JP2830195B2 - Multi-output transformer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-output transformer used in various industrial and consumer electronic devices.

2. Description of the Related Art In recent years, as multi-output transformers have become increasingly sophisticated and miniaturized for various types of electronic devices for industrial use and consumer use, there is a strong demand for smaller output transformers having various output voltages.

 Hereinafter, a conventional multi-output transformer will be described.

FIG. 10 is a simplified configuration diagram of a conventional multi-output transformer focusing only on the magnetic core and the winding so that the winding structure becomes clear. In FIG. 10, 1 is a magnetic core,
This is an EE type magnetic core commonly used. Reference numeral 2 denotes a main magnetic leg of the magnetic core 1, and reference numerals 3 and 4 denote first and second auxiliary magnetic legs.
The sum of the cross-sectional areas of the sub-magnetic legs 3 and 4 is substantially equal to the cross-sectional area of the main magnetic leg 2. Reference numerals 5 and 6 denote input winding terminals. In the description of the present drawing, the windings are referred to as input windings 5-6. Reference numerals 7 and 8 denote first output winding terminals, and reference numerals 84 and 85 denote second output winding terminals. The dots in the figure represent the polarity of each winding, are shown near one of the winding terminals, and the winding terminal with the dot is called the winding start terminal for convenience. The broken line in the magnetic core 1 indicates the path of the magnetic flux generated in the magnetic core 1, and the arrow in the invention indicates the direction of the magnetic flux generated when a current flows from the winding start terminal of the winding.

In the case of the multi-output transformer shown in this figure, as can be seen from the figure, the input winding 5-6 has two turns, and the first output winding 7-8.
Is a two-turn winding, and the second output windings 84-85 are one-turn windings. When an input voltage is applied to the input windings 5-6, a voltage according to the turn ratio, that is, a first output winding 7-8 is applied to each output winding.
, A voltage equal to the input voltage is generated, and the second output windings 84-85 generate and output half the input voltage. The desired output voltage is obtained by adjusting the number of turns of each winding, that is, the turn ratio.

Next, a circuit configuration diagram of a switching power supply device is shown in FIG. 11 as an example of use of a conventional multi-output transformer, and its operation will be described. In FIG. 11, reference numeral 86 denotes a DC input voltage source,
The voltage is defined as an input voltage Ei. The DC input voltage source 86 is usually obtained by rectifying and smoothing a commercial AC power supply or using a battery, and its voltage is not stable. A switching element 87 converts the input voltage Ei into a high-frequency AC voltage by repeatedly turning on and off at a predetermined time ratio. A multi-output transformer 88 has an input winding 89, a first output winding 90, and a second output winding 91. Reference numerals 92 and 93 denote diodes for connecting high-frequency AC voltages generated to the first and second output windings 90 and 91, respectively. Reference numerals 94 and 95 denote capacitors. Diodes 92 and 93 smooth the rectified voltage and output the DC output voltages E ₀₁ and E ₀₂ to the loads 96 and 97, respectively. 98 is a control circuit detects a DC output voltage E _01, has a function of adjusting the duty ratio of the switching element 87 in order to stabilize the DC output voltage E _01.

When the switching element 87 is on, the input voltage Ei is applied to the input winding 89 of the multi-output transformer 88, and the output windings 90, 9
1 generates a voltage according to the turns ratio. However, since the generated voltage is generated in a direction in which the diodes 92 and 93 are reverse-biased, no current flows through the output windings 90 and 91 and the input winding 8
Current flows only through 9 to excite the multi-output transformer 88. When the switching element 87 is turned off, each winding voltage of the multi-output transformer 88 is inverted, and a flyback voltage is generated. Since the generated flyback voltage is generated in a direction to bias the diodes 92 and 93, a current flows through each output winding 90 and 91, and when the switching element 87 is on, the excitation energy stored in the multi-output transformer 88 is Released. Flyback voltage generated in the first output winding 90 is output to the load 96 as a DC output voltage E ₀₁ is rectified and smoothed by the diode 92 and the capacitor 94. Similarly, the flyback voltage generated at the second output winding 91 is a diode 93 and a capacitor 95.
And output to the load 97 as the DC output voltage _E02 .

Such a switching power supply system that obtains a DC output voltage by rectifying and smoothing a flyback voltage generated in an output winding is called a flyback converter. The number of turns of the input winding 89 is N89 and the number of turns of the first output winding 90 is N90.
The number of turns of the output winding 91 is N91, the period when the switching element 87 is on is Ton, and the period when it is off is Toff
And the forward voltage drops of diodes 92 and 93 are VD9
If 2, VD93, the following relational expression holds.

_{E 01 = (N90 / N89)} · (Ton / Toff) · Ei-VD92 E 02 = (N91 / N89) · (Ton / Toff) · Ei-VD93 control circuit 98 a DC output detects a DC output voltage E ₀₁ Voltage E
_{If 01} is going to be higher than the predetermined voltage, the duty D will be increased, and if DC output voltage _E01 is going to be lower than the predetermined voltage, the duty D will be reduced. The duty ratio D is the ratio of the ON period to the switching cycle of the switching element 87, and D = Ton / (Ton + Toff). That is, the DC output voltage is controlled by the control function of the control circuit 98.
_E01 is stabilized irrespective of the input / output conditions such as the fluctuation of the input voltage Ei and the fluctuation of the load 96. On the other hand, DC output voltage
_E02 is determined by the turns ratio of the multi-output transformer 88 and is relatively stabilized, as seen from the above-mentioned relational expression, with some fluctuation due to input / output conditions. If Nobere Conversely, the DC output voltage E ₀₂ is that setting the winding ratio of the multi-output transformer 88, stability depends largely on the degree of coupling between the first output winding 90.

Generally, when designing a transformer, it is a minimum requirement that the operating magnetic flux density ΔB must be smaller than the saturation magnetic flux density Bs, and also to reduce iron loss of the magnetic core represented by hysteresis loss. The operating magnetic flux density ΔB cannot be increased. The effective area of the magnetic core of the multi-output transformer 88 is A
And the operating magnetic flux density is ΔB, the following relational expression holds.

ΔB∝Ei · Ton / (N89 · A) That is, if the ON period Ton of the switching element 87 is reduced, the number of turns can be reduced and the effective area of the magnetic core can be reduced. When the switching frequency of the switching power supply is increased, the size of the transformer can be reduced, which leads to downsizing of the switching power supply using the transformer as a main component.

However, the above-described conventional multi-output transformer has a limitation of a minimum number of turns of one turn, and cannot be reduced even if it is desired to reduce the number of turns by increasing the operating frequency or improving the performance of the magnetic core material. There was a problem. Also, the tenth
In the case of the conventional multi-output transformer shown in the figure, for example, the input voltage is 8 V
If you want output voltages such as 8V and 6V for
When the number of turns of the output windings 84 to 85 is one turn, the output voltage is insufficient, and when the number is two turns, the output voltage becomes excessive. If the structure shown in FIG. 12A is used to make 1.5 turns, the following problems will occur.

FIG. 12 (b) illustrates the problem of FIG. 12 (a). In particular, only the second output winding 99-100 is used for one turn and 0.5 turn.
It is divided into turns. Although there is no problem with the one-turn portion, the 0.5-turn portion generates a magnetic flux φ1 that passes only through the sub-magnetic legs 3 and 4 without passing through the main magnetic leg 2 as is apparent from the drawing. As a result, not only does a magnetic flux imbalance occur in the magnetic core 1 but also the second output winding 99-100 has an accurate
It does not generate a voltage for 1.5 turns and has a magnetic flux in a different path from the input winding and other output windings, and this magnetic flux acts in the same way as the leakage magnetic flux, and therefore the inductance generated by this magnetic flux also decreases This results in leakage inductance.

After all, if you want 8V and 6V output voltage for 8V input voltage, you need to apply 4 turns for the input winding and 4 turns and 3 turns for the output winding. Would.

Such a problem has been a serious problem that hinders miniaturization of a switching power supply device that is being studied for downsizing by increasing the switching frequency. For example, in the case of switching power supply shown in FIG. 11, E ₀₁
0.8V but 5V, E ₀₂ is 24V, the use of the Schottky barrier diode in the diode 92 VD92 is 0.5V, VD93 by using the conventional fast recovery diode to diode 93
Then, the turns ratio of each output winding is N90: N91 = 5.5: 24.8 ≒ 2: 9. Therefore, the first output winding 90 has a limit of 2 turns, and the second output winding 91 has a limit of 9 turns. If the number of turns is 1 turn and 4.5 turns by the method shown in FIG. , A magnetic flux imbalance occurs, or the second output winding 91
Causes leakage inductance. The leakage inductance not only deteriorates the degree of coupling with other windings and deteriorates the stability of the DC output voltage _E02 , but also generates a surge voltage during the transition period of the switching operation of the switching element 87, that is, at the time of turn-on / turn-off. This leads to increased stress and destruction of each component and also causes noise.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a multi-output transformer that realizes a good coupling degree and a non-natural number of turns without causing magnetic flux imbalance.

Means for Solving the Problems In order to achieve this object, a multi-output transformer of the present invention uses a magnetic core composed of two or more sub-magnetic legs having the same magnetic resistance as the main magnetic leg, and has an input winding on the main magnetic leg. And a first output winding, and windings each having the same number of turns on the auxiliary magnetic leg,
It is connected in parallel to form a second output winding.

Further, the input winding and the first output winding may be wound with windings each having the same number of turns on each sub-magnetic leg, and these may be connected in series. Alternatively, the winding may be wound.

Operation With the above-described winding structure, the multi-output transformer of the present invention can reduce the voltage generated in the second output winding to a voltage smaller than the voltage of one turn of the first output winding. Obtainable. Because there are N secondary legs,
N ₃ turns by winding each sub magnetic legs and are wound. When the number of turns of the input winding is n ₁ , the number of turns of the first output winding is n ₂ turns, and when an AC voltage of e ₁ is applied to the input winding, the voltage generated in the first output winding is e. _{Assume 2} . Assuming that the magnetic flux generated by the input winding is φ, the magnetic flux that changes in the first output winding is also φ, so the voltage generated is On the other hand, since the magnetic flux flows in each sub-magnetic leg by 1 / N, the voltage e ₃ generated in each winding having the number of turns n ₃ of each sub-magnetic leg is: Since the windings of each sub leg having the number of turns n ₃ are connected in parallel with the same polarity, the voltage of e ₃ is the voltage of the second output winding.

Here, if the number of turns n ₂ = 1 turn of the first output winding, from (5) Becomes That is, a voltage of n ₃ / N of the voltage e ₂ obtained in one minimum turn of the first output winding is obtained in the second output winding. In particular, the number of turns n ₃ =
At the time of one turn, the minimum voltage is obtained, and the number N of the auxiliary magnetic legs is obtained.
The smaller the voltage, the smaller the voltage.

Further, since the windings having the same number of turns are wound around each sub-magnetic leg, all the generated magnetic fluxes are equal, and no imbalance of the magnetic fluxes occurs.

Further, the input winding and the first output winding are formed by winding windings each having the same number of turns on each sub-magnetic leg, and connecting these in series, and winding over all the sub-magnetic legs. The operation is the same for the case where the is wound.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a simplified configuration diagram of the multi-output transformer according to the first embodiment of the present invention, focusing only on the magnetic core and the winding so that the winding structure thereof becomes clear. In FIG. 1, reference numeral 1 denotes a magnetic core, which is a commonly used EE type magnetic core. 2 is a main magnetic leg of the magnetic core 1. Reference numerals 3 and 4 denote first and second auxiliary magnetic legs, respectively, which have the same magnetoresistance as viewed from the main magnetic leg 2. Reference numerals 5 to 16 denote winding terminals. In the description of the present embodiment, the windings are referred to as windings 5-6. Reference numeral 5-6 denotes an input winding, which is wound around the main magnetic leg 2 for two turns. Reference numeral 7-8 denotes a first output winding.
2 turns. Reference numeral 9-10 denotes a winding wound one turn around the main magnetic leg 2, and reference numerals 11-12 and 13-14 denote the first winding.
Are respectively wound around the auxiliary magnetic leg 3 and the second auxiliary magnetic leg 4 by one turn. The dots in the figure represent the polarity of each winding, are shown near one of the winding terminals, and the winding terminal with the dot is called the winding start terminal for convenience. The winding terminals 5, 7, 9, 11, 13 are winding start terminals of the respective windings. The winding terminals 10, 11, 13 are connected to form a winding terminal 15 having the winding terminal 9 as a winding start terminal. The winding terminals 12 and 14 are connected, and this connection point is further used as a winding terminal 16. A winding 15-16 is used as a second output winding. The broken line in the magnetic core 1 indicates the path of the magnetic flux generated in the magnetic core 1, and the arrow in the broken line indicates the direction of the magnetic flux generated when a current flows from the winding start terminal of the winding.

In the multi-output transformer configured as described above, the windings are wound around both the sub-magnetic legs 3 and 4, and the magnetic flux generated in the main magnetic leg 2 when a voltage is applied to the input winding 5-6. Are pointed out as a problem in the above-mentioned FIG. 12 because the magnetic resistance of each of the sub-magnetic legs 3, 4 is equal and the parallel connection is made in the direction passing through the respective sub-magnetic legs 3, 4 and the magnetic resistance of each sub-magnetic leg 3, 4 is equal. Such a magnetic flux imbalance does not occur. Moreover, since the magnetic flux passing through each of the sub-magnetic legs 3 and 4 is half of the magnetic flux generated by the main magnetic leg 2, n ₃ =
1, N = 2, and the windings 11-12 and 13-14 correspond to 0.5 turns for one turn of the main magnetic leg. That is, the second output winding 1
5-16 is 1.5 turns because it is in series with one turn of the winding 9-10 wound around the main magnetic leg 2. In this case, each sub-magnetic leg 3, 4
If the reluctance of the main magnetic leg 2 is less than twice the reluctance of the main magnetic leg 2, the generated magnetic flux passes through the sub magnetic legs 3, 4 without leaking.
The 0.5 turns of the windings 11-12 and 13-14 have relatively good coupling with other windings wound on the main magnetic leg 2.

Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.

FIG. 2A is an external view of a magnetic core of a multi-output transformer used in the second embodiment of the present invention. FIG. 2 (b) shows the second
FIG. 3 is a configuration diagram showing only a magnetic core cross section and a winding so that a state of winding on a magnetic core in FIG. In FIG. 2 (b), the magnetic core 17 is composed of three sub-magnetic legs 19, 20, 21 each having the same magnetic resistance with respect to the main magnetic leg 18. 22 to 29 are winding terminals, and windings 22 to 23 are connected to the main magnetic leg 18 by one turn.
The windings 24-25, 26-27 and 28-29 are wound around the sub-magnetic legs 19, 20, 21 respectively by two turns. In this embodiment, similarly to the above-described embodiment, each of the windings 24-25, 26-27, 28-29 is arranged such that the magnetic flux generated in the main magnetic leg 18 passes through the sub magnetic legs 19 to 21.
And the winding terminals 22, 24, 26, and 28 are used as winding start terminals. Further, the winding terminals 24, 26, 28 are connected, the connection point is a winding terminal 30, the winding terminals 25, 27, 29 are connected, and the connection point is a winding terminal 31.

In the multi-output transformer configured as described above, a winding is wound around each sub-magnetic leg, and when a voltage is applied to the windings 22 to 23, the magnetic flux generated in the main magnetic leg 18 is generated by each sub-magnetic leg. The first connection point described above in that the magnetic poles are connected in parallel in the direction passing through the legs 19 to 21 and the magnetic resistances of the sub-magnetic legs 19 to 21 are equal.
This embodiment is the same as the embodiment shown in FIG.
It is a book, and the winding of each of the auxiliary magnetic legs 19 to 21 is two turns. Therefore, the magnetic flux generated in the main magnetic leg 18 is divided into three equal parts by the sub magnetic legs 19 to 21, and one turn of the winding of the sub magnetic legs 19 to 21 corresponds to one third turn of the winding of the main magnetic leg 18. Each sub magnetic leg 19-2
The winding 30-31 is the main magnetic leg 1
This is equivalent to 2/3 turns of 8 windings. That is, n ₃ = 2 and N = 3 in equation (7). Also in the case of this embodiment, it is desirable that the magnetic resistance of the sub magnetic legs 19 to 21 be three times or less the magnetic resistance of the main magnetic leg 18 as in the embodiment of FIG.

As can be seen from the first and second embodiments, each of the N sub-magnetic legs having the same magnetic resistance with respect to the main magnetic leg is wound around each of the n- _three- turn windings, and the winding is generated on the main magnetic leg. If the magnetic flux is connected in parallel with the polarity aligned in the direction passing through each sub leg, the number of turns is n ₃ per turn to the main leg.
This is equivalent to / N turns.

Next, a third embodiment of the present invention will be described with reference to the drawings.

FIG. 3 is a simplified configuration diagram of the multi-output transformer according to the third embodiment of the present invention, focusing only on the magnetic core and the windings so that the winding structure becomes clear. In FIG. 3, reference numeral 1 denotes a magnetic core, which is the same as in the first embodiment. The magnetic resistances of the sub magnetic legs 3 and 4 are assumed to be equal. 32 to 56 are winding terminals, and windings 32-33, 34
−35,36−37,38−39,40−41,42−43 turns one turn per sub leg 4, windings 44−45,46−47,48−49,50−51,52−53, 54
-55 is wound one turn at a time on the auxiliary magnetic leg 3 and its polarity is determined so that the magnetic flux generated by each of the auxiliary magnetic legs 3 and 4 is in the same direction on the main magnetic leg 2. , 34,36,38,40,42,44,4
6,48,50,52,54. In addition, winding terminals 33 and 44, 34 and 4
5, 35 and 46, 37 and 48, 43 and 49, 39 and 50, 41 and 52, 42 and 53
And 54, 43 and 55, the connection point between the winding terminals 43 and 55 is the winding terminal 56, the winding 32-47 is the input winding, and the winding 36-51 is the first winding.
And the windings 40-56 as the second output winding.

The multi-output transformer configured as described above has sub-poles 3,
4 is wound so that the magnetic flux generated in the main magnetic leg 2 is equal and doubled in the main magnetic leg 2, so that one turn of the sub magnetic legs 3, 4 is
Of 0.5 turns. Accordingly, the input windings 32-47 and the first output windings 36-51 have four turns connected to 0.5 poles, each corresponding to two turns. Also, the second output winding 40-56 is connected in series with one having 0.5 turns connected to two poles and one having 0.5 turns connected in parallel with two polarities. Equivalent to a turn.

In this embodiment, compared to the first embodiment, by arranging the magnetic poles to be wound, the distance between the windings becomes shorter, and the degree of coupling becomes more dense than in the first embodiment. The magnetic core 1 of this embodiment may be the same as that of the first embodiment, but the magnetic resistance of the main magnetic leg is adjusted so that the magnetic flux generated by each sub-magnetic leg passes through the main magnetic leg without leakage. It is desirable to keep the magnetic resistance of the leg below 1/2.

Further, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 4 shows the winding terminal 3 in FIG.
Same for 2,36,47,51,40-56, changed for 33-39,44-50, 33 and 34, 35 and 44, 45 and 46, 37 and 38, 39 and
In FIG. 3, one turn (ie, 0.5 turn) of each sub-magnetic leg is connected to the pole, respectively, while two turns (ie, 0.5 turn) are connected to each of the sub-magnetic legs 3, 4 in FIG. (1 turn) and then connected in series to the pole. Therefore, although the characteristics of the multi-output transformer according to this embodiment are equivalent to those of the third embodiment, the winding method is easy as can be seen by comparing the drawings.

As means for facilitating the winding method for the third embodiment, there is a means for changing the shape of the magnetic core in addition to the fourth embodiment. Hereinafter, a fifth embodiment of the present invention will be described with reference to FIG.

In FIG. 5, reference numeral 57 denotes an eye-shaped magnetic core having a first sub-magnetic leg 58 and a second sub-magnetic leg 59 having the same magnetic resistance, and a first main magnetic leg 60 and a second sub-magnetic leg 60 also having the same magnetic resistance. Of the main magnetic leg 61. 32, 36, 40, 42, 43, 47, 51, 53 to 56 are winding terminals, and windings 32 to 47 are input windings and are two-turn windings extending over two sub-magnetic legs 58, 59. I have. The winding 36-51 is a first output winding and is wound for two turns over the two sub-magnetic legs 58 and 59. The windings 40-53 are wound one turn over the two auxiliary magnetic legs 58, 59, and the windings 42-43 and 54-55 are wound one turn on each of the auxiliary magnetic legs 58, 59. It is lined. The polarity of each winding is determined so that the direction of the magnetic flux generated at each sub-magnetic leg 58, 59 is aligned, and the winding terminals 32, 36, 40, 42, 54 are used as winding start terminals,
Connect the winding terminals 42, 53, 54, connect the winding terminals 43 and 55,
The connection point is referred to as a winding terminal 56. The windings 40-43 and 54-55 are connected in parallel with the
The second output winding 40-56 is connected in series with the additional pole 53 and an additional pole.

In this embodiment, two sub poles 58 and 59 of the third embodiment are
The main magnetic legs 60 and 61 are arranged next to each other, and are arranged outside the main magnetic legs 60 and 61. The windings are wound around the two auxiliary magnetic legs 58 and 59 collectively. Although the number of main magnetic legs 60 and 61 is increased to two, this embodiment is equivalent to the third embodiment in terms of a magnetic circuit. Therefore, the numbers of the winding terminals are also given corresponding to those of FIG. With such a configuration, the distance between the input winding and the output winding is short, and the coupling degree is further improved as compared with the third embodiment.

According to the fifth embodiment, although the winding is easy,
There are windings extending over the two sub-magnetic poles 58 and 59 and windings on the respective sub-magnetic legs 58 and 59, so that the shape of the bobbin is complicated. If the winding is applied only to each of the sub-magnetic legs 58 and 59, the bobbin shape can be simplified by using two bobbins.

An example is shown in FIG. 6 as a sixth embodiment. In the sixth embodiment, the winding method of the fourth embodiment is realized by using the magnetic core of the fifth embodiment. This embodiment is equivalent to the fourth embodiment in terms of a magnetic circuit. Is the same as the fifth embodiment is equivalent to the third embodiment on a magnetic circuit. Accordingly, the numbers of the winding terminals are also given in correspondence with those of FIGS.

FIG. 7 is a structural diagram of a multi-output transformer according to a seventh embodiment of the present invention. This is one in which the main magnetic pole of the magnetic core in the fifth embodiment is one, and 62 is a main magnetic leg. The auxiliary magnetic legs and the windings are the same as those in FIG. In the seventh embodiment, all the magnetic flux generated by the input winding flows into one main magnetic leg 62. At this time, as shown by the broken line in FIG.
The portion generated from the sub-magnetic leg 58 passes through the longer magnetic circuit than the portion 59. Therefore, the voltage may be different between the windings 54-55 and the windings 42-43 wound around the sub-magnetic legs 58, 59, but if a magnetic core having a sufficiently large magnetic permeability is used. Since the difference becomes very small, there is almost no problem in practical use.

In the seventh embodiment, the structure of the magnetic core is simple.
Since the windings are wound around the auxiliary magnetic legs 58 and 59 in the same manner as in the embodiment, the coupling degree is high.

In addition to the embodiments of the multi-output transformer according to the present invention described above, depending on the specifications such as the number of output windings and input / output conditions of the multi-output transformer, the method of dividing the magnetic core and the magnetic legs or the method of connecting the winding terminals may be used. Numerous variations and applications are possible. For example, in the second embodiment, two turns are wound around each of the three sub-magnetic legs and connected in parallel to create 2/3 turns. However, as an eighth embodiment, a winding method as shown in FIG. 2/3 turns. 8, 17 to 23 are the same as in FIG. 2 (b), and 64 to 69 are winding terminals. The difference from FIG. And windings 66-67 are wound over the auxiliary magnetic legs 20 and 21, windings 68-69 are wound over the auxiliary magnetic legs 21 and 19, and the winding terminals These are connected as 64, 66, 68 as the winding start terminals, and the connection point is set to 30, and the winding terminals 65, 67,
This is the point that 69 is connected and the connection point is 31. Winding
It goes without saying that 30-31 turns into 2/3 turns.

Further, as a ninth embodiment, as shown in FIG. 9 (a), in the case of a magnetic core having four sub magnetic legs having the same magnetic resistance,
In order to make 0.5 turns, that is, 2/4 turns, two turns are wound around each sub-magnetic leg, and the parallel connection is made with the same polarity.
By assuming that the two sub magnetic legs are divided into two sub magnetic legs, it can be realized by a winding method as shown in FIG. 9 (b). In FIG. 9 (b), the magnetic core 70 is composed of four sub-magnetic legs 72, 73, 74, 75 each having the same magnetic resistance with respect to the main magnetic leg 71. 76 to 83 are winding terminals;
-77 is one turn to the main leg 71, and windings 78-79 are the sub leg 72 and
One turn across 73, windings 80-81 are sub-magnetic legs 74 and 75
And the magnetic flux generated in the main magnetic leg 71 passes through the sub magnetic legs 72 to 74 in the direction in which the windings 78-79, 80-81
And the winding terminals 76, 78, and 80 are used as winding start terminals.
Furthermore, wire terminals 78 and 80 are connected, and the connection point starts winding terminal 8.
2, the winding terminals 79 and 81 are connected, and the connection point is set to 83.
As described above, the windings 82-83 have 0.5 turns.

As described above, according to the present invention, the main magnetic leg and the magnetic resistance equal to each other are equal to two.
Since a magnetic core composed of at least two sub-magnetic legs is used, and windings having the same number of turns are wound around the sub-magnetic legs and connected in parallel to form a second output winding, an input winding or a first output winding is used. Can be taken out, and the voltage of each output winding in the multi-output transformer can be freely adjusted with a small number of turns. The miniaturization of a multi-output transformer using a small number of turns can be realized. Therefore, the effect of miniaturization is great when the switching power supply is used for a multi-output type, which has been miniaturized by increasing the switching frequency corresponding to the operating frequency of the multi-output transformer.

[Brief description of the drawings]

FIG. 1 is a winding configuration diagram of a multi-output transformer according to a first embodiment of the present invention. FIG. 2 (a) is an external view of a magnetic core of the multi-output transformer according to a second embodiment of the present invention. (B) is a winding configuration diagram of a multi-output transformer in a second embodiment of the present invention, FIG. 3 is a winding configuration diagram of a multi-output transformer in a third embodiment of the present invention, and FIG. And FIG. 5 is a winding configuration diagram of a multi-output transformer according to a fifth embodiment of the present invention, and FIG. 6 is a sixth embodiment of the present invention. , FIG. 7 is a winding configuration diagram of the multi-output transformer according to the seventh embodiment of the present invention, and FIG. 8 is a winding configuration diagram of the multi-output transformer according to the eighth embodiment of the present invention. FIG. 9A is an external view of a magnetic core of a multi-output transformer according to a ninth embodiment of the present invention. (B) is a winding configuration diagram of a multi-output transformer in a ninth embodiment of the present invention, FIG. 10 is a winding configuration diagram of a conventional multi-output transformer, and FIG. 11 is a switching power supply in a usage example of a multi-output transformer. Circuit diagram of the device,
FIG. 12 (a) is a winding configuration diagram of a conventional multi-output transformer, and FIG.
FIG. 12 (b) is a winding configuration diagram for explaining the problem of the multi-output transformer of FIG. 12 (a). 1 ... magnetic core 2 ... main magnetic leg of magnetic core 1 3 ... first sub magnetic leg of magnetic core 1 4 ... second sub magnetic leg of magnetic core 1, 5 to 16 ...
Winding terminal, 17 ... magnetic core, 18 ... Main magnetic leg of magnetic core 17, 19 ...
A first sub magnetic leg of the magnetic core 17, 20 a second sub magnetic leg of the magnetic core 17,
21... Third auxiliary leg of the magnetic core 17, 22 to 56.
... magnetic core, 58 ... first sub magnetic leg of magnetic core 57, 59 ... magnetic core 57
The second sub-legs, 60 ... The first main leg of the magnetic core 57, 61 ...
The second main leg of the magnetic core 57, 62... The main magnetic leg, 64-69... The winding terminal, 70... The magnetic core 71, the main magnetic leg of the magnetic core 70, 72.
The first sub-magnetic legs of 70, 73... The second sub-magnetic legs of the magnetic core 70, 74.
... Third sub-magnetic leg of the magnetic core 70, 75... Fourth sub-magnetic leg of the magnetic core 70, 76-83.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tatsuo Maeoka 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-63-266807 (JP, A) JP-A-48 -93920 (JP, A) Jikken 57-22420 (JP, Y2) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01F 27/28 H01F 27/24 H01F 30/00

Claims (6)

(57) [Claims] 1. A magnetic core comprising one main magnetic leg and two or more sub magnetic legs having the same magnetic resistance. An input winding is wound around the main magnetic leg, and a first output winding is formed on the main magnetic leg. The secondary magnetic legs are wound with windings having the same number of turns, and are connected in parallel to form a second winding.
Multi-output transformer with output winding of. 2. A magnetic core comprising one main magnetic leg and two or more sub magnetic legs having the same reluctance, and windings of the same number of turns are wound around each of the sub magnetic legs and connected in series. With the number of input turns, each sub-magnetic leg is further wound with the same number of turns and connected in series to form a first output winding, and each sub-magnetic leg is wound with the same number of turns. A multi-output transformer connected in parallel to serve as a second output winding. 3. A magnetic core comprising one main magnetic leg and two or more sub magnetic legs having the same reluctance, and an input winding and a first output winding are provided across all the sub magnetic legs. A multi-output transformer which is wound and wound on each of the sub-magnetic legs with an equal number of turns and connected in parallel to form a second output winding. 4. A magnetic core comprising two main magnetic legs and two or more sub magnetic legs having the same reluctance, and an input winding and a first output winding are provided over all of the sub magnetic legs. A multi-output transformer which is wound and wound with windings each having the same number of turns on each sub-magnetic leg and connected in parallel to form a second output winding. 5. The multi-output transformer according to claim 4, wherein the magnetic core is shaped like an eye, two inner magnetic legs are used as auxiliary magnetic legs, and two outer magnetic legs are used as main magnetic legs. 6. A magnetic core comprising one main magnetic leg and three or more sub magnetic legs having the same reluctance. An input winding is wound around the main magnetic leg and a first output winding is provided. A multi-output transformer in which two or more sets of windings extending over two or more sub-magnetic legs are wound on the sub-magnetic leg and connected in parallel to form a second output winding.