WO2015063870A1

WO2015063870A1 - Switching power supply apparatus

Info

Publication number: WO2015063870A1
Application number: PCT/JP2013/079298
Authority: WO
Inventors: 政巳上原; 和仁山岸
Original assignee: 株式会社テーケィアール
Priority date: 2013-10-29
Filing date: 2013-10-29
Publication date: 2015-05-07
Also published as: JP6393689B2; JPWO2015063870A1

Abstract

Provided is a switching power supply apparatus whereby an output voltage can be stabilized without having an extra winding of a transformer. This switching power supply apparatus is provided with a transformer having a primary winding, a secondary winding, and a bias winding, has a power supply connected to a switching element via the primary winding, and controls the switching element by means of an output from the bias winding, thereby outputting a stabilized voltage from the secondary winding. The bias winding of the transformer can be configured from a plurality of bias windings having an equal winding number by setting the winding number of the bias windings equal to that of another primary winding, the bias windings are connected in parallel, and the secondary winding of the transformer is wound to be sandwiched between the bias windings.

Description

Switching power supply

The present invention relates to a switching power supply device using a transformer.

Some switching power supply devices are referred to as an insulation type that transmits power by isolating a primary circuit and a secondary circuit using a transformer. As a method using a transformer, a method for controlling the switching of a semiconductor element by detecting the output on the secondary side and feeding back using, for example, a photocoupler, a winding for detection is provided in the transformer, and the output is used for semiconductors. There is a method for controlling element switching (primary side detection control method). In the case of a method using a photocoupler, since the output on the secondary side is directly detected, the output accuracy is good, but an expensive photocoupler is necessary, and the circuit becomes complicated. On the other hand, in the case of the primary side detection control system, the output stability is not so good, but the circuit becomes simple and the cost can be reduced.

As a switching power supply device that performs constant voltage control only on the primary side of a transformer without using a photocoupler, Patent Document 1 discloses a transformer having a primary winding, a secondary winding, and a bias winding, and a primary winding of the transformer. Switching element connected in series to the wire, one end of the bias winding of the transformer is connected to the control electrode of the switching element, the other end is connected to the ground line, and a specific oscillation control is performed on the primary side of the transformer A self-excited switching power supply that performs constant voltage control of the output voltage on the secondary side by providing a circuit is described.

Patent document 2 discloses in claim 1 that “a DC input voltage obtained by rectifying and smoothing a DC voltage or an AC voltage, a primary circuit including at least a primary control circuit and a main switching element, 1 A switching transformer having a bias circuit for supplying to the secondary side control circuit and a secondary side rectifying and smoothing circuit, and lines corresponding to the number of turns so as to be tightly wound between the primary winding and the secondary winding of the switching transformer. When the diameter is changed or the number of turns is small, a switching power supply device provided with a bias winding in which several wires are wound in parallel is described.

Japanese Patent Laid-Open No. 5-304778 JP-A-9-74754

The switching power supply device of Patent Document 1 does not use a photocoupler, but it is necessary to provide a specific oscillation control circuit on the primary side of the transformer. Further, the switching power supply device of Patent Document 2 reduces the switching noise without providing a shield winding by providing a bias winding between the primary winding and the secondary winding of the switching transformer. .

An object of the present invention is to provide a switching power supply capable of stabilizing an output voltage without adding a transformer winding.

In order to achieve the above object, the present invention adopts the structure described in the claims.

The present invention includes a plurality of means for solving the above-described problems. If an example of the switching power supply device of the present invention is given, a transformer having a primary winding, a secondary winding, and a bias winding is provided. A switching power supply that outputs a stabilized voltage from the secondary winding by connecting the switching element via the primary winding and controlling the switching element by the output of the bias winding, The bias winding of the transformer is composed of a plurality of bias windings having the same number of turns, the plurality of bias windings are connected in parallel, and the secondary winding of the transformer is sandwiched between the plurality of bias windings. Is wound around

To give another example of the switching power supply device of the present invention, a transformer having a primary winding, a secondary winding and a bias winding is provided, and a power source is connected to the switching element via the primary winding. In the switching power supply that outputs a stabilized voltage from the secondary winding by controlling the switching element by the output of the bias winding, the transformer is further the same as the second primary winding. The bias winding of the number of turns is provided, the bias winding and the second primary winding are connected in parallel, and the secondary winding of the transformer is connected to the bias winding and the second primary winding. It is wound so as to be sandwiched between and.

According to the present invention, by improving the winding structure of the transformer, it is possible to stabilize the output voltage of the switching power supply device without adding a winding, thereby reducing the size and cost of the transformer, and consequently the power supply. Miniaturization and cost reduction of the device can be achieved.

It is a circuit diagram of the switching power supply circuit examined in the process leading to the present invention. It is a figure which shows the transformer structure of the switching power supply circuit examined in the process leading to this invention. It is a figure which shows the transformer structure of the switching power supply circuit of Example 1 of this invention. It is a circuit diagram of the switching power supply circuit of Example 2 of this invention. It is a figure which shows the transformer structure of the switching power supply circuit of Example 2 of this invention. It is a figure which shows the relationship between load current and an output voltage (with load current). It is a figure which shows the relationship between load current and output voltage (no load current).

The switching power supply device studied in the process leading to the preferred embodiment of the present invention will be described.

Fig. 1 shows a switching power supply of the primary side detection control system (Primary Side Sensing Regulation). Although not shown, for example, a direct current obtained by full-wave rectifying the alternating current of a commercial power supply of 100 V with a bridge rectifier circuit is input to the input terminal Vi of the switching power supply device. This direct current is applied to the switching transistor in the switching IC 20 via the smoothing capacitor 22 and the primary winding P1 of the transformer 10. The outputs of the secondary windings S1 and S2 of the transformer are rectified and smoothed by a circuit including a diode 23 and a smoothing capacitor 24, and output as, for example, a DC of 12V. As described in detail in FIG. 2, the secondary winding has a configuration in which two windings S1 and S2 having the same number of turns are connected in parallel. The transformer 10 is provided with a feedback bias winding PB. The output of the transformer 10 is applied to the feedback terminal FB of the switching IC 20 and is converted into a direct current by a rectifier circuit including a diode 25 and a smoothing capacitor 26. Applied to the power supply terminal Vcc of the switching IC 20. The transformer 10 is also provided with a second primary winding P2, and its output is converted into a direct current by a rectifier circuit composed of a diode 27 and a smoothing capacitor 28. Used for power supply.

Fig. 2 shows the winding structure of the transformer 10. The figure shows a cross section of one side of the transformer. As the winding 14, a primary winding P 1, a secondary winding S 1, a bias winding PB, a secondary winding S 2, and a second primary winding P 2 are wound around the bobbin 16 in order. Here, the secondary winding is composed of S1 and S2 having the same number of turns, and the bias winding PB is sandwiched between the secondary windings S1 and S2, thereby increasing the degree of coupling between the bias winding and the secondary winding. I can raise it. Thereby, the sensitivity of feedback control can be increased and the output voltage of the secondary output can be stabilized. In the figure, reference numeral 12 denotes a transformer core, and reference numeral 17 denotes a terminal.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that components having the same function are denoted by the same names and reference numerals in the drawings for describing the embodiments, and repetitive description thereof is omitted.

According to the study by the present inventors, it was found that the degree of coupling between the secondary winding and the bias winding is not necessarily sufficient in the winding structure shown in FIGS. Therefore, the present inventors have realized that the magnetic adhesion between the secondary winding and the bias winding is improved, the degree of coupling is increased, and the output voltage of the switching power supply circuit is stabilized.

FIG. 3 shows a transformer winding structure of the switching power supply circuit according to the first embodiment of the present invention. In this embodiment, as shown in the circuit diagram of the transformer 10, the bias winding is composed of two windings PB-1 and PB-2 having the same number of turns, and the two windings are connected in parallel. As shown in the winding structure, the bobbin 16 has, as the winding 14, a primary winding P1, a secondary winding S1, a bias winding PB-1, a secondary winding S2, and a bias winding PB- in order. 2. Wind the second primary winding P2. The secondary winding S2 is sandwiched between two bias windings PB-1 and PB-2.

In FIG. 3, the secondary winding is composed of two windings having the same number of turns, and the secondary winding and the bias winding are alternately arranged. The degree of coupling can be increased by adopting a structure in which the secondary winding is a single winding and the secondary winding is sandwiched between two bias windings. In particular, as shown in FIG. 3, the secondary winding is also composed of two windings having the same number of turns and sandwiched between each other, thereby further increasing the degree of coupling between the secondary winding and the bias winding. it can. Further, the degree of coupling can be further increased by using three or more bias windings or secondary windings and sandwiching each other.

According to this embodiment, the bias winding is composed of two windings having the same number of turns, the two bias windings are connected in parallel, and the secondary winding is wound so as to be sandwiched between the two bias windings. Thus, the magnetic adhesion between the secondary winding and the bias winding can be improved, and the degree of coupling can be increased. Thereby, the sensitivity of feedback control can be increased and the output voltage can be stabilized.

According to Example 1 in FIG. 3, the degree of coupling can be increased by configuring the bias winding with two windings and sandwiching the secondary winding. However, the addition of the bias winding PB-2 increases the size of the transformer and increases the cost. In the second embodiment, the degree of coupling is increased without adding a bias winding.

FIG. 4 shows a circuit diagram of the switching power supply device according to the second embodiment of the present invention. For example, a direct current obtained by full-wave rectifying the alternating current of a commercial power supply of 100 V with a bridge rectifier circuit is input to the input terminal Vi of the switching power supply device. This direct current is applied to the switching transistor in the switching IC 20 via the smoothing capacitor 22 and the primary winding P1 of the transformer 10. The outputs of the secondary windings S1 and S2 of the transformer are rectified and smoothed by a circuit including a diode 23 and a smoothing capacitor 24, and output as, for example, a DC of 12V. The secondary winding has a configuration in which two windings S1 and S2 having the same number of turns are connected in parallel. The bias winding of the transformer 10 is composed of two bias windings PB-1 and PB-2 having the same number of turns, and the two bias windings PB-1 and PB-2 are connected in parallel. Yes. The output of the bias winding is applied to the feedback terminal FB of the switching IC 20, converted into a direct current by a rectifier circuit including the diode 25 and the smoothing capacitor 26, and applied to the power supply terminal Vcc of the switching IC 20. Further, the output of the bias winding is converted into a direct current by a rectifier circuit including a diode 27 and a smoothing capacitor 28, and is used as a primary control power source or the like as a direct current of 20V, for example.

The switching power supply circuit of FIG. 4 has a bias winding PB-1 in the circuit of FIG. 1 by making the bias winding PB the same number of turns as the primary winding P2, and the primary winding P2 is also a bias winding. It can be said that the bias winding PB-2 is regarded as a line, and the bias windings PB-1 and PB-2 are connected in parallel. That is, it can be said that the primary winding P2 is also used as the bias winding. In FIG. 3, two bias windings PB-1 and PB-2 are connected in parallel inside the transformer, but in FIG. 4, two bias windings PB-1 and PB-2 are connected to each other. Are connected in parallel outside the transformer.

FIG. 5 shows a winding structure of the transformer 10 according to the second embodiment of the present invention. The figure shows a cross section of one side of the transformer. As the winding 14, a primary winding P1, a secondary winding S1, a bias winding PB-1, a secondary winding S2, and a bias winding PB-2 are wound around the bobbin 16 in this order. The secondary winding S2 is sandwiched between two bias windings PB-1 and PB-2.

In FIG. 5, the secondary winding is composed of two windings having the same number of turns, and the secondary winding and the bias winding are alternately arranged. By making the secondary winding into one winding and sandwiching the secondary winding between the two bias windings, the degree of coupling can be increased. However, as shown in FIG. By configuring with two windings having the same number of turns and sandwiching each other, the degree of coupling between the secondary winding and the bias winding can be further increased. Further, the degree of coupling can be further increased by using three or more bias windings or secondary windings and sandwiching each other.

According to this embodiment, the bias winding PB is a bias winding PB-1 having the same number of turns as the second primary winding P2, and the primary winding P2 is also regarded as a bias winding. By connecting the two bias windings PB-1 and PB-2 in parallel and winding the secondary winding so as to be sandwiched between the two bias windings, the secondary winding and the bias winding Magnetic adhesion with the wire can be improved and the degree of coupling can be increased. Thereby, the sensitivity of feedback control can be increased and the output voltage can be stabilized.

In addition, since the conventional primary winding P2 is used as a bias winding, it is not necessary to add a bias winding, so that the transformer is not enlarged and an increase in cost can be prevented.

6 and 7 show the characteristics of the switching power supply device in comparison with the switching power supply device before improvement described in FIGS. 1 and 2 and the switching power supply device of this embodiment (after improvement). FIG. 6 shows characteristics when a current of 50 mA is passed through a 20V load, and FIG. 7 shows characteristics when the 20V load is open. In both figures, the horizontal axis represents the load current and the vertical axis represents the output voltage. In particular, as shown in FIG. 6, when a load current is passed, the change in the output voltage of 12V is reduced and the output voltage of 20V is also stabilized.

According to the present invention, it is possible to stabilize the output voltage of the switching power supply device without adding a transformer winding, and to achieve downsizing and cost reduction of the transformer and the power supply device. The switching power supply device of the present invention can be used in general for power supplies in addition to power supplies for control of air conditioners, refrigerators, washing machines and the like.

10 Transformer 12 Core 14 Winding 16 Bobbin 17 Terminal 20 Switching IC
22 Smoothing capacitor 23 Diode 24 Smoothing capacitor 25 Diode 26 Smoothing capacitor 27 Diode 28 Smoothing capacitor P1 Primary winding P2 Second primary winding S1, S2 Secondary winding PB Bias winding PB-1, PB-2 Bias Winding

Claims

Comprising a transformer having a primary winding, a secondary winding and a bias winding;
In a switching power supply apparatus that outputs a stabilized voltage from the secondary winding by connecting a power source to the switching element via the primary winding and controlling the switching element by an output of the bias winding ,
The bias winding of the transformer is composed of a plurality of bias windings having the same number of turns, and the plurality of bias windings are connected in parallel,
A switching power supply device in which a secondary winding of the transformer is wound so as to be sandwiched between the plurality of bias windings.
The switching power supply device according to claim 1,
The secondary winding of the transformer is composed of a plurality of secondary windings having the same number of turns, and the plurality of secondary windings are connected in parallel.
A switching power supply device in which a plurality of secondary windings and a plurality of bias windings of the transformer are alternately wound.
The switching power supply device according to claim 1,
The bias winding of the transformer is composed of two bias windings having the same number of turns, and the two bias windings are connected in parallel,
A switching power supply device in which a secondary winding of the transformer is wound so as to be sandwiched between the two bias windings.
In the switching power supply device according to claim 3,
The secondary winding of the transformer is composed of two secondary windings having the same number of turns, and the two secondary windings are connected in parallel.
A switching power supply device in which two secondary windings and two bias windings of the transformer are alternately wound.
The switching power supply device according to any one of claims 1 to 4,
A switching power supply device that outputs a direct current by connecting a rectifier circuit to the bias winding of the transformer.
In the switching power supply device according to claim 5,
A switching power supply apparatus using the output of the rectifier circuit as a power supply for a control circuit.
The switching power supply device according to any one of claims 1 to 6,
A switching power supply device that outputs a direct current by connecting a rectifier circuit to the secondary winding of the transformer.
Comprising a transformer having a primary winding, a secondary winding and a bias winding;
In a switching power supply apparatus that outputs a stabilized voltage from the secondary winding by connecting a power source to the switching element via the primary winding and controlling the switching element by an output of the bias winding ,
The transformer further includes the bias winding having the same number of turns as the second primary winding,
Connecting the bias winding and the second primary winding in parallel;
A switching power supply device in which a secondary winding of the transformer is wound so as to be sandwiched between the bias winding and the second primary winding.
The switching power supply device according to claim 8,
The secondary winding of the transformer is composed of two secondary windings having the same number of turns, and the two secondary windings are connected in parallel.
A switching power supply device in which a secondary winding of the transformer, the bias winding, and the second primary winding are alternately wound.
In the switching power supply device according to claim 8 or 9,
A switching power supply device in which a rectifier circuit is connected to the bias winding of the transformer to serve as a power supply for the control circuit.
The switching power supply device according to any one of claims 8 to 10,
A switching power supply device that outputs a direct current by connecting a rectifier circuit to the secondary winding of the transformer.