JPH04171705A - Switching power unit - Google Patents

Abstract

PURPOSE:To relax the restriction in the arrangement of parts and to make thin the device and improve the heat radiation property by using a plurality of transformers small in all of length, width, and height. CONSTITUTION:Noise components of AC voltage are removed by a filter 11, and then full-wave rectification is performed with a rectifier 12, and it is accumulated as charge in a capacitor 13 for smoothing. Next, by the driving of a switching element 14, it becomes a current and flows to the primary winding of a transformer 15. Next, electromotive force is induced in the secondary winding of the transformer 15, and it is rectified with a rectifying diode 16, and is smoothed with a capacitor 17, and is supplied to a load. And this transformer 15 is composed of three pieces of transformers T1, T2, and T3, and the number of windings and the current to flow are made approximately one third, respectively. Hereby, the compactification of a device is realized and the transformer breakdown by temperature rise can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a switching power supply device that obtains a constant DC voltage necessary for operating an electronic device or the like from, for example, a commercial power source.

(Prior Art) Conventionally, in various electronic devices, a switching power supply device for obtaining a constant DC voltage from a commercial power supply voltage has been used.

FIG. 5 is a circuit diagram showing the basic configuration of this switching power supply device.

In the figure, 1 is a filter that removes noise components of AC voltage taken in from a commercial power supply AC, 2 is a rectifier that full-wave rectifies the AC voltage after passing through the soil coil 1, and 3 is a smoother that smoothes the voltage after full-wave rectification. 4 is a switching element such as a power transistor. Further, 5 is a transformer for transmitting the energy of the primary side circuit to the secondary side circuit, 6 is a rectifier diode that rectifies the voltage induced in the secondary winding of the transformer 5, and 7 is a compressor for compressing the voltage ripple after rectification. It is a capacitor for Further, reference numeral 8 insulates the output voltage V OUT obtained from the secondary circuit through a photocoupler (not shown), compares it with a reference value, and adjusts the pulse-on width of the switching cable 4 so that the difference becomes zero. 9 is a snubber circuit that consumes the energy stored in the primary winding of the transformer 5 after the switching cable 4 is turned off.

Next, the operation of this switching power supply device will be explained. First, an alternating current voltage taken in from a commercial power supply AC is filtered to remove noise components by a filter 1, then full-wave rectified by a rectifier 2, and stored in a smoothing capacitor 3 as an electric charge. Thereafter, the charges accumulated in the smoothing capacitor 3 flow as a current to the primary winding of the transformer 5 by driving the switching cable 4. As a result, an electromotive force is induced in the secondary winding of the lance 6, and the induced voltage is transferred to the rectifier diode 6.
The signal is rectified by a capacitor 7, smoothed by a capacitor 7, and then supplied to a load.

Incidentally, in such a switching power supply device, the size of the transformer 5 is a major factor in determining the overall size of the device. In other words, as shown in FIG. 6, the transformer 5 is constructed by winding the primary and secondary wires 5b around a magnetic core 5a multiple times (=I), and the larger the current flowing, the thicker the wire 5b is used. This is because it is a component that is extremely difficult to make compact.

(Problem to be Solved by the Invention) Therefore, in the conventional switching power supply device, it is necessary to pay attention to securing space for arranging the transformer at the design stage, and even if all the components are arranged well, the transformer There is a problem in that there is a limit to how thin the device can be made depending on the height of the device.

The present invention has been made to solve these problems, and it is an object of the present invention to provide a switching power supply device that can effectively reduce restrictions on component placement and make the device thinner, and that also has excellent heat dissipation of the transformer. The purpose is

[Structure of the Invention (Means for Solving the Problems) In order to achieve the above-mentioned object, the switching power supply device of the present invention switches the supply of DC current to the transformer and supplies it to the secondary circuit of the I-lance. A switching power supply device that transmits energy is characterized in that the transformer is composed of a plurality of transformers.

(Function) In the present invention, since a switching power supply device is configured using a plurality of transformers, the size of each transformer is small in length, width, and height. As a result, restrictions on component placement are reduced and It is possible to effectively reduce the thickness of the device, and by increasing the total surface area of the transformer, heat dissipation is improved, and heat damage to the transformer can be prevented.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a circuit diagram showing the configuration of a switching power supply device according to an embodiment of the present invention.

In the figure, 11 is a filter that removes the noise component of the AC voltage taken in from the commercial power supply AC, 12 is a rectifier that full-wave rectifies the AC voltage after passing through the soil coil 11, and 13 is a smoother that smoothes the voltage after full-wave rectification. smoothing capacitor for
14 is a switching element such as a power transistor. Further, 15 is a transformer for transmitting the energy of the primary side circuit to the secondary side circuit, and in this embodiment, a plurality of transformers Tl, T2, and T3 are combined to form a target transformer. Here, the primary windings of the transformers TI, T2, and T3 are connected in series in the primary circuit, and the secondary windings are connected in parallel in the secondary circuit. Furthermore, 16 is a rectifier diode that rectifies the voltage induced in the secondary winding of each transformer T1, T2, and T3;
] 7 is a capacitor for compressing the voltage ripple after rectification. 18 is the output voltage V obtained from the secondary side circuit.
A pulse width control unit 19 is a pulse width control unit that takes in OUT insulatively through a photocoupler (not shown), compares it with a reference value, and controls the pulse-on width of the switching element 14 so that the difference becomes zero. After turn-off, the snubber circuit consumes the energy stored in each secondary winding of transformers TI, T2, and T3.

Next, the operation of this switching power supply device will be explained. First, an alternating current voltage taken in from a commercial power source AC is filtered to remove noise components by a filter 11, then full-wave rectified by a rectifier 12, and stored in a smoothing capacitor 3 as an electric charge. Thereafter, the electric charge accumulated in the smoothing capacitor 13 flows as a current to the primary winding of each transformer TI, T2, and T3 by driving the switching element 14. As a result, an electromotive force is induced in the secondary winding of each transformer TI, T2, T3, and the induced voltage is transferred to the rectifier diode 1.
The signal is rectified by 6, smoothed by a capacitor 17, and then supplied to the load.

Now, in the switching power supply device of this embodiment, as shown in FIG. 2(a), the target transformer 15 is constructed using a plurality of (three in this embodiment) transformers TI, T2, and T3. . These transformers T1, T2, T3 are
A conventional single transformer T shown in FIG. 2(b)
Since the number of windings and the flowing current are approximately 1/3 compared to transformer a, the vertical, horizontal, and height dimensions are significantly smaller than the conventional transformer Ta. Therefore, constraints on component placement such as securing space for arranging the transformer within the device from the beginning are reduced at the design stage, etc., and the height of the device is also reduced, making the overall device more compact. It becomes possible to achieve this goal.

In addition, in the switching power supply device of this embodiment, the heat generation due to energy loss is shared between the transformers Tl, T2, and T3, and the total surface area of the transformers Tl, T2, and T3 is increased as a result, so that transformer breakdown due to temperature rise is avoided. Preventable.

In the above embodiment, the secondary windings of the transformer 15 are connected in parallel, but the present invention is not limited to this.

For example, each secondary winding of the transformer 15 may be connected in series, or as shown in FIG. The present invention is also applicable to Further, as shown in FIG. 4, the present invention also includes a case where the respective secondary windings of the transformer 15 are connected in parallel and series. Furthermore, in FIG. 3, the secondary windings of transformers TI and T2 connected in parallel and the secondary winding of transformer T3 are connected in series, and in FIG. 4, the transformers TI and T2 are connected in parallel. The present invention is also applicable to a configuration in which each secondary winding of T2 and each secondary winding of transformers T3 and T4 are connected in series. In this way, the connection of each secondary winding and the connection of each secondary winding of the transformer 15 may be series, parallel, or parallel-series.

Furthermore, in application of the present invention, there is of course no upper limit to the number of transformers.

Furthermore, in FIG. 1, it is assumed that each transformer TI.

When the primary windings T2 and T3 are connected in parallel, taking into consideration the variations in the output of each secondary side, between a and d, between b and e,
A rectifier diode (not shown) may be additionally connected between c and d.

[Effects of the Invention] As explained above, according to the switching power supply device of the present invention, since the switching power supply device is configured using a plurality of transformers, the size of each transformer is small in length, width, and height. As a result, it is possible to effectively reduce restrictions on component placement and make the device thinner.
Moreover, by increasing the total surface area of the transformer, heat dissipation is improved and breakage of the transformer can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram for explaining the configuration of a switching power supply according to an embodiment of the present invention, and FIG. 2 compares the appearance of a transformer group used in the switching power supply of FIG. 1 with a conventional transformer. 3 and 4 are respectively circuit diagrams for explaining other embodiments of the present invention, and FIG. 5 is an l++l circuit diagram for explaining the configuration of a conventional switching power supply device. FIG. 6 is a perspective view showing the appearance of a transformer used in the switching power supply device of FIG. 5. DESCRIPTION OF SYMBOLS 11... Filter, 12... Rectifier, 13... Smoothing capacitor, 14... Switching element, 15
(Tl, T2, T3)...Transformer, 16...Rectifier diode, 17...Capacitor, 18...Pulse width control unit, 19...Snubber circuit. Applicant Toshiba Corporation Agent Patent Attorney Suyama Sa-L” 〉 IO□

Claims (1)

[Claims] A switching power supply device that switches the supply of direct current to a transformer and transmits energy to a secondary circuit of the transformer, characterized in that the transformer is composed of a plurality of transformers. switching power supply.