JP4520205B2 - Switching power supply - Google Patents

Description

The present invention relates to a switching power supply device in which a low-pass filter is provided in a DC output smoothing circuit.

  2. Description of the Related Art Conventionally, in a switching power supply device capable of outputting a large current DC, a low-pass filter capable of outputting a large current is provided in a DC output smoothing circuit to reduce noise.

This output low-pass filter is composed of a series inductance and a capacitor, and in order to allow a large current to flow through the series inductance, conventionally, a cable is wound around a printed circuit board and placed horizontally, and crimp terminals provided at both ends. Is screwed onto the substrate (Patent Document 1).
Japanese Patent Laid-Open No. 11-122911

  However, in such a low-pass filter using a cable as an inductance, there is a problem that assembling takes time and cost because the cable is provided with a crimp terminal and mechanically connected to a printed circuit board with screws. There is.

  In addition, since a flexible cable is wound and used as an inductance, it can be easily moved, and the position as the inductance is unstable without being determined, and the distribution of the magnetic field generated from the inductance itself varies depending on the state of the cable, There is a problem that an AC input filter disposed in the vicinity is easily affected.

  Furthermore, since the cable is arranged horizontally with respect to the printed circuit board, an arrangement area on the printed circuit board corresponding to the size of the coil around which the cable is wound is necessary, which is an obstacle to miniaturization of the switching power supply device. .

The present invention requires a small installation space, can be easily mounted on a printed circuit board, and constitutes an output low-pass filter with an inductance that does not affect the case where AC input filters are arranged close to each other. The purpose is to provide.

  In order to achieve this object, the present invention is configured as follows. The present invention relates to a switching power supply device in which a DC output smoothing circuit is arranged at the shortest distance on a DC output terminal block on a printed circuit board. The DC output smoothing circuit is connected to a smoothing capacitor and a smoothing circuit on the printed circuit board from the DC output terminal block side. The choke coils are sequentially arranged, and a plate-like inductance is arranged in parallel between the smoothing capacitor and the smoothing choke coil. Here, the plate-like inductance is a U-shape opened downward.

According to another aspect of the present invention, there is provided a switching power supply device which is arranged close to an AC input line filter on a printed circuit board and has a DC output smoothing circuit arranged at a shortest distance on a DC output terminal block. The DC output smoothing circuit sequentially arranges the smoothing capacitor and the smoothing choke coil on the printed circuit board from the DC output terminal block side, and arranges the plate inductance in parallel between the smoothing capacitor and the smoothing choke coil. The shape inductance is characterized by having a substantially U-shape opened downward with the AC line filter side as an inclined plate portion.

  According to the present invention, the plate-like inductance can be manufactured by metal stamping, the production cost is low and the shape as the inductance is fixed, and it can be inserted into the printed circuit board and automatically assembled such as flow soldering, when a cable is used There is no instability as manual work or inductance.

In addition, the low-pass filter that can be placed in the space between the smoothing capacitor and the smoothing choke coil in the DC output smoothing circuit and can output a large current without increasing the board space by mounting upright on the printed circuit board. In addition, a large current capacity is secured by a sufficient plate width, and it is suitable for use with a large current.

  FIG. 1 is an explanatory view showing a circuit arrangement on a printed board of the switching power supply device of the present invention. In FIG. 1, a terminal block 2 is provided on the left side of a printed circuit board 1 used for the switching power supply of the present invention, and the terminal block 2 is provided with AC input terminals 3a and 3b and DC output terminals 22a and 22b. .

  Following the AC input terminals 3a and 3b, an AC input line filter 4 is provided. The AC input line filter 4 includes a capacitor 5, a balun coil 6, and a capacitor 7.

  Subsequently, a rectifier circuit 8 using a diode bridge or the like is provided, and an input capacitor 9 is provided on the output side of the rectifier circuit 8 to obtain a DC input. Subsequently, an active filter circuit 10 is provided to suppress the generation of noise by switching control so that the power factor of the current and voltage of the full-wave rectified output of the rectifier circuit 8 is 1.

  Subsequently, an inverter circuit 11 is provided. The inverter circuit 11 performs switching control of a switching element 15 such as an FET connected in series to the primary winding 13 of the transformer 12. In this switching control, the on-time of the switching element 15 is controlled, for example, by pulse width so that the output voltages of the DC output terminals 22a and 22b are stabilized at a specified voltage.

  Rectifier diodes 16 and 17 are provided for the secondary winding 14 of the transformer 12. Following the rectifier diodes 16 and 17, a toroidal choke coil 18 and a smoothing electrolytic capacitor 19 are provided to constitute an output smoothing circuit. Subsequently, a plate inductance 20 and a filter electrolytic capacitor 21 are provided to constitute a low-pass filter. The output of the low-pass filter is connected to DC output terminals 22a and 22b.

  FIG. 2 is an explanatory diagram of component arrangement on the printed circuit board of the DC output smoothing circuit portion in the switching power supply device of the present invention. In FIG. 2, the terminal block 2 is mounted on the left side of the printed circuit board 1, and the terminal block 2 is provided with AC input terminals 3a and 3b and DC output terminals 22a and 22b.

  Following the AC input terminals 3a and 3b side of the terminal block 2, a capacitor 5, a balun coil 6 and a capacitor 7 are sequentially arranged on the printed circuit board 1 to constitute an AC input line filter 4. A DC output smoothing circuit and a low-pass filter are provided close to the DC output terminals 22a and 22b of the terminal block 2 on the lower side of the AC input line filter 4 at the shortest distance.

  That is, the smoothing electrolytic capacitor 19 and the filter electrolytic capacitor 21 are arranged on the printed circuit board 1 side by side in the direction of the terminal block 2 from the DC output terminals 22a and 22b side of the terminal block 2, and the toroidal choke coil 18 on the right side thereof. Is arranged.

  Between the smoothing electrolytic capacitor 19 and the filter electrolytic capacitor 21 and the toroidal choke coil 18 arranged in parallel, the plate-like inductance 20 according to the present invention is orthogonal to the arrangement direction of the circuit components in the horizontal direction, and the toroidal choke The coil 18, the smoothing electrolytic capacitor 19, and the filter electrolytic capacitor 21 are arranged in parallel with each other.

  FIG. 3 is an explanatory view of the plate-like inductance 20 used in the embodiment of FIG. 2, and FIG. 3 (A) shows a side view and FIG. 3 (B) shows a front view. The plate-like inductance 20 has a horizontal plate portion 24 following a vertical plate portion 23 integrally formed with a terminal 27 at a lower portion, and a tapered plate portion 25 is formed obliquely downward from the horizontal plate portion 24 to form a vertical plate portion 26. The terminal 28 is formed on the lower side of the vertical plate portion 26. The plate-like inductance 20 shown in FIG. 3 has a taper plate portion 25 arranged on the printed circuit board 1 shown in FIG. 2 facing the AC input line filter 4 side.

  FIG. 4 is an explanatory diagram of another embodiment of the plate-like inductance used in the present invention. The plate-like inductance 30 in FIG. 4 has a horizontal plate portion 34 following a vertical plate portion 33 provided with terminals 37 on the lower side, a vertical plate portion 36 provided following the horizontal plate portion 34, and a lower side thereof. A terminal 38 is formed. 4A is a side view and FIG. 4B is a front view.

  Here, when the plate-like inductance 20 of FIG. 3 and the plate-like inductance 30 of FIG. 4 are compared, both have a substantially U-shaped shape opened downward, but the plate-like inductance 20 of FIG. However, as shown in FIG. 2, it is different in that it has a downwardly open U-shape with a tapered plate portion 25 located on the AC input line filter 4 side.

  FIG. 5 is an explanatory diagram of how to use the plate-like inductance 20 of FIG. 3 and the plate-like inductance 30 of FIG. FIG. 5A shows the plate-like inductance 20 arranged on the printed circuit board 1 of FIG. 2 together with the balun coil 6 of the AC input line filter 4 when viewed from the lateral direction. FIG. 5B shows a state in which the plate-like inductance 30 shown in FIG. 4 is arranged instead of the plate-like inductance 20 shown in FIG.

  Here, when a DC output current flows through the plate-like inductance 20 in FIG. 5A and the plate-like inductance 30 in FIG. 5B, a magnetic field is generated around each plate portion. At this time, in the plate-like inductance 30 in FIG. 5B, a magnetic field 39 is generated by the output current flowing through the vertical plate portion 36, and this magnetic field 39 is the balun coil 6 in the adjacent AC input line filter 4. Will increase the input noise.

  Therefore, in the present invention, when the DC output circuit is arranged close to the AC input line filter, the plate-like inductance 20 having the taper plate portion 25 is used as shown in FIG. The part 25 is arranged so as to be located on the balun coil 6 side. For this reason, when a DC output current flows through the plate-like inductance 20, a magnetic field 29 is generated on the surface perpendicular to the direction of the taper plate portion 25 in the taper plate portion 25, and the magnetic field 29 does not penetrate the balun coil 6. The problem of increasing input noise can be solved.

  On the other hand, when the AC input line filter 4 is not disposed close to the printed circuit board, specifically, a circuit in which an AC input terminal is provided on one side of the printed circuit board and a DC output terminal is provided on the opposite side of the printed circuit board. In the case of arrangement, the plate-like inductance 30 shown in FIG. 4 may be used.

  Further, the plate-like inductances 20 and 30 shown in FIGS. 3 and 4 can be easily made by pressing a metal plate. The terminals 27 and 28 or the terminals 37 and 38 are inserted on the printed circuit board, respectively, and flow soldering or the like. It can be easily mounted by automatic assembly.

  In addition, by adjusting the plate width in the plate-like inductances 20 and 30, a sufficient current capacity corresponding to the required DC output current can be easily and easily ensured. Furthermore, since the plate-like inductances 20 and 30 are plate members that stand up from the printed circuit board 1, they have a function as a heat radiating plate by themselves, and even if heat is generated when a large current is passed, heat is efficiently radiated. can do.

In the above-described embodiment, the plate-shaped inductance is taken as an example in which the plate-shaped inductance is opened downward in a U-shape. However, the present invention is not limited to this, and the U-shape is formed in the downward direction. Any shape can be used as long as it is an open shape or a polygonal shape other than a U-shape. When any shape is placed close to the AC input line filter, the taper plate portion is placed on the AC input line filter side. 25 may be formed.

Explanatory drawing which showed circuit arrangement | positioning on the printed circuit board of the switching power supply device of this invention Explanatory drawing of component arrangement | positioning in the printed circuit board of the DC output smoothing circuit part in the switching power supply device of this invention Explanatory drawing of embodiment of the plate-shaped inductance used by this invention Explanatory drawing of other embodiment of the plate-shaped inductance used by this invention Explanatory drawing which showed the influence to the AC input line filter of the magnetic field which generate | occur | produces with the plate-shaped inductance of this invention

Explanation of symbols

1: Printed circuit board 2: Terminal block 3a, 3b: AC input terminal 4: AC input line filter 5, 7: Capacitor 6: Balun coil 8: Rectifier circuit 9: Input capacitor 10: Active filter circuit 11: Inverter circuit 12: Transformer 13: primary winding 14: secondary winding 15: switching element 16, 17: rectifier diode 18: toroidal choke coil 19: smoothing electrolytic capacitor 20, 30 plate-like inductance 21: filter electrolytic capacitors 22a, 22b: DC output terminals 23, 26, 33, 36: vertical plate portions 24, 34: horizontal plate portions 25: taper plate portions 27, 28, 37, 38: terminals 29, 39: magnetic fields

Claims (3)

In a switching power supply device in which a DC output smoothing circuit composed of a smoothing capacitor and a smoothing choke coil and a subsequent low-pass filter composed of an inductance and an electrolytic capacitor are arranged on the DC output terminal block on the printed circuit board at the shortest distance. And
The inductance is plate-shaped,
In order from the DC output terminal block side to the printed circuit board, a smoothing capacitor and an electrolytic capacitor are arranged in parallel to the DC output terminal block, and then the plate-like inductance is orthogonal to the arrangement direction of the circuit components in the horizontal direction. And arranging in parallel with the arrangement direction of the electrolytic capacitor for the smoothing capacitor filter, and further, arranging the smoothing choke coil,
A switching power supply device.
2. The switching power supply device according to claim 1, wherein the plate-like inductance is a U-shape opened downward.
Arranged close to the AC input line filter on the printed circuit board, the DC output terminal block is composed of a DC output smoothing circuit composed of a smoothing capacitor and a smoothing choke coil , followed by an inductance and an electrolytic capacitor. In a switching power supply device in which a low-pass filter is arranged at the shortest distance,
The inductance is plate-shaped,
The AC input line filter is disposed at a position orthogonal to the plate-shaped inductance horizontal plate,
In order from the DC output terminal block side to the printed circuit board, a smoothing capacitor and an electrolytic capacitor are arranged in parallel to the DC output terminal block, and then the plate-like inductance is orthogonal to the arrangement direction of the circuit components in the horizontal direction. And arranged parallel to the direction in which the electrolytic capacitors for the smoothing capacitor filter are arranged, and further, the smoothing choke coil is arranged,
The switching power supply device according to claim 1, wherein the plate-like inductance has a substantially U-shape opened downward with the AC input line filter side as an inclined plate portion.

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