to the second output terminal OUT2 via the second choke coil L2. It is connected.

  Further, one terminal of the third line bypass capacitor C3 is connected to the first output terminal OUT1, and one terminal of the fourth line bypass capacitor C4 is connected to the second output terminal OUT2. The other terminal of the 3-line bypass capacitor C3 and the other terminal of the fourth line bypass capacitor C4 are connected to a sheet metal case (frame ground).

  In the conventional power supply apparatus configured as described above, the first input terminal is provided by a filter including the first line bypass capacitor C1, the second line bypass capacitor C2, and the first choke coil L1 disposed on the input side. The noise input from IN1 and the second input terminal IN2 is removed, and the filter configured by the third line bypass capacitor C3, the fourth line bypass capacitor C4, and the second choke coil L2 disposed on the output side, Noise output from the DC / DC converter 1 is removed.

  FIG. 5 is a circuit diagram showing an example of the electrical configuration of another conventional power supply apparatus. In this power supply device, an AC voltage input between the first input terminal IN1 and the second input terminal IN2 is converted into a predetermined DC voltage, and output from between the first output terminal OUT1 and the second output terminal OUT2. Is done.

  In this power supply device, a rectifying / smoothing circuit 3, a fifth line bypass capacitor C31, and a sixth line bypass capacitor C32 are added between the first choke coil L1 and the DC / DC converter 1 of the power supply device shown in FIG. Configured. The rectifying / smoothing circuit 3 rectifies the AC voltage input between the first input terminal IN1 and the second input terminal IN2 by the diode bridge circuit DB, and further smoothes and outputs the smoothed voltage by the smoothing capacitor C20. The output of the rectifying / smoothing circuit 3 is sent to the DC / DC converter 1. The fifth line bypass capacitor C31 and the sixth line bypass capacitor C32 arranged as Y capacitors remove noise from the output of the rectifying and smoothing circuit 3.

  Moreover, there exists patent document 1 as a technique relevant to the prior art. The power supply device described in Patent Document 1 rectifies and smoothes AC power using a rectifying element and a smoothing capacitor, and uses the switching element to intermittently rectify and smooth the DC power at a frequency higher than the commercial frequency. In a power supply apparatus that supplies DC power to a predetermined load by smoothing, a filter means is provided between the commercial line and the rectifying element in order to prevent noise generated by the switching operation from returning to the commercial power supply. And the filter means has overvoltage prevention means for preventing transient overvoltage caused by external noise such as lightning.

Moreover, there exists patent document 2 as a technique relevant to the prior art. The switching regulator described in Patent Document 2 includes a noise absorption circuit including a series circuit in which a commutation diode and a saturable reactor are connected in series, and a CR snubber circuit connected in parallel to the series circuit. By using a switching regulator, the recovery current from the diode is absorbed, and noise reduction and power supply efficiency are improved.
JP 2003-116267 A Japanese Patent Laid-Open No. 10-262371

  However, in the above-described conventional power supply apparatus, noise generated by a noise source such as the DC / DC converter 1 and circuit components flows to the sheet metal case (frame ground) of the power supply apparatus. There is a problem that noise flows on the control board of the system. Since this noise is output to the output side of the DC-DC converter, for example, a display device, an image with a deteriorated S / N is displayed.

  On the other hand, in Patent Document 1, although conduction of high-frequency noise to the commercial power supply side is prevented, noise on the control board as shown in FIG. 4 cannot be reduced. In Patent Document 2, although noise due to a recovery current from a diode is reduced, noise on a control board as shown in FIG. 4 cannot be reduced.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a power supply device that can reduce noise appearing in an output.

  In order to achieve the above object, a power supply device according to the present invention is connected between input terminals of a noise source circuit that generates noise, and a first series circuit in which a first capacitor and a second capacitor are connected in series, A second series circuit connected between output terminals of the noise source circuit and having a third capacitor and a fourth capacitor connected in series; the noise source circuit, the first series circuit, and the second series circuit; And a metal plate for connecting a connection point of the first capacitor and the second capacitor and a connection point of the third capacitor and the fourth capacitor outside the substrate. To do.

  According to the power supply device according to the present invention, the noise generated in the noise source circuit is generated from the connection point of the third capacitor and the fourth capacitor arranged on the output side via the metal plate on the input side. Feedback is made to the connection point of the first capacitor and the second capacitor.

  Therefore, the amount of noise generated in the noise source circuit is looped in a closed circuit and the amount transmitted to the output is reduced, so that the noise output from the power supply device can be reduced.

  Hereinafter, a power supply device according to an embodiment of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol as the code | symbol used in description of the conventional power supply device is attached | subjected and demonstrated to the part which is the same as that of the structure of the conventional power supply device demonstrated in the background art column, or an equivalent part.

  1 is a side sectional view schematically showing the structure of a power supply device according to Embodiment 1 of the present invention. This power supply apparatus is configured by storing a power supply substrate 20 and a metal plate 2 in a box-shaped sheet metal case 10 constituting a housing.

  The power supply substrate 20 is screwed to a self-stud 41 made of a conductive member fixed to the bottom surface inside the sheet metal case 10 by a substrate fixing screw 42. The power supply board 20 is composed of, for example, a printed wiring board, to which an input cable 21 drawn from the outside of the sheet metal case 10 is connected and an output cable 22 drawn to the outside of the sheet metal case 10 is connected. .

  Further, on the power supply substrate 20, the first line bypass capacitor C1, the second line bypass capacitor C2, the third line bypass capacitor C3, the fourth line bypass capacitor C4, the first capacitor C11, the second capacitor C12, the third capacitor. Electronic components such as C13, a fourth capacitor C14, a first choke coil L1, a second choke coil L2, and a DC / DC converter 1 are mounted. A ground pattern (not shown) formed on the power supply substrate 20 is electrically connected to the sheet metal case 10 via a substrate fixing screw 42 and a self stud 41.

  The metal plate 2 is electrically insulated from the sheet metal case 10, and is screwed to the power supply substrate 20 by a plate fixing screw 44 through a conductive spacer 43. The metal plate 2 is made of, for example, a conductive member, for example, a steel plate, having a thickness of about 1 mm and a surface substantially the same size as the surface of the power supply substrate 20. The length of the spacer 43 is determined so that the distance between the power supply substrate 20 and the metal plate 2 becomes a predetermined value determined by safety standards.

  Although the details will be described later, the connection point of the first capacitor C11 and the second capacitor C12 and the connection point of the third capacitor C13 and the fourth capacitor C14 are electrically connected via the plate fixing screw 44, the spacer 43, and the metal plate 2. Connected.

  Next, an electrical configuration of the power supply device according to the first embodiment configured as described above will be described. FIG. 2 is a circuit diagram illustrating an electrical configuration of the power supply device according to the first embodiment. In this power supply device, a DC voltage (DC input) input between the first input terminal IN1 and the second input terminal IN2 from the input cable 21 is converted into a predetermined DC voltage, and the first output terminal OUT1 is used as a DC output. And the second output terminal OUT2 through the output cable 22.

  This power supply device includes a first line bypass capacitor C1, a second line bypass capacitor C2, a third line bypass capacitor C3, a fourth line bypass capacitor C4, a first capacitor C11, a second capacitor C12, a third capacitor C13, a fourth The capacitor C14, the first choke coil L1, the second choke coil L2, the DC / DC converter 1, and the metal plate 2 are included.

  The first input terminal IN1 is connected to one terminal of the first line bypass capacitor C1 and is connected to one input terminal of the DC / DC converter 1 via the first choke coil L1. The second input terminal IN2 is connected to one terminal of the second line bypass capacitor C2, and is connected to the other input terminal of the DC / DC converter 1 via the first choke coil L1. The other terminal of the first line bypass capacitor C1 and the other terminal of the second line bypass capacitor C2 are connected to the sheet metal case 10 (frame ground).

  Between the input terminals of the DC / DC converter 1, a first series circuit including a first capacitor C11 and a second capacitor C12 connected in series is connected. Specifically, one terminal of the first capacitor C11 is connected to one input terminal of the DC / DC converter 1, and one terminal of the second capacitor C12 is connected to the other input terminal of the DC / DC converter 1. The other terminal of the first capacitor C11 and the other terminal of the second capacitor C12 are connected to the metal plate 2.

  The DC / DC converter 1 corresponds to the noise source circuit of the present invention, and converts a DC voltage input from the first input terminal IN1 and the second input terminal IN2 via the first choke coil L1 into a predetermined DC voltage. And output. One output terminal of the DC / DC converter 1 is connected to the first output terminal OUT1 via the second choke coil L2, and the other output terminal is connected to the second output terminal via the second choke coil L2. Connected to OUT2.

  Further, a second series circuit including a third capacitor C13 and a fourth capacitor C14 connected in series is connected between output terminals of the DC / DC converter 1. Specifically, one terminal of the third capacitor C13 is connected to one output terminal of the DC / DC converter 1, and one terminal of the fourth capacitor C14 is connected to the other output terminal of the DC / DC converter 1. The other terminal of the third capacitor C13 and the other terminal of the fourth capacitor C14 are connected to the metal plate 2.

  Further, one terminal of the third line bypass capacitor C3 is connected to the first output terminal OUT1, and one terminal of the fourth line bypass capacitor C4 is connected to the second output terminal OUT2. The other terminal of the 3-line bypass capacitor C3 and the other terminal of the fourth line bypass capacitor C4 are connected to the sheet metal case 10 (frame ground).

  In the power supply device according to the first embodiment of the present invention configured as described above, as in the conventional power supply device, the first line bypass capacitor C1, the second line bypass capacitor C2 and the first line bypass capacitor C1 arranged on the input side are arranged. The filter configured by the choke coil L1 removes noise input from the input cable 21, and includes a third line bypass capacitor C3, a fourth line bypass capacitor C4, and a second choke coil L2 arranged on the output side. The noise output to the output cable 22 is removed by the filtered filter.

  Furthermore, the noise generated in the DC / DC converter 1 is the second noise that is arranged on the input side from the connection point of the third capacitor C13 and the fourth capacitor C14 via the metal plate 2 as indicated by an arrow in FIG. Feedback is made to the connection point between the first capacitor C11 and the second capacitor C12.

  Therefore, the noise generated in the DC / DC converter 1 loops in a closed circuit, and the amount transmitted to the first output terminal OUT1 and the second output terminal OUT2 decreases. Therefore, noise output from the power supply device can be reduced.

  In the above configuration, instead of the metal plate 2, a wiring pattern is formed on the power supply substrate 20, and the connection point between the first capacitor C11 and the second capacitor C12, and the connection point between the third capacitor C13 and the fourth capacitor C14. It is also conceivable to configure such that However, in the case of this configuration, depending on the voltage to be handled, there may be a case where the creepage distance cannot be sufficiently secured and a predetermined standard cannot be satisfied.

  On the other hand, according to the power supply device according to the first embodiment, the conductor connecting the connection point of the first capacitor C11 and the second capacitor C12 and the connection point of the third capacitor C13 and the fourth capacitor C14 is connected to the power supply. Since it is configured to be provided independently of the substrate 20, a sufficient creepage distance can be secured and various standards can be accommodated.

  In the power supply device according to the first embodiment described above, the case where DC power is input has been described. However, even when AC power is input, noise output from the power supply device is reduced with the same configuration as described above. Can be made.

  FIG. 3 is a circuit diagram showing an electrical configuration of a power supply device for inputting AC power. In this power supply device, AC power (AC input) input between the first input terminal IN1 and the second input terminal IN2 from the input cable 21 is converted into a predetermined DC voltage, and the first output terminal OUT1 as a DC output. And the second output terminal OUT2 through the output cable 22.

  This power supply apparatus is configured by adding a rectifying and smoothing circuit 3 between the first choke coil L1 and the DC / DC converter 1 of the power supply apparatus according to the first embodiment shown in FIG. The rectifying / smoothing circuit 3 rectifies the AC voltage input between the first input terminal IN1 and the second input terminal IN2 by the diode bridge circuit DB, smoothes it by the smoothing capacitor C20, and outputs it. The output of the rectifying / smoothing circuit 3 is sent to the DC / DC converter 1.

  In the power supply device configured as described above, a filter including a first line bypass capacitor C1, a second line bypass capacitor C2, and a first choke coil L1 disposed on the input side, as in the conventional power supply device. To remove noise input from the input cable 21 and output to the output cable 22 by a filter composed of the third line bypass capacitor C3, the fourth line bypass capacitor C4, and the second choke coil L2 arranged on the output side. Noise is eliminated.

  Further, the noise generated in the DC / DC converter 1 is, as indicated by arrows in FIG. 3, the first capacitor C11 disposed on the input side from the third capacitor C13 and the fourth capacitor C14 via the metal plate 2. And fed back to the second capacitor C12.

  Therefore, the noise generated in the DC / DC converter 1 is looped in a closed circuit, and the amount transmitted to the first output terminal OUT1 and the second output terminal OUT2 is reduced. Therefore, noise output from the power supply device can be reduced.

  The present invention is applicable to a switching power supply such as a DC-DC converter.

It is a sectional side view which shows roughly the structure of the power supply device which concerns on Example 1 of this invention. It is a circuit diagram which shows the electric constitution of the power supply device which concerns on Example 1 of this invention. It is a circuit diagram which shows the electric constitution of the power supply device which concerns on the modification of Example 1 of this invention. It is a circuit diagram which shows the electrical structural example of the conventional power supply device. It is a circuit diagram which shows the electrical structural example of the other conventional power supply device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 DC / DC converter 2 Metal plate 3 Rectification smoothing circuit 5 1st series circuit 6 2nd series circuit C1-C4 1st-4th line bypass capacitor C11-C14 1st-4th capacitor L1 1st choke coil L2 2nd Choke coil 10 Sheet metal case 20 Power supply board 21 Input cable 22 Output cable 41 Self-stud 42 Board fixing screw 43 Spacer 44 Plate fixing screw

Claims (3)

A first series circuit connected between input terminals of a noise source circuit for generating noise and having a first capacitor and a second capacitor connected in series;
A second series circuit connected between the output terminals of the noise source circuit and having a third capacitor and a fourth capacitor connected in series;
A substrate on which the noise source circuit, the first series circuit and the second series circuit are mounted;
A metal plate for connecting a connection point of the first capacitor and the second capacitor and a connection point of the third capacitor and the fourth capacitor outside the substrate;
A power supply device comprising:   2. The power supply apparatus according to claim 1, wherein the noise source circuit comprises a DC / DC converter that converts a DC voltage input from the outside into a DC voltage of another magnitude. It has a rectifying and smoothing circuit that converts AC voltage input from the outside into DC voltage,
2. The power supply apparatus according to claim 1, wherein the noise source circuit comprises a DC / DC converter that converts a DC voltage obtained from the rectifying / smoothing circuit into a DC voltage of another magnitude.

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