JPH02178908A - Transformer - Google Patents

Abstract

PURPOSE:To lessen the voltage regulation with the desired output voltage by dividing a core into plural core parts of specified cross section, and winding a coil individually around each core part and connecting the windings in parallel. CONSTITUTION:A core 11 is divided into plural core parts AR2 and AR3 of specified cross-sectional areas, and a coil is wound around the core parts AR2 and AR3, and the windings 16 and 17 are connected in parallel. By winding coils on both of the two foot parts AR2 and AR3 and connecting them in parallel, even if the output current becomes great, the magnetic reluctances of the foot parts AR2 and AR3 are kept at an equal value. And the magnetic fluxes which respectively pass the foot parts AR2 and AR3 are kept at a fixed value so as to prevent the fluctuation of the output voltage. Hereby, even if it is difficult to set the winding ratio to a desired integer ratio, the desired output voltage can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a transformer, and is suitable for application to, for example, a switching transformer in a switching regulator circuit.

B Summary of the Invention The present invention provides a transformer in which the core is divided into a plurality of core parts each having a predetermined cross-sectional area and wound, and the windings are connected in parallel so that the turns ratio is selected to be other than an integer ratio. ,
A desired output voltage can be obtained with a small voltage fluctuation rate.

C. Prior Art Conventionally, in a switching regulator circuit, the turns ratio of a switching transformer is selected to be a predetermined integer ratio, thereby obtaining a desired output voltage determined by the ratio relative to the input voltage.

D Problems to be Solved by the Invention By the way, in a switching regulator circuit, if the driving frequency is increased, the efficiency of the switching regulator circuit can be improved accordingly.

Furthermore, by doing this, it is possible to use a switching transformer with low inductance, and it is thought that the switching transformer can be made smaller accordingly, and the entire switching regulator circuit can be made smaller.

However, in a small switching transformer with low inductance, the number of turns of the primary winding is reduced accordingly.

Therefore, in order to obtain a desired output voltage, it may be necessary to select a turns ratio other than an integer ratio, and in this case, there is a problem that it becomes difficult to obtain the required output voltage.

One possible method for solving this problem is to set the turns ratio high to obtain an output voltage higher than the desired voltage, and then correct the output voltage using a series regulator circuit.

That is, as shown in FIG. 12, in the drive circuit 1,
A switching transformer 2 having a primary winding of 10 turns is driven with a driving voltage of 50 (V).

The secondary winding of the switching transformer 2 has three turns as a whole, and an intermediate tap is provided at the second turn.

Therefore, since an output voltage of 5 [■] can be obtained per turn of the winding, the output voltage of 5 [ (2)] and an output voltage of 15 (V) can be obtained.

Thus, by correcting the output voltage of 15 [■] to 12 (V) by the series regulator circuit 7, output voltages of 5 [■] and 12 (V) can be obtained.

However, in this way, the series regulator circuit 7
When correcting the output voltage with the series regulator circuit 7, the efficiency of the entire power supply circuit decreases by the amount corrected by the series regulator circuit 7, and the configuration of the power supply circuit becomes larger due to the series regulator circuit 7, and the drive frequency is increased. It becomes meaningless to make the switching regulator circuit smaller and more efficient.

The present invention has been made in consideration of the above points, and aims to propose a transformer that can obtain a desired output voltage even when it is difficult to select the turns ratio to a desired integer ratio. .

EMeans for solving the problem In order to solve the problem, in the present invention, the core 1
1 is divided into a plurality of core parts AR2 and AR3 having a predetermined cross-sectional area, and the core parts AR2 and AR3 are each wound with a wire, and the winding wires 16 and 17 are connected in parallel.

The F-acting core 11 is divided into a plurality of core parts AR2, A, and R each having a predetermined cross-sectional area.
By dividing the coil into three parts and winding each core portion AR2, AR3, the magnetic flux interlinking with each coil 16, 17 can be reduced by that amount, and a desired output voltage can be obtained.

Furthermore, by connecting the windings 16 and 17 in parallel, it is possible to reduce variations in the output voltage with respect to variations in the output current.

G example An embodiment of the present invention will be described in detail below with reference to the drawings.

(G1) First Embodiment In FIG. 1, 10 indicates a switching transformer as a whole, and a magnetic circuit is constructed using U-shaped cores 11 and 12 having the same shape.

That is, the cores 11 and 12 are combined, and one leg 11A and 12A thereof is wound with 10 turns, thereby forming the primary winding 13.

On the other hand, as shown in FIG. 2, grooves 15 are provided in the remaining legs 11B and 12B of the cores 11 and 12 so as to be exposed on the mating surfaces of the cores 11 and 12, and the legs 11B and 12B are cut off. The groove 15 divides it into two regions (hereinafter referred to as leg portions) AR3 and AR3 having the same area.

The secondary winding of the switching transformer 10 is connected to this leg 1.
Two windings 16 and 17 are formed, which are wound around the portions 1B and 12B and make one turn around each of the leg portions AR2 and AR3.

Therefore, in one winding 16.17 that goes around each leg part AR2 and AR3, cores 11 and 12, respectively.
Let Φ be the magnetic flux induced in the leg parts AR2 and AR
Since the cross-sectional area ratio of 3 is divided into 1:1, it interlinks with the magnetic flux Φ2 of the following formula % formula % (1), and as a result, the leg 1 of the core 11 or 12
1. When a voltage of E [V] is induced in the winding that goes around the entirety of B or 12B, a voltage E2 of the following formula % is induced in each of the windings 16 and 17.

Therefore, the fractional ratio output voltage E2 expressed by equation (2) is
from each winding 16 and 17, which allows the turns ratio to be chosen to be other than an integer ratio to obtain the desired output voltage.

Thus, in this embodiment, the primary winding 13 is selected to have 10 turns, and the primary winding 13 has a diameter of 24.0 (
The secondary windings 16 and 17 are driven to apply a voltage of 12 (V), thereby obtaining an output voltage of 12 (V) from each of the secondary windings 16 and 17.

Further, the windings 16 and 17 of the leg portions AR2 and AR3 are connected in parallel, thereby improving the voltage fluctuation rate of the switching transformer 10.

That is, when the legs 11B and 12B are divided into two to form the leg portions AR2 and AR,3, the magnetic circuit of the switching transformer 10 can be expressed as shown in FIG.

Here, assuming that the number of turns of the primary winding is N and the current of the primary winding is 1, the magnetomotive force F is expressed by the following formula (3), and the magnetic resistance of the leg parts AR2 and AR3 is The magnetic resistance other than R2 and R3 and leg portions AR2 and AR3 is set as R1.

In this case, if an output voltage of 12 (V) is obtained by winding only one of the leg portions AR, 2 or AR, 3, as long as the current flowing through the winding is small, the leg portions AR, 2 The magnetic resistances R2 and R3 of AR3 are maintained at equal resistance values, and the magnetic flux Φ2 passes through the leg portions AR2 and AR3.
are maintained in the relationship expressed by equation (1), whereas as the current flowing through the windings increases, the magnetic resistances R2 and R3
changes to different values, resulting in a significant imbalance in the magnetic flux passing through leg portions AR2 and AR3.

As a result, when only one of the leg portions AR, 2 or A, R3 is wound, the output voltage varies greatly depending on the load impedance connected to the winding (ie, depending on the output current).

Therefore, in this embodiment, by winding both the two leg parts AR2 and AR3 and connecting them in parallel, even if the output current becomes large, the magnetic resistances R2 and R3 of the leg parts AR2 and AR3 have equal resistance. As a result, the magnetic flux passing through each of the leg portions AR2 and AR3 is maintained at a constant value, thereby preventing fluctuations in the output voltage.

Thus, as shown in FIG.
Compared to the case where the wire was wound only on one side (shown by the broken line), the voltage fluctuation rate could be significantly improved.

According to the above configuration, the legs 11B and 12B of the cores 11 and 12 are divided into two equal parts, and the divided leg portions AR2,
By winding the AR3 and connecting the windings 16 and 17 in parallel, it is possible to select the output voltage at a ratio other than an integer ratio to obtain the desired output voltage, and it is also possible to use a switching transformer with a small voltage fluctuation rate. You can get 10.

(G2) Second Embodiment In FIG. 5, coaxial cores 18 and 19 are opposed to each other in place of the U-shaped core to form a magnetic circuit.

That is, as shown in FIG. 6, in the core 18, a cylindrical O leg 22 is arranged at the center of a disc-shaped bottom plate 21, and a cylindrical leg 23 is arranged around the bottom plate 21 coaxially with the side 22. are arranged so that

A winding 25 is provided on the leg 22 so as to turn around a predetermined number of times, and the winding 25 constitutes a part of the primary winding of the switching transformer 30.

On the other hand, large grooves 27 are provided in the surrounding legs 23 at angular intervals of 90 degrees, and the lead wire of the primary winding is drawn out through one of the grooves 27, and the lead wire of the primary winding is drawn out through one of the grooves 27. The entire area 23 is divided into four parts.

On the other hand, as shown in FIG. 7, the core 19 has legs 31 and 32 coaxially formed in the same manner as the core 18, and a groove 33 having the same shape as the groove 27 of the core 18 forms the legs 31 and 32 on the outer peripheral side.
2 is divided into four.

Furthermore, a winding 34 is provided on the inner leg 31 so as to turn around a predetermined number of times, and constitutes a primary winding together with the winding 25 of the core 18.

Thus, as the magnetic flux induced in the legs 22 and 31 by the primary windings 25 and 34 passes through the leg 23 via the bottom plate 21 of the core 18, the magnetic flux is divided into the divided leg portions 23A, 23B,
After passing through 23C123D in parallel, it passes through divided leg portions 32A132B and 32C132D of core 19 in parallel and returns to legs 22 and 31.

Therefore, when the cores 18 and 19 are brought into close contact with each other to form a magnetic circuit, 174 of the magnetic fluxes induced in the central legs 22 and 31 are transferred to each leg portion 23A, 23B, 23C12.
Pass through 3D, 32A, 32B, 32C, and 32D.

In this way, if the windings are made to go around each leg portion 23A, 23B, 23C, 23D and 32A, 32B, 32C132D, 1/4 turn is required for the applied voltage per turn of the primary winding 25.34. It is possible to obtain an induced voltage of

Thus, in this embodiment, among the coaxially arranged core legs 22, 23, 31, 32, the outer leg 23.
By dividing 32 into four parts and winding them, a desired output voltage can be obtained by selecting a winding ratio other than an integer ratio.
Windings 35, 36, 37, and 38 are wound around each of the 3D.

Further, as shown in FIGS. 8 and 9, in the switching transformer, adjacent leg portions 23A and 23
Windings 35 and 36.3 surrounding B, 23C and 23D
7 and 38 are connected in parallel to form a switching transformer for double-wave rectification.

Therefore, even if the output current varies greatly in each winding 35, 36, 37, 38, each winding 35, 36, 37, 38.
37.38 output currents can be held equal, thereby allowing the applied leg portions 23A, 23B, 23C12 of each winding to
The 3D magnetoresistance can be held equal to prevent variations in the output voltage.

According to the configuration shown in FIG. 5, by dividing the outer leg 23 into four parts, winding each leg part 23A, 23B, and 23C123D, and connecting the windings 35, 36, 37, and 38 in parallel, By selecting the turns ratio to a desired ratio other than an integer ratio, a switching transformer with a small voltage fluctuation rate can be obtained.

(G3) Third Embodiment FIG. 10 shows a third embodiment, in which a switching transformer 42 is constructed by using cores 40 and 41 divided into three instead of dividing the outer leg into four. .

That is, in the cores 40 and 41, the primary winding is wound around the center leg, and the lead wire 44 thereof is drawn out from the groove 43.

On the other hand, as shown in FIG.
and windings 50.51.5 on 49.49 and 47 respectively
2 is wound around, thereby winding three secondary windings.

Therefore, in each leg portion 47, 48 and 49, 1/3 of the magnetic flux induced in the central leg passes through each leg, so that in each winding 50, 51 and 52, 2 /3 of the magnetic flux.

Thus, in each of the windings 50, 51 and 52, an induced voltage of 2/3 turns can be obtained with respect to the voltage applied to one turn of the primary winding.

Furthermore, in this embodiment, each winding 50, 51 and 5
2 are connected in parallel so that the magnetic flux passing through the leg portions 47, 48 and 49 provided with the respective windings 50, 51 and 52 will not become non-uniform.

Therefore, each leg portion 47
．． The magnetic resistances of 48 and 49 can be kept at equal values, and fluctuations in the output voltage can be effectively avoided.

According to the configuration shown in FIG. 10, the legs of the core 40, 41 are divided into three parts and the winding is made to go around the two leg parts, so that the voltage is applied to one turn of the primary winding. An output voltage of 2/3 turns can be obtained with respect to the voltage, and thus the turns ratio can be selected to a desired ratio other than an integer ratio to obtain a desired output voltage.

Furthermore, by connecting three windings in parallel, a switching transformer with a small voltage fluctuation rate can be obtained.

(G4) Other Embodiments In the above-mentioned embodiments, a U-shaped core and a coaxial core were used, but the shape of the core is not limited to this, and various shapes such as an EI-shaped core can be used. The core shape can be widely applied.

Furthermore, in the above-mentioned embodiment, the case where the secondary winding is wound around the leg portion has been described, but the present invention is not limited to this.
The primary winding may be wound around the leg portions if necessary.

Furthermore, in the above-described embodiments, a case has been described in which the legs of the core are divided to form leg portions, and wires are wound around the leg portions, but the present invention is not limited to the case where the legs are divided; A rectangular groove can be provided in the middle of the core and the wire can be wound using this groove, or a part of the core that makes up the magnetic circuit can be divided and winding can be carried out on the divided part (hereinafter referred to as the core part). All you have to do is line.

Further, in the above-described embodiments, a case has been described in which the present invention is applied to a switching transformer, but the present invention is not limited to this, and can be widely applied to various transformers such as an input/output quadrangle that inputs and outputs signals, for example.

H Effects of the Invention As described above, according to the present invention, the core is divided into a plurality of core parts each having a predetermined cross-sectional area, each core part is individually wound, and the windings are connected in parallel to increase the number of turns. The ratio can be selected to be other than an integer ratio, and a transformer with a desired output voltage and a small voltage fluctuation rate can be obtained.

Figure 4 is a characteristic curve diagram for explaining its operation, and Figure 5 is a characteristic curve diagram for explaining its operation.
The figure is a perspective view showing the second embodiment, FIGS. 6 and 7 are perspective views showing the shape of the core, FIGS. 8 and 9 are connection diagrams for explaining the operation, and FIG. 1O is a perspective view showing the shape of the core. A perspective view showing the third embodiment, FIG. 11 is a connection diagram for explaining its operation,
FIG. 12 is a connection diagram for explaining the problem.

2.10.42...Switching transformer, 1
1.12.15.18.19.40.41...
Core, 11A, 11B, 12A, 12B, 22.23.
31.32... Legs, AR2, AR3, 23A1
23B, 23C, 23D, 32A, 32B...
Leg part, 13.25.34...Winding, 15.2
7.33...groove.

[Brief explanation of the drawing]

Claims (1)

[Scope of Claims] A transformer characterized in that the core is divided into a plurality of core parts each having a predetermined cross-sectional area, each of the core parts is wound with a wire, and the winding wires are connected in parallel.